NBSIR 83-2786

Technical Activities 1983

Center for Analytical Chemistry

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory

Washington, D.C. 20234

October 1 983

Final

Issued December 1983

Prepared for U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington, D.C. 20234

NBSIR 83-2786

TECHNICAL ACTIVITIES 1983

CENTER FOR ANALYTICAL CHEMISTRY

H. S. Hertz, R. A. Velapoldi, and J. K. Taylor, Editors

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory

Washington, D.C. 20234

October 1983

Final

Issued December 1983

Prepared for U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington, D.C. 20234

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
Certain commercial equipment, instruments, or materials are identified in

this report to specify adequately the experimental procedure. Such

identification does not imply recommendation or endorsement by the National

Bureau of Standards3 nor does it imply that the materials or equipment

identified are necessarily the best available for the purpose.
TABLE OF CONTENTS

Page

I. CENTER FOR ANALYTICAL CHEMISTRY

A. Center Overview 1 B. Voluntary Standardization and Quality Assurance 10

C. Laser Analytical Chemistry Group 13

1. Group Overview 13

2. Selected Technical Reports 14

a. Use of Laser-Enhanced Ionization in Flames for

the Analysis of Standard Reference Materials. ... 14

b. Inclusion of Background Effects in the Computer

Simulation of LEI in Flames 17

3. Outputs and Interactions 20

II. INORGANIC ANALYTICAL RESEARCH DIVISION

A. Division Overview 23

B. Selected Technical Reports 35

1. A New Electrochemical Technique for the Estimation

of Diffusion-Layer Thicknesses at Hydrodynamic

Electrodes 35

2. Determination of Vanadium in Botanical, Biological,

and Environmental SRM's Using High-Sensitivity,

Pulse-Counting Isotope Dilution Thermal Ionization

Mass Spectrometry . 37

3. Ultra trace Determinations of Critical Elements in

Biological Materials Using Improved Radiochemical

Separations 38

4. Material Transport 40

5. Analysis and Stability of Environmental Specimen Bank

Samples 41

6. The Characterization of Metastable Excited State

Atomic Species Produced in Thermal Vaporization Using

Resonance Ionization Mass Spectrometry (RIMS) 44

7. Interferences in the Determination of Germanium Using

Electrothermal Atomization Atomic Absorption

Spectrometry 47

8. Gases-in-Metals Analysis 49

9. The Standard Potential of the Ag/AgCl Electrode for

High Accuracy pH Measurements. 50

10. Resonance Ionization Mass Spectrometry of Iodine and

Carbon 52

11. Thermal Release of Helium from Single Crystal Nickel . . 54

12. Determination of Selenium in Subcellular Fractions to

Study the Glutathione Peroxidase System 57

13. The Measurement of Natural Variation in the 32 S/ 34 S

Ratio in Atmospheric Samples 59

14. Evaluation of the Isotope Dilution Method for

Ultra trace Chromium Concentrations 62

i
Page

15. Ion Optics of Single and Double Stage Mass

Spectrometers 63

16. Development of Reference Materials for Acid Rain

Studies 65

17. The Development of a Pulsed Thermal Atom Source For

Use in RIMS 67

18. Characterization of Biological SRM's Using Atomic

Spectrometry Techniques 69

19. Measurement of Iodine Concentrations and Isotope

Ratios at Environmental Levels 72

20. Certification of Uranium Isotopic Standard Reference

Materials 73

21. Neutron Depth Profiling and the Characterization of

Dopant Distributions 74

22. An Automated Mass Spectrometer--Inlet System for Gas

Analyses 76

23. Potential Limitation in the Use of Thin Metal Films

as Transmittance Standards 78

24. The Effect of Manganese on the Determination of

Sulfur by Optical Emission Spectrometry 80

25. Certification of NBS Buffer Materials 82

26. Standard Reference Materials 83

C. Outputs and Interactions 86

III. ORGANIC ANALYTICAL RESEARCH DIVISION 101

A. Division Overview 101

B. Selected Technical Reports 114

1. Synthesis and Characterization of Chemically Bonded

C 18 Phases for Liquid Chromatography 114

2. Characterization and Comparison of Three Air

Particulate Samples for Polycyclic Aromatic

Hydrocarbon Distributions 119

3. Determination of Chlorinated Pesticide Residues in

Human Liver Specimens for the Pilot Environmental

Specimen Bank Program 124

4. Certification of Selected Organic Compounds in

SRM 1582, Petroleum Crude Oil 127

5. Determination of Relative Isomer Content in SRM 916,

Bilirubin 131

6. Determination of Organic Nutrients in SRM 1549,

Non-Fat Milk Powder 132

7. Use of Polynuclear Aromatic Hydrocarbon Generator

Columns for Calibrating Air Sampling Systems 135

8. Detection of Arson—Analysis of Accelerant Residues

on Soot 137

9. Analysis of EPA Performance-Evaluation Standard

Samples 138

10.

Preparation and Certification of SRM Calibration

Solutions 139
Page

11. Reference Methods for Certification of Seven Enzymes

in SRM 909 142

12. Metal -Ion Affinity Chromatography Supports for

Protein Separation 144

13. Thin-Layer Isoelectric Focusing for Sensitive Protein

Analysis 145

14. Nitrogen-15 NMR Spectrum Editing by the DEPT

Technique 145

15. Two-Dimensional, DEPT Heteronuclear J-Resolved

Carbon-13 NMR Spectroscopy 149

16. Preparation and Analysis of a Quality Assurance

Sludge Material 153

17. Investigation of Desorption Mechanisms in Laser

Desorption and Field Desorption Mass Spectrometry. . . . 155

18. Development of an Isotope Dilution/Mass Spectrometry

Definitive Method for the Determination of Serum

Creatinine 157

19. Two-Dimensional Electrophoresis System Implemented

for Protein Separation and Identification 160

20. Laser Photodissociation of Ions and Reactive

Ion/Molecule Collisions: Instrumentation and

First Results 161

21. Determination of Polynuclear Aromatic Hydrocarbons in

Environmental Samples Using Negative Chemical

Ionization Mass Spectrometry 163

22. Polyethylene Methacrylate Coated Electrodes--Nonaqueous

Solvent-Stable Polymer Film Electrode Modified with

Methyl viologen 166

23. Use of a Zinc Scrubber Column for In-Line Removal of

Oxygen from HPLC Mobile Phases 168

24. High-Performance Liquid Chromatographic Methods for

the Determination of Nitro-Polynuclear Aromatic

Hydrocarbons (N-PAH) in Complex Mixtures 173

25. Spectroelectrochemical Investigations of Cyanine

Dyes , Rutheni urn- ( bi pyri di ne

)

2 di thiocarbamate

Complexes, and Copper Dithiocroconates 179

26. Theoretical Modeling of the Double Step

Chronocoulometry and Spectroelectrochemistry of

Systems with Strong Product Deposition 181

C. Outputs and Interactions 184

IV. GAS AND PARTICULATE SCIENCE DIVISION

A. Division Overview 197

B. Selected Technical Reports 205

1. Cross-Coupled Interaction of Thermal , Electrical,

Mechanical, and Chemical Parameters of

Polymeric Permeation Devices 205

2. Band Strength Measurements of Propane by Fourier

Transform Infrared Spectroscopy 206

iii
Page

3. Sampling and Measurement of Nitrous Oxide, Carbon

Dioxide, and Methane in the Amazon 209

4. Stability Studies of NO in N 2 SRM's 213

5. Evaluation of Degree of Sorption in Collection of

Trace-Organic Vapors on Sorbents 216

6. Round-Robin Assessment of Gas Saturation Test Method

Proposed by EPA for Generating Vapor Pressure Data

on Organic Chemicals 218

7. Development of Techniques for Preparation and

Analysis of ppb Level Toxic Organic Standards 221

8. Pollutant Levels in Non-protected and Protected

National Archival Storage Areas 222

9. Toxic Gases from Lithium Battery Discharges 225

10. Mathematical Chemistry: Design and Evaluation of

the Analytical Measurement Process, Detection Limits,

and Multidimensional Data 227

11. Origins of Carbonaceous Gases and Aerosols: Survey

of Recent Measurement Advances and Results 231

12. Detection of HC1 at the Sub-Parts-Per-Bill ion Level

Using Tunable Diode Laser Absorption 234

13. Completion of Measurements of the Temperature

Dependence of the Ozone Absorption Cross-section

in the Vacuum Ultraviolet 236

14. Reference Ultraviolet Photometer for Ozone Calibration

and Assay 237

15. Completion of the Respirable Quartz SRM 239

16. Use of Monte Carlo Electron Trajectory Simulation for

Basic Studies in Analytical Electron Microscopy 240

17. Visualization of the Three-Dimensional Nature of the

Electron Interaction Volume in Solids 243

18. An Evaluation of X-ray Loss Due to Electron

Backscatter 246

19. Studies of the Depth Distribution of Boron in Glass

by Neutron Depth Profiling and Secondary Ion Mass

Spectrometry 248

20. Detection and Analysis of Organic Monolayers by Laser

Microprobe Mass Analysis 250

21. Standard Reference Material for Analysis of

Asbestos by Electron Microscopy 251

22. Visibility of Asbestos Fibers in the Scanning

Electron Microscope 253

23. An Analytical Algorithm for Calculation of Spectral

Distributions of X-ray Tubes for Quantitative X-ray

Fluorescence Analysis 254

24. Comparison of Theoretical a-Coefficient Fundamental

Parameter Method with NRLXRF for Quantitative X-ray

Analysis 258

25. Final Measurements and NBS Certification of Thin-Glass

Standard Reference Samples for X-ray Spectrometry and

Microanalysis 260

C. Outputs and Interactions 261

iv
I. Center for Analytical Chemistry

Harry S. Hertz, Director

Ranee A. Velapoldi, Deputy Director

A. Center Overview

The Center for Analytical Chemistry develops and maintains the scientific

competences and the experimental facilities necessary to provide the Nation

with the basis for uniform measurements through development of measurement

methodology and standards and provision of measurement services in the field

of analytical chemistry. Analytical measurements provide a foundation for

scientific and technological research and development concerning materials and

their practical application. Moreover, analytical measurements are increasingly used as the basis for industrial, regulatory, and medical decisions.

The Center serves as the National reference laboratory for assuring the

reliability of analytical measurements.

The principal means by which the Center has served as a National reference

laboratory is through the development and issuance of Standard Reference

Materials (SRM's). The ubiquity of and demand for analytical measurements in

modern society is reflected in the diversity of SRM's produced in the Center.

These standards are widely used in such diverse areas as the metal and chemical industries and in clinical and environmental laboratories. Each standard

is supported by research on homogeneity and stability and is certified as to

chemical composition using the most reliable analytical methods available.

Analytical chemistry is increasingly being called upon to provide key

data for highly complex sample types - hazardous chemical and nuclear wastes,

body fluids, plant and animal tissues, foods, and high-technology materials.

Often, analytical values as a function of location within a sample are

needed. As the demands upon analytical chemistry become more sophisticated,

the problem of standardization becomes more challenging both in terms of

the number and the complexity of the proposed standard materials. As it is

not reasonable to contemplate the development of standards to deal with every

measurement problem, the Center's program must be multifaceted, seeking a variety of avenues to influence the quality of analytical measurements made

in the United States. In addition to the issuance of standards, the Center

exerts influence through close contacts with various communities by means of

workshops, symposia, and participation in voluntary standards committees.

Through such contacts, priorities are established for the production of

standards and mechanisms are set in place for their effective use.

NOTE: Certain commercial equipment3 instruments3 or materials are identified in this report to specify adequately the experimental

procedure. Such identification does not imply recommendation or endorsement by the National Bureau of Standards3 not does it

imply that the materials or equipment identified are necessarily

the best available for the purpose.

1
During 1983 and 1984 we are devoting considerable effort in the Center to

better define our user communities and the various mechanisms for interacting

with these communities. This effort is part of the larger issue of better

definition of the role and function of the Center as the National reference

laboratory for analytical chemistry. The matrix on page 3 presents our current

thoughts on this issue and we are now seeking the best implementation mechanisms for our efforts.

Through better definition of the role of the reference laboratory, we intend to clarify opportunities for assuring traceability of analytical mea- surements to national standards. In an era of increased reliance on voluntary

standards it is vital, in our opinion, to assure the integrity of the measurement system through traceability to national standards. In this era, a scientifically accurate measurement base is the best support mechanism for

both the industrial and regulatory sectors of the communities we serve.

The program of the Center strives to achieve a balance among the provision

of currently needed standards and research efforts on new types of standards

and methods of measurement. The work of the Center is performed in three

divisions, each focusing upon specific sample types — inorganics, organics,

and gases and particles. Within each division there are several groups representing separate analytical chemical disciplines, e.g., mass spectrometry and

electrochemistry. One group, the Laser Analytical Chemistry Group, is attached

to the Center office. Each division is responsible for a program in basic and

applied research and maintains contacts with appropriate communities.

In the following, the major recent activities and technical directions of

the divisions and groups mentioned above are given. Much work in progress is

omitted but will be included in subsequent Annual Reports.

1. Outputs and Interactions

a. Publications

Schaffer, R., Sniegoski, L. T., Welch, M. J., White V, E., Cohen, A.,

Hertz, H. S., Mandel , J., Paule, R. C., Svensson, L., Bjorkhem, I., and

Blomstrand, R., Comparison of Two Isotope Dilution/Mass Spectrometric

Methods for the Comparison of Total Cholesterol, Clin. Chem. 28 (1 )

,

5-8 (1982).

May, W. E., Chesler, S. N., Hertz, H. S., and Wise, S. A., Analytical

Standards and Methods for the Determination of Polycyclic Aromatic

Hydrocarbons in Environmental Samples, J. Environ. Anal. Chem. 1^,

259-275 (1982).

White V, E., Welch, M. J., Sun, T. , Sniegoski , L. T., Schaffer, R.

,

Hertz, H. S., and Cohen, A., The Accurate Determination of Serum

Glucose by Isotope Dilution/Mass Spectrometry -- Two Methods,

Biomed. Mass Spectrom. , 395-405 (1982).

2
CAC

ASA

REFERENCE

LABORATORY

IN

NATIONAL

ANALYTICAL

MEASUREMENT/MONITORING

PROGRAMS

3

li
May, W. E., Brown-Thomas , J. M. , Chesler, S. N., Guenther, F. R.,

Hilpert, L. R. , Parris, R. M. , Richie, K. L., Sonnefeld, W. J.,

Wise, S. A., and Hertz, H. S., Interlaboratory Comparisons of Quantitative Analyses of Individual Compounds in Simple and Complex Mixtures,

Oak Ridge Press, in press.

Yap, W. T. , Schaffer, R. , Hertz, H. S. , White V, E. , and Welch, M. J., On the

Difference Between Linear and Non-Linear Models in Bracketing Procedures

in Isotope Dilution/Mass Spectrometry, Biomed. Mass Spectrom. , Vol . 10,

262-264 (1983).

May, W. E. , Chesler, S. N., Hilpert, L. R. , Hertz, H. S. , Rebbert, R. E.

,

Vogt, C. R. , and Wise, S. A., "Characterization of Polycylics Aromatic

Hydrocarbons in Air Particulate Extracts by Liquid and Gas Chromatographic

Methods," "Identification and Analysis of Organic Pollutants in Air,"

L. R. Keith, ed. , Butterworth Publications.

Reimann, C. W. , Velapoldi, R. A., and Taylor, J. K., "Annual Report 1982,

Center for Analytical Chemistry", NBSIR 82-2620.

Reedjik, J. , Siedle, A. R. , Van Hest, J. A. M. , and Velapoldi, R. A.,

Coordination Compounds of Benzotriazole and Related Ligands, Inorg. Chim.

Acta, 1983, in press.

Reimann, C. W. , and Velapoldi, R. A., "Analytical Methods", in Encyclopedia of

Chemical Technology, John Wiley and Sons, N.Y., in press.

Velapoldi, R. A., White, P. A., May, W. E. , and Eberhardt, K. R. , "Spectrofluorimetric Determination of Polycyclic Aromatic Hydrocarbons in Aqueous

Effluents from Generator Columns", Anal. Chem. 55^, 1896 (1983).

Burke, R. W. and Velapoldi, R. A., Collators. ISO Commission on Physiocochemical Measurements and Standards; Recommended Reference Materials for

the Realization of Physicochemical Properties: Wavelength and Transmittance.

ISO Proceedings, August 1983.

Taylor, J. K. , "Validation of Analytical Methods," Anal. Chem. 5!5, 600A-608A

(1983).

Becker, D. A., Used Lube Oil: Hazardous Waste vs. Valuable Resource, Proceedings, Conference on Trace Substances in Environmental Health, XVI,

pp. 22-27.

Becker, D. A., and Hsu, S. M. , NBS Provisional Tests for Re-refined Engine Oil,

Proceedings, Fourth Conference on Measurement & Standards for Recycled

Oil, September 14-16, 1982 (in press).

Becker, D. A., Analysis for PCBs in Oil: The ASTM/NBS Round Robin, Proceedings,

Fourth Conference on Measurement & Standards for Recycled Oil, September

14-16, 1982 (in press).

Weeks, S. J. , Becker, D. A., and Hsu, S. M. , "ASTM/NBS Basestock Consistency

Study Data", NBS Spec. Publ . 661 (1983).

4
Becker, D. , Recycling Oil, Encyclopedia of Chemical Technology, Third Edition,

Volume 19, 1982, pp. 979-985.

Hsu, S. M. , Ku, C. S. , and Becker, D. A., "Re-refined Base Oil Characterization

and Consistency Monitoring," Paper in Base Oils for Automotive Lubricants,

SP-526, pp. 87-104 (Society of Automotive Engineers, 400 Commonwealth Drive,

Warrendale, PA 15096, 1982).

b. Talks

H. S. Hertz, "The Development and Role of Definitive Methods in Clinical

Chemistry" - 31st Annual Conference on Mass Spectrometry and Allied Topics,

Boston, May 6, 1983.

H. S. Hertz, "SRM's and Definitive Methods: Their Roles in Clinical Chemistry",

CAP/American Society for Clinical Pathologists Spring Meeting, Chicago,

April 1983.

C. W. Reimann, "Trends Affecting Analytical Laboratories: Problems and Opportunities" - O'Hara Exposition Center - Rosemont, Illinois.

C. W. Reimann, "Analytical Chemistry in the Materials Sciences", - Johns Hopkins

Hospital, Baltimore, Maryland, December 8, 1982.

C. W. Reimann, "An Assessment of Sciences Precision of Chemical Compositional

Data Used in Support of Toxicology and Nutrition Programs," - National

Academy of Sciences, February 10, 1983.

R. A. Velapoldi, "Review of the Center for Analytical Chemistry", and "Spectrophotometry and Spectrofluorimetry: Standards and Analyses", - State Bureau

of Metrology, National Institute of Metrology, Beijing, China, October

18-19, 1982.

R. A. Velapoldi, Above two seminars at Shanghai Institute for Testing Technology,

Shanghai Bureau of Standardization and Metrology, Shanghai, China,

October 23-24, 1982.

R. A. Velapoldi, "Accurate Measurements and Analytical Chemistry", Guest

Lecturer for Course on Chromatography" by H. McNair at NBS,

April 20, 1983.

R. A. Velapoldi, "Microspectrofluorimetric Measurements and Standards for

Biological/Cytological Research", - Baylor College of Medicine, Houston,

Texas, August 29, 1983.

R. A. Velapoldi, "Microspectrofluorimetry for Petrographic Analysis" - Conoco,

Inc., Ponca City, Oklahoma, August 30, 1983.

J. K. Taylor, "Essential Features of a Laboratory Quality Assurance Program",

ASTM Symposium on Statistics in the Environmental Sciences, Philadelphia,

Pennsylvania, October 7, 1983.

5
J. K. Taylor, "Quality Assurance of Chemical Measurements", EPA Region VII,

Kansas City, MO, October 25-26, 1983.

J. K. Taylor, Quality Assurance Workshop - ADABSE Meeting, NBS, October 28,

1983.

J. K. Taylor, "Quality Assurance of Chemical Measurements", California

Department of Health, Berkeley, California, February 14-15, 1983.

J. K. Taylor, "Quality Assurance of Chemical Measurements", California

Department of Health, Los Angeles, California, February 17-13, 1983.

J. K. Taylor, "Quality Assurance of Chemical Measurements", ACS Short Course,

Pittsburgh Conference, Atlantic City, New Jersey, March 4-5, 1983.

J. K. Taylor, "Quality Assurance of Chemical Measurements", Army Environmental

Hygiene Agency, Edgewood, Maryland, March 28-29 and 30-31, 1983.

J. K. Taylor, "An Adequate Quality Assurance Program - The Prerequisits for

Reliable Data", ACS MARM, White House, Pennsylvania, April 6, 1983.

J. K. Taylor, "Quality Assurance of Chemical Measurements", Ford Motor Co.,

Dearborn, Michigan, April 11-12, 1983.

J. K. Taylor, "How to Conduct a Collaboration Test of a Method", ASTM D-22

Meeting, Louisville, Kentucky, April 20, 1983.

J. K. Taylor, "Overview of Quality Assurance", FSDA Seminar, Rockville,

Maryland, April 21, 1983.

J. K. Taylor, "Quality Assurance of Chemical Measurements, NBS, May 3-4,

May 12-13, and May 17-18, 1983.

J. K. Taylor, "Quality Assurance of Chemical Measurements", Standard Oil Company

of Ohio, Cleveland, Ohio, May 18, 1983.

J. K. Taylor, "Quality Assurance for the Laboratory", Maryland Department of

Health, Baltimore, Maryland, May 24, 1983.

J. K. Taylor, "Quality Assurance of Chemical Measurements", Chemical Institute

of Canada, University of Alberta, Edmonston, Alberta, Canada, July 8-9,

1983.

J. K. Taylor, "What is Quality Assurance?", ASTM Conference on Quality Assurance

of Environmental Measurements, Boulder, Colorado, August 8, 1983.

J. K. Taylor, "Quality Assurance, Evaluating Analytical Methodology and

Laboratory Performance", FSDA, New York Regional Laboratory, Brooklyn,

New York, August 25, 1983.

6
J. K. Taylor, "Quality Assurance of Chemical Measurements", ACS Short Course,

ACS Meeting, Washington, D.C., August 29-30, 1983.

J. K. Taylor, "Interpretation of Collaboration Test Results", ACS Meeting,

Washington, D.C., September 1, 1983.

c. Committee Assignments

Harry S. Hertz

Secretary, American Society for Mass Spectrometry

Chairman, ASMS, Committee on Education

Member, ASTM, Committee D19 on Water

Member, CEQ, Interagency Task Force on Environmental Data and Monitoring

Air Pollution Data and Monitoring Working Group, Task Group in

Anticipatory Monitoring

Secretary, NCCLS

Technical Advisor, OIML, SP26, Subcommittee SR5 on Reference Materials

for Calibration of Instruments Meant for Checking Substances During

Medico-Biological and Research Analyses

Curt W. Reimann

Chairman, Regulatory Affairs Committee, American Chemical Society

Member, Instrumentation Advisory Panel, ANALYTICAL CHEMISTRY

Co-Chairman, Symposium on Improving the Analytical Chemistry/Regulatory

Interface

Member, Project Group on Quality Assurance, Interagency Task Force

on Environmental Cancer and Heart and Lung Disease

Advisor, Food Chemicals Codex

Member, Analytical Laboratory Managers Association

Ranee A. Velapoldi

Member, Interagency Toxic Substances Data Committee

Working Advisor, ASTM, Committee E7 on Nondestructive Testing,

Subcomni ttee E7.03 on Liquid Penetrant and MPI Methods, Task

Group E7.03.03 on E-270 Glossary Revision

Member, ASTM, Committee E13 on Molecular Spectroscopy, Subcommittee

E13.06 on Molecular Luminescence

Task Group El 3. 06. 01 on Presentation of Corrected

Fluorescence Spectra

Task Group El 3. 06. 02 on Recommended Practices on Molecular

Fluorescence Spectroscopy

7
John K. Taylor

Member, IS0/TC48, Laboratory Glassware and Related Apparatus

IS0/TC48/SC1 , Volumetric Glassware

IS0/TC146, Air Quality

IS0/TC146/SC3, Ambient Measurements

ANSI TAG, I SO/TCI 72 , Optical Instruments

ASTM D19, Water

Chairman, ASTM D1 9 . 01 ,07 , International Standards

ASTM D19.05, Inorganic Constituents

ASTM D19.07, Sediments

ASTM D22, Atmospheric Analysis

ASTM D22.04, Workplace Atmospheres

ASTM 22.01, Quality Control

Member ASTM D22.09, USTAG to TC 146

ASTM E34, Occupational Safety and Health

ASTM E36, Criteria for the Evaluation of Testing & Inspection

Laboratories

ASTM E41 , Laboratory Apparatus

ASTM E41.01, Glass and Plastic Apparatus

ASTM E41.06, Weighing Devices

ASTM E41.07, Microchemical Apparatus

Collaborative Testing Subcommittee - Standard Methods

Advisory Committee - CHEMTECH (ACS)

ACS Committee on Environmental Chemistry - Subcommittee on Environmental Analytical Chemistry

NBS Museum Committee

NBS Performance Review Board, SES

NBS Representative - Interagency Advisory Committee on Water Data

Donald A. Becker

Member, ASTM, Committee D-2, Petroleum Products and Lubricants

Subcommittees B, C, E, L, N, and P

d. Center Colloquium Series

October 13, 1982 Dr. Thomas L. Isenhour, University of

North Carolina, National Science Foundation,

Chapel Hill, NC, "Computer Interpretation

of Analytical Data with Examples from

GC/FTIR."

November 10, 1982 Dr. Phillip D. LaFleur, Eastman Kodak

Company, Rochester, New York, "Analytical

Chemistry at Kodak Research Laboratories."

December 8, 1982 Dr. Kenneth A. Rahn, Center for Atmospheric

Chemistry Studies, University of Rhode Island,

Narragansett, RI, "Is the Midwest Really the

Source of Northeastern Acidic Aerosol? New

Evidence from Elemental Tracers."

8
February 23, 1983 Dr. Nan Newell, Office of Technology

Assessment, U.S. Congress, "The Future of

Biotechnology."

March 16, 1983 Dr. Robert J. Chari son. Department of Civil

Engineering and Institute for Environmental

Studies, The University of Washington, Seattle,

WA, "Factors Controlling the Acidity of Natural

Rainwater.

March 23, 1983 Dr. Shier Berman, National Research Council

of Canada, Ottawa, Canada, "The Development

of Reference Materials for Marine Chemistry."

April 13, 1983 Dr. Karlheinz Ballschmiter, Department of

Analytical Chemistry, University of Ulm,

Ulm, F.R. Germany, "Studies of the Global

Baseline Pollution: A Challenge in Organic

Trace Analysis."

May 4, 1983 Dr. Jaromir Ruzicka, The Technical University

of Denmark, Lyngby, Denmark, "From a Test Tube

to Integrated Microconduits: A New Concept of

Solution Handling Based on Flow Injected Analysis."

May 11, 1983 Dr. Robert J. Huggett, Virginia Institute of

Marine Sciences, College of William and Mary,

Gloucester Point, VA, "Chemical and Biological

Studies of an Estuary Highly Contaminated by

Polynuclear Aromatic Hydrocarbons."

June 10, 1983 Dr. Michael E. Lipschutz, Department of

Chemistry, Purdue University, West Lafayette,

IN, "Thermal History of Solar Systems Objects

as Revealed by Trace Elements."

9
B. Voluntary Standardization and Quality Assurance

1. Voluntary Standardization

The availability of carefully evaluated methods, standardized by the consensus of knowledgeable analysts is recognized as an essential component

of the quality assurance of chemical measurements. Where such methods are closely related to standard reference materials and to appropriate quality

assurance programs, a high quality of data is possible. Closely related to

this is the requirement for evaluated and standardized analytical data.

Accordingly, the Center has played and continues to play an active role

in the voluntary standardization process, both nationally and internationally.

More than one-third of the staff engages in some aspect of this activity and

leadership is provided in the following important standardization committees

and organizations:

Altogether the Center is represented on more than one hundred separate

committees, and task groups of various standardization organizations. Such

activity provides the opportunity for direct transfer of Center technology to

a wide range of constituency. The contacts made at meetings of such organizations provide valuable input into the long-range planning of the Center.

The Center specifically interacted with the standardization community

during the past year in the co-sponsoring of a Conference on the Quality

Assurance of Environmental Measurements, in cooperation with ASTM and EPA.

This conference, held at the University of Colorado, Boulder, CO, during the

week of August 8-12, 1983, was attended by 140 persons. The coordinator was co-chairman and presented the opening address at the conference.

2. Quality Assurance

To further the quality assurance program of the Center, a pilot quality

circle was established in cooperation with the Organic Analytical Research

Division. A quality circle consists of a group of people engaged in similar

activities who meet periodically to discuss a broad scope of subjects relating

to quality measurements. The group consisted of the group leaders of the

Division and the Division Chief and his Deputy. The Center Quality Assurance

Coordinator organized the circle and provided initial leadership. The group was joined at times by a statistician who has been responsible for analyzing

much of the SRM data produced by that Division.

ASTM C-26

ASTM D-19

ASTM D-22

ASTM E-02

ASTM E-07

I S0/TC1 46

I S0/TC1 47

IUPAC

NCCLS

Nuclear Fuel Cycle

Water

Sampling and Analysis of Atmospheres

Emission Spectroscopy

Nondestructive Testing

Air Quality

Water Quality

Commission on Atomic Weights

National Committee for Clinical Laboratory

Standards

10
The circle initially renewed basic statistical concepts and how they

relate to evaluating the uncertainties of organic analytical data. The scope

then changed to the consideration of measurement uncertainties in SRM's

previously certified or presently being analyzed by the group. This has led

to a general consideration of sources of error in organic analysis. The

circle is continuing to operate largely under its own leadership with invitation of technical consultants as pertinent.

In the previous year, a generic quality assurance plan was developed in

cooperation with the Office of Standard Reference Materials for the certification of SRM's. The plan formalizes the procedures that have evolved and have

been followed over a long period of time. Its major features include a strong

emphasis on planning the experimental work and an improved system for

documenting all aspects of the certification process.

In order to test the plan, prior to its general use, three pilot projects

were initiated, one in each of the Divisions. The subjects include the

certification of uranium isotopic abundance standards, a mixed p-aminobenzoic

acid - phenacetin standard, and calibrated permeation tubes. Tne considerable

differences in the individual material were believed to provide a good test

of the QA plan. All of the projects are now in an advanced stage and their

progress has been periodically appraised on the basis of their amenability to

the requirements of the QA plan. No problems have been experienced and the

practicality of the plan has thus been established. In light of the favorable

experience the plan is expected to be generally applied in future SRM

certification.

The Center continues to assist others in their quality assurance efforts.

The 2-day seminar, "Quality Assurance of Chemical Measurement", was presented

three times at NBS to a total of 140 persons. In addition it was presented on two occasions to the Army Environmental Hygiene Agency, to EPA Region VII,

and on separate occasions to two F&DA field laboratories. Cooperation has

been established with the American Chemical Society in presenting it as a short course which has been done twice in the past year.

The Center continues its interest in cooperating with state laboratories.

Assistance has been provided to the NBS Office of Weights and Measures in the

development and implementation of a Plan for Certifying the Capability of

State Metrology Laboratories. A handbook on good measurement practices for

such laboratories is under development. In the chemical area, the quality

assurance seminar was presented to analytical chemists of the state of

California in Berkeley and again in Los Angeles. A much abbreviated

introductory version was presented to the environmental laboratory of the

state of Maryland in Baltimore and this is expected to be extended in the

future.

The Center is participating in a part-time research associate program

with the Ford Motor Company. The project is concerned with investigating the

merits of several approaches to quality assurance in a diversified industrial

laboratory. In connection with this program, the quality assurance seminar

was presented at the Ford Central Laboratory Seminar to their personnel.

11
In recognition of quality assurance as the central theme of much of the

Center's external program, the Center Director has made a number of contacts,

especially with other government groups. As a result of this, it is expected

to develop a generic quality assurance plan during the coming year for a marine environmental monitoring program involving some five other agencies.

In cooperation with the NBS Office of Standard Reference Materials, a handbook for SRM users has been planned and has advanced to the writing stage.

The handbook is based on the premise that a better understanding of SRM's and

their role in the chemical measurement process will improve the quality of

analytical data. It will attempt to answer many of the questions raised by users of SRM's and provide guidance on the use of SRM's in specific measurement problems.

John K. Taylor

12
C. Laser Analytical Chemistry Group

1. Group Overview

The main long-term objective of this group is to develop new approaches

to performing accurate chemical analysis. Current emphasis is on the use of

lasers as spectroscopic probes. This emphasis remains strong, particularly

as a result of our collaboration with the Mass Spectrometry Groups. However,

a gradual shift toward the study of the material transport process is occurring

as described below.

We have completed the theoretical understanding of the point charge model

of laser enhanced ionization (LEI) in flames, and much has been learned in

this last year's completed study of the finite differences numerical model.

We have mapped the time dependent field effects in one dimension and results

show that the spatial shape of the electric field is an important parameter for

assuring accurate analyses. This model shows that differences in field distribution between the anode and cathode can adversely affect the accuracy of an analytical result for the pulsed laser mode of excitation but not for the CW

mode. Unfortunately, the necessary photon flux cannot be generated in the CW

mode. The next best approach is to use a kHz pulse rate laser with adequate

peak flux which simulates CW operation for the aspirated flame. Our plans for

FY 84 include demonstrating this effect using a recently acquired copper vapor

laser. We will continue our theoretical studies by using the existing mathematical model to evaluate new settings of the various experimental variables.

Our effort continues in establishing the accuracy of LEI by analyzing

elements in existing Standard Reference Materials and applying LEI to the

analysis of complex samples, some of which will become SRM's. In some cases

it is necessary to remove elements that ionize easily in the flame; this was done by developing an ion exchange separation in collaboration with the

Inorganic Mass Spectrometry Group. This year, in addition to analyzing more

samples, we will be studying sources of variability in the measurement process.

We will also incorporate a wavelength meter into the computer controlled system

so that desired optical transitions can be accessed more easily.

Since most atomic spectroscopies best utilize atoms in the vapor phase,

it would be considered useful if methods could be devised to transport atoms

from the solid or liquid phase directly into the vapor without compositional

bias. Spark erosion or laser ablation may do this, but studies to date are incomplete with respect to compositional bias during the transport step.

Careful and detailed long term research must be devoted to this subject. The

payoff is extremely high if such a method of unbiased atomic transport can be

designed since the result could be matrix independent accurate analysis by

many spectroscopic techniques with concomitant decrease in the need for matched

matrices of standards to samples. This year we will investigate the plasma

physics in the DC spark and laser ablation processes to evaluate various experimental designs. In addition, we will continue to study the relationship of

chemical composition to size of the particulate matter in these processes by

using microprobe and conventional analytical techniques on size-separated

particles.

13
We were pleased to have Professor F. E. Lytle with us on a six month

sabbatical. His interaction with the Inorganic Mass Spectrometry Group on the Resonance Ionization Mass Spectrometry (RIMS) project as well as others

proved to be most beneficial.

We continue to collaborate strongly with many groups in the Center:

Inorganic Analytical Research Division - Mass Spectrometry Group on RIMS and

on ion separation techniques; Atomic Spectroscopy Group on spark material

transport; Organic Analytical Research Division - Mass Spectrometry Group on laser photofragmentation; and the Gas and Particulate Science Division —

Microanalysis Research Group on material transport particle analysis; Gas

Metrology Group on the analysis of nitrogen dioxide with the IR diode laser;

Atmospheric Chemistry Research Group on HC1 analysis with the IR diode laser,

material transport particle classification, and the designs of signal processing of carbon-14 detectors. Summaries of these collaborations can be found

in the Divisions' sections of this report.

2. Selected Technical Reports

a. Use of Laser-Enhanced Ionization in Flames for the Analysis of Standard

Reference Materials (11310)

G. C. Turk and H. M. Kingston (551)

Performance evaluation of laser-enhanced ionization (LEI) spectrometry

for trace metal analysis has continued with the application of the technique

to the analysis of standard reference materials. Fuel Oil (SRM 1634a), Incoloy

and Inconel Specialty Alloys (SRM's 1244-1247), and Trace Elements in Water

(SRM 1643a, b) are among the samples which have been analyzed using LEI.

The incoloy and inconels are specialty alloys with high Ni , Fe, and Cr

contents. Because of the complex spectral background resulting from the major

elements, the determination of trace elements using conventional optical

methods can be difficult. The high sensitivity and double-resonance selectivity

of stepwise excitation LEI can be useful for accurate analysis of trace metals

in these samples. We have demonstrated this with the determination of Co in

the proposed series of incoloy and inconel SRM's.

Laser excitation of Co was done in a stepwise manner, with one laser at

252.14 nm exciting the atom to an intermediate level, and a second laser at

591.68 nm further exciting the atom from the intermediate level to within one

eV of the ionization potential of Co, where efficient colli si onal ionization

in the flame occurs. A 170-fold sensitivity enhancement is realized through

the use of the stepwise excitation method rather than with the first step wavelength alone. Figure 1 shows a LEI wavelength scan taken while aspirating a solution of SRM 1244 inconel into the air-acetylene flame. The solution was prepared from an acid digestion of a 1 gram sample diluted to 2 L with distilled

water. The scan was taken with the second step wavelength fixed and the first

step wavelength scanned in the vicinity of the Co first step line. Note the

comparable level of the Co signal, which is enhanced by stepwise excitation,

to the nearby single photon lines from Fe, which is present at approximately

14
LEI

Wavelength (nm)

Figure 1. LEI spectral scan taken while aspirating lg/2L solution of inconel

SRM 1244. A second step laser wavelength is fixed at 591.68 nm,

which enhances Co signal at 252.14 nm by a factor of 170.

160 times the Co concentration. Listed below are the average results obtained

from three replicate measurements each of two independent sample preparations

for each SRM in the series. Also included is the average result obtained for

SRM 1289 high alloy steel, which was used as a quality control standard.

Table 1. Cobalt in Incoloy and Inconel Alloys.

Standard Deviation

SRM Co (yg/g) of Average

1244 613 6

1245 738 7

1246 745 12

1247 915 8

1289 345 (350 ± 40)

a

2

Certified value.

15
Six trace elements were determined in Trace Elements in Water, SRM 1643a

(previously certified) and the renewal SRM 1643b (being certified). Work with

these samples was hampered by broadband spectral background interferences

caused by alkali and alkaline earth elements present in the sample. Because

of the extremely high sensitivity of the low ionization potential elements to

single photon LEI and their excess concentration relative to the trace metals,

broadband signals from the Lorentzian "wings" of strong absorption lines are observed several nm from the line center. The noise associated with these

signals can substantially raise the limit of detection. In addition, the

alkaline earth elements can give rise to broadband molecular LEI signals. For

these reasons, it was necessary to remove alkali and alkaline earth elements

from the sample, using a procedure designed for such purpose based on the use of Chelex-100 chelating resin. Figure 2 shows how effectively this procedure works for LEI determination of Co in SRM 1643b. The interference in this case is particularly severe, as is seen in the top trace of the figure, taken

while aspirating the untreated sample. The background signal observed is from

the wings of the Na D lines, 2.7 nm away from the Co second step excitation

line. The level of Na present in the sample is approximately 200 times greater

than that of Co, and the Co signal is completely lost in the noise of the Na

background interference. The lower trace was taken after removal of the alkali

and alkaline earth elements, and the signal from the 26 ng/g of Co in the

sample is easily discerned. Varying degrees of broadband spectral interferences were observed for all of the six elements studied, with all being removed

by the Chelex-100 procedure. The table below summarizes the results obtained.

Table 2. Analysis of Trace Elements in Water SRM's Using LEI

Flame Spectrometry.

Element Average

3

SRM 1643a

Certified Value Average*

5 SRM 1643b

Std. Dev. i

Cd 10.2 10 ± 1 20.0 0.2

Co 20.5 19 ± 2 26.0 0.1

Cu 17.8 18 ± 2 21.8 0.1

Mn 31.0 31 ± 2 30.1 0.3

Ni 52.3 55 ± 3 46.6 0.2

Pb 26.9 27 ± 1 23.9 0.3

a0f 2 samples prepared.

^0f 7 samples prepared.

16
Figure 2. Stepwise excitation LEI signal for 26 ng/g of Co in water SRM 1643b

before and after removal of alkali and alkaline earth elements by

Chelex-100 procedure. Ten-fold scale expansion of Co signal in the

treated sample is also shown. First step wavelength is scanned with

second step wavelength fixed at 591.68 nm.

b. Inclusion of Background Effects in the Computer Simulation of LEI in

Flames (11310)

J. C. Travis, J. Wen, and P. K. Schenck (561)

In last year's report, we described a computer simulation of charge

transport and current detection following pulsed LEI in flames (NBSIR 82-2620,

section 2. a). In the model described, a fixed number of ions and electrons

was deposited at time zero at a given spatial coordinate. The electrically

perturbed flame in which these charges were deposited was simulated by a predicted electric field distribution and appropriate electron and ion mobilities.

The sophistication of the simulation has since been considerably increased by

computing the background flame conditions (electron and ion denisities and the

electric field distribution) from first principles, and permitting the background to respond to the perturbation of the laser-added charges.

17
Figure 3 shows a typical background calculation for a simulated airacetylene flame between infinite plane parallel electrodes spaced at 2.0 cm

at a potential difference of 1500 V. Because electrons move 100-1000 times

faster than atomic ions in response to an electric field, a positive ion

excess, or space-charge, accumulates near the cathode at steady-state, as shown. This charge results in an electric field gradient, such that the

electric field may actually fall to zero in the flame, as shown, for certain

combinations of background ionization rate, applied potential, and electrode

spacing.

o

Figure 3. Calculated ion and electron densities and electric field in a simulated C2 H2 /air flame between infinite parallel plate

electrodes separated by 2 cm and biased at a potential

difference of 1500 V.

18
Figure 4 shows the perturbations resulting to the ion and electron

densities 40 ns after the deposition of 3 x 10^ ions and electrons per cm3 over

a width of 0.1 cm by an LEI event centered 0.5 cm from the cathode (x=0). The

number densities shown are differences between those calculated following laser

perturbation and the steady-state background populations of figure 3. The field

is plotted in the same manner as figure 3, but the perturbation in field due to

the laser-produced charges is evident in figure 4 at this level of added charge.

The negative-going peak in the electron perturbation curve constitutes a very

important proof of a concept that we had advanced previously on the basis of

empirical evidence: that the portion of the flame not perturbed by the electric

field behaves as a conductor, making the interface between the field-perturbed

"sheath" and the field-free region act as a virtual anode. The negative peak

corresponds to the image charge that would be induced in a solid conductor by

the free charge (positive peak) in the flame.

o

o

Figure 4. Perturbations to the electron and ion densities and to the electric

field of figure 3 40-ns after the deposition of 3 x 109 ions and

electrons in a 0.1 mm wide region centered at 0.5 cm from the

cathode.

19
Inclusion of the background conditions in the model calculations has

provided an improved understanding of the role of sample matrices in perturbing

the background, and with it, the LEI signal. Further additions to the model are expected to include flame convection and temperature variation with

position.

3. Outputs and Interactions

a. Pub! i cations

Travis, J. C. , "Limits to Sensitivity in Laser Enhanced Ionization," J. Chem.

Ed., 59, 909-914 (1982).

Havrilla, G. J., Weeks, S. J., and Travis, J. C., "Continuous Wave Excitation

in Laser-Enhanced Ionization Spectrometry," Anal. Chem., 54, 2566-2570

(1982).

Fassett, J. D. , Travis, J. C., Moore, L. J., and Lytle, F. E., "Atomic Ion

Formation and Measurement with Resonance Ionization Mass Spectrometry,"

Anal. Chem., 55, 765-770 (1983).

Travis, J. C., Turk, G. C., and DeVoe, J. R. , "Trace Metal Analysis by

Laser-Enhanced Ionization in Flames," Clinical Chemistry, Sept. 1983.

Maki , A. G. and Sams, R. L. , "Diode Laser Spectra of cis-HONO near 850 cm” 1 and trans-HONO near 1700 cm” 1 ," J. Mol. Struct, (submitted 1983).

Kagann, R. H., Elkins, J. W., and Sams, R. L., "Absolute Band Strengths of

Halocarbons F-ll and F-12 in the 8- to 16-ym Region," J. Geophys. Res.,

88(c2)

,

1427-1432 (1983).

b. Talks

Travis, J. C., "Trace Element Analysis Using Laser-Enhanced Ionization in

Flames," Stauffer Chemical Co., Dabbs Ferry, N.Y., Feb. 16, 1983.

Travis, J. C., Turk, G. C. , and DeVoe, J. R. , "Trace Metal Analysis by Laser

Enhanced Ionization in Flames," 15th Annual Symposium on Advanced

Analytical Concepts for the Clinical Laboratory, Gatlinburg, Tenn.,

April 22, 1983.

Travis, J. C., "Studies in Selective Ionization for Inorganic Analysis,"

Gordon Conference on Analytical Chemistry, New Hampton, N.H., August 18,

1983.

Moore, L. J., Fassett, J. D., Travis, J. C., Lucatorto, T. B. and Clark, C. W.

,

"Isotopic Selectivity in Ultrasensitive Resonance Ionization Mass

Spectrometry," 27th Annual SPIE Technical Symposium, San Diego, Calif.,

August 23, 1983.

20
Travis, J. C. "Selective Laser Ionization for Trace Element Analysis," 30th

Annual Conference of the Spectroscopy Society of Canada, Vancouver,

B.C., Canada, Oct. 6-8, 1983.

G. C. Turk, C. J. Havrilla, P. K. Schenck, and J. C. Travis, "Laser-Enhanced

Ionization Spectrometry for Trace Metal Analysis," IX FACSS, Philadelphia

Pa., Sept. 21, 1982. Invited

G. C. Turk, "Laser-Enhanced Ionization Spectrometry," Chemistry Department

Seminar, University of Bari, Bari, Italy, June 15, 1983. Invited

G. C. Turk, J. C. Travis, and J. R. DeVoe, "Laser-Enhanced Ionization

Spectrometry for Trace Metal Analysis," C.N.R.S. International

Colloquium on Optogalvanic Spectroscopy and Its Applications, Aussois,

France, June 23, 1983. Invited

G. C. Turk, J. C. Travis, and J. R. DeVoe, "Trace Metal Analysis by LaserEnhanced Ionization Spectrometry," 23rd Colloquium Spectroscopicum

Internationale, Amsterdam, The Netherlands, July 1, 1983.

21

II. Inorganic Analytical Research Division

Ernest L. Garner, Chief

Barry I. Diamondstone, Deputy Chief

A. Division Overview

The Inorganic Analytical Research Division conducts research, develops

analytical methods, and makes qualitative and quantitative measurements of

inorganic constituents, to certify standards and to provide analytical services

in support of national needs. To accomplish its mission, the Division is

organized into four research groups which function along competence lines.

The four groups are: Activation Analysis, Atomic and Molecular Spectrometry,

Electroanalytical Chemistry, and Analytical Mass Spectrometry. This structure

provides the flexibility to address a wide variety of research and analytical

problems requiring highly sensitive and highly accurate measurements. Working

within a framework of providing maximum public benefit, research and measurement

priorities are established on the basis of: (1) advancing and maintaining

analytical chemical metrology; (2) providing the basis for chemical standardization; and (3) providing accurate chemical measurements for materials

characterization.

As in recent years, the scientific program of the Division is diversified

and supports a number of areas that have clearly identified a need for accurate

baseline data. The level of activity and its cross-cutting nature are reflected

by an impressive list of Standard Reference Materials that have been analyzed

for certification, an extensive list of publications and talks, and a large

number of interactions with industrial and academic laboratories. Guest

workers (8), visiting scientists (10), postdoctorals (2), and IPA's (1) have

spent all or part of the year in varying degrees of involvement in mainstream

research and measurements and have made significant contributions to the success of our program.

Competence research, a cornerstone of our research program and a primary

means of exploring new directions in analytical chemistry, has resulted in

major breakthroughs in neutron depth profiling and ionization mechanisms

research. These advances in programs initiated 2-3 years ago represent substantial gains in terms of moving research from the conceptual stage to the point

of exploiting research results for their potential new measurement capabilities.

Most of the recent developments in neutron depth profiling and ionization

mechanisms are described in greater detail in the Group overviews and technical

accomplishments of this report. Particularly noteworthy are the research

findings in neutron depth profiling during the first full year of use as a measurement tool. During this period, a radioactive nuclide ( 22 Na) was profiled

for the first time and 3 He, 6 Li, and 10 B were quantitatively profiled in a variety of semi-conductor materials. These achievements by a team composed of

research chemists from the Activation Analysis Group, a postdoctoral scientist,

a research associate from industry, and a university researcher are an excellent

example of collaborative investigations into research and process problems of

interest to government, industry, and universities.

23
Equally important in terms of impact on future measurement capability are

the findings in ionization mechanisms research. From this program, resonance

ionization mass spectrometry has emerged as a powerful analytical tool with

increased selectivity and sensitivity for all groups of elements in the periodic

table. Among numerous significant accomplishments was a demonstration of a three-photon process to ionize carbon and iodine. This achievement opens the

door to a new approach for ionizing and analyzing elements on the right hand

side of the periodic table which are sensitive indicators in environmental

monitoring programs. Along with the successful utilization of a multi -photon

ionization process, parallel developments in resonance ionization, including

multielement isotope dilution, isotope ratio quantitation, and high resolution

sub-doppler resonance ionization, leads towards new horizons in analytical mass spectrometry.

Continuing research in material transport and hydrodynamic modulation of

electrodes has reached a point where analytical applications could begin in

the near future. Results in these forward-looking areas of research, along

with research to upgrade or develop new methods for existing instrumentation,

will enhance the overall measurement capability of the Division. This is

illustrated by the various components of methods research underway in a number

of problem oriented areas for the Standard Reference Materials Program, the

Recycled Oil Program, and the Nondestructive Evaluation Program. As an example,

the recently equipped laboratory for gases-in-metals measurements has made

substantial progress in developing methods for the analysis of oxygen, nitrogen,

and hydrogen in selected metals. This technology will be utilized extensively

to update existing standards as well as to certify new high technology materials

as standards. Similarly, methods research in gas isotope dilution, spectrophotometry, trace elements in complex matrices, fluoride analysis, and pH are expected to pay dividends at a later time when specific measurements are required.

The commitment to the certification of SRM's has remained at a high level.

Coverage has been extensive in terms of material types, categories, and numbers

of different standards analyzed. The highlights in this area are described in

Group overviews and technical reports. A Division-wide effort has been in

progress this year to determine high priority trace elements in three new SRM's;

Powdered Milk, Urine, and Human Serum* These materials along with future SRM's,

such as clay, soil, and plastic, will provide important new standards to meet

well identified measurement needs. Along with measurement services for the

Standard Reference Materials Program, significant contributions were made to

the quality assurance efforts of other government agencies. These include the

analysis of audit samples, preparation and evaluation of materials for use as standards, isotopic tracer studies for acid rain, and the analysis of a variety

of materials for trace elements.

New opportunities for research and analytical services are constantly

being explored as a means of coupling base programs to the needs of other

government agencies. Some progress has been made with the submission of major

proposals for nutritional studies and bioavailability of trace elements, direct

solid sampling using laser mass spectrometry, and isotope tracer studies for

receptor modeling in acid rain. In conjunction with this outreach program to

couple NBS efforts with those of other agencies, considerable attention has

been given to maintaining and expanding our broad-based constituency. Among

24
the most successful efforts during the year are the research collaborations

developed in the competence area for neutron depth profiling and resonance

ionization mass spectrometry. These efforts will continue with a high level

of commitment.

For the coming year a nearly equal effort is anticipated in research,

certification of standards, and analytical support for problems of national

importance. Exclusive of other agency commitments, only modest changes are anticipated in current directions of base programs. For example, a minor

reprogramming effort will be utilized to initiate research in high resolution

chromatography. Predictably, the other agency situation is quite fluid and

will be structured to provide the best match between base effort and the needs

of the requesting agencies. The commitment to the certification of SRM's will

remain constant and at a very high level of activity.

1 . Activation Analysis Group: Overview

The Activation Analysis Group has as its objective basic and applied

research to develop nuclear analytical techniques for increased sensitivity,

better selectivity, and higher accuracy. A high level of competence has been

developed for various reactor-based activation analysis techniques which

include instrumental and radiochemical neutron activation analysis (INAA and

RNAA), prompt gamma activation analysis (PGAA), and the nuclear track technique

(NTT). The three year research program in elemental depth profiling has added

the technique of thermal neutron beam depth profiling (NDP) to the scope of

reactor based analytical activities. Non-reactor-based techniques include

photon activation analysis (PAA), fast neutron activation analysis, and charged

particle activation analysis, have been used on a more limited scale. These

various techniques provide sensitive tools for fulfilling the needs of analytical chemistry in various branches of science and technology. Depending on the

analytical requirements, simultaneous instrumental multielement determinations,

highly selective radiochemical analysis of ultratraces, and quantitative depth

profiles are available to certify standards, support other government agencies,

and collaborate with academic and industrial laboratories.

Basic research and development in depth profiling have progressed to the

point of yielding quantitative measurements. This facility is a unique

resource in the U.S. which is needed for investigations of the important near- surface region of semiconductors and glasses, first wall fusion materials, and

ion implantation processes. The facility is the focal point for coordinated

research involving several research associates and guest workers from industry,

government R&D agencies, and universities. Quantitatively depth profiling

boron in semiconductor materials has been a significant accomplishment of the

past year. The data from these depth profiles have been in excellent agreement

with determinations done by secondary ion mass spectrometry and are necessary

to evaluate the performance of electronic devices. The recent expansion of

NDP to other elements has contributed to the understanding of the behavior of

helium in metals, and has resulted in depth profiles for sodium ( 22 Na) to

study its diffusion in glasses and semiconductors.

25
A major effort was expended in problem oriented projects and cooperative

programs with other agencies. The expansion of research activities into

related areas of general analytical importance such as sampling and quality

assurance has focussed around specimen banking. During the past year the

program to analyze trace elements in human liver and Mytilus edulis (mussels)

specimens required the efforts of both activation analysis and atomic absorption. Even though the NBS specimen bank program is a pilot effort, the

experience gained provides the basis for considering specimen banking as a viable long term mechanism for evaluating environmental health and monitoring

parts of our biosphere. The protocols developed for sample collection,

processing, storage, and analysis, under contamination-free conditions, yield

benefits beyond their application to specimens in the NBS pilot specimen bank

and are applicable to other critical areas such as nutrition and health. In an effort to transfer the technology and expertise, cooperative agreements

have been established with the Armed Forces Institute of Pathology and

Georgetown University School of Dentistry.

The continuing efforts to enhance the capabilities of INAA and RNAA procedures have resulted in several major accomplishments. For example, mercury

can now be determined at the ng/g level in water and urine utilizing an optimized INAA procedure. This achievement resulted from a significant

improvement in the performance of recently upgraded equipment. RNAA procedures

such as group separations or element specific liquid extractions have been

further developed to exploit the inherent sensitivities of activation analysis.

These procedures are used to determine critical elements, at low concentration

levels, in materials like milk and serum.

Considerable improvements in the equipment for nuclear measurements have

been realized. An additional high efficiency, high resolution detector was installed, enhancing multielement and low level capabilities. A pneumatic

shuttle system was installed for rapid sample transfer from the irradiation

facilities to the counting rooms. It is equipped for automated operation and,

in addition, can function as a sample changer. A second new sample changer

is being installed in cooperation with the Smithsonian Institution. Interactions with the manufacturers of nuclear data acquisition systems have led to

the general availability of a loss-free ADC and modular MCA's which are based

on existing computers. A modular system has been purchased and extensive use during the next year should provide the basis for further improvements.

Research plans for the coming year include continued efforts to improve

the INAA and RNAA procedures. The modifications in the irradiation facilities

along with the planned upgrade of the reactor power to 20 MW will be utilized

to initiate and evaluate "absolute" activation analysis. This methodology

will be based on continuous monitoring of the neutron flux spectrum at the

irradiation site. It will allow definitive determinations of essentially all

elements that can be activated as long as their nuclear parameters are known

with sufficient precision and accuracy. In the long range, isotopic abundances, half lifes and decay schemes may have to be redetermined. Upgrading

the reactor to higher power levels will allow the facility to be used for

additional purposes; such as beryllium depth profiling. These improvements

in the current irradiation facility will enhance both sensitivity and resolution for neutron depth profiling measurements. It is anticipated that

26
investigations of near surface regions in materials may extend beyond the

capabilities of NDP. Therefore, a proposal to use charged particles for depth

profiling is being developed. This proposal could result in a CAC facility

that is available for depth profiling work as well as for other activation

analysis programs. Such a facility would allow the Group to become independent

of the reactor as a neutron source as well as adding new methodologies to the

scope of work. Independently, a major effort will be put towards evaluating

"non-conventional " activation analysis procedures. Very short lived isotopes

are of interest for new applications, and 14 MeV and charged particle activation will be evaluated for the determination of light elements, e.g., gases

in metals. With the increased sensitivities of INAA and RNAA new approaches

utilizing chromatographic procedures will be tested for the determination of

organometallic and biological species.

Rolf L. Zeisler, Group Leader; M. James Blackman, Kathleen A. Fitzpatrick,

Ronald F. Fleming, Robert R. Greenberg, John K. Langland, Richard M. Lindstrom,

George J. Lutz, Susan F. Stone, John T. Maki , Dietrich H. Vincent

2. Analytical Mass Spectrometry Group: Overview

The Analytical Mass Spectrometry Group develops and maintains the

capabilities required to perform chemical composition measurements using the

analytical sciences of chemical separation and mass spectrometry. For many

years, the Group has been involved in chemical separations, plus the highly

precise and accurate isotope ratio measurements, required to determine the

atomic weights of the elements and to make definitive isotope dilution measurements of trace element concentrations. While maintaining the basic thrust in

the traditional areas, the horizons of the Group have broadened markedly in

the past year. Predicated on the competence building program and related basic

research, substantial changes have been initiated to develop new capabilities

for chemical separations and ion spectroscopy. By combining the foundation

evolved from many years of measurement research and applications with the

fundamental changes described below, the next few years will witness the

evolution of a new generation of measurement capabilities for analytical ion

spectroscopy and the realization of new compositional analysis capabilities

that they portend.

Basic and applied research have been pursued in several significant

areas that will eventually restructure, in a fundamental way, measurement

capabilities in analytical spectrometry for chemical composition analysis.

Research in the ion mechanisms competence building program has resulted in

several significant accomplishments: resonance ionization mass spectrometry

(RIMS) has been used to demonstrate resonance ionization feasibility and to

study the spectroscopy for one-fourth of the elements in the periodic table;

selective electronic energy state interrogation has resulted in the characterization of atomic metastable distributions and a better understanding of the

thermodynamic nature of the thermal atomization process; a three-photon process

has been used to ionize carbon and iodine, which potentially opens up most of

the upper right-hand portion of the periodic table to analysis and provides

access to an unexplored area of ultraviolet atomic spectroscopy; the incipient

basis for multielement analysis with RIMS has been established and the ability

to access more than twenty elements in a single tunable dye range has been

27
demonstrated; a pulsed atom source has been developed and evaluated to provide

a projected 30-fold improvement in RIMS sample utilization efficiency.

Ion optics calculations for the magnetic sector systems have been refined

during the past year to eliminate software and computation inconsistencies.

Refined stray magnetic field measurements have been completed on a magnet with

adjustable gap widths and a more refined algorithm is being developed to fit

the data. A copy of the recently developed Simion ion source computer modeling

program has been acquired and efforts are underway to access the necessary

on-site computing capability to integrate Simion into the overall approach to

ion optics modeling. A new system for rapid switching of the high voltage

supply is being developed for spark source mass spectrometry. Variations in

sample homogeneity and sparking conditions would be minimized for isotope

dilution trace measurements, resulting in improved accuracies and precisions.

Last year the thermal formation of negative ions from complex emitting

surfaces was combined with chemical separations to produce an isotope dilution

method for determining iodine in botanical materials. Recently, a modified

negative ion source design was acquired that can be operated at higher voltages

with attendant higher efficiencies. During the next year this ion source will

be used to explore negative ion formation characteristics in thermal sources. Possible applications to high ionization potential transition metals and non- metals will be examined.

Recent developments in trace level sulfur measurements by isotope dilution

have produced a method capable of precisely analyzing samples containing yg/g

quantities of sulfur. Exploratory research with this methodology has been

pursued to establish the feasibility of identifying the sources of sulfur in

particulate air samples. Encouraging results have been obtained from a collaborative effort with Professor Zoller of the University of Maryland to

resolve isotope ratio variations in high altitude samples of particulate ejecta

from the Mexican El Chi chon volcanic eruption. These results indicate that

sulfur isotope ratio variations can possibly be used as a tool for the

"provenance" determination of acid rain. The established capability for

provenance determination of archaeological artifacts using the lead isotope

ratio "fingerprint" has continued in collaboration with the Smithsonian

Institution. A new and extensive collection of Chinese bronze artifacts has

been examined, and the resulting lead isotope ratios have been aggregated into

five groups that suggest separate artifact fabrication sites. Efforts are currently underway to correlate these groups with existing geological isotope

ratio data from specific locations in China.

A substantial portion of the effort in the atomic weights program this

past year was directed toward producing an up-to-date compilation of atomic

weight data from international research efforts. These data were compiled for

the 1983 meeting of the IUPAC Commission on the atomic weights of the elements

and represent the efforts of experts from Europe and the United States.

Experimental atomic weight research continues on the gravimetric assay of

lithium and on refinements to the chemical purification and isotopic analysis

of gallium.

28
High sensitivity applications of isotope dilution have highlighted the

analytical applications portion of the Group's program, including ultra-low

concentration measurements of uranium, vanadium, _and cadmium in biological

materials and other natural matrices (e.g., 5xlO~ 10 g/g Cd in normal urine,

SRM 2670). These measurements, in combination with the lower levels of chromium

and sulfur, determined in a variety of SRM's and natural matrices, are indicative of the considerably expanded measurement capabilities. A large number of

certification measurements were completed for the Standard Reference Materials

program including trace elements in human serum, metals, waters, and biological

materials.

Collaborative efforts have been initiated between members of the Group and

scientists from the Centers for Radiation Research, Absolute Physical Quantities,

and Chemical Physics. The CRR-CAC collaboration has already produced several

theoretical and experimental research papers dealing with isotopic ionization

selectivity and the potential for measuring high abundance sensitivity ratios.

Progress is anticipated during the next year in the selective state interrogation of sputtered neutrals from solid surfaces in collaboration with personnel

from the Surface Science Division of the Center for Chemical Physics.

Several substantial proposals to other government agencies are in various

stages of progress. If completely successful, these long-term proposals will

impact the Group's program heavily in the areas of: basic research in resonant

ionization pathways and highly sensitive and selective isotope measurements

with laser spectroscopy; technology development and studies of nutrition and

essential trace element bioavailability in humans using stable isotope tracers;

and a new approach to the direct compositional analysis of solids using

selective resonance ionization of neutrals sputtered from solids. Equipment

funds from an other agency proposal are currently being used to establish a unique RIMS facility for high abundance sensitivity measurements.

Research in ion optics and measurement science will result in an upgrading

of existing mass spectrometry instrumentation in several critical areas and

allow the Group to maintain its leadership in accurate and precise isotope

ratio measurements. Significant advances achieved in RIMS technology during

the past year will continue to play an important role in defining new areas of

potential impact in chemical composition measurements. The ability to sensitively and selectively interrogate atoms and molecules with energy state

specificity provides a unique and broadly applicable level of measurement

sophistication in ion spectroscopy. The impact of these developments will be

felt in a trend toward matrix-free direct compositional analysis, ultrasensitive

measurements of atoms and molecules in natural samples, and chemical speciation.

A full development of negative ion spectroscopy should greatly expand the

utility of thermal ionization for isotope dilution and related applications for

which the precision and accuracy may be usefully employed in the establishment

of definitive measurements.

Plans are underway to combine the areas of chemical separations technology

with the new instrumentation under development to provide a powerful new set

of analytical tools for real-world samples. For example, the group-specific

chelate separation schemes can be developed to match the evolving multielement

RIMS isotope dilution capabilities that utilize specific laser-dye combinations

29
and element groupings. In general, by combining the established measurement

expertise in isotope ratios and mass spectrometry with the above new developments, quantum level advances can be realized in the determination of chemical

compositions.

Larry J. Moore, Group Leader; I. Lynus Barnes, Ellyn S. Beary,

William A. Bowman, III, Karen A. Brletic, Emile C. Deal, John D. Fassett,

John W. Gramlich, Emerson F. Heald, William R. Kelly, Howard M. Kingston,

George M. Lambert, Lawrence A. Machlan, John R. Moody, Thomas J. Murphy,

Paul J. Paulsen, Lura J. Powell, Ronald W. Shideler, Mary E. Stone

3. Atomic and Molecular Spectrometry Group: Overview

The objective of the Atomic and Molecular Spectrometry Group is to conduct

research on fundamental chemical and physical phenomena related to sampling and

spectrochemical analysis. Experimental control of critical processes can then

be used to improve analytical measurement capability. This research includes

the development of new and improved techniques to lower the detection limits

for elemental analysis and to improve the precision and accuracy of these

measurements. Efforts toward achieving these goals have been in the area of

material transport, matrix modification, gases in metals, high accuracy

spectrophotometry and expanded multielement capabilities.

Research in material transport has proceeded in three basic phases. The

first phase involved the design and construction of a controlled waveform spark source to be used in the fundamental studies on spark sampling. The second

phase of the research has involved the modification of a commercial spark

stand to accept the standard tungsten counter electrode as well as a laminar

flow jet counter electrode. The third phase was the production, collection,

and analysis of aerosol particulates from SRM brass and titanium based alloys.

Differences in composition between spheres and aggregates produced in the

discharge varied with the materials. Future studies will involve a quantitative assessment of the sampling process.

Significant progress has been made in a continuing program to develop

methods for the determination of gases in metals. Methods have been developed

for hydrogen in cast iron and steels using state-of-the-art instrumentation.

Sample preparation and analysis procedures are presently being developed for

the determination of oxygen and nitrogen in metals and methods should be

available for certifying these gases in SRM's in the near future. In a related

area, methods have been developed for the determination of carbon and sulfur

in cast irons, steels, and other metals.

In high accuracy spectrophotometry, two problems continue to limit the

production and potential utilization of the NBS thin metal film transmittance

SRM. Fortunately, the problem of significant wedge effects, observed in many

of the earlier films, has been minimized by systematically modifying and

empirically determining optimum coating conditions. Currently the transmittance

uniformity of films supplied by a commercial contractor is about 0.1 percent.

The second problem deals with a general concern about using thin metal film

filters in instruments that have an interreflection error. These films

30
attenuate radiation not only by absorption but also by reflection. This

reflected component could, in instruments of specific design, produce artifically large interreflection effects. A modified design of a metal -on-quartz

filter that should eliminate the reflected radiation from the optical path is

presently being tested in a broad range of commercial spectrophotometers. A

major development in using the high accuracy spectrophotometer has been the

extension of the wavelength range from the current 200-800 nm to 2500 nm

(2.5 ym). This new capability is expected to have important applications in

the areas of defense, agriculture, and medicine where IR measurements are important. In addition, a special multi-purpose fluorescent glass standard,

for improved characterization of dye penetranst used in non-destructive crack

testing procedures, was produced and evaluated.

Major thrusts during the past year included characterizing Standard

Reference Materials (SRM's) and providing analytical services to characterize

highly complex samples for other government agencies as well as other divisions

at NBS. To meet these demands, new spectrochemical techniques were developed

and expertise in old established techniques such as Kjeldahl nitrogen, spectrophotometric determination of fluoride, and gases in metals was renewed.

A great deal was accomplished in the area of spectrometric analysis during

the past year. The methods employed include AAS, I CP, and DCP. The following

SRM's have been characterized for major, minor, and/or trace constituents:

Trace Elements in Water, Powdered Milk, Urine, Pine Needles, Tomato Leaves,

Bovine Liver, Human Serum, Fly Ash, Cast Iron, Urban Particulates, Incoloys

and Inconel s. Wear Metals in Oil, High Purity Heptane and Isooctane, Manganese

Ore, Rutile, Brasses, Bronzes, Trace Elements on Filters, XRF-films, and

Aqueous Spectrometric Standard Solutions. AAS was used to determine several

elements in samples of human liver for the tissue bank, four elements in a heart-tissue sample survey for the Johns Hopkins University, and germanium in

samples of serum, plasma, urine, red blood cells, and bile from patients at

the Georgetown University Hospital. In addition, ICP, DCP, and AAS techniques

were used to determine trace elements in samples of acid rain, solid waste

leachates, nuclear waste glasses, and EPA drinking water standard solutions.

Optical emission spectrometry (spark) was again used extensively for homogeneity

studies of SRM's (irons, steels, brasses, and bronzes). This technique was also used to produce elemental profiles for several steels.

Another significant project was the development of a training program for

visiting scientists in state-of-the-art sample preparation, atomic absorption,

and emission spectrometry procedures. During the past year scientists from

the National Sanitation Foundation, B. F. Goodrich, Materials Research

Corporation, and U.S. Army Aberdeen Proving Ground participated in this

program. In addition, at the request of the U.S. State Department, a program

is underway to train four scientists from the Assay and Weights Administration

in Cairo, Egypt.

