NBSIR 80-21 64 /f

Technical Activities 1980

Center for Analytical Chemistry

C. W. Reimann, R. A. Velapoldi, L. B. Hagan, and J. K. Taylor, Editors

National Measurement Laboratory

National Bureau of Standards

U.S. Department of Commerce

Washington, DC 20234

October 1980

I Final

Issued December 1980

Prepared for National Bureau of Standards

Department of Commerce

Washington, D.C. 20234

NBSIR 80-2164

TECHNICAL ACTIVITIES 1980

CENTER FOR ANALYTICAL CHEMISTRY

C. W. Reimann, R. A. Velapoldi, L B. Hagan, and J. K. Taylor, Editors

National Measurement Laboratory

National Bureau of Standards

U.S. Department of Commerce

Washington, DC 20234

October 1980

Final

Issued December 1980

Prepared for National Bureau of Standards

Department of Commerce

Washington, D.C. 202340

U.S. DEPARTMENT OF COMMERCE, Philip M. Klutznick, Secretary

Jordan J. Baruch, Assistant Secretary for Productivity. Technology, and Innovation

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
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TABLE OF CONTENTS

Page

I. CENTER FOR ANALYTICAL CHEMISTRY

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

Coordination 4

C. National Environmental Specimen Bank 8

D. Service Analysis 21 E. New Competence Building Program — FY '81 23

F. Instrument Development Group 26

1 . Group Overview 26

2. Selected Technical Accomplishments 28

a. Studies of the Charge-Collection Mechanism in

Laser Enhanced Ionization Spectrometry 28

b. Atomic Resonance-Line Lasers for Atomic

Spectrometry 33

c. Reduction of Ionization Interferences in Laser

Enhanced Ionization Spectrometry 36

d. Detection Limits of Some Trace Molecules of the

Atmosphere by IR Diode Laser Absorption .... 38

e. Trace Organic Analysis by Multi photon Ionization 41

f. Instrumentation Project 45

3. Outputs and Interactions 46

II. INORGANIC ANALYTICAL RESEARCH DIVISION

A. Division Overview 49

B. Selected Technical Accomplishments 59

1. D.C. Plasma Emission Spectrometry 59

2. The Halogen Content of Lubricating Oils 61

3. Measurement of the Co-60 to Co- 59 Ratio in Microparticles 62

4. Cryogenic Homogenization of Tissue 64

5. Rapid Analysis of Toxic Metals in Biological Tissue

and Fluids by Atomic Absorption Spectrometry .... 66

6. Comparative Measurements of Zinc-70 Enrichment in

Human Plasma Using Neutron Activation Analysis and

Thermal Ionization Mass Spectrometry 68

7. Trace and Toxic Elemental Study of the Chesapeake

Bay 69

8. Characterization of Potentially Hazardous Wastes —

Development of Rotary Extractor and Quality

Assurance Standards 72

9. Development of an Improved Gravimetric Method for

the Determination of Aluminum in Bauxite 75

10. Fission Track Monitor 77

11. Interferences in the Inductively Coupled Plasma

(ICP) Technique 77

12. Atomic Weight of Silver 79

1
13. High Accuracy Mass Spectrometric Isotopic Analysis

of Uranium 81

14. Half-Life of 2*+ipu 82

15. High Precision Pulse-Counting 83

16. High Accuracy Method for Determining Sulfur in

Iron Base Alloys 84

17. Standard Reference Materials 86

C. Outputs and Interactions 89

III. ORGANIC ANALYTICAL RESEARCH DIVISION

A. Division Overview 99

B. Selected Technical Accomplishments 110

1. Isotope Dilution/Mass Spectrometry Definitive Method

Developed for Creatinine in Serum 110

2. Human Serum Reference Material (SRM 909) Ill

3. FI uoroimmunoassay Procedure Developed for

Dinitrophenol s in Water 112

4. Development of Methods for Determination of the

Aromatic Carbon Content of Recycled Oils by HighField ^^C NMR Spectroscopy 113

5. Research on Two-Dimensional Proton NMR Spectroscopy

and Its Application to SRM Q-Glucose 118

6. Analysis of Sodium Pyruvate and Its Impurities by

Proton NMR Spectroscopy at 400 MHz 121

7. Analysis of Boat Conformations of a-D-Al tropyranoside

Derivatives by Interpretation of Highly Coupled

Proton NMR Spectra 124

8. Laser Polarimetry and Its Application to Recertification of Sucrose SRM (SRM 17c) 131

9. Certification of Generator Columns for Polynuclear

Aromatic Hydrocarbons in Water (SRM 1644) 131

10. First Natural Matrix Trace Organic SRM Issued for

Shale Oil (SRM 1580) 134

11. Synthesis, Isotopic and Purity Analyses, and Preparation of Solutions of Stable Isotope Labeled Marker

Compounds for Priority Pollutant Analysis 136

12. Evaluation of a Spectroel ectrochemical System

Using ^-Tol idine 138

13. Development of a System for Computer-Controlled

Rapid Electrochemical Measurements 140

14. Development of a High-Sensitivity Dual -El ectrode

Detector for Liquid Chromatography 141

15. Estimation of Thermodynamic and Kinetic Data from

Spectroel ectrochemical Studies Using Digital

Simulations 141

16. Method Development for Determination of Ambient

Temperature Vapor Pressures of Polynuclear Aromatic

Hydrocarbons 146

17. Combined LC/MS Techniques for Direct Quantitative

Analysis of Individual Organic Compounds in Complex

Mixtures 148

18. Correlation of Liquid Chromatographic Retention Data

with Molecular Shapes for Polycyclic Aromatic

Hydrocarbons 148

i i
19 . Application of Mul ti-Dimensional Chromatography to

Trace Organic Compound Quantitation 150

20. Development of a Procedure for the Analysis of

Polychlorinated Biphenyls in Recycled Oils 152

21. Development of a Fourier Transform Infrared

Spectrometer-Gas Chromatograph Interface and Its

Application to Pollutant Identification 153

C. Outputs and Interactions 154

IV. GAS AND PARTICULATE SCIENCE DIVISION

A. Division Overview 165

B. Selected Technical Accomplishments 174

1 . Intercomparison of O3 and NO2 Measurement Standards

by Gas Phase Titration 174

2. Development of Atmospheric Nitrous Oxide and Halocarbon Standards 176

3. The Determination of Infrared Line Intensities for

Selected Molecules Using Diode Laser and Fourier

Transform Infrared Spectroscopy 179

4. The Measurement of Temperature Dependence of Ozone

Absorption Cross-Sections in the Ultraviolet 180

5. Standards for Measurement of Atmospheric Carbon

Dioxide 182

6. Industrial Preparation of Traceable Gas Certified

Reference Materials 183

7. Standard for Measurement of Benzene and Perchlorethylene in Workplace Atmospheres 184

8. Motor Vehicle Manufacturers Association Program for

Heavy Duty Vehicle Emissions Standards 185

9. Evaluation of the Coherent Anti-Stokes Raman

Spectroscopy (CARS) Capillary Waveguide Detection

System for High Performance Liquid Chromatography . . 187

10. Measurement of Ambient Sulfur Aerosols by a New Fast

Response Flame Photometric Instrument 189

11. Monte Carlo Electron Trajectory Calculation of Beam

Spreading Effects in Thin Foils in the Analytical

Electron Microscope 190

12. General Expression Developed for the X-ray

Bremsstrahlung Intensity Data 192

13. Development of a Sequential Simplex Procedure for

Resolving Spectral Interference in Energy Dispersive

X-ray Spectrometry 194

14. Development of a New Procedure for Calibration of a Crystal Spectrometer for Relative Line Intensity

Measurements 195

15. Successful Raman Microprobe Analysis of Opaque

Particles 197

16. Development and Characterization of a New Raman

Microprobe with Multichannel Optical Detector .... 200

17. Ion Microprobe and Laser Microprobe Mass Analysis of

Inorganic Particulates 203
18. Evaluation of Counter Error in the Development of

Asbestos Standards for the Electron Microscope .... 206

19. The Development of Thin Glass Films as Potential

Standards for X-ray Spectrometric Calibration 207

20. Low Velocity Wind Tunnel Facility for the Evaluation

of Personnel Dosimeters 211

21. Enhanced Detection of Molecules Near a Surface by

Raman Spectroscopy Excited by Evanescent Waves .... 212

22. Statistical Evaluations of the International Radiocarbon Cross Calibration Exercise, and of the Natural

Radiocarbon Fluctuations 214

23. Advances in Small Sample Radiocarbon Measurement

Techniques; Application to the Assay of Individual

Atmospheric Chemical Species 220

C. Outputs and Interactions 223
I. Center for Analytical Chemistry

Curt W. Reimann, Director

Ranee A. Velapoldi, Deputy Director

A. Center Overview

The Center for Analytical Chemistry develops and maintains the

scientific competences and the experimental facilities necessary to

provide the Nation with the basis for uniform measurements through development of measurement methodology and provision of measurement services in

the field of analytical chemistry. Analytical measurements provide a foundation for all aspects of scientific and technological research and

development concerning materials and their practical application. Furthermore, results of analytical measurements are increasingly used as the

basis for regulatory, medical, and industrial decisions. It is essential

that these measurements be reliable and the Center serves as the national

reference laboratory for assuring this reliability.

The principal means by which the Center serves as a national reference

laboratory is through the development and issuance of standard reference

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

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

Center. These standards are used in the metal and chemical industries and

in clinical and environmental laboratories. Each standard is supported by

research on homogeneity and stability and is certified as to chemical

composition using the most reliable analytical methods available.

Analytical chemistry is increasingly being called upon to provide key

data for highly complex sample types — hazardous chemical and nuclear

wastes, body fluids, plant and animal tissue, foods, and high-technology

materials. Often analytical values as a function of location within a sample are needed. As the demands upon analytical chemistry become more

sophisticated, the problem of standardization becomes more challenging

both in terms of the number and the complexity of the proposed standard

materials. As it is not reasonable to contemplate the development of

complex standards to deal with every measurement problem, the Center's

program must be multifaceted, seeking a variety of avenues to impact the

quality of analytical measurements made in the U.S. In addition to the

issuance of standards, the Center exerts influence through close contacts

with various communities by means of workshops, symposia, and participation in standards committees. Through such contacts, priorities are established for the production of standards and mechanisms are set in

place for their effective use.

1
The program of the Center strives to achieve a balance among the

provision of currently needed standards and research efforts on new types

of standards and measurement methods. The work of the Center is performed

in three divisions, each focusing upon specific sample types — inorganics,

organics, and gases and particulates. Within each division there are

several groups representing separate analytical chemical disciplines,

e.g., mass spectrometry and electrochemistry. One group, the Instrumentation Development Group, is attached to the Center office. Each division

is responsible for a program in basic and applied research and maintains

contacts with appropriate communities.

In the following, the major recent activities and technical directions of the divisions and groups mentioned above are given. Much work in

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

1 . Outputs and Interactions

a . Publ i cations

Brewer, Leo and Hagan, Lucy, "The Oscillator Strength of the C2 Swan

Bands", High Temperature Science , 1

1

, 233-264 (1979).

Reimann, Curt W. and Hagan, Lucy, "Technical Activities 1979, Center for

Analytical Chemistry", NBSIR 80-1995 (March 1980).

b. Committee Assignments

Lucy Hagan

Member, NBS Synfuels Task Force

Member, CAC Committee on Computer Requirements

c . Center Colloquium Series

October 1 , 1979 Graeme Batley, Australian Atomic Energy Commission, Lucas Heights, Australia, "Electrodeposition

Techniques for the Study of Heavy Metals in

Natural Waters".

October 9 - Steven C. Wofsy, Harvard University, "Some

Recent Problems of Atmospheric Chemistry".

October 30 Morteza Janghorbani, Massachusetts Institute of

Technology, "Stable Isotope Tracers in Human

Mineral Nutrition".

November 14 - Charles E. Kolb, Aerodyne Research, Bedford, MA,

"Laboratory Applications of Tunable Diode Lasers".

2
November 1 5, 1979 - Charles A. Evans, Charles Evans Associates,

San Mateo, CA, "Recent Advances in Materials

Analysis by Secondary Ion Mass Spectroscopy".

November 30 Andrew Tam, IBM, San Jose, CA, "Laser

Optoacoustic Spectroscopy".

December 3 Bruce Kowalski, University of Washington,

"Chemometrics in Analytical Chemistry".

December 12 John I. Peterson, NIH, Bethesda, MD, "The Fiber

Optic pH Probe"

.

January 16, 1 980 William Dark, Waters Associates, Milford, MA,

"An Overview of HPLC for Clinical Analysis".

February 13 Geraldine M, Huitink, Indiana University of

South Bend, South Bend, IN, "The Role of the

Fluorophore in Metal lofluorescent Indicators".

March 14 - Richard Van Duyne, Northwestern University,

Evanston, IL, "Recent Developments in Enhanced

Raman Spectroscopy".

March 21 — David M. Coleman, Wayne State University,

Detroit, MI, "Studies in New Analytical Segregated Electrical Discharge Systems".

April 9 Jack W. Frazer, Lawrence Livermore Laboratory,

Berkeley, CA, "Characterization and Control of

Complex Chemical Systems".

May 14 • Velmer A. Fassel , Iowa State University, Ames,

lA, "Inductively Coupled Plasma-Atomic Emission

Spectroscopy: Past, Present, and Future".

June 13 John C. Wright, University of Wisconsin, Madison

WI, "Application of Selective Laser Excitation

Studies to Solid State Chemistry and Ultra-Trace

Analysis"

.

June 18 - John T. Stock, University of Connecticut,

"Historic Instruments: The Scientist's

Heritage"

.

3
B. Voluntary Standardization and Quality Assurance Coordination

1 . Voluntary Standardization

Parttcipation in the voluntary standardization process is. an ijnportant

activity of members of the staff of the Center. Committee assignments,

listed under the respective divisional summaries, indicate that 24 menbers,

i.e., 20 percent of the staff, hold memberships on 9.7 national and international organizations. The extent of participation ranges from general

review of documents to holding of major offices. During the past year,

positions of leadership were held on 12 groups or committees, and Center

staff actively authored a number of standards and participated in four

collaborative tests.

Participation in standardization activities has hitherto been on a rather informal basis. While some has resulted from direct invitations

for NBS to participate, most has stemmed from the personal interests of

the staff, which NBS has always had the policy to encourage. As a result,

there are a number of committees and/or task groups in which there is

multiple representation and such redundancy is not without benefit. On

the other hand, there are doubtless other groups which may be in need of

the Center's expertise, where it is presently lacking. Recent Developments in standardization policy and outlook emphasize the need for some coordination of the Center's standardization activities.

Under provisions of Circular A-119 issued by the Office of Management and Budget in January 1980, entitled, "Federal Participation in the

Development and Use of Voluntary Standards", government organizations are encouraged to participate in development of, and to make more use of

voluntary standards as they relate to their areas of interest. The

Circular limits participation to those organizations which have the

broadest representation of the areas of interest and which fully utilize

due-process practices in standards development.

CAC expertise can well serve these objectives. Through a wider base

of service, the Center could provide increased services to existing

constituents and perhaps broaden its base to constituents not presently

reached. A careful search for areas of need may identify new opportunities. Because of the amount of present activity, it might be necessary to

limit some multiple representations in order to extend service to others.

A further need for coordination results from the growing concern

about "high impact" standards. Examples of such standards are those with

considerable economic impact, or that would involve policy decisions in

their development. Furthermore, a number of standards committees are becoming classified, i.e., membership is classified to assure a balance

of interests, bence, coordination of position across laboratory or agency

lines may need to be established. As a minimum, more record keeping will

be required not only in the sensitive areas, but in others as well, since

there is no certain way to identify, before hand, when a high-impact

issue might develop within any committee.

