NBSIR 86-3468

A 111 Ob 0MA7E1

Genter for

Analytical

Chemistry

QC

100

.U56

86-3468

1986

November 1986

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards
NATIONAL INSTITUTE OF STANDARDS &

TECHNOLOGY

Research Information Center
NBSIR 86-3468

Center for

Analytical

Chemistry

R. A. Durst

H. S. Hertz

J. K. Taylor

R. A. Velapoldi

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory Center for Analytical Chemistry

Gaithersburg, MD 20899

November 1986

k?

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

National Bureau of Standards, Ernest Ambler, Director

TABLE OF CONTENTS

Page

I. CENTER FOR ANALYTICAL CHEMISTRY

A. Center Overview 1 B. Outputs and Interactions 3 C. Voluntary Standardization and Quality Assurance 9 D. Service Analysis 10

II. INORGANIC ANALYTICAL RESEARCH DIVISION

A. Division Overviews 11

B. Selected Technical Reports 22

1. Installation of an Automatic, Multi-Collector Mass

Spectrometer 22

2. The Determination of Lead Isotope Ratios in Some Ancient

Obj ects . 23

3. Ultratrace Elemental and Isotopic Analysis of Os and Re

Using RIMS and Thermal Vaporization 24

4. Quantification of Pulsed Ion Currents Produced in

Resonance Ionization Mass Spectrometry (RIMS) 25

5. Detection of Uranium from Cosmos -1402 in the Stratosphere

by Thermal Ionization Mass Spectrometry 26

6. Progress in the Development of Microwave -Coupled Acid

Dissolution Procedures 29

7. Inductively Coupled Plasma Mass Spectrometric Analysis of

Major and Trace Elements in SRMs Using Isotope Dilution ... 30

8. Improved Laboratory Facilities for Trace Element

Determination 31

9. Development of a Computer-Controlled System for Analytical

Separations by Column Chromatography 32

10. Use of Voltammetry to Detect Electroactive Organic

Products from Microwave-Assisted Wet Ashing 33

11. Absolute Measurement of Aqueous Electrolytic Conductance

Standards 34

12. High Ionic Strength pH Standards Research 35

13. Activation Analysis Using Cold Neutron Beams 37

14. The Determination of Chromium- 50 in Human Blood and Its

Utilization for Blood Volume Measurements 38

15. Evaluation of USDIET-I Total Human Diet Samples for

Nutritional Constituents 39

16. Precision in Routine INAA Over a Two Year Period at NBSR . . 40

17. Determination of Silicon by Fast Neutron Activation

Analysis 41

18. Specimen Banking and Analysis in the National Status and

Trends Program 42

19. Determination of Total Zinc and Selenium in Human

Blood Serum 43

20. Ion Chromatography Coupled to a Direct Current Plasma for

On-Line Matrix Separations 45

21. Measurement of 9 Be- 10 Be Isotope Shifts using Doppler-Free

Resonance Ionization Mass Spectrometry 46

22. Ion-Pairing HPLC/AAS for the Determination of Cr(III) and

Cr(VI) in Natural Water 47

iii
TABLE OF CONTENTS (Continued)

Page

23. Atomic Emission Homogeneity Testing of the New Magnesium

Standard Reference Material, SRM 656 48

24. Real-Time Metal Analysis of Ambient Aerosols 49

25. Error Modeling and Confidence Interval Estimation for

ICP Calibration Curves 50

26. The National Cancer Institute - National Bureau of

Standards Round Robin Data Analysis 52

27. Optical Lifetime Measurements of Laser- Induced Ions in

Flames 53

28. Standard Reference Materials 54

C. Outputs and Interactions 57

III. ORGANIC ANALYTICAL RESEARCH DIVISION

'

A. Division Overview 76

B. Selected Technical Activities 91

1. Analysis of Electrophoretic Protein Patterns of

Human Liver 91

2. Analytical Studies of Commercial Sources of Sodium

Dodecyl Sulfate 91

3. NMR Characterization of Solid Sugars for Use in

Measurements of Enthalpy of Combustion 92

4. Immobilized Enzymes Bound to Inert Supports Retain

Activity 93

5. Honey Protein Patterns from Isoelectric Focusing Allow

Classification by Origin . 93

6 . Development of Bioanalytical Sensors . 94

7. Chronoamperometry in Polymer-Modified Electrodes 95

8. FTIR- Photoacoustic Spectroscopic Characterization of

Thermally Crosslinked and Derivatized Poly-

(vinylpyridinestyrene) Copolymer Film Electrodes 96

9. Catalytic Oxygen- Scrubber Column Developed for the

Reductive Electrochemical Detection of Nitro-PAH in

Diesel Soot 97

10. Determination of Biogenic Thiols Using HPLC with

Electrochemical Detection 98

11. Photodissociation of Ions Generated by Liquid SIMS ........ 98

12. Determination of PAH and Alkylated PAH in Particulate

Extracts Using Negative Ion Chemical Ionization Mass

Spectrometry 100

13. Development of a Confirmatory Chemical Test for Exposure

to 3 -Quinuclidinyl Benzilate (BZ) 101

14. Determination of the Relationship between Dose and Yield

of Radiolytic Products in Irradiated Meats 102

15. Development of a New Definitive Method for Uric Acid 103

16. Determination of Fat Soluble Vitamins using Liquid

Chromatography with UV/Visible Absorbance and Oxidative

Electrochemical Detection 104

17. Characterization of Chemically Modified Substrates by

Small Angle Neutron Scattering . 105

18. Determination of the Molar Absorptivities of Bilirubin

Isomers 106

iv
TABLE OF CONTENTS (Continued)

gage

19. Determination of High Molecular Weight PAH in Coal Tar

Air Particulate Materials 107

20. Development of a Refined IDMS Method for the Determination

of Organic Compounds in CRM Gas Cylinders 108

21. Refined Analytical Procedure for the Determination of

PCBs & Chlorinated Pesticides in Human Liver Samples 109

22. Specimen Banking Activities for the NOAA National Status

and Trends Program Ill

23. Determination of PAH, PCBs, and Chlorinated Pesticides in

Marine Tissue and Sediment Samples 112

24. Reference Laboratory Activities Associated with the

National Cancer Institute Cancer Chemoprevention

Programs 113

25. International Round Robin Study on the Determination of

PAH and Nitro-PAH in Environmental Samples 114

26. Construction of a New Sample Preparation Laboratory 115

C. Outputs and Interactions 117

IV. GAS AND PARTICULATE SCIENCE DIVISION

A. Division Overview 127

B. Selected Technical Activities 141

1. Continuum Radiation Produced in Pure -Element Targets by

10-40 keV Electrons: An Empirical Model 141

2. Defocus Modeling for Compositional Mapping with

Wavelength- -Dispersive X-ray Spectrometry 142

3. Bright Field Image Correction Using Various Image

Processing Tools 143

4. Euclidian Distance Mapping for Shape Characterization of

Alloy Grain Boundaries 144

5. Ion Implantation Artifacts Observed in Depth Profiling

Boron in Silicon by Secondary Ion Mass Spectrometry 144

6. An Evaluation of A High Purity Germanium X-ray Detector

on a 200 kV Analytical Electron Microscope 145

7. Compositional Analysis of Human Cardiovascular Deposits

by Micro-Raman Spectroscopy 146

8. Analysis of Molecular Carbonate by Laser Microprobe Mass

Analyzer 148

9. Ultratrace XRF Analysis with Monochromatic Synchrotron

Radiation - Some Preliminary Observations 148

10. Uncertainties in Mass Absorption Coefficients in

Fundamental Parameter X-ray Fluorescence Analysis 149

11. XRF Analysis of Marine Sediments (NOAA/NBS Specimen Bank)

by Automated Borate Fusion 150

12. Determination of Absorption and Pressure-Broadening

Coefficients for Selected Infrared Transitions of N02 by

Tunable Diode Laser Absorption Spectrometry 151

13. Construction and Characterization of a Highly Accurate

Dynamic N02 Calibration System for NASA's Global

Tropospheric Experiment 152

14. Development of a HN03 Calibration System for Dynamic

Standards in the Parts-Per-Million Concentration Range .... 153

v
TABLE OF CONTENTS (Continued)

Page

15. Re-Investigation of the Gas Phase Titration Reaction

Between NO and 03

: Redetermination of the Absolute

Cross Section of 03 at 254 run 154

16. Technical Accomplishments of a Three-Year NBS-DOE Program

for the Development of Standards and Reference Methodology

for C02 in Air . . 155

17. Assessment of the Air Matrix Effect in the Non-Dispersive

Infrared Analysis of C02 in Air Standards 156

18. Assessment of the Absolute Error in the Use of Primary

Gravimetric Standards for the Development of C02 Air SRMs

for Global Monitoring of Atmospheric C02 Changes 156

19. Characterization of the Temperature Dependence of the

Infrared Band Strengths of Halocarbons F-ll (CC13 F) and

F-12 (CC12 F2 ) Using a Cryogenic Gas Cell and FT-IR

Spectrometry 157

20. Development of a Seventeen- Component NBS -Traceable

Volatile Toxic Organic Gas Standard at 10 ppb for GC-MS

Calibrations 158

21. Development of NBS -Traceable Gas Standards to 1 ppb for

Dry Acid Deposition Studies 159

22. Comparison of Single -Component Standards to MultiComponent Standards for Use in the Analysis of

Natural Gas 160

23. Technical Up-Grade of Analytical Gas Mass Spectrometer .... 161

24. Chemome tries : National and International Activities

Related to Nomenclature, Detection, and Reporting of

Analytical Data 162

25. Microchemical and Isotopic Carbon: Accuracy, Precision

and Applicabilities of an Improved Measurement Process

Coupled to Accelerator Mass Spectrometry .................. 163

26. 14 C in Elemental Carbon and Trace Organics: The

Integrated Air Cancer Project 164

C. Outputs and Interactions 166

vi
I. Center for Analytical Chemistry

Harry S. Hertz, Director

Ranee A. Velapoldi, Deputy Director

Richard A. Durst, Acting 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 reference materials 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 healthrelated 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 of measurement concepts and methods, provision of quality assurance services, and certification of Standard Reference

Materials (SRMs) . The ubiquity of and demand for analytical measurements in

modern society is reflected in the breadth of SRMs produced in the Center.

These reference materials are widely used in such diverse areas as the semiconductor 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 - body fluids, plant and animal tissues, foods,

hazardous chemical wastes, and high-technology materials. Increasingly, 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 needed measurement methods and references materials. As it

is not reasonable to contemplate the development of SRMs 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 research publications and the certification

of reference materials, the Center exerts influence through close contacts with

various communities by means of workshops, symposia, and participation in pro- • fessional societies and voluntary standards committees. Through such contacts,

priorities are established for the development of measurement methods and the

production of reference materials, and mechanisms are set in place for their

effective use.

NOTE: 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 Standards, nor does it imply that the materials or equipment identified are necessarily the best available for the

purpose

1
We are devoting considerable attention in the Center to better definition

of our user communities and the various mechanisms for interacting with these

communities. During the past year members of the CAC staff participated in 235

professional, technical, and standards committees. More than 150 tours of CAC

laboratories took place. We co-sponsored/hosted several conferences, including

a major conference in the area of biotechnology - the annual meeting of the

Electrophoresis Society of the Americas. We have continued the process of

visiting key members of our industrial constituency to obtain direct input to our planning process and to identify chemical measurement needs for the next

few years and for the future. The number of guest scientists performing

research in our laboratories increased by 50% during the past year to 80 guest

scientists. We encourage this mode of interaction and invite researchers to

work with us in areas where unique expertise or instrumentation exists at NBS

In some instances, this research at NBS may include work of a proprietary

nature

In September 1987, we will be sponsoring a symposium on Accuracy in Trace

Analysis -- Accomplishments, Goals, Challenges. We look forward to this

symposium with excitement, and welcome this opportunity to bring together the

chemical measurement community to discuss the problems they are facing and the

solutions which tomorrow's measurement technology must bring.

Directly related to our interactions with user communities is our major

planning effort in chemical measurement services. As part of this activity, we have been seeking advice from constituents on the measurement science, measure- ment technology, and technology transfer needs which the Center must prepare

for today, to deliver relevant services in the 1990' s. We are in the process

of conducting a broad- scale chemical measurement impact study. We invite input

on topics to be included and on mechanisms for demonstrating the value added to

industrial products through measurement. A major factor in our planning is the

realization that 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 nationally accepted measurement 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 between the

provision of currently needed reference materials and research efforts on new

types of reference materials and methods of measurement. The work of the

Center is performed in three Divisions, each focusing upon specific analytes - inorganics, organics, and gases and particles. Within each Division there are several groups representing separate analytical chemical disciplines, e.g., mass spectrometry and electrochemistry. Each Division is responsible for a program in basic and applied research and maintains contacts with appropriate

scientific and user communities.

In the following pages, some of the major recent activities and technical

directions of the Divisions and groups are summarized. Much of the work in

progress is omitted but will be included in subsequent Annual Reports.

2
B. Outputs and Interactions i (Center for Analytical Chemistry)

1 . Publications

Durst, R. A., Chemically Modified Electrode Sensors, Ion- Selective Electrodes,

Vol. 4, E. Pungor and I. Buzas , Eds., Akademiai Kiado, Budapest, 115-

128 (1985).

Durst, R. A., Hertz, H. S., and Taylor, J. K. , Technical Activities 1985 - Center for Analytical Chemistry, NBSIR 85-3272, 189 pages (Nov. 1985).

Durst, R. A., Clinical Electrode Potentiometry : Sources of Error, Reference

Methods and Materials, Direct Piotentiometric Measurements in Blood, W.

Koch, Ed., NCCLS Publication, 143-157 (1985).

Durst, R. A., Blubaugh, E. A., Bushong, W. C., and Shupack, S. I., Thermal

Crosslinking Procedure for Preparing Solvent-Stable Polymer-Film

Electrodes, Anal. Lett., in press.

Durst, R. A., and Blubaugh, E. A., Chemically Modified Electrode Sensors,

Fundamentals and Applications of Chemical Sensors, D. Schuetzle and R.

Hammerle , Eds., ACS Symposium Series #309, Washington, DC, 245-255

(1986).

Durst, R. A., Chemically Modified Electrode Sensors, Proceedings of the

International Symposium on Ion-Selective Electrodes, Zhang, Z.-R., Ed.,

Shanghai, P. R. C., in press.

Durst, R. A. and Yap. W. T. , Effects of Resistance and Capacitance on the

Chronoamperometry of Polymer-Coated Electrodes as Modeled by a Finite

Element Digital Simulation, J. Electroanal. Chem. , in press.

Hertz, H. S., "Accuracy in Clinical Chemistry," Archives of Pathology and

Laboratory Medicine, 1985, 109, 1066-1067.

Hertz, H. S., "An Overview of a National Reference System," A Reference System

for Clinical Enzymology: Proceedings of the Workshop, Bowers, G. N.

Edwards, G. C. , Rand, R. N. , Eds., NCCLS, 1-10 (1986).

Taylor, J. K. , Impact of Instrumentation in Analytical Chemistry, in The

History and Preservation of Chemical Instrumentation . J. T. Stock and

M. V. Orna, Eds., D. Reidel Publishing Co. (1986) pp . 1-10.

Taylor, J. K. , On Validation of Analytical Data, Marine Chem. 18, 115-9 (1986).

Taylor, J. K. , Role of Collaborative and Cooperative Studies in Evaluation of

Analytical Methods, J. Ass. Off. Anal. Chem. 69, 398-400 (1986).

Taylor, J. K. and Kratochvil, B., Sampling, in Metals Handbook . 9th Edition,

Vol. 10, American Soc . for Metals, Metals Park, OH (1986) pp . 12-18.

Taylor, J. K. , A Collection of Abstracts of Selected Publications Related to

Quality Assurance of Chemical Measurements, NBSIR 86-3352, April 1986.

3
Taylor, J. K. , Ed., Summary Report of NOAA-NBS Quality Assurance Workshop,

NBSIR 1986.

Velapoldi, R. A., Liquid Standards in Fluorescence Spectrometry, Conference

Proceedings, "Advances in Standards and Methodology in Spectrophotometry,"

Elsevier Publishing Co., The Netherlands, Accepted for Publication.

Velapoldi, R. A., Christy, A. A., Karstang, T. , Kvalheim, 0. M. , Sletten, E. , and Telnaes, Multivariate Calibration of Diffuse Reflectance Infrared

Spectra of Coals as an Alternative to Rank Determination by Vitrinite

Reflectance, Chemometrics and Intelligent Laboratory Systems, Accepted for

Publication.

Welch, M. J., Cohen, A., Hertz, H. S., Ng, K. J., Schaffer, R. , Van Der Lijn,

P. , and White V, E. , Determination of Serum Creatinine by Isotope Dilution

Mass Spectrometry as a Candidate Definitive Method, Analytical Chemistry,

1986, 58, 1681-1885.

2. Talks

Christy, A. A. and Velapoldi, R.A. , "Diffuse Reflectance Spectroscopy" and

"Coal Maturity by Diffuse Reflectance FT-IR," Chemistry Dept., University

of Bergen, Bergen, Norway, March 1986. Invited

Christy, A. A. and Velapoldi, R. A., "Multivariate Calibration of Diffuse

Reflectance FT-IR Spectra of Coals as an Alternative to Rank Determination

by Vitrinite Reflectance, Conference on Chemometrics for Geologists,

Ulvik, Norway, April 1986.

Durst, R. A., "Chemically Modified Electrode Sensors," Chemistry Department

Seminar, Occidental College, Los Angeles, CA, January 17, 1986.

Invited

Durst, R. A., "Electrochemistry," NBS-ADABSE Analytical Chemistry Workshop,

National Bureau of Standards, April 16, 1986. Invited

Hertz, H. S., "Analytical Chemistry: State-of- the-Practice , State-of - the -Art

and the Importance of Each," Baton Rouge Analytical Instrument Discussion

Group (BRAIDG) , Baton Rouge, LA, October 2, 1985. Invited

Hertz, H. S., "NBS Chemical Measurement Services/Standard Reference Materials",

Eli Lilly and Company, Indianapolis, IN, October 3, 1985. Invited

cHertz, H. S., "An Overview of a National Reference System," National Committee

for Clinical Laboratory Standards and the National Reference System for

the Clinical Laboratory, Workshop on a National Reference System for

Clinical Enzymology, Arlington, VA, October 16, 1985. Invited

Hertz, H. S., "Opportunities in Chemistry at NBS," National Academy of

Sciences, Washington, DC, October 22, 1985. Invited

Hertz, H. S., "The What, Why, and How of Future Chemical Measurements," CENTCOM

Breakfast, 37th Pittsburgh Conference on Analytical Chemistry and Applied

Spectroscopy, Atlantic City, NJ , March 11, 1986. Invited

4
Hertz, H. S., "Implementing a Quality Assurance Program," 37th Pittsburgh

Conference on Analytical Chemistry and Applied Spectroscopy, Atlantic

City, NJ , March 13, 1986. Invited

Hertz, H. S., "Laboratory Standards: 1) NBS Standard Reference Materials and

QA Program, 2) Overview of the National Committee for Clinical Laboratory

Standards Program," Association of State and Territorial Public Health

Laboratory Directors, Charleston, S. Carolina, April 8, 1986. Invited

Hertz, H. S., "Current Research in Analytical Chemistry at NBS," The Procter

and Gamble Company, Cincinnati, Ohio, July 24, 1986. Invited

Hertz, H. S., "The Clinical Laboratory Voluntary Standards Process in the

U.S.," European Committee for Clinical Laboratory Standards Annual General

Meeting, Cophenhagen, Denmark, August 12, 1986. Invited

Hertz, H. S., "Isotope Dilution Mass Spectrometry, An Accuracy Tie Point for

the Clinical Chemistry Measurement System," Sixth International Symposium

on Mass Spectrometry in the Life Sciences, State University of Ghent,

Belgium, September 2, 1986. Invited

Taylor, J. K. , "Quality Assurance of Chemical Measurements," LANL-NBS, Los

Alamos, NM, October 2-3, 1985. Invited

Taylor, J. K. , "Long-term Goals for Quality Assurance," NBS-NOAA Workshop,

National Bureau of Standards, December 6, 1985. Invited

Taylor, J. K. , "The Critical Relation of the Sample to Environmental Decisions," European Community Sampling Conference, Bilthoven, The

Netherlands, January 21, 1986. Invited

Taylor, J. K. , "The Role of Reference Materials in Environmental Analysis,"

European Community Sampling Conference, Bilthoven, The Netherlands,

January 22, 1986. Invited

Taylor, J. K. , "Statistics for Chemists," Pittsburgh Conference, Atlantic City,

NJ , March 14, 1986. Invited

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

Conference, Atlantic City, NJ , March 14, 1986. Invited

Taylor, J. K. , "Relation of Data Quality to Detection," -ACS Meeting, New York,

NY, April 16, 1986. Invited

Taylor, J. K. , "ACS Principles for Environmental Analysis, Recommendations for

Reporting Low-Level Data," ACS Meeting, New York, NY, April 16, 1986.

Invited

Taylor, J. K. , "Planning for Quality Data - IX Conference on Chemistry of the

Mediterranean Sea," Primosten, Yugoslavia, May 7, 1986. Invited

Taylor, J. K. , "Principles of Quality Assurance," Quebec Association for

Advancement of Science, Montreal, Canada, May 12, 1986. Invited

Taylor, J. K. , "Why Data Quality is so Important," Virginia Military Institute,

Lexington, VA, July 19, 1986. Invited

5
Velapoldi, R. A., "Spectroscopy and Geology," Geology Division, Norsk Hydro,

Bergen, Norway, January 1986.

Velapoldi, R. A., "Diffuse Reflectance FT-IR," Instrumentation Group, Norsk

Hydro, Bergen, Norway, February 1986.

Velapoldi, R. A., "Total Internal Reflection FT-IR of Drilling Fluids," Well

Technology Division, Norsk Hydro, Bergen, Norway, July 1986.

Velapoldi, R. A., Liquid Standards in Fluorescence Spectrometry, Conference on "Advances in Standards and Methodology in Spectrophotometry," Held at

Keble College, Oxford, September 16, 1986. Invited

3 . Committee Assignments

Harry S. Hertz

President, National Committee for Clinical Laboratory Standards

Chairman, Education Committee, American Society for Mass Spectrometry

Member, ASTM, Committee D19 on Water

Committee E48 on Biotechnology

Member, Analytical Laboratory Managers' Association

Member, Department of Energy, Health and Environmental Research

Advisory Committee

Analytical Chemistry Editorial Advisory Board

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

Calibration of Instruments Meant for Checking Substances During

Medico -Biological and Research Analyses

Richard A. Durst

Member

Member

Member

Member

Member

Member

ASTM, Committee D19 on Water

ASTM, Committee E-48 on Biotechnology

Board of Advisory Editors, Ion-Selective Electrode Reviews

IUPAC, Committee V on Analytical Chemistry

Subcommittee 5 on Electroanalytical Chemistry

Member, NCCLS , Subcommittee on Electroanalytical Methods

Subcommittee on pH and Blood Gases

NBS , Research Advisory Committee

DoC, Biotechnology Working Committee

John K. Taylor

Member, IS0/TC48, Glassware and Related Apparatus

ISO/TC48/SC01, Volumetric Glassware

IS0/TC146, Air Quality

IS0/TC146 . 01 , Stationary Source Emission

IS0/TC146 . 02 , Work Place Atmospheres

IS0/TC146 . 03 , Ambient Atmospheres

IS0/TC146 . 04 , General Aspects

Chairman, ASTM D19.01, International Standards

ASTM D22, Sampling and Analysis of Atmospheres

Member, ASTM D19 , Water

ASTM DIO. 02, General Specifications and Technical Resources

ASTM D19.05, Inorganic Constituents in Water

ASTM D19.07, Sediments

ASTM D22.01, Quality Control

ASTM D22.02, Source Measurements

ASTM D22.03, Ambient Measurements

6
ASTM D22.04, Analysis of Work Space Atmospheres

ASTM D22.05, Indoor Atmospheres

ASTM D22.06, Acid Deposition

ASTM D22.09, ISO TAG for ISO/TC146

ASTM E34, Occupational Safety and Health

ASTM E36, Criteria for the Evaluation of Testing and/or

Inspection Agencies

ASTM E36.10, Generic Criteria

ASTM E36.30, Nomenclature and Definitions

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 Representative - Interagency Advisory Committee on Water Data

4 . Courses Taught

Harry S . Hertz

"Interpretation of Mass Spectra," ASMS Annual Conference on Mass

Spectrometry and Allied Topics, Cincinnati, OH, June 7-8, 1986.

John K. Taylor

"Quality Assurance of Chemical Measurements," Shell Development, ACS Short

Course, Houston, TX, October 8-10, 1985.

"Quality Assurance of Chemical Measurements," Nuclear Regulatory Commission, National Bureau of Standards, Gaithersburg, MD, October 29-31,

1986.

"Quality Assurance of Chemical Measurements," EPA-Region II, National

Bureau of Standards, Edison, NJ , November 13-14, 1985.

"Quality Assurance of Chemical Measurements," National Bureau of

Standards, December 3-4, 1985.

"Quality Assurance of Chemical Measurements," Ratheon, ACS Short

Course, Grande Isle, MI, December 10-11, 1985.

"Quality Assurance of Chemical Measurements," United Technologies, ACS

Short Course, West Palm Beach, FL, February 5-6, 1986.

"Quality Assurance of Chemical Measurements," Atlantic City, NJ , ACS Short

Course, March 8-9, 1986.

"Quality Assurance of Chemical Measurements," ALCOA, ACS Short Course,

Pittsburgh, PA, April 20-21, 1986.

"Quality Assurance of Chemical Measurements," Alberta Environmental

Center, ACS Short Course, June 18-19, 1986.

"Quality Assurance of Chemical Measurements," Tri-Cities University, ACS

Short Course, Edmonton, Canada, June 25-26, 1986.

"Quality Assurance of Chemical Measurements," ACS Short Course, Anaheim,

CA, September 6-7, 1986.

"Quality Assurance of Chemical Measurements," ACS Short Course, St. Louis,

MO, September 26-27, 1986.

7
5. Sessions Chaired

Harry S . Hertz

"Quantitative Mass Spectrometry," Sixth International Symposium on Mass

Spectrometry in the Life Sciences, Ghent, Belgium, September 2, 1986.

6 . Center Colloquium Series

October 30, 1985 Dr. Louis Meites, Chairman Department of Chemistry,

George Mason University, Fairfax, Virginia,

"Thermometric Titrimetry Through the Ages."

November 13, 1985 Dr. Douglas Donahue, Department of Physics, University of Arizona, Tucson, Arizona, "Application of

Accelerator Mass Spectrometry to Some Problems in

Archeology and Geophysics."

April 9, 1986 Dr. Catherine E. Costello, Department of Chemistry

Massachusetts Institute of Technology, Cambridge,

Massachusetts, "Adventures with a New High- Field

Four-Sector Mass Spectrometer."

May 14, 1986 Dr. George Morrison, Department of Chemistry, Cornell

University, Ithaca, New York, "Ion Microscopy in

Biology and Medicine."

May 15, 1986 Dr. Dennis Schuetzle, Chemical Analysis Research

Department, Ford Motor Company, Dearborn,' Michigan,

"Recent Advances in ESCA and SIMS."

June 11, 1986 Dr. Jeannette Grasselli, Research and Development

Division, Standard Oil Company (SOHIO) , Cleveland,

Ohio, "The Challenge and Opportunity for Analytical

Chemistry in Industry."

September 10, 1986 Dr. Edmund R. Malinowski, Department of Chemistry and

Chemical Engineering, Stevens Institute of

Technology, Hoboken, New Jersey, "Introduction to

Factor Analysis in Analytical Chemistry."

8
c. Voluntary Standardization and Quality Assurance

1. Voluntary Standardization

John K. Taylor

The Center continues to play an important role in standardization

activities. Twenty-nine members of the staff hold 154 memberships on standards

committees, including positions of leaderships on 10 of these, as follows:

ASTM C-26

ASTM D- 19

ASTM D-22

ASTM E-02

ASTM E-03

ASTM E-07

IS0/TC146

ISO/TC147

IUPAC

NCCLS

Nuclear Fuel Cycle

Water

Sampling and Analysis of Atmospheres

Emission Spectroscopy

Chemical Analysis of Metals

Nondestructive Testing

Air Quality

Water Quality

Commission on Atomic Weights

National Committee for Clinical Laboratory Standards

Leadership was provided in organizing the 1986 Johnson Conference of ASTM

Committee D22 on Sampling and Analysis of Atmospheres. The conference dealt

with the currently important issues of asbestos measurement, indoor air

monitoring, and the analysis of acid rain. Five center scientists made

important contributions to this conference - a number of Center scientists also

are cooperating with the USA Reporting Secretariat PS17/R52 of International

Organization for Legal Metrology in developing performance standards for

analytical instrumentation of pollution monitoring.

2 . Quality Assurance

The Center's program to provide quality assurance education and assistance

to other government agencies and ‘to the public has been very active during the

past year. A key feature of this is the Quality Assurance Seminar series

initiated in 1983. These seminars are of two types: those held at NBS consist

of 10 hours of lectures and 4 hours of small -group discussions (mini -workshops)

in selected measurement areas; those presented away from NBS consist entirely

of 16 hours of lectures given during a two-day period. Essentially the same material is presented in the lectures of both seminars, except that the content

is enlarged in the case of the latter type. One seminar of the first type was presented at NBS with an attendance of 45 persons. A special seminar of the

second type was presented at NBS to personnel of the Nuclear Regulatory

Commission. A similar seminar was given at the Los Alamos National Laboratory

and five seminars were presented with ACS sponsorship at two national meetings

and at three industrial organizations.

Special cooperation has been provided to the Army's Edgewood operations.

A comprehensive survey was made and advice provided on the Army Industrial

Hygiene Agency's contract laboratory program. In addition I have served

throughout this year as an advisory member of the quality assurance task- group

of the Chemical Research, Development, and Engineering Corps.

In special cooperation with EPA, I am an advisory member of a special task

group whose mission is to develop guidelines for admission and coding of data

to STORET Computerized Water Quality Database.

9
NBS Special Publication 260-100, "Handbook for SRM Users/" was published

at the beginning of the year and its initial printing of 5000 copies is about

exhausted. It has been slightly revised and reprinted. This handbook provides

information on the role of SRMs for quality assessment of analytical data and

gives guidance on how to use them effectively to evaluate measurement accuracy.

The systematic measurement of SRMs, along with a laboratory's own control

samples with all results interpreted by means of control charts, is proposed as the most effective way to accomplish this purpose.

The center has organized a quality assurance task group that is developing

selected aspects of its QA program. During the year, the group has developed a document setting forth policy and guidance for laboratory record keeping as well as a form for 'use in defining the work to be done in service analysis or for SRM certification measurements. A document providing guidance for the more uniform statistical treatment of measurement data also has been prepared.

D . Service Analysis

R. W. Burke and M. V. Smith

The performance of service analyses continues to be an important function

of the Center for Analytical Chemistry (CAC) . Within the scope of this

activity, the technical staff gives advice, performs accurate chemical analyses, and provides state-of-the-art calibrations on a wide range of research and

standard materials. This service is available, on request, to NBS staff and to

all Federal, state, and local government groups. It is also available for use by the private sector in those special instances for which CAC possesses a unique measurement capability. Within the latter category, the two most

frequent types of requests are for the verification of spectrophotometric

transmittance SRMs and for the recalibration of SRM gas mixtures.

In the performance of the service analysis function, every member of the

CAC staff is dedicated to providing timely, cost effective, and informative

analyses. The turnaround time for the more straight-forward analyses ranges

typically from several days to about two weeks. All work is performed on a cost reimbursable basis. Within NBS, funds are obligated on an interdivision

work order and designated cost centers are cross-charged. All outside work is

performed on a purchase order.

During the first 11 months of FY86, CAC staff provided analyses or recalibrations for some 110 requests at a cost of $208,020. These requests and

their associated funding were divided among the three categories of customers

as follows: NBS - 25 jobs ($88,730); other government agencies - 21 jobs

($56,050); and private industry - 65 jobs ($63,240).

Historically, other government agencies have spent the most dollars on service analyses. This year, expenditures in this category was markedly lower

than in previous years ($75K decrease from FY85)

This decrease is likely due

to cutbacks resulting from Gramm -Rudman legislation. The number of requests

and level of funding from NBS and private industry were about on a par with

past years.

10
II. Inorganic Analytical Research Division

James R. DeVoe , Chief

Barry I. Diamondstone , Deputy Chief

A. Division Overview

The Inorganic Analytical Research Division conducts research that is

directed toward improving the accuracy of compositional measurements of

inorganic constituents in a variety of materials. This research takes the form

of basic studies on new principles of chemical analysis as well as improvements

to existing methods. In addition, the Division uses accurate methods to

certify Standard Reference Materials, to provide analytical services for other

government agencies, and to provide analytical support for solving problems

related to national needs. The Division is organized into four Groups which

are oriented to specific technical disciplines. The Groups are: Analytical

Mass Spectrometry, Atomic and Molecular Spectrometry, Electroanalytical

Research, and Nuclear Methods.

The implementation of a new data base, containing analytical values

obtained for SRM certification, has resulted in increased attention being paid

to the intercomparison of results among analytical methods. This capability to

rapidly identify discrepancies has led to an increased effort in the Division

to evaluate sources of bias for various analytical procedures. Numerous

activities are in progress that are aimed at producing new and more effective

chemical separations. There are three projects underway that involve the use

of liquid chromatography (LC) , each using a different approach (one involves

the separation of alkali metals from the transition metals using robotics, one uses ion chromatography, and one uses high performance liquid chromatography

(HPLC)). The major thrust of this work has been in the area of atomic spectroscopy since Division analysts are especially sensitive to the need to matrix

match for improving accuracy in this area. However, it is expected that very

high resolution LC will prove to be useful with many of the analytical

techniques. Our fledgling effort in the use of robots has the potential for

significant impact (as indicated in a following report) . We are actively

studying the meaning and use of the so-called expert systems which may be

adapted to optimize chemical separations with respect to the analytical method

as well as to the sample being analyzed. A decision has been made to reemphasize wet chemistry followed by gravimetry and/or spectrophotometry for the high

accuracy measurement of certain macro and minor constituents such as silicon

and phosphorus. In the future, it is possible that improvements to existing

techniques, such as isotope dilution mass spectrometry (IDMS) , can be used for

such purposes, but in the meantime at least one man-year will be devoted to

reestablishing classical techniques.

During the past year, funds have been made available to upgrade and

refurbish a number of laboratories. One existing clean room on the third floor

of the Chemistry building that was more than 15 years old was completely

rebuilt using state-of-the-art clean room facilities. This effectively doubles

the clean room space which has been very much needed. Division personnel,

experienced in clean room design and use, were available to help design the new

facility and to oversee the implementation of the refurbishing process. In

addition, work has begun on the renovation of the radiochemical laboratories in

the Reactor Building. This will allow the rest of the Division staff to

utilize tracer techniques, with their inherent high sensitivity, to investigate

problems such as losses of elemental constituents during chemical dissolution.

11
The Division has been fortunate to have a number of guest workers with us from The Peoples' Republic of China. They have been of inestimable assistance

by helping to certify SRMs while, at the same time, they have had the opportunity to learn some of the new methods that have been developed at NBS . Without

exception, these guest scientists have been eager to learn and have proven to

be very capable.

There have been significant advances in the developmental research area

this past year, and some of these are detailed in the various reports that

follow. Several have not been included but are of equal importance. For

example

Ion chromatographic methods have been developed and applied to the

determination of alkali and alkaline earth metals at trace and ultratrace

levels

The development of a high accuracy analytical procedure for CO2 by isotope

dilution mass spectrometry has progressed well during the last year.

Extensive improvements have been made in the type of standards that are currently available for the calibration of spectrophotometers.

Significant progress has been made in determining the extent to which

resonance ionization mass spectrometry can be used to measure high

isotopic abundance ratios.

The determination of arsenic in human livers by instrumental neutron

activation analysis, the institution of specimen banking for NOAA, and

participation in a number of "round-robin" studies such as the analysis of

selenium and zinc for NIH, as well as the analysis of a variety of steels

for C and S for the International Organization for Standardization (ISO)

have all been part of the research activities carried out in the Division

during the past year.

The concept of Technical Champions, which was initiated last year, has

become a major part of Division efforts in the analysis of SRMs. More than a dozen senior scientists have taken the responsibility of overseeing the

technical aspects of forthcoming SRMs. The ultimate goal of this program is

closer interaction between the members of the Division and the project managers

of the Office of Standard Reference Materials.

Long-range planning is carried out while taking into account two main

considerations which operate under a degree of counterpoise. Projects are planned on the principle that, in the long run, the results of R&D will produce

an improvement in the accuracy of chemical analyses. This means that emphasis

is placed upon techniques such as isotope dilution mass spectrometry that have

the requisite high accuracy. This method and nuclear activation analysis are our most expensive techniques, but the resulting accuracy is worth the investment. If accuracy is taken as the ultimate consideration, then these two

methods should be the mainstays in the certification of Standard Reference

Materials. On the other hand, if fiscal constraints such as the need for the

Office of Standard Reference Materials to reduce the cost of the certification

of SRMs is considered, there is considerable interest in doing R&D on the

accuracy of techniques that are less costly, and as a consequence, are widely

used in industry. Such techniques are the optical, atomic, ion

chromatographic, and electrochemical methods.

12
Taking all of the above considerations into account, our long range plans

are as follows:

1. Perform developmental research in the area of IDMS by trying to automate

various parts of the analysis without sacrificing accuracy, in order to

reduce the cost of this technique. (Examples are the automation of

chemical separations via HPLC, R&D on the ICP-MS, and the purchase of the

new multi -source and detector mass spectrometer)

2. Perform R&D to improve the accuracy of the optical, ion chromatographic,

and electrochemical techniques.

3. Institute greater use of technicians for the certification of SRMs by all

techniques. Since there is always the danger of sacrificing accuracy by

doing this, a much greater emphasis will be placed on quality assurance

coupled with very close supervision by the senior staff.

1 . Analytical Mass Spectrometry Group: Overview

The Analytical Mass Spectrometry Group performs compositional measurements

using the analytical sciences of chemical separation and mass spectrometry.

For many years, the Group has been involved in making isotope ratio measurements with the highest precision and accuracy. These measurements are done

using thermal ionization mass spectrometry on highly purified elemental materials. The separation of elemental species, often from very complex matrices,

with high efficiency and low contamination, is an expertise that is required to

complement the capabilities of thermal ionization mass spectrometry for making

precise and accurate isotopic ratio measurements. The Group has applied these

measurements to the determination of the atomic weights of the elements and

chemical analysis by the technique of isotope dilution. While maintaining the

basic thrust in the traditional areas, the horizons of the Group have broadened

markedly in recent years. New techniques in sample handling and preparation,

separations, and mass spectrometry have been introduced.

Two new commercial mass spectrometers have been acquired by the Group in

the past two years. Last year, an inductively coupled plasma mass spectrometer

(ICP-MS) was installed and made operational. This instrument has been intensively studied this year for its ability to make high- sensitivity isotope

dilution measurements directly from aqueous solutions. Very promising experiments have been completed which compare isotope ratio measurements of this

instrument with thermal ionization. An NRC-NBS postdoctoral associate has

joined the group this year and has begun experiments to interface the ICP-MS to

a liquid chromatograph to do elemental speciation studies.

A second instrument, an automated multi-collector thermal ionization mass spectrometer, has been purchased, and installed this year. The purchase of

this instrument represents a dramatic departure from tradition, since, historically, the Group has operated only NBS-built thermal ionization mass spectrometers. The multi- turret source and automated capabilities promise to increase

sample throughput and the multi-collector can make high-precision measurement

more routine. Further studies are required to demonstrate accuracy.

Progress continues to be made in the resonance ionization mass spectrometry (RIMS) program. The capabilities for osmium and rhenium isotopic

measurement by RIMS have been extended to the sub-nanogram levels. The incorporation of a measurement system based upon signal averaging or pulse counting,

13
using a transient-digitizer, has been evaluated and is now in operation. A

high- resolution laser system has been built and is used with our second RIMS

instrument. This system has recently been used to demonstrate isotopicallyselective resonance ionization; the first isotopic shift measurements have been

made for beryllium. In collaboration with researchers from the Centers for

Radiation Research and Chemical Physics, instrumentation for laser desorption

and ion sputtering studies is being developed and preliminary results have been

obtained.

Research and development work on a microwave digestive system has

continued. By use of probes that measure the pressure and temperature in

closed vessels in a microwave oven, power absorption data can be collected

during acid decomposition of samples. These data have then been used to

generalize the technique for different heating conditions and samples. Through

collaborative research with a number of analytical groups outside NBS , the

usefulness of microwave dissolution has been demonstrated for many types of

samples

The use of robots for the automation of chemical separations is being

investigated. Training a robot to do some of the more routine, yet vital

functions of the Group's chemistry has been and will continue to be challenging.

Since accurate isotope ratio measurements have always been the Group's

strength, we have been very active in this over the past year. Significant

progress has been made on the chemical assay and isotopic analysis of nickel,

such that the redetermination of the atomic weight of nickel should be com- pleted next year. High sensitivity measurements of uranium have continued in

support of a number of programs, including one using the reduction of background for a multi-national experiment involving proton decay. The Group has

also made significant contributions to the certification of various Standard

Reference Materials.

In the future, the general research program of the inorganic mass spectrometry group will be directed toward traditional goals of improving

sensitivity, applicability, precision and accuracy of isotope ratio measurement. The program will encompass state-of-the-art instrumentation (ICP-MS,

RIMS, HPLC) and emerging ideas and concerns in inorganic analysis (automation,

inorganic chromatography, multicomponent analysis). The Group will continue to

develop low blank methods of chemical separation and high sensitivity methods

of ionization to certify elements at ultratrace levels in a variety of important materials (Se, Zn, V in serum; B, S in steel; Os, Re in rocks; U, Th in

water). The Group will become more involved in new areas of isotope metrology,

such as: the use of isotopic tracers in environmental and nutrition studies,

the development of new atomization techniques for laser mass spectrometry, and

the measurement of radioactivity by mass spectrometry. And finally, the Group

will be actively pursuing the introduction of automation in the laboratory,

both in mass spectrometry (evaluation of fully automated mass spectrometers)

and in the chemistry (robotics), which promises to provide increased throughput

and reproducibility for the more routine measurements.

Jack D. Fassett, Group Leader; I. Lynus Barnes, Ellyn S. Beary , William A.

Bowman, III, Karen A. Brletic, Courtney A. Clements, Emile C. Deal, John W.

Gramlich, Scott A. Hotes , Lois B. Jassie, W. Robert Kelly, Howard M. Kingston,

George M. Lambert, John R. Moody, Paul J. Paulsen, Ronald W. Shideler, Heinz

Zeininger, and Richard J. Walker.

14
2 . Atomic and Molecular Spectrometry Group: Overview

The Atomic and Molecular Spectrometry Group investigates fundamental

processes in atomic and molecular spectroscopies to develop new analytical

techniques and to improve existing methodology. Research and development

activities include areas of atomic emission, absorption, and fluorescence

spectroscopy, as well as resonance ionization mass spectroscopy, and the

application of lasers to ionization processes, e.g., laser enhanced ionization

in flames and photoionization processes in mass spectrometry (RIMS) . The

developmental research emphasizes the detection of all random and systematic

errors and applying these resulting methodologies to the certification of

Standard Reference Materials (SRMs)

The testing of SRMs for homogeneity and their subsequent certification

continues to be a major activity of the Group. Over 110 elements were determined in a total of 30 SRMs using all of the established analytical techniques

in the Group. In particular, the determination of 12 elements in Dolomitic

Limestone will result in the renewal of this SRM with low uncertainty limits

for most of the elements determined. The homogeneity assessment and acceptance

testing of the new 1760 series low alloy steel SRMs using spark emission

spectrometry marks the first step in a major effort to replace the depleted

1260 series. We have analyzed a number of materials for other government

agencies. For example, participation in round-robin studies has continued in

support of a National Cancer Institute study of Se and Zn in blood using atomic

absorption spectrometry, and in ISO and ASTM studies of C, S, 0, and H in

steels using inert* gas fusion techniques.

Research in laser enhanced ionization has been continued by one of the

Group members (G.C. Turk) who is on sabbatical at ISPRA working with N.I.

Omenetto. Laser probes in chemical flames, coupled with electrical detection

have been used to study ionization efficiencies and spectroscopic lifetimes.

This new approach allows the comparison of ion depletion rates due to

recombination and fast chemical reaction processes in the flame.

Several group members have collaborated with the mass spectrometry group

on the resonance ionization mass spectrometry (RIMS) project. Very narrow

laser linewidths, combined with an opposed beam geometry resulted in excitation

to the ion with Doppler-free linewidths being produced. Using this instrument,

optical isotope shifts have been measured for a number of the atomic transitions in beryllium.

Research on separation techniques for improving the accuracy and precision

of trace element determinations has continued in three major areas. The first

involves the application of HPLC for the separation of major constituents from

trace elements in complex matrices. The goal is to provide a means for atomic

and molecular instrumental measurement techniques to determine trace elements

without systematic errors due to the presence of the sample matrix elements.

Initial efforts have focussed on the characterization of solvent and apparatus

materials compatibility to minimize sample contamination. The second area is

the use of ion chromatography for the separation of phosphorus from iron and

copper matrices prior to determination by direct current plasma spectrometry.

The quantitative separation of P from solutions of copper benchmark SRMs

eliminated an unresolvable spectral interference from Cu in the DCP emission

spectrum. The third area of research involves the use of HPLC coupled with

AAS . The system developed last year to preconcentrate Cr+6 from aqueous

mixtures of Cr+3 and Cr+6 has been modified to allow the separation and

15
determination of both Cr+3 and Cr+6 in natural waters and sediment leachates.

The group has contributed expertise in software and instrument -computer interfacing design to a project to apply robotics to automated sample preparation

and chemical separation in collaboration with the mass spectrometry group.

Research in calibration statistics has led to a new method for estimating

uncertainties for calibration curves. The specific application is for linear

calibration curves over concentration ranges of several orders of magnitude.

Non- constant variance (heteroscedasticity) is usually exhibited by measurements

over such a wide range, and special techniques must be employed to account for

the changing variance.

Material transport research has continued with the examination of accuracy

in solid sampling of aluminum matrices. Progress in aerosol generation, transport and collection techniques has led to the development of a method for realtime analysis of ambient aerosols. Single element detection has been demonstrated using regenerative blower sampling coupled to atomic absorption

spectroscopy (AAS) . The entire system is portable and will be used to monitor

Fe aerosols in air.

Optical absorbance filters continue to be important SRMs for spectrophotometric measurements in industry, as evidenced by the high demand for these

SRMs. Research in this area has resulted in significant advances in the

characterization of these filters. The precise measurement of substrate,

coating thickness, and transmittance (T) uniformity is now automated and implemented on a routine basis. The calibrated range of transmittance has been

extended from 10-30 %T to 1-50 %T. A new technique for producing solid fluorescence standards has been developed using sintered phosphorus compounds and

powdered Teflon. Twelve sets of these new materials have been delivered to

other laboratories for evaluation.

The Group has determined that wet chemical analysis techniques must be re- instituted and that expertise in this area be maintained to complement instrumental spectrometry. We also expect to use existing instrumental spectrometry

to improve the accuracy of the classical techniques.

The Group has maintained its high level of cooperative research with NBS

and other visiting scientists. R. Paule , National Measurement Laboratory, has

collaborated with F.C. Ruegg on the analysis and graphical presentation of

interlaboratory data from the National Cancer Institute. R. Christensen,

Liquid Chromatography Group, Prof. A. Syty, Indiana University of Pennsylvania,

and T.C. Rains have continued their studies on chromatographic separations

coupled to AAS. R. Christensen has also consulted with R.W. Burke on metal

chelate separations using HPLC . C. Spiegelman, Center for Applied Mathematics,

Prof. R. Carroll, University of North Carolina, Chapel Hill, and R.L. Watters,

Jr. have developed the heteroscedastic calibration method. N. Valette-Silver

University of Maryland, N. Boctor, Carnegie Institute of Washington, and R.L.

Watters, Jr. have applied ICP spectrometry to the study of geothermal fluids

and deposits. M.S. Epstein is working with K. Epler, University of Maryland on coupling ion chromatography to DCP spectrometry as part of Ms. Epler' s doctoral

research with Prof. T. 0' Haver.

In the future, the Group plans to apply some of the emerging laser

techniques to the accurate analysis of SRMs. The Laser Enhanced Ionization

(LEI) technique has matured to the point that specific matrices can be analyzed

for trace elements at sub ng/mL concentrations. As sources of systematic error

16
in new matrices are defined, and the sensitivity and selectivity are improved,

the capability of LEI as an accurate method will be evaluated for a number of

new materials. We expect to develop fluorescence techniques using both laser

and broad-band sources, and the hollow cathode discharge will be investigated

as a source of atomic vapor for spectrometric analysis. Chromatography will

play an increasingly important role both for chemical speciation and for

pretreatment of complex samples to reduce systematic errors in instrumental

spectrometric analysis. Matrix element separation schemes will also be investigated as a means of reducing errors in absorption or emission spectrometry.

Since these schemes often involve the use of a variety of organic and inorganic

solvents, new spectrometric calibration effects with AAS , ICP, DCP, and LEI

will be characterized. We also expect that existing spectrometric techniques

will be used to analyze intermediate fractions of classical separations for

major element determinations. This will eliminate the need for multiple

separations often required to make classical analysis techniques accurate.

Robert L. Watters, Jr., Group Leader; Robert W. Burke, Therese A. Butler, Barry

I. Diamonds tone , Katherine Epler, Michael S. Epstein, Robert C. Gauer, R. Eben

Jenkins, Radu Mavrodineanu, John A. Norris, Theodore C. Rains, Fillmer C.

Ruegg, Theresa A. Rush, Melody V. Smith, John C. Travis, Gregory C. Turk,

Thomas W. Vetter, Jesse Wen, and Laura J. Wood.

3 . Electroanalvtical Research Group: Overview

The Electroanalytical Research Group conducts basic research and utilizes

electrochemical principles to develop new' techniques, to improve existing

techniques, and to apply them to chemical analyses. The techniques in practice

include amperometry, conductimetry , coulometry, ion chromatography, polarography, 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

The Group's interest in accurate measurements in acid rain has continued

along three major lines: a) continued checking of SRM 2694, Simulated Rainwater, for long-term stability, b) studying the effects of radiation sterilization on long-term stability of rainwater standards and groundwater standards,

c) working with ASTM to establish a standard method for the measurement of pH,

anions, cations, conductivity, and acidity in rainwater. SRM 2694 has been

reanalyzed one year after its initial production. Minor changes were noted in

pH and sulfate; a significant change was observed in the nitrate concentration

of Level 1. These changes resulted in a revision to the Certificate of

Analysis. Rechecks of SRM 2694 are planned at six month intervals. It is

hoped that the irradiation study started this year will remedy these

instability problems.

A Research Associateship Project has been established in the

Electroanalytical Research Group in conjunction with the National Committee for

Clinical Laboratory Standards (NCCLS) , and the Council of the National Reference System for the Clinical Laboratory. The purpose of this project is to

develop reference methodology for measuring by direct potentiometry with ion

selective electrodes, the activity of free ionized sodium, potassium, and

calcium in blood. Definitive and reference methods, and certified reference

materials for measurement of each element's total concentration are currently

available. However, the increased use of ion selective electrodes requires

that a reference method be developed to measure each element's activity.

17
Through financial sponsorship by industrial manufacturers of direct potentioraetric analyzers, the NCCLS and the Council have hired a postdoctoral research

associate, Dr. P. Chandrani Gunaratna, to work under the direct supervision of

the senior staff in the Group. Initial efforts have concentrated on developing

the necessary skills and experience in this new endeavor. A new cell design

has been developed, which, along with an ammonium chloride filling solution,

minimizes liquid junction potential biases in a serum matrix. Work is proceeding to use a sodium amalgam cell to improve the accuracy of the determination

of the activity of sodium ion.

Research is continuing on the development of aqueous electrolytic

standards. A Jones Bridge has been acquired and has been recalibrated by the

Electricity Division at NBS . Other instrumentation necessary for the

measurement of conductance has been improved and tested. The oil bath used for

temperature control has been improved, with temperature stability to 0.001 °C

at 25 °C. A new cell that will give an absolute measure of cell constant, has

been designed and fabricated. Preliminary testing shows that this novel

approach using a cell with variable, but accurately known cell length is

feasible and theoretically accurate. Modifications to the cell are being made.

Collaborations with Professor Robert L. Kay at Carnegie-Mellon and with Anna

Tomek at the Office of Measures in Hungary have been established.

Research in electrolyte theory has been initiated, and consultations with

noted experts (Harold Friedman, Walter Hamer, Vincent Bower, Robert Kay, and

Arthur Covington) in the field have been held in an endeavor to improve the

state of pH measurements and standards, which will ultimately lead to a single,

unified pH scale. Dr. Rabindra Roy from Drury College, Springfield, Missouri

has joined the Electroanalytical Research Group on an IPA assignment for the summer. His research project has been to develop, by using the Harned cell, an accurate data base which is necessary for the development of high ionic

strength pH buffer standards that have applications in oceanography and

clinical chemistry.

Research in voltammetry is progressing well: a new microprocessorcontrolled vo Itammeter has been acquired which will permit determinations with

lower detection limits and includes capabilities in ASV, cyclic, and differential pulse polarography . A project done in collaboration with the mass spectrometry group has resulted in the development of improved dissolution

procedures incorporating microwave digestion. This required the development of

voltammetric techniques to detect traces of undigested organics. Applications

include bovine liver and monel. The use of indium as an internal standard in

anodic stripping voltammetry has been developed and applied as a means of

improving its accuracy and precision. The vibrating wire electrode has been

used as a detector in the ion chromatographic determination of iodide with a ten- fold enhancement in sensitivity over the static electrode. Additional

research is needed to fully develop the procedure.

Methods have been developed for the ion chromatographic determination of

sodium, potassium, ammonium, calcium, and magnesium. Anion determinations have

been improved with the implementation of a new micromembrane suppressor system;

a similar system has been installed for the cations. Using concentrator

columns, determinations of calcium at the parts per trillion level have been

made. Attempts to use ion chromatography for the determination of fluoride in

botanicals at natural levels proved impractical due to interferences. Instead,

a method was developed using ion-selective electrodes after high-pressure

oxygen bomb combustion. This method was used to determine the concentration of

18
fluoride as a function of particle size in timothy grass, a candidate SRM. A

joint research project with the Atomic and Molecular Spectroscopy Group, aided

by a graduate student from the University of Maryland, which couples ion chromatography to direct current plasma spectrometry has been initiated. Separations of several metals have been achieved, and a procedure for eliminating the

copper interference from phosphorous has been developed. Research is beginning

on the implementation of replacement chromatography followed by atomic

spectrometry.

As always, SRM certification and other service analyses have been an important part of the Electroanalytical Research Group's activities. Sulfur in

various oils and fuels has been determined by ion chromatography. Combustion

gases have been analyzed for chloride, bromide, and cyanide. The trace ionic

impurities on filters have been measured. Potassium tetroxalate has been

recertified as a pH buffer standard. Monel has been analyzed for lead and

copper. Potassium dichromate and calcium carbonate have been assayed by

controlled-current coulometry. A joint project with the Electrodeposition

Group of the Metallurgy Division involving plating characteristics of various

materials has continued for a second year.

The Electroanalytical Research Group continues to expand its resources and

scope of research through active use of the guest worker program, and industrial, international, and academic collaborations. This year the group is

composed of four research chemists, a guest worker from the People's Republic

of China, two summer students, a research associate, and two visiting professors. The group maintains its involvement with ASTM and NCCLS through participation in meetings and task groups, and has been active in Task Group IV

(Monitoring) of the National Acid Precipitation Assessment Program. Research

in pH will continue as a long-term commitment to provide reliable and thermodynamically significant measurements and standards. The development of a series of matrix- specific pH standards is a high priority. Investigations in

aqueous conductance will continue; advancements in ion chromatography will be

explored. Flow- inj ection analysis with electrochemical detection will be

implemented for determinations of trace metals in complex matrices. Voltammetry will be used extensively as a valuable analytical research technique

within the group. Speciation of metals by valence and by complexation will be

a dominant research direction.

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

Melissa Knoerdel, Lisa A. Holland, Han Kai, P. Chandrani Gunaratna, Rabindra

Roy, and Clarence H. Breedlove.

4 . Nuclear Methods Group: Overview

The development and application of nuclear analytical techniques for

greater accuracy, higher sensitivity, and better selectivity are the goals of

the Nuclear Methods Group. A high level of competence has been developed in

reactor-based activation analysis, which includes instrumental and radiochemical neutron activation analysis (INAA and RNAA) . In addition, the Group

has a unique capability in neutron beam analysis, using both prompt gamma

activation analysis (PGAA) and neutron depth profiling (NDP) . The NDP technique utilizes prompt charged particle emission to determine elemental distributions within the first few micrometers of a surface while the PGAA technique

utilizes prompt gamma-ray emission to measure the total amount of an element in

a sample regardless of its distribution. These techniques provide an arsenal

19
of cools to address a wide variety of analytical problems in science and

technology

The activities of the past year have been highlighted by our involvement

in the 7th International Conference on Modern Trends in Activation Analysis, by

new measurements carried out at other research facilities, and by a major

renovation of laboratory space in the Reactor Building. The MTAA-7 meeting,

which was held in Copenhagen in June, commemorated the fiftieth anniversary of

the discovery of activation analysis by Hevesy and Levi. NBS scientists were authors of ten of the papers presented at this conference. The opportunity was also provided for visits to the laboratories of’ several of our European

colleagues

In addition to our on-going use of the nearby reactors at the University

of Maryland and the University of Virginia, primarily for fast and epithermal

neutron activation analysis, Group members carried out measurements using the

facilities at the new cold neutron source at Julich and the intense guided

thermal neutron beam at Grenoble. The Julich work, which was reported at the

MTAA-7, provided the first demonstration of the use of a cold neutron beam for

prompt gamma activation analysis. At the ILL Grenoble reactor, which currently

has the world's most intense thermal neutron beam, the neutron depth profiling

facility was used to demonstrate the profiling of oxygen with the 17 0(n,a) 14, C

reaction. This work has since been repeated on the NBS facility, but to be

practical, the actual implementation of NDP for oxygen must await the very

intense beams of the proposed NBS Cold Neutron Facility.

The Group's contribution to the certification of Standard Reference

Materials is illustrated by the multielement measurements done on the following

SRMs : Fly Ash, Flint Clay, Plastic Clay, Dolomitic Limestone, Rice Flour, and

Wheat Flour. At major levels, the determination of silicon by fast neutron

activation analysis has been demonstrated. Preliminary measurements of trace

levels of lithium and boron in biological materials will be published using a thermal neutron irradiation followed by a helium gas mass spectrometric

determination for quantification.

Research into biomedical problems has again been strong this year centered

around the activities of the joint NBS/NOAA/EPA Environmental Specimen Bank. A

new stable isotope technique for the measurement of total blood volume in

humans has been reported based on the NAA determination of the Cr-51/Fe-59

ratio in samples spiked with Cr-50. The characterization of biological

macromolecules by a combination of gel electrophoresis and neutron activation

analysis is under development. A special large volume irradiation facility has

been constructed for this purpose. A systematic effort has begun to make

accurate and efficient measurement of trace elements in human serum, focused

initially on zinc and selenium. The crucial step of valid sampling of

biological materials was reviewed in a special issue of the Bureau's Journal of

Research (1)

The strong interaction with industrial scientists using neutron depth

profiling, prompt gamma activation analysis, and neutron activation analysis is

continuing with a growing number of guest workers, research associates, and

joint publications. The long-term NDP study of the mobility of helium in

nickel has been completed. The measurement of distributions of lithium and

boron in metals, glasses, and polymers continues to produce important results.

20
The joint NBS/FDA/USDA study of trace elements in human diet, sponsored by

the International Atomic Energy Agency, has completed its second year. A total

of 30 biologically important minor and trace elements have been measured on the

total diet material, USDIET-I. A second composite diet material is being

prepared for study and will be considered for use as an NBS Reference Material.

During the coming year, the Group will continue to improve the accuracy

and sensitivity of those nuclear methods that are applied to elemental

measurement. This will address the problems of sample preparation,

irradiation, and counting, with the goal of reducing and quantifying the

various sources of systematic error in analysis by nuclear methods. In

particular, the application of NAA, both instrumental and radiochemical, to the

analysis of important trace elements in biological samples will be pursued. In

the area of materials analysis, the improvement of both the beam techniques,

NDP and PGAA, and traditional NAA will extend our capabilities in sensitivity,

and the number of elements that can be profiled or measured. As always, one of

the major products of all of our efforts is the increased capability to carry

out certification measurements on Standard Reference Materials.