Research during the coming year will focus on the development of multielement procedures, primarily on solid sampling techniques to be used in

conjunction with AAS and ICP. Other activities will include the development • of a procedure for the analysis of silicon in biological materials and the

development of new methodologies for tin analysis in sea water. In the area

31
of metal analysis, the Kjeldahl method for nitrogen will be applied to trace

nitrogen determinations in steels, and new or improved methods for oxygen and

nitrogen in metals will be investigated. The extension of the wavelength

range of the high-accuracy spectrophotometer to the near-infrared region will

be completed and the evaluation of new primary sources in atomic absorption

and fluorescence will be undertaken. Material transport research will focus

on the examination of the dependence of particle size distributions on spark

source parameters and the chemical analysis of specific size fractions by ICP

and AAS. Investigations into sample introduction techniques for plasma

emission spectrometry will include the development of continuous flow injection

for microsampling by DCP and ICP, and a feasibility study for using hydride

generation as a technique for introducing samples into the DCP and ICP.

Theodore C. Rains, Group Leader; David E. Brown, Robert W. Burke,

Therese A. Butler, Barry I. Diamondstone, Michael S. Epstein, Radu Mavrodineanu,

Kimberly I. Moran, John A. Norris, Douglas J. Patin, Theresa A. Rush,

Robert L. Watters, Jr., Yong-Kang Zhang

4. Electroanalytical Chemistry Group: Overview

The Electroanalytical Chemistry Group conducts basic research and utilizes

electrochemical principles to develop techniques and apply them to chemical

analyses. The techniques in practice include amperometry, anodic stripping

voltammetry, conductimetry, coulometry, ion chromatography, potentiometry , and

voltammetry. Research activities are directed toward attaining a more thorough

understanding of the complex electrochemical systems encountered in the

development and implementation of electroanalytical methods. In this past

year the Group has added a full-time research chemist and a NRC/NBS Postdoctoral Research Associate. In addition, two guest workers from the University

of Maryland were active through the year, and a Visiting Professor from

Tennessee State University joined the Group during the last quarter. During

the summer, two students actively participated in the Group's work. This

increase in personnel allowed the Group to expand into the following new areas of research: fundamental studies in potentiometric measurements, hydrodynamic

modulation, and applications of anodic stripping voltammetry.

This year the Group hosted a very successful symposium entitled "Workshop

in Direct Potentiometric Measurements in Blood," co-sponsored by CAC/NBS and

the National Committee for Clinical Laboratory Standards (NCCLS). The purpose

of this meeting was to provide a forum for research scientists and manufacturers and users of clinical instrumentation to discuss the current status and

needs of direct potentiometric measurements in blood, with particular emphasis

on the measurement of sodium. The workshop was international in scope with

eight of the sixty- three attendees being from foreign countries. The proceedings of the workshop will be published.

The new pH facility has been well utilized for several projects. Three new lots of SRM pH buffers (sodium bicarbonate/sodium carbonate, borax, and

potassium di hydrogen phosphate/di sodium hydrogen phosphate) and one new lot

of SRM pD buffer (sodium bicarbonate/sodium carbonate) have been certified

using hydrogen Ag-AgCl cells without liquid junction. The pH values of two

solutions of dilute hydrochloric acid have been determined with the same

32
apparatus. These solutions represent a preliminary effort in the development

of a new generation of pH standards, which will be matrix specific, in this case for acid rain measurements. Concurrent with these pH determinations,

fundamental studies of the standard potential of the silver/silver chloride

electrode are in progress. This work is described in detail as a technical

highlight.

Research in voltammetry is in progress in the area of hydrodynamic

modulation. Platinum, gold, and amalgamated gold vibrating wire microelectrodes

have been designed and constructed at NBS along with the related hardware and

electronic circuitry. A new method for estimating diffusion-layer thickness

at hydrodynamic electrodes has been conceived and tested for rotating disc

electrodes and vibrating electrodes. The theory of the relaxation of the

Nernstian diffusion layer has been extended to predict the frequency response

of the vibrating wire electrode. The development of the vibrating wire

voltammetric technique and its application to flow-injection analysis is in

progress. This should substantially reduce background currents and enhance

sensitivity for ultra-trace metal analyses. A spin-off of this research has

been the discovery that the vibrating wire electrode may have applications for

extremely low ionic strength DC conductivity measurements.

The instrumentation for ion chromatography (IC) has been heavily used for

the analysis of several SRM's (milk powder, fly ash, vanadium in oil, base oil,

and wear metals in oil), acid rain samples, and water quality audit solutions.

The IC analysis of total cyanide has been extended to cyano-metal complexes by

modifying existing reflux-distillation procedures.

Work on an acid rain project has progressed significantly toward the

development of reference materials and measurement methodologies to provide

quality assurance for the National Acid Precipitation Assessment Program.

This work is detailed in a technical highlight.

Coulometry has been used, in the controlled current mode, for highaccuracy assays of several preparations of uranium oxide from Oak Ridge

National Laboratory and in the control! ed-potential mode for the assay of

rutile. Anodic stripping voltammetry is being applied to the analysis of acid

rain samples, glass films, and hair.

The Group is maintaining its proficiency in traditional chemical analyses

through the determination of total manganese and available oxygen in manganese

ore by permanganate titration. In addition, a cooperative effort is underway

with the Metallurgy Division (564) to study the characteristics of plating

bath solutions used in the pulsed electrodeposition of nickel -chromium alloys.

An informal agreement was initiated with the Department of Chemistry,

University of Maryland, to collaborate in the investigation of air particulate

and aerosol samples from remote areas and areas of volcanic activity. The

major objectives of this project are to develop the methodologies necessary

for trace-level sulfur and chlorine measurements and to use these methodologies to establish baseline values.

33
The expansion in personnel and in scope of research, within the Group, is

expected to continue through active collaboration with area universities and

by making full use of the postdoctoral, research associate and visiting

scientists programs. The agreement with the University of Maryland will

continue. In conjunction with the NCCLS, it is anticipated that a research

associate will develop methods and reference materials for the potentiometric

measurement of calcium in biological fluids. Research in pH will continue

as a long-term commitment to provide reliable and thermodynamically significant

measurements and standards for one of the most widely used analytical

parameters. In the next year, this activity will focus on resolving the

problems associated with residual liquid junction potentials, specifically as they apply to acid rain measurement. Research will be initiated to develop

advanced expertise in conductance measurements with the view towards issuing a Standard Reference Material for aqueous conductivity and towards understanding

the fundemental relationships among conductivity, ionic mobility, diffusion,

and ionic strength. Flow- injection analysis with electrochemical detection

will be explored in depth. The outlook for the acquisition of an advanced ion

chromatographic system is promising. This instrument will allow the Group to

expand this technique into speciation studies for metals and metal lo-compl exes,

and into cationic analyses.

William F. Koch, Group Leader; George Marinenko, Kenneth W. Pratt,

Roger M. Stone, Rubye P. Torrey, Yung-Chi Wu

34
B. Selected Technical Reports

(Inorganic Analytical Research Division)

1 . A New Electrochemical Technique for the Estimation of Diffusion-Layer

Thicknesses at Hydrodynamic Electrodes (27201)

K. W. Pratt, Jr.

In voltammetry, the maximum analytical sensitivity of convective

electrodes is governed by the thickness of the diffusion layer established at

the electrode. Hence, the diffusion-layer thickness, 6, provides a figure of

merit for the sensitivity of a given electrode. The value of 6 may be used

both in intercomparisons of electrodes of different geometries and in optimization of a specific electrode. Measurement of 6 by standard techniques requires

the determination of the "electrochemical" surface area of the electrode, which

generally is greater than the "geometric" surface area.

In the past year, a new technique has been developed at NBS which allows

the value of 6 to be determined for any hydrodynamic electrode without measuring the surface area of the electrode. Prior knowledge of the hydrodynamic

conditions prevailing at the electrode is not required. The determination of

6 by this new technique is based on a comparison of the steady-state and

transient currents observed at the same electrode in a single solution. The

steady-state limiting current, I ss

, is measured under the hydrodynamic conditions of interest at a potential Ei, corresponding to the mass-transport

limited reaction of the electroactive species at the electrode. The transient

faradaic response of the electrode, I(t), is then recorded in quiescent

solution for a potential step at time t = 0 from a value E Q

, where no reaction occurs at the electrode, to Ei , the value used in the steady-state

measurements. These currents are described by equation 1 for the steady-state

case and by equation 2, the Cottrell equation, for the transient case:

In these equations, the parameters n, F, A, D, and C represent the number of

electrons in the electrode reaction, Faraday constant, electrode surface area,

diffusion constant, and concentration of the electroactive species, respectively. Using the same electrode and solution in both experiments ensures the

equality of n, F, A, D, and C.

Representative graphs of I and I(t) as functions of time are presented

in figure 5. For t = t

Q

, the point at which I(t) = I $s , the right members of

equations 1 and 2 are equal. Simplification yields the following expression:

I ee nFADC

ss =

6

( 1 )

( 2 )

6 = (TrDt

Q

) 1/2

(3)

35
*0

t Figure 5. Steady-state and transient faradaic currents for

a typical electrode. I = I ( t) at t = t

Q

.

Equation 3 is used to calculate the value of 6, using the experimental t . Values for D may be calculated from ionic mobilities, available from

0 the literature. Neither A nor C needs to be experimentally determined.

Experimental determinations of diffusion layer thickness have been con- ducted at NBS using rotating disc and vibrating electrodes, for which 6 ranged

from 2.5 to 15 ym. Recordings of I ( t) were obtained using a triggered-sweep

oscilloscope and a pulsed potentiostat with 2 ys response time. Non-faradaic

components were eliminated from the I ( t) -t curve by graphic subtraction of the

non-faradaic transient recorded in pure supporting electrolyte. Values of 6 obtained by the new method agreed within 10 percent of those obtained using

standard techniques. Errors can be attributed to bulk depletion resulting from

repetitive pulsing of the electrode. Comparative tests employing a potentiostat

designed at NBS proved that the errors in 6 were not related to the response

time of the potentiostat.

This technique has been applied to the rotating disc electrode (RDE), for

which an expression for 6 based on hydrodynamic theory is known. Using the RDE,

this technique has also been employed to determine diffusion coefficients of

electroactive species. This same technique is also suited to the direct determination of the Schmidt number. Sc. In conjunction with a signal generator and

synchronization circuity developed in this laboratory, theoretical models based

on this technique have been developed which describe the experimentally observed

electrochemical frequency response characteristic of vibrating wire electrodes.

Future efforts in this area will be directed toward increasing the

accuracy of the method and extending the results to a comparative evaluation

of the sensitivity of pulsed and hydrodynamic techniques in voltammetry.

36
2. Determination of Vanadium in Botanical, Biological, and Environmental

SRM's Using High-Sensitivity, Pulse-Counting Isotope Dilution Thermal

Ionization Mass Spectrometry (15310)

J. D. Fassett, H. M. Kingston

Vanadium is an essential trace element in man and other species of animal

and plant-life. The relationship of V to human health is currently being

investigated. Vanadium concentration is regulated within a narrow range in

the blood stream of healthy individuals but has been shown to vary for both

cancer and heart patients. Like many trace elements, V is toxic when ingested

at elevated levels. Most cases of V toxicity are related to the use of fossil

fuels, whose combustion products are typically V enriched.

A high-sensitivity, isotope dilution thermal ionization mass spectrometric

procedure, capable of determining V at the ultratrace level has been developed

which makes possible the certification of many biological and botanical standards for V content at natural levels. New procedures in both mass spectrometry

and chemistry have been developed to extend earlier work done at NBS to the

ultratrace levels.

A series of successively lower 50 V enriched standards were prepared and

calibrated. These calibrated spike solutions and standards permitted all

samples, regardless of their V content, to be optimally spiked. A separation

procedure that uses a chelating resin was developed. Vanadium-48 and 51 Cr

radiotracers were used to optimize the separation procedure which chelates the

V and then allows it to be selectively removed from a small column of resin.

Each sample is oxidized prior to analysis and is contained in a single drop of

6 mol/L hydrochloric acid.

The separated V samples are loaded onto rhenium filaments containing a slurry of high purity, spectroscopic graphite. The advantages of this procedure

are that a relatively large V ion beam is formed with low Cr, Ti, and V blanks;

vanadium oxide formation which can cause unpredictable and undesirable behavior

is suppressed; and, the high temperature ionization filament used in triple

filament procedures is avoided, thus reducing Cr background. The loading

blank is measured by directly loading ng amounts of the V spike and is less

than 50 pg. Measurements were made on a thermal ionization mass spectrometer

equipped with an ion-counting detector, for maximum detection sensitivity.

The determination of V is complicated by two isobaric interferences, 50 Cr

and 50 Ti. To accurately measure 50 V/ 51 V, both 52 Cr and 48 Ti must be monitored

and corrections must be made for these interferences. These elements are essentially separated during the chemical processing. However, residual

signals for both elements come from the purified V samples and from the filament loading process. Typical corrections are less than 0.25 percent. The

limiting factor in the determination of V is the analytical blank which has

ranged from 0. 9-4.0 ng. The source of this blank must be identified and the

level of the blank must be significantly reduced in order to determine the low

V levels in some important matrices such as human serum, which has a concentration of 0.02-0.04 ng/g.

37
Table 3 summarizes the values obtained and the associated measurement

uncertainties for the materials analyzed to date. The biological, botanical,

and environmental materials which have now been certified for V should provide

significant support to initial investigative efforts. However, additional

materials such as serum and foodstuffs need to be analyzed to fulfill the

needs of researchers evaluating the effects of V on human health.

Table 3. The Concentration of Vanadium in Selected SRM's.

SRM Concentration, yg/g

1566, Oyster Tissue 2.316 + 0.006 a

1572, Citrus Leaves 0.2446 + 0.0049

1643b, Trace Elements in Water 0.04520 + 0.00012

1633a, Fly Ash 296.7 + 0.9

RM

8505, V in Crude Oil 390.4 ± 1.1

a

± value represents measurement precision, s, for at least six

independent determinations.

3. Ultratrace Determinations of Critical Elements in Biological Materials

Using Improved Radiochemical Separations (15310)

R. R. Greenberg

In view of the continuing concern over the levels of anthropogenic inputs

to the environment, accurate and reliable analytical methods for the determination of toxic elements are needed. The need to determine these elements at

lower and lower concentrations necessitates improvements in the analytical

methodology. When coupled to an appropriate radiochemical separation, neutron

activation analysis (NAA) has the capability of determining many biologically

important elements at the required trace and ultratrace levels.

A radiochemical procedure was previously developed to determine Ag, As,

Cr, Mo, Sb, and Se via NAA with the use of hydrated manganese dioxide (HMD)

inorganic ion exchanger [1], Copper and cadmium were subsequently extracted

from the eluent using Bi and Zn di ethyl dithiocarbamates (DDC) in chloroform,

and their concentrations were determined. Unfortunately, most or all of the P contained in a sample is also retained by HMD when the above procedure is used,

and 32 P can interfere with the determination of the elements of interest by

elevating the background level of radiation. This can be particularly serious

when analyzing biological materials such as animal tissues and body fluids,

milk, leafy vegetables, etc. where the P concentration can be as high as one

38
percent on a dry weight basis. In addition, the determination of Cd, after

extraction with Zn(DDC) 2 , can, at the ng/g level and below, suffer from the

background radiation produced by the small fraction of radioactive Zn which

accompanies Cd through the separation procedure.

Research was initiated to reduce the level of P retained on the HMD resin

and also to reduce the fraction of radioactive Zn accompanying Cd. A procedure

has been developed which, with carefully controlled experimental parameters,

reduces the 32 P level on the HMD column by 80-90 percent and has only minimal

effects on the elements of interest. Basically, the procedure involves

preconditioning the HMD with 1M HN03 -1M H 3 PO4 followed by eluting the 32 P with

dilute (0.0025 M) H 3 PO4 in 1M HN03

. With these modifications Ag, As, Mo, and

Sb are quantitatively retained (>99.5 percent), Cr and Se are nearly quantitatively retained (98.5-99.5 percent) and Cu and Cd are quantitatively eluted.

This procedure has been used to analyze Bovine Liver (SRM 1577) and the new Milk Powder (proposed SRM 1549), which is currently being certified. The

observed concentrations in the Bovine Liver are compared with the certified

values in Table 4. The amount of 32 P retained by the HMD was reduced by 80-90

percent resulting in a reduction of the background levels for most elements by

a factor of 5-10. This lower level of background radiation not only improved

the counting statistics by a factor of 2-3, but also allowed the samples to be

counted closer to the detector for an additional improvement in sensitivity.

Table 4. Concentrations Observed in Bovine Liver, SRM 1577.

Element This Work Certified

Ag (ng/g) 58 + 2a

(60)

b

As (ng/g) 50 + 2 55 ± 5

Cd (ng/g) 292 + 8 270 ± 40

Cr (ng/g) 85 ± 5 88 ± 12

Cu (yg/g) 192 + 4 193 ± 10

Mo (yg/g) 3.18 + 0.03 (3.4)

b

Sb (ng/g) 5.6 + 0.7 (5)

b

Se (yg/g) 1.08 + 0.03 1.1 ± 0 .

Uncertainties are standard deviations (Is) of five or more samples.

bNon-certified, information only value.

Although Cd can be determined in most biological materials as part of the

multielement HMD-DDC procedure, its concentration in the Milk Powder was too

low to be determined with the interference produced by Zn(DDC ) 2 carry through.

Efforts were directed at reducing the levels of radioactive Zn which accompanied

the Cd through the separation procedure. Several modifications to the

39
extraction procedure, including washing the Zn(DDC) 2 /chloroform solution

(containing Cd) twice with aqueous solutions of 100 mg of unirradiated Zn+2

, back-extractinq the Cd into 2M HC1 , and eliminating the HMD step (to minimize

decay of the x ^ 5 Cd isotope) produced a significantly improved signal-to-noise

ratio for Cd. The observed recovery for this separation procedure, while not

quantitative was highly reproducible, 95.2 ± 0.4 (ls)%. Five samples of Milk

Powder were analyzed and the observed Cd concentration was 0.47 ± 0.07 (Is)

ng/g.

Neutron activation analysis has the capability of determining many

elements at biologically important levels when coupled to an appropriate

radiochemical separation. Improved radiochemical separations have been

developed to determine eight biologically active elements at the trace and

ultratrace levels frequently required in current biomedical research. Two of

these elements, Cd and Sb have been determined at the sub-ppb level in the

Milk Powder. Individual separation procedures have previously been developed

for Hg, Pt, Se, and Sn, and continuing research will be directed at improving

the methodologies for other biologically important elements such as Cr and Ni.

Reference

[1] Gallorini, M. , Greenberg, R. R. , and Gills, T. E., Anal.

Chem. , 50, 1479 (1978).

4. Material Transport (15310)

R. L. Watters, Jr., J. A. Norris, M. S. Epstein

Many analytical spectrometric techniques consist of a step which converts

the sample into vapor followed by an excitation step. Various forms of atomic

and ionic spectroscopy are then used to derive the analytical signal. The

overall accuracy of such techniques can be limited by bias in the sampling

step. When the bulk sample is transported into a chemical and physical form

amenable to analysis, the vapor composition may not match that of the original

material. By focussing on the processes of sampling for analytical spectrometry we define a broad area of research on material transport devoted to the study

of a variety of sampling techniques. The short term goal is to investigate

the spark discharge as a sampling device.

The spark discharge produces atoms, ions, and particles by erosion of the

cathodic sample. The relative populations and compositions of these species

provide the elements necessary to define the material balance of this sampling

process. This year we have restricted our attention to the study of the

aerosol produced by the spark. The particles exiting an enclosed spark

standard were collected using an electrostatic precipitator and examined under

an analytical electron microscope (AEM). The spark source is similar to many

industrial units of the controlled waveform type which are used for emission

spectrometry. A second spark source was constructed to study the affects of

specific electronic parameters on aerosol production. Electronic triggering

of this source enables a wide range of spark repetition rates to be used.

40
A Standard Reference Material Brass Sample (SRM C1101) was chosen to

compare the Zn/Cu ratio in the collected aerosol with the bulk composition.

The certified values are 69.50 percent Cu and 30.30 percent Zn for a Zn/Cu

ratio of 0.436. The electronically triggered source was used to generate

aerosol for excitation with the inductively coupled plasma (I CP). The intensity

ratio of Zn/Cu emission from the I CP stabilized after a few seconds and

remained constant for 60 seconds. Furthermore, peak spark current, duration,

and repetition rate seemed to have little effect on the Zn/Cu intensity ratio.

However, observation of the aerosol using the AEM revealed two particle size

domains. A sparsely populated fraction consisted of 500 nanometer diameter

copper spheres in which Zn could not be detected. The predominant fraction

consisted of aggregates of 10 nanometer particles. Although these particles

contained both Cu and Zn, the exact concentration ratio has yet to be measured.

From these observations, it appears that the major mass fraction of sampled

brass is contained in the aggregates and that the composition of the sampled

material remains constant regardless of spark source parameters mentioned.

Particles from a titanium based alloy (SRM 654) and a stainless steel

material (SRM 1154) have also been examined using the AEM. Differences in

composition between spheres and aggregates are apparent in these materials

as well, and the relative population of the spheres in the stainless steel

aerosol is greater than the other aerosols.

It is thought that the aggregates result from vapor-phase condensation of

the sampled material and that spheres result from ejection of molten material

from the sample surface. It is, therefore, likely that the relative populations of these size fractions will vary with sample matrix. In order to

quantitatively measure the size fraction populations, an aerosol charge

mobility analyzer will be coupled to the electronically triggered source.

Each fraction will then be isolated for independent chemical analysis using

I CP, direct current plasma, and atomic absorption techniques. Observed variations in particle size and composition, and the degree to which these

variations can be controlled, will then be related to matrix type. The optical

equipment for investigating condensation processes using laser fluorescence is

presently being assembled for the next major phase of the study.

5. Analysis and Stability of Environmental Specimen Bank Samples (15310)

K. A. Fitzpatrick, S. F. Stone, R. Zeisler

Several tasks of the Pilot Environmental Specimen Bank program (see

previous reports [1,2]) have been accomplished in the past year. The first

sample type, human livers, is being collected and analyzed on a continuing

basis. From the previously banked and analyzed human liver specimens, a set

of 12 was selected and reanalyzed to evaluate their stability during long term

storage. A second sample type, Mytilus edulis , representing an aquatic

accumulator, was added to the bank.

Human Livers . The collection of liver samples is still carried out by a contractor in Seattle. By the end of this fiscal year, a total of 450 liver

samples will have been banked. Homogenization and analysis of the 30 baseline

samples collected during the second year are completed. This brings the total

41
number of analyzed livers to 66. The trace element concentrations found during

the second year of the study are comparable to those found during the first

year.

The reanalysis of the first year samples was carried out to evaluate the

effect of the different storage conditions on elemental concentrations. In

comparing data from the samples stored at liquid nitrogen vapor temperature

(-120 °C to -190 °C), at -80 °C, at -25 °C, and freeze dried at room temperature, no statistically significant changes (see [1]) have been found for trace

element concentrations.

Mussels . The marine mussel, Mytilus edulis , was added to the bank as the

second environmental sample. A set of 6000 mussels was collected from

Narragansett Bay, R.I., as part of the first year study to develop the sampling

and analytical protocols. The mussels were separated into batches of 70

animals each and banked under the four storage conditions: LN 2 (-120 °C to

-190 °C), -80 °C, -25 °C, and freeze dried at room temperature. Two batches

have been homogenized. Individual aliquots of the homogenate are stored at

LN2 vapor temperature and, to date, ten subsamples from each batch have been

analyzed.

The implementation of a completely instrumental analytical protocol was

initiated. Concentration for 28 trace elements were determined using neutron

activation analysis (INAA). This technique is complemented by an x-ray

fluorescence procedure to obtain data for additional elements and also to

provide a check on quality assurance for selected values obtained from INAA.

An intercomparison of the two techniques has been initiated. Table 5 shows

the mean values and their standard deviations for each of the elements obtained

from INAA in the ten subsamples. Additional data are given for a freshwater

mussel homogenate from the German Pilot Environmental Specimen Bank. This

analysis was done as part of the ongoing exchange of specimens between the two

programs and subsequent intercomparisons. The German homogenate shows elevated

europium and chromium levels and an unusually high hafnium concentration. The

difference in the bromine concentrations is explained by bromine being a component of sea salt, which would be present in the marine mussel tissues.

The future activities in this program will focus on the dissemination of

the results to the potential user communities and on the technology transfer

to other related programs. A cooperative program is being developed with the

Army Institute of Pathology. The goal is to investigate possible relationships

between trace constituent concentrations in different human organs and

diseases. In continuation of the initial pilot program, the sampling and

analysis procedures for the measurements of trace constituents in human

dietary intake will be reviewed. Collaboration in this area has been initiated

with USDA, FDA and IAEA.

References

[1] Annual Report 1981, CAC, NBSIR 81-2425, p. 9-16.

[2] Annual Report 1982, CAC, NBSIR 82-2620, p. 10-21.

42
Table 5. Trace Elements in Marine and Freshwater Bivalves.

(Concentration in yg/g)

Mytilus Edulis Dreissena Polymorphy

M2N0054 Mussel Homog.

Na 54200 + 1000 nd

Mg 6430 + 540 nd

A1 760 + 70 nd

Cl 100100 + 4900 nd

K 11700 + 1500 nd

Sc 0.138 + 0.007 0.699 + 0.006

Cr 2.05 ± 0.20 14.8 + 1.9

Mn 21.9 + 1.2 nd

Fe 571 + 27 978 + 60

Co 0.538 + 0.014 1.478 + 0.013

Cu <70 nd

Zn 122 + 5 154.7 + 0.8

As 10.4 + 1.0 6.90 + 0.48

Se 2.47 + 0.11 4.62 + 0.15

Br 443 + 40 38.6 + 1.5

Rb 7.24 + 0.56 0.251 + 0.027

Mo <1.4 2.5 + 0.3

Ag 0.104 + 0.013 <0.10

Cd <4 72.5

Sb 0.255 + 0.007 “0.033 + 0.010

Cs 0.683 + 0.003 0.165 + 0.006

La 0.59 + 0.09 0.472 + 0.015

Ce 0.98 + 0.10 0.79 + 0.14

Sm 0.101 + 0.014 0.130 + 0.008

Eu 0.0193 + 0.0004 0.557 + 0.006

Hg 0.48 + 0.24 <0.2

Th 0.139 + 0.006 nd

Hf 0.070 + 0.018 59.0 + 0.8

nd not determined. Errors represent sample standard deviation

and measurement uncertainty.

43
6. The Characterization of Metastable Excited State Atomic Species Produced

in Thermal Vaporization Using Resonance Ionization Mass Spectrometry

(RIMS) (26108)

J. D. Fassett, L. J. Moore, J. C. Travis (550), F. E. Lytle

Resonance ionization mass spectrometry (RIMS) combines mass spectrometry

with laser photo-ionization to provide a selective and sensitive method of

producing ions from a gas phase reservoir of atoms. As part of a multiyear

competence research program in ionization mechanisms and ion structures, a RIMS system has been established at NBS. This system is one of the first in

the U.S., where there are presently four or five laboratories actively

investigating applications of RIMS in analytical chemistry. Only recently

have the results of these investigations begun to appear in the literature.

The NBS RIMS system was described in last year's report [1] and at that time

preliminary results were discussed. In the past year the system has been

considerably upgraded, allowing it to be better utilized in a variety of

research modes. This report summarizes the broad elemental utility of the

system.

The NBS system is conceptually different from the RIMS systems established

elsewhere [2, 3]. By designing the system around a tunable dye laser with

frequency-doubled output, it was hoped that an experimentally versatile instrument would be established that could ionize a majority of elements in the

periodic table. Experiments have shown this original design concept to be

correct. Resonance ionization has been demonstrated for 25 elements in this

laboratory during the past year. Fully 75 percent of all elements ionized

by RIMS to date were first studied here at NBS. The majority of these elements

have extremely high ionization potentials and thus are difficult to ionize by

conventional means.

Several important changes have been made in the RIMS system. The initial

results indicated that the atomic spectroscopy was a much more complex phenom- enon than previously anticipated [ 1 J . Routine atomic spectroscopy was made

possible by completely automating the wavelength scanning capabilities of the

laser system. A computer-controlled stepper motor was coupled to the grating

of the dye laser with a minimum step size of 0.5 pm in the UV. An autotracker

was added to the frequency doubler which maintains maximum conversion of the

visible light to the UV as the dye laser frequency is scanned. Software was implemented to collect the data and plot ion-intensity versus wavelength

information in real time and to manipulate these data in a variety of useful

ways. The interaction of the laser beam with the atom plume was also changed

by the removal of the 200 mm lens which was previously used to focus the UV

light through the mass spectrometer. The saturation effects, which occurred

with focussing, severely distorted the laser optical spectra. These changes

have helped to make the spectroscopy more tractable.

The production of neutral atomic beams by thermal vaporization and

resonance ionization has been demonstrated for 25 elements. Table 6 summarizes

the results for those elements investigated with the wavelength range of the

dye Rhodamine 610, 292-304 nm, and in figure 6 the breadth of types of atomic

metastable distributions is illustrated, ranging from ^<100 percent ground state

44
Table 6. Resonance Ionization Mass Spectrometry Spectroscopic

Survey Between 292-304 nm.

ELEMENT

FIL./

TECH.

TEMP.

K

SPECTRAL LINES®

GSO ESO UNTAB.

MAX.

INT.

Co Re/H 1195 4 2 2 30.

Dy Re/H 1470 1 0 10 .72

Er Re/H 1561 1 0 4 6.4

Fe Re/H 1228 4 17 0 138.

Hf Hf (3.75 A) 5 7 1 15.6

In Re/C 1070 1 0 0 .84

Lu Re/H 1760 1 0 0 .44

Mo Re/H 1184 2 0 1 47.

Ni Re/H 1228 3 8 18 11.1

Re Re 2291 2 34 23 4700.

Sr Re/H 1294 1 0 0 1.5

Ta Ta (2.75 A) 2 15 4 137.

Th Re/C 1967 1 0 36 85.

Ti Re/C 1794 4 1

4 27.

U Re/C 1933 2 2 180 3.5

V Re/C 1828 2 11 1 3.7

Y Re/C 1736 5 6 2 40.

Zr Re/C 2033 2 2 10 3.8

®GSO“Ground— State— Originating. ESO“Excited— State — Originating.

Tabulated from NBS Monograph 145, Part 1.

Figure 6.

Wavelength, nm

RIMS spectra, ion intensity versus wavelength, of 187 Re , 60 Ni +

, 56 Fe+

, and 98 Mo

+

.

45
populations for Mo, to broadly populated lower energy level states for Fe and

Ni . In addition to the elements in the table, Li, Sn, Mg, Os, and Pb, as well

as I and C have also been photoionized. The samples were prepared for these

experiments by two methods designed to generate reduced elemental species on the thermal filament substrate: a hydrogen reduction process and a carbonization process (designated H and C, respectively in the table). Sample sizes were typically one microgram.

Peaks corresponding to the predicted ground-state-originating resonant

transitions were observed. Also observed were peaks corresponding to transitions from atomic excited states and untabulated, unexplained peaks. An

anlysis of the excited-state-originating lines produced the following observations. Although the relative intensities of lines are dependent upon photon

absorption cross sections, the wavelength-dependent photon flux, the geometry

of the laser/atom plume interaction volume, as well as the populations of the

transition-originating state, it was shown that the line intensities semiquantitatively follow a Boltzmann distribution of excited state populations as defined by the temperature of the filament. This result implies that

equilibrium conditions are established in the thermal vaporization source and

that excited-state atomic species which are formed in the vaporization process

are long lived.

The extent to which metastable excited-states affect analytical measurements using RIMS will be strongly dependent upon the element and its electronic

structure and to a lesser degree the vaporization temperature. For a large

number of elements, excited states will be significantly populated. The

implications are manifold. Absolute sensitivity will be reduced by a factor

corresponding to the fractional population of the level from which excitation

occurs, ionization efficiencies being equivalent. Furthermore, spectral

selectivity will be reduced as the number of observed transitions per element

increases. A positive aspect of metastable atom formation is the possibility

of using these spectral lines analytically in RIMS. This fact widens the

potential multielement analytical utility of the technique.

References

[1] Fassett, J. D., Travis, J. C. , Moore, L. J., and Lytle, F. E.,

Anal. Chem., 55, 765 (1983).

[2] Donahue, D. L., Young, J. P., and Smith, D. H., Int. J. Mass

Spectrom. Ion Phys., 43, 293 (1982).

[3] Miller, C. M. , Nogar, N. S., Gancarz, A. J., and Shields, W. R.

,

Anal. Chem., 54, 2377 (1982).

46
7. Interferences in the Determination of Germanium Using Electrothermal

Atomization Atomic Absorption Spectrometry (15310)

Y. K. Zhang, T. C. Rains

r—v /—N-(CH

? )~N(CH,) 2

Spirogermanium-HCl ^H^Ge^ V | 2HC1 , an antineoplastic agent, is being clinically evaluated on carcinoma cells and as an anti-malaria drug at the Georgetown University Hospital, Washington, DC. This

material is a white powder which is soluble in water and 95 percent ethanol

and has a molecular formula of C 17 H36 GeN2 *2 HC1. Presently, there is no established clinical method for the determination of germanium in biological

materials. The determination of germanium is difficult by any method because

it forms volatile halide compounds. In atomic absorption spectrometry,

germanium forms a highly stable oxide species at relatively high temperatures

which precludes the efficient production of germanium atoms. The high temperature nitrous_oxi de-acetylene flame has a detection limit of approximately

1.5 yg Ge mL" 1. However, the small quantity of sample available for analysis

in some biological samples precludes the use of any flame technique.

Electrothermal atomic absorption spectrometry (ETAAS) is frequently used

for trace analysis. However, the improved sensitivity for germanium by ETAAS

was not attained when the biological material was sampled off the walls of the

graphite tubes. With the addition of the L'vov platform to the graphite tube,

the absorption signal for germanium improved by an order of magnitude. This

supports the theory that the germanium is being volatilized as the oxide.

When the sample is volatilized off the wall of the graphite tube, the GeO

passes into the inner gas cavity, which is cooler than the wall temperature.

Under these conditions, the GeO is not completely dissociated into the atomic

form. When the L'vov platform is used, the GeO remains on the platform longer

permitting the inner gas cavity to reach a higher temperature; therefore, the

GeO is more likely to be dissociated.

The L'vov platform used in this study is similar to the one described by

Henderberger et a]_. [1]. A 5 by 8 mm curved section is cut from the grooved

end of a pyrolytically coated tube. No difference has been shown between used

and unused tubes. The sides of the chip or platform are filed so that the

platform will fit into the furnace, and the platform is inserted into another

graphite tube using a pair of tweezers. The platform is centered directly

under the sample port by using a metal probe. The window is reinstalled and

the injection tip adjusted to ensure that it does not come in contact with the

platform. There should be a 1 mm gap between the platform and the bottom of

the graphite cell. If the platform rests on the bottom of the graphite tube,

a longer cooling down period will be required after atomization.

Initial studies without the L'vov platform verified the reports of interferences found by other workers. Chloride and phosphate ions severely interfere

with the determination of germanium. To alleviate these difficulties, a series

of matrix modifiers was evaluated. Nickel nitrate is widely used in ETAAS as a matrix modifer to suppress the volatilization of As, Se, and Sn. Figure 7

shows a comparison of the absorption of germanium with and without nickel. Not

only did the nickel increase the sensitivity of germanium but it also permitted

47
Figure 7. Effect of charring temperature on absorption of 4 ng of germanium

with and without matrix modifiers.

A. 1% HN03 B. 1% HN0 3 plus 1 % ammonium tartrate

C. 1% HN03 plus 1000 yg Ni/ml (. - .) D. 1% HN03 , 1% ammonium tartrate plus 1000 yg Ni/mL (x - x)

the use of a higher charring temperature. Nickel concentrations of 1000 yg/mL

did not alleviate the interferences resulting from concentrations of chloride

greater than 0.5 percent. Ammonium tartrate was investigated but showed little

improvement over a 1 percent HN03 solution (Figure 7). However, with the

addition of nickel nitrate plus ammonium tartrate the interference of chloride

was completely removed and a charring temperature of 1200 °C could be used.

With no matrix modifier, 1 to 10 yg/mL of Na, K, Ca, Mg, and P04 completely

suppressed the absorption signal of 0.2 yg of germanium. With the addition of

1000 yg of nickel and 1 percent ammonium tartrate, concentrations of 5000 yg/mL

of Na, K, and Ca produced no adverse effect. Under the same conditions, a slight suppression of 0.2 yg/mL of Ge was observed at the 5000 yg/mL level of

magnesium. The presence of 1000 yg of P04 ”

3 produced a severe suppression of

the signal from 0.2 yg/mL of Ge. By increasing the concentration of nickel to

4000 yg/mL the effect of the signal from 2000 yg/mL of P04

"

3 on the signal

from 0.2 yg/mL of Ge was eliminated.

48
In summary, a method has been developed to determine germanium by ETAAS

at the submicrogram level using nickel and ammonium tartrate as matrix modifers

in conjunction with the L'vov platform. The procedure has been used to

determine germanium in samples of serum, plasma, red blood cells, urine, and

bile from patients treated with the drug at Georgetown University Hospital.

Reference

[1] Hinderberger, E. J., Kaiser, M. L., and Koirtyohann, S. R.

,

Atomic Spectrosc. , 2_, 1-7 (1981).

8. Gases-in-Metals Analysis (15310)

B. I. Diamondstone, D. E. Brown, G. J. Lutz

The capability to make quantitative measurements of gases-in-metals has

not been available at NBS for the last 15 years. As a result of outside

requests, the Division has begun to reestablish this capability with the

support of the Office of Standard Reference Materials. Earlier determinations

of gases-in-metals involved the use of hot-extraction and vacuum-fusion

techniques for hydrogen while analyses for oxygen and nitrogen were done by vacuum- fusion, inert gas fusion and neutron activation techniques. Of primary

importance has been the evaluation of newly received instrumentation to

determine its capabilities. In addition, the operators of the equipment must

gain the experience necessary for the analyses of various gases in a wide

variety of materials.

The gases-in-metals instrumentation has been combined, in a single

laboratory, with the carbon and sulfur analyzers. The new equipment consists

of a furnace and detector combination for the simultaneous determination of

oxygen and nitrogen as well as a similar unit for the determination of

hydrogen.

Initial studies involved the analyses of a number of commercially available

standards as well as NBS Standard Reference Materials (SRM's) to evaluate the

precision and accuracy of the instrumentation. Participation in a number of

ASTM round robins has also provided valuable information during the evaluation

period. Both of the above exercises required considerable investigation into

"proper" methods of sample preparation. This work is ongoing and is recognized

as a critical part of any analysis for gases in metals.

An important goal of the gases-in-metals program is to establish two

independent techniques for the certification of H2 , N 2 , and 02 in metal SRM's.

Work is underway to utilize activation analysis as a supporting technique. A

recent literature survey confirmed that 14 MeV neutron activation of oxygen is

specific for most metals and the lower limit is a few tenths of a ppm. Lower

levels can be determined by 3 He activation using an accelerator. Preliminary

samples have been delivered to the 14 MEV facility at Texas A&M. If the

information obtained from Texas A&M is promising, then further studies involving

NBS personnel will be planned. An extensive library search is underway to

locate potential backup techniques for H2 and N2 analyses.

49
The most significant accomplishment of the program, to date, has been the

completion of the analysis of SRM 352b, an unalloyed titanium which will be

certified for H2 and will replace SRM 352a. Although the data have not been

finalized, preliminary values indicate that this material will be certified

with an uncertainty considerably less than its predecessor.

The increased need for SRM's certified for gases will result in more

pressure to produce accurate and precise values for gases-in-metals at

continually decreasing concentrations. Considerable effort will be made to

update "information only" values on existing SRM's as well as to produce new

ones. Emphasis during the next few years will be on developing backup

techniques for certification and carefully evaluating the effects of sample

preparation on observed concentrations.

9. The Standard Potential of the Ag/AgCl Electrode for High Accuracy

pH Measurements (15310)

Y. C. Wu, G. Marinenko, K. W. Pratt, Jr., W. F. Koch

The Ag/AgCl electrode is a thermodynamically reversible electrode of the

second kind. Its usefulness has been demonstrated for many years and as a result it has been adopted as a reference electrode. The use of the Ag/AgCl

electrode for pH determinations was originated at NBS in the late thirties

[1]. Today this electrode is used routinely at NBS to certify pH measurements

in a number of SRM's.

The measurement of pH is directly related to E° of Ag/AgCl through the

following relationship:

E-E°

pH = -log a

H+ = log m^- + RTlnlO F + log (y c1

-

)

j

where a^+ is the activity of hydrogen ion, m

cl

- is the concentration of

chloride ion, E is the emf of the cell, E° is the emf of Ag/AgCl electrodes

at their standard states, F is the Faraday constant, y

c1

- is the activity

coefficient of chloride ion, and log (yq]

-

)j is evalauted at m^-j- -» 0 and at

constant ionic strength of the test solution. The value of E° is the measure

of accuracy for determining pH. Recently, Bates [2] has reported that values

for E° of Ag/AgCl determined in cells without-transference from over 30

independent measurements vary from 0.2222 to 0.2228 V at 25 °C. The extreme

difference is about 0.0006 V, which amounts to differences of approximately

0.01 pH units in subsequent pH measurements.

Variations in E° of such magnitude (0.6 mV) must be caused by the Ag/AgCl

electrode itself, because the other factors in the system for determining E° can be systematically eliminated. In fact, experts met in 1956 and decided to

assign an uncertainty of 0.2 mV to the E° measurements for this electrode.

The sources of problems associated with this electrode have been investigated

by numerous workers in electrochemistry. The areas studied have included

methodology, electrode preparation, and operational precautions. The

50
characteristics of this electrode needed to be better defined in order to

reduce the uncertainties associated with pH measurements done on SRM's at NBS.

When classical experiments were repeated, it was observed that oxygen

entered the electrode and was probably the major cause of the observed variations in E°. Although this observation was not new, the effect had never been

fully discussed and investigated. To verify the effect of oxygen on the

behavior of the electrode, the following experiments were conducted.

A. Electrode Preparation: A thermal electrolytic type of preparation

was selected because the method is simple and avoids contamination.

Classical procedures were followed, except when electrodes were

necessarily exposed to either ordinary or argon atmosphere.

B. Cell EMF Measurement: The cell setup, temperature control, and

measuring device were similar to those described by Durst [3]

with a few minor modifications. Special care was taken to have

the electrode and HC1 solution under either ordinary or argon

atmosphere.

Four sets of experimental conditions were compared:

where el(0) = electrode exposed to air, el(Ar) = electrode exposed to argon,

S (0) = HC1 solution saturated with air, S(Ar) = HC1 solution saturated with

argon. The range of results for approximately one hundred electrode measurements under the four sets of experimental conditions respectively are:

(1) E° = 0.22260 V and up

(2) E° = 0.22250 - 0.22260 V

(3) E° = 0.22240 - 0.22250 V

(4) E° = 0.22230 - 0.22240 V

The results clearly demonstrate the oxygen effect on E° for the Ag/AgCl

electrode. However, the overall reproducibility for each set was only ±0.05 mV

as compared with 0.01 to 0.02 mV as reported in the literature. Work is

continuing in the areas of oxygen adsorption and desorption measurements to

quantitatively determine the effects of oxygen on E°. This work is necessary

to lower the uncertainties in existing pH measurements.

References

[1] Hamer, W. J. and Acree, S. F. , "Potentiometric Method for the

Accurate Measurement of Hydrogen- ion Activity," J. Res. NBS,

23^, 647 (1939).

[2] Bates, R. G. and Macaskill, J. B., "Standard Potential of the

Ag/AgCl Electrode," Pure Appl . Chem. , 50^, 1701 (1978).

[3] Durst, R. A., "Standardization of pH Measurements," NBS

Special Publication 260-53 (1975).

O) E

el(0)

-S(0)

(2) E el(0) -S(Ar)

(3) Eel(Ar) -S(0)

< 4 > Eel(Ar)-

S < A,->

51
10. Resonance Ionization Mass Spectrometry of Iodine and Carbon (15310)

J. D. Fassett, L. J. Moore, J. C. Travis (550), T. B. Lucatorto (533),

C. W. Clark (531)

The elements iodine and carbon possess long-lived radionuclides

( 129 I, t

-|^2 = 1.7 x 109 y;

14 C, t-j^ = 5.7 x 10 3 y) that are important as environmental tracers of natural and anthropogenic activity. The measurement

of the radionuclides by mass spectrometry has provided major challenges; the

high ionization potentials (C = 11.25 eV; I = 10.45 eV) make these elements

extremely difficult to ionize by conventional means. Mass spectrometric

techniques based upon negative ionization have been the most successful,

however, these techniques have not been capable of measuring the high isotopic

abundance ratios of these elements with the requisite sensitivity to address

the most difficult tracer and dating problems.

The feasibility of ionizing both iodine and carbon by resonance ionization

mass spectrometry (RIMS) has been demonstrated. In contrast to the two-photon

RIMS that has been done for other elements, a three photon process was used in

this study to ionize the elements. This process consisted of a two-photon

transition via a virtual state followed by the absorption of a third, ionizing

photon. Theoretical calculations for carbon indicate that saturation of the

absorption cross-section for a two-photon transition is within the capabilities

of existing instrumentation. Thus, sensitivity of the ionization step will

not be sacrificed in the resonance ionization process.

The use of a two-photon transition for the ionization of both iodine and

carbon provides an extra dimension to the RIMS process by introducing the

potential of isotopic selectivity. If the photons that these elements absorb

are polarization labelled, Doppler-free spectroscopy of these elements is

theoretically possible. The isotopic shifts of both elements are believed to

be large enough that Doppler-free resonance ionization will allow the selective

ionization of one isotope. The wavelength-dependent selective ionization of

one isotope in the presence of a second would help to overcome the abundance

sensitivity limitations imposed by the mass spectrometer and allow large

isotopic ratios to be measured by conventional instrumentation. Research is

actively being pursued in this area.

The samples were prepared by drying Agl (for iodine) and graphite (for

carbon) onto the rhenium filament substrate. Sample sizes were typically

10-100 yg. The resonance ionization signals for the two-photon transitions of

iodine (279.7 nm) and carbon (287.0) were observed at nominal temperatures of

650 °C and 1750 °C, respectively. The laser beam from the frequency doubler

was focused with a 30 cm lens, before it entered the mass spectrometer

ionization region; which produced a peak power of 102 gW/cnr. Wavelength

scanning and RIMS spectra were collected for both elements. A relatively

large off-resonance background was present in both cases, probably resulting

from the dissociation/ionization of molecular species with little wavelength

dependence. The molecular ion, C2 +

, was observed for carbon. For iodine,

there existed a relatively large Ag

+ signal. Neither of these ions showed

any wavelength dependence.

52
J

):

t -

I I I I I I I L

280.8

280.6

280.4

280.2

280.0 |

•< 270.8

-| 278.6

- 278.4

-I 278.2

278.0

282.8

282.8

282.4

282.2

282.0

281.8

281.8

281.4

281.2

281.0

c

I

I 1 1 I I I I I L

287.4

287.3

287.2

287.1

287.0

286.8

286.8

288.7

288.6

288.6

287.4

287.3

287.2

287.1

287.0

288.0

288.6

288.7

286.6

286.6 e o o

« n n

luujna uoi +oM

luojjna uoi +o((

53

Figure

8.

RIMS

spectra,

ion

intensity

versus

wavelength

of

C

and

I.

(a)

idC

;

286.7-287.1

nm

(b)

13

C

+;

286.7-287.1

nm.

(c)

127I

+;

279-281

nm.

(d)

127I

+;

261-283

nm.
Carbon has two low-lying energy levels within 50 cm" 1 of the ground state,

as well as three nearly equivalent energy levels at the excited state. The

experimental spectrum is seen in figure 8. The predicted spectrum consists of

eight lines and thus, one of the predicted lines is unresolved. If the distribution of electronic state populations follows the Boltzmann relationship as previously shown for other elements studied by RIMS, then 55 percent of the

atoms leaving the filament will be in the excited state, 43.5 cm" 1 above the

ground state.

The spectroscopy of iodine showed several transitions from extremely high

excited state levels that could not have been populated by equilibrium thermal

processes. Possibly, iodine is selectively populating certain metastable

excited state levels significantly above the ground state in the molecular

dissociation process induced by the laser. Evidence for this phenomenon has

been reported elsewhere, but this is the first example observed in this

laboratory.

The ability to form and measure ions with the sensitivity and selectivity

reported here, coupled with an understanding of the basic processes involved,

extend the potential utility of RIMS to detection of many of the elements on the right hand side of the periodic table. Furthermore, the use of RIMS to

characterize vapor compositions and to identify photodecomposition products

can be applied to the study of vaporization phenomena and to tailor the

formation of atom reservoirs for specific measurement applications.

11. Thermal Release of Helium from Single Crystal Nickel (26109)

D. H. Vincent, J. T. Maki , K. S. Grabowski

The diffusion and trapping of helium, as well as other inert gases in

metals, became of great practical interest during recent years because of

material problems related to nuclear energy production, e.g., the void formation in structural materials under neutron bombardment in fission reactors and

the ablation of first wall materials in future fusion reactors. A new approach

to the problem of identifying trapping sites and determining trap binding

energies for helium in metals at low helium concentrations has been developed.

The approach is based on using ion implantations of 3 He and subsequent depth

profiling of the implanted helium using a thermal neutron beam. The thermal

release of the helium is studied by measuring the depth distribution of the

helium remaining in the sample after each anneal. While this method has been

used before to observe helium release from molybdenum, niobium, and copper,

this work will represent the first unambiguous determinations of detrapping

energies. Since the solubility of helium in metals is quite low, studies often

require the introduction of helium atoms into a metal by implantation as helium

ions in an accelerator. If such implantations are performed at ion energies

above a few keV, with the sample held at room temperature, the implanted helium

is quantitatively trapped. Each helium atom is trapped very close to the end

of its range in the metal, so that concentration profiles of the implanted

helium can be used to determine range distributions of the implanted ions. An

example of such a range distribution is shown in figure 9. If a metal sample

containing implanted helium is brought to a sufficiently high temperature,

some or all of the helium atoms will be released from their trapping sites.

54
150 keV IMPLANT

Figure 9. Helium depth profiles in nickel for a 150 keV implant (•), and for

a 250 eV surface implant (o) which represents the system resolution

function.

Once the helium is detrapped, it is released from the metal surface almost

instantaneously, indicating a very large diffusivity for helium in metals.

Most of the measurements dealing with helium in nickel have been done as desorption experiments in which helium-implanted samples were subjected to a temperature ramp, and the helium release was observed by mass spectrometry.

Implantation energies were usually low (of the order of 1 to 10 keV), and

implantation surface doses were comparatively high, so that the formation of

helium atom aggregates was likely before release. The present work differs

from previous investigations in two respects. First, a relatively high

implantation energy is used (150 keV), and the implantation dose is kept low

enough to avoid, as much as possible, the formation of larger helium aggregates

(bubbles). Secondly, helium release is observed not by measuring the amount

of gas released through the surface of the sample, but by observing changes in

the helium concentration inside the sample as a function of depth. Using this

method, it will be possible not only to measure activation energies for helium

55
detrapping, but also to relate these activation energies to specific trapping

sites along the range distribution of the implanted ions.

The activation energy for helium detrapping is likely to depend on the

particular kind of lattice defect at which the helium is trapped. In order to

reduce the variety of trapping sites as much as possible, single crystal nickel

samples are used for helium implantation. This confines the helium traps

mainly to isolated vacancies and excludes trapping at extended defects such as dislocations and grain boundaries.

Samples for helium implantation were prepared by cutting slices of

approximately 1 mm thickness from a single crystal nickel rod. One surface of

each slice was carefully polished and its crystallinity tested by obtaining a Laue x-ray pattern. These patterns indicate that the normal of the samples is

well away from any ion channeling direction, so that helium ion channeling

should not occur during implantation if the sample is perpendicular to the ion

beam axis.

A first set of samples has been implanted with 3 He ions at an ion implantation accelerator at the Naval Research Laboratory. Precautions were taken to

prevent ion beam heating of the samples during implantation. Ion beam currents

of approximately 300 nA were used, and implantation surface doses were 2xl016

, IxlO* 6

, 6x1

1

, and lxlO15 3 He-ions/cm2

. The largest surface dose (2x16 3 Heions/cm2

) produced a maximum concentration of about 0.9 atom percent 3 He at

the peak of the range distribution for 150 keV 3 He ions. This can be compared

with the solubility of helium in nickel at room temperature which is 1x10 7 atom percent.

The depth distribution of the helium after implantation was measured at

the neutron depth profiling facility at the NBS research reactor. The distance

from the surface of specific implanted 3 He atoms was determined by measuring

the energy loss of protons from the nuclear reaction 3 He(n,p) 3 H. This reaction

has a large cross section at thermal neutron energies (5237 barns) and produces

protons with an energy of 572.5 keV. The energy spectrum of protons emerging

from the surface of the sample as it is irradiated with thermal neutrons was measured with a silicon surface barrier detector. This energy spectrum was converted to a depth distribution for the implanted 3 He atoms with the aid of

the known proton stopping power (dE/dx) in nickel. Figure 9 shows the depth

distribution of helium atoms in a sample implanted with 150 keV 3 He- ions to a surface dose of 2xl016 3 He-ions/cm2

. This depth distribution is broadened by

the energy resolution of the detector and the associated electronic equipment.

To indicate the width of the resolution function, a spectrum from a surface

implantation of helium ions (250 eV implantation energy) is also shown in

Figure 9. The mean projected range of the 150 keV implant is 372 nm. This

compares well with the value of 367 nm obtained by interpolation from a set of

theoretical mean ranges at various energies given by Biersack elt aK [1].

Annealing experiments on the implanted samples are in progress. Activation

energies for detrapping of the implanted helium will be determined by a combination of isochronal and isothermal anneals. It is planned to extend the

present work to include 3 He profiling and thermal release studies of nickelbased metallic glasses. Both the trapping efficiencies and the detrapping

behavior will be investigated. A further application of the technique of 3 He

56
depth profiling will be the decoration of radiation-induced defects in pure

metals, in metallic glasses, and in silicate glasses. Of these, the silicate

glasses may be the most promising materials for an application of this method,

since helium is known to permeate these materials easily at room temperature.

Preliminary experiments on this new application of 3 He depth profiling are

planned.

Reference

[1] Biersack, J. P., Fink, D., Henkelmann, R. , and Muller, K. , J.

Nucl. Mater. 85/86, 1165 (1979).

12. Determination of Selenium in Subcellular Fractions to Study the

Glutathione Peroxidase System (15310)

R. Zeisler, A. G. Katki , C. E. Myers

Cardiac mitochondria generate significant quantities of hydrogen peroxide

as a by-product of normal metabolism. This toxic product must be eliminated

before it causes severe damage to mitochondria and surrounding organelles.

For this reason, the existing defenses of mitochondria to hydrogen peroxide

attack are of interest. There are two major enzyme classes able to destroy

hydrogen peroxide: catalases and glutathione dependent peroxidases. The

latter are all known to be soluble enzymes which contain selenium in their

active sites. Indeed, tissue activity of this enzyme appears to be strictly

dependent on dietary selenium. Selenium deficiences may result in diseases

which have been associated with a resultant lack of glutathione peroxidase

activity. This enzyme class may also be involved in protection against

chemical carcinogens and radiation damage. However j there are considerable

variations in dietary selenium levels in man and animals. Also, the existence

of healthy, selenium deficient subjects suggest that other mechanisms of

peroxidase removal must exist. Katki and Myers [1] showed the presence of

membrane bound glutathione peroxidase-like activity in mitochondria which may

be selenium independent.

The interrelationships among selenium, peroxide detoxification mechanisms,

and enzyme separations have been studied. In addition, the influence of drugs

on the peroxidase system has been investigated using selenium determinations

in enzyme and cell fractions. Instrumental as well as ultrasensitive radiochemical neutron activation analysis procedures have been implemented for the

determination of selenium and other essential trace elements in a series of

samples provided by the National Cancer Institutes (NCI). In an attempt to

purify a membrane-bound, selenium-independent, glutathione peroxidase, beaf

heart mitochondria were investigated for the presence of this new enzyme.

After preparing mitochondria and intermembrane space by digitonin treatment,

the preliminary separation scheme resulted in purified enzyme fractions in

which selenium and other trace elements were determined (figure 10). The

determination of selenium in the final preparation is of utmost importance

since this is the only true measure of the dependence of the peroxidase system

on selenium concentration. The newly developed radiochemical activation

57
Figure 10. Specific Activity and Selenium Concentrations in Enzyme

Fractions.

Solid Line: Specific peroxidase activity, 0 to 30 nmoL/min.

mg (protein) --Reduction of Peroxide

Broken Line: Specific transferase activity, 0 to 4 nmoL/min.

mg (protein)--Reduction of Peroxide

Shaded Areas: Selenium concentration, 0 to 5 yg/g (dry

matrix) in freeze-dried pooled fractions. In fractions 24

to 28 and 42 to 48, selenium is below the INAA detection

limit of 0.7 yg/g.

analysis procedures provide a sensitivity of 'vlO" 12

g for selenium, i.e., the

selenium concentration in nanogram amounts of enzyme can be used to quantify

the enzyme, as highly purified enzymes become available.

Future work will utilize the ability to determine nanogram quantities of

enzymes to identify the proteins directly on chromatography columns or on two-dimensional protein maps.

Reference

[1] Katki, A. 6. and Myers, C. E., "Membrane-bound Glutathione

Peroxidase-Like Activity in Mitochondria," Biochem. Biophys.

Res. Com., 96, 85 (1980).

58
13. The Measurement of Natural Variation in the 32 S/ 34 S Ratio in Atmospheric

Samples (15310)

W. R. Kelly, P. J. Paulsen

A new procedure for the measurement oj sulfur isotopic ratios by thermal

ionization mass spectrometry using the AsS molecular ion has been developed

during the last two years. Previous reports [1] provided examples of precise

and accurate sulfur determinations by isotope dilution in a variety of Standard

Reference Materials. The chemical blank (^0.3 yg S) is the limiting source of

uncertainty for quantities of sulfur below 100 yg and the calibration of the

tracer is the limiting source of error (^0.2% rel., Is) above this amount

[1 , 2]. Another important application which has been explored during the past

year is measurement of natural variations in the 32 S/ 34 S ratio.

Sulfur has four stable isotopes with the following average relative

abundances: 32 S ^95.02 percent, 33 S ^0.75 percent, 34 S ^4.21 percent, and

36 S ^0.02 percent. The abundances of the sulfur isotopes vary in nature as a result of mass dependent fractionation principally during S-0 bond breaking in

sulfur reducing bacteria. Over geological time this has resulted in large

variations in the 32 S/ 34 S ratio. These differences are expressed as enrichments

or depletions in the 34 S abundance relative to Canyon Diablo meteoritic troilite

(FeS) defined by the following equation:

34

o o/oo =

( 34

S/

32

S) sample _-|

_ ( 34

S/

32

S) STD

x 1000

The vast majority of samples found in nature fall between +40 and -40 6 34 S

units, but samples with 6 34 S values as large as -65 and +95 have been observed.

This variation has been used to trace the origin of ore and oil deposits,

natural waters, and sulfur in the atmosphere [3]. Of particular interest is

the problem of determining the source of atmospheric sulfur compounds at a receptor site. The main thrust of our work has been the development and

refinement of the thermal ionization technique for the determination of sulfur

isotopic ratios on small samples. As a demonstration of the capabilities of

the technique developed, 6 34 S values have been determined in a number of samples

collected by Project Airstream after the eruption of the El Chichon volcano

in southern Mexico. Project Airstream has been sampling the stratosphere for

more than a, decade in a transect from 60 °N to the equator [4]. The eruption

of El Chichon in March- April 1982 had the largest impact on the atmosphere of

any eruption since the 1883 eruption of Krakatoa. The main impact has been

the large amount of S injected into the stratosphere, estimated to be more

than 1

6 T or about 10 times more than that from Mount St. Helens. The source

of this enormous amount of sulfur is not completely known. Aqueous extracts

of filter samples were obtained through the cooperative efforts of E. J. Mroz

of Los Alamos Scientific Laboratory and W. H. Zoller of the University of

Maryland. Values of 6 34 S have been determined in samples from three different

flights of Project Airstream. The chemical and mass spectrometric procedures

used are similar to those described in previous reports. Measurement precisions were about 0.1 percent. The results given in Table 7 are the first

59
Table 7. 6 34 S o/oo Values in Project Airstream and El Chichon Samples.

Sample S

Sample yq s Sample S 6 34 S o/ooq

Flight 4 (4/20/82)

Filter 8 31 26 +13.2 +2.2

-3.3

9 172 191 +32.3 +0.7

-1.0

10 201 183 +29.2 +1.5

-1.9

11 49 288 +28.9 +0.7

-0.9

Flight 5 (7/21/82)

Filter 5 41 40 +3.4 +2.7

-2.9

7 63 45 +3.7 +1.7

-1.9

8 67 66 +3.3 ±1.6

10 114 81 +5.0 +1.2

-1.3

11 68 57 +4.3 +1.6

-1.8

Flight 6 (10/27/82)

Filter 7 118 74 +11.0 +1.5

-1.8

8 131 87 +11.6 +1.4

-1.7

9 159 99 +13.2 +0.5

-0.7

10 115 100 +11.8 +1.1

-1.3

11 123 103 +14.5 +1.7

-2.0

El Chichon

Elemental S 300 6000 +0.78 ± 0.4

Lake Water %200 4000 +17.0 ± 2.0

Uncertainties are computed as the linear sum of the measurement

precision (2s) and the bias due to chemical blank.

60
sulfur isotopic measurements on Project Airstream samples. The sample sizes

shown in column 2 range from about 30 to 200 yg S. Column 3 lists the (sample

S/blank S) weight ratios. It was assumed that the blank could have a composition of 6 34 S o/oo = ±40 which accounts for the asymmetry in the uncertainties

given in the last column. The variations in 6 34 S o/oo range from +0.8 to +32.

A graphical representation of a portion of the data is given in Figure 11 (a)

and (b) where the 6 34 S values have been plotted on contour plots from Mroz

et al_. [5], Figure 11 (a) constructed with data from before the eruption of

El Chi chon shows a homogeneous distribution of sulfate in the atmosphere.

Figure 11 (b) constructed from data after the eruption shows a very heterogeneous

distribution of sulfur with extremely high values at 19 km at latitude 10 °N.

The very large 6 34 S values of +32, in this region indicate that this is not

juvenile sulfur from the El Chichon magma but may be due to the injection of

overlying evaporites deposits which can have high 6 34 S values. Further

interpretations must wait for additional data.

+32 +29

Figure 11. Contour plots of sulfate, concentrations before (a) and after (b)

the eruption of El Chichon volcano. 5 34 S o/oo values are plotted

for four stratospheric samples (b).

References

[1] Paulsen, P. J. and Kelly, W. R. , "Determination of Sulfur by

+ Isotope Dilution Thermal Ionization Mass Spectrometry as AsS

Ions," submitted to Anal. Chem.

[2] Kelly, W. R. and Paulsen, P. J., "Precise Determination of

Sulfur at High Concentrations by Isotope Dilution Thermal

Ionization Mass Spectrometry," submitted to Talanta.

[3] Krouse, H. R. , "Sulur Isotopes in Our Environment," in Handbook

of Environmental Isotope Geochemistry , Vol . 1 , Tte Terrestrial

Environment, 1980.

61
[4] Sedlacek, W. A., Mroz, E. J., Lazrus, A. L., and Gandrud, B. W. , "A

Decade of Stratospheric Sulfate Measurements Compared with Observations of Volcanic Eruptions," J. Geophys. Res. 88, 3741-3776 (1983).

[5] Mroz, E. J., Mason, A. S., and Sedlacek, W. A., "The Stratospheric Sulfate from El Chichon and the Mystery Volcano,"

submitted to Geophyd. Res. Letts.

14. Evaluation of the Isotope Dilution Method for Ultratrace Chromium

Concentrations (15601)

K. A. Brletic, L. J. Powell

The accurate determination of chromium concentrations in samples containing

less than 100 ng/g of chromium is a problem of major concern to nutritionists.

Many of the results published over the past 10-15 years are unreliable and, as

a result, estimates of chromium concentration in biological fluids have varied

by more than a factor of 1000 during this period. A long-term goal of this

project has been to develop a method for the accurate measurement of chromium

concentrations at the sub-nanogram per gram level. This year's efforts resulted

in the certification of four environmental and clinical Standard Reference

Materials, several of which contained less than 20 ng/g of chromium.

Last year's annual report outlined a method for the mass spectrometric

analysis of chromium capable of increased sensitivity over previous methods.

At that time the method had received only minimal evaluation; and, in fact no determinations were made at the sub-100 nanogram per gram level. Briefly

described, the chromium is separated from the matrix by solvent extraction into

methyl isobutyl ketone and is then back extracted into water and reduced. The mass spectrometric procedure requires the sequential drying of silica-gel,

approximately 200 nanograms of chromium(III) nitrate, and boric acid onto a rhenium filament followed by high temperature drying. This loading technique

yields ion currents of l-4xlO_li A.

To work at this level, a thorough assessment of the analytical blank had

to be made. Efforts to reduce the blank included further purification of

reagents and more extensive cleaning of apparatus. In addition, an attempt was made to reduce the quantities of reagents used in the chemical separation

procedure of the analysis. This, however, resulted in lower recovery of the

chromium as well as a greater concentration of impurities in the final sample,

which inhibited the ionization of the chromium in the mass spectrometer.

Overall, these efforts led to a four-fold reduction in the magnitude and

variability of the analytical blank.

The concentration of chromium was determined in SRM 1643b, Trace Elements

in Water; SRM 909, Human Serum; SRM 2670, Toxic Metals in Urine (Elevated and

Normal Levels); and SRM 1549, Powdered Milk. The average values and associated

uncertainties reported at the 95 percent confidence level are summarized in

Table 8.

62
Table 8

SRM 2670, Urine - Elevated

Normal

SRM 1643b, Water

SRM 909, Human Serum

Concentration (ng/g)

18.6 ± 0.3a

89.5 ± 3.0

a

84.5 ± 6.9a 12.4 ± 5.8a

SRM 1549, Powdered Milk < 10.0

a95 percent confidence level.

The analytical blanks ranged from 1-15 nanograms depending upon the

complexity of the analytical procedure. Large (multigram) samples were used

to offset the effects of the blank. For SRM 1549, Powdered Milk, the level of

chromium in the analytical blank was greater than the level in the sample and,

therefore, the determined concentration must be viewed as an upper limit.

In summary, the method outlined above makes it possible to measure chromium

concentrations at levels of 20 nanograms per gram with an accuracy of a few

percent. The analytical blank, however, is clearly a limiting factor in terms

of increased sensitivity, and thus remains a major barrier, particularly when

the total amount of chromium in the sample is less than 10 nanograms. Additional research is needed to reduce the analytical blank to the pi cogram level

to adequately satisfy many of the analytical requirements of clinical and

nutritional studies. However, this technique is sufficiently useful and

accurate to meet many of the needs for chromium analysis.

15. Ion Optics of Single and Double Stage Mass Spectrometers (15310)

I. L. Barnes, P. Morales

Historically high precision or "analytical" mass spectrometers have been

constructed so that the ion beam enters the magnetic field normal to the

magnetic pole faces. While this permits instruments to be constructed with

well defined and predictable geometries, there are severe constraints, the two

most important of which are the lack of focussing in the vertical or "z"

direction and the fact that the dispersion (or resolution) is directly proportional to the magnet radius (i.e., to increase the dispersion by a factor of

10, the magnet must be 10 times as large). Greater dispersion would permit

increased accuracy in the measurement of isotopic ratios, especially very large

ratios. This would also allow the use of multiple collectors, again increasing

the accuracy of the measurement.

A program is underway to develop a theoretical background for the ion

optics of mass spectrometers using non-normal entry of ion beams. This work

is being carried out in conjunction with researchers at the Institute of Physics,

University of Mexico. Such instruments would produce increased dispersion (for

63
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64

Figure

12.

Plot

of

cross

section

of

ion

beam

at

the

focal

point

fora

beam

with

"z"

focussing

(12a)

and

without

"z"

focussing

(12b).

Each

single

digit

number

represents

the

position

in

the

final

beam

of

that

many

rays

originating

from

random

points

ona

filament

0.020

cm

wide

by1

cm

high.

Since

only

single

digits

are

allowed,

the

letters

A-Z

represent

10-36

rays.

One

thousand

original

rays

were

selected

and,

in

this

case,

1000

were

collected.
a given radius magnet) and would also give simultaneous focussing in the

horizontal and vertical directions. Since precise knowledge of the value of

the stray magnetic field is an important part of the theoretical background,

previous work involved careful measurements of the stray field of an NBS

designed magnet and the development of a mathematical expression describing

the field. During the past year these measurements have been repeated on a magnet which could be adjusted to give different width gaps. These data are currently being processed to determine the constants which give the best fit.

The computer programs TRANSPORT and TURTLE have been modified to include the

expression for a specific magnet and the output of these programs gives much

more realistic results. An example of the ion beam cross-section at the focal

points of two systems is shown in figure 12.