4
2. Quality Assurance

The growing interest in quality assurance of analytical data is

making increasing demands on the Center's programs while influencing its'

internal activities as well. The Center has always had concern for the

quality of its data and its quality assurance program might be described

as one of informal redundancy. Key measurements , such as standard

reference material CSRM) certifications, for example, are made using at

least tvi/o independent methods and often with the number of repetitions

far exceeding the minimum requirements. However, interagency agreements

involving data production are or will be requiring formal Quality

Assurance programs to be used. For this and other reasons, a critical

survey will be made of the Center's existing Quality Assurance programs

to see if and/or where they need strengthening. The results should be

internally beneficial, as well as helpful to others in designing their own Quality Assurance programs.

Another area related to quality assurance is the proper utilization

of SRM's. While the end-purpose of these is for the improvement of

measurement accuracy, no formal instructions for their use, in this

respect, are ordinarily available from NBS. As SRM's are being obtained

by a growing community of users, the need for more formal applications

information is emerging. Such guidelines or instructions would extend

their usefulness, alleviate possible misuse, and conceivably extend the

supply in some cases.

A protocol for industrial production of certified reference materials,

traceable to NBS SRM's is under development by the Gas and Particulate

Science Division, in collaboration with the Environmental Protection

Agency. This protocol describes in detail how the SRM should be used to

assure the quality of the measurement of the certified reference material.

While protocol development may be useful in only a limited number of

cases, there are others where procedures could be recommended to maximize

the usefulness of the SRM. Center scrutiny will be encouraged to identify

such cases, especially while certifying a specific SRM, so that applications for information can be developed concurrently.

John K. Taylor

3. Outputs and Interactions

a . Publ tcations

Taylor, J. K., "The Importance of Intercal tbration in Marine Analysts",

Thai. Jugoslav., ii 0/21 221-229. 0978) COelayed publ teat ion )_.

Taylor, J. K., "Qual ity Assurance Measures for Environmental Data" tn

Lead tn the Martne Environment , M. Brantca and Z. Konrad, Eds.,

Pergamon Press, Oxford, England 0980).

5
b. Talks

Taylor, J. K. , "Technical Activities of the NBS Center for Analytical

Chemistry", Japan-U.S. Symposium on SRM^s, Korlyama, Japan,

October 7, 1979.

Taylor, J. K., "Environmental Standard Reference Materials", Japan-U.S.

Symposium on SRM's, Korlyama, Japan, October 8, 1979.

Taylor, J. K., "Quality Assurance Program for Analytical Chemistry",

Japan-U.S. Symposium on SRM's, Korlyama, Japan, October 9, 1979.

Taylor, J. K., "The Role of Standard Reference Materials In Quality

Assurance of Chemical Measurements", Tokyo University, Tokyo, Japan,

October 11 , 1 979.

Taylor, J. K. , "Traceability of Chemical Measurements to National Measurement Standards", Kyoto University, Kyoto, Japan, October 13, 1979.

Taylor, J. K., "Methods for Preparation of Standard Gas Mixtures", National

Institute for Environmental Studies, Tsukuba, Japan, October 16, 1979.

Taylor, J. K., "Recent Advances in El ectroanalytical Chemistry", National

Institute of Metrology, Beijing, China, November 14, 1979.

Taylor, J. K., "Coulometrtc Analysis", Natllonal Institute of Metrology,

Beijing, China, November 1 5, 1 979.

Taylor, J. K., "Water Pollution Analysis", National Institute of Metrology,

Beijing, China, November 16, 1979.

Taylor, J. K., "Air Pollution Analysis", National Institute of Metrology,

Beijing, China, November 17, 1979.

Taylor, J. K., "Measurement and Analysis of Particulates", National Institute

of Metrology, Beijing, China, November 19, 1979.

Taylor, J. K., "Microchemical Analysis", National Institute of Metrology,

Beijing, China, November 20, 1979.

Taylor, J. K., "Quality Assurance and Its Role in the Management of Chemical

Laboratories", National Institute of Metrology, Beijing, China,

November 21 , 1979.

Taylor, J. K., "Standard Methods and Standard Reference Materials",

National Institute of Metrology, Beijing, Cfilna, November 22, 1979.

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

Academy of Sciences, Shanghai, China, November 27, 1979..

Taylor, J. K., "Standard Reference Materials", Shanghai Academy of Sciences,

Shanghai, China, November 28, 197 9.

6
Taylor, J. K., "Water Pollution Analysis - Standardization of Methods - SRM's", Kwangchow Academy of Sciences, Kwangchow, China, December 4,

1 979.

Taylor, J. K., "The NBS Center for Analytical Chemistry", National Institute

of Metrology, Beijing, China, December 7, 1979.

Taylor, J. K., "Principles of Quality Assurance Applied to Forensic

Analysis", Federal Bureau of Investigation, Washington, D.C.,

December 14, 1979.

Taylor, J. K., "Quality Assurance of Chemical Measurements", VI International Symposium, "Chemistry of the Mediterranean", Rovinj,

Yugoslavia, May 4, 1980.

c. Committee Assignments

John K. Taylor

Member, IS0/TC48, Laboratory Glassware and Related Apparatus

IS0/TC48/SC1 , Volumetric Glassware

IS0/TC146, Air Quality

IS0/TC146/SC3, ^nbient Measurements

Chairman, IS0/TC147, Water Quality

Member, ISO/TCl 47/S.Cl , Terminology

IS0/TC147/SC2, Chemical, Physical, Biochemical Methods of Analysis ^ ISO/TCl 47/SC6, Sampling

ANSI TAG, ISO/TCl 47, Water Quality

ANSI TAG, IS0/TC172, Optical Instruments

ASTM D19, Water

Chairman, ASTM D19.01.07, International Standards

Member, ASTM D19.02, General Specificiations

ASTM D19.05, Inorganic Constituents

ASTM D19.07, Sediments

ASTM D22, Atmospheric Analysis

ASTM D22.04, Workplace Atmospheres

Vice Chairman, ASTM D22.05, Calibration

Member, ASTM D22.07, Precision and Accuracy

ASTM D22.09, USTAG to TC 146

ASTM E34, Occupational Safety and Health

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 CACS)

ACS Committee on Environmental Chemistry - Subcommittee on Environmental Analytical Chemistry

NBS Museum Committee

NBS 80th Anniversary Celebration Committee

NBS Advisory Committee, State Measurement Needs Survey

7

I
C. National Environmental Specimen Bank

1. Introduction

In response to the growing concern for the potential dangers to

human health and the environment by the increasing influx of man-made

substances in our ecosystem, the U.S. Environmental Protection Agency

(EPA) and the National Bureau of Standards (NBS) are currently studying

the feasibility of establishing a National Environmental Specimen Bank

(NESB). The program for such a Bank would incorporate a well-defined

system of collection, analysis, and long-term storage of selected environmental samples to provide (1) real-time monitoring data for pollutant

trend analysis and (2) properly collected and stored samples for retrospective analysis.

The National Bureau of Standards is currently involved in a five-year

Pilot Environmental Specimen Bank Program which will provide actual working experience in all stages of the banking effort: specimen collection,

processing, storage, analysis, and data management. The purposes of this

pilot study are: (1) to develop analytical protocols for sampling and

storage of four types of environmental samples, (2) to improve analytical

methodologies for both trace elements and trace organics, (3) to evaluate

the feasibility of long-term specimen storage at various conditions

(-25 °C, -80 °C, -120 °C, and freeze-dried at room temperature), and

(4) to provide a "bank" of samples for retrospective analysis in future

years as analytical methodologies improve. The experience gained in this

pilot study will be used to evaluate the feasibility of the NESB Program.

The rationale for this specimen banking program, a review of the NBS activities relating to this program, and an outline of the proposed five-year

pilot specimen bank study at NBS have been described previously [1,2]. In these previous reports, the construction of the clean 1 aboratory/storage

facility was described and the preliminary plans for sample collection and

storage were reviewed. During this initial year of the proposed five-year

pilot study, the collection, processing, storage evaluation, and trace

element analysis of the first environmental specimens, human livers, were

implemented. Detailed reports [1,3] are available which describe the

pilot specimen bank program. Highlights from these reports are included

here

.

2 . Safety Requirements

The handling of human liver samples carries the potential risk of

exposure to infectious diseases, particularly hepatitis B virus or "serum

hepatitis." As a result, certain precautions are necessary to insure

protection of the analysts involved in sample processing and analysis.

To eliminate potentially infectious liver specimens from the speci- men bank samples, a blood sample is removed from the donor at the time of

autopsy to be used for hepatitis B screening. In addition, liver speci- mens from the right lobe are removed for preparation of histological

slides. These slides are examined by the pathologists for evidence of

8
infectious diseases. Liver samples are placed in temporary storage at

liquid nitrogen temperatures at NBS until the results of the screening

are received from the hopsitals supplying the livers.

A Safety Advisory Committee has been established to advise the Center

for Analytical Chemistry concerning suitable safety precautions for the

handling and processing of these liver samples at MBS. This committee

consists of Michael Greene, M.D. (NBS physician), Robert Purcell, Ph.D.

(Chief of Hepatitis Section, National Institutes of Health), and Tom Koch,

Ph.D. (Department of Pathology, University of Maryland). Recommendations

were made by the committee regarding procedures to safeguard personnel.

The Safety Advisory Committee will be requested to review annually the

procedures of the pilot specimen bank program.

3. Collection of Liver Samples

Contracts for procurement of liver samples were negotiated and

awarded to three medical schools located in Baltimore, Maryland;

Minneapolis, Minnesota; and Seattle, Washington. Each contractor is

providing 100 liver samples this year for a total of 300 samples (see

figure 1).

Due to the extremely low levels of trace elements and organic

pollutants in human liver tissue, the analytical chemist must exercise

extreme caution to avoid possible contamination of the sample. (The

lack of contamination control has made existing banks of samples useless

for general trace constituent analyses.) A detailed sampling protocol,

designed from the viewpoint of analytical chemists, is utilized to minimize contamination. The written sampling protocol outlines in detail

the case selection criteria and the steps to be followed by the contractor

in obtaining a "valid" sample. The implementation of this protocol is a result of extensive interaction with NBS personnel and the contractors to

insure the quality of the samples.

The individual collecting the liver samples uses (1) non-talced

gloves, C2) a special titanium-bladed knife for bisecting the liver (to

avoid contamination from other elements, i.e., Cr, Ni , etc.), (3) Teflon

sheets upon which the sample is placed, and (4) high-purity water to

rinse the sample. The samples are then sealed in Teflon bags, frozen at

liquid nitrogen temperature, and shipped to NBS. A data form, sent with

each liver sample, contains information about the donor and specimen,

e.g., date of birth, sex, residence, ethnic group, height, weight, smoker,

occupation (if known), diagnosis of autopsy, date and time of death and

autopsy, and weight of sample. Approximately 100 samples have been

received and stored in the pilot bank facility at NBS.

The scheme for the collection and allocation of subsamples for

storage evaluation are shown in figures 1 and 2. The liver specimens are received as duplicate sections of the left lobe identified as sections

"A" and "B". All "A" sections are placed in liquid nitrogen freezers for

long-term storage, and the "B" sections are used for storage evaluation.

9
1

I

10

Figure

1.

Sample

collection

scheme

for

human

livers.
Sample

Storage

Evaluation

>* cL

eze

dr

store E

0)

E

0) o

u. o

cc

e-52 .= (0

1-

^

(0 c

a> ^ cc

11

Figure

2.

Allocation

of

subsamples

for

storage

evaluation.
i.e., real-time analysis and long-term storage evaluation at different

conditions. Approximately 10 percent of the samples will be homogenized

using a cryogenic brittle fracture technique. This homogenization provides about 20 aliquots of 5-8 g which are stored in Teflon jars. To

solve the question of appropriate temperature for sample storage, these

sample aliquots will be stored under four different conditions: freezedried at room temperature, fresh frozen at -25 °C, at -80 °C, and in

liquid nitrogen vapor at -120 °C to -190 °C. The concentrations of trace

constituents found after storage under those conditions will be compared

to the data found in the "real-time" analysis of each specimen (figure 2).

The "A" sections are reference samples which may be used to re-evaluate

results on a particular "B" section. At the end of the pilot program,

the "A" sections stored at liquid nitrogen temperatures will represent a valuable bank of validated samples available to the scientific community.

In addition, a large quantity of data, from the analyses of the "B"

sections, will be available on many of these samples.

The success of the NESB will be determined in a large part by the

ability to preserve the integrity of the trace substances (i.e., organic,

inorganic, and organometal 1 ic species) in samples during long-term storage. Changes in the forms and concentrations of the numerous environmentally important substances in specimens stored for extended periods may occur in several ways. Processes such as surface adsorption and sample

degradation may reduce the concentrations of various components. In addition, continued biochemical and enzymatic activity may produce species

which may not have been present in the original sample. On the other hand,

contamination of the specimen fluids could lead to apparent increases in

trace substances' concentrations. Superimposed on these processes are the

factors which will affect the process rates, such as container material,

contact time and area, storage temperature, pH, and initial species con- centration. All of these factors are important considerations in

evaluating the suitability of long-term storage.

The probability for the discovery of changes in the concentrations

of trace constituents during storage has been assessed by statistical

treatment of the expected experimental parameters, e.g., number of speci- mens analyzed, homogeneity of subsamples, and analytical error (K. R.

Eberhardt and L. DeRobertis, Center for Applied Mathematics, Statistical

Engineering Division, NBS). Figure 3 consists of a series of curves generated from the experimental parameters of 5 percent inhomogeneity and

5 percent analytical error. These curves determine the probability of

detecting a particular percent change in concentration (e.g., 6 and 4

percent for curves 1.0 and 0.7, respectively) for a given number of liver

samples analyzed. For example, we would have a 98 percent probability of

detecting a 6 percent change (Point A) and a 78 percent probability of

detecting a 4 percent change in concentration (Point B) if 30 livers are analyzed. If the sample inhomogeneity or analytical error increased to

10 instead of 5 percent, the percent change detectable at Points A and B would be 12 and 8 percent, respectively. Based on these curves, the

number of samples to be analyzed was set at 30. Analyses of a smaller

number of samples would significantly reduce the probabilities of detecting small changes, whereas increasing the number of samples analyzed

would not increase greatly the probability of detecting changes.

12
Figure

3.

Probability

of

detecting

change

in

the

concentration

due

to

storage

condition.
The 30 specimens used for the storage evaluation represent approximately 10 percent of the specimens collected per year. A major limitation to this number is the present analytical capacity. In order not

to exceed the currently available analytical capability, most of the

analytical work is deferred to the year 1984, when the program should

have a larger analytical capacity. For the evaluation of the storage

of human livers. Table 1 gives the analytical needs in terms of numbers

of livers to be analyzed each year.

Table 1. Number of Livers to be Analyzed for Storage Evaluation Study.

Year 80 81 82 83 84

Real Time Analysis 36 30 30 30

1 Year Storage LN^ 12 30

-85 ®C Samples 12 Sampl es 30

-25 °C from '80 12 from '83 30

RT U _30

2 Years Storage LN

2

To

-85 °C Sampl es 30

-25 °C from ' 82 30

RT 30

3 Years Storage LN

2 To

CO cn 0 0 Sampl es 30

-25 °C from ' 81 30

RT 20

4 Years Storage LN

2

24

-85 °C Sampl es 24

-25 °C from ' 80 24

RT 24

Livers Analyzed/Year 36 78 30 30 456

14
4. Trace Element and Trace Organic Analysis

The trace element analysis activities of the specimen bank project

have concentrated on three main tasks this year: (1) development of a comprehensive analytical scheme, (2) evaluation of the sample collection

protocols, and (3) initiation of the analysis of the first year's collected samples.

The current analytical protocol is directed toward the analysis of

most of the first-priority elements proposed by the International Workshop on Monitoring Environmental Materials and Specimen Banking [4].

Additional elements occurring as biological major elements and trace

elements in the samples are included in the protocol because their

levels might supply information about the "normal" state of the specimen.