Ronald F. Fleming, Group Leader; Thelma A. Allen, M. James Blackman, Donald A.

Becker, B. Stephen Carpenter, Kevin D. Diamant, R. Gregory Downing, Kathleen A.

Fitzpatrick, Robert R. Greenberg, G. Venkatesh Iyengar, John K. Langland,

Richard M. Lindstrom, George J. Lutz, John T. Maki, Bruce R. Norman, Susan F. Stone, Mano P.M. Tillerkeratne , and Rolf L. Zeisler.

(1) Journal of Research of the National Bureau of Standards 91, No. 2, March

1986 Special Issue: Biomedical Sampling.

21
B. Selected Technical Reports

(Inorganic Analytical Research Division)

1 . Installation of an Automatic. Multi-Collector Mass Spectrometer

I.L. Barnes and J.W. Gramlich

An automatic thermal ionization mass spectrometer has been received,

installed and initial analyses have been completed. The instrument has provision for loading of up to 13 samples at one time with full computer controlled

operation possible. The most important feature, however, is that the instrument is equipped with 7 deep Faraday cup collectors, 6 of which are externally

adjustable. This permits simultaneous collection of up to 7 mass beams. This

collection scheme is made possible by the unique ion optical design of the

instrument which takes advantage of the fact that greatly increased dispersion

is obtained when ions enter the magnetic at an angle other than normal to the

field. By use of this design, the instrument with a nominal radius of 23 cm has the equivalent dispersion of a 46 cm radius magnet. Additional optical

magnification at the collector gives this instrument dispersion equal to that

of a mass spectrometer with a 64 cm radius, sufficient to permit deep Faraday

cup collectors that can be adjusted to cover the mass range from 2 to 240.

Installation and acceptance testing was completed in early July and while

there has been insufficient time to complete extensive tests of all the

capabilities of the instrument, some excellent data has been obtained.

Isotopic analyses of about 40 samples of neodymium have been completed with

very good results. For example, external (run to run) precision of a set of 13

samples of the commonly used "La Jolla" neodymium standard was 9 ppm and equal

or .better precision was obtained on other materials. During these analyses it was determined that all 7 neodymium isotopes (which cover the mass range 142-

150) could be collected simultaneously. A very important test was made during

these analyses to determine that all 7 collectors were collecting ions with

equal efficiency and that amplifier drift was sufficiently small during the

course of the analyses that the results were unaffected. This was done by

collecting several specific ion beams in a particular set of cups and then

shifting these same beams to a different set of cups. Within a few (1 to 4)

ppm, no differences could be detected in the ratios measured or in the

uncertainties

In addition, a new determination of the atomic weight of strontium has

been completed. The 6 synthetic mixes of the separated isotopes of °°Sr and

®^Sr that were used in the original determination of this atomic weight (1)

were each remeasured 6 or 7 times. These analyses were interspersed with the

analyses of 19 samples of SRM 987, Strontium Carbonate. While the statistical

analysis of the final data has not yet been completed, preliminary results

indicate that the atomic weight of strontium is 87.6167518 ± 0.0000735. This

result is within the uncertainty of the previously determined value but the

uncertainty is reduced by a factor of 2. A paper describing this work is in

preparation. Perhaps the most important thing determined during the course of

this work, is that in the original work the final total uncertainty was about

equally divided between the chemical preparation and the mass spectrometric

measurement of the ratios while, in the new determination, the final

uncertainty is essentially all due to the chemistry. This means that in future

work the ultimate precision obtained may be limited by our ability to prepare

samples

22
The early work with this instrument has indicated that, to take advantage

of the much increased precision, new filament preparation, loading, and drying

procedures will have to be developed for each element and work has started on these procedures. We plan early development work on procedures for nickel to

use the instrument for measurements of the atomic weight of this element.

2 . The Determination of Lead Isotope Ratios in Some Ancient Objects

I.L. Barnes, E. Joel (Smithsonian Institution), and R.H. Brill (Corning

Museum of Glass)

The measurement of the isotopic ratios of lead in ores and slags from

sites known to have been in use in ancient times and in ancient objects can often be used to determine or confirm the provenance of these objects. Since

three of the four lead isotopes ( 20 6 Pb, 2 0 7 Pb, and 20 8 Pb) are the stable end

product of the radioactive decay of uranium and thorium, the isotopic ratios of

each lead deposit depends on the relative amount of each of these elements

present and the length of time of the formation of the lead before separation

and deposition of the lead. In theory, each lead deposit has a unique isotopic

signature which can be matched with that in the objects of interest.

In the past year, the long term cooperative project with NBS , the

Smithsonian Institution and the Corning Museum of Glass has continued with high

precision isotopic analyses of lead from a number of objects and ores. One of

the projects involved the analyses of a number of objects taken at a site under

excavation in San Salvador known as the "Long Bay Site" . There is much current

speculation that this is the site of the first landfall made by Columbus on the

discovery voyage. European made objects such as coins, pieces of metal (that

may have been a shoe buckle) and a number of glass beads of a type commonly

used as trading gifts have been recovered from this site. Lead isotope

analyses as well as other examination are all consistent with a Spanish origin

or source for these samples at about the time of the Columbus voyage

Lead isotope analyses have been completed on essentially all of the

Chinese bronzes from the Sachler Collection to be housed in the new Smithsonian

Museum now under construction. Since few samples of ores from sites in China

known to have been used in ancient times are available at this time, we have

not yet been able to identify possible sources of raw materials for these

objects though we believe this is possible in the future. The data have

however been of great use in refining the lists of stylistic attributes used to

identify objects from particular periods.

We have also obtained samples from recently rediscovered sites of ancient

mining activity in central Turkey. These lead samples are of particular interest since they contain rather high concentrations of silver, gold, and in a few

cases, cobalt. Cobalt is known to have been used in early times as a colorant

but sources of cobalt in the middle east are quite rare. It is also hoped that

information will be obtained of possible sources for the many objects made and

traded in ancient Persia.

23
3 . Ultratrace Elemental and Isotopic Analysis of Os and Re Using RIMS and

Thermal Vaporization

R.J. Walker and J.D. Fassett

The capability of precisely measuring the isotopic compositions of

sub-nanogram quantities of Re and Os in geologic materials is of great

potential value to geochemists examining the chemical evolution of the earth

and solar system. The Re -Os isotopic system is based on the radioactive decay

of 187 Re to 1 8 7 0s with a half life of 4.35xl010 yr. Since the geochemical

behavior of Os is unique, the Re-Os isotopic system can provide complementary

information to other isotopic systems (Sm/Nd, Rb/Sr, U/Pb) which are now used

to study the chemical evolution of the earth's mantle and crust. Both Re and

Os generally occur in sub-ppb concentrations in geologic materials and, thus,

a technique is required that is capable of routinely measuring sub-nanogram

quantities of both elements.

Resonance ionization mass spectrometry (RIMS) is a technique that combines

the ability of laser radiation to selectively and efficiently photoionized gas

phase atomic species with the mass resolution capabilities of mass spectrometry. A number of other mass spectrometric techniques have been and

are being investigated to make isotopic Os measurements. To date, however, the

physical and chemical properties of Os have combined to forestall the routine

application of these other techniques to sensitive and accurate Os isotopic

measurement

We have developed HIMS procedures for the sensitive measurement of Os and

Re isotopic ratios. Efficient thermal atomization and resonance ionization has

necessitated the development of specialized sample loading techniques. The Re

and Os are preferentially adsorbed onto resin beads, which separates them from

other elements that may remain after chemical processing. These resin beads

are carefully placed on microfilaments with graphite and collodion, which

facilitates the chemical reduction of these elements in the mass spectrometer. The resin bead loading produces a virtual point source of atomization

from the hottest part of the filament. The microfilament is pulse-heated,

which maximizes sample utilization: the duty cycles of atomization and

ionization are matched and the required high temperature for atomization is

easily maintained.

Three types of measurements have been conducted in order to define the

precision, accuracy, and sensitivity of the RIMS measurement system for Re and

Os: 1) measurement of isotopic compositions of microgram quantities of spikes

and standards, and mixtures of both, 2) measurement of loading blanks, and 3)

measurement of sub-nanogram quantities of standards. The measurement of

microgram quantities of mixed isotopic solutions indicate precisions and

accuracies of 1% can be achieved for both elements. Loading blanks have been

examined for a number of different filament substrate materials. These loading

blanks are determined by the direct loading of isotopic spikes onto filaments

in the same manner of samples (500 and 50 pg of 185 Re and I90 Os, respectively). The blanks ranged from 2 ng to 3 pg for Re and 260 pg to 3 pg for Os.

The reproducibility of the system for the determination of sub-nanogram

quantities was assessed by multiple runs with 900 pg quantities of Os standard

loaded on the filament. The 192 0s/19 °0s ratio was measured with 1.3% relative

standard deviation; the 187 0s/186 0s ratio was measured with a 3.2% relative

standard deviation. The precision of measurements was counting statistics

limited.

24
The making of real measurements at the highest sensitivity forces the

solution of many problems that are not evident in the analysis of larger

amounts of material. Here we have used RIMS to correct for the non- selective

ionization of a hydrocarbon background. This correction reduces the effective

sensitivity of the instrument, because the ultimate limitation will be the

signal- to -background ratio. A second problem was observed due to the accidental overlap of photoionization wavelengths of Os and Ta filament substrate.

This overlap resulted in a scatter background for Os from 181 Ta. Clearly in

the development of RIMS schemes, sensitivity is only one consideration.

Selectivity must be evaluated relative not only to obvious isobaric overlaps,

but also to ionization of species that can degrade the overall measurement

process. Chemical separation procedures for Os and Re from rocks is presently

being developed and initial analyses being made.

4 . Quantification of Pulsed Ion Currents Produced in Resonance Ionization

Mass Spectrometry (RIMS’)

J.D. Fassett, R.J. Walker, J.C. Travis, and F.C. Ruegg

The use of pulsed lasers as ion sources in inorganic mass spectrometry

creates a new challenge for precise and accurate isotope ratio measurements.

Although pulsed laser ionization processes can be orders of magnitude more

sensitive than traditional, continuous ionization techniques such as thermal

ionization or electron bombardment ionization, the problem of quantitation of

pulsed ion signals has not been adequately addressed. Furthermore, the

measurement of ion currents over relatively large dynamic ranges (> 1:106

) is a non- trivial problem in pulsed ionization. Laser ionization can result in the

formation of ion packets as large as 10 5 ions/pulse/mass that are accelerated

and focussed to the 'detector with time spreads as small as 10 ns. Issues of

detector response linearity between and among differing species at widely

different intensities must be faced in order to demonstrate quantitative

isotope ratio measurement.

In last year's annual report we described the development of a measurement

system based on time array detection using a transient digitizer. Here, we report on the evaluation of this system. We have evaluated the linearity of

the response of the electron-multiplier-based ion detector and developed procedures for large dynamic range ratio measurement. Data have been collected

which demonstrate quantitative ratio measurements in pulse counting/pulse

counting mode, pulse counting/analog mode, and analog/analog mode of operation.

The laser-generated ion signal is detected using a 17-stage electron

multiplier whose output is preamplified and directed into the transient

digitizer. A non- symmetric pulse with a half-height width of 2 /is is output by

the preamplifier. The transient digitizer is set up to sample 2048 channels,

20 ns per channel, and is triggered by a photodiode detector of the laser

ionization pulse.

Several routines were developed for processing of data acquired by the

transient digitizer in real time, so that no ionization data is sacrificed.

The most general routine signal averages the digitized waveforms acquired by

the transient digitizer. In addition to the signal averaging that is done, a pulse-counting routine has been incorporated into the general signal processing

program which is used for low level signals. At high signal levels this

routine is not useful for quantitation but can be used to verify that there

have been no pulses that have exceeded the 8 -bit dynamic range of the

25
digitizer. After the signal -averaged data has been acquired and processed,

five pieces of information are extracted, displayed, and transferred to the

isotope ratio program: 1) total number of waveforms acquired; 2) position of

peak; 3) baseline; 4) baseline corrected signal; and, 5) number of pulses

detected.

The isotope ratio program controls the laser wavelength, magnetic field of

the mass spectrometer, and data acquisition and processing. The program is a variant of the standard ratio program used in high precision thermal ionization

where a single channel detector is available and alternating measurements are made on two isotopes. The key change that was made to accommodate RIMS is the

determination of baseline on mass for each isotope, but off the resonance

wavelength. Thus, the signal quantified is the elementally selective

ionization caused by the laser.

The measurement of Os and Re using this system has been described in

another highlight of this report. Those measurements were made at one gain

setting of the electron multiplier and both intensity- averaged and pulsecounted ratio measurements were demonstrated. Procedures have also been

developed for large ratio measurements which combine pulse -counted and

intensity- averaged signals at different gain settings of the electron multiplier. These procedures were tested by measuring natural 18

Os/1 9Os which has

a ratio of 4x10“ 4 and an isotopic standard of 129 1/127 1 which had a ratio of

10“ 6

.

The predominant uncertainties in ratio measurement will differ according

to the signal quantification scheme: for large signals, the linearity of the

transient digitizer and reproducibility of the mass spectrometry is limiting;

for small signals, pulse counting statistics predominate; and, when the two

schemes are combined, gain calibration of the multiplier is significant.

Nonetheless, our RIMS measurement system has proven to be quantitative over a large dynamic range of measurement.

5 . Detection of Uranium from Cosmos -1402 in the Stratosphere by Thermal

Ionization Mass Spectrometry

W.R. Kelly, J.D. Fassett, R. Leifer (DoE) , and Z.R. Juzdan (DoE)

Cosmos -1402, a Soviet radar reconnaissance satellite powered by a nuclear

reactor containing about 50 kg 23

U, was launched into an earth orbit of 240-

270 km on August 30, 1982. A malfunction on December 28, 1982 prevented the

reactor from being boosted into a burial orbit and on February 7, 1983 it

reentered the earth's atmosphere over the South Atlantic Ocean. In an effort

to determine the fate of the reactor, the 235u^238u ratio of the aerosol in the

stratosphere has been measured by mass spectrometry. This U isotopic ratio is a particularly sensitive tracer for the kind of event because the natural ratio

is small and constant, 0,0072, whereas that of the fuel for a reactor of this

type is about 10.

Since balloon launches and sampling were restricted to the northern

hemisphere, it was necessary to wait until stratospheric circulation transported the reactor aerosol into the northern hemisphere and to lower altitude

before sampling. Based on 1983 meteorological observations, it was estimated

that the best time for sampling would be late winter of 1983. One balloon was launched on February 28 and another on March 13, 1983, providing samples

between 27 and 39 km (see Table 1). A flight 16 days before the reentry of

26
Cosmos -1402 provided an important background sample which permitted measurement

of the concentration of U nuclides in the stratospheric aerosol prior to the

burn-up of Cosmos-1402. Aerosol samples were collected on IPC-1478 cellulose

filter paper in samplers designed and used in the Department of Energy's (DOE)

project ASHCAN. Portions ("10 g) of filters were spiked with 233 U, wet ashed,

chemically purified by anion exchange, and the U isotopic ratios measured by

thermal ionization mass spectrometry using pulse counting detection. Chemical

yields were determined for all samples and the appropriate blank corrections

were applied to both the concentration and composition data.

Table 1. Filter Samples Collected in the Study of Cosmos -1402

Filter Altitude Volume of Air

No. Sample Date (km) Sampled (m3

) Comments

1,2 Blank for 6

3 Blank for 7,8

4 Blank for 5 5 1/23/83 38.6 40.5 Background

6 2/28/84 36.0 92.4 Post -Cosmos - 1402

7 3/13/84 26.6 60.5 Post -Cosmos - 1402

8 3/13/84 31.9 17.9 Post -Cosmos - 1402

Table 2 gives the concentration and composition data. The blank filters

show a small enrichment of 23

U compared to natural U This was also observed

in a previous study, but the exact reason for this is unknown. The filter

material used in this study was about an order of magnitude more homogeneous in

U concentration than that used previously, which permits smaller perturbations

in U isotopic composition to be detected. Of the three post Cosmos-1402

samples, only filter 6 shows a measured isotopic enrichment above the mean of

the blank filters. Although filters 7 and 8 do not show evidence of enrichments above the blank levels, the following model allows the decoupling of the

large amounts of natural U that were collected at the lower altitudes and the

determination of the enriched U from the reactor component.

The following mass balance relation can be written for each filter:

( 235 U) b + ( 235 U) r + ( 235 U) a

( 23 5u/2 3 8 u)m _ (1)

( 23 8 U) b + ( 2 3 8 u) r + ( 23 8 U) a

27
Table 2. Uranium Isotope Composition of Filter Samples

Filter

Weight

Atoms 23U

per g

2 3 4 u

23 5u

Atom % (12s)*

23 6y 2 3 8y

No . # (g)

H O o

r

-

V-/ /"-N O

1 .e- (10” 3

) (10” 4

)

Natural Uranium

55 720 0 99.28

Cosmos -1402 Reactor

10000 90000 5000 8.5

KD 4.2430 47 .1±0.7 85120 845110 316 99.15010.0010

2(2) 4.3307 48 .510.8 106129 832118 516 99.16010.0018

3(1) 6.1505 43.110.4 79111 832128 214 99.18010.0028

4(1) 8.1178 46.812.0 80131 83415 013 99.16010.0005

Pre Cosmos- 1402 Stratospheric Aerosol

5(9) 37.1756 60.711.4 9413 81512 813 99.17010.0002

Post Cosmos -1402 Stratospheric Aerosol

6(11) 44.5520 76.811.6 9616 94214 1911 99.03010.0004

7(2) 3.4602 211.012.0 6914 80017 215 99.19210.0007

8(2) 5.4806 113.012.0 101110 82716 1113 99.16010.0006

*The total uncertainty includes components from ion counting, blank, and

chemical yield.

#Number in parenthesis represents number of determinations. When the number is

greater than 2, the atom % and 2 3 8 U concentration are the weighted mean and

standard deviation. 42% of filter 5 was analyzed. 34% of filter 6 was analyzed

$Assumed to be similar to NBS/SRM U-900.

where m, b, r, and a stand for measured, blank, reactor, and air respectively.

Since we have a good estimate of the 23 5 U and 2 3 8 U concentrations in the blank

filter, we can calculate the concentrations of these isotopes in the natural

background aerosol and the reactor derived aerosol. We have assumed the

( 2 3

U/2 3U) r ratio to be 10.6; however, this assumption is not critical for the

calculation of the ( 235 U) r concentration. A ratio as low as 0.1 would not

change the calculated concentrations. By assuming that background filter 5 is a two component mixture of filter blank and ambient aerosol, we calculate the

( 235 U/238 U) a ratio to be 0.0075510.00052 (2s) which is indistinguishable from

28
the natural U ratio of 0.0072 and indicates that the stratospheric aerosol had

a natural 235 U/238 U ratio. This latter value was used for the air component in

equation (1) for filters 6, 7, and 8.

The average mass of Cosmos-1402 23 5 U per gram of filter 6 is 1.2±0.2xl09 atoms or a total amount for the filter of 68 pg

23 5 U. This corresponds to an excess in 235 U of 36±9% relative to natural U. The maximum observed 235 U

enrichment for Cosmos -1402 was significantly less than that observed for

Cosmos -954. This is ascribed to the higher altitude of injection and later

sampling time which caused a greater dispersion of the material. Assuming that

the ablation aerosol is distributed uniformly around the earth above 26.6 km, we calculate the total mass of 23 5 U injected into the stratosphere to be 30±8

kg. This value is close to the reported reactor mass of 50 kg 2 3 5 U and

suggests that all excess 23 5 U in the upper atmosphere could have come from this one reactor.

6 . Progress in the Development of Microwave -Coupled Acid Dissolution

Procedures

H.M. Kingston and L.B. Jassie (CEM Corporation)

The method of microwave -coupled acid dissolution of samples has gained

enthusiastic support from industry and researchers alike and their desire for

more fundamental data to aid their understanding of the parameters governing

the process has continued. Over 250 industries, universities, research

laboratories or other government laboratories have contacted the NBS for

information and guidance in microwave dissolution technology.

One of our contributions to help meet this research and information need

is the publication of our studies to date on closed vessel microwave digestion.

This report will be published in October as a paper in Analytical Chemistry.

This paper describes methods of predicting the final temperature and time to

temperature at any power setting for single component acid systems. It also

gives examples of reaction control methods and examples of digestion procedures

for some of the most popular biological and botanical Standard Reference

Materials

During this past year, we have cooperated with several other federal

laboratories in the application of the microwave technique to problems con- fronting these organizations. I.E. DuPont Savannah River Laboratory requested

our help in developing a digestion procedure for five materials which simulate

the nuclear waste tank contents and their mixed process materials during the

making of nuclear waste glass. A timely sample digestion procedure which can

be performed remotely is very important in their quality control efforts. We

were successful in developing a single procedure that digested all five

materials. The first step relies on a 10-12 minute microwave digestion with

hydrofluoric and nitric acids under 5 atm of pressure and exceeding 170 °C. As

part of this program, a fiber optic temperature measurement system was evaluated for monitoring temperature in microwave fields and found to possess many

advantages over previous temperature measuring devices. A paper will be

forthcoming on this procedure.

The analysis of biologically active inorganic elements is of importance in

diverse studies of medicine, nutrition, and agriculture. Currently, we are concluding studies with the Department of Agriculture and have proved that

biological fluids and tissues containing Se can be digested in closed vessels

29
in the microwave without losses of this volatile element. Losses in the sa'mple

preparation step are one of the most frequent causes for erroneous Se concen- trations reported in biological materials. The studies include endogenously

Labeled Se-75 and Se-82 that were monitored using gamma-ray spectroscopy and

GC/MS respectively. A paper will be forthcoming on this procedure.

We are organizing the first symposium on microwave sample preparation

which will be held at the Eastern Analytical Symposium in October 1986. This

symposium will act as a focus for fundamental methods in all the major sample

types currently prepared by microwave dissolution: biological; environmental;

geological; and selected industrial samples.

Further efforts to define’ parameters are progressing and include studies

of new acids and new materials. Specific anomalies between accepted theory and

measured phenomenon are being studied to understand the fundamental relationships of materials and the absorbed energy which produce these effects.

7 . Inductively Coupled Plasma Mass Spectrometric Analysis of Major and Trace

Elements in SRMs Using Isotope Dilution

P.J. Paulsen and E.S. Beary

The ICP-MS now has detection limits as low as 0.2 ppb for water samples

using a one minute data collection period covering a mass range from m/z 2 to

250 (an all element survey). Analysis of SRMs with the ICP-MS is done using

isotope dilution analysis since it is an inherently accurate technique. A

major advantage is the ability to make precise isotope ratio measurements even under conditions where the absolute signal level is unstable. Over forty

elements can be analyzed by isotope dilution using the ICP-MS.

Major Elements in SRMs

The ICP-MS has a higher sample throughput rate when compared to other mass spectrometric methods used for isotope dilution. However, to take advantage of

its speed, comparable time savings must be made in the chemical processing

steps of an isotope dilution analysis. Analysis of major elements by ICP-MS -ID can provide faster chemistry since it doesn't need the chemical preconcentration or separation steps required by other MS-ID methods. Better precision and

accuracy are expected for major elements than for trace elements and this is

the critical factor for ICP-MS-ID.

An ICP-MS-ID analysis of six copper concentrate samples was compared to an independent thermal MS -ID analysis of the same material. A sample by sample

comparison between the two MS techniques showed an average difference of 0.33%.

Most of this difference can be attributed to changes in the ICP-MS "mass bias"

correction factor which showed a ±0.24% rsd during the data collection period.

Pb in reference fuel by ICP-MS-ID found 768±8 ppm (la) as compared to a value of 767.3±1.5 ppm (la) measured by thermal MS -ID. Again it was found that

variation in the "mass bias" correction factor could explain the scatter in the

results. Possible sources of variation in the "mass bias" correction are under

investigation.

30
Trace Elements in SRMs

Analysis of a Ni-Cu alloy, SRM C1248, illustrates the capabilities of ICPMS-ID for trace element measurements near detection limits. Tin and lead

determinations were required when co-operating laboratories reported divergent

results, over a factor of ten for Sn, at low ppm levels. Preliminary tests on

the sample indicated that it could be measured without preconcentration or separation chemistry. One gram samples were spiked with 117 Sn and 206 Pb,

dissolved and equilibrated, then diluted to 100 mL with 1% HNO 3

. The ICP-MS

"sampling cone" quickly clogged up with this "1% solids" solution. A dilution

of 1 g/L was required before the ICP-MS interfacing "sampling cone" could

operate properly. Tin with a ppm concentration in the original sample, was therefore at a ppb in the solution being introduced into the ICP. In the

parlance of "ICP-MS" vocabulary, this would normally be referred to as a ppb of

tin. This distinction between concentrations in the original sample and the

"concentration" introduced into the ICP because of instrumental constraints is

not often made in promotional information and literature.

Our analysis found 1.09±0.15 Vg/g (2 a) of tin and 3.84±0.16 ng/g (2a) of

lead in C1248. Dilution of 1 gto 1 L resulted in a signal to noise ratio for

tin that is as low as is practical for certification of an SRM. Analysis of

lower concentrations would require preconcentration techniques and would result

in both better precision of analysis and lower detection limits.

8 . Improved Laboratory Facilities for Trace Element Determination

J.R. Moody

Since 1971, a Class 100 or better clean laboratory has been an essential

part of the mass spectrometry group's trace metal analysis methodolo gy • The

laboratory, built in 1971, was the first attempt at clean room design by NBS

staff and some shortcomings were evident after a few years of use. All

subsequent versions of this laboratory have incorporated various upgrades which

either eliminated or greatly diminished the unwanted effects.

In recent years, the effects of corrosion and poor ventilation had

rendered the original (1971) clean lab almost unusable for trace metal analysis

even though the particle counts were still acceptable. At the same time,

Division 553 was finding that the use of a clean bench for certain of their

micro-analytical analyses was less than satisfactory. Eventually a decision

was made to dismantle the old clean lab and build a new facility for both

groups

This facility was finished in early March 1986 and after acceptance tests

and adjustments is now considered to be fully operational. The present design

is somewhat different from earlier designs, in that no interlock, corridor, or change room exists between the hallway of the building and the clean laboratory. This compromise allowed the incorporation of 25% more usable laboratory

space in the same room, an important consideration when a shared facility is

being designed.

The portion of the laboratory used by Division 553 is walled off by

plexiglass partitions to form a completely independent pressurized facility.

Neither laboratory's functions can have an adverse effect upon the other. The

design goal was to meet a Class 10 standard under all conditions of usage

(e.g., with a door open). The recently completed performance tests indicated

31
chat all clean bench locations and each of the 3 laminar flow fume hoods met a Class 1 or 2 standard. This result is largely attributable to higher quality

HEPA air filters and a higher percentage of recirculated air.

The other noteworthy feature incorporated into the laboratory is a PVC and

fiberglass fume hood imported from England for use as an acid bath-clean up

station. For the first time, the group now has a facility for acid washing

where there is no chance of metal contamination, and, equally important, there

is minimal risk to the laboratory because of escaping acid fumes. Laboratory

ventilation is now very good to excellent.

The Class 1 performance may not be an important factor in contributing to

lower analytical blanks. However, the present design incorporates all of the

lessons learned in clean room use and design at NBS and should far out- last and

out-perform previous versions. The total cost for the project as completed was

$105 K, well below current commercial costs for a Class 100 room of similar

size and fittings.

9 . Development of a Computer-Controlled System for Analytical Separations by

Column Chromatoeraphv

H.M. Kingston and F. Ruegg

The first phase of a multi-year effort to develop an automated chemical

separation system has been completed. This phase consisted of system design,

equipment assembly and testing. Some new equipment was developed to perform

unique tasks. The logic and control programs for the application are currently

under development.

This system will perform chelation and ion-exchange separations which

isolate single trace elements or groups of elements from their sample matrix.

It will be used to support thermal isotope dilution mass spectrometry which

requires the isolation of each element prior to instrument introduction. Other

instrumental groups in the division will also be supported through the

separations by reducing instrumental interferences from matrix elements.

The system is unique in its design and concept. It relies on robotics for

the necessary movement of beakers and reagent dispensing. Actual chemical

handling is accomplished through the use of computer controlled valves. The

control of the entire chemical separation procedure is handled by a personal

computer that programs the robot and valves automatically. The robot con- troller is used to store subroutines that are organized and then called in

order by the computer. This is a conceptual departure from standard laboratory

robot applications.

This system has been designed as a multi -separation system. It is

designed to be a dynamic growing instrument which can learn new tasks that can

be integrated into its separations procedures. These procedures can be performed any number of times and in any sequence depending on the analyst's

requests. The format of the separation can be altered by the analyst for

individual sample set without reprogramming the robot. The reprogramming will

be done by the computer automatically after the chemist alters the separation

parameters

The system will perform many different separatipns which are repeated many

times in the course of yearly elemental determinations. In addition, it will

32
be capable of running separations which are now not widely used due to their

long time requirements and inability to be divided into manageable components.

Additional separations will be added in the future which will increase the

automated separations available to the analysts.

10 . Use of Voltammetry to Detect Electroactive Organic Products from

Microwave-Assisted Wet Ashing

K.W. Pratt and H.M. Kingston

Microwave -ass is ted dissolutions of biological samples have received

significant attention due to their improved rapidity and ease of control as compared to classical digestions at atmospheric pressure. A critical factor in

the evaluation of these dissolutions is the completeness of decomposition of

the original matrix. Research during the past year has demonstrated the

capability of voltammetry to indicate the effectiveness of microwave-assisted

dissolutions of biological samples.

Microwave-assisted dissolutions generally employ HN03 alone or a HN03 -HF

mixture as the solvent. For biological samples, the expected products of

incomplete dissolution include nitro compounds. This is particularly true for

components of the sample containing benzene rings or other aromatic structures,

which are highly resistant to decomposition. The resulting nitro compounds are generally electroactive and therefore may be detected polarographically

Evidence for such compounds was obtained during development of a procedure for

the polarographic determination of trace metals in SRM 1577a, Bovine Liver.

Polarograms obtained using microwave -assisted dissolution in HN03 + HF without

HC104 contained peaks at -0.23, -0.34, and 0.75 V vs. Ag/AgCl reference, in

acetate buffer. These peaks did not correspond to metals known to be present

in the sample. In addition, results obtained for Cu in these samples were

lower than the certified value. Further experiments demonstrated that these

unwanted peaks were eliminated or greatly reduced if the digested samples were

refluxed with boiling HCIO^ , which destroys any organic species not decomposed

by HN03

. Results found for Cu using HC104 agreed with the certified value.

Results obtained for Zn both with and without use of HC104 were in agreement

with the certified value.

The unwanted peaks occur at potentials characteristic of nitroaromatic

compounds (-0.2 to -0.5 V) and aliphatic nitro compounds (-0.7 to -0.9 V) at

this pH. Residue from the initial HN03 digestion was found to contain an organic component or components which were insoluble in hexane and cold water

but soluble in hot water and methyl isobutyl ketone (MIBK) . Following extraction into MIBK, the organic species could be re -extracted into aqueous NaOH.

Polarography of this NaOH extract in acetate buffer yielded a peak at -0.23 V

vs. Ag/AgCl. Ultraviolet spectra of the MIBK extract were consistent with the

presence of nitroaromatic compounds.

The above data all point toward acidic nitroaromatic compounds as major

components of the residue remaining after incomplete digestion of biological

samples in HN03

. Based on experimentally-obtained polarographic half-wave

potentials, the most likely compounds responsible for the peak at -0.23 V are

o-

m-and p-nitrobenzoic acids. These compounds are plausible products of

incomplete oxidative degradation of a biological matrix using HN03

. The other

peaks at more negative potentials likely result from other, non-acidic nitro

compounds. Investigations using HPLC with UV and electrochemical detection are

33
currently in progress to obtain further information about the products of

incomplete digestion of biological samples.

The sensitivity of voltammetric analyses to organic complexing agents is

demonstrated by the low values and poor precision obtained for Cu in digestions

using HN03 alone. Because of this sensitivity, voltammetry can serve as an excellent indicator for complete decomposition of organic sample matrices.

High precision for voltammetric determinations, coupled with the absence of

voltammetric peaks not associated with trace metals, indicates complete

decomposition of the sample matrix.

11 . Absolute Measurement of Aqueous Electrolytic Conductance Standards

Y.C. Wu and W.F. Koch

Measurements of aqueous electrolytic conductance are performed routinely

in a variety of disciplines and industries. Conductivity is a measure of the

ionic content in solution and thus has applications in pharmaceuticals, power

plants, rainwater, lake surveys, and oceanography, to name a few. The need for

standards for this measurement is immediate and work in the Electroanalytical

Research Group has begun to meet this need. A thorough review of the measurement of and standards for aqueous electrolytic conductance has been completed.

At present, the standards considered to be the most precise and accurate have

been set forth by the International Organization of Legal Metrology (OIML) , and

have been adopted by most standards organizations including ASTM. However, the

uncertainty assigned to these standards, especially the secondary standards, is

somewhat larger than would be expected from the physical aspects of the

measurement. It has been deemed necessary to investigate this deficiency

before issuing NBS standards which would propagate this uncertainty.

Specific conductance is the reciprocal of resistivity. Thus, through

resistance, it may be defined as K — G/R, where G is the ratio of 1/A (called

the cell constant), and R is resistance. G is defined in terms of the lines of

force traveling the distance (1) between the two electrodes over the effective

cross-sectional area (A) of these lines of force between the two electrodes.

Hence, the units of K are ohm-1

cm

-1

, or in SI units, S/m (siemens per meter).

To measure specific conductance on an absolute basis, both G and R must be

determined independently and on an exact (i.e.physical) basis. The measure- ment of R has been accomplished through the use of a Jones' Bridge, calibrated

by the Electricity Division at NBS. One approach to the attainment of G would

be the accurate measurements of 1 and A. Because of the geometry and design of

the conductance cell, these would be exacting and non- trivial measurements to

the accuracy required. Instead of this direct determination of 1 and A, a substitution method has been devised using a conductance cell of unique design.

The cell is similar to a Jones' cell, except that a portion of the distance

between the electrodes is now variable by the insertion of precision-bore

boros ilicate glass tubes of accurately known diameter and varying, but accu- rately known, lengths. It was a major engineering accomplishment to construct

a leak- free cell and required several modifications.

The theory behind this approach is as follows. The specific conductance

for a known concentration of electrolyte is a constant. The total effective

cross-sectional area is a fixed value for a given cell, and is composed of two

parts for the NBS cell: AQ , the area, due to the portion of the cell between

the electrodes and the connecting flanges; and A^ , due to the diameter (hence,

the area) of the replaceable center tube. A^ must be accurately known and the

34
diameter of the center tubes must be identical to that of the connecting tubes

of the body of the cell. The distance, 1, has two components: 1 0 , the portion

of fixed but unknown length between the electrodes and the connecting flanges;

and 1^, the accurately known length of the i'th center tube. The resistance,

R^, is the measured quantity, and can be separated into two components: r Q , due to 1 0 , Aq , and the conductivity of a given electrolyte; and r^, due to the

i ' th center tube . Thus

Ri - rQ + 1,/KA, (1)

and,

Ra = rQ + 12 /KA2

( 2 )

By performing the experiment with two center tubes of different lengths and

with Ax=» A2 and by solving the simultaneous equations, K can be determined.

Preliminary experiments using potassium chloride have been completed

successfully. Agreement with the OIML recommended value is within 0.02%.

Refinements to the cell and the procedure are being made to improve the

accuracy and precision, and will be completed in the coming year. This will

establish a new basis for all electrolytic aqueous conductivity standards and

represents the first high-accuracy endeavor in this field in over fifty years.

12 . High Ionic Strength pH Standards Research

Y.C. Wu, R. Roy, and W.F. Koch

The influence of ionic strength on the value of pH and on the measurement

of pH is a well-known, but poorly appreciated phenomenon. The recent work of

the Electroanalytical Research Group in the measurement of pH in acid rain of

low ionic strength gave clear evidence of the erratic nature of this measurement when the customary buffer standards of moderate ionic strength were used

to calibrate the conventional glass/reference pH electrode systems. This

difficulty was attributed partly to the difference in ionic strength between

rain water and the buffer standard, and partly to the asymmetry of the liquid

junction potential. It was satisfactorily resolved through the issuance of

strict measurement protocols and a control standard, SRM 2694, Simulated

Rainwater, which approximates the matrix and ionic strength of rainwater.

Attention has now turned to the equally vexing problem of pH measurements in

high ionic strength solutions, such as encountered in biological fluids and

seawater. The approach being investigated is similar to that used for acid

rain, i.e., match the ionic strength and matrix of the standard with that of

the solution to be measured.

To develop high ionic strength pH standards, a firm understanding and

basis in two fundamental areas must be attained: the activity coefficient as a function of ionic strength, and the influences of neutral salts and of organic

compounds on the value of pH. Research in the first aspect is well underway.

The approach is to use the Harned cell with dilute solutions of strong acids,

such as HC1 or H2 S04 [around 5x10“ A molal (m) ] to which neutral salts are added

to bring up the ionic strength from 0.1 to 1.0 m. The following

electrochemical cell was used:

Pt,H2 (1 atm.) | H+

(.0005 m) , KC1 (m2 ) , K2 S0A (m3 ) | AgCl.Ag

35
The concentration of KC1 (m2

) was varied from 0.005 to 0.02 in order to

facilitate extrapolation to zero chloride concentration for the calculation of

pH as shown below. The concentration of the neutral salt (m3

) was adjusted to

raise the total ionic strength (I) to the desired level. For the first set of

experiments, these concentrations were 0.1, 0.17, 0.3, 0.5, 0.7 and 1.0 molal.

The observed emf of the Harned cell, E, was used to calculate pH values as follows

-log aH7C1 = (E-E°)/k + log mcl (1)

where E° and k have their usual significance. Extrapolating -log vs

m^

to m^ — 0 yields

-log (

H7 ) 0 - p(aH7

)° - pH - log y°at j (2)

The quantity log 7^ t j was evaluated by the Debye -Huckel equation as a function

of I with two adjustable parameters i.e.,

log 7 - -(Az2 7l)/(1 + Ba/l) + bl (3)

where A and B are Debye-Huckel constants. The ion size parameter, a, and b are

the adjustable parameters and are obtained by least- squares fitting. Experiments were run over the temperature range 15 to 35 °C. The experimental

results indicate that equation (3) is a well-behaved function, and therefore can be used in the calculation of pH values for high ionic strength pH

standards.

The 0.0005 m strong acid, high ionic strength solution (1=0.7) prepared

and measured as above was used to calibrate a conventional glass/reference pH

measurement system prior to the measurement of the pH of "Copenhagen water" and

a simulated seawater solution. These two samples were also measured in the

Harned cell. The Harned cell approach is inherently more accurate than the

glass/reference electrode system, but is tedious and time-consuming. Furthermore, the Ag/AgCl electrode in the Harned cell is very sensitive to contamination and poisoning from components in real samples. This justifies the use of

the less accurate, but more convenient and robust glass/reference system, on

the condition that suitable standards are used to calibrate the system. The

agreement between the two methods was within 0.02 pH units and is considered

excellent. The values obtained for the seawater samples when measured with the

glass/reference electrode system calibrated with conventional buffer solutions

were biased by several tenths of a pH unit.

Additional research is needed to investigate the influence of organic

compounds on pH before high ionic strength buffer standards can be certified

and issued. This research will have considerable impact on the measurement of

pH in clinical and medical situations. Research is also underway to elucidate

the ionic interactions in a multi-component system. Moreover, thermodynamic

properties in a four component system, such as free energy, enthalpy, and

entropy, are being evaluated. This thermodynamic treatment in a complex

aqueous system is the first of its kind.

36
13 . Activation Analysis Using Cold Neutron Beams

R.M. Lindstrom, R. Zeisler, and M. Rossbach (Nuclear Research Center,

Julich, Germany)

The application of neutron- capture prompt gamma-ray activation analysis

(PGAA) has been pursued to date at only a few laboratories on a full-time

basis, partly because of the need for continuing access to a reactor neutron

beam. Irradiation times of several hours are required for most samples in

which many elements are to be measured, hence the throughput is low because

only one sample can be irradiated and measured at a time. The low sensitivity

is not due to a low neutron capture rate, but to a low detection efficiency for

the resulting gamma-rays, because of the necessary bulk of active and passive

shielding around the detector. Simply moving the detector closer to the sample

increases the efficiency, but at the cost of higher backgrounds and other

consequences of operating instruments in high radiation areas.

For chemical analysis, the ideal neutron field has the largest possible

number of activating particles per cm2 »s on the sample, and the smallest

possible number of interfering particles at the detector. A narrow beam is

desirable so that the gamma-ray detector can be moved near the sample and the

size of the shielding may be minimized. A guided beam of cold neutrons meets

these requirements exactly. The slowest neutrons from the reactor are reflected with high efficiency from the walls of the guide tube, while the fast

neutrons and gamma-rays decrease as 1/r2 with distance from the source. Therefore, the signal, to noise ratio is high. Since the apparatus is not near

the reactor and other experiments , the background from these sources is low and

there is room between experimental facilities to construct efficient shielding.

The capture rate is also higher with cold than with thermal beams. Since

capture cross sections for most target nuclei are inversely proportional to the

neutron velocity, the same number of neutrons per cm2 *s at 30 K gives three

times the reaction rate as at 300 K.

These expectations have been tested at the recently commissioned ELLA

Neutron Guide Laboratory at the FRJ-2 (DIDO) reactor of the Nuclear Research

Center Julich. Samples examined include Standard Reference Materials, and

industrial, biological, and environmental specimens as air filters. Synthetic

standards were irradiated to study the systematic errors in hydrogen containing

matrices and other limitations on accuracy with existing facilities. The main

advantages of cold neutron beams were verified in the experiments. The PGAA

sensitivity, expressed in counts/s»g, was nine times better than the published

sensitivity of the UMd-NBS facility. The hydrogen background in the spectrum

of a Teflon sample envelope was 100 /xg, four times lower than the better of two

major PGAA facilities.

In the analysis of plant and animal tissues, the limiting factor for both

the sensitivity and the accuracy of PGAA determinations is the amount of

hydrogen in the sample. The strong hydrogen capture gamma-ray at 2223.2 keV is

accompanied by a high Compton continuum, making the capture lines of other

elements below 1995 keV much less sensitive than they would otherwise be.

Active Compton suppression can reduce this baseline substantially. With the

high gamma-ray detection efficiency possible with cold neutron beams, the

practical limitation on the analytical usefulness of PGAA will be the ability

to collect data at high counting rates without distortion. With large Ge

detectors coupled with compact high-Z gating detectors, Ge-Ge coincidence

counting may cleanly resolve interfering lines in a crowded spectrum. Further

37
enhancement in sensitivity is possible since neutron optics may be used to

focus cold neutrons onto a small area. The techniques developed for the microscale electron- and ion-probe analogs of this situation are directly applicable

for the formation of two-dimensional images, with millimeter resolution, of the

elements which produce prompt radiations under neutron bombardment.

14 . The Determination of Chromium- 50 in Human Blood and Its Utilization for

Blood Volume Measurements

R. Zeisler and I. Young (NIH)

Systematic studies involving the measurement of maternal blood volume

increases are needed since subnormal increases have been associated with

maternal complications and intrauterine growth retardation in a few instances.

To establish a possible link, a new measurement procedure for the maternal

blood volume is required that would be accurate enough to determine the

relatively small differences between normal/subnormal increases during

pregnancy.

Currently, only the radioisotope dilution technique employing chromium- 51

(Cr-51) as a label for red blood cells can provide results with a standard

error smaller than 5%. However, this technique cannot be used with pregnant

women and also would impose severe restrictions on a large scale field study

because of the radioisotope involved. Therefore, the Cr-51 radioisotope

technique should be replaced by a dilution technique that utilizes enriched

chromium- 50 (Cr-50) as a label. The Cr-50 can then be determined by

instrumental neutron activation analysis or mass spectrometry.

The current investigations focus on the development of an INAA procedure

for the determination of red cell blood volumes (RCBV) . Although INAA procedures were introduced in the 1970' s to measure the stable isotope tracer Cr-50

in several clinical applications, the procedure was not routinely implemented

for RCBV determinations. A possible reason for this may be the fact that low

level determinations of Cr-50 (a 4.35% abundant isotope of natural chromium)

are needed for reliable results. These were unavailable at the time.

Recently, the knowledge about sources of contamination and the experience in

contamination control has enabled us to determine chromium at naturally

occurring low levels in such difficult samples as blood, serum, etc.

Besides the establishment of validated sampling procedures for the

clinical blood samples, additional precautions were needed for the stable

isotope technique with INAA because of interfering activation reactions and

small activities produced. These were resolved with irradiations in highly

thermalized neutron fields and background reduction during counting by Compton

suppression. The application of the procedures to the measurement of natural

chromium in total blood yielded the first results reported by INAA at a consistent low level of < 2.5 ng/mL (0.3 to 2.5 ng/mL) in samples from human

volunteers and rhesus monkeys.

Based on the INAA procedure, a new approach to the blood volume measure- ment via Cr-50 isotope dilution has been developed. It utilizes the ratios of

the induced activities of Cr-51 to the iron-59 (Fe-59) instead of the

calculation of specific activities or concentrations since the iron

concentration in the blood cells remains unchanged during the dilution experiment. This makes the method independent of sample size and irradiation and

counting parameters that may add to the uncertainty of the measurements. Only

38
the volume or mass of the labeled blood which is injected into the subject's

blood stream for dilution must be known exactly. The dilution factor is then

determined on a second blood sample and the volume can be calculated. The

estimated uncertainty for this procedures is not exceeding several percent and

results may be more reliable than with the classical Cr-51 procedure. A first

comparison of the two techniques confirmed this estimate. Due to its

simplicity and inherent accuracy and precision, this novel approach is well

studied as a clinical tool to study problems associated to the maternal blood

volume

15 . Evaluation of USDIET-I Total Human Diet Samples for Nutritional

Constituents

G.V. Iyengar (USDA)

A multi-nation study, sponsored by the International Atomic Energy Agency,

is aimed at obtaining comparative data on dietary intakes of 25 biologically

important minor and trace elements in a variety of developed and developing

countries. Three Federal Agencies, namely the National Bureau of Standards

(NBS), the Food and Drug Administration (FDA) and the U.S. Department of

Agriculture (USDA) are participating in this study. The scope of the study

provides an unique opportunity to develop a coordinated approach by the

collaborators of these 3 agencies for the U.S. part of the study.

The combined expertise of the participants is aimed toward the needed

developments and improvements of analytical methodology for the accurate

assessment of the dietary intakes of trace elements. Aspects of quality

assurance in sampling, sample preparation, analysis and data evaluation have

been addressed by intercomparison studies of minor and trace elements in

dietary reference materials (NBS Rice Flour SRM 1568a, NBS Wheat Flour SRM

1567a and two mixed diet samples, namely IAEA-H9 and TDD- ID) using different

analytical techniques. Precision and accuracy aspects related to Flame Atomic

Absorption Spectrophotometry, Atomic Emission Spectrophotometry with an inductively coupled plasma source and Neutron Activation Analysis were evaluated by analyzing the same test materials by all the three methods.

As a contribution to this project, a benchmark mixed U.S. diet research

material using 201 different foods from the FDA Total Diet Study (TDS) has been

prepared. According to the FDA-TDS study, a 25-30 year old male consumes daily

a total of 3075 g from these 201 foods. This represents the group with highest

caloric intake per day and has been used as a basis for all the calculations in

the present study. The first batch comprises about 10 kg of mixed diet.

Proximate analysis has been carried out on USDIET-I (fresh material) and

the following results were obtained; total volatiles = 83.8%, ash content

0.66%, fat = 2.92%, protein - 3.42%, carbohydrates = 9.2%, and total caloric

energy (kcal/100 g) =» 76.76.

Over 30 minor and trace elements have been characterized in USDIET-I using

a combination of analytical techniques. A comparison of the daily intakes of

Ca, Cu, Fe, Mg, Mn, Na, P, and Zn from this total diet material with those of

FDA-TDS figures calculated from single food analysis results showed that the

mixed diet concept is a viable approach. The daily intakes from USDIET-I were

also compared with the Recommended Daily Dietary Allowances suggested by the

National Academy of Sciences. The agreements were generally very good.

Additionally, analysis for a number of elements such as Cd, Cr, Hg, and Mo that

39
occur at low concentration levels in 'individual foods, demonstrated the

feasibility of a reliable assessment of their daily intake by use of a total

diet material, e.g., USDIET-I.

A number of organic nutrients have also been determined in USDIET-I, and

their stability during storage is being evaluated. The initial findings

suggest that USDIET-I may also be useful to develop reference materials for

organic nutrients. There is a great need for these types of reference

materials. Thus, it may pave the way for considering production of a single

SRM certified for both organic and inorganic nutrients.

Simultaneously, the long-term implications of biomonitoring of foods is

being studied by storing about 3 kg of USDIET-I as originally composited.

Dietary collections from different regions of the U.S. are currently underway.

Representative portions of these total diets from future collections will also

be preserved in the Biomonitoring Specimen Bank.

16 . Precision in Routine INAA Over a Two Year Period at NBSR

M.J, Blackman (Smithsonian Institution)

Beginning in June 1984 and continuing to date, aliquots of SRM 697 - Brick

Clay have been included as a check standard in 61 separate irradiations of

archaeological ceramics. The goals of the analysis of the ceramics were to

routinely analyze a large number of samples (1100) for as many elements as possible (32 sought) with as much precision as possible. Working within these

constraints, irradiations and counting times could not be tailored to specific

elements

The irradiations were carried out with reactor power at 10 mw in the RT-3

pneumatic facility and with reactor power at 20 mw in the RT-1 and RT-4

pneumatic facilities. The length of the irradiations were varied in accordance

with the neutron flux in each facility so that the fluence was approximately

the same. Samples and standards, in 0.5 mL polyethylene microcentrifuge tubes,

were packed in a single band in the "rabbit" to minimize linear flux gradients.

No special attention was given to the placement of standards or check standards

within the band, and therefore any radial flux variation was not controlled.

The gamma counting was carried out on two different detectors with similar

resolution, but quite different counting efficiencies (8.3% vs. 34.8%). Two

different automated sample changers were used, one with a fixed geometry of 10 cm and the other with variable geometry. Each sample was counted twice, the

first count after a 5 day decay and the second after at least a 30 day decay.

The counting times were varied according to the detector efficiency and the

sample geometry so that the counting statistics were approximately equal for

each element determined in each aliquot.

Initially about 10 grams of SRM 679 was dried for 24 hours at 110 °C and

cooled and stored in a desiccator. Fifty four nominal 1.00 mg aliquots were weighed as needed over the two year period, in addition, seven nominal 40 mg.

aliquots were also analyzed in separate irradiations. The initial stock of SRM

679 was periodically redried. During this period at least three different

balances were used for weighing.

SRM 1633 (coal fly ash) was the comparator standard used to quantify 23

elements in SRM 679. Commercially available computer software was used to

process the gamma ray data with several upgrades and a shift in computer

40
systems occurring during the duration of the experiment. In summary, while the

requisite care in accordance with good analytical procedures was taken for each

analysis, there was a great deal of variability in irradiation facilities,

counting equipment, and processing software. The data set for SRM 679 ought

then to provide a baseline for analytical precision in instrumental neutron

activation analysis over time at a single facility.

The results of 54 analyses of nominal 100 mg samples show that of the 23

elements quantified in SRM 679, over half (14) have a precision of better than

5% (1 standard deviation) , with five elements better than 2% precision. Only

three elements had precisions worse than 10% Ba-12.9%, Tb-13.0%, and U-15.9%.

Typical counting statistics for each of these elements in SRM 679 are: Ba10.5%; Tb-10.0%; and U-13.3%. For these three elements, all but about 2 to 3%

of the sample variance can be attributed to counting error. When the elements

with very low counting errors (Sc, Co, La, and Sm) are examined, the sample

variance not attributed to counting error is 1 to 1.5%. All random and

systematic errors, exclusive of counting error, appear therefore, to contribute

only about 1.5% to the sample variance, this includes potential sample

inhomogeneity

The results of the 7 analyses of nominal 40 mg samples are comparable to

those for the nominal 100 mg samples. The concentrations for all 23 elements

fall within 1 standard deviation in the two sets. The implication is that to

within about 1.5% to 2.0%, 40 mg aliquots of SRM 679 and the standard SRM 1633 are both homogeneous and directly comparable to 100 mg. aliquots. Examination

of the data sets shows that for a large number of elements instrumental neutron

activation analysis can routinely achieve better than 5% precision regardless

of changes in irradiation facilities, instrumentation, and computer processing

software. With some special effort at tailoring irradiation and counting times

to the nuclides displaying less precision, precision of better than 5% could be

achieved routinely for all 23 elemental concentrations reported here.

17 . Determination of Silicon by Fast Neutron Activation Analysis

D.A. Becker

An instrumental neutron activation analysis method utilizing fast neutrons

has been developed for the determination of silicon in a variety of matrices.

This method has been applied to the certification of silicon in SRM 1632b,

Trace Elements in (Bituminous) Coal, and in the determination of silicon in a number of marine sediments

The nuclear reaction used for the analysis is the silicon- 29 (n , p)

aluminum-29 reaction, with counting of the 1273 keV gamma-ray (half-life is 6.5

minutes). The sample is irradiated in a boron nitride capsule, which absorbs

the thermal neutrons while passing the fast neutrons. This substantially

lowers the overall radioactivity of the sample, while not affecting the

analytic signal for silicon. In particular, the BN reduces the interference

due to production of aluminum- 28 by thermal neutrons.

The University of Maryland nuclear reactor was used for the irradiations,

since its design (light water cooled and moderated) provides a greater

intensity of fast neutrons than the NBS reactor, even though the thermal

neutron intensity is less than 3% of the NBSR (which was designed specifically

to provide a maximum intensity of thermal neutrons) . Irradiation times ranged

from one to six minutes, depending on the silicon concentration in the samples.

41
For the coal analysis, four bottles were analyzed in duplicate, with

sample sizes ranging from 0.58 to 0.75 g. The silicon concentration found was

1.35 ± 0.03% (S.D., Is). Good agreement was obtained between all four bottles.

For the sediment analysis (made as part of a series of specimen bank

samples for NOAA and described elsewhere in this report) silicon concentrations

ranged from 23 to 31%. Excellent agreement was obtained for check samples of

NBS/SRM 1646 (Estuarine sediment), the IAEA sediment samples, and NCR-Canada

reference sediments, although none of these are known to a high degree of

accuracy

From the above data, it is estimated that analysis for silicon using

aluminum- 29 can be made for 2 mg of silicon with approximately 3 percent

counting statistics, or 0.2 percent silicon in a one gram sample. Further, if no aluminum or phosphorus is present in the sample, this level could most

likely be lowered to 0.02 percent through use of the aluminum- 28 isotope. Work

is continuing on additional types of samples and to establish experimental

detection limits for silicon.

18 . Specimen Banking and Analysis in the National Status and Trends Program

R. Zeisler, S.F. Stone, B.J. Koster, and K.D. Diamant

Recently, environmental monitoring has been complemented by programs for

systematic and controlled long term storage of environmental samples, i.e,,

environmental specimen banking (ESB) . The necessity, usefulness and importance

of ESB has been demonstrated for current monitoring as well as for preserving

the representation of the past for examination in future years. In 1984, the

National Oceanic and Atmospheric Administration (NOAA) initiated a specimen

bank for estuarine and coastal samples as part of its National Status and

Trends (NS&T) Program. This specimen bank has been incorporated in the

research activities of the Pilot Environmental Specimen Bank which is housed at

NBS . The research includes all steps of the ESB operation with special

emphasis on quality assurance in the selection, collection, preparation,

storage, and analysis of marine samples according to validated procedures.

The NS&T program is sponsoring two monitoring projects for the U.S.

coastal waters: the Mussel Watch with 154 collection sites and the Benthic

Surveillance with 50 collection sites. The Mussel Watch collects bivalves and

sediments from tidal sites whereas the Benthic Surveillance collects bottom

feeding fish and sediments from estuarine and continental shelf sites. Over 40

sites nationwide are now included in the ESB. The sampling techniques applied

in these programs have been refined and modified in cooperation with the field

scientists to fulfill the requirements of the ESB and to ensure comparability

between the samples used in real time monitoring and the banked samples. Protocols have been developed for the sampling and preparation of the specimens

that greatly reduce the risk of contamination. Special tools and implements,

chiefly made from titanium and Teflon, are used to prepare the samples for

transport and storage at liquid nitrogen temperature. The samples are prepared

for analysis in a clean- room by contamination free blending (sediments) or cryogenic homogenization (tissues) in Teflon disk mills.

A unique sequence of instrumental analytical methods involving x-ray

fluorescence and neutron activation analysis procedures has been employed for

the determination of 44 elements in marine bivalves. The individual procedures

are a x-ray fluorescence method based on backscatter with fundamental parameter

42
corrections, prompt gamma activation analysis, and neutron activation analysis

with instrumental and radiochemical procedures. This analytical approach has

been expanded to include the analysis of sediments and fish tissues. It is

possible to use a single subsample of about 250 mg and follow it through three

instrumental analyses, nondestructively , and a final radiochemical procedure,

which consumes the sample. The advantage of this approach is obviously the

reduced sample preparation which minimizes contamination or loss and assures

the true correlation of elements since all results are based on the same subsample, i.e., eliminating uncertainties due to sample to sample variations.

Analytical quality assurance has been accomplished by two means: first,

the sequential analytical procedure allows for the independent determination of

up to twenty elements by the two or three techniques involved. Since the same subsample is used by all techniques , any deviation of the results would

indicate a possible bias of one technique. Secondly, a sufficient number of

certified reference materials has been analyzed in parallel with the monitoring

samples. Good agreement of the analytical results with the certified values

will allow conclusions on the accuracy of the results obtained for the

monitoring samples.

Analytical data have been obtained for tissue samples from earlier bivalve

specimens and from sediment samples collected during the 1985 NS&T project

year. Because of the limited number of individual samples included so far in

the ESB, no assessment of the environmental status can be made at this time.

However, the primary emphasis of this work on high quality multielement determinations is documented in the results. The implementation of this analytical

approach on certified reference materials and control materials designed for

the NS&T program was successful.

19 . Determination of Total Zinc and Selenium in Human Blood Serum

R.R. Greenberg and G.V. Iyengar (USDA)

Establishment of precise and accurate analytical measurements for trace

elements in various biomedical specimens is crucial in order to provide reliable reference values for various applications in environmental and health

related investigations. In dealing with biological samples, it is not uncommon

to experience contamination or other methodological problems for even such

common elements as Cu, Fe, and Zn which occur at relatively high concentration

levels in many samples, such as blood serum, milk and urine. Other more

analytically difficult elements, e.g., Cr, Mo, Mn, and Se in blood serum,

present considerable challenges in obtaining meaningful analytical output. A

comprehensive quality assurance (QA) program is an essential requirement for

such studies, beginning with the biological and analytical validity of the

sampled material, followed by chemical analysis using critically controlled

analytical procedures. The requirement for QA is even more important if the

analyzed specimen is intended to serve as a reference material. For such uses,

it is not only desirable to generate a homogeneous material, but the measurement process applied should be capable of keeping the analytical errors as low

as possible, e.g., 1-2%. Such a measurement capability has been demonstrated

in our laboratory using instrumental neutron activation analysis (INAA) to

determine Zn and Se in a pooled human serum sample.

It is of practical significance to note that real world clinical specimens

are very precious, and often they are obtainable only in limited quantities,

e.g., blood serum. Therefore, implicit confidence in the chosen analytical

43
technique is necessary. There are many ongoing studies investigating the

effects of Zn and Se as protective agents against various types of cancers and

nutritional disorders. In view of the ubiquitous nature of Zn, it is often

easy to contaminate samples with this element during the sample preparation

steps prior to the actual determination step. Selenium is a particularly

difficult element to determine in many biological materials in view of the

volatility of a number of Se compounds, and the difficulty of decomposing some organo- selenium compounds. In this context, INAA offers a number of advantages

compared to other analytical techniques including: high sensitivity; lack of

matrix effects; minimal sample pretreatment; and non-destructive capability;

which eliminates analytical problems due to sample dissolution and to volatility losses of Se. In addition, the measurements can be repeated on the same samples, if necessary, utilizing the non-destructive nature of the technique.

Zinc and Se have been determined using INAA in seven replicates from a pooled human serum sample provided by the Organic Analytical Research Division.