A new program "MASMEX", which uses only fundamental physical expressions

for the position of the ion beams coming from as many as 27 points on the

representation of a real filament, was written here last year. The program

has the advantage that the coordinates of the beams may be obtained at any

point in the complete system so that the effects of small changes in the

magnetic field may be examined. During this past year a fundamental "bug" was discovered which has now been corrected. A plotting subroutine is being added

which will reduce the large amount of data and make the program easier to use.

During the next year, we plan to add a segment to each program to model

the focussing properties of the ion source so that realistic ion beams focussed,

partially focussed, and defocussed may be examined at any point in the complete

mass spectrometer.

16. Development of Reference Materials for Acid Rain Studies (15310)

W. F. Koch, G. Marinenko, Y. C. Wu

Acid rain is a topic of national and international concern. The ramifications of this phenomenon involve social, political, economic, environmental

and energy- related issues. To assess and propose meaningful remedial strategies,

chemical analyses must be done on rainfall samples. Since the acid rain

problem is not restricted to specific times or locales, these analyses must be

performed over long periods of time at numerous locations around the world.

The analyses are carried out both in the field and in laboratories. Since

1975, the National Bureau of Standards has had an agreement with the US EPA to

provide a means of intercalibrating the various measurement stations and of

establishing a foundation for long term trend analysis. Initially, the project

entailed the production and characterization of audit materials, dubbed.

Simulated Precipitation Reference Materials (SPRM). In 1980, the scope of the

project was significantly broadened to include research leading to the development of a Standard Reference Material (SRM) for acid rain. In addition,

measures aimed at improving the accuracy and reliability of the analytical

methods used in acid rain studies were to be evaluated. In the past year,

significant progress has been made toward achieving the research goals.

A major change has been made in the composition and storage of the fifth

series of SPRM. This series has been stored in polyethylene bottles rather

65
than glass ampoules and consists of a set of five solutions, all concentrates

requiring a 50-fold dilution before they can be used. Three of the solutions

have been characterized for the major anions and cations found in rainwater,

as well as pH, acidity, and conductivity. The other two solutions in the set

contain trace metal ions stabilized with 0.5 mol/L nitric acid.

The move to polyethylene bottles was necessitated by the fact that the

moderately acidic solutions are not stable in glass ampoules. This has been

established through several long term stability studies. The results of one

such study is shown in Table 9. A solution prepared in May 1981 was split

between glass ampoules and polyethylene bottles. A divergence between the

values for pH and conductance was apparent after the first month and continues

to date. In another experiment the pH and conductivity of a dilute solution

of sulfuric acid (^pH 4) in polyethylene has remained stable for over three

years.

Table 9

Glass Polyethylene

Date fid. Conductance fiH Conductance

6/81 4.12 36.0 yS/cm 3.87 52.4 jiS/cm

3/82 4.30 29.3 3.90 53.0

1/83 4.50 23.9 3.85 54.0

4/83 4.34 27.1 3.84 54.8

7/83 4.44 26.6 3.91 54.7

Three new studies have been initiated this year to enhance our knowledge

of the stability of anions and hydrogen ion in dilute solutions. One study

involved the monitoring of SPRM (V) samples that were stored in polyethylene

following a 50-fold dilution. Preliminary results are very encouraging.

Another set of solutions has been prepared containing phosphate as well as the

other major cations and anions. This was done to simulate the composition of

rainwater in the Midwest and plains states. Early indications are that such

solutions, particularly when dilute, are not stable. Additional studies on these solutions using a bactericide have yet to be carried out. The third

study entailed the collection, characterization, storage, and monitoring of a sample of natural rainwater. It is still too early to draw any conclusions

about the stability of these solutions.

Research in methods development has focussed primarily on the measurement

of pH in low ionic strength solutions. The residual liquid junction potential

resulting from the use of buffer solutions to calibrate the electrode system

can seriously bias measurements of the pH of rainwater. Work is underway to

account for this phenomenon and to determine if one type of junction performs

better than others. Also in progress is the preparation of two strong acid

solutions (nominally pH 3.8 and 4.3) which will be analyzed for pH using

hydrogen, Ag/AgCl cells without liquid junctions. This is a preliminary study

to test the feasibility of using such solutions for the calibration of pH

measurements in rainwater samples. An inter! abbratory comparison using the

solutions is planned for this fall.

66
The overall goal of this project is to provide quality assurance for the

analytical measurements of rainwater samples as part of the National Acid

Precipitation Assessment Program. It is anticipated that the research involving

measurements in wetfall will continue for two more years. At the same time,

it is planned to expand the project to include dry deposition studies. Other

related projects include fundamental studies in the measurement of pH and

conductivity and will continue on a long-term basis.

17. The Development of a Pulsed Thermal Atom Source For Use in RIMS (26108)

J. D. Fassett, R. W. Shideler, L. J. Moore

The development and application of a resonance ionization mass spectrometer

(RIMS) system is described in accompanying reports. This system consists of a pulsed laser, operating at 10 Hz, and a continuous thermal atomization source.

It has been demonstrated that thermal sources can be used to produce neutral

atom beams for a wide range of elements. However, the duty cycle mismatch

between the continuous atom source and the laser results in a substantial loss

in sample utilization efficiency, i.e., sensitivity of the process. To exploit

the inherently high photoionization efficiency of the laser and ultimate

sensitivity of RIMS, a better match is required between the ionization and

atomization processes.

The atomization and ionization processes can be better matched by either

pulsing the atomization source or by using a higher repetition rate laser or continuous (CW) laser for photoionization. Work is underway in other laboratories to develop CW RIMS systems [1]- With the present state of laser

technology, CW systems have many disadvantages relative to pulsed laser

systems. They lack both the elemental coverage and the ionization efficiency

of pulsed systems, and thus are applicable only to specialized problems. The

atomization process can be pulsed by either ablative techniques, such as ion

and atom sputtering or laser heating, or by pulsed vaporization. Ablation has

definite promise and is being investigated by several laboratories. However,

the energetics of these ablative processes and their inability to selectively

produce atoms strongly suggests that their general application needs to be

firmly established.

A pulsed thermal vaporization source, based upon the known ability to

produce stable neutral atom beams whose temperature- intensity behavior is

classically defined, was constructed. The nature of the thermal atom pulse

was evaluated by temporal scanning of the atomization pulse relative to the

laser pulse. Changes in the atomization filament were required to achieve the

most pronounced pulsed atom beam. When iron samples were used to test this

system, a 30-fold improvement in sample utilization over the continuous atom

source was demonstrated for the pulsed thermal vaporization source.

The pulsed thermal source was made by modifying the solid-state, constantcurrent filament supply that has been developed and used in this laboratory

for thermal ionization. This supply provides up to 10 amps of current. In

the pulsed mode of operation, a 10 amp current pulse is applied to the filament

for a selected period of time. The 10 amp pulse can be applied on top of an

67
established base current level. The thermal pulse can be triggered in conjunction with the laser or a delay can be incorporated such that the laser pulse

is triggered at the time of maximum atom density.

The temporal nature of the thermal pulse was determined by delaying the

laser relative to the pulser. A photodiode detector of the laser pulse was used to trigger both an oscilloscope and a pulse generator. The pulse generator

which provided a pulse delay (ns to ms) was used to trigger the thermal pulser.

The oscilloscope was used to monitor the position of the thermal pulse relative

to the laser pulse. The ion signal versus the time delay was determined by

manually scanning the relative position of the two pulses in the 100 ms region

between pulses. The ion signal was integrated at each time position in the scan for 20 s or 200 laser pulses.

The first experiments with the standard Re filament assembly indicated

that the mass of the filament limited its temperature response and thus, sample

utilization. As a result, a second filament was prepared whose length and

width were reduced. For this filament, a 4.5 ms current pulse produced the

experimental signal versus time curve that is illustrated in figure 13 (a).

The signal decayed to 50 percent of maximum in 3.5 ms and to one percent of

maximum in 30 ms. In contrast to the standard filament, the baseline was reached between thermal pulses. A sample utilization improvement factor of

12 is calculated from this curve.

Figure 13. Profile of thermal atom pulse with miniaturized filament

assembly. RIMS signal versus time after thermal pulse

initiation: (a) no current offset and 4.5 ms current pulse

width; (b) 0.9 amp offset and 3.0 ms current pulse width.

68
Since this second miniaturized filament reached baseline between thermal

pulses, an attempt was made to apply the current pulse on top of a constant

current base level. A base level of 0.9 amps was established and midlevel

ionization signal achieved with a 3 ms pulse. The experimental signal-versustime curve also is illustrated in figure 13 (b). In this experiment, it took

less than 1 ms to decay to 50 percent of the maximum. However, it still

required 30 ms to decay to one percent of the maximum signal. The best

observed enhancement, a factor of 31, was achieved in this case.

Further attempts to reduce the size of the filament were unsuccessful.

It is obvious that reducing the size of the filament to achieve the fastest

heating response must be balanced against the ability to load a sample upon the

filament such that the sample sees an isothermal heating pattern. Improvements

in sample loading will be required to address this problem. The 30-fold increase

in sample utilization improves the_efficiency of the pulsed atomization-pulsed

ionization RIMS system to about 10” 3

. The elemental coverage and analytical

sensitivity make the potential applications extremely exciting.

Reference

[1] Miller, C. M. and Nogar, N. S., Anal. Chem. , 55, 1608 (1983).

18. Characterization of Biological SRM's Using Atomic Spectrometry Techniques

(15601)

T. C. Rains, T. A. Rush, T. A. Butler, M. S. Epstein, R. L. Watters, Jr.

There is increasing concern about both the essential lity and toxicity of

substances in man's diet. An important aspect of characterizing the intake of

such substances is the trace element analysis of foods. The accumulation of

certain elements in the body can be monitored by analyzing trace elements in

biological fliuds. The accuracy of these analyses is of great concern to

nutritionists, and is, in part, assured by the use of well characterized

reference materials. Two biological SRM's are being prepared and analyzed for

this purpose. Numerous major, minor, and trace elements are being determined

in a large supply of powdered milk to be issued as an NBS SRM. In addition,

a similar program is underway in which samples of freeze-dried urine, having

normal and elevated levels of trace elements of interest, are prepared and

analyzed.

The elemental concentrations in milk and urine vary over a wide range.

Biological matrices which have a relatively high concentration of Na, Ca, or

Mg produce interelement effects during the analysis of most analytes by

electrothermal atomic absorption spectrometry (ETAAS). This difficulty has

been largely alleviated by using matrix modification techniques and the L'vov

platform. In the direct current plasma emission spectrometry technique (DCP),

a solution of Li (1000 ug/mL) was added as a spectroscopic buffer. With the

inductively coupled plasma (ICP) technique, high concentrations of cations did

not create any difficulty. However, it was essential to match the acid

concentration to achieve optimal precision and accuracy.

69
The major difficulty encountered in the determination of trace elements

such as Cd, Fe, and Pb is contamination. The sources of contamination include

the apparatus, the reagents, the environment, and the analysts. Glass of any

kind is attacked by strong acids and must not be used. Teflon-containers have

been evaluated by Murphy [1] and are acceptable for these analyses. Another

source of contamination is the plastic cups used routinely with the automatic

pipetting system of the ETAAS instrument. Reused plastic cups which had been

soaked overnight in 20 percent HN03 and then rinsed with copious amounts of

distilled water produced significant blanks. To minimize the difficulty

encountered in Fe, Cd, and Pb analyses, only new cups were used. To ensure

low and reproducible blanks, each new cup had to be soaked according to the

previously described procedure.

Tables 10 and 11 show the results obtained for SRM 1549 (Powdered Milk)

and SRM 2672a (Urine). The powdered milk was digested with a mixture of HN03 and HC104 and then the solution was analyzed for all the major and trace

elements except Si and Hg. To prevent losses of mercury during the digestion,

the sample was digested under reflux conditions. Silicon was solubilized with

a sodium carbonate fusion in separate solutions. For the analysis of freeze

dried urine, the urine was reconstituted with water. The DCP analysis was performed on the reconstituted urine after appropriate dilutions were made

and lithium was added as a spectroscopic buffer. For the FAAS and ETAAS

analyses, the urine was digested in HN03 and the appropriate matrix modifier

was added.

In conclusion, the use of matrix modifiers and spectroscopic buffers

greatly improved the precision and accuracy of FAAS, ETAAS, and DCP analyses.

In addition, the care taken to minimize the sources of contamination significantly reduced blank levels. Further work is needed to improve the detection

limits of silicon in biological materials.

Reference

[1] Murphy, T. J., "The Role of the Analytical Blank in Accurate

Trace Analysis," NBS Spec. Publ. 422, 7th IMR Symposium, U.S.

Gov. Printing Office, August 1976.

70
Table 10. SRM 1549, Powdered Milk.

Element Method Concentration, Wt. %

a

Ca ICP 1.27 (0.01)

K ICP 1.79 (0.01)

FES 1.70 (0.01)

Na ICP 0.501 (0.002)

P DCP 1.052 (0.009)

yaZa

Cd ETAAS 0.031 (0.009)

Co ETAAS <0.1

Cu DCP 0.68 (0.05)

Fe ETAAS 2.5 (0.3)

Hg CVAAS 0.0004 (0.0001)

Mn DCP 0.29 (0.03)

Pb ETAAS <0.1

Si DCP <50

Sn DCP <0.5

Zn FAAS 46.3 (0.8)

ICP 45.2 (0.6)

a Average of replicate determinations, one standard

deviation of a single determination in parentheses.

Element

Table 11.

Method

SRM 2672a, Freeze Dried Urine.

ug/mL -

Normal 3 Elevated3

Ca FAAS 104 (1.8) 105 (1.2)

DCP 105 (0.9) 106 (0.7)

Cd ETAAS 0.0023 (0.0001) 0.97 (0.006)

Cu DCP 0.126 (0.008) 0.370 (0.016)

ETAAS 0.128 (0.013) 0.362 (0.012)

Cr ETAAS 0.0098 (0.0017) 0.183 (0.010)

Pb ETAAS <0.005 0.099 (0.011)

Hg CVAAS <0.002 0.105 (0.003)

aAverage of replicate determinations, one standard deviation of a single determination in parentheses.

FAAS - Flame atomic absorption spectrometry

DCP - Direct current plasma spectrometry

ETAAS - Electrothermal atomic absorption spectrometry

CVAAS - Cold Vapor atomic absorption spectrometry

ICP - Inductively coupled plasma

FES - Flame emission spectrometry

71
19. Measurement of Iodine Concentrations and Isotope Ratios at Environmental

Levels (15310)

R. M. Lindstrom, G. J. Lutz

Iodine-129, a long-lived (ty

2 = 15.7 My) isotope produced in high yield

in uranium fission, is an ideal tracer for assessing the environmental impact

of nuclear testing and nuclear energy production. Because of its long half-life

and low energy of its radioactive emissions, 129 1 cannot be measured directly

by radiation counting at the present-day environmental level of <10” 6 Bq/g,

which corresponds to <109 atoms/g or <2xl0" 13 g/g. Neutron activation analysis

is a sensitive method for measuring concentrations of 129 I and stable 127 I found in environmental samples, the 129 I being converted to the more readily

measured 130 I isotope having 10 5 times as much activity. The procedure used

at NBS involves the separation of iodine from the sample by combustion, intense

neutron irradiation, removal of interfering radioactivities by gas-phase

separation using a selective ion-retention medium, and low-level gamma-ray

assay.

In the early phases of this work, repeated measurements of samples

expected to be low in 129 I yielded occasional high concentrations, many times

the level expected. Contamination of laboratories by this commercial lyavailable isotope in the course of tracer work is insidious and difficult to

detect because of its low-energy emissions and long half-life. Stringent

precautions must be taken to prevent contamination of samples containing

background levels of 129 I. Pre-irradiation sample manipulations at NBS are confined to laboratories and apparatus where 12 ^I has never been used. All

sample handling is done in a clean area within one laboratory, in which the

air supply to the work bench is filtered through activated charcoal to remove elemental iodine and through a HEPA filter to remove particulates. Oxygen

flowing over the sample during combustion is filtered through silvered quartz

wool and activated charcoal. The combustion tube and boat are precleaned by

ignition in flowing oxygen, and the activated charcoal for the combustion trap

is crushed and sieved in a class 100 clean room and baked in vacuum before

use. Cross-contamination is avoided by using a new combustion tube and boat

for each new material; agreement among replicate samples of the same material

burned in the same combustion tube is a stringent test of the blank. These

measures have been sufficient to eliminate entirely the occasional high values

seen earlier, so that the blank is now comparable to the detection limit.

During the past year, reproducible measurements of 129 I at the sub-pg/g level

were performed routinely.

Stable 127 1 is measured in the same samples by a short irradiation and

gamma assay before the long irradiation. In order to avoid the uncertainty

associated with yield determination, an epithermal irradiation capability in

the NBS Reactor has been established, allowing non-destructive measurements

of stable iodine to be made in botanical materials down to a few tenths of a microgram per gram.

NBS measurements help to provide quality control to other laboratories

involved in monitoring environmental levels of 129 I. Two Standard Reference

72
Materials have been characterized to assist in assuring comparability. SRM

1572, Citrus Leaves, was found to have a 129 1 concentration of (2 ± 1 ) xl

8 atoms/g (0.04 ± 0.02 pg/g), and in SRM 1646, Urban Particulate, (17 ± 5)xl0" 8 atoms/g. The 1 29 I/i 2 ^ I isotopic ratio in both materials is 2xl0" 8

, which

appears to be characteristic of the present-day environmental average in the

northern hemisphere. For comparison, the 1 29 1/i 27 1 ratio in the pre-1945

biosphere has been estimated to be 2xl0~ 12

, near unity in uranium fission and

10" 6 near reprocessing plants.

Emphasis in the coming year will be on improving the sensitivity of 129 I measurements by reducing the continuum background due to fission products in the

gamma spectrum, and by irradiating at as high a flux as the triple-capture

interference will allow. In the longer term, specificity and probably sensitivity can be improved by the use of coincidence counting techniques tailored

to the decay scheme.

20. Certification of Uranium Isotopic Standard Reference Materials (15310)

J. W. Gramlich, L. A. Machlan, J. R. Moody

Highly accurate uranium isotopic standards are necessary to calibrate

mass spectrometers used in the nuclear industry for the precise isotopic

analysis of nuclear materials. The mass dependent isotopic fractionation,

inherent in the mass spectrometric ionization process, must be calibrated

against standards of known isotopic composition if accurate results are to be

obtained. This information is necessary for the accountability and safeguarding of nuclear materials. The purpose of this project was to reissue

several uranium isotopic SRM's which are used to calibrate mass spectrometric

measurements. In addition to the reissuance of current uranium isotopic

SRM's, this project will yield accurate measurement of the isotopic composition

of SRM 960, a uranium metal certified only for uranium assay. Since there is no National standard of uranium with natural isotopic composition that is

certified for isotopic composition, the certification of this SRM will be a significant contribution to the nuclear community.

The new SRM's, at nominal 235 U abundances of 3, 2, and 0.5 percent and in

the form of U 3 0 8 , were obtained from Oak Ridge National Laboratory. The newly

developed semi -micro Davies-Gray titration was used in both the preparation of

synthetic mixtures for the determination of the major isotopes, 235 U and 238 U;

and the determination of the minor isotopes, 234 U and 236 U. Spark source mass spectrometry was used to verify that no impurities were present which could

interfere with the titration or with the mass spectrometry measurements.

The synthetic mixtures for the 235 U and 238 U determination were prepared

by combining weighed aliquots of two separated isotope solutions, 23

U and 238 U,

whose concentrations had been accurately and precisely determined by the semimicro Davies-Gray titration method. These synthetic mixtures, with known

isotopic ratios, were used to calibrate the mass spectrometers used for the

isotopic assay of the SRM materials. The minor isotopes, 234 U and 23

U, were

measured using isotope dilution. Known amounts of each SRM were spiked with a known amount of 233 U, SRM 995. The minor isotopes in these three new materials

are considerably lower in concentration than in the old SRM's, thus increasing

73
the difficulty of accurate measurements. Low mass scatter from 238 U interferes

with the baseline measurements for 236 U: at a ratio of 106 for 238y/236y ^-,-5 can become a significant contribution to the errors in the 236 U measurements.

A similar relationship exists between 235 U and 234 U. By optimizatinq the

analytical and instrumental parameters, the minor isotopes 234 U and 236 U were measured with an average uncertainty (Is) of 0.5 percent. Measurements were

made both under computer control and by manual scanning followed by hand

calculation of the data: the results of the two methods of data collection

are in good agreement. The isotopic measurements required for certification

of these SRM's are essentially complete and the statistical evaluation of the

data is in progress.

Based on the precision obtained using the Davies-Gray titrations (<0.01

percent), as well as the quality of the mass spectrometric measurements, it is

expected that the new uranium isotopic standards will be substantially more accurate than the presently available standards. The issuance of these new

SRM's will conclude this research effort. These SRM's are expected to

substantially improve accountability measurements in the nuclear industry.

21 . Neutron Depth Profiling and the Characterization of Dopant Distributions

(26109)

R. F. Fleming, R. G. Downing, J. T. Maki , D. H. Vincent

Increasingly, problems in science and industry require measurement of the

concentration distribution of constituents in the near-surface region of

materials. This is most significant in the semiconductor industry where non- destructive profiling reference measurements are needed to cross-cal ibrate

other methods as well as to perform simple analyses. In the case of boron,

its distribution after an implantation, its diffusion during material processing, and its homogeneity throughout glass overcoats must be known to design

state-of-the-art microcircuitry of reproducible integrity. In this first year

of operation, the synergism between neutron depth profiling (NDP) and other

techniques such as secondary ion mass spectroscopy (SIMS) [1], spreading

resistance probe (SRP), Fourier transform IR (FTIR) and prompt gamma-ray

emission (PGRE) has been demonstrated for the analysis of boron in semiconductor

materials.

The NDP facility utilizes a high quality, intense thermal neutron beam at

the NBS 10 MW reactor [2]. The depth profiling of boron or a number of other

elements (e.g.. He, Li, Na) depends on the fact that when the target isotope

absorbs a neutron, monoenergetic charged particles are isotropically emitted.

The amount of energy these particles lose before reaching a detector outside

the sample surface is directly related to the depth at which the reaction

takes place. Therefore, the energy spectrum of the charged particles can be

unfolded to give an absolute measurement of the depth distribution of the

reacting element. The particles stopping power in a particular matrix must

therefore be known.

Figure 14 is an overlay of two NDP measurements made on a borophosphosilicate glass (BPSG) film. One measurement was made after the sample was

74
Figure 14. Boron concentration profile of a borophosphosilicate glass

film on a silicon substrate. The comparison is between the

deposited glass (•) and the same film after annealing (x).

Data are not corrected for detector resolution.

deposited on a silicon wafer and the other measurement was made on the same wafer after physical processing of the sample. BPSG is used as an insulating

layer and for forming tapered contours over steep steps of oxide on silicon

for high density integrated circuits. NDP was able to determine the sample

thickness, the homogeneity of the boron distribution, and the absolute boron

concentration at discrete depths using a single non-destructive measurement.

Together the plots show the leveling of the boron distribution after processing.

The integrals of the two peaks are equivalent indicating that no boron loss

occured during processing. In addition, these measurements were used to

establish a calibration curve for FTIR, PGRE, and NDP in collaboration with

researchers from industry and university labs.

With respect to other elements of interest, perhaps the most significant

accomplishment this year has been the profiling of 22 Na for the first time.

In figure 15, the sodium profile of 22 Na is shown, diffused in a single layer

thick BPSG film on a silicon substrate. In addition, collaborative work with

other National labs is being carried out to study diffusion properties of 6 Li

in copper and lattice damage during implantation of 10 B in copper. In the

coming year NDP will continue to be applied to the profiling of He, Li, B, Na,

and Bi. The successful profiling of boron and 22 Na points toward the extension

of NDP to other elements such as beryllium profiling using 7 Be. Further improvements in resolution and accuracy should result as this unique facility continues

to develop.

75
20

u 15

x

CO

2:o

I—

cc

CCZ

8

10

0 J*1

0 12 3

DEPTH IN MICROMETERS

Figure 15.

References

Neutron depth profile of 22 Na in BPSG film, not

corrected for detector resolution.

[1] Downing, R. G. , Fleming, R. F. , Simons, D. S., and Newbury, D. E.,

Microbeam Analysis-1982, K. F. J. Heinrich, ed., (San Francisco

Press, 1982), pp. 219.

[2] Downing, R. G. , Fleming, R. F., Langland, J. K. , Vincent, D. H.,

Proceeding of the Sixth Intern. Conf. on Ion Beam Analysis,

1982, Nucl. Instr. Method, in press.

22. An Automated Mass Spectrometer--Inlet System for Gas Analyses (15601)

I. L. Barnes, W. A. Bowman, R. L. Shideler, P. Morales

Isotope dilution mass spectrometery is an analytical technique which is

widely applied to the determination of trace constituents in solid materials.

In many cases this method is highly precise and very accurate and has been

accepted as a definitive method.

IDMS has not yet been applied to the determination of the normally gaseous

light stable elements, i.e., carbon, hydrogen, oxygen, nitrogen and sulfur.

However, the same principles as for solid samples should apply, with the addec

advantage that gas phase measurements are more precise than those made with

thermal ionization since the measurements are usually compared to a reference

gas which is analyzed alternately with the sample.

76
A program was initiated to construct an instrument and develop the

methodology for the IDMS analyses of gases with the initial effort to be

concentrated on the analysis of carbon dioxide in nitrogen and air. To

accomplish this, a 30 cm radius, 90° deflection mass spectrometer has been

constructed. The instrument has an electron bombardment ion source and a specially designed (using the new ion optics programs) triple collector to

collect the three masses for C02 (44, 45, and 46), simultaneously (figure 16).

Figure 16. Triple filament collector assembly. Designed

specifically for carbon dioxide, each collector

contains an adjustable slit assembly, a deep

Faraday cup, and guard and repel ler plates.

The critical part of this instrument, however, is the specially designed

inlet system. Such a system must actually consist of two identical systems as closely matched as possible. A schematic diagram of the new inlet system is

shown in figure 17. The pressure in the sample and standard sides must be

matched as perfectly as the best technology permits. This is accomplished in

the new system by the use of a mechanism consisting of two matched stainless

steel bellows mounted on slide assemblies with precision lead screws driven by

computer controlled stepper motors. Each side of the system is connected to one side of a high precision capacitance manometer operated in the null mode.

A binary coded decimal (BCD) output from the manometer interfaced to a computer

is used to control the stepper motors to produce equal pressure. In addition,

the output signal from the mass 44 signal from the mass spectrometer is

monitored with a high precision digital voltmeter (DVM). A mismatched signal

indicates mismatched pressures and possibly an impure sample. Each of the air

operated valves indicated in Figure 17 is controlled by a small solenoid which

is controlled by a NBS designed IEEE-488 interface connected to the computer.

Any, or all, valves may be opened or closed independently or simultaneously.

An additional feature of the new instrument is the use of high precision ratio

DVM's so that the ratios 44/45 and 44/46 can be measured directly and at the

same time.

77
Figure 17. Schematic diagram of automated sample preparation,

storage, and inlet system for light stable elements.

The initial measurements of the isotopic ratios of several C02 reference

materials made with the instrument were an order of magnitude more precise

than the best reported to date and it is expected that this will be improved

further as the computer program is refined.

23. Potential Limitation in the Use of Thin Metal Films as Transmittance

Standards (15601

)

R. W. Burke, R. Mavrodineanu, M. V. Smith

A continuing research activity in high accuracy spectrophotometry is

focussed on the development of transmittance standards whose spectral properties

permit their use throughout the ultraviolet, visible, and near infrared regions

of the spectrum. Semi-transparent metal films have long been considered the

best of the extremely limited number of materials that can be used for this

purpose. Filters prepared by evaporating thin films of chromium, inconel, or nichrome onto quartz substrates exhibit excellent optical neutrality from

200 nm to 2.5 pm. Because of this neutrality, their transmittance is, except

for the most stringent applications, independent of wavelength, spectral

bandpass, and heterochromatic stray radiation.

During the production of SRM 2031 (chromium on quartz), there were, in

addition to long term stability, two other potential problems of major concern. The first dealt with finding a suitable means for protecting the chromium film

from environmental exposure and physical damage. This problem was solved when

it was found that the exposed metal layer could be adequately protected by

covering it with a second clear quartz plate. This second plate was ground

and polished in such a manner that a rigid assembly of the two plates could be

achieved by optical contact. The second problem dealt with the possible

consequences of the intrinsic property of semi-transparent metal films to

attenuate incident radiation not only by absorption but also by significant

reflection. It was our concern that, for instruments of less than optimal

design, this reflected radiation could produce erroneous indications of the

accuracy of the photometric scale because of the substantially larger

78
contribution to the measured transmittance of interreflections between the

film and the irradiating or detecting optics.

Although concern about the reflection problem still existed at the time,

SRM 2031 was issued in March 1980 on the basis of a lengthy in-house study and

collaborative measurements performed by the National Physical Laboratory in

Great Britain, the Michel son Laboratory in China Lake, CA, and nine other

laboratories in the United States, six of which were manufacturers of spectrophotometers. At the time, none of these laboratories encountered any

difficulties in using this type of filter and no problems were reported in the

subsequent use of SRM 2031 until April 1983. At that time, a representative

of a Swedish manufacturer of spectrophotometers informed NBS that a check of

the transmittance accuracy of one line of their instruments with NBS SRM 930d,

Glass Filters and SRM 2031, produced discrepant results. One of these instruments was tested by NBS and the discrepancies were confirmed. An examination

of this instrument indicated that reflections from the chromium-on-quartz

filters could be responsible for the observed differences. To confirm this

lypothesis, the chromium-on-quartz filters were placed in special holders in

i/hich they were tilted at an angle of 5 to 6 degrees to the incident beam.

Jnder these conditions the indicated accuracy of the instrument was comparable

:o that obtained with the glass filters (SRM 930d). These findings confirmed

an initial opinion that, for this particular instrument, isochromatic reflections generated by the chromium films are primarily responsible for degrading

the accuracy of the measured transmittance. Subsequent discussions with the

manufacturer have led to a change in optical design that substantially reduces

the instrument's interreflection error.

A modification of SRM 2031 is presently being evaluated that should prevent

reflective metal film transmittance standards from magnifying the interreflection effects in spectrophotometers whose optical design inherently produces

interreflection errors. This modification is illustrated in figure 18.

Cross-sectional views of the existing SRM 2031 and the proposed modification

are shown in 18 (A) and 18 (B) respectively. In the case of the modified

filter, the chromium layer is evaporated onto a quartz plate that has been

ground and polished at a 7° angle to the front face. The quartz cover plate

has an identical but opposite wedge. In this modification the chromium layer

receives the incident radiation at an angle and whatever portion is reflected

is eliminated from the optical path since it is absorbed by the blackened

walls of the sample compartment. A second important advantage of this particular design of tilted filter is that it does not shift the beam significantly.

Because the front and the rear surfaces of the assembly are perpendicular to

the incident radiation and only the film is tilted, the shift of the transmitted beam at the photocathode is kept at a minimum.

Six sets of these modified filters have been prepared and are presently

undergoing extensive in-house testing. Pending the results of these tests,

the filters will be tested further in the broadest range of commercial

spectrophotometers available to establish their general effectiveness for

calibrating instruments with inherent interreflection errors.

79
REFLECTED RADIATION INCIDENT AND REFLECTED

RADIATION (a) INCIDENT RADIATION (b)

QUARTZ

PLATES SEMI -TRANSPARENT

CHROMIUM METAL LAYER ^

QUARTZ

PLATES

SRM 2031 MODIFIED SRM 2031

Figure 18. Cross-sectional views of SRM 2031 (a) and its proposed

modification (b) for minimizing interreflection effects.

24. The Effect of Manganese on the Determination of Sulfur by Optical Emission

Spectrometry (15310)

J. A. Norris, D. E. Brown

An apparent bias in the emission spectrochemical determination of sulfur

in steels was reported previously [1], This discrepancy became apparent during

the redetermination of sulfur, in a number of SRM's, by isotope dilution mass spectrometry (ID/MS). At the time the report was written, there was not sufficient information available to determine a definite cause for the discrepancy.

A major cause of bias in emission spectroscopy is the presence of a spectral line of another element at or very near the analytical line of the

element being determined. Most SRM's are complex mixtures of many elements at

varying concentrations. Consequently, quantifying the interference due to a particular element is a difficult procedure. Sometimes these assignments can

be made successfully for wavelengths above 2000 A where abundant photographic

information is available. For the vacuum region, below 200 A, little information is available; thus determining interferences requires special materials.

A listing of glow discharge emission lines cites only Ca, 1807.74 A; Ti,

1806.98 A, and Ta, 1806.82 A as possible interferences with S 1807.31 A.

Another compendium of vacuum ultraviolet emission lines indicates that Ni,

1807.56 A and 1807.245 A; A1 , 1807.40 A; and Mo, 1807.63 A might interfere.

However, these data were obtained under excitation conditions considerably

different from those normally used for spectrochemical analysis.

Special ferrous base binary alloys, prepared by SKF STAL of Sweden, were

used to identify elements that interfere with the analysis of sulfur. These

alloys contained B, A1 , Si, P, V, Cr, Mn, Co, Ni, Cu, As, Nb, Mo, Sn, and W

in concentrations ranging from ppm levels for some elements to 24 percent for

Cr and 22 percent for Ni . All materials were analyzed on the vacuum spectrometer using calibration curves based on existing SRM's.

Of all the elements tested, only Mn and Ni had an appreciable influence

on the sulfur determination. The influence of Ni was an order of magnitude

less than that of manganese. The results obtained are shown in Table 12.

O

o

o

o o o

80
Table 12. Influence of Manganese on the Determination of Sulfur.

Assigned Values

Binary # % Mn % S

Determined Value

% S

% Sulfur Bias

Per % Mn

6012H

6013G

601 4G

0.553

1.08

2.04

0.0112

0.0120

0.0080

0.0123

0.0142

0.0113

0.00199

0.00203

0.00162

The only available information on a possible bias between the SKF sulfur

determination and our sulfur calibration comes from the values for sulfur in

two base steel materials that are a part of the binary series. The results

obtained for these samples are shown in Table 13.

Table 13. Sulfur Determined in SKF Base Steels.

Assigned Values Determined Values

% Mn % S % S

0.006 0.0101 0.0100, 0.0101

0.013 0.0115 0.0108, 0.0108

These data show that a correction of 0.002 percent S per percent Mn is the

present best estimate of the manganese influence on sulfur. Several recent

homogeneity studies have been reevaluated and the sulfur values have been

corrected to reflect the influence of manganese. This correction significantly

improves the accuracy for samples having a major amount of manganese. The

corrected values are shown in Table 14.

Table 14. Corrected Sulfur Values (%).

Uncorrected Corrected

SRM Certificate S Sulfur Sulfur

1222 0.022 + 0.002 0.022 0.0204 + 0.0011

1224 0.039 + 0.005 0.045 0.044 + 0.0024

1225 0.014 + 0.001 0.0161 0.0152 + 0.0008

1226 0.0044 + 0.0006 0.0051 0.0045 + 0.0003

1227 0.026 + 0.002 0.0305 0.0297 + 0.0024

1228 0.018 + 0.001 0.0194 0.0187 + 0.0008

1269 0.0061 + 0.0004 0.0085 0.0058 + 0.0004

1270 0.0065 + 0.0010 0.0064 0.0051 + 0.0004

Cl 285 0.020 + 0.001 0.0218 0.0211 + 0.0036

1286 0.017 + 0.001 0.0171 0.0168 + 0.000

Reference -

[1] 1981 Annual Report, iCenter for Analytical Chemistry,»

81
25. Certification of NBS Buffer Materials (15310)

Y. C. Wu, G. Marinenko

The pioneering work on the development of the National pH Scale was conducted at NBS under the leadership of S. F. Acree, W. J. Hamer, and

R. G. Bates. The National pH Scale, which evolved from their work, has gained

worldwide recognition and acceptance. The NBS pH scale is defined over a range of pH 3.5 to pH 10 in terms of seven pH ( S ) values assigned to seven primary reference standards. Traceability of this scale is maintained by

Standard Reference Materials (SRM's) of these seven buffers which are evaluated

at NBS and the measured pH ( S ) values certified. Depletion of the reserve quantities of these SRM buffers requires certification of the pH values for new lots of these materials.

For the purpose of primary certification (absolute measurement), accurate

emf measurements must be performed in a galvanic cell without a liquid junction.

Since the measured pH value is computed directly from E° and the measured emf

of the cell, accurate values for the potentials of the hydrogen and Ag/AgCl

electrodes must be assured. Performance of the hydrogen electrodes was checked

periodically by making emf measurements in 0.01 m HC1 against a common Ag/AgCl

reference electrode. The emf of all hydrogen electrodes was within 0.02 mV,

which contributes less than 0.001 pH uncertainty to the certified pH of the

standard buffers.

The Ag/AgCl electrodes used in this work are of somewhat different design

than those used previously. They are formed on high purity silver wire using

the thermal electrolytic method. Particular attention is given to the exclusion

of oxygen. Electrodes produced by this procedure are more stable and more

reproducible than those produced by the previous method. The lifespan of the

Ag/AgCl electrodes is also significantly extended, as indicated by the

reproducibility of E° of these electrodes measured periodically. Maintenance

of the instrumentation required for pH measurements is a continuous process,

involving periodic calibration of the digital barometer, quartz thermometer,

and digital voltmeter against the National standards.

Using the above approach and the improved facilities, three new buffer

materials were evaluated this year and their pH(S) values certified, at 5°

increments;, between 0 and 50 °C:

pH at 25 °C

(1) SRM 1 91 a/1 92a NaHC0

3/Na

2

C0

3

10.010

(2) SRM 187c Borax 9.180

(3) SRM 1 86 Id/1 86 I Id KH

2

P0

4

/Na

2

HP0

4

6.863

Further work is in progress on the development of reference solutions for

the calibration of glass electrodes for pH measurements of low ionic strength

solutions such as acid precipitation.
26. Standard Reference Materials (15310)

B. I. Diamondstone

The certification of Standard Reference Materials (SRM's) represents one of our major outputs and accounts for approximately one- third of the Division's

total staff effort. This work is diverse in nature, requires a high degree of

analytical skills and covers the full range of acceptance testing, homogeneity

evaluation, and accurate measurements leading to the certification of inorganic

constituents. As in the past, this support falls into two categories; STRS--

Scientific and Technical Research Services and WCF--Working Capital Funds.

Input in these areas is provided by the entire scientific staff with a considerable portion representing cooperative efforts between groups within the

Division.

During the past year, six different areas of rsearch were funded by the

Office of Standard Reference Materials under the STRS program (Table 15). The

STRS portion of the funding is intended for the preliminary research necessary

to develop the methodologies required for the actual production of SRM's. On

the other hand, the WCF projects result in the actual certification for

chemical composition of a marketable standard. Once again, analyses were

carried out on more than 75 different SRM's covering a variety of matrices

including metals, fossil fuels, body fluids, foods, nuclear materials, and

biological s (Table 16). In many cases, each certification involves several or

all of the groups in the Division and can require 20-30 individual analyses

on each SRM.

A major effort has been put forth to apply existing and newly acquired

methodologies to the determination of trace and ultratrace level elements in

urine, serum, and milk. Work is nearly complete on these materials and they

should be issued as SRM's in the near future. Nearly a dozen separate

techniques have been used to certify these three materials. In the area of

metals, work continues towards the certification of a number of new SRM's such

as inconel s, incoloys, and manganese ores. The process of updating existing

SRM's is carried out on a continual basis. For the first time in approximately

15 years, NBS has produced a certifiable value for hydrogen in a metal SRM.

This year the first set (Cd, Pb, Ag, Zn) of a new series of aqueous spectrometric standard solutions has been prepared. These standards are intended

for use with any of a number of spectrometric techniques including AAS, ICP,

DCP, and spectrophotometry.

During the coming year work will begin on several new materials leading

to the certification of a number of new SRM's. These materials include soil,

clay, tissues, ores, and metals. Additional sets of aqueous spectrometric

standards are also planned. Each year a significant amount of work goes into

updating existing SRM's, i.e., changing "information only" numbers to certified

values and performing analyses on previously undetermined elements.

83
Table 15. STRS Projects Supported by OSRM During FY 83.

Task Description Effort, SY

Gases in Metals

Measurement of pH

Analytical

Methodologies

Gas Isotope Dilution

Mass Spectrometry

High-Accuracy

Spectrophotometry

Neutron Depth

Profi 1 i ng

Research leading to the develop- 0.7

ment of an in-house capability

to certify oxygen, nitrogen, and

hydrogen in a broad range of metals.

Develop 14 MeV neutron technology

used in the measurement of oxygen

in steels.

Research to develop the capability 0.2

of making high-accuracy measurements

of pH suitable for certification

purposes.

Continued research to develop 1.1

analytical methodologies related

to the certification of Standard

Reference Materials.

Continued research leading to the 0.5

development of gas ID/MS methods for

determining elements such as sulfur,

oxygen, and nitrogen in many metals

and CO and C02 in nitrogen and air.

Research to extend the measurement 0.5

capabilities of the high-accuracy

spectrophotometer into the wavelength

region from 800 nm to 3.5 nm. Also,

investigate the wedge effect of

chromium coatings on optical filters.

Research to develop accurate thermal 0.2

neutron beam method for measuring

the compositional profile of boron-10

in silicon.

3.3

84
Table 16. WCF Work Carried Out on Standard Reference Materials During FY 83.

SRM Number Title 1Effort,

1233, 346a Valve Steels 0.1

1219, 11 51 -11 54a, 1155, 343a Stainless Steels 0.3

864-867, 1244-1247 Inconel s and Incoloys 0.5

2670 Trace Elements in Urine 0.5

2671 Fluorine in Urine 0.5

2672 Mercury in Urine 0.5

953 Neutron Density Monitor Wires 0.2

1633a Trace Elements in Fly Ash 0.3

191a, 192a pH Sodium Carbonate--Sodium

Bicarbonate

0.6

2031 Metal on Quartz Filters 0.6

930d Glass Filters for Spectrometry 0.2

1084, 1085 Wear Metals in Oil 0.3

1083 Base Stock Oil 0.3

1573, 1575 Tomato Leaves, Pine Needles 0.2

1549 Powdered Milk 1.2

1643b Trace Elements in H2O 0.8

1577a, b Trace Elements in Bovine Liver 0.1

Cl 252, 400, 399, 398,

457, 496, 395, 394

Copper Benchmarks 0.1

C2403-C2410 Brasses 0.4

Cl 290-C1 292 , C2400-C2402 White Irons 0.4

2423-2427 Ductile Iron 0.4

25d Ruti 1

0.2

670 Manganese Ore 0.2

909 Trace Elements in Serum 0.6

1618 Fuel Oil 0.2

2121 Atomic Absorption Standard

Solutions

0.3

120c, 694 Phosphate Rocks 0.2

1832 XRF Films 0.4

33e, 1761-1767 Low Alloy Steels 0.3

1264a High Carbon Steel 0.3

1227 Plain Steel 0.3

9.4

85
C. Outputs and Interactions

(Inorganic Analytical Research Division)

1 . Pub! i cations

Barnes, I. L., Murphy, T. J., and Michiels, E. A. I., "Certification of Lead

Concentration in Standard Reference Materials by Isotope Dilution Mass

Spectrometry," J. Assoc. Off. Anal. Chem. , 65, 953 (1982).

Bechtler, G. , Epstein, M. S., Geary, T. D. , Havemann, W. , and Attoe, P.,

"Provisional Guidelines for Listing Specifications of Flame Emission

Spectrometers," Clin. Chim. Acta, 122 , 1 1 1 F (1982).

Burke, R. W. , Paulsen, P. J., Maienthal, E. J., and Lambert, G. M. , "Validation

of the Sulfur Concentration of Selected Iron-Base NBS Standard Reference

Materials by Isotope Dilution Spark Source Mass Spectrometry," Talanta,

29^, 809 (1982).

Coplen, T. , Kendall, C., and Barnes, I. L., "Two New Carbonate Stable Isotope

Standards," Geostandards Newsletter, VI_, 257 (1982).

Cronin, D. J. and Kingston, H. M. , "An Examination of the MCC-1 Leach Test

Method: Comparison of Glass Compositions," Materials Characterization

Center DOE, Summary Report PNL-4382, Battel le. Workshop on the Leaching

Mechanisms of Nuclear Waste Forms, 144 (1982).

Downing, R. G. , Fleming, R. F., Simons, D. S., and Newbury, D. E., "NeutronInduced Reactions and Secondary Ion Mass Spectrometry: Complementary

Tools for Depth Profiling," Microbeam Analysis-1982, K. F. J. Heinrich,

ed., San Francisco, pp. 219 (1982).

Epstein, M. S. , Geary, T. D., Gower, G., Tavsch, W., Mills, K. J., and

Polt, D. , "Provisional Guidelines for Listing Specifications of Atomic

Absorption Spectrometers," Clin. Chim. Acta, 122 , 117F (1982).

Fleming, R. F. , "Neutron Self-Shielding Factors for Simple Geometries,"

Int. J. of Applied Radiation and Isotopes, 83, 1263 (1982).

Greenberg, R. R. , "Radiochemical Procedures Used at NBS for High-Sensitivity

Certification Analysis of Standard Reference Materials," Trans. Am. Nucl

Soc., 43, 269 (1982).

Kingston, H. M. , Cronin, D. J., and Epstein, M. S., "An Examination of the

MCC-1 Leach Test Methods: Experimental Technique," Materials Characterization Center DOE, Summary Report PNL-4382, Battelle, Workshop on the

Leaching Mechanisms of Nuclear Waste Forms, 133 (1982).

Kingston, H. M. , Greenberg, R. R. , Beary, E. S., Hardas, B. R. , Moody, J. R.

,

Rains, T. C. , and Liggett, W. S., "The Characterization of the Chesapeake

Bay: A Systematic Analysis of Toxic Trace Elements," National Technical

Information Service, Order No. PB82-265-265, (1982).

86
Kingston, H. M. and Lutz, G. J., "Adsorption and Stability Prior to Analysis

of Simulated Nuclear Waste Leachate," Nuclear and Chemical Waste

Management, 3^, 245 (1982).

Koch, W. F. , Marinenko, G. , and Stolz, J. W., "Simulated Precipitation Reference

Materials, IV," National Bureau of Standards (U.S.), NBSIR 82-2581, (1982).

Mielenz, K. D. , Weidner, V. R. , and Burke, R. W. , "Heterochromatic Stray Light

in UV Absorption Spectrometry: A New Test Method," Applied Optics, 2^,

3354 (1982).

Moody, J. R. , "NBS Clean Laboratories for Trace Element Analysis," Anal.

Chem., 54, 1358A (1982).

Moody, J. R. and Beary, E. S., "Purified Reagents for Trace Metal Analysis,"

Talanta, 29, 1003 (1982).

Burke, R. W. and Mavrodineanu, R. , "Accuracy in Analytical Spectrophotometry,"

NBS Special Publication 260-81, (1983).

Burke, R. W. and Velapoldi, R. W., "Recommended Reference Materials for

Realization of Physicochemical Properties: Transmittance and Wavelength,"

Draft Documents for IUPAC Commission 1.4, (1983).

Epstein, M. S. , "Determination of Ultratrace Levels of Lead in Reference Fuels

by Graphite Furnace Atomic Absorption," Atomic Spectrosc., ^4, 62 (1983).

Fassett, J. D. , Moore, L. J., Travis, J. C., and Lytle, F. E., "Atomic Ion

Formation and Measurement with Resonance Ionization Mass Spectrometry,"

Anal . Chem. , 55_, 765 (1983).

Greenberg, R. R. , "Neutron Activation Analysis Techniques Used For Ultra-trace

Level Elemental Characterization of New NBS Milk Powder Standard

Reference Material," Trans. Am. Nucl. Soc., 44, 28 (1983).

Greenberg, R. R. and Kingston, H. M., "Trace Element Analysis of Natural

Water Samples by Neutron Activation Analysis with Chelating Resin,"

Anal. Chem., 55, 1160 (1983).

Kelly, W. R. and Fassett, J. D. , "Determination of Picogram Quantities of

Uranium in Biological Tissues by Isotope Dilution Thermal Ionization Mass

Spectrometry with Ion Counting Detection," Anal. Chem., 55, 1040 (1983).

Koch, W. F. , "The Determination of Trace Levels of Cyanide by Ion Chromatography

with Electrochemical Detection," J. Res. Nat. Bur. Stand. (U.S.), 88,

157 (1983).

Koch, W. F. , Stolz, J. W., Kelly, W. R. , Paulsen, P. J., Lindstrom, R. M.

,

Fleming, R. F. , and Greenberg, R. R. , "Methods and Procedures Used at the

National Bureau of Standards to Certify NBS Sulfur in Coal SRM's for

Sulfur Content, Calorific Value, Ash Content," T. E. Gills, ed., Nat.

Bur. Standard. (U.S.) Spec. Publ. 260 (1983).

87
Marinenko, G. , Koch, W. F., and Etz, E. S., "High-Precision Coulometric

Titration of Uranium," J. Res. Nat. Bur. Stand. (U.S.), 88, 117 (1983).

Messman, J. D., Epstein, M. S., Rains, T. C., and O'Haver, T. C. , "Performance

Characteristics of a Continuum-Source Wavelength-Modulated Atomic

Absorption Spectrometer," Anal. Chem. , 5J5, 1055 (1983).

Moody, J. R. , "Sampling and Storage of Materials for Trace Elemental

Analysis," Trends in Anal. Chem., 2 , 116 (1983).

Pella, P. A., Kingston, H. M. , Sieber, J. R., and Feng, L. Y., "Effect of

Sample Dissolution Procedures on X-ray Spectrometric Analysis of Biological

Materials," Anal. Chem., 5>5, 1193 (1983).

Pratt, K. W. and Johnson, D. C., "The Vibrating Wire Electrode as an Amperometric Detector for Flow-Injection Systems," Anal. Chim. Acta, 148, 87

(1983).

Watters, R. L. , Jr., "Practical Limits of Precision in Inductively Coupled

Plasma Spectrometry," American Laboratory, p. 16 (1983).

Wise, S. A., Fitzpatrick, K. A., Harrison, S. H., Zeisler, R., Langland, J. K.,

Kratochvil, B., Rains, T. C., Rush, T. A., Butler, T. A., Gramlich, J. W.,

Powell, L. J., Brletic, K. A., Murphy, T. J., Bailey, J., Maienthal, E. J.,

Koch, W. F. , Kline, W. F. , Allen, C. F., Chesler, S. N., Hilpert, L. R.

,

Greenberg, R. R. , MacCrehan, W. A., and Anderson, D. F. , "The Pilot

National Environmental Specimen Bank--Analysis of Human Liver Specimens,"

Zeisler, R. , Harrison, S. H., and Wise, S. A., eds., Nat. Bur. Stand.

(U.S.) Spec. Publ . 656, p. 127 (1983).

Barnes, I. L., Gills, T. E., and Reed, W. P., "Copper Standard Reference

Materials," ASTM Special Publication, "Copper Cathodes," in press.

Beary, E. S., Paulsen, P. J., and Lambert, G. M. , "The Determination of

Selenium and Tellurium in Copper Reference Materials Using Isotope

Dilution Spark Source Mass Spectrometry," in press.

DeBievre, P. , Gallet, M. , Holden, N., and Barnes, I. L., "Isotope Abundances

and Atomic Weights of the Elements," J. of Phys. and Chem. Ref. Data,

in press.

Domalski, E. S., MacCrehan, W. A. Moody, J. R. , Tewari, Y. B., and

Walker, J. A., "Characterization of Mill Scale Wastes," Annual Report of

Office of Recycled Materials, National Bureau of Standards, in press.

Downing, R. G. , Fleming, R. F., Langland, J. K. , and Vincent, D. H., "Neutron

Depth Profiling at the National Bureau of Standards," Proceedings of the

Sixth International Conference on Ion Beam Analysis, Tempe, AZ, May

23-27, 1983, Nucl. Instr. and Method., in press.

Epstein, M. S. and Blundell, C. G., "Temperature Regulation System for

a D.C. Plasma/Echelle Spectrometer," Anal. Chem., in press.

88
Epstein, M. S. and Winefordner, J. D., "Summary of the Usefulness of Signalto-Noise Treatment in Analytical Spectrometry," Prog. Anal. Atom.

Spectrosc., in press.

Fassett, J. D. and Kelly, W. R. , "Interlaboratory Analysis Program of Anion

Exchange Resin Beams Loaded with Nanogram Amounts of Uranium and Plutonium

Using Thermal Ionization Mass Spectrometry," in press.

Fassett, J. D. , Moore, L. J., Shideler, R. W., and Travis, J. C., "Pulsed

Thermal Ion Source for Use in Resonance Ionization Mass Spectrometry,"

in press.

Fassett, J. D. , Moore, L. J., and Travis, J. C., "The Characterization of

Thermally Produced Metastable Excited State Atomic Species Using Resonance

Ionization Mass Spectrometry," Int. J. Mass Spectrom. Ion Phys., in press.

Fleming, R. F. , Pei, P. and Hsu, S. M. , "Test Methods for Total Chlorine

in Lubricating Base Oils," in press.

Gramlich, J. W. and Machlan, L. A., "Isotopic Variations in Commercial

High Purity Gallium," in press.

Kelly, W. R. and Paulsen, P. J., "Precise Determination of Sulfur at High

Concentrations by Isotope Dilution Thermal Ionization Mass Spectrometry,"

in press.

Kingston, H. M. , Cronin, D. J., and Epstein, M. S., "Investigation of a Precise

Static Leach Test for the Testing of Simulated Nuclear Waste Materials,"

in press.

Kingston, H. M. , Paulsen, P. J., and Lambert, G. M. , "The Determination of

Selenium and Tellurium in Stainless Steel, White Cast Iron, and Nickel

Base Alloy Standard Reference Materials by Isotope Dilution Spark Source

Mass Spectrometry," in press.

Ku, C. S., Wu, Y. C. , and Hsu, S. M. , "Oxidative Degradation Mechanism

of Lubricants," in press.

Lucatorto, T. B., Clark, C. W., and Moore, L. J., "Ultrasensitive Mass

Spectrometry Based on Two-Photon, Sub-Doppler Resonance Ionization,"

in press.

Moody, J. R., "Recent Trends in Laboratory Design in the USA," Proceedings

of Lab Expo 82 (London), in press.

Moore, L. J., Kingston, H. M., Murphy, T. J., "The Use of Isotope Dilution

Mass Spectrometry for the Certification of Standard Reference Materials,"

in press.

Paulsen, P. J. and Kelly, W. R. , "Determination of Sulfur by Isotope Dilution

Thermal Ionization Mass Spectrometry as AsS

+ Ions," in press.

89
Powell, L. J. and Murphy, T. J., "The Determination of Atomic Weights at

NBS--The Case of Silver and Its Impact on the Faraday," in press.

Powell, L. J. and Paulsen, P. J., "The Determination of Microgram Per Gram

Concentrations of Hafnium in Zirconium Metal and Zircaloy 4 Metal Standard

Reference Materials by Isotope Dilution Spark Source Mass Spectrometry,"

in press.

Winefordner, J. D. and Epstein, M. S., "Atomic Spectrometric Methods," Chapter

in physical methods of Chemistry, B. W. Rossiter and J. F. Hamilton,

eds., John Wiley & Sons, New York, in press.

Wu, Y. C. and Hsu, S. M. "Lubricant Degradation Mechanism for Engine Oil," NBS

Special Publication for the Conference on Measurements and Standards for

Recycle Oil-IV, in press.

Yaffe, Y., Flessel, C. P. , Wesolowski, J. J., del Rosario, A., Guirguis, G. N.,

Martias, V., Gramlich, J. W. , Kelly, W. R. , DeGarmo, T. E., and

Coleman, G. C. , "Identification of Lead Sources in California Children

Using the Stable Isotope Ratio Techniques," in press.

Zeisler, R. , Harrison, S. H., and Wise, S. A., "Trace Elements in Human Livers

Using Quality Control in the Complete Analytical Process," Biol. Trace

Element Res., in press.

Zeisler, R. , Langland, J. K. , and Harrison, S. H., "Cryogenic Homogenization

Procedure for Biological Tissues," Anal. Chem., in press.

Greenberg, R. R. , Fleming, R. F. , and Zeisler, R. , "High Sensitivity Neutron . Activation Analysis of Environmental and Biological Standard Reference

Materials," submitted for publication.

Kingston, H. M. and Greenberg, R. R. , "An Elemental Ratioing Technique for

Assessing Concentration Data From a Complex Water System," submitted for

publication.

Lutz, G. J., Rook, H. L. , and Lindstrom, R. M. , "Determination of 1-129 at

Natural Levels by Thermal Neutron Activation Analysis," submitted for

publication.

Rains, T. C. , "Atomic Absorption Spectrometry," Chapter in Treatise on Water

Analysis , R. A. Mi near, ed.. Academic Press, submitted for publication.

Rains, T. C., Watters, R. L., Jr., and Epstein, M. S., "Application of Atomic

Absorption and Plasma Emission Spectrometry for Environmental Analysis,"

submitted for publication.

Zhang, Y. K. , "Determination of Germanium in Biological Fluids by Electrothermal Atomization Atomic Absorption Spectrometry," submitted for

publication.

90
2. Talks

Moody, J. R. , "Sampling for Trace Analysis," Society for Applied Spectroscopy

Continuing Education Course, Beltsville, MD, October 4, 1982. Invited

Epstein, M. S., "Atomic Absorption Spectrometry," 2nd NBS-ADABSE Analytical

Chemistry Workshop, National Bureau of Standards, Gaithersburg, MD,

October 24, 1982. Invited

Watters, R. L. , Jr., "Atomic Emission Spectrometry Using the Inductively

Coupled Plasma (ICP) Technique," NBS-ADABSE Analytical Chemistry Workshop,

National Bureau of Standards, Gaithersburg, MD, October 24, 1982. Invited

Rains, T. C. , "State of the Art of Atomic Absorption Spectrometry," NBS-ADABSE

Analytical Chemistry Workshop, National Bureau of Standards, Gaithersburg,

MD, October 26, 1982. Invited

Zeisler, R., "Trace Elements in Human Livers Using Quality Control in the

Complete Analytical Process," 1st Annual Scientific Meeting of the Society

for Environmental Geochemistry and Health, Greenville, NC, November 2,

1982.

Dowing, R. G. , "Thermal Neutron Depth Profiling in Boron and Silicon,"

7th International Conference on the Application of Accelerators in

Research and Industry, Denton, TX, November 8, 1982.

Greenberg, R. R. , "Radiochemical Procedures Used at NBS for High-Sensitivity

Certification Analysis of Standard Reference Materials," American Nuclear

Society Meeting, Washington, DC, November 16, 1982. Invited

Moody, J. R., "Special Facilities for Trace Metal Analysis at NBS," University

of Illinois (Champaign), Chemistry Colloquium, November 16, 1982. Invited

Rains, T. C. , "State of the Art of Sample Preparation for Inductively

Coupled Plasma," 21st Eastern Analytical Symposium, New York, NY,

November 18, 1982. Invited

Watters, R. L., Jr., "Random and Non-Random Variability in ICP Calibration

Functions," 21st Eastern Analytical Symposium, New York, NY,

November 18, 1982. Invited

Moody, J. R. , "Techniques for Trace Metal Analysis at NBS," U.S.G.S. National

Water Quality Control Laboratory Colloquium, Arvada, CO, November 19,

1982. Invited

Rains, T. C., "Using Matrix Modification to Alleviate Interferences in Graphite

Furnace Atomic Absorption Spectroscopy," 21st Eastern Analytical

Symposium, New York, NY, November 19, 1982.

Fleming, R. F. , "Neutron Depth Profiling of Elemental Concentrations,"

Bell Laboratories, Murray Hill, NJ, December 1, 1982.

91
Fassett, J. D., "Resonance Ionization Mass Spectrometry," Division Seminar,

National Bureau of Standards, Gaithersburg, MD, December 1, 1982.

Rains, T. C., "New Innovations in Electrothermal Atomization/Atomic Absorption

Spectrometry," Milwaukee Section of Society for Applied Spectroscopy,

Milwaukee, WI, February 15, 1983. Invited

Barnes, I. L., "Focussing Properties of Stray Magnetic Fields," Institute of

Physics, University of Mexico, March 2, 1983. Invited

Rains, T. C. , "Atomic Absorption and Emission Spectrometry," ACS Short

Course, Pittsburgh Conference, Atlantic City, NJ, March 5, 1983.

Barnes, I. L., "Isotope Dilution Mass Spectrometry and Its Use in Chemical

Analysis," Graduate School of Chemistry, University of Mexico,

March 9, 1983. Invited

Rains, T. C. , "The Art of Sample Preparation for Atomic Absorption

Spectrometry," Assay and Weights Administration, Gamalia, Cairo,

March 20, 1983. Invited

Rains, T. C., "Instrumental Method of Analysis," Assay and Weights

Administration, Gamalia, Cairo, March 21, 1983. Invited

Rains, T. C. , "Determination of Trace Elements in Water and Air Particulate

by AAS," Assay and Weights Administration, Gamalia, Cairo, March 23,

1983. Invited

Rains, T. C., "Interferences in Atomic Absorption Spectrometry," Assay

and Weights Administration, Gamalia, Cairo, March 27, 1983. Invited

Gramlich, J. W. , "The Application of Thermal Ionization Isotope Dilution Mass

Spectrometry to the Certification of NBS Standard Reference Materials,"

Department of Chemistry, Arizona State University, Tempe, AZ, March 29,

1983. Invited

Rains, T. C., "State of the Art of AAS," Egyptian Organization for

Standardization," Gamalia, Cairo, March 29, 1983. Invited

Rains, T. C., "Characterization of Standard Reference Materials by AAS,"

National Research Center, Dokki , Cairo, March 30, 1983. Invited

Rains, T. C., "Determination of Major, Minor, and Trace Elements in Ferrous

and Non-ferrous Metals, Ores, and Ceramics by AAS," Assay and Weights

Administration, Gamalia, Cairo, March 31, 1983. Invited

Vincent, D. H., "Neutron Depth Profiling at the National Bureau of Standards,"

New York Area Regional Meeting on Ion Beam Analysis, Brooklyn, NY,

April 6, 1983.

Ku, C. S., Wu, Y. C., and Hsu, S. M. , "Oxidative Degradation Mechanism of

Lubricants," Am. Soc. Lubricant Engineers Annual Meeting, Houston, TX,

April 25, 1983.

92
Fleming, R. F. , "Advantages of Neutron Activation Analysis with Special Emphasis

on Semiconductor Technology," Ford Motor Company, Dearborn, MI, April 27,

1983.

Fleming, R. F. , "Analytical Chemistry Applications of Neutrons," Great Lakes

Chapter of the Health Physics Society, Dearborn, MI, April 28, 1983.

Invited

Rains, T. C., "Trace Elemental Analysis of Environmental Materials," Florida

Society of Environmental Analysis, Tampa, FL, April 29, 1983. Invited

Kelly, W. R. , "The Use of Stable Traces in Source Apportionment. Discussions

on the Deep Creek Lake Source— Receptor Study," National Bureau of

Standards, Gaithersburg, MD, May 3, 1983. Invited

Fleming, R. F. , "Elemental Depth Profiling Using Thermal Neutrons,"

Eastman Kodak Company, Rochester, NY, May 9, 1983.

Brletic, K. A., Powell, L. J., and Garner, E. L., "A High Sensitivity Procedure

for Chromium Using Silica-Gel Boric Acid Ionization Enhancement," 31st

Annual Conference on Mass Spectrometry and Allied Topics, Boston, MA,

May 12, 1983.

Paulsen, P. J., Beary, E. S., and Lambert, G. M., "The Determination of

Selenium and Tellurium in NBS Copper Base SRM's by SSMS Isotope Dilution,"

31st Annual Conference of Mass Spectrometry and Allied Topics, Boston,

MA, May 12, 1983.

Fassett, J. D. , Moore, L. J., and Travis, J. C. , "RIMS—Resonance Ionization

Mass Spectrometry of 18 Elements From Thermal Vapor Atom Reservoirs,"

31st Annual Conference of Mass Spectrometry and Allied Topics, Boston,

MA, May 13, 1983.

Fassett, J. D. , Moore, L. J., and Travis, J. C., "A Laser Mass Spectrometry

Laboratory for Stable Isotope Measurements and Vaporization Diagnostics,"

31st Annual Conference of Mass Spectrometry and Allied Topics,

Boston, MA, May 13, 1983.

Downing, R. G. , "Neutron Depth Profiling and Semiconductor Analysis," Motorola

Surface Research and Development Laboratory, Pheonix, AZ, May 20, 1983.

Kelly, W. R. , "The Measurement of Sulfur Isotopic Ratios by Thermal Ionization

Mass Spectrometry," Carnegie Institution of Washington, Washington, DC,

May 25, 1983. Invited

Barnes, I. L., "Ultimate Mass Dispersion and Resolution in Magnetic Sector

Machines," Symposium on New Techniques and Potential Applications of

Ultrasensitive Mass Spectrometry, National Bureau of Standards,

Gaithersburg, MD, May 31, 1983. Invited

93
Fassett, J. D., "Recent Developments in RIMS," Symposium on New Techniques

and Potential Applications of Ultrasensitive Mass Spectrometry,

National Bureau of Standards, Gaithersburg, MD, May 31, 1983.

Kelly, W. R., "Cosmogenic and Geophysical Measurements," Symposium on New

Techniques and Potential Applications of Ultrasensitive Mass Spectrometry,

National Bureau of Standards, Gaithersburg, MD, May 31, 1983. Invited

Moore, L. J., "Resonance Ionization Mass Spectrometry--Potential Applications,"

Symposium on New Techniques and Potential Applications of Ultrasensitive

Mass Spectrometry, National Bureau of Standards, Gaithersburg, MD, May

31, 1983. Invited

Zeisler, R., "The Table Top Accelerator as an Analytical Tool," Symposium on New Techniques and Potential Applications of Ultrasensitive Mass

Spectrometry, National Bureau of Standards, Gaithersburg, MD, May 31,

1983.

Fleming, R. F., Vincent, D. H., and Downing, R. G., "Neutron Depth Profiling

for Materials Characterization," 5th Symposium on Applied Surface Analysis,

Dayton, OH, June 10, 1983.

Greenberg, R. R., "Neutron Activation Analysis Techniques Used for Ultra-trace

Level Elemental Characterization of New NBS Milk Powder Standard Reference

Material," American Nuclear Society Meeting, Detroit, MI, June 15, 1983.

Invited

Lutz, G. J., "The Determination of Iodine in Biological Standard Reference

Materials by Instrumental Photon and Epithermal Neutron Activation

Analysis," American Nuclear Society Meeting, Detroit, MI, June 15, 1983.

Invited

Fleming, R. F. , "Applications of Neutron Depth Profiling," National Bureau

of Standards, Gaithersburg, MD, June 15, 1983.

Koch, W. F. and Marinenko, G., "Atmospheric Deposition Reference Materials:

Measurement of pH and Acidity," 76th Annual Meeting of the Air Pollution

Control Association, Atlanta, GA, June 22, 1983.

Rains, T. C., Rush, T. A., and Butler, T. A., "Trace Element Characterization

of Urine for a Standard Reference Material by Atomic Absorption and

Emission Spectrometry," 23rd Colloquium Spectroscopicum International

Amsterdam, The Netherlands, June 27, 1983.

Rains, T. C. , "Trace Elemental Analysis of Water by AAS," EPA, Annapolis,

MD, July 21, 1983. Invited

Moody, J. R. , Machlan, L. A., and Gramlich, J. W., "Characterization of

Uranium Absolute Isotopic Standard Reference Materials," 53rd Society of

Analytical Chemistry Meeting, Edinburgh, Scotland, July 22, 1983.

94
Norris, J. A., "Qualitative and Semi -quantitative Analysis, Data Handling, and

Statistics, Direct Reading Spectrochemical Analysis and Laboratory

Instruction in Photographic Emission Spectroscopy," 28th Annual Course on Modern Industrial Spectroscopy, Arizona State University, Tempe, AZ,

August 1, 1983.

Moore, L. J., Fassett, J. D. , Travis, J. C., Lucatorto, T. B. , and Clark, C. W.

,

"Isotopic Selectivity in Ultrasensitive RIMS," Symposium on Laser-Based

Ultrasensitive Spectroscopy, SPIE Conference, San Diego, CA, August 22,

1983. Invited

Moore, L. J., Fassett, J. D. , Travis, J. C., and Lucatorto, T. B., "Resonance

Ionization Mass Spectrometry," Lawrence Livermore National Laboratory,

Nuclear Chemistry Division, Livermore, CA, August 25, 1983. Invited

Rains, T. C., "Atomic Absorption and Plasma Emission Spectrometry," American

Chemical Society National Meeting, Washington, DC, August 27-28, 1983.

Beary, E. S. and Moody, J. R. , "Laboratory Design for the Safe Distillation

of Acids," American Chemical Society, National Meeting, Washington, DC,

August 29, 1983. Invited

Koch, W. F., "Acid Precipitation Standards: Measurement of pH," American

Chemical Society National Meeting, Washington, DC, August 29, 1983.

Moore, L. J., "Stable Isotope Measurements with Thermal and Resonance

Ionization Mass Spectrometry," Symposium on Stable Isotopes in Nutrition,

American Chemical Society National Meeting, Washington, DC, August 29,

1983. Invited

Moody, J. R., "Installation and Proper Use of Fume Hoods for Perchloric

Acid in Analytical Laboratories," American Chemical Society National

Meeting, Washington, DC, August 29, 1983. Invited

Stone, S. F., "A Protocol for the Multielement Analysis of Banked Marine

Bi values," American Chemical Society National Meeting, Washington, DC,

August 30, 1983.