The elements under consideration, their priority, and the analytical

techniques to be used appear in Table 2. This scheme incorporates the

NBS-CAC approach of multi-technique analysis for quality control. The

first three techniques listed, i.e., atomic absorption spectroscopy

(AAS), anodic stripping voltammetry (ASV) or linear sweep voltammetry

(LSV), and instrumental neutron activation analysis (INAA), comprise the

current routine analytical scheme. Isotope Dilution Mass Spectrometry

(IDMS) and radiochemical neutron activation analysis (RNAA) will be

performed on a limited number of samples to provide multi-technique

quality control as well as to add data on elements of special environmental interest, e.g., thallium. Prompt gamma activation analysis (PGAA)

will be performed in collaboration with the University of Maryland,

Division'of Nuclear and Environmental Chemistry. Preliminary results

from PGAA of samples of specimen bank livers appear promising for the

elements indicated in Table 2, particularly for the major elements, H,

C, and N, and the trace element, B. The determination of H, C, and N may be useful in the planned research on the most suitable weight basis,

e.g., dry versus wet weight.

According to the proposed storage evaluation scheme, 36 livers are being analyzed during the first year of sample collection. These samples

are being analyzed by AAS, voltammetry, INAA, and IDMS. Some preliminary

results of liver analyses are shown in Table 3.

15
Table 2. Comprehensive Analytical Scheme for Trace El ements in Human Liver

Priority^

1 2 B AAS^ ASV/LSV^ INAA^ IDMS*^ RNAA*^ PGAA^

H *** kkk

Li

Be *** ***

B kkk

C *** kkk

N kkk

0 ***

Na ***

Mg

** kkk kkk

A1 *** kkic kkk kkk

Si

P ***

S *** kkk

Cl *** kkk kkk

K *** kkk kkk

Ca ***

Sc kkk

V ***

Cr

** kick kkk kkk

Mn

** kkk

Fe *** kkk kkk

Co *** kkk

Ni

** kkk

Cu kkk kkk kkk

Zn *** kkk kkk

As *** kkk kkk

Se kkk kkk

Br *** kkk

Rb kkk

Sr •kirk kkk

continued

16
Table 2. Comprehensive Analytical Scheme for Trace Elements in Human Liver,

continued.

Priority®

1 2 B AAS^ ASV/LSV

^ INAA^ IDMS

^ RNAA^ PGAA^

Mo *** *** ***

Pd ***

Ag *** ***

Cd *** *** *** *** ***

Sn *** ***

Sb *** ***

I irk*

Ba *** ***

Ta

W

Pt ***

Hg *** *** ***

T1 *** **

Pb *** *** *** ***

Bi ***

1 = First priority elements

Environmental Materials

October 1978.

from "International Workshop on Monitoring

and Specimen Banking" held in Berlin,

2 = Additional elements of environmental concern.

B = Biological elements.

'aas = atomic absorption spectroscopy;

ASV/LSV = anodic stripping voltammetry/linear sweep voltammetry;

INAA = instrumental neutron activation analysis;

IDMS = isotope dilution mass spectrometry;

RNAA = radiochemical neutron activation analysis;

PGAA = prompt gamma activation analysis.

17
Table 3. Analysis of Trace Elements in Human Liver.

Concentration Range Cyg/g) NBS Results

Element from the Literature [5]

for Human Livers INAA^ ASV/LSV^

Be ND

F 0.06 - 1.4

A1 1.6 - 2.6

V < 0.007 - 0.09

Cr 0.005 - 0.27 0.04

Mn 0.5 - 1.9

Fe 70 - 210 154

Co 0.017 - 0.16 0.039

Ni 0.009 - 0.32 < 0.4

Cu 3.2 - 14.7 11.2 10.1

Zn 31 - 80 63 64

As 0.006 - 0.46 0.033

Se 0 .09.7 - 0.68 0.35

Rb 7 - 12 3.7

Sr 0.01

Mo 0.4 - 1.6 1 .0

Pd ND

Ag 0.006 - 0.07 0.044

Cd 0.5 - 4.9 1 .1 0.9

Sn 0.08 - 0.65

Sb 0.01 0.007

Ba 0.01

Pt ND

Hg 0.005 - 0.25 +

T1 0.001 - 0.009

Pb 0.8 - 2.3 0.7

^INAA = instrumental neutron activation analysts;

ASV/LSV = anodic stripping voltammetry/linear sweep voltammetry.

Results are based on fresh weight.

18
Analytical methods for the analysts of two classes of organic

compounds, t.e., organochl orine pesticides and polycyclic aromatic hydrocarbons (PAH) are currently being developed. Preliminary results have

been obtained using the following analytical procedures: (1) extraction

with acetonitrile, (2) 1 tquid-1 iquid partition into hexane, [3) concentration by evaporation, (4) high-performance liquid chromatography (HPLC) to

isolate the compounds of interest, and (5) gas chromatography (GC) analysis

on capillary columns with selective electron capture detection. An HPLC

method, using a chemically bonded amine column has been developed to

isolate the organochl orine pesticides and PAH from interfering organic

constituents. GC methods have been developed for the determination of

the 16 pesticides on the priority pollutant list. Research is continuing

on the methodology for quantitation of these compounds in liver samples

in order to initiate real-time analyses for organics in 1981. Future plans

include (1) the evaluation of homogeneity for organics, (2) the development

of procedures for comparison of organochl orine content determined by GC and

determined by neutron activation analysis, and (3) expansion of the pilot

program to include development of analytical protocols for the mussel/

oyster samples.

5. Interactions with National and International Programs

Since 1975, the U.S. EPA and the Environmental Agency of the Federal

Republic of Germany have been pursuing collaborative research in the area of the specimen bank program as part of a bilateral agreement on the

environment. Recently, specimen banking was incorporated into a similar

agreement with the People's Republic of China.

In November 1979, NBS, in conjunction with EPA, hosted the third

annual meeting as part of the Bilateral Agreement on the Environment

with representatives of the Federal Republic of Germany. This meeting

addressed in general the environmental specimen bank programs and specifically, the implementation of pilot programs presently underway in both

countries. Construction of the German specimen bank facility is expected

to be completed in early 1981.

In May 1980, NBS scientists were invited to participate in a "Workshop on Research Needed to Improve Data on Mineral Content of Human

Tissues," sponsored by the American Institute of Nutrition and funded by

the National Science Foundation. In an editorial in Analytical Chemistry

52 , 1393 (1980) concerning this workshop. Dr. George H. Morrison, editor

of Analytical Chemistry and Professor of Chemistry at Cornell University,

commented on the NBS Pilot study:

"Of particular interest is the recent establishment of a pilot

environmental specimen bank at the National Bureau of Standards

in cooperation with the Environmental Protection Agency (Anal

.

Chem. 1980 , 52 , 887A). Initial efforts are concerned with the

gathering, processing, and storage of human liver samples. The

goal of the specimen bank program is to develop analytical

protocols and measurement methods, and to evaluate the various

19
storage and sample preparation techniques for their effects

on the samples. This pilot study, limited to environmental

considerations of one human tissue, is a good beginning to

the broader problem of the mineral content of human tissues."

We have recently initiated interactions with the "Mussel Watch Program," coordinated by Dr. Donald Phelps at EPA/Marragansett , Rhode Island,

to coordinate protocol and analytical methods development for the

mussel /oyster samples. The "Mussel Watch Program" will help provide

samples for the pilot banking program.

References

[1] Gills, T. E., Rook, H. L. , and Durst, R. A., The National

Environmental Specimen Bank Research Program for Sampling,

Storage, and Analysis, EPA-600/1-79-017, U.S. Environmental

Protection Agency (1979).

[2] NBSIR 80-1995, Technical Activities 1979, Center for

Analytical Chemistry (1979).

[3] Harrison, S. H., Zeisler, R. , and Wise, S. A., Pilot Program

for the National Environmental Specimen Bank--Phase I, to be

published as an NBS Technical Note.

[4] Selection of Pollutants and Pollutant Categories of Interest

for Monitoring Environmental Materials, in Monitoring

Environmental Materials and Specimen Banking , N. P. Luepke, ed.,

Marti nus Nijoff Publishers, The Hague, 22 (1979)

.

[5] Iyengar, G. V., Kollmer, W. E., and Bowers, H. J. M. , The

Elemental Composition of Human Tissue and Body Fluids,

Verlag Chemie , Weinheim--New York (1978).

S. A. Wise, Project Manager, K. A. Fitzpatrick, R. R. Greenberg,

S. H. Harrison, W. F. Kline, J. K. Langland, E. J. Maienthal, R. Zeisler

20
D. Service Analysis

An important function of the Center for Analytical Chemistry is the

provisions of consultation, advice, and expert chemical analyses on the

many types of diverse materials that are utilized in the research programs

at NBS. This service is also available to other Federal, state, and local

agencies when it is in the instances, where the CAC has a unique analytical

capability, thus some may be extended to the private sector.

In 1980, the staff of the Center for Analytical Chemistry performed

147 service analyses. Of this number, 125 were performed on a cost

reimbursable basis and, for the first time, because of a new funding

structure within the Center, 22 were performed on a no cost basis. Among

the three categories of customers, the largest user was the MBS staff with

64 requests ($108,000), followed by private industries, 52 requests

($33,000) and, thirdly, other federal, state, and county agencies, 31 requests ($39,000).

On the whole, the year was typified by an increased number of requests

for short and rapid turn-around analyses. The two most frequent requests

were for the identification of suspected asbestos-containing materials

and for the recalibration of glass filters used as standards for checking

the transmittance accuracy of visible spectrophotometers. Among the more

interesting analyses were the following studies:

• Investigation of abnormally high incidence of broken hypodermic

needles in products from one pork processing plant (U.S.

Department of Agriculture)

Examination of broken needles supplied by this plant yielded no explanation for their abnormally high occurrence. Subsequent physical

and chemical analyses of new needles from the six U.S. and foreign

manufacturers that could be identified showed that they were not distinguishable and thus any attempt to associate the broken needles with a particular source was not possible. On examining more closely the details

of the plant's history (it did not do its own slaughtering, had considerable worker unrest and, generally, was reluctant to comply with Department

of Agriculture recommendations), it became apparent that the broken

needle problem could be possibly attributed to internal strife. To

pursue this theory it was requested that whenever a broken needle was found, the pork sample in which it was found should also be submitted for

analysis. From the trace chromium and nickel data, a reasonable estimate

of the time the needle had been in the sample could be made. Ironically,

since requesting tissue samples and explaining their intended use, the

discovery of additional broken needles has suddenly ceased.

• Materials failure of steel bars used in construction of new jail

facility (District of Columbia Government)

21
Spectrographic analyses and hardness measurements showed that the

bars used in construction of this facility did not meet specifications.

• Characterization of ink wastes for compliance with the new Environmental Protection Agency's hazardous waste regulations (U.S. Bureau

of Engraving and Printing)

Atomic absorption analyses of leachates obtained from application

of EPA's extraction procedure to wastes produced in the various printing

and plating processes indicated that lead and chromium were abnormally

high in two operations. Additional samples from these two sites have

been requested for a more thorough evaluation.

• Analysis of a large number of culture media for trace concentrations of calcium (National Institutes of Health)

In the growing of mouse epidermal cells the calcium concentration

in the culture media must be kept below about 20 ppm in order to prevent the multi-layering of cells. In a low calcium serum culture medium,

the cells will grow in a uniform layer indefinitely. Using repetitive

optical scanning for background correction in conjunction with flame

emission analysis, NBS has, periodically, accurately monitored the

efficiency of ion exchange procedure used for calcium removal.

• Determination of "age" of wire recovered from tropical environment

(National Security Agency)

Electron probe and spectrographic data obtained on the corrosion

products permitted the NBS Chemical Stability and Corrosion Division

to estimate the time that the wire had been in service to be 18 ± 6

months

.

• "Soft" spots in aluminum alloy plate (National Aeronautics and

Space Administration)

As a part of a larger study being carried out by the Center for

Materials Science on possible soft spots in aluminum alloys, analyses were performed for copper, manganese, and iron in samples taken from

various locations across the face of a 2219 aluminum alloy ingot. These

analyses confirmed that part of the variations in the mechanical properties across the finished alloy plate is caused by significant variation in the

concentrations of these alloying elements. Subsequently, CMS has determined that while macrosegregation of these alloying elements cannot be

completely eliminated by chill face scalping and subsequent thermomechanical treatment, good scalping practice should reduce significantly

the deterioration in mechanical properties.

R. W. Burke

22
E. New Competence Building Programs. — FY'81

1 . Analysis of Ionization Mechanisms and Ion Structures

NBS currently occupies a leadership position in the utilization of

analytical mass spectrometry for the qualitative and quantitative analysis

of "real-world" samples. Most current researchers in mass spectrometry

accept hypothesized ionization mechanisms and assumed structures of ions

on faith, with quantitative internal standards being extensively used in

"correcting" for a lack, of baste understanding. Recent advances in mass spectrometer instrumentation, chemical enhancement of ionization processes,

and laser physics make this an opportune time to further our basic understanding of the ionization process and ion structures. It is the goal of

this competence building program to utilize these recent advances to

develop a theoretical background on which analytical measurements can be

based, and in so doing, maintain and build on the NBS leadership position

in analytical mass spectrometry.

The main scientific and technical thrusts are centered about the use of chemical and physical means for probing ionization mechanisms/

enhancement and ion structures.

• Chemical enhancement of the ionization process will be examined

as a probe of species in the ionization region of the mass spectrometer and collisional activation of ions with reactive

gases will be examined as a probe of the structure of organic

ions

.

• Laser enhancement of the ionization process will be examined as

a sensitive and selective probe of species in the ionization

region, and laser induced metastable ion generation will be

examined as a selective probe of the structure of ground-state

and excited organic ions.

As one output of this program, experiments have already been designed

which would examine the "charge localization" concepts, a basic hypothesis

underlying our current understanding of fragmentation processes in mass

spectrometry.

NBS progress in the research discussed above will have direct application to other research in the Center for Analytical Chemistry (e.g.,

emission spectroscopy) and will allow a more effective attack on measurement problems being faced by NBS Programs and other agencies requesting

CAC analytical expertise.

Industry has become increasingly concerned with measurements of trace

substances in complex matrices. This concern has been increased by con- siderable recent legislation which mandates regulation with respect to

nutritional labeling, good laboratory practices, toxic substances and the

environment. The proper and timely response to these concerns, as well

as the enforcement of all such legislation and regulations are dependent

upon continuing advances in the state-of-the-art of analytical techniques

such as those discussed above.

23
2 . Development of Methods for Compositional Mapping

NBS has played a major role in the development of analytical methods

based on excitation with particle beams of electrons, ions, photons, and

neutrons. An important extension of these techniques for the characterization of samples is the preparation of "area maps" which plot th,e lateral

distribution of characteristic signals, and "depth profiles" which map the

distribution in depth of elemental or molecular constituents. While these

area and depth maps can give a qual itative sense of the spatial distribution of constituents of interest, extension of the mapping techniques to

yield quantitative compositional maps raises exciting experi'mental and

theoretical challenges. Recent advances at NBS and elsewhere suggest that

this is an opportune time to pursue the development of several methods of

compositional mapping. The fundamental scientific problems underlying

these techniques can be uniquely attacked at NBS Because of the diversity

of existing resources combined with the additions suggested in this

proposal . It is the goal of this program to develop the theoretical and

experimental bases necessary for the production of quantitative compositional maps By electron, ion, and neutron beam techniques. Further

investigations will be made to evaluate the possibilities of selective

organic compound mapping by photon excitation.

The main theoretical and experimental approaches can be divided into

three sections:

• Lateral compositional mapping by electron beam x-ray microanalysis requires modeling of the electron-specimen interactions,

particularly for the important class of rough specimens, and

development of algorithms for rapid calculation. Compl ementary

experimental work will be performed to develop new systems for

rapid spectral acquisition.

• Lateral and depth compositional mapping by secondary ion mass spectrometry (ion microprobe) requires fundamental theoretical

studies on the mechanisms of secondary ion formation and on the

modification of secondary ion intensities by chemical state.

Experimental studies will be conducted on techniques of rapid

spectral acquisition and processing by computer control of the

mass spectrometer.

• Depth compositional mapping by neutron irradiation requires

development of the theoretical basis for quantification through

accurate modeling and for unfolding the charged-particle energy

spectrum. Experimental measurements are needed to determine

the matrix dependency of the charged-particle stopping power

and to improve depth resolution and elemental sensitivity.