Care was taken in each step of the analysis to keep the total systematic error

to one percent or less. Serum samples (approximately 500 mg each) were weighed

into acid-washed, ultrapure quartz vials, lyophilized at -40 °C, and sealed. A

quartz vial containing 500 nL of high purity (sub-boiling distilled) water was processed simultaneously with the samples as a blank, and two samples of Bovine

Liver, SRM 1577 were prepared for use as control samples. A new standard

solution was prepared gravimetrically containing both Zn and Se, and was deposited gravimetrically onto filter papers placed inside quartz vials. A Se

standard used in the certification analysis of Milk Powder, SRM 1549, was also

prepared in the same manner as an additional check. The height of the filter

papers in the quartz ampoules was exactly matched to that of the lyophilized

serum samples to eliminate both irradiation and counting geometry effects. The

samples, standards, controls and blank were irradiated together in two polyethylene irradiation containers (rabbits) for three hours in the RT-3 pneumatic

tube facility of the NBS reactor. One month after irradiation, the samples

were removed from the rabbits, washed in nitric acid to remove any surface

contamination from the quartz vials, and counted at a distance of 5 cm from the

gamma-ray detector for approximately one day each. Zinc was quantified using

the 1115 keV gamma-ray from Zn-65, and Se quantified using the 136, 265, and

400 keV gamma-rays from Se-75.

The results of this analysis are very encouraging. The observed precision

(relative standard deviations) for the concentrations of both elements in the

seven replicate samples was one percent, which was consistent with the counting

statistics. The Se results obtained using each of the three different gammarays were in close agreement, and the observed concentrations in the Bovine

Liver control samples were in close agreement with the certified values. The

two Se standards agreed to within a few tenths of a percent, and this differ- ence could be explained by the uncertainty due to counting statistics. The

concentrations of both elements were in the reference range for "normal"

individuals, indicating that this serum pool may be useful as a reference

material. It may also be used as a research material for validating methodologies for analytical techniques whose systematic errors are less completely

understood than are those of INAA.

In view of the closely bio-regulated concentration levels of many

essential elements in tissues and body fluids, it may be necessary to achieve

the level of precision and accuracy demonstrated in this investigation, to

successfully identify subtle differences, if any, in specimens from normal

individuals compared to those from pathological cases.

44
20 . Ion Chromatography Coupled to a Direct Current Plasma for On-Line Matrix

Separations

M. Epstein, W. Koch, K. Epler (University of Maryland), and T. O'Haver

(University of Maryland)

While the sensitivity of the Direct Current Plasma (DCP) rivals that of

the Inductively Coupled Plasma (ICP) , the DCP is far more sensitive to sample

matrix- induced enhancements or suppressions of emission intensity, which place

a finite limit on the accuracy of analytical determinations. Analysis with the

DCP requires the use of matrix-matching, electron density buffers, and standard

addition to assure the accuracy necessary for the certification of Standard

Reference Materials (SRMs). Furthermore, spectral interferences often require

a compromise in the choice of analysis parameters, such as the use of a less

sensitive emission line or the application of a correction factor, even with

the high-resolution echelle spectrometer. Therefore, in certain cases, an on-line separation/preconcentration scheme is needed to obtain a high sample

throughput as well as to improve sensitivity and accuracy. Ion chromatography

(IC) lends itself well to this application.

We have coupled an ion chromatograph to a wavelength-modulated DCP

spectrometer and have investigated its application to the determination of

phosphorus in several copper-based Standard Reference Materials. The most

sensitive phosphorus line, 213.618 nm, cannot be resolved from the copper

213. 598 -nm ion line in a copper-based matrix. The phosphorus 253. 565 -nm line

is not affected by copper radiation, but exhibits reduced sensitivity and a severe iron emission line overlap (253.560 nm) . The vacuum UV phosphorus lines

are’ not available using the echelle spectrometer. Thus, the determination of

phosphorus in copper-based SRMs is difficult without a separation step.

Using an on-line ion chromatographic separation with a cation separator

column, we have determined phosphorus in SRM 1251, with a result of 420 ±

40 Mg/g, compared to direct DCP analysis using the less sensitive 253.565 nm phosphorus line with • a correction factor for the iron interference (440 ± 20 Mg/g) and a wet-chemical analysis (392 ± 2 n g/g) . Complete chromatographic

separation of phosphorous and copper eliminated the phosphorus -copper spectral

interference using 50 pL of a solution of the SRM in 10% HCI/HNO 3 at a copper

concentration of approximately 2%. However, attempts to improve the sensitivity by using more concentrated solutions of the SRM, up to 10% copper, resulted

in overloading of the column and an incomplete separation. Further experiments

with a higher capacity column are now underway.

We are also experimenting with the technique of replacement ion

chromatography, where the analyte ion is exchanged in a post column with an equivalent number of replacement ions, which are quantified by a detector that

is extremely sensitive and specific for the replacement ion. Such a scheme

would be an ideal complement for an analytical method such as Laser Enhanced

Ionization Spectroscopy, which is extremely sensitive and specific for a limited number of elements.

45
21. Measurement of 9 Be- 10 Be Isotope Shifts using Doppler-Free Resonance

Ionization Mass Spectrometry

J.C. Travis, J. Wen, and J.D. Fassett

The high-resolution resonance ionization mass spectrometry (RIMS)

developments reported here are the result of an on-going collaboration with

T.B. Lucatorto, C.W. Clark, B.C. Johnson, and R.E. Bonnano of the Radiation

Physics Division, Center for Radiation Research. The analytical goal of this

effort is to demonstrate isotopically selective laser ionization in order to

enhance the ability of conventional mass spectrometers to measure extreme

(e.g., 10 10

) isotope ratios, such as encountered in carbon dating and other

geochronological applications. In order to achieve this enhancement, the

resonant laser must have a bandwidth much less than the optical isotope shift

between the two isotopes to be discriminated, and, in almost all cases, the

effects of the Doppler shifts must be drastically reduced.

A laser bandwidth of 150 MHz (0.005 cm

-1

) at 560 nm has been achieved by

substituting a single-longitudinal-mode (< 10 MHz bandwidth) continuous wave

dye laser, amplified in 5-ns bursts (at 10 Hz) by a pulsed dye amplifier (PDA),

for the normal dye laser head of the second generation RIMS instrument (RIMS

II). After frequency doubling the 25 mJ PDA output in an appropriate crystal,

2-3 mJ of light in the region of 280 nm may be obtained. Resonance ionization

of Be through high- lying ("70,000 cm

-1

) energy levels is achieved by uv twophoton excitation followed by photoionization with a more intense (~10 mJ)

infrared (1064 nm) laser beam obtained from the NdrYAG laser used to pump the

PDA.

In order to achieve Doppler-free two-photon linewidths, the uv beam is

retro -reflected through the mass spectrometer ion source so that the atomic

cloud is subjected to counterpropagating beams. In this manner, approximately

one -half of the two-photon excitations involve one photon from each of the two

beams. For an atom with an arbitrary velocity (speed and direction), this type

of excitation cancels the Doppler shift to first order, since the Doppler

shifts with respect to the two beams are equal in magnitude and opposite in

sign. The remaining two-photon excitation events, involving two photons from

the same beam, produce a "pedestal" approximately two orders of magnitude

broader and a similar factor lower in amplitude than the Doppler -free peak.

The ultimate in analytical performance will require the elimination of this

pedestal by means of perfectly circularly polarized laser beams and delta-m

selection rules. To date, we have achieved only partial cancellation, but have

reasonable expectation of being able to achieve the desired goal.

Doppler- free signals have been used for isotope shift measurements using

five Be transitions for a sample with a

9 Be: 10 Be ratio of ~2500:1. For the

Is 2 2s2 - ls 2 2s6s 1 S Q (71321 cm

-1

) transition, we have reported an optical

isotope shift of 13.31 ± 0.05 GHz, showing a predominant normal mass shift and

a small (~2%) specific mass shift. In spite of the demonstrated isotopic

ionization selectivity for Be, our "abundance sensitivity," or ability to

measure extreme ratios, is limited by the number density of the minor species

in the atomic vapor, and by the low duty factor of the pulsed laser system.

New atomization methods such as laser ablation and pulsed ion beam sputtering

are being explored to improve sensitivity.

46
22 . Ion-Pairing HPLC/AAS for the Determination of Cr(III) and Cr(Vl) in

Natural Water

A. Syty (Indiana University of Pennsylvania), R.G. Christensen, and T.C.

Rains

Although the toxic form of chromium is its +6 oxidation state, current

government regulations still limit only the total chromium concentration permissible in natural, drinking, and waste waters. Sensitive measurement of

total chromium in aqueous samples is simple and straightforward, but it is

obviously desirable to develop reliable, rapid, and sensitive methods for

selective determination of the Cr(III) and Cr(VI) species. Such endeavors have

recently received some attention in the literature, and papers have been

published describing separate determinations of hexavalent and trivalent

chromium using solvent extraction, coprecipitation, ion-exchange and chelating

resins. Many of these methods are time-consuming, involve a considerable

amount of sample manipulation, and are only selective for either one or the

other of the forms of chromium.

In previous work, we have experimented with the use of tetrabutylammonium

phosphate as a means of on-column preconcentration of Cr(VI) . In the present

work, we have investigated the ion-pairing reversed-phase HPLC speciation of

chromium and improved the method reported in the literature by making it faster

and generally applicable to all soluble compounds of Cr(III) , as well as Cr(VI) . We have also performed a time study of the reduction of Cr(VI) in

natural water spiked with Cr(III) and Cr(VI)

Separation of the chromium species was accomplished on a 4- cm long column

packed with 5-/im polymeric C 18 material. The optimum eluent composition proved

to be the following: distilled water containing 1x10“ 4 M tetrabutylammonium

phosphate, 1x10-4 M ammonium acetate, and sufficient acetic acid to lower the pH

to 3. 1-3. 2. The eluent was pumped through the column at 2.0 mL/min. The

column was coupled directly to the capillary of an atomic absorption

spectrometer and absorbance was measured at the 357. 8 -nm Cr line.

A sample of natural water was collected from a pond in mid-March and

another sample was collected from the same pond in mid-May when the content of

suspended solids was visibly much higher. Five aliquots of each sample were spiked with different levels of Cr(III) and Cr(VI) and sufficient HOAc was added to make the pH - 3. 1-3. 2. The initial concentrations of Cr(III) and

Cr(VI) varied from 0 to 2 /ig/mL. Standard Cr(III) and Cr(VI) mixtures

containing similar levels of each Cr species were used as comparison standards.

With the eluent composition given above, the elution times are 22 seconds

for Cr(III) and 70 seconds for Cr(VI). Since the Cr(VI) peak was slightly

broader in the natural water than in the standards, evaluation was done by

measuring peak areas. The detection limits were 40 ng/mL for Cr(III) and

80 ng/mL for Cr(VI)

All the spiked samples of pond water showed gradual decreases of Cr(VI)

and increase of Cr(III) as a result of reduction by the organic matrix of the

natural water. In all cases, the rate of Cr(VI) reduction was higher in the

water collected in May than in the water Collected in March. For example, it

took more than 20 days for 0.4 /ig/mL of Cr(VI) to decrease below the detection

limit in a sample of water collected in March, but the same level of Cr(VI) in

a sample of May pond water took only 5 days to decay below the detection limit.

47
The average recovery of total chromium added in all the spiked samples of

pond water was 101 ± 6%. This outcome supports the validity of the proposed

method for Cr(III) and Cr(VI) speciation and measurement in natural waters.

23 . Atomic Emission Homogeneity Testing of the New Magnesium Standard

Reference Material, SRM 656

J. Norris and T. Vetter

In cooperation with the metals industry, the first of a series of

magnesium SRMs has been prepared and tested. The SRM is in the form of a solid

disk 51 mm (2 in) in diameter and 8 mm (5/16 in) thick. The surface preparation for analysis by spark optical emission spectrometry is carried out by

facing the metal surface on a lathe. The account of material removed is

referred to as the surface depth.

No standard ASTM method exists for the spectrometric analysis of

magnesium, however, two suggested methods are available. Both suggested

methods call for sample excitation using a self - igniting bipolar capacitor

discharge in air with a graphite counter electrode. Although this condition

could have been implemented on the laboratory spectrometer, a total argon

atmosphere with a unipolar capacitor discharge was chosen for the homogeneity

test. For test purposes, a 15 s preburn and 20 s exposure period was employed.

To determine the within- sample homogeneity, the sample was divided into five

pie -shaped pieces, and these plus the center were analyzed multiple times. To

determine between- sample homogeneity, seven samples were "grabbed" from the lot

of 150 pieces. The spectrometer was calibrated using reference materials

originally obtained in 1952 and 1953 from Dow Chemical Co. and Apex Smelting

Co.

The results from the within/between seven sample test gave unexpected

variation from piece to piece as shown in Table 1 for aluminum.

Table 1. Aluminum SRM 656 Values in %

Piece Number % Al

1 8.64

2 8.81

3 8.61

4 8.81

5 8.60

6 8.86

7 8.71

Since the pieces had been selected at random and were run in random order, this

cyclic variation must have had a special cause. On examination of each sample,

it was determined that the samples had been surfaced on different sides with

one side having more material removed than the other due to mold marks. Two

additional pieces were selected to examine the effects of surface depth on results for aluminum. Successive depths of 1 mm were removed from each piece

and an analysis was performed at each depth. The results for this test for

aluminum are shown in Table 2.

48
Table 2. Aluminum SRM 656 Values in %

Analysis Depth

Cl mm steps') Sample 1 Sample 2

1

2

3

4

5

6

9.61

8.53

8.06

8.03

7.94

7.98

9.17

8.37

8.28

8.04

8.06

8.17

The correlation between %Al and depth is evident. When this material is

certified, a very careful sampling for chemical analysis will be made and the

certified portion specified. For a specified depth from the surface, any

portion of that surface may be used for analysis.

24 . Real-Time Metal Analysis of Ambient Aerosols

R.L. Watters, Jr., M.S. Epstein, and F. Shen

Air pollution monitoring is presently accomplished by analyzing

particulates collected on high-volume air filters. Although this method allows

preconcentration of the particulate matter, it has the disadvantage of being a batch process. On-line monitoring of air flows that contain particles is

possible by introducing the sample stream directly into an inductively coupled

plasma (ICP) or atomic absorption spectrometer (AAS) system.

As part of our material transport studies, we have used the spark

discharge as a means of producing fine particles in a stream of argon.

Emission spectrometry resulting from ICP excitation of the aerosol allows the

direct analysis of conductive metal samples. We have examined the potential of

this approach for analyzing particle streams in air by dilution of the argonborne aerosol with air and introducing the mixture into the ICP. Air entrainment into an ICP usually extinguishes the flame, so a special high-power

generator was used to sustain the plasma under various air- flow conditions.

An alternative approach using the air-acetylene flame of an AAS system

was found to be a simpler application for air samples. Although the atomic

absorption experiment is a single element determination, infusion of the air

stream into the flame is more straightforward than into the ICP. Conditions

for maximum sensitivity were reached when the sample introduction device was

set to provide the entire air flow (10 L/min) for the chemical flame. When ICP

excitation is used, less than 1 L/min of air can be tolerated.

Sample aerosol introduction devices that produce a positive air flow can

be connected directly to the ICP or AAS. However, to sample ambient air, a device is needed to draw in the aerosol and force it into the plasma or flame

region. A small regenerative blower was found to be suitable for ambient air

sampling. When coupled to either the ICP or the AAS systems, the blower was used to sample streams of air containing aerosols of Cu, Zn, and Fe

Calibration curves for Fe were linear and the detection limit was less than

0.01 /ig/L.

A field test instrument based on the AAS was assembled and taken to a smoke chamber to measure Fe aerosols. Fe was determined at a concentrated

49
smoke condition and at very low levels in the chamber. Consistently linear

response was observed for Fe concentrations from 15 jxg/L to 0.55 /xg/L using

different absorption lines of known relative sensitivities. The data were used

to predict that the lowest concentration that could be measured with a signalto-noise ratio of 20 was 0.15 /xg/L.

Recent work has focused on the problem of system calibration using aerosol

streams of known metal content. A conventional ICP nebulizer system was coupled to a desolvation system to produce dry aerosols in air. The desolvation system consists of a heated tube that evaporates the water droplets,

allowing the metal particles to separate in the stream. A cooling condenser

follows the heated tube and is used to remove only the water vapor from the air

stream. Standard solutions of various metals were nebulized and collected on a filter for a fixed time period. The collected aerosol was then dissolved from

the filter and analyzed by conventional ICP spectrometry to ascertain the

aerosol generator output. Stable conditions have been established whereby the

aerosol delivery rate is reproducible within ±5% relative. Changing the

concentration of the nebulized solution changes the concentration of the dry

aerosol in a controlled manner. A plot of the measured aerosol delivery rate

versus the concentration of the standard solution is linear between 0 and

0.7 /xg Fe/L measured aerosol concentration. The standard concentrations used

for these measurements ranged from 0 to 1000 /xg Fe/mL.

This system will be used to calibrate a new AAS system with the blower

connected to the sample inlet. Aerosol transport efficiencies for various

particle sizes and geometries will be measured and the effects of static charge

on. the particles will also be investigated. Measurement capabilities for

detecting Pb in automobile exhaust and other metals in smoke from incinerators

will be examined.

25 . Error Modeling and Confidence Interval Estimation for ICP Calibration

Curves

R.L. Watters, Jr., C.H. Spiegelman (NBS) , and R.J. Carroll (NBS)

A simple linear calibration function can be used over a wide concentration

range for the Inductively Coupled Plasma (ICP) due to its linear response. The

random errors over wide concentration ranges are not constant, and constant

variance regression should not be used to estimate the calibration function.

Weighted regression techniques are appropriate if the proper weights can be

obtained. Use of the calibration curve to estimate the concentration of one or more unknown samples is straightforward, but confidence interval estimation for

these results is less obvious. We have developed a method for modelling the

error along the ICP calibration curve and using the estimated parameters from

the fitted model to calculate weights for the calibration curve fit. Multiple

and single -use confidence interval estimates are obtained and results along the

calibration curve are compared. A particular feature of our approach is that

each iteration of the noise model fit is itself a weighted fit using estimates

from the previous iteration. We compared a model of standard deviation, Model

(1) with a model of variance, Model (2) to estimate calibration variability.

The final set of fitted variances is then used for the weighted regression of

the straight-line calibration curve. Confidence limits for concentrations

obtained using the calibration curve are calculated in a straightforward

manner

50
We examine the effects of calibration in various ICP analysis schemes in

the following example. The measurements were performed on a Perkin- Elmer

Plasma II ICP dual spectrometer system using the "A" monochromator. The

spectral bandpass of this monochromator is 0.007 nm. The spectral background

for Ni at 231.625 nm was measured and subtracted from the peak intensity for

each instrumental integration.

A total of nine Ni standard solutions were prepared gravimetrically along

with a reagent blank for the zero -standard. The concentrations of the standards ranged from 0 /ig/mL to 5.0275 jig/mL. The first analysis of the data

included all ten replicates at each of the ten standard concentrations. Since

the ICP is often used in laboratories where the sample analysis rate is high,

instrumental replicates are limited to as few as four. We therefore examined

this case by repeating the fit using only the first four replicates from each

set of ten. At this point the data were examined to test the assumption of

measurement independence and outliers. The fit of the estimated standard

deviation, a(x) for the 10 and 4 replicate cases according to model (1) yields

parameter estimates with small differences observed between the unweighted case and either of the two weighted fits. These differences have little effect on

the remainder of the analysis.

The fit of estimated variance, a

2 (x) , according to model (2) results in

the parameter estimates for unweighted, weighted by 1/s 4

, and weighted by 1/a 4 fitting. The method of weighting has a significant effect on the parameter

estimates. The weights, 1/a2

, for the fit of s using model (1) range over one order of magnitude. However, the weights, 1/a4

, for the variance fit of model

(2) range over two orders of magnitude. Although the high concentration points

are important for estimating this fit in the quadratic region, they have

extremely low weighting (1/a4 ). Therefore, the weighted fitting procedure will

have difficulty distinguishing between a linear and a quadratic model. Thus,

the estimates of the linear and quadratic terms will be poorly determined,

although the fit may be quite adequate.

We then examined the fit of the calibration function. Fitting effects on

the calibration curve with weights equal to 1.00, 1/s2

, and l/a2 w

were com- pared. The coefficient and standard error estimates for the 10 -replicate data

are quite similar regardless of weighting method. The unweighted case yields

slightly different (and erroneous) values for the standard errors. Of course

uncertainty interval estimates for an unknown sample concentration cannot be

calculated for the unweighted case since homoscedasticity would have to be

assumed. No single value for the standard deviation is suitable over the range

of calibration.

Using only 4 replicates causes a small change in the slope and a relatively larger change in the intercept, especially for the s

2 -weighting

case. However, the standard errors for these estimates are large enough to

minimize the significance of these differences. In practical applications a more limited range of calibration is appropriate when the chief concern is

trace analysis near the intercept. In terms of the standard error of the

estimated coefficients, the 4-replicate data represent a minor deterioration in

the variability of the fit.

Confidence interval estimation was carried out using a - 0.10. It was found that the uncertainty interval for the unknown sample measurement and the

calibration uncertainty band contribute almost equally to the total

uncertainty. Ignoring either source of variability will result in a

51
significant underestimation of the random error in a sample analysis.

Confidence intervals were calculated for 10 and 4-replicate calibration, for

single and multiple -use of the calibration curve, and for weighting with l/crw

2 and 1.00 as weights at each x^ . A comparison of single versus multiple use of

the calibration curve indicates the expected wider confidence intervals for

multiple use.

An important difference in interval width exists between the weighted and

unweighted cases. In the latter case, the value of o-w (x^) is 1.0 and at the

low end of the calibration curve, a is appreciably larger for the unweighted

fit than the weighted fit. The product, aw (x^) a, is therefore slightly larger

for the unweighted case. This causes an over-estimation of confidence intervals at the low end of the calibration curve.

At the high end of the calibration curve the predicted value for aw(x^)

for 4 replicates is greater than that for 10, causing the 4-replicate intervals

to be wider than the corresponding 10-replicate intervals. At this end of the

calibration curve, however, the interval widths for fitting with weights 1.0

significantly underestimate the true interval widths as estimated by the

weighted cases. The larger variance at the high end of the calibration curve,

as estimated by <?w (x^) accounts for this difference.

In summary, estimation of the error along the calibration curve is

important for weighted regression. Error modelling is more robust than using

the standard deviations of the calibration standard measurements themselves,

and the iterative weighted fitting procedure is generally applicable. Clearly,

if heteroscedasticity is ignored, confidence intervals will be too narrow at

the high end and too wide at the low end of the ICP calibration curve.

26 . The National Cancer Institute - National Bureau of Standards Round Robin

Data Analysis

F.C. Ruegg and R.C. Paule (NBS)

In cooperation with W.E. May and R. Schaffer of the Organic Analytical

Research Division and with the National Cancer Institute, round robin interlaboratory studies of a- tocopherol , ^-carotene, retinol, selenium and zinc in

human serum were performed. A suite of computer programs for data management

and reduction were written to analyze and display the data. The following

commercial software is used on this project: IBM Basica, Micro Data Base

Systems Knowledgeman/2 and Redding Group Graftalk. Knowledgeman/2 is a data

base manager which is used to store and manage all of the round robin data.

Graftalk is a graphics interpreter which is used for graphics output.

The data for each round robin analysis are entered into an IBM PC -AT

computer using the data base manager to allow the data to be edited and

manipulated. The data are sorted into the proper order using the data base

manager, and a program written in Basica then performs an analysis of variance

on the data.

The statistical analysis for each analyte and sample consists of:

1) Calculating a grand mean for each sample and analyte from all

reporting laboratories

52
2) Calculating the standard error of the average of each laboratory's

reported result

3) Calculating on both an absolute and relative basis the within and

between laboratory components of standard deviation for each analyte

An example of the program output is shown for round robin VII:

Standard Lab Analvte=Zinc

Serum Grand AVG S.E. AVG S Within S Between % CV AVG % CV X

040 0.801 0.018 0.033 0.059 2.2 8.4

041 1.049 0.020 0.037 0.070 1.9 7.5

042 1.471 0.026 0.021 0.096 1.8 6.7

043 1.855 0.037 0.027 0.137 2.0 7.5

047 0.674 0.027 0.026 0.073 4.0 11.5

048 1.394 0.048 0.027 0.136 3.5 9.9

Using Graftalk, a laboratory'

data for a selected analyte in several sera

amples can be plotted against the grand means for all reporting laboratories

and a linear least square fit can be calculated and plotted. The data from

previous round robins can be combined on the same graph if similar samples have

been analyzed in more than one round robin.

Thus far, we have analyzed the data from eight round robins. Each round

robin consists of measurements from up to 25 laboratories reporting a pair of

replicate measurements on five analytes for up to five different human sera, or on the order of 1200 numbers. This represents approximately 10,000 data

points. Each pair of data points requires five ancillary entries to identify

uniquely the pair requiring a total of approximately 25,000 computer entries.

This approach has proven to be an effective way to evaluate statistical control

of a laboratory's analysis of sera for the five analytes of interest.

27 . Optical Lifetime Measurements of Laser- Induced Ions in Flames

G.C. Turk and N. Omenetto (Joint Research Center, Ispra Italy)

Laser -enhanced ionization (LEI) spectroscopy utilizes direct electrical

detection of element- specific ionization induced as a result of resonant laser

photoexcitation. The experiments reported here have combined the ion

production aspects of LEI with ion detection by laser induced ionic fluorescence. Although direct electrical detection of laser- induced ionization is

certainly more sensitive, the magnitude and temporal profile of the direct

signal is very much dependent on the magnitude and uniformity of the electric

field, which is typically non-uniform and easily perturbed in a flame. Also,

electrical detection is non-specific, whereas fluorescence detection is ionspecific and is not subject to the same types of perturbation as electrical

detection. Studies of temporal and spatial profiles of the laser produced ions are straightforward.

Strontium atoms in the air-acetylene flame are directly photoionized in

two steps provided by one dye laser tuned to the resonance ground state transition (460.733 nm) and by the excimer pump beam at 308 nm, partially split from

the amplifier section of the dye laser. The ions produced are then monitored

53
by a third laser beam, collinear and counterpropagating in the flame, tuned to an ionic fluorescence transition and variably delayed with respect to the

ionizing beams.

With the ionizing laser off, the fluorescence probe laser excites only the

Sr+ ions that are present in the flame as a result of unassisted thermal ionization of the aspirated Sr. A natural thermal ionization fraction of 12% was measured for Sr at 10 ng/mL by observing the increase in the resonance atomic

fluorescence of Sr at 460.733 nm, which occurs when the thermal ionization is

suppressed by the addition of 1000 /xg/mL of Cs . Under the same conditions, the

magnitude of the laser-produced Sr+ ionic fluorescence was found to be 1.8

times that of the natural level, for a laser ionization yield of 25%. For

comparison, an ionization yield of 14% was estimated from the integrated

current in the direct electrical signal pulse, the estimated laser/atomic

interaction volume, and the estimated Sr atomic number density in the flame.

The time history of laser-produced ions showed two distinctly different

decay modes. An exponential decay of 58 ns time constant consumes 85% of the

laser produced ions before equilibrium is reached. The remaining 15% decay

takes place with an exponential time constant of 57 microseconds. The slow

decay is in a time range consistent with ion-electron recombination and with

the physical transport effects of diffusion and flame gas flow. Cs excesses of

10- , 30- , and 100 -fold decreased the slow decay component to 14.8, 7.2, and 2.9

microseconds, respectively. This behavior is consistent with expected

recombination behavior in the presence of the excess electrons provided by Cs

The fast decay process is unaffected by the presence of Cs buffer and is

too fast to be related to any physical transport. However, changes in the fast

decay behavior with fuel- to -oxidant ratio suggest that the fast decay is the

result of chemical reaction of Sr+ with flame constituents. In the theoretical

models of the LEI process, which have been developed using rate equation

analysis, the only ion loss mechanism considered has been that of recombination. The possibility of a very fast chemical reaction loss has never been

considered, and further study will be necessary to evaluate the consequences of

such fast decay.

28 . Standard Reference Materials

B.I. Diamondstone

This year has been the first full year during which the Division has

implemented the concept of "Technical Champions". This involves the use of

selected senior staff to interact with the project manager from the Office of

Standard Reference Materials (OSRM) to provide technical oversight for the

entire process of producing a Standard Reference Material (SRM) . The two major

projects that have been implemented under this program are the preparation of a replacement Trace Elements in River Sediment SRM and the preparation of a new Trace Elements in Bovine Serum SRM. Both projects are in process and the

interaction between Division 551 and OSRM has been quite satisfactory.

Hopefully, this new concept will gain full acceptance and will prove to be an excellent way to establish a direct link between the analysts and the project

managers. To date, more than one dozen Technical Champions have been

identified and are at various stages in producing new standards.

During this year, considerable emphasis has been placed on important areas

of the SRM certification process. Attempts have been made to provide estimates

54
that are more accurate, both for the amount of time required to carry out

analyses and the cost of these analyses. Much discussion has revolved around

the use of preliminary analyses to identify potential problem areas that could

be encountered during the actual certification process. This has triggered a search for rapid, inexpensive, multi-element techniques which would be used to

avoid pitfalls which can delay predetermined deadlines and lead to expensive

cost overruns. In addition, considerable effort has been expended in the area

of identifying and resolving biases between techniques.

As in the past, there are three sources of support for work on SRMs

Scientific and Technical Research Services funds (STRS) provided by OSRM are intended for the preliminary research necessary to develop the methodologies

required for the actual production of SRMs; Working Capital Funds (WCF) are intended for the actual production of SRMs and; STRS funding from the Technical

Division is often used to resolve unforeseen analytical problems which occur

during the certification process. The relative amounts of funding from the

above mentioned sources are presently in the ratio of approximately 1:4:2.

Input to all SRM projects is provided by the entire scientific staff and most

often involves cooperative work by staff from all Groups in the Division.

Listed below are different areas of research that were funded by OSRM

during the past year.

Task

STRS Projects Supported by OSRM during FY86

Description

Phosphorus in Steels Research to eliminate the matrix effects and to

develop selective 'separation procedures for the

determination of 1-100 fig of P. Research is in

progress

Silicon in Fuels Research leading to the development of an improved

nuclear method for the determination of Si in

fossil fuels. Preliminary measurements have been

made and initial results indicate that analyses can

be carried out for samples containing 0.2% Si in a one gram sample.

SRM Analysis by RIMS Research leading to the determination of Cr, V, Ti,

and Mo in SRMs by RIMS. Work is in progress to

develop processing procedures and to develop the

systematics of the multielement experiment.

ICP-Mass Spectrometry Continued research leading to the application of

Inductively Coupled Plasma Mass Spectrometry to the

analysis of SRMs. Tin and lead have been

determined in Monel with no preconcentration.

pH Buffers Research leading to improved accuracy of pH

standardization. Work is in progress on long term

stability of electrodes and on the determination of

the ion size parameter.

Electrolytic Conductance Research leading to the determination of absolute

electrolytic conductance standards. Work is in

progress to replace existing Organisation Internationale de Metrologie Legale (OIML) standards

with the new NBS standards.

55
Once again, analyses were carried out on more than 60 different SRMs

covering a wide variety of matrices including metals, fossil fuels, foods,

glasses and environmental materials. In most cases, each certification

involved several or all of the Groups in the Division and required 20-30

individual analyses on each SRM. Examples of the SRMs worked on during the

past year are listed below:

Selected Standard Reference Materials Analyzed During FY86

SRM Number Title

2670 Freeze Dried Urine

2677 Be/As on Filters

88b Dolomitic Limestone

1549 Powdered Milk

97b Flint Clay

98b Plastic Clay

2689-2691 Fly Ashes

1638b Reference Fuel

1616-1617 Kerosene

1641b-1642b Trace Elements in Water

1575 Pine Needles

1572 Citrus Leaves

1567a Rice Flour

1568a Wheat Flour

931c Liquid Absorbance Filters

1634b Fuel Oil

679 Brick Clay

1632b Coal

1577 Bovine Liver

2423 Ductile Iron

C1248 Monel

2695 Fluoride in Vegetation

1244b -1247b Inconel and Incoloy

332 Copper Concentrate

2100 '

Spectrometric Solutions

120c Phosphate Rock

2694 Simulated Rainwater

1260-1265

' Low Alloy Steels

2676c Trace Metals on Filters

1930 Extended Range Filters

1621c- 1622c Residual Fuel Oils

2678,2680,2681 Blank Filters

As in the past, a number of elements were determined this year in some SRMs for which these elements were not certified in past years. These additional analyses are part of a program to continually update existing SRM

certificates in response to requests from customers. In addition, material

preparation is underway this year for the replacement Oyster Tissue SRM and the

Fluoride in Vegetation SRM, as well as a series of seven new Low Alloy Steel

SRMs

Among the new SRMs being worked on during the past year are the Extended

Range Filters, River Sediment, Low Alloy Steels, Leads, and Trace Metals in

Blank Filters.

56
C. Outputs and Interactions

(Inorganic Analytical Research Division)

1 . Publications

Barnes, I. L. , Brill, R. H. , Deal, E. C., and Piercy, G. V. , Lead Isotope

Studies of Some of the Finds from the Serce Liman Shipwreck, Proc . 1984

Symposium on Archaeometry, J. S. 'Olin and M. J. Blackman, Eds., Smithsonian Institution, Wash. DC. Accepted for Publication, in press.

Barnes, I. L. , Deal, E., Chase, W. T. , Holmes, L. , Meyers, P., and Sayre, E. V. , The Nine Tripods and the Six Formulas: Lead and Lead Isotope Ratios

in Ancient Chinese Bronzes, in Proc. 1984 Symposium on Archaeometry . J. S. Olin and M. J. Blackman, Eds., Smithsonian Institution, Washington, D.C.

Accepted for Publication, in press.

Barnes, I. L. , Brill, R. H. , and Deal, E. C., "Lead Isotope Studies of Early

Chinese Glasses," Proc. Symposium on Ancient Glass and Glass Making,

Beijing, August 27-31, 1984, Special Publication, American Ceramic

Society, Accepted for Publication, in press.

Barnes, I. L. , 1985 Table of the Isotopic Composition of the Elements, Report

to the IUPAC Commission on Atomic Weights and Isotopic Abundances,

February 1986.

Barnes, I. L. , Atomic Weights of the Elements - 1985, (Co-authors, Members of

The Commission on Atomic Weights and Isotopic Abundances), Pure Appl.

Chem. , in press

Beary, E. S., Brletic, K. A., Paulsen, P. J., Moody, J. R. , "Isotope Dilution

Mass Spectrometric Assay of Copper in Copper Ore Reference Materials , " Submitted to The Analyst . A special issue will contain selected papers

from the meeting in Bristol.

Beary, E. S., Gramlich, J. W. , Deal, E. C., Machlan, L. A., "The Determination

of Lead and Thallium in Human Liver Samples by Isotope Dilution Mass

Spectrometry," NBS Special Report to EPA.

Becker, D. A., "The Role of Reactor Characterization in NAA Quality Assurance,"

J. Radioanal. Nucl. Chem., (in press).

Becker, D. A., "Primary Standards in Activation Analysis," J. Radioanal. Nucl.

Chem., (in press).

Blackman, M. J., "The Provenience of Obsidian Artifacts from Late Chalcolithic

Levels at Aphrodisiacs, Turkey," in Prehistoric Aphrodisiacs . M.

Joukowsky, Ed. , Institut Superieur D'Archelogie et Histoire de L'Art Brown

University

Blair, W. , Olson, G., Brinckman, F. , Paule , R. , and Becker, D., An International Butyltin Measurement Methods Intercomparison: Sample Preparation

and Results of Analysis, NBSIR 86-3321, (February 1986).

57
Bowers, G. N., Jr. and Rains, T. C., "Total Calcium in Biological Fluids:

Measurement by Flame Atomic Absorption Spectrometry," Chapter 38 in

Metallobiochemistrv . J. Riordan and B. Vallie , Eds., Academic Press,

Submitted for publication.

Bowman, R. C., Jr., Robertson, R. E. , Konudsen, J. R. , and Downing, R. G.,

"Studies of Boron Implantation Through Photochemically Deposited Si02 Films on Hg1

_ xCdxTe," Proceedings of the International Conference on Optical and Optoelectronic Applied Sciences and Engineering, 1986 (In

press)

Carpenter, B. S., Gramlich, J. W. , Greenberg, R. R. , Machlan, L. A., DeBievre,

P., Eschbach, H. L. , Meyer, H. , Van Audenhove , J., Connolly, V. E.,

Trahey, N. M. , and Zook, A. C., "Standard Reference Materials: Uranium235 Isotope Abundance Standard Reference Materials for Gamma Spectrometry

Measurements," NBS Spec. Publ. 260-96, in press.

Carpenter, B. S., Gramlich, J. W. , Greenberg, R. R. , and Machlan, L. A.,

"Uranium- 235 Isotope Abundance Standard Reference Materials for Gamma

Spectrometry Measurements," NBS Spec. Publ. 260-96, in press.

Carpenter, B. S. and Pilione, L. J., "The Use of Delayed Nuclear Track Counting

for Determining Bismuth," Journal of Radioanalytical and Nuclear

Chemistry, to be Submitted for publication.

Carpenter, B. S., Horvath, C„, and Vogt," C. R. , "The Production of Porous

Microspheres by the Nuclear Track Technique," Nuclear Tracks and

Radiation Measurements, Submitted for publication.

De Bievre, P. and Barnes, I. L. , Table of the Isotopic Composition of the

Elements as Determined by Mass Spectrometry, Int. Jour. Mass Spectrom. Ion

Proc. , 65, 211-230 (1985)

Downing, R. G., Maki , J. T. , and Fleming, R. F. , "Application of Neutron Depth

Profiling to Microelectronic Materials , "ACS Symposium Series No. 295, L. A. Casper, Ed., 163-180, (1984).

Downing, R. G., Maki, J. T. , and Fleming, R. F. , "Analytical Applications of

Neutron Depth Profiling," Proceeding of the 1986 Modern Trends in

Activation Analysis, in press.

Fassett, J. D., Moore, L. J., Travis, J. C., and DeVoe , J. R. , "Laser Resonance

Ionization Mass Spectrometry," Science 230 . 262-267 (1985).

Fassett, J. D. and Kingston, H. M. , "Determination of Nanogram Quantities of

Vanadium in Biological Materials by Isotope Dilution Thermal Ionization

Mass Spectrometry with Ion Counting Detection," Anal. Chem. , 57, 2474-2478

(1985).

Fassett, J. D., Zeininger, H. J., and Moore, L. J., "Time-Resolved Magnetic

Dispersion for Large Isotope Ratio Measurement in Resonance Ionization

Mass Spectrometry," Int. J. Mass Spectrom. Ion Proc., 69., 285-296 (1986).

Fassett, J. D., Walker, R. J., Travis, J. C., and Ruegg, F. C., "Quantification

of Pulsed Ion Currents Produced in Resonance Ionization Mass

Spectrometry," Submitted for publication.

58
Fleming, R. F. and Lindstrom, R. M. , "Precise Determination of Aluminum by

Instrumental Neutron Activation," (Submitted to Proc. 7th MTAA,

Copenhagen, 1986)

Garry, V. F. , Pohlman, B. L. , Wick, M. R. , Garvey, J. S., and Zeisler, R. , "Chronic Cadmium Intoxication: Tissue Response in an Occupationally

Exposed Patient," Am. J. Indust. Med., in press, (1986).

Greenberg, R. R. , "Elemental Characterization of the National Bureau of

Standards Milk Powder Standard Reference Materials by Instrumental and

Radiochemical Neutron Activation Analysis," Anal. Chem. (In press).

Greenberg, R. R. , "The Role of Neutron Activation Analysis in the Certification

of NBS Standard Reference Materials," Proc. of the Seventh International

Conference on Modern Trends in Activation Analysis, in press.

Greenberg, R. R. , Fleming, R. F. , and Lindstrom, R. M. , "Elemental Characterization of Four Coal Standard Reference Materials via Instrumental Neutron

Activation Analysis and Neutron- Capture Prompt Gamma-Ray Activation

Analysis," through WERB; To be submitted for publication.

Greenberg, R. R. and Carpenter, B. S., "High Accuracy Determination of 235-U in

Non -destructive Assay Standards by Gamma Spectrometry," Journal of

Radioanalytical and Nuclear Chemistry, To be submitted for publication.

Han, K. and Koch, W. F. , "Determination of Ultra-trace Levels of Sulfide by Ion

Chromatography with Electrochemical Detection," Submitted to Analytical

Chemistry

Han, K. , Koch, W. F. , and Pratt, K. W. , "An Improved Procedure for the Determination of Iodide by Ion Chromatography with Electrochemical Detection,"

submitted to Analytical Chemistry.

Iyengar, G. J. V. and Tanner, J. T. , "Biological and Dietary Reference Materials for Organic and Inorganic Nutrients," Food Laboratory Newsletter,

No. 4, Sept. 85, pp. 20-25.

Iyengar, G. V. , Tanner, J. T. , Wolf, W. R. , and Zeisler, R. , "Preparation and

Characterization of Mixed Diet Composite USDIET-I: Determination of

Energy, Phytic Acid and Elemental Concentration," IAEA Coordinated

Research Programme on Human Daily Dietary Intakes of Nutritionally

Important Trace Elements, Report in preparation.

Iyengar, G. V. , "Sample Validity in Biological Trace Element Research Studies,"

J. Radioanal . Mucl. Chem., in press.

Kelly, W. R. , Fassett, J. D., and Hotes, S. A., "Determination of Picogram

Quantities of Uranium in Human Urine by Thermal Ionization Mass

Spectrometry," Health Phys . , in press.

Kelly, W. R. and Hotes, S. A., "The Importance of Chemical Blanks and Chemical

Yields in Accurate Chemical Analysis," Submitted to Anal. Chem.

59
Kelly, W. R. , "Determination of Sulfur in NBS SRM 2694 (Simulated Rainwater) by

Thermal Ionization Mass Spectrometry, Methods and Procedures Used at the

National Bureau of Standards to Prepare, and Certify SRM 2694. Simulated

Rainwater, and Recommendations for Use . W. F. Koch, ed. , NBS Spec. Publ.

260-106 46-51 1986.

Kingston, H. M. and Jassie, L. B. , "Microwave Energy for Acid Decomposition at

Elevated Temperatures using Biological and Botanical Samples," Accepted

for publication in Analytical Chemistry , scheduled for October, 1986.

Koch, W. F. , Han, K. , and Knoerdel, M. , "Determination of Fluoride, Chloride,

Nitrate, Sulfate, Ammonium, Sodium and Potassium by Ion Chromatography,

and Specific Conductance by Conductimetry , " Standard Reference Materials:

Methods and Procedures Used at the National Bureau of Standards to

Prepare. Recommendations for Use. Natl. Bur. Stand. (U. S.) Spec. Pub.,

260-106, 22-29 (1986).

Koch, W. F. and Liggett, Jr., W. S., "Critical Assessment of Detection Limits

for Ion Chromatography," submitted to ACS Symposium Series, "Detection

Limits: From Basic Concepts to Practical Applications".

Koch, W. F. , Marinenko, G. , Holland, L. A., and Paule , R. C., "Preparation and

Certification of Reference Materials for Rainwater Analysis," in Standard

Reference Materials: Methods and Procedures Used at the National Bureau

of Standards to Prepare. Analyze, and Certify SRM 2694. Simulated Rainwater. and Recommendations for Use . Natl. Bur. Stand. (U. S.) Spec. Pub.,

260-1-6, 22-29 (1986).

Koch, W. F. , Marinenko, G., and Paule, R. C., "An Interlaboratory Test of pH

Measurements in Rainwater," J. Res. Natl. Bur. Stand., 91(1), 23-32

(1986) .

Koch, W. F. , Marinenko, G., and Paule, R. C., "Development of a Standard

Reference Material for Rainwater Analysis," J. Res. Natl. Bur. Stand.,

91(1) 33-41 (1986).

Koch, W. F. , Editor, "Direct Potentiometric Measurements in Blood," Proceedings

of the Workshop on Direct Potentiometric Measurements in Blood.

Gaithersburg, MD, May 18-20, 1983. National Committee for Clinical

Laboratory Standards, Villanova, PA (1985).

Koch, W. F. , Ed. , Standard Reference Materials: Methods and Procedures Used at

the National Bureau of Standard to Prepare. Analyze, and Certify SRM 2694,

Simulated Rainwater, and Recommendations for Use . Natl. Bur. Stand. (U.S.)

Spec. Pub., 260-106, July, 1986.

Lashmore, D. S., Weishauss, I., and Pratt, K. W. , "Electrodeposition of NickelChromium Alloys," Plating and Surface Finishing, 7J3, 48-54 (1986).

Lauenstein, G. G., Schantz, M. M. , Wise, S. A., and Zeisler, R. , "Specimen

Banking in the National Status and Trends Program: Development of

Portocols and First Year Results," Proc. Oceans '86, September 23-25,

1986, To be published.

Leifer, R. , Juzdan, Z. R. , Kelly, W. R. , and Fassett, J. D., "Detection of

Uranium from COSMOS -1402 in the Stratosphere," Submitted to Science.

60
Lindstrom, R. M. and Anderson, D. L. , Analytical Neutron- Capture Gamma-Ray

Spectroscopy: Status and Prospects, S. Raman, Ed., Capture Gamma-Ray

Spectroscopy and Related Topic-1984" (AIP Conf. Proc. No. 125), Am. Inst.

Physics, New York 1985, pp . 810-819.

Lindstrom, R. M. , Activation Analysis of Semiconductor Materials, in " Microelectronics Processing: Inorganic Materials Characterization , " L . A

Casper, Ed., (ACS Symp . Ser. No. 295), Am. Chem. Soc, Washington 1986, pp

294-307.

Lindstrom, R. M. , Zeisler, R. , and Rossbach, M. , Activation Analysis Opportunities Using Cold Neutron Beams, Submitted to Proc. 7th MTAA, Copenhagen

1986.

Machlan, L. A., Gramlich, J. W. , Powell, L. J., and Lambert, G. M. , "Absolute

Isotopic Abundance Ratio and Atomic Weight of a Reference Sample of

Gallium," J. Res. Nat. Bur. Stand. (U.S.), in press.

Maki, J. T. , Fleming, R. F. , and Vincent, D. H. , "Deconvolution of Neutron

Depth Profiling Spectra," to be published in Nuclear Instruments and

Methods in Physics Research.

Marinenko, G., Paule, R. C., and Koch, W. F. , "Effect of Variables on pH

Measurement in Acid-Rain-Like Solutions as Determined by Ruggedness Test,"

J. Res. Natl. Bur. Stand., 91(1) . 17-22 (1986).

Mavrodineanu, R. and Burke, R. W. , "Chemical Calibration Standards for Molecular Absorption Spectrometry," Proceedings of the Conference: Advances

in Standards and Methodology in UV-Visible-NIR Spectrometry . Oxford,

England, September 14-17, 1986 (In press).

Michel, R. , Iyengar, G. V., and Zeisler, R. , Current Aspects of Multielement

Analysis in the Life Sciences, in Instrumental Multielement Analysis . Sansoni, B., Ed., VCH Publishers. Deerfield Beach, FL, 1985, pp . 607-619.

Moody, J. R. and Beary, E. S., "Apparatus for the Rapid Equilibration of

Moisture Sensitive Materials," in review, Submitted to Analytical

Chemistry

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

W. , "Resonance Ionization Mass Spectrometry of Carbon," J. Opt. Soc. Am. B

2B, 1561-5 (1985).

Myers, E. and Blackman, M. J., "Conical Plates of the Hispano-Moresque Tradition from Islamic Qsar es-Seghir: Petrographic and Chemical Analysis," La

Ceramica Medievale Nel Mediteraneo Occidental, pp. 55-68, Edizioni

All'Insegna Del Giglio, Florence, Italy.

Myers, E. , "Chemical Composition of the Sackler Maiolica Ceramics," Appendix in

Forthcoming Catalogue on the Sackler Maiolica, Lois Katz, The Arthur M.

Sackler Foundation, New York, New York.

Olin, J. S. and Blackman, M. J., "The Proceedings of the 1984 Archaeometry

Symposium," Smithsonian Institution Press, Washington, D. C., in press.

61
Paule, R. C., Marinenko, G., Knoerdel, M. , and Koch, W. F. , "Ruggedness Testing

- Part I: Ignoring Interactions," J. Res. Natl. Bur. Stand., 91(1) . 3-8

(1986).

Paule, R. C., Marinenko, G., Knoerdel, M. , and Koch, W. F., "Ruggedness Testing

- Part II: Recognizing Interactions," J. Res. Natl. Bur. Stand., 91(1) . 9-15 (1986).

Pratt, K. W. and Koch, W. F. , "Determination of Trace-Level Chromium (VI) in

the Presence of Chromium (III) and Iron (III) by Flow Injection

Amperometry , " Anal. Chem. , 58(1) . 124-127 (1986).

Pratt, K. W. and Koch, W. F. , "High Accuracy Differential Pulse Anodic Stripping Voltammetry Using Indium as an Internal Standard," Submitted to

Analytical Chemistry.

Ratzker, M. , Lashmore, D. S., and Pratt, K. W. , "The Electrodeposition and

Corrosion Performance of Nickel-Phosphorous Amorphous Alloys," Plating and

Surface Finishing, in press.

Riley, J. E., Jr. and Lindstrom, R„ M. , "Determination of Boron in Borosilicate

Glasses by Neutron Capture Prompt Gamma-Ray Activation Analysis," through

WERB; submitted to Anal. Chem., October 1985; to be submitted to J.

Radioanal. Chem.

Stone, S. F. , Hancock, D., and Zeisler, R. , "Characterization of Biological

Macromolecules by Electrophoresis and Neutron Activation," Journal of

Radioanalytical and Nuclear Chemistry, in press.

Stroube, W. B., Jr. and Lutz, G. J., "Analysis of Foods for Iodine by Thermal

Neutron Activation Analysis," J. Radioanal. and Nuclear Chemistry, in

press

Syty, A., Christensen, Jr. G., and Rains, T. C., "Trace Determination of Cr(VI)

by LC/AAS with On-Line Preconcentration," at. Spectrosc., 2. (1986).

Syty, A. , Christensen, R. G. , and Rains, T. C. , "Ion Pairing HPLC/AAS for the

Determination of Cr^-^' and Cr^I) i n Natural Waters," Anal. Chem.,

Submitted for publication.

Tanner, J. T. , Smith, J. S., Angyal , G., Defibaugh, P. W. , Villalobos, M. C.,

Bueno, M. P. , Iyengar, G. V., Worf, W. R. , and Zeisler, Jr., in Search of

SRMs for Organic Nutrients . 2nd International Workshop on Biological

Reference Materials, W. R. Wolf, Ed., in press.

Turk, G. C. and Omenetto, N. , "Optical Detection of Laser Induced Ionization:

A Study of the Time Decay of Strontium Ions in the Air-Acetylene Flame,

Appl. Spectrosc., in press.

Turk, G. C., Ruegg, F. C., Travis, J. C., and DeVoe , J. R. , "Three-Dimensional

Atomic Spectra in Flames Using Stepwise Excitation Laser -Enhanced Ionization Spectroscopy," accepted for publication in the Nov. -Dec. 1986 issue

of Appl. Spectrosc.

62
Walker, R. J. and Fassett, J. D. , "Isotopic Measurement of Microgram and SubNanogram Quantities of Rhenium and Osmium by Resonance Ionization Mass

Spectrometry," Submitted for publication.

Watters, R. L. , Jr., "Quality Assurance in Metals Analysis Using the Inductively Coupled Plasma," Proceedines of the ASTM Symposium on Chemical

Analysis of Metals. 50th Anniversary of Committee E-3 . June 19, 1985, ASTM

Standardization News, in press.

Watters, R. L. , Jr., Epstein, M. S., Rains, T. C., and Comeford, J. J.,

"Progress in Real-time Analysis of Metal Aerosols," Proceedings of the

1986 Chemical Research and Development Conference . Department of the Army,

Edgewood, MD, 1986, In preparation.

Watters, R. L. , Jr., Spiegelman, C. H. , and Carroll, R. J., "Heteroscedastic

Calibration in Inductively Coupled Plasma Spectrometry," Submitted.

Watters, R. L. , Jr. and Wood, L. J., "The Meaning of Blanks in Detection Limit

Measurements for Atomic Spectrometry," Proceedings of the Symposium,

Detection Limits: From Basic Concepts to Practical Applications . ACS

Symposium Series, 1986, In preparation.

Wise, S. A. and Zeisler, R. , Eds., "International Review of Environmental

Specimen Banking," Natl. Bur. Stand. (U.S.), Spec. Pub. 706, 1985, p. 62.

Wise, S. A. and Zeisler, R. , "The U. S. Pilot Environmental Specimen Bank

Program," Natl. Bur. Stand. (U.S.) Spec. Pub. 706, 34-45, (1985).

Wu, Y. C., Koch, W. F. , and Marinenko, G., "Thermodynamic Properties of DC1 in

D2 0 Solution, (0.002 to lm) from 5 to 50 C," J. Soln. Chem. , 15, 675-692

(1986) .

Wu, Y. C. and Koch, W. F. , "The First and Second Dissociation Constants of

Deuterio-o-phthalic Acid in D2 O from EMF Measurements from 5 to 50 C," J.

Soln. Chem., 15, 481-493 (1986).

Zeisler, R. , Stone, S. F. , Fitzpatrick, K. A., and Wise, S. A., "The Eighth U.

S. - German Seminar on State and Planning of Environmental Specimen

Banking and the International Review of Environmental Specimen Banking,"

Natl. Bur. Stand. (U.S.), Spec. Pub. 706 1-3, (1985).

Zeisler, R. , "Foreword: Symposium on Standardization of Collection and

Preparation of Biomedical Samples for Trace Element Analysis," NBS J.

Res. , 91, 45-56 (1986) .

Zeisler, R. , "The Sampling and Analysis of Human Livers," NBS J. Res., 91., 75-

85 (1986).

Zeisler, R. and Young, I., "The Determination of Chromium-50 in Human Blood and

Its Utilization for Blood Volume Measurements," J. Radioanal. Nucl. Chem.,

in press.

Zhang, Y. Z., Watters, R. L. , Jr., and Rains, T. C., "Determination of

Phosphorus in Refractory Materials by Inductively Coupled Plasma Atomic

Emission Spectrometry," Submitted for publication.

63
Zielinski, W. L. , Jr., Hughes, E. E., Barnes, I. L. , Elkins, J. W. , and Rook,

H. L. , High Accuracy Standard and Reference Methodology for Carbon Dioxide

in Air, U. S. Department of Energy, DOE/PR-06010- 31 , TR033, 1986.

2 . Talks

Epstein, M. S., Turk, G. C., and Travis, J. C., "Evaluation of ND-^-YAG and

Copper-Vapor Pumped Dye Lasers as Excitation Sources for Atomic

Fluorescence Spectrometry," 12th Annual Meeting of the Federation of

Analytical Chemistry and Spectroscopy Societies, Philadelphia, PA, October

2, 1985. Invited .

Travis, J. C., Fassett, J. D., and Moore, L. J., "Thermal Vaporization Reson- ance Ionization Mass Spectrometry," 1985 Annual Meeting of the Optical

Society of America, Washington, D.C., October 17, 1985. Invited .

Gramlich, J. W. , "The Determination of the Atomic Weights of the Elements at

NBS , " Department of Chemistry, George Washington University, Washington,

D.C., October 25, 1985.

Rains, T. C., "The Art of Sample Preparation for Spectrochemical Analysis,"

"Determination of Trace Elements in Refractory Materials by Atomic

Absorption and Emission Spectrometry," "Applications of Electrothermal

Atomization Atomic Absorption Spectrometry," and "Research and Development

in Atomic Spectrometry," Shanghai Institute of Ceramics, Shanghai, China,

October 25-31, 1985. Invited .

Walker, R. J. and Moore, L. J., "Resonance Ionization Mass Spectrometry (RIMS)

for the Measurement of Multi-Element and Re-Os Isotopes in Crystal Rocks,"

96th Annual Meeting of the Geological Society of America, Orlando, FL,

October 30, 1985.

Rains, T. C., "Trace Elemental Analysis in Environmental Samples by AAS ,

Shanghai Institute of Testing Technology, Shanghai, China, November 1,

1985. Invited .

Rains, T. C., "The Art of Sample Preparation" and "Research and Development in

Atomic Spectroscopy at NBS," Institute of Geochemistry, Guiyang, China,

November 3-5, 1985. Invited .

Kelly, W. R. , "The Determination of Sulfur and Uranium by Thermal Ionization

Mass Spectrometry," Department of Chemistry, University of Missouri -Rolla

November 4, 1985. Invited .

Travis, J. C., "Resonance Ionization Mass Spectrometry for Trace Metal Analysis," Department of Chemistry, University of Michigan, Ann Arbor, MI,

November 5, 1985. Invited .

Rains, T. C., "Characterization of Standard Reference Materials by Atomic

Absorption and Inductively Coupled Plasma Atomic Emission Spectrometry,"

and "The Art of Sample Preparation," Institute of Geochemistry, Guilin,

China, November 8-9, 1985. Invited .

Rains, T. C., "Characterization of Standard Reference Materials by Atomic

Absorption Spectroscopy," Institute of Environmental Chemistry, Beijing,

China, November 11, 1985. Invited .

64
Rains, T. C., "The Art of Sample Preparation," Research Institute for Atomic

Energy, Beijing, China, November 12, 1985. Invited .

Rains, T. C., "Characterization of Standard Reference Materials by Atomic

Spectroscopy," Research Institute for Standard Materials, Beijing, China,

November 13, 1985. Invited .

Rains, T. C., "Trace Elemental Analysis in Ores, Minerals and Metals by AAS , " General Research Institute of Mining and Metallurgy; Beijing, China,

November 16, 1985. Invited .

Rains, T. C., "Research and Development in Atomic Spectroscopy at NBS , " Spectroscopy Society of China, Xang Shan Hotel, Xang Shan, China, November

17, 1985, Plenary Lecture .

Rains, T. C., "Characterization of Standard Reference Materials by Atomic

Absorption and Inductively Coupled Plasma Atomic Emission Spectrometry,"

1st Beijing Conference and Exhibition on Instrumental Analysis, Beijing,

China, November 18, 1985, Plenary Lecture .

Travis, J. C., Fassett, J. D. , and Moore, L. J., "Resonance Ionization Mass

Spectrometry, First International Laser Science Conference, Dallas, TX,

November 20, 1985. Invited .

Rains, T. C., "Trace Elemental Analysis in Non-Ferrous Metals by Atomic

Spectroscopy," General Research Institute for Non-Ferrous Metals, Beijing,

China, November 21, 1985. Invited .

Rains, T. C., "Determination of Trace Elements in Fossil Fuels by AAS," 1st

Beijing Conference and Exhibition on Instrumental Analysis, Beijing,

China, November 21, 1985.

Whelan, David P., "Square-Ware Voltammetry at Microelectrodes," November 27,

1986.

Zeisler, R. , "The Role of Specimen Banking in the NOAA Status and Trends

Program," NOAA/NBS Quality Assurance Workshop, National Bureau of

Standards, Gaithersburg, MD, December 5-6, 1985. Invited .

Zeisler, R. , "Protocols for Sampling," NOAA/NBS Quality Assurance Workshop,

National Bureau of Standards, Gaithersburg, MD, December 5-6, 1985.

Invited .

Iyengar, G. V., "Biological Trace Element Research: Recent Developments,"

Department of Chemistry, University of Kentucky, Lexington, KY, December

13, 1985. Invited .

Kingston, H. M. , "Understanding the Acid Coupling in Microwave Dissolution,"

CEM Corporation, Charlotte, NC , December 14, 1985.

Fleming, R. F. , "Analytical Applications of Neutrons," Workshop on an Advanced

Steady State Neutron Facility, National Bureau of Standards, Gaithersburg,

MD, December 16, 1985.

Carpenter, B. S., "Science as a Career," Junior Science and Humanities Symposium, Georgetown University, Washington, D.C., January 9, 1986. Invited .

65
Greenberg, R. R. , "Preparation of High Quality Multielemental Standards for

Instrumental Neutron Activation Analysis," ASTM Task Group on Nuclear

Methods of Chemical Analysis (E10.05.02), New Orleans, LA, January 14,

1986. Invited .

Bowman, R. C., Jr. and Downing, R. G. , "Boron Implantation Behavior Through

Si02 Film on Hg0

. 7 Cd0

. 3 Te , " American Physical Society, Atlanta, GA,

January 27, 1986.

Kingston, H. M. , "Laboratory Robotics," Society for Applied Spectroscopy,

Gaithersburg, MD, January 28, 1985.