Fleming, R. F., Downing, R. G., Lindstrom, R. M. , Riley, J. E., Jr., and

Vincent, D. H., "Materials Analysis Using Thermal Neutron Reactions:

Methods," American Chemical Society National Meeting, Washington, DC,

August 31, 1983. Invited

Riley, J. E. , Jr., Downing, R. G., Fleming, R. F., Lindstrom, R. M. , and

Vincent, D. H. , "Materials Analysis Using Neutron Reactions: Applications,"

American Chemical Society National Meeting, Washington, DC, September 1,

1983. Invited

Zeisler, R. , "Quality Assurance and Standardization in Sampling and Sample

Preparation of Biological Materials," 10th Annual Meeting of the Federation for Analytical Chemistry and Spectroscopy Societies, Philadelphia, PA,

September 26, 1983. Invited

95
Epstein, M. S., "Laser-excited Atomic Fluorescence Spectroscopy In Florida,"

10th Annual Meeting of the Federation for Analytical Chemistry and

Spectroscopy Societies, Philadelphia, PA, September 27, 1983. Invited

Rains, T. C., "Sample Preparation Workshop," 10th Annual Meeting of the

Federation for Analytical Chemistry and Spectroscopy Societies,

Philadelphia, PA, September 27, 1983.

3. Committee Assignments

I. Lynus Barnes

Member, Department of Health, Education, and Welfare, The Chemistry

Task Force of the National Shellfish Sanitation Program

Washington Editorial Review Board

International Union of Pure and Applied Chemistry, Commission

of Atomic Weights and Isotopic Abundances

Secretary, IUPAC, Commission on Atomic Weights and Isotopic Abundances,

Subcommittee for Assessment of Isotopic Abundances

Robert W. Burke

Member, ASTM D-34, Waste Disposal

ASTM E-03, Chemical Analysis of Metals

Collator, Transmittance and Wavelength Section, IUPAC Commission

1.4, Physicochemical Measurements and Standards

Barry I. Diamondstone

Member, ASTM D-34, Waste Disposal

ASTM D-34. 02. 01, Section on Batch Extractions

ASTM E-03, Chemical Analysis of Metals

ASTM E-03. 01, Gases in Metals

ASTM E-03. 93, Long Range Planning

Michael S. Epstein

Member, ASTM D-19, Water

Editorial Advisory Board, Progress in Analytical Atomic Spectroscopy

Chairman, Baltimore-Washington Section of the Society for Applied

Spectroscopy

Conference Committee, Society for Applied Spectroscopy

Delegate, FACSS Governing Board for the Division of Analytical

Chemistry of the American Chemical Society

Ronald F. Fleming

Member, Committee on Accelerator-Based Neutron Research at NBS

ASTM E-10.05, Nuclear Radiation Metrology

John W. Gramlich

Member, Institute of Nuclear Materials Management Committee N15.9.3,

Non-Destructive Assay (Physical Methods)

96
Robert R. Greenberg

Member, NBS Chemistry Storeroom Committee

Trace Analysis Committee, Biomedical Division, American Nuclear

Society

Howard M. Kingston

Member, ASTM C-26.05, Methods of Test

ASTM C-26.07, Waste Materials

Task Group Leader, C-26.05, Leachate Analysis Methods

William F. Koch

Member, ASTM D-19, Water

ASTM D-19, 02, General Specifications and Technical Resources

ASTM D-19. 05, Inorganic Constituents in Water

ASTM D-22, Air

Chairman, Teller's Committee, Chemical Society of Washington

John K. Langland

Member, NBS Electronics Storeroom Committee

Richard M. Lindstrom

Alternate Member, NBSR Hazard Evaluation Committee

Lawrence A. Machlan

Member, ASTM C-26, Nuclear Fuel Cycles

ASTMC-26.05, Test Methods

Secretary, ASTM C-26. 01, Editorial and Terminology

George Marinenko

Member, ASTM D-19, Water

ASTM D-19. 09, Saline and Brackish Waters

ASTM D-19. 05, Inorganic Constituents in Water

ASTM D-19. 05. 03. 06, Ozone

Registration Committee of National Meeting of the Electrochemical

Society

Chairman, ASTM D-19. 05. 04. 03, Voltammetry

ASTM D-19. 09. 01 .14, Chlorine in Saline Water

ASTM D-19. 09. 06, Redox Potentials

ASTM D-19. 09. 07, pH in Saline Water

National Capital Section of the Electrochemical Society

Blum Award Arrangements, Committee of the Electrochemical

Society

Councilor, National Capital Section of the Electrochemical Society

John R. Moody

Member, ASTM D-19, Water

ASTM D-19. 05, Inorganic Constituents in Water

Audit Committee, Chemical Society of Washington

Contamination Control Standards and Practices for Federal

State 209c Institute for Environmental Sciences

97
Thomas J. Murphy

Member, American Chemical Society Committee on Analytical Reagents

American Chemical Society Committee on Membership Affairs

International Union of Pure and Applied Chemistry (IUPAC),

Commission on Atomic Weights and Isotopic Abundances

International Union of Pure and Applied Chemistry (IUPAC),

Subcommittee for the Assessment of Isotopic Abundances,

Commission on Atomic Weights and Isotopic Abundances

Chairman, American Chemical Society Admissions Committee

Audit Committee, Chemical Society of Washington

Councilor, Chemical Society of Washington

John A. Norris

Member, ASTM E-02.01, Fundamental Practices

ASTM E-02.02, Statistics

ASTM E-02.04, Samping and Standards

ASTM E-02.06, Lead, Tin, Zinc

ASTM E-02.07, Aluminum

ASTM E-02.08, Refractory Metals

ASTM E-02.09, Ferrous

ASTM E-02.10, Miscellaneous Non-Metallic Materials

Representative, SAS to Joint Committee on Atomic and Molecular

Physical Data

Secretary, ASTM E-02, Emission Spectroscopy

Lecturer, Annual Short Course, "Modern Industrial Spectroscopy,"

Arizona State University, Tempe, AZ

Lura J. Powell

Member, Audit Committee, Chemical Society of Washington

Board of Directors, NBS Child Care Association

Chairman, Committee on Isotope Ratio Measurements, American Society

for Mass Spectrometry

Treasurer, Chemical Society of Washington

President, Standards Committee for Women

Theodore C. Rains

Member, Proposal Evaluation Committee for National Science Foundation

AOAC Committee on Automated Methods

Editorial Board of Annual Reports on Analytical Atomic Spectroscopy (The Chemical Society of London) and the Canadian Journal

of Spectroscopy

Subcommittee No. 6 on Methods of Air Sampling and Analysis

ASTM E-02.10, Non-Metallic Materials

ASTM E-02. 13, Nomenclature

ASTM D-01, Paint and Related Coatings

ASTM D-19, Water

Chairman, FACSS Governing Board

Past-President, Society for Applied Spectroscopy

Professor-in-charge, ACS Short Course on "Atomic Absorption Spectroscopy"

Task Force Leader, Scientific Instrumentation Information Network

and Curricula (SUNG) for project on "Atomic Absorption Spectroscopy"

Column Editor, Journal of Applied Spectroscopy

98
Ronald W. Shideler

Member, NBS Electronics Storeroom Committee

Yung-Chi Wu

Member, ANSI Z228 Incineration

Council Member, ASME Codes and Standards

Rolf L. Zeisler

Member, IAEA Advisory Group on Nuclear Techniques in Environmental

Health Studies of Mineral Pollutants

Technical Program Committee International Symposium on the Use

and Development of Low and Medium Flux Research Reactors

NBSR Hazard Evaluation Committee

Chairman, Trace Element Analysis Committee, Biomedical Division,

American Nuclear Society

4. Other

a. Seminars

October 14, 1982

December 16, 1982

January 27, 1983

February 2, 1983

April 6, 1983

May 25, 1983

Professor William H. Zoller, Analytical Nuclear

and Environmental Chemistry Division, Department

of Chemistry, University of Maryland, "The

Chemistry of Remote Area Aerosols."

Dr. John A. Miller, Air Resources Laboratory,

NOAA, "Acid Precipitation."

Dr. R. Jack Pickering, United States Geological

Survey, "Atmospheric Deposition Monitoring

Under the National Acid Precipitation Assessment

Plan (NAPAP)."

Mr. Walter Slavin, Applied Research Department,

Perkin-Elmer Corporation, "Practical Experiences

with the Modern Graphite Furnace."

Mr. William P. Reed, Production and Certification

Programs, Office of Standard Reference Materials,

National Bureau of Standards, Washington, DC,

"Research and Measurement Needs for the Certification of Standard Reference Materials,

Plans, and Perspectives for FY 84."

Dr. Walter Mertz, Beltsville Human Nutrition

Research Center, U.S. Department of Agriculture,

Beltsville, Maryland, "Health Implications of

Modern Nutrition Research-Relation to Progress

in Analysis."

99
b. Conferences Sponsored

September 19-20, 1983

September 21, 1983

R. Zeisler, Eighth U.S. /German Seminar

of State and Planning on Environmental

Specimen Banking, National Bureau of

Standards, Gaithersburg, MD.

R. Zeisler, International Review of Environmental Specimen Banking, National Bureau

of Standards, Gaithersburg, MD.

c. Seminars Organized

W. F. Koch, Workshop on Direct Potentiometric Measurements in Blood,

National Bureau of Standards, Gaithersburg, MD, May 18-20, 1983.
III. Organic Analytical Research Division

Willie E. May, Acting Chief

Dennis J. Reeder, Deputy Chief

A. Division Overview

The Organic Analytical Research Division conducts research to develop and

improve techniques for the preparation, purification, characterization, and

analysis of organic compounds and uses these techniques in the solution of

analytical problems related to national needs. The Division's research is

carried out by five groups organized along functional lines: Bioanalytical

Techniques, Electrochemistry, Gas Chromatography, Liquid Chromatography, and

Mass Spectrometry. During the past year, the Division has been actively

engaged in the application of organic analytical chemistry to measurement

problems related to energy, the environment, health and clinical chemistry,

and food and nutrition. Results of Division research are utilized by industry,

other Federal agencies, public and private institutions, and research programs

at the National Bureau of Standards. Research efforts during the past year

have resulted in over 50 articles being published or in press in archival

journals.

As in past years, our research efforts have been in support of basic

organic analytical chemistry, in support of Other Agency requests, and in

short-term projects performed on a service analysis basis. This year, substantial progress has been made in research on basic techniques in organic

analytical chemistry and in furthering our understanding of measurement

principles in this area. The Division is now actively involved in three

competence building programs selected for funding by the NBS Director:

Organic Electrochemistry, Analysis of Ionization Mechanisms and Ion Structures

in Organic Mass Spectrometry, and Bioanalytical Techniques—The Use of Proteins

in Analytical Chemistry. In addition, we have continued our research

activities in liquid chromatographic retention mechanisms, funded out of our

Division's STRS base. Details concerning these activities are provided in the

group overviews and technical reports that follow.

During the past year, we have performed service analyses in support of

several NBS and other government agency programs. Some examples follow. We

completed our first set of organic analyses, organochlorine pesticides in 30

human liver samples, in support of the Environmental Specimen Bank program.

In addition, we analyzed over 28 oil samples for PCB content in support of the

NBS Recycled Materials program. We also assisted the Quality Assurance Branch

of EPA/Cincinnati by analyzing their performance evaluation and quality control

standards, prepared by an outside contractor, to establish traceability to

NBS. Details concerning this activity are given in technical report 9.

Collaborative research efforts have begun with the two other divisions in

the Center for Analytical Chemistry. Research in conjunction with the Gas and

Particulate Science Division is providing a foundation for the development of

an isotope dilution gas chromatography/mass spectrometry procedure for analysis

of low ppb levels of toxic organics in air. Joint studies have been initiated

with the Inorganic Analytical Research Division for neutron activation analyses

of electrophoretic gels to provide information on the distribution of silver

in gels and give insight into the mechanism of silver staining.

101
The major portion of our efforts in support of the NBS Standard Reference

Materials (SRM) program was focused on the development of synthetic calibration

mixtures to complement existing matrixed SRM's. We also supplied information

values for a number of SRM's, certified in previous years, in an attempt to

increase their utility. Details concerning these and other SRM activities are given in technical reports 2, 4, 5, 6, 10, and 11 and in the group overviews.

Our projected SRM research activities for the coming year include the beginning

of a staged and comprehensive program for the development of SRM's for dioxins

and dibenzofurans.

The toxic chemicals handling laboratory, completed during FY 1982, has

become fully operational --a protocol for its use has been written and put into

use. A new gas chromatography laboratory was completed in February. We are currently completing the design of a bioanalytical facility and expect to

begin construction early in FY 1984.

Our programs in liquid chromatographic retention mechanisms and mass spectrometric ionization mechanisms were bolstered by NRC postdoctoral fellows

in the respective areas. Each will remain with us for an additional year. We

also plan to actively pursue postdoctoral fellows for the gas chromatography,

organic electrochemistry, and bioanalytical areas during the coming year. We are continuing our collaborative efforts with the College of American Pathologists by the addition of a new research associate. Dr. Kwokei Ng, to replace

Dr. Michael Welch, who has joined our full-time staff. Our full-time hiring

priorities include a senior level liquid chromatographer and a biochemist with

experience in enzymes and enzyme immobilization.

In keeping with research planning which we have been actively doing for

the past several years, we anticipate pursuing some very exciting research

areas during the coming year. We will continue to work on high-priority

analytes, such as creatinine, for clinical chemistry; to extend the usage and

capabilities of the NMR facility; and to further improve our protein separation

capabilities while developing standard marker proteins for two-dimensional

electrophoresis. We also plan to expand our efforts in interfacing liquid

chromatography and/or metal -ion affinity chromatography with electrophoretic

methods. We will continue to apply the use of electrochemical detection

combined with liquid chromatographic separations to the analysis of trace

organic and organometallic species. The spectroelectrochemical study of metal

croconates will be completed in FY 1984 and the analytical applications of

chemically modified electrodes will be pursued. Our efforts in liquid

chromatography/mass spectrometry will continue, as will our studies of the

photodissociation of ions and structures of ions and molecules. Our studies

in liquid chromatographic retention mechanisms will continue and a program

in supercritical fluid chromatography will be initiated.

Finally, as mentioned in last year's report, we have begun to focus a portion of our research efforts in the areas of nutrient and hazardous waste

analyses. Our research in both areas is beginning to bear fruit and these new thrusts will continue. Our research in the nutritional area will be expanded

to include serum as well as food analysis. National concern regarding the

presence of dioxins and dibenzofurans in the environment is demanding a stronger effort in that area.

102
1 . Bioanalytical Techniques Group: Overview

The Bioanalytical Techniques Group has continued its programs in the

competence area by further research on protein separations using electrophoresis. The Spectroscopy Group was merged into the Bioanalytical Techniques

Group in November, with one of the members devoting time to investigation of

protein staining mechanisms. Additionally, the continued work in the clinical

chemistry area has resulted in the development of isotope dilution/mass

spectrometric (ID/MS) methods for creatinine and urea.

Electrophoretic methods for separation and detection of proteins were

implemented and improved. The "rocket" technique using antiserum in an agarose matrix was shown to be useful for quantifying human albumin. This

method was used to determine the albumin content of SRM 909. Further work

using this technique is planned.

Thin-layer isoelectric focusing (TL-IEF) shows promise as a rapid method

for screening proteins. This technique makes use of high-field gradients

(>400 volts/cm) to produce rapid focusing in thin (125 ym) gels. To dissipate

the Joule heat thus formed with up to 20 W of power, an efficient thermoelectric device cools the plates to constant temperature. Silver staining of

the focused proteins gives results within one hour after the electrophoretic

run of 40 minutes. Up to 60 bands of focused proteins have been observed in

serum samples. The extraordinary sensitivity of this method is evidenced by

the small amount of protein required. Typically, 1 pL of a 1:20 dilution of

serum is used for separations. This means that we are detecting approximately

5-50 ng of protein per band.

The two-dimensional electrophoresis (2-DE) work moved forward with the

acquisition of equipment capable of running ten large gels at one time. The

set-up and implementation of the larger capacity was greatly helped by the

talents of Professor Frederic Giere, a summer faculty hire from Lake Forest

College, Lake Forest, IL. Professor Giere has had many years experience in

teaching workshops on 2-DE. The system was used to examine fish serum,

bacterial membrane proteins, and enzymes as marker proteins. Preliminary

studies showed great heterogeneity among commercially available molecular

weight marker proteins.

The studies that began last year to assess the effect of composition of

sodium dodecyl sulfate (SDS) preparations on 2-DE separations were extended

and completed (see Technical Report 12). The results of that work were

presented at an invited session of the annual meeting of the Electrophoresis

Society.

Several publications are being drafted to report the results of the

protein separations stemming from our collaborative work with the Sandy Hook

Marine Laboratory.

We initiated joint studies with Rolf Ziesler of the Inorganic Analytical

Research Division for neutron activation analysis of electrophoretic gels to

provide information on the distribution of silver in the gels and give insight

into the mechanism of silver staining. A major effort leading to this work

103
was the compilation and comparison of silver staining methods from available

literature.

Work in the spectroscopy area resulted in five publications and several

major developments. A new pulse sequence has been developed for doing twodimensional, heteronuclear J-resolved 13 C NMR, with polarization transfer by

the DEPT technique. The sequence has been applied to analysis of the anomeric

and ring form equilibria of digitoxose. Spectrum editing of the 15 N NMR

spectra of aminoglycoside antibiotics has been implemented by the DEPT technique. In addition, two-dimensional, proton-proton shift correlated NMR

(COSY) has been applied to the almost complete assignment of the proton NMR

spectra of the angiotensin SRM and also the different forms of digitoxicose.

Further, NMR methods have been developed for the analysis of water in SRM urea and of lactose in SRM 1549, Non-Fat Dry Milk. Certification of SRM 1595,

Tripalmitin, has been completed. Recertification of SRM dextrose is underway.

Continuing activities in the clinical area have focused on improvements

to the wet-chemical steps, including spiking, analyte isolation, and derivative

formation, in order to minimize errors in the ID/MS definitive methods. A

manuscript describing our serum urea ID/MS definitive method is being reviewed

within NBS prior to submission to Analytical Chemistry for publication.

Creatinine doubly labeled with carbon-13 was synthesized for the ID/MS method

we are developing for creatinine in serum. We had been using creatinine-d3 with the deuterium atoms in nonreactive positions in the molecule, but the

precision was much less than satisfactory and there was evidence of bias

between independently prepared sets of standards. With the creatinine- 1C2 , the precision was very much better, and no bias was observed between sets

of standards.

We began planning, design, and initial work on a triple-module modernized

laboratory for biotechnology. This laboratory will have a ten-foot hood for

handling many of the volatile solutions used in electrophoresis. In addition,

an adjoining section will house many of the instruments that are now scattered

in various laboratories. The laboratory will provide working space for

approximately six chemists and is expected to improve efficiency in operations.

During FY 1984, we will continue to improve our separation capabilities,

while developing protein marker standards. The hire of a biochemist with

experience in enzymes and enzyme immobilization is expected to add considerably to the expertise of the group. We are actively recruiting during this

time. We plan to expand our efforts in interfacing techniques, such as liquid chromatography, metal -ion affinity chromatography , and other separations methods with the analytical tools of electrophoresis.

A workshop on 2-D electrophoresis standardization is planned for FY 1984

with preliminary planning underway. Contacts for plenary lectures have been

made.

Dennis J. Reeder, Group Leader; Lyle A. Alexander, Alex Cohen, Bruce Coxon,

Andrew E. Davidson, Alexander J. Fatiadi, Frederic A. Giere, Diane K. Hancock,

Cindy L. Hsu, Maria L. Luzarraga, Millard Maienthal, Robert Schaffer

104
2. Electrochemistry Group: Overview

The competence building program in organic electrochemistry has continued

to make good progress toward its research goals this year, and we have been

able to apply the results of some of our research to NBS programmatic areas. During the fifth year of this effort, our staffing has remained stable and

most of the major pieces of equipment are now operational. Some needs still

exist for instrumentation, especially in the area of automation.

Our research continued to be focused on the study of organic and organometallic redox reactions using state-of-the-art electrochemical techniques:

cyclic voltammetry, chronoamperometry , chronocoulometry , and rotating ringdisk electrochemistry; hybrid techniques, such as spectroelectrochemistry and

liquid chromatography with electrochemical detection; the preparation and

evaluation of chemically modified electrodes; and mathematical modeling of

electrochemical processes in support of the group research activities.

In one study, the electrochemical behavior of the laser dye, 4-[2-(5-

phenyloxazolyl )]-l -methyl pyridini urn tosylate was examined. In aqueous solution,

the one-electron reduction of this cation is characterized by very strong product

deposition as evidenced by a pronounced stripping wave on the oxidative scan.

An extensive spectroelectrochemical study using gold-mini grid optically

transparent thin-layer electrodes is nearly complete, with results showing

characteristic and diagnostic behavior associated with a product-deposition

process. In double potential step chronocoulometry, unusual charge-time

features are also observed related to the product deposition. This behavior

has been mathematically modeled on the assumption of phase equilibrium between

the deposited product and the solution adjacent to the electrode. Analytical

equations were developed for the charge-time plot in chronocoulometry and the

Nernst plot in spectroelectrochemistry. These equations not only describe the

experimental behavior but also provide the means to obtain kinetic and

thermodynamic information, such as the diffusion coefficient, formal potential,

electrochemical stoichiometry, and solubility of the reduced form of the dye,

from the experimental data.

Cyclic voltammetry, chronocoulometry, and spectroelectrochemistry are also being used to study the electrode reactions of copper(II) complexes of

dithiosquarate, dithiocroconate, and dicyanomethylenedithiocroconate in

nonaqueous media. The formal redox potentials and the number of electrons

involved in the redox processes are being evaluated spectroelectrochemically.

From the electrochemical data, we are attempting to determine the effects of

the ligands on the copper(II) reduction process.

The development of selective analytical sensors and catalytic surfaces

for electrosynthesis may be achieved by the chemical modification of electrodes.

Furthermore, modification by means of polymer films offers the advantages of

inherent chemical and physical stability, incorporation of large numbers of

catalytic sites, and relatively facile electron transport across the film. As

reported last year, we have followed two approaches in the fabrication of

polymer-film electrodes: electrochemically initiated polymerization and spindip coating. In both cases, two types of polymers have been studied, those

which covalently bind the electroactive sites and ion-exchange polymers which

electrostatically sequester the electroactive sites. In addition, we have

investigated the electrochemical behavior of doped and undoped polymer films

105
of polyacetylene and polypyrrole which are electronic conductors, in contrast

to previously studied polymer films which were ionic conductors with site-tosite charge transfer.

Our investigation of the behavior of charged and uncharged film penetrants

has been continued. The overall catalytic efficiency of these films will

depend on the mobility of the substrate molecules across the film. With the

completion of our computer-controlled system for the acquisition of currenttime or charge-time transient responses, this area of investigation is now proceeding at a much faster and more efficient rate. In-depth studies have

been performed on [Ru(II)(bpy) 2 (4-VP) 2 ]*2PF6 and [Ru(II) (bpy) 2 (4-VP) 2 ]*2(styrene

sulfonate) polymer films, where the two films differ as to the degree of

cross-linking. Polymeric ion-exchanger films of polyethylene methacrylate and

Nafion have been derivatized with cationic molecules such as methyl viologen,

organic laser dyes, and transition metal complexes. These derivatized films

have been evaluated using cyclic voltammetry and charge-time transient studies.

Our investigation of the mass transport processes within these polymeric films

is critical for the fundamental understanding of the electronic and structural

changes occurring during the electrochemical conversion.

In conjunction with the Liquid Chromatography Group, an analytical method

has been developed for the determination of phenol and ortho-cresol in crude

oil based on the extraction of the diluted oil with aqueous base followed by

neutralization of the phenolate anions. The final determination was made

using reversed-phase liquid chromatography coupled to oxidative detection at a glassy carbon electrode.

Work is continuing on several aspects of the chemistry, electrochemistry,

and analytical determination of nitro-polynuclear aromatic hydrocarbons (N-PAH).

We are collaborating with Alexander Fatiadi of the Bioanalytical Techniques

Group by evaluating the products of nitration reaction mixtures and various

purification schemes. The goal of this project is to provide suitable standards

for the analytical and electrochemical studies of N-PAH. We are also studying

the photodegradation products of N-PAH in solution. The electrochemical

reduction reactions of these compounds are being investigated in aqueous and

nonaqueous media using normal, reverse, and differential pulse polarography

and cyclic voltammetry. Coulometry is also being used in conjunction with

liquid chromatography to study the complex, multi step reduction of N-PAH.

Collaboration with the Liquid Chromatography Group has resulted in the

development of two approaches to the determination of N-PAH in diesel exhaust

particulate extracts. These liquid chromatographic methods will be used

along with gas chromatography/mass spectrometry for the certification of

several N-PAH in SRM 1650, Diesel Exhaust Particulates.

Our plans for the coming year call for continued research on several of

the above projects with special emphasis in the area of chemical modification

of electrodes as selective organic sensors. We expect to continue to adapt

our research efforts to address the analytical needs of the Center.

Richard A. Durst, Group Leader; Elmo A. Blubaugh, Richard T. Burke,

Belle Liang, William A. MacCrehan, Gwendolyn S. Marbury, Scott R. Mund,

William T. Yap

106
3. Gas Chromatography Group: Overview

Three areas of analytical research have been explored by the Gas

Chromatography Group during the past year. Our program in gas chromatography

combined Fourier transform infrared spectroscopy (GC/FTIR) was continued. A new laboratory was designed and constructed to house the GC/FTIR and the

instrument was installed and optimized therein. A number of inlet configurations and columns were utilized in an attempt to increase the apparent

sensitivity and resolution of the system; however, GC/FTIR performance is still

below that which is needed to obtain useful spectroscopic identifications of

components in complex environmental samples. We hope to be able to attract a postdoctoral fellow or similar person to work in this area, as a complete

redesign of the GC interface will probably be required if high quality data

is to be realized.

We have modified the gas saturation system developed and used previously

by the Liquid Chromatography Group to measure vapor pressures of polynuclear

aromatic hydrocarbons (PAH) at temperatures between 60-300 °C. The work done

previously in the Liquid Chromatography Group covered the 10-50 °C range. The

log P versus 1/T plots obtained using this system are linear and agree with

literature values. A variant of this system is being employed in this laboratory for the introduction of well-defined amounts of gaseous PAH internal

standards onto sampling tubes containing porous polymers (XAD-2). Using these

spiked tubes and the sampling system developed last year, we have determined a set of potassium correlated PAH profiles from wood burning stove emissions.

We have also pursued a number of basic chromatographic investigations.

Split, splitless, and on-column injection techniques have been modified to gain

an increase in chromatographic precision. The performance of two sulfurspecific detectors, electrolytic conductivity detector, and a flame photometric

detector were compared using sulfur PAH standards. Although the electrolytic

conductivity detector was considerably more sensitive, it suffered from high

noise and baseline drift. A post-column trapping technique was developed to

remove polar solvents, such as methanol, while allowing nonpolar analytes

eluting with the solvent to pass only slightly broadened to the detector. In

collaboration with the Liquid Chromatography and Mass Spectrometry Groups,

quantification and identification of minor PAH constituents in Washington,

St. Louis, and Philadelphia dust samples have been accomplished using high

resolution techniques.

As in past years, the group has been actively involved in the Standard

Reference Materials program. We have participated in the certification

analyses for the following materials:

1. SRM 1581, Organics in Drinking Water - Completed analysis of

halocarbons and developed delivery system.

2. SRM 1582, Petroleum Crude Oil - Information values for phenol

and o-cresol provided.

3. SRM 1583, Pesticides in Isooctane - Completed analysis of all

analytes.

107
4. SRM 1585, Polychlorinated Biphenyl Congeners in Isooctane - Completed analysis of all analytes.

5. SRM 1586, Unlabeled and Deuterium Labeled Priority Pollutants - Chemical purities completed; ampouling completed and analyses

proceeding.

6. SRM 1584, Phenols in Methanol - Analysis of 11 analytes in

progress.

In collaboration with the Mass Spectrometry Group, a synthetic leachate

sample was prepared, ampouled, and analyzed. This surrogate standard will be

used by EPA/Las Vegas for proficiency testing. In addition, two sets of

solutions used by EPA/Research Triangle Park as marker compounds for its

"Master Analytical Scheme" have been analyzed for nitrobenzene and t-butanol

Five sets of check samples were analyzed for EPA/Cincinnati . Each sample

set contained related halogenated compounds ranging from chlorinated solvents

to pesticides at concentrations of between 1 to 1000 yg/g. A total of 114

ampoules were analyzed and over 650 separate analytical determinations were

made. The samples (except for one set) were analyzed on our computercontrolled auto-injection GC system.

In collaboration with the Bioanalytical Techniques Group, the purity of

17 samples of sodium dodecyl sulfate (SDS) was determined. This analysis

required the use of a double extraction technique on the hydrolyzed SDS

samples. The results of the analyses were correlated with protein separations

performed by two-dimensional electrophoresis (2-DE).

A new project, funded by the Law Enforcement Standards Laboratory, was initiated in the group. The objective of the program was to determine arson accelerants from soot collected remotely from the point of fire origin. It was found that soot originating from common accelerants (except for alcohol)

contained traces of PAH, while soot arising from the normal contents of a house (wood, paper, plastics, synthetics, etc.) do not contain the PAH

markers.

In support of the U.S. Pilot Environmental Specimen Bank program, the

pesticide contents of 30 human liver tissue samples were analyzed by electron

capture gas chromatography. Also, 28 samples of oil submitted by the recycled

oil repository were analyzed for polychlorinated biphenyls (PCB). The samples were analyzed using our bidimensional chromatographic technique.

A new gas chromatography laboratory was completed and the group has

occupied the facility since February. The group acquired a second automated

gas chromatographic system and will receive a new integration/control system

shortly.

108
In FY 1984, the group will continue in its research program as previously

reported. Special emphasis will be placed on high resolution techniques and new methods of analysis for compounds such as dioxins and dibenzofurans. The

group also plans to collaborate with the Liquid Chromatography Group in

developing a program in supercritical fluid chromatography.

Stephen N. Chesler, Group Leader; Delmo Enagonio, Franklin R. Guenther,

Reenie M. Parris, Richard E. Rebbert

4. Liquid Chromatography Group: Overview

The research activities in the Liquid Chromatography Group involve both

basic and applied components. A major effort continues to be focused on gaining a clearer understanding of the chemical and physical processes that

contribute to retention in reversed- and normal -phase liquid chromatography

(LC). We have also extended our efforts in the development and use of multidimensional LC systems (chromatographic selectivity) in combination with

selective detectors or detection systems for the determination of individual

compounds in complex mixtures. These research efforts have resulted in 25

publications being co-authored by members of the group (and frequently with

members of other groups) during the past year.

Specific research accomplishments for the past year are as follows:

(1) Evaluated the feasibility for modifying LC column selectivity by mixing

C18 materials with different selectivities both intimately and by short

columns in a series. We found that columns with specific selectivities could

be "customized." (2) Developed synthesis conditions and procedures for

characterization of monomeric, oligomeric, and polymeric C18 phases. Evaluated

selectivity differences among these different phase types using selected probe

molecules. (3) In conjunction with the Gas Chromatography (GC) and Mass

Spectrometry (MS) Groups, provided a detailed characterization of air particulate samples collected in Washington, DC (SRM. 1649), St. Louis, MO (SRM 1648),

and Philadelphia, PA. Several polynuclear aromatic hydrocarbons (PAH) were

identified (based on GC and LC retention times, mass spectra, and fluorescence

spectra) for the first time on air particulate samples. Quantitative data

were provided for over 100 components per sample. (4) In conjunction with

the GC Group, analyzed over 30 liver specimens for determination of organochlorine residues. An interlaboratory comparison exercise for measurement of

these compounds between NBS and two German laboratories was completed. (5) In

conjunction with the Electrochemistry Group, completed the development of two

methods for determination of nitro-PAH in complex mixtures (technical report

23). (6) Developed methods for analysis of ascorbic acid, nicotinic acid, and

nicotinamide in powdered milk formulations in preparation for supplying

concentration values for those analytes in SRM 1549, Non-Fat Dry Milk. In

addition, we made contributions to several Other Agency projects.

As in past years, the group has been actively involved in the NBS Standard

Reference Materials (SRM) program. We have participated in analyses leading

to the certification or characterization of the following materials:

109
1. SRM 1582, Petroleum Crude Oil - Completed analysis for six PAH and,

in conjunction with the Electrochemistry Group, two phenols

(technical report 23).

2. SRM 1514, p-Aminobenzoic Acid in Phenacetin - Completed analysis of

nominal 0.7, 2.0, and 5.0 mole percent sets (technical report 10).

3. SRM 1584, Priority Pollutant Phenols in Methanol - Ampouling complete;

analysis for five phenols completed (technical report 10).

4. SRM 1549, Non-Fat Dry Milk - LC values provided for vitamin C,

vitamin D2 , nicotinic acid, nicotinamide, and lactose. This SRM will

be certified for trace metals content and is intended primarily for

evaluating procedures and equipment used for trace metals analysis.

5. SRM 1648, Urban Particulate Matter - Provided information values for

13 PAH. This SRM was issued in 1978, certified for inorganic

constituents only.

6. SRM 911, Bilirubin - Determined the relative proportions of the

three structural isomers of bilirubin (technical report 5). This

SRM was certified in 1971 for bilirubin content, but no information

was provided on the individual isomer content.

7. SRM 1650, Diesel Soot - Ampouling has been completed and analyses

for selected PAH and nitro-PAH are in progress.

8. No number assigned yet, Nitrated-PAH in Solvent - Stability of five

nitrated PAH in several solvents and conditions of storage being

investigated; ampouling of the SRM solution is scheduled for

January 1984 (technical report 10).

Our program in LC retention mechanisms has been bolstered by the addition

of Dr. Lane Sander as a NAS/NRC Postdoctoral Fellow from the University of

Washington. Dr. Sander's work has focused mainly on stationary phase contributions to LC retention. Dr. Sander has been primarily responsible for the

synthesis and characterization of the monomeric, oligomeric, and polymeric C 18

phases mentioned earlier. This year, with the addition of Dr. Joe Foley, a NAS/NRC Postdoctoral Fellow from the University of Florida, we will broaden

our investigations of LC retention mechanisms to include the role of the

mobile phase.

During the coming year, we will continue our efforts in LC/MS (in con- junction with the Mass Spectrometry Group), the development and use of

multidimensional approaches for the analysis of complex mixtures, and work in

the area of post- and pre-column derivatization. We plan to begin work in the area of both packed and capillary supercritical fluid chromatography. Our

efforts in the environmental area will continue to decrease, while we expand

our clinical and food/nutritional programs.

Willie E. May, Group Leader; Bruce Benner, Jr., Iona N. Black,

Jeanice M. Brown-Thomas, Richard G. Christensen, Walter F. Kline, Linda D. Fong,

Sam A. Margo! is. Lane C. Sander, Stephen A. Wise

110
5. Mass Spectrometry Group: Overview

The Mass Spectrometry Group has pursued research in a number of areas involving both basic and applied research. Efforts are continuing to develop

mass spectrometric methods for the accurate quantitation of individual organic

compounds in complex matrices, to refine the liquid chromatography/mass

spectrometry (LC/MS) interface, and to use it for quantitation in conjunction

with the triple quadrupole mass spectrometer system. Research has also

continued on the laser induced photodissociation of ions and the collision

induced dissociation of ions as part of the competence building program in mass spectrometry, "Analysis of Ionization Mechanisms and Ion Structures."

Investigations have begun on two projects in conjunction with the Gas and

Particulate Science Division; one on the mechanistic relationship between

field desorption mass spectrometry and laser desorption mass spectrometry,

and the other on development of gas chromatography/mass spectrometry (GC/MS)

methods and standards for trace organic chemicals in air.

Quantitative measurements made in the Mass Spectrometry Group over the

past year have been used for the certification of several SRM's including

SRM 1582 (Wilmington Crude Oil), SRM 1583 (Pesticides in Isooctane), and

SRM 909 (Human Serum).

Development of isotope dilution definitive methods for the quantitative

determination of human serum constituents has continued in collaboration with

the Bioanalytical Techniques Group. Human Serum SRM 909 has now been certified

for four organic analytes and measurements have begun on creatinine. The

concentration of glucose in SRM 909 has been remeasured because the glucose

level has been found to change with time. As mentioned previously, a manuscript describing the ID/MS method for serum urea has been completed and will

be submitted to Analytical Chemistry . A manuscript describing our ID/MS

method for uric acid is in preparation. Work has begun on preparation of a labeled tripalmitin to be used in an ID/MS method for triglycerides.

Research in the environmental area has focused on the development of

accurate quantitative methods for the determination of trace level toxic

organic compounds in a variety of sample types. Research supported by the

Department of Energy (DOE) has led to the development of GC/MS methods for the

quantitation of organic compounds in aqueous leachates of hazardous wastes.

The method, which involves solvent extraction of an aqueous leachate followed

by capillary column GC/MS with selected ion monitoring, provides the sensitivity

and selectivity necessary for quantitation at the part-per-billion level. The

method has been used to measure organic compounds in aqueous leachates of two

DOE-supplied materials: (1) solvent refined coal vacuum still bottoms and

(2) an H-coal filter cake material. Capillary column GC/MS using positive

chemical ionization has been used to determine the concentrations of seven compounds in a petroleum crude oil sample, which is to be issued as SRM 1582.

The analytes include five polynuclear aromatic hydrocarbons (PAH) and a sulfur- and a nitrogen- heterocyclic compound. Preliminary investigations on the use of methane negative chemical ionization (NCI) mass spectrometry

indicate that this may be a sensitive and highly selective technique for

the determination of certain types of compounds including several PAH and

pesticides. A gas chromatography/negative chemical ionization mass spectrometry (GC/NCIMS) method was used to measure the concentrations of three PAH

111
in SRM 1582. We have also used GC/NCIMS to measure the concentrations of

heptachlor epoxide, aldrin, and y-BHC in SRM 1583, Pesticides in Isooctane.

In conjunction with the Gas Chromatography and Liquid Chromatography

Groups, the development of isotopically labeled marker compound standards for

use in EPA's "Master Analytical Scheme for the Analysis of Organic Compounds

in Water" and "Comprehensive Scheme for Solids, Sediments, and Sludge" and

stability studies of the marker compound solutions were completed during the

past year.

Capillary column GC/MS with selected ion monitoring detection was used for

the determination of 12 toxic organic compounds in a gravimetrically prepared

liquid hazardous waste which was delivered to the EPA for use in its quality

assurance monitoring programs. Measurements made on this sample have enabled

us to assess the accuracy and precision achievable in the analysis of a hazardous waste sample. Work is continuing on the development of a solid

hazardous waste quality assurance material for the EPA. This material is to

be prepared so that known amounts of selected organic compounds will be

obtained in aqueous leachates.

As part of a joint project with the Gas and Particulate Science Division

for the EPA on research leading to standards for hazardous chemicals, the

Mass Spectrometry and Gas Chromatography Groups are developing a method for

measuring toxic organic compounds in gases at the ppb level. A cold trapping

technique followed by GC/MS using isotope dilution methodology adapted from

the definitive methods has been applied to bromobenzene at 30 ppb in nitrogen

with promising results. We are working to extend the method to 1 ppb and to

establish the accuracy and precision of the method. Such a method will

provide EPA with a direct way to determine the sensitivity of a GC/MS system

and NBS with an independent method for certifying organic compounds present at

low levels in gases.

Studies on the collision of ions with reactive neutral species, a part

of the competence building program in mass spectrometry entitled "Analysis

of Ionization Mechanisms and Ion Structures," have begun using a newly acquired

triple quadrupole mass spectrometer. The MS/MS instrument is also being used

in conjunction with our LC/MS interface in an attempt to perform direct

LC/MS/MS determination of dibenzothiophene in SRM 1582, Wilmington Crude Oil.

Research in laser photodissociation of organic ions has continued this year.

Ions generated by electron impact ionization have been subjected to laser

induced dissociation in both the ion source and the first field free region

of a double focusing mass spectrometer. Design has been completed for an apparatus to allow study of the photodissociation in the first field free

region of ions generated by field ionization and field desorption and con- struction is underway.

A study of the mechanisms involved in the laser desorption (LD) and field

desorption (FD) mass spectrometry of organic compounds has been initiated.

The LD work was done on a laser microprobe mass analyzer (LAMMA) in collaboration with the Gas and Particulate Science Division. Several organic acids

and salts have been examined in this work that looks at some of the existing

theories of ion formation proposed for desorption techniques.

112
During the past year. Dr. Corazon Vogt, University of Missouri, Columbia,

MO, conducted sabbatical research with the Mass Spectrometry Group. Dr. Vogt

assisted in the development of methods for the quantitative determination of

trace level organics in aqueous leachates of hazardous wastes. We were also

fortunate to have Dr. Zhao Min from the People's Republic of China working in our group for six months. She was involved in both the definitive methods

development and ionization mechanisms programs.

We plan to continue the ongoing projects with which the group is involved

including the environmental projects with special attention to further investigation of the utility of negative chemical ionization, the development of

isotope dilution definitive methods, and the study of the photodissociation of

ions and the collision of ions with reactive neutral molecules as sources of

information on the structures of ions and molecules.

Edward White V, Group Leader; Gary D. Byrd, Laurence R. Hi 1 pert, Zhao Min,

Stanley Meiselman, Kristy L. Richie, Lorna T. Sniegoski, Corazon R. Vogt,

Michael J. Welch

113
B. Selected Technical Reports

(Organic Analytical Research Division)

1 . Synthesis and Characterization of Chemically Bonded C 18 Phases for

Liquid Chromatography (15320)

L. C. Sander, S. A. Wise

To a large extent, the chromatographic properties of a reversed-phase

liquid chromatographic (LC) sorbent are dependent on the conditions of the

bonded phase synthesis. Pronounced differences in selectivity have been

observed between monomeric and polymeric alkyl bonded phases, especially in

the analysis of polycyclic aromatic hydrocarbons. An understanding of the

origin of these differences is important both theoretically and practically.

Such knowledge would be valuable in methods development and would permit the

retention behavior of certain compounds to be more accurately predicted. In

the past, we have examined selectivity differences for various commercially

available C18 materials. However, these studies were somewhat limited since

the exact details of the synthesis conditions were unavailable. In this

study, a number of monomeric, polymeric, and oligomeric (intermediate) C18

bonded phases were prepared (i.e., synthesized) on a variety of silica substrates and the selectivity differences were evaluated. The goals of this

study were threefold: to examine changes in selectivity with phase type

(monomeric, polymeric, oligomeric), to observe the effects of surface coverage

on selectivity for polymeric phases, and finally to study any effects that the

silica substrate might impart to solute retention.

Five different base silicas were used in the preparation of the bonded

phase sorbents. The physical properties of these substrates vary considerably,

o as shown in Table 17; however, all five silicas have 300 A pore diameters.

The various LC phases prepared are listed in Table 18. Surface concentration

values (ymol/m2

) for the oligomeric series of phases were larger than the

monomeric phases, and the polymeric phases had the largest C18 surface concen- trations of all phase types. Furthermore, within the polymeric phases, chain

density increases with the amount of water added during phase synthesis.

Selectivity differences among the phases were examined using a 16 polycyclic

aromatic hydrocarbon mixture (SRM 1647). Separations of this mixture on three

representative phases are illustrated in figure 19. The best separations were obtained with moderately loaded polymeric phases. The oligomeric phases gave

only partial resolution of benzo[k]fluoranthene and benzo[a]pyrene (peak

numbers 12 and 13), while on the monomeric phases these and several other

components were unresolved. A simple empirical LC test was devised to gauge

the relative monomeric or polymeric nature of a phase. The elution order of a three component mixture, phenanthro[3,4-c]phenanthrene (PhPh), 1 ,2:3, 4:5, 6:7,8-

tetrabenzonaphthalene (TBN), and benzo[a]pyrene (B[a]P) was observed to be

strongly dependent on the type of phase and surface coverage. Using a mobile

phase of 85 percent acetonitrile/water, the mixture was analyzed on each of

the columns (figure 19). On monomeric phases, the elution order was B[a]P,

PhPh, TBN; on oligomeric phases, PhPh, B[a]P, TBN; and on polymeric phases,

PhPh, TBN, B[a]P. Depending on the elution order of a mixture, new phases

114
could be rapidly screened and column selectivity toward more complex PAH

mixtures predicted.

The effect of pore size of the silica substrate was also investigated for

the polymeric phases. Polymeric phases were produced on four silica substrates

o o with 60, 100, 150, and 300 A pore diameters. The 100 and 150 A substrates were

o experimental silicas of the same composition as silica A, Table 17. The 300 A

o silica is listed as silica C, and the 60 A silica, an irregular substrate

material not listed in Table 17. Differences in selectivity were clearly

evident as being a function of pore size (figure 20). Using the threecomponent test mixture, the polymeric nature of the phases was judged to

increase with increasing pore size. Polymeric phases produced on small pore

substrates had chromatographic properties similar to those of monomeric phases,

and separation of all 16 components was not possible. Baseline separation of

o all components was possible using the larger (150 and 300 A) pore substrates.

Future studies on bonded phases will be directed toward the production of new

phases using ultralong alkyl chains with both monomeric and polymeric surface

modification.

Table 17. Physical Properties of Silica Substrates.

Silica

Specific Surface

Area (m2 /g)

a Shape

Pore Volume3

(mL/g)

Percent Carbon

(Silica Background)

Silica A 45 spherical 0.42 0.06

Silica B 60 spherical 0.6 0.10

Silica C 90 spherical 0.66 0.41

Silica D 200

b spherical 2.0 0.18

Silica E 250 irregular 1.52 0.11

a Nominal values reported by the manufacturer.

^Manufacturer's surface area value is 250 m

2 /g; the value listed was determined

by BET measurement.

115
Table

18.

Physical

and

Chromatographic

Properties

of

C

18

Bonded

Phases.

o_ -Z LO CO CO r— CO LO 00 00 1^. CO LO 00 *3- CO

D_ 03 CM r— o CD 00 CO l"» CO CO CO LO

1—1 Q_ CQ r— r— r— o o o O o o O 0 O 0 0 O O 3

Cl. z 1 CM o CO r-^ CO r— r— CD CD CO 00 r— CD CO LO

CO r0 n— o LO >3- CO »— CO 10 00 CO CO CO

h“ 1 CQ CM CM f— 1— 1— 1— I— r— O o 0 O O O 0 O

3

-C O') CD CO CM CM CD 00 CO CO O 00 00 CD CM z o_ CO CO r^. r--. CO CO CO CO

CO -C

1— Q_ r— r— r— r— r— r— r— r“ r— r— r—

3

0)

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s- CM O CM CD CD o r— i r— 00 CO 0 r— CO

CD 1— i > O CM CO CO CO CO «5J" <3- LO LO CO LO LO 10 *5f LO o E o 3-

+-> c C O CM CM CM CM I''- CM CO LO co LO

cd O r— <sj- CO 00 CD CD r— I CO t"- 00 CM CO CO CD U -Q i i- s- CM un Lf) CO CO CO r-'. 00 CD O CO 00 LO CD

a) «o r— r— r—

o_ <_>

oCD -aa

< CM LO O 0 LO 10 LO LO LO

_i

E s_ O o o o O O o O O r— LO 0 0 O O O CD

4-> 3

CD O O 0 O O

Q. 0 a •r* •f r- •r— •f O O O O 0 a O O

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CD E E O O O O O E E E

i,

E E E

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f0 c c •r— •r— •r* •r— • 1— r— r— 1— r— 1— n” r—

-C O 0 1— 1— r— 1— 1— 0 0 0 0 0 O 0 0

Ql E E O O O O O CL Q. CL a. a. CL CL CL

s-<u

to C o O O O (_> o o o o o <C Q C_5 CQ

o

<_)

1— CM fOOCDCD-i- CO CO CO CO CO in (O co 01 in

116

polymi
MONOMERIC TBN

6 OLIGOMERIC TBN

*,K>

WiPh

n

B,W

Jc

r—r— r

"

"

i , | i i i i i i 0 S 10 13 20 25 30 3S 40 0 5 10 15 RETENTION TIME

(mlnutM)

Figure 19. Separation of polycyclic aromatic hydrocarbons (SRM 1647) on representative monomeric, oligomeric, and polymeric phases.

Separation of the sixteen-component mixture was performed using

gradient elution, 40-100 percent acetonitrile in water over 30

minutes at 2 mL/min. The three-component mixture was run isocratically at 85 percent acetonitrile in water, and the

order of elution is indicative of phase type.

117
60 A PORE DIAMETER

TBN

PhPh

BoP

100 A PORE DIAMETER

>' « " f r—

i f t i T” r—

» » 0 3 M11NMNU40U 0 3 K IS

RETENTION TIME

(minutes)

Figure 20. Selectivity comparison for polymeric phases prepared on narrow and wide pore silica substrates. Note especially

components 9 and 10 (benz[a]anthracene and chrysene).

118
2. Characterization and Comparison of Three Air Particulate Samples for

Polycyclic Aromatic Hydrocarbon Distributions (15320)

S. N. Chesler, L. R. Hilpert, W. E. May, R. E. Rebbert, C. R. Vogt,

S. A. Wise

In a previous report [1], the methodology and results for the determination of selected polycyclic aromatic hydrocarbons (PAH) in SRM 1649 (Urban

Dust/Organics) were reported. Since this air particulate material and a second air particulate SRM sample (SRM 1648, Urban Particulate Matter, which

is certified for inorganic species only) are available to other laboratories

to serve as benchmark materials for interlaboratory comparisons and methods

development, additional characterization of the PAH content of these two

materials was undertaken. A third air particulate sample, collected in

Philadelphia, PA, by the Environmental Protection Agency (EPA) for both

chemical and biological characterization, was also analyzed. Normally, only

10 to 15 major PAH components are measured in such samples. However, since

these three materials are available in large quantities and have been widely

distributed, these samples were characterized not only for the major PAH

constituents but also for the numerous minor PAH components.

After extraction of the samples with methylene chloride, the PAH con- stituents were isolated by clean-up on a short silica column, followed by

normal-phase liquid chromatography (LC) on an aminosilane column to isolate a total PAH fraction. The major PAH components were then determined in the

total PAH fraction from each sample using high resolution capillary gas

chromatography (GC) and reversed-phase LC with fluorescence detection. The

results of the GC and LC analyses of the PAH mixtures from the three air

particulate samples are summarized in Tables 19-21.

Quantification of the minor components in complex PAH mixtures is often

difficult because of the co-elution of many components even when using high

resolution capillary GC. To overcome this problem, the total PAH mixture from

each sample was further separated into eight fractions using normal -phase LC on an aminosilane column. Normal-phase LC provides separation of PAH based on the number of aromatic carbons, i.e., alkyl -substituted PAH elute with the

parent PAH. These fractions were then analyzed by reversed-phase LC, GC, and

gas chromatography/mass spectrometry (GC/MS) to identify and quantify the

individual PAH. To quantify the minor components in each fraction, one of the

major components in each fraction, which had been quantified previously in the

total PAH fraction, was used as an internal standard, e.g., phenanthrene in

fraction 2, fluoranthene in fraction 3, benz[a]anthracene in fraction 4,

benzo[a]pyrene in fraction 5, etc. Using this approach, over 100 components

in each air particulate sample were quantified. Of these compounds, approximately 40 unsubstituted PAH and 15 methyl -substituted PAH were identified

based on GC and LC retention data, fluorescence spectra, and mass spectrometric data. The remaining compounds were tentatively identified as alkyl

substituted PAH based on mass spectrometric and fluorimetric data. Several

compounds were positively identified for the first time in air particulate

samples, e.g., pentaphene and dibenzo[b,k]fluoranthene.

119
The last two PAH fractions from the normal -phase LC fractionation were of

particular interest. Fraction 7 contained six isomers of molecular weight

278. Using LC retention data in conjunction with fluorescence spectra, these

isomers were identified as dibenz[a,c]anthracene, dibenz[a,j]anthracene,

dibenz[a,h]anthracene, pentaphene, benzo[b]chrysene, and picene. Quantification of these six isomers without isolation into a separate fraction would

be extremely difficult, since they are only minor components which elute in

the same region as several major constituents. The last fraction contained

six isomers of molecular weight 302 (di benzopyrene or di benzofluoranthene

isomers). Two of these isomers were identified as naphtho[l ,2,3,4-defjchrysene

and dibenzo[b,k]fluoranthene.

Of particular interest in the comparison of the results from these three

samples is the possibility of source identification based on relative ratios

of selected PAH. For example, the ratio of benzo[e]pyrene to benzo[a]pyrene

is 1.1 for the Washington, DC, sample versus 1.7 for the St. Louis and

Philadelphia samples. Future research will investigate the potential use of

PAH ratios for source identification and apportionment, particularly using

ratios of minor PAH components which are not generally quantified.

Reference

[1] Center for Analytical Chemistry Annual Report, NBSIR 82-2620 (1982).

120
Table 19. Concentration (ug/g)

a of Selected PAH in Washington, DC, Sample

(SRM 1649) as Determined by GC and LC Methods.

Compound Measured GC [4]

b

LC-I

C

[18] LC- II C

[9]

Phenanthrene -- -- 4.5 ± 0.3

Anthracene -- — --

Pyrene 7.2 ± 0.2 6.3 ± 0.4 6.2 ± 0.2

Fluoranthene 7.3 ± 0.2 7.0 ± 0.5 6.8 ± 0.4

Benz[a]anthracene 2.4 ± 0.1 2.8 ± 0.3 2.4 ± 0.1

Chrysene f4 6 + 0 2 ^ 3.5 ± 0.1 3.7 ± 0.2q

Tri phenyl ene — 1.7 ± 0.1

e

Benzo[e]pyrene 3.3 ± 0.2 -- —

Benzo[a]pyrene 3.0 ± 0.3 2.6 ± 0.4 2.6 ± 0.1

Perylene 0.84 ± 0.09 0.80 ± 0.04 0.65 ± 0.02

Indeno[l ,2,3-cd]pyrene 3.3 ± 0.3 3.4 ± 0.4 3.6 ± 0.2

Benzo[ghi ]perylene 4.7 ± 0.2 3.9 ± 0.8 5.2 ± 0.6

Di benz[a , h]anthracene -- — 0.41 ± 0.07

Benzo[b]f1 uoranthene — — 6.2 ± 0.3 6.0 ± 0.3

Benzo[k]f1 uoranthene -- 2.0 ± 0.1 2.1 ± 0.1

a Values represent the mean ± standard deviation for the given number of

determinations.

dumber in brackets indicates number of samples extracted. Each extract

analyzed in duplicate.

c LC-I, no LC clean-up, 7-methyl fluoranthene used as internal standard; LC-II,

no LC clean-up, perylene-d12 used as internal standard; LC-III, LC clean-up,

perylene-d12 used as internal standard.

dc value includes both chrysene and tri phenyl ene. determined by LC analysis of four- ring PAH fraction isolated by normal -phase

LC.

121
Table 20. Concentration (yg/g)

a of Selected PAH in St. Louis, MO, Sample

(SRM 1648) as Determined by GC and LC Methods.

Compound Measured GC [4]

b

LC

C

[3] LC- I I

C

[4]

Phenanthrene 3.8 + 0.2C — 4.6 ± 0.3

Anthracene -- -- 0.36 ± 0.01

Pyrene 7.3 + 0.4 7.4 ± 0.2 6.8 ± 0.2

Fluoranthene 9.2 + 0.5 7.9 ± 0.6 8.7 ± 0.4

Benz[a]anthracene 3.2 + 0.2 2.8 ± 0.1 3.2 ± 0.1

Chrysene n 8 + 0 6^ 6.6 ± 0.1 6.6 ± 0.2

Triphenylene -- --

Benzo[e]pyrene 5.2 ± 0.3 -- —

Benzo[a]pyrene 3.1 ± 0.2 2.6 ± 0.2 3.4 ± 0.2

Perylene 0.76 ± 0.07 0.65 ± 0.02 0.69 ± 0.02

Indeno[l ,2,3-cd]pyrene 4.4 ± 0.15 4.8 ± 0.2 4.7 ± 0.2

Benzo[ghi]perylene 4.7 ± 0.1 5.5 ± 0.8 —

Benzo[b]f1 uoranthene 3.7 ± 0.5 - - Benzo[k]f1 uoranthene 3.5 ± 0.2 3.3 ± 0.1 3.4 ± 0.05

Benzo[j ]f1 uoranthene 9.8 ± 0.5 -- —

Benzofluoranthenes (Total) 16.9 ± 0.8 — —

a Values represent the mean ± standard deviation for the given number of

determinations.

^Number in brackets indicates number of samples extracted. Each extract

analyzed in duplicate.

cLC-I, no LC clean-up, 7-methyl fluoranthene used as internal standard; LC- II, no LC clean-up, perylene-d12 used as internal standard; LC-III, LC clean-up,

perylene-d12 used as internal standard.

dc value includes both chrysene and triphenylene.

determined by LC analysis of four-ring PAH fraction isolated by normal -phase

LC.

122
Table 21. Concentration (yg/g) of Selected PAH in Philadelphia, PA, Sample

(EPA) as Determined by GC and LC Methods.

Compound Measured GC [if LC-III [1]'

Phenanthrene 3.5 + 0.1 2.9

Anthracene - 0.4

Pyrene 7.3 + 0.1 6.6

Fluoranthene 13.6 + 0.2 11.8 ± 0.2

Benz[a]anthracene 11.4 + 0.2 11.7 ± 0.2

Chrysene (29 7 + 2 5^ 23.1 ± 0.1

Triphenylene 9.8 ± 0.1

(

Benzo[e]pyrene 16.4 + 0.7 —

Benzo[a]pyrene 9.5 + 0.1 7.5 ± 0.1

Perylene 2.2 + 0.2 2.1 ± 0.1

Indeno[l ,2,3-cd]pyrene 12.5 + 0.7 13.1 ± 1.0

Benzo[ghi ]perylene 12.6 + 0.7 —

Benzo[b]fluoranthene 9.9 + 1.0 —

Benzo[k]fluoranthene 11.1 + 1.4 11.0 ± 0.1

Benzofj ]f1 uoranthene 26.7 + 1.1 -- Benzofluoranthenes (Total) 48.5 + 2.0 —

a Values represent the mean ± standard deviation for triplicate measurements

of a single extract.

dumber in brackets indicates number of samples extracted and analyzed.

c LC-I, no LC clean-up, 7-methyl fluoranthene used as internal standard; LC- II, no LC clean-up, perylene-d12 used as internal standard; LC-III, LC clean-up,

perylene-d12 used as internal standard.

dc value includes both chrysene and triphenylene.

determined by LC analysis of four-ring PAH fraction isolated by normal -phase

LC.

123
3. Determination of Chlorinated Pesticide Residues in Human Liver Specimens

for the Pilot Environmental Specimen Bank Program (15320)

S. N. Chesler, W. F. Kline, S. A. Wise

As part of the NBS/EPA Pilot Environmental Specimen Bank program, analytical methodology for the determination of organochlorine pesticide residues in

human liver samples was implemented during the past year. Thirty individual

human liver samples, which were obtained in accordance with the NBS/EPA

National Environmental Specimen Bank protocol for sample collection [1], were cryogenically homogenized as described by Zeisler, et al

[2] and aliquots

were analyzed for organochlorine pesticide residues. Aliquots from these same 30 liver specimens were placed in storage under various conditions as part of

the storage evaluation study to determine the feasibility of long-term storage

of biological samples for trace analysis. The results from the analyses of

these 30 liver specimens will provide the baseline values for comparison to

results obtained in the future from analyses of stored aliquots.

The sample preparation consisted of mixing the liver homogenate with

sodium sulfate, chromatographic extraction of the sample/sodium sulfate

mixture with hexane: acetone (2:1), and chromatographic clean-up of the extract

on Florisil. Internal standards were added to the sample prior to extraction

to facilitate quantitation. The percent extractable fat was determined for

each sample by taking an aliquot of the extract to dryness in a small tared

flask. The mass of residue was assumed to be fatty lipid material. The

Florisil column chromatography separated the chlorinated pesticides from the

polar or lipid material. The eluant from the Florisil column was concentrated

to an appropriate volume and analyzed by capillary gas chromatography (GC)

with selective electron capture detection.

The data obtained from the analyses of the 30 individual samples are summarized in Table 22. Eight different chlorinated pesticides were observed

in nearly all of the samples. The range, mean, and median values based on both wet weight and fat weight are given. In a strict analytical sense, the

wet weight values are the most appropriate in that they reflect the concen- trations of the pesticides in the actual liver sample. The values, based on percent extractable fat, assume that all of the pesticides observed were originally associated with the extractable fat. This assumption, while

lacking absolute analytical validity, has become a convention among researchers

in this area since it facilitates the comparison of data obtained from the

analysis of different organs in addition to compensating for different extraction techniques [3]. The average percent standard deviation associated with

the gas chromatographic analysis of each sample is shown in the last column in

Table 22. Approximately 30 samples will be analyzed in the next year to

provide additional baseline data. Selected samples, which have been stored

for over one year, will be reanalyzed to evaluate the stability of the samples

under various conditions of storage.

124
Table

22.

Concentration

Ranges

of

Organochlorine

Pesticide

Residues

in

Human

Liver

Specimens.

rO *o e

<D 4-> SO

DIC fl-r

rO 0) -O -M

iU £ ro

a> s- to t > cu +> > < a. co £

CO

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VO

C\J VO LO CM r— VO CO f— i—

m

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m

ro cn

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rO ro > Ll_ £

ro +-> •r- 3 •o CD*-'.

a> •r- CD z: <u \3 CD£

4-> ^

<U 3

CD CO

r- CO i—

CO

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r—

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+-> u

ro

to CD CO o CM I-*- CD CD CO S- CO \ r— CM p— CO CM r— +-> CD • X

+-> OLl. o O

O o CMOO o CU

a)

CD*

•r- cn| cu • 3 cn| £

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<u

LO cr> cd 00 CO r—

CD CM

CM 00

cu

Oil c

to oa

4-om

cuin>>£

(O CM CO O r^. o vo

to LO VO CM VO o CD 00 o •r— o CO O o r— o’ CD CM o O ro CD | 1 i 1 i 1 1 1 cu 00 \ VO CM in r— 00 M cn CO VO o r— CO CM rO

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cu •o ro £ •r— +>

cuX s- in

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cu LJ 3 £

JO

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J- o £ £ o O Lul £ 1— h- O

r— 3 £ o •r— o o 3 U 1 o j- a o -o a 3 ro in 1 *o i 1 CU

ro

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X 3 CL ro Cl cu CL CL rO

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125
As part of a cooperative program with a similar Pilot Environmental

Specimen Bank Program in the Federal Republic of Germany, aliquots of liver

specimens from each pilot program were exchanged and analyzed for the determination of chlorinated pesticides. The results of this interlaboratory

comparison of analyses between NBS and the University of Ulm in Germany are summarized in Table 23. The agreement of the results is good considering that

somewhat different analytical methods were used by each laboratory. The results

obtained by the University of Ulm for dieldrin are low due to suspected losses

in the LC clean-up procedure. No explanation is available for the difference

in the results obtained for 3-HCH in the U.S. sample. The NBS results for

p,p'-DDT in the German liver sample may be high due to the presence of high

concentrations of polychlorinated biphenyls (PCB's) in this sample. The PCB's are isolated in a separate fraction in the German analytical procedure,

whereas they are in the same fraction as the chlorinated pesticide residues in

the NBS procedure and several isomers may co-elute with p,p'-DDT. Additional

liver samples and extracts have been exchanged between these two laboratories

in order to further investigate the interlaboratory comparability of these

analyses.

Table 23. Interlaboratory Comparison of Determinations of Organochlorine

Pesticide Residues in Human Liver Specimens (ng/g extractable fat).

U.S. Sample (L1S0347) German Sample (006)

NBS

a Ulm

b

NBS

a Ulm

b

Ulmc

Hexachlorobenzene 72 ± 15

d

73 ± 2 2580 ± 230 1711 ± 169 1923 ± 32

3-HCH 383 ± 37 12 ± 1 888 ± 73 892 ± 73 982 ± 18

p,p' -DDE 2340 ± 140 2138 ± 60 1840 ± 40 1794 ± 65 1858 ± 14

Dieldrin 1020 ± 190 585 ± 22 — —

p,p'-DDT 334 ± 80 330 ± 10 40 ± 2 20 ± 1 20 ± 1

aThree sample aliquots extracted from one jar; three GC analyses per sample

extract.

b

0ne sample (jar) extracted; three GC analyses per sample extract.

p

Three samples (jars) extracted; three GC analyses per sample extract.

^Based on one standard deviation of the mean for triplicate measurements.

References

[1] Zeisler, R. , Harrison, S. H., and Wise, S. A., eds.. The Pilot

National Environmental Specimen Bank: Analysis of Human Liver

Specimens , NBS Special Publication 656, Washington, DC (1983).

126
[2] Zeisler, R. , Langland, J. K. , and Harrison* S. H., Cryogenic Homogenization Procedures for Biological Tissues, Analytical Chemistry

(in press).

[3] Morgan, D. P. and Roan, C. C., Chlorinated Hydrocarbon Pesticide

Residues in Human Tissues, Archival Environmental Health 20, 452-457

(1970).

4. Certification of Selected Organic Compounds in SRM 1582, Petroleum Crude

Oil (15320)

J. M. Brown-Thomas, L. R. Hi 1 pert, W. F. Kline, W. A. MacCrehan, W. E. May,

R. M. Parris, R. E. Rebbert, C. R. Vogt

The objective of this program was to develop a Standard Reference Material

(SRM) with certified concentrations for selected organic compounds in a complex

matrix. This SRM will be useful in chemical characterization and methods

development research programs and quality assurance efforts of laboratories

involved in trace organic analysis in general, and the characterization of

fuels in particular. A petroleum crude oil (Wilmington crude) was selected as the matrix to be used in this effort. This material will serve as a companion

to SRM 1580, Organics in Shale Oil, that was certified in 1980 for many of the

same compounds. The use of both SRM's will provide analysts with two points

of calibration for the measurement of compounds that are certified in both

materials.

In general, the certification of SRM's is accomplished through utilization

of a single definitive method or at least two independent analytical methods.

In order for a parameter to be certified, the results of the analyses by the

independent methods must be in agreement. The limits of uncertainty given on the Certificate of Analysis reflect the agreement between the methods. The

concentrations of dibenzothiophene, phenol, o-cresol , and six polycyclic

aromatic hydrocarbons (PAH) were determined by two methods each. Carbazole,

benzo[e]pyrene (B[e]P), benzo[ghi]perylene (B[ghi]P), and indeno[l ,2,3-cd]-

pyrene (IP) were measured using only one analytical procedure. A summary of

the results obtained and the methods used for analysis are presented in

Table 24.

The sequential, high-performance liquid chromatographic (HPLC/HPLC)

procedure that was used for determination of six PAH has been reported previously [1,2,3] and was used in the certification of SRM's 1530 and 1649. The

high-performance liquid chromatographic/electrochemical detection (HPLC/EC)

procedure for determination of phenol and o-cresol was developed specifically

for this SRM and is similar to that reported by Shoup et al

[4].

The phenolic compounds were extracted from the oil into an aqueous phase

by basic conversion to the phenolate anions with base. They were subsequently

neutralized and then analyzed using a C-8 column with a mobile phase of

30 percent acetonitrile/5 percent tetrahydrofuran in water with a 0.05 mol/L

ammonium acetate electrolyte. The electrochemical detector consisted of a 1.2 mm glassy carbon electrode, and an applied potential (versus Ag/AgCl

127
Table

24.

Summary

of

Analytical

Results

(ug/g)

a

by

Various

Methods

Used

for

the

Analysis

of

Petroleum

Crude

Oil.

oo

pu

m

ioVOCM

-oCOin

«_> C5O

_J

o_

CMr—

+i o

CMO

VOO

O—I

Cl.

+1 VOCM+1 CM

CO

S3 S3 S3 S3 S3 LO S3 O

CM LO CM r^. VO o CTV r— o JO

C/> r**. O O O

O o r-" o o

+i +1 +1 +1 +i +1 +1 +i +1 +1

c_> o LO

vo VO CO CM VO <T> vo i-* 1— o CM r-. CM O , O *3’ , o o CO

CM vo CO CM

c_> • • • • • _J CO O o o |— o

Q-oc +1 +1 +i +1 +1 +1 o vo o VO co _i • • • • • Cl. co CM VO co CM r— d o CO

VOCM

+1

vooCO

COo

+1

CO

<uc

CU

Q)c

<1) im <u >> C QQJ I“1 i— *o o <U a; >> u 1)

(0 c c t- i 0) 0) fc. QJ 0) 0) CO a. c c x: £ a. •> o

0) <y P >) CM •r

J- JC c Ol a. •r «> JC 0) sz p (0 QJ r—

r—

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c tV3 <U cn 1 l O o o

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128

Values

represent

the

mean

±

standard

deviation.

Unless

otherwise

noted,

data

reported

represent

at

least

duplicate

analyses

of

five

or

more

ampoules.

Measurements

made

by

positive

chemical

ionization.

Measurements

made

by

negative

chemical

ionization.

*Data

reported

represent

the

analysis

of

only

one

sample.
3 mol/L KC1) of -1.00 V was used. Quantification was accomplished by use of

standard additions.