Upon establishment of this knowledge base, the techniques can

be applied to the measurement of interesting new isotopes,

e.g., 26ai.

24
The development of quantitative compositional mapping will aid

on-going research programs in CAC and elsewtiere at NBS, as well as otheragency sponsored research programs, for example the AFTAC program on the

characterization of particulates and the DOE project on the analysis of

fusion reactor first-wall reactions. The specific measurement problems

which can be addressed by these techniques include the characterization'

of metals, ceramics, semiconductor materials, and particulates, analysis.

The behavior of many systems of profound interest to the physical and

biological sciences, as well as many technological processes, are con- trolled by compositional variations on a spatial scale of 1 micrometer

or less, and therefore, quantitative compositional mapping techniques can

have great impact across a diverse range of scientific and engineering

endeavors

.

"A

25
F. Instrument Development Group

1 . Group Overview

The main objective of this group is the development of new approaches

to performing accurate chemical analyses. The group is working in two

general areas: (1) investigating the use of lasers for chemical analysis;

and (2) providing assistance to the Center staff on matters of instrument

design, computer control, and processing of data.

James R. DeVoe

a . Laser Project Overview

Laser sources, with their high power, coherence, and spectral purity, are being used increasingly in analytical chemistry both in spectroscopy

and in other applications. The rapid advances in laser technology and

applications in physics and other branches of chemistry require research

capabilities within the Center both to contribute to the advances and to

effectively capitalize on developments elsewhere. The research in laser

chemistry is threefold: basic and applied research in laser enhanced

ionization; collaboration within the Center on the use of lasers in

analytical applications; and collaborative efforts with other Centers

when their work has potential analytical application.

Several' investigations were completed during this year. Although no LEI signal was observed using a spark discharge several other interesting

results were observed and were recently published. Multi -photon ionization of organic molecules has been completed and is reported below in the

Technical Accomplishments section. Considerable progress has been made on the mechanism of LEI in flames. The inoperability of lasers has limited

progress in certain areas. We have been unable to complete our semiconductor diode laser project because of a succession of diode failures.

The stepwise multi-photon LEI in flames was not begun this year because of

an inoperable flash! amp pumped system. Recently, we have purchased the

beginning of a laser system that should perform adequately.

Our plans for LEI are to continue to study the fundamental processes

for signal production and collection. These studies have already led to

significant changes in electrode design and photo-excitation techniques.

We have established that the basic principles of the quantitative analysis

are sound and that the potential accuracy is high because of the interference-free nature of the spectroscopy. However, the technique is not

immune to the interferences generally encountered in solutions that are aspirated into flames. For this reason we are interested in investigating

the technique in other atom reservoirs, such as the solution aspirated

into an inductively coupled plasma, hollow cathodes, various types of

26
sparks, and totally new designs that involve combinations of techniques.

Each of these areas, however, involves many man-years of effort. We plan

to collaborate as much as possible with outside laboratories in this area.

Our long term plan is to develop the LEI in flames to a point where

a quantitative analytical system can be assembled. At this point in our research, the "system" has been changing too rapidly to warrant assembly

of the quantitative system. If a quantitative system can be assembled

within the next two years, many types of real samples will be run in order

to evaluate the effectiveness of LEI.

Several of our earlier investigations have led to new projects that

are to be conducted in collaboration with staff in the various divisions.

For example, the multi-photon ionization of organic molecules has led to

a series of projects as part of competence building with the Organic

Analytical Research Division. Other projects include laser assisted hot

filament ionization and IR semiconductor diode absorption studies in the

Inorganic Analytical Research Division and the Gas and Particulate Science

Division, respectively.

Thomas C. O'Haver, Robert L. Sams, Richard Simon, John C. Travis,

Gregory C. Turk

b. Instrumentation Project

An important contribution to the progress of research and development

activities is technical support in electronic, mechanical, automation

and computer system design. Support is being provided in five major

areas: research involving the use of a new electronic design for current

analytical instrumentation; the interaction of computer systems with

analytical instrumenation; the design of mechanical components; the repair

of all types of electronic and electromechanical equipment; and the

utilization and/or lending of special test equipment for various experiments conducted within the Center.

There has been increased collaboration and interaction with scientists

outside of the Center. Specifically, work is in progress or planned with

staff in the Center for Materials Sciences, and the Center for Thermodynamics and Molecular Sciences on projects involving use of computers

for data collection and processing. In addition, we have participated on

a number of committees related to the use of computers at MBS (see

appropriate sections below).

Andrew Beals, Lisa Bergen, John K. Langland, Robert McDiffett, Scott Mund,

Fillmer C. Ruegg, Ronald W. Shideler

27
2. Selected Technical Accomplishments

a , Studies of the Charge-Collection Mechanism in Laser Enhanced Ionization Spectrometry

The use of laser enhanced ionization (LEI) in flames for chemical

analysis was proposed by us in 1976 [1], and has been the subject of

a number of papers since then [2-8]. The principle behind the method,

also known as the opto-gal vanic effect, is that the volume ionization

rate of an ionizing medium (such as a flame or discharge) is changed when

a laser is used to significantly perturb the electronic state population

distribution of a species present in the medium [9-12]. This perturbation is observed experimentally as a change in a current passed through

the flame using external electrodes.

During the past year research was performed in collaboration with

P. K. Schenck, of the Chemical Stability and Corrosion Division (561),

CMS. The object of the research was to demonstrate the consistency of the

spatial and temporal characteristics of the laser enhanced ionization

signal with fundamental theoretical expectations based on a one-dimensional

model. Three distinct types of experiments were performed:

(1) Voltage/current (V/I) characteristic curves were obtained for a variety of aspirated solutions, with and without laser irradiation.

These studies revealed the response of the bulk electrical properties of

the H 2 /air flame — the volume ionization rate, the positive ion space

charge, and the electrical potential and field distribution — to changes

in the sampled solution and laser excitation. At low applied voltages

(V < 200 V) the 2 mm diameter laser beam appeared to increase the

Q p

|J ionization rate throughout the 1 cm wide flame, indicating a significant role for ion diffusion.

(2) Signal rise and fall time were measured as a function of electrode

potential difference. In the high voltage limit (V > 200 V) the rise

d p p and fall times were found to obey the expected correlation with ion mobility,

electrode separation, and applied voltage. The total charge arriving at

the electrode (the integral under the current probe) was found to be

independent of voltage. This fact is taken to indicate 100 percent

efficiency in ion collection, since any postulated ion loss mechanisms

(recombination, volume replacement, etc.) should be more effective for

long ion extraction times (lower voltages) than short extraction times

(higher voltages). At voltages < 200 V the signal deteriorates due to

space charge shielding of the electric field.

(3) One dimensional ion imaging was employed to profile the flame

ionization rate as a function of height above the burner head. To the

best of our knowledge, this is a new technique, and a patent search is

in progress. The imaging is accomplished with the electrode configuration

shown in figure 1, in which the small, moveable probe rod intercepts

a "slice" of the ions being transported by the well-defined field of the

28
Figure 1. Apparatus for ion imaging.

parallel plates. Figure 2 shows a profile of the ionization rate taken

with the system for an aspirated, 1 ppm Na solution, and 15 mW of laser

excitation of the 589.0 nm transition. The ionization rate is seen to

diminish smoothly from the reaction zone upward, with the pronounced

exception of the "bulge" at 1 9 mm owing to laser excitation. Use of the

full available 200 mW of laser power reduces the background component

proportionally. By chopping the laser and using synchronous detection,

the background component may be eliminated altogether, leaving only the

laser-produced ion image. Such images are shown in figure 3 for two

magnitudes and signs of high voltage applied to the HV electrode. For

large potential drops, the image is sharp, and centered at the laser

position. For low potential drops, the ion image spreads by diffusion

and coulometric repulsion, and moves in the direction of the flame

velocity. The collection of electrons (-HV) or positive ions (+HV) yields

shape differences resulting from the vast difference in mass. The ion

images confirm that ion losses to diffusion and flow removal are trivial

at high voltages, again supporting a postulate of 100 percent efficient

ion collection.

These experiments demonstrate significant agreement with theory

illustrating the relative roles of the volume ionization rate, applied

voltage and resulting current, flame and cold-air ion mobilities, electric

field strength, laser power, diffusion, and electro-static repulsion.

Several conclusions stated in the manuscript [13] resulting from the

research are:

1) The results imply 100 percent ion collection efficiency for

high applied potentials;

29
o

m

CO

*

o

CO

LO

CM

o

CM

.. in

m

B\B\i uoj^ezjuoi 9A!}e|9y

30

Height

(mm)

Figure

2.

Ionization

rate

height

above

the

burner

shows

a

distinct

peak

at

the

position

of

the

laser

beam

for

a

1

ppm

Na

solution,

and

15

mW

of

laser

irradiation

20

mm

above

the

burner

head.
to

CM

o

CM

uoitezmoi aAneiay

31

Height

(mm)

Figure

3.

Images

of

ionization

caused

by

the

laser

beam,

separated

from

the

background

by

synchronous

detection,

for

repelling

potentials

of

-2000

V

(*)

,

+2000

V

(0),

+250 V

(X)

and

-250

(+).
2) The steady-state excess ion distribution becomes considerably

larger than the 1 aser-irradiated volume for voltages well below electrical

saturation of the flame;

3) The one-dimensional spatial ion-imaging technique should be a useful tool for combustion research — with or without laser irradiation;

4) Laser enhanced ionization is an attractive means of selectively

increasing the ionization rate at a well defined position and time in a seeded flame;

5) The concepts developed should be useful in the further refinement of the analytical application of LEI.

References

[1]

Green, R. B., Keller, R. A., Schenck, P. K., Travis, J. C.,

and Luther, G. G., J. Am. Chem. Soc . 98, 8517 (1976).

[2] Turk. G. C., Travis, J. C., DeVoe, J. R., and O'Haver, T. C.,

Anal . Chem . 817 (1978).

[3] Travis, J. C., Turk, G. C., and Green, R. B., Chapter 6 in

New Applications of Lasers to Chemistry, G. Hieftje, ed.,

ACS Symposium Series American Chemical Society, Washington,

D.C., 91 (1 978).

[4] Schenck, P. K., Mallard, W. G., Travis, J. C., and Smyth, K. C.,

J. Chem . Phys . 5147 (1978).

[5] Turk, G. C., PhD Dissertation, University of Maryland (1978).

[6] Gonchakov, A. S., Zorov, N. B., Kuzyakov, Yu. Ya., and Mateev,

0. I., Anal . Lett. 12A, 1037 (1979).

[7] Turk, G. C., Travis, J. C., DeVoe, J. R., and O'Haver, T. C.,

Anal . Chem . 1890 (1979) .

[8] Turk, G. C., Mallard, W. G., Schenck, P. K., and Smyth, K. C.,

Anal . Chem . 2408 (1 979).

[9] Van Dijk, C. A., PhD Thesis, University of Utrecht, The Nether1 ands (1 978)

.

[10] Travis, J. C., Schenck, P. K., Turk, G. C., and Mallard, W. G.,

Anal . Chem . 1 516 (1979).

[11] Van Dijk, C. A., and Alkemade, C. Th. J., Combust. Flame 38, 37

(1 980).

32
[12] Smyth, K. C. , Schenck, P. K. , and Mallard, W. G. , to be published

in the Proceedings of the American Chemical Society Symposium

on Laser Probes of Combustion Chemistry.

[13] Schenck, P. K. , Travis, J. C., Turk, G. C., and O'Haver, T. C.

,

submitted to the NBS Washington Editorial Review Board for

approval

.

J. C. Travis, G. C. Turk, T. C. O'Haver

b. Atomic Resonance-Line Lasers for Atomic Spectrometry

A new class of lasers has been developed at the Lincoln Laboratory

of MIT which shows much promise as light sources for analytical spectroscopic measurements [1-3]. These lasers are unique in that they

produce laser light at fixed frequencies corresponding to atomic resonance

lines. Other fixed frequency atomic lasers (i.e. HeNe, Cu, Pb, Hg) yield

only nonresonance (excited state to excited state) transitions, which

produce wavelengths of little use to the analytical spectroscopist.

With the purpose of demonstrating the feasibility of such lasers for

analytical spectroscopy a joint experiment was performed with D. J.

Ehrlich and R. M. Osgood, Jr. at the Lincoln Laboratories, MIT. The new

lasers were utilized as excitation sources for trace metal analysis via

laser enhanced ionization (LEI) spectrometry.

The principle behind the atomic resonance laser (ARL) is the direct

population of metal atom excited states through UV photodissociation of a metal halide, thereby producing an initial population inversion in the

atomic species. The ARL itself is very simple, consisting of a 10 cm x 2.2 cm diameter spectrophotometer cell, evacuated except for a small

amount of the appropriate metal halide and resulting vapor. Photodissociation of the halide is accomplished by optical pumping with an excimer laser. To date, lasers have been constructed for Na, K, Rb, Cs,

T1 , In, Ga, and A1

.

Laser enhanced ionization signals of thallium and sodium were studied,

using Til and Nal lasers. Partial energy level diagrams for T1 and Na are given in figure 4, showing the origin of the atomic laser lines for

the two lasers. Table 1 summarizes the operating characteristics of the

two lasers and the LEI analytical results. Excellent detection limits

were achieved with a linear dynamic range of 10^.

33
Energy

Above

Ground

State

(cm

Tl Na

S P S P

Figure 4. Partial energy level diagram for Til and Nal lasers, showing

origination of atomic laser lines.

34
Table 1. Operating Characteristics and Analytical Results for T1 1 and

Nal Lasers.

Til Nal

Resonance Wavelength(s) , nm 377.6 589.0, 589.6

Energy/Pulse, yJ 9 0.1

Nonresonance Havel ength(s) , nm 535.0 1140.3, 1138.2

Energy/Pulse, yJ 30 5 Operating Temperature, ®C 380 660

El ement Analyzed T1 Na

Limit of Detection, ng/mL 3 0.3

Linear Dynamic Range, Orders of ^\^4 -^4 Magnitude

A unique aspect of the Nal laser for LEI is the presence of the

1,140 nm nonresonance line whose lower level is the same as the upper

level of the resonance line. This situation results in a two-photon

stepwise excitation of Ma atoms, a great advantage for LEI since it

allows population of an excited state close to the ionization limit. In

this case the stepwise excitation resulted in a 13-fold sensitivity

enhancement over that of single photon excitation. The ultimate analytical impact of the atomic resonance line photodissociation laser will

depend on the number of elements for which such lasers are eventually

constructed. In the meantime, the lasers demonstrated here, as well as other available lasers, may well be the source of choice for many

specific, dedicated applications.

References

[1] Ehrlich, D. J., Maya, J., Osgood, R. M. , Appl . Phys. Lett. 33,

931-933 (1 978).

[2] Ehrlich, D. J., Osgood, R. M., Appl. Phys. Lett. 34, 655-658

(1979).

[3] Deutsch, T. F. , Ehrlich, D. J., Osgood, R. M., Jr., Opt. Lett.

4, 378-380 (1979).

J. C. Travis, G. C. Turk

35
c. Reduction of Ionization Interferences in Laser Enhanced Ionization

Spectrometry

Laser enhanced ionization (LEI) spectrometry in flames is based on the electrical detection of the thermal ionization of excited state atoms or molecules produced by laser excitation. For many elements a very high

level of sensitivity is possible, but general application to the analysis

of complex samples has been hampered by the method's susceptibility to

ionization interference. This interference results from the unassisted

thermal ionization of low ionization potential elements in the sample

matrix. Recent advances in our understanding of how the LEI signal is

collected have resulted in a better understanding of why this interference

occurs, and have led to an experimental modification which has greatly

reduced LEI susceptibility to ionization interference.