Barnes, I. L. , "The Atomic Weights of the Elements - 1985. An Analysis of

Uncertainties," Inorganic Analytical Research Division Seminar, February

11, 1986.

Fleming, R. F. , "Analytical Applications of Neutrons," Seminar, Department of

Chemistry, Indiana University of Pennsylvania, Indiana, PA, February 17,

1986.

Iyengar, G. V. , "Trace Element Analytical Chemistry in Medicine and Biology,"

India Institute of Science, Bangalore, India, February 21, 1986. Invited .

Kingston, H. M. , "The Certification of Vanadium in Human Serum at the ppb Level

using IDMS , " Indiana university of Pennsylvania," Indiana, PA, February

21, 1986.

Iyengar, G. V., "Trace Elements in Relation to Public Health Problems," Bhabha

Atomic Research Center, Bombay, India, February 27, 1986. Invited .

Marinenko, G., "Potential Reference Methods for Free Alkali and Alkaline EarthIons," AACC Ionized Calcium Symposium, Galveston, TX, February 27, 1986.

Invited .

Iyengar G. V. , "Multielement Analyses of Biological and Dietary Reference

Materials: An Update of the Current Status," Central Department for

Chemical Analyses, Nuclear Research Center, Julich, FRG, March 3, 1986.

Invited .

Fassett, J. D., "Analytical Systems -RIMS , " NBS Staff Research Seminar, March 4,

1986.

Paulsen, P. J., "Application of »ICP-MS to Isotope Dilution Analysis of Standard

Reference Materials," ICP-MS Symposium, Pittsburgh Conference, Atlantic

City, NJ , March 10, 1986. Invited .

Riley, J. E. and Downing, R. G., "Quantitative Depth Profiling of Boron in

Glass with Neutrons," Pittsburgh Conference, Atlantic City, NJ , March 13,

1986.

Fleming, R. F. , "Analytical Applications of Neutrons," Seminar Department of

Nuclear Engineering, University of Michigan, Ann Arbor, MI, March 14,

1986.

66
Marinenko, G., "Development of Methods for Sodium Ion Activity Measurements in

Biological Fluids," National Meeting of the National Committee for

Clinical Laboratory Standards, Baltimore, MD, March 20, 1986. Invited .

Downing, R. G., "Neutron Depth profiling of Technologically Important Materials," State University of New York, Buffalo, NY, March 21, 1986.

Invited .

Epstein, M. S., Velapoldi, R. A., Blackburn, D. A., and Picciole, G. L. , "Evaluation of Uranyl-doped Glass Microspheres as Standards for Fluorescence Immunoassay," 86th Annual Meeting of the American Society for

Microbiology, Washington D. C., March 26, 1986.

Kingston, H. M. , "The Use of Microwave Energy in Acid Decomposition of Samples

for Trace Elemental Analysis," SOHIO, Cleveland, OH, March 26, 1986.

Iyengar, G. V. , "Accurate Measurements of Trace Elements in Biological

Tissues," Rutgers University, Department of Chemistry, New Brunswick,

April 1, 1986. Invited .

Koch, W. F. and Liggett, W. S., "Critical Assessment of Detection Limits for

Ion Chromatography," ACS National Meeting, New York, NY, April 15, 1986.

Invited .

Rains, T. C., "State of the Art of Atomic Absorption Spectrometry," 5th NBSADBASE Analytical Chemistry Workshop, National Bureau of Standards,

Gaithersburg, MD, April 15, 1986.

Iyengar, G. V. , Tanner, J. T. , Wolf, W. R. , and Zeisler, R. , "Preparation and

Characterization of Mixed Diet Composite USDIET-I: Determination of

Energy, Phytic Acid and Elemental Concentrations," Working Paper presented

at the IAEA Research Coordination Meeting on Coordinated Research

Programme on Human Daily Dietary Intakes of Nutritionally Important Trace

Elements, Vienna, April 15-18, 1986.

Zeisler, R. , "Incorporation of the Total Diet Concept in the U.S. Biomonitoring

Specimen Bank," IAEA Research Coordination Meeting, Vienna, Austria, April

15-18, 1986. Invited .

Epstein, M. S., "Comparison of Detection Limits in Spectroscopic Methods of

Analysis," 191st National Meeting of the American Chemical Society, New

York, NY, April 16, 1986. Invited .

Gramlich, J. W. , "Inorganic Mass Spectrometry Applications," The 1986 NBS

Analytical Chemistry/Materials Science Workshop, Nat. Bur. Stds.,

Gaithersburg, MD, April 17, 1986. Invited .

Kelly, W. R. , "Chemical Separations," 5th NBS-ADBASE Analytical Chemistry

Workshop, National Bureau of Standards, Gaithersburg, MD, April 17, 1986.

Invited .

Barnes, I. L. , "Inorganic Mass Spectrometry," The 1986 NBS Analytical Chemistry

/Materials Science Workshop, Nat. Bur. Stands., Gaithersburg, Md., April

17, 1986. Invited .

67
Zeisler, R. and Iyengar, G. V. , "Specimen Banking of Foods for Biomonitoring of

Inorganic Constituents," International Workshop Trace Element Analytical

Chemistry in Medicine and Biology, Neuherberg, F. R. Germany, April 21-23,

1986.

Rains, T. C., "Preparation of Environmental Samples for Trace Metal Analysis,"

EPA/Kansas City Section of SAS , Kansas City, MO, April 24, 1986, Keynote

Address .

Zeisler, R. , Iyengar, G. V. , Tanner, J. T. , Wolf, W. R. , "Preparation and

Analysis of Nutritional Materials for Quality Assurance," Second International Symposium on Biological Reference Materials, Neuherberg, F. R. Germany, April 24-25, 1986. Invited .

Lucatorto, T. B., Travis, J. C. , Fassett, J. D., and Clark, C. W. , "High

Resolution Laser Techniques in Resonance Ionization Mass Spectrometry,"

Department of Energy Contractors Workshop on Advanced Laser Techniques for

Chemical Measurements, Seattle, WA, April 29, 1986. Invited .

Wen, J., Johnson, B. C., Travis, J. C. , Fassett, J. D. , Bonanno , R. E., and

Lucatorto, T. B. , "Determination of the 2s2 -6s 1 S

9 Be- 1

OBe Isotope Shift

via Resonance Ionization Mass Spectrometry," American Physical Society,

Washington D. C., April 29, 1986.

Kelly, W. R. , "Detection of COMOS-1402 in the Stratosphere," Chalk River

Nuclear Laboratories, Atomic Energy of Canada Limited, Chalk River,

Ontario, Canada, May 8, 1986. Invited .

Carpenter, B. S., "Nuclear Chemistry and its Applications," Seneca Valley High

School, Germantown, MD, May 15, 1986. Invited .

Iyengar, G. V., "Trace Metals in the Diet and in Biological Specimens,"

National Institutes of Health, National Cancer Institute, Bethesda, MD

May 16, 1986. Invited .

Epstein, M. S., Diamondstone , B. I., Hilpert, L. R. , Miller, M. M. , Chesler, S. N. , and Gills, T. E. , "Progress in the Development of a New River Sediment

Reference Material, Symposium on Chemical and Biological Characterization

of Municipal Sludges, Sediments, Dredge Spoils and Drilling Muds,"

Cincinnati, OH, May 20, 1986.

Epstein, M. S., "The Certification and Use of Standard Reference Materials from

an Analyst's Viewpoint," Cincinnati, OH, May 20, 1986*. Invited .

Walker, R. J., Fassett, J. D., and Shirey, S. B., "The Use of Resonance

Ionization Mass Spectrometry for Examining the Re-Os Isotopic Systematics

of Archean Komatities," Geological Society of America Ann. Conf.,

Baltimore, MD, May 22, 1986.

Iyengar, G. V. , "Selenium and Zinc in Human Serum from Different Global

Regions," Second NBS/NCI Micronutrient Analysis Workshop, Gaithersburg,

MD, May 28, 1986. Invited .

Greenberg, R. R. , "Determination of Zinc and Selenium in Human Blood-Serum by

Neutron Activation Analysis," Second NBS/NCI Micronutrient Analysis QA

Workshop, Gaithersburg, MD , May 28, 1986. Invited .

68
Turk, G. C., "New Developments in Laser Enhanced Ionization Spectroscopy,"

Department of Physics Colloquium, Chalmers University, Goteborg, Sweden,

May 29, 1986. Invited .

Zeisler, R. , "Recent Developments in Analytical Methodology Related to the U.S.

Specimen Bank Program," Colloquium, Institute for Applied Physical

Chemistry, Nuclear Research (KFA) , Julich, F. R. Germany, June 2, 1986.

Invited .

Lindstrom, R. M. , "Cold-Neutron Prompt-Gamma Activation Analysis at ELLA:

Recent Measurements," Institute for Applied Physical Chemistry,

Kernforschungsanlage Julich, Germany, June 2, 1986.

Wen, J., Johnson, B. C., Travis, J. C., Lucatorto, T. B., and Clark, C. W. , "Measurement of 9 Be - 10 Be Isotope Shifts by Doppler- free Resonance

Ionization Mass Spectrometry," Gordon Research Conference on Multiphoton

Processes (Poster Session), New London, NH, June 9, 1986.

Johnson, B. C., Wen, J., Travis, J. C. , Fassett, J. D. , Bonanno , R. E. , and

Lucatorto, T. B., "Determination of the 2s2 lS-6s 1 S

9 Be- 10 Be Isotope Shift

via Resonance Ionization Mass Spectrometry," 17th Annual Meeting of the

Division of Electron and Atomic Physics, American Physical Society,

Eugene, OR, June 18, 1986.

Zeisler, R. , "Multielement Studies on Total Diets and Human Materials Including

Analytical Quality Control," Seminar on Multielement Studies, Nuclear

Research Center (KFA), Julich, F. R. Germany, June 19, 1986. Invited.

Greenberg, R. R. , "Multielement Neutron Activation Analysis - A Valuable Tool

for Environmental Studies," Seminar on Multielemental Studies, KFA,

Julich, FRG, June 19, 1986. Invited .

Lindstrom, R. M. , "Determination of Enyironmental 1-127 and 1-129 by Neutron

Activation," Department of Radioecology, Swedish University of

Agricultural Sciences, Uppsala, Sweden, June 19, 1986.

Kelly, W. R. , "Determination of Picogram Quantities of Uranium by Thermal

Ionization Mass Spectrometry," ASTM Seminar: Alpha Particles and

Semiconductors, National Bureau of Standards, June 19, 1986.

Downing, R. G. , "Analysis of Optical Signal Processing Materials by Neutron

Depth Profiling," International Meeting on Nuclear Analytical Methods,

Orleans, France, June 20, 1986.

Stone, S. F. , Hancock, D., and Zeisler, R. , "Characterization of Biological

Macromolecules by Electrophoresis and Neutron Activation," Modern Trends

in Activation Analysis, Copenhagen, Denmark, June 23, 1986.

Downing, R. G., Maki , J. T., and Fleming, R. F. , "Analytical Applications of

Neutron Depth Profiling," 1986 Modern Trends in Activation Analysis,

Copenhagen, Denmark, June 23, 1986.

Zeisler, R. and Young, I., "The Determination of Chromium-50 in Human Blood and

Its Utilization for Blood Volume Measurements," 7th International Conference Modern Trends in Activation Analysis, Copenhagen, Denmark, June 23-

27, 1986.

69
Iyengar, G. V., "Sample Validity in Biological Trace Element Research Studies,"

Modern Trends in Activation Analysis, Copenhagen, June 23-27, 1986.

Invited .

Barnes, I. L. , "Inorganic Mass Spectrometry," Center for Analytical Chemistry

Summer Seminar, Nat. Bur. Stands., Gaithersburg, MD, June 23, 1986.

Invited .

Watters, R. L. , Jr., Epstein, M. S., Rains, T. C., and Comeford, J. J., "Realtime Analysis of Metal Aerosols," 1986 Chemical Research and Development

Conference, Department of the Army, Edgewood, MD, June 24, 1986. Invited .

Lindstrom, R. M. , "Activation Analysis Opportunities using Cold Neutron Beams,"

7th International Conference on Modern Trends in Activation Analysis

Conference, Copenhagen, June 25, 1986.

Stroube, W. B. and Lutz, G. J., "Analysis of Foods for Iodine by Epithermal

Neutron Activation Analysis," 7th Modern Trends in Activation Analysis

Conference, Copenhagen, June 25, 1986.

Becker, D. A., "Primary Standards in Activation Analysis," 7th International

Conference on Modern Trends in Activation Analysis, Copenhagen, June 26,

1986.

Fleming, R. F. and Lindstrom, R. M. , "Precise Determination of Aluminum by

Instrumental Neutron Activation Analysis," 7th International Conference on Modern Trends in Activation Analysis, Copenhagen, Denmark, June 26, 1986.

Greenberg, R. R. , "The Role of Neutron Activation Analysis in the Certification

of NBS Standard Reference Materials," 7th Int’l Conf. on Modern Trends in

Activation Analysis, Copenhagen, Denmark, June 27, 1986. Invited .

Iyengar, G. V., "International Studies on Dietary Intake of Trace Elements by

Human Subjects," Nuclear Research Center, Jiilich, June 30, 1986. Invited .

Greenberg, R. R. , "Elemental Characterization of the NBS Milk Powder Standard

Reference Material via Instrumental and Radiochemical Neutron Activation

Analysis," University of Pavia, Pavia, Italy, July 1, 1986. Invited .

Iyengar, G. V., "State of the Art of Trace Element Analysis Techniques and

Reference Values for Elemental Concentrations in Human Tissues and Body

Fluids," Reference Man Task Group Meeting, International Commission on Radiological Protection, Oak Ridge, Tennessee, July 9, 1986.

Iyengar, G. V., "Dietary Intakes of Minor and Trace Elements by Human Infants

and Adults: A Global View Based on Some Recent International Studies,"

Reference Man Task Group Meeting, International Commission on Radiological

Protection, Oak Ridge, Tennessee, July 10, 1986.

Koch, W. F. , "Standard Reference Materials for Acid Deposition Measurements,"

1986 Johnson Conference, Johnson, VT, July 17, 1986. Invited.

Beary, E. S., "Isotope Dilution Mass Spectrometric Assay of Copper in Copper

Ore Reference Materials," SAC 86/3rd BNASS University of Bristol,

Bristol, England, July 24, 1986.

70
Greenberg, R. R. and Fleming, R. F. , "High Accuracy Analysis of Biological

Materials by Neutron Activation Analysis," Middle Atlantic Regional

Meeting of the American Chemical Society, Baltimore, MD, September 3,

1986. Invited .

Fassett, J. D. and Walker, R. J., "Ultratrace Elemental and Isotopic Analysis

of Osmium and Rhenium Using Resonance Ionization Mass Spectrometry and

Thermal Vaporization," 3rd International Resonance Ionization Spectroscopy

Symposium, Swansea, Wales, September 9, 1986.

Travis, J. C. , Fassett, J. D., and Lucatorto, T. B., "Resonance Ionization Mass

Spectrometry," 3rd International Resonance Ionization Spectroscopy

Symposium, Swansea, Wales, September 9, 1986.

Pratt, K. W. , "High Accuracy Differential Pulse Arodic Stripping Voltammetry

Using Indium as an Internal Standard," ACS National Meeting, Anaheim, CA,

September 11, 1986.

Mavrodineanu, R. , "Chemical Calibration Standards for Molecular Absorption in

Spectrometry," Conference on Advances in Standards and Methodology in UVVisible-NIR Spectrometry, Oxford, England, September 16, 1986. Invited .

Watters, R. L. , Jr., "ICP Calibration over Wide Concentration Ranges," FACSS

13, St. Louis, MO, September 29, 1986. Invited .

Walker, R. J., and Fassett, J. D., "Ultratrace Elemental and Isotopic Analysis

of Osmium and Rhenium Using Resonance Ionization Mass Spectrometry (RIMS)

and Thermal Vaporization," 13th Annual Meeting of the Federation of

Analytical Chemistry and Spectroscopy Societies, St. Louis, MO, September

29, 1986.

Epler, K. , Epstein, M. S., Koch, W. F. , O'Haver, T. C., "Improving the Accuracy

and Sensitivity of Atomic Spectroscopic Methods Using Ion Chromatography,"

13th Annual Meeting of the Federation of Analytical Chemistry and Spectroscopy Societies, St. Louis, MO, September 30, 1986.

Watters, R. L. , Jr., Epstein, M. S., Harnly, J. M. , and Miller-Ihli, N. , "Realtime Analysis of Ambient Aerosols," FACSS 13, St. Louis, MO, October 3,

1987.

3 . Committee Assignments

I. Lynus Barnes

Member, Department of Health and Human Resources, Chemistry

Task Force of the National Shellfish Sanitation Program

Washington Editorial Review Board

International Union of Pure and Applied Chemistry

Commission on Atomic Weights and Isotopic Abundances

Chairman, IUPAC Sub-commission on Isotopic Abundance Measurements

71
Donald A. Becker

Member, ASTM E-10, Nuclear Technology and Applications

ASTM E-10. 05, Nuclear Radiation Metrology

ASTM E-10. 05. 02, Radionuclide Metrology

ASTM E-10. 05. 08, Nuclear Environmental Metrology

ASTM E-10. 05. 10, Neutron Metrology

ASTM D-19, Water

ASTM D-19. 01, Statistical Methods

ASTM D-19. 02, General Specification and Technical Resources

ASTM D-19. 03, Sampling of Water and Water-Formed Deposits, and

Surveillance of Water

ASTM D-19. 04, Methods of Radiochemical Analysis

ASTM D-19. 05, Inorganic constituents in Water

ASTM D-19. 07, Sediments

ASTM D-19. 33, Water Associated with Synthetic Fuel

Production

Chairman, ASTM E-10. 05. 12, Task Group on Nuclear Methods of Chemical

Analysis

Member, ANS , Trace Element Analysis Committee, Technical Group on Biology

and Medicine

ANS, Activation Analysis Committee, Isotopes and Radiation Division

M. James Blackman

Smithsonian Institution:

Materials Analysis Academic Program Committee

SARCAR Advisory Committee

Extramural Committees:

ASTM E-10, 05. 12, Task Group on Nuclear Methods of Chemical Analysis

Stephen B. Carpenter

Member, Institute of Nuclear Materials Management, Standards Committee

N15.9.3, Non-destructive Assay (Physical Methods)

Technical Consultant, U.S. House of Representatives, Committee on Science

and Technology, Science Policy Task Force

Commissioner and Member of the Board of Directors, Commission on Professionals in Science and Technology

Member, American Nuclear Society, International Committee and the Isotopes

and Radiation Division, Nuclear and Atomic Analysis Technical

Committee

Finance and Housing Chairman and member of Technical Committee,

International Conference on Methods and Applications of Radioanalytical

Chemistry, Kona, Hawaii, April 5-10, 1987.

Council, Joint Board on Science and Engineering Education

Member, National Bureau of Standards, Radiation Safety Review Subcommittee

Robert G. Downing

Member, ASTM E-10, Nuclear Methods for Chemical Analysis

Member, Inorganic Analytical Research Division Seminar Committee

Chairman, Inorganic Analytical Research Division Safety Committee

Michael S. Epstein

Member, ASTM D-19, Water

Treasurer, Society for Applied Spectroscopy

72
Ronald F. Fleming

Member, ASTM E-10.05, Nuclear Radiation Metrology

ASTM E-10.07, Radiation Effects on Materials

Member, NSERC Visiting Committee on the McMaster Nuclear Reactor

John W. Gramlich

Member, Institute of Nuclear Materials Management, Committee N15.9.3,

Non- Destructive Assay (Physical Methods)

Member, International Union of Pure and Applied Chemistry, Commission on Atomic Weights and Isotopic Abundances

Robert R. Greenberg

Member, ASTM E-10.05, Nuclear Radiation Metrology

Member, NBS Chemistry Storeroom Committee

Member, ANS , Trace Analysis Committee, Technical Group for Biology and

Medicine

Govindaraja V. Iyengar

International Commission on Radiological Protection, Task Group on Reference Man

International Union of Pure and Applied Chemistry, Subcommittee on Selenium

International Scientific Committee of the Modern Trends in Activation

Analysis

Vice-President, International Union of Elementologists (India)

Member, Editorial Board, the Science of the Total Environment (U.K.)

Advisor, Food Laboratory Newsletter (Sweden)

Howard M. Kingston

Member, ASTM C-26.05, Methods of Test

ASTM C-26.07, Waste Materials

Session Chairman and Eastern Analytical Symposium

Technical Consultant, Congressional Science and Technology

Committee

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, ASTM D-22. 03, Task Group on pH

ASTM D-22. 06, Atmospheric Deposition

Personnel Officer, NBS Child Care Association, Board of Directors

Member, National Committee for Clinical Laboratory Standards

John K. Langland

Chairman, NBS Electronics Storeroom Committee

Richard M. Linds trom

Alternate Member, NBS Reactor Safety Evaluation Committee

73
George Marinenko

Member, ASTM D-19, Water

Chairman, D- 19 . 05 . 04 . 03 , Voltammetry

D-19. 09. 06, Redox Potentials in Saline Water

D-19. 09. 07, pH in Saline Water and Brines

D-19. 09. 01, Chlorine Residuals in Saline Water

Chairman, National Capital Section of the Electrochemical Society

John A. Norris

1st Vice Chairman ASTM E-02, Emission Spectroscopy

ASTM E-02. 01, Fundamental Practices

ASTM E-02. 02, Statistics

ASTM E-02. 04, Sampling and Standards

ASTM E-02. 05, Copper, Cobalt, Nickel, and High Temperature

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. 13, Terminology

Consultant-Chemists Committee -American Iron and Steel Institute

Kenneth W. Pratt

Secretary/Treasurer , National Capital Section of the Electrochemical

Society

Member, NBS Inorganic Analytical Research Division Safety Committee

Member, Inorganic Analytical Research Division Seminar Committee

Member, Research Information Subject Specialist

Theodore C; Rains

Member, Proposal Evaluation Committee for National Science Foundation

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-19, Water

NIH Proposal Evaluation Committee for Instrumentation

Post -Chairman, FACSS Governing Board

Professor- in-Charge , ACS Short Course on Atomic Absorption and Plasma

Emission Spectroscopy

Task Force Leader, Scientific Instrumentation Information Network and

Curricula (SIINC) for Project on "Atomic Absorption Spectroscopy"

Column Editor, Journal of Applied Spectroscopy

74
Thomas W. Vetter

Member, ASTM E-02, Emission Spectroscopy

ASTM E-02. 02, Statistics

ASTM E-02. 04, Sampling and Standards

ASTM E-02. 06, Lead, Tin, Zinc

ASTM E-02. 07, Aluminum

ASTM E-02. 09, Ferrous

ASTM E-03, Chemical Analysis of Metals

ASTM E-03. 01, Ferrous

ASTM E-03. 91, Editorial

ASTM E-03. 92, Standards

Chairman ASTM E-03. 01, Task Group on Low Concentration of Sulfur in Cast

Iron, Combustion Method

Yung -Chi Wu

Member, ASTM D-19, Water

Member, NBS/NML Minority Advisory Panel

Rolf L. Zeisler

Member, NBSR Safety Evaluation Committee

Chairman, Trace Element Analysis Committee, Technical Group for Biology

and Medicine, American Nuclear Society

75
III. Organic Analytical Research Division

Willie E. May, Chief

Michael J. Welch, Deputy Chief

A. Division Overview

The Organic Analytical Research Division conducts research to develop and

improve techniques for the preparation, purification, and analysis of organic

compounds and employs these techniques in the solution of problems related to

national needs. The Division's research is carried out in five groups that are organized along the following functional lines: Bioanalytical Techniques,

Electrochemistry, Gas Chromatography, Liquid Chromatography, and Mass Spectrometry. Current activities in each of the groups will be discussed in the Group

Overviews and Technical Reports that follow. The Division responds to the

measurement and standards needs of industry, other government agencies,

(Federal, state, and local) public and private institutions and associations,

and other research organizations at the National Bureau of Standards. Research

efforts in the Division during the past year have resulted in the publication

of 25 articles in archival journals and other technical media. An additional

22 articles are currently in press. Division scientists also presented 38

talks at technical meetings and conferences during FY86

During the past year, approximately 45 percent of our efforts were directed toward basic research in organic analytical chemistry. The remainder

of our efforts were in support of other Federal Agency programs and to a limited degree in short-term projects performed on a service analysis basis.

The Division is actively involved in four Competence Building Programs that

have been selected for funding by the NBS Director. Three of these programs,

Organic Electrochemistry, Analysis of Ionization Mechanisms and Ion Structures

in Organic Mass Spectrometry, and the Use of Proteins in Analytical Chemistry

have been on-going for several years. Accomplishments in all of these areas will be discussed in the Group Overviews and Technical Reports. During the

past year, some very exciting research has begun on the development of Bioanalytical Sensors. The objective of this new Competence Building Program is to

combine the selectivity inherent in immunological recognition with chemistrybased procedures for signal amplification to provide highly specific and ultrasensitive chemical sensors. Additional details concerning this research are found in the Bioanalytical Techniques and Electrochemistry Group overviews and

Technical Report 6. Research on liquid chromatographic retention mechanisms

and high field NMR have also continued with base support.

As in the past few years, the major portion of our other agency support

has come from the National Cancer Institute (NCI) and the Environmental

Protection Agency (EPA) , with substantial support also being provided by the

Department of Energy (DoE) , Department of Defense (DoD) , Department of Agriculture (USDA) , and the National Oceanic and Atmospheric Administration (NOAA)

Specific research efforts in support of these other Federal agency programs

included: serving as Reference Laboratory and Analytical Quality Assurance

Center for a network of NCI supported laboratories investigating the efficacy

of selected vitamins and other organic micronutrients as cancer chemopreventive

agents; continuing to develop reference materials and providing analyses of EPA

audit and quality control samples as part of the process for establishing NBS

traceability; developing analytical procedures for the determination of polar

PAH derivatives and providing reference compounds and characterized complex

mixtures for DoE laboratories involved in the investigation of health effects

76
associated with exposure to complex environmental 'mixtures; continuing the

development of an isotope dilution gas chromatography/mass spectrometry method

for determining human exposure to chemical warfare agent BZ for the DoD;

collaborating with the Center for Radiation Research in the development of an analytical method for performing post- irradiation dosimetry on meats for the

USDA; and providing methods development and specimen banking support for the

EPA and for NOAA's National Status and Trends monitoring program. Information

concerning these activities are provided in the Group Overviews and Technical

Reports

Several short-term projects were also undertaken on a service analysis

basis in support of several NBS and other Federal Agency programs. A few

examples follow that indicate the wide variety of measurement problems that we are asked to address with rapid turnaround: a method for analysis of fugitive

emissions from a paper shredder-burner device was developed for the Navy and

utilized on several samples; an apparatus was constructed, a method developed

and several samples analyzed to determine methylene bromide leakage from

batteries in artillery proximity fuses in a DoD supported project for Harry

Diamond Laboratories; several metal surfaces were analyzed for the Naval

Research Laboratory to determine if hydrocarbon films were present that might

explain the loss of paint adhesion on the surfaces; and the identity of a tear

gas neutralizer was determined using fast ion bombardment mass spectrometry and

high field NMR. In addition, PCB levels were determined in transformer fluids

of transformers taken from the White House.

The collaborative research efforts that were begun several years ago with

the other two Divisions in the Center for Analytical Chemistry have continued.

The research effort with the Gas and Particulate Science Division for development of an isotope dilution GC/MS method for verifying the concentrations of

volatile toxic organics in air SRM cylinders is nearly completed and is

described in Technical Report 20. Laser ionization mass spectrometric and

Raman spectroscopic measurements are continuing to be performed to assist in

determining structures of chromatographic supports for biomolecule affinity

chromatography. Our efforts with the Inorganic Analytical Research Division

involving neutron activation analysis of two-dimensional electrophoretic slab

gels to study protein-metal binding interactions are still on-going and we have

provided our expertise in HPLC in the development of methods for the determination of metallo-organic chelates in water. Collaborative research efforts are also on-going with several other technical Centers within NBS. Details

concerning our collaborative efforts with the Centers for Chemical Physics,

Fire Research, Radiation Research, and the Institute for Materials Science and

Engineering are found in the Group Overviews and Technical Reports

•We have continued our active support of the NBS Standard Reference

Materials Program. SRM related activities represented approximately 10% of our budget. Measurements for the certification of eleven SRMs have been completed

during FY86 and measurements are currently in progress on an additional five

materials. Analyses were performed to monitor the stability of an additional

six SRMs. Details concerning many of these activities will follow in various

Group Overviews. The development of SRMs for drugs of abuse in urine, marine

sediment (with certified values for PAH, chlorinated pesticides and PCBs), fatsoluble vitamins in human serum, and molecular weight markers for

electrophoresis are among the dozen projects that we will undertake in FY87.

Development and certification of the marine sediment SRM will be funded by NOAA

and development of fat-soluble vitamins in serum material will be supported by

77
NCI. All other SRM related activities will be supported solely by the NBS

Office of Standard Reference Materials.

Research efforts in the Division have been bolstered by the contributions

of approximately 20 research associate and guest workers during the past year.

Research efforts in our Gas Chromatography, Electrochemistry, and Bioanalytical

Techniques Groups were strengthened by NRC Postdoctoral Research Associates,

Howard Mayfield, Damian Shea, and Michael Ambrose, respectively. Dr. Polly

Ellerbe, a Research Associate supported by the College of American Pathologists, continues to make significant contributions in our Definitive Methods

in Clinical Chemistry Program. Three foreign Visiting Scientists, Dr. Emil

Schonberger (National Physical Laboratory of Israel), Dr. S. D. Yang (Chinese

Academy of Medical Science in Beijing), and Professor Zeng-nan Zhou (East China

Institute of Textile Science in Shanghai) have made major contributions in

several Other Agency measurement programs. Dr. P. V. Sundaram (Max Planck

Institute in Berlin) has provided us with guidance in the area of enzyme

immobilization and stabilization. Professor Barry K. Lavine (Clarkson University) is utilizing his expertise in multivariant analysis to assist scientists

in our Bioanalytical Techniques and Liquid Chromatography Groups. The addition

of Dr. Anne L. Plant, a biochemist assigned to our Bioanalytical Techniques

Group, and Laurie L. Brown, a biomedical engineer working in our Electrochemistry Group, to our full-time staff has provided additional strength, enthusiasm

and a number of innovative ideas in our Bioanalytical Sensors research program.

In FY87 we will continue to direct a substantial portion of our efforts in

each of the Division's five groups towards basic research. Details concerning

these activities are found in the three-year research plans found in the

individual Group Overviews. We will also continue to advocate the utilization

of our measurement expertise, gained in part from these basic studies, along

with our quality assurance experience and background to fulfill Reference

Laboratory functions in long-term national monitoring programs. We are currently fulfilling such a function for the NCI Cancer Chemoprevention

Program, the DoE Health Effects from Exposure to Complex Mixtures Project, and

the NOAA National Status and Trends Program. During the coming year, we anticipate commencing a Reference Laboratory/Quality Assurance function for the

EPA Integrated Air Cancer Project and the EPA component of the NHANES-III

Program.

The three -year research plans that are included in the individual Group

Overviews include equipment needs necessary to completely fulfill those plans.

Our general purpose equipment allocation for FY87 will be utilized to purchase

a triple quadrupole mass spectrometer and a capillary supercritical fluid

chromatograph. Other vital pieces of equipment will be acquired with Other

Agency support. Our foremost personnel need is for a protein chemist to help

support our biotechnology program. Other pressing needs are for a separations

chemist with experience in nutritional measurements to support our NCI efforts

and a mass spectrometrist to assist in the development of drugs of abuse in

urine SRMs

1 . Bioanalytical Techniques Group: Overview

The activities of the Bioanalytical Techniques Group are primarily

directed towards (1) developing means for separating and characterizing

proteins, peptides, and other bioraolecules for standards needs in

biotechnology, (2) synthesizing organic compounds labeled with stable isotopes

for high accuracy work in clinical/nutritional chemistry, (3) maintaining

78
expertise and performance of research in high- field nuclear magnetic resonance

spectroscopy, and (4) investigation of the use of immunochemical reactions to

provide selectivity for the fluorimetric detection of biomolecules

During the past year we have continued to make progress on the research

goals set forth in the Bioanalytical Competence Program. The focus of research

with proteins and peptides has been to develop ultra- sensitive methods for

protein separation, visualization, and’ identification. During the characterization phase of this work, specific applications have been attempted to

demonstrate state-of-the art capabilities for protein separations. Such work

includes studies of viral proteins, honey proteins, effects of reagents on electrophoresis, and use of new materials for chromatographic separations.

Viral protein studies have attempted to identify new proteins produced in

the membranes of cells grown in tissue culture and infected with viruses such

as the respiratory syncytial virus (RSV) . This work has been done in collaboration with the Uniformed Services University of the Health Sciences. We are currently awaiting the installation of an imaging system that will allow

matching of proteins from different two-dimensional electrophoretic gels. This

new tool should help identify subtle protein differences in infected cells that

have been collected at selected time intervals during the viral infection

phase

Studies of the proteins isolated from honey have led to the interesting

observation that the isoelectric focusing patterns have encoded in them

information which allows differentiation based on their geographical origin.

The results from this investigation are being submitted for publication in

ELECTROPHORESIS (see Technical Report 5)

Studies of protein separations are continuing with the synthesis of new

immobilized polyvinylpyrrolidone (PVP) -metal -redox matrices. The action of

immobilized PVP-copper oxidants such as periodate, persulfate or permanganate

is being tested on human serum proteins. Different oxidants may have affinity

for or react with specific groups of proteins present in the serum. Similarly,

the action of immobilized reducing agents (e.g., S03 ”, S

2 04 =

, BH4

‘

, etc.) on proteins will be examined. The synthesis of hexadecyl modified silica is being

investigated for protein immobilization.

Our studies of the effects of reagent purity on electrophoretic

separations continue to focus on sodium dodecyl sulfate (SDS) . Electrophoretic

separations of the same protein can vary depending upon the source of SDS.

Many SDS samples were analyzed for chain length, for pH in aqueous solutions,

for conductivity, and for spectral properties. In addition, HPLC analyses were

performed on solutions of the SDS samples utilizing a C 18 column with conductivity detection. Analysis for the presence of free alcohols in the SDS

samples was also achieved by quantitative derivatization. Critical micelle

concentrations of several of the SDS samples were established by a spectroscopic dye method. Currently, electrophoretic separations of selected

proteins are being performed using the different SDS samples to correlate the

analytical data.

As part of the advancement of a refined isotope-dilution mass- spectrome trie definitive method for measuring uric acid in serum (with uric

acid-1 , 3.- 1

N2 as the internal standard), optimal conditions were developed for

isolating uric acid from serum constituents using ion-exchange chromatography

and for derivatization by silylation to a stable product for analysis by

79
GC/MS . This work, done in conjunction with the Mass Spectrometry Group is

described in Technical Report 15.

Using the upgraded Bruker WM-400 NMR spectrometer, we have studied the

ring conformations of a group of fortimicin aminoglycoside antibiotics by

proton NMR spectroscopy at high field. This work is directed towards

correlating the 15 N NMR chemical shifts with chemical conformations. In 2-D

NMR spectrum- editing studies, a new Pascal compiler has been used to speed

computations by a factor of 4-5, and phase -sensitive 2-D NMR spectrum editing

has been investigated further. In work designed to characterize solid sugars

used in measurements of enthalpy of combustion, the utility of high- field

proton NMR of dimethylsulfoxide solutions for analysis of the anomeric composition of these sugars has been confirmed by parallel studies using cross

polarization- -magic angle spinning 13 C NMR to analyze the solid sugars

directly.

Eight 15 N-enriched aminodeoxy monosaccharides are being synthesized.

These sugars will be used as model compounds for 15 N NMR investigation of the

relationship between 15 N NMR spectral parameters, i.e., chemical shift and 15 N1 H coupling constants, and molecular structure. Currently, several partially

protected sugars are being prepared in conjunction with an investigation to

determine optimum reaction conditions for the synthesis.

Feasibility studies on probing the mechanism of a protein silver stain by

109 Ag NMR have been completed. Ammoniaca1 silver solutions with various water

soluble amino acids were studied to determine if it would be possible to

identify silver binding sites. The shifts observed with methionine and

histidine indicated that binding occurs but that the systems also undergo

exchange reactions. Low temperature work (-40 e C) failed to give resolution of

the broadened 109 Ag signal. It was concluded that the experimental and interpretational problems were sufficiently complex that work has been terminated.

We are continuing to work on developing capabilities for enzyme and other

protein immobilization by solid-phase binding with the newer "spacer-arm" techniques. For example, urease was immobilized on a variety of different polymeric supports by different coupling mechanisms. The retained enzyme activity

of columns packed with immobilized enzyme varies from support to support and

also varies with the coupling technique used. At present there are 8 columns

that have been studied for nearly one year. Five columns have retained between

76% to 87% of their activities. This work also has application to our recently initiated biosensor development program.

We have also been active in coordinating a national interlaboratory

comparison study to assign activity values to the enzyme aspartate aminotransferase (ASAT) in connection with our clinical chemistry standards program. A

reference material with accurately assigned activity measurements will soon be

issued.

As part of a National Cancer Institute project, and as a prelude to

development of a fat soluble vitamin calibration solution SRM, ethanolic

solutions for retinol, tocopherol, and beta-carotene have been prepared. For

the ethanolic standards, each vitamin solution will be produced with and

without the addition of butylated hydroxytoluene (BHT) . These solutions will

be stored at -25 °C, -80 °C, and liquid nitrogen temperatures. The stability of

these standards will be followed during the coming year by spectroscopic and by

HPLC analysis to facilitate the detection of possible oxidation products. We

80
have also prepared a series of serum pools which have been sent to

participating laboratories. Statistical reporting of the results is

proceeding

During the past year, a NRC/NBS Postdoctoral Research Associate (M.

Ambrose) has begun work in the synthesis of labelled sugars to correlate

chemical shifts with changes in structure. Dr. A. Plant also joined the group

to provide expertise in liposome technology as well as in immunology and

enzymology. A post-doctoral candidate is being sought to work in the area of

chemically-modified proteins and protein separations with emphasis on enzyme

immobilization and stabilization, or on protein/peptide structure and function.

A permanent staff member is being sought to develop an in-depth program in

studying protein stabilization and in studying chemical interactions between

proteins and other biomolecules, including polymers and other supports.

Spectroscopic studies including fluorescence studies of protein folding will be

included.

Future directions for the Bioanalytical Techniques Group include the

development of better techniques for protein/peptide separation and detection.

We will continue to extend our capabilities to immobilize enzymes on solid

supports and monitor enzymatic activity. We will continue our work on organic

synthesis of stable isotopes for high- accuracy clinical and nutritional

studies. Research in high-field NMR spectroscopy will be directed towards

developing optimal pulse sequences for NMR studies of peptide and other

biomolecule structures. Research on biosensor development will include

investigation of newer methods of immobilizing enzymes for specific applications in biosensor methodology and the development of immunological and

enzymatic approaches to liposome sensitization and lysis.

Dennis J. Reeder, Group Leader; Lyle A. Alexander, Michael G. Ambrose, Alex

Cohen, Bruce Coxon, Jesse J. Edwards, Alex J. Fatiadi, Joyce F. Graf, Diane K.

Hancock, Ken Keiler, Margaret C. Kline, Millard Maienthal, Kristy L. Richie,

Robert Schaffer, P. V. Sundaram, Paul Vetter.

2 . Electrochemistry Group: Overview

During the past year the electrochemistry group has focused its efforts on three principal areas of research: (1) development of methods for selective

electrochemical detection in liquid chromatography, (2) study of the chemistry

and physics of electrode surface modification with polymer- immobilized catalysts, and (3) investigation of the use of immunochemical reactions to provide

selectivity for the electrochemical determination of bio-molecules. The common

goal of this work has been to increase the sensitivity and selectivity of

voltammetric measurements. The research tools we have used to achieve this

goal include: square -wave, differential pulse, and cyclic voltammetry; chronoamperometry and chronocoulometry ; rotating ring-disk voltammetry; as well as hybrid techniques such as spectroelectrochemistry and liquid chromatography

with ultraviolet/visible absorbance (LCUV) and electrochemical (LCEC)

detection

We have continued to make progress on the research goals targeted in the

Electrochemistry Competence Building Program. Polymer-modified electrodes have

been constructed for the reduction of ethylene dibromide and the selective

concentration of anionic analytes at the electrode surface. Extending the

original research of Professor Allen Bard of the University of Texas, we have

developed a stable, polymer-modified reference electrode for use in nonaqueous

81
media. This device received one of the prestigious I-R 100 awards for 1986.

Considerable progress has been made in addressing programmatic needs in

NBS/Other Agency programs by the application of LCEC/UV to the determination of

fat-soluble vitamins in human serum, nitro-polynuclear aromatic hydrocarbons in

air and diesel particulate extracts, and phenylalanine/tyrosine radiolytic

products as part of the effort to develop an analytical method for postirradiation dosimetry on meats.

In collaboration with the Bioanalytical Techniques Group, work has begun

on the development of electrochemical and optical sensors for the trace determination of organic analytes. The goal of this project is to use the specificity of immunological recognition coupled to chemical amplification to

provide highly selective and sensitive detection. One step toward this goal

is the encapsulation of an electroactive marker in the aqueous volume trapped

in a lipid vesicle (liposome). Amplification of an immunological binding

event may then be achieved by the lysis of the liposome, releasing thousands of

marker molecules for subsequent detection. We are currently developing a flowinjection system with the immunochemical reaction taking place on the surface a packed column. The antibody is covalently bound to small glass beads and a solution of antigen- liposome/marker complex mixed with the unknown solution is

used to competitively bind to the immobilized antibody. Unbound antigenliposome/marker complex is carried downstream for non-selective detergent

lysis, providing a chemically amplified signal proportional to the unknown

antigen concentration. A voltammetric or fluorometric flow-cell detector

completes the measurement process. The entire flow- inj action system is under

computer control, with separate solution and timing sequences for ' the entire

process: generation/regeneration of the reactor column, competitive binding of

the analyte/liposome solution, lysis of the unbound liposomes, and detection of

the released markers.

One important accomplishment, which is both an outgrowth of the effort in

chemically modified electrodes and in the development of biosensors, has been

the development of an electrode that selectively preconcentrates anionic marker

compounds for subsequent square -wave voltammetric detection. The electrode is

based on an oxidized platinum surface derivatized with a trichlorosilylethylpyridine reagent. The covalently-bound pyridine group is easily quaternized

with methyl iodide. This creates an anion exchange polymer at the surface of

the platinum. The electrode may be used to preconcentrate the ferrocyanide

marker released by lysis of liposomes either in the heterogenous flow reactor

system or in a homogeneous assay. The advantages of the new electrode are that

the electrochemical current measured at the modified surface is about two

orders of magnitude larger than at the bare platinum, and the modified electrode dees not exhibit the fouling problems observed at bare electrodes in the

presence of serum samples.

In addition to the development of polymer materials for the modification

of electrodes, we have also made progress in the mathematical description of

the response obtained at these electrodes. For the common situation, where the

rate of charge transport through the film on the electrode is slow, we have

developed a model with finite-element digital simulation of the various charge

transport rate -limiting parameters. As an experimental model system, we have

studied the electrochemistry of ferrocene in polyethylene oxide electrolyte.

This solid/viscous liquid reveals - in extreme - the effects of uncompensated

resistance and slow diffusion of the analyte. From the results of cyclic

voltammetry as a function of temperature, an activation energy for diffusion

was calculated to be 5 kcal/mol. From the diffusion-controlled portion of a

82
chronoamperometric measurements, the diffusion coefficients could be calculated

at various temperatures. Again, an activation energy of 5 kcal/mol was found.

This experimental system has provided many new insights into the behavior of

polymer-modified electrodes.

An important aspect of the Group's efforts using LCEC/UV has been in the

support of two Other Agency projects, the determination of retinol, tocopherol,

and carotene in serum as part of our Reference Laboratory function for the

National Cancer Institute (NCI) Cancer Chemoprevention Program and the measurement of radiolytic products of phenylalanine and tyrosine, as part of a study

for the United States Department of Agriculture (USDA) , aimed at developing

methods for post- irradiation dosimetry in meats. State-of-the-art chromatographic separations as well as selective detection methods have been developed

and utilized to support these projects. In addition, a new approach for the

determination of 1-nitropyrene in diesel particulate extracts has been developed, using a solid-phase extraction column to fractionate the sample before

determination by reductive, amperometric LCEC.

During the past year we have been assisted by the efforts of several

temporary staff members. A NRC/NBS Postdoctoral Research Associate (D. Shea)

has begun work on the determination of organic and inorganic sulfur compounds

in marine sediments using LCEC. During part of the summer of '86 a general

physical scientist (S. Ehlers) assisted in this work. From 3/85 to 6/86, we benefited from the assistance of a guest scientist from the National Physical

Laboratory of Israel (E. Schonberger) , who supported our efforts in the LCEC of

vitamins in serum. During the past year, we have also benefited from the work

of a guest scientist from the Chinese Academy of Medical Sciences in Beijing

(S. D. Yang), who has contributed to the effort in the LCEC of radiolytic

products and the determination of nitro-PAH. We have increased our efforts in

the area of the development of biosensors by the recruitment of a biomedical

engineer (L. Brown) and a biochemist (A. Plant, who is assigned to the

Bioanalytical Techniques Group)

During the past year we acquired a UV/visible spectrophotometer, a phase

resolved fluorescence spectrometer, and three computers (2 IBM PC -AT for mathematical modeling and an Apple lie for the control of the flow injection system)

for use in our biosensors program. To support the vitamins in serum work, a wavelength programmable LC absorbance detector and an autosampler were

purchased.

In the coming year, in addition to continuing or completing our current

projects, several new areas of work will begin. In the area of LCEC, a new

project on the determination of organotin compounds in marine sediments will

begin. This work will "dovetail" nicely with both the OSRM goal of developing

a natural marine sediment SRM and our current research on organothiols in

sediments. Also, we would like to begin research on ultra-micro and array

electrodes for use in both liquid and supercritical fluid chromatography.

In the research on charge transport in polyethylene oxide, we would like

to extend our models to the cyclic voltammetric response of these systems.

Goals in the modification of electrode surfaces include: controlled synthesis

of polymer layers to thicknesses of only hundreds of angstroms, which should

allow faster permeation of the analyte and not exhibit the large, uncompensated

resistance problems of the thicker films studied to date; research silane

reagents that may be used with copolymers for coupling to the surface of the

electrode

83
Future directions for the biosensors project include the design and

development of practical devices and systems for the detection of hormones,

drugs, and vitamins in urine and blood.

William A. MacCrehan, Acting Group Leader; Elmo A. Blubaugh, Laurie L. Brown,

Sharon Ehlers , Rosanne M. Kannuck, Emil Schonberger, Damian Shea, Shu De Yang,

and William T. Yap.

3 . Gas Chromatography Group: Overview

The Gas Chromatography Group conducts research in the areas of high

resolution gas chromatography, advanced sample preparation techniques and

computer automation to allow the development of new techniques and maintain

state-of-the-art measurement capabilities, which are used to certify complex

Standard Reference Materials (SRMs) , address the measurement needs of Other

Agencies and disseminate technical information.

The Laboratory Information Management System (LIMS) , which was initially

structured in FY85, continues to grow in size and utility. Additional software

was developed allowing users more latitude in data manipulation. In particular, a program was written allowing manual integration and digital smoothing

under cursor control. This program allows us to make corrections to peaks

improperly integrated by software -driven data acquisition computers. Additional software allows the transfer and manipulation of both graphical and

numeric data between any of the computers within or remotely connected to the

LIMS system.

Our efforts in supercritical fluid capillary chromatography (SFCC) have

not proceeded for lack of adequate instrumentation. However, during the past

year a modest effort has resulted in the construction of a supercritical C02 extraction apparatus for rapid and efficient removal of trace organic species

from solid samples. This apparatus has been shown to be able to extract PAHs

from SRM 1649 (Urban Particulate Matter) and PGBs from sediment in less than 1 hour with efficiencies equal to a 16 -hour Soxhlet extraction. This work has

also resulted in an archival publication.

The program on the theoretical optimization of the multidimensional gas

chromatographic experiment has been successfully concluded and a second manu- script has been prepared for publication. Our postdoctoral appointee, Howard

T. Mayfield, upon the completion of 18 months at NBS has left to accept a position with the Department of Defense. Additional work needs to be done to

apply the theoretical models of the sequentially coupled column experiment to

complex separations.

A gas chromatograph with a mass selective detector (MSD) has been acquired

and installed. This instrument gives the Group the ability to make extremely

selective analyses at the 10-100 pg/g level. It also allows us to utilize the

isotope dilution method of internal standardization. If desired, this detector

can also yield mass spectral data for qualitative analysis. To date, the MSD

has been used for the quantitation of minor PAH constituents in air particulate

samples, the certification of pesticides and PCBs in SRM 1588 (Cod Liver Oil),

the isotope dilution measurements of ng/g levels of volatile organics in CRM

cylinders, and the qualitative analysis of the constituents in the exhaust of a document shredder -burner . Software has been written to allow information from

the MSD data system to be transferred to the LIMS system.

84
As in past years, the Group has directed a great deal of its efforts to

the solution of Other Agency measurement problems . Under a new agreement with

the National Oceanographic and Atmospheric Administration (NOAA) we have

developed written sample collection and analytical procedures for the determination of PAH, pesticides and PCBs in marine sediment and bivalves. We have

also analyzed a number of sediment and tissue samples as part of a "Specimen

Banking" component of our Reference Laboratory function of NOAA's Mussel Watch

and Benthic Surveillance Program. In our efforts to produce a marine sediment

SRM, we are developing a tributyl tin analysis protocol. Thirty new humanliver samples, from the NBS/EPA Environmental Specimen Bank, were analyzed for

pesticides and PCB congeners using a recently modified, sample preparation

procedure (see Technical Report 22) . Three sets of Quality Assurance Materials

from EPA/Cincinnati were analyzed and .NBS traceability established. Three PCBs on Terrestrial Sediment materials have been homogenized and analyzed, also for

EPA/Cincinnati, to be used in their Quality Assurance Program. The Group also

prepared and analyzed three alcohol in iso-octane quality assurance materials

for EPA Research Triangle Park (RTP) . Funding from EPA/RTP has enabled the

GC/MS isotope dilution method to be refined for measuring parts -per-billion

high-pressure gas standards. Procedures for preparation, storage and analysis

of a volatile hydrocarbons in whole blood quality assurance materials are being

developed for EPA/Las Vegas.

The Group has made a modest contribution to the Division's SRM program.

Three separate alcohol in reference fuel SRMs were prepared and certified this

year. These SRMs, 1837-39, contain various alcohols commonly added to gasolines and will be of use to the petroleum industry as well as Federal, state,

and local regulatory agencies. Measurements of the Cod Liver Oil Research

Material (RM 1588) have been repeated using the MSD equipped gas chromatograph

and the material now has certified values and has been re-released as an SRM.

PAH content in the GC Performance/Coal Tar SRM is being determined at the

present time.

Additionally, the Group has performed a number of service analyses for

other Governmental Agencies. We have determined the PCB concentration of

transformer fluids taken from the White House, the rate of leakage of methylene

bromide from fuse batteries for the Harry Diamond Laboratories, the chemical

composition of the exhaust from a document burner for the Department of

Defense, and latent hydrocarbon residue analysis for the Naval Research

Laboratories

While the Group is heavily committed to its Other Agency and SRM work, we realize the need to concurrently pursue an active research program in order to

maintain our cutting edge measurement capabilities. We hope in the next three

years to make substantial progress in four areas. First, we want to continue

to attain proficiency in multidimensional gas chromatography and would like to

attract a Postdoctoral Research Associate in this area. This technique will be

increasingly needed for the separation of moderately polar solutes in extremely

complex matrices such as nutrients and flavors in foodstuffs and heteroatom

polycyclic aromatic compounds (PAC) in environmental particulate materials. We are eager to expand into the area of supercritical fluid capillary chromatography. With SFC instrumentation we will be able to broaden our spectrum of

analytical capability to include bio-molecules, vitamins and nutrients, and

thermally fragile molecules such as non-chlorinated pesticides and drugs of

abuse. We will also investigate the use of the new capillary column

technological breakthroughs, ultra- thin films and high temperature phases and

columns, for new areas of application such as the high resolution separation of

85
di- and triglycerides. Finally, we want to develop new analytical methods for

certification of needed SRMs such as tributyl tin in a marine sediment matrix.

Stephen N. Chesler, Group Leader; Franklin R. Guenther, Reenie M. Parris,

Lauren E. Perry, Richard E. Rebbert, Michelle M. Schantz, and Michael R.

Summers

4 . Liquid Chromatography Group: Overview

The activities of the Liquid Chromatography Group continue to be focussed

on (1) gaining a better understanding of the mechanisms of retention and

selectivity in liquid chromatography (LC) , and (2) applying this information to

the development of methods for the isolation, separation, identification, and

quantification of individual components in various mixtures and natural

matrices

Physical and chromatographic characterization of alkyl bonded phases

continues to be a major area of research in the understanding of reversed-phase

LC retention mechanisms. Investigations of the use of small -angle neutron

scattering (SANS) for the physical characterization of alkyl bonded phases are continuing. Using SANS, the pore network of porous silica and controlled pore

glass has been shown to be fully accessible to chromatographic solvents even after alkyl surface modification. Initial SANS experiments to determine the

thickness of the alkyl layer have shown that the resolution of the technique is

sufficient to distinguish between C8 and C 18 monolayers (see Technical Report

17). Work in progress will use SANS to investigate the orientation of the

alkyl chains (i.e., extended vs. collapsed) on the substrate surface as the

polarity of the mobile phase changes.

Investigations of selectivity in reversed-phase LC have been directed

towards the comparison of selectivity on a variety of alkyl phases with

particular emphasis on the comparison of monomeric and polymeric alkyl phases.

Polymeric C 18 phases have been shown to provide greater selectivity for the

separation of polycyclic aromatic hydrocarbons (PAH) than monomeric phases and

separation of PAH isomers is related to the shape of the solute. In the past

year, these studies have included preparation and characterization of (1) C 18

phases prepared with dichloro and trichlorosilanes , (2) long-chain alkyl phases

such as C30 , and (3) novel alkyl phases with potentially more rigid chains than

conventional phases. These studies are directed towards the development of a "model" of the physical nature of alkyl bonded phases, e.g., the thickness and

the surface density of the alkyl layer, the extent of cross-linking in

polymeric alkyl phase prepared with multifunctional silanes, and the

orientation of the alkyl chains.

The LC Group is heavily involved in the application of LC to the

measurement of trace -level analytes in various samples as part of the NBS

Standard Reference Materials Program and in support of projects for Other

Federal Agencies including the Environmental Protection Agency (EPA)

Department of Energy (DoE) , National Cancer Institute (NCI), Department of

Agriculture (USDA) , and National Oceanic and Atmospheric Administration (NOAA)

Specific SRM activities are discussed in the Division overview.

We have collaborated with the Inorganic Analytical Research Division (551)

in the development of LC methods for the separation of metal chelates and the

combination of LC methods with atomic absorption spectrometric (AAS ) detection.

86
Ion-pairing LC has been used for preconcentration and determination of Cr(VI)

in the presence of Cr(III) using AAS detection. We are also assisting the

Inorganic Analytical Research Division in the preparation of a C 18 modified

silica substrate with three concentration levels of carbon for use as an SRM

for carbon determination. The development of this SEIM is a direct result of a joint effort with Division 551 during the past several years to determine

carbon content in LC packing materials. In conjunction with the GC Group,

research in the use of supercritical fluid extraction for the isolation of

analytes of interest from various matrices is in progress. Development and

validation of this extraction technique will provide a valuable alternative to

conventional extraction procedures which will be useful in a number of our projects, particularly in SRM certification, where two independent methods for

sample preparation as well as analyses are desired.

During the past year, we have been funded by the Office of Standard

Reference Materials to investigate the feasibility of developing an SEIM for the

characterization of LC columns. An extensive literature survey has been

conducted and discussions held with a number of researchers to determine the

types of solutes used by various laboratories to evaluate such column properties as carbon loading, selectivity, phase type, residual silanols, etc. Based

on the results of the literature survey and discussions, test mixtures of

selected solutes will be prepared and used to evaluate the properties of a number of reversed-phase LC columns. Based on these results, a suitable column

performance SRM will be developed.

During the coming year, several new SRMs will involve LC measurements

including: f^t- soluble vitamins in serum, a re-issue of SEIM 1647 (PAH in

solvent), and a drugs of abuse (THC and metabolites) in urine material. A

major new effort will be directed towards the certification of a marine

sediment SEIM for various organic pollutants.

In support of the NCI Cancer Chemoprevention Project, we have used LC

methods and differential scanning calorimetry to determine the purity of

commercial vitamin standards; investigated approaches for the measurement of

ascorbic acid in serum; evaluated the use of supercritical fluid extraction to

remove vitamins from serum; determined the relative absorptivities of /?- carotene in various solvents; investigated the feasibility of using directinjection techniques for the determination of vitamins in human serum, and

established protocols for the banking of serum samples in the specimen bank

facility

A new project sponsored by EPA's Integrated Air Cancer Project involves

the standardization of an LC fractionation scheme for the isolation of mutagenic components in air particulate samples. Initially, we will investigate

the LC retention behavior of selected "marker" compounds which will be representative of various fractions, e.g., PAH, nitro-PAH, aza-arenes, quinones,

phenols, etc. Based on these retention data, specific compounds will be

selected to serve as markers to standardize the collection of fractions for

further chemical and biological characterization.

We made extensive LC measurements on three samples (an air particulate

extract, a diesel particulate extract, and a diesel particulate sample) for the

determination of PAH and nitro-PAH as part of an international round robin

study sponsored in part by the Coordinating Research Council and DoE (see

Technical Report 25). These LC measurements, in conjunction with the GC/MS and

LC/EC results, will serve as benchmark values for the study in evaluating the

87
data from the various laboratories. As a result of this study, we have extensive information on the comparison of LC and GC/MS methods for the

determination of these compounds in complex environmental samples.

The LC Group has also been involved in several Other Agency projects such

as the determination of herbicides in a water sample to provide NBS traceability for an EPA QA material, the development of LC methods for the measurement

of high molecular weight PAH in combustion- related samples (DoE) (see Technical

Report 19) , use of LC fractionation to isolate radiolytic products in irradiated meats (USDA) , and the determination of PAH in marine sediments (NOAA)

Four new staff members and guest scientists have joined the LC Group

during the past year. Barbara J. Koster joined the Group with responsibilities

for the operation of and coordination of the activities in the Environmental

Specimen Bank facility; Professor Zeng-nan Zhou from the East China Institute

of Textile Science in Shanghai has joined the Group as a guest scientist

working in the development of methods for water soluble vitamins in food

matrices; Apryll M. Stalcup, a graduate co-op from Georgetown University, will

investigate solute retention mechanisms in both LC and supercritical fluid

chromatography; Professor Barry K. Lavine , a guest scientist from Clarkson

University, is providing the Group and the Division with expertise in

multivariate analysis; one staff member, Walter F. Kline, left NBS to accept a position in industry.

During the next several years, research in the understanding of LC

retention mechanisms will continue to focus on (1) methods of physical and

chromatographic characterization of stationary phases, (2) factors affecting

selectivity, and (3) comparison of LC and SFC. We will continue to develop LC

methods for the determination of trace organic constituents in various

matrices. For environmental samples we will continue to improve LC methods for

the isolation and determination of the compounds of interest with emphasis on

the polar constituents. In the coming years, we anticipate more emphasis on

the measurement of vitamins in serum and food matrices and drugs of abuse in

urine. In addition to analytical separations, LC will become more important as

a means of isolating the analytes of interest from the serum or urine matrices

prior to quantification by other techniques.

We intend to actively recruit postdoctoral research associates and guest

scientists with backgrounds in retention mechanisms, bonded phase characterization, microbore/capillary LC, LC detector development, and/or supercritical

fluid chromatography.

Stephen A. Wise, Group Leader;* Bruce A. Benner, Jeanice Brown-Thomas , Richard

G. Christensen, Barbara J. Koster, Barry K. Lavine, Sam A. Margolis, Lane C.

Sander, Apryll M. Stalcup, J. Sullivan, and Zeng-nan Zhou.

5 . Mass Spectrometry Group: Overview

The Mass Spectrometry Group conducts research in a number of areas including both basic and applied efforts. The major part of our work continues

to be in the development of mass spectrometric methods for the accurate quantitation of individual organic compounds in complex matrices and in the laserinduced photodissociation of ions as part of the mass spectrometry competence

building program, "Analysis of Ionization Mechanisms and Ion Structures."