A sample of SRM 1580 was analyzed to assess the accuracy of the procedure. The certified concentrations of phenol and o-cresol are 407 ± 50 and

385 ± 50, respectively. The concentrations, as determined using this procedure, were 375 ± 15 and 391 ± 5, respectively.

Measurements for the PAH, dibenzothiophene, and carbazole were made by

gas chromatography/mass spectrometry (GC/MS) using both positive (Cl) and

negative chemical ionization (NCI). The NCI GC/MS procedure used for the

determination of B[a]P, B[ghi]P, and IP is described in detail in technical

report 21 of this section. For the positive Cl GC/MS procedure, measurements

were made on samples of the diluted oil without any sample pre-treatment or clean-up. Chromatographic separations were carried out on high resolution

fused silica capillary columns with a liquid phase of either SE-52 or DB-5.

The columns were connected directly to the ion source of the mass spectrometer

through a specially designed interface. The interface allows the methane

reagent gas to be brought in coaxially with the capillary column so that it

sweeps the effluent from the column into the ion source. Selected ion monitoring dejection was used to obtain additional selectivity; the quasi-molecular

ion (M+H) was monitored for each analyte. Quantitative measurements were

made using perylene-d12 as the internal standard. Relative response factors

for the analytes were determined from a solution of the analytes plus

perylene-d12 gravimetrically prepared to mimic the concentrations of the

analytes in the oil.

The sequential liquid chromatographic/gas chromatographic (HPLC/GC)

procedure used for determination of dibenzothiophene involved the isolation of

the analyte from the oil matrix by HPLC using a semi -preparative ami nosilane

column using a 1 percent methylene chloride in hexane mobile phase. The

fraction collected from the HPLC column was then analyzed by capillary GC with

flame photometric detection.

Detector calibration experiments were performed to determine the linearization exponent to be used for samples to be analyzed that day. The three

calibration mixtures were composed of dibenzothiophene in hexane with 2-methyl

dibenzothiophene (2-M-DBTP) present for volume correction. The concentration

of 2-M-DBTP was identical in each calibration mixture, while the relative

concentration of DBTP was 1.0, 2.0, and 3.0 units, respectively. A linearization exponent was obtained from the slope of the regression line calculated

from a plot of log concentration DBTP versus log DBTP/2-M-DBTP response. This

exponent was then used in the standard additions calculations to determine the

concentration of DBTP.

The gas chromatograms of the LC fractionated samples gave well -resolved

peaks for DBTP and for three other peaks which eluted after it. The first and

largest peak in the chromatogram has a retention time identical to 4-methyl

dibenzothiophene; the second, either 2- or 3-M-DBTP; and the third was not

identified but may be 1-M-DBTP. The first peak was used for volume correction

since it gave the highest measured precision. The other two peaks were used

similarly as a confirmatory check. For all samples analyzed, the concentration

129
of DBTP determined by use of any of the three possible volume correction peaks

agreed to within experimental error.

The extraction/GC procedure used for the determination of phenol and

o-cresol has been reported previously [1,5] and was used in the certification

of SRM 1580. However, at the low concentrations of phenols present in the

petroleum crude oil, we had problems distinguishing the analyte signals from

background signals. We were able to salvage useful data from only one of the

eight samples analyzed.

This material will be issued as SRM 1582 upon completion of statistical

analysis of the data generated by the various methods described in this

report. Certified values will be given for phenanthrene, fluoranthene,

pyrene, benz[a]anthracene, perylene, benzo[a]pyrene, and dibenzothiophene.

Information values will be provided for the other analytes measured.

References

[1] Hertz, H. H., Brown, J. M. , Chesler, S. N., Guenther, F. R. , Hilpert,

L. R. , May, W. E., Parris, R. M. , and Wise, S. A., Determination of

Individual Organic Compounds in Shale Oil, Anal. Chem. 52^ 1650-1657

(1980).

[2] May, W. E., Brown-Thomas, J. M. , Hilpert, L. R. , and Wise, S. A.,

Certification of Selected Polynuclear Aromatic Hydrocarbons in

SRM 1580, Organics in Shale Oil, Anal. Methods and Biol. Fate of

Polynuclear Aromatic Hydrocarbons, M. Cooke and A. J. Dennis, eds.,

Battelle Press, Columbus, Ohio, 1-16 (1981).

[3] Brown, J. M. , Wise, S. A., and May, W. E., Determination of Benzo[a]-

pyrene and Recycled Oils by a Sequential HPLC Method, J. Environ.

Sci. Health A15 (6), 613-623 (1980).

[4] Shoup, R. E. and Meyer, G. S., Determination of Environmental

Phenols by Liquid Chromatography/Electrochemistry, Anal. Chem. 54,

1164-1169 (1982).

[5] Guenther, F. R., Parris, R. M. , Chesler, S. N., and Hilpert, L. R.

,

Determination of Phenolic Compounds in Alternate Fuel Matrices, J.

Chromatog. 207, 256-261 (1981).
5. Determination of Relative Isomer Content in SRM 916, Bilirubin (15320)

J. M. Brown-Thomas, R. 6. Christensen, A. Cohen, W. E. May, R. Schaffer

SRM 916 is known to consist of three structural isomers of bilirubin,

differentiated as Ilia, IXa, and XI I la. Bilirubin IXa is the natural product.

The Ilia and Xllla forms arise from the IXa as a result of a fragmentation and

recombination reaction. It is believed that the reaction that gave rise to

the Ilia and XI I la forms in the bilirubin used for SRM 916 took place early in

the process of its isolation. McDonagh [1] discovered these isomers, isolated

each by thin-layer chromatography, and measured their molar absorptivities.

He estimated their proportions in SRM 916 to be 10:75:15, respectively. We

had confirmed the ratio by using his molar absorptivities and TLC. Now we undertook to measure the isomer proportions by liquid chromatographic analysis

and to confirm their molar absorptivities.

Conditions were: Silica column, methylene chloride solvent containing

0.7 percent (v/v) acetic acid, detection at 450 nm. The relative peak areas

found (mean of five measurements ± standard error of the mean) were 102.6 ± 0.9,

794.6 ± 2.6, and 104.0 ± 1.6 for the Ilia, IXa, and Xllla isomers, respectively. These are not representative of the relative amounts of the isomers,

however, because the individual molar absorptivities are known to be different.

The determination of molar absorptivities was accomplished by separating

quantities of the bilirubin isomers on a preparative scale liquid chromatographic column, using a chromatographic scheme similar to that described above

and in reference [2]. After the isomer-containing fractions were collected,

the solvent was removed by using a rotary evaporator; then each of the fractions

was subjected to another similar fractionation. This resulted in three Isomer

fractions that were obtained in smaller volumes of solvent, thus minimizing

possible contamination from solvent impurities and/or column bleed. Solutions

of each isomer fraction were made in methylene chloride containing 0.7 percent

acetic acid and the absorbances at the peak maxima and at 450 nm were noted.

Each solution was then subjected to an analytical liquid chromatography

separation to determine its proportional content of the three isomers.

The "contamination" isomers present in each solution ranged from less

than 0.5 percent to about 5 percent. By an iterative process, the extinction

coefficients were corrected to eliminate errors from that source. The mi 1 1 1

molar absorptivities at 450 nm were found to be: 62.35, 61.67, and 49.00 for

the Ilia, IXa, and Xllla isomers, respectively. The precision of these

measurements is estimated to be about one percent relative standard deviation.

The presence of any systematic bias, such as that from possible inclusion of

solvent in the bilirubin crystals, is unknown.

Using these molar absorptivities at 450 nm and the relative peak areas noted above, the relative amounts of the isomers in SRM 916 were calculated

to be: 0.099 ± 0.002, 0.774 ± 0.008, and 0.127 ± 0.002 for the Ilia, IXa, and

Xllla isomers, respectively. The uncertainties are dominated by the contributions from the absorptivity determinations. Now that the necessary techniques

have been perfected, we plan to make a more definitive measurement.

131
References

[1] A. F. McDonagh and F. Assisi, Commercial Bilirubin: A Trinity of

Isomers, FEBS Letters 18, 315-317 (1971).

[2] T. A. Woodbridge and D. A. Lightnor, Separation of the Ilia, IXa,

and XI I la Isomers of Bilirubin and Bilirubin Dimethyl ester by HighPerformance Liquid Chromatography, J. Liquid Chromatog. 657-658

(1978).

6. Determination of Organic Nutrients in SRM 1549, Non-Fat Milk Powder

(15320)

I. N. Black, L. D. Fong, S. A. Margolis

Liquid chromatographic (LC) methods have been developed for the analysis

of ascorbic acid, nicotinic acid (NA), and nicotinamide (NAM). The method for

ascorbic acid uses a semi -preparative amine column, and the analyte is eluted

isocratically with a solvent composed of 30 percent 0.005 mol/L monobasic

sodium phosphate in acetonitrile with 0.1 percent mercaptoethanol . Detection

is UV (254 nm). At a flow rate of 3.5 mL/min, the ascorbic acid elutes at

^1 3.5 minutes and is resolved from isoascorbic acid and dehydroascorbic acid

(figure 21). The limit of detection for ascorbic acid was below 1.0 yg.

Figure 21. Separation of ascorbic acid,

dehydroascorbic acid, and

isoascorbic acid by HPLC

using an amine column with

isocratic elution.

Several methods have been evaluated for the analysis of the NA and NAM.

Reversed-phase LC methods using ion-pairing and an octadecylsilane column

separated either one compound or the other, but no method was capable of

resolving both compounds with k's of 5 to 10. A method using an analytical

amine column and a solvent similar to that used for ascorbic acid analysis

retained NA with a k' of about 10, but did not retain NAM. A strong cation

132
I

II

exchange resin equilibrated with 0.01 mol/L formic acid: acetonitrile 95:5

( v : v) was used to retain both NA and NAM. The analytes were eluted from the

column with a 13-40 percent linear gradient (15 minutes), 0.1 mol/L ammonium

acetate pH 6.0, acetonitrile 75:25 (v:v). The NA and NAM were well separated

(figure 22) and the limits of detection were less than 0.1 yg for each analyte.

i 3

Figure 22. Separation of nicotinic acid

and nicotinamide by HPLC

using a cation exchange

column with gradient elution.

The method for extracting and stabilizing the ascorbic acid from non-fat

dry milk consists of dissolving 0. 1-1.0 g of sample in 2 ml of a 0.1 percent

aqueous solution of dithiothreotol , precipitating the proteins with 2 mL of

meta phosphoric acid (HP03 ), and then adding 1 mL of acetonitrile. The

suspension is centrifuged and an aliquot of the clear supernatant fluid is

133
analyzed by the method described above. We are using dithiothreotol to reduce

dehydroascorbic acid to ascorbic acid and to prevent oxidation of ascorbic

acid. The optimum conditions for the extraction of ascorbic acid are being

evaluated. Table 25 summarizes our effort to date. The optimum concentration

for the meta phosphoric acid lies above 8 percent, and the time intervals

between the various additions appear to be unimportant if completed within one

hour. The identity of the ascorbic acid peak from the chromatogram was con- firmed by collecting the peak in five consecutive fractions and demonstrating

that the material in each fraction exhibited a UV spectrum characteristic of

ascorbic acid. The ascorbic acid content in SRM 1549 (non-fat dry milk), when

analyzed by the AOAC method at the FDA, is 72 yg/g. Our preliminary results

are 55-60 yg/g.

Table 25. Effect of HP03 and Time on Ascorbic Acid Extraction from

Non-Fat Dry Milk.

Ascorbic Acid Content (yg/g Sample)

Percent

HP0„

One Hour Delay in

No Delay HPO^ Addition

One Hour Delay in

CH^CN Addition

0 3

2 42

4 57 55 56

6 52

8 65

12 54

16 57

The method for extracting NA and NAM from non-fat dry milk and rice flour

consists of hydrolyzing the nicotinic acid containing organic molecules to

yield NA. The hydrolysis is performed with a 10 percent suspension of calcium

hydroxide at elevated temperatures. Experiments with NAD and NADH indicate

that they will be completely hydrolyzed to NA and NAM in three hours at 75 °C.

Under these same conditions, NAM is partially hydrolyzed to NA in the absence

of food materials. In the presence of rice flour, NA is released from its

organic sources, but NAM does not appear to be hydrolyzed to NA. Furthermore,

only 30 percent of the added NA is recovered as NA after the hydrolysis

reaction. The remainder appears to be converted to a compound with a retention time that is similar to that for NAM. We are now searching for optimum

conditions for stabilizing and extracting NA and NAM from non-fat dry milk and

rice flour. The vitamin content of these materials is being determined by the

standard additions method of analysis. Preliminary results indicate that the

rice flour contains 30 yg/g NA. Determination of NA in SRM 1549 is in

progress.

134
7. Use of Polynuclear Aromatic Hydrocarbon Generator Columns for Calibrating

Air Sampling Systems (19105, 15320)

S. N. Chesler, F. R. Guenther, W. H. Zoller (University of Maryland)

A method for measuring vapor pressures of high molecular weight polycyclic

aromatic hydrocarbon (PAH) at temperatures between 60 and 300 °C has been

developed. This study is a continuation of work done in the Liquid Chromatography Group [3] and utilizes a method similar in principle. The work done

previously covered the 10-50 °C range and benz[a]anthracene (molecular weight

228) was the largest compound studied. In this method, an all -glass sampling

system, along with a gas chromatographic (GC) oven, allows an extensive

temperature range to be studied (60-300 °C). Vapor pressure data is important

in the prediction of transport mechanisms from industrial processes or waste

sites, the adsorption tendencies of PAH on airborne particulate matter, and in

the calculation of Henry's law constants to predict water/air distributions.

This study has also resulted in the construction of a constant vapor density

generator to use in the calibration of air sampling equipment.

The vapor generator columns were constructed with 6 mm O.D. glass packed

with 100 mesh glass beads. Three zones of the pure crystalline compound under

study are packed within the last 3 cm of glass beads. A fused silica capillary

column provides the physical linkage between the generator column and a cold

trap. The generator column is housed within a GC oven, and a thermocouple

(situated within the generator column at the entrance to the fused silica

line) is used to measure temperature.

To measure the vapor pressure at a particular temperature, the oven is

equilibrated at that temperature for a period of one-half hour. The vapor is

vented during this time. To begin trapping, the trap line is opened at a valve and the vent line closed. The vapor is then directed through the fused

silica line, through the trap and valve, and into a water filled inverted

volumetric flask. After collecting a known volume of saturated vapor, the

trap is washed out with methylene chloride. A suitable internal standard is

added and the resulting solution analyzed by GC. With the collected volume

known (volumetric flask) and the amount collected known (GC analysis), the

vapor density can be calculated. Then by calculating back to the generator

column conditions (temperature/pressure corrections), the saturated vapor

density can be found. Vapor densities can be converted to vapor pressures

through use of the ideal gas law. The vapor pressure values are in reasonable

agreement with some literature values obtained for the same temperature range

(Table 26). However, a bias exists between these values and the data obtained

previously [3] When extrapolated to the same temperature region. Reasons for

these differences are being investigated.

Vapor density measurements for anthracene, fluoranthene, pyrene,

1 -methyl pyrene, chrysene, benzo[a]anthracene, benzo[e]pyrene, and perylene

have been made. Table 26 shows some vapor pressure data from this work and,

for comparison, some literature values. Measurements of benzo[a]pyrene,

benzo[ghi]perylene, indeno[ghi]pyrene, and some nitro-PAH are planned.

135
Table 26. Vapor Pressure in Pascals at 100 °C.

Present Work Literature

Anthracene 2.92 3.144 [1], 0.0632 [2], 1.37 [3]

Pyrene 1.81 1.793 [1], 1.150 [2], 0.976 [3]

1 -Methyl pyrene 1.20

Benz[a]anthracene 0.137 0.114 [2], 0.0201 [3]

Chrysene 0.0154 0.0160 [2]

Benzo[e]pyrene 0.00994 --

A semi -portable 1 -methyl pyrene generator column has also been developed.

This column is packed in a similar method, as stated above. 1 -Methyl pyrene

was chosen because it is not generally found (relative to other PAH) in

environmental samples and can therefore be used as an internal standard for

the analysis of PAH in air. The generator column is made of 6 mm O.D. pyrex

glass wrapped with 28 gauge Nichrome wire. A tapered glass tip leads from the

column to a fine tip from which the vapor is emitted. The tip is heated from

a separate circuit of wrapped Nichrome wire. The entire generator column is

insulated with ceramic fiber cloth. A proportional temperature controller

monitors and heats the main body of the column. A Variac is used to heat the

tip to a temperature well above the column temperature.

In use, the column is equilibrated at the desired temperature for one

hour. Then, several calibration runs are made by collecting the vapor for

30 minutes with an inverted miniature glass funnel in which 100 yL/min of air

is drawn. The collected condensate is then washed out with methylene chloride

and an internal standard added. The resulting solution is then measured by

GC. After calibration, the generator column can be used to spike 1 -methyl - pyrene into air sampling traps. In this way, 1 -methyl pyrene is introduced

into the system as a vapor and is allowed to interact with adsorbents in a similar way as components in sampled air. This method for introduction of

internal standards should allow more accurate accounting for losses that occur during sample work-up.

References

[1] Bradley, R. S. and Cleasby, T. G. , J. Chem. Soc. 1690-1692 (1953).

[2] Hoyer, H. and Peperle, W. , Z. Elektrochem. 62_, 61-66 (1958).

[3] Sonnefeld, W. J., Zoller, W. H., and May, W. E., Anal. Chem. 55^,

275-280 (1983).

136
8 . Detection of Arson-Analysis of Accelerant Residues on Soot (16630)

S. N. Chesler, F. R. Guenther

The purpose of this project was to determine if residues or products from

accelerant combustion could be detected on soot. The ultimate goal was to be

able to determine, from collected soot, if accelerants had been involved in a fire when other physical evidence has been destroyed. Our immediate goal was

to determine if any unconsumed vapors would be adsorbed onto soot as it leaves

flaming accelerants. This hypothesis proved to be incorrect, as we could find

no trace of an accelerant pattern on soot generated in the laboratory. Our

attention thus turned to investigation of higher molecular weight species that

may be produced in the sooting process.

To produce soot in the laboratory, we burned a number of accelerants in

pyrex beakers and collected the soot on watch glasses positioned over the top

of the beakers. The soot was then scraped and collected. Approximately

200 mg was then extracted with hexane using sonic vibration. The resulting

solution was centrifuged and the supernate transferred to a clean GC sample

vial. These samples were then concentrated under a flow of purified N 2 to

approximately 200 yL and a 1 yL aliquot injected onto a 30 m x 0.25 mm I.D.

capillary column coated with an immobilized SE-52 phase to 0.25 ym film

thickness. Accelerants studied included unleaded and leaded gasoline, kerosene, paint thinner, charcoal lighter fluid, methanol, toluene, and hexane.

Gas chromatographic (GC) analysis showed a clearly recognizable pattern

among all accelerant soots, except from methanol, of polycyclic aromatic

hydrocarbons (PAH). Although small amounts of PAH are produced in any com- bustion process, the magnitude of the concentration of PAH on the soot samples

was much greater than expected from wood or material burns. Subsequent

testing of soot collected from burning wood, rug, and small amounts of plastics

showed no pattern of PAH at this concentration level. It seems very probable

that soot PAH profiles might serve as useful indicators of arson.

This method will be subjected to stringent field testing. We are in the

process of obtaining samples from actual fires when arson is known to have

occurred, and the presence of accelerants are suspected, as well as samples

from accidental fires. So far, we have examined samples from a single fire

and have observed a PAH profile from soot collected at the fire scene. While

arson is not suspected in this nonresidential fire, certain aerosol cans and

other materials of unknown composition were consumed. These results may point

to a possible interference in the method. We will conduct further investigations in an attempt to eliminate this source of interference and therefore

false diagnosis. One possible explanation for this data is that large amounts

of plastics produce soot mimicking accelerant soot in a flaming fire of high

temperatures.

137
9. Analysis of EPA Performance-Evaluation Standard Samples (15320)

S. N. Chesler, F. R. Guenther, R. E. Rebbert

This work was undertaken as part of the Center for Analytical Chemistry

effort to assist the Quality Assurance Branch of EPA in Cincinnati with their

performance evaluation and quality control studies and to establish traceability to NBS. Our participation in this program was begun in late FY 1982

and will continue into FY 1984. In particular, the following types of samples

were analyzed: quality control samples (QCS) for water quality analyses for

volatile organics--series 17; QCS for drinking water analyses for (1) chlorinated hydrocarbon pesticides--series 4 and (2) trihalomethanes--series 3; and

QCS for priority pollutants/hazardous wastes/toxic chemicals for chlorinated

hydrocarbon pesticides--series 18. In addition, at EPA's request, we also

analyzed QCS for purgeables (sample with 30 volatile compounds in methanol).

In the volatile organic series, four solutions with different concentrations of nine volatile halocarbons in methanol were analyzed by gas chromatography with a flame ionization detector (FID). These compounds were:

chloroform, 1 ,1 ,1-trichloroethane, 1 ,2-dichloroethane, carbon tetrachloride,

trichloroethylene, bromodichloromethane, dibromochloromethane, tetrachloroethylene, and bromoform. The concentrations of the various compounds varied

from 25 to 600 yg/g. Triplicate measurements were made on six ampoules for

each solution. In this case, the less sensitive FID was used instead of the

more sensitive electron capture detector (ECD), which is usually employed.

However, the ECD is 500-1000 times less responsive to 1 ,2-dichloroethane than

trichloroethane, which eluted from the column only 0.3 minutes before it.

Thus, the dichloroethane is lost in the tail of the trichloroethane when an ECD is used; both of these compounds are easily detected when a FID is used.

For the chlorinated hydrocarbon pesticides--series 4, an ECD was utilized

to measure the concentration of lindane, endrin, and methoxychlor in six

ampoules selected from the lot. At least five injections were made from each

ampoule to determine the average concentrations, which varied from less than 1 to almost 100 yg/g. In this study, our results showed an ampoule-to-ampoule

variation in the lindane concentration and the appearance of an unknown

compound whose concentration changed inversely with the concentration of

lindane. This suggests that in some ampoules the lindane had decomposed and

produced the unknown compound.

The four solutions of the trihalomethane series were also analyzed with

an ECD. Again, at least five measurements were made for each of the six

ampoules from each solution. The average concentrations of the compounds

(chloroform, bromodichloromethane, dibromochloromethane, and bromoform)

determined in methanol varied from 40 to 660 yg/g.

The chlorinated hydrocarbon pesticide--series 18 was analyzed with an

ECD. Six injections from six ampoules from each of four solutions were used

to determine concentrations of the six compounds (heptachlor, aldrin, p,p'-DDE,

dieldrin, p,p'-DDD, and p,p'-DDT). The average concentrations varied from 0.1

to 1.1 yg/g.

138
Although the purgeable samples contained 30 compounds, EPA requested that

we analyze for chloromethane, chloroethane, and bromomethane only. These

components were analyzed by an internal standard (vinyl chloride) method with

a 30 m x 0.25 mm I.D. capillary column coated with 1 ym film of an immobilized

SE-52 phase. A post-column trap packed with activated alumina was installed

between the column exit and the FID. This trap selectively removes the

methanol solvent, but allows the analytes of interest to pass through to the

detector unhindered and be measured without interference from the solvent.

Our analytical results and those of EPA agreed closely for all analytes

except for bromomethane. Differences in results for this analyte are being

resolved.

| Tables of these results are not given since these samples will be used by

EPA in future performance evaluation studies and confidentiality is required.

This cooperative effort with EPA/Cincinnati will continue into FY 1984. In

particular, a formal means for showing traceability to NBS will be developed

for these and future quality control samples.

10. Preparation and Certification of SRM Calibration Solutions (15320)

J. M. Brown-Thomas, S. N. Chesler, F. R. Guenther, D. K. Hancock,

W. F. Kline, W. E. May, R. M. Parris, R. E. Rebbert, D. J. Reeder

The Standard Reference Materials (SRM's) that have been certified for

trace organic analysis fall into two general categories--those to be used for

calibration of analytical instrumentation and those to be used for quality

assurance of analytical procedures. Our major thrusts during the past few

years have been directed toward the development of SRM's for trace organic

analytes in complex natural matrices, i.e., SRM 1580 (Organics in Shale Oil)

and SRM 1649 (Urban Dust/Organics) for the latter purpose.

During FY 1983, in addition to certifying another complex matrix SRM

(1582, Organics in Petroleum Crude), we have produced and certified a number

of calibration SRM's (solutions or mixture). Each of these SRM's, with the

exception of SRM 1514 (Differential Thermal Analysis Purity Set), contain a number of selected analytes dissolved in a pure solvent. SRM 1514 is composed

of three sets of p-aminobenzoic acid--phenacetin mixtures. These SRM's can be

used for calibrating analytical instrumentation. Many calibration SRM's are also useful as standard addition analytes in the analysis of complex mixtures.

Halocarbons in Methanol for Drinking Water Analysis, SRM 1539, has been

completed and is now available. This SRM contains seven halocarbons ranging

from chloroform to bromoform and, when diluted 1 : 1

5 in halocarbon-free water,

produces a water-containing halocarbon at commonly encountered concentration

levels (0.5-50 mg/L).

Chlorinated Pesticides in Isooctane, SRM 1583, has been certified and

will be available shortly. This SRM contains six common pesticides--<s- and

y-BHC, aldrin, heptachlor epoxide, p,p'-DDE, and p,p'-DDT—at certified levels

near 1 yg/g. This SRM will serve the residue chemist and provide for the first

time an NBS traceable standard for environmental measurements of pesticides in

water, food, tissues, and airborne particulates. A related material, SRM 1585,

139
Polychlorinated Biphenyls (PCB) Congeners in Isooctane, contains eight individual PCB congeners. Each of these congeners, listed in the table below, were

chosen for their specific chemical toxicological or environmental effects.

PCB

Number Congener

3 4-Monochl orobi phenyl

15 4,4' -Diehl orobi phenyl

28 2,4,,4 '-Tri chi orobi phenyl

52 2,2' ,5,5' ,-Tetrachlorobiphenyl

77 3,3' ,4,4' -Tetrachl orobi phenyl

101 2,2' ,4,5,5' -Pentachl orobi phenyl

138 2,2' ,3,4,4' ,5 ' -Hexachlorobi phenyl

153 2,2' ,4,4' ,5,5'-Hexachlorobiphenyl

Rationale

A prevalent, incidentally generated PCB

A prevalent, incidentally generated PCB

A predominant peak of Aroclors 1016, 1242

A predominant peak of Aroclors 1016, 1242

A very toxic, less metabolized PCB

A predominant peak of Aroclors 1254, 1260

A predominant peak of Aroclors 1254, 1260

A predominant peak of Aroclors 1254, 1260

The congeners are certified at the yg/g level and also can be used as qualitative

markers for determination of the presence of incidentally generated PCB and the

various commercially produced PCB mixtures (Aroclors).

SRM 1586, Isotopically Labeled and Unlabeled Priority Pollutants in

Methanol, has been prepared specifically to be of use to those environmental

analysts who use the U.S. Environmental Protection Agency (EPA) Standard

Methods 1624, 1625, 624, 625, 524 or 525. SRM 1586 consists of two separate

solutions of ten priority pollutants. The compounds in one solution carry

either a deuterium or carbon-13 label, while the second solution contains the same compounds with no isotopic labels. The compounds, EPA compound class,

type of label, and nominal concentrations are listed in the table below.

Compound Type

Selected Compound

(Isotopic Label)

Nominal Concentration

yq/mL

Acid Extractable Phenol (dg)

2,4-Dichlorophenol

100

(3,5,6-d

3

) 100

2-Nitrophenol (3,4,5,6-d^) 100

Base/Neutrals Bis-2-Ethyl hexyl Phthalate

(3,4,5,6-d^) 60

Nitrobenzene (dg) 100

Naphthalene (dg) 100

Benzo[a]pyrene (d

12 ) 40

Purgeables/

1

Carbon Tetrachloride ( C) 100

Volatiles Chlorobenzene (dg) 100

Benzene (dg) 100

140
These SRM solutions will be used either together or separately to calibrate

and/or test the user laboratory's employment of the various EPA standard

methods. The SRM was certified by the use of gravimetry, gas chromatography

(GC), and liquid chromatography (LC); isotopic purity was verified by mass spectrometry.

SRM 1584 is a methanol solution of the eleven phenols included in the

EPA's list of priority pollutants. The concentrations range from 15 to

65 yg/mL. This SRM will be useful for calibrating gas and liquid chromatographic instrumentation, for phenol analysis, and can also be used for

fortifying water samples. This SRM was certified by use of gravimetry, GC,

and LC.

SRM 1514 is composed of a set of four vials containing "pure" phenacetin

and phenacetin doped with nominately 0.7, 2, and 5 mole percent p-aminobenzoic

acid. These materials are intended for use in evaluating the method of

determining purity by differential scanning calorimetry. The actual amounts

of p-aminobenzoic acid present were determined by liquid chromatography and

confirmed by spectrofluorimetry.

The preparation and certification of (1) Nitrated-Polycycl ic Aromatic

Hydrocarbonss (N-PAH) and (2) Dioxin Calibration Solution SRM's are planned

for early FY 1984. The N-PAH SRM project represents a joint effort between

NBS and the Coordinating Research Council, Inc. (CRC), Atlanta, GA. The CRC

is funding a commercial laboratory to synthesize 20 pure (>99 percent) N-PAH.

We will dissolve them in an appropriate solvent and certify their concentrations. This SRM will be intended for use in calibrating instrumentation

to be used in the analysis of N-PAH in complex mixtures.

We are currently investigating the stability of N-PAH solutions using

2-nitronaphthalene, 2-nitrofluorene, 9-nitroanthracene, 1-nitropyrene, and

6-nitrobenzo[a]pyrene as representative compounds from the class. Methylene

chloride, methanol, and nitromethanol solutions have been prepared. The

solutions are being stored at room temperature or at -10 °C in either clear or amber ampoules. We have found nitromethane and methanol solutions of these

N-PAH stored at -10 °C to be stable for at least six months.

The Dioxin Calibration Solution SRM is being prepared using NBS funding

and will have certified concentrations (^100 ng/mL) of 13 C labeled and

unlabeled 2,3,7,8-tetrachlorodibenzo-p-dioxin (the most hazardous of the

family of 75 different chlorinated dioxins) in separate isooctane solutions.

141
11. Reference Methods for Certification of Seven Enzymes in SRM 909 (15606)

R. Schaffer

The catalytic (activity) concentrations of the seven enzymes acid phosphatase (ACP), alkaline phosphatase (ALP), aspartate aminotransferase (AspAT),

alanineaminotransferase (AlaAT), creatine kinase (CK), lactate dehydrogenase

(LDH), and y-glutamyl transferase (y-GT) were determined in NBS Human Serum

Standard Reference Material (SRM 909). Separate teams of clinical chemistry

experts selected specific analytical methods for each of the enzymes and then

performed them. The results obtained by each team in the third (and last)

round of team testing provided the activity concentrations assigned to the

SRM. All of the methods are spectrophotometric and are primarily those

recommended as candidate reference methods by the Standards Committee of the

American Association for Clinical Chemistry and/or the Experts Panel on Enzymes of the International Federation of Clinical Chemistry. However, the

reaction temperature for all of these analyses was 29.77 °C, the melting point

of gallium for which NBS issues SRM 1968. Interlaboratory standard deviations

of less than 10 percent were achieved (see Table 27 and figure 23). Measurements made one year after the conclusion of the multi laboratory studies showed

unchanged enzyme activities, i.e., activities within the uncertainties of the

assigned values. This work is described in detail in NBS Special Publication

260-83 on "The Measurement of the Catalytic (Activity) Concentration of Seven

Enzymes in NBS Human Serum SRM 909," published in June 1983.

Figure 23. Summary of all results in terms of percent deviations from

enzyme team means. Each laboratory is represented by its mean value (closed circle, •).

142
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nj +-> E PT3 (O CO E (U *r- <D to > + /^U W 0) N LD ^ C dlQ co LO px. '—ID E _l ro LO CM

cl 

a co o CM CM I— X E • • ‘ • • lOUJ ID ST o o CM —

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t—

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or - . >

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cc

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V r- _Q —

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CM r— CO

n$ 2 CO CO p— E •o 4-> O CM r— E E <D • • • 3 ns co o o r—

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px. r— LO CO

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CO cn 00 Px. o CO

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with

orr. )

without

orr. )

CM 1 U to 1 O to in to to -Q -O jn -Q -Q

1— ns 1— -ic ns l— ns (0 ns < C p- < c •— <C r- r— 1—

ns ns ns <a CL rc CJ3 r— i— LO i— r— LO to LO Q 1 <C X>x»^ «Cx—

_J

— > ns

143

Enriched

material,

not

SRM

909.
12. Metal-Ion Affinity Chromatography Supports for Protein Separation (26111)

L. A. Alexander, A. E. Davidson, A. J. Fatiadi, C. L. Hsu, S. A. Margolis,

D. J. Reeder

Descriptions of the development and use of immobilized metal ions on chromatography supports for separating proteins and other biomaterials are beginning to appear in the scientific literature. Exploiting the interactions

between solutes and immobilized metal ions appears to be a viable direction

for exploring new ways to achieve protein separations. We began synthesis of

several chromatographic supports to which the following metal ions were

covalently attached: Mn

2+

, Fe

2+

, Fe

3+

, Co

2+

, Ni

2+

, Cu

2+

, Zn

2+

, and Cd2+

. The primary support material was polystyrene-di vinyl benzene copolymer beads

with covalent attachment of the metal ions by an imi nodi acetate ligand.

These column materials were tested in a low-pressure liquid chromatographic system using flow rates of approximately 1 mL/min. Human serum was placed on the column and sequentially eluted with increasing ionic strength

buffers. Peak fractions were obtained, concentrated, and analyzed by sodium

dodecyl sulfate (SDS) polyacrylamide gel electrophoresis, thin-layer isoelectric

focusing, and two-dimensional electrophoresis.

Of the materials tested, the column support coupled with Cu

2+

appears to

be the most interesting. Three major protein peaks are consistently eluted,

using a three-step sodium acetate, pH 5.5 gradient with increasing ionic

strength. The first peak contained albumin and many other proteins. The

protein distribution in the second and third peaks is now being investigated.

There is a large proportion of protein in the second peak that has a basic

charge and migrates to an apparent isoelectric point (pi) of about 9. This

peak appears to be devoid of albumin. The third peak has a more neutral

distribution of proteins, with the majority of protein having a pi of about 7.

Albumin is absent in this peak as well.

We are systematically exploring the interactions of proteins with a wide

variety of supports to further understand the mechanisms of interactions of

the metal -binding ligands with individual protein molecules. By studying

these specific interactions, we expect to gain a greater knowledge of protein

structure and the mechanisms of separation. Use of these and similar supports

may play an important analytical, as well as industrial, role in biomolecule

separations.

144
13. Thin-Layer Isoelectric Focusing for Sensitive Protein Analysis (26111)

C. L. Hsu, D. J. Reeder, K. L. Richie

Separation of protein mixtures into component parts is a goal of many

techniques in biotechnology. Separation by isoelectric focusing is accomplished

in a pH gradient stabilized by carrier ampholytes between two electrodes. In

this technique, proteins migrate until they align themselves at their isoelectric point (pi) at which point a protein possesses no net overall charge and

will therefore concentrate as migration ceases. Resolution in isoelectric

focusing is a function of the square root of the voltage gradient applied.

Typically, either long (>10 cm) polyacrylamide gels in glass tubes or flat,

thick (1-2 mm) gels are used in these separations. High voltages that would

increase resolution in the traditional -type gels result in distortion of the

protein bands due to the heating caused by direct current flowing through a high resistance. We have developed capabilities for preparing thin acrylamide

gels containing ampholytes on glass or thin plastic plates. This technique

makes use of high field gradients (>400 volts/cm) to produce rapid focusing in

thin (125 ym) gels. The improved cooling characteristics of thin-layer gels

also allow ampholyte concentrations to be increased to improve pH gradient

production. To dissipate the heat (>20 w) formed, an efficient thermoelectric

device cools the plates to constant temperature even with 20 watts input.

Silver staining of the focused proteins gives results within one hour after

the electrophoretic run of 40 minutes. Up to 60 bands of focused proteins

have been observed in serum samples. The extraordinary sensitivity of this

method is evidenced by the small amount of protein required. Typically, 1 yL

of a 1:20 dilution of serum is used for separations. Thus, individual protein

components in the 10-50 ng range may be detected. The faintest bands are estimated to contain about 1-5 ng of protein.

Thin-layer isoelectric focusing (TL-IEF) thus shows promise as a rapid

method for separating and screening proteins. We have used the technique to

differentiate serum proteins obtained from fish, to assess the purity of human

insulin produced by bio-engineered bacteria, to evaluate enzyme purity, and to assess different types of bacterial vaccines.

14. Nitrogen-15 NMR Spectrum Editing by the DEPT Technique (15320)

B. Coxon

NMR spectrum editing by the DEPT (Distortionless Enhancement by Polarization Transfer) method [1] was originally developed for the purpose of confirmation of spectral assignments in 13 C NMR spectra. The end result of this

technique is a set of separated CH, CH2 , and CH 3 subspectra with signal :noise

ratios enhanced by transfer of magnetization from the protons to the 13 C nuclei.

Since each subspectrum contains either CH, CH2 , or CH 3 signals, this allows the

ready identification of these structural types. Sensitivity enhancement by

magnetization transfer is achieved in this instance by methods in which several

pulses are applied (in some cases simultaneously) to the protons and 13 C nuclei.

The implementation of such pulse sequences has been made possible by the

145
installation (during 1982) of an advanced pulse programmer in our WM-400 NMR

spectrometer. This accessory also permits control of the RF phases (±x,±y) of

the observation and decoupling channels.

We have recently extended spectrum editing by the DEPT technique to the

structural analysis of aminoqlycoside antibiotics by 15 N NMR. The major

chemical difference between * 3 C and 15 N sites is that most CH protons do not

exchange or exchange only very slowly, whereas most NH protons undergo rapid

chemical exchange. This is particularly true for the aminoglycoside antibiotics, for which we have observed that NH proton exchange is enhanced by the

polyhydroxyl ic nature of the compounds. For this reason, these antibiotics

were examined as their solutions in 9:1 v/v CF3 C02H:CD3 C02H, a solvent mixture

that protonates all nitrogen atoms except those of amide groups, and thereby

suppresses the rapid NH proton exchange which occurs at higher pH. For the

purpose of a deuterium lock signal, the less expensive CD3 C02 D solvent was not

used, in order to avoid the complication of partially deuterated amino groups.

The pulse sequence for proton decoupled, 15 N DEPT NMR is indicated in

figure 24, in which e represents a proton pulse (at 400 MHz) of variable width,

and 1/2J is a fixed delay time defined by an average value of the one-bond

coupling constants t*ie antibiotics. For the purpose of 15 N spectrum

editing (for example, the proton decoupled 15 N NMR spectrum of isofortimicin)

,

a set of three raw spectra (e ls e 2 , and e 3 ) was acquired by use of the proton

pulses e = tt/4 , ir/2, and 3tt/4» respectively (see figure 25 (d), for e = tt/4,

for example). Linear combinations of these raw spectra, according to the

equations,

I

NH = 02-O.4Oex-O.2895

NH2 = 0.5801+0. 29e 2 -0. 98e 3 NH3 =

0

x -0 . 68©2+0 . 69© 3

then gave a set of proton decoupled NH, NH2 , and NH 3 subspectra (see figures

25 (a), 25 (b), and 25 (c), respectively).

The 15 N assignments indicated by these subspectra neatly confirm those

which we had made earlier by analysis of the multiplicities of the proton

coupled, 1

N spin multiplets of isofortimicin (see figure 25 (e)) combined with

15N chemical shift correlations with structural analogs. The nonideal values

of the coefficients in the linear combinations indicate pulse imperfections,

due possibly to nonoptimum design of the decoupler coils in our 15 mm 15 N probe or to the use of overly long proton pulse widths U/2 = 75 ys) because

of insufficient pulse power at 400 MHz. Future work will be directed toward

improvement of the experimental conditions.

References

[1] Doddrell, D. M. , Pegg, D. T., and Bendall, M. R. , J. Magn. Reson.

48, 323-327 (1982); Bruker literature, with Hull, W. E., (1982).
\c

IIT“ <D

CM \

C CO

II II CM CO

CD CD

X

CM\ [ c

CO

>

J20Q

147

Figure

24.

Pulse

sequence

for

15N

DEPT

NMR

with

proton

decoupling.

The

pulse

angles

e

3

used

for

spectrum

editing

are

indicated.
148
15. Two-Dimensional, DEPT Heteronuclear J-Resolved Carbon-13 NMR Spectroscopy

(15320)

B. Coxon

The DEPT technique discussed in the previous section has been combined

with two-dimensional, heteronuclear J-resolved NMR by the spin-flip method

[1] to give a new pulse sequence for two-dimensional, DEPT Heteronuclear (2D

DEPTH), J-resolved NMR. The 2D DEPTH sequence (shown in figure 26) has been

implemented for 13 C NMR at 100.6 MHz, using 5 mm samples. The first four

pulses of the sequence are used to transfer magnetization from the protons to

the 13 C nuclei, and, as in the spin-flip method, the last ! H tt pulse is used

to invert the proton spin states so that J-modulation of the 13 C magnetization

continues during the entire tx period and is not refocused at the time of

acquisition. In this sequence, the fixed delay D2 is defined by the reciprocal of an average value of the one-bond coupling constant x j£H

. The 2D

DEPTH data matrix is generated by incrementing the total variable delays

(

x /2) from a minimum value of V2J^

H plus the width of the e pulse. The

latter pulse may be assigned the various values tt/6, tt/4, tt/2, 3tt/4, or 5tt/6,

depending upon the purpose of the experiment.

The 2D DEPTH sequence has been used to analyze the anomeric and ring form

equilibria of D-digitoxose in DMSO-dg solution, the 1 J^

H

values being useful

for categorizing the various forms. A contour plot and associated projection

of a 2D DEPTH J-resolved 13 C NMR spectrum of a mixture of four anomers of

digitoxose is shown in figure 27. Like the INEPT (^sensitive Nuclei Enhancement by Polarization Transfer) version of 2D heteronuclear J-resolved NMR, the

2D DEPTH sequence offers sensitivity enhancement by means of polarization

transfer and proton Tx s that are perhaps shorter than 13 C Tx s, but has the

added advantage of "correct" multiplicities in the 2D J-spectra. For example,

figure 28 shows a comparison of the J-spectra obtained by 2D DEPTH, 2D spinflip, and 2D INEPT methods. The 2D DEPTH and 2D spin-flip methods yield the

correct multiplicity (triplet) for the methylene carbon signal, whereas the

2D INEPT method yields an incorrect multiplicity (doublet). Some spectral

artifacts have been noted in the 2D DEPTH method and studies of methods for

removal of these artifacts are planned.

References

[1] Bodenhausen, G. , Freeman, R. , Niedermeyer, R. , and Turner, D. L.,

J. Magn. Reson. 2£, 291-294 (1976).

149
<0\c

in

>

JB

0) D

Is

_p CO

W (5

rs \c

00

CM\c

c

CO

II CMD

II O " O CD

150

Figure

26.

Pulse

sequence

for

two-dimenstional

DEPT

Heteronuclear,

J-resolved

13C

NMR

spectroscopy.
DEPTH

J-RESOLVED

,aC

NMR

OF

DIGITOXOSE

ANOMERS

I

151

of

four

anomers

of

digitoxose

in

DMSO-dg

solution.
DEPTH (6=

45° ) O

CM

O•CO

QQ E

LU CM

O

O f- 0) -h> O -E 3

CM +-> r—O

(U 4- CO x: o

+-> cq

CO -0 | >, C I .oo o •r- 00 DVS DUO L. 0) •r- CO C

cr co o co

co

Q)

coOc

co

s->>

QJCOoXo

+->

•I

CD

O-I o a) x co o

+-> 0) •r- SCT> cO

Oe

CO o cO I S- CKI+J I U

ca OJ i- O. 3 4- co O O I <*- "D

CO <4-

s- aj o

-t-> -C Oh <1) a> s- CL 3

co • +» I CO X

'“D "O t- O E

a: .c Z -p « Z E<+- o o

co h~

r-l Q_ cO LU S- Q Z -P

CM >—> O

ai 0)0 0- -E CM co +J -o a: 4- c S O IOZ C *'"0 0 0- 0) CO T- > IhO CO CO Q- C 0) E *r- S- o a. i o co o

00

CM0) $_

C7>

152 I
16. Preparation and Analysis of a Quality Assurance Sludge Material (15320)

D. Enagonio, L. R. Hilpert, R. C. Paule (500), C. R. Vogt

The Resource Conservation and Recovery Act of 1976 (RCRA) established a Federal program to provide comprehensive regulation of hazardous wastes.

Materials are designated as hazardous wastes based on a number of criteria

including chemical composition and the ability of toxic organic compounds to

migrate from, or leach out of, the waste. Accurate quantitative data on the

concentrations of toxic organic compounds in the waste or aqueous leachates

of the waste are vital to any program for the proper management of hazardous

wastes. The use of Standard Reference Materials (SRM's), where available, or the use of wel 1 -characterized materials as standards and methods whose accuracy

and precision are known can help ensure the accuracy of analyses. During the

past year, we have characterized and analyzed a liquid sludge material by

combined high resolution capillary column gas chromatography/mass spectrometry

to determine the accuracy and precision achievable in the analysis of a hazardous waste. This work, supported by the EPA, is part of a continuing

project on the development of methods and standards for the analysis of

hazardous wastes. The liquid sludge material, prepared and analyzed at NBS,

is currently being used by the EPA in its quality assurance monitoring programs.

A sample of an industrial organic sludge from a solvent recovery/hazardous

waste storage facility was diluted with a high-boiling ligroin (bp 90-110 °C)

and fortified with known amounts of 11 priority organic pollutants so that the

resulting concentrations were in the 10-50 yg/g (ppm) range. Fifty liters of

the material were prepared, and 100 mL aliquots were packaged in 500 clean,

amber sample vials and sealed with teflon-lined caps.

A stratified random sampling scheme was used to select 15 samples from

the total batch of material for quantitative analysis. Fifteen separate strata

were used, and a random sample within each stratum was chosen. This ensured

full examination of the sample set and at the same time ensured a degree of

random choice of samples. Duplicate analyses of the 15 samples were made, and

the order of the individual analyses was randomized. Quantitative measurements

for phenol, m-dichlorobenzene, hexachlorobenzene, pentachlorophenol , phenanthrene, fluoranthene, pyrene, benzidine, di-n-propyl phthalate, di -2-ethyl hexyl

phthalate, and benz[a]anthracene were made by gas chromatography/mass spectrometry (GC/MS) with selected ion monitoring detection. Table 28 shows the results

of the quantitative determinations. Because samples of this material are currently being used in quality assurance monitoring programs by the EPA, actual

analyte concentrations are not given. In most cases, the experimental concentration agreed well with the gravimetric concentration. Benzidine showed the

poorest agreement. The best precision was obtained for the di -2-ethyl hexyl

phthalate and the polycyclic aromatic hydrocarbons fluoranthene, pyrene, and

benz[a]anthracene; poorer precision was observed for the benzidine, phenol,

and m-dichlorobenzene.

For each of the 11 analytes, a within- and between-bottle analysis of

variance (AN0VA) was performed [1,2]. The results showed no statistically

significant between-bottle variability. Furthermore, approximately one-half

of the calculated between-bottle components of variance were slightly negative,

153
Table 28. Analytes in Quality Assurance Sludge at the 10-50 yig/g (ppm)

Level Determined by GC/MS.

Analyte

Percent Difference Between

Gravimetric Concentration and

Experimental Concentration3

Percent

cv

b

Phenol -5.9 5.7

m-Di chlorobenzene -3.6 4.7

Hexachlorobenzene 0.9 2.1

Pentachlorophenol 1.8 2.5

Phenanthrene -1.3 3.4

Fluoranthene 4.1 1.5

Pyrene 5.4 1.6

Benzidine 31.4 3.3

Di-n-propyl Phthalate 0.0 2.4

Di -2-ethyl hexyl Phthalate 5.4 1.1

Benz[a]anthracene

a

8.7 1.4

aAverage of 29 measurements (one analysis was discarded due to faulty

injection).- Values represent (gravimetric concentration - experimental

concentration)/gravimetric concentration x 100 percent.

b

Percent CV = (standard error/x) x 100, where x is the standard error of

a single measurement.

and the other half were small and slightly positive, a behavior characteristic

of a homogeneous material.

The GC/MS data was also used to characterize the GC/MS measurement

variability. A within- and between-day AN0VA was made for the 11 analytes to

characterize the overall variability of the GC/MS measurements. This yielded

statistically significant between-day components of variance for almost all

analytes. It is therefore necessary to take this component of variability

into account in the experimental design.

The standard error (standard deviation of the weighted average) for each

analyte was calculated from the within- and between-day components of variance

The coefficient of variation (Table 28), which is an expression of uncertainty

was about 3 percent for all analytes. These data indicate that accurate

quantitative results for the determination of toxic organic compounds in a complex matrix, such as an industrial sludge, can be obtained using high

resolution capillary column GC/MS with selected ion monitoring detection.

154
References

[1] Paule, R. C. and Mandel, J., Consensus Values and Weighting Factors,

J. Res. NBS 87_, 377-385 (1982).

[2] Mandel, J. and Paule, R. C., Interlaboratory Evaluation of a Material

with Unequal Numbers of Replicates, Anal. Chem. 42, 1194-1197

(1970); and Correction, Anal. Chem. 43, 1287 (1971).

17. Investigation of Desorption Mechanisms in Laser Desorption and Field

Desorption Mass Spectrometry (26108)

G. D. Byrd, E. White V, D. S. Simons (553)

Large organic molecules that are not sufficiently volatile nor thermally

labile for analysis by electron impact ionization can often be successfully

characterized using various types of desorption mass spectrometry. Some of

the more common desorption methods used in mass spectrometry include field

desorption (FDMS), laser desorption (LDMS), and fast atom bombardment (FAB).

The future development of these ionization methods as analytical tools will

depend on knowledge of the basic phenomena involved in each case. Overall

similarities in the mass spectra produced by various desorption sources suggest that these methods may share one or more common ionization mechanisms.

In this work, some of the proposed mechanisms suggested for FDMS and LDMS

are examined. The FDMS work is being done on a double focusing instrument and

the LDMS work is being carried out on a laser microprobe mass analyzer in

conjunction with the Gas and Particulate Science Division (553).

The two methods were investigated by looking at a series of simple homologous di carboxylic acids [H00C-(CH2 ) -C00H, n = 0 to 5]. Both methods produced

+ +

* (M+H) and (M+H-H2 0) in most cases, but LDMS gave more fragmentation, some of

which may be due to partial pyrolysis of the sample. Also, an increase in

fragmentation/pyrolysis with increasing chain length of the acids was observed

in LDMS but not in FDMS. One explanation of these results is that the minimum

energy necessary for desorption and ionization is applied in the case of FDMS

by the control of the emitter wire current, while the nearly instantaneous

heating of a localized area in LDMS supplies excess energy to the desorbed

species. The amount of heating that takes place in LDMS depends somewhat on the ability of the sample to absorb the photons and disperse the heat

generated. In FDMS, the transfer of heat to the sample is more uniform and

the absorption properties of the sample are not important.

An important mechanism believed to be operational during the desorption

process is that of gas phase ion-molecule reactions which are thought to be

responsible for the production of protonated, cationized, and anionized

species which are often the major peaks in the spectra. Such reactions may

occur just above the surface in LDMS where easily ionized species such as alkali cations attach themselves to neutral organics that are also thermally

desorbed. In order to verify this mechanism for the di carboxylic acids, a metal cation was co-desorbed along with the organic species by defocusing the

laser beam such that the copper metal substrate was included in the target

155
o

GO

156

Figure

29.

Laser

desorption

mass

spectrum

(

LDMS )

of

Succinic

Acid

on

copper.
area. Recent experiments iij) gas phase reactions between metal ions and

organics have shown that Cu reacts with carboxylic acids to release H2 0 from

the collision complex. As shown in figure 29, this product is formed during

the LD experiment, and thus the experiment adds to the mounting evidence for

the importance of gas phase reactions in LDMS.

Some variations in sample mounting were tried to examine the role played

by the substrate material in the desorption process. An attempt to desorb

sample ions from a liquid substrate by LD proved successful. In this experiment, a volatile organometallic solid, ferrocene, was suspended in glycerol

and mounted in the LDMS source. A remarkably clean spectrum consisting almost

completely of M

+ * and no glycerol -related peaks was observed. This demonstrates the difference in the desorption characteristics of the sample and the

substrate material chosen in this case and suggests possible applications of

desorption techniques to volatile species suspended in liquids. Future

experiments will look further at the role of the substrate material in the

desorption process.

18. Development of an Isotope Dilution/Mass Spectrometry Definitive Method

for the Determination of Serum Creatinine (15320, 26108)

A. Cohen, H. S. Hertz, R. Schaffer, M. J. Welch, E. White V

Definitive methods are carefully designed methods which, after rigorous

testing, have been shown to provide highly accurate and precise results [1].

Such methods are used at NBS for the certification of analyte levels in

reference serum pools, which then serve as accuracy transfer standards for the

evaluation of reference and field methods. We have developed definitive

methods for cholesterol, glucose, uric acid, and urea and used these methods

to certify concentrations in a freeze-dried human serum pool. Standard Reference

Material (SRM) 909, as well as in other reference sera. Creatinine, another

clinically important analyte in serum, is used as a measure of renal function.

Development of a definitive method for serum creatinine has now been completed

and certification of the creatinine level in SRM 909 is in progress.

The definitive method for creatinine utilizes isotope dilution/mass

spectrometry, as have all other definitive methods for organic serum analytes.

Initial development work used a creatinine-d3 as the labeled internal standard.

Results were very imprecise, possibly due to isotope effects. We synthesized

a creatinine-1

C2 from glycine-1C and methyl iodide- 1

C according to the

following scheme:

^"3

N

H

157
Using this new labeled material, the precision of the method was substantially

improved (CV's of <0.2 percent).

A brief description of the method is as follows: A weighed quantity of

creatinine-1

C2 is added to a known weight of serum, such that the labeled/

unlabeled creatinine ratio is approximately 4:1. After an overnight equilibration, the serum is put on a weak acid resin column and washed through with

water. Any creatine present is eluted while creatinine is retained. The

creatinine is then eluted with an aqueous ammonia solution and this fraction

is freeze-dried. For derivatization, creatinine is heated in the presence of

2,4-pentanedione, acetic acid, and ethanol for three days at 85-86 °C to form

the ethyl ester of N- (4, 6-dimethyl -2-pyrimidinyl)-N-methyl glycine. Excess

reagents are evaporated and the derivative is dissolved in distilled heptane

for analysis.

Isotope ratio measurements are made on a low resolution, magnetic sector

mass spectrometer modified with an NBS-built microcomputer system, which

controls switching of the magnetic field and handles data acquisition, output,

and reduction. Samples are introduced via a gas chromatograph directly coupled

to the mass spectrometer and equipped with a nonpolar capillary column.

The electron impact mass spectrum of the creatinine derivative has a very

intense (M-C00C2 H 5 ) + ion at m/z 150 and 152 for the unlabeled and labeled

forms, respectively. These two ions are monitored sequentially; the measured

intensities of each are corrected for background and then summed. The summed

intensities are then ratioed for each sample or standard. The standards are mixtures of known amounts of creatinine- 1

C2 and SRM 914 (creatinine) derivatized as described above and are used for calibration of the measured intensity

ratios of serum samples. The technique of bracketing is used for calibration

and the following scheme is employed: For each sample, the two standards whose

unlabeled/labeled weight ratios most closely bracket that of the sample are

chosen. One standard is injected into the GC, followed five minutes later by an injection of the sample, and ten minutes later by the other standard. After

a retention time of approximately 26 minutes, each is measured. The intensity

ratio for the sample is compared with the intensity ratios for the standards

to precisely find the weight ratio for the sample. The samples are remeasured

on a second day with the order of standards reversed. The results from the

two days are averaged for the reported result. To test for the presence of

measurement bias, some samples are remeasured, using (M+l)

+ ions generated by

isobutane chemical ionization.

Prior to the measurement of serum samples, two independently prepared

sets of standards are tested for consistency with use of the bracketing

technique described above. The results of such a test for the standards used

in bracketing serum samples from SRM 909 are shown in Table 29. The agreement

between the two sets is satisfactory, with an apparent bias of 0.12 percent

between the two sets.

The results of two independently prepared sets of samples from SRM 909 are shown in Table 30. The agreement within and between sets meets our criteria for a definitive method. However, before certification is complete,

another set will be run and confirmatory measurements, using isobutane chemical

158
Table 29.

Standard

Consistency Tests for Two Independently Prepared Sets of

Standards, A-D and E-H, by Use of Bracketing.

TibeTedT Ratlos

Mean ID/MS

Bracketed Determined Weighed-In Difference

By Weight Ratio Ratio Percent

A

_a 0.2679

B E,F 0.24965 0.2493 +0.14

C E,F 0.23705 0.2370 +0.02

D F,G 0.2196 0.2193 +0.14

E A,B 0.25765 0.2582 -0.21

F C,D 0.22825 0.2284 -0.06

G D,H 0.21625 0.2166 -0.16

H a 0.2083

aNot bracketed.

Table 30. Creatinine in Human Serum SRM 909 by Isotope Dilution/Mass

Spectrometry—Two Independently Prepared Sets.

Mean mg Creatinine/

g Dry Serum

Sample Set 1 Set 2

1 0.2155 0.2155

2 0.2155 0.2154

3 0.2154 0.2151

4 0.2157 0.2156

5 0.2157 0.2154

6 0.2153

Mean 0.2156 0.2154

CV (%) 0.06 0.08

Difference Between Set Means = 0.09 percent

159
ionization, will be made on a subset of samples selected from these three sets

to provide additional evidence for the absence of significant bias.

Future work in this program will include measurement of creatinine in the

proficiency testing sera of the College of American Pathologists and possibly

other reference sera, remeasurement of glucose in SRM 909, and development of

a definitive method for triglycerides.

References

[1] "Guidelines for the Development of Definitive Methods for Use in

Clinical Chemistry for the National Reference System in Clinical

Chemistry," NRSCC 1, National Committee for Clinical Laboratory

Standards, Villanova, PA 19085 (1979).

19. Two-Dimensional Electrophoresis System Implemented for Protein Separation

and Identification (26111, 15310)

F. A. Giere, D. K. Hancock, D. J. Reeder

As part of our efforts in the separation and characterization of proteins,

with the eventual goal of using them as analytical reagents, work has continued

on refining two-dimensional electrophoresis (2-DE). Our initial experience

with the technique indicated that the resolution and sensitivity were high,

but that reproducibility and staff-hour requirements were unsatisfactory. If

multiple gels could be cast and run simultaneously, gel-to-gel reproducibility

and efficiency could be improved. Various options were explored and a commercially available system was chosen to satisfy our requirements.

A 2-DE laboratory has been set up using this system. This allows the

simultaneous casting and running of 20 first dimension iso-gel rods. Ten

18 x 16 cm gradient gels can also be simultaneously cast and then run in the

second dimension. This gives us a throughput of 30 gels/week compared to the

four previously possible.

A photographic system for documentation of the 2-DE gels has been established. Panatomic-X film, a 35 mm camera with a Wratten #55 gel filter, and a light box with daylight bulbs have been found to give excellent results.

Various methods of protein staining have been tested on the second dimension gels, and these various techniques are now being compared using sets of

identical 2-DE gels. Of particular interest are the silver stains, which give

the greatest sensitivity but also unfortunately the greatest experimental

difficulties. In collaboration with R. Zeisler of the Inorganic Analytical

Research Division, neutron activation analysis of silver-stained gels is being

used to gain information on silver distributions in the gels and on conditions

that may lead to enhancement of the stain and sensitivity of the technique.

Initial results show that low background gels can be prepared and that a uniform distribution of silver occurs in ammoniacal silver stains while silver

is concentrated in the protein bands in the non-ammoniacal stains. Extension

160
of this technique should allow detection of metal -binding enzymes and phosphop rote ins.

Interlaboratory reproducibility continues to be a major problem with

2-DE. This is due, in part, to variations in source materials for casting and

running gels. The composition of the acrylamide, which serves as the separation matrix, has been examined by high-performance liquid chromatography

(HPLC). Differences between freshly recrystallized and commercially available

acrylamide have been determined and correlation of these differences with

electrophoretic separation is under further study. A definitive relationship

has been found between the purity of sodium dodecyl sulfate (SDS) and electrophoretic resolution. Impure SDS was shown to cause band spreading, loss of

staining, and streaking artifacts in the 2-D gels.

Interlaboratory comparison would be further aided by use of marker compounds that would identify molecular weight and isoelectric point parameters.

Potential proteins have been identified as candidate marker compounds. Future

work will involve modification of these proteins with chromophores for easy

visualization.

Several collaborative projects using 2-DE have been pursued with two

other agencies. Work continues with Sandy Hook Marine Laboratories on differentiation of several species of flounder and on coordinating their serum

agglutination properties with 2-DE patterns. A 2-DE comparison study of

bacterial cell wall 1 ipopolysaccharides is being carried out to clarify results

obtained at Walter Reed on bacterial phenotypes used in hybrid vaccines.

20. Laser Photodissociation of Ions and Reactive Ion/Molecule Collisions:

Instrumentation and First Results (26108)

R. G. Christensen, H. S. Hertz, D. J. Pereles, R. L. Sams (550),

M. J. Welch, E. White V

As part of the continuing mass spectrometry competence building program,

"Analysis of Ionization Mechanisms and Ion Structures," we have been investigating the potential of the laser induced photodissociation and the collision

induced dissociation of ions for organic structure determination and analytical

specificity.

A schematic of the three different experimental set-ups for investigating

the photodissociation of ions is shown in figure 30. In each case, the beam

from an argon ion laser with an output power of at least one watt at each of

ten wavelengths between 357 and 529 nm (3.47-2.34 eV) is directed into a double focusing mass spectrometer of Mattauch-Herzog geometry. The signal from

ions created by photodissociation is extracted by chopping the laser beam and

measuring the intensity of the in-phase ion signal with a lock-in amplifier.

A first set of experiments, begun two years ago, was conducted by directing

the laser beam through the source (entry point 1) into the first field-free

region of the mass spectrometer. Ions created by electron impact and then

photodissociated in the first field-free region (metastable ions) were detected

161
CHOPPER

ARGON ION LASER

Figure 30. Schematic of the experimental arrangements for the laser induced

photodissociation of ions. Mirrors have been omitted.

by either accelerating voltage scans or by linked scans of the electric and

magnetic sectors. These experiments showed that the experimental set-up is

capable of detecting ions created by photodissociation. We have confirmed

that photodissociation of organic ions occurs for at least some ions from most

of the compounds examined, that the extent of dissociation is wavelength

dependent even in the visible region and different for different ions, and

that the ion source temperature affects the internal energy of the ions to the

extent of about 0.2 eV/100 °C.

In a second type of experiment conducted recently, we have looked at

photodissociation in the ion source by bringing the laser beam through the

electron impact ionization region perpendicular to the ion beam (entry point

2). After consideration of the residence times of the ions in the laser beam

and the focusing of the laser beam, the arrangement was expected to produce

moderately stronger signals at the cost of the loss of parent-daughter specificity provided by the metastable ion experiments. Instead it was found that

one watt at 514.5 nm dissociated about a quarter of the molecular ions of

butyl benzene. The extent of dissociation was also found to be pressure

dependent with no detectable dissociation observed at an indicated gauge

pressure of about 4 x 10~ 6 torr and maximum dissociation at lower pressures.

Additional experiments have led us to the tentative conclusion that the

pressure in the ionization region is very much higher than expected and that

charge exchange ionization is occurring. We intend to investigate further

since these effects can produce gross changes in the relative intensities of

peaks in photodissociation mass spectra, thus limiting their usefulness.

One promising use of the photodissociation of ions for structure determination is its application to ions of low internal energy, such as those

formed by field ionization, field desorption, chemical ionization, and fast

atom bombardment. The photon-induced fragmentation should provide structural

information for molecules not amenable to electron impact ionization similar
to that obtainable from low energy collision induced dissociation, but with the

advantage of precise energy control by selecting the wavelength. Modification

of the mass spectrometer to bring the laser beam into the first field-free

region (entry point 3), while allowing the use of field ionization and desorption, and the construction of a device to permit multiple passes of the laser

beam through the ion beam are underway.

Experiments on collision induced dissociation of ions began early in 1983

after modifying an existing instrument to a triple quadrupole mass spectrometer. Initial efforts were devoted to understanding the complex focusing

properties of the instrument, comparison of results on several test compounds

with results reported in the literature, and experiments which taught us what

to expect from variations in the ion energy of collisions. We completed our

part of a round robin experiment designed to discover what factors affect

comparability of collision induced dissociation spectra from different mass spectrometers. Reactive collisions have been observed to occur and the

reaction to depend on the ion energy. Plans for the near future include

addition of a data acquisition system, exploration of reactive collision

gases, and application of collision induced dissociation to quantitation by

combined liquid chromatography/mass spectrometry/mass spectrometry with both

reactive and unreactive collision gases.

21 . Determination of Polynuclear Aromatic Hydrocarbons in Environmental

Samples Using Negative Chemical Ionization Mass Spectrometry

(15320, 26108)

6. D. Byrd, L. R. Hi 1 pert, C. R. Vogt

Negative chemical ionization mass spectrometry (NCIMS) is a relatively

new ionization technique which provides a highly selective and sensitive means

of determining certain classes of organic compounds in complex mixtures. NCI mass spectra can be obtained from organic compounds by resonance capture of

thermal electrons if the molecules have positive electron affinities, and if

the electrons emitted from a hot filament are reduced to energies of a few

electron volts through collisions with inert gases such as_CH4 , Ar, or N2 . The major species formed is usually the molecular anion, M~', which often

yields relatively large ion currents and little fragmentation. The specificity

of NCIMS, coupled with a high resolution separation technique such as fused

silica capillary column gas chromatography, provides a highly selective means

for the determination of NCI-sensitive compounds in complex environmental

samples, often with a minimum amount of sample clean-up.

During the past year, we have investigated the NCIMS of polynuclear

aromatic hydrocarbons. We have observed a remarkable selectivity of detection

of benzo[a]pyrene (B[a]P) over the benzo[e]pyrene (B[e]P) isomer. Figure 31

shows the methane NCI spectra for B[a]P and B[e]P, respectively. The NCI

spectrum for the B[a]P shows a strong molecular anion at m/z 252 and a small

(<1 percent) adduct ion at m/z 266. In comparison, the NCI spectrum of the

B[e]P shows a base peak at m/z 266 and a much less intense molecular anion at

m/z 252. Stockl and Budzikiewicz [1] have shown that alkyl radical species

present in the CH4 plasma can react with substrate molecules to give

163
Figure 31. Methane negative chemical ionization mass spectra of

benzo[a]pyrene and benzo[e]pyrene.

(M+C

n

H 2n

)"‘ ions, and we believe this process yields the (M+CH2 )~‘ species at

m/z 266. The NCI spectra of indeno[l ,2,3-cd]pyrene and benzo[ghi]perylene also

show strong molecular anions at m/z 276 and small adduct ions at m/z 290.

Quantitative determinations for benzo[a]pyrene, indeno[l ,2,3-cd]pyrene,

and benzo[ghi]perylene in SRM 1582 (Petroleum Crude Oil) were made by gas

chromatography (GC) NCIMS using B[a]P-d12 as an internal standard and detection

by selected ion monitoring. Earlier attempts to determine B[a]P in a Wilmington

crude oil by GC/MS, using both electron impact and positive chemical ionization

(Cl), proved unsuccessful due to the low concentration of the analyte in the

oil and the many interferences encountered, even in the selected ion monitoring

analysis of the diluted oil. Values for the B[a]P concentration determined by

electron impact and positive Cl GC/MS fell in a range of approximately 1.0-2.

ppm with coefficients of variation of 15-30 percent.

Figure 32 shows a selected ion record chromatogram for the negative CIMS

analysis of a Wilmington crude oil sample. The B[a]P peak is free of interferences and is easily integrated. Five ampoules of SRM 1582 were measured in

triplicate. The results of these determinations are shown in Table 31. The

GC/NCIMS value for the B[a]P concentration in SRM 1582 is in reasonable

agreement with the value of 1.2 ppm determined using a multidimensional HPLCspectrofluorimetric procedure.

164
m/z 252

m/z 264

Total

Ionization

m/z 276

Total

Ionization

Figure 32.

INDENOft ,2 p 3-cdj FYRENE BEUZO ( ghi ) PERYLENE

Negative chemical ionization selected ion record chromatograms

m/z 252, 264, and 276 for analysis of Wilmington crude oil.

165
Table 31. Concentrations of Selected Polynuclear Aromatic Hydrocarbons

in Wilmington Crude Oil Measured by Negative Chemical

Ionization GC/MS.

Concentration (yg/g)

a

Benzo[a]pyrene Indeno[l ,2,3-cd]pyrene

0.951 ± 0.048 0.169 ± 0.044

a Values represent the mean ± standard deviation

Reference

[1] Stock!, D. and Budzikiewicz, H., Org. Mass

(1982).

Benzo[ghi ]pery! ene

1.697 ± 0.135

for 15 determinations.