Electrical detection of LEI requires that an electric field be

applied to the region of the flame being irradiated by the laser. Because

of the vastly different mobilities of electrons and positive ions, this

field is in most cases not uniformly distributed between the anode and

cathode, but rather is concentrated near the cathode in a region known as the cathode fall or as the cation sheath. This sheath becomes larger

as higher voltages are applied, but compresses as higher ion concentrations

are encountered, as when significant matrix ionization is occuring. Most

LEI work to date has utilized a split cathode configuration, where the

burner head is used as the anode and a pair of metal plates just outside

opposite sides of the flame form the cathode. This configuration has the

advantage of leaving the flame physically unperturbed. However, in the

presence of high ion concentrations resulting from matrix ionization, the

cation sheath can collapse to within a very short distance from the

cathode plates. When this occurs no electric field exists inside the

flame near the laser beam, and consequently no LEI signal is collected.

A new electrode configuration has been developed which greatly

reduces LEI susceptibility to ionization interferences. A water cooled

cathode, constructed from 1/4" diameter stainless steel tubing is placed

directly into the flame, one cm above the burner head anode. This allows

the laser beam to be positioned very close to the cathode surface, thus

reducing the possiblity of the beam being outside of the sheath. Water

cooling prevents deterioration of the cathode. No contamination or memory effects have been observed.

Figure 5 shows the effect of varying the sodium concentration (matrix

effects) on an LEI signal observed for 50 yg/mL of Fe for both the

external split cathode plate configuration and the new internal watercooled cathode. A 1500 V potential is applied in both cases. The new configuration has improved the LEI tolerance from ^ 100 yg/mL to over

3,000 yg/mL to the sodium matrix effect. The maximum allowable concentration of sodium ions in the aspirated solution is limited by arcing, which

36
150

AaaAOoaa %

37

30

100

300

10^

SODIUM

CONCENTRATION

(/ig/mL)

The

effect

of

sodium

on

the

recovery

of

an

LEI

signal

for

50

lag/mL

of

iron.
occurs at -v 5000 yg/mL. This is a major improvement to LEI spectrometry

allowing a more accurate analysis of a wide variety of complex samples

containing easily ionizable materials.

G. C. Turk, J. C. Travis

d. Detection Limits of Some Trace Molecules of the Atmosphere by IR Diode

Laser Absorption

All molecules except homonuclear diatomics have an infrared spectrum.

This fact, in conjunction with the newly developed tunable infrared diode

laser sources that have high spectral purity and power, make possible the

detection of trace species by IR radiation absorption. We have set up a tunable diode laser system that incorporates a diode laser with some

external optics and additional electronics as shown in figure 6. This

system allows the use of second derivative modulation techniques with a long-pass White cell. In this way, very low (ppt) detection limits were obtained for numerous molecules as shown in Table 2. First and second

derivative techniques were used to discriminate from the baseline.

Improvement in the net signal was at least 10^ over conventional absorption measurement techniques. The signal -to-noise of the weakest line

corresponds to an absorption coefficient of 5 x 10"® m”^ for a 40 m cell.

The total cell volume is 8 liters which means that the amount of sample

needed for 1000 Pa pressure (normal operating pressure) is 5 millimoles.

The technique is not only very sensitive but quite selective at the

pressures used. Further increases in sensitivity are anticipated in the near future by using more stable diodes which will enable the use of

longer time constants and signal averaging. This effort is the forerunner

to a project in cooperation with the staff of the Gas and Particulate

Science Division on the accurate measurement of molecular species in the

atmosphere.

38
39

Figure

6.

Block

diagram

for

experimental

set-up.
Table 2. Detection Limits of Trace Constituents of the Atmosphere.

Band

Molecule Band Transition

Pathlength

(m)

Strength

cm"^ atm"^

Detection

Limit^

N 2 O 00°l-00°0 R(8) 24 1173 200

NO 2 00°l-00°0 1^1 5l6"^72 ,17 40 2000 100

CS 2 11^1-01^0^ P(27) 24 2220 40

CO 2 04°l-04°0^’^ P(23) 40 2440 20

OCS 04°0-0°0^ P(15) 24 2400 20

^The actual measured transitions were from these bands. The detection

limits in column 6 were estimated using relative band strengths.

^Strongest band.

Extrapolated detection limit (i.e., signal is twice the standard

deviation of the noise) in ppt for strongest band.

*^Line was actually ^^C02 at -80 °C (dry ice) temperatures.

R. L, Sams, J. R. DeVoe

t .

40
e. Trace Organic Analysis by Multi photon Ionization

Resonance-enhanced multi photon ionization (MPI) is an especially

promising technique for the detection of trace organic species in the

vapor phase using high-powered, tunable lasers. The technique, which was developed at New York University (Stoneybrook) , utilizes a laser beam

which passes into the gas of a proportional counter or ion chamber. The

photoionization process is detected by measuring the current produced from

the detector which is in coincidence with the laser pulse. The method has

potential for very low detection limits with high selectivity. Unfortunately, with large organic molecules, the optical selectivity is inherently

poor due to the spectral density resulting in line overlap. Because of

this, our initial investigations of the technique have assumed the need

for further selectivity by such means as multiphoton laser excitation

coupled with gas chromatography and/or mass spectrometry.

Experiments with chlorobenzene and napthalene have shown the expected

spectral character, and sensitivity at the 10 ppb level in air, using our

flashl amp-pumped laser. The MPI spectrum of chlorobenzene at 2 ppm in

air is shown in figure 7. The intense band head at 37050 cm”^ is used

for analytical measurements.

An especially revealing series of experiments utilized a gas chromatograph with a hybrid MPI/electron capture detector (ECO), as shown in

figure 8. Representative chromatograms are shown in figure 9. In the top

series, (a) through (c), the ECO is operated normally, showing two solvent

peaks followed by a chlorobenzene peak. When partial (b) and full (c)

laser power is applied, the ECO response to chlorobenzene is enhanced over

the unperturbed (a) case. The origin of this behavior is not obvious,

but the possibility of photofragmentation should be considered. When the

normal ECD sensitivity is drastically reduced by the use of a reverse bias

(series d - f) laser-produced ionization for partial (c) and full (f) laser

irradiation may be seen as a negative-going hash. The ionization signal

is negative because ECD response is electron absorption , and the signal

is ragged because the laser is pulsed. The perturbation to the chlorobenzene peak is taken to correspond to resonance-enhanced MPI (figure 7).

The perturbation at the trailing edge of the solvent peak is a puzzle,

but could represent non-resonant photo-detachment of an electron from a negative solvent ion.

We plan to investigate these observations in future studies using mass spectrometric detection and a more suitable laser.

R. K. Simon, J. R. DeVoe, J. C. Travis

41
i

42

'1

PHOTON

ENERGY

(cm"')

Figure

7.

Partial

MPI

spectrum

of

chlorobenzene

in

the

37,000

cm’i

region
Figure

CMX-4

Pulsed

Dye Laser

12.5 cm Focal Length

Lens

Beam

Splitter

UV

Filter

Mirror

. Experimental arrangement for GC detection with a laser-irradiated electron capture detector.

43
No Laser Partial Laser Power Full Laser Power

Figure 9. Gas chromatograms showing solvent and chlorobenzene peaks with

the ECD normally biased (top) and reversed-biased (bottom).

Effects due to the laser in the chlorobenzene (third) peak are seen by comparing laser off (left) to laser on (center = 50% attenuated; right = full laser intensity) chromatograms.

The laser effect on the solvent peak (bottom right) is taken

to represent wavelength-independent electron photo-detachment.

44
f. Instrumentation Project

The people in this project interface with all Center personnel to

provide technical support in the areas of computers and instrumentation.

The work performed can be classified into three major areas: 1) microcomputers (microprocessors) for data acquisition, manipulation, and

instrument control; 2) instrument design and modification; and 3) instrument-computer repair. Selected examples of the work in each category

are:

1) Microcomputers — development of a microcomputer based

system consisting of one 16 bit microcomputer, 1 Mbyte

of memory, parallel-serial I/O, terminal, CRT, dual

floppy discs with BASIC and FORTRAN costing $7K that

has an overall performance approximately equivalent to

a POP 11-34 minicomputer-adaptation or updating of

microcomputers for use on ESCA-Auger spectrometers,

IR diode laser system, gas handling systems, and low

level ^‘^C radiation counters to provide foregroundbackground capabilities;

2) Instrument design, construction and modification —

construct triple filament controller for mass spectrometry, nuclear waste container scanner incorporating a unique stepping motor drive designed to

minimize vibration, an optoacoustic detector, and

a potentiostat for fast electrochemical reactions;

and

3) Instrument-computer repair - in addition to the

usual types of instrument repair, the increasing

use of microcomputer systems results in the need

to replace defective boards and floppy discs,

upgrade software, and develop special software.

R. W. Shideler, F. C. Ruegg, J. K. Langland, B. McDiffett, S. Mund,

A. Beals, L. Bergen

45
3. Outputs and Interactions

Publ 1 cations

Turk, G. C., Mallard, W. G., Schenck, P. K., and Smyth, K. C., "Improved

Sensitivity for Laser Enhanced Ionization Spectrometry in Flames via

Multiple Wavelength Stepwise Exitation", Anal . Chem . 51 , 2408-10, (1979).

Turk, G. C., Travis, J. C., DeVoe, J. R., and O'Haver, T. C., "Laser Enhanced

Ionization Spectrometry in Analytical Flames", Anal. Chem. 51 , 1890-90

(1979).

Travis, J. C. and DeVoe, J. R., "Optogal vanic Spectroscopy", scheduled for

publication in Lasers and Chemical Analysis , Hieftje, G. M., Lytle, F. E.,

and Travis, J. C., eds., Humana Press, Clifton, N. J. to be published.

Travis, J. C., editor with Lytle, F. E., and Hieftje, G. M., "Laser and

Chemical Analysis", Human Press, Clifton, N. J. to be published.

Proceedings of the 1979 Analytical Chemistry Summer Symposium.

Ehrlich, D. J., Osgood, R. M., Jr., Turk, G. C., Travis, J. C., "Atomic

Resonance-Line Lasers for Atomic Spectrometry", Anal. Chem. 52, 1354-5

(1980).

Green, R. B., Keller, R. A., Luther, G. G., Schenck, P. K., Travis, J. C., United

States Patent No. 4,184,127, Jan. 15, 1980 entitled "Frequency Stabilized

Laser"

.

Scheeline, A., Travis, J. C., DeVoe, J. R., Watters, J. P., "Discovery of an Electrical Post-Pulse in the Surroundings of a High Voltage Spark Discharge"

Accepted for publication Spectrochimica Acta B.

Scheeline, A., Norris, J. A., Travis, J. C., DeVoe, J. R., Walters, T. P.,

"Particulates Formed by a Stabilized High Voltage Spark Discharge",

accepted for publication Spectrochemica Acta B.

Maki, A. G., Olson, W. B.,_Sams, R. L., "High Resolution Infrared Spectrum of

the 859 and 1711 - cm~^ Bands of Carbonyl Sulfide (OCS)", J. Mol. Spectros.

^(1980).

Sams, R. L., Olson, W. B., "Analysis of the_High Resolution Infrared Spectrum of

the V2 Bending Mode of HOCl at 1238 cm~^", Mol . Spectrae accepted for

publ i cation.

Seger, P. M., and Sams, R. L. , "Diode Laser Spectra of the V2 Band of H 2 ^^CO

and H 2 ^^CO", Mol . Spectrae . Accepted for publication.

46
b. Tal ks

J. R. DeVoe, "Laser Enhanced Ionization in Flames", Eastern Analytical

Symposium, New York, N. Y. Oct. 1979 (invited).

R. L. Sams, J. R. DeVoe, "Measurement of the V 3 Band of by Tunable

Diode Laser", Thirty-fifth Symposium on Molecular Spectroscopy, Ohio

State University, Columbus, Ohio, June, 1980.

R. Simon, "Mul ti-photon Ionization of Organic Compounds" Seminar, Chemistry

Department, Kansas State University, July 9/25, 1980.

c . Invited Tal ks by J. C. Travis

(with G. C. Turk, S. J. Weeks, and J.r R. DeVoe) "Trace Metal Analysis by Laser

Enhanced Ionization in Flames", Expochem '79; Houston, Texas; Oct. 22, 1979.

"Laser Enhanced Ionization in Flames", Chemistry Dept. Colloquium; Villanova

University; Philadelphia, PA.; Nov. 27, 1979.

"Perspectives on The Use of Lasers for Chemical Analysis", New York Academy of

Sciences; New York, N. Y.; Dec. 13, 1979.

"Perspectives on The Use of Lasers for Chemical Analysis", Center for Analytical

Chemistry Colloquium; National Bureau of Standards; Washington, D. C.; Dec. 19,

1 979.

"Laser Opto-gal vanic Spectroscopy for Trace Metal Detection", Society for

Applied Spectroscopy, Bal timore-Washington Section; Rockville, Maryland; Feb.

19, 1980.

"Laser Enhanced Ionization in Flames for Trace Metal Analysis", Chemistry

Department Seminar, University of Florida; Gainesville, FL; Oct. 22, 1980.

(with Richard K. Simon and James R. DeVoe) "Selective Laser Ionization for

Atomic and Molecular Trace Analysis", Dept, of Energy "Workshop on Advanced

Laser Technology for Pollutant Measurements; Harper's Ferry, W. Va.; June 10,

1980.

(with G. C. Turk and P. K. Schenck), "Progress in Laser Enhanced Ionization",

Federation of Analytical Chemistry and Spectroscopy Societies (FACSS-VII);

Philadelphia, PA.; Sept. 30, 1980.

d. G. C. Turk Talks, Sept. 1979 - Sept. 1980

"Laser Enhanced Ionization Spectrometry", G. C. Turk, University of Maryland,

Analytical Chemistry Division Seminar, College Park, Md., Oct. 1979.

"Reduction of Matrix Interferences in Laser Enhanced Ionization Spectrometry",

G. C. Turk, J. C. Travis, and J. R. DeVoe, 7th Annual FACSS Meeting,

Philadelphia, Pa., Sept. 1980.

47
"Atomic Resonance-Line Lasers: New Sources for Analytical Atomic Spectrometry",

P. J. Ehrlich , R. M. Osgood, Jr., G. C. Turk, and J. C. Travis, 7th Annual

FACSS Meeting, Philadelphia, Pa. Dept. 1980. (Keynote Talk).

e. Committee Assignments

James R. DeVoe

CAC Committee on Computer Requirement

NBS Committee on Selection of Microprocessor for the Storeroom

NBS Computer Evaluation Committee

F. C. Ruegg, Jr.

NBS Committee on Selection of Microprocessors for the Storeroom

R. W. Shideler

NBS Committee for Electronic Storeroom

J. K. Langland

NBS Committee for Electronics Storeroom

NBS Committee on Selection of Microprocessors for the Storeroom

48
II. Inorganic Analytical Research Division

Ernest L. Garner, Chief

Thomas J. Murphy, Deputy Chief

A. Division Overview

The diverse analytical competences in the Inorganic Analytical

Research Division are organized functionally into the four broad areas of activation analysis, atomic and molecular spectrometry, analytical

mass spectrometry, and el ectroanalytical chemistry. This structure

provides both the flexibility and the analytical capability to address a wide variety of research problems and also to analyze the full range of

materials utilized in the various research activities at NBS, other

Federal agencies and, when requested and appropriate, other institutions,

either private or public. Within this framework, the research and measurement priorities of the Division are established on the basis of

potential public benefit and of developing the science to accurately

determine the concentration of inorganic species in the numerous materials problems which confront government and industry.

During the past year, the Division witnessed a continuation of the

growth and proliferation of demands for inorganic analytical chemistry.

These requests reflect a broad spectrum of needs ranging from the users of calibration or unique service analyses to the agencies/organizations

primarily concerned with analytical chemistry as a tool for the solution

of problems of national and/or international impact. With ever increasing frequency, this constituency is seeking accurate multi -element data

for complex matrices such as drilling mud, sludges, retort water, high

performance metals, oil shale, and effluents or leachates from a variety

of manufacturing and process streams. The reality of our current position with respect to the need for more accurate multi -element data is

reflected by the lack of a single technique, either free of matrix

interferences or with the dynamic calibration range, to accurately

measure 10 or more trace elements in a complex matrix. As such, a major

thrust in the Division's long term research is the ultimate development

of basic calibration methodology which will yield accurate multi-element

measurements for trace elements under a variety of matrix and concentration conditions.