88
Quantitative measurements made in the mass spectrometry group in the past

year have been used in the certification of several SRMs as described in

Technical Report 26. We also contributed to an international round robin on

the determination of polynuclear aromatic hydrocarbons (PAH) and nitro-PAH.

The results are reported in Technical Report 25. The research reported in

previous years on the behavior of PAH and substituted PAH in negative ion

chemical ionization has been extended and applied (Technical Report 12), to the

determination of some PAH and substituted PAH in the extract from urban air and

diesel exhausts particulates.

The use of isotope dilution and GC/MS in developing definitive methods for

quantitative determination of constituents in human serum has continued in

collaboration with the Bioanalytical Techniques Group. A new and substantially

simplified method developed for uric acid is described in Technical Report 15.

The method for cholesterol is being applied to several serum pools, distributed

to clinical laboratories by the College of American Pathologists as part of

their proficiency testing program, in an effort to resolve a discrepancy

between the mean results of the clinical laboratories and those of the Centers

for Disease Control's reference method. Work on a method for "triglycerides"

has been deferred in favor of developing a method for vitamin C (ascorbic

acid)

The isotope dilution methodology developed for the definitive methods has

been adapted and extended to low concentrations for the determination of 3-

quinuclidinyl benzilate (BZ) , a chemical agent scheduled for demilitarization,

and its metabolites as described in Technical Report 13. This isotope dilution

GC/MS approach is also being employed in a joint effort with the Center for

Radiation Research for the Department of Agriculture. We are investigating the

feasibility of monitoring certain oxidation products of amino acids formed in

fresh meat exposed to ionizing radiation as a means of determining the radiation dose to which the meat was exposed. This work is described in Technical

Report 14.

Investigation of the laser- induced photodissociation of both positive and

negative ions generated by cesium ion bombardment, done as part of the competence building program in mass spectrometry, has continued successfully,

demonstrating that the technique has potential for the determination of the

structure of large molecules. The results are summarized in Technical Report

11 .

In the year ahead, we plan to continue work on many of the projects with

which the group is presently involved. Specific efforts will include:

completion of the method for the determination of BZ; the development of SRMs

with certified concentrations of metabolites of cocaine and marijuana in urine,

the development of methods for the determination of polar compounds in air and

diesel particulates and for radiolytic products in meats to determine radiation

dose; the completion of a definitive method for vitamin C; the application of

the new method for uric acid; the improvement and application of the definitive

method for cholesterol to a number of serum pools as our contribution to the

development of a National Reference System for Cholesterol, and, as part of the mass spectrometry competence building program, increasing the extent of

photodissociation achieved and investigating the chemical modification of

molecules of biological interest to permit photodissociation with visible

light. Longer range plans include: the development of SRMs for cholesterol at

high levels; the development of definitive methods for triglycerides in serum

and for analytes in matrices other than serum; the extension of the post89
irradiation dosimetry program to include non-meat products and to investigate

loss of nutrient content as a function of dose; the development of a triple

quadrupole mass spectrometer for high accuracy quantitation; and the adaptation

of photodissociation experiments to instrumentation other than the high

resolution double focusing magnetic instrument presently used.

The age and limitations of our instrumentation has been and remains a concern. During the past year, a quadrupole GC/MS instrument was retired, and

a triple quadrupole instrument, no longer useful for analytical measurements,

was permanently loaned to the Chemical Kinetics Division, Center for Chemical

Physics. The group presently has five mass spectrometers; two of these

instruments have proved difficult to keep operating this past year. The

expected acquisition of a modern, fully equipped, triple quadrupole instrument

in 1987 will provide additional GC/MS capacity and substantial new analytical

capability

John-Marc Rodier, a student at The American University, has joined the

group for the summer to assist with the photodissociation experiments and to

run service analyses. He is expected to return next summer. We are seeking

postdoctoral candidates whose interests are compatible with our programs and

are particularly interested in finding a strong candidate for the

photodissociation work. We are also in need of and seeking an additional

person for the drugs in urine SRM work.

Edward White V, Group Leader; Gary D. Byrd, Polly Ellerbe, Laurence R. Hilpert,

Stanley Meiselman, Larry R. Phillips, John-Marc Rodier, Lorna T. Sniegoski, and

Michael J. Welch.

90
B. Selected Technical Reports

(Organic Analytical Research Division)

1 . Analysis of Electrophoretic Protein Patterns of Human Liver

J . J . Edwards

The Bioanalytical Techniques group has undertaken the task of establishing

two-dimensional polyacrylamide gel maps of selected human tissue proteins. The

initial effort is directed toward mapping non-pathological tissue samples in

order to begin generating a data base of normal proteins present in the population. Presently the tissue under study is human liver obtained from the

NBS/EPA Environmental Specimen Bank. To date we have examined five liver

specimens by this protein mapping technique. These samples were from individuals in the age range 18 to 57 years and included three males and two females.

Because we are not presently equipped to obtain a computerized analysis of

the protein maps, we used the services of Protein Data Bases, Inc. (Huntington

Station, NY) to provide the initial computer gel matching services. The com- puter gel matching involved the scanning, digitization, smoothing and storage

of two film exposures of each gel pattern. From this information, composite

images of each gel were created. Confirmed protein spots were assigned

position numbers which were used in subsequent matching experiments. Quantification was accomplished by conversion of the optical density of each protein

spot to the relative amount of protein represented by that image. Quantification data were presented in the form of bar graphs in order that individual

spots in each sample could be compared. Approximate molecular weight and

isoelectric point data were also provided.

One sample was arbitrarily chosen as a "standard" for comparison to the

other samples. This sample was found to contain 472 resolved protein spots.

Overall, individual samples contained between 362 and 473 resolved spots with a total number of 594 different spots being detected.

Using this information as a starting point, we can assess our in-house

capabilities for gel imaging and protein quantification, and establish a mea- surement base against which other protein samples can be compared. The information obtained concerning protein electrophoretic patterns from "normal"

tissue samples will also be of interest to other researchers in several diverse

fields such as biotechnology, environmental toxicology and separations science.

2 . Analytical Studies of Commercial Sources of Sodium Dodecvl Sulfate

M.C. Kline and D.J. Reeder

Electrophoretic separations of proteins can vary depending upon the source

of sodium dodecyl sulfate (SDS) utilized in the system. In many instances the

different sources of SDS may have the same composition by chain length analysis, but behave quite differently in their ability to solubilize proteins.

Analytical tests were performed on 18 different lots/sources of SDS to determine the presence or absence of factors other than chain length that may be

associated with the quality of electrophoretic separation. These include:

pH: The pH of a 1% aqueous solution of the SDS samples ranged from 5.8 to

9.5, demonstrating the non-uniform nature of these samples.

91
Conductivity: The conductivity of a 1% aqueous solution of the SDS

samples ranged from 1140 to 1629 siemens.

HPLC : HPLC analyses of the 1% aqueous solution of the SDS samples

utilizing a C 18 column in conjunction with a conductivity detector were performed. Total peak areas of the chromatograms ranged from 3.11 to

5.46 cm2

. HPLC analysis for the presence of free alcohols in the SDS

samples was achieved by quantitatively derivatizing the free alcohols with

1-naphthylisocyanate and chromatographing the derivatives on a C 18 column,

monitoring the absorbance at 230 nm. Free decanol, dodecanol,

tetradecanol , and hexadecanol in the samples ranged from 0.013% to 0.419%

with decanol varying from 0 to 0.106%; dodecanol from 0.006% to 0.245%;

tetradecanol from 0 to 0.116%; and hexadecanol from 0 to 0.111%.

Critical Micelle Concentration (CMC) : CMC values for 7 of the SDS samples

were established by a spectroscopic dye method. These values ranged from

0.010 to 0.022 g/L. The remaining samples are being evaluated.

Electrophoretic separations are now being performed on a standard protein

sample using the different SDS samples. After these separations are complete,

we will attempt to discover correlations between the analytical data and the

electrophoretic patterns. This work should provide researchers using electrophoresis with the basis for making choices in their selection of reagents for

protein separations based on reagent components.

3 . NMR Characterization of Solid Sugars for Use in Measurements

of Enthalpy of Combustion

B. Coxon, J.C. Colbert, and E.S. Domalski

In a collaborative project in biotechnology with personnel of the Center

for Chemical Physics, both liquid- and solid-state NMR techniques have been

used to determine the anomeric compositions of crystalline D-ribose and 2-

deoxy-D-ribose ( 2 -deoxv-D- ervthro -pentose) samples that were to be used in

measurements of enthalpy of combustion and enthalpy of formation. This study

was initiated in order to increase understanding of the energetics of chemical

bonding in nucleosides and nucleotides. Information on the anomeric compositions of the solid sugars was required so that the measured enthalpies could be

correctly attributed to either a single anomeric ring form, or to a mixture of

anomers. Such information is generally not available without analytical investigation, because, depending on the physical and conformational properties of

the sugar and on the conditions of crystallization, sugars may crystallize

principally either as a single ring form, or as a mixture of two- to- four

anomeric ring forms and an acyclic aldehvdo form. These forms may equilibrate

during melting of the sugars, as has been experienced during differential

scanning calorimetric (DSC) measurements. This behavior is also relevant to

understanding phase transition phenomena in sugars, as well as to mechanisms of

combustion.

Several investigations at NBS have suggested that the compositions of

solid sugars (for example, SRM D-glucose) and certain other related materials

(for example, pyruvate cyclic dimer) can be determined by dissolution in

dimethyl sulfoxide-d6 (DMS0-d6 ), followed by analysis of the resulting solution

by X H or 13 C NMR. In this solvent, isomerization is usually sufficiently slow

that the proportions of different forms determined soon after dissolution are a good indication of the compositions of the solid materials. The relative pro92
portions of the four ring forms of D-ribose and 2-deoxy-D-ribose have been

measured by digital integration of the HO-1 doublets in the 1 H NMR spectra of

solutions of both the crystalline and the melted sugar samples. The applicability of the solution method has been confirmed by direct analysis of the

crystalline sugars by cross -polarization- -magic angle spinning (CP-MAS) 13 C NMR

spectroscopy (courtesy of D. Vanderhart) . The results from the two NMR methods

have been compared and they indicate that the crystalline D-ribose is principally a mixture of 64-65% of the /3-pyranose (/J-p) form and 34-35% of the a- pyranose (a-p) form, whereas crystalline 2-deoxy-D-ribose is almost exclusively

the /3-p form.

The thermochemical, NMR, and DSC results have been submitted to the

Journal of Chemical Thermodynamics .

4 . Immobilized Enzymes Bound to Inert Supports Retain Activity

M.C. Kline, D.J. Reeder, P.V. Sundaram, and P. Vetter

One component of the biotechnology initiative funded by Congress during

the past year involves the investigation of mechanisms of enzyme stabilization

and protein activity. One approach to the solution of this problem involves

covalently binding proteins at sites remote from the active site. As a beginning to this work, we have immobilized the enzyme, urease, on a variety of

different inert supports by diverse coupling mechanisms. The retained enzyme

activity of small columns packed with immobilized enzyme varies from support to

support and also seems to vary with the coupling technique used.

Retained enzyme activity of the columns over time is being studied using a spectroscopic assay. At present there are 8 columns that have been studied for

32 weeks. Five columns have retained between 76% to 87% of their original

enzymatic activity. Another column has retained 17% of its original activity

while the remaining two columns have only 1% or less retained activity. In

addition to the above columns, there are 7 additional supports that have been

recently synthesized. Three of these columns are retaining their enzymatic

activity (76% after six weeks)

Supports made of Nylon derivatives seem to be better suited as immobilization sites than do those of the more popular carboxymethyl-Sephadex.

Tosylation and tresylation coupling methods appear to be the preferred

procedure for retaining urease activity on the nylon supports.

Additional studies will focus on new chemistries for linkage and on the use of enzymes that may have use in industrial biotechnology applications.

Scale-up to larger column bed volumes will be attempted once the reactions are characterized.

5 . Honey Protein Patterns from Isoelectric Focusing Allow Classification by

Origin

F.R. Guenther, D.J. Reeder, and K.L. Richie

In a previous report (Technical Activities, Center for Analytical

Chemistry, 1985, p. 113), a collaborative study with the Food and Drug Administration (FDA) is described wherein ultra- thin isoelectric focusing and two

dimensional electrophoresis were used to compare protein patterns in honey that

originated in the United States, Argentina, Hungary and China. Using ultra93
thin (160 pm) polyacrylamide gels followed by a silver staining method for

protein visualization, we found that there were significant differences in the

protein patterns in the honey of the four countries.

To pursue this study in more detail, we decided that it would be necessary

to limit our honey source to one country and instead examine several types of

honey from different floral sources and geographical regions in the United

States. We examined AO honey samples provided to us by the Food and Drug

Administration which represent several different floral sources and three

geographical locations- -California, North Dakota and Florida. Sample preparation involved dialysis, centrifugation, and adjustment to a constant protein

concentration. Ultra- thin isoelectric focusing was used as our primary method

of separation, followed by silver staining for protein detection. At this

stage of analysis, all honey samples appeared to give very similar protein band

patterns with the average (pi) values ranging from A. 9 -5. 8. To probe further, we used laser densitometry and pattern recognition programs so that we could

analyze the information encoded in the protein composition of honey.

All data from the laser scans including peak area and relative band

position were entered into a microcomputer (Lotus) spread sheet and the data

were analyzed with a microcomputer based statistical program (Statpro) or transferred to the NBS computing facility for further statistical analysis with

the ARTHUR chemometrics/statis tical software package for mainframe computers.

Pattern recognition procedures within ARTHUR were run on scaled protein data to

determine if there were significant regional differences encoded in the protein

patterns. Using several of these pattern recognition programs we were able to

correctly classify the samples according to their origins. Thus it appears

that information regarding geographical source of origin was encoded in the

protein patterns. Classification of the data based on the floral source of the

honey was also attempted. However, these analyses suffered from the lack of

enough cases for each floral source.

More work is planned to demonstrate further the capabilities of combined

high resolution protein separations and state-of-the-art data analysis procedures. We also anticipate studies to analyze more honey to see if

classification based on floral source is possible.

6 . Development of Bioanalvtical Sensors

L.L. Brown, R.A. Durst, R.M. Kannuck, and A.L. Plant

Biologically derived substances such as antibodies, cell-surface receptors

and circulating binding proteins have important application as components of

rapid sensing devices because of their binding specificity, the strength of

their interactions, and their potential for use in a wide variety of detection

schemes. We are currently exploring optical and electrochemical techniques for

detection of low levels of analyte based on immunological recognition. The

binding of analyte to antibody results in a change in fluorescence or electrochemical signal by release of indicator substance from liposomes. Liposomes

are phospholipid bilayer membranes which enclose an aqueous volume in which

such indicator agents are trapped. We have found that ferrocyanide is an excellent agent for electrochemical detection, and cannot be detected until it

is released from inside liposomes. It can be trapped in liposomes at high

concentrations (10-3 M) with minimal spontaneous leakage. For fluorometric

detection, we have used 5 -carboxyfluorescein and other xanthene dyes which are approximately 95% self -quenched in vesicles at local concentrations of 100 mM.

9A
Release of these dyes from liposomes results in dilution and increase in

fluorescence intensity. The use of liposomes amplifies the sensitivity of the

system because for every antigen- antibody binding event which occurs on a liposome surface, thousands of indicator molecules are released. Both a homogeneous and a heterogeneous assay are being developed using antibodies to

2 ,4-dinitrophenol (DNP) , a model hapten, and DNP-aminocaproyl phosphatidylcholine, which is a component of the liposome bilayer. In the homogeneous assay,

binding of anti-DNP antibody to the DNP on liposome surfaces initiates, in the

presence of serum, release of the aqueous contents of the liposomes by serum

components collectively known as "complement". In a flow injection heterogeneous assay, free antigen competes with antigen covalently coupled to the surface

of liposomes for binding to antibody which is covalently coupled to a solid

support. The number of liposomes displaced from the solid support is proportional to the amount of analyte present. The displaced liposomes are collected

downstream from the reaction chamber, disrupted with detergent, and their

trapped contents are quantified.

The sensitivity of electrochemical detection to be used in both assays is

enhanced by the use of a polymer modified electrode. The reaction of 4- [2-

(trichlorosilyl) ethyl] pyridine at an oxidized platinum surface results in the

convalent bonding of the organosilane to the electrode. By refluxing in neat

iodomethane, the pyridine is quarternized and acts as an ion exchange site for

the anionic ferrocyanide . By this preconcentration of the analyte, sensitivity

of the technique is increased by about two orders of magnitude. The use of

this polymer modified electrode also prevents fouling of the electrode surface

by serum proteins -- a common problem that has hindered electrochemical

analysis in biological solutions. This feature is especially important to our development of a homogenous immunoassay involving complement -mediated

lysis of the liposomes. The combination of high specificity for analyte with

efficient amplification provides the potential for extremely sensitive devices

with predicted detection limits of 10" 14 M.

The use of liposomes in biosensors is an important means for providing

chemical enhancement of biochemical reactions. One of the major areas to be

studied with respect to liposomes is consistency in their preparation, homogeneity in their size, and stability with respect to their permeability and

composition.

7 . Chronoamperometrv in Polymer-Modified Electrodes

W.T. Yap and R.A. Durst

In electroanalytical chemistry, the faradaic current produced by various

applied potential techniques yields important information about the analyte.

The measurements and analyses of the faradaic current in polymer-coated electrodes are complicated by the large charging current due to the high resistance

and the capacitance of the system and, in addition to the usual ionic and

molecular diffusion, by the effect of migration of charged species. In large

potential step chronoamperometry , these complications give unusual current- time

curves which are not simply of the inverse-square-root-of - time type for a simple diffusion-controlled case nor the exponential decay of an RC circuit;

neither is it a simple superposition of the two. In order to elucidate these

behaviors, we developed a digital simulation of this problem, using a finite

element procedure which is especially convenient for cases with zero flux at

the boundary. This problem has naturally two scales of time: RC , the decay

constant of the charging current and d

2 /D which is a measure of the transport

95
time of the electroactive species with diffusion coefficient D through the

thickness d of the polymer layer.

For RC«d2 /D, the current- time plot may be approximated by joining the

charging current for the RC circuit at short time with the transport -limited

faradaic current when the charging current becomes negligible. As RC

approaches d

2 /D, the effect is not as simple, and working curves were

constructed from the simulation.

By superimposing the experimental ln[current*sqrt(time) ] versus In(time)

plot onto the theoretical working curves until they fit, some of the unknown

experimental quantities, such as the diffusion coefficients, can be determined.

This procedure was successfully applied to an electrode coated with

poly[Ru(II) (bpy) 2 (4-vpy) 2 ] + PF6 “

.

The effects of these and other electrode parameters on the charge -time

behavior will be studied further to develop more useful diagnostic plots. For

example, plots of cyclic voltammetric peak current ratios or peak separations

as functions of the electrode parameters will be constructed for characterization or diagnostic purposes.

8 . FTIR-Photoacoustic Spectroscopic Characterization of Thermally Crosslinked

and Derivatized Polv(vinvlpvridinestvrene') Copolymer Film Electrodes

E.A. Blubaugh, Jr. and C.K. Chiang

One of the goals of this research program is the development of

electrochemical detectors for use with liquid chromatography. With solvents of

varying nature and fluid flow past these electrodes, long-term stability of

these electrocatalytic polymer films is of paramount importance. We have

developed a thermal crosslinking procedure which enhances the stability of the

bulk polymer film and the polymer film/substrate electrode interface by almost

two orders of magnitude.

As part of this work, it was necessary to optimize the thermal

crosslinking procedure with respect to the crosslinking agent, initiator, and

time. These polymer film electrodes contain about 10 micromoles of polymer,

and this polymer film/electrode combination is optically opaque. With these

two conditions, transmission spectroscopic techniques are ruled out. However,

FTIR-photoacoustic spectroscopy (FTIR-PAS) is ideally suited to examine samples

such as ours. FTIR-PAS is a surface sensitive and, as important, nondestructive analytical method for determining the vibrational spectroscopic character

or "finger printing" of these polymer films.

Our study began by obtaining the FTIR-PAS spectra of the polymer powder

and the crosslinking agent as received. We then addressed the questions of

whether the crosslinking agent was retained in the polymer film during the

thermal treatment and, also, were the crosslinking active sites totally

reacted. We found that the crosslinking agent was retained in the polymer

films and that the active crosslinking sites where totally reacted. An

additional piece of information that we obtained from this study was that the

parent polymer is not degraded by our oxidative thermal procedure. The second

question that we addressed was to determine if the spectrum of the polymer film

changes as a function of film thickness. This is an important question since

FTIR-PAS is a surface sensitive technique. The film thickness was varied from

about 0.1 to 1 pm and an FTIR-PAS spectrum was obtained at each thickness. We

96
did observe differences for the vibrational bands associated with the cross- linking agent as a function of thickness. At thin films we observe one IR band

for the ester groups ("1730 cm

-1

) and with thicker films we then observe three

IR bands for the ester groups. This difference is presumed to be due to the

heterogeneity of these polymer films. One possible explanation for the

heterogeneity of these films is due to spatial differences imposed by some of

the polymer macromolecules being near the platinum surface and some being far

from the platinum surface.

Future work with FTIR-PAS as a tool to study these polymer film electrodes

will focus on immobilizing different metal complexes and studying the binding

of these complexes as well as studying the binding of these complexes in the

films. This will help to determine if immobilization is via covalent linkage

or just due to simple entrapment.

9 . Catalytic Oxygen- Scrubber Column Developed for the Reductive

Electrochemical Detection of Nitro-PAH in Diesel Soot

W.A. MacCrehan and S.D. Yang

The need to remove oxygen from the mobile phase for reductive

electrochemical detection in LC has limited the application of this powerful

technique. Although many schemes for oxygen removal by complete purging of the

solvent reservoir, degassing with oxygen-permeable tubing, or even chemical

reduction with a zinc -scrubber column, have appeared in the literature, none has gained widespread use. We have developed a different approach, conceptually similar to the work of Tejada et al. at EPA Research Triangle Park, that

uses a catalytic reaction of alcoholic solvents with the mobile phase oxygen.

Oxygen reduction occurs in a 15 cm column packed with a platinum catalyst which

is incorporated into the LC system after the solvent delivery pump. Complete

reduction in the presence of methanol is evidenced by the low residual current

observed at mercury thin- film electrodes in the potential range of 0 to -1.2 V

(vs. Ag/AgCl) . We have also examined the residual current at two potentials

(-600 and -1000 mV) as a function of the percentage methanol in the mobile

phase. As little as 1% methanol provides some reduction of oxygen, but 3% is

required for low residual currents.

The convenience and efficacy of the Pt oxygen scrubber was demonstrated in

the reductive determination of nitro-polycyclic aromatic hydrocarbons (N-PAH)

in extracts of diesel particulate matter (soot) . We have investigated two

approaches to the problem of achieving the selectivity to measure the N-PAH in

this very complex matrix. In earlier work, we used the differential -pulse (DP)

mode of detection to increase the detector selectivity, so that sample fractionation was not necessary. However, because of the unusual sensitivity of

the electrochemical signal to the detection conditions for N-PAH, the reproducibility with this approach is poor. We had not observed the reproducibility

problems with simple amperometric detection, so the second approach we have

pursued this last year to achieve adequate selectivity to determine the N-PAH

in this complex matrix is a two-step prefractionation of the soot extract.

First, a hexane/methylene chloride extract is solvent extracted with concentrated aqueous ammonia to remove many interfering acidic components. The

organic layer is collected, evaporated, redissolved, and then sorbed onto a small normal phase (silica) sample preparation cartridge and eluted with

hexane : methylene chloride. This fractionation procedure removes many of the

interfering reducible matrix compounds (such as PAH-quinones ) . Then, using a simple isocratic solvent program with the amperometric detection, baseline97
resolved signals for the 1-nitropyrene and its deutero analogue can be

achieved. Results on the determination of 1-nitropyrene in a diesel soot

sample certified recently as SRM 1650 by the new LC/EC technique are in

agreement with independent measurements by GC/MS and LC/FL.

10 . Determination of Biogenic Thiols Using HPLC with Electrochemical

Detection

D. Shea and W.A. MacCrehan

A variety of organic sulfur compounds are produced in marine sediments by

microbial sulfate reduction and digenesis of organic matter. Thiols are of

particular importance because they are major intermediates in the microbial

cycling of sulfur and also have a high affinity for certain trace metals.

Despite the biogeochemical significance of thiols, relatively little is known

about the nature and distribution of these species in marine waters and

sediments. In order to evaluate the role of thiols in marine processes, we are developing methods for the determination of biogenic thiols and disulfides in

natural water samples.

Initially, we have been using a reverse -phase , ion-pairing HPLC separation

coupled to selective electrochemical detection at a gold/mercury- film electrode. This method has been found to be both sensitive and selective for many

thiols when analyzing standards. However, we have encountered some difficulties with the most hydrophilic thiols (e.g., cysteine) when analyzing

natural water samples. Therefore, we are currently investigating a method

using precolumn derivatization of the thiols with o-phthalaldehyde to form

isoindole products. The major advantages of this method are increased retention of the hydrophilic thiols and the capability of detecting the thiols with

both electrochemical and fluorometric detection. We are in the process of

analyzing sediment pore water samples from the Chesapeake Bay with both of

these HPLC methods.

With the development of a reliable method for determining thiol

concentrations in natural waters, we are poised to investigate the effect of

thiols on trace metal mobility in the marine environment. Efforts to account

for observed trace metal concentrations in anoxic marine waters have had only

limited success in the past, due in part to the lack of knowledge of the

identity and amount of thiols that are present. There have been no previous

attempts to measure trace metal concentrations simultaneously with the

inorganic and organic sulfur species in marine waters. In addition to the

thiol measurements, we will be using standard polarographic methods for the

determination of the inorganic sulfur species (sulfide, polysulfide, sulfite,

thiosulfate and polythionates) and certain trace metals (Cu, Cd, Zn, and Pb) . These data will be used to develop a thermodynamic model describing the

solubility of sulfide minerals in marine waters.

11 . Photodissociation of Ions Generated bv Liquid SIMS

M.J. Welch and E. White V

New "soft ionization" techniques have permitted the mass spectrometric

analysis of many biomolecules and other thermally labile and nonvolatile

compounds. Soft ionization is a term used to describe processes in which

gaseous ions are formed with little excess internal energy. Such ions tend to

remain intact, resulting in mass spectra exhibiting strong [M+Adduct] + ions and

98
little fragmentation. Since fragment ions provide structural information,

approaches have been developed for inducing fragmentation of ions generated bysoft ionization techniques.

The most common approach has been the use of collision induced

dissociation (CID) , in which the ions are excited by collisions with gaseous

molecules and then dissociate. An alternate approach is photodissociation, in

which the ions are irradiated with photons. If the photons are absorbed, the

ions are excited and may dissociate. This technique has two potential advantages: 1) the energy input to an ion can be better controlled than with CID;

and 2) photodissociation is only observed for those ions that absorb photons,

thus certain substances can be photodissociated selectively in the presence of

others by proper choice of wavelength.

We have investigated the photodissociation of ions generated by bombarding

a liquid matrix with high energy cesium ions, an ionization technique known as liquid SIMS. An argon ion laser is used to irradiate the first field- free

region of a double- focusing mass spectrometer. Ions that are formed by dissociations of a selected parent ion in this region are detected by means of a linked scan at a constant ratio of the magnetic field strength to the voltage

on the electrostatic analyzer. The laser beam is mechanically chopped and ions

formed in-phase with the chopped light are detected by a lock-in analyzer. We

have now studied the photodissociation by visible light of both positive and

negative ions formed by cesium ion bombardment of a variety of substances to

determine if useful structural information can be obtained.

The compounds tested for evidence of photodissociation had molecular

weights ranging from about 250-1400 u. We have observed that for compounds in

this range, the absorption spectra for gaseous molecular ion species is very

similar to that of the condensed phase material. Thus compounds which absorbed

strongly in the 450-515 run range exhibit the strongest photodissociation for

both positive and negative ions. Such compounds are generally red or orange in

color. Methyl red, for example, exhibits a moderately intense photodissociation mass spectrum, which is distinctly different from the CID spectrum. Other

compounds which are highly colored in a different portion of the visible

spectrum generally exhibit weak photodissociation, while colorless compounds

exhibit no photodissociation. The results of the photodissociation of positive

ions was recently published ( Anal . Chem. 58, 890-894, 1986). For negative

ions, electron detachment is a competitive process with photodissociation.

While we are unable to measure the amount of electron detachment that occurs, we can estimate its relative effect by comparing the abundance of daughter ions

formed by photodissociation with the total loss of abundance of the parent ion.

We found that if the daughter ion formation is large, the relative amount of

electron detachment is small, but it becomes the major factor if the compound

being tested exhibits low daughter ion production.

The technique is limited on our present instrumentation by the short

interaction time between ions and photons. It is also limited by the lack of an intense uv source in the 200 nm region, where most substances absorb. We are investigating the attachment of groups with chromophores for visible light to

colorless molecules, such as peptides, to determine if structural information

can be obtained. The combination of a fourier transform mass spectrometer,

which allows ions to be stored and irradiated for up to a few seconds , with an excimer laser, which provides intense pulses of uv light down to 190 nm,

appears to be the most promising approach to making this technique a useful

structural tool.

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12 . Determination of PAH and Alkylated PAH in Particulate Extracts Using

Negative Ion Chemical Ionization Mass Spectrometry

L.R. Hilpert

An interesting aspect of the negative ion chemical ionization (NICI) mass spectrometry of polycyclic aromatic hydrocarbons (PAH) is the selectivity of

detection observed for certain isomeric species. Two striking examples of this are the selectivity of detection observed for the molecular anion (M“ • ) of

fluoranthene over pyrene, and the selectivity of detection of M" • for

benzo (a)pyrene over benzo (e) pyrene . Under optimized conditions of ion source pressure and temperature, the molecular anion for fluoranthene is more than

lOOx more abundant than that of pyrene, and the molecular anion for benzo(a)-

pyrene is more than lOOOx more abundant than that of benzo (e) pyrene . In

addition to the selectivity of detection observed for the parent PAH, similar

selectivities are seen for their alkylated homologues. As many alkylated PAH

are known to be as mutagenic as the parent PAH, and in some cases more so (e.g., chrysene is only weakly mutagenic, whereas 5-methylchrysene is as potent

a carcinogen as benzo (a) pyrene ) , sensitive analytical methods capable of determining alkylated species at low concentrations in complex mixtures are needed.

NICI has proven to be a useful mass spectrometric technique for solving the

difficult problem of differentiating isomeric PAH species.

During the past year NICI and El mass spectrometry were used for the

determination of PAH and alkylated PAH in two particulate samples which have

previously been certified as Standard Reference Materials: SRM 1648, Urban

Particulate Matter, and SRM 1650 Diesel Particulate Matter. Using a combination of El and NICI techniques, it was possible to differentiate and quantify

individual isomeric PAH and alkylated PAH based. on the selectivity of detection

under NICI conditions. Methyl -substituted fluoranthenes were easily distinguished from methylpyrenes , and methylbenzo(a)pyrenes and methylbenzofluoranthenes could be distinguished from the methylbenzo(e)pyrenes

Under El conditions both methylfluoranthenes and methylpyrenes are detected in the selected ion monitoring analysis. Under NICI conditions

however, fluoranthene and the methylfluoranthenes are detected selectively. No

peaks due to pyrene or the methylpyrenes are observed. Comparison of the El

and NICI analyses allows facile identification of the me thy Ifluoranthenes and

the methylpyrenes.

Methyl -substituted benzo (e)pyrenes could also be distinguished from other

methyl -substituted MW 252 isomers (methylbenzofluoranthenes , methylbenzo(a)

pyrenes, or methylperylenes) using NICI. Although the situation was somewhat

more complicated by the fact that there are more MW 252 species which give a NICI response, it was possible to identify three different methylbenzo(e)

pyrenes in extracts of the air and diesel particulates.

Results from the quantitative measurement of alkylated PAH showed that the

methylfluoranthenes were present at approximately 17 /ig/g in the diesel

particulate sample, which represents approximately 33% of the fluoranthene

concentration (51.0 /ig/g). The methylpyrenes were also present at approximately 30% of the pyrene concentration. In the air particulate sample, the

methylfluoranthenes were present at 2.5 /ig/g, which represents approximately

30% of the fluoranthene concentration (9.2 /ig/g). The methylpyrenes, at 1.3

/ig/g were 18% as abundant as pyrene (7.3 /ig/g) in the air particulate sample.

The methylbenzofluoranthenes and methylbenzo(a)pyrenes were present at

100
approximately 30% of the concentration of the parent PAH in the diesel

particulate SRM, and at approximately 12% of the parent PAH concentration in

the air particulate SRM.

In addition to the selectivity advantage offered by NICI , it is well

suited for the quantitative determination of alkylated PAH due to the greater

sensitivity for those compounds which are NICI sensitive. Also, response

factors for alkylated PAH are essentially the same as for the parent PAH under

NICI conditions, unlike El where there may be large differences in response

factors for isomeric alkylated PAH. This enables reliable quantitative results

to be obtained, even in the absence of authentic standards for the individual

isomers. In this regard, work is currently underway on the NICI determination

of nitrated PAH and alkylated nitrated PAH (for which there are few authentic

standards available) in the diesel and air particulate samples.

13 . Development of a Confirmatory Chemical Test for Exposure to

3 -Ouinuclidinvl Benzilate (BZ)

G.D. Byrd, L.C. Sander, L.T. Sniegoski, and E. White V

The current stockpiles of the incapacitating agent 3-quinuclidinyl

benzilate (BZ) in the U.S. are scheduled for demilitarization in the near

future. Because of the potential for worker exposure to this material, the

U.S. Army Medical Research and Development Command is supporting the development of a confirmatory test for human exposure to BZ prior to the start-up of

the actual demilitarization process. The purpose of this project is to develop

a highly specific confirmatory test based on an evaluation of the literature

and from research conducted by NBS . We are developing a method for this test

using isotope dilution GC/MS analysis of urine sample extracts.

BZ is a relatively nonvolatile ester that affects the brain and nervous

system. It is a specific binding antagonist for the muscarinic class of

receptors and is capable of producing incapacitation at very small doses (1-5

ng/g) . Of the BZ that enters the body, 50 to 90% is excreted via the kidneys

with most in the form of the metabolites benzylic acid (BA) and 3 -quinuclidinol

(Q) . The exact relationship between BZ dose and levels of BZ, BA, and Q in the

urine is not well understood. However, based on the known no-effect level, the

required detection limits of these analytes in urine have been set at 0.5 ng/mL

for BZ and 5 ng/mL for BA and Q.

Confirmation of specific exposure to BZ requires that the analysis be for

intact BZ or for both BA and Q. A method for quantifying all three analytes is

desirable. Initial work on this project has focused on the metabolites BA and

Q. Isotope dilution GC/MS was selected as the analytical method because of the

need for high sensitivity and selectivity for these analytes in a complex

matrix. Labeled analogs of BZ, BA, and Q were synthesized in order to do the

isotope dilution measurements.

BA was extracted directly from urine with chloroform. Q, on the other

hand, proved difficult to extract from urine into organic solvents due to its

polar and hydrophilic properties. A method using a Florisil SepPakTM cartridge

was developed to remove the Q from urine. The Q was eluted from the Cartridge

with concentrated NH^OH. The extracts from both samples were dried and derivatization reagent was added to each to form the trimethylsilyl derivatives of

the analytes (BA-TMS and Q-TMS) . The recovery of each analyte from urine is

approximately 50% at the 5 ng/mL level.

101
The GC/MS instrument used was equipped with a 30 meter DB-17 fused silica

capillary column directly interfaced to the source of a quadrupole mass spectrometer. Analyses were carried out by single ion monitoring (SIM) using

the most intense ions above m/z 100. The fragment ion (C6 H5

) 2 C0TMS+ at m/z 255 was monitored for BA-TMS and the molecular ion at m/z 199 was monitored for QTMS . This work demonstrates that the BZ metabolites BA and Q can be determined

at the 5 ng/mL level in urine. Future work will involve the development of a method for detecting BZ in urine pending approval of our laboratory for

handling exempt surety material.

14 . Determination of the Relationship between Dose and Yield of Radiolvtic

Products in Irradiated Meats

W.A. MacCrehan, S.A. Margolis, W.E. May, M.J. Welch, S.D. Yang,

M. Dizdaroglu, L. Karum, and M. Simic

Treatment of foods with ionizing radiation to improve its storage lifetime

is of considerable interest to the food processing industry. Proof that cer- tain foods have or have not been irradiated will be required of food processors

and wholesalers by regulatory agencies for regulating imports/exports. Reliable measurement methods for performing post- irradiation dosimetry are therefore needed by regulatory agencies also.

In a joint effort with the Center for Radiation Research (CRR) , we are investigating the development of a method based upon production of certain

amino acids in meat exposed to radiation. Phenylalanine, a common amino acid

in protein, reacts with OH radicals formed in water by ionizing radiation to

form isomers, of tyrosine. Para- tyrosine is naturally present in meats at

relatively high levels (low ppm) , but the ortho and meta isomers appear to be

present only at very low levels. Researchers in CRR have found that, at least

in chicken meat, these two isomers may be completely absent from meat fibers,

unless the meat has been irradiated. Therefore, our efforts are concentrating

on determining if the formation of either of these two compounds can be corre- lated with the radiation dose. Other marker compounds- which are under study,

but appear less promising at this time, include two isomers of dihydroxyphenylalanine (DOPA) formed by irradiation from para- tyrosine and various compounds

produced by irradiation from tryptophan.

Investigations involving the HPLC-UV analysis of radiolytic products from

aqueous solutions of phenylalanine and para- tyrosine found a linear and

reproducible relationship between the production of the o- and m- tyrosine

isomers and the radiation dose, but the results for DOPA were much more scattered, possibly because of the instability of DOPA in solution. Direct

HPLC-UV analysis of meat-based samples is not feasible. The most promising

approach for the analysis of such samples involves use of a deuterated internal

standard, hydrolysis of the sample under strong acid conditions, isolation of

the amino acids of interest by HPLC fractionation, derivatization, and measurement by GC/MS with selected ion monitoring. Experiments with an unfractionated

meat hydrolyzate found that production of the tyrosine isomers increased versus

dose, while the DOPA isomers were not detected.

Work will continue on development of methods for the determination of

radiation dose based upon the formation of radiolytic marker compounds in a variety of meats. Our efforts initially will concentrate on pork, for which

radiation treatment is being considered to kill trichinae. At the present time we are investigating optimum conditions for HPLC fractionation. Other

102
experiments to be performed involve determining the distribution of the marker

compounds in unirradiated meats, the reproducibility of their production in

irradiated meats, and the effects of temperature, dose rate, and storage

conditions upon the concentrations of the marker compounds.

15 . Development of a New Definitive Method for Uric Acid

A. Cohen, P. Ellerbe, S. Meiselman, R. Schaffer, M.J. Welch, and

E. White V

As part of our program for developing definitive methods for organic serum

constituents, we have developed a new isotope dilution mass spectrometry (IDMS)

method for the measurement of uric acid in human serum. The original method,

developed ten years ago, gave satisfactory results, but the derivatization led

to the formation of several isomeric tetraethyl uric acids and required a complex time-consuming sample workup. Other reported IDMS methods for uric

acid are not sufficiently precise for our purposes or have not been tested for

column memory effects or measurement bias. The new method for uric acid uses a simplified chemistry and sample workup, and is more precise than the original

method. A new method for switching between the masses used for measurement has

been devised which gives excellent precision even on very narrow GC peaks.

In this new method a known weight of serum is spiked with a known weight

of uric acid-1 , 3- 1

N2 dissolved in ammonium hydroxide, and is allowed to equilibrate overnight. The uric acid retained on passage over an anion exchange

resin is eluted with acetic acid and the eluent freeze-dried. Standards are prepared by weight from solutions of unlabelled and labelled uric acid, and are freeze-dried. The uric acid from either sera or standards is converted with Nmethyl-N- ( t-butyldimethylsilyl) trifluoroacetamide containing 1% imidazole in

acetonitrile to the tetrakis(t-butyldimethyl-silyl)derivative . Samples and

standards are introduced into the mass spectrometer via a 15 m DB-1 capillary

column. Measurement of the unlabelled/labelled ratio for each sample is made

in the electron impact mode by alternately monitoring the intensities of the

(M-57) + ions at m/z 567 and 569. Samples are analyzed according to a strict

protocol which involves running each sample with standards bracketing it in

both time and ratio on two separate days. A test for column memory is included

in each day's measurements; no evidence of column memory has been seen.

To accurately and precisely measure the unlabelled/labelled ratio for a GC

peak, at least 30 measurement cycles must be acquired. Magnetic switching is

too slow for our observed peak width of about 14 s, and accelerating voltage

switching is too imprecise. We have devised a new system to switch between

masses using the beam deflection plates located in front of the collector slit.

With this system, repeated measurements of the ratio of a given mixture of

labelled and unlabelled uric acid routinely give coefficients of variation of

under 0.1%.

We prepared three independent sets of standards and tested them for

consistency. The members of each set were used as standards for measuring the

weight ratios of members of the other sets. The difference between the

measured and weighed weight ratios was calculated as a percent difference,

which was then used to calculate a mean bias between sets. The mean bias

between sets was 0.15%, 0.10%, and 0.22% for each pair of sets.

To test for the presence of measurement bias, for example from an undetected interference, the measurements were repeated under different

103
conditions. A test for bias was made monitoring the molecular ions at m/z 624

and 626. The difference between the weight ratios measured at M* and (M-57) + was 0 . 11 %, which is within the precision of the measurements.

This new candidate definitive method for uric acid requires only minimal

sample preparation, shows no GC column memory effect, gives excellent precision

on repeated measurements of individual samples, shows acceptably low bias among

sets of independently prepared standards, and shows no detectable measurement

bias for serum samples. The method will be further investigated, and used to

certify uric acid concentrations in reference serum pools.

16 . Determination of Fat Soluble Vitamins using Liquid Chromatography with

UV /Visible Absorbance and Oxidative Electrochemical Detection

W. A. MacCrehan and E. Schdnberger

As part of an interlaboratory study sponsored by the National Cancer

Institute (NCI), we have developed analytical techniques for the determination

of retinol, alpha- tocopherol , and beta-carotene in human serum using reverse - phase liquid chromatography (LC) coupled to UV/visible absorbance (UV) as well

as oxidative electrochemical detectors (EC)

Several aspects of the determination of these vitamins have been

investigated: the organic solvent extraction; the choice of internal standards; separation of the vitamins and their isomers; selectivity of both the

absorbance and electrochemical detection approaches; and the detection limits

of the two detectors.

We have made notable improvement in the separation of the vitamins and

their isomers, by using a polymeric, large-pore C 13 column. We have also

noted the benefit of the addition of n-butanol to the methanol/water ( 0.02

mol/L buffer) gradient system. Using a 35 minute gradient, all trans-retinol

can be baseline separated from the 13-cis isomer; at- tocopherol can be separated

from 7 ; and /3-carotene can be separated from the a and 15,15 cis- isomers.

Oxidative amperometrie detection has been developed as an alternative to

UV for the measurement of retinol, a- tocopherol , and /3-carotene. The hydrodynamic voltamograms indicate that all of these compounds may be detected at a glassy carbon electrode at an applied potential of +900 mV. A detailed comparison of the electrochemical and UV/visible absorbance detection approaches was

made, with particular attention to the relative sensitivity and selectivity of

the two detectors. EC detection provides comparable (carotene), better

(tocopherol), and poorer (retinol) detection limits than UV. The selectivity

observed with serum extracts is better for tocopherol but poorer for retinol

and carotene.

The three vitamins were determined in several "round robin" serum pools in

order to provide benchmark values for samples being analyzed as part of an NCI

sponsored Micronutrient Analyses Proficiency Testing Program as well as in 40

split sera from an epidemiology study being conducted in Japan on atomic bomb

survivors

104
17 . Characterization of Chemically Modified Substrates by Small Angle Neutron

Scattering

L.C. Sander, C.J. Glinka, and S.A. Wise

Although liquid chromatography (LC) is now considered a mature analytical

technique, the development of LC methods for analytical separations are often

carried out on an empirical basis, without full understanding of the retention

mechanisms involved. The selection of an appropriate column for a given separation is a case in point. Even among monomeric or polymeric C 18 columns of

the same type prepared by different manufacturers , variations can be great and

separations that are easily achieved with one column may become difficult or impossible with other columns. These differences take the form of variations

in column efficiency, absolute retention, and selectivity, and may result from

differences in phase loading, the type of silane used in the synthesis, and

trace metal activity and other differences in the silica substrate. For these

reasons, the characterization of physical and chemical properties of bonded

phase sorbents is of highest importance in elucidating such differences and the

process involved in solute retention.

Small angle neutron scattering (SANS) is one technique well suited to the

study of bonded phase morphology. In a collaborative effort with a scientist

in the Institute for Materials Science and Engineering (C.J. Glinka), we have

demonstrated the utility of SANS for the characterization of pore structure in

bare silica substrates. Both surface area and pore size measurements determined by SANS were observed to correlate closely with values determined by

other techniques. Furthermore, a procedure known as density matching was used

to probe pore accessibility. By filling the pores of the bare silica with a solvent having similar scattering properties as the silica (in this case, a mixture of water and deuterated water), scattering from the sample was eliminated, thus proving the existence of a fully permeable pore network.

To obtain scattering information about alkyl modified substrates, a related density matching study was carried out using a mixture of methanol and

deuterated methanol with C8 and C 18 modified controlled pore glass (CPG) . The

composition of the mixture was adjusted so that the scattering length density

(sld; index of refraction for neutron scattering) matched that of (bare) CPG.

The resulting scattering patterns were attributed to scattering from the alkyl

layers. An analysis of the scattering patterns revealed that the pore network

of the CPG was fully permeable to the methanolic mixture, even after silanization (no pore blockage) . The scattering was found to be related to pore size

of the CPG as well as bonded phase thickness. Because differences between the

C 8 and C 18 scattering patterns were evident, the "resolution" of the experiment

is at least sufficient to discriminate between alkyl phase thickness differ- ences of about 10 carbon atoms (ca. 1.5 nra) . Development of mathematical

models (based on the spinodal decomposition model for CPG) are in progress that

should permit explicit evaluation of bonded phase thickness. Measurement of

alkyl phase thickness of monomeric and polymeric C la phases may ultimately lead

to a description of solute retention processes that will aid column selection

and method development.

The use of SANS to study bonded phases may also answer a controversial

question about phase morphology: does alkyl chain conformation vary with

solvent environment? Theory suggests that alkyl chains are closely associated

with the substrate surface in polar solvents (collapsed state) and fully

extended in nonpolar solvents (extended state). To test this theory, density

105
matching experiments will be carried out in methanol, tetrahydrofuran, and

toluene environments. Any changes in the resulting scattering patterns will be

conclusive proof of phase conformational transitions.

18 . Determination of the Molar Absorptivities of Bilirubin Isomers

R.C. Christensen

Natural bilirubin occurs as the IXa isomer. In the process of isolating

preparations of bilirubin, some isomerization to the Ilia and XHIa forms

takes place. These isomers, Ilia, IXa, and Xllla, can readily be separated by

normal-phase liquid chromatography (1), but quantification of the relative

amounts of each isomer present is not straightforward because the molar

absorptivities of the isomers are different. If the molar absorptivities were

known, however, at some given wavelength, the chromatography could be monitored

with a variable wavelength UV absorbance detector, and the relative amounts of

each isomer present could be inferred from the areas of the respective chromatographic peaks. Since the molar absorptivities of these compounds vary with

the solvent it is important to know them in the solvent used as the

chromatographic mobile phase.

Measurements of the molar absorptivity of these substances have been

reported by McDonagh (2), and others have been made by A. Cohen and R. Burke in

CAC. They are reported in chloroform, however, and at the wavelength of

maximum absorbance, rather than all at the same selected wavelength. Therefore, it was decided to isolate a sufficient quantity of each isomer by semipreparative liquid chromatography to enable us to determine the desired

absorptivities

Separations were carried out using a semi-preparative scale silica column

with a mobile phase of methylene chloride containing 0.7% acetic acid.

Fractions were collected from a number of runs, with the effluent being

carefully filtered to remove silica particles from the column. Working in

subdued light to inhibit photoisomerization, the solvent was evaporated. Each

fraction was subjected to a refraction and the solvent was removed as before.

Analytical-scale liquid chromatography using a silica column, eluting with

methylene chloride containing 2% acetic acid showed that the preparations had

negligible contamination with the other isomers, with the exception of the

Xllla sample, which contained a small amount of the IXa isomer.

Molar absorptivities were measured at 23.6 °C at 452 nm in methylene

chloride-2% acetic acid, making a correction for the IXa isomer present in the

Xllla isomer preparation. They were also measured in chloroform. Standard

Reference Material 916, Bilirubin, was used as a photometric standard.

The millimolar absorptivities (1 cm

-1 mmol-1

) at 452 nm were found to be:

Solvent Ilia IXa Xllla estimate

ch2 ci2 /ch3 cooh 68.26 61.93 51.42

of S.D.

0.52

CHC13 67.50 61.04 51.61 0.18

106
The absorptivities measured in chloroform were in good agreement with

those found by others.

The determination of these values in conjunction with the use of the HPLC

method described in reference (1) will assist analysts in making rapid,

unambiguous assays of bilirubin samples for their content of these three

isomers

1. T . A. Woodbridge and D.S. Lightnor, J. Liquid Chromatogr. 1, 657 (1978).

2. A.F. McDonagh and F. Assisi, FEBS Letters 18., 315 (1971). (FEBSFederation of European Biochemical Societies).

19 . Determination of High Molecular Weight PAH in Coal Tar Air Particulate

Materials

B.A. Benner, G.D. Byrd, A. Colmsjo, and S.A. Wise

The determination of polycyclic aromatic hydrocarbons (PAH) in

environmental samples has focussed primarily on the measurement of PAH of

molecular weight less than 300. Both capillary gas chromatography (GC) and

reversed-phase liquid chromatography (LC) have been used extensively for these

analyses. In general, the carcinogenic nature of complex PAH mixtures has been

correlated with the concentrations of PAH of molecular weight 228 to 300 and,

in particular, to the level of benzo [a] pyrene . However, Grimmer et al . (1)

have shown recently that PAH of MW greater than 300 accounted for about 50% of

the- carcinogenicity of a hard-coal combustion effluent.

Recently, we reported the detailed characterization of PAH mixtures

isolated from two Standard Reference Material air particulate samples (2) . The

PAH mixture was divided into subfractions based on the number of aromatic

carbons. Of particular interest was the last fraction which contained a number

of isomers of molecular weight 302 based on GC-MS analysis. The determination

of PAH isomers of molecular weight 302, e.g., dibenzo- or naphthopyrenes

dibenzo- or naphthofluoranthenes , and benzoperylenes , has received relatively

little attention for several reasons: [1] their low concentrations in samples

of environmental interest relative to the lower molecular weight PAH, [2] the

large number of possible isomers (34 isomers), and [3] the limited availability

of authentic reference standards. In addition, GC is only partially successful

in separating the numerous isomers and mass spectrometry provides little differentiation among the various isomers. Because of the above-mentioned limitations, the determination of these compounds in complex PAH mixtures has been

generally limited to tentative identifications of one or two of these isomers

based only on comparison with GC retention times.

Reference compounds were obtained for 19 of the possible 34 PAH isomers of

molecular weight 302. Chromatographic retention characteristics were

investigated for GC and LC (normal-phase LC on an aminosilane column and

reversed-phase LC on both monomeric and polymeric C 10 columns). In normalphase LC these compounds have similar retention characteristics, thereby

allowing isolation of these isomers as a group from complex mixtures. As with

other groups of PAH isomers, polymeric C 18 columns were found to have greater

selectivity than the monomeric C 10 column for the reversed-phase LC separation

of these isomers. Reversed-phase LC on a polymeric C 10 column was capable of

separating all seven of the available dibenzo- and naphthopyrenes and seven of

the ten dibenzo- and naphthofluoranthene standards. The elution order of these

107
isomers on the polymeric C 18 phase is closely related to the shape (length- tobreadth ratio) of the solutes, i.e., the more rod-like solutes are retained

longer

PAH isomers of molecular weight 302 were isolated and identified in two

Standard Reference Materials: an air particulate extract (SRM 1648) and a coal

tar extract that is being certified as SRM 1597. The compounds of interest

were isolated from the extracts using normal-phase LG. Thirteen isomers of

molecular weight 302 were identified using a combination of GC-MS, reversedphase LC with fluorescence detection, and Shpol'skii fluorescence spectroscopy

of chromatographic fractions collected from the reversed-phase LC analysis.

The Shpol'skii fluorescence analysis of the fractions was performed by Prof.

Anders Colmsjo of the University of Stockholm. The following isomers were identified in the coal tar extract: dibenzo [a, e] pyrene , dibenzo [ a , i ] pyrene

dibenzo[ a, h] pyrene, dibenzo[e,l] pyrene, naphtho ( 2 , 1-a] pyrene , naphtho[2,3-

ajpyrene, naphtho [ 2 , 3-e jpyrene , dibenzo [ a , e ] fluoranthene , dibenzo [b , k] fluoranthene , naphtho [ 1 , 2-k] fluoranthene , naphtho [ 2 , 3-b] fluoranthene , naphtho [2, 3-

k] fluoranthene , and benzo [b]perylene . Most of these isomers have not been

identified or quantified previously in either coal tar or air particulate

samples. Quantification of these isomers in both the coal tar and air

particulate SRM is in progress.

1. G. Grimmer, H. Brune , R. Deutsch-Wenzel , G. Dettbarn, J Misfeld, U. Abel,

and J. Timm, Cancer Letters .23, 167 (1984).

2. S. A. Wise, B. A. Benner, S. N. Chesler, L. R. Hilpert, C. R. Vogt, and W.

E. May, Anal. Chem. , in press.

20 . Development of a Refined IDMS Method for the Determination of Organic

Compounds in CRM Gas Cylinders

S.N. Chesler and F.R. Guenther

« A refined isotope dilution/mass spectrometric (IDMS) method for the

determination of organics in Certified Reference Material (CRM) gas cylinders

has been developed. Previously the CRM cylinders have been analyzed using an external standard, gravimetrically prepared cylinder. This method of quantitation is incapable of detecting a bias in the delivery of the analytes from the

cylinder, or in the gravimetric preparation. The IDMS method was designed to

overcome these flaws.

The original GC/IDMS method that was developed, employed a cryogenic trap

for concentrating large volumes (1-2 liters) of CRM gas prior to cryofocussing

onto the head of a capillary GC column. The isotope diluent was added in the

form of a solution through a heated injection port. This method provided data

with a coefficient of variation of 5 to 10% for the ppb level samples. A large

portion of this imprecision can be attributed to uncertainties associated with

measurement of the volume of sample taken from the cylinder.

In this approach, a sampling loop of known volume is filled with the gas

from a cylinder, with that volume of gas being subsequently injected onto the

head of a GC column. A known quantity of a solution containing isotope

diluents for each analyte is then injected onto the column and quantitative

analysis of the analytes within the gas is then carried out. With knowledge of

the loop volume, temperature and pressure, the molar concentration of the

analytes within the cylinder can be calculated.

108
An 8-port valve was configured such that a 3.5 mL stainless steel loop

could be filled from the cylinder, and the contents of the loop switched into

the gas stream of a capillary column. It was discovered that compounds such as chlorobenzene and bromobenzene concentrate within a loop at room temperature.

Therefore, the valve and loop were placed in a thermostated oven and kept at

80° C. A 0.20 mm outside diameter fused silica tube connected the loop to the

capillary column through an on- column injector. A regulated flow of 5.5 mL/min

was directed through the loop and into the capillary column. At this flow

rate, 5 minutes were required to quantitatively transfer the contents of the

loop to the column. A head pressure of 20 psi was sufficient to incorporate

all of this flow into the capillary column. Approximately 1 m of the capillary

column was coiled into a liquid nitrogen bath to cryogenically concentrate and

focus the analytes at the head of the column. The loop was purged into the

column for 5 minutes at which time 3 pL of an isotope diluent solution was injected through the on- column injector. The GC oven fan was then turned on,

the column pressure reduced to 10 psi, and the temperature program started.

The liquid nitrogen evaporated quickly after the fan was turned on, and the

analytes were then chromatographed. The analytes were detected and quantified

using a Hewlett Packard 5970 mass selective detector (MSD) . For maximum

sensitivity the MSD was used in the selective ion monitoring mode. The

response factor solution and the isotope diluent solution were prepared

gravimetrically in 100 mL volumetric flasks. Response factors were calculated

from multiple injections of the response factor solution.

To validate this approach, a gas cylinder containing a nominal

concentration 250 ppb of benzene, toluene, chlorobenzene, and bromobenzene was quantified. Response factors for these components relative to their labeled

homologs exhibited a variance of less then 0.5%. The calculated cylinder

concentrations had variances of less than 2%. A large portion of this variance

is probably associated with uncertainties of injecting small volumes (=3 /iL) of

solution onto the column. We are currently contemplating replacing syringe

injection with a HPLC type sample valve. Work is continuing to further

validate this method, and to compare the results obtained using this approach

to those obtained from external standard, gravimetrically prepared cylinders.

21 . Refined Analytical Procedure for the Determination of PCBs & Chlorinated

Pesticides in Human Liver Samples

S.N. Chesler, R.M. Parris, and S.A. Wise

Thirty individual human liver samples from the Environmental Specimen Bank

Facility at NBS have been analyzed for 5 selected polychlorinated biphenyl

congeners (PCBs) and 7 chlorinated pesticides using methods developed at NBS.

With this procedure, low ng/g levels of these components in human livers can be

measured because 1) matrix components that would interfere with the quantitative analysis are removed, 2) analytes are separated into 2 fractions which

precludes coelution of some components during the analytical chromatographic

analyses, and 3) sample contamination during the analysis is minimized. This

project, partially funded by EPA, is part of a continuing effort to archive and

characterize several types of environmental samples for future retrospective

analyses for both inorganic and organic components.

Concentrations of the PCBs measured ranged from 0.5 to 15 ng/g of wet

liver tissue. The individual PCB congeners chosen are among those currently

being used by many researchers as marker compounds for the identification and

quantification of PCB contamination. 4,4' -DDE levels up to 150 ng/g liver

109
tissue (wet) were measured and concentrations of other pesticides (heptachlor

epoxide, transnonachlor , dieldrin, 4,4' -DDD, 2,4' -DDT and 4,4' -DDT) ranged from

0.5 to 25 ng/g liver tissue (wet).

The method developed for these analyses consists of extraction of the

sample, two liquid chromatographic cleanup steps, and quantitative analysis

using gas chromatography with electron capture detection. To minimize contamination of the sample during the analysis, all glassware is cleaned prior to

each use with an RBS-35 surfactant cleaner and a series of solvent washes

(acetone, methanol, methylene chloride, and hexane). All glassware and sample

solutions are capped with hexane -cleaned aluminum foil except during actual

sample transfers. HPLC grade solvents suitable for pesticide residue analyses

are used throughout this procedure. These steps are necessary to avoid

significant levels of PCB contamination. With each set of samples, an aliquot

of a solution containing only the internal standard components was utilized as

a system blank and underwent each step of the analyses.

The 30 samples analyzed, which were collected in 1984 in Seattle,

Washington, were cryogenically homogenized prior to storage. For analysis, a weighed sample is ground with precleaned anhydrous sodium sulfate to disrupt

the cells and remove water from the sample. This mixture is poured into a glass column and 2 mL of internal standard solution is added. Each sodium

sulfate mixture is eluted overnight with 2/1 (v/v) hexane/acetone mixture. The

volume of the extract is reduced and the percentage extractable fat of each

sample is determined. After the volume is further reduced, the sample is

filtered using a 0.5 nm glass microfilter. To remove most lipid and other

large molecular weight components, the sample is fractionated on a PL- gel

preparative scale column. The fraction containing the PCBs and chlorinated

pesticides is collected according to previously calibrated retention volumes.

The volume of the fraction is reduced and the entire fraction is injected onto

a semi-preparative scale aminosilane column from which two fractions are collected. The first fraction contains the PCB components and nonpolar

chlorinated pesticides such as hexachlorobenzene while the second fraction

contains the more polar chlorinated pesticides (as 4,4' -DDT, dieldrin, transnonachlor and heptachlor epoxide) . The fractions are evaporatively concen- trated and analyzed using capillary gas chromatography with electron capture

detection. The internal standard method of quantification is employed. Each

set of samples analyzed included 6 liver samples, duplicate aliquots of 2 liver

samples analyzed in the previous set, 1 system blank and 2 aliquots of a gravimetrically prepared calibration solution.