Spectrom. V7 (8) , 376

22. Polyethylene Methacrylate Coated Electrodes--Nonaqueous Solvent-Stable

Polymer Film Electrode Modified with Methyl viologen (26101)

E. A. Blubaugh, R. A. Durst

We wish to report on the preparation and electrochemical evaluation of

polymer film modified electrodes for use as analytical sensors when derivatized

with an appropriate catalyst. Platinum electrodes have been coated with the

copolymer of ethylene methacrylic acid/Na (PEM), which forms a uniform and

continuous film, and cationic species may be incorporated via ion exchange at

the carboxyl ate sites. The structure of PEM is shown below:

ch3 -(CH2

- CH2 )- (CH2 -C) m

• n/m = 25

C00H

COO" Na

+

These copolymer films offer the advantages of enhanced tensile strength, ease

of preparation, and most importantly, they are stable to a wide range of

organic solvents (e.g., DMF, propylene carbonate, CH3 CN, CH2 C1 2 ), which are important with respect to their utilization as chemical sensors.

These ion-exchange polymers may fulfill the above goal for the following

reasons. Ion-exchange based electrode coatings have the potential technological

advantages of being regenerate and easy to prepare. The electroactive catalyst

is incorporated by immersing the polymer film/electrode into a solution of the

catalyst. A disadvantage of these ion-exchange polymers is that the electrostatic trapping in the ion-exchange process is a chemically reversible step.

That is, the catalyst may be leached from the polymer film. However, relative

solution/polymer film solubilities may be exploited to minimize the leaching

problem.
We have incorporated a variety of redox catalysts in polymer films

of PEM. Some examples of these cationic electroactive species are methyl

viologen, [ruthenium-trisbi pyridine]2 * and 5-phenyl -2- (4-pyridyl )oxazole* ^oTS

(a laser dye). We have concentrated our efforts on the study of methyl viologen

and the laser dyes. We are primarily interested in the methyl viologen as a redox catalyst for the catalytic reduction of organo-halides. The following

reactions are important to investigate:

1

+ MV

11 + le •* MV

+ * (1)

+

MV

+ * + R-X +

+ II + MV

11 + R* + Cl (2)

Figure 33 presents the cyclic voltammogram for the redox reactions in

equation 1 for the reduction of methyl viologen. This reaction takes place in

the polymer film, and analysis of the current-potential curves indicate that

the reaction is chemically reversible. As the reduction of the entrapped

methyl viologen proceeds, the film turns a bright blue color, due to the cation

radical MV '. We have added solutions of organo-halide compounds (e.g.,

1 ,2-dibromoethane) to the solution containing the derivatized polymer film

electrode and observed enhanced reduction current for the catalytic reduction

of the organo-halide (reaction 2). This behavior unfortunately persists for

only a few cyclic voltammograms. Future work will involve investigation of

the cause of instability of these methyl viologen derivatized polymer films

of PEM and their use as analytical sensors.

+ 1.00 +.500 0.00 -.500 - 1.00 - 1.50 - 2.00

E, VOLTS VS. SCE

Figure 33. Cyclic voltammogram for incorporated methyl viologen in

polyethylene methacrylic acid/Na copolymer film electrode

in 0.200 M Na2 S04 solution. Scan rate = 50 mV/second.

167
23. Use of a Zinc Scrubber Column for In-Line Removal of Oxygen from HPLC

Mobile Phases (15320, 26101)

W. A. MacCrehan, W. E. May

There are several reasons why the removal of atmospheric oxygen from

liquid chromatographic mobile phases may be desirable or necessary. In the case of molecular fluorescence detection, the signal may be "quenched" by

intersystem energy transfer from the excited state of the fluorophore to

singlet oxygen. For reductive electrochemical detection, oxygen must be

reduced to very low levels, since the oxygen reduction current contributes

deleteriously to the residual current and detector noise.

We have discovered a simple, but effective, way to quantitatively reduce

oxygen to water in high-performance liquid chromatographic mobile phases,

using a zinc scrubber column (consisting of a short HPLC column, dry-packed

with zinc particles). When a neutral supporting electrolyte is added to the

LC eluent, oxygen is reduced by the following reactions:

We felt that it was important to investigate whether both reactions 1 and 2

went to completion, since the incompleteness of reaction 2 would allow the

undesirable production of hydrogen peroxide in the HPLC mobile phase. To test

for the production of H2 02 , an aliquot of zinc scrubbed eluent was collected

and subjected to differential pulse polarographic analysis. Figure 34-A shows

th£ scan of the unadulterated eluent, with only a reduction wave evident for

Zn 2. To confirm that H2 02 did not contribute

+to the signal observed, an aliquot of Na2 EDTA was added to complex the Zn 2

, shifting its reduction

potential to a more negative value. Had H 2 02 been present, its wave should

have been apparent after the "subtraction" of the zinc wave. However, as figure 34-B illustrates, no H2 02 was detected. To demonstrate the expected

response for H2 02 , an aliquot was added to the level of H 2 02 that would be

expected if only reaction 1 occurred (figure 34-C).

The effectiveness of the oxygen reduction efficiency is apparent when we examine the residual current curve for reductive electrochemical detection

(figure 35). The current level obtained is quite low and is suitable for high

sensitivity work.

The zinc scrubber may also be used in conjunction with fluorescence

detection to eliminate oxygen-quenching. The data presented in Table 32 show

the relative signal enhancement obtained when the oxygen is removed with the

scrubber, when ratioed to the signal obtained in non-degassed saturated mobile

phase (70 percent CH3 CN in H 2 0). In some cases, such as pyrene, the signal

enhancement factor (9) could provide a significant increase in sensitivity

as well as improve the reproducibility of fluorescence measurement.

Zn + 02 + 4H

+ + Zn

+2 + H 2 02

Zn + H2 02 + 2H

+ Zn

+2 + 2H2 0

( 1 )

( 2 )

168
-0.5 -0.7 -0.9 - 1.1 - 1.3

Applied Potential in V

Figure 34. Differential pulse polarographic analysis of zinc scrubbed

eluent. Conditions: sample—eluent diluted 1:10 with

0.1 mol/L sodium phosphate buffer pH 7.0; electrode—SMDE

medium drop; reference electrode—Ag/AgCl 3 mol/L KC1

scan rate—5 mV/s. A—scrubbed eluent alone; B—addition

of 4 x 10'3 mol/L Na2 EDTA; C—addition of 1.3 x 10" 1* mol/L

H2 02.

169
TD •

a> o e

cm E

u nz

VU Nl !N3ddnO LDn

cu

s-3

cn

170
Fluorescence Enhancement Using Zinc Scrubber Column, Relative to

Air Saturated Solution.

Table 32.

Compound

Anthracene

Fluoranthene

Pyrene

1 -Ami nopyrene

Benz[a]anthracene

Benzo[a]pyrene

Phenanthrene

Benzo[b]f1 uoranthene

Benzo[k]f1 uoranthene

Chrysene

Di benz[a ,h]anthracene

Benzo[g , h , i ]peryl ene

Indeno[l ,2,3-cd]pyrene

Relative Fluorescence Signal

1.2

1.7

9.0

1.3

3.0

2.9

2.7

1.9

1.4

2.7

3.3

6.4

1.2

We also found the scrubber column to be useful for increasing the lifetime of a small "reducer column" used for the conversion of nitrated PAH to

their amino derivatives (see technical report 24 of this section). These

short columns contain only 200-300 mg of zinc, which was consumed rapidly when

used with air saturated mobile phases. The time dependence of the conversion

efficiency of the reducer columns during use in HPLC for the reduction of

1-nitropyrene is shown in figure 36. The reducer columns last much longer

(squares) when the zinc scrubber is in the system than when not in the system

(circles)

171
Hours of Operation

Figure 36. Fluorescence signal as a function of reducer column age when used

at constant flow. Conditions: as figure 35 except, analyte

1-nitropyrene; flow rate—1.5 mL/min; open circles/solid line—

without zinc scrubber; squares/dashed line—with zinc scrubber.

172
24. High-Performance Liquid Chromatographic Methods for the Determination of

Nitro-Polynuclear Aromatic Hydrocarbons (N-PAH) in Complex Mixtures

(15320, 26101)

W. A. MacCrehan, W. E. May

Many studies have demonstrated the high mutagenicity of diesel and

gasoline engine particulate emissions. Recent work has shown that unburned

polynuclear aromatic hydrocarbons (PAH) may react with nitrogen oxides to

produce nitrated PAH derivatives (N-PAH). The N-PAH compounds that are formed

are said to represent as much as 50 percent of the "direct-acting" mutagenicity

of diesel particulate extracts when determined by the Ames Salmonella bioassay

[1]. Thus, it is important to develop accurate and reliable methods for

measuring these compounds.

During the past year, we have continued to develop the two high-performance

liquid chromatographic (HPLC) detection methods, mentioned in last year's

report [2], for the HPLC determination of N-PAH in complex mixtures--molecular

fluorescence following on-line reduction to the corresponding amine and

reductive differential pulse electrochemical detection.

The fluorescence detection approach relies on a simple, quantitative

conversion of the N-PAH to the corresponding amine using a short column packed

with zinc metal particles. This "reducer column" follows the analytical

column but precedes the fluorescence detector. The following reaction has

been shown to occur:

Ar - N02 + Zn PH 5,2

> Ar - NH2 + Zn

+2

The measured conversion efficiency was found to be greater than 99.5 percent

for the following N-PAH tested: 2-nitronaphthalene, 9-nitroanthracene,

2-nitrofluorene, 1-nitropyrene, and 6-nitrobenzo(a)pyrene. The peak dispersion

effect of using the reducer column was minimized by its small dimensions

(0.4 x 4 cm) and by mixing small particle zinc metal (7 ym) with silica

particles (20 ym) in an optimized ratio of 1:2 by weight. The peak-width-athalf-height is increased by only about one second for a fifteen-second peak.

Thus, very little chromatographic resolution is lost using this on-line

reduction.

Figure 37 shows a gradient elution chromatogram of several N-PAH standards

using the reduction/fluorescence detection approach. The limit of detection

is quite good--about 15 pg for 1-nitropyrene. This is quite adequate for the

measurement of N-PAH in organic solvent extracts of diesel soot.

Selectivity in the fluorescence detection comes from the ability to

control both the excitation wavelength and resulting emission wavelength. In

fact, for detection of selected N-PAH compounds, the excitation and emission

wavelengths may be programmed during the chromatographic run, optimizing these

parameters for each compound. However, despite the selectivity of this

fluorescence detection approach, the diesel particulate extracts have too many

fluorescent matrix constituents (such as PAH and nitrogen-containing aromatic

173
90%

ch

3

cn

n

1 r

10 20 30

Minutes

Figure 37. HPLC/fluorescence detection of some N-PAH standards after on-line

reduction of the amines. Conditions: column—octadecyl si lane

bonded-phase silica, 5 ym particles, 25 x 0.46 cm; solventgradient of CH

3 CN/H2 0 as marked, 0.025 mol/L NHuOAc pH 5.4; flow

rate— 1.5 mL/minute; zinc/oxygen scrubber 14 x 0.4 cm, 100 mesh

particles; zinc—reducer column 4 x 0.3 cm, packed with Zn/silica;

detector—fluorescence with excitation and emission wavelengths

optimized for each component using 2.5 nm slit widths; sample—

2 y

L injection of a mixture of 10.0 yg/g 2-nitronaphthalene (2-N

Nap), 10.7 yg/g 2-nitrofluorene (2-N Flu), 11.7 yg/g 9-nitroanthracene (9-N Ant), 11.0 yg/g 1-nitropyrene (1-N Pyr) , and

8.0 yg/g 6-benzo[a]pyrene (6-N B[a]P).

174
compounds) for the signals from N-PAH to be measured without interference by a direct injection HPLC analysis. A semi -preparative, normal -phase fractionation

of the diesel particulate extracts has been developed to overcome this selectivity difficulty. Using a hexane/methylene chloride mobile phase and a propyl ami nocyano bonded-phase column, a fraction may be collected that includes

N-PAH from between two to seven aromatic rings, yet excludes all interfering

PAH and other aromatic nitrogen-containing compounds. The detection of

several N-PAH in a methylene chloride extract of diesel particulates, using

the fractionation and reduction/fluorescence approach, is shown in figure 38.

Future work will center on developing an optimum excitation/emission wavelength program and the extension of the technique to include dinitro-PAH.

90% CH

3

CN

ir~i—r i i [

5 10 15 20 25 30

Minutes

Figure 38. Fractionated diesel particulate sample using wavelength programmed

fluorescence detection. Conditions: column—octadecyl si lane

bonded-phase silica, 5 u m particles, 25 x 0.46 cm; solventmethylene chloride extract of diesel particulates fractionated on PAC column; flow rate— 1.5 mL/minute; zinc/oxygen scrubber 14 x 0.4

cm, 100 mesh particles; zinc— reducer column 4 x 0.3 cm, packed

with Zn/silica; detector—fluorescence with the following optimized

wavelengths (2.5 nm slit widths)— 2-nitrofluorene x ex

= 285 nm,

x em

= 370 nm » 9_n1 troanthracene x gx

s 260 nm, x em

= 505 nm, 1-nitropyrene x QV = 360 nm, x om = 430 nm, 6-nitrobenzo[a]pyrene x = 300

6X Cm Ca

nm, x em

= 475 nm.

175
The second approach under development for the HPLC detection of N-PAH

compounds is reductive electrochemical detection. This approach utilizes the

relatively low electrochemical reduction potential of nitro-aromatic compounds

at a mercury-gold thin-film electrode. When this detector cell is used in

conjunction with the zinc-oxygen scrubber (to remove atmospheric oxygen to low

levels), very low residual currents are observed at the potential for the

detection of N-PAH.

In order to optimize the sensitivity and selectivity of the electrochemical detection approach, we are making a thorough investigation of the

electrochemical behavior of N-PAH. This information will then be used to aid

in the design of an optimum detection strategy.

The simplest and most sensitive electrochemical detection mode we have

investigated is amperometry, where a constant potential (usually -0.75 V for

N-PAH) is applied and the current monitored. However, since all species with

their reduction potential at or below -0.75 V give a detector response, the

amperometric mode does not have the selectivity to measure N-PAH directly in

unfractionated diesel particulate extracts. Other work has shown that the

diesel soot contains many electroreducible oxygenated hydrocarbons, such as qui nones, which may co-el ute with the N-PAH and cause an additive interference.

When the normal -phase fractionation is used prior to the reversed-phase

chromatography to isolate the N-PAH, the amperometric detection approach

produces clear signals for 1-nitropyrene and 6-nitrobenzo(a)pyrene (figure 39).

However, we would like to develop a detection technique that would not rely on the same sample preparation procedure used in the reductive/fluorescence

approach. Fortunately, the selectivity of electrochemical detection may be

substantially enhanced by the use of a differential pulse waveform. In this

detection mode, a small amplitude potential pulse- -centered at the potential

where the analyte displays the maximum change in current/potential behavior—

is combined with gated current detection measuring the difference current

resulting from the pulse. A selectivity enhancement results since only

compounds having their current/potential half-wave within the pulse interval

will provide a current output. The detection of N-PAH in an unfractionated

diesel extract is shown in figure 40. A pulse interval was chosen that was optimized for the detection of 1-nitropyrene. Signals for 1-nitropyrene and

6-nitrobenzo( a) pyrene may be seen with little Interference from unresolved

matrix components.

These HPLC procedures will be used in conjunction with gas chromatography/

mass spectrometry (GC/MS ) to certify the concentrations of selected N-PAH in a diesel soot material (SRM 1650).

References

[1] Schuetzle, D. , Env. Health Persp. 47, 65-80 (1983).

[2] Center for Analytical Chemistry Annual Report, NBSIR 82-2620 (1982).

176
90% CH

3

CN

8 16 24 32 40 48 60

Minutes

Figure 39. Fractionated diesel particulate sample using amperometric detection.

Conditions: column—octadecyl si lane bonded-phase silica, 5 ym

particles, 25 x 0.46 cm; solvent—methylene chloride extract of

diesel particulates fractionated on PAC column; flow rate— 1.5 ml/

min; zinc/oxygen scrubber 14 x 0.4 cm, 100 mesh particles; zincreducer column 4 x 0.3 cm, packed with Zn/silica; detector—

amperometry at -0.7 V (versus Ag/AgCl 3 mol/L KC1 reference),

electrode gold-mercury thin film 3.0 mm diameter.

177
90%CH3CN

Minutes

Figure 40. Unfractionated diesel particulate sample using differential pulse

electrochemical detection. Conditions: sample--methylene

chloride extract of diesel particulates; detector electrode--

gold-mercury thin film 1.2 mm diameter; base potential -0.57,

pulse height 5 mV.

178
25. Spectroelectrochemical Investigations of Cyanine Dyes, Ruthenium-

(bipyridine^dithiocarbamate Complexes, and Copper Dithiocroconates

(26101)

E. A. Blubaugh, R. T. Burke, R. A. Durst, G. S. Marbury, W. T. Yap

Several spectroelectrochemical studies are currently in progress to help

elucidate the electrochemical behavior of a variety of interesting research

materials. One of these studies concerns the vinyl ogous family of polyine

monocationic dyes, illustrated by the typical group structure:

C2 H5

X= CH-CH , CH2 , 0 , S , Se , NH

Y=0, 1,2,3...

These compounds are very strong absorbers of radiation in the visible spectral

region with their wavelengths of maximum absorbance determined by the length

of the conjugated chain, the end group h’eteroatom, and the structure of the

end group. These dyes are widely used as sensitizers in photographic emulsions,

laser dyes, and energy conversion catalysts in photovoltaic cells. Using the

model compound 1 ,1 '-diethyl -4,4' -dicarbocyanine iodide (kryptocyanine) , a series of spectra were recorded spectropotentiostatically over a period of

90 minutes. The very sharp isosbestic point observed indicates that the

product, assumed to be a radical, is exceptionally stable. A Nernstian plot

of the applied potential versus log[R]/[0] was linear and, from the slope and

intercept, values of n = 1.10 and E°' = 0.882 V versus SSCE were obtained. In

addition to providing thermodynamic data on these compounds, these spectroelectrochemical studies point to a potential new application. Because of the

exceptionally large absorptivities of both the reactant and product, and the

apparent reversibility of the electron transfer process, their use in electrochromic display devices is suggested.

A great deal of interest and work by a number of research groups has been

directed toward the characterization of bi pyridine complexes of ruthenium.

This interest is generated, in part, because of the usefulness of these

ruthenium complexes for heterogeneous catalysis, for solar energy conversion,

and in electrochromic devices. This work focuses on the electrochemical

characterization of a series of complexes with the general formula:

179
s

II Ru(Hl(bpy)2 S-C-R

where bpy =2, 2'-bipyridine, and

R= -O-CH3 , -N(C2

H

5

) 2 , -N(CH 3

) 2

Cyclic voltammograms of these sulfur-containing complexes show two redox

couples. The couple located in the positive potential region is the Ru(III)/

Ru(II) process, while the redox couple observed at negative potentials is

ascribed to the reduction of the bipyridine ligand to the anion radical. Scan

rate studies indicate that the Ru redox couple is a diffusion controlled

process.

The spectroelectrochemical behavior of the four complexes was also

investigated. A Nernst plot of spectropotentiostatic data for the xanthate

complex gave values for n and E

0 ' of 1.0 and 0.706 V versus SSCE, respectively. Results for the dithiocarbamate complexes were similar with values of

n = 1 and E°‘ about 0.5 V versus SSCE. The observation that the E°‘ values

for the dithiocarbamate complexes were less positive than that for the xanthate

complex presumably reflects the relative stabilization of the ruthenium

oxidation states by the sulfur-containing ligands. It is proposed that the

greater stabilizing power of the dithiocarbamate ligands is due to delocalization of some positive charge into the ligand system by the following resonance forms:

S CH3

W / C-N

/ \

S" ch3

S'

\C = N

/ \

S" ch3

The xanthate ligand, however, does not posses capability for positive charge

delocalization to the same extent.

A third study concerns the electrochemical behavior of dithiocroconate

complexes of Cu(II). The ligands are oxocarbon analogs in which two of the

oxygen atoms have been replaced by sulfur. Certain of these compounds have

been shown to possess the properties of photoconductivity and rectification.

Cyclic voltammetric studies of the Cu (II) /Cu ( I ) redox couple for the dithiocroconate and dicyanomethylene dithiocroconate complexes in dimethyl formamide

showed reversible behavior with E°* values of -0.34 V and -0.05 V versus SSCE,

respectively. Spectroelectrochemical Nernst plots gave values of -0.306 V

and -0.0536 V, respectively, again showing the expected trend toward less

negative reduction potentials with increased ligand conjugation which is

180
better able to delocalize the electron density by tt back bonding with the

metal d and d orbitals. The Nernst plots provided n values of 1.34 and

xz yz

1.49 for the two complexes and further work is in progress to try to account

for these noninteger values.

26. Theoretical Modeling of the Double Step Chronocoulometry and Spectroelectrochemistry of Systems with Strong Product Deposition (26101)

E. A. Blubaugh, R. T. Burke, R. A. Durst, W. T. Yap

A theoretical model has been developed to explain and to analyze the

double-potential step chronocoulometric data for systems with products which

strongly deposit onto the electrodes, such as in the case of the cyanine laser

dyes. Two of the most striking characteristics of the charge, Q, as functions

of time, t, of such a system a re: (1) the net charge passed in the reverse

step, Q

r

, plotted against e = /t-r + /F - /t, where t is the time duration of

the step, yields a set of parallel straight lines with constant slope for

different concentrations of the dye (C*); and (2) intercept (Q

q

) of these

lines with the Q-axis increasing with t. We make the assumption that the

concentration of the product adjacent to the electrode surface is fixed at the

product solubility, s R

, for the condition of phase equilibrium between the

deposited phase and the solution phase. Then solving the diffusion equations

with appropriate initial and boundary conditions for the oxidized and reduced

species, we obtained the following charge-time relationships:

Q ( t<T ) = KC*/t + Q

q

(1)

and

Q

r

= Q(t) - Q(t>x) = KyS

R

e + K(C* - s rY )^ + Q

0

(2)

where K = and y

= /D

r/Dq.

Figure 41 shows plots of Q as a function of /t (unlabeled line) and Q as

a function of e for various t (curves 1 to 5). The points are data from

experiments performed in aqueous solution containing 1.0 mmol/L of the laser

dye and 0.1 mol/L KC1. The values of t for curves 1 to 5 are 6.35 s, 12.75 s,

19.05 s, 25.4 s, and 31.75 s, respectively.

In a system with strong product deposition, the spectropotentiostatic

Nernst plot (figure 42) is biphasic instead of a single straight line. By

applying the condition of phase equilibrium between the deposited phase and

the solution in the thin-layer cell, we obtain the following relation between

the two Nernst plot variables, the applied potential E and r(E) = [A(E) - AD ]/

[A

0

- A(E)],

R

ln[e(E)(l-xf) + x(l-f)] - ln(l-x) for E>E

In r(E) = {

S

(3)

lne(E) + 1 n[f/ (

1 -xf-fe [E] ) ] for E<E

$

181
Figure 41. Plots of Q(t<x ) versus /t and Q

r (t> T ) versus e. For t<x, experimental points are denoted by * and the line is eq. (1). For t>x,

experimental points are denoted by + and the lines are eq. (2)

with different values of t.

182
Figure 42. Plot of E versus In r(E). Experimental points are measured at

368 nm. The solid curve is eq. (3).

where f - s R

/C*, e(E) = exp[n(E-E°' )/RT], and x denotes the ratio of the molar

absorptivity of the reduced form to that of the oxidized form, A(E) denotes

the absorbance at E, and E

$

is the potential at which deposition first occurs. Figure 42 shows a Nernst plot of an experiment using 2.4 mmol/L of laser dye in

0.1 mmol/L KC1. With the application of this model, the diffusion coefficient,

the formal potential, the number of electrons involved in the electrochemical

reactions, and the solubility of the product can be estimated from the experimental data obtained from chronocoulometry and spectroelectrochemistry.

183
C. Outputs and Interactions

(Organic Analytical Research Division)

1 . Publications

Bunding, K. A., Bell, M. I., and Durst, R. A., Surfaced-Enhanced Raman Spectrum

of N-Methylpyridinium Ion on a Silver Electrode, Chem. Phys. Lett. 89,

54-58 (1982).

Coxon, B. and Reynolds, R. C., Synthesis of Nitrogen-15 Labeled Amino Sugar

Derivatives by Addition of Phthal imide - 1

H to a Carbohydrate Epoxide,

Carbohyd. Res. 110 , 53-54 (1982).

Doane, L. M. and Fatiadi, A. J., Electrochemical Oxidation of Croconate Salts

and Evidence of Chemical Equivalency of Carbonyl Oxygen Atom and

Dicyanomethylene Group, Angew. Chem. Intern. Ed. Engl. 21 , 635-636 (1982).

Durst, R. A., The International pH Scale, Methodology and Physiology of Blood

Gases and pH, B. Oeseburg and W. G. Zijlstra, eds.. Private Press, Groninqen,

TFi~Netli¥rTands , 186-189 (1982).

Durst, R. A., Blubaugh, E. A., Bunding, K. A., Fultz, M. L., MacCrehan, W. A.,

and Yap, W. T. , Organic Electrochemical Techniques Having Potential

Clinical Application, Clin. Chem. 28 (9), 1922-1930 (1982).

Fultz, M. L. and Durst, R. A., Mediator Compounds for the Electrochemical Study

of Biological Redox Systems, Anal. Chim. Acta 140 , 1-18 (1982).

Kline, W. F. , Enagonio, D. , Reeder, D. J., and May, W. E., Liquid Chromatographic

Determination of Valproic Acid in Human Serum, J. Liq. Chromatoq. 5 (9),

1697-1709 (1982).

Kong, R. C., Lee, M. L. , Tominaga, Y., Pratap, R. , Iwao, M., Castle, R. M., and

Wise, S. A., Capillary Column Gas Chromatographic Resolution of Isomeric

Polycyclic Aromatic Sulfur Heterocycles in a Coal Liquid, J. Chromatoq.

Sci. 20, 502-510 (1982).

MacCrehan, W. A., A Centrifugal Filtration System Modified to Minimize Losses

of Organomercury Cations, Anal. Chem. 54 , 838-839 (1982).

Margolis, S. A., Reference Materials for Organic Nutrient Measurement:

Proceedings of a Workshop Held at NBS, Gaithersburg, MD, October 23, 1980,

NBS SP 635, 43 pages (1982).

May, W. E., Chesler, S. N., Hertz, H. S., and Wise, S. A., Analytical Standards

and Methods for the Determination of Polycyclic Aromatic Hydrocarbons

in Environmental Samples, Intern. J. Environ. Anal. Chem. 12 , 259-275 (1982).

Schaffer, R. , Mandel, J., Sun, T. , Cohen, A., and Hertz, H. S., Standard

Reference Materials: Evaluation by an I D/MS Method of the AACC Reference

Method for Serum Glucose, NBS SP 260-80, 43 pages (1982).

184
Sniegoski, L. T. , White V, E. , and Konash, P. L., Synthesis of 2-Naphthalene-d7 Sulfonic Acid, J. Labeled Compounds and Radiopharm. 19 (9), 1081-1087 (1982).

Sonnefeld, W. J. , Zoller, W. H., May, W. E., and Wise, S. A., On-Line Multidimensional High-Performance Liquid Chromatographic Determination of

Polycyclic Organic Material in Energy Related Fuel Oils, Polynuclear

Aromatic Hydrocarbons: Phys. and Biol. Chem. , M. Cooke and A. J. Dennis, eds..

Battel le Press, Columbus, OH, 755-764 (1982).

White V, E., Welch, M. J., Sun, T. , Sniegoski, L. T. , Schaffer, R. , Hertz, H. S.,

and Cohen, A., The Accurate Determination of Serum Glucose by Isotope

Dilution/Mass Spectrometry -- Two Methods, Biomed. Mass Spectrom. 9,

395-405 (1982).

Wise, S. A., Allen, C. F. , Chesler, S. N., Hertz, H. S., Hilpert, L. R.

,

May, W. E., Rebbert, R. E., and Vogt, C. R. , Characterization of Air

Particulate Material for Polycyclic Aromatic Compounds, NBSIR 82-2595,

57 pages (1982).

Wise, S. A., Bowie, S. L. , Chesler, S. N., Cuthrell, W. F., May, W. E., and

Rebbert, R. E., Analytical Methods for the Determination of Polycyclic

Aromatic Hydrocarbons in Air Particulate Matter, Polynuclear Aromatic

Hydrocarbons: Phys. and Biol. Chem. , M. Cooke and A. J. Dennis, eds..

Battel le Press, Columbus, OH, 919-929 (1982).

Yap, W. T. and Doane, L. M. , Determination of Diffusion Coefficients by Chronoamperometry with Unshielded Planar Stationary Electrodes, Anal. Chem. 54

(8), 1437-1439 (1982).

Ausloos, P. , Rebbert, R. E., Schwarz, F. P., and Lias, S. G., Pulse- and

Gamma-Ray Radiolysis of Cyclohexane: Ion Recombination Mechanisms,

Rad. Phys. and Chem. 21 , 27 (1983).

Botto, R. E. and Coxon, B., Nitrogen-15 Nuclear Magnetic Resonance Spectroscopy

of Neomycin B and Related Aminoglycosides, J. Am. Chem. Soc., 1021-1028

(1983).

Bowers, G. N., Jr., Alvarez, R. , Cali, J. P., (NBS retired), Eberhardt, K. R.

,

Reeder, D. J., Schaffer, R. , and Uriano, G. A., Standard Reference Materials:

The Measurement of the Catalytic (Activity) Concentration of Seven Enzymes

in NBS Human Serum SRM 909, NBS SP 280-83, 95 pages (1983).

Christensen, R. G. , White V, E., Meiselman, S., and Hertz, H. S., Quantitative

Trace Analysis by Reversed-Phase Liquid Chromatography-Mass Spectrometry,

J. Chromatogr. 271 , 61-70 (1983).

Covington, A. K. , Bates, R. G. , and Durst, R. A., Definition of pH Scales,

Standard Reference Values, Measurement of pH and Related Terminology,

Pure and Appl . Chem. 55 , 1467-1476 (1983).

185
Davidson, R. M. , Margolis, S. A., White V, E., Coxon, B., and Oppenheimer, N. J.,

A New, Facile Synthesis of 2-ami no(pento- and Hexo-furanojoxazol ine

Derivatives, Carbohyd. Res. Ill , C16-C19 (1983).

Davidson, R. M. , White V, E., Margolis, S. A., and Coxon, B., Synthesis of

Nitrogen-15 Labeled 2-Ami no(glycofurano)Oxazol ines Via Glycosylamine

Intermediates, Carbohyd. Res. 116 , 239-254 (1983).

Durst, R. A., pH Values, Scales, and Standards, Geiqy Scientific Tables, 8th

ed. (3), 54-57 (1983).

Fatiadi, A. J., Preparation and Synthetic Applications of Cyano Compounds,

The Chem. of Functional Groups , Suppl

C, S. Patai and Z. Rappoport, eds.,

John Wiley and Sons, London, 1057-1303 T"1983).

Fatiadi, A. J. , Priority Toxic Pollutants in Human Urine: Their Occurrence and

Analysis (Monograph), NBS/EPA, NBSIR 83-2690 (1983).

Hertz, H. S. , Chesler, S. N., Gump, B. H., and May, W. E., Intercalibration:

A Means for Interlaboratory Validation of Environmental Data, A Summary

of Activities Related to Offshore Dri 11 i ng of Petroleum at the Natl

Bureau of Stds. 1975-1981 , 68-70 (1983).

Kline, W. F. , Allen, C. F. , Chesler, S. N., Hilpert, L. R. , and Wise, S. A.,

Development of Analytical Methodology for the Determination of Organochlorine Compounds in Human Liver Samples, in The Pilot Natl. Environ.

Specimen Bank -- Anal, of Human Liver Samples, R. Zeisler, S. H. Harrison,

and S. A. "Wise, eds., NBS SP 656, 91-97 (1983).

Maas, A. H. J., Weisberg, H. F. , Zijlstra, W. G. , Durst, R. A., and SiggaardAndersen, 0., Reference Method for pH Measurement in Blood, J. Clin. Chem.

Clin. Biochem. 21, 313-321 (1983).

MacCrehan, W. A., Determination of Organomercury Cations in Tissue Samples Using

Liquid Chromatography with Amperometric Detection, in The Pilot Natl. Environ.

Specimen Bank -- Anal, of Human Liver Samples, R. Zeisler, S. H. Harrison,

and S. A. Wise, eds., NBS SP 656, 115-119 (1983).

Margolis, S. A. and Coxon, B., Comparison of Amino Acid Analysis of Angiotensin

by Proton NMR and Classical Methods, Abstracts of Am. Soc. of Biol. Chem.

74th Mtg. , San Francisco, CA, (1983).

May, W. E., Gump, B. H. , Chesler, S. N., and Hertz, H. S., Analysis of Polynuclear

Aromatic Hydrocarbons in Marine Samples by Coupled-Column Liquid Chromatography, A Summary of Activities Related to Offshore Drilling of Petroleum

at the Natl . Bureau of Stds. 1975-1981 , 1 50-155 (198JT

May, W. E., Miller, M. M. , Tewari , Y., Brown-Thomas , J. M., and Goldberg, R.

The Solution Thermodynamics of Some Slightly Soluble Hydrocarbons in Water,

J. Chem. Eng. Data 28 , 197 (1983).
Perry, B. W. , Doumas, B. T. (Chairman), Bayse, D. D., Butler, T. , Cohen, A.,

Fellows, W. , Garber, C. C., Howell, B., Koch, T. , Krishnamurthy , S.,

Louderbach, A., McComb, R. B., Miller, D. , Miller, R. R. , Rand, R. N., and

Schaffer, R. , A Candidate Reference Method for Determination of Bilirubin

in Serum. Test for Transferability, Clin. Chem. 29 (2), 297-301 (1983).

Sniegoski, L. T. and White V, E., Synthesis of l-Dodecyl-d2 5 Phosphate, J.

Labeled Compounds and Radiopharm. 20 (2), 303-309 (1983).

Wise, S. A., High-Performance Liquid Chromatography for the Determination of

Polycyclic Aromatic Hydrocarbons, Chapter 5, Handbook for Polycyclic

Aromatic Hydrocarbons, A. Bjtfrseth, ed. , Marcel Dekker, New York, NY,

183-256 (1983).

Wise, S. A., The National Environmental Specimen Bank: Background and History,

in The Pilot National Environ. Specimen Bank -- Analysis of Human Liver

Samples, R. Zeisler, S. H. Harrison, and S. A. Wise, eds., NBS SP 656,

1-4 (1983).

Wise, S. A., Fitzpatrick, K. A., Harrison, S. H., and Zeisler, R., Operation of

the U.S. Pilot National Environmental Specimen Bank Program, in Environmental

Specimen Banking and Monitoring as Related to Banking , R. A. Lewi s

,

N. Stein, and C. W. Lewis, eds., Univ. of Saarland, Germany, 108-129 (1983).

Wise, S. A. and May, W. E., The Effect of Ci 8 Surface Coverage on Selectivity

in Reversed-Phase Liquid Chromatography of Polycyclic Aromatic Hydrocarbons,

Anal. Chem. 55, 1479-1485 (1983).

Yap, W. T. , Durst, R. A., Blubaugh, E. A., and Blubaugh, D. D. , Chronoamperometry of Polymer-Modified Electrodes: Charge Transport by Diffusion and

Migration, J. Electroanal. Chem. 144 , 69-75 (1983).

Yap, W. T. , Schaffer, R. , Hertz, H. S., White V, E., and Welch, M. J., On the

Difference Between Linear and Non-Linear Models in Bracketing Procedures

in Isotope Dilution/Mass Spectrometry, Biomed. Mass Spectrom. 10 (4),

262-264 (1983).

Zeisler, R. , Harrison, S. H., and Wise, S. A., Analysis of Human Liver Specimens

in the U.S. Pilot Environmental Specimen Bank Program, in Environ. Specimen

Banking and Monitoring as Related to Banking , R. A. Lewis, N. Stein,

C. W. Lewis, eds., Univ. of Saarland, Germany, 331-351 (1983).

Bunding, K. A., Durst, R. A., and Bell, M. I., Surface-Enhanced Raman Spectroscopy of N-Methylpyridinium Cation and Pyridine: Identification of

Surface Species, J. Electroanal. Chem. , in press.

Durst, R. A., Clinical Electrode Potentiometry: Sources of Error, Reference

Methods and Materials, Proceedings of the Workshop on Direct Potentiometric Measurements in Blood, in press.

Fatiadi, A. J., The Oxidation of Organic Compounds by Active Manganese Dioxide,

Oxidative Procedures in Org. Chem. Involving Metal Compounds , W. J. Mijs,

ed.. Plenum Press, London, in press.

187
Fultz, M. L. and Durst, R. A., Investigation of Two Multichannel Image Detectors

for Use in Spectroelectrochemistry, Talanta, in press.

Kamat, P. V. , Fox, M. A., and Fatiadi, A. J., Dye Loaded Polymer Electrodes,

Photoelectrochemical Sensitization by Croconate Violet in Polymer Solutions

and Films, J. Amer. Chem. Soc. , in press.

Margolis, S. A. and Konash, P. L., The HPLC Analysis of Diastereomers and

Structural Analogs of Angiotensins I and II, Anal. Biochem. , in press.

Mattammal, M. B., White V, E., Zenser, T. V., and Davis, B. B., Mass Spectrometry

of 2-Substitutes-Y-Arylthi azoles III. Identification of Microsomal NitroReduction Products by Mass Spectrometry, Biomed. Mass Spectrom. , in press.

May, W. E., Brown-Thomas , J. M. , Chesler, S. N., Guenther, F. R. , Hilpert, L. R.,

Parris, R. M. , Richie, K. L., Sonnefeld, W. J., Wise, S. A., and

Hertz, H. S., Interlaboratory Comparisons of Quantitative Analyses of

Individual Compounds in Simple and Complex Mixtures, Oak Ridge Press,

in press.

May, W. E. , Chesler, S. N., Hilpert, L. R. , Hertz, H. S., Rebbert, R. E.,

Vogt, C. R. , and Wise, S. A., Characterization of Polycyclic Aromatic

Hydrocarbons in Air Particulate Extracts by Liquid and Gas Chromatographic

Methods: Identification and Analysis of Organic Pollutants in Air,

L. R. Keith, ed. , Butterworth Publications, in press.

Wise, S. A., Analytical Techniques for the Determination of Petroleum Hydrocarbons and Combustion Products, Pollution and the Protection of Water Quality , Hemisphere Publishing, New York, NY, in press.

Wise, S. A., Interlaboratory Comparisons and the Use of Reference Materials for

Quality Control of Analytical Methodologies, Pollution and the Protection

of Water Quality , Hemisphere Publishing, New York, NY, in press.

Wise, S. A., Campbell, R. M. , May, W. E., Lee, M. L., and Castle, R. N., Normaland Reversed-Phase Liquid Chromatographic Separations of Polycyclic Aromatic

Sulphur Heterocycles, Polynuclear Aromatic Hydrocarbons: Combustion

Processes, Environ. Effects, and Biochem. , M. Cooke, A. J. Dennis, and

G. L. Fisher, eds., Battelle Press, Columbus, OH, in press.

Wise, S. A., Sander, L. C. , and May, W. E., Modification of Selectivity in

Reversed-Phase Liquid Chromatography of Polycyclic Aromatic Hydrocarbons

Using Mixed Stationary Phases, J. Chromatog. , in press.

Velapoldi, R. A., White, P. A., May, W. E., and Eberhardt, K. , Spectrofluorometric

Determination of Polycyclic Aromatic Hydrocarbons in Aqueous Effluents from

Generator Columns, Anal . Chem. , in press.

Yap, W. T., Blubaugh, E. A., Durst, R. A., and Burke, R. T., Spectroelectrochemistry of a System Containing a Species which Deposit onto the Electrode,

J. ETectroanal . Chem.

in press.

188
Yap, W. T. , Burke, R. T. , Blubaugh, E. A., and Durst, R. A., Chronocoulometry

of a System with Strong Product Adsorption, J. Electroanal. Chem. , in press.

Fatiadi, A. J., Permanganate Ion: An Old, But Still Novel Oxidant in Organic

Chemistry, Oxidate Procedures Involving Metal Compounds in Org. Chem. , submitted for publication.

MacCrehan, W. A. and May, W. E., Oxygen Removal in Liquid Chromatography Using

Zinc/Oxygen Scrubber Column, Anal. Chem. , submitted for publication.

May, W. E. and Wise, S. A., Liquid Chromatographic Determination of Polycyclic

Aromatic Hydrocarbons in Air Particulate Extracts, Anal . Chem. , submitted

for publication.

Parris, R. M. , Guenther, F. R. , May, W. E., Chesler, S. N., Analysis of PCB's

in Oil: Technique On SRM Development, Proc. Conf. on Measurements and

Stds. for Recycled Oil -- IV, National Bureau of Standards, Gaithersburg,

MD, (September 14-16, 1982J7 submitted for publication.

Roberts, G. D. and White V, E., Silver Sulfonates as Mass Standards in Field

Desorption Mass Spectrometry, Biomed. Mass Spectrom. , submitted for

publication.

Welch, M. J., Cohen, A., Hertz, H. S., Ruegg, F. C., Schaffer, R.

,

Sniegoski, L. T. , and White V, E., An Isotope Dilution Mass Spectrometric

Method for the Accurate Determination of Serum Urea, Anal . Chem. , submitted for publication.

2. Talks

D. J. Reeder, "Materials Variations in Polyacrylamide Gel Electrophoresis,"

Two-Dimensional Gel Electrophoresis Journal Club Seminar, October 5, 1982.

Invited

W. E. May, "On-Line Multidimensional Liquid Chromatographic Determination of

PAH in Complex Samples," ASTM E- 19 Committee on Chromatography, New Orleans,

LA, October 12, 1982. Invited

R. G. Christensen, "Quantitative Trace Analysis by Reversed-Phase LC/MS Employing

Continuous Preconcentration," Second Workshop on LC/MS and MS/MS of the

International Association of Environmental Analytical Chemistry, Montreaux,

Switzerland, October 21, 1983. Invited

S. A. Wise, "Normal- and Reversed-Phase Liquid Chromatographic Separations of

Polycyclic Aromatic Sulfur Heterocycles," Seventh International Symposium

on Polynuclear Aromatic Hydrocarbons, Columbus, OH, October 26, 1982.

E. A. Blubaugh, "Electrochemical Techniques: Cyclic Voltammetry and Hybrid

Electrochemical Techniques," Second NBS/ADABSE Analytical Chemistry

Workshop, NBS, Gaithersburg, MD, October 27, 1982.

189
I

R. A. Durst, "Electrochemistry," Second NBS/ADABSE Analytical Chemistry Workshop, 1 NBS, Gaithersburg, MD, October 27, 1982. Invited

R. Schaffer, "Certified and Uncertified Values Assigned to SRM's," Capital

Section of the AACC, Columbia, MD, November 17, 1982. Invited

S. A. Wise, "Determination of Polycyclic Aromatic Compounds in Environmental

Samples," Eastern Analytical Symposium, New York, NY, November 17-19, 1982.

Invited

A. J. Fatiadi, "The Chemistry and Electrochemistry of Oxo- and Pseudo-Oxocarbons,"

Georgetown University, Washington, DC, November 18, 1982. Invited

W. E. May, "On-Line Multidimensional Liquid Chromatography," Eastern Analytical

Symposium, New York, NY, November 18, 1982. Invited

B. Coxon, "Nitrogen-15 NMR Spectroscopy of Aminoglycosides," American University,

Washington, DC, November 30, 1982. Invited

R. A. Durst, "Polymer Modified Electrodes for Organic Electrochemistry," Special

Symposium on NBS Research, NBS, Gaithersburg, MD, January 10, 1983. Invited

R. A. Durst, "Electrochemical Approaches to Organic Analysis," California

Department of Health Services, Los Angeles, CA, January 20, 1983. Invited I

R. A. Durst, "Novel Electrochemical Techniques for Organic Analysis," IBM

Research Laboratory, San Jose, CA, January 21, 1983. Invited

W. A. MacCrehan, "Liquid Chromatographic, Organometal Speciation Using Electrochemical Detection," Gordon Research Conference on Chemical Oceanography,

Ventura, CA, January 31, 1983. Invited

R. A. Durst, "Overview of Strategies for the Characterization and Analysis of

Organic Compounds," Lawrence Berkeley Laboratory, Berkeley, CA, February 1,

1983. Invited

R. A. Durst, "Organic Electrochemical Research at the National Bureau of

Standards," Lawrence Livermore Laboratory, Livermore, CA, February 2, 1983.

Invited

1 R. A. Durst, "Electrochemical Approaches to Organic Analysis," Department of

Health Services, Berkeley, CA, February 4, 1983. Invited

W. E. May, "Multidimensional HPLC Techniques Applied to the Determination of

Polycyclic Aromatic Compounds in Complex Mixtures," Emory University,

Atlanta, GA, February 22, 1983. Invited

J. M. Brown-Thomas, "Introduction to Basic Principles in High-Performance

Liquid Chromatography," Alcorn State University, Lorman, MS, February 24,

1983. Invited

190
W. E. May, "Multidimensional HPLC Techniques Applied to the Determination of

Polycyclic Aromatic Compounds in Complex Mixtures," Alcorn State University

Lorman, MS, February 24, 1983. Invited

F. R. Guenther, "Characterization of Wood Combustion Emissions," 34th Pittsburgh

Conference on Analytical Chemistry and Applied Spectroscopy, Atlantic City,

NJ, March 7, 1983.

W. E. May, "HPLC Determination of Nitrated- PAH in Complex Mixtures," 34th

Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy,

Atlantic City, NJ, March 7, 1983.

W. A. MacCrehan, "Conversion of Nitro-Polycyclic Aromatic Hydrocarbons to the

Amines Using an On-Line Liquid Chromatographic Reducer Column," 34th

Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy,

Atlantic City, NJ, March 8, 1983.

J. M. Brown-Thomas , "Determination of Organic Nutrients in Milk by Multidimensional

High-Performance Liquid Chromatography," 34th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Atlantic City, NJ, March

10, 1983.

W. F. Kline, "The Determination of Organochlorine Pesticide Residues in Human

Liver Specimens from the NBS/EPA Pilot National Environmental Specimen

Bank Program," 34th Pittsburgh Conference on Analytical Chemistry and

Applied Spectroscopy, Atlantic City, NJ, March 10, 1983.

W. E. May, "Trace Organic Analytical Applications of HPLC," Bishop College,

Dallas, TX, March 21, 1983. Invited

W. E. May, "Liquid Chromatographic Methods for Determination of Physico-chemical

Properties of Organic Compounds," Bishop College, Dallas, TX, March 21, 1983.

Invited

W. E. May, "Trace Organic Analytical Applications of HPLC," Prairie View University, Prairie View, TX, March 22, 1983. Invited

W. E. May, "Liquid Chromatographic Methods for Determination of Physico-chemical

Properties of Organic Compounds," Prairie View University, Prairie View, TX,

March 22, 1983. Invited

S. A. Wise, "Liquid Chromatography for the Determination of Polycyclic Aromatic

Compounds in Environmental Samples," Department of Health Services, State

of California Air and Industrial Hygiene Laboratory, Berkeley, CA,

March 23, 1983. Invited

W. E. May, "Trace Organic Analytical Applications of HPLC," Huston-Tillotson

College, Austin, TX, March 24, 1983. Invited

W. E. May, "Liquid Chromatographic Methods for Determination of Physico-chemical

Properties of Organic Compounds, Huston-Tillotson College, Austin, TX,

March 24, 1983. Invited

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I

W. E. May, "Trace Organic Analytical Applications of HPLC," Alabama A&M University, Huntsville, AL, March 25, 1983. Invited

_P I W. E. May, "Liquid Chromatographic Methods for Determination of Physico-chemical

Properties of Organic Compounds," Alabama A&M University, Huntsville, AL,

March 25, 1983. Invited

B. Coxon, "Two-Dimensional DEPT Heteronuclear J-Resolved 13 C NMR and 15 N NMR

Spectrum Editing," 24th Experimental NMR Conference, Asilomar, CA,

April 13, 1983.

W. E. May, "Liquid Chromatographic Methods for the Determination of Polynuclear

Aromatic Hydrocarbons (PAH) and Nitro-PAH in Environmental Samples," Florida

A&M University, Tallahassee, FL, April 14, 1983. Invited

L. T. Sniegoski, "The Use of Isotope Dilution/Mass Spectrometry for the Accurate

Determination of Organic Constituents in Serum," Women's Forum, NBS,

Gaithersburg, MD, April 20, 1983. Invited

W. E. May, "Environmental Applications of High Performance Liquid Chromatography,"

ACS, Norfolk, VA, April 22, 1983. Invited

J. M. Brown-Thomas, "Determination of Organic Nutrients in Milk by Multidimensional

High-Performance Liquid Chromatography, Hampton Institute, Hampton, VA,

April 29, 1983. Invited

S. A. Wise, "Modification of Selectivity in Reversed-Phase Liquid Chromatography

of Polycyclic Aromatic Hydrocarbons Using Mixed Stationary Phases," Seventh

International Symposium on Column Liquid Chromatography, Baden-Baden,

Germany, May 2-6, 1983.

M. J. Welch, "The Accurate Determination of Serum Urea and Creatinine by Isotope

Dilution/Mass Spectrometry," ASMS, Boston, MA, May 10, 1983.

L. R. Hi 1 pert, "Accuracy and Precision in the GC/MS Determination of Toxic

Organic Compounds in Hazardous Wastes," ASMS, Boston, MA, May 11, 1983.

L. R. Hilpert, "Hazardous Waste Analysis -- Sticking to Measurements and Avoiding

Controversy," ASMS Workshop on Sampling and Analysis of Hazardous Wastes,

Boston, MA, May 11, 1983. Invited

W. A. MacCrehan, "Reductive LCEC of Nitro-Polynuclear Aromatic Hydrocarbons

(N-PAH) Diesel Exhaust Particulates Using a Zinc/Oxygen Scrubber Column,"

1983 International Symposium on LCEC and Voltametry, Indianapolis, IN,

May 16, 1983. Invited

R. A. Durst, "Clinical Electrode Potentiometry : Sources of Error, Reference

Methods and Materials," Workshop or Direct Potentiometric Measurements in

Blood, NBS, Gaithersburg, MD, May 20, 1983. Invited

192
W. E. May, "Liquid Chromatographic Determination of Nitrated Polynuclear Aromatic

Hydrocarbons in Complex Mixtures," 10th Annual Meeting of the National

Organization for the Professional Advancement of Black Chemists and Chemical

Engineers, Knoxville, TN, May 27, 1983.

W. E. May, "Liquid Chromatographic Determination of Physico-chemical Properties

of Hydrophobic Substances," 10th Annual Meeting of the National Organization

for the Professional Advancement of Black Chemists and Chemical Engineers,

Knoxville, TN, May 27, 1983.

R. A. Durst, "Ionic Activity and Single Ion Activity Coefficients for Calcium

Ion at 25 °C," 1st Meeting of the European Working Group on Ionized Calcium,

Oslo, Norway, June 17, 1983. Invited

R. G. Christensen, "Quantitative Trace Organic Analysis by Combined LC/MS,"

Symposium on LC/MS 186th ACS National Meeting, Washington, DC, August 29,

1983.

B. Coxon, "Spectrum Editing of the Nitrogen-15 NMR Spectra of Aminoglycosides

by the DEPT Technique," 1983 American Chemical Society Meeting, Washington,

DC, August 29, 1983.

B. Coxon, "Two-Dimensional DEPT Heteronuclear J-Resolved 13 C NMR of Digitoxose,"

1983 American Chemical Society Meeting, Washington, DC August 29, 1983.

B. Coxon, "Two-Dimensional Proton-Proton Chemical Shift Correlated NMR Spectroscopy of Digitoxose and Its Anomers," 1983 American Chemical Society

Meeting, Washington, DC, August 29, 1983.

B. Coxon, "Structure of the Reaction Product of 4-phenyl -2, 3-dioxobutyro-l ,4-

lactone, a Dehydroascorbic Acid/Analog, with o-phenylene Diamine," 1983

American Chemical Society Meeting, Washington, DC, August 31, 1983.

W. F. Kline, "The Determination of Organochlorine Pesticide Residues in Human

Liver Specimens from NBS/EPA Pilot Environmental Specimen Bank Program,"

The Eighth U.S. -German Seminar of State and Planning on Environmental

Specimen Banking, NBS, Gaithersburg, MD, September 19, 1983. Invited

S. A. Wise, "Status of the U.S. Pilot National Environmental Specimen Bank,"

International Review of Environmental Specimen Banking, NBS, Gaithersburg,

MD, September 21, 1983. Invited

3. Committee Assignments

Willie E. May

Chairmen, ADABSE, Analytical Workshop Committee

Member, ASTM, Committee D19 on Water,

Committee El 9 on Chromatography

Member, ACS

Member, Washington Chromatography Discussion Group

193
Bruce Coxon

Secretary, ASTM, Committee E13.07 on Nuclear Magnetic Resonance,

Committee El 3 on Molecular Spectroscopy

Associate Referee, International Commission for Uniform Methods of Sugar

Analysis, Subcommittee 5 on 100 °S Point of Sugar Scale

Referee, U.S. National Committee on Sugar Analysis, Subcommittee 5 on 100 °S Point of Sugar Scale

Richard A. Durst

Member, Advisory Board, Analytical Chemistry

Member, ASTM, Committee D19 on Water

Member, Board of Advisory Editors, Ion-Selective Electrode Reviews

Member, Department of the Interior, Office of Water Data Coordination,

Task Group 5 on Chemical and Physical Quality of Water and Sediments

Secretary, IFCC, Scientific Committee, Analytical Section, Expert Panel

on pH and Blood Gases

Member, Instrument Society of America, Subcommittee SP76.02 on Electrochemical Analyzers

Member, IUPAC, Committee V on Analytical Chemistry, Subcommittee 5 on Electroanalytical Chemistry

Member, NCCLS, Subcommittee on Electroanalytical Methods

Member, NCCLS, Subcommittee on pH and Blood Gases

Laurence R. Hi! pert

Member, ASTM, Committee D34 on Waste Disposal

Dennis J. Reeder

Member, AACC, Committee on Standards

Study Group on Cortisol

Study Group on Total Serum Protein

Associate Member, IFCC, Expert Panel on Drug Effects in Clinical Chemistry

Member, NCCLS, Subcommittee on Total Protein

Robert Schaffer

Member, AACC, Committee on Standards

Subcommittee on Cholesterol

Subcommittee on Creatinine

Subcommittee on Electrolytes

Subcommittee on Glucose

Subcommittee on Iron

Sbucommittee on Theophylline

Subcommittee on Urea

Subcommittee on Uric Acid

Member, NCCLS, Area Committee for Clinical Chemistry

Subcommittee on Calibration Reference and Control Materials

Subcommittee on Quantities and Units

Subcommittee on Reference Methods and Materials

Member, Council for National Reference System in Clinical Chemistry

194
4. Other

a. Seminars

October 6, 1982

October 19, 1982

November 16, 1982

November 19, 1982

December 1, 1982

January 19, 1983

January 31, 1983

February 17, 1983

February 24, 1983

March 14, 1983

April 11, 1983

April 12, 1983

April 21, 1983

Branimir Simic-Slavaski , Case Western Reserve University

"Surface-Enhanced Raman Scattering from Adsorbed Phthalacyanines and Their Electrochemical Behavior".

Anders Colmsjt5, University of Stockholm, "The Shpol'skii

Effect and Its Applications in Analytical Chemistry".

James B. Call as. University of Washington, "ReversedPhase Chromatography — Adsorption or Partitioning

Chromatography?".

Robert C. Allen, Medical University of South Carolina,

"Two-Dimensional Electrophoresis: Denaturing and NonDenaturing Conditions".

George N. Bowers, Jr., Hartford Hospital, "Standardization

of Ionic Calcium Measurements".

Alan Lowe, DuPont Company, "HPLC Columns for High Speed

and High Resolution Analyses".

Elwood 0. Titus, Food and Drug Administration, "The Role

of Calcium in Trans Membrane Systems".

Marko Branica, Ruder Baskovic Institut, Yugoslavia,

"Electrochemical Determination of Metal -Ligand

Interactions in Natural Waters".

Otto S. Wolfbeis, Institut fur Organische Chemie, Austria,

"Synthesis and Application of Fluorescent Reagents to

be Used in Analytical Chemistry and Biochemistry".

James Alexander Apffel , Free University, The Netherlands,

"Quantitation in On-Line Multidimensional HPLC".

Thomas Doyle, Food and Drug Administration, "HighPerformance Liquid Chromatography of Enantiomers Using

Chiral Stationary Phases".

William P. Reed, NBS Office of Standard Reference

Materials, "Research and Measurement Needs for the

Certification of Standard Reference Materials, Plans,

and Perspectives for FY 84".

Dennis Gere, Hewlett-Packard Company, "Bioanalytical

Applications of Supercritical Fluid Chromatography".

195
May 4, 1983

July 6, 1983

Jaromir Ruzicka, The Technical University of Denmark,

"From a Test Tube to Integrated Microcondiut by Flow

Injection Analysis — A New Approach to Sample Handling

in the Research Laboratory".

David Firestone, Richard Niemann, and James Sphon, Food

and Drug Administration, "Analytical Methods for the

Determination of Dibenzodioxins in Environmental Samples",

b. Conferences Sponsored

October 24-29, 1982 -

September 21, 1983 -

W. E. May, Workshop on "A Survey of State-of-the-Art

Instrumental Methods for Chemical Analysis," jointly

sponsored by the National Bureau of Standards and the

Association for the Development and Advancement of

Black Scientists and Engineers (ADABSE), National

Bureau of Standards, Washington, DC.

S. A. Wise, "The International Review of Environmental

Specimen Banking, National Bureau of Standards,

Washington, DC.

c. Seminars Organized

S. A. Wise, "The 8th U.S. -German Seminar of State and Planning on Environmental

Specimen Banking," National Bureau of Standards, Washington, DC,

September 19-20, 1983.

d. SRM Certification/Information Values

1) SRM 911, Bilirubin

2) SRM 1581, Organics in Drinking Water

3) SRM 1582, Petroleum Crude Oil

4) SRM 1583, Pesticides in Oso-octane

5) SRM 1584, Phenyls in Methanol

6) SRM 1585, Polychlorinated Biphenyl Congeners in Iso-octane

7) SRM 1586, Unlabeled and Deuterium Labeled Priority Pollutants

8) SRM 1514, Purity Established for Differential Thermal Analysis

9) SRM 1648, St. Louis Urban Dust

10)

SRM 1649, Urban Dust, Organics

196
IV. Gas and Particulate Science Division

Harry L. Rook, Chief

Raymond L. McKenzie, Deputy Chief

A. Division Overview

The Gas and Particulate Science Division conducts research to develop new

or improved chemical measurement procedures and uses those procedures to

certify the chemical composition of NBS standards and to solve analytical

problems related to national needs. The research is directed toward the

measurement of chemical composition on a microscopic scale and the measurement

of gaseous molecules in complex mixtures or in atmospheric samples. The

Division's programs are carried out by four groups with the research effort

divided approximately equally between gas analytical research and microanalytical research.

During 1983, the Division has completed a long range plan for research in

trace gas analysis and standards and has initiated research in two major areas.

In toxic organic gas analysis, our efforts have been devoted to the development

of standards and methods of analysis for gases at concentrations ranging from a few parts-per-billion (ppb) to 10 parts-per-million (ppm). Although the

microgravimetric gas mixture preparation procedure described last year is

capable of making predictable multicomponent gas mixtures with concentrations

of individual components below one ppb, analytical methods for most components

were limited by detection sensitivity and imprecision. This year, considerable

effort has been devoted to developing methods for the gas chromatographic

separation and analysis of multicomponent gaseous organic mixtures where

component concentrations were as low as one ppb. The precision of the GC

analysis procedure has been improved by over a factor of four such that the

individual components of benzene, carbon tetrachloride, vinyl chloride and

tetrachloroethylene now can be analyzed with an uncertainty of less than ±15%

at a few ppb concentrations. Collaborative research with the Organic Analytical Research Division to develop isotope dilution gas chromatographic-mass

spectrometric procedure for similar gas mixtures has been promising. Recent

analysis on gas mixtures analyzed by both methods has given data which agree

within ±20%. Work is continuing on these methods to improve agreement. The

results of these research programs will allow us to obtain analytical data by

two independent methods of analysis for the certification of Standard Reference

Materials containing trace levels of volatile toxic organic materials.

The second area of major research activity has been in trace atmospheric

gas analysis. Initial research to develop analytical methods for HC1 and N2 0

at atmospheric concentrations has been described in past reports. During the

current year, planning meetings have been held with program managers at NASA

and EPA to define needs for trace gas standards and calibration mixtures for

trace atmospheric species. The Importance of accurate analytical methods and

standards for these gases is underscored by the fact that NASA alone is

spending more than $50 million this year in tropospheric and stratospheric

trace gas research and measurements. Currently, no accurate calibration gases

or standards exist to put these measurements on a common scale.

197
As a result of our planning, the Division has initiated a research

program to develop analytical methods with the sensitivity and selectivity

to allow accurate analysis of specific atmospheric species below 1 ppb.

Concurrent with this effort, studies on methods of preparing stable gas

mixtures at these levels has been initiated. Initial analytical research has

focused on diode-laser absorption photometry and electron capture gas chromatography. This year, a technique has been developed for the measurement of

gaseous HC1 below one ppb using direct diode laser absorption. This technique

has proven to be more than ten times more sensitive than the technique

developed using photothermal detection discussed in last year's report. Also,

a new method has been completed for the analysis of N2 0 at atmospheric levels

using gas chromatography with electron capture detection. This method is the

result of two years research and now allows for the analysis of N2 0 with a precision of ±0.1 percent in binary gas mixture standards and ±0.3 percent

precision in atmospheric air. The method is a major improvement over currently used procedures and is being applied to the certification

analyses of a new series of atmospheric gas SRM's.

Other significant accomplishments of the past year include: The

completion of the ozone ultraviolet absorption cross-section values at

four atmospheric temperatures; the development of a model which elucidates

a mechanism for the loss of nitrous oxide in compressed gas cylinders; the

ultratrace detection of N02 in air by photothermal spectroscopy; and the

completion of absolute band strength measurements on seven vibrational band

systems in Freon-11 and 12.

In the Microanalysis Research Group and the X-Ray Fluorescence Group,

this year's programs have focused on improved first-principal quantitation

methods and on elemental, isotopic, and molecular compositional mapping.

During 1983, research on combined analyses using the Analytical Electron

Microscope (AEM) and the Laser Microprobe Mass Analyzer (LAMMA) has led to the

first complete compositional mapping of particles smaller than one micrometer

in diameter. Compositional maps of heterogeneous single particles and aggregates of submicrometer particles contained information on morphology and major,

trace, and isotopic composition of elements of interest. Such complete

analysis of particles allows information to be derived on particle origin and,

to some degree, atmospheric transformation. A second area where substantial

progress has been made is in automated data transfer and analysis of chemical

or isotopic images. A procedure had been developed and tested to transfer

digital image information to a dedicated computer for identification and

quantitative data analysis. A prime concern of this research has been the

retention of analytical accuracy and precision during the image processing.

Other important accomplishments include: development of new thin film glass

standards for AEM and LAMMA calibration; research into improved accuracy and

precision of isotopic ratio analysis by LAMMA and Secondary Ion Mass Spectrometry (SIMS); the first automated digital chemical image transfer; and

completion of a new XRF quantitation algorithm for the calculation of the

spectral output distribution of x-ray tubes.

Future research in gas analytical chemistry has been reviewed this year.

A new long-range research plan has been developed combining research objectives

in gas analytical chemistry and atmospheric chemistry. Research in the

accurate measurement of trace and ultra trace atmospheric constituents is the

198
lead component of the plan. Initial efforts will concentrate on laser absorption photometry, improved multicomponent methods using gas chromotography

and collaborative research in both inorganic and organic isotope dilution gas mass spectrometry coupled with the research into methods of preparing stable

gas mixtures containing trace constituents.

Future research in microanalysis is primarily defined by the third year

portion of the Compositional Mapping research plan. Automated two-dimensional

chemical images will be processed using new dedicated digital imaging systems

on both the SIMS and AEM systems. Methods to insure quantitative information

retention will be developed and tested. Research on quantitative sub-micrometer

analysis of both thin samples and particles will be continued. Finally, a new base-funded program in chemometrics and chemical information optimization will

be initiated.

1 . Microanalysis Research Group: Overview

The Microanalysis Research Group carries out research to advance the

development and application of microbeam analysis techniques for the chemical,

crystallographic, and morphological characterization of matter on the micrometer

and sub-micrometer spatial scale. The analytical techniques utilized are based

on primary (excitation) particle beams of electrons, ions, or photons, and

secondary (analytical) signals of x-rays, inelastically scattered electrons,

inelastically scattered photons, and ions. The techniques include electron

microprobe analysis, scanning electron microscopy, electron energy loss

spectrometry, secondary ion mass spectrometry, laser micro-Raman spectrometry,

and laser microprobe mass analysis. Research is conducted on several aspects

of each technique, including (1) advancing understanding of the basic physics

of sample excitation and attenuation of the secondary radiation; (2) developing

methods of quantitation; (3) producing standards and techniques as a means of

disseminating developments; and (4) applying results of the research to developing improved compositional mapping techniques and to the study of specific

analytical problems in aid of NBS and other government agency activities.

In the area of microanalysis standards, a major standard was issued in

FY83 representing the culmination of intensive research into the characterization of asbestos by microscopy. SRM 1876, Chrysotile Asbestos Fibers,

represents the first available asbestos material for which the fiber loading

has been adequately characterized to serve as a test for counter accuracy.

Research has also continued in our program of developing glass standards for

microanalysis. A new series of bulk glass standards is nearing completion.

Thin film glass standards for analytical electron microscopy and laser

microprobe mass analysis have been tested for homogeneity and resistance to

degradation under electron bombardment. It is our objective to establish

these films as SRM's in FY84 or FY85 depending on OSRM funding.

Several members of the group have continued to work intensively in the

development of sequential analytical electron microscopy/laser microprobe mass analysis for the elemental and isotopic analysis of single particles. Particular emphasis has been placed on the development of thin films to serve as support structures for particles while contributing minimal spectral interferences.

199
Combined secondary ion mass spectrometry (SIMS)/neutron depth profiling

(NDP) studies have been carried out on a series of samples, including candidate

materials for a new SRM boron-in-silicon depth profiling standard. This work

was a joint effort with Division 551 and is advantageous to the development

and quantitation of both techniques, since SIMS offers lateral spatial resolution and sensitivity while NDP provides a depth profile with minimal sample

disruption.

Studies of the accuracy and precision of isotopic ratio analysis by laser

microprobe mass analysis have been carried out. The detector response has

been examined in detail, and the limitations imposed by the non-linear response

of the detector/transient recorder have been more fully characterized.

Research plans for 1984 include activities in each of the major techniques. In secondary ion mass spectrometry, quantitative compositional

imaging will be explored, and limits to accurate isotopic ratio measurements

will be established. In laser Raman microanalysis, the performance of multichannel detection systems is under study. In analytical electron microscopy,

the measurement of the composition of entrained particles will be considered

by a combination of experiment and Monte Carlo simulation. In laser microprobe

mass analysis, interelement effects and sensitivity factor variations will be

studied by means of sputtered glass films. Combinations of several of these

techniques will enable us to create compositional maps with improved accuracy

and utility.

Plans to upgrade selected microbeam instruments are progressing. The ion

microscope will be augmented with a primary mass filter which will allow

selection of the primary ion species. A dedicated digital imaging system will

be attached to the ion microscope in FY84. A digital imaging system is also

being developed for the analytical electron microscope which will make use of

the VAX computer and the DeAnza image processor. The transient recorder on the LAMMA will be upgraded to provide better dynamic range and mass storage,

which should improve the precision of the isotopic measurements as well as providing full spectral coverage on each laser shot.

Dale E. Newbury, Group Leader; Adville A. Bell, David S. Bright, R. G. Downing,

Edgar S. Etz, Ryna B. Marinenko, Robert L. Myklebust, Patrick J. Sheridan,

David S. Simons, John A. Small, Brian R. Stallard, Eric B. Steel,

Barbara B. Thorne.

2. X-ray Fluorescence Group: Overview

The X-ray Fluorescence Group performs research on improved techniques for

sample preparation to increase the analytical sensitivity; and fundamental

parameter data reduction methods to increase the accuracy of quantitative

analysis of the elemental composition of thin and bulk samples. A major

portion of our work also consists of the quantitative analysis and homogeneity

testing of new, and renewal SRM's using a high performance automated

wavelength-dispersive spectrometer.

This year several important accomplishments have been achieved. First,

the development of an NBS algorithm for the calculation of the spectral output

200
distribution of x-ray tubes has been completed. A research paper on this work

has been presented at the 23rd International Spectroscopy Congress in

Amsterdam, the Netherlands and has been submitted for publication in "X-ray

Spectrometry". We are now working to incorporate this algorithm in an NBS

fundamental parameters computer program for quantitative x-ray fluorescence

analysis. Related to the development of fundamental parameter methods, we have assessed the relative accuracy of a new theoretical a-coefficient model

proposed by LaChance [1] using a number of samples of different types such as alloys, pressed powders, and fused oxide minerals.