With multi-element analysis as one of several pressure points, the

past year's activities reflect a predominant orientation to analytical

measurements with a significant effort devoted to developing new or improved methods. For example, research to more accurately characterize

Standard Reference Materials included the development of D.C. plasma

spectrometry for trace element analysis, and reference methods for

bismuth, iodine, aluminum, and carbon in material types which range from

biological to sophisticated high performance metals. In addition to

this research, a major effort, approximately 25 percent of the total

,

was devoted to analytical measurements to certify SRM's.

49
other applied research and measurement, in support of major NBS

activittes or in direct support of other government agencies, provided

assistance to the Recycled Oil Program, Environmental Measurements,

Nuclear Safeguards, Resource Recovery, the National Environmental Specimen

Bank, Trace Element Profiles for the Chesapeake Bay, and Trace Elements in

Biologies and Injectibles. As an example, the activities with respect to

recycled oil provide a diversified mix of research to develop an operational ICP system for high sensitivity mul ti -el ement analysis of selected

elements in oil, methods evaluation and speciation studies by atomic

absorption, analytical measurements and speciation studies by activation

analysis, investigations to evaluate ion chromatography as a quantitative

method for chlorine and bromine, and also an assortment of service

analyses

.

Fossil fuel waste sampling and characterization, acid rain, and trace

metals in different injectable types of biological materials represent new research and measurement activities. An ultimate goal in each of these

areas is the production and accurate characterization of trace elements in

quality assurance materials or Standard Reference Materials. For fossil

fuel waste residues, a multi-year effort is oriented to developing the

analytical methods, leach protocols, and quality assurance materials to

accurately characterize both the leachate and waste residues of the highly

variable waste streams of conventional and emerging technology fossil fuel

power plants. As a part of this research, a rotary extractor for leach

studies has been constructed and preliminary testing completed. This unit

as well as improved leach protocols and a synthetic leachate represent

significant progress in establishing an accurate data base for waste

residues such as coal fly ash, coal bottom ash, sludges, and other

effluents from the residues of power producing plants.

In high accuracy measurements, a redetermination of the atomic weight

of silver was completed. The overall accuracy of this is expected to be

approximately 1 in 10®. At this significantly improved accuracy, the

uncertainty in the atomic weight of silver is no longer a major factor in

the calculation of a high accuracy value of the Faraday constant from the

electrochemical equivalent of silver. The NBS atomic weight research

represents one of the few remaining sources of new atomic weight data and

is one of the prime reasons for continued improvement in the precision of

isotopic ratio measurements. This improvement is demonstrated by recent

isotopic measurements with precisions equal to or greater than those

obtained in the gravimetric preparation of synthetic calibration mixtures.

For next year, planned activities will focus on automation and

research to increase sensitivity, accuracy, and multi-element capability

for trace elements. One of the more urgent automation needs is the

design and construction of rotators, sample changers, and manipulators

for automated irradiation and counting of samples by activation analysis.

In this connection, a new computerized system for instrument control,

data acquisition, computation, and statistical analysis of data will also

be required to handle the increased volume of samples which is anticipated

over the next several years. Recent advances in microprocessor technology

will definitely allow improved control of mass spectrometers and will.

50
over a multi-year period, lead to fully automated instruments for both

high precision and high accuracy measurements. The third area of immediate concern is the wfiole process of data acquisition, correlation, curve

fitting, interelement corrections, and background corrections leading to

improved calibration in emission and atomic absorption spectrometry.

Compositional depth profiling and mass spectrometry are target areas

for increased research. The intent of depth profiling is to develop a facility at NBS for depth location of selected elements using thermal

neutron induced reactions. The ultimate goal of this research is to

demonstrate the limits of resolution and sensitivity and to extend the

technique to isotopes other than ^He, ^Li, and Research in mass spectrometry will focus on the use of lasers and other techniques to

better understand some of the processes which will improve the sensitivity

and accuracy of isotopic measurements.

Calibration methods which are applicable over a large dynamic range

and for a large number of different matrices are keys to improving the

quality of multi -element data. As such, the multi -element problem will

be attacked on several fronts with immediate goals of improving the calibration methods for the ICP and as a means of making emission spectrometry

more quantitative. Closely related to this effort is the continuing

effort to utilize wavelength modulation in conjunction with a high

intensity continuum source and an echelle monochromator to reduce the

effects of interference in atomic absorption measurements. This basic

approach has significant potential for multi-element analysis. Finally,

epithermal activation analysis techniques in conjunction with an antiCompton shield will be investigated as a means of improving the quality

of multi-element measurements. Ultimately, several of the activation

techniques must be explored as a means of quickly and accurately

establishing the concentration levels of a large number of elements.

Two new areas which are expected to become targets of opportunity

for long-term research are measurements and standards for nuclear waste

management and metal speciation studies. Nuclear waste disposal is a major national problem requiring a coordinated effort from various units

of the Division to produce accurate trace and ultratrace element measurements of glasses, basalts, and other potential storage materials for

long-lived radioactive waste. For speciation, the need to know not only

the accurate concentration of trace elements but also the chemical species

will require a multifaceted approach. The ultimate development of this

capability will have a profound impact in areas such as energy production,

environment, industrial processes, food, nutrition, and health.

1 . Activation Analysis Group: Overview

Research in activation analysis at NBS is a continuing effort to

improve analytical accuracy, sensitivity and selectivity in diverse

matrices of technological and scientific importance. Improved measurements in activation analysis can be realized both by systematic

evaluation and elimination of errors associated with current methods.

51
and by the development of new and improved techniques. Both approaches

have been used to improve the measurement capability in trace analysis.

Innovation within the group and work at the frontier of the field has

earned the respect of the trace analytical community. This group is

looked to for leadership in nuclear methods for accurate trace analysis.

The group members continue to develop specific competences in the areas of reactor neutron activation analysis (NAA), photon activation analysis

(PAA), nuclear track technique (NTT), and prompt gamma activation

analysis (PGAA).

The Activation Analysis Group is conducting research and analysis

in four basic areas. Basic research is aimed towards the improvement of

the analytical measurement system using nuclear techniques. The end

result of this activity is to have a constantly expanding analytical

capability which can be applied to all areas of elemental analysis.

Applying analytical research to specific programs, the group utilizes its

capability to provide reliable analytical data for the study of systems

dependent on trace elemental composition. Analyses performed on new Standard Reference Materials are an extremely important area of the

group's activity. Special emphasis is placed on the accuracy of analytical results. A small but important part of the group's analytical program

is "service analysis." This is chiefly undertaken to expedite other

programs, by providing crucial analytical data, or a unique measurement

when needed. The activities in the different program areas keep the group

members aware of developments in other fields, and in many instances the

"real world" samples obtained for analysis spur new research ideas.

Recent accomplishments in research are highlighted by the contributions to the establishment of a "definitive" or reference method for the

determination of aluminum. Other continuing efforts on the selective

analysis of specific elements have led to the development of two independent procedures for the determination of iodine in biological matrices,

which will provide reliable results for iodine at the yg/g level and

below. A highly selective separation for bismuth from photon-activated

nickel alloys makes the determination of this element feasible at the

ng/g level and below.

The group is substantially supporting major NBS programs with

research and analysts. Specific efforts have been made in sampling and

sample preparation methodology in order to provide meaningful analytical

samples in connection with the National Environmental Specimen Bank

(NESB). The extended instrumental capabilities help the Activation

Analysis Group to provide the large quantity of reliable analytical data

which, combined with the results of other analytical techniques, provide

essential information on environmental and biological systems. This

information is needed, for example, in the Chesapeake Bay Program and in

the pilot NESB Program. Sampling and analysis techniques have been

developed for the dependable measurement of key elements in both homogeneous and non-homogeneous oils in support of the ongoing Recycled Oil

Program. Studies in support of the development of low-enriched uranium

oxide, for use as SRM's for non-destructive analysis are being made to

identify all possible interferences to the nuclide of interest.

52
The group parttctpated in the certification of new biological

metals, minerals, and environmental SRM's. Analytical problems solved

by the group for other programs included the determination of chlorine

in CdS-samples using epithermal reactor neutrons for activation. Selenium was determined in extremely small samples of mitochondria in

collaboration with researchers at the NIH. The current state of high

precision measurements enables the group to carry out determinations of

activation cross sections (e.g. ^^Co to ^°'^Co and ^°^Co to ^^Co) and to

contribute to the accuracy of physical constants.

Immediate future goals are the improvement of the instrumental analysis capabilities by advanced counting methodologies including coincidence

and anti-coincidence spectrometry and the development of a precise monostandard technique. New radiochemical methodology will provide results on ultratrace elements and, in collaboration with separation chemists, the

quantitative determination of organic species will be investigated.

Efforts will be directed to the determination of the location of traces

within a matrix.

Rolf L. Zeisler, Group Leader; B. Stephen Carpenter,

Kathleen A. Fitzpatrick, Ronald F. Fleming, Thomas E. Gills,

Robert R. Greenberg, Sally H. Harrison, James Koskoris,

Richard M. Lindstrom, George J. Lutz, M. James Blackman

2 . El ectroanalytical Chemistry Group: Overview

The El ectroanalytical Chemistry Group's expertise focuses on, but

is not limited to, the utilization of electrochemical principles for

chemical analysis. The techniques employed include voltammetry, coulometry, ion-chromatography, amperometry, potentiometry , and conductimetry

.

A major effort of this group is concerned with the development and

certification of Standard Reference Materials. This activity is of

three types: research, acceptance testing, and analysis for certification. Two research projects were undertaken this year. One involved a development of an improved method for gravimetric determination of

aluminum in bauxite. The other was the development of a method for the

determination of trace amounts of iodide in biological and botanical

matrices by differential pulse polarography. Three materials (benzoic

acid, tris(hydroxymethyl )ami nomethane, and potassium dichromate) were

assayed coul ometrical ly, prior to their acquisition in bulk, for use as renewal Standard Reference Materials. Two of the three materials were acceptable and will be certified next year. Trace metals were determined

for certification of estuarine sediment, bovine liver, citrus leaves,

line pipe steel, and alloy steels by voltammetry. Ion-chromatography was used to certify the sulfur content in several oils, and the chlorine and

sulfur content in citrus leaves and bovine liver.

A significant effort was expended in the improvement Cpcu^ticularly

in extending the range) of the sodium alcoholate ion-chromatographic

method for the determination of chlorine and bromine in recycled oils.

53
As part of the National Environmental Specimen Bank Program, human liver

samples were analyzed for trace metals by cathode ray polarography . A

set of four oils, ranging in sulfur content from 0.5 percent to 4 percent, were analyzed by ion-chromatography as part of a cooperative program

between the National Bureau of Metrology in France and the Office of

Standard Reference Materials.

A multi-year project concerned with acid rainfall has been initiated.

The scope of this project is to investigate and identify the problems and

present limitations in the measurement of acidity and pH in rainwater.

Based on the findings, research will be conducted to develop stable acid

rain reference materials and to develop protocols for pH, acidity, and

conductivity measurements in low ionic strength, unbuffered solutions.

This will require the strengthening of the group's competences in pH,

potentiometry , and conductimetry

.

During the past year, a programmable computing integrator was added

to the ion-chromatograph which greatly expands its usefulness as an analytical tool. It is hoped that similar data acquisition and data

management devices can be acquired for voltammetry, coulometry, and

potentiometry to improve measurement capabilities and to handle routine

mathematical operations.

In the coming year, in addition to an anticipated intense sampleanalysis effort, the El ectroanalytical Chemistry Group will engage in

research to develop a species-selective and sensitive anion detector for

ion-chromatography based on amperometric principles. Investigations will

be conducted as to the sources of and remedy for possible systematic

errors in high-precision coulometric measurements which may adversely

affect the accuracy of the method. Continuing into the next year is a project concerned with the determination of aluminum and other metals at

trace and ultra-trace levels in serums and injectibles.

William F. Koch, Group Leader; E. June Maienthal, George Marinenko,

Jeffrey W. Stolz, Pan Xiurong,

3. Analytical Mass Spectrometry Group: Overview

The primary objectives of the Analytical Mass Spectrometry Group are the development and maintainence of a capability for high accuracy

isotope ratio measurements. The increasing need for such high quality

analytical measurements on sub-microgram amounts of material has required

continual improvement in chemical separation and purification techniques

and instrumentation. To accomplish these tasks, the mass spectrometry

group is composed of essentially two sub-groups. The chemistry sub-group

is responsible for all of the chemical aspects of the group's work.

Expertise in separation technology, isotope equilibration, sample dissolution, purification, and "contamination-free" sample handling are primary

concerns in this area. The other sub-group specializes in inorganic mass spectrometry . This sub-group has considerable expertise in high accuracy

mass spectrometric isotope ratio measurements and is responsible for

54
developing improved methodology and instrumentation for spark source,

electron impact, thermal ionization, and surface ionization mass spectrometry.

A significant effort has been expended in the areas of improved

analytical measurements and basic methodology. Major accomplishments in

analytical measurements include nuclear standards, atomic weights, and

methodology needed for environmental and health related problems. A

spike solution (SRM 995) has been certified for assay and isotopic

composition by comparison to a uranium metal standard (SRM 960) and a spike solution (SRM 993). The intercomparison of the three uranium

SRM's showed internal consistency of better than 0.1 percent. Analytical

work has been completed for the determination of the isotopic composition

and assay of a ^‘+^Pu SRM. These results, together with those from

Los Alamos Scientific Laboratory, will be used in the certification of

this new material . Concurrent research on the analysis of nanogram quantities of U and Pu loaded on single ion exchange resin beads has produced

precisions of better than 0.1 percent for isotope ratio measurements.

Research and measurements for a redetermination of the absolute

isotopic abundance and atomic weight of silver have been completed. Preliminary statistical evaluation of the data indicates a total uncertainty

for the atomic weight of less than 1 ppm, a factor of 100 improvement

over the currently accepted value. A more accurate value for the atomic

weight of silver is needed because of a recent high accuracy redetermination of the electrochemical equivalent of silver. The uncertainty in the

atomic weight of silver thus became the largest component of uncertainty

in the value of the Faraday constant.

Sulfur concentrations have been certified in 12 iron base SRM's by

isotope dilution-spark source mass spectrometry using a sealed tube

dissolution and equilibration method. Sulfur blanks have been reduced

to less than 1 yg so it is now possible to analyze samples containing

less than 10 ppm sulfur.

In a joint program with the Department of Nutrition and Food

Science, Massachusetts Institute of Technology, a study was undertaken

to determine whether or not oral administration of the stable isotope

^^Zn, at physiological ly relevant concentrations, would allow the

measurement of zinc enrichment with sufficient accuracy to investigate

zinc metabolic kinetics in human plasma. Measurements on blood samples

at MIT by neutron activation analysis and at NBS by mass spectrometry

show this approach to studying metabolic processes to be feasible.

Major accomplishments in the area of improved methodology include

development of mass spectrometric procedures for the analysis of elements

not previously measured by this group, and improvements in instrumentation

to increase precision as well as analytical output. Techniques have been

developed for the isotopic analysis of microgram quantities of vanadium

and iodine with precisions approaching 0.1 percent. A solid state filament control (which controls the current supplied to the mass spectrometer

sample filaments with a stability of better than 0.01 percent) has been

55
developed and tested. This unit has considerably improved the intraanalysis precision.

Future plans call for detailed studies of the mechanisms involved

during the sample mounting and vaporization/ionization processes to allow

better control of existing mass spectrometric procedures and to aid in

the development of new procedures. This will include studies, by surface

techniques, of the chemical and crystallographic species formed on the

filament, and identification of the positive, negative, and neutral species

formed during the ionization process. The successful analysis of iodine

by negative ionization techniques will be followed by efforts to develop

mass spectrometric procedures for other elements which are potentially

ionizable as negative ions.

The use of lasers as an alternative ionization mode for spark source

mass spectrometry will be investigated. The peak power available from

lasers has become high enough for the laser driven plasma to be an efficient means of ionization. The energy that is available in these plasmas

far exceeds that which is required to ionize all elements. This should

result in both high absolute sensitivities and smaller differences in

sensitivity between elements.