Several liver samples collected in 1982 and previously analyzed for

selected chlorinated pesticides are being analyzed this year for individual PCB

congeners and reanalyzed for chlorinated pesticides using this method. Also,

liver sample aliquots stored at -25 °C, -80 °C and liquid nitrogen vapor temperature will be analyzed for these chlorinated components as part of a study

to evaluate the stability of these analytes under various conditions of

storage

110
22 . Specimen Banking Activities for the NOAA National Status and Trends

Program

B.J. Koster, W.E. May, M.M. Schantz, S.A. Wise, and R. Zeisler

Since 1979 the Center for Analytical Chemistry, in conjunction with the

Environmental Protection Agency, has been involved in an Environmental Specimen

Bank Program to evaluate the feasibility of long-term storage of various environmental samples. A pilot banking program was designed to collect several

types of environmental accumulators representative of human tissue (liver),

marine samples, and food samples. In 1985 the National Oceanic and Atmospheric

Administration (NOAA) incorporated specimen banking as part of its National

Status and Trends (NS&T) Program. The NS&T Program consists of two monitoring

projects, the Benthic Surveillance project and the Mussel Watch project, which

are designed to quantify the current status and long-term temporal and spatial

trends for key pollutant concentrations and biological indicators of contamination effects in the nation's coastal and estuarine environments. The Benthic

Surveillance project consists of 50 U.S. coastal sites at which bottom- feeding

fish tissue (muscle and liver) and sediments are collected; whereas the Mussel

Watch project consists of 150 sites at which sediment and mussels or oysters

are collected. In both of these projects the sediments and tissues are analyzed for the determination of trace elements and various organic

pollutants.

Prior to the banking of these marine specimens, detailed protocols were

developed, in conjunction with NOAA scientists, for collecting, packaging, and

transporting the specimen to the NBS Specimen Bank facility for long-term

storage. For the Benthic Surveillance project two duplicate aliquots of 150 g

each of fish liver and muscle tissue were obtained from 50-100 fish depending

on the size of the species collected. To avoid contamination, fish are necropsied in positive pressure hoods using specially cleaned titanium/teflon

tools. Two duplicate aliquots of 150 g each of sediment samples are obtained

from each sampling site. These samples are obtained using teflon cylinder

corers to remove the top 3 cm of undisturbed surface sediment from three

different grabs with a box core sampler. For the Mussel Watch project,

duplicate samples of bivalves (50 mussels or 30 oysters) are composited from

three stations per sampling site. Duplicate sediment samples, each 150 g

composites from three stations per site, are obtained using a teflon coated

scoop from the grab sampler. The fish tissue, bivalve, and sediment samples are sealed in teflon bags, frozen, and shipped to NBS for storage at -120 °C. As

part of the NS&T specimen banking effort, samples from 12 Benthic Surveillance

sites and 30 Mussel Watch sites, collected during the past year, were stored in

the NBS Specimen Bank Facility. Samples from a similar number of sites from

each project will be added to the bank throughout the NS&T Program. Selected

sediment and bivalve samples have been homogenized and analyzed for the

determination of both inorganic and organic pollutants. The results of these

analyses will be used to provide baseline values for stability evaluation and

for comparison with data from other laboratories involved in analyses for the

NS&T Program.

Also in support of the NOAA NS&T Program, CAC organized a Quality

Assurance Workshop for the various NOAA laboratories and contractors involved

in the program. At this workshop the analytical methodologies to be used in

the NS&T Program and results from the analysis of NOAA intercalibration samples

were discussed in detail. NOAA has requested that NBS organize these workshops

on an annual basis as part of the NS&T quality assurance program.

Ill
The incorporation of the NOAA specimen banking project into the existing

EPA/NBS Environmental Specimen Bank Program provides the necessary support for

research and development of banking procedures for marine specimens as originally intended in the pilot program. In addition, the NOAA specimen banking

activity provides an excellent model for the role of specimen banking as part

of all national biomonitoring programs.

23 . Determination of PAH. PCBs . and Chlorinated Pesticides in Marine Tissue

and Sediment Samples

S.N. Chesler, M.M. Schantz, and S.A. Wise

As part of NOAA's National Status and Trends (NS&T) Program, surficial

sediment, bottom feeding fish, and bivalve molluscs are being collected from a number of sites around the United States yearly. Additional specimens are collected at selected sites for long-term storage in the Environmental Specimen

Bank Facility operated by NBS . From those specimens placed in long-term

storage, a subset of bivalve tissue and sediment samples has been homogenized

for inorganic and organic analysis. These analyses will provide baseline

values for the selected sites and will be compared with data from other NOAA

laboratories and contractors.

The organic contaminants of interest are polycyclic aromatic hydrocarbons

(PAH), polychlorinated biphenyls (PCBs), and chlorinated pesticides. Methods

have been developed in this laboratory utilizing liquid chromatographic

fractionation to isolate the three fractions, PAH, PCBs, or more polar pesticides, respectively, from the Soxhlet extracts. In the case of sediment

analysis, a silica microfractionation column and an aminosilane liquid chromatographic column are utilized for isolation of the desired fractions; for

tissue analysis, a gel permeation column followed by the aminosilane liquid

chromatographic column are utilized. The final analyses are done by gas

chromatography using the appropriate detector, either flame ionization or electron capture. An internal standard method is used for quantification, and

concentrations are reported on a dry weight basis. The liquid chromatographic

fractionation method utilized is less time-consuming and requires less exposure

of the sample to the atmosphere than conventional column chromatographic

fractionation methods.

An intercalibration sediment sample provided by NOAA as part of the

Quality Assurance Program for NS&T and six sediment samples from the NS&T

Specimen Bank have been analyzed using this methodology. Concentrations of

selected PAH in the intercalibration sample range from 0.5 to 3.9 ng/g dry

sediment, and those of selected PCBs and chlorinated pesticides range from

below the minimum detection limit (< 0.2 ng/g dry sediment) to 127 ng/g dry

sediment. These concentrations are in good agreement with values obtained by

NOAA's National Marine Fisheries Laboratory using a different clean-up

procedure. The six Specimen Bank samples analyzed were collected from the

Chesapeake Bay, MD; Mississippi River Delta, LA; Corpus Christi, TX; Dana

Point, CA; Nisqually Beach, WA; and Elliott Bay, WA. For these sediment

samples, PAH concentrations ranged from below the minimum detection limit

(<0.02 Mg/g dry sediment) to 5.3 /ig/g dry sediment while the PCB and

chlorinated pesticide concentrations ranged from below the minimum detection

limit to 58 ng/g dry sediment.

An intercalibration mussel sample and six bivalve samples stored in the

NS&T Specimen Bank have been homogenized and will be analyzed this year. The

112
bivalve samples were collected from San Diego, CA; Galveston Bay, TX; Fort

Johnson, SC; Dorchester Bay, MA; Pascagoula Bay, FL; and Baltimore Harbor, MD.

In the future, additional sediment and bivalve samples will be analyzed as well

as fish liver and possibly fish tissue samples.

24 . Reference Laboratory Activities Associated with the National Cancer

Institute Cancer Chemonrevention Programs

W.E. Hay, R.C. Paule, and R. Schaffer

For the past two years the Center for Analytical Chemistry has been

operating a quality assurance program for laboratories that measure serum and

plasma concentrations of ascorbic acid (vitamin C) , beta-carotene, retinol

(vitamin A), selenium, alpha- tocopherol (vitamin E) , and zinc. The Division of

Cancer Prevention and Control of the National Cancer Institute (NCI) asked NBS

to organize the program in order to ensure the long-term reliability of

measurements being made in conjunction with several NCI-supported investigations of the possible cancer-prevention benefits of these micronutrients in

populations of humans at high risk for certain forms of cancer. In addition to

the NCI-sponsored laboratories, other laboratories that analyze for these

substances for other medical reasons were invited to join the program; this

allowed us to have results from 10 to 20 laboratories per analyte. The serum

concentrations of these nutrients are typically below 1 mg/L for beta-carotene,

retinol, and selenium; about 1 mg/L for zinc; and about 10 mg/L for ascorbic

acid and alpha- tocopherol . Each laboratory used methods that they routinely

employ for analysis of the round-robin samples.

For the organic micronutrients, almost all laboratories use high-performance liquid chromatography (HPLC) with UV-visible detection, but

methodologic details vary among the laboratories. Their methods differed also

from those of NBS. For ascorbic acid, we use ion-exchange HPLC with isocratic

elution and UV-VIS and electrochemical detection. For the fat-soluble

vitamins, we use C-18 reverse-phase HPLC with gradient elution and both

wavelength-programmed UV and electrochemical detection.

For selenium, the various laboratories use four different atomic

absorption methods and an isotope dilution mass spectrometric method. Two

atomic absorption methods are being used for zinc. We use atomic absorption

methods for both analytes.

Overall laboratory proficiency for these analyses is shown from our statistical analysis on the most recently obtained interlaboratory test

results. After removing outliers, the NBS and the laboratory grand means for

individual samples were generally within 5%. The values calculated for the

percent coefficient of variation of a single measurement made by a single

laboratory ranged from 12-28% for the organics, 17-27% for selenium, and 7-12%

for zinc. (This coefficient of variation equals 100 S x/x where x is the grand

mean and S x

is the square root of the sum of the within and between components

of variance.) These relative imprecision values are large partly because of our practice of retaining as much laboratory data as possible for statistical

analysis. In general, a result had to be more than 60% lower or 100% higher

than the grand mean of all laboratory measurements to be excluded as an outlier. Even with these wide selection limits and depending on the analyte,

we classified from zero to 20% of laboratory results for the different samples

as outliers.

113
We are also serving as a referenbe laboratory for a collaborative

epidemiologic research study being carried out by the Epidemiology and

Biostatistics Program of the National Cancer Institute for evaluating the

effects of ionizing radiation on cancer risk among atomic bomb survivors in

Hiroshima and Nagasaki. One component of the study involves determinations of

serum nutrient levels (beta-carotene, retinol, selenium, alpha- tocopherol , and

zinc) in persons exposed to high or low doses of radiation, who had donated

blood in the 1970 's and subsequently developed cancer. The serum from approximately 600 donors is to be assayed in two laboratories in Japan, one for the

metals, another for the vitamins. We are to determine both the vitamins and

metals in split samples from a random selection of the donor sera.

To obtain preliminary information concerning the quality of the data that

might be forthcoming, the Japanese laboratories were sent samples that had been

analyzed previously by NBS and other U.S. NCI laboratories. Results have been

received thus far only for the vitamins. From the biases in these results and

a description of the methodology employed, we recognized that the Japanese

laboratory was using a vitamin analysis method which our recent investigation

has been shown to be subject to non-reproducible 40-50% biases. This method

was published by one of the laboratories in our quality assurance program.

After consulting with NBS personnel the source of error was discovered, and its use has been abandoned in that laboratory. The negative information on that

method is now being submitted for publication.

We have been informed that neutron activation analysis will be used for

the metal analyses run in Japan. Both NBS and the Japanese laboratory

responsible for metals analyses are. analyzing a pooled serum sample by atomic

absorption spectroscopy and neutron activation analysis, and (with the cooperation of a USDA lab) also getting results by isotope dilution mass spectrometry, to ensure that results for the metals are not method/technique

specific

25 . International Round Robin Study on the Determination of PAH and Nitro-PAH

in Environmental Samples

B.A. Benner, L.R. Hilpert, W.A. MacCrehan, W.E. May, and S.A. Wise

Development of new analytical techniques and the refinement of established

techniques continues at a rapid pace in analytical laboratories throughout the

world. A challenging problem in analytical chemistry is the accurate determination of individual organic species in complex mixtures such as diesel and

air particulate extracts. An effective means to gauge the variability among

the diverse analytical techniques used is through interlaboratory comparisons

of analyses of complex mixtures.

During the past year, we have conducted an international interlaboratory

comparison study, sponsored in part by the Coordinating Research Council and

the Department of Energy, on the determination of PAH and nitro-PAH in three

complex environmental samples: a diesel particulate extract, an urban air

particulate extract, and a solid diesel particulate sample. The air particulate and diesel particulate extracts were obtained from SRMs 1648 and 1650,

respectively. Samples were distributed throughout the world to laboratories

involved in the measurement of PAH and nitro-PAH. The laboratories were requested to use analytical techniques of their choice to determine PAH and

nitro-PAH. Laboratories were asked to determine only those compounds which

they routinely measure so that a realistic assessment of the state-of-the-art

114
for environmental analysis might be obtained. However, all laboratories were

asked to measure a core set of compounds consisting of phenanthrene

fluoranthene, benz [a] anthracene , benzo[ a] pyrene, benzo [ ghi ] perylene , and 1-

nitropyrene. The selection of this core group of compounds was necessary to

ensure that we obtained sufficient data on a minimum number of analytes to form

a valid data base for statistical comparison.

Data were received from 29 laboratories including NBS . The participating

laboratories were from the following countries: the United States (12), Europe

(Sweden, Norway, Germany, France, and Italy) (9), Japan (5), Canada (2), and

Australia (1). These laboratories used the following analytical techniques for

the PAH measurements: reverse-phase liquid chromatography with fluorescence

detection (10 labs), liquid chromatography with diode array UV detection [1

lab], capillary gas chromatography (GC) [10 labs], Gas chromatography-mass

spectrometry (GC-MS) [9 labs], thin-layer chromatography (TLC) [2 labs], and

direct fluorescence measurements without chromatographic separations [2 labs]

At NBS we used two techniques for the determination of the PAHs : [1] reverse- phase LC with fluorescence detection and [2] GC-MS. Three techniques were used

at NBS for the determination of nitro-PAH: [1] reverse-phase LC with fluorescence detection after on-line reduction of the nitro-PAH to the corresponding

amino PAH, [2] GC-MS, and [3] reverse -phase LC with reductive electrochemical

detection. The other participating laboratories used similar LC and GC-MS

techniques for their nitro-PAH determinations.

The evaluation of the data from all of the laboratories is in progress to

assess the state of the art for these determinations. In addition, this study

will provide information on differences among the various analytical techniques

used routinely for making these measurements.

26 . Construction of a New Sample Preparation Laboratory

S.N. Chesler and R.M. Parris

A new Sample Preparation Laboratory has been constructed in Modules B105-

107 of the Chemistry Building. This facility replaces the non- functional and

outmoded walk-in coldroom and an area used by the Mass Spectrometry Group. The

old sample preparation area A- 106 will now be used as a general purpose

laboratory by the Mass Spectrometry Group.

The new laboratory was designed to accommodate three operations:

glassware cleaning and storage, sample storage, and sample preparation. Since

the laboratory will be used for general trace organic analysis, special care was taken in choosing the laboratory accouterments. The flooring is a continuously welded polyvinyl chloride material which is solvent resistant and

nonporous so that any spills can be completely removed by solvent washing. The

bench tops are made from a solid epoxy-resin substance and is non-contaminating

and nonporous. The walls and ceiling are coated with a highly reflective epoxy

based paint which, like the floor, can be easily decontaminated. Two allstainless steel fume hoods are also provided as vented work areas.

The laboratory is equipped with a 7 cubic foot forced air oven that can operate above 500 °C. At these temperatures all measurable organic contaminants are removed by oxidation and/or vaporization. We have shown that no traces of PCBs (< 50 pg/g) remain on glassware that had been contaminated with

Aroclor 1260 just prior to the thermal cleaning operation. Prior to the

thermal cleaning, all glassware will be detergent washed and rinsed with

115
distilled water to avoid obvious contamination to the oven interior. The

heating cycle is 22 hours with an 18 -hour thermal soak at 500 °C.

The laboratory has a total of 75 cubic feet of low- temperature sample

storage, although long-term storage of samples in the laboratory is not contemplated. This includes a 4 °C refrigerator, two -20 °C freezers and a -76 °C

ultracold freezer. These storage areas are also used to keep small amounts of

chemical standards and solutions currently in use. All the cold storage is

alarmed such that appropriate personnel are alerted in case of a refrigeration

failure

The central bench area of the new laboratory has space for 14 Soxhlet

extractors and three preparative single pump liquid chromatographs. In this

area initial extraction and then extract purification takes place. Six

additional Soxhlet extractors can be placed in the fume hood for use with very

toxic extractants or samples, such as benzene or diesel particulate material.

Benchspace on the sides of the laboratory is provided for a rotary evaporator,

laboratory centrifuge, a large-scale Soxhlet extractor, a ultrasonic bath and

various stirrers and agitators. A stone weighing table in the corner of the

laboratory provides a location for an analytical micro-balance and a highcapacity balance. A special records -keeping area is located in an alcove above

which shelf space is available for storage of reference texts, laboratory

notebooks, etc. A large, high-capacity shelf is located above the refrigerated

storage area and will be used to store sampling equipment, high-capacity

metallic containers and shipping materials.

116
C. Outputs and Interactions

(Organic Analytical Research Division)

1 . Publications

Byrd, G. D., Fatiadi, A. J., Simons, D. S., and White V, E. , Laser Desorption

Mass Spectrometry of Squaric Acid and its Salts, Org. Mass Spectrom. 21,

63-68 (1985).

Byrd, G. D., Sniegoski, L. T., and White V, E. , Development of a Confirmatory

Chemical Test for Exposure to 3-Quinuclidinyl Benzilate (BZ) , Phase I,

Report to U. S. Army Medical Bioengineering R&D Laboratory (1985).

Christensen, R. G. and White V, E. , Determination of Dibenzothiophene in Oils

by Liquid Chromatography -Tandem Mass Spectrometry, J. Chromatogr. 323 . 33-

36 (1985).

Christensen, R. G., On-Line Multidimensional Chromatography Using

Supercritical Carbon Dioxide, HRR CC J. High Resolut. Chromatogr. Commun.

8, 824-828 (1985).

Fletcher, R. A. and Fatiadi, A. J., Laser Ionization Mass Spectrometry of

Poly (4-Vinylpridine) , Polymer Commun. 26,, 270-272 (1985).

Glinka, C. J., Sander, L. C., Wise, S. A., Hunnicutt, M. L. , and Lochmuller, C. H. , Determination of Pore Accessibility in Silica Microparticles by Small

Angle Neutron Scattering, Anal. Chem. 5_7 , 2079-2084 (1985).

Hartmann, A. E., Naito, H. K. , Burnett, R. W. , and Welch, M. J., Accuracy of

Participant Results Utilized as Target Values in the CAP Chemistry Survey

Program, Archives of Pathology and Laboratory Medicine, 109 . 1068-1071

(1985).

Reeder, D. J., Standards for Forensic Electrophoresis, Proceedings of the

International Symposium on the Forensic Applications of Electrophoresis . June 20-28, 1984, Forensic Science Research and Training Center, FBI

Academy, Quantico, VA (1985).

Wise, S. A., Chesler, S. N., Hilpert, L. R., May, W. E., Rebbert, R. E., Vogt,

C. R., Nishioka, M. G., Austin, A., and Lewtas , J., Quantification ofPolycyc'lic Aromatic Hydrocarbons and Nitro-Substituted Polycyclic Aromatic

Hydrocarbons and Mutagenicity Testing for the Characterization of Ambient

Air Particulate Matter, Environmental International 11 . 147-160 (1985).

Wise, S. A. and Zeisler, R. , Eds., International Review of Environmental

Specimen Banking . NBS SP 706, U. S. Government Printing Office,

Washington, D. C. (1985).

Byrd, G. D. , Sniegoski, L. T. , and White V, E. , Development of a Confirmatory

Chemical Test for Exposure to 3 -Quinucl idinyl Benzilate (BZ) , Phase II,

Report to U. S. Army Medical Bioengineering R&D Laboratory (1986).

Collins, J. C., Kiss, K., Pereles , D. J., and White V, E., Photodissociation of

Chlorostyrene Molecular Ions, Org Mass Spectrom. 21 . 447-448 (1986).

117
Fatiadi, A. J., New Applications of Tetracyanoethylene in Organic Chemistry,

Synthesis 1986 . 249-284 (1986).

Guenther, F. R. , Parris, R. M. , and Chesler, S. N. , The Determination of

Individual Organic Compounds in Complex Mixtures, Proceedings of the

Seventh International Symposium on Capillary Chromatography, D. Ishii, K. Jinno, and P. Sandra, Ed., The University of Nagoya Press, 298-308,

(1986).

Lauenstein, G. G., Schantz , M. M. , Wise, S. A., and Zeisler, R. , Specimen

Banking in the National Status and Trends Program: Development of

Protocols and First Year Results, Proc . Oceans 86 Conference, Washington,

D. C. , Sept. 22-26, 1986.

Lee, M. L. , Goates , S. R. , Markides , K. E., and Wise, S. A., Frontiers in

Analytical Techniques for Polycyclic Aromatic Compounds, in Polynuclear

Aromatic Hydrocarbons: Chemistry. Characterization, and Carcinogenesis , M. Cooke and A. J. Dennis, Eds., Battelle Press, Columbus, OH, 13-36

(1986) .

Reeder, D. J. (Ed.), Proceedings of the 1986 Meeting of the Americas Branch of

the Electrophoresis Society, NBSIR-3345 (1986).

Sander, L. C., Glinka, C. J., and Wise, S. A., Recent Advances in the

Characterization of Bonded Phases, in Chemically Modified Surfaces

Silanes, Surfaces and Interfaces . D. E. Leyden, Ed., Gordon and Breach

Science Publishers, 431-445 (1986).

Sander, L. C. and Wise, S. A., Investigations of Selectivity in RPLC of

Polycyclic Aromatic Hydrocarbons, in Advances in Chromatography 25 . J. Calvin Giddings, E. Grushka, J. Cazes, and P. R. Brown, Eds., Marcel

Dekker, Inc., New York, 139-218 (1986).

Welch, M. J., Sams, R. , and White, E., Photodissociation of Ions Generated by

Soft Ionization Techniques, Analytical Chemistry 58,, 890-894 (1986).

Welch, M. J., Cohen, A., Hertz, H. S., K. J., Schaffer, R. , Vanderlijn, P., and

White V, E., Determination of Serum Creatinine by Isotope Dilution Mass

Spectro Analytical Chemistry, Analytical Chemistry 58,, 1681-1685 (1986).

West, W. R. , Wise, S. A., Campbell, R. M., Bartle , K. D., and Lee, M. L. , The

Analysis of Polycyclic Aromatic Hydrocarbon Minerals Curtisite and

Idrialite by High Resolution Gas and Liquid Chromatographic Techniques, in

Polynuclear Aromatic Hydrocarbons: Chemistry. Characterization and

Carcinogenesis . M. Cooke and A. J. Dennis, Eds., Battelle Press, Columbus,

OH, 995-1009 (1986).

West, W. R. , Smith, P. A., Booth, G. M., Wise, S. A., and Lee, M. L , Determination of Genotoxic Polycylic Aromatic Hydrocarbons in a Sediment

from the Black River, Arch. Environ. Contam. Toxicol. 15,, 241-249 (1986).

Wise, S. A. , Campbell, R. M. , West, W. R. , Lee, M. L. , and Bartle, K. D. , Characterization of Polycyclic Aromatic Hydrocarbon Minerals Curtisite,

Idrialite and Pendletonite Using High-Performance Liquid Chromatography,

Gas Chromatography, Mass Spectrometry and Nuclear Magnetic Resonance

Spectroscopy, Chemical Geology 54, 339-357 (1986).

118
Wise, S. A., Sander, L. C., and May, W. E, , Investigations of Selectivity in

Reversed-phase Liquid Chromatography on Chemically Bonded C^g Phases, in

Chemically Modified Surfaces Silane. Surfaces and Interfaces , D. E. Leyden, Ed., Gordon and Breach Science Publishers, 349-369 (1986).

Cohen, A., Hertz, H. S., Schaffer, R. , Welch, M. J., and White V E. , Synthesis

of 2 -Amino- 1, 5 -Dihydro- 1- (Me thyl- 13 C) -4H-Imidazol-4-0ne-5- 13 C (Creatinine

2^2 ) , Journal of Labelled Compound Radiopharmacology, in press.

Coxon, B., Complete Assignment of the 13 C NMR Spectra of the Ring Forms of

Digitoxose by DEPT Spectrum Editing and Two-Dimensional CH Chemical Shift

Correlation Spectroscopy, in press.

Coxon, B. , Optical Rotation, Physico-Chemical Properties (IUPAC) , in press.

Domalski, E. S., Churney, K. L. , Ledford, Jr., A. E. , Bruce, S. S., Buckley, T.

J., Parris, R. M. , and Chesler, S. N. , Monitoring the Fate of Chlorine

from MSW Sampling through Combustion, Proceedings of EPRI Municipal Solid

Waste as a Utility Fuel Seminar (Nov. 20-22, 1985, Madison, Wisconsin), in

press

Domalski, E. S., Churney, K. L. , Ledford, Jr., A. E., Bruce, S. S., Buckley, T. J., Parris, R. M. , and Chesler, S. N. , Monitoring the Fate of Chlorine

from MSW Sampling through Combustion, Part II: Combustion Studies,

Chemosphere . in press.

Ellerbe, P., Development of Definitive Methods for Human Serum Analytes - A

Progress Report from the CAP NBS Research Associate, Pathologist, in

press

Espinosa-Leniz , R. and White V, E., Silver Sulfonates: A Novel Calibration

Material for Field Desorption Mass Spectrometry, Biomedical Mass

Spectroscopy . in press.

Foley, J. P. and May, W. E., Optimization of Secondary Chemical Equilibria in

Liquid Chromatography (SCE-LC) : Variables Influencing the SelfSelectivity, Retention, and Efficiency in Acid-Base Systems, Anal , Chem

. in press

Foley, J. P. and May, W. E., Optimization of Secondary Chemical Equilibria in

Liquid Chromatography: Theory and Verification, Anal . Chem

. in press.

Guenther, F. R. , Chesler, S. N., and Parris, R. M., Analysis of Nitrogen

Heterocycles in Shale Oil by a Dual Capillary Column Heart Cutting

Technique, J . Chromatogr . . in press.

MacCrehan, W. A. and Brown-Thomas , Determination of Phenols in Petroleum Crude

Oils Using LCEC, Anal . Chem

. in press.

Margolis, S. A. and Black, I., The Stabilization of Ascorbic Acid and Its

Measurement in Non-fat Dry Milk, J. Offic, Anal, Chem, . in press.

Margolis, S. A. and Coxon, B. C., Identification and Quantitation of the

Impurities in Sodium Pyruvate, Anal , Chem

. in press.

119
May, W. E. , Schaffer, R. , and Paule , R. C., Establishment of a Quality

Assurance Program for the National Cancer Institute's Chemioprevention

Program, Journal of the Cancer Institute, in press.

Reeder, D. J., Development of Standards for Electrophoresis and Electrofocus - ing, ACS Symposium Series: New Directions in Electrophoretic Methods . Jorgenson, J. and Phillips, M. (Eds.), in press.,

Reeder, D. J., Hancock, D. K. , Edwards, J. J., and Richie, K. L. , Electrophoresis Society Meeting Hosted at NBS , NBS J. Res. (Conf. Report), in press.

Schantz, M. M. and Chesler, S. N., A Supercritical Extraction Procedure for

the Removal of Trace Organic Species From Solid Samples, J. Chromatogr.,

in press.

Syty, A., Christensen, R„ G., and Rains, T. C., Trace Determination of Cr (III)

and Cr (VI) by LC/AAS with On-Line Preconcentration, Atomic Spectroscopy , in press

Wise, S. A., Benner, B. A., Chesler, S. N., Hilpert, L. R. , May, W. E., and

Vogt, C. R, , Characterization of the Polycyclic Aromatic Hydrocarbons

from Two Standard Reference Material Air Particulate Sample, Analytical

Chemistry, in press.

Yap, W. T. and Durst, R. A. , A Finite Elements Digital Simulation of

Chronoamperometry with Polymer-Modified Electrodes, J. Electronal. Chem.,

in press

Byrd, G. D., Richie, K. L. , Sniegoski, L. T., and White V, E. Direct

Calibration of GC/MS Systems Using- SRM Gas Cylinders, NBSIR, in press.

Chesler, S. N., Rebbert, R. E. , and Enagonio , D. P., Examination of the AAMI

ETO Residues Recommended Practice and a Determination of ETO Kinetics in

Water, Report to FDA, in press.

2 . Talks

W. E. May, "Analytical Methods and Standards for the Determination of Trace

Organic Species in Complex Mixtures," Department of Chemistry, South

Carolina State University, Orangeburg, SC, October 14, 1985. Invited

L. R. Hilpert, "The Analytical Methods for the Certification of a Diesel

Particulate SRM," Coordinating Research Council, CAPE-30 Project Meeting,

University of Nebraska, Lincoln, NE , October 15, 1985. Invited

W. E. May, "Standard Reference Materials and their Uses in the Determination of

PAH and Related Compounds in Complex Mixtures," Tenth Anniversary of the

Internatinal Symposium on Polynuclear Aromatic Hydrocarbons," Columbus,

OH, October 21, 1985.

B. Coxon, "Software for Two-Dimensional NMR Spectrum Editing," Bruker NMR

Users' Conference, Nashua, NH , October 30, 1985.

B. Coxon, "Two-Dimensional NMR spectrum Editing of Carbohydrates," Department

of Pharmacology and Experimental Therapeutics, The Johns Hopkins

University School of Medicine, Baltimore, MD , November 8, 1985.

120
S. A. Wise, "The Environmental Specimen Bank Program at NBS , " Belgian Embassy,

Washington, DC, November 8, 1985. Invited

P. Ellerbe , "Six-Month Progress Report on the Activities of the CAP Research

Associate," College of American Pathologists; Standards Committee,

Scottsdale, AZ, January 14, 1986. Invited

B. Coxon, "One-and Two-Dimensional NMR Spectrum Editing," Department of

Chemistry, American University, Washington, DC, February 7, 1986.

A. L. Plant, "Collisional Quenching of Zanthene Dyes Applied to Study the

Mechanisms of Complement-Mediated Lysis of Lipid Vesicles," Biophysical

Society, 30th Annual Meeting, Brooks Hall, San Francisco, CA,

February 10, 1986.

S. A. Wise, "Selectivity in Reversed- Phase Liquid Chromatography," Analytical

Chemistry Division Seminar, The Pennsylvania State University, State

College, PA, Feb. 14, 1986. Invited

W. A. MacCrehan, "Liquid Chromatography with Electrochemical Detection," Food

and Drug Administration, Washington, DC, February 28, 1986. Invited

D. J. Reeder, "Electrophoresis in an Analytical Laboratory Setting," Chemistry

Department, University of Maryland, College Park, MD, February 28, 1986.

Invited

W. A. MacCrehan and E. Schonberger, "Detection of Retinol and Its Impurities

Using LC/UV, EC," Pittsburgh Conference, Atlantic City, NJ

March 12, 1986.

W. A. MacCrehan and E. Schonberger, "Determination of Fat Soluble Vitamins in

Serum Using LCEC , " Pittsburgh Conference, Atlantic City, NJ

March 12, 1986.

G. D. Byrd, "Calibration of GC/MS Instrumentation for the Analysis of Volatile

Organics Using Cryogenic Trapping," Pittsburgh Conference, Atlantic City,

NJ, March 12, 1986.

K. L. Richie, "Results of an Interlaboratory Round Robin Using Isoelectric

Focusing to Assess Reproducibility of Rehydratable , " 1986 Meeting of the

American Branch of the Electrophoresis Society, Holiday Inn, Gaithersburg,

MD, March 26, 1986.

R. Schaffer, "NBS Definitive Method for Cholesterol," Laboratory

Standardization, National Cholesterol Education Program, National Heart,

Lung and Blood Institute, National Institutes of Health, Bethesda, MD

April 7, 1986. Invited

R. G. Christensen, "Preconcentration and Determination of Trace Cr(VI) by

LC/AAS , " Chromexpo- 1986 , Rockville, MD , April 10, 1986.

S. A. Wise, "The Need for Environmental Specimen Banking," Commission on Life

Sciences, Board on Environmental Studies and Toxicology, Committee on Biological Markers, National Academy of Science, Washington, DC,

May 8, 1986. Invited

121
F. R. Guenther, "The Determinatin of Individual Organic Compounds in Complex

Mixtures," Seventh International Symposium on Capillary Chromatography,"

Nagara, Gifu, Japan, May 11, 1986.

J. Brown- Thomas , "Liquid Chromatography," Montgomery Public School's Science

Conference, Wooton High School, Rockville, MD , May 17, 1986. Invited

S. A. Wise, "Determination of Dibenzopyrenes and Dibenzofluoranthenes by Liquid

Chromatography," Tenth International Symposium on Column Liquid

Chromatography, San Francisco, CA, May 18-23, 1986.

L. C. Sander, "Characterization of Bonded Phase Sorbents by Small -Angle Neutron

Scattering," Tenth International Symposium on Column Liquid

Chromatography, San Francisco, CA, May 18-23, 1986.

L. R. Hilpert, "Determination of PAH and Alkylated- PAH in Particulate Extracts

Using Negative Ion Chemical Ionization Mass Spectrometry," 34th Annual

Conference on Mass Spectrometry and Allied Topics, Hyatt Regency,

Cincinnati, OH, June 10, 1986.

M. J. Welch, "Photodissociation of Negative Ions Generated by LSIM," 34th

Annual Conference on Mass Spectrometry and Allied Topics, Hyatt Regency,

Cincinnati, OH, June 10, 1986.

P. Ellerbe, "Development of a New Definitive Method for Uric Acid," 34th Annual

Conference on Mass Spectrometry and Allied Topics, Hyatt Regency,

Cincinnati, OH, June 10, 1986.

W. A. MacCrehan and E. Schonberger , "Determination of Fat Soluble Vitamins in

Serum Using LC with Absorbance and Electrochemical Detection,"

Electroanalysis na hEireann, Dublin, Ireland, June 10, 1986.

S. Meiselman, "Isotope Dilution Mass Spectrometry Utilizing Electric Deflection

Plate Switching," 34th Annual Conference, American Society for Mass

Spectrometry, Hyatt Regency Hotel, Cincinnati, OH, June 10, 1986.

G. D. Byrd, "Development of a Confirmatory Test for Exposure to 3-

Quinuclidinyl Benzilate (BZ)," 34th Annual Conference on Mass Spectrometry

and Allied Topics, Hyatt Regency Hotel, Cincinnati, OH, June 12, 1986.

W. A. MacCrehan and S. D. Yang, "A Catalytic Oxygen Scrubber Column for the

Reductive LCEC of Nitro-PAH in Diesel Soot," Electroanalysis na hEireann,

Dublin, Ireland, June 12, 1986.

W. E. May, "Establishment of Interlaboratory Comparability for Trace Organic

Environmental Measurements," 2nd Annual DOE Contractors Meeting on Health

& Environmental Effects of Complex Chemical Mixtures," Lake Lawn Lodge,

Delavan, WI , June 17, 1986. Invited

B. A. Benner, "Mobile Sources of Polycyclic Aromatic Hydrocarbons (PAH) and

Nitro-PAH: A Roadway Tunnel Study," Fifth Symposium on Environmental

Analytical Chemistry: Atmospheric Chemistry and Source Apportionment,

Provo, UT, June 18-20, 1986.

S. A. Margolis and B. Primack, "The Alkaline Rearrangement of NADP and the

Isolation of an Inhibitor of Oxidation and Reduction of NADP(H) by

122
Secondary Alcohol Dehydrogenase,” Gordon Conference on Enzymes and Coenzymes, Kimball Academy, Merraden, NH, July 30, 1986.

B. Coxon, "2D J (CH) -Resolved1

NMR Spectrum Editing of Carbohydrates," XIII The

International Carbohydrate Symposium, Cornell University, Ithaca, NY,

August 8, 1986.

S. A. Wise, "Determination of Dibenzopyrenes and Dibenzofluoranthenes by Liquid

Chromatography," ARCO Chemical Company, Newtown Square, PA, August 25,

1986. Invited

L. T. Sniegoski, "Development of a Confirmatory Chemical Test for Exposure to

3 -Quinyclidinyl Benzilate (BZ)," 20th Middle Atlantic Regional Meeting,

September 2-4, 1986.

D. J. Reeder, "A Chemometric Approach to Analysis of Protein Patterns from

Ultra-Thesis Isoelectric Focusing Gels," Fifth International Meeting of

The Electrophoresis Society, Conference Centre, Royal Borough of

Kensington and Chelsea Town Hall, London, England, September 11, 1986.

D. Shea and W. A. MacCrehan, "Role of Biogenic Thiols on the Solubility of

Sulfide Minerals," American Chemical Society Meeting, Anehiem, CA,

September 12, 1986.

3 . Committee Assignments

Willie E. May

Chairman, - Center for Analytical Chemistry Analytical Workshop Committee

Member, ASTM Committee D19 on Water; Committee E19 on Chromatography

Member, ACS Environmental Chemistry Division

Board of Directors, Washington Chromatography Discussion Group

Member, Coordinating Research Council-Air Pollution Research Advisory Board

Member, ICPAH Research Steering Committee

Board of Governers, International PAH Symposium

Member, NIH Minority Biomedical Instrumentation Review Board

Member, Food Irradiation Research Steering Committee

Bruce Coxon

Member, Committee E13 on Molecular Spectroscopy

Secretary, ASTM Committee E13.07 on Nuclear Magnetic Resonance,

Member, Program Committee 12th International Carbohydrate Symposium

Member, Program Committee 27th Experimental NMR Conference

Richard A. Durst

Member, ASTM Committee D19 on Water

Member, Board of Advisory Editors, Ion- Selective Electrode Reviews

Member, IUPAC Committee V on Analytical Chemistry; Subcommittee 5 on Electroanalytical Chemistry

Member, NCCLS Subcommittee on Electroanalytical Methods; Subcommittee on pH

and Blood Gases

Member, NBS Research Advisory Committee

Jesse J. Edwards

Member, ASTM Committee E48 on Biotechnology

123
Diane K. Hancock

Referee, U.S. National Committee on Sugar Analysis, Subcommittee 6 on Quartz Control Plates

Associate Referee, International Commission for Uniform Methods of Sugar

Analysis

Laurence R. Hilpert

Member, ASTM Committee D34 on Waste Disposal

Member, ASMS Environmental Committee

Dennis J. Reeder

Member, AACC Committee on Standards; Study Group on Total Serum Protein

Associate Member, IFCC Expert Panel on' Drug Effects in Clinical Chemistry

Member, NCCLS Subcommittee on Total Protein

Vice President, International Electrophoresis Society

Robert Schaffer

Member, NCCLS Area Committee for Clinical Chemistry

Member, NCCLS Area Committee on Evaluation Protocols

Subcommittee on Creatinine

Subcommittee on Theophylline

Member, Council for National Reference System in Clinical Chemistry

Delegate, Laboratory Standardization Panel of the National Cholesterol

Education Program

Michael J. Welch

Member, Standards Committee of the Americal Association of Clinical

Chemistry

Stephen A. Wise

Program Chairman, Washington Chromatography Discussion Group

4 . Other

a Seminars

September 13, 1985

January 7, 1986

February 3, 1986

March 17, 1986

March 19, 1986

Prof. Jarmila Janatova, University of Utah , "Biochemis

try of Complement . " (Division Sponsor: R. A Durst)

Barry Lavine , Pennsylvania State University, "Pattern

Recognition Studies of Complex Chromatographic Data

Matrices: Taxonomy Based on Chemical Constitution."

(Division Sponsor: S. A. Wise)

Carl Marrese, Bacharach Instruments, "Electrocatalysis

at Chemically-Modified Electrodes and Diffusion in BSA

Gel Coated Electrodes." (Division Sponsor: D. J. Reeder)

Harlan K. Jones, University of Utah, "Field Flow

Fractionation of Colloidal Particles." (Division

Sponsor: S. A. Wise)

Grace Picciolo, Food & Drug Administration, "Chemical

Biosensors as Medical Devices." (Division Sponsor:

R. A. Durst)

124
April 16, 1986 Deborah Winn, National Center for Health Statistics,

"Analytical Measurements and Quality Assurance Needs

for National Health and Nutrition Evaluation Survey

(NHANES-III) . " (Division Sponsor: W. E. May)

May 8, 1986 Louis E. Henderson, NCI-Frederick Cancer Research

Facility, "Separation of Proteins by Reversed Phase

HPLC . " (Division Sponsor: D. J. Reeder)

May 14, 1986 Maurice Verzele, State University of Ghent, Ghent,

Belgium, "Recent Advances in Liquid Chromatographic

Packing Materials." (Division Sponsor: S. A. Wise)

May 28, 1986 Beverly Packard, Johns Hopkins University, "Probing

Cellular Dynamics with Fluorescence Spectroscopy."

(Division Sponsor: A. Plant)

June 24, 1986 Neal Craft, USDA, "Analysis of Vitamins in Serum."

(Division Sponsor: R. Schaffer)

July 7, 1986 Joe P. Foley, Louisiana State University, "Systematic

Errors in Chromatographic Analyses." (Division

Sponsor: W. E. May)

July 11, 1986 Anders Colmsjo, University of Stockholm, Stockholm,

Sweden, "Liquid Chromatography and Low- Temperature

Fluorescence for the Determination of Organic

Compounds." (Division Sponsor: S. A. Wise)

July 23, 1986 Marcel Gonzalez, University of Pennsylvania,

Philadelphia, PA, "Role of the Carboxylate in Yeast

Inorganic Pyrophosphatase." (Division Sponsor: D. J.

Reeder)

August 12, 1986 Donald Atha, Beth Israel Hospital, Boston, MA

"Structure/Function of Heparin Binding to

Antithrombin." (Division Sponsor: D. J. Reeder)

August 19, 1986 Andrew Alpert , Columbia, MD , "Covalent Coatings on Silica for Chromatography and Immobilization of

Proteins and Peptides." (Division Sponsor: A. L. Plant)

August 25, 1986 Rebecca A. Cowling, "Chemical Modification of

Dihydropyrimidine Amidohydrolase . " (Division Sponsor:

D. J. Reeder)

August 29, 1986 Winfred Malone, NCI, "Analytical Needs to Support NCI

Cancer Chemo - Prevention Programs." (Division Sponsor:

W. E. May)

Conferences Sponsored

December 5&6 , 1985 W. E. May, NOAA/NBS Methods Development/Quality

Assurance Workshop

125
March 26-28, 1986 - D. J. Reeder, Electrophoresis Society Meeting

May 28-29, 1986 - W. E. May and R. Schaffer, 2nd NBS/NCI Micronutrient

Analysis Q.A. Workshop

c. SRM Activities

SRM 17D

SRM 41C

SRM 911B,

SRM 914A

SRM 927a,

SRM 1549,

SRM 1563,

SRM 1585,

SRM 1587,

SRM 1588,

SRM 1596,

SRM 1597,

SRM 1648,

SRM 1649,

SRM 1650,

SRM 1829,

SRM 1837,

SRM 1838,

SRM 1839,

SRM 1916A

Sucrose

D-Glucose (Dextrose)

Cholesterol

Creatinine

Bovine Serum Albumin

Non-Fat Dry Milk

Cholesterol and Fat Soluble Vitamins in Coconut Oil

Chlorinated Biphenyls in 2 , 2 , 4-Trimethylpentane (Isooctane)

NPAH in Methanol

Organics in Cod Liver Oil

Dinitropyrenes in Methylene Chloride

Complex Mixture of Polycyclic Aromatic Hydrocarbons from

Coal Tar

Urban Particulate. Matter

Urban Dust/Organics

Diesel Particulate Material

Alcohols in Reference Fuel

Methanol (9 volume percent) and t-Butanol (6 volume percent)

in Reference Fuel

Ethanol (10 volume percent) in Reference Fuel

Methanol (0.3 volume percent) in Reference Fuel

Bilirubin

126
IV. Gas and Particulate Science Division

Harry L. Rook, Chief

William D. Dorko , Deputy Chief

A. Division Overview

The Gas and Particulate Science Division conducts research to develop new

and improved techniques for the preparation and analysis of gases and microscopic regions of matter. These include research leading to (a) improved

measurements of gaseous species in the atmosphere and in specially prepared gas

mixtures, (b) new or improved methods of laser spectrometry for the analysis of

specific gaseous molecules, (c) new chemometric techniques for improved chemical measurements, (d) improved quantitative x-ray fluorescence analysis, (e)

improved analytical methods for quantitative electron, ion, and photon microanalysis, and (f) the preparation and certification of standards for measure- ment quality assurance in analytical chemistry. The Division responds to the

measurement and standards needs of other Federal agencies, industrial organizations, universities, and governments, both state and local. The research

efforts are conducted by the five groups which comprise the Division and are divided about equally between the two general areas of gas analytical chemistry

and microanalytical chemistry.

During the past year, research in gas measurement has been directed toward

developing new methods for trace and ultra- trace gas analysis and standards and

toward improving the accuracy of data produced by existing methodologies and

used in the certification of NBS SRMs . Research in gas analysis is carried out

in the Gas Metrology, Atmospheric Chemistry, and Laser Analytical Spectrometry

Groups of the Division. Their research plans and results are coordinated in

quarterly Group Leaders meetings devoted to research planning. Selected

highlights in gas measurement research follow.

Research in laser spectrometry continued to improve quantitative

spectroscopic measurements by both investigating better calibration techniques

and also by investigating potential problems inherent in the spectrometry

itself. Better calibration techniques were used for the quantitation of

absorption and pressure -broadening coefficients for N02 , which is an atmospheric gas of interest to a variety of agencies and industries. Traditionally, the determination of these coefficients has been accomplished by

using measured pressures of pure N02 in an absorption cell as the calibrant.

Systematically low absorption coefficients are likely to result because of the

loss of N02 , due to its reactive nature, and also because of the equilibrium

between N02 and N2 0 4

. These problems were eliminated by utilizing dynamically

generated dilute N02 standards employing permeation tubes which were specially

prepared in-house. The diluted standards eliminated the N2 0 4 as a molecular

species and the continual flushing of the cell, due to the dynamic nature of

the calibrant, eliminated the reactive losses due to wall contact. The concen- tration of the N02 in the calibration gas was determined by gravimetrically

determining the weight loss of the permeation tubes, by Fourier transform

infrared spectroscopy and by gas phase titration (in which 03

, NO and NO^ were measured). Using this approach, with the redundant verification of the

calibration concentration, absorption and pressure -broadening coefficients for over 26 different vibration- rotation lines of N02 in one of the most important

spectral regions of the infrared (the 1/3 band at 6.2 urn) were determined.

127
Significant progress has also been made in improving the photometric

accuracy of TDLAS measurements. Employing techniques, line fitting algorithms

and system improvements discussed in last year's report, a subtle, systematic

source of error has been identified. For quantitative purposes, many investigators correct determinations based upon peak absorbance measurements using

the increased absorption linewidth as a scaling factor. This is accurate as long as all of the causes of increased linewidth are recognized and included.

Our investigations have recently revealed a heretofore unreported source of

increased linewidth and this is from laser frequency jitter caused by mechanical shocks from the closed-cycle refrigerator compressor. To eliminate this

problem, a microprobe - triggering circuit has been completed which tracks the

motion of compressor piston and allows data to be taken only during the central

portion of the cycle.

Another atmospherically active and important molecule was also studied.

The stoichiometry of the gas phase titration reaction between NO and 03 to

produce N02 was reinvestigated using improved techniques for the generation and

analysis of the three components of interest. The results suggest that the

presently accepted value for the 03 absorption cross-section at 254 nm should

be lowered by 1 to 1.5% which is in agreement with results recently obtained by

university researchers employing a completely different technique.

Major accomplishments have continued in developing and evaluating

compressed gas standards with the analytes of interest in the low concentration

range . The analytes have ranged from toxic organic compounds to inorganic

gases which are precursors to acid rain. The gas cylinder mixture of 17

volatile toxic organic components, all at about 10 ppb , which was prepared last

year has been used by EPA/EMSL/RTP for calibrating GC/MS measurements of air

samples obtained from an accidental chemical emission in the vicinity of a major urban area. The cylinder was returned to NBS after several months and

subsequent reanalysis has shown that the contents have remained stable. This

is quite important, since this is the first time that a gas mixture, this

complex, and with components at such trace concentration levels has been

verified to be well characterized and stable. The other area of trace level

gas standards is for dry acid deposition measurements. Specially prepared

mixtures of both S02 in Air and NO in N2 at the 100 ppb level have been evaluated over a period of time and have shown excellent stability. A dynamic

dilution system to provide a 100 to 1 dilution has also been developed so that

these mixtures can be accurately diluted to provide standards at 1 ppb, which

is the level of analytical significance.

Other areas of activity include (1) an extensive evaluation of the errors associated with the gravimetric procedure used for the development of high

accuracy gaseous SRMs of carbon dioxide in air (300 to 400 ppm) for the global

monitoring of temporal changes in atmospheric carbon dioxide levels, (2) the

quantitative determination of the strengths of infrared absorption bands of

halocarbons F-ll and F-12 at stratospherically- relevant temperatures, (3)

initiation of the development of multicomponent gas standards for automotive

emission testing for EPA and State Inspection/Monitoring programs, and (4) the

analytical certification i:o restock 50-cylinder batches of about 20 gaseous

SRMs.

Chemometrics is a new area of research for the Division. A major

Competence Building proposal was developed this year and presented to the NBS

Director. This proposal will also be the planning guide for research during

the next five years, with the level of effort determined by funding and staff

128
which we can hire or commit to this area. Chemome tries employs advanced

mathematical statistical methods together with expert chemical knowledge for

the design and evaluation of complex, multicomponent chemical measurement

processes. Recent activities have emphasized detection limits, quality

assurance, multivariate analysis, and planning for an integrated chemometric

approach to the chemical measurement process. Fundamental and applied aspects

of the limit of detection in analytical chemistry was the subject of a two day

symposium organized by the group leader for the spring 1986 national meeting of

the ACS

Source apportionment of bulk atmospheric, carbonaceous particles and gases

has continued to be another major activity. The work, with collaboration with

groups within and outside the U.S., has focused on basic advances in the

measurement of natural levels of 1A C in trace levels of atmospheric carbon. A

microsample preparation system developed at NBS has made it possible to prepare

excellent targets for accelerator mass spectrometry (AMS) with less than 100 /ig

carbon in the original atmospheric sample. These 1

C measurements have been

used to discriminate CO and particles from woodburning and fossil fuel combustion, and also to estimate source contributions for polycyclic aromatic

hydrocarbons for the EPA's Integrated Air Cancer Program.

The basic mission of microanalysis research is to advance the development

and application of microbeam analysis techniques for the chemical, morphological, and crystallographic characterization of matter in the micrometer and

submicrometer spatial scales. Compositional mapping has continued to be a major theme for much of the work. A new method has been developed which makes

direct use of a spectrometer wavelength scan across a peak to provide the basis

for mathematically constructing a "standard map" for subsequent calculation of

the k-value map for the unknown. This procedure results in significant

benefits by eliminating the time required for acquiring the standard maps and

by improving the statistical quality of the data for the standard. The new

procedure should make compositional mapping more readily applicable to

practical problems.

In the area of mass spectrometry microanalysis, the automatic measurement

of isotopic ratios of arrays of discrete particles viewed in the ion microscope, a form of secondary ion mass spectrometry, has been accomplished. The

image processing software operates in digital images recorded by a TV camera which views the fluorescent screen of the ion microscope . The computer image

processor automatically recognizes particles, corrects for background, and

calculates isotopic ratios from a series of images taken at various masses.

Special efforts have been concentrated in the area of laser Raman microanalysis (LRM) as applied to biological problems. LRM represents one of the

most promising molecular microanalysis techniques for use in the area of

biotechnology

Research in x-ray fluorescence continues to focus on ways to improve

accuracy and sensitivity these measurements. A major accomplishment has been

the determination of the effects of different sources of mass absorption

coefficients in fundamental parameter computer programs on the results of

analysis. When coefficients from three commonly used compilations are used,

differences of 10% or greater are often found in the results for elements with

atomic numbers greater than 20 and energies in the 10 to 30 keV range. In an effort to increase sensitivity, the use of synchroton x-radiation has been

explored for the potential development of a reference method for the

129
certification of trace element SRMs . The use of highly intense, polarized and

monochromatic x-rays, tunable from 5 to 20 keV in total reflection geometry

makes elemental analysis possible down to ppb levels.

Future research in the Division includes a diverse range of interests.

Ion beam analysis by secondary ion microscopy will be extended to realize

complete three-dimensional compositional mapping which, in conjunction with the

Nuclear Analytical Methods Group, will hopefully develop into the first NBS ion

implant depth profiling SRM. In the area of molecular microanalysis by LAMMA,

a program will be implemented to examine pattern recognition techniques for

spectrum analysis. In the area of electron analysis, investigations into lowenergy microanalysis of solid specimens will be initiated. Application of

total reflection XRF using synchroton radiation will be oriented toward the

measurement of selenium in human serum.

Other research will include an investigation of sources of methane, carbon

monoxide, and elemental and organic carbon in atmospheric particles on an urban

to global scale, and also the investigation of trace carbonaceous particles

will be extended to the paleoatmosphere through recovery of particles from

polar and midlatitude ice cores. In the area of spectroscopy, investigations

to ferret out systematic errors in diode laser measurements will continue along

with the determination of absorption coefficients for reactive radicals such as H02

. Gas standards research will include the development of a dynamic HN03 generation system for sub-ppm levels, implementation of procedures by which EPA can calibrate a mobile TDLAS unit for N02

, finalization of the evaluation of

isotope dilution mass spectrometry as an absolute reference method for determining C02 at ambient concentrations, development of multicomponent toxic

organic cylinder standards for EPAs group four compounds at the ppb level, and

the evaluation of trace analysis protocols and standards to provide data

quality assurance in the analysis of gaseous mixtures for NASA's space shuttle

program

1 . Mi croanalvs is Group: Overview

The Microanalysis Research Group carries out research to advance the

development and application of microbeam analysis techniques for the chemical,

morphological, and crystallographic characterization of matter on the micrometer and sub-micrometer spatial scales. The analytical techniques utilized are based on primary excitation beams of electrons, ions, or photons, and secondary

analytical signals of x-rays, inelastically scattered electrons, inelastically

scattered photons, or ions. The techniques employed by Group members include

electron probe microanalysis. (EPMA) , scanning electron microscopy (SEM),

analytical electron microscopy (AEM) , electron energy loss spectrometry (EELS),

secondary ion mass spectrometry (SIMS) , laser microprobe mass analysis (LAMMA)

and laser Raman microanalysis (LRM)

Research is conducted on several aspects of each technique, including (1)

advancing understanding of the basic physics of sample excitation by the

primary radiation and of the propagation of the secondary radiation, (2)

developing methods of quantitation, (3-) producing standards and techniques as a means of disseminating developments, (4) applying results of the research to

developing improved compositional mapping techniques, and (5) the study of

specific analytical problems in aid of NBS and other government agency

activities as well as national scientific priorities.

130
During FY86 , the members of the Group have been active in research in each

of the major technical areas, including electron, ion, and photon beam

techniques, with the following progress in each area:

(1) Electron Beam Microanalvsis

Compositional mapping has continued to be a major theme for much of our

work. In electron probe microanalysis, the successful development of a compositional mapping technique for use with wavelength-dispersive x-ray

spectrometry, first described in FY85, has been significantly modified and

improved. A new method has been developed which makes direct use of a spectrometer wavelength scan across a peak to provide the basis for mathematically

constructing a "standard map" for subsequent calculation of the k-value map 'for

the unknown. This procedure results in significant benefits by eliminating the

time required for acquiring the standard maps and by improving the statistical

quality of the data for the standard, since the much smaller number of channels

needed for the peak scan allows longer counting time at each channel. The new procedure should make compositional mapping more readily applicable to

practical problems.

In scanning electron microscopy, the acquisition of a new high resolution

analytical scanning electron microscope has stimulated our research in both

imaging and analysis problems. The visibility of asbestos fibers as a function

of sample preparation technique and electron optical conditions has been

studied to aid in the development of test samples for the Environmental

Protection Agency.

In analytical electron microscopy, the advanced image processing system

for the AEM has undergone additional development. Rapid exchange of images has

been demonstrated between the VAX 11/730 computer which handles the instrument

automation and the VAX 11/780 computer, in which the image processor and the

higher level image processing algorithms reside. This computer network will

provide access to the sophisticated image processing techniques developed in

the LISP-based procedures on the VAX 11/780, including automatic control of the

beam position on the specimen based on the results of image processing. The

analytical capabilities of the AEM have been extended by the inclusion of an ultrathin window energy dispersive x-ray spectrometer, which allows measurement

of x-ray energies as low as 185 eV (B K x-rays) and a high purity germanium

energy dispersive x-ray spectrometer, which can measure x-rays with energies up

to 150 keV. These spectrometers provide access to the entire range of

characteristic x-rays, except for those of the very lightest elements.

( 2 ) Mass Spectrometry Microanalvsis

The automatic measurement of isotopic ratios of arrays of discrete

particles viewed in the ion microscope, a form of secondary ion mass spectrometry, has been accomplished. The image processing software operates on digital images recorded by a TV camera which views the fluorescent screen of

the ion microscope. The computer image processor automatically recognizes

particles, corrects for background, and calculates isotopic ratios from a series of images taken at various masses. The limits to the accuracy and

precision of measurements from a camera-based imaging system are being

evaluated

The data recording capability of the laser microprobe mass analyzer has

been greatly extended by the incorporation of a pair of digital transient

131
recorders with 32, kilobyte memory capacity, which allows recording at two

sensitivities of the complete mass spectrum from hydrogen to the actinides on every laser shot. Using the new data handling capability, a research program

has been installed to measure interelement effects on the quantitative analysis

of multi-element glasses in the form of films and particles.

(3) Molecular Microanalvsis

Studies of molecular microanalysis with the laser microprobe mass analyzer

have been extended to a study of carbonate compounds, under the impetus of

developing techniques for the chemical analysis of individual mineral

particles. The molecular species produced under laser ablation from various

compounds have been studied in detail to attempt to resolve certain

difficulties in reproducing results reported in the literature by other

workers. Results suggest that the formation of carbonate ion species in the

LAMMA spectrum is dependent on the cation present and the laser irradiation

conditions. Also, certain artifacts which arise from substrate contributions

to the spectrum have been recognized.

In the area of laser Raman microanalysis, progress has been made on applications of the technique to molecular microanalysis for biological

problems. LRM represents one of the most promising molecular microanalysis

techniques for application to biotechnology, so that special efforts have been

concentrated in this area.

Future Plans :

In the area of electron analysis, the digital imaging system will be

extended to include digitization of the conventional transmitted electron

images and diffraction patterns, which will greatly extend our analysis

capabilities. Image processing algorithms will be developed for direct

solution of electron diffraction patterns from the fundamental characteristics

of the pattern with minimal operator intervention. The electron energy loss

signal will also be utilized for compositional mapping images. Investigations

into low-energy microanalysis of solid specimens will be initiated.

Further advances in the development of quantitative EPMA are limited by

the existing data base of quantitative measurements on known standards and of

the fundamental parameters which are incorporated in the physical models of

electron beam specimen interactions. The limitations on the k-value data base

from standards will be addressed during the next year by initiating a project

involving a guest worker to make comprehensive measurements on the suite of

special standards which have bee developed within the Group in recent years.

During the past year, the Group has also investigated the feasibility of

developing an electron/x-ray optical bench which will permit the measurement of

fundamental parameters. Preliminary design work has been completed, and we plan to implement these designs in the next year to produce an initial

instrument

Ion beam analysis by secondary ion microscopy will be extended to

demonstrate quantitative analysis both laterally and in-depth to realize

complete three-dimensional compositional mapping. As part of this work, we plan to develop in conjunction with the Nuclear Analytical Methods Group the

first NBS ion implant depth profiling SRM. The camera-based digital imaging

system will be augmented to permit quantitative measurements over a much larger

dynamic signal range. The quantitative measurement of concentrations by

132
imaging methods is a high priority for development. An opportunity also exists

for collaborative work with the sub-micrometer scanning ion microprobe of Prof.

R. Levi-Setti at the University of Chicago. We will attempt to investigate the

utility of this instrument for isotopic analysis of sub-micrometer particles.

In laser microprobe mass spectrometry, a major limitation to the

quantitative use of the technique arises from the poor reproducibility of the

ion source (laser beam - specimen interaction) and the non-linear response of

the signal measurement process. A systematic effort is planned to study the

entire signal generation and processing chain. In addition, experiments to

investigate the possibility of separating the atom transport and the ionization

stages by use of two laser pulses separated in time will be carried out. In

the area of molecular microanalysis by LAMMA, a program has been implemented to

examine pattern recognition techniques for spectrum analysis. This program

includes the interfacing of the LAMMA data output to the VAX computer to

provide for the higher level of computation and mass storage required.

Dale E. Newbury, Group Leader; Adville A. Bell, David S. Bright, Peter H. Chi,

Edgar S. Etz, Robert A. Fletcher, Ryna B. Marinenko, Robert L. Myklebust,

Thomas R. Pereles, Patrick J. Sheridan, David S. Simons, John A. Small, Eric B. Steel, and Barbara B. Thorne.