We have completed our fabrication of two sets of thin glass films to serve as SRM x-ray spectrometer standards. Of major importance in this work

was the design and manufacture at NBS of a planetary substrate stage especially adapted for the ion sputtering instrument. This modification allowed a uniform deposition of glass in which the elemental composition was homogeneous

across the film diameter. The new planetary stage is especially important for

fabricating high quality thin films of different elemental composition for

future SRM's.

Finally, several kinds of samples such as steel alloys, phosphate ores,

borosilicate glass, brass alloys, and over four hundred austenite samples were

measured for either elemental homogeneity and/or quantitative analysis.

Plans for activities of the X-ray Fluorescence group for FY84 will

include: (1) continued development of our fundamental parameter approach to

x-ray analysis; (2) completion of a data reduction computer program which will

incorporate the NBS algorithm together with the calculation of theoretical

a-coefficients for performing quantitative x-ray analysis; (3) final certification of thin film glass standards for x-ray calibration; (4) performance

testing of the new PW1400 automated wavelength-dispersive spectrometer; and

(5) research in preconcentration technology with various cation and anion

specific substrates.

Reference

[1] LaChance, 6. R., Cloisse, F. , Adv . X-ray Anal . , 23 , 87 (1980).

Peter A. Pella, Group Leader; Anthony A. Marlow, John R. Sieber,

Gerald SI eater.

3. Atmospheric Chemistry Research Group: Overview

The Atmospheric Chemistry Research Group conducts research on measurement

techniques for ambient concentrations of atmospheric species in both the gas

and particle (liquid and solid) phases. This research includes the development

of sampling/collection techniques, in situ analytical methods, and micro-sample

preparation and analysis techniques. A primary objective of this research is

the extension of existing techniques and the development of new analytical

techniques for the detection and characterization of trace and ultratrace

level atmospheric constituents.

201
Research has continued this year in the study and development of spectroscopic techniques for the analysis of trace and reactive atmospheric gases.

The determination of the ozone ultraviolet absorption cross-section values as

a function of temperature has been completed. The values are being used

internationally by the ozone monitoring community although the values have

been distributed as provisional pending final error analysis of the complete

data set. The construction, calibration, and evaluation of performance

parameters of a new standard reference ozone photometer has been completed.

The new instrument now serves as the standard reference photometer at NBS,

as the reference photometer for the EPA ozone monitoring network, and most

recently as the standard for a NASA intercomparison study of various ozone

measurement systems used for stratospheric and tropospheric ozone concentration measurements. Research to develop sensitive reactive gas analytical

techniques has resulted in a technique for the detection of HC1 at the

sub-parts-per-billion level using tunable diode laser absorption. This is the

most sensitive in situ detection method available for this important reactive

atmospheric trace gas. Also, significant progress has been achieved this

year in the application of photothermal spectroscopy for the detection of

trace levels of N02.

Significant achievements have been obtained in the development and

application of mathematical analysis of analytical data sets in evaluation of

detection limit assessment, design and improvement of the analytical measurement process, and in the interpretation of multidimensional data sets. A

primary application of these techniques has been the study of the origins of

carbonaceous aerosols (source apportionment and receptor modeling). Other

applications include: Consultation with DOE in the design and feasibility of source apportionment in the study of the generation and transport of sulfur

emissions suspected to be involved in the formation of acid rain; and research

to define the lower limits of detection of radiological effluent from nuclear

power plant operation.

Accomplishments have been achieved in several areas of particle research

and characterization. The Respirable Quartz SRM has been completed and the

data turned over to the Office of Standard Reference Materials for issuance as

a Standard Reference Material. Studies in collaboration with the Microanalytical Group on the characterization of organic materials adsorbed on surfaces

and particles by Laser Microprobe Mass Analysis (LAMMA) have provided a demonstration of the feasibility of the technique for qualitative analysis of

micrometer and sub-micrometer sized samples. We have also completed studies

on the development and characterization of personal particulate exposure

monitors (PEM's). The NBS sampler has been evaluated in a field study intercomparison which confirmed the performance characteristics obtained by wind

tunnel testing in the laboratory. We also completed a feasibility study on the development of an in-vehicle PEM for use to measure commuter exposure to

lead and specified organic pollutants characteristic of automobile emissions.

The focus of research activities for the next year will include:

a) characterization of sampling and sample transport of material from a bulk

sample by spark discharge; b) continued development and application of

photoacoustic spectroscopic detection techniques for trace and ultratrace

atmospheric gases, including reactive species which must be measured in situ ;

202
c) continued development and application of mathematical analysis and modeling

of data sets, including receptor modeling, source apportionment and detection

limit issues; d) application of carbonaceous aerosol and gas measurement

techniques to the study of polar ice core samples to help determine the

composition of ancient atmospheres; and e) applications of the LAMMA for

analysis of organic and inorganic species on surfaces and particles.

Raymond L. McKenzie, Group Leader; Arnold M. Bass, Robert E. Continetti,

Lloyd A. Currie, Robert A. Fletcher, Alan Fried, Rudy V. Kelly,

George A. Klouda, David A. Krask, James E. Norris, Jeannie Sullivan,

Gerald R. Tompkins.

4. Gas Metrology Research Group: Overview

The Gas Metrology Research Group conducts fundamental and applied research

leading to the improvement of measurement science for ambient and trace gas

analysis, and the development of accurate and reliable standards for a variety

of gaseous species. The latter are developed to provide data quality assurance

in gas measurements made world-wide, and include both non-organic and organic

gaseous species. Basic measurements and research are carried out to ensure

that the gas standards generated are both accurate and stable. Research is

also conducted to improve the scientific understanding of chemical instability

of certain gaseous species. The Group directly responds to and interacts with

gas measurement and standards needs of other agencies, industrial associations,

and standards setting bodies, and provides advice and guidance to the private

sector as appropriate. The Group, utilizing its unique capabilities, also

performs a limited number of gas analyses for external organizations.

Activities and accomplishments during the past year have included: a continuation of trace gas research using Fourier transform infrared spectroscopy

(FTIR) and diode laser systems; completion of the first set of SRM's to provide

data quality assurance in world-wide measurements of long-term changes of

atmospheric C02 levels; assessment of the causes for concentration instability

in NO gas mixtures; the development of low parts-per-billion (ppb) level

organic gas mixtures; and the application of gas analysis to a variety of

other agency programs. A brief description of some of these activities are given below and in the more detailed write-ups of the technical accomplishments

that follow.

The first three ambient concentration level C02 in air SRM's (nominally

330, 340, and 350 ppm) were completed in FY83. These SRM's have estimated

uncertainties less than 0.1% relative, and are now available for calibrations

of world-wide measurements for quantifying long-term trends in increasing

atmospheric levels of C02

. A second set of three SRM's covering the 300-400

ppm range, are now undergoing certification analysis. This second set will

also be certified for ppb levels of N 2 0, and will provide information values

for Freons F- 11 and F-12 in the parts-per-trill ion range. Research on the

characterization of fundamental spectral properties of the Freons using FTIR

has led to publication of absolute band strengths of F-ll and F-12 covering

three vibrational band systems of the former and four of the latter at

203
296 ± 1 K, with a resolution of 0.06 cm" 1 in the "atmospheric window" between

8-16 ym. These results infer a 17% and 5% greater absorbance strength for F-ll

and F-12 than band strengths used in recent greenhouse warming calculations.

Research using FTIR and conventional gas analysis techniques was applied

to the examination of the causes of instability in NO gas mixtures. A terminal

reaction product, nitrous acid (H0N0), predicted from homogeneous gas phase

kinetics, was found at concentrations much lower than predicted, and its trace

presence in both stable and unstable mixtures did not allow for a meaningful

correlation of H0N0 with NO instability. The difficulty in using H0N0 to

quantify NO instability may be complicated by surface sorption in cylinders

and on the glass gas cell used in FTIR analysis. Elevated levels of N02 in NO

mixtures may correlate with NO instability, and further work is continuing to

explore this possibility. Additional studies are planned using mixtures of NO

that have been quantitatively doped with known trace levels of N02 and/or

water vapor using a new flow-through FTIR gas cell to minimize wall effects

during analysis.

In the area of trace organic gas standards, notable progress has been

made in the preparation of multi -component organic mixtures in the low ppb

(5-15 ppb) range. The techniques developed to reliably produce such mixtures

were published during this year. Work is also in progress for the certification of four-component aromatic mixtures of benzene, toluene, chlorobenzene,

and bromobenzene at 0.25 ppm and 9.5 ppm.

Several special studies were undertaken during the course of the past

year involving: a time-course examination of pollutant gas levels in the

National Archives; analyses of toxic gases evolved from lithium batteries,

for the Naval Surface Weapons Center (NSWC); and the analysis of air samples

taken from the Amazon River in Brazil. The Amazon study was a joint effort

with Harvard University, NASA, and the Calypso Society, to assess the concen- trations of selected gas species (CH4 , C02 , N2 0, CO, and freons F-ll and F-12)

in a remote area. Preliminary analyses of the samples taken indicate enrichments of about 4 percent for methane and about 1 percent for N2 0 in the air

above the tropical rain forest surrounding the Amazon River, relative to air

above the Atlantic Ocean.

Future research plans of the Gas Metrology Research Group include:

(1) continued research using FTIR, diode-laser, and GC-electron capture for

detection, analysis, and characterization of trace gas species; (2) continued

analytical research into the causes of instability in reactive gas mixtures

using synthetically-prepared N0-N02 -water vapor mixtures; (3) development of

heats of sorption data associated with the sorption of volatile toxic organics

by sorbents; and (4) the application of electrochemical approaches to the

analysis of reactive gas mixtures containing NO and S02

. A

Walter L. Zielinski, Jr., Group Leader; Barry C. Cadoff, William F. Cuthrell,

William D. Dorko, James W. Elkins, Ernest E. Hughes, Patricia A. Johnson,

Gerald D. Mitchell, Richard D. Myers, George C. Rhoderick, William P. Schmidt,

Gerald A. SI eater, James E. Suddueth.

204
B. Selected Technical Reports

(Gas and Particulate Science Division)

1 . Cross-Coupled Interaction of Thermal, Electrical, Mechanical, and

Chemical Parameters of Polymeric Permeation Devices (15330)

G. D. Mitchell

Although gas permeation tubes have been used empirically to generate

known concentrations of gases in various matrices [1-4], no definitive

investigation to establish the underlying theoretical basis or to determine

the effect of the various parameters on the permeation process has been

undertaken. The interest in gas permeation tubes and biological control

release devices led to a preliminary theoretical evaluation to establish

the relation between selected (external /i nternal ) parameters and the

diffusitivity, solubility and permeability of specific species through

polymeric materials. The parameters of concern are not only the gradient

of the chemical potential of the species, but also such parameters as stress, strain, electric field, polarization, charge, voltage, temperature,

and entropy. Cross-coupled interactions of these parameters, which in

the past have not been studied in relation to polymer permeation, represent

the basis for this evaluation. A comprehensive approach to the complete

characterization of polymeric permeation devices is afforded by a thermodynamic-based theory that explores the cross-coupled relationship between

the permeating species and substrate under the influence of any or all

of the parameters mentioned above.

A dynamic model of cross-coupled interactions of thermal, mechanical,

electrical, and chemical parameters and their effect upon permeation is

being explored. Since permeation and control release devices are binary

systems, consisting of both the polymer substrate and a permeator, and

since the permeation process depends on both kinetic and thermodynamic

properties of the system it is not unexpected to find that gas permeation

through polymeric materials is not entirely related to any one specific

property of either the permeator or the substrate. The Table presented

below depicts the parameters and coefficients that are to be considered,

in addition to the diffusion and solubility characteristics of the

permeation device. Research aimed at improving the understanding of the

limitations and role of these parameters in relationship to permeation

devices is continuing.

References

[1] A. E. O'Keefe and G. C. Ortman, Anal, Chem. 38, 760 (1966).

[2] A. E. O'Keefe and G. C. Ortman, Anal, Chem. 39^, 1047 (1967).

[3] M. D. Thomas and K. E. Amtower, J. Air Pollut. Contr. Assoc.

16, 623 (1966).

[4] L. A. Elfey and C. E. Decker, Anal. Chem. 40, 1959 (1968).

205
Table 33. Definitions of the Coefficients Representing the

Principal and Coupled Parameters.

Converse Converse Thermal

Elasticity Piezoelectricity Piezogalvanic Expansion

3e 3e 3e 3e

03 Q

mQ

9E

oqT

^

aET

9T

aEqFn

Dielectric Geometric

Piezoelectricity Susceptibility Parameter Pyroelectricity

3P 3P_ 3 P 3 P 30

EqT

9E

aqT 9q aET

9T Fn aEq

Piezogalvanic Geometric Thermogalvanic

Effect Parameter Capacitance Coefficient

3 V 3V 3 V 3 V

90

EqT

3E nT aqT 9 « aET

9T Fn aEq

Piezocaloric Electrocaloric Galvanocaloric Thermal

Effect Effect Effect Capacity

3S as 3S 3S

90

EqT

3E

aqTnT 8 « aET

9T Fn aEq

o

- Stress q

- Charge

e

- Strain V - Voltage

E

- Electric Field T - Temperature

P

- Polarization S - Entropy

2. Band Strength Measurements of Propane by Fourier Transform Infrared

Spectroscopy (15330)

G. C. Rhoderick, J. W. Elkins

The infrared properties of propane have received considerable attention

in atmospheric science because of the role of propane in the tropospheric

chemistry of polluted urban environments. Interest has also extended into

planetary astrophysics, since the positive identification of propane in the

atmospheres of Saturn and its largest satellite. Titan, by the Voyager 1 spaceprobe's FTIR spectrometer [1]. Accurate measurement of the band strengths

(S

y

) permit determination of concentration values from recorded spectra. We

have re-examined these values at a higher resolution (0.06 cm" 1

) with a FTIR

spectrometer to improve the accuracy of spectroscopic analysis techniques for

propane.

206
Figure 43 shows a representative Beer's law plot, the integrated

absorbance versus pressure-pathlength product, for the v!(v 2 ) and v 3 bands of

propane. Standards prepared by gravimetry and by pressure measurements were

used to fill a 5- and 10-cm cell to one atmosphere. The integrated absorbance

was measured also from a 5-cm cell containing 0.25 percent propane in nitrogen

from SRM 2647. The data from the SRM, pressure and gravimetric standards fall on the same line. Therefore, the pressure and gravimetric methods produce

equivalent standards under the conditions of the experiment. The plot also

demonstrates that the FTIR is a valuable tool in the verification of concentration values for SRM's.

0 10 20 30

1 i i i * i i * i i i

i i i 1 i* 0 12 3 4

(kPa • cm)

PRESSURE-PATHLENGTH PRODUCT (p i) Figure 43. Beer's law plots with band strengths (slope of line) for the

vi[v2 ) and v 3 bands. The standard deviation of the least

squares determination of the slope is the value in parenthesis.

The slope of the line in figure 43 is equal to the band strength.

Table 34 shows previous measurements together with our measurements of the

major band systems of propane between 700 and 4400 cm"1

, corrected to 296 K. The previous results of Stalmakhova et al. [2] and Kondo and Saeki [3] were

obtained using conventional spectrometers at 2 and 1 cm” 1 resolution,

respectively. Band assignments in parentheses indicate that the band system

has coincidental overlapping of bands from different vibrational states.

Many of the infrared bands of propane are merged together and require deconvolution to separate individual band strengths from interfering bands. The

207
C

3

H

8

Table 34. Band Strengths for Propane (C^Hg).

Band Strengths at 296Ka

S

v

( 296 ) cm"

2

atm”

1

Band Observed Stalmakhova Kondo Present

System Band

Center

(cm"

1

)

et al

(1965)

Ref. 2

b

and Saeki

(1972)

Ref. 3

b

Work

V

21

748 9.92 9.05(1.03) 9.97(0.32)

v 8

869 2.32 2.26(0.70) 2.04(0.13)'

v 16

922 6.12 4.69(0.66) 4.57(0.17)'

V

1

1054 4.38 4.07(0.45) 3.26(0.15)

CM a

;> 1170 5.21 5.10(0.62) 3.89(0.13)

v 141338 9.92 10.3(2.9) 7.56(0.30)' v

6

(v 13 ) 1378 26.5 24.3(3.7) 23.8(0.8)°

v

4

(v

5

) 1476 70.3 70.8(7.4) 75.1 (2.4)°

v

3 2887 372 218(43) 188(7)°

CM 2977 554 736(59) 748(24)

c

v

l +v 22

3175 — — 9.91(0.36)

V i+Vg 3335 — — 1.49(0.05)

4150 — — 13.0(0.5)

4300 — — 17.9(0.6)

v8(v 16

)d 8.44 6.95 6.61(0.22)

v4(v

5

)(u

6

)

. (vi 3 )(vi 4

)

106.7 105.4 106.6(3.4)

Vi (v

2

) (v

3

) d 926 954 936(30)

Uncertainties for band strengths in the last digits are given In parentheses.

The uncertainties for previous work are reported values, whereas the uncer- tainties in the present work include both reproducibility errors and possible

systematic errors (see text).

bAuthors in ref. 1 reported values in 10" 8 cn^s^mol"1 with uncertainties of

5-10%, and in ref. 2 reported in L mol” 1 cm"2

. Measurements of these bands obtained by deconvolution.

dValues from ref. 1 and 2 are the sum of the individual band strengths. The

values from the present work are measurements made from baseline to baseline.

208
largest disagreement between our results and previous measurements exist for

these interfering bands. This discrepancy can be explained as the inability

to define precise upper and lower bounds of an individual band in a merged

continuum of numerous bands (errors in deconvolution), since the total band

system strengths of the interfering bands agree to within a few percent

between laboratories (see last three lines in Table 34).

Estimates of our uncertainties (reported as one standard deviation) given

in Table 34 were obtained by adding in quadrature three major possible sources

of error: pressure-pathlength product (pi) errors (±0,7 RSD, relative standard

deviation), reproducibility in the least squares determination of the slope of

the Beer's law plot (i.e. standard deviation shown in figure 43), and a possible systematic error. A systematic error of ±3 percent (RSD) was estimated

by comparing our FTIR results of other infrared absorbing molecules against

accurate high resolution infrared measurement by other researchers. We

believe our band strengths of propane are reliable, because of the higher

resolution of our measurements compared to other studies and the care we took

to avoid possible errors.

References

[1] Maguire, W. A., R. A. Hanel , D. E. Jennings, V. G. Kunde,

and R. E. Samuel son. Nature, 292, 683-686, (1981).

[2] Stalmakhova, A. G. Finkel and L. M. Sverdlov, Optika I Spektroskopia,

18, 1083-1086, (1965).

[3] Kondo and Saeki , Spectrochim. Acta, 29A, 735-751, (1972).

3. Sampling and Measurement of Nitrous Oxide, Carbon Dioxide, and Methane in

the Amazon (15330)

J. Elkins

Increased levels of certain trace gases in the atmosphere, (such as carbon

dioxide (C02 ), methane (CH4 ), and nitrous oxide (N2 0) may increase the surface

temperature of the earth [1] and may also influence the equilibrium concentration of stratospheric ozone [2]. The sources and sinks of these gases are primarily biological [3], together with significant anthropogenic sources.

Global climatic models predict enhanced concentration levels of these gases

in the atmosphere over biologically active areas, such as the Amazon river

basin. Few reliable measurements of trace gases are reported in the literature

for such a remote global region.

A unique research opportunity was offered by the Cousteau Society when

scientists from NBS and Harvard University were invited to sail with the

research vessel, R/V Calypso, during the Amazon Expedition in December 1982.

The Amazon estuary is important because the waterway provides about 20 percent

of the total fresh water source to the world's oceans. Our research was co-sponsored by the National Aeronautics and Space Administration (NASA) and

the Cousteau Society in order to sample both the air and water ecosystems for

209
analysis of trace gaseous species from this large river system. Water and air

samples were collected at Manaus and aboard the R/V Calypso. Duplicate air

samples were returned to NBS and Harvard University for analysis.

Figure 44 shows the cruise track of the R/V Calypso in December 1982 during

the course of the expedition from Belem, Brazil at the mouth of the Amazon to

the Caribbean island of Martinique. Station locations are marked on the

figure. The interior stations (Sta. 1 & 2) at Manaus, Brazil were sampled

before boarding the Calypso. December is typically the "dry season" in the

Amazon river basin and a period of low river flow. The source of the air mass over the Amazon basin are the "Trade winds", generally blowing in from either

the northeast or the southeast.

Figure 44.

210
The most interesting results from the expedition were the differences in

the atmospheric concentrations of these trace gases for the interior and

coastal stations of the Amazon basin. Table 35 shows the average, standard

deviation, and number of measurements for the concentrations of each trace gas

at the stations indicated in figure 44. The observed differences in concentration between the interior and coastal Amazon stations for each gas were

calculated along with the uncertainties of the differences at the 95 percent

confidence level. Identical samples from the same location were measured

independently by different analytical methods at both NBS and Harvard University

(Professors McElroy and Wofsy). The agreement in Ac values between laboratories reported in the last two rows of Table 35 was excellent. The results

show a statistically significant enrichment of about 3 percent and 1.5 percent

for CH4 and N2 0, respectively, in the air above the interior station at Manaus

over the air above the stations off the coast of Brazil. This enrichment of

CH4 and N2 0 confirmed calculations from global climatic models developed at

Harvard University and Goddard Institute for Space Studies. The concentration

for carbon dioxide at the interior stations ranged from 338 to 419 ppm (partsper-million), indicating large and variable sources of C02 near the ground

of the forest.

The measurements reported here are limited in scope and reflect only

results from the "dry season". We have recently collected additional samples

from more locations around Brazil during the "wet season" and those samples

are currently being analyzed.

References

[1] Chamberlain, J. W. , H. M. Foley, G. J. MacDonald, and M. A. Ruderman,

in Carbon Dioxide Review: 1982, ed. by W. C. Clark, Oxford

University Press: New York, 255-277, (1982).

[2] McElroy, M. B. , J. W. Elkins, S. C. Wofsy, and Y. L. Yung,

Rev. Geophys. Space Sci., 14, 143-150, (1976).

[3] Elkins, J. W. , S. C. Wofsy, M. B. McElroy, C. E. Kolb, and

W. A. Kaplan, Nature, 275, 602-606, (1978).

211
Table 35. Results 0 for Methane, Carbon Dioxide, and Nitrous Oxide During

Amazon Expedition, December 1982.

SITE CH

4

CONC. (ppm) C0

2 CONC.(ppm) N2

0 CONC.(ppb)

STA #1 2

MANAUS* 1.684 ± 0.015 (11) 371.0 ± 23 (11) 307.2 ± 3.3 (10)

DEC 8,9

a

STA #3 4

COAST ’ a 1.637 ± 0.013 (9) 344.6 ± 5.1 (9) 302.4 ± 1.4 (7)

DEC 10,1

a

STA #5

OCEAN

8°N

DEC 1

a 1.658 ± 0.008 (5) 345.5 ± 4.2 (5) 302.5 ± 1.5 (4)

STA #6

OCEAN

1 2°N 1.652 ± 0.015 (6) 343.0 ± 0.9 (5) 302.2 ± 0.7 (6)

DEC 1

a

MANAUS-COAST (ac)

NBS

AC h

95% CI

D 0.047 ± 0.011 26.4 ± 12.6 4.8 ± 2.1

HARVARD

AC , 95% CI

D 0.042 ± 0.019 19.2 ± 21.1 4.0 ± 2.8

a Values reported as average ± standard deviation. Value in parentheses is

number of measurements (ppm= parts-per-million, and ppb= parts-per-bil 1 ion)

b Uncertainties are based on the t-test and reflect the 95% confidence

interval (Cl).

C

A11 ± values represent one standard deviation except those for Manaus-Coast

(95% Cl (two standard deviations)).

212
4. Stability Studies of NO in N? SRM's (15330)

B. C. Cadoff

While SRM gas mixtures are widely recognized standards due to their

concentration accuracy and stability, occasionally cylinders are not certified

because of an observed instability. Generally, it is the more reactive gas

species (such as NO and S02 ) that are more prone to show instability, which,

although over a period of time may be relatively small (e.g., 1-2 percent

concentration degradation), is still unacceptable. The current research

program has the long range objective of identifying the causes of instability

and proposing ways of improving stability. The program has initially been

focused on examining the instability of NO in N2 gas mixtures.

The first approach was to assess the effects of homogeneous gas phase

reactions. For this study, a total of 15 cylinders were examined which had

been prepared as SRM 1687a, at a nominal concentration of 1000 ppm NO in N 2. Most of the cylinders had shown small losses of NO between the initial analysis

and a second analysis some 18 months later. The approach to this study

involved both collection of analytical data on species present and consideration of the gas phase chemical reactions that can occur, along with the

associated rate and equilibrium constants.

The presence of impurity gases in compressed gas mixtures has always been

a concern; however, any cause and effect pattern on composition instability

due to these impurities has been, at best, ambiguous. For example, it has

been postulated that water vapor may play a role in the loss of some species

such as NO. However, it has been observed that some stable cylinders contain

higher concentrations of H2 0 than other unstable cylinders.

The reactions that havfe been reported to occur in the gas phase involving

NO, N02 , H2 0 and 02 are few ill number and are as follows:

2N0 + 0

2

2N0

2 (1)

2N0

2

N 2°4 (2)

NO + N0

2

N 2°3 (3)

n

2 o

3 + h

2 o 2H0N0 (4)

3N0

2 + H2

0 2HN0

3 + NO (5)

Reaction (1) is a rather fast reaction which has been well studied and for

which the rate constant is reliable. The reaction goes to completion with no reverse reaction at room temperature. When representative values for NO and

02 [955 ppm NO, 7 ppm 02 , 13.78 MPa (2000 psi)] are substituted in the rate

equation, calculation indicates that the reaction is more than 99.9 percent

completed in 10 minutes. In fact, even at concentrations of 50 ppm NO, trace

02 is converted to N02 in approximately one hour. Hence, any trace oxygen

that may be present during the preparation of a cylinder is rapidly converted

to N02

.

213
Reaction (5) can be excluded from consideration since recent studies have

shown that, in the presence of a high concentration of NO relative to N02 , no detectable reaction between N02 and H 2 0 takes place. Therefore, the gas phase

reactions that can lead to a slow degradation of an N0-in-N2 mixture are reactions (2), (3) and (4). [In a totally dry system equations (2) and (3)

would govern.] These reactions are relatively slow, and produce (at equilibrium)

HONO as the predominant product. Earlier in this project, a computer-based

kinetics program was used to model the case of 100 ppm NO, with N02 and H2 0

present. It was found that NO would degrade slowly, over a period of months

or years. The problem with this calculation was that there is no reliable

rate constant for equation (4) -literature values varied by a factor of 100.

However, the situation with respect to equilibrium constants is much better

(with errors in the range of about 5%) and an equilibrium model was finally

used to compare and assess the chemical analysis of these cylinders.

Analytical data were obtained as follows: NO - chemiluminescent detector;

H2 0 — electrolytic analyzer; all other species — FTIR using a 100 meter cell.

Table 36 lists the analytical results for these cylinders. Percentages at the

top of the columns are estimates of uncertainties. These cylinders are now three years old and have been analyzed for NO on three occasions, approximately

18 months apart.- Two cylinders have exhibited no change (41-2-C and 41-3-C);

the other 13 cylinders have undergone changes as large as 1.9 percent. However, with the exception of 41 -51 -C , every cylinder has been stable from the

second to the third analysis. Referring to equations (2), (3) and (4) and

calculating the concentrations at equilibrium, we find that, for the case of

NO = 955 ppm, N02 = 14 ppm and H2 0 = 20 ppm, all at 2000 psi , the products of

reaction would be 6 ppm HONO and 0.8 ppm N 2 03 , with trace amounts of N2 04

. As seen from Table 36, HONO is present in only trace amounts (less than 1 ppm),

and N 2 03 is not detectable. If we make the assumption that HONO is lost to

the walls of the cylinder, this reaction would result in a 1.5 percent loss of

NO, a representative loss as seen from Table 36. Thus, we can explain the

loss of NO as resulting from gas phase reactions and subsequent loss to the

walls, or in other words, a gas phase titration reaction. Of course, this is

not a proof but rather a plausible explanation. In this connection it is

interesting to note that the cylinders that did not undergo change between the

second and third analysis all had only trace levels of N02

. The one cylinder

that did change had a very high level of N02 (25 ppm).

The mechanism of degradation which has been postulated requires that N02 be present. The experimental results are in accord with this mechanism since

stable cylinders, and cylinders which have previously undergone changes but

which are now stable, contain only trace levels of N02 , far below the amount

necessary to cause a detectable change in the NO concentrations. The one cylinder which has continued to degrade contains a large concentration of N02

. The expected products of reaction, N 2 03 and HONO, are either absent (in the case of N2 03 ) or present in extremely low concentrations (in the case of HONO)

indicating that one or both products are lost to the walls.

The now-stable cylinders will be reexamined after several months to

redetermine NO content. It is expected that no further change will take place

since only trace levels of N02 are present. A key set of experiments are planned in which we will fill cylinders with suitable levels of NO, N02 and

214
Table

36.

Analytical

Data

for

Cylinders,

Concentrations

in

ppm.

CM Oo

oCM

CM O

OCM

o o LO in o in in LO in o o LO LO LO

as LO CO at CO CO at in rx o r— o 00 CO o o o CM CM CO c— CM in at <o CO

• • • +1 o O o o o o o o o o o o o o

in to LO o o in o o o o LO o o LO o as r— CNJ rx LO co LO co LO cn LO

+1 CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM

O O o O o O O O o o as <u 4> at a CM o <3- o 00 0J r— LO o (U o c C r— c CO CM CM CM r— c CO CO CO CM C

CO o o • o • • • • • o • • • • o

+1 z z o z o o O o o z o o o o z

o o LO LO in o in o LO LO o o o o as 00 o 00 CO r— LO at 00 at r^. o o CM co CM CM <3- r— CM co in CM LO CM r— o co

+i O o O O o o © o o O o o o o LOCM

LO LO LO O O o o in o o O o o o o LO r—

+1 LO LO o LO r^. r>* co CO LO VO LO LO r— LO

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215

(-

0

. 95

%)

(-

1

. 9

%)

±

10%
H2 0 and determine the resulting component concentration changes. A more

detailed kinetic study can also be conducted in which varying levels of the

reactants are studied.

The NO, N02 , H2 0 system might also be used to assess the inertness of a particular cylinder (or a particular treatment for a cylinder) by determining

whether the concentrations of species agree with those predicted by considering

the appropriate equilibrium constants.

5. Evaluation of Degree of Sorption in Collection of Trace-Organic Vapors

on Sorbents (15330)

6. Sleater, W. L. Zielinski, Jr., G. A. Ulma, Jr.

Sorbents have been widely used in the past decade for the evaluation of

air pollution and of personal exposures in industrial environments due to

volatile organic compounds of known or suspected human health hazards. The

sorbed organics are typically measured by desorption from the sorbent using

either solvent extraction or thermal means, followed by chromatographic analysis. Several significant activities relative to the importance of developing

standardized, reliable, data concerning air pollutant levels and worker

exposures, include: NBS ' development of a set of SRM's containing quantified

levels of specific organics sorbed on charcoal; EPA's proposed gas saturation

procedure, based on sorbent collection of organic vapors for organic vapor

pressure measurements (q.v.); and NIOSH's development of an analytical method

(No. P&CAM 127), based on sorption on charcoal followed by desorption with

carbon disulfide.

It was determined by NBS and others that attempts of quantitative recovery

of sorbed organics from the substrate introduced the greatest uncertainty in

estimations of the levels of trace organics in air. To address this, a series

of experiments were initiated during the past year, aimed at improving the

understanding of the behavior of the sorption-desorption process. Three

different sorbents were selected for study: coconut charcoal, Tenax, and a carbopack-like material.

Three types of experiments were designed with the objective of:

(1) comparing sorbent capacities; (2) developing heat of sorption data for

various volatile organics; and (3) testing the efficacy of employing heat of

sorption values for selecting optimum desorbing solvents.

Weighed samples of the sorbents were incubated at room temperature in

desiccators containing vapors of specific organics to compare their relative

sorptive capacities. Preliminary experiments using toluene as the test vapor

indicated that charcoal sorbed about 4-fold the amount of toluene sorbed by

Tenax (weight increase of 38.3% versus 9.97%). In a more defined desiccator

study, sorbent capacities for acetone and benzene were examined for all three

sorbents studied, with the following results:

216
% Weight Increase

Acetone Benzene

Charcoal 28.44

Tenax 0.34

Carbopack 0.26

28.47

5.02

0.24

Hence, sorbent capacities vary dramatically. Charcoal may have too great

a sorptive capacity, engendering incomplete desorption prospects, while

carbopack appears to have low sorbent qualities of little utility.

In a separate set of experiments, heats of sorption of various organic

vapors were measured. The experimental design involved sampling the head-space

vapor of an organic compound and measurement of retention data on a gas

chromatographic column packed with the sorbent at 4-6 temperatures. The use of a charcoal GC column afforded very limited retention data due to the high

capacity (sorption affinity) of charcoal. However, analyses on Tenax were

successful. The heats (aH ) were calculated from the relationship

aInv' = -AH /RT + C

i a where \l' is the corrected retention volume at column temperature T in degrees

Kelvin, and R is the gas constant, 1.987 cal /mol -degree. Linear regression

analysis of ln\T vs 1/T gave the following sorption heats on Tenax:

Correlation

aH_ (kcal/mole) Coefficient

a 2-Nitrophenol 19.01 0.9993

Benzene 14.01 0.9998

Chloroform 13.01 0.9998

Ether 12.68 0.9983

Acetone 11.56 0.9997

Carbon Disulfide 10.17 0.9997

These results are consistent with the capacity measurements of benzene

and acetone on Tenax, given above. It is interesting that carbon disulfide,

commonly used as a desorbing solvent, does not appear to be an optimum choice

because of its lower heat of sorption. Solvent desorption experiments from

desiccator experiments are currently in progress to test the consistency of

desorption recovery data with heats of sorption data.

217
6. Round-Robin Assessment of Gas Saturation Test Method Proposed by EPA for

Generating Vapor Pressure Data on Organic Chemicals (15330)

W. L. Zielinski, Jr, K. R. Eberhardt (714)

A round-robin study was conducted to evaluate a test standard proposed by

EPA [1] for the determination of near-ambient vapor pressures of pure organic

compounds. The study was coordinated by NBS, supported by the EPA Office of

Pesticides and Toxic Substances, and involved an analytical evaluation by eight

private testing laboratories, a university laboratory, and the Gas & Particulate

Science and Organic Analytical Research Divisions of CAC. Statistical evaluations of the data obtained were performed in the Statistical Engineering

Division of the NBS Center for Applied Mathematics.

The test method is based upon the gas saturation technique in which the

carrier gas flows through the test compound compartment and then through a two-stage adsorbent trap. In this technique the flow system is housed in a constant temperature box and the effluent flow rate is monitored over the time

course of the experiment. Following the experiment, the adsorbent trap is

demounted, and the level of sorbed test compound is determined by solvent

extraction of the sorbent and quantitative analysis (using gas chromatography

or another appropriate technique). Desorption efficiency is determined

separately from sorbent spiked with the test compound, to correct for that

fraction of compound not desorbed by the extracting solvent.

The private laboratories examined 10 test compounds, comprised of either

solids or liquids, covering a nominal vapor pressure range of 102 -10" 5 Pa

(about 10°-10' 7 torr). The university laboratory examined two of the test

compounds to test the adaptability of the proposed test standard in the hands

of capable, but inexperienced operators. NBS performed an evaluation of the

experimental assembly and the proposed test standard per se to develop guidance

information for the round-robin, and evaluated six of the test compounds in an independently developed alternate procedure [2] for vapor pressure measurements

using either cryogenic trapping or sorption on C-18 reversed-phase particles,

followed by HPLC analysis. The data obtained by the latter procedure were highly precise, consistent with reliable literature data, and were used as reference values in the statistical evaluation of the round-robin data.

Vapor pressure values (p, in Pascals) were calculated from the

experimental results using the expression:

p = wRT/Mv

where w is the total sorbed mass of a test compound of molecular weight M, v is the total volume (m3

) passing through the system during the duration of the

experiment, T is the experimental temperature in Kelvin, and R is the gas

constant (8.31 Pa-m3 /mol-deg) . The round-robin data received from the eight

private testing laboratories for the 10 test compounds were subjected to

statistical analysis. A summary of this analysis is given in Table 37. This

numerical summary follows the format given in ANSI/ASTM E 691-79, "Standard

Practice for Conducting an Interlaboratory Test Program to Determine the

Precision of Test Methods." In Table 37, column (2) lists the mean of the

218
Table

37.

Numerical

Summary

for

Vapor

Pressure

Round-Robin.

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<L> Q.

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«— CM

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LU ^ (

0

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219

Mean

vapor

pressure

in

Pa

except

where

specified

otherwise.

Reference

[2].
laboratory means at a given temperature for a given test compound. Column (3)

is the "repeatability" standard deviation (S

r

) of three replicate analyses for

a compound by a test laboratory, pooled across all laboratories (with S

r expressed as a percent of the mean in parenthesis). The standard deviation (S

in column (4) estimates the between-lab component of variation from a random-effects model one-way analysis of variance, and represents the variability due strictly to between-lab differences after the within-lab variabili

is accounted for. The "reproducibility" standard deviation (S

R

) in column (5)

combines the within-lab and between-lab standard deviations, and represents

the typical variability between individual results obtained by two different

laboratories analyzing one sample each using the proposed test method (the

coefficient of variation for reproducibility, representing S

R as a percent of

the mean, is given in parenthesis). Reference values for several of the

test compounds are given in column (6).

The most notable observations of this round-robin evaluation of the

proposed test method were that: (1) the within-lab precision was typically

significantly less than the between-lab precision, pointing out the need for a more explicit description of the test method to minimize individual interpreta

tions in using the test method; (2) the laboratories most experienced in using

the test method gave the most precise, but not always the most accurate

results; (3) the greatest uncertainty in obtaining results using the test

method was contributed by the imprecision in the desorption efficiency

determination and the use of this determination for correcting for the amount

of test compound not desorbed by the extraction solvent in the actual vapor

pressure experiments (especially When using charcoal as the sorbent); and,

finally, (4) the precision and accuracy in vapor pressure measurement by the

gas saturation technique are much improved when a sorbent is excluded (e.g.,

using cryogenic trapping).

A final report of this round-robin, including all test data and their

statistical evaluation has been submitted to the EPA Office of Pesticides

and Toxic Substances.

References

[1] Federal Register, Vol . 45, No. 227, pp. 77345-77350.

[2] Sonnefeld, W. , Zoller, W., and May, W. , Anal. Chem. , 55, 275

(1983).

220
7. Development of Techniques for Preparation and Analysis of ppb Level

Toxic Organic Standards (15330)

W. P. Schmidt, W. F. Cuthrell

Previous work in this long-range research program for the development

of reliable, stable gas standards of toxic, volatile organic species has led

to the development of benzene and tetrachloroethylene gas cylinder SRM's, each

at nominal concentrations of 10 and 0.25 parts-per-million (ppm) and a benzene

permeation tube SRM with a nominal permeation rate of 0.3-0. 5 micrograms/minute

at 25 °C. The successful development of gas-cylinder SRM's was based on a precise method for gravimetric preparation and gas chromatographic measurement

reported previously [1],

During the past year, research has been specifically directed toward the

extension of this technology to the preparation and analysis of multi -component

organic gas mixtures at the low parts-per-billion (ppb) level. One of the

applications evaluated has been the preparation and analysis of a five-component

organic gas-cylinder mixture in which each of the organics were at concentrations below 15 ppb, by mole. This mixture was prepared at the request of EPA

to conduct a field test to intercompare the efficiencies of different air

sampling approaches for monitoring toxic organic species in the atmosphere.

The mixture was prepared gravimetrically , and analyzed prior to and following

the field test, as well as several months later to check the stability of the

organic components. Analyses were conducted by intercomparing a number of

primary gas mixtures prepared by gravimetry with the test mixture by repeated

gas chromatographic analysis using a flame ionization detector (FID). The

resultant data were subsequently evaluated by a statistical curvilinear fit to

obtain concentration levels for the organic components in the test cylinder.

The results are summarized in Table 38.

Table 38. Comparison of Gravimetrically Calculated and Analyzed Levels

for a Five Component Mixture.

(ppb, by mole)

Species Gravimetric 1st Analysis 2nd Analysis 3rd Analysis

CHC1

3

3.7 4.8 ± 2.6 3.5 ± 0.4 3.8 ± 0.12

CC1

4

8.2 7.9 ± 6.1 7.3 ± 1.0

C

2

C1

4

12.4 13.7 ± 3.4 11.4 ± 0.5 12.5 ± 0.16

Benzene 9.0 6.8 ± 0.3 8.3 ± 0.2 8.4 ± 0.28

Toluene 6.5 5.9 ± 0.6 6.1 ± 0.3 6.1 ± 0.23

It may be noted that in the first analysis the measurement precision of

the three halogenated compounds in the mixture is about a factor of 10 poorer

than for benzene and toluene. This occurred because the FID has a lower

response for this class of compounds and had to be operated at its limit of

sensitivity. An electron capture detector would provide greater sensitivity

for this class of compounds, but because its response characteristics are

221
non-linear, it was not used. The notable improvement between the 1st and

subsequent analyses (up to a factor of 20) was principally due to (a) increasing

the GC sampling loop volume from 5 to 10 mL, and (b) refinement of chromatographic conditions. The field test was conducted between the 1st and 2nd

analyses, during which time the cylinder pressure was reduced about 1000 psi

(from 1950 to 900 psi); performance of the 2nd and 3rd analyses resulted in a pressure loss of less than 100 psi. These data demonstrate, for the first

time, the feasibility of preparing reliable, stable, multi -component organic

gas mixtures in the very low ppb range.

The technology developed from the research being conducted in this program

is currently being applied to the preparation and analysis of four cylinders

each containing five organic species (chloroform, carbon tetrachloride,

tetrachloroethylene, benzene, and vinyl chloride) in the low (<50) and intermediate (100-250) ppb range. These gas mixtures will be used as a primary

standard for EPA in a test audit for monitoring emissions from hazardous waste

incineration. Work will also be conducted in the coming year on the certification of the first NBS multi -component organic gas mixture SRM's containing

benzene, toluene, chlorobenzene, and bromobenzene in a nitrogen matrix at

nominal concentrations of 0.25 and 9.5 ppm, by mole.

Reference

[1] Schmidt, W. P. and Rook, H. L., "Preparation of Gas Cylinder

Standards for the Measurement of Trace Levels of Benzene and

Tetrachloroethylene," Analytical Chemistry (1983) 55^, 290-294.

8. Pollutant Levels in Non-protected and Protected National Archival

Storage Areas (16114)

E. E. Hughes, R. Myers

The Gas Metrology Group participated in an extensive survey of the quality

of air within three federal buildings in which materials of great national and

artistic value are stored and displayed. The study, coordinated by the Center

for Building Technology, NBS, included the National Archives, the Madison

Building of the Library of Congress, and the East Wing of the National Gallery

of Art. The survey was conducted to determine the efficiency of the ventilating

systems for removing deleterious air pollutants drawn into and circulated

through the buildings.

In this study, measurements were made at eleven different locations

inside the National Archives. Each location was supplied by a different

ventilating system. Nitrogen oxides as NO (N02 +N0) and sulfur dioxide levels

A

were measured continuously for a minimum of 24 hours, but in most cases for at

least 48 hours. Ozone measurements were measured for several short periods of

time during each day.

The oxides-of-nitrogen analyzer and the sulfur dioxide analyzer were calibrated at the beginning and end of each sampling period and once every

222
24 hours in between. Permeation tubes were used as cal i brants for sulfur

dioxide and nitrogen dioxide, and a gas mixture of nitric oxide in nitrogen

was used to calibrate for nitric oxide. The ozone analyzer was calibrated at

NBS. It was necessary to measure instrument temperature and barometric

pressure during sampling times in order to calculate ozone levels. Although

the requirements for measurement accuracy in this report were not stringent,

the calibration scheme used was adequate to determine differences in the

ventilating systems. The maximum uncertainty of the measurement of oxides of

nitrogen did not exceed ±5% relative, since the primary cal i brant of the

oxides of nitrogen used was a stable gas mixture. The observed variation of

the sensitivity (signal /concentration) for both sulfur dioxide and nitrogen

oxides analyzers calibrated with permeation tubes was about ±10% relative over

the more than two months course of the measurements. Because little or no ozone was measured at any of the sampling sites, it was only necessary to be sure that the ozone analyzer was functioning properly when sampling.

The results of the measurements of oxides of nitrogen showed, in general,

a diurnal pattern following the morning and evening rush-hour traffic. For

all but one sampling site at the National Archives, concentrations were less

than the District of Columbia's ambient measurements. The measurements made

at the Madison Building of the Library of Congress and at the East Wing of

the National Gallery of Art were similar to the results obtained at the

National Archives.

The significance of the sulfur dioxide measurements at the National

Archives became obvious when compared to the results obtained at the Madison

Building and the East Wing of the National Gallery. The sulfur dioxide concentration at these two sites did not exceed the lower detectable limits. At the

time of the analyses, this limit was 0.0005 ppm at the Madison Building and

0.001 ppm at the East Wing of the National Gallery. The ambient concentrations

measured by the District of Columbia were consistently above the lower

detectable limits. No significant concentration of ozone was found at any of

the locations sampled either in the National Archives or at the Madison

Building and the East Wing of the National Gallery. Data supplied by the

District of Columbia Air Monitoring Division indicated a maximum ambient

concentration of 21 ppb ozone during any sampling period. Because ozone in

the ambient atmosphere is usually at low levels at the time of this study, no

real conclusions could be drawn.

Figure 45 shows a typical plot of the concentration of oxides of nitrogen

measured in one of the stack areas of the National Archives. Figure 46 shows

a similar plot of measurements made at the Madison Building.

223
TIME IN HOURS

Figure 45. Concentration of oxides of nitrogen measured in stack area

9W4 of the National Archives compared to ambient outdoor

measurements made by the DC Government.

Figure 46. Concentration of oxides of nitrogen measured in the Madison

Building of the Library of Congress compared to ambient

outdoor measurements made by the DC Government.

224
9. Toxic Gases from Lithium Battery Discharges (15330)

W. Dorko

The Naval Surface Weapons Center (NSWC) is evaluating lithium batteries

as a source of power for certain military systems. The term "lithium battery"

refers to a family of battery types, all containing lithium, but which may

differ in size, type of electrolyte, internal design, and other construction

materials. These batteries can be used aboard submarines, surface ships,

aircraft, and in a navigational system called the Global Positioning System.

A principal advantage of lithium batteries is their high and constant power

output. Two areas of concern in the use of lithium batteries are the

potential for evolution of toxic gases during discharge and the potential for

battery explosion under certain adverse conditions. NBS was requested to

examine the evolved gases generated by the batteries under various NSWC test

conditions.

A number of lithium batteries were individually discharged in special

chambers at NSWC under controlled but varying conditions. The gases evolved

from each battery discharge were collected in stainless steel sample cylinders

and transferred to NBS for analysis. The gaseous components of primary

interest were those that exceeded one percent of the total gas mixture

evolved during each discharge.

Due to the complexity of the samples, both gas chromatography and mass spectrometry were required for the analyses. Two different gas chromatographic

columns were necessary to achieve the required separation. A separate mass spectrometric analysis was used to verify the chromatographic results, and to

identify and quantify several additional constituents (HC1 , Cl 2 , and S0C1 2 ) that did not elute from the GC columns. A number of binary gas mixtures were

prepared and used for calibration purposes, along with a multicomponent gas

mixture containing C02 , COS, CS2 , H2 S, and S02 in nitrogen.

The results of a series of analyses are summarized in Table 39. A number

of the gases that were identified and quantified (CO, H2 S, HC1 , COS, S02 , CS2 , S0C1 2 ) possess toxic and/or corrosive characteristics. The results will be

used by NWSC to assess appropriate precautions for personnel protection during

battery use. These and further studies will be undertaken to improve the

understanding of the chemistry associated with the production of the observed

gases.

225
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226
10. Mathematical Chemistry: Design and Evaluation of the Analytical

Measurement Process, Detection Limits, and Multidimensional Data (15330)

Lloyd A. Currie, George A. Klouda

The program to apply advanced statistical and mathematical tools to the

analytical measurement process (AMP) has continued during the past year with

special emphasis on: (a) multi parameter data acquisition and multiple quality

control charts for environmental radiocarbon measurements; (b) development of

multidimensional (multi species) AMP design criteria taking into account the

effects of measurement imprecision and collinearity; and (c) the assessment of

the state-of-the-art and the development of improved techniques for evaluating

detection limits, particularly with regard to multidimensional measurements

and regulatory issues. The overall objective of these activities is improved

chemical measurement, using computational and statistical tools (plus physicochemical knowledge) to improve the design, evaluation and reliability of

analytical measurements—especially multidimensional measurements (and

"chemical fingerprints") and those having potential impact on public perceptions or policy.

The first activity noted above relates to the continued development of

our unique ultrasensitive 14 C counting system, in which we are monitoring

on-line a very large number of parameters for each counting event. The

approach taken has not only led to a highly reliable system for very difficult

measurements, but is providing an important case study of multi parameter

quality control and new information on the behavior of background events in

low-level counting systems. An interesting by-product is the generation of

large data sets of (presumably) random events which are of interest to the

statistical community for "physical" random number generation [1].

The importance of multidimensional AMP design has grown with the evolution

of multielement analysis and "chemical fingerprinting" (or pattern recognition)

techniques. Efforts in this area are of increasing significance, however,

because of the enormous growth of linked spectroscopic and chromatographic

techniques and because of the growing use of multi species measurements to

identify sources of environmental pollutants, "acid rain," and climaticallyactive species (as elemental carbon). From our work in FY82 on the mathematical

evaluation of multivariate Receptor Modeling (RM) data [2], it became clear

that a unified approach to the design and evaluation of RM experiments was called for, with special emphasis on what to measure, precision and sensitivity

requirements, and the effects of collinearity. As a contribution to a meeting

at NBS in May, 1983 concerning multi species measurement, receptor modeling and

acid rain, we illustrated the application of such design criteria and measurement limitations to the resolution of sources of Washington, DC aerosol. As

shown in figures 47 and 48, the decision of what and how to measure, together

with collinearity profoundly influences the ability to discrimate between

particle sources, such as coal and soil [3].

227
Collinearity

Soil (j = 1)

! Coal (j

= 2)

Fe (i = 2)

(j

= 3)

Mn (i = 1)

(SIN). ~ sin fy I (SIN)*

Figure 47. The effect of collinearity (similar source profiles or "chemical

spectra") on the precision of analysis. The signal/noise for a given source estimate (e.g., j=l, soil) is by definition the

reciprocal of its relative standard deviation. For a 1 -component

system (or orthogonal multicomponent system) the length of this

(S/N). vector is simply the vector sum of the individual contribusJ tions for each chemical measurement, (S/N)... (This follows

J directly from conventional error-propagation formulas). For two

non-orthogonal components, the overall S/N "length" is decreased

by the measure and collinearity, sin $. [Really, better termed

the "measure of orthogonality," since sin <t> + 1 when orthogonal.]

The simple expression [Eq (1) in Fig. (47)] must be viewed as an approximation for a many component system because of the

complicating effects of multi collinearity.

228
SOIL

(ng/m3

)

COAL

Limitations

1 • collinearity

2 • instability

3 • variability (crH )

4 detection limit

6 • covariance

5 • ok

Figure 48. Correlation plot for trace element patterns of soil vs coal

aerosol sources. The solid line, which would indicate complete

correlation, shows that Ca, Fe, .and A1 lead to collinearity.

Species well removed from the line (As, Pb, contemporary [CC],

and fossil carbon [FC],...) are important for source resolution.

Imperfect characteristics (numbered conditions) tend to limit

resolution or reliability.

229
The third area of endeavor relates to the general issue of detection in

multidimensional chemical measurements, and the specific issue of the "lower

limit of detection" of effluent and environmental radioactivity for the

Nuclear Regulatory Commission. These topics have been addressed at two special

ACS symposia, an NBS Symposium on Regulatory Issues, and at meetings with NRC

officials and contracting laboratories.

Assessment of detection from the perspective of Regulatory Limits, and

exposure to the actual practices among utility and (nuclear) contractor laboratories, have shown that widely varying terminology, formulations, reporting

practices, and assumptions remain in this basic area of analytical chemistry.

Having completed a literature survey for the NRC [5], we are gathering practical

information from facility and laboratory visits. During the next fiscal year,

we shall work with the NRC to help them extablish a uniform position regarding

LLDs, and produce a "NUREG" document on this topic.

Finally, in order to contribute to the furthering of mathematical -chemical

education, Dr. Currie will participate on the faculty of a NATO Advanced Study

Institute (ASI) on Chemometrics in Sept. 1983 treating the subject of Data

Analysis in Analytical Chemistry.

Reference

[1] Currie, L.A., Gerlach, R. W. , Klouda, G. A., Ruegg, F. C. and

Tompkins, G. B. , "Miniature Signals and Miniature Counters:

Accuracy Assurance via Microprocessors and Multi parameter

Control Techniques," Radiocarbon, 1983 25^ 553.

[2] Gerlach, R. W. , Currie, L. A., and Lewis, C. W. , "Review of

the Quail Roost II Receptor Model Simulation Exercise," in

Proc. APCA Specialty Conference on Receptor Models Applied to

Contemporary Air Pollution, 1983 (in press).

[3] L .A. Currie, "Design of the Multidimensional Measurement

Process for Optional Receptor Modeling Source Resolution and

Information Content: The Effect of Col linearity", talk given

at NBS in May 1983.

[4] L. A. Currie, "The Many Dimensions of Detection in Chemical

Analysis", ACS Symposium Series on Chemometric Techniques in

Pesticide Analysis (1983).

[5] L. A. Currie, "Survey of 60 Years of the Detection Limit

Literature (1923-1982)," NRC Report, Jan. 1983.
11 . Origins of Carbonaceous Gases and Aerosols: Survey of Recent

Measurement Advances and Results (15330)

Lloyd A. Currie and George A. Klouda

The development and application of advanced analytical techniques for the

assessment of natural and anthropogenic sources of carbonaceous gases and

aerosols has continued during the past year and new data on 14 C in atmospheric methane, carbonaceous particles and accelerator techniques have been

obtained [1,2].

Accelerator Mass Spectrometry (AMS) continues to be one of the most

exciting new techniques in fields ranging from oceanography to astrophysics

to environmental chemistry. The tandem accelerator at the University of

Arizona, Tucson has become a vital tool for our studies of atmospheric carbon.

Experiments demonstrated that we could measure 14 C in 100-500 yg-C of atmospheric samples with an imprecision of ^2 percent (RSD). Evaluation of the

precision and accuracy was accomplished by using three radiocarbon dating

standards and two samples of known age. Extensive measurements of blanks and

carbon from atmospheric methane and particles also took place. One of the

most important consequences of this improved sensitivity (small sample size)

is that we now can determine the biogenic carbon contribution to individual

particle size fractions and individual chemical forms--as shown in Table 40,

which summarizes our recent AMS results.

Table 40. AMS Measurements of Standards and Blanks. 3

t Modern

Sample Initial Mass-C(yg) [± la-Poisson]

14 C Dating Std (SRM 4990B) 500 [Defined as 1 .05]

New 14 C Std (RM49) 500 1.24 + 0.02

ANU-Sucrose 500 1.49 + 0.02

USGS-Wood" 500 0.42 + 0.02

Arizona- 1890 wood <300 0.96 + 0.03

Our blanks with chem.

(coal, two graphites) 300-500 0.098 + 0.01

Arizona, CaC03 Blk

NS-Graphite (direct to Fe-carbide)

2000

500

0.005 + ^0.02

a Data here and in Table 41 were obtained with the Tucson Tandem

Accelerator in January 1983. Data obtained in May 1982 on the 14 C

dating standards blanks, two aerosol samples, and the Urban Particulate

SRM were reported previously.

231
Besides the measurements by AMS, we have continued collaborative efforts

on 14 C in particles from Norway [3], the Yukon (both cases of significant

winter-time wood-burning pollution, confirmed), and Colorado. The lastmentioned work is in collaboration with Kent Voorhees, supported by NSF, and

it is directed at 14 C and pyrolysis-mass spectrometry of particles from

vegetative emmissions (remote forests), auto emissions (Eisenhower tunnel

experiment), and forest fires. This combination of techniques is continuing

to provide strong confirmation of suspected sources of carbonaceous particles

in the Rocky Mountain area [4].

Measurements on two urban particulate SRMs (1648, 1649) have taken place

during the past year on different chemical fractions, in cooperation with

Division 552. Results are given in Table 41.

New developments in our studies of carbon chemistry have focused on identifying and separating important chemical species from particles (e.g.,

elemental carbon); in miniaturizing of separation and AMS preparation apparatus

for improved yields and blanks; and in developing methods to assay CO3 in

particles via thermogravimetry and microacidification (H3 PO4 ) followed by PVT

measurement.

Research recently started includes improved isotope separator-AMS linkage

(for 14 C); a new process of AMS sample preparation based on closed-system C02 reduction followed by CO "cracking"; and the evaluation of 13 C as a supplementary tool to determine the origin of atmospheric carbon.

Finally our high sensitivity gas counting system is undergoing a major

evolutionary phase, with the addition of (a) a new data acquisition computer

with 5 MB storage to permit recording of the full individual pulse time record,

and (b) a transient digitizer, which has already given us considerable insight

into the nature (waveform) of the individual pulses.

Reference

[1] Currie, L. A., Klouda, G. A., Continetti, R. E., Kaplan, I. R.

Wang, W. W., Dzubay, J. D., and Stevens, R. K.^ "Of the

Origin of Carbonaceous Particles in American Cities: Results

of Radiocarbon 'Dating' and Chemical Characterization."

Radiocarbon 25, p. 603 (1983).

[2] L. A. Currie, "Application of Tandem AMS to Measurement of

Submilligram Amounts of Carbon in Atmospheric Gases and Particles."

[3] Ramsdell, R. , Schjoldager, 0., Currie, L. A., Moller, M.

Hassendoff, E. , Klouda, G. A., and Afheim, I., "Air Pollution

from Wood Combustion: Ambient Air Measurements in Elverum,

Norway," (Submitted to Environmental Science & Technology,

1983).

[4] Voorhees, K. J., Schulz, W. D., Currie, L. A., and Klouda, G. A.,

A., "An Investigation of the Insoluble Carbonaceous Material

in Airborne Particulates from Vehicular Emissions," (Submitted

to Analytical Chemistry 1983).

232
Table 41. Report on the Urban Dust Standards, Carbon Results.

SRM

Chemical

Fraction • Percent Carbon (SE, n)

fjj (SE)

b

(X2 /df ,df)

f

c

(SE)

Extraction Procedure #1

1648 Total 13.1

(0.3, 6)

60(3)

(0.66, 2)

43(2)

1648 PAH 80

(2,3)

22(4)

(3.45, 4)

16(3)

1649 Total 17.5

(0.4, 6)

61(4)

(0.89, 2)

45(3)

1649 PAH 87

(2,3)

17(4)

(1.88, 2)

13(3)

1649 Nonextractable 14

(1,4)

55(4)

(0.00, 1)

41(3)

1649 Benz/Meth 63

(3,3)

46(6)

(0.74, 1)

34(4)

Extraction Procedure #2

1649 Hexane Sol

.

78

(0.7, 2)

17(3)

(0.02, 1)

13(2)

1649 Methanol Sol

.

27

(11, 2)

58(4)

(2,50, 2)

43(3)

1649 Benzene Sol

.

65

(0.7, 2)

35(4)

(0.12, 1)

26(3)

1649 Water Sol

.

22

(8,2)

54(4)

(11.23, 1)

40(3)

a f

- t M

Percent "Modern Carbon" •

bSE- The standard error, SE, is the Poisson standard deviation of the mean.

c f^ - Percent contemporary carbon for SRM 1648 is = f^/1.40 [1975

vegetation] and for SRM 1649 f^ = f^/1.36 [1977 vegetation].

233
12. Detection of HC1 at the Sub-Parts-Per-Billion Level Using Tunable

Diode Laser Absorption (15330)

Alan Fried and Robert Sams (550)

In our 1982 report, we presented results of a laboratory study for

detecting the important atmospheric molecule, HC1, using a photoacoustic

detection system. The present investigation is a continuation of this study

as part of our long term effort to develop and characterize sensitive and

selective laser-based techniques for the measurement of such molecules.

Measurement of HC1 concentrations has received a great deal of attention

in stratospheric studies because of its importance in the stratospheric 03 destruction cycle. Despite this large data set, the altitude profiles collectively derived from such measurements exhibit discrepancies, and thus further

independent measurements in the critical region between 20 and 40 km are essential. The purpose of the present study is to demonstrate that the

sensitive and selective technique of tunable diode laser absorption can be

successfully employed for detection of HC1 at the sub-parts-per-billion levels

found in the stratosphere. Since the pressure in this critical region ranges

between 2 and 41 torr, photoacoustic techniques are not quite as sensitive.

In the present investigation, we report the results of a laboratory study

for detection of HC1 in this pressure regime using the NBS tunable diode laser

spectrometer coupled with a multipass White cell. The experimental apparatus

is illustrated schematically in figure 49. In contrast to many prototype

laboratory studies, this work was Carried out near the concentration range of

interest. This is important, since highly polar molecules such as HC1 present

234
(molecules • cm’3

) x 10’8

Figure 50. The second harmonic response as a function of the volume mixing

ratio for HC1, in normal isotopic abundance, at 8-9 torr based

upon four independent determinations. The points [HC1] and

[HC1] 4 are based upon ir ratioing techniques using HC1 and CH4 respectively, as the reference gas. The point [HC1

]

Neut * Act - is based upon the quantitative trapping of HC1 on nylon filters

followed by neutron activation analysis of Cl. The [HC1 ]Permeatl on response curve is based on a commerical permeation calibration

system. The uncertainties shown are the measurement standard

deviations. The uncertainties in the concentration determinations

are not shown but are discussed in the text. For readers more

familiar with other concentration units, 1 ppb = 1627 ng/m3 (STP).

235
measurement problems associated with losses and/or adsorption on instrument

surfaces when the concentration is in the ppb range. Trace concentrations of

HC1 in the 0.8 to 16 ppb range were generated using a commerical permeation

calibration system and were continually drawn through the White cell at a flow

rate of approximately 0.5 L/min. The absolute HC1 concentration in the White

cell was determined using four independent techniques: the calculated calibration system output based upon the measured permeation and diluent flow rates;

ratioing the second derivative response from the White cell to that obtained

by alternately placing cells containing reference concentrations of HC1 or of

CH4 , into the beam path; and finally, from measurements obtained by diverting

the calibration output flow through ultrapure nylon filters and subsequently

measuring the quantitatively trapped acid-chloride by neutron activation. The

results based upon all four system calibration techniques are shown in figure

50. From a detailed analysis of the various measurement uncertainties, the

latter three calibration techniques are in statistical agreement. This agreement firmly establishes the HC1 White cell concentrations used throughout this

work. Attempts are being made to find the bias in the permeation calibration.

Using a 39.4 m pathlength and the R(l) line of H 35 C1 at 2925.897 cm" 1

, we have achieved a detection limit (S/N=l) in the 0.2 to 0.3 ppb range at a cell

pressure of about 9 torr. We have also investigated the dependence of

pressure and modulation depth upon the detection limit. We have further

investigated possible interferences from CH4 , N02 , and H 2 0. At their respective

ambient concentrations, all three constituents do not present any interference

when small modulation depths are employed. Finally, we anticipate that modest

system improvements would lower the limit of detection to well below 0.1 ppb.

Such sensitivity is more than sufficient for detecting HC1 in the stratosphere.

The results of this investigation, therefore, are of extreme importance to

researchers carrying out in situ stratospheric measurements.

13. Completion of Measurements of the Temperature Dependence of the Ozone

Absorption Cross-section in the Vacuum Ultraviolet (15330)

A. M. Bass

We are now approaching the completion of this project for the determination of the temperature dependence of the ultraviolet absorption cross-sections.

These cross-sections are needed for the interpretation of observational data

and for modeling calculations of ozone concentrations in the earth's atmosphere.

The only previous comprehensive study of the temperature dependence of the ozone absorption cross-sections was done in 1953 by Vigroux [1], The older

data were recorded under less favorable experimental conditions and over irregularly spaced wavelength intervals. We have been able to take advantage

of the technological developments of the past two decades to make measurements

of much greater photometric precision on a better characterized sample of

ozone. We use a computer to control the data collection and reduction and

have been able to make measurements at much smaller wavelength intervals and

thus describe the spectrum more completely.

236
The objective of this study is to determine the ozone cross-section

values over the wavelength range 230 to 350 nm, and over the temperature

range 200 to 300 K. We have now completed these measurements for the specified

wavelength range (230-350 nm) using a spectral resolution of about 0.025 nm in

steps of 0.05 nm. The measurements have been completed for four temperatures:

295 K, 243 K, 228 K, 193 K. These results are being analyzed for statistical

consistency by Dr. R. Paur of the EPA, and a final data set will be ready for

publication by the end of 1983. Preparation of the results of these measurements for publication will complete the work planned.

In the measurement procedure used for these data, all cross-sections are referenced to the value of the cross-section at 253.7 nm. We have now completed

detailed measurements of the temperature variation from 193 K to 295 K of the

cross-section at 253.7 nm. These measurements indicate that, over this temperature interval the cross-section increases by about 1 1/2 percent. This result

contradicts the results reported earlier [1] which indicated a decrease in the

cross-section of about 3 percent.

We have proposed to follow this study by a new measurement of the

absolute cross-section of ozone at 253.7 nm. The literature value for this

cross-section has an uncertainty of about 2 percent, which is the principal

source of error in our ozone concentration measurements. We plan to collaborate with Prof. Mauersberger of the University of Minnesota in a joint project

to redetermine the cross-section. By combining his techniques of mass spectrometry and accurate pressure measurement with our high precision

photometry, we believe we can redetermine the cross-section to an accuracy of

approximately 0.5 percent. Since we have made the measurement of the entire

ozone spectrum relative to the value at 253.7 nm, we will then be able to

normalize the entire data set to the new value and thus achieve the same over all accuracy for the cross-section measurement.

Reference

[1] Vigroux, E. , Ann Physique 8, 709 (1953).

14. Reference Ultraviolet Photometer for Ozone Calibration and Assay (15330)

A. M. Bass

We have discussed in previous reports the rationale for the development

of a reference photometer for the calibration of ozone monitors [1]. To

summarize briefly, in 1979 the US Environmental Protection Agency promulgated

a new calibration procedure for ozone based on ultraviolet abosrption

photometry. In response to a request for assistance by the EPA, we undertook

to design and construct a new photometer that would serve as a primary standard for the EPA laboratories, and that would also replace the existing NBS

standard ultraviolet ozone photometer.

This development, which was done in collaboration with Dr. R. Paur of the

EPA, has been completed and the instruments that have been constructed have

met or exceeded the design criteria in all respects.

237
Three photometers have been fully completed. One instrument remains at

NBS as our new standard; the second instrument was delivered to the EPA in

February, 1983; the third photometer is now being compared with the NBS standard prior to delivery to the EPA. Completion of photometer No. 4 has been

delayed while waiting for delivery of components, but we expect to deliver the

instrument to the EPA before October 1, 1983.

The new standard is a double-beam photometer with an effective pathlength

of about 172 cm. Absorption of the 253.7 nm line of the mercury spectrum by ozone is determined by means of a very sensitive detection system. From the

measured absorbance and known pathlengths, application of the Beer-Lambert

law yields the ozone concentration of the sample. The temperature and

pressure of the sample are continuously recorded and corrections for these

parameters are made automatically. The entire measurement process is controlled

by a desk-top computer, and the data are automatically reduced and stored on magnetic tape.

Detailed testing and comparison of the new photometers has confirmed the

high precision of the instruments. Over the range of concentrations from 100

to 1000 ppb, the precision of the concentration determination is better than

±0.3 percent. At concentrations below 100 ppb the precision is ±0.2 ppb. The

accuracy of the measurement is limited to approximately ±2 percent principally

because of the uncertainty in the value of the ozone absorption cross-section

at 253.7 nm [2].

In the period May 15 to June 25, the NBS photometer was used at NBS and

the launch site as the standard for calibration of 19 instruments that will

fly on the NASA Balloon Ozone Intercomparison Campaign (B0IC). In this NASA

project, a large number of ozone monitors will be carried aloft on two balloons

in order to make simultaneous measurements in the stratosphere. These measurements will provide a basis for intercomparison of data collected over a long period of time by these instruments. This comparison provided valuable

guidance to the experimenters as to the flight-readiness of their instruments,

and will serve as a basis for the accurate reduction of the data acquired in

flight.

References

[1] NBSIR 82-2620 CAC Annual Report (1982).

[2] Vigroux, E., Ann. Physique 8, 709 (1953).

238
15. Completion of the Respirable Quartz SRM (15330)

R. L. McKenzie

There has been a long-standing need for an SRM for the calibration and

performance verification of techniques (primarily x-ray scattering used for

the identification and quantification of a-Quartz in the respirable size range

We have completed the developmental and certification research on a respirable

quartz material that will be released for sale through the Office of Standard

Reference Materials as an SRM.

The primary properties of concern for the SRM are the size distribution

(respirable, i.e. in the size range of 0.5 to 5 ym) and the purity of the

crystalline phase (a-quartz). A commercial ly-avai Table material (min-U-Sil 5) was selected as a candidate material. The size distribution of the powder was determined using sedimentation and aerodynamic size measurement techniques.