Future efforts in instrumentation are aimed at the development of

fully automated mass spectrometers with accuracies and precisions equal

to or better than can be obtained by manual operation. The general

approach is a systematic upgrading of the major electronic sub-assemblies

associated with the mass spectrometer. This will require research in

specific areas to develop prototypes which can eventually be assembled

as a fully automated instrument. Instrumental improvements scheduled

for the near future include replacement of existing optical pyrometers

used for setting filament temperatures with an infrared detection system,

which under computer control will automatically reproduce and maintain

constant filament temperatures, and more extensive automation of magnetic

field selection, baseline measurements, and ion beam focusing.

We also plan to automate some of our liquid ion-exchange chromatographic procedures to permit a greater sample throughput and, possibly,

more efficient separations.

Thomas 0. Murphy, Group Leader; I. Lynus Barnes, Ellyn S. Beary,

William A. Bowman, Karen A. Brletic, Lura P. Dunstan, John D. Fassett,

John W. Gramlich, Billy R. Hardas, Emerson F. Heald, William R. Kelly,

Howard M. Kingston, George M. Lambert, Lawrence A. Machlan,

John R. Moody, Paul J. Paulsen, P. Andrew Sleeth

56
4. Atomic and Molecular Spectrometry Group: Overview

The goals of the Group continue to be closely associated with the ever increasing demands for more accurate, more sensitive, and more

rapid spectrometric analyses. Currently, a multifaceted approach is

being used which includes the development of improved plasma emission

and atomic absorption instrumentation, investigation of controlled

spectrochemical excitation, development of novel sample preparation and

dissolution techniques, and the issuance of more useful spectrophotometric transmittance standards.

The Group's research efforts in atomic spectrometry have focused

primarily on the continued development and improvement in the analytical

capabilities of the inductively coupled plasma (ICP) spectrometer and on the evaluation of a newly acquired direct current plasma (DCP)/echel le

spectrometer. Application of the ICP to the analysis of selected Standard Reference Materials has demonstrated that a variety of chemical and

physical matrix interferences must be better understood and controlled

before this technique can provide data sufficiently accurate for certification use. Studies with the DCP instrument have indicated that detection

limits are comparable to the ICP and, through use of a lithium buffer

solution, matrix interferences can be reduced to acceptable levels.

In molecular spectrometry, research efforts have been directed

towards identifying those factors responsible for the apparent inhomogeneity observed with a significant number of the metal -on-quartz

transmittance filter standards. The apparent inhomogeneity observed of

approximately half of the chromium-on-quartz filters commercially produced

for NBS is a problem that continues to severely hinder the widespread

issuance of these filters as SRM's. For selected filters, transmittance

differences as large as two percent have been observed when these filters

are displaced laterally, £ 1 mm with respect to the incident radiation.

The recent transfer of the fabrication of these filters from an outside

laboratory to the NBS Optical Shop should facilitate a more systematic

study of the problem since optical measurements can be made at key

stages in the fabrication process.

Paralleling these research efforts have been the demands associated

with an intensive sample analysis work load. Areas in which the Group

has been a principal contributor include Standard Reference Materials,

hazardous waste characterization, Chesapeake Bay survey, used and

recycled oil analysis, ppb analyses of injectables for the Food and Drug

Administration, NBS-EPA National Environmental Specimen Bank, and service

analyses.

Important accomplishments of the Group during the past year include:

(1) design and construction of an improved extractor for the characterization of potentially hazardous wastes; (2) further refinement in the

definitive method for sulfur in iron-base alloys; (3) development of an improved atomic absorption method for lead in blood; (4) performance of

metal homogeneity measurements, using emission spectroscopy, with a relative standard deviation of 0.2 percent; (5) development of a graphite

57
furnace technique for arsenic and selenium that Is much superior to

hydride generation; and development of an ultratrace method for

silicon utilizing the reaction with methane in conjunction with Zeeman

atomic absorption spectrometry.

Future plans Include the placing of a greater emphasis on understanding and controlling the fundamental excitation processes occurring

In atom-producing sources, the systematic Investigation of electrothermal Ionization technique's for the direct analysis of solids, and

further refinements In the multielement capabilities of the ICP, DCP,

and continuum source wavelength modulated atomic absorption instrument.

In addition, a major effort will be Initiated within the Group in 1981

for performing metal speclatlon measurements by coupling high performance

liquid chromatography with a variety of metal-specific spectrometric

detectors

.

Robert W. Burke, Group Leader; John R. Baldwin, Carol G. Blundell,

David E. Brown, Therese A. Butler, Erie R. Deardorff, Barry I. Diamondstone,

Michael S. Epstein, Shigeki Hanamura, Jerry D. Messman, Klaus D. Mielenz,

John A. Norris, Theodore C. Rains, Theresa A. Rush, Robert L. Watters,

Glenn J. All In, Radu Mavrodineanu

58
B. Selected Technical Accomplishments

(Inorganic Analytical Research Division)

1 . D.C. Plasma Emission Spectrometry

The development of plasma sources for atomic emission spectrochemical

analysis has revived interest in the technique as a rapid, precise, and

sensitive method of sequential or simultaneous multielement determinations.

While most analytical interest has been directed towards inductivelycoupled plasmas (ICP), recent design advances in direct-current plasma

(DCP) technology have spurred development of that source.

The recent acquisition of a Spectraspan III D.C. PI asma/Echel 1

e

atomic emission spectrometer has not only significantly expanded our

analytical capability, but has also provided us with an opportunity to

study and improve the performance of the DCP. Two significant characteristics of a D.C. Plasma/Echelle spectrometer are its tolerance of a wide

variety of organic solvents and the excellent 0.005 nm) spectral

resolution. Recent investigations have taken full advantage of both

these characteristics.

The direct determination of silicon in lubricating oil is preferred

to oxidative digestion methods, primarily because time-consuming and

contamination-prone procedures are avoided. The direct atomic absorption

method involves introduction of an organic solvent containing the oil

into a nitrous oxide/acetylene flame, a rather hazardous procedure. For

this reason, DCP methodology was evaluated for the direct determination

of silicon in a Wear-Metal s-in-Oil Standard Reference Material. Three

proposed solvent systems for dissolution of the oil were investigated:

xylene, kerosene, and methyl -isobutyl ketone (MIBK) . MIBK was discarded

because of its rapid attack on the peristaltic pump tubing. Xylene was satisfactory in that it dissolved both the oil and the organometal 1 ic

Standard Reference Material (1066a--0ctaphenylcyclotetrasiloxane) but it

produced a significantly greater spectral continuum in the plasma than

kerosene, in which the SRM 1066a was insoluble. A solvent system of 95/5

kerosene/xylene was finally chosen (with dissolution of the SRM 1066a

in pure xylene and subsequent dilution with kerosene) and standards were

matrix-matched to the dissolved oils using Conostan 245 basestock oil.

The matrix-matching was required to avoid mixing chamber equilibration

problems. The limit of detection was 40 ng/mL silicon and analytical

results were within two percent of the certified value of the SRM WearMetal s-in-Oil with a relative standard deviation varying from one to

two percent.

The analysis of refractory elements in high alloy steel by emission

spectrometry is fraught with difficulties. High temperature plasma

techniques produce a combination of intense continuum and complex line

spectral radiation from sample concomitants. This spurious radiation

severely tests the background correction capability and resolution of

the spectroscopic instrumentation required to obtain accurate analytical

results. Figure 10 illustrates the importance of the resolution and background correction of the DCP/Echelle spectrometer for the determination

59
EMISSION

INTENSITY

WAVELENGTH

Figure 10. Spectral wavelength scans of approximately 1 yg/mL zirconium

in a matrix of one percent high alloy steel. While both

zirconium analytical lines illustrated in (A) and (B) are useful, greater precision and accuracy are obtained using (B)

because of the lower continuum radiation intensity.

60
of zirconium in high alloy steel. Correlation of results from two analyte

lines, such as the 360.12 nm and 468.78 nm zirconium lines, provides a good assurance that accurate results have been obtained from the background

correction procedures employed.

A program is presently underway to establish benchmarks (i.e., detection limits, precision, linear dynamic range, and accuracy) against which

future system improvements can be measured. Some proposed modifications

include: (a) improved pneumatic and ultrasonic nebulization for increased

sensitivity and reduced chemical interference; (b) direct coupling to a liquid chromatograph for speciation studies; (c) application of gas generation procedures for sample introduction to improve sensitivity for elements

such as boron, phosphorus, lead, arsenic, selenium, and other hydride

forming species; Cd) investigation of the use of the DCP as a radiation

source for atomic fluorescence spectrometry; and (e) determination of the

usefulness of the DCP as a source for vacuum UV emission spectrometry.

M. S. Epstein

2 . The Halogen Content of Lubricating Oils

With the escalating emphasis on energy-efficiency, fuel saving and

recovery, and material durability and reutilization, the halogen content

of oils is of mounting importance and concern. It is vital to know that

recycled oils burned in heating and power plants do not contain excessive

amounts of halogen in order to limit acidic emissions; that re-refined

lubricating oils have not been contaminated with halogen-containing

cutting oils which could cause undue engine wear. Present analytical

methods adopted by the American Society for Testing and Materials, the

American National Standards Institute, and the Institute of Petroleum do

not adequately address the problem at the levels of concern, being

deficient in trace level capability, and in ability to distinguish

chloride from bromide. Activation analysis, of course, can meet the

demand and is being used extensively at NBS for this purpose, but this

technique is costly and not readily available to commercial laboratories. The need for other methods is obvious.

With this end in mind, a new method has been developed capable of

detecting chloride and bromide in oils at levels below 10 ppm. The

method is based on a sodium alcoholate digestion, wherein halogen is

liberated from its organically-bound state by a substitution reaction,

an extraction of the free halide into water, and detection and quantitation by ion-chromatography. The digestion step is a variation of an ASTM procedure (01317), but much less sample is required in the improved

procedure. A serious emulsion problem can arise in the extraction step

with some oils; it can be remedied with the aid of demulsifiers. The

aqueous phase of the extract is treated with cation-exchange resin before

injection into the ion-chromatograph to neutralize the base formed in the

digestion step. Chromatographic conditions have been selected to optimize

resolution of and sensitivity for chloride and bromide. A standard

additions sequence is recommended to compensate for matrix effects on peak

shape and retention time. Psesults, representative of the method's

61
capability, are tabulated below. The present limitations in this new method are due primarily to the purity of the sodium metal used in the

digestion step. The purest commercially available sodium contains

10-20 yg/g chlorine.

Whereas this new method cannot compete with activation analysis in

terms of minimum detection limits (or precision at the lower levels), it

should prove to be a valuable analytical tool for the rapid screening of

oils for halogen content and for the quantitative determination of

chloride and bromide in oils at levels above 10 ppm.

Table 3. Chlorine and Bromine in Oils by Sodium Alcohol ate/

Ion Chromatographic Method.

Oil ppm Cl S.D. n^ ppm Br S.D. n

0033 225 34 4 <2

0026 13.5 3.7 5 4.2 2.8 4

0076 9.3 3.4 5 3.2 0.7 4

0050 8.3 2.0 4 <1

1634a 27.3 2.9 11 <1

W. F. Koch

3. Measurement of the Co-60 to Co- 59 Ratio in Microparticles

As part of the Bureau's health physics program, several metallic

particles were discovered that had very high specific activities of ®°Co;

Division members were asked to help analyze them. The question raised was whether or not this activity could have been produced in the NBS

reactor, and if so, how long ago. The measurement of the cobalt isotopic

ratio by neutron activation analysis can contribute to a simple and

effective means to identify the origin of the irradiated particle as well

as to establish the approximate time or irradiation. As a result of the

measurement described below, it was concluded that the particles were

indeed produced in the NBSR about six years ago.

For example, if a cobalt-bearing steel is subjected to neutron

irradiation and at a subsequent time the ratio of cobalt-60 to cobalt-59

atoms and the ratio of iron-55 to iron-54 atoms are measured, it is

possible to determine both the decay time since the end of irradiation

and the neutron fluence to which the particle was exposed. For this

purpose, we developed two methods for the determination of the cobalt

ratio and applied them to particles ranging in mass from 80 ng to 300 yg.

The measurements were carried out at the ORR reactor in Oak Ridge during

the period of the NBSR shutdown.

62
The first method is the approach of conventional neutron activation

analysis. The sample was irradiated along with a known mass of elemental

cobalt as a standard. The 58.6 KeV gamma emitted by the 10.47 minute

^®*^Co activity produced was counted using a thin Ge photon detector.

This gave the ^^Co mass. The number of ^®Co atoms was determined by

counting the particle against a ®*^Co standard source (SRM-4210). This

gave the specific activity of the particle as curies of ®®Co/gram ^^Co.

The direct measurement of the ^*^Co/^^Co ratio was also done by NAA.

For this, a know mass of cobalt was irradiated along with a ^*^Co source

of known activity. In addition to the ^^Co (n,y)^®"’Co gamma, we also

measured the activity of the 67.4 KeV gamma from the 99 minute ®^Co produced by ®*^Co (n,A)^^Co. This provided a calibration of the irradiation/

counting system since

Neo

N 59

where

A

= . e"" - “ /, -Atv/, -XAx X6

(1-e )(l-e )

Os 9 Ifipm cgom

o'go ^61 ^61

with X

cT

A

6

ti

o

T

e

decay constant

net counts in photopeak

irradiation time

live time of count

dead time of count

time from end of irradiation start of count

activation cross section

gamma per decay

detector efficiency

The measurement gave the calibration factor (in square brackets) as 0.229 (±10 percent) so that the specific activity is given as

Curies (^^Co)/grams(^^Co) = 264

Ato""

This second method has the important advantage that all geometry

effects during irradiation and counting are eliminated. This proved to

be crucial in the case of particle DlOA which was not visible and hence

difficult to position precisely. The results of the measurements for

six particles by the two methods are given below. The agreement is

excellent except for DlOA for which the direct method gives the more

reliable result.

63
Table 4

^*^00 Activity Ci ^°Co/gm

Particle Weight (yg) (y Ci) Direct Conventional

HEX 7-1

D1 OA

G2

D1RF

G1

300.3

66.2

28.0

15.7

134.3

0.083

12.8

9.30

8.97

5.58

257

2.59 335

1 .36

10.4

11 .6

0.91

1 .34

10.2

11 .6

19.6

282

B. S. Carpenter, R. F. Fleming, R. M. Lindstrom, R. Zeisler

4. Cryogenic Homogenization of Tissue

The major task of the National Environmental Specimen Bank (NESB)

Pilot Program includes the evaluation of specimen storage under different

conditions, and the analysis and re-analysis of the same specimen by

different techniques. To obtain the needed information, the individual

specimens have to be stored and analyzed in the form of small but

representative subsamples. Large inhomogeneities within a single liver

have been reported when typically one gram subsamples are used [1]. The

concentrations of essential trace elements vary by a factor of four and

up to a factor of 1000 for other trace elements. Therefore, the ability

to homogenize the tissue to produce representative subsamples is essential to the program.

The method of cryogenic homogenization [2], brittle fracture technique, has been adapted to the needs of the banking program and has been

evaluated for its performance and general applicability to the homogenization of fresh, soft biological material. A prototype brittle fracture with

up to 250 g capacity has been developed at NBS. This capacity is needed

to homogenize a half left lobe of a human liver, one of the kinds of

specimens stored in the NESB. The machine is essentially a Teflon ball

mill, in which samples are fractured and homogenized at liquid nitrogen

temperature without contamination.

The storage evaluation experiment of the NESB Pilot Program requires

that the inhomogeneity error due to the analytical subsample is less than

10 percent. To evaluate the homogeneity and the performance of the modified brittle fracture technique, the sampling constant and sampling

diagram models [3] have been applied. The models developed for particulate materials assume Poisson statistics to govern the relation between

sample size and sampling error. A sampling constant can be defined as

R or K

s 3 R^ w

64
where R is the relative error in percent and w is the sample weight.

Therefore, represents the sample weight, at which the sampling error

is one percent. For nearly particulate analytical materials, e.g. liver

homogenate, the sampling constant can be estimated by generating a sam- pling diagram and examination of its compliance with the above assumption.