2 . X-Rav Fluorescence Group: Overview

Improvement of the accuracy and sensitivity of x-ray fluorescence

spectrometry continue to be long term research goals of this group. The

accuracy of fundamental constants required in first principle calculations for

correction of matrix effects for quantitative analysis is of primary interest.

This year we examined three commonly used compilations of mass absorption

coefficients to determine any influences in the results of analysis which could

be ascribed to the different compilations. For improving analytical sensitivity via sample preconcentration, several approaches are being explored to

develop specific chelator membranes. We have investigated the potential of

using synchrotron x-radiation in so-called total reflection geometry for

ultratrace analysis and especially for application to certification analysis of

trace element SRMs . A major portion of our work continues to be the quantitative analysis and homogeneity testing of new and renewal SRMs and the

fabrication and characterization of new thin glass films for XRF calibration.

A major accomplishment during the past year has been the publication of a paper describing the effects of different sources of mass absorption coefficients in fundamental parameter (first principle) computer programs on the

results of analysis. One finds when comparing three commonly used compilations

that differences of 10% or larger are often found for elements with atomic

numbers greater than 20 and energies in the 10 to 30 keV range.

We are investigating a commercially available fluorocarbon polymer

membrane in addition to cellulose filter papers for attachment of specific

chelating ligands for sample preconcentration. An automated closed- system

apparatus has been constructed for performing the activation with subsequent

attachment of the chelating groups to the substrates.

In addition to the development of sample preconcentration techniques for

enhancing analytical sensitivity, the use of synchrotron x-radiation was explored for the first time by this group for the potential development of a reference method for the certification of trace element SRMs. The use of

133
highly intense, polarized, and monochromatic x-rays, tunable from 5 to 20 keV,

in total reflection geometry makes elemental analysis possible down to ppb

levels

Several Marine and NOAA samples were analyzed by XRF as part of an NBSNOAA Specimen Bank Project. In the National Status and Trends program, NOAA

(National Oceanic and Atmospheric Administration) monitors the levels of both

organic and inorganic pollutants in 50 coastal cities around the U.S. NBS banks

samples from twelve of these sites and performs quantitative analysis of

selected samples.

During the past year, several types of alloys were tested for homogeneity

and quantitatively analyzed. These include SRMs 1685B, 1686B, 1687B, 2631, and

2632. Proposed SRM 679 (Brick Clay) and SRM 88b (Dolomite) were also analyzed,

the results of which are used in the certification of these materials.

Future Plans

In the area of sample preconcentration, we expect to evaluate the

performance of prototype chelator membranes for trace analysis using typical

SRMs. Additional work on the application of total reflection XRF using

synchrotron radiation will be oriented towards the measurement of selenium in

human serum. The development of new thin films for XRF calibration will

include candidate thin samples for sulfur calibration. Finally, the testing of

homogeneity and analysis of materials for OSRM will continue.

Peter A. Pella, Group Leader; Anthony A. Marlow, John Sieber, Gerald Sleater,

and Wang Ziyao

3 . Atmospheric Chemistry Group: Overview

Research activities of the Atmospheric Chemistry Group are directed toward

a) the development of a program in Chemometrics which employs advanced mathematical statistical methods together with expert chemical knowledge for the

design and evaluation of complex, multicomponent chemical measurement processes, and b) the development of standard reference instruments and advanced

methods of measurement of atmospheric ozone and trace carbonaceous gases and

particles. Cooperative research activities with scientific institutions in

this country and abroad continue to focus on increasing our knowledge of trace

chemical perturbations of the atmospheric system by anthropogenic and natural

processes

The ozone calibration facility provided service during the past year to

industrial laboratories and to U.S. and Canadian government laboratories. The

EPA ozone monitoring network was augmented with the delivery of two additional

Standard Reference Ozone Photometers (SRP). Also, a stable ozone generator was developed for possible use as a secondary ozone standard. The sensitivity of

the ozone absorption cross section instrumentation is being increased to permit

measurements in the 400-600 nm range; a possible byproduct of this effort will

be an improvement in ozone SRP sensitivity to 0.06 ppb.

Chemometrics activities have emphasized detection limits, quality

assurance, multivariate microanalysis, and planning for an integrated chemometric approach to the chemical measurement process. Fundamental and applied

aspects of the limit of detection in analytical chemistry was the subject of a two day symposium organized by the group leader for the spring 1986 National

134
American Chemical Society (ACS) meeting. The substance of the symposium will

be published by the ACS in their symposium series early in 1987. Detection

limit concerns of the International Atomic Energy Agency (IAEA) in their

Intercomparison and Cooperative Research Programs were addressed via a Consultants' Meeting, called by the IAEA and chaired by the group leader. A document

resulting from the meeting will provide a unified approach for the evaluation

of detection limits for a variety of trace analysis methods utilized in IAEA

programs. Special attention is being given in this document to the confounding

effects of difficult chemical matrices and blanks.

This year's research has focused on the effective extraction of chemical

information from multidimensional signals in multicomponent systems. Initial

studies in this area are treating laser mass spectra of microscopic samples of

organic polymeric particles and a continuous multielement glass film. Factor

analytical techniques are being successfully applied to estimate the instrinsic

dimensionality (number of independent factors) and to select the mass fragments

carrying the greatest discriminating power. Applications of this work are anticipated in investigations of multicomponent microhomogeneity, interlaboratory trace analysis, and source apportionment of individual atmospheric

particles

Source apportionment of bulk atmospheric, carbonaceous particles and gases

has continued with important collaborative efforts with the EPA, Sandia

National Laboratory, the University of Arizona, and the Norwegian Institute for

Air Research. The work at Arizona, together with some cooperation also with

the . University of Pennsylvania, has focussed on basic advances in the measure- ment of natural levels of 14 C in trace levels of atmospheric carbon. A

microsample preparation system developed at NBS has made it possible to prepare

excellent targets for accelerator mass spectrometry (AMS) with less that 100 ng

carbon in the original atmospheric sample. Extremely efficient and clean

sample preparation techniques have been responsible for this success. Among

the 14 C measurements completed with this technique have been samples of

atmospheric methane and carbon monoxide, plus carbonaceous aerosols from

Norway, Alaska, New Mexico and North Carolina.

Most of the 14 C measurements concern the issue of urban pollution,

especially the discrimination of CO and particles from woodburning and fossil

fuel combustion. 14 C is probably the most reliable discriminating species for

this type of problem. As a result, it is being used to estimate directly the source contributions, and also to calibrate or validate indirect methods based

on patterns of trace elements or polycyclic aromatic hydrocarbons (PAH)

Investigation of the origins of elemental and organic carbon, including the

PAH, constitutes the major thrust of the cooperative research in the EPA's

Integrated Air Cancer Program.

Future plans for the Atmospheric Chemistry Group include: a) extension of

the Chemometrics effort toward the development of an integrated approach to the

chemical measurement process (CMP) including exploratory and expert systems

considerations for CMP design; this would be followed by iterative techniques

of method optimization and data evaluation, and application to selected

research problems in the Center; b) completion of the EPA ozone monitoring

network, with the delivery of the final two SRP's early in 1987; c) extension

of the sensitivity of the ozone SRP's, and exploring their applicability to

other atmospheric trace gases; d) investigation of sources of methane, carbon

monoxide, and elemental and organic carbon in atmospheric particles on an urban

to global scale, in parallel with the development of complementary isotopic

135
(

1

C , i4, C) and PAH pattern recognition. The investigation of trace

carbonaceous particles will be extended to the paleoatmosphere through recovery

of particles from polar and midlatitude ice cores, in a program which would

involve cooperation among a number of organizations, including NBS , the

National Science Foundation, and the University of Arizona.

Lloyd A. Currie, Group Leader, Arnold M. Bass, George A. Klouda, James E. Norris, Will Ollison, Ann E. Sheffield, T. Stafford, J. M. Sullivan, P. E. Hare

and V . Mohan

4 . Gas Metrology Research Group: Overview

The Gas Metrology Research Group conducts research on preparative and

analytical techniques for the development and quantitative assessment of trace

gas mixtures, investigates the measurement uncertainty associated with the

preparation and analysis of these mixtures, conducts evaluations to discern

their short and long term stability, and develops basic data to characterize

their fundamental spectral, chromatographic, and detection properties.

Preparative techniques used to develop primary standards for calibrating the

trace gas measurements include pressure -vacuum manifold systems, precise and

accurate gravimetry, dynamic dilution systems, and gas blending. Analytical

techniques include gas chromatography, mass spectrometry, non- dispersive

infrared analysis, chemiluminescence analysis, Fourier- transform infrared and

diode laser spectroscopy, and various analytical systems for the determination

of trace gaseous impurities.

This research is applied to a) the improvement of measurements for

ambient, trace, and ultra- trace gas analysis, and to b) the development of

accurate and stable single and multi -component standards for a wide variety of

inorganic gaseous and organic vapor mixtures ranging in concentration from the

percent to the part-per-billion (ppb) level. These standards are developed and

maintained as primary calibrants for national and state regulatory programs,

industrial, institutional, and federal measurements, international

collaborative programs, and global monitoring programs. The Group directly

responds to and interacts with gas measurement and standards needs of other

agencies, industrial organizations, and standards - setting bodies at the local,

state, and national levels. Utilizing its unique capabilities, the Group also

performs a limited number of gas analyses for external organizations.

During FY86 , Group research activities have included: (1) an extensive

evaluation of the errors associated with the gravimetric procedure used for the

development of high accuracy gaseous SRMs for global monitoring of atmospheric

carbon dioxide, (2) the development of multi - component standards of volatile

toxic organics in the low ppb range to provide data quality assurance for EPA's

national ambient and hazardous waste incineration audit programs, (3) the

completion of a portable tritium calibration system for the calibration of

measurements of ultra-trace levels of atmospheric tritium, (4) the completion

of a stable standard for sulfur dioxide in air at 100 ppb and a 100:1 dilution

system for calibration of sulfur dioxide in ambient dry acid deposition

measurements over the concentration range of 1-100 ppb, (5) the analytical

measurement of the strengths of infrared absorption bands of halocarbons F-ll

and F-12 at stratospherically-relevant temperatures, (6) an assessment of errors associated with the use of single- vs. multi-component hydrocarbon

standards in the analysis of natural gas mixtures, (7) an initiation of the

development of multi-component gas standards for automotive emission testing

for EPA and State IM programs, (8) feasibility studies for the development of

136
stable standards of hydrogen sulfide for calibrating reduced sulfur emissions

by the pulp and paper industry, and (9) the certification analyses to restock

about 20 gaseous SRMs.

Two major accomplishments during the past year have been: (1) a rigorous

evaluation of the methodology used for preparing highly accurate primary gravimetric standards for carbon dioxide in air used for the certification of stable

SRMs in the 300-400 ppm range, having a concentration uncertainty of less than

0.1 percent relative at 95 percent confidence; and (2) the development of a 17-

component mixture of volatile toxic organics to calibrate GC/MS analyses of

ambient air samples. Research in the former area has led to the development of an optimized procedure that minimizes errors due to the transfer of pure carbon

dioxide into primary standards during their preparation and to the effects of

differences in the matrix air employed. Research in the latter area has

resulted in an NBS - traceable standard that has been used by EPA/EMSL/RTP for

calibrating GC/MS measurements of air samples obtained from an accidental

chemical emission in the vicinity of a major urban area.

Future Plans:

Further developmental activities planned for atmospheric level Carbon

Dioxide - in-Air SRMs include: the finalization of the evaluation of isotopic

dilution mass spectrometry as an absolute reference method; certification of

SRMs at 300 and 360 ppm; the establishment of a set of about six such SRMs that

will continue to bracket global atmospheric carbon dioxide levels for the

indefinite future; and collaborative studies in working with other Federal

agencies and with the World Meteorological Organization in laboratory intercomparisons to ensure an international consistency in ambient carbon dioxide

measurements. Research in the area of volatile toxic organic standards will

include the development of ppm and ppb multi - component mixtures for EPA's Group

Four compounds and the development of preparative methodology for seven- component mixtures at 5 ppb for State monitoring programs. Other planned

research activities include the development of electrochemically-based gas

analysis methodology, the development of ppb mixtures of nitric oxide for dry

acid deposition studies, and the evaluation of trace analysis protocols and

standards to provide data quality assurance in the analysis of gaseous mixtures

for NASA's space shuttle program. The Group also will continue to provide

certification analyses to maintain the availability of gaseous SRMs, currently

totaling about ninety different.

Group staff changes during the year have included the interagency transfer

of Dr. James Elkins in late FY86 to NOAA/GMCC in Boulder, CO, and his replacement with Dr. Michael Verkouteren. Dr. Verkouteren has completed a postdoctoral appointment with Dr. Lloyd Currie in our Division, and comes to us with experience in gas analysis, mass spectrometry, and low-level radioactivity

measurements. The Guest Worker appointment of Mr. Zhong-tao Cai (Shanghai

Institute of Ceramics, People's Republic of China) was extended through

December 1986. Correspondence is in progress concerning the possible

appointment of a second Guest Worker from the People's Republic of China in

trace gas analysis.

137
More detailed write-ups of selected activities and accomplishments of the

Gas Metrology Research Group during FY86 are provided in the Technical

Activities section.

Walter L. Zielinski, Jr., Group Leader; Zhong-tao Gai, William F. Cuthrell,

William D. Dorko , Ernest E. Hughes, Rudolph von Kelly, Gerald D. Mitchell, W.

Robert Miller, Richard C. Myers, George C. Rhoderick, James E. Suddeuth,

Michael Verkouteren.

5 . Analytical Laser Spectrometry Group: Overview

The Analytical Laser Spectrometry Group conducts research on the

development, characterization and application of state-of-the-art laser-based

spectroscopic techniques for the detection of trace and ultra- trace level

gaseous atmospheric constituents. The analytical techniques utilized include

a) photoacoustic spectroscopy, b) phase fluctuation optical heterodyne detection, c) photothermal deflection, and d) tunable diode laser and Fourier

Transform IR (FTIR) absorption spectrometry. A primary objective of the

research carried out in the group is the improvement of measurement sensitivity, selectivity and accuracy of these various techniques for the analysis of

trace reactive atmospheric gases. Other objectives include: (1) development

of new calibration approaches for the above laser-based techniques, (2)

measurement of fundamental molecular parameters necessary for quantitative

spectrometry such as infrared absorption, pressure-broadening and collisionalnarrowing coefficients, (3) intercomparison of concentration determinations by

various techniques, and (4) application of tunable diode laser spectrometry in

the verification of gas standard concentrations and in kinetic measurements of

transient species.

As in the past year, the group's activities throughout FY86 have focused

on fundamental and applied research utilizing tunable diode laser absorption

spectrometry (TDLAS) . Four different, but closely related, research topics were pursued. As will be further detailed in the selected technical reports

that follow, these research activities include the (1) determination of

absorption and pressure -broadening coefficients for selected nitrogen dioxide

(N02

) lines in the infrared, (2) the reinvestigation of the gas phase titration

(GPT) reaction between nitric oxide (NO) and ozone (03

)

(3) the construction

and characterization of a highly accurate dynamic N02 calibration system, and

(4) the development of a nitric acid (HN03

) calibration system for dynamic

standards in the parts -per-million (ppm) concentration range.

Accurate molecular parameters, such as absorption and pressure -broadening

coefficients, for important atmospheric gases like N02 are essential for both

laboratory and atmospheric studies. Traditionally, such determinations for N02 have been carried out using only pressure measurements to derive the number

density of the absorbing species. Because of the presence of N2 0A and the

reactive nature of this compound, systematically low absorption coefficient

results are likely to occur employing pure samples of N02

, unless special

precautions are taken. To address this problem, a novel approach was developed

in our laboratory this past year which completely eliminated the possibility of

such error sources. This was achieved utilizing dynamically generated N02 standards in the 50-100 ppm range employing specially prepared permeation

tubes. In this way, the absorption cell was continuously exposed to new sample

gas. More importantly, this approach enabled us to determine the concentration

of the sample gas with a great deal of redundancy employing gravimetric,

Fourier transform infrared and gas phase titration techniques. Using this

138
approach, absorption and pressure -broadening coefficients for over 26 different

vibration-rotation lines of N02 in one of the most important spectral regions

of the infrared (the i/ 3 band at 6 . 2 /im) were determined.

Significant progress has also been made this past year on the group's long

term goal of improving the photometric accuracy of TDLAS measurements.

Employing the techniques, line- fitting algorithms and system improvements

discussed in last year's report, we have been able to identify and characterize

a subtle, but major, systematic error source not heretofore reported. In

measuring gas concentrations by TDLAS, or alternatively in determining absorption coefficients, the peak absorbance at the center of the absorption feature

under study is typically measured. It has been well established that such

determinations can be systematically low by as much as 50% when the laser

exhibits an appreciable linewidth relative to the absorption feature under

study. The shape of the resulting absorption profile becomes clearly distorted, as manifested by an increased absorption linewidth. However, the

integrated absorbance across the absorption feature will be unaffected by this

"excess laser linewidth." With this in mind, many investigators typically

correct determinations based upon peak absorbance measurements using the

increased absorption linewidth as a scaling factor. This is accurate as long

as no other causes of increased linewidth are prevalent. However, our investigations reveal that laser frequency- j itter , due to mechanical shocks from the

closed-cycle refrigerator compressor, also causes an increased absorption

linewidth. In contrast to excess laser linewidth, this compressor frequencyjitter does not affect the peak absorbance but rather the integrated absorbance. In this case, determinations based upon the peak absorbance would be

accurate while those based upon the integrated absorbance, or corrected for the

increased width, would be systematically too large by as much as 12%. As a result of these two opposite effects, and their associated systematic errors,

all determinations carried out in our laboratory utilize both peak and integrated-fit absorbances. In addition, a unique microphone - triggering circuit

has recently been completed which tracks the motion of the compressor piston

and allows data to be taken only during the central portion of the cycle. This

eliminates the mechanical shock responsible for the compressor frequencyj itter

Significant progress has also been achieved this past year in

reinvestigating the stoichiometry of the gas phase titration reaction between

NO and 03 to produce N02

. As in our past studies carried out four years ago,

all three constituents were measured employing independent techniques.

Significant improvements, however, in both the generation and measurement of 0 3 as well as the measurement of N02 were incorporated in the present study.

Throughout these measurements, the measured 0 3 concentration was found to be

consistently lower than the concentrations of the other two constituents by 1-

1.5%. Various precautions were taken to ensure that other photochemical

oxidants, such as H02 and CH3 02

, were not simultaneously involved in titrating

NO to N02

. Work is continuing on this project. However, our results to date

suggest that the presently accepted value for the 03 absorption cross section

at 254 run may have to be lowered by 1-1.5%, in almost exact agreement with

results recently obtained by Mauersberger employing a completely different

technique

139
Research planned for the upcoming year will continue many of the efforts

initiated this past year. In particular, research will focus on employing

TDLAS in: (1) continuing the reinvestigation of GPT, (2) studies to characterize HN03 in high concentration N02 /air compressed air cylinders, (3)

research efforts to continue the development of a dynamic HN03 generation and

calibration system for ppm and sub-ppm concentration levels, (4) the implementation of procedures and protocols by which EPA can calibrate a mobile TDLAS

for field measurements of N02 , (5) the continued investigation of systematic

error sources, and (6) in the determination of absorption coefficients for

reactive radicals such as H02

.

Alan Fried, Group Leader; Robert Sams, Barry Cadoff, Patricia Johnson, Linda

Nunnermacker , and Nathan Yates.

140
B. Selected Technical Papers

(Gas and Particulate Science Division)

1 . Continuum Radiation Produced in Pure-Element Targets by 10-40 keV

Electrons : An Empirical Model

J . A . Small, S.D. Leigh, D.E. Newbury, and R.L. Myklebust

The purpose of this work was to generate a comprehensive x-ray continuum

database and develop an empirical expression for continuum emission by modeling

the data. The data set used in this study consisted of approximately 4100

continuum x-ray intensity values. The intensity of the continuum l v , is a function of the atomic number of the target, Z, the energy of the continuum

x-rays, Eu , and the energy of the incident electrons, Eq. The targets used in

the study were opaque to the electron beam and consisted of 44 pure elements

ranging in atomic number from Z-4 to Z-92. Eq values of 10,15,20,25,30,35, and

40 keV were investigated for this study.

The modeling of continuum x-ray production was done on generated x-ray

intensities, i.e., the intensity per unit of electron flux produced within the

target. The experimental intensities were selected so that they were free of

characteristic and escape peaks as well as other major spectral artifacts. The

calculation of the generated continuum x-ray intensities from experimental

x-ray intensities required correcting the data for absorption of x-rays by the

target material and the detector, electron backscatter loss, and anisotropic

x-ray generation. No corrections were made for the escape of Si x-rays from

the detector, incomplete charge collection, and the absorption of x-rays in the

20 nm thick carbon coat on the sample. For continuum measurements, these

corrections are relatively insignificant and will have a minimal effect on the

final model. In addition, the final equation does not include a geometric

efficiency term.

Our basic approach in developing a parametric empirical model to describe

the data was to employ graphical methods to analyze the data by plotting

various portions of it in 2-, 3-, and 4-dimensional representations. For this

work, l

u , was consistently used as the dependent variable. These plots were

then fitted in an iterative fashion with models suggested by the observed

shapes. The modeling was done with the NBS DATAPLOT program. The 2-

dimensional plots were modeled first. The information from the fits run on the

2 - diraens ional plots was then combined to model the 3- and 4 - dimens ional

surfaces. The final model can be expressed in photons-per coulomb-per 10 eV

energy window as

log(Iv ) = ( Mlog(ZEq/Eu

- 1 ] ) + B } (1)

where M - 0.0060E0 + 1.047; B - -0.032E0 + 5.799

This relation incorporates the well-known Kramers' variable, Z* ( Eq/Ev

1 )

into a global model useful for predicting generated continuum intensities over

a wide range of accelerating voltages 10-40 keV , atomic numbers 4-92, and x-ray

energies 1.5-20 keV. It was determined from the mathematical modeling of an extensive data set that includes a broad range of Eq

s and Eu

'and a majority

of the pure-element targets which are usable in electron beam instruments . In

general, under normal analysis conditions, relative errors less than 20 percent

can be expected for intensities calculated with this equation.

141
2 . Defocus Modeling for Compositional Mapping with Wavelength-Dispersive

X-ray Spectrometry

R.L. Myklebust, D.E. Newbury, R.B. Marinenko , and D.S. Bright

Quantitative compositional mapping by electron probe microanalysis with

wavelength-dispersive x-ray spectrometry provides a new and important mode of

operation. The use of the wavelength-dispersive x-ray spectrometer (WDS)

provides access to trace compositional levels but, in order to employ the WDS,

a correction must be applied to the data to compensate for the effects of

spectrometer defocusing. There exist four methods to correct spectrometer

defocusing: (1) stage scanning; (2) spectrometer crystal rocking to move the

focus position of the spectrometer in synchronism with the beam scan on the

specimen; (3) "defocus mapping," described in our work for FY85, in which a "standard map" is prepared under the same conditions as the unknown and is used

to calculate intensity ratios with the map of the unknown on the basis of

corresponding pixels; and (4) "defocus modeling," in which the defocus map is

calculated rather than directly measured.

While the standard map technique can provide accurate corrections for

defocusing, there are significant drawbacks in the practical application. (1)

Preparing the standard map requires scanning an area on the standard as large

as that of the unknown. (2) Any defect in the standard such as a scratch,

hole, or inclusion which affects the x-ray intensity will appear as an artifact

in the final compositional map of the unknown. (3) Although the standard maps can be archived and readily scaled to changes in beam current or spectrometer

efficiency, a new map is required for each new magnification and element.

Defocus modeling can overcome 'several of these limitations and provide a more flexible approach to mapping.

The principle of defocus modeling is based on the observation that an x-ray area scan which is generated with a moving electron beam and a fixed

spectrometer contains equivalent information to an intensity profile of an x-ray peak generated by scanning the spectrometer with a fixed beam. Thus, if we have a spectrometer scan across a peak measured on a standard, which

consists of the intensity as a function of angular position, it should be

possible to construct an equivalent "standard map." The procedure used to

calculate a standard map is to first determine two points on the line of

optimum focus in the scan matrix, which can be recognized in the intensity map

of the unknown. For each location (i,j) in the standard matrix, the distance

from the focus line is then calculated. This matrix distance is converted into

a angular deviation which corresponds to a particular excursion off the peak in

the spectrometer scan of a standard. From this equivalent position in the peak scan vector, the intensity, I, relative to the peak centroid is taken and

assigned to matrix location ( i , j , I )

The procedure is repeated until the

standard map matrix is completed.

In order to test this procedure, a defocus map was generated by the

modeling method and compared to a defocus map generated by the scanning method

The disagreement between the trace from the synthetic standard map and the

trace from the experimental standard map is less than 2% throughout the range.

There are several advantages of defocus modeling. Only one peak scan of

sufficient angular width is needed to generate a standard map appropriate to

any magnification in the range covered. The calculation procedure from stored scan vectors is inherently fast. The modeling procedure is useful down to

magnification of approximately 150x, being eventually limited by statistical

142
considerations due to the fall-off in spectrometer transmission. The synthesized standard map can have better counting statistics than a conventionally

scanned standard map because longer counting times per channel can be allowed

when making the peak scan.

3 . Bright Field Image Correction Using Various Image Processing Tools

D.S. Bright and E.B. Steel

Many microscopes, whether using light or electrons, have trouble

maintaining uniform illumination across a field of view at the lowest magnification ranges available on the instrument. This is because the microscope

optics and detectors are primarily designed for higher magnification viewing.

However, uniform background illumination is desirable not only for display but

for subsequent computer analysis.

Elementary calculations show that a bright field or transmission mode

image may be corrected for uneven background illumination and non-uniform

detector sensitivity by dividing the image by a background or blank image.

Images typically corrected by this method are taken at low magnification, e.g.,

40X on a compound light microscope (LM) or 300X on a Scanning Transmission

Electron Microscope (STEM). The correction is made by dividing the image by a blank or background image, with appropriate filtering, and then by scaling the

result. When blank images are not easily obtained instrumentally , and when the

objects in the image are sufficiently thin or small, the background image may

be approximated using the sample image by applying a maximum filter. The

maximum filter is a smoothing filter where each pixel of the generated blank

image is the maximum value of the original pixels in a square window around it.

The window should be about twice as wide as the largest narrow dimension of any

feature in the sample image.

The rationale for dividing an image by a blank image is the following:

For each pixel:

(a) I - L * A * S

where I is the pixel intensity, L is the illumination for that pixel, A is the

fraction of radiation transmitted by the object, and S is the sensitivity

factor of the detector. With no sample present, the pixel intensity, lb , for

the blank image is:

(b) lb = L * S

Dividing equation (a) by equation (b) gives:

(c) A - I / lb.

A is the desired intensity, to within a scaling factor, for the corrected

image- -one with even background illumination, and uniform detector sensitivity.

Digital images corrected with this algorithm show the desired background

uniformity and provide a better starting point for more sophisticated processing algorithms which seek to extract objects based on size and shape information or other criteria. This relatively simple background algorithm is thus a key to realizing better performance in the more complex image processing

operations which are critical to our work.

143
4. Euclidian Distahce Mapping for Shape Characterization of Alloy Grain

Boundaries

i

D.S. Bright and D.E. Newbury

When monitoring the changes in microstructure of an alloy, as imaged with

optical, electron, or ion microscopy, it may be desirable to characterize the

shape of the grains of the discontinuous phase. In the course of examining

some two-phase microstructures, the more common spatial parameters used to

describe the structure, such as the phase intercept length, were not adequate

to follow the complex changes observed in the structure. In particular, the

discontinuous phase showed the formation of string-like protuberances.

A measurement that is sensitive to protuberances can be developed from the

Euclidian distance map. The distance map is constructed from the original

image by:

1. Setting a threshold intensity level to distinguish the discontinuous

grains from the continuous phase.

2. Calculating the distance map for each grain.

3. Averaging selected values from the distance map over selected grains.

The choice of the threshold value is critical in such operations since the

area, connectivity, and many other characteristics of each grain are affected.

Often this choice is made by human” operators, and therefore might not be

reproducible. We have developed a computer algorithm that sets the threshold

automatically, given that the edges of the grains in the image are sharp. The

algorithm first takes the gradient of the image, which makes the edges of the

grains the brightest objects in the image. Then a threshold level of this

gradient image is chosen such that the edge areas selected have a maximum

thickness of two pixels from the original image. The average intensity of the

edge pixels is used as the threshold value. The distance map is then calculated using an efficient algorithm from the image processing literature. For

pixels in each grain, values of the distance map represent the distance from

the pixel to the nearest edge of the grain. The distance map has local maxima

that lie on the skeleton of the grain. The value or height of the distance map

at these points gives the width of the grain there. The average of the local

maxima is a shape measure sensitive to the long thin protuberances which are attached to larger, more rounded parts of the grains. Rounded grains typically

have a few large values, while the long, thin protuberances have many small

values. The new measurement technique has been successfully applied to monitor

changes in lead- tin alloys during annealing.

5 . Ion Implantation Artifacts Observed in Depth Profiling Boron in Silicon by

Secondary Ion Mass Spectrometry

D.S. Simons and P. Chi

We recently conducted and reported a comparison study of depth profiling

by secondary ion mass spectrometry (SIMS) and neutron depth profiling (NDP) in

collaboration with Division 551 and the NBS Center for Electronics and

Electrical Engineering. The specimens were portions of 5 cm diameter single

crystal <111> silicon slices in which 10 B had been implanted at various

fluences and energies on the CEEE ion implanter. NDP measurements were made on

144
a 13 mm diameter area at the center of the wafers. SIMS measurements were

taken from a 60 ^m diameter area approximately 16 mm from the center of the

wafers

One observation that emerged from this work was an apparent discrepancy

between the profiles of 10 B measured by NDP and SIMS. The peaks of the SIMS

profiles were typically deeper than those of NDP by as much as 30 nm, which is

10% of the projected range for a 70 keV implant. Moreover, the profiles could

not be made to coincide by either a constant shift or a proportional change of

one depth scale with respect to the other. The discrepancy was not explainable

by any known artifact of either SIMS or NDP. This led to a hypothesis that the

actual depth distribution of boron in the wafers was not laterally homogeneous.

We have conducted two experiments to check this proposed explanation. In the

first case, SIMS profiles of 1X B were taken at 5 mm intervals across two

perpendicular diameters of a 5 cm diameter wafer of <111> silicon that had also

been implanted at the CEEE facility. Discrepancies in the depth of the peak as large as 25 nm were seen between the edge and center of the wafer, with the

profile near the edge being deeper. Profile shapes were also different. These

differences were not a smooth function of position along the diameter.

Instead, all of the changes occurred from one edge to the center, and no differences outside of measurement variability were seen from the center to the

other edge. The second experiment was a remeasurement by SIMS of several of

the original wafers that had been implanted with 10 B, this time at the center

of the same area that had been sampled by NDP. In this case the agreement of

the two methods was within the limits of measurement variability.

The lateral inhomogeneity of boron that these experiments have

demonstrated arises from the variable contribution of ion channeling during

implantation. The single-crystal wafer is tilted 7 degrees from the surface

normal in an attempt to achieve a "random equivalent" orientation that minimizes unintentional ion channeling. However, the ion beam is scanned by a single plate electrostatic deflection system that varies the angle of incidence

by several degrees from one side of the wafer to the other. Since the fraction

of incident ions that is channeled is a strong function of the incidence angle

for angles less than 7 degrees, it is easy to understand how variations in ion

channeling could occur across the wafer surface, resulting in differences in

peak shape and projected range. Other factors that may contribute to this

problem are the uncontrolled azimuthal angle of the wafer in the implanter and

a possible misalignment between the center of the beam raster pattern and the

center of the wafer. As a result of this new understanding of systematic

effects in ion implantation, it is now possible to embark on a joint SIMS-NDP

project to produce an ion- implanted depth profiling standard reference material

for SIMS.

6 . An Evaluation of A High Purity Germanium X-ray Detector on a 200 kV

Analytical Electron Microscope

Eric B. Steel

The Microanalysis Research Group has tested the first high purity

germanium detector (HPGE) to be used on an analytical electron microscope

(AEM) . Theoretical predictions and preliminary experimental results have been

compared for the HPGE and Li thium- Drifted Silicon [Si(Li) ] x-ray detectors

which are simultaneously mounted on the microanalysis AEM.

145
A JEOL 200 CX AEM equipped both with a zero-degree take-off angle

germanium detector and with a high take-off angle conventional Be window Si(Li)

detector was used to collect data. NBS research material synthetic glasses,

natural minerals, and pure metals were examined at an accelerating potential of

200 kV. The specimens were prepared as particles or sputtered films on thin

carbon films supported by 200 mesh copper grids.

An AEM operating at an accelerating voltage of 200 kV is capable of

exciting the K-line x-rays of all known elements, but the sensitivity of the

Si(Li) x-ray detector mounted on these instruments decreases rapidly with

increasing x-ray energy for the K-line x-rays of elements heavier than

molybdenum (K- alpha = 17.44 KeV.) An attractive alternative for the high

energy portion of the x-ray spectrum above 20 keV is the HPGE detector, which

has been used for many years to analyze gamma - rays . The 5.6 mm thick HPGE has an efficiency greater than 90% for the K-line x-rays from the elements with

atomic numbers from approximately 25 through 85. The Si (Li) detectors must

rely on the observation of M and L-line x-rays for most elements above

approximately atomic number 50.

Analysis with these high energy K- lines has certain advantages over the

analysis of L and M- lines from the same elements: (1) The fluorescent yield is

many times larger for the K- lines than the L or M- lines. (2) The continuum has

lower intensity at high energies which improves the signal to noise for the

high energy K-lines. (3) The absorption correction is very low for these high

energy x-rays in the thin specimens analyzed on the AEM and in most cases can

be ignored. (4) The K-line spectra are relatively simple with reasonably well

known weights of lines. The M and L-line x-rays yield much more complex

spectra with many more, often overlapping, peaks than are seen for K-lines. In

addition, much less data is available on the relative weights of L and M x-rays

than exists for the K-lines. Because of these problems with L and M-line

x-rays, quantitation of heavy element compositions can be difficult.

The positive factors associated with the AEM x-ray analysis using an HPGC

are tempered by several problems. The chief difficulty is the behavior of the

ionization cross section. The cross section falls by a factor of ten from

atomic number 50 to 96 when operating at 200 kV, so that although the high

energy K x-rays are more efficiently detected they are less efficiently

excited. Another disadvantage of the HPGE is the poor efficiency for the low

energy x-rays from the elements with atomic number less than 20. This is

largely controlled by the absorption in the Ge dead layer of the detector.

Another factor which exacerbates the low energy problem is the large incomplete

charge tails on the peaks in this region. These problems can be overcome by

using the Si(Li) detector for analysis of the low energy x-ray lines.

7 . Compositional Analysis of Human Cardiovascular Deposits by Micro-Raman

Spectroscopy

E . SEtz

In previous applications of Raman microprobe spectroscopy to the study of

biological tissues, we have examined the processes of mineralization in tooth

and bone with a view to obtaining data on the molecular composition from

microscopic sampling regions. These studies have now been extended to other

types of calcified tissues to further the present understanding of various

forms of pathological calcification. The specific aim is to obtain a comprehensive physicochemical characterization of cardiovascular calcification in man

146
employing a broad range of analytical techniques mainly to establish -- in the

first phase of this work -- the complex identity of the inorganic or mineral

phase of cardiovascular calcified deposits. The work described here is

conducted in collaboration with researchers at the American Dental Association

Health Foundation at the NBS under a grant from the National Heart, Lung and

Blood Institute of the NIH.

Laser-Raman microanalysis (LRM) stands out as the only technique to

provide direct molecular and structural information not available from the

conventional electron- and ion-beam microanalytical techniques. Thus, LRM has

corroboratively been applied to elucidate two types of cardiovascular calcification: (i) atherosclerotic calcification in man, and (ii) bioprosthetic

calcification of heart-assist devices implanted in animals and in man. There

is at present a special urgency about gaining a fuller understanding of the

pathogenesis of biomineralization as it holds the promise of a more successful

application in man of bioprosthetic cardiovascular devices. These investigations have relevance to certain areas of biotechnology, especially to current

efforts of improving the blood compatibility of a wide range of biomedical

polymers undergoing extensive evaluation as biological implant materials.

Of prime interest is the composition of the apatitic phase in native

calcified deposits, and of deposits with the organic matrix removed by a deproteination treatment. Other goals are to obtain information on the type of

carbonate substitution of C03 2- for either P04 3- or OH* (or both) in these

biological calcium phosphates, and to quantify carbonate contents by an empirical procedure employing calibration data derived from the measurement of

synthetic carbonate apatites of known composition. The most abundant mineral

in human tissues is a "biological" hydroxyapatite (HAP) , idealized as Ca x

(P0 4

) 6 (0H) 2

. But other calcium phosphates, for example CaHP04• 2H2 0

(brushite) , Ca3 H2 (P0 4

) 6

• 5H2 0 (octacalcium phosphate, OCP) , and /)-Ca3 (P04

) 2 (/3- tricalcium phosphate, /3-TCP) , have been identified with or without association with apatite. With age, and in most cases of pathological calcification,

the phosphate minerals incorporate carbonate, forming stable phases of biological "carbonate apatites". In these, carbonate may substitute for phosphate

(Type-B carbonate apatites) or for hydroxyl (Type-A carbonate apatites).

Several types of cardiovascular calcified deposits were examined in the Raman

microprobe furnishing diagnostic vibrational spectra. These consisted of human

atherosclerotic deposits and of bioprosthetic calcified plaques removed from

the "Blomer" (a widely used polyether urethane) surfaces of blood pumps

implanted in both animals (calves and sheep) and in man. The Raman spectra of

these deposits show a close similarity in composition of the mineral phase

found in the different living organisms and associated with different host

materials. It consists of an "impure" carbonate substituted (Type-B)

hydroxyapatite for which carbonate contents are found to range from 5.8 to 7.5

wt% . These carbonate apatites of variable composition may be represented by

the general empirical formula (Ca x

_ x _y (P04

) 6

_ x (HP04 , C03

) X

(0H) 2

_ x . 2 y

with

substantial substitution of Ca by both Na and Mg. These results shed new light

on the pathological processes leading to atherosclerotic disease and the

degradation of bioprosthetic implant materials in the cardiovascular system.

Furthermore, they point to similar mechanisms by which these deposits are formed

147
8 Analysis of Molecular Carbonate fev Laser Microprobe Mass Analyzer

R.A. Fletcher

There is considerable interest in detecting the presence of carbonates on

the micrometer scale in biological bone apatites and in a recently discovered

and extremely rare mineral. Owing to the low mass, carbonates are difficult to

detect by electron microscopy, but can readily be detected by mass spectrometry. The analysis of carbonate in apatites by the Laser Microprobe

Mass Analyzer (LAMMA) has been previously reported by one researcher. The

LAMMA is a time - of - flight mass spectrometer that utilizes a pulsed laser to

ablate and ionize the specimen in the micrometer domain. Attempts to reproduce

the work quoted in the literature with the NBS LAMMA resulted in some anomalous

observations, and a much more detailed study was undertaken as a result.

Mass spectra have been obtained for several alkali metal and alkali earth

carbonates. Both commercial and high purity SRM material were examined. Dry

crystals of each compound were suspended from a nickel transmission grid with

no thin film backing. The samples were all irradiated with 266 rim radiation

for a 10 ns pulse duration with power densities ranging from approximately 10 7 to 10 8 w/cm2

. The reported fragment ion useful for identifying carbonate is

C03 - m/z = 60. For the calcium, barium, and strontium carbonates, we have

observed low ion formation at m/z of 60. The small m/z 60 peak is usually

found in the presence of carbon clusters, Cn _ , which appear at m/z 12, 24, 36,

48, 60, 72. However sodium, potassium, and to some extent lithium generate

strong m/z 60 peaks. This is puzzling since the heats of formation for all the

above compounds are approximately the same, -110 kJ/mole. What is of interest

is that more soluble compounds tend to generate strong mass 60 peaks. The m/z

60 peak has been verified as the carbonate ion by using carbon 13 labeled

isotopes of potassium and barium carbonate. The carbon cluster formation which

is an interference at m/z 60 is from a carbon 12 contaminant, not from the

fragmentation of the 99% J- J C03

. An understanding of the C03 - abundance

differences between alkali and alkaline earth carbonates is being sought.

The m/z 60 peak has been confirmed as the carbonate ion. However, the

fact that the carbonate ion formation is so mysteriously weak for alkaline

earth carbonates leads us to believe that the LAMMA in its current

configuration will not prove to be a useful tool for analysis of biological

samples where calcium carbonate is the species of interest. The further

understanding of the interaction of alkali and alkaline earth carbonates with

ultraviolet radiation may lead to some new knowledge of bond breaking and

ionization processes in LAMMA. We are also interested in further developing

the LAMMA with double-pulse ionization capabilities which may improve its

sensitivity and specificity.

9 . Ultratrace XRF Analysis with Monochromatic Synchrotron Radiation - Some

Preliminary Observations

P.A. Pella and R.C. Dobbyns

Energy-dispersive x-ray fluorescence spectrometry is a technique often

used as a routine analytical method because it is non-destructive, rapid, and

capable of multi-element analysis. A major drawback is its relatively low

sensitivity when compared to many other trace element techniques. Key factors

to improving the minimum detection limit (MDL) consist of signal enhancement

through higher x-ray intensity sources which are also energy tunable, and

148
reduction of background. Recently, high sensitivity in XRF analysis has been

demonstrated by using synchrotron radiation (SR) in which high brightness,

energy tunability, and polarization of SR are effectively utilized. In the SR

experiment, scattered radiation can be reduced owing to the effective utilization of the polarization of SR and to the use of a thin sample. In order to

reduce the background still further, the use of total reflection of x-rays has

been shown to be an effective technique. The combination of SR and total

reflection geometry for XRF analysis has recently been applied by Iida and

coworkers at the University of Tokyo at concentrations as low as 0.5 ppb or

1 PgThe NBS Materials Science beam line has been operating at the Brookhaven

National Laboratory for the past several years. This year we carried out preliminary experiments to determine if the existing experimental arrangement at

the beam line is suitable for performing total reflection XRF analysis. We were also particularly interested to see if selenium in human serum could be

analyzed non -destructively. There has been increased interest in the accurate

determination of selenium at nanogram levels, especially for the development of

human and bovine sera standard reference materials.

It was found that the present instrumentation at the beam line is ideally

suited for performing total reflection XRF analysis in the 5 to 20 keV range

using the monochromatic x-ray beam. This was determined using various types of

samples on Si(lll) reflector surfaces when the x-ray beam incident on the

sample could be controlled and varied at angles below and above the critical

angle, typically in the region of a few milliradians . A twenty microliter

droplet of a human serum sample was allowed to evaporate on a Si (111) reflector

and gave a Se signal which was about 2.3 times that of the background. These

results indicate that Se at the nanogram level should be measurable by this

technique. Further work will be directed towards the quantification of the Se

x-ray intensity to determine concentration and to investigate the potential of

the high flux white beam for ultratrace analysis.

10 . Uncertainties in Mass Absorption Coefficients in Fundamental Parameter

X-ray Fluorescence Analysis

P.A. Pella and B.A.R. Vrebos

Fundamental parameter correction methods for x-ray fluorescence analysis

in the form of computer programs are becoming more common place in recent

years. Programs such as NRLXRF, XRF- 11, SAP3, and NBSGSC require physical

constants such as mass absorption coefficients, fluorescence yields, and

absorption jump ratios. When comparing programs, one finds that different

sources of mass absorption coefficients are often used. Since there is no definitive compilation of mass absorption coefficients that x-ray analysts

accept as being the most accurate, it was of interest to examine three commonly

used compilations and to determine what influence, if any, could be observed on

the results of analysis. These are the compilations of (1) Heinrich; (2)

Leroux and Thinh; and (3) McMaster et. al . In addition, some fundamental

computer programs use the total mass absorption coefficient (i.e., photoelectric plus coherent and incoherent scatter) while others just use the

photoelectric contribution. The accuracy of any mass absorption coefficient

can significantly affect the accuracy of results obtained when only pure

standard samples are used for calibration and in so-called "standardless

analysis." To test the influence of the different compilations on the analysis

results, the program NBSGSC was used. This program offers several options,

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among which are choice of mass absorption coefficient compilations, measured or calculated primary spectral distributions, and selection of pure or multielement standards for calibration. The influence of different sources of

primary spectral distributions has already been published.

To obtain a perception of the relative differences in the mass absorption

coefficient compilations over a broad range of atomic numbers and x-ray line

energies, computer imaging was used to compare the individual values between

any two compilations and to display the relative differences. From these

figures it was surprising to see differences greater than 10% for elements with

atomic numbers larger than 20 and energies in the 10 to 30 keV range.

To detect any direct influence of mass absorption coefficient differences

in results of analysis, an analysis strategy had to be devised. Sample matrix

and incident x-radiation energy had to be chosen when the mass absorption

coefficient differences in compilations were significant. For this reason, we chose to perform an energy-dispersive experiment using different secondary

target exciters in order to select monochromatic primary radiation of known

energy. In this way, uncertainties in the incident x-ray spectrum are minimized. The samples chosen were Fe-Ni, and Fe-Ni-Cr alloys which exhibit strong

interelement effects as well as strong absorption for the primary radiation.

The secondary targets were zinc, germanium, molybdenum, and tin, covering a range from 8.6 to 25 keV for the incident energy. Both KQ and Kg lines of the

secondary targets were considered for excitation where their ratio was measured

from the scattered incident radiation from a light element sample. The samples were analyzed first with pure elements and then with "type" standard materials

where calibration included linear and second degree polynomial fits to the

standards when the intercept was constrained to zero.

An analysis of variance (F-test) using pure element standards showed that

34 out of 48 absolute errors for the Fe-Ni system using the three different

compilations and bichromatic excitation were significantly different at

confidence levels ranging from 90 to 99%. The degree of agreement between

results with the different compilations improved with "type" standards where,

with linear calibrations only, 14 out of 48 absolute errors were significantly

different, and with a second degree polymonial fit, no significant differences

were observed.

It was concluded from this work that, for some sample types, different

mass absorption coefficient compilations can lead to serious differences in

results, especially when only pure elements or no standards are used for

calibration. In regions where serious differences occur, more good

experimental measurements may be needed to resolve disagreements

11 . XRF Analysis of Marine Sediments (NOAA/NBS Specimen Bank) by Automated

Borate Fusion

G.A. Sleater

A new class of materials that was analyzed by XRF spectrometry in the past

year consisted of marine sediments. Six samples of marine sediments were taken

from materials stored in the National Environmental Bank at NBS ; four samples were supplied by NOAA. The analyses, done for the Specimen Bank, were intended

not only to determine the composition of the sediments but also to furnish

information for selecting future Standard Reference Materials.

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1 The ten samples varied in consistency from fine, flour-like powders to

gritty, sand- like materials. As the analytical specimens were to be prepared

from the samples by automated fusion with a lithium tetraborate flux at 1050 C

to form homogeneous glass disks, preliminary studies were made to determine the

loss on ignition (LOI) of each sample at this temperature. Because the range

of LOIs was so great (from about 1% to 55%), all sample materials were preignited at the above temperature before preparing the fused specimens; this

pre- ignition ensured a uniform ratio between sample and flux in all specimens.

To determine concentrations from XRF intensity data, synthetic standards

containing the elements of interest were prepared from high purity (99.999%)

reagents under conditions identical to the preparation of the marine sediment

specimens.' Preliminary concentrations for the sediments were calculated using

the NBSGSC fundamental parameter program for interelement corrections developed

in this Group. Additional synthetic standards were then prepared to duplicate

the concentrations calculated for each marine sediment sample, and final

concentrations were calculated.

The concentration ranges (weight percent) for the ten elements determined

by XRF spectrometry are given below. Wavelength-dispersive spectrometry was used to determine all concentrations, except for Rb and Sr which were measured

by energy-dispersive XRF analysis.

Si; (36.69% - 12.87%) Ti: (0.63% - 0.21%)

Al: (7.84% - 3.72%) Mn: (0.12% - 0.027%)

Fe: (5.22% - 1.41%) Zn: (0.023% - 0.0012%)

K: (2.27% - 0.61%) Sr: (0.040% - 0.011%)

Ca: (1.97% - 0.28%) Rb: (0.013% - 0.0016%)

Determination of Absorption and Pressure - Broadening Coefficients for

Selected Infrared Transitions of N0„ bv Tunable Diode Laser Absorption

Spectrometry

A. Fried and R.L. Sams

The reactive gas N02 is one of many key atmospheric species presently

being studied worldwide in numerous laboratories as well as in the ambient

environment. To meet the ensuing need for accurate standards employed in these

various studies, the National Bureau of Standards has been actively involved in

providing and certifying N02 standards capable of delivering concentrations in

both the parts -per -billion (ppb) and parts -per-million (ppm) ranges.

As part of our long-term program to ensure high accuracy in such

calibration standards, the Analytical Laser Spectrometry Group has been active

in developing alternate methods by which to verify calibration. Tunable diode

laser absorption spectrometry (TDLAS) is a particularly attractive means to

accomplish this in both of the above mentioned concentration regimes. However,

accurate molecular parameters, such as absorption and pressure -broadening

coefficients must first be determined. The present study was therefore

undertaken with this goal in mind.

Traditionally, absorption coefficients for N02 have been determined only

using pressure measurements to derive the number - dens i ty of the absorbing

species. Because of the presence of N2 0A and the reactive nature of NO,,

systematically low absorption coefficient results are likely to occur employing

151
pure samples of N02 , unless special precautions are taken. To address this

problem, a novel approach was developed which completely eliminated the

possibility of such sources of error. This was achieved by utilizing dynamically generated N02 permeation standards in the 50-100 ppm range employing

specially prepared permeation tubes. In this way, the IR absorption cell was continuously exposed to fresh sample gas. More importantly, this approach

enabled us to determine the concentration of the sample gas with a great deal

of redundancy. We first utilized the conventional gravimetric approach in

which the sample gas concentration was determined based upon accurate flow

calibrations and permeation tube weight loss measurements. Fourier transform

IR spectrometry (FT-IR) was next employed to search for impurity gases like

HN03 co -permeating with N02

. No other gases were found. The accuracy of the

gravimetric determination was further corroborated by integrated band absorption measurements employing FT-IR as well as by gas phase titration, as will be

thoroughly discussed in a subsequent report.

Employing such unprecedented redundancy in determining the sample gas

concentration, absorption and pressure -broadening coefficients for over 26 of some of the stronger IR absorption lines of N02 (6.2 /xm spectral region) were determined. As a result of this effort, TDLAS can now be employed with high

accuracy to measure N02 standards independently.

13 . Construction and Characterization of a Highly Accurate Dynamic N0 2 Calibration System for NASA's Global Tropospheric Experiment

A. Fried, L. Nunnermacker , B. Cadoff, N. Yates, R. Dickerson, R. Sams, and

J . Norris

The National Aeronautics and Space Administration (NASA) is sponsoring a multi-year program to study the non-urban troposphere, the Global Tropospheric

Experiment (GTE). In the second phase of this study scheduled for August 1986,

important atmospheric constituents such as N02 and HN03 will be measured at

trace background levels extending down well below one part-per-billion (ppb)

Accurate calibration standards in this concentration range are therefore

required.

Because of our expertise in trace N02 standards, the Analytical

Spectrometry Group was asked by NASA this past year to construct and characterize a highly accurate dynamic N02 calibration system for use in this field

experiment. Such trace level calibration standards can conveniently be

prepared using low level (1-50 ppm) compressed gas N02 mixtures in a dynamic

dilution system. The accuracy of the resulting trace gas mixture will obviously be directly tied to the accuracy of the input gas. However, in addition

to significant amounts of HN03 found in these cylinders, the stability of the

N02 concentration in such compressed gas mixtures remains unknown.

Consequently, we decided to develop a dynamic calibration system centered

around an N02 permeation tube standard.

The N0? permeation calibration system was constructed by modifying a commercial unit. First, thermostated mass flow controllers were added for

precise and accurate flow control. A second dilution stage was next added to

generate N02 concentrations as low as 0.5 ppb. To achieve this, most of the

flow from the first stage has to be vented and only a very small flow of

approximately 0.1 L min-1 (where the standard conditions are 25 °C and 1 atm

pressure) is allowed to entered the second stage for dilution with 10 L min 1 (where the standard conditions are 25 °C and 1 atm pressure) of air. Control

152
of this flow into the second stage is accomplished by controlling the vent flow

with a mass flow controller. In this way, the permeant gas directly enters the

second stage without going through a mass flow controller. Thus, we avoid the

attendant uncertainty of concentration losses. The downstream side of the vent

flow controller, however, must be connected to a vacuum pump to satisfy the

necessary pressure drop for flow control without pressurizing the entire

upstream side of the system. Extensive tests have been performed to characterize both the linearity of the system from approximately 30 ppb down to 0.5

ppb as well as the absolute N02 output concentrations. Determinations of these

concentrations over this range have been carried out based upon permeation tube

flow and weight loss measurements and compared with those determined using an ultra- sensitive chemiluminescence detector calibrated by NO SRM standards and

gas phase titration. Agreement was typically within 2%, thus indicating no significant N02 losses as well as good mixing dynamics.

14. Development of a HN03 Calibration System for Dynamic Standards in the

Parts - Per-Million Concentration Range

L. Nunnermacker , R. Dickerson, and A. Fried

Nitric acid (HN03

) is an important molecule in atmospheric studies. This

species plays a key role in the nitrogen chemistry of the atmosphere and is

directly linked to major concerns associated with acid precipitation. As with

N02

, accurate gas standards in both the parts -per-billion (ppb) and parts-permillion (ppm) concentration range are required for both laboratory and field

studies.

Commercial HN03 permeation tubes can deliver ppm and ppb levels of this

gas, and a gravimetric calibration can be obtained from the weight loss and the

flow rate in much the same manner as for an N02 permeation tube. However,

while N02 permeation tubes contain pure N02 , the HN03 tubes contain a mixture

of HN03 and H2 0. A constant boiling azeotropic mixture of HN03 and H2 0

permeates through the walls and thus the resulting weight loss does not

accurately reflect the HN03 concentration permeating. During this past year, a research study was initiated to characterize accurately the HN03 concentration

from such permeation tubes using dynamic standards in the ppm and ppb range.

In collaboration with the University of Maryland, we have been studying

the reaction between HCl and AgN03 to form HN03 gas and AgCl precipitate. In

the 100 ppm concentration range, this reaction was found to generate quantitatively one molecule of HN03 in the gas phase for every HCl molecule flowing

(50-100 scm3 rain-1

) into the AgN03 reactor tube. The gas eluting from the

reactor tube was passed into aqueous solution where the resulting N0 3 ion

concentration was measured by ion chromatography (IC). Since 99.6% of the gasphase HN03 was found to be trapped in the first of a series of such solutions,

the aqueous N03 ion concentration is directly related to the gas -phase concen- tration of HN03 in the flowing gas stream. This gives a direct means of

calibration. In most cases, residual Cl ion, which would be indicative of

unreacted HCl , was not found in solution. We therefore plan to measure

accurately the HCl cylinder concentration by tunable diode laser absorption

spectrometry (TDLAS) , a task in which we have considerable expertise, to obtain

a second independent calibration of the gas-phase HN03 concentration.

Continued research on this calibration technique is planned for the coming

year. In addition to extending the technique to the low ppm and ppb range,

studies are planned to couple the above two calibration approaches with three

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additional approaches using 1) chemiluminescence detection employing nylon

scrubbers, 2) direct absorption by TDLAS , and 3) direct absorption by Fourier

transform IR spectrometry. The resulting HN03 calibration system, which will serve as a working standard for permeation tube studies, will have the utmost

in calibration redundancy.

15. Re - Investigation of the Gas Phase Titration Reaction Between NO and 03

: Redetermination of the Absolute Cross Section of 03 at 254 nm

A. Fried, B. Cadoff, L. Nunnermacker , R. Sams, A. Bass, and J. Norris

This past year, research was resumed on the investigation of the

stoichiometry of the gas phase titration (GPT) reaction: NO + 03 = N02 + 02

. This reaction, which we studied four years ago, is very important since it

provides a mechanism by which standards for the first three constituents can be

intercompared. Such intercomparison is an integral part of our group's long

term goal to ensure high accuracy in gas calibration standards provided by NBS

In the case of NO and N02 , NBS provides and certifies NO standard reference

material (SRM) gas mixtures and N02 permeation tube standards, respectively

Measurements of 03 are carried out employing ultraviolet (UV) absorption

photometry using the 254 nm Hg line, and thus the standard employed is the

absorption cross section at this wavelength. The study of the GPT reaction was

re- initiated this past year in an effort to explain and minimize a 3.6%

systematic bias previously found between measurements of 0 3 and those for NO

and N02

. The latter two constituents were in agreement to better than 1%.

As in our past study, all three constituents were measured employing

independent techniques. Significant improvements, however, in both the

generation and measurement of 03 as well as the measurement of N02 were incorporated in the present study. Measurements of 03 were carried out

employing one of the Standard Reference Ozone Photometers which is part of the

NBS/EPA national monitoring network. This photometer was developed by Bass and

Paur and described in a number of previous reports. In contrast to the long

path 0 3 photometer using in our previous GPT study, both the short and long

term stability for the new photometer and 03 generator were excellent. We also

improved our measurement capability for N02 in terms of sensitivity and

selectivity utilizing tunable diode laser absorption spectrometry (TDLAS) . In our previous study, N02 measurements were carried out employing photoacoustic

spectrometry (PAS). Although PAS is fairly selective, the extremely high

selectivity of TDLAS is further required in GPT studies to unequivocally verify

that the oxidation of NO does not proceed beyond N02

.

Throughout this study, the measured 03 concentration was found to be

consistently lower than the concentration of either NO or N02 by 1 - 1.5%.

Agreement for the latter two species was typically better than 0.5%, thus

offering further verification for both the NO SRM and N02 permeation standards.

Work is continuing on this project. However, our results to date suggest that

the presently accepted value for the 03 cross section may have to be lowered by

1-1.5%, in almost exact agreement with the recently obtained direct UV

absorption measurements of Mauersberger

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16. Technical Accomplishments of a Three -Year NBS-DOE Program for the

Development of Standards and Reference Methodology for C02 in Air

E.E. Hughes, I.L. Barnes, J. Elkins, R.C. Myers, P.A. Johnson, and W.L.

Zielinski, Jr.

The long-term data record at Mauna Loa and other global sites has

demonstrated that global atmospheric carbon dioxide (C02) levels have been

increasing markedly over the past three decades, from 316 ppm in 1958 when

continuous monitoring was initiated to 345-350 ppm in 1985. Such monitoring is

needed to quantify accurately the temporal and long-term changes in atmospheric

C02 to assess future impacts of these changes on global warming and climate.

During this period, standards to calibrate continuous monitoring were provided

by the Scripps Institution of Oceanography (SIO) at the University of

California, La Jolla.

To ensure the long-term availability of C02 gas standards, an interagency

research program having three basic components was established to institutionalize the availability of such standards at the National Bureau of Standards. These three research components were: (1) the development of highly

accurate and stable CO 2 in air Standard Reference Materials (SRMs) over the

300-400 ppm range of interest; (2) a research evaluation of the equivalency of

gravimetry (employed by NBS) and manometry (employed by SIO), and (3) the

research development and evaluation of a second reference method at NBS to

independently confirm NBS gravimetric values for the future ( isotope - dilution

mass spectrometry [ID-MS]).

This program has led to the development of seven batches of stable SRM's

for C02 in air having a 95% concentration uncertainty not exceeding 0.1%

relative, covering the important range of 330-380 ppm (nominally at 330, 340,

350, and 370 ppm). Additional SRM's are in process or planning for 300 and 360

ppm, with wider range standards (at 200 and 1000 ppm) for agriculture research

on C02 effects. Intercomparison studies between NBS and SIO revealed some slight differences (which appear to be resolvable) and generally excellent

agreement in C02 concentrations determined in identical standards, the results

of which confirm that the use of NBS SRM's will ensure the long-term scientific

continuity of the existing monitoring data record. Finally, a computercontrolled ID-MS system has been completed and currently is under final

evaluation for accurate C02 measurements in NBS SRM's. The ID-MS system is

based on the use of three Faraday cups to simultaneously collect signals at m/e

44, 45, and 46, and the use of a computer program to collect and deconvolute

the data.