Sedimentation size distribution analysis indicated that 95 percent of the mass of the material had an equivalent spherical dimater (E.S.D.) less than 5 ym

and that the mean E.S.D. was 2.15 ym. Analysis of the number distribution of

the aerodynamic diameter of the powder indicated that 98 percent of the

particles had an aerodynamic diameter of 3.5 ym or less. The powder had an off-white egg-shell color, not white as the powder should appear, so an acid

washing procedure was developed to clean the material before further character

ization was done. The acid washing (HC1) resulted in a canary-yellow, clear

supernatant characteristic of FeCl 2 , and a white powder. Because the powder

may be used for calibration of other techniques than x-ray scattering, it is

desirable to make the powder as pure as feasible. The washing and drying of

the powder resulted in caking and aggregation of the powder such that, though

composed of respirable particles, much of the powder was not respirable. A

technique was developed for dispersing the powder in an air stream and then

collecting that portion of the powder that passed through an impaction stage

designed to have penetration characteristics approximating the American

Conference of Governmental Industrial Hygienists (ACGIH) respirable criteria.

We discovered that even when the powder is dispersed as a respirable powder,

if it is subsequently collected a large percentage (up to 40%) reaggregates

such that it is not in the respirable size range. (This is true of both the

original and the acid-washed quartz materials.) Because of the tendency to

aggregate and the difficulty in reproducibly dispersing the powder as a respirable dust, the SRM will not be certified to be a respirable dust. We

are able however, to disperse the particles in a liquid reproducibly and

demonstrated that the powder is composed entirely of respirable size particles

therefore, though the material cannot be certified to be a respirable dust we

are able to certify that the powder is comprised of particles that are in the

respirable size range.

The size distribution of the powder was established by sedimentation

measurements. We verified that the powder was reproducibly and completely

dispersed in the sedimentation liquid. Dispersion was accomplished by a soni cation and stirring procedure. Size distribution measurements showed that

the powder was homogeneous with a mean E.S.D. of 1.62 ± 0.05 ym and 97.5

percent of the mass of the particles with an E.S.D. less that 5 ym.

239
The second important property of the powder is the crystalline phase

purity. The material was tested for crystalline homogeneity by several

techniques. One test was the measurement of the lattice parameters (at 25 °C).

The mean values (in angstroms)

<a> = 4.9135 (1)

<c> = 5.4057 (1),

agreed closely with the reported lattice parameters for crystalline a-quartz.

Another test of homogeneity consisted of comparing the intensity of the 100

reflection to the intensity of the 101 reflection. No measurable differences

were observed for the samples analyzed that were attributal to sample inhomogeneity. The final test was based on the determination of the Reference

Intensity Ratio (RIR) of the quartz relative to silicon powder. RIR is

defined as the ratio of the intensity of the strongest line of the analyte to

the strongest line of silicon for a 1:1 mixture by weight. This test also

indicated no measurable inhomogeneity exists in the powder. The final mea- surement was a direct measurement of the crystalline and amorphous quartz

percentages of the powder. These measurements demonstrate that the powder is

>95 percent a-quartz. Final determination of the exact value and a statement

of precision of the number are in process by NML statisticians.

16. Use of Monte Carlo Electron Trajectory Simulation for Basic Studies in

Analytical Electron Microscopy (26109)

Dale E. Newbury, Robert L. Myklebust

The NBS Microanalysis Monte Carlo electron trajectory simulation [1] has

been applied to the study of two fundamental problems in quantitative analytical electron microscopy: (1) the role of fast secondary electrons in degrading

spatial resolution and (2) determination of the correct form of the x-ray

generation depth distribution function for tilted thin samples.

The question of the limits to spatial resolution in analytical electron

microsopy (AEM) has been a subject of great interest in the AEM community in

recent years [2], Previously, all attention has been focused on the role of

high angle and multiple elastic scattering in degrading the cylindrical interaction volume defined by the current distribution of the incident probe and

the specimen thickness. Recently, it has been recognized that fast secondary

electrons generated by the high energy beam electrons can degrade the spatial

resolution [3]. Fast secondary electrons (FSE's) are generated by ejection

of atomic electrons during inelastic scattering of the beam electrons. Their

kinetic energies can range from zero to half of the incident beam energy.

The cross section for production of FSE's follows a 1/E2 dependence, so that

the majority of FSE energies lie below 0.1 E Q

, where EQ

is the incident beam

energy. Most importantly, FSE's in this energy range are scattered at angles

from 60° to 90° from the incident beam trajectory. For an electron beam set

normal to the surface of a foil, the FSE's tend to propagate laterally into

the foil, degrading spatial resolution. Moreover, the cross section for inner

240
shell ionization, which leads to the production of the characteristic x-rays

used for analysis, tends to peak at low values of the overvoltage U (U = E/E ) where E is the energy of the exciting electron and E is the critical excitaV

tion energy for the atomic shell). The influence of FSE's upon the excitation

of x-rays of low energy (0.5 to 5 keV) is larger than the number of FSE's

relative to the number of beam electrons would suggest.

The Monte Carlo electron trajectory simulation has been modified to

calculate FSE generation. The simulation has become, in effect, a "double

Monte Carlo". A primary trajectory is followed until FSE generation occurs,

and then the primary trajectory is interrupted while the FSE is followed until

it either escapes the foil or is absorbed, after which the primary trajectory

is resumed. An example of the results of the calculation is shown in figure

51, which compares the interaction in a silicon target from beam electron

excitation and from FSE excitation. The two interaction volumes are significantly different in shape. The interaction volume due to beam electrons is

cone-shaped with the apex at the beam entry point, while the interaction

volume due to FSE's is cylindrical, a result of the fact that FSE's are created with nearly uniform probability along the beam electron trajectory.

The significance of these calculations is that there exists a fundamental

physical limit to spatial resolution, independent of elastic scattering of the

beam electrons. FSE-generated x-rays will have to be considered in models

for de-convolution of high spatial resolution compositional profiles.

Figure 51. Comparison of electron interaction volumes for primary

beam electrons and fast secondary electrons; target

silicon, 100 nm thick; beam energy: 200 keV.

241
The depth generation function of x-rays produced by the beam electrons

is an important parameter in models for the quantitative AEM analysis [4].

At normal beam incidence, the generation function follows a monotonic increase

with depth. This behavior has been assumed in current models for correction

of x-ray absorption effects. Many AEM's require the sample to be tilted to

angles as high as 45°. At these angles, scattering parallel to the foil

surface will occur which can modify the depth distribution function. To study

this phenomenon, the Monte Carlo simulation was employed in conjunction with

experimental measurements of x-ray production at the exit surface of gold

foils [5]. An example of the results is shown in figure 52. The solid curve

shows the comparison of the Monte Carlo calculations for the exit surface with

experimental measurements made with a tracer layer placed on the exit surface

of thin gold foils. Considering the difficulty of the experiment, the agreement is satisfactory. The plotted points give the Monte Carlo results for the

x-ray depth production function for foils of various thicknesses. The curves are found to deviate significantly from the monotonic increase observed at

normal beam incidence. The results of these calculations can be utilized for

the development of more accurate models for quantitative AEM analysis.

Figure 5. Comparison of <j>(pz) curves for thin gold films calculated

by Monte Carlo electron trajectory simulation and

measured by use of Au-Hf foils; beam energy-100 keV;

sample tilt-45°.

242
References

[1] Newbury, D.E. and Myklebust, R.L. (1981) "A Monte Carlo Electron

Trajectory Simulation for Analytical Electron Microscopy" in

Analytical Electron Microscopy-1981, ed. R. Geiss (San Francisco

Press, 1981) 91.

[2] Newbury, D.E. (1982) "Beam Broadening in an Analytical Electron

Microscope" in Microbeam Analysis-1982, ed. K.F.J. Heinrich

(San Francisco Press) 79.

[3] Joy, D.C., Newbury, D.E., and Myklebust, R.L. (1982) "The Role

of Fast Secondary Electrons in Degrading Spatial Resolution in

the Analytical Electron Microscope", J. Microscopy, 128, RP1

.

[4] Goldstein, J.I. (1979) "Principles of Thin Film Microanalysis"

in Introduction to Analytical Electron Microscopy, ed.

J.J. Hren, J.I. Goldstein, and D.C. Joy (Plenum, New York) 83.

[5] Newbury, D.E., Myklebust, R.L., Romig, A.D. and Bieg, K.W.

(1983) "Observations on the Determination of 4. (p z ) Curves for

Thin Films in the Analytical Electron Microscope" Microbeam

Analysis-1983, ed. R. Gooley (San Francisco Press) 168.

17. Visualization of the Three-Dimensional Nature of the Electron Interaction

Volume in Solids (15330)

D. S. Bright, R. L. Myklebust, D. E. Newbury

The development of the Monte Carlo electron trajectory simulation

technique for solid specimens has provided a major tool for theoretical

calculations in scanning electron microscopy (SEM), electron probe analysis

(EPMA), analytical electron microscopy (AEM) and microbeam lithography [1].

Analogous to the development and use of dynamical diffraction calculations

in the interpretation of transmission electron microscope images of crystalline

objects, Monte Carlo calculations are being employed to aid in the interpretation of SEM images [2,3] and for the prediction of x-ray intensities generated

in targets, particularly those with unusual shapes [4,5]. In many cases, a graphical plot is particularly valuable in understanding the behavior of

electron trajectories at a discontinuity such as a boundary.

Plots of electron trajectories are usually generated by projecting the

trajectory segments between scattering points onto a plane which is either

perpendicular or parallel to the specimen surface. A continuous record of

each trajectory is thus obtained, but the three dimensional nature of the

interaction volume is lost. In such a plot, an example of which is shown in

figure 53, it is difficult to follow a particular trajectory when several

trajectories apparently intersect in the projection plane. Also, as seen by

contrasting the flat or planar representation of figure 53 with the 3-D representation in figure 53, the loss of the third dimension by projecting on to a plane causes serious loss of any notion of true shape. Projection onto a plane makes the overall size of the interaction volume to appear smaller and

243
Is_

Figure 53. Side view of a 40 keV beam incident on gold at

10° from the surface, plotted in stereo as

(a) a two dimensional projection and (b) a three dimensional object. Cube edge 0.3 mm.

much more dense than the view obtained by stereo projection. Further, most

of the trajectories appear to overlap and become confused.

To overcome these limitations, a method of generating matched stereo

projection plots of Monte Carlo trajectories has been developed to visualize

the true three dimensional structure of the electron interaction volume.

There are advantages and unique capabilities of stereo presentation.

The stereo presentation allows a sense of spatial size and often allows one to

look behind nearer trajectory segments to follow more distant segments, so that confusion from overlap does not occur. Beyond the improvements over

conventional projection plotting noted above, the three-dimensional Monte Carlo

plot offers the capability of providing any desired view of the trajectories

from different observation points. This facility is illustrated in figure 54,

which illustrates three useful views of the interaction volume and backscatter

distribution from a highly tilted gold target.

244
l*_

Figure 54. Three views of a 20 keV electron beam incident

gold on at a grazing angle (1 deg. from

surface). Cube edge =0.3 ym.

(a) a few degrees above the tilt axis which is

similar to the conventional projection

representation; (b) along the surface normal,

looking toward the surface; and (c) a few

degrees above the surface looking back towards

the incident beam.

245
Reference

[1] Heinrich, K.F.J., D.E. Newbury, and H. Yakowitz, eds. (1976).

"Use of Monte Carlo Calculations in Electron Probe Microanalysis

and Scanning Electron Microscopy: National Bureau of Standards

(US) Special Publication 460 (Washington, DC).

[2] Fathers, D.J., J.P. Jakubovics, D.C. Joy, D.E. Newbury, and

H. Yakowitz (1973), "A new Method of Observing Magnetic Domains

by Scanning Electron Microscopy: I. Theory of the Image

Contrast", Phys. Stat. Sol. (a) 20:535.

[3] Murata, K. (1973), "Monte Carlo Calculations on Electron

Scattering and Secondary Electron Production in the SEM",

SEM/1973, 267.

[4] Yakowitz, H., D. E. Newbury, and R. L. Myklebust (1975),

"Approaches to Particulate Analysis in the SEM with the Aid of

a Monte Carlo Program", SEM/1975, 93.

[5] Newbury, D.E. and R. L. Myklebust (1979), "Monte Carlo Electron

Trajectory Simulation of Beam Spreading in Thin Foil Targets",

Ultramicroscopy 3:391.

18. An Evaluation of X-ray Loss Due to Electron Backscatter (15330)

R. L. Myklebust

One of the most important corrections in the atomic number-absorptionfluorescence matrix correction technique (ZAF) used in quantitative electron

probe microanalysis is the so-called "R-factor". The R-factor is an estimate

of the fraction of the total possible inner shell ionization which is actually

produced in the specimen considering the loss in possible ionization which

results from electron backscattering. The formulation of the R-factor

currently in use is based on empirical fits of experimental data on electron

backscattering and backscattered electron energy distributions [1]. While

this formulation has great value in quantitative microanalysis, there exists

some uncertainty in its accuracy due to the limited angular integration of the

backscattered electron energy distribution in the experimental measurements.

Moreover, the expression for R is in the form of a fifth degree polynomial in

two separate variables which is inconvenient to calculate.

The loss of x-ray intensity due to backscattered electrons has been

re-evaluated with the aid of a Monte Carlo (MC) simulation for electron

scattering in solids. The advantage of the Monte Carlo simulation is the

capability of effectively integrating the energy distribution of backscattered

electrons over all possible angles of emission. Additionally, the Monte Carlo

simulation can be applied to the calculation of tilted specimens for which

virtually no experimental data exists. The Monte Carlo simulation is a single

scattering model employing a Rutherford scattering cross-section and a Bethe

inner shell ionization cross-section [2]. Initial electron energies in the

246
range 4-50 keV were considered in this study. The results are presented as

R, the ratio of x-rays generated within the solid to the total x-rays that

would have been generated had none of the electrons backscattered. The R

values for K x-ray lines agree reasonably well with those of [1]; however, the

R values for L and M x-ray lines are different. Table 42 lists a few of the

values obtained together with values computed with an expression formulated by

Duncumb [1]. A third value is listed which was computed with the expression:

R = aZ + bZ

2 + cZ(exp(-U) ) + 1

where Z is the atomic number and U is the overvoltage (initial electron energy/

excitation potential). The coefficients a, b, and c have different values for

)f x-ray lines.

Table 42.

Element Line U R(MC) R(Duncumb) R(calc)

Na K 4.0 0.924 0.939 0.930

Fe K 4.0 0.846 0.861 0.841

Ru K 2.0 0.809 0.837 0.790

Zr L 4.0 0.750 0.791 0.758

Ag L 4.0 0.726 0.765 0.730

Pb L 2.0 0.697 0.747 0.715

Ta M 6.0 0.613 0.674 0.624

Bi M 6.0 0.613 0.650 0.600

U M 6.0 0.596 0.633 0.583

The principal differences in quantitative analyses calculated with R(MC)

and R(calc) compared to R(Duncumb) are evident for high atomic number elements.

Three lead silicate glasses were analyzed using two different lead standards.

The results of the analyses are shown in Table 43.

Table 43. Lead Anlyses at 15 keV and Pb M-alpha X-ray Line.

Glass Composition New R-factor Duncumb R-factor

Standards Standards

Pb PbTe K-227 PbTe K-227

K-456 65.76 65.70 65.62 66.97 65.99

K-493 63.28 63.47 63.41 64.81 63.84

K-523 63.45 63.30 63.24 64.64 63.68

References

[1] Duncumb, P. and Reed, S.J.B., NBS Spec. Pub. 298, K.F.J. Heinrich,

ed., (1968) 133.

[2] Mott, N.F. and Massey, H.S.W., The Theory of Atomic Collisions,

2nd Edition, p. 243 (Oxford Univ. Press, London, 1949).

247
19. Studies of the Depth Distribution of Boron in Glass by Neutron Depth

Profiling and Secondary Ion Mass Spectrometry (15443)

G. Downing, R. Fleming, B. Stallard, D. Simons

During the past year the first spectra were obtained utilizing the neutron

depth profiling (NDP) facility at the 10 MW NBS reactor. This dedicated

facility, unique in the United States, allows nondestructive determination of

concentration profiles in the near-surface region for selected elements [1].

By coupling the capabilities already available using secondary ion mass spectrometry (SIMS) with the complementary strengths of NDP, a totally new synergism has become available for material analysis.

The NDP technique provides an absolute concentration scale and can be

used to nondestructively detect variable ionization or matrix effects which

might be present in the SIMS spectra. Initial applications were prompted by

the semiconductor industry's interest in the concentration and spatial distribution of boron in processed and unprocessed semiconductor materials. Figure

55 is a comparison of the NDP spectrum, before resolution corrections, and the

SIMS depth profile for an annealed boron-10 implant in silicon. The SIMS

technique provides sharper resolution and is capable of detecting concentration

levels to 1014 atoms/cnr. This sample is one of a series analyzed to study

the total boron distribution, including the boron component that is not

electrically active and thereby not observable by the commonly used spreading

resistance probe. The boron, a solid state precipitate, is manifested as the

peak that rises above the broader electrically active and thermally mobile

boron distribution in the figure.

Figure 55. Depth Profiles obtained

by the SIMS and NDP

technique for a 70 keV

boron-10 implant in

silicon at a dost of

1016 boron- 10 atoms/cm2 and annealed at 1000 °C

for 30 minutes.

1021

1020

CO ^ E

o

(AE

o**<

CD °

1019 -

1018

Jl. £ ' /

o Secondary Ion Mass Spectra

• Neutron Depth

Profile

0 200 400 600 800

Depth in Nanometers

248
A second example of a joint NDP-SIMS analysis is shown in figure 56.

Borophosphosilicate glass (BPSG) is a material often used as the insulating

barrier between devices on microcircuits as well as the support for the electrical leads between devices. The integrity of the circuit depends critically

on a smooth, continuous glass film over the substrate and therefore, on a uniform boron distribution in the glass. Knowledge of the glass film thickness

is also desired. In this case a SIMS and NDP collaborative effort was used to:

(1) study the boron profile in the "as deposited" and "processed" films;

(2) quantify the concentration of boron present in the samples; (3) calibrate

the Fourier transform infrared (FTIR) technique for total boron determinations;

and (4) evaluate concentration data from the prompt gamma-ray emission (PGRE)

technique. Figure 56 compares spectra obtained from a BPSG film by SIMS and

NDP analysis. As before SIMS provides the greater resolution. The NDP

measurement, on the other hand, was able to identify and correct measurement

artifacts present in the SIMS spectra as a consequence of sample charging

during analysis and to establish an absolute boron concentration scale.

Measuring the crater depth produced by SIMS enabled a depth scale to be

obtained for these spectra. The absolute boron concentration determined from

the NDP spectra also allowed comparisons with the values obtained from the

FTIR and PGRE techniques and made possible a calibration of the FTIR for

future total boron measurements of BPSG films.

Figure 56. A comparison of depth profiles measured by SIMS and NDP

techniques for a thin BPSG film on a silicon substrate.

Other studies now underway include the profiling of sodium in glass,

boron and beryllium in gallium arsenide, and analysis of boron diffusion and

segregation through Si02 /Si boundaries.

Reference

[1] R.G. Downing, R.F. Fleming, J.K. Langland and D.H. Vincent,

"Neutron Depth Profiling at the National Bureau of Standards",

Sixth International Conference on Ion Beam Analysis, Tempe, AZ

May 23-28, 1983.

249
20. Detection and Analysis of Organic Monolayers by Laser Microprobe Mass

Analysis (13225)

R. A. Fletcher

The laser microprobe mass analyzer (LAMMA) is an instrument which couples

a Nd:YAG laser for ablating and ionizing a sample to a time-of-flight (TOF) mass spectrometer for ion analysis. Usually this instrument is used at high

power densities for detection of atomic ions with high sensitivity. By using

low laser power densities, we have been able to gently desorb, ionize, and

detect an organic monolayer from the surface of a 5 nm thick silver film.

Moreover, this measurement has been carried out with a lateral resolution of

^10 micrometers which is a unique capability in organic mass spectrometry.

The thin silver films are made by an evaporative process which results in

resonant-active silver microstructures (silver islands) being created which

are utilized in surface-enhanced Raman scattering (SERS). The silver film is

spin-coated with a 0.001 mol/L paranitrobenzoic acid (pNBA) in ethanol solution

forming what we believe to be paranitrobenzoate, (pNBA-H)”, on the surface.

This molecular ion has been observed on the Ag film by SERS. The initial goal was to see whether the silver microstructures which have a surface resonance

at the frequency doubled wavelength of the Nd:Yag fundamental, 532 nm, could

be used to desorb the (pNBA-H)’ ions. The resonant effect was not observed,

but (pNBA-H)" was detected from the monolayer as shown in figure 57(b).

Figure 57(b) shows the negative ion mass spectrum that results when a 5 nm thick Ag film coated with a monolayer coverage of (pNBA-H)" is irradiated by

a laser pulse with energy densities (at the sample surface) of ^400 mJ/cm2. Figure 57(a) shows a similar spectrum for the Ag film without pNBA coverage.

The molecular ion peaks of (M-H)~ at 166 atomic mass units (amu), and its

fragments of (M-H-C02 )" at 122 amu and N02 ~ at 46 amu are present in figure

57(b) and absent in figure 57(a). Contaminant peaks which appear in figure

57(a) and (b) most likely result from the film preparation and are not totally

unexpected since the samples are exposed to air for several days prior to

analysis. The Ag" ion appears at 107 and 109 amu in both spectra.

When the pNBA coated film is irradiated at energy densities of ^100 mJ/cm2 at either 266 or 532 nm wavelengths, a gentle desorption process occurs which

liberates molecular ions from the surface as shown in figure 57(c). The

desorption mechanism is thought to be thermal in nature. Evidence for this is

the strong power dependence and wavelength independence (for the two wavelengths used). Extinction measurements of the coated Ag films show that the

absorption is nearly equal at wavelengths of 266 nm and 532 nm. The Ag film

thus absorbs the radiant energy, heating the surface to liberate the preformed

negative ion, paranitrobenzoate. This shows a detection capability for ^106 molecules based on irradiated spot size and assuming 1014 molecules/cm2 coating

density for the monolayer.

This gentle desorption technique should prove to be a useful analytical

tool for organic molecular analysis since the molecule is preserved in the

desorption process and there appears to be some selectivitity on the sample

surface as apparent in figure 57(c), where only the molecular ion with its

fragments are present in the spectrum.

250
1 1 1 1 1

1 1 r 23 40 60 80 100 120 140 160 180 200 m/z (amu) Figure 57. Negative ion TOF mass spectra of (a) uncoated silver film,

(b) paranitrobenzoate monolayer coated film at laser energy

densities of >400 mJ/cm2 and (c) coated film at lower laser

energy density, ^95 mJ/cm2

. The laser wavelength was

532 nm for (a) and 266 nm for (b) and (c).

Reference

[1] Fletcher, R.A., I. Chabay, D.A. Weitz, and J.C. Chung "Laser

Desorption Mass Spectrometry of Surface-Adsorbed Molecules."

Chem. Phys. Letts, (submitted).

21 . Standard Reference Material for Analysis of Asbestos by Electron

Microscopy (15330)

John A. Small, Eric B. Steel

The determination of asbestos present in the non-workplace environment is

currently accomplished by filtering the air sample through a membrane filter

and then analyzing the collected particulate by analytical electron microscopy

(AEM). A multi -laboratory study was conducted in 1977 by the Environmental

Protection Agency (EPA) on ambient air samples with unspecified sample preparation and counting procedures. The results reported from the different

laboratories on the analysis of split samples varied by several orders of

magnitude for the asbestos fiber loading in the air. Since that time, the EPA

has been developing a standard methodology for the analysis of asbestos in

non-workplace environments. As part of the EPA's overall asbestos program,

the National Bureau of Standards (NBS) and the EPA have been cooperating on the development of a Standard Reference Material (SRM) to aid in the analysis

of the asbestos-fiber loading in non-workplace samples. The final goal of our

program was to provide an SRM in the form of statistically predictable loadings

of chrysotile asbestos fibers on a substrate suitable for sample preparation

and analysis by AEM. This set of samples could be used by field laboratories

251
to test, refine, and calibrate their sample preparation and analysis procedures..

The SRM consists of sections from a polycarbonate filter which contain a medium loading of chrysotile asbestos mixed with an urban particulate matrix.

Urban air particles were selected as the matrix material so that the SRM would

simulate a sample collected from the environment.

The work on this standard has been completed. It will be released in two

batches as SRM 1876 and SRM 1876A. It was decided that the users of the SRM

should determine the asbestos fiber loading by AEM on five separate areas of

approximately 0.01 mm2 each and average the five values. It was felt that a sample size of five represented the minimum number of samples necessary to

make the standard usable in the field. A laboratory cannot be evaluated on the basis of one sample because of the large single-measurement variation in

the counts. An additional constraint placed on the users is that the areas counted must come from areas which are distributed evenly over the entire

filter section used for preparation of the standard rather than one local area. Table 44 lists the certified values "for the two SRM batches, the uncertainties

in these values expressed as the 95-95 tolerance intervals for a five measure- ment mean.

Table 44. Certified Values and Uncertainties.

SRM Certified Value Tolerance Interval

Fibers/0.01 mm2 Fibers/0.01 mm2

1876 30 ±9

1876A 37 ±13

The certified values are means calculated from the analysis of 21 individual 0.01 mm2 areas on SRM 1876 and 23 areas on SRM 1876A. Each individual area was analyzed by 2-5 operators with the verified counting procedure which

was developed at NBS [3]. The verified counting procedure uses the relative

locations of the fibers recorded by each operator, to construct a map which

shows the position of each fiber for each operator. The fiber count on the

grid opening is then verified by having an operator reanalyze any fiber for

which there were questions. This includes any fibers that were found by only

one operator, or any fibers whose identification was disputed because of

ambiguous morphology or diffraction data. In this way, a count approaching as closely as possible to the true amount of asbestos is obtained.

Tolerance intervals rather than sample standard deviations were chosen as

a robust way of making credible statements about uncertainties in means of

counts that the users are likely to obtain in their attempts to characterize

pieces of the SRM filter. A 95-95 tolerance interval for a five measurement

mean indicates that 95 percent of the population of such 5-count means will

fall within the tolerance interval with a 95 percent confidence. The certificate for the SRM will also include the sample standard deviations for the two

SRM batches since this value is based directly on experimental measurements.

252
References

[1] Leidel, N.A. , Bayer S.G. , Zumwalde, R.D. and Busch, K.A.,

USPHS/NIOSH Membraine Filter Method For Evaluating Airborne

Asbestos Fibers, Technical Rpt., U.S. Dept. HEW 1979.

[2] Mountgomery County Asbestos Study, EPA Internal rpt. U.S. EPA,

Environmental Monitoring Systems Laboratory, Environmental

Monitoring Division, Research Triangle Park, N.C. 27711,

Oct. 1977.

[3] E.B. Steel, J.A. Small, and P. Sheridan, Analytical Errors in

Asbestos Analysis by Analytical Electron Microscopy, NBS SP.

619, Asbestos Standards: Materials and Analytical Methods,

1982, p 162.

22. Visibility of Asbestos Fibers in the Scanning Electron Microscope (15330)

J. A. Small, D. E. Newbury, R. L. Myklebust

The analysis of asbestos mineral fibers in environmental samples requires

the careful determination of fiber loading on filter media [1]. Well established techniques exist for the transfer of asbestos fibers from such filter

media to thin carbon films and subsequent counting in the transmission electron

microscope (TEM) [2,3]. However, due to the cost of TEM instrumentation and

the time required for sample preparation, there has been considerable interest

in the development of techniques for direct examination of the filter in the

scanning electron microscope (SEM). In this work, we have considered the

problem of fiber visibility under SEM imaging conditions in a fiber search/

counting procedure.

The asbestos mineral chrysotile is typically found in environmental

samples as long fibers composed of one or more fibrils. Individual fibrils

have a diameter of approximately 40 nm and a length which can extend to

several micrometers. In order to estimate the visibility of single fibrils

and fiber bundles in an SEM image, we have used a three stage procedure:

first (1) we calculated the contrast of the asbestos fiber compared to the

filter background with the NBS Monte Carlo program; (2) we calculated the

threshold beam current necessary to observe that contrast; and (3) we calculated the smallest beam size which could contain the required threshold

current. Finally, by comparing the size of the beam calculated in the above

steps, with the fiber diameter, the visibility of the fiber was estimated.

Table 45 shows the results of the calculations for several different

fiber diameters. These results indicate that asbestos fibers below approximately 200 nm diameter will not be visible under the imaging conditions in a fiber search/counting procedure. Only for fibers of 240 nm diameter and above

is the threshold visibility condition substantially exceeded, which should

ensure adequate image quality. The minimum fiber size for visibility can be

reduced by using more efficient detectors and higher brightness electron

sources. For practical conditions, such improvements might decrease by a factor of two the minimum fiber diameter which would be visible. However,

253
Table 45. Calculations of Asbestos Fiber Contrast and Visibility.

Fiber diameter

(nm)

Contrast Threshold Current

(nA)

Beam Diameter

(nm)

Visibility

40 0.013 540 1050 No

80 0.025 147 550 No

120 0.031 95 440 No

160 0.039 60 350 No

200 0.049 38 280 ? 240 0.061 25 223 Yes

since the statistical assumptions used in deriving the threshold equation are based on an average observer, it should be noted that working with objects near the visibility threshold will produce counting results that are erratic

and subject to large uncertainties. Since environmental asbestos samples are likely to contain fibers of small diameter, we recommend not using an SEM

counting procedure for characterization of such samples.

References

[1] A.V. Samudra, C.F. Harwood, and J.D. Stockham, "Electron

Microscope Measurement of Airborne Asbestos Concentrations, A

Provisional Methodology Manual", Environmental Protection

Agency, EPA-600/2-77-178, revised 1978.

[2] P.M. Cook and D.R. Marklund, "Sample Preparation for Quantitative

Electron Microscope Analysis of Asbestos Fiber Concentrations

in Air" in Asbestos Standards: Materials and Analytical Methods,

National Bureau of Standards (US) Special Publication 619

(Washington, 1982) eds. J. Small and E. Steel, 53.

[3] E.J. Chatfield, "Analytical Procedures and Standardization for

Asbestos Fiber Counting in Air, Water, and Solid Samples" NBS

SP 619, op cit. , 91

23. An Analytical Algorithm for Calculation of Spectral Distributions of

X-ray Tubes for Quantitative X-ray Fluorescence Analysis (15330)

L. Feng, P. A. Pella, J. Small

Last year we reported on the initial development of an algorithm for

calculating the spectral distribution of x-ray tube emission for making

fundamental parameter matrix effect corrections in quantitative x-ray fluores- cence analysis [1], Fundamental parameter methods require knowledge of the

sample excitation function and hence the spectral distribution of the particular

x-ray tube used for excitation. Several researchers have proposed theoretical

approaches to the calculation of spectral distributions but these require

rather extensive computer capabilities. In addition, these methods require

254
knowledge of parameters such as backscattering and target absorption factors,

ionization cross sections, and fluorescence yields which are not known with

sufficient accuracy. Spectral distributions have been measured, but only for

a few x-ray tubes operated at 45-50 kV.

We have completed an initial phase of our work this year in that we have

developed an algorithm to calculate x-ray tube spectral distributions under

various operating conditions by utilizing extensive electron microprobe data

obtained with several pure metal targets, covering a wide range of atomic

numbers. This proposed analytical algorithm has the advantage that it is

simple to program on a computer and combines several fundamental parameters

mentioned above into factors determined by the curve-fitting of the corrected

electron microprobe experimental data. The algorithm calculates the continuum

spectral distribution and the ratio of the target characteristic x-ray line

intensity to the continuum intensity at the wavelength of the characteristic

line. The target characteristic line intensity is then calculated by multiplying the ratio by the associated continuum intensity. For use in quantitative

x-ray fluorescence analysis, the sample excitation function or primary spectrum

is obtained by integrating from the short-wavelength limit to the absorption

edge wavelengths for the analyte element(s) of interest in the specimen.

We have performed some limited testing of our proposed algorithm. The

continuum spectral distributions calculated from our algorithm were compared

to those calculated from another fundamental parameter program called NRLXRF.

These calculated primary spectra were also compared to experimental x-ray tube

data from the literature [2]. In figure 58, for example, the primary spectra

for a tungsten target x-ray tube operated at 45 kV, a x-ray tube take-off

angle of 22 degrees, and a beryllium window thickness of 0.25 mm are compared.

These data indicate good relative agreement. To illustrate the validity of

our proposed algorithm for analysis purposes, we analyzed a number of wellcharacterized Fe, Ni , Cr alloys using just the pure elements as standards for

calibration. In Table 46 are summarized the results on selected alloys using

the NRLXRF fundamental parameter program. The concentrations were calculated

using either the primary spectrum calculated from our proposed algorithm

substituted in the NRLXRF or that calculated by NRLXRF. This was done by

editing the existing NRLXRF spectral distribution file. In order to be consistent, the intensity data were input over the same wavelength region as the

inherent NRLXRF primary spectral data. In this way we could compare results

using different sources of primary spectral distributions. The results shown

in Table 46 are in reasonably good agreement, with relative errors less than

5 percent. Although these results are encouraging, more extensive work is

needed to fully test the proposed algorithm. During the upcoming year we intend to include various sample types such as fused and pressed powder

samples, and to analyze them with different x-ray tube targets at various

operating conditions.

255
I

\

(arbitrary)

W TARGET

1.0 2.0 0 3.0 40

X(A)

Figure 58. Comparison of experimental and calculated continuum

spectral distributions.

References

[1] NBSIR-82-2620, page 208.

[2] Brown, D. B. , Gilfrich, J.V., and Peckerar, M. C. , J. Appl.

Phys. 46, No. 10, 4537 (1975).

256
Table

46.

Analysis

of

NBS

Alloys

Using

NRLXRF

Fundamental

Parameter

Method

With

Different

Sources

of

X-Ray

Tube

Spectral

Distributions. 9

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L. • • • <_> CD to CD 00 P— CVJ r— c

0)E • r— *3- r— P—

•f- o 00 CM CM o • CO CO CVJ <U i—i Qu oo

LO in LO rx cso

"Oc

•r—s

CL) CO

in

<u

cr> e

CO01 cu

(0

+-> oCO

CM

LOo-

-Oc

co oCM

+-> cuCD

s_co

toeo

+j

•r— -ocoo

CD

-t-> co

s-cuQ.O

CU JD3

4->>>

ro

S- XCO

to • to +J +-> r—3 3

to CO

CU cu

s- S- > >JaC o LO

CM <oCU cu

s- s03 c0

CU cu c c

‘1— 1— 1— 1—

s_ scu cu Cl s

CL o 3 —

to

C

•r*

CO CO

+-> +-> CO CO Q Q , s p*—** t— OJ V ' X ^

257

Note:

RE=

relative

error
24. Comparison of Theoretical a-Coefficient Fundamental Parameter Method with

NRLXRF for Quantitative X-ray Analysis (15330)

P.A. Pella, Y. Tao

Fundamental parameter methods for quantitative x-ray fluorescence analysis

make use of equations derived from first principles and contain physical

constants, absorption coefficients, primary excitation spectra and geometric

factors. They can be used to predict the x-ray intensity emitted by an element

in any prescribed specimen composition after correction of the matrix effect.

The correction term can be visualized as the sum of all coefficients of every

element j of the matrix, each one taken in a proportion equal to the concen- tration C.. Expressed mathematically

vl C. = K - 1 - ( 1 + l .a. -C.)

1 l l

v J 1J J where each a., coefficient represents the quantification of all matrix effects

* J due to element j on analyte i, and thus has physical meaning. Therefore, the

calculation of from the measured intensity I. is possible provided that all

values of the alpha coefficients are accurately known. Alpha coefficients can be reliably determined experimentally using regression methods, but this

depends on the availability of sufficient standards which is often not

practicable. A simpler approach is to compute theoretical alpha coefficients

from fundamental parameter expressions. Unfortunately, for certain sample

types, especially alloys, a., is not a constant over the entire concentration

* J range of the analyte from 0 to 100 percent. Over the past few years a comprehensive alpha model has been proposed by Lachance [1] which employs three

alpha coefficients in addition to so-called "crossed" coefficient term which

are calculated to describe the overall matrix correction from the 0 to 100

percent analyte concentration range in accordance with fundamental theory.

During the past year we have evaluated this model by analyzing a number of

sample types such as alloys, pressed powders and fused minerals and compared

the results with those obtained by another fundamental parameter program

called NRLXRF. The alpha algorithm was obtained from Lachance in the form of

a computer program which we modified somewhat and is on our NBS computer

facility. In Table 47 is a summary of the analysis of selected samples of

each type. The results are in good agreement with the accepted values and

also consistent with NRLXRF. The alpha algorithm presently employs measured

primary x-ray tube spectral distributions for sample excitation.

We are also currently working to incorporate our proposed NBS algorithm

for calculating the primary spectral distribution in this quantitative

analysis scheme, so that we can test its relative accuracy with NBS standard

reference materials during the next year.

Reference

[1] Lachance, G.R., Claisse, F., Adv . X-ray Anal, 23 , 87 (1980).

258
Table 47. Comparative Analysis of Selected Samples.

Sample Type

Elements

Stainless Steel Method Cr £e Co N1_ Mo

1198 a 12.9 36.2 0.70 40.1 6.08

b 12.80 36.19 0.72 40.21 6.12

c 13.08 36.36 0.70 40.29 6.08

Compounds

Fused Minerals Al

2°3 sio

2

k

2

o CaO tio

2

Fe2°3

NBS-76 a 37.67 54.68 1.37 0.27 2.21 2.38

b 37.91 55.66 1.60 0.21 2.18 2.14

c 38.80 55.59 1.62 0.26 2.13 2.26

Pressed Cement

Powder MgO ai2o

3

sio

2 ^3 CaO Fe

2°3

634 a 3.30 5.21 20.73 2.21 62.58 2.84

b 3.12 4.97 20.77 2.14 62.56 2.71

c 3.15 4.93 20.67 2.23 62.26 2.64

NOTE: under method a = Chemical values In weight percent.

b = COAL (Comprehensive Lachance Algorithm),

c = NRLXRF.

259
25. Final Measurements and NBS Certification of Thin-Glass Standard Reference

Samples for X-ray Spectrometry and Microanalysis (15601)

P. A. Pella, E. B. Steel

X-ray fluorescence spectrometry is a versatile and rapid method for the

multi-element analysis of many substances in the form of deposits on a filter,

mesh or membrane, or as thin pressed pellets. Collected airborne particulate

matter, particulates in waste water, and geochemical samples are just a few

examples of this type. The absence of any sizable interelement effects in

such "thin samples" makes possible a linear instrument response to element

mass-per-unit-area for most elements except low atomic number elements such

as aluminum and silicon. For such applications, thin standard reference

materials are required for calibration of instrument response where the

element mass loading and uniformity across the film diameter are known within

acceptable limits. Several types of thin standard materials are available

from commercial sources, but the accuracy of these materials is not traceable

to any NBS standard as yet. Our efforts at NBS over the past several years

have been to provide a reference material that has several advantages over presently available commercial ones. The method of focused-ion beam sputtering was investigated and found to be ideal for producing thin multielement standards for this purpose. Our proposed standards consist of several elements

dissolved in a glassy matrix.

In a previous report [1], we described the status of our thin-glass

standards program. Essentially we found that in one set of thin glass films

the radial inhomogeneity across the film diameter was severe, especially for

lead (e.g. ^25%). This year, these problems were overcome through the use of

a planetary substrate holder designed and fabricated at NBS. Electron probe

microanalysis of films fabricated using the planetary holder where the electron

beam was stepped in 1 mm increments across the film diameter showed that the

elements were distributed at random across the film with no observable systematic trends, in marked contrast with previous samples when only sample rotation was used. For example, the relative standard deviation based on 35 measurements across the film diameter was 1.5 percent for lead and 5 percent for zinc. The

combination of sample rotation and planetary motion of each sample along its own axis is the key to preparing high quality uniform films independent of

elemental composition. Several in-house methods are currently being employed

for NBS certification of both sets of thin glass films. These include ICP,

AA, INAA, and IDMS. In addition, selected samples from both sets have been

submitted to five cooperating laboratories for analysis by energy-dispersive

x-ray spectrometry. A protocol for the analysis has been established at NBS

according to a well-defined statistical plan. We expect to receive and

compile all analytical data by the end of the fiscal year, and hope to have

both sets NBS-certified and available for sale by January 1, 1983.

References

[1] NBSIR-82-2620, page 209.

260
C. Outputs and Interactions

(Gas and Particulate Science Division)

1. Publications

Bright, D. S. and Fletcher, R. A., "New Portable Ambient Aerosol Sampler,"

Journal of Am. Ind. Hygiene Assoc. 44 (7) 523 (in press).

Bright, D. S. , Myklebust, R. L. and Newbury, D. E., "Stereo Presentation of

Monte Carlo Electron Trajectory Simulations," (in preparation).

Cadoff, B. C. and Hodgeson, J., "Passive Sampler for Ambient Levels of

Nitrogen Dioxide, Anal . Chem . (1983).

Currie, L. A., "Contemporary Particulate Carbon," in: Particulate Carbon:

Atmospheric Life Cycle, G. T. Wolff and R. L. Klimisch, eds., General

Motors Research Laboratories, (1982).

Schell, W. R., Swanson, J. R. and Currie, L. A., "Anthropogenic Changes in

Orqanic Carbon and Trace Metal Input to Lake Washington," Radiocarbon

29, 621 (1983).

Currie, L. A., Klouda, G. A., Continetti, R. E., Kaplan, I. R. , Wang, W. W.,

Dzubay, J. G. , and Stevens, R. K. , "Of the Orgin of Carbonaceous Particles

in American Cities: Results of Radiocarbon "Dating" and Chemical

Characterization," Radiocarbon 25 , 603 (1983).

Currie, L. A., Gerlach, R. W. , Klouda, G. A., Ruegg, F. C. and Tompkins, G. B.,

"Miniature Signals and Miniature Counters: Accuracy Assurance via Microprocessors and Multi parameter Control Techniques," Radiocarbon (in press).

Voorhees, K. J., Schulz, W. D. , Currie, L. A. and Klouda, G. A., "An Investigation of the Insoluble Carbonaceous Material in Airborne Particulates from

Vehicular Emissions," (submitted to Anal. Chem).

Randall, R. , Schjoldager, J., Currie, L. A., Moller, M. , Hassenoff, E.,

Klouda, G. A. and Afheim, I., "Air Pollution from Wood Combustion:

Ambient Air Measurements in Elverum, Norway,: (submitted to Environmental

Science & Technology) .

Currie, L. A., Gerlach, R. W. , Lewis, C. W. , Balfour, W. D. , Cooper, J. A.,

and Dattner, S. L. , "Interlaboratory Comparison of Source Apportionment

Procedures: REsults for Simulated Data Sets," (submitted to Atmospheric

Environment ).

Kagann, R. H. and Elkins, J. W. , "Absolute Band Strengths of Halocarbons F-ll

and F-12 in the 8-10 um Reqion," J. of Geophysical Res., 88 (2) 1427-1432

(1983).

Fried, A. and Lin, H-B. , "Application of Photothermal Techniques for Trace

Detection of N02 in the Troposphere," NASA Workshop Publication (1983).

261
Fried, A. and Berg, W. , "Photoacoustic Detection of HC1," Opt. Lett., 8 (3)

160 (1983).

Fried, A., Sams, R. and Berg, W. , "Detection of HC1 at the Sub-Parts-Per

Billion Level Using Tunable Diode Laser Absorption," Proceedings

of the Society of Photo-Optical Instrumentation Engineers: Tunable

Diode Laser Development and Spectroscopy Applications, 438 (1983).

Fletcher, R. A. and Bright D. S., "NBS Portable Ambient Particulate Sampler,"

Final Report for the Environmental Protection Agency, NBSIR-2561 (1983).

Fletcher, R. A., "Chemical Surface Analysis on Particles Using the LAMMA,"

J. Aerosol Science and Technology , 2 , 156 (1983).

Solomon, P. A., Moyers, J. L. and Fletcher, R. A., "A High Volume Dichotomous

Virtual Impactor for the Fractionation and Collection of Particles

According to Aerodynamic Size," J . Aerosol Science and Technology

(in press).

Fletcher, R. A., Chabay, I., Weitz, D. , and Chung, J., "Laser Desorption

Mass Spectroscopy of Surface-Adsorbed Molecules," Chem. Phys. Letts.

(submitted).

Gerlach, R. W., Currie, L. A. and Lewis, C. W. , "Review of the Quail Roost II Receptor Model Simulation Exercise," in Proc. APCA Speciality Conference

on Receptor Models Applied to Contemporary Air Pollution (1983).

Hughes, E. E. , "Nitric Oxide in Nitrogen Appendix D to "A Procedure for

Establishing Traceability of Gas Mixtures of Certain National Bureau

of Standards SRM's," NBS EPA Joint Report EPA-600/7-81-010, (1981).

Ibid, "Sulfur Dioxide in Nitrogen," Appendix E

Ibid, "Propane in Air or Nitrogen," Appendix F

Hughes, E. and Myers, R. , "Measurement of the Concentration of Sulfur

Dioxide, Nitrogen Oxides and Ozone in the National Archives Bldg."

NBSIR (In review).

Klouda, G. A., Currie, L. A., Gerlach, R. W. , Continetti, R. E. and

Tompkins, G. B., "Estimating the Impact of Atmospheric Carbonaceous

Particulates on Urban and Rural Enviornments by Radiocarbon Measurements," Proc. Residential Wood and Coal Combustion Specialty

Conference of Air Pollution Control Association 189-206 (1982).

Marinenko, R. B., Steel, E. B., Small, J. A., and Newbury D. E., "Standards

for Microbeam Analysis, Bull, of the Electron Microscopy Soc. of Am.,

13_ (1) 67 (1983).

262
Liu, B. Y. H., Pui, D. Y. H., McKenzie, R. L., Argawal , J. K. , Janicke, R.

,

Pohl, F. 6., Preining, 0., Reischl, G., Szymanki , W. , and Wagner, P. E.,

"Intercomparison of Different "Absolute" Instruments for Measurement

of Aerosol Number Concentration," J. Aerosol Science 13 , 429-450 (1982).

McKenzie, R. L. , Bright D. S., Fletcher, R. A., and Hodgeson, J. A.,

"Development of a Personal Exposure Monitor for Two Sizes of Inhalable

Particulates," Environ. Internat. 8, 229-233 (1982)

Camp, D. C., Stevens, R. K. , Cobourn, W. G., Husar, R. B., Collins, J. F.

,

Huntzicker, J. D. , Husar, J. D. , Jaklevic, J. M. , McKenzie, R. L.,

Tanner, R. L., and Tesch, J. W. , "Intercomparison of Concentration

Results from Fine Particle Sulfur Monitors," Atmos. Environ. 16,

911-916 (1982).

Liu, B., Pui, D. , McKenzie, R. L. , Argawal, J. K. , Pohl, F. G., Preining, 0.,

Reischl, G. , Szymanski, W. , and Wagner, P. E., "Measurement of KelvinEquivalent Size Distributions of Well-Defined Aerosols with Particle

Diameters above 13 nm," (submitted to Aerosol Science And Technology)

Myklebust, R. L. , Pella, P. A. and Thorne, B., "An Overview of EXFNBS - A

Data Reduction Procedure for Energy-Dispersive XRF with Secondary

Target Excitation," X-Ray Spectrometry , 2 (4) 170-172 (1982).

Myklebust, R. L., "An Evaluation of X-Ray Loss Due to Electron Backscatter"

,

10th International Cong, on X-Ray Optics and Microanalysis, Toulouse,

France (1983).

Kelley, R. D. , Candela, G. A., Madey, T. E., Newbury, D. E. and Schehl

,

"Surface and Bulk Analysis of a Deactivated Raney Nickel Methanation

Catalyst," J. Catalysis 80 , 235-248 (1983).

Dunn, P. J. and Newbury, D. E. , "Loudonite: A New Zirconium Silicate from

Virginia" Canadian Mineralogist 21 , 37-40 (1983).

Newbury, D. E. , "Recent Developments in Microbeam Analysis," Proceedings of the

Electron Microscopy Society of Southern Africa, 12^ 5-8 (1982).

Joy, D. C. , Newbury, D. E. , and Myklebust, R. L., "The Role of Fast Secondary

Electrons in Degrading Spatial Resolution in the Analytical Electron

Microscope," J. Microscopy 128 (1982).

Newbury, D. E. , Myklebust, R. L. , Romig, A. D., Jr., and Bieg, K. W., "Determinatio of the Depth Distribution of X-ray Generation, i (pz), for Tilted

Specimens of Au in the Analytical Electron Microscope," Microbeam

Analysis/1983 (San Francisco Press, 1983)

Butrymowicz, D. B. , Piccone, T. J., Manning, J. R. , and Newbury, D. E., "Color

Metallography of Diffusion -- Induced Grain Boundary Migration in Cu-Zn

and Cu-As Alloy, (submitted to Inti. J. Metallography).

263
Taylor, H. F. W. and Newbury, D. E., "Calcium Hydroxide Distribution and

Calcium Silicate Hydrate Composition in Tircalcium Silicate and betaDicalcium Silicate Pastes," (submitted to Cement and Concrete Research).

Williams, D. B. and Newbury, D. E., "Recent Advances in the Electron Microscopy

of Materials," (submitted to Advances in Electronics and Electron Physics)

Small, J. A. and Steel, E. B., "Reference Filter Standards for the Analysis

of Chrysotile Asbestos in Non-Workplace Environments (to be published in

the Proc. of the 4th Inti. Conf. on Dust Measuring Technique and

Strategy, Edinbourgh, Scotland 1982).

Small, J. A., "Limits of Visibility for Chrysotile Asbestos in the Scanning

Electron Microscope, (to be published in the Proc. of the 4th Inti.

Conf. on Dust Measuring Technique and Strategy, Edinbourgh, Scotland 1982)

Small, J. A., Newbury D. E. , and Myklebust, R. L., "The Visibility of Asbestos

Fibers in the Scanning Electron Microscope, Microbeam Analysis (1982)

San Francisco Press, Ed.

Small, J. A., Norris, J. A., and McKenzie, R. L., Fabrication of Metals and

Metals Alloys as Particle Standards, Microbeam Analysis (1983)

San Francisco Press, Ed.

Small, J. A. and Newbury, D. E., "The Visibility of Serpentine and Amphibole

Asbestos in the Scanning Electron Microscope and the Scanning Transmission Electron Microscope, (submitted to the J. of Microscopy ).

Small, J. A, Newbury, D. E., Leigh, S. D. , and Myklebust, R. L. , "Development

of an Analytical Expression for the Generation of Bremsstrahlung in

Pure Element Targets (submitted).

Small, J. A., Steel, E. B. and Leigh, S. D. , "The Development of Filter

Standards for the Analysis of Chrysotile Asbestos at Non-Workplace

Environments (submitted to Anal. Chem. ).

Conzemius, R. J., Simons, D. S., Shankai , Z. , and Byrd, G. D., "Laser

Spectrometry of Solids: A Bibliography 1963 - 1982," Microbeam

Anaylsis (1983), R. Gooley, Ed.

Finkelman, R. B., Simons, D. S., and Dulong, F. T. , "Semi-Quantitaitve

Ion Microprobe Mass Analyses of Mineral -rich Particles in the Upper

Freeport Coal, " (accepted for publication in Coal Geology (1983)

Simons, D. S., "Isotopic Analysis with the Laser Microprobe Mass Analyzer,"

(accepted for publication in the Inti . vh_ of of Mass S pectrometry and

Ion Physics (1983).

Stallard, B. R. , Champion, P. M., Callis, P. R. , and Albrecht, A. C., "Some

Advances in Calculating Raman Excitation Profiles by Means of the

Transform Theory," J. Chem. Phys. 78 712 (1983).
Lewis, A., Grubb, S. and Stallard, B. R. , "Raman Difference Studies of

Isotopically Labeled Bacterial Rhodopsin," (submitted to Biochemistry).

Stallard, B. R. , Champion, P. M. and Albrecht, A. C., "The Inverse Transform

in Resonance Raman Scattering," (submitted to J. Chem. Phys. ).

Pella, P. A., Kingston, H. M. Sieber, J. R. and Feng, L., "Effect of

Sample Dissolution Procedures on X-ray Spectrometric Analysis of

Biological Materials," Anal. Chem. 55 1193 (1983).

Pella, P. A., Feng, L., and Small, J. A., "An Analytical Algorithm for

Calculation of Spectral Distributions of X-Ray Tube Emission for

Quantitative X-Ray Spectrometry," (submitted for publication)

Zielinski, W. L. , "A Summary of Activities Concerning Coal Gasification

and Liquidfaction at the National Bureau of Standards 1976 -1980."

EPA-600/7-82-002 (1982).

Zielinski, W. L. , "Recent Research Trends in Environmental Measurements,"

Trends in Analytical Chemistry 2 (5) XI-XII (1983).

2. Talks

Cadoff, B. C. , "Applications of FTIR and Reaction Modeling to Problems of

Instability of NO in N 9 Gas Mixtures," 25th Rocky Mountain Conference,

Denver, CO (8/15/83).

c

Cadoff, B. C., "Design and Construction of Constant Flow Sampling Systems,"

1983 Federation of Analytical Chemistry and Spectroscopy Societies

( FACCS) , Philadelphia, PA (9/29/83).

Currie, L. A., "Identification & Quantification of the Sources of Ambient

Particulate Matter by Receptor Oriented Techniques," APCA Specialty

Meeting, Danvers, MA (10/18/82).

Currie, L. A., "The Analytical Measurement Process: Assumptions and Realistic Measures of Uncertainty," Symposium on Improving the Analytical

Chemistry/Regulatory Interface, NBS, Gaithersburg, MD (10/20/82).

Currie, L. A., "Radiocarbon Dating of Atmospheric Particles," Oak Ridge

National Labs, Oak Ridge, TN (1/10/83).

Currie, L. A., "The Many Dimensions of Detection in Trace Analysis," ACS

Symposium The Role of Chemonetrics in Pesticide Analysis, Seattle, WA

(3/23/83).

Currie, L. A., "Detection and Quantitation in Nuclear and Analytical Chemistry," Colorado State University, Fort Collins, CO (6/3/83).

Dorko, W. and Fried, A., "Certification of High Concentration Level Nitrogen

Dioxide in Air Gas Standards," 185th American Chemical Society National

Meeting, Seattle, WA (3/20-25/83).

265
Downing, R. G. , "Neutron Depth Profiling at the National Bureau of Standards," Sixth International Conference on Ion Beam Analysis, Arizona

State University, Tempe, AZ (5/23/83).

Elkins, J. W., "Gas Analysis by Fourier Transform Infrared Spectroscopy,"

2nd NBS-ADABSE Analytical Chemistry Workshop, (10/25-26/82).

Elkins, J. W., Sams, R. L., Kagann, R. H., "Infrared Band Strengths Measurements for Halocarbons F-ll, F-12, CF., and ChLCl in the "Atmospheric

Windows", American Geophysical Union, Baltimore, MD (6/2/83).

Fletcher, R. A., "Chemical Surface Analysis on Particles Using the LAMMA,"

American Association for Aerosol Research Conference, Washington, D.C.

(4/83).

Fletcher, R. A., "Laser Desorption of an Organic Monolayer from a 50A Thin

Silver Film," Texas Symposium oh Particle Induced Desorption Mass Spectrometry, College Station, TX (5/83).

Marinenko, R. B. , Blackburn, D. H., "Glasses for Microanalysis: New NBS

Standard Reference Materials," 10th International Congress on X-ray

Optics and Microanalysis, Toulouse, France (9/83).

Mitchell, G. D. , "Origin of Entropies in Polymeric Permeation Devices,"

Southern University, Baton Rouge, LA (3/11/83).

Mitchell, G. D., "The Metrology of Gases: High Accuracy C0« Analysis,"

Southern University, Baton Rouge, LA (3/11/83).

Mitchell, G. D. , "Cross-Coupled Interaction of Thermal, Electrical, Mechanical, and Chemical Parameters of Polymeric Permeation Devices," 185th

American Chemical Society National Meeting, Seattle, WA (3/20-25/83).

Mitchell, G. D., "Primary and Secondary Contribution to Entropy-Related

Parameters in Polymeric Permeation Devices," Norfolk State College,

Norfolk, VA (4/29/83).

Mitchell, G. D., "Cross-Coupled Interaction of Thermal, Electrical, Mechanical

and Chemical Parameters of Polymeric Permeation Devices," National

Meeting, National Organization of Black Chemists and Chemical Engineers,

Knoxville, TN (5/27/83).

Newbury, D. E. , "Ion Microscopy for Compositional Mapping." NIH Biomedical

Instrumentation Symposium, Washington, DC (11/17/83).

Newbury, D. E., "Electron Probe Microanalysis of Failures in Aluminum Wire

Electrical Junctions," University of Port Elizabeth, South Africa

(11/29/82).

Newbury, D. E., "Recent Developments in Microbeam Analysis," Electron Microscopy Society of Southern Africa, Rhodes University, Grahamston, South

Africa (12/21/82).

266
Newbury, D. E., "Electron Beam Microanalysis of Particles and Rough Surfaces,"

Department of Metallurgy, Univeristy of CapeTown, South Africa (12/6/82).

Newbury, D. E., "Microbeam Mass Spectrometry," Anglo American Research Labs,

Johannesburg, South Africa (12/8/82).

Newbury, D. E., "Quantitative Electron Probe Microanalysis With the Energy

Dispersive X-ray Spectrometer," Physics Department, University of Witswatersrand, Johannesburg, South Africa (12/8/82).

Newbury, D. E., "Mass Spectrometry at High Spatial Resolution," Commonwealth

Science and Industrial Research, Pretoria, South Africa (12/10/82).

Newbury, D. E., "Accuracy of Microprobe Analysis," Workshop on Evaluation of

Binary Alloy Phase Diagrams, NBS, Gaithersburg, MD (1/31/83).

Newbury, D. E.

, "Microprobe Analysis Methods for Quantitative Materials Characterization," Alloy Phase Diagrams Conference, NBS, Gaithersburg, MD

(3/83).

Newbury, D. E., "Microbeam Analysis for Particle Characterization," International Congress on X-ray Optics and Microanalysis, Toulouse, France

(9/5/83).

Pella, P. A., "X-ray Spectrometric Analysis of NBS^SRM Bovine Lever and Pine

Needles After Separation and Preconcentration," ACS, Division of Analytical Chemistry, Seattle, WA (3/23/83).

Pella, P. A., "Approach to Calculation of X-ray Tube Spectral Distributions

for X-ray Analysis," 23rd Colloquium Spectroscopi cum Internationale,

Amsterdam, The Netherlands (6/28/83).

Pella, P. A., "The Application of Chelex-rlOO and 5A-2 Resins to the Preconcentration of Elements Prior to XRF Analysis," Center for Radiochemistry

and Activation Analysis in Pavia, Italy (7/5/83).

Pella, P. A., "The Application of Chelex*rl00 and SA-2 Resins to the Preconcentration of Elements Prior to XRF Analysis," Institute for Analytical,

Micro-, and Radiochemistry, Technical University of Graz, Graz, Austria

(7/8/83).

Pella, P. A., "The Application of Chelex-100 and SA-2 Resins to the Preconcentration of Elements Prior to XRF Analysis," Institute for Radiochemistry, Nuclear Research Center, Karlsruhe, West Germany (7/12/83).

Simons, D. S., "Isotopic Analysis with the Laser Microprobe Mass Analyzer,"

Microbeam Analysis Society, Washington, DC (8/82).

Simons, D. S., "Microanalysis of Particles by Mass Spectrometry," University

of North Carolina, Chapel Hill, NC (11/1/82).

267
Simons, D. S., "The Laser Microprobe Mass Analyzer in Biomedical Research,"

NIH Biomedical Instrumentation Symposium, Washington, DC (11/17/82).

Invited

Simons, D. S., "Quantitative Compositional Mapping," Special Symposium on NBS

Research, National Bureau of Standards, Gaithersburg, MD (1/10/83).

Invited

Simons, D. S., "Microanalysis Research at NBS," Physics Colloquium, Catholic

University of America, Washington, DC (4/21/83). Invited

Simons, D. S., "Isotopic Analysis by LAMMA," Workshop on Laser Microprobe

Mass Analysis, Research Institute Borstel , Borstel , W. Germany (9/2/83).

Small, J. A., "Analysis of Micrometer and Submicrometer Particles,"

Metropolitan Chapter, Microbeam Analysis Society, Paramus, NJ

(4/28/83).

Small, J. A., "Quantitative Particle Analysis in Electron Beam Instruments,"

Metropolitan Chapter, Microbeam Analysis Society, Paramus, NJ

(4/28/83).

Small, J. A., "Particle Analysis: A Tutorial," Scanning Electron Microscopy

Meeting, Detroit, MI (4/83).

Small, J. A., "Fabrication of Metals and Metal Alloys as Particle Standards,"

Microbeam Analysis Society Meeting, Pheonix, AZ (8/83).

Small, J. A., "Limits of Visibility for Chrysotile Asbestos in the Scanning

ning Electron Microscope," Interantional Conference on Dust Measuring

Techniques and Strategy, Edinbourgh, Scotland (9/82). Invited

Small, J. A., "Reference Filter Standards for the Analysis of Chrysotile

Asbestos in Non-workplace Environments," International Conference on Dust Measuring Techniques and Strategy, Edinbourgh, Scotland (9/82).

Invited

Small, J. A., "Microanalytical Techniques for the Analysis of Particles,"

Microbeam Analysis Society Metropolitan Chapter Meeting, Paramus, NJ

(4/83). Invited

Small, J. A., "Quantitative Analysis of Individual Particles with Electron

Beam Instruments," Microbeam Analysis Society Metropolitan Chapter

Meeting, Paramus, NJ 94/83). Invited

Small, J. A., "Visibility of Asbestos Fibers in the Scanning Electron Microscope," Microbeam Analysis Society Meeting, Pheonix, AZ (8/83). Invited

Zielinski, W. L., Jr., "Recent Developments in Environmental Standard Reference

Materials to Assist Data Quality in Environmental Measurements,"

1972 Eastern Analytical Symposium, New York, NY (11/17-19/82).

268
Zielinski, W. L., Jr., Ulma, G. A., Miller, M. , and Wasik, S. P., "GLC Separation Behavior of Polychlorinated Biphenyl Isomers Between a Neumatic

Liquid Crystal Stationary Phase and a Non-Pol ar Hydrocarbon Phase

(Apolane-87) ," 1983 Pittsburgh Conference on Analytical Chemistry and

Applied Spectroscopy, Atlantic City, NJ (3/7-12/83).

Zielinski, W. L., Jr. and Martire, D. E., "A Stationary Phase-Independent

Predictive Scheme for Retention Data of Solutes in Gas-Liquid

Chromatography," 1983 Pittsburgh Conference on Analytical Chemistry and

Applied Spectroscopy, Atlantic City, NJ (3/7-12/83).

3. Committee Assignments

Harry Rook

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Member, ASTM D-22. 05 Calibration

Member, ASTM D-22. 07 Precision and Accuracy of Methods

Member, Office of Water Data Coordination, Committee 5F

Raymond McKenzie

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Member, ASTM D-22. 03 Monitoring Instrumentation

Member, ASTM D-22. 05 Calibration

Member, ASTM D-22. 07 Precision and Accuracy of Methods

Member, ASTM E-29 Particle Size Measurement

David Bright

Member, ASTM E-29 Particle Size Measurement

Member, ASTM SC. 10 Liquid Particle Measurement

Lloyd Currie

Member, Intersociety Committee - Methods of Air Sampling and Analysis

Member, Model Validation Subcommittee - Receptor Modeling Workshop

Member, CAC Computer Utilization Committee

William Dorko

Member, American Chemical Society, Washington Section, Board of Managers

Edgar Etz

Member, ASTM D-22 Methods of Sampling and Analysis of Atmospheres

Ernest Hughes

Member, IS0/TC 158 Gas Analysis

Member, IS0/TC 158/SC-l Methods for Preparation and Definition of Gas

Mixtures for Calibration

Member, IS0/TC 158/WG-2 Transfer Lines and Sampling

Member, IS0/TC 158/WG-3 Evaluation of the Characteristics of Analysis

Member, IS0/TC 158/WG-4 Analysis of Natural Gas

Member, IS0/TC 158/WG-l Terminology

269
Robert Myklebust

Member, Microbeam Analysis Society (National Council)

Member, ASTM E-2 Emission Spectroscopy

Member, ASTM E-2. 04 Standard Reference Materials

Dale Newbury

Member, Microbeam Analysis Society

Member, Technical Program Committee

Member, ASTM E-42 Surface Analysis

Member, Journal of Microscopy, Editorial Review Board

Member, Scanning, Editorial Review Board

Member, J. Trace and Microprobe Techniques, Editorial Review Board

Member, Sigma Xi

Peter Pella

Member, ASTM E-2 Emission Spectroscopy

Member, ASTM E-2. 02 Statistics, Calibration and Standardization

Gerald SI eater

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Member, ASTM D-22. 06 Source Sampling

Member, ASTM D-22. 07 Precision and Accuracy of Methods

Walter Zielinski

Member, Interagency Committee on C0« and Climate

Member, Stratospheric Ozone Protection

Member, Indoor Air Quality

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Member, Center for Analytical Chemistry Colloquium Committee

4. Other

a. Seminars

April 19, 1983

March 22, 1983

June 28, 1983

Jorgen Schjoldager, Norwegian Inst,

for Air Research, "The Presence of

Photochemical Oxidants in Scandinavia"

(NBS Sponsor: L. Currie)

Joseph P. Krasnecv Demaray Scientific

Inst., "Quality Assurance for Gaseous

SRM Work" (NBS Sponsor: J. Elkins)

Richard Linton, Univ. of North Carolina,

"Dynamic Secondary Ion Mass Spectrometry

of Organic Matrices — Applications to

the Biological and Polymer Sciences"

(NBS Sponsor: D. Simons)

270
b. Standard Reference Materials

X-ray Fluorescence

Steel Alloys

C2400 and C2400A

C2401 and C2401A

C2402 and C2402A

Cl 290 and C1290A

Cl 291 and C1291A

Cl 292

Brass Alloys

C2403

C2404

C2405

C2406

C2408

C2409

C2410

Other

0.5% Austenite in Ferrite

Borosilicate Glass

Glass Sand

Powdered Phosphate Rocks

Powdered Mineral Samples (drilling mud, potential SRM)

271
Gas Metrology Group

1625 Sulfur Dioxide Permeation Tube, 10 cm

1626 Sulfur Dioxide Permeation Tube, 5 cm

1627 Sulfur Dioxide Permeation Tube, 2 cm

1629 Nitrogen Dioxide

1911 Benzene

1658a Methane in Air CH 4 1 ppm

1659a Methane in Air CH4 10 ppm

1660a Methane-Propane In Air CH4 4 ppm

C 3 H 8 1 ppm

1661a Sulfur Dioxide in Nitrogen SO2 500 ppm

1662a Sulfur Dioxide in Nitrogen S02 1000 ppm

1663a Sulfur Dioxide in Nitrogen S02 1500 ppm

1664a Sulfur Dioxide in Nitrogen S02 2500 ppm

1683a Nitric Oxide in Nitrogen NO 50 ppm

1684a Nitric Oxide in Nitrogen NO 100 ppm

1686b Nitric Oxide in Nitrogen NO 500 ppm

1693 Sulfur Dioxide in Nitrogen S02 50 ppm

1694 Sulfur Dioxide in Nitrogen S02 100 ppm

1805 Benzene in Nitrogen CeH6 0.25 ppm

1806 Benzene in Nitrogen C6 H6 10 ppm

1808 Perchloroethylene in N2 1809 Perchloroethylene in N2

2612a Carbon Monoxide in Air CO

2613a Carbon Monoxide in Air CO

2614a Carbon Monoxide in Air CO

0 ..25 ppm

10 ppm

10 ppm

20 ppm

45 ppm

ftU.8. GOVERNMENT PRINTING OFFICE: 1983 421 997 S2S4

272
MRS.114A (REV- 2*8C> - 1. PUBLICATION OR

REPORT NO.

2. Performing Organ. Report No. 3. Publication Date

NBSIR 83-2786 December 1983

U.s. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See in structions)

4. TITLE AND SUBTITLE

Technical Activities, 1983, Center for Analytical Chemistry

5. AUTHOR(S) _ i H. S. Hertz, R. A. Velapoldi, J. K. Taylor

6. PERFORMING ORGANIZATION (If joint or other than NBS, see in struct/on s)

national bureau of standards

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8. Type of Report & Period Covered

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City, State, ZIP)

Same as above.

10. SUPPLEMENTARY NOTES

J Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

This report summarizes the technical activities of the Center

for Analytical Chemistry at the National Bureau of Standards. It

emphasizes activities over the Fiscal Year 1983 in the Laser

Analytical Chemistry Group, the Inorganic Analytical Research

Division, the Organic Analytical Research Division, and the Gas

and Particulate Science Division. In addition, it describes

certain special activities in the Center including quality

assurance and voluntary standardization coordination.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) analytical chemistry; analytical services; gas and particulate science; inorganic

analytical chemistry; organic analytical chemistry; quality assurance; voluntary

standardization.

13. availability

Uni imited ® For Official Distribution. Do Not Release to NTIS

Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

15. Price

USCOMM-DC 8043-P SO
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