A detailed report describing the activities and accomplishments of the

three separate components of this program has been published for world-wide

distribution to researchers and programs involved in carbon dioxide research

("High Accuracy Standards and Reference Methodology for Carbon Dioxide in Air,"

Report No. TR033, DOE/PR- 06010 , June 1986). This joint report of DOE's Carbon

Dioxide Research Division and NBS' Center for Analytical Chemistry is available

from the National Technical Information Service, Springfield, VA 22161.

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1 7 . Assessment of the Air Matrix Effect in the Non-Dispersive Infrared

Analysis of C02 in Air Standards

R.C. Myers, E.E. Hughes, and W.L. Zielinski, Jr.

Global programs for monitoring the atmospheric level of carbon dioxide

(C02

) and its change over time rely on data generated by a non=dispersive

infrared (NDIR) analyzer that is specific for C02

. Such analyzers have

routinely been calibrated by the use of standards of C02 in a nitrogen or air

matrix. It has long been established, however, that a C02 in air standard will

produce an NDIR signal that is lower than that produced from a standard

containing the same concentration of C02 in nitrogen. This matrix effect

results in an error in the order of 4 ppm for air. The effect is caused by a pressure -broadening of the C02 response by oxygen (in a C02 -in-air matrix),

resulting in a decrease in the amplitude of the response relative to nitrogen.

To further complicate this issue, argon (present in real air) also

decreases the NDIR signal. On an absolute basis, preliminary results indicate

that the argon effect may be greater than that of oxygen; however, on a real

air basis the argon and oxygen effects appear to be of the same magnitude, and

may, to a first approximation, be additive. To illustrate, if one compares the

NDIR signal for three standards having the same C02 concentration, one in pure

nitrogen, one in pure oxygen, and one in pure argon, the signal for the oxygen

and argon standards are approximately 19 and 25 ppm lower, respectively, than

that obtained for the nitrogen standard. However, since real air has a composition of 21% oxygen, 0.93% argon, and 78% nitrogen, the NDIR air matrix

effect for a 1% difference in argon and oxygen is in the order of 0.25 and 0.2

ppm, respectively. These effects emphasize the importance of knowing the

matrix composition of the standards being used to calibrate NDIR equipment ' for

accurate measurements of atmospheric C02

. The use of calibration standards

that contain no argon may result in an error in the order of 0.2 ppm; using

standards that contain only nitrogen may result in an error in the order of 4

ppm; using different standards of C02 in air that contain varying matrix

compositions may result in a data scatter that would be difficult to interpret

if such compositional differences are unknown or appropriate corrections for

matrix differences are not applied. Since researchers involved in global

monitoring of atmospheric C02 routinely report their data to at least the

nearest 0.1 ppm and are extremely interested in detecting subtle seasonal

changes in atmospheric C02 , accurate calibration of NDIR analyzers is essential. To quantitatively correct NDIR responses for differences in the air

composition of C02 in air standards, the exact effects must be known and be

predictable for changes in the composition of the air matrix. Research is

currently being extended in this area to further this understanding and

predictability. The results of this research should be directly extendable on

a relative basis to other NDIR analyzers used by the atmospheric C02 research

and monitoring community.

18 . Assessment of the Absolute Error in the Use of Primary Gravimetric

Standards for the Development of C02 Air SRMs for Global Monitoring of

Atmospheric CCL Changes

E.E. Hughes, J. Elkins, R.C. Myers, H.L. Rook, and W.L. Zielinski, Jr.

The certification of gaseous SRMs involves (a) the preparation of primary

gravimetric standards bracketing the concentration range of the gas mixture in

a homogeneous batch of approximately 50 cylinders, (b) the assignment of

156
concentration of the gas mixture in a sample taken at random from the batch

("batch standard") by analytical intercomparison with the primary standards,

and (c) the assignment of certified concentrations to the remaining samples in

the batch by analytical intercomparison with the batch standard. The total

uncertainty (at 95% confidence) assigned to the certified concentration is

estimated by summing, in quadrature, the total error due to preparation of the

gravimetric primary standards and the errors associated with the two principal

analysis steps. The analytical uncertainties are determined directly from the

analytical data; the assessment of the error in the primary gravimetric

standards, hence, represents a critical control point in the overall

certification process.

In the case of C02 -in-air SRMs , the two analytical errors are of the same magnitude, and each are in the order of 0.02-0.05 ppm. To assess the error in

the preparation of the primary gravimetric standards, one must sum the individual component errors due to the preparation steps. These errors include: the errors in the weights used in weighing the pure C02 and air reagents; the

weighing imprecision; the measurement of the purity of the C02 ; the molecular

weight determined by careful analysis of major and minor components of the air

reagent; and any transfer errors associated with the transfer of the reagents

into the pre-weighed, evaluated primary cylinder. The random error comprising

these individual errors can be assessed by determining the difference between

gravimetrically-calculated concentrations and concentrations obtained from a parabolic regression of the gravimetric concentrations against voltages

obtained by high-precision non-dispersive infrared (NDIR) analysis. Independent intercomparisons with another absolute method for C02 (manometry) have

indicated the absence of a large systematic error in the gravimetric procedure.

Research studies were carried out recently to verify the internal

consistency of sets of primary gravimetric standards for C02 -in-air by regressing NDIR signals against gravimetric concentrations over a range of 270-410

ppm. In addition, research was carried out to intercompare the gravimetric

method with an alternative gravimetric method involving the intermediate

preparation of a 1.5% C02 -in-air primary standard from which gravimetric

primaries in the 270-410 ppm range were directly prepared. This alternative

method ( "double -dilution" ) produced primaries having an apparently greater

internal consistency than the standard method (i.e., lower mean residuals

between gravimetric and NDIR-correlation values) . This second method was evaluated since it had been determined that the largest individual error in the

gravimetric procedure was due to weighing and a greater weight of C0 ? reagent

could be used in this method. Current results indicate that it is feasible to

prepare a set of primary gravimetric standards for C02 -in-air with a total

uncertainty on the order of 0.1 ppm or less. Long-term analyses (over 5 years)

have shown primary standards and SRM's to be stable.

19 . Characterization of the Temperature Dependence of the Infrared Band

Streneths of Halocarbons F-ll (CC1 3 F) and F-12 (CC1 2 F2

) Using a Cryogenic

Gas Cell and FT-IR Spectrometry

J. Elkins and R. Sams

Halocarbons F-ll (CC1 3 F) and F-12 (CC1 2 F2

) have strong absorption bands in

the infrared "atmospheric window" for the absorption of terrestriallyirradiated infrared (IR) energy. Releases of these halocarbons into the

atmosphere from anthropogenic activities may increase the surface temperature

of the earth ("greenhouse effect"). Band strength measurements can be obtained

157
by FT-IR analysis; such measurements relate the amount of IR radiation absorbed

per molecule, which is important in calculating the radiative budget of the

atmosphere. Few such measurements exist for these halocarbons at room temperature; even fewer results are available at the lower temperatures that are representative of those in the upper atmosphere.

Research was carried out using an FT-IR spectrometer and a specially

designed cryogenic gas cell to measure the band strengths of these halocarbons

in the atmospheric window between 8 and 16 microns at a resolution of 0.06 cm

-1

, at three temperatures: 297, 273, and 238 K. The cryogenic cell was a cylindrical stainless - steel cell having a vacuum maintained between two walls

(for insulation); temperature-controlled by circulated, refrigerated ethanol;

three platinum resistance thermometers and Csl internal and KBr external

windows. The cell temperature was maintained to within 1 K at 297 and 273 K,

and to within 2 K at 238 K.

The band strengths were found to be constant within experimental error

over the range of temperatures studied. The shape of the bands, however,

showed a temperature dependence, being narrower and of higher amplitude with

decreasing temperature. Specific band strengths were determined for halocarbon

F-ll in three principal IR ranges (760-880, 1020-1120, and 900-960 cm

-1

), and

for halocarbon F-12 in two ranges (855-950 and 1050-1200 cm

-1

). These results

should be of interest to atmospheric scientists concerned with accurate

measurements of these halocarbons in the atmosphere , and show a temperature

dependence when using absorptivities based on band amplitude but not on band

area (i.e., band strength).

20 . Development of a Seventeen-Component NBS -Traceable Volatile Toxic Organic

Gas Standard at 10 ppb for GC-MS Calibrations

G.C. Rhoderick and W.L. Zielinski, Jr.

Analyses of ambient air samples for volatile toxic organic compounds are routinely conducted using GC-MS systems that previously have been calibrated

with appropriate gas standards. Such calibrations are tedious and prone to

calibration errors when several standards must be used to cover a sufficient

number of organic compounds. In an attempt to relieve this situation, research

was conducted at NBS to assess the feasibility of developing a gas standard

containing a substantial number of these compounds.

The mixture was compounded by initially preparing two eight-component

mixtures using a microgravimetric procedure established here. One of the pure

organics was quantitatively introduced into a pre-weighed evacuated cylinder by

the standard microgravimetric procedure. Following this, a pre -calculated

amount of each of the two eight-component mixtures was transferred to the same cylinder, which was then pressurized with a pre -calculated amount of pure

nitrogen gas (the matrix). The resulting mixture contained the following

organics

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bromoe thane

chloroform

1.2-

dichloroe thane

1,1,1- trichloroe thane

trichloroethylene

1.2-

dibromoe thane

toluene

ethylbenzene

o-xylene

vinyl chloride monomer

trichlorofluorome thane (F-ll)

carbon tetrachloride

1 , 2 -dichloropropane

benzene

tetrachloroethylene

chlorobenzene

styrene

The concentrations of the individual organics were determined by

analytical intercomparisons with primary gravimetric standards that had been

independently verified for accuracy. Analyses were carried out by gas chromatography using a linear temperature program (45 °C for 3 minutes, followed by

a 8 °C/min increase to 220 °C) , a column of 1% SP-1000 on 60-80 mesh Carbopack

B, a N2 carrier gas flow of 30 mL/min, a gas sampling valve and loop, and

flame- ionization and electron-capture detection.

This standard represents the most complex, stable, ppb concentration

calibration mixture ever prepared. The standard was developed under an NBS-EPA

interagency program for EPA/EMSL/RTP , and has already been used for calibrating

GC-MS analyses of field samples taken from a major industrial area.

21 . Development of NBS -Traceable Gas Standards to 1 ppb for Dry Acid

Deposition Studies

W.D. Dorko and Z.T. Cai

Meaningful measurements to study- dry acid precipitation require

characterized gas standards for acidic molecules at the 1 ppb level, the major

compounds being S02 , NO and N02

. The most useful type of standard is a compressed gas mixture contained in a high pressure cylinder. However, there

are no cylinder standards available at this level for either of the three

mentioned gases. These gases exhibit reactive and corrosive properties,

therefore, special precautions are required when trying to prepare stable gas

mixtures of them at any concentration and the difficulties increase as the

concentration levels decrease.

The next most convenient method for providing gas calibration standards is

by dynamic dilution, where the final mixture flows from a blending process

rather than from a contained static mixture. The input for the gas of interest

can be a permeation device (if appropriate) or a higher concentration cylinder

mixture. Due to practical limitations in the maximum dilution ratio (generally, about 100:1) low concentration inputs to the dilution system must be used

to attain an output concentration of 1 ppb. In this program, specially prepared cylinder mixtures containing nominal concentrations of either 100 ppb,

S02 or NO were evaluated for long-term stability. A dynamic dilution system

consisting of in-house calibrated mass flow controllers was rigorously characterized using inputs either from thermostatically controlled S02 and NO., permeation tubes or from higher concentration cylinder mixtures of S02 and NO, and

appropriate detectors. The 100 ppb cylinder mixtures are then used as inputs

to the dilution system to produce calibrating mixtures ranging down to I ppb.

At these low concentration levels, however, background levels of the gaseous

analytes of interest in the dilution gas itself can represent a serious

problem. Sulfur dioxide may be removed by scrubbing, therefore several

materials were tested and the best one chosen as a scrubbing agent through

159
which the air is passed to provide both a zero and dynamic dilution diluent

gas. Nitric oxide is not easily removed by scrubbing, and therefore, the

"zero" gas is reacted with 03 to convert any NO to NQ2 before entering the NO

detector. An evaluation of the other possible sources of systematic error,

including reaction of the gaseous specie of interest with the transfer lines

and flow controllers prior to dilution, was found not to exceed 1.5% relative.

The characterized 100:1 dynamic dilution system and an NBS - traceable

stable compressed gas cylinder standard containing 100 ppb S02 in air have been

delivered to EPA for dry acid deposition studies. Similar standards for NO and

N02 are in progress.

22 . Comparison of Single-Component Standards to Multi -Component Standards for

Use in the Analysis of Natural Gas

G.C. Rhoderick and E.E. Hughes

Precise compositional analysis of natural gas mixtures requires that

specific quantifications be made for each of the components present in such

mixtures. Since the natural gas industry has been in the process of changing

from billing customers by volume to billing by BTU and is evaluating the

feasibility and reliability of changing from traditional calorimetric determinations of BTU to compositional gas chromatographic determinations of BTU,

precise compositional analyses have become critically important. Errors asso- ciated with such analyses can have a substantial economic impact, considering

the huge volume of natural gas consumed annually. Precise compositional analyses of natural gas standards have been provided for national calibrations by

the Center for Analytical Chemistry for many years, with the most recent ones provided in 1985. The resultant NBS- traceable compositional standards are subsequently used to characterize natural gas secondary standards that are used

throughout the U.S. to provide data quality assurance in the production of

natural gas by the natural gas industry.

Single- and multi-component primary gravimetric standards prepared by NBS

are used for the compositional characterization of NBS- traceable natural gas

standards. The error associated with the use of both single- and multicomponent standards had not previously been evaluated. While multi-component

primary standards may simulate the compositioji of natural gas mixtures being

analyzed, the preparation of single - component primary gravimetric mixtures is

simpler. Research studies were carried out to assess the relative error in

using single-component and multi - component primary gravimetric standards.

Several simulated natural gas mixtures containing methane, seven higher

hydrocarbons, nitrogen, and carbon dioxide were obtained. Concentrations of

the components of these mixtures were determined from gas chromatographic

calibrations using multi -component primary gravimetric standards (containing

all of the components of these mixtures) and from similar calibrations using

single -component primary gravimetric standards (containing different concen- trations for each component in a methane matrix) . The total concentration

uncertainty (95% confidence) of the individual components in the primary

standards did not exceed 0.5% relative.

The differences in the concentrations of the components of the mixtures,

obtained from the two types of calibrations, were small when the total differ- ences for all mixture components were considered. The difference in the con- centrations of the non-methane hydrocarbons in the mixtures between the single

160
and multi -component calibrations ranged from 0.02% relative (for ethane at 4

mole-%) to 1.2% relative (for ISO-pentane at 0.1 mole-%); however, these

differences were within the analytical imprecision, demonstrating that no real

difference existed using calibrations with single- vs. multi -component standards. Gas chromatographic analyses of methane revealed a slight decrease

(1.0%) in the methane response factor (peak area divided by concentration) when

identical sample sizes taken from pure methane (100%) and a series of primary

standards ranging down to 75% methane. Since methane is the main contributor

to the BTU value of natural gas mixtures, this finding emphasizes the

importance of using a methane standard that has a methane concentration quite

similar to that in the mixture being analyzed.

The effect of the total differences obtained "from calibrations using

single- vs. multi -component primary standards on the heating value of analyzed

natural gas mixtures was only 0.2 BTU, which is well within the typical

uncertainty of 1 BTU for a natural gas sample. This research indicates that

carefully prepared single-component standards may be used in place of multicomponent standards in precise compositional analyses of natural gas mixtures.

23 . Technical Up-Grade of Analytical Gas Mass Spectrometer

W.D. Dorko and E.E. Hughes

The Gas Metrology Group's gas mass spectrometer (a CEC 21-103-C) was installed in 1961. It is a magnetic sector instrument with a Faraday cup

detector which has excellent linear response characteristics over a wide

concentration range. It also is equipped with a batch inlet system for direct

entry of pure gases, gas mixtures, or volatile liquids. This instrument plays

a key role in the Group's research and development activities in the preparation and evaluation of primary gas standards for the certification of gaseous

SRMs . It is used in the purity assay of reagent gases and as one of several

techniques for verifying major and/or minor components in the final gas

mixtures. It also is used frequently as the primary analytical technique, in a variety of other agency, university, and industrial projects. The Division's

Atmospheric Chemistry Group has modified part of the instrument for use in

determining the CO and C02 in gas samples produced by the oxidation of very

small amounts of atmospheric carbonaceous material.

Over the past years, a number of the original components of this system

have been replaced with components of improved technology. However, the

system's three main circuits (ionization region control circuit (isotron), high

voltage power supply circuit, and magnet power supply and control circuit)

remained. These utilize 1950' s technology involving vacuum tubes, which often

are difficult to obtain. Furthermore, these circuits were aging to the point

that the overall performance was frequently marginal and unpredictable.

During 1986, these three vacuum tube-based circuits were replaced with

specially designed solid-state modules that incorporate modern technology. The

design of these modules was developed as a single purchase package, such that

the connection of a module to other modules or to other components of the mass spectrometer was accomplished with cables and connectors without hard-wiring.

This allows great flexibility in configuring the system and an efficient use of

space

The up-graded mass spectrometer now is operating better than it did when

it was first acquired in 1961. Its performance is excellent, stable,

161
predictable, and more versatile. Projects that require isotope quantitation

can now have data generated by magnetic scanning instead of by electrostatic

scanning. The magnetic scan provides better quantification and statistics due

to a new capability for unattended, automatic magnetic up-field and down-field

scanning. The electrostatic and magnetic mass scanning rate can be linearly

adjusted from very fast to very slow. This allows for a very rapid qualitative

survey scan of an unknown sample, or for the development of quantitative data

at slower rates. The ultimate instrument resolution (e.g., separate D 2 from

He) can be achieved by using even slower rates. In addition, the accelerating

voltage and magnetic field strength (using a new Hall probe) can be read

accurately from the front panel for calculating fragment mass numbers for

identifying unknown sample components.

In summary, the up-graded mass spectrometer not only exceeds its original

performance specifications, but now contains useful features that were not

originally included.

24 . Chemometrics : National and International Activities Related to

Nomenclature. Detection, and Reporting of Analytical Data

L.A. Currie

During the past year, significant efforts have been devoted to central

issues related to the performance characteristics of the Chemical Measurement

Process (CMP) . The primary channels through which these efforts have taken

place were the Quality Assurance Task Force (QATF)' of the Center for Analytical

Chemistry, the International Union of Pure and Applied Chemistry (IUPAC), the

International Atomic Energy Agency (IAEA) , and the American Chemical Society

(ACS). Besides these four rather intensive activities, which will be described

below, requested guidance on the treatment of detection limits and analytical

uncertainties has been given to nuclear power industry personnel, an American

National Standards Institute committee developing performance criteria for

radiobioassay, and an NBS working group on the expression of measurement

uncertainties. This last group is charged with framing NBS inputs for

international efforts through the International Standards Organization.

Work performed as a member of the QATF included the development of a draft

document, "Guidelines for Characterizing the Chemical Measurement Process and

the Reporting of Analytical Results." Primary cooperation in this effort was given by the other two subcommittee members, J.K. Taylor (550) and R. Zeisler

(551). The document presents recommendations concerning many issues arising in

the characterization of the CMP, ranging from definitions of the principal

performance characteristics, to means for estimating them on the basis of

statistical approaches as well as chemical knowledge, to recommendations for

control, treatment of multicomponent data, and the reporting of results. A

summary table is included, containing symbols, terminology, references, and

estimation and reporting guidelines.

In parallel with the QATF activity was work for the IUPAC Commission on Analytical Nomenclature. Final work is underway on reports to the Commission

entitled "Recommendations for Nomenclature in Evaluations of Analytical

Methods" and "Recommendations for the Presentation of Results of Chemical

Analysis." The latter effort is being carried out in cooperation with

G. Svehla, former Chairman of the Commission, who prepared the initial drafts.

162
The IAEA has developed special needs in the area of detection limits, in

connection with its international comparison program and its coordinated

research programs involving trace analytical measurements in bioenvironmental

matrices. As a result, a special Consultants Meeting on the Limit of Detection

(LOD) was held last December at IAEA headquarters, where Agency scientists

headed by R.M. Parr plus five international experts met to address the problem

and draft a report or manual to be used in the Agency programs. The difficulties treated were manifold. Results of intercomparisons showed, for example,

that diverse terminology and numerical expressions for the LOD were in use. More serious, however, was the fact that totally inconsistent results were being reported: in some cases trace elements were reported by some laboratories at orders of magnitude higher concentrations than the detection limits of

other laboratories which reported "none detected." A primary focus for the

manual which is in preparation is to force attention to measurement quality in

the region of the LOD, especially through rigorous control of matrix

corrections and realistic assessment of the blank.

A Symposium on "Detection Limits: from Basic Concepts to Practical

Applications," was organized at the invitation of the Analytical Division of

the ACS for the spring meeting in New York in April 1986. The two day, four

session meeting treated the topic from quite a broad perspective. All papers

were invited, and they ranged from fundamental statistical concepts and

fundamental chemical limitations to public policy issues, and important

applications in clinical, geo-, forensic, and environmental chemistry. A

symposium volume, to be published by the ACS, is now in preparation. It will

contain two chapters by L.A. Currie, one consisting of an overview of the

evolution and importance of the concept; the other, summarizing approaches

developed for the special radioactivity monitoring needs of the Nuclear

Regulatory Commission and the forementioned bioenvironmental trace analysis

requirements of the IAEA.

25 . Microchemical and Isotopic Carbon: Accuracy, Precision and

Applicabilities of an Improved Measurement Process Coupled to Accelerator

Mass Spectrometry

R.M. Verkouteren and L.A. Currie

The abundance of the naturally- occurring radioisotope 14 C in carbonaceous

materials reflects the systematics behind carbon cycle geochemistry, receptor

modelling, and the chronology of natural and anthropogenic artifacts. Of

particular interest are radiocarbon abundances in samples containing only very

small amounts of total carbon (< 100 ^g) ; e.g., specific chemical subfractions

in atmospheric air and aerosol samples, amino acid fractions from ancient

bones, and carbonaceous particles from glaciers and ice sheets. When extracted

from a contaminated host matrix, separated fractions should give reliable

radiocarbon values.

Samples are processed in a closed system to prevent atmospheric contact,

hence minimizing that source of contamination and avoiding many operator

dependencies. Gaseous or particulate samples are thermally and/or chemically

processed to separate and purify the carbonaceous species of interest, then

combusted to C02 and cryotransferred to a reduction tube where elemental carbon

is deposited on an iron wool catalyst at 600 °C. Complete reduction, monitored

by recording the pressure drop and confirmed by gas chromatography of the

residual gas mixture, is achieved within twelve hours. Total carbon analysis

by LECO of the iron wool blanks Indicates 0.4 ±0.5 /j.g C per target disc.

163
To assess the accuracy, precision and applicabilities of this measurement

process, targets were generated containing from 50 to 990 micrograms of car- bon. Carbon- 12 ion currents were measured and found to be sufficiently intense

(from 5-70% those of pure graphite) to enable beam focusing and to give

statistically meaningful count rates. With 100 micrograms of "dead" carbon,

the 14 C blank was 0.006 (fraction of modern level); 600 micrograms of "dead"

carbon gave f^ < 0.001 (> 43,000 yr BP). Measurement of NBS oxalic acid con- taining 550 ng C gave f^ - 1.339 ± 0.028, within one standard deviation of the

true value, and indicating a measurement imprecision of 2.1% (RSD) . In progress is an assessment of accuracy and precision for measurements of smaller

samples, as well as samples diluted with isotopically pure 12 C02 to larger

size

In conjunction with carbon isotopic measurements of small samples,

radiocarbon enhancement via thermal (hot wire) diffusion of CO is being

pursued. Computer simulations of microchemical diffusion in the column at the

NBS indicate a maximum 14 C enhancement of 300-500x in 1-2 months, corresponding

to an increase in the conventional radiocarbon dating limit by about 40,000

years. Investigations into the effect of ternary mixtures (CO + N2

) on radiocarbon enhancement factors are also planned. An important and interesting byproduct of this research will be the ability to study the rare terrestrial

nuclear reactions, per se . thus possibly gaining knowledge of "paleo" neutron

fluxes in geological and glaciological contexts.

26. 1

C in Elemental Carbon and Trace Organics: The Integrated Air Cancer

Proi ect

G.A. Klouda, A.E. Sheffield, and L.A. Currie

This year's activities, related to the chemical and isotopic ( 14 C)

composition of urban atmospheric carbonaceous particles, involved participation

in EPA's Integrated Air Cancer Project (IACP). The purpose of the IACP was to

identify the chemical constituents, biological activity, and isotopic composition of the fine particles collected during the winter of 1984 and 1985 in

Raleigh, North Carolina and Albuquerque, New Mexico. The amount of elemental

(non-volatile or soot) and organic (semi-volatile) carbon extractable from the

fine particles in addition to their 14 C abundance was proposed for tracing

mobile (fossil, 14 C - 0) vs residential (wood burning) combustion sources contributing to winter time pollution episodes. Radiocarbon measurements of

these carbon fractions and PAH extracts are valuable inputs to the receptor

model for source apportionment. Also, 14 C measurement and AMES mutagenic

bioassay of the bulk organic material would yield the origin of this biologically active or inactive material; important for human health reasons.

Our specific role was to develop and validate a thermal or chemical method

to separate organic (C Q ) and elemental (C e ) carbon fractions from the total

particulate material for quantitative determination and subsequent 14 C measurements. Work began by investigating thermal methods with important considerations given to 1) removal of artifact carbon, e.g., adsorbed atmospheric C02 , 2) the prevention of "charring" (low temperature pyrolysis) of organics, and 3)

the determination of carbonate carbon; all of which could potentially alter the

true C Q and C e

14 C abundances.

An initial experiment was performed to study artifact carbon by applying a vacuum extraction/thermal oxidation technique to a prefired blank quartz

filter. Results showed that 2 /ig/cm2 of artifact carbon was adsorbed on the

164
filter and that all of this carbon was removed by vacuum desorption. Future

experiments related to artifact carbon will include determination of the

adsorption per unit area of a known volatile compound on quartz fiber filter

material and its vacuum/thermal desorption characteristics.

Thermal separation techniques investigated were applied to known organic

compounds, mixtures of organic compounds and soot or graphite, and EPA IACP

ambient samples. Clean (without charring) CQ/C e separations and good yields

(-95%) were obtained when these thermal techniques were applied to known

compounds and mixtures. In contrast, thermal results of C 0 and C e from the

ambient particles were significantly different than expected, suggesting

problems with charring of organic carbon. In an attempt to resolve the

question of charring, a wet oxidation technique (cf. Schultz, 1962) was applied

at NBS to aliquots of the same filters to remove quantitatively organic carbon

with HN03 and thermally oxidize and volumetrically determine the remaining

carbon (C e

)

A comparison of thermal analysis and thermal/optical analysis (R. Cary)

for separation of C Q and C e was made and results indicate that as much as 20 to

30% of the total carbon chars at low temperature. The thermal/optical approach

utilizes the optical transmission of the filter during thermal volatilization

to correct for any charring of organic material. NBS C e results by wet

oxidation/thermal combustion correlated well with the thermal/optical method.

These preliminary results suggest that charring may be difficult to avoid

during the thermal process and that the wet oxidation treatment followed by

thermal combustion of the residue may be the most reliable means for isolating

C e for 14 C measurements.

Carbonate carbon was determined on aliquots of the same IACP filters

analyzed thermally for C Q and C e

. Samples were treated with hot phosphoric

acid and the evolved C02 was measured volumetrically. For all filters analyzed, carbonate carbon was not detected above the system blank ('2 /ig or equivalent to < 1 /ig/cm2

) and, therefore, is not a significant influence on the

thermal C e fraction.

Initial 14 C results, determined primarily on total carbon to date, show

Albuquerque, NM, fractions of contemporary (biogenic) carbon (f^-) to be 0.58 ±

0.06 for a daytime sample and 0.80 ± 0.03 for a nighttime sample. A Raleigh,

NC , nighttime sample gave an fc of 0.88 ± 0.04 (fc - 1.00 for 100% biogenic

carbon). The results indicate the major impact of woodburning at night in both

cities during the winter.

165
C. Outputs and Interactions

(Gas and Particulate Science Division)

1 . Publications

Benninghoven, A., Colton, R. J., Simons, D. S., and Werner, H. W. , Eds.,

Secondary Ion Mass Spectrometry SIMS V, Springer Series in Chemical

Physics . 44, Springer-Verlag, Berlin, (1986).

Bright, D. S., The Lispix Image Analysis System with Applications to

Microscopy, (Submitted to Journal of Microscopy 1986).

Bright, D. S. and Steel, E. B., Microscope Calibration with Automated Analysis

of Images of Length Standards," (Submitted to J. Microscopy 1986).

Bright, D. S. and Steel, E. B. , Automated Analysis of Regular Spot Patterns in

Electron Diffraction Images, (Submitted to J. Microscopy 1986).

Bright, D. S. and Newbury, D. E., Bright Field Image Correction Using Various

Image Processing Tools, Microbeam Analysis . (1986)

Bright, D. S. and Newbury, D. E. , Distance Mapping for Shape Characterization

of Alloy Grain Boundaries, Microbeam Analysis . (1986).

Bright, D. S., An Automated Image Thresholding Method Using Sharp Edges,

(Submitted to Journal of Microscopy 1986)

Bright, D. S. and Steel, E. B., Two Dimensional Top Hat Filter For . Extracting

Spots and Spheres from Images, (Submitted to Journal of Microscopy 1986).

Byrd, G. D., Fatiadi, A. J., Simons, D. S., and White V, E., Laser Desorption

Mass Spectrometry of Some Salts of Squaric Acid, Organic Mass

Spectrometry, 21 , 63, (1986).

Currie, L. A., The Limitations of Models and Measurements as Revealed through

Chemometric Intercomparison, NBS Journal Research, 90, 409, (1986).

Currie, L. A., Use of Simulation Data Sets for Assessing Interlaboratory

Pattern Recognition Accuracy, Optical Engineering, 24, 1004, (1985).

Currie, L. A., Detection Limits in Analytical Chemistry, Evolution and

Prognosis, (Submitted to Detection Limits, from Basic Concepts to

Practical Application, ACS Symposium Series 1985)

Currie, L. A. and Parr, R. M. , Perspectives on Detection Limits for Nuclear

Measurements in Selected National and International Programs, (Submitted

to Detection Limits, from Basic Concepts of Practical Application, ACS

Symposium Series 1985)

Currie, L. A., Klouda, G. A., Schjoldager, and Ramdahl , T., The Power of 1

C

Measurements Combined with Chemical Characterization for Tracing Urban

Aerosol in Norway, Radiocarbon, Vol. 28, No, 2a, (1986).

Currie, L. A., Klouda, G. A., Elmore, D., and Gove, H. E., Radiocarbon Dating

of Microgram Samples: Accelerator Mass Spectrometry and Electromagnetic

166
Isotope Separation, Nuclear Instrum, and Methods in Physics Research B12 , 396-401, (1985).

Copien, T., Currie, L. A., Fehn, U. , Johnson, V. , Phillips, Shea, M. , and

Stuiver, M. , Application Areas and Needs in the USA, The Future of

Accelerator Mass Spectrometry in the USA . Workshop Report, D. Elmore, Ed.,

(University of Rochester, May 1986).

Dorko, W. D. and Hughes, E. E. , Special Calibration Systems for Reactive Gas

and Other Difficult Measurements, (Submitted to Proceedings ASTM D-22

Conference, 1986).

Etz, E. S. and Travis, J. C., Stokes and anti-Stokes Fluorescence of Er(3+) in

the Raman Spectra of Erbium Oxide and Erbium Glasses, (Submitted to

Proceedings of the Tenth International Conference on Raman Spectroscopy

ICORS-X, University of Oregon, 1986).

Etz, E. S., Tomazic, B. B., and Brown, W. E., Micro-Raman Characterization of

Atheroscelerotic and Bioprosthetic Calcification, (Submitted to Microbeam

Analysis 1986).

Fletcher, R. A. and Fatiadi, A. J., Laser Ionization Mass Spectrometry of

Chromatography Column Packing Material, Journal of Trace and Microprobe

Techniques (In review)

Fried, A., Sams, R. L. , and Dorko, W. D., Quantitative Tunable Diode Laser

Absorption Spectrometry for the Determination of Nitrogen Dioxide- in-Air

Compressed Gas Mixtures, (in WERB review for submission to Analytical

Chemistry) .-

Fried, A., Dorko, W. D., Sams. R. L. , Elkins, J. W. , and Cai, Z. T.,

Intercomparison of Tunable Diode Laser Chemiluminescence and Fourier

Transform Infrared Detection for the Determination of Nitrogen Dioxide- inAir Compressed Gas Mixtures, (in WERB review for submission to Analytical

Chemistry)

Fried, A. and Sams, R. L. , Tunable Diode Laser Absorption Spectrometry for

Ultra-Trace Measurement ^nd Calibration of Atmospheric Constituents, (To

be published in the American Society for Testing Materials, Volume:

Sampling and Calibration for Atmospheric Measurements 1986).

Gordon, G. E. and Sheffield, A. E., Variability of Compositions of Particles

Released by Coal-Fired Power Plants, Environmental Science of Fuels . ACS

Symposium Series, (in press 1986).

Grice, J. D., Van Velthuizen, J., Dunn, P. J., Newbury, D. E., Etz, E. S., and

Nielsen, C. H., Moydite, (Y, REE) B(0H) A (C03 ) , a New Mineral from EvansLou Pegmatite, Quebec, Canadian Metallurgist, (1986).

Houck, J. E. , Pritchett, L. C., Cooper, J. A., Olunez , I., Sheffield, A. E.,

Gordon, G. E., Dzubay , T. G., and Bennett, R. L. , Elemental Profiles of

Selected Sources in Philadelphia for Receptor Modeling Applications, (In

preparation 1986).

Hughes, E. E. , Standards for the Analysis of Natural Gas, in Gas Quality . G. J. van Rossum, Ed., Elsevier Science Publishers, 675-682, (1986).

167
Hughes, E. E. , Standards for the Measurement of Atmospheric Carbon Dioxide

Based on Absolute Gravimetry, Tellus (In press 1986).

Klouda, G. A., Currie, L.A. , Donahue, D. J., Jull, A. J. T., and Naylor, M. H.,

Urban Atmospheric 14 CO and 1A CH4 Measurements by Accelerator Mass

Spectrometry, Radiocarbon . Vol. 28, No. 2a, (1986).

Lindner, M. , Leich, D. A., Borg, R. J., Russ, G. P., Bazan, J. M. , Simons, D,

S., and Date, A. R. , Direct Laboratory Determination of the 187Re HalfLife, Nature, 320 . 246, (1986).

Marinenko, R. B., Myklebust, R. L. , Bright, D. S,, and Newbury, D. E., Digital

Quantitative Compositional Mapping with Defocus Corrections for Wavelength

Dispersive X-Ray Spectrometry, Proc . of the ll c^ International Congress on X-Ray Optics and Microanalysis, London, Ontario, Canada, (To be

published, 1986)

Marinenko, R. B., Myklebust, R. L. , Bright, D. S., and Newbury, D. E., Digital

X-Ray Compositional Mapping with 'Standard Map' Corrections For Wavelength

Dispersive Spectrometer Defocussing, (Submitted to Journal of Microscopy,

1986).

Marinenko, R. B. and Steel, E. B., NBS Standards for Microanalysis:

Certification and Applications, Journal of Trace and Microprobe

Techniques, (Accepted for publication, 1986).

Moens, M. , Adams, F. G., Simons, D. S., and Newbury, D.E., Investigation of

Interfaces in a Ni/Cr Multilayer Film with Secondary Ion Mass Spectrometry, Secondary Ion Mass Spectrometry SIMS V . Springer-Verlag , Berlin,

377-379, (1986).

Musselman, I. H., Simons, D. S., Small, J. A., and Linton, R. W. , The Use of

Single - Particle Standards for LAMMA Calibration, (Submitted to the Journal

of Trace and Microprobe Techniques 1986)

Myklebust, R. L. , Newbury, D. E., Marinenko, R. B., and Bright, D. S., Defocus

Modeling for Compositional Mapping with Wavelength- Dispersive X-Ray

Spectrometry, Microbeam Analysis . San Francisco Press, (1986).

Myklebust, R. L. , Marinenko, R. B., Newbury, D. E., and Bright, D. S.,

Quantitative Compositional Mapping on an Electron Microprobe, Electron

Microscopy and Analysis 1985 . Institute of Physics, London, 219-263,

(1985).

Newbury, D. E., The Role of Electron Microprobe Techniques, (To be published in

the Journal of Trace and Microprobe Techniques, 1986).

Newbury, D. E., Bright, D. S., Williams, D., Sung, C. M. , Page, T., and Ness,

J., Application of Digital SIMS Imaging to Light Element and Trace Element

Mapping, Secondary Ion Mass Spectrometry SIMS V . Springer-Verlag, Berlin,

261-263, (1986).

Pella, P. A., Newbury, D. E., Steel, E. B., and Blackburn, H. B., Development

of National Bureau of Standards Thin Glass Films for X-Ray Fluorescence

Spectrometry, Analytical Chemistry, .58, 1133-1137, (1986).

168
Pella, P, A., Tao, G. Y. , and Lachance, G. R. , Intercomparison of Fundamental

Parameter Interelement Correction Methods-Part 2, X-Ray Spectrometry, 15,

(1986) .

Rhoderick, G. C. and Hughes, E. E. , Comparison of Single Component Standards to

Multi-Component Standards for Use in Analysis of Natural Gas, in Gas

Quality . G. J. van Rossum, Ed., Elsevier Science Publishers, Amsterdam,

711-719, (1986).

Rook, H. L. , and Taylor, J. K. , Eds., Precision and Accuracy Assessment Derived

from Calibration Data, (Accepted for publication in ASTM Special

Publication, 1986)

Rook, H. L. , Ed., Special Issue on Standards for Microprobe Analysis, Journal

of Trace and Microprobe Techniques, 1986.

Rouse, R. C. , Peucor, D. R. , Dunn, P. J., Simmons, W. B., and Newbury, D. E. , Wheatleyite, Na2 Cu(C2 0 4 ) 2

• 2 (H2 0) , a Light Element and Trace Element

Mapping, (Submitted to American Mineralogist, 1986).

Sams, R. L. and Fried, A., Spin Splitting in the V 3 Band of NO2 , (In WERB

Review for submission to Journal of Molecular Spectroscopy 1986)

Sams, R. L. and Fried, A., Potential Sources of Systematic Errors in Tunable

Diode Laser Absorption Measurements, Journal of Applied Spectroscopy, 40,

24, (1986)...

Sheffield, A. E. and Gordon, G. E., Variability of Particle Composition from

Ubiquitous Sources: Results from a New Source-Composition Library,

Receptor Models for Source Apportionment: Real World Issues and Applications . Pace, T. G., Ed., Published by the Air Pollution Control

Association, 9-22, (1986).

Sheridan, P. J. and Musselman, I. H., Characterization of Aircraft-Collected

Particles Present in the Artie Aerosol; Alaskan Artie Spring 1983,

Atmospheric Environment, 19, 12 . 2159, (1986).

Simons, D. S., Single Particle Standards for Isotopic Measurements of Uranium

by Secondary Mass Spectrometry, (Accepted for publication in Journal of

Trace and Microprobe Techniques 1986).

Sleater, G., Crissman, J. M. , Humphreys, J. C., and Pella, P. A., The Effect of

X-Rays on The Polycarbonate Substrate of X-Ray Calibration Standards,

Analytical Chemistry, (Submitted 1986).

Small, J. A., Newbury, D. E., Leigh, S. D., and Myklebust, R. L. , Modeling of

Brerasstrahlung Radiation Produced in Pure-Element Targets by 10-40 keV

Electrons, (Submitted to Journal of Applied Physics 1986).

Small, J. A., Ritter, J. J., Sheridan, P. J., and Pereles, T. R., Methods for

the Production of Particle Standards, (Submitted to the Journal of Trace

and Microprobe Techniques 1986).

Small, J. A. , Leigh, S. D. , Newbury, D. E. , and Myklebust, R. L. , Modeling of

Electron- Induced Bremss trahlung Emission from Solid Targets, (Submitted to

Journal of Applied Physics 1986).

169
Small, J. A., Leigh, S. D., Newbury, D. E, , and Myklebust, R. L. , Continuum

Radiation Produced in Pure -Element Targets by 10-40 keV Electrons: An

Empirical Model, (To be published in Microbeam Analysis 1986).

Steel, E. B., A High Purity Germanium X-Ray Detector on a 200 kV Analytical

Electron Microscope, Microbeam Analysis, (1986).

Steel, E. B., Hartman, A., Hembree, G., Sheridan, P., and Small, J. A.,

Performance Standards for Microanalysis, (Accepted for publication in the

Journal of Trace and Microprobe Analysis 1986)

Tomazic, B. B., Etz , E. S., and Brown, W. E., Nature and Properties of Cardio-

'vascular Deposits, (Submitted to Scanning Electron Microscopy 1986).

Vrebos, B. A. R. and Pella, P. A., Uncertainties in Mass Absorption Coefficients in Fundamental Parameter X-Ray Fluorescence Analysis, X-Ray

Spectrometry, (Submitted 1986).

Welch, M. J., Sams, R. L. , and White, E., Photodissociation of Ions Generated

by Soft Ionization Techniques, Analytical Chemistry, 5J3, 890, (1986).

Zielinski, W. L. , Miller, W. R. , Ulma, G., and Wasik, S. P., Gas Liquid

Chromatography of Polychlorinated Biphenyl Congeners Between a Nematic

Liquid Crystal Phase and a Non-Polar Phase, Analytical Chemistry, (in

press 1986)

Zielinski, W. L. , Jr., Hughes, E. E., Barnes, I. L. , Elkins, J. W. , and Rook,

H. L. , High Accuracy Standards and Reference Methodology for Carbon

Dioxide - in- Air , Technical Report Series, U. S. Department of Energy, (In

press 1986 )

2 . Talks

Bass, A. M. , and Fried, A., "Ozone Absorption Coefficients," Air Force Workshop

on Atmospheric Transmittance, AFCLR, Bedford, MA, June 5, 1986.

Nunnermacker , Linda, Dickerson, R. and Fried, A., "A New Nitric Acid Calibration

System," 27 c ^ Rocky Mountain Conference, Denver, CO, July 14-18, 1985.

Fried, A. and Sams, R. L. , "Tunable Diode Laser Absorption Spectrometry for

Ultra-Trace Measurement and Calibration of Atmospheric Constituents,"

American Society for Testing Materials Conference, Boulder, CO, August 12-

16, 1985.

Fried, A., "Status Report of NO 2 Standards Normalization," NASA's Fourth

Science Meeting for the Global Tropospheric Experiment/CITE- 2 , Arlington,

VA, August 26-28, 1985.

Dorko, W. D. and Zielinski, W. L. , Jr., "New Gas Reference Material for

Measurement," Labcon Central, Chicago, IL, October 1985.

Elkins, J. W. , "Nitrous Oxide Measurements Off the Coast of Peru during 1985:

Response to the 1982 - 83 El Nino," GMCC , Boulder, CO, October 3, 1985.

Rook, H. L. , "Evaluation of Pilot Quality Assurance Program for AFTAC

Laboratories," U.S. Air Force CAD Meeting, October 23, 1985.

170
Elkins, J. W. , "Nitrous Oxide in the WOW Layer During NITROf, -85," Bigelow

Laboratory for Ocean Sciences, West Boothbay Harbor, Maine, October 28,

1985.

Elkins, J. W. , "Nitrous Oxide Off the Coast of Peru," Center for Earth and

Planetary Physics, Harvard University, October 29, 1985.

Pella, P. A., "Advances in X-Ray Fluorescence Analysis," Shanghai Institute for

Ceramics, Academia Sinica, Shanghai, China, November 7, 1985.

Pella, P. A., "Advances in X-Ray Fluorescence Analysis," Institute for

Geochemistry Academia Sinica, Guiyang, China, November 11, 1985.

Pella, P. A, , "Sample Preparation Techniques for Analysis of Geological Samples

by XRF," China National Nonferrous Metals Industry Cooperation, Guilin,

China, November 14, 1985.

Pella, P. A., "X-Ray Fluorescence Spectrometry at the U. S. National Bureau of

Standards," First Beijing Conference and Exhibition in Instrumental

Analysis, Beijing, China, November 18, 1985.

Pella, P. A., "Modern Trends in X-Ray Fluorescence Analysis," Institute of Rock

and Mineral Analysis, Ministry of Geology and Mineral Resources, Beijing,

China, November 19, 1985.

Fletcher, R. A., "Laser Microprobe Mass Analyzer: Soft Ionization Techniques

for Molecular Analysis," Joint Meeting of Microbeam Analysis Society and

American Society of Metals, Albuquerque, NM, November 20, 1985.

Small, J. A., "Microprobe Mass Analyzer: High Energy Ionization Techniques for

Elemental Analysis," Joint Meeting of Microbeam Analysis Society and

American Society for Metals, Albuquerque, NM, November 20, 1985.

Fletcher, R. A., "Intercomparison of Dichotomous and Personal/Portable

Samplers," American Association for Aerosol Research, Albuquerque, NM,

November 21, 1985.

Small, J. A., "Particle Collector for Microanalysis," American Association for

Aerosol Research Conference, Albuquerque, NM, November 22, 1985.

Currie, L. A., "General and Statistical Background," Consultants' Meeting on Detection Limits, International Atomic Energy Agency, Vienna, Austria,

December 2 , 1985

Elkins, J. W. , "Dissolved N2 0 and the Appearance of Two N2 0 Minima in Peruvial

Waters during NITROP-85," American Geophysical Union Ocean Science

Meeting, New Orleans LA, January 14, 1986.

Rook, H. L. , "Particle Identification by Digital Compositional Imaging,"

Argonne National Laboratory, January 27, 1986.

Newbury, D. E., "Compositional Mapping," New Mexico Society for Electron

Microscopy and Microanalysis, Albuquerque, NM, February, 7, 1986.

Bright, D. S., "Computers and Learning," George Washington University,

Graduate School, March 1, 1986.

171
Simons, D. S., "Laser Microprobe Mass Spectrometry," Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Atlantic City, NJ , March

12, 1986.

Newbury, D. E. , "Elemental Compositional Mapping of Microstructures by Electron

and Ion Microbeam Analysis," The Pittsburgh Conference on Analytical

Chemistry and Applied Spectroscopy, Atlantic City, NJ , March 13, 1986.

Bright, D. S., "Image Processing and Analysis Techniques for Electron Microscopy," Appalachian Regional Electron Microscopy Society, Charlotte, NC , March 21, 1986.

Fletcher, R. A., "Chemical Surface Analysis on Particles Using the LAMMA,"

Washington Area Aerosol Science Group, NBS Washington, D. C. , April 1986.

Marinenko, R. B., "Electron Microprobe Analysis at the National Bureau of Standards," Wells College, Aurora, NY, April 11, 1986.

Fried, A., "Tunable Diode Laser Spectroscopy," NBS Analytical Chemistry/

Materials ADABASE Science Workshop, NBS, Gaithersburg, MD, April 14, 1986.

Newbury, D. E., "Microbeam Analysis," NBS Analytical Chemistry/Materials

Science ADABASE Workshop, NBS, Gaithersburg, MD, April 14, 1986.

Currie, L. A., "Perspectives on Detection Limits for Nuclear Measurements in

Selected National and International Programs," National American Chemical

Society Meeting, New York, NY, April 17, 1986.

Simons, D. S., "Secondary Ion Mass Spectrometry - Overview," Chemical Process

Metrology Division, NBS, Gaithersburg, MD , April 17, 1986.

Zielinski, W. L. , Jr., "Gas Analysis and the Thermodynamic Basis for Separations," ADABASE and Materials Science Workshop, April 18, 1986.

Newbury, D. E., "Scanning Electron Microscopy and Microprobe Analysis,"

American Society for Metals Workshop, NBS, Gaithersburg, MD, April 21,

1986.

Newbury, D. E., "Secondary Ion Mass Spectrometry," American Society for Metals

Workshop, NBS, Gaithersburg, MD , April 21, 1986.

Hughes, E. E. , "Standards for the Analysis of Natural Gas," International

Congress of Gas Quality, Groningen, The Netherlands, April 24, 1986.

Rhoderick, G. C., "Comparison of Single Component Standards to Multi-Component

Standards for Use in Analysis of Natural Gas," International Congress on Gas Quality, Groningen , The Netherlands, April 24, 1986.

Newbury, D, E. , "Compositional Mapping: Your Investment in the Future,"

Institute for Materials Science and Engineering Seminar, NBS,

Gaithersburg, MD, April 29, 1986.

Klouda, G. A., "Progress in Source Apportionment of Atmospheric Carbon via M C

- Accelerator Mass Spectrometry," Aerosol Science Meeting, NBS,

Gaithersburg, MD , April 30, 1986.

172
Fletcher, R. A., "Laser Desorption of Organic Monolayer from Silver Films,"

Joint Meeting of the American Chemical Society of Washington and the

American Affiliates of the Royal Society for Chemistry, May 9, 1986.

Verkouteren, M. R. , "Preparation of Microgram Samples for Radiocarbon Analysis

via Accelerator Mass Spectrometry," Washington Chemical Society 90 th Meeting, Northern Virginia Community College, May 9, 1986.

Elkins, J. W. , Sams, R. L. and Wen, J., "Temperature Dependence on the Infrared

Band Strengths and Shapes for Halocarbons F-ll and F-12," American Geophysical Union Conference, Baltimore, MD, May 19 - 23, 1986.

Dorko, W. D. , "NBS Gas Standards for Calibrating Monitoring Equipment," NCASI

Meeting, Williamsburg, PA, June 1986.

Newbury, D. E. , "Applications of Secondary Ion Mass Spectrometry Image Analysis

in Materials Science," American Society for Mass Spectrometry, Cincinatti,

OH, June 9, 1986.

Bright, D. S., "Processing and Analysis of Images from a Cameca Ion Microscope," American Society for Mass Spectrometry, Cincinatti, OH, June 10,

1986.

Sams R. L. and Fried,

Some Selected NO

Spectroscopy, 41

16-20, 1986.

s£

A. , "Line Strengths and Pressure Broadening Widths of

Lines of Atmospheric Importance Using Diode Laser

Molecular Spectroscopy Symposium, Columbus, OH, June

Rook, H. L. and Fleming, R. F., "High Accuracy Neutron Activation for Reference

Material Certification," International Meeting on Nuclear Analytical

Methods, Orleans, France, June 19-20, 1986.

Small, J. A., "Intercomparison of PCM, SEM, and TEM for Analysis of Asbestos,"

1986 Johnson Conference, Johnson, VT, July, 1986.

Steel, E. B., "Asbestos Analysis Using the Transmission Electron Microscope,"

California State Department of Health, Berkeley, CA, July 1986.

Newbury, D. E., "Compositional Mapping by Electron and. Ion Beam Microanalysis,"

Institute for Materials Science and Engineering Seminar, NBS, Gaithersburg

MD, July 8, 1986.

Bright, D. S., "Bright Field Image Correction Using Various Image Processing

Tools," Microbeam Analysis Society/Electron Microscopy Society of America

Joint Conference, Albuquerque, NM, August 1986.

Bright, D. S., "Distance Mapping for Shape Characterization," Microbeam

Analysis Society/Electron Microscopy Society of America Joint Conference,

Albuquerque, NM, August 1986.

Etz, E. S., "The Role of Reference Samples in Raman Microprobe Analysis," ll c ^ International Congress on X-Ray Optics and Microanalysis (ICOM-11),

University of Western Ontario, London, Ontario, Canada, August 4 - 8,

1986.

173
Newbury, D. E. , "Compositional Mapping by Electron and Ion Beam Microanalysis

with Applications in Materials Science "Department of Materials and

Metallurgical Engineering New Mexico Institute of Mining and Technology,

Socorro, NM, August 5, 1986.

Marinenko, R. B., "Digital Quantitative Compositional Mapping with Defocus

Corrections for Wavelength Dispersive X-Ray Spectrometry," 11^ International Congress on X-Ray Optics and Microanalysis, London, Canada, August

8, 1986.

Newbury, D. E., "Compositional Mapping by Electron and Ion Beam Microanalysis

with Applications in Materials Science," Los Alamos National Laboratory,

Los Alamos, NM, August 8, 1986.

Newbury, D. E., "Strategy for Interpretation of Contrast Mechanisms in Scanning

Electron Microscopy: A Tutorial," Annual Conference of the Microbeam

Analysis Society and the Electron Microscopy Society of America,

Albuquerque, NM, August 11, 1986.

Small, J. A., "Electron Beam Analysis of Particles," Annual Meeting of the

Microbeam Analysis Society and the Electron Microscopy Society of America,

Albuquerque, NM, August 12, 1986.

Etz

E. S., "Micro-Raman Characterization of Atherosclerotic Bioprosthetic

Calcification," Annual Meeting of the Microbeam Analysis Society and the

Electron Microscopy Society of America, Albuquerque, NM, August 14, 1986.

Myklebust, R. L. , "Defocus Modeling for Compositional Mapping with WavelengthDispersive X-Ray Spectrometry," Annual Conference of Microbeam Analysis

Society and Electron Microscopy Society of America, Albuquerque, NM,

August 14, 1986.

Small, J. A., "Continuum Radiation Produced in Pure Element Targets by 10-40

keV Electrons: An Empirical Model," Annual Meeting of the Microbeam

Analysis Society and the Electron Microscopy Society of America,

Albuquerque, NM, August 14, 1986.

Newbury, D. E., "Initial Experience with Compositional Mapping Applied to

Materials Science," Annual Conference of the Microbeam Analysis Society

and the Electron Microscopy Society of America Albuquerque, NM, August 15,

1986.

Simons, D. S., "Determination of the Half-Life of Re-187 by Laser Microprobe

Spectrometry," Third International Laser Microprobe Mass Spectrometry

Workshop, Antwerp, Belgium, August 26, 1986.

Fletcher, R. A. , "Utilizing Pattern Recognition Spectral Analysis for Laser

Mass Spectrometry," 10 c ^ International Symposium on Microchemical

Techniques, Antwerp, Belgium, August 27, 1986.

Etz, E. S., "Stokes and anti-Stokes Fluorescence of Er(3+) in the Raman Spectra

of Erbium Oxide and Erbium Glasses," 10 c^ International Conference on Raman Spectroscopy (ICORS-10), University of Oregon, Eugene, OR, September

3, 1986.

174
Newbury, D. E. , "Application of Digital SIMS Imaging to Light Element and Trace

Element Mapping," Fifth International Conference on Secondary Ion Mass

Spectrometry, Washington, D. C., October 1, 1986.

3 . Committee Assignments

Harry Rook

Chairman, EPA Scientific Review Panel on Quality Assurance

Chairman, Office of Water Data Coordination, Committee 5F

Chairman, ASTM D-22.03 Sampling and Analysis of Ambient Atmospheres

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Member, ASTM D-22. 01 Quality Assurance

Member, IUPAC Commission V.3 (Analytical Nomenclature)

Arnold Bass

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Member, ASTM D-22. 01 Quality Assurance

Member, ASTM D-22.03 Sampling and Analysis of Ambient Atmospheres

Member, Ozone Science Guidance Committee, NESDZS

David Bright

Member, ASTM E-29 Particle Size Measurement

Member, ASTM E29.04 Liquid Particle Measurement

Lloyd Currie

Member, ASTM E10.05.02 Task Group

Member, CAC , Quality Assurance Task Force

Titular Member, IUPAC Commission on Analytical Nomenclature

Chairman, Consultant's Group, International Atomic Energy Agency, on Limit

of Detection

Member, Interagency Workshop on the Future of Accelerator Mass

Spectrometry in the U.S.A.

Member, University of Maryland Thesis Committee (A. E. Sheffield)

Member, Editorial Board, Journal of Chemometrics

William Dorko

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Secretary, ASTM D22.03 Sampling and Analysis of Ambient Atmospheres

Edgar Etz

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Alan Fried

Member, NASA's Science Team Committee for the Global Tropospheric

Experiment

Member, University of Maryland Thesis Committee (L. Nunnermacker

Ernest Hughes

Member, ISO/TC 158 Gas Analysis

Member, ISO/TC 158/SC-l Methods for Preparation and Definition of Gas

Mixtures for Calibration

Member, ISO/TC 159/SC-2 Analysis of Natural Gas

Robert Myklebust

Member, ASTM E-2 Emission Spectroscopy

Member, ASTM E-2. 04 Standard Reference Materials

175
Dale Newbury

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, Journal of Electron Microscopy Techniques, Editorial Review Board

Peter Pella

Member, ASTM E-2 Emission Spectroscopy

Member, ASTM E-2. 02 Statistics, Calibration and Standardization

Gerald Sleater

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Member, ASTM D-22. 06 Source Sampling

Walter Zielinski

Member, Interagency Committee on CO 2 and Climate

Member, Interagency Committee for Stratospheric Ozone Protection

Member, Interagency Committee for Indoor Air Quality

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Member, Journal of Analytical Toxicology, Editorial Review Board

4 . Others

a . Seminars

November 13, 1985 - Professor D. J. Donahue, University of Arizona,

"Application of Accelerator Mass Spectrometry to Some

Problems in Archaeology and Geophysics." (Division

Sponsor: L. Currie)

July 31, 1986 - Dr, Yohichi Gohshi, University of Tokyo, "X-Ray

Fluorescence Analysis with Synchrotron Radiation."

(Division Sponsor: P. Pella)

September 10, 1986 - Professor E. R. Malinowski, Stevens Institute of

Technology, "Introduction to Factor Analysis in

Analytical Chemistry." (Division Sponsor: L. Currie)

b. SRM Certification/Information Values

Microanalvsis

SRM 483, Homogeneity Testing and Compositional

Silicon Specimens

SRM 1219, 431 Stainless Steel

SRM 1223, 416 Stainless Steel

SRM 1233, Valve Steel

SRM 1250, CO Base High Temperature Alloy

SRM 1761 - 1767, Low Alloy Steels Series

Analysis of Iron 3%

X-Rav

SRM 1685B

SRM 1686B

SRM 1687B

176
SRM 2630

SRM 2631

Proposed SRM Brick Clay 679

Proposed SRM Dolomitic Limestone 88B

Gas Metrolozv

SRM 1625,

SRM 1626,

SRM 1627,

SRM 1629,

SRM 2627,

SRM 2628,

SRM 2629,

SRM 1693,

SRM 1694,

SRM 2636,

SRM 2637,

SRM 2638,

SRM 2639,

SRM 2642,

SRM 1683,

SRM 1684,

SRM 2619,

SRM 2621,

SRM 2622,

SRM 2624,

SRM 2625,

SRM 2626,

10 cm SO 2 Permeation Tubes

5 cm SO 2 Permeation Tubes

2 cm SO 2 Permeation Tubes

NO 2 Permeation Tubes

5 ppm Nitric Oxide in Nitrogen

10 ppm Nitric Oxide in Nitrogen

20 ppm Nitric Oxide in Nitrogen

50 ppm Sulfur Dioxide in Nitrogen

100 ppm Sulfur Dioxide in Nitrogen

250 ppm Carbon Monoxide in Nitrogen

2500 ppm Carbon Monoxide in Nitrogen

5000 ppm Carbon Monoxide in Nitrogen

1% Carbon Monoxide in Nitrogen

8% Carbon Monoxide in Nitrogen

50 ppm Nitric Oxide in Nitrogen

100 ppm Nitric Oxide in Nitrogen

0.5% Carbon Dioxide in Nitrogen

1.0% Carbon Dioxide in Nitrogen

2% Carbon Dioxide in Nitrogen

3% Carbon Dioxide in Nitrogen

3.5% Carbon Dioxide in Nitrogen

4.0% Carbon Dioxide in Nitrogen

177
N 8S-1 1 4A irev. 2 -ec) U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

2. Performing Organ. Report NoJ 3. Publication Date NBSIR 86-3468 NOVEMBER 1986

4 . TITLE AND SUBTITLE

Technical Activities, 1986, Center for Analytical Chemistry

5. AUTHOR(S)

R. A. Durst, H. S. Hertz, J. K. Taylor, R. A. Velapoldi

6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions)

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. Stote, ZIP)

Same as above.

10 . supplementary notes

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

bi bl lography 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 1986 in 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 i Analytical chemistry; analytical services; gas and particulate science;

inorganic analytical chemistry; organic analytical chemistry; quality assurance;

voluntary standards.

13. availability 14. NO. OF

PRINTED PAGES

' Xj U n 1 i mi ted For Official Distribution. Do Not Release to NTIS 184

Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

' 20402. 15. Price

|X I Order From National Technical Information Service (NTIS), Springfield, VA. 22161 $16.95

<£I3)

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