A sampling diagram can be developed by analyzing a sufficient number of

subsamples of different weights. The analytical error necessarily has to

'be small, at least less than 1/3 of the sampling error.

Radiotracer studies can provide the required analytical information;

however, to minimize possible different behavior of spikes, a five_gram

subsample of a liver specimen was irradiated (2 min at 5 x lO^^ncm'^s ^).

The radioactive subsample was added to the remainder of the tissue and

then homogenized. Ten subsamples each were taken at a nominal weight of

100 mg, 1000 mg, and 6000 mg. Subsequently, the subsamples were counted

on a gamma spectrometer. Counting errors were minimized to the error due to counting statistics.

The radioactive ^^*Na was used to monitor the distribution of sodium

in the samples. The results are plotted in figure 11, showing a typical

sampling diagram. The sampling constant, K^, i.e., the subsample weight

where an inhomogeneity of one percent can be expected, was calculated to

be 35 g. This experiment confirms our ability to take a grossly inhomogeneous sample and produce a material from which representative subsamples

can be taken. With a typical analytical subsample of one gram used in

the NESB Program, a sampling error of five percent or less can be expected.

The upgrading of the brittle fracture technique and the measurable improvements of the homogeneity of the specimens will have impact on the trace

analysis in life sciences and environmental sciences. A large sample can now be homogenized without the danger of contamination by metals and fluids

used in other blending operations. In addition, the sample is kept at low

temperatures throughout the entire operation, thus largely preventing

chemical and biochemical changes.

65
Figure 11. Sampling diagram of ^*^Na in human liver homogeneate.

References

[1] Schicha, H., Kasperek, K., Riedel, V., Feinendegen, L. E.,

Vyska, K. , and Muller, W., Proc. Symp. Nuclear Activation

Techniques in the Life Sciences 1972, IAEA, Vienna, 451 , (1972).

[2] Iyengar, G. V. and Kasperek, K., J. Radioanal. Chem., 39, 301

(1977).

[3] Ingamells, C. 0., Geochim . Cosmochim . Acta , 38 , 1225 (1974).

S. H. Harrison, R. Zeisler

5. Rapid Analysis of Toxic Metals in Biological Tissue and Fluids by

Atomic Absorption Spectrometry

Current interest in the effect of trace quantities of toxic metals in

plants, animals, and human beings, coupled with widespread concern over

the possible accumulation of these toxic metals in the environment, has

created a need for the determination of ever lower concentrations of metals

in a wide variety of biological materials. Reliable methods do not exist

in many clinical or biological laboratories for the determination of physiological levels of many trace metals. The ideal clinical or biological

66
method should be relatively rapid, free from interferences, capable of

determining relatively low concentrations of the analyte in a minimum

volume of sample, and have a relatively high degree of precision and

accuracy. Unfortunately, Standard Reference Materials for trace metals

in biological fluids are not available and only two types of animal tissue

are available to evaluate analytical methods currently being used in these

laboratories.

In the area of blood-lead, a method was developed at NBS whereby

lead is stripped from 100 yL of whole blood into 5 percent nitric acid

medium and determined by AAS with electrothermal atomization. The method

is capable of determining 5-90 yg Pb/dL of whole blood with a precision

of ± 2 yg/dL. The time required for an analysis is 15 minutes. The method

developed at NBS is being widely used in clinical laboratories throughout

the U.S.A. and the world. The technique was recently adopted as the

standard method for blood-lead at the Mayo Clinic, Rochester, MN. The

analytical capability of the method is tremendous. Cadmium in whole blood

can be determined with a precision that is comparable with the blood-lead

analysis. This method meets the criteria for an ideal clinical method.

In the analysis of biological tissue and bio-injectibl e vaccines by

conventional AAS methods, cadmium and lead signals are severely suppressed. To alleviate this difficulty, a technique of matrix modification is

used. For lead analysis, a 0.01 percent K2 Cr 207 solution is added and

the sample is charred at 900 °C in the electrothermal atomizer prior to

atomization. The high charring temperature removes many of the interferences without loss of the lead. In cadmium analysis, the interferences

are alleviated by the addition of a 1 percent solution of ammonium

orthophosphate E(NH4 ) 2 HP 04 ] . In the presence of (NH 4 ) 2 HP04 , the sample

can be charred at a temperature of 800 °C without loss of cadmium. The

difficulty encountered with the use of (NH4 ) 2 HP04 is a high reagent

blank. To overcome this difficulty, the (NH4 ) 2 HP04 is pre-extracted

with a solution of ammonium pyrrolidine dithiocarbamate (APDC) and

methyl isobutyl ketone.

With an increased interest in the trace analysis of arsenic and

selenium in biological tissue and fluids, an evaluation of several

analytical techniques was undertaken. The vapor generation-AAS technique using an argon (entranced air)-hydrogen flame was found to produce

low and erratic results. The system was modified by using a heated

absorption cell with no resulting improvement in interferences. Electrothermal atomization was investigated using matrix modification by

adding 1000 yg Ni/mL. The addition of nickel permitted a charring

temperature of 800 °C. This method was found to alleviate the interferences

encountered in biological tissue and fluid. As a check of the recovery

of the method, the single standard addition technique was used.

Currently, AAS with electrothermal atomization is being used to

survey trace metals (A1 , As, Ba, Cd, Co, Cr, Hg, Pb, Se, T1 , and Zn) in

several types of injectable biological products. As a result of this

survey, a biological product will be selected as a candidate for a Standard Reference Material

.

C. G. Blundell, T. A. Butler, J. D. Messman, T. C. Rains, T. A. Rush

67
6. Comparative Measurements of Zinc-70 Enrichment in Human Plasma Using

Neutron Activation Analysis and Thermal Ionization Mass Spectrometry

A joint project between the Inorganic Analytical Research Division

and the Nuclear Reactor Laboratory, Department of Nutrition and Food

Science, Massachusetts Institute of Technology was undertaken to establish

whether analytical methodology is available that would allow accurate

measurement of ^°Zn enrichment in human plasma during zinc metabolism

studies. If successful, it would be possible to conduct human zinc

metabolism studies with small amounts of ^°Zn stable isotope instead of

either radioactive zinc or abnormal quantities of natural zinc. The two

methods chosen for this investigation were radiochemical neutron activation at MIT and thermal ionization mass spectrometry at NBS on samples

provided by MIT.

Plasma appearance curves for zinc following oral administration in

humans have been studied to a very limited extent using both radioactive

zinc isotopes and natural zinc. The former method is restricted in regard

to general use because of issues related to administration of radioisotopes, while the latter requires oral intakes of zinc significantly

greater than the normal daily intake of the mineral.

The stable isotope ^®Zn is natually present at 0.62 percent atomic

abundance, being the least abundant of all stable isotopes of zinc.

Therefore, it could potentially provide a suitable vehicle for studies

of dietary enrichment. It is of considerable interest and importance to

determine whether or not oral administration of "^^Zn at physiologically

relevant levels would allow the measurement of zinc enrichment in human

plasma to the extent that would permit the investigation of plasma

appearance kinetics for zinc.

Accurate measurements of "^^Zn enrichment under normal nutritional

conditions is difficult due to two primary factors. First, in a typical

human study involving time-dependent measurements, the amount of plasma

available at any given time is restricted to only a few milliliters.

This sample size provides a total "^^Zn content of only a few nanograms.

Secondly, the expected total plasma increase due to the administration

of the isotope is at most only a few percent of the oral dose.

Following an overnight fast, four healthy adult male volunteers con- sumed a single glass of orange juice containing 3.2 mg of ^°Zn. Venous

blood samples were withdrawn from the anticubital vein every fifteen

minutes for the first two hours, at half hour intervals for the next 1 1/2

hours and then hourly until eight hours after isotope ingestion. The

blood samples were analyzed by neutron activation analysis at MIT and by mass spectrometry at NBS.

Previously employed mass spectrometric procedures for zinc isotopic

analysis required approximately 10 micrograms of zinc per analysis.

Since these plasma samples contained only about 0.5 micrograms of zinc,

it was necessary to develop mass spectrometric techniques for the

analysis of submicrogram quantities. Modifications to the existing

68
procedure, principly lowering the zinc-to-silica-gel ratio on the

filament, achieved the goal of allowing ^®Zn/'^°Zn ratios to be measured

on 0.3 microgram samples with a precision for replicate analyses of a standard of 0.13 percent relative (1 std. dev.). The corresponding

precision found for activation analysis was 8.3 percent.

The results of this study indicate that in a typical metabolic study,

where a single 3 mg dose of ^°Zn is administered whose kinetic plasma

appearance is similar to the data obtained in this study, then at the peak

appearance the expected ^°Zn plasma enrichment should be about 200 percent

of the plasma ^°Zn baseline level (an increase in ^°Zn enrichment from

0.62 percent to 1.83 percent). Under these conditions, neutron activation

analysis should provide satisfactory results with its attainable precision

of 5-10 percent. If however, ^°Zn appearance is significantly lower than

these values, then the precision of neutron activation analysis becomes

marginal and a technique such as mass spectrometry will be required to

obtain meaningful results.

J. W. Gramlich, L. A. Machlan, M. Janghorbani

7. Trace and Toxic Elemental Study of the Chesapeake Bay

As part of a multidisciplinary study of the Chesapeake Bay, the

National Bureau of Standards (NBS) was asked to develop the techniques

and procedures necessary to measure the trace and toxic element concentrations within the water column throughout the entire length of the Bay.

As part of this program, NBS collected 102 separate water samples and is

currently completing the analysis for selected elements (Cd, Ce, Co, Cr,

Cu, Fe, Mn, Mo, Ni , Pb, Sc, Sn, Th, and Zn), including some elements at concentrations consistently below one picogram per milliliter

(part per trillion). The collection of the samples was described in the

1979 Technical Activities, however, the list of elements to be analyzed

was upgraded this year to its present complement with the addition of

Ce, Sc, Th, and U.

The literature on marine water analysis reflects the considerable

difficulty in establishing an accurate and precise method of analysis

for trace metals. An estuarine or sea water matrix defies a simplified

approach. The extremely low trace concentrations cause the sample and

analytical blank to be of paramount importance. The integrity of the

sample can be compromised by just a brief exposure to normal laboratory

air. In addition, the extremely high concentrations of alkali, alkaline

earth, and halogen elements in the marine water matrix make direct

analysis difficult or impossible for most analytical techniques.

To circumvent these problems, special chemical and instrumental procedures were developed. While the chemical separation, preconcentration

was completed in late 1979, it was optimized this past year for neutron

activation analysis (NAA). The basic chemical procedure was developed

and published in 1978 and 1979 [1,2]. The chemical procedure was substantially unchanged as reported for use with thermal device atomic

69
absorption (TDAA). However, the elements were not eluted from the resin

when used in conjunction with NAA. Both the modification and the

established procedure proved to be extremely advantageous when applied

to estuarine or seawater analysis.

The elimination of matrix elements allows the determination of many

elements which could not otherwise be analyzed and enhances the sensitivity

of other elements of interest. The control of the blank in this procedure

has enabled its contribution to be sufficiently low that it does not limit

the measurement of pristine samples. The particulate fraction of each

sample was prepared in the field by splitting a two-liter sample into two

one-liter filter samples, one for TDAA and a second for NAA to eliminate

handling and dividing a single particulate sample.

Both the samples and the blanks have undergone rigorous statistical

scrutiny and are being reported after correction for blank contribution

(where necessary) at the 95 percent confidence limit.

It was necessary to extend the capabilities of the chemical and

instrumental techniques to obtain state-of-the-art concentration data for

the samples. All of the elements of interest cannot be analyzed by a single instrumental technique. The methods necessary to analyze the

estuarine and seawater using NAA have been developed this past year. The

combined use of NAA and TDAA provides the capability to determine a wide

range of important trace elements in estuarine samples. It was found that

by drying the resin in the column after chemical separation and analyzing

it directly in heat sealed polyethylene film that NAA could simultaneously

analyze many elements at the ultratrace level with a high degree of

accuracy. This detailed technique will be published in the open literature

in the near future.

These concentration measurements will be used as the basis for several

studies. Because the samples were taken concurrently with sediment, pore

water, and benthic studies, both the water- to-sediment equilibrium and

aquatic population will be correlated. Beyond this, a "state-of-the-Bay"

is being established which includes an estimate of the impact of the

population area impinging on it. The ultimate goal of the program is to

produce an informative study to guide the management of the Bay. To meet

these demands, it is necessary to compare the results respective of their

location throughout the Bay. The interpretation of the concentration data

obtained at the different locations throughout the Bay is extremely

difficult. At a single location the concentration can vary with time,

tide, current, wind conditions, temperature, bi^+‘', etc. With these

perturbations of concentration at a single Ic on, interpretation of the

differences found at separate locations is formidable. One approach which

has proven useful in minimizing fluctuations is the comparison of elemental

ratios rather than absolute concentrations. For this technique to be

successful, however, the elemental concentration must be determined with

a high degree of accuracy. Reference elements must be chosen which are ubiquitous and essentially nonanthropogenic. An increase in the total mass loading will increase the absolute concentrations, but will not affect the

elemental ratios. A significant addition of a single element or several

70
elements to the environment from either natural or anthropogenic sources

will increase the ratios of this (these) element(s) with respect to the

reference element. Increases in concentration, however, may not be

obvious over the normal fluctuations of the absolute elemental concentrations. This technique has been applied to the elemental concentrations in

the estuarine samples with dramatic results. The elemental concentrations

in the particulate fractions were found to vary over two orders of

magnitude between locations as indicated in Table 5. The ratios for Fe,

Th, and Ce are essentially constant, differing by only 20 percent, while

the Co to Sc ratio is four times greater in sample 11,032 than in either

1 1 ,005 or 11 ,007.

Table 5. Concentration in Particulate Phase and Ratios to Scandium.

Sample Number

11,005 11 ,007 11 ,032

El ement Concentration--nq/mL

Fe 2,800 ±100 128 ±8 18 ± 1

Co 1.02 ± 0.05 0.050 ± 0.003 0.028 ± 0.003

Sc 0.90 ± 0.005 0.040 ± 0.002 0.0049 ± 0.0002

Th 0.66 ± 0.03 0.032 ± 0.002 0.0038 ± 0.0005

Ce 6.0 ± 0.3 0.26 ± 0.01 0.039 ± 0.003

Ratio to Scandium, [X]/[Sc]

Fe 3.2 X 1Q3 3.2 X 10^ 3.7 X 103

Co 1.1 1 .3 5.7

Sc E 1 E 1 E 1

Th .73 .80 .78

Ce 6.7 6.5 8.0

This technique provides a means for identifying the similarities and

differences between the sample locations. A comparison of ratios through

out the Bay may be useful in identifying anthropogenic and/or naturally

occurring sources to the Chesapeake Bay. If the concentrations of toxic

elements are found to be excessively high, it is necessary to identify

their sources before any attempt can be undertaken to reduce these levels.

71
References

[1] Kingston, H. M., Barnes, I. L., Brady, T. J., Rains, T. C., and

Champ, M. A., "Separation of Eight Transition Elements from Alkali

and Alkaline Earth Elements in Estuarine and Seawater with Atomic

Absorption Spectrometry, " Anal . Chem . , 50 , 2064 (1978).

[2] Kingston, H. M., "Quantitative Ultratrace Transition Metal

Analysis of High Salinity Waters Utilizing Chelating Resin

Separation," Interagency Energy/ Environmental R&D Program

Report, p. 72, EPA-600/7-79.-174. 1979.

E. S. Beary, R. R. Greenberg, H. M. Kingston, T. C. Rains

8 . Characterization of Potentially Hazardous Wastes—Development of

Rotary Extractor and Quality Assurance Standards

With the passage of the Resource Conservation and Recovery Act in

1976, Congress mandated that EPA establish a set of regulations by April

1978 regarding the identification, transportation, and disposal of

hazardous waste materials. EPA subsequently defined eight characteristics

for waste materials, any one of which would classify a waste material as hazardous. One of these characteristics, EP toxicity, EPA has chosen to

relate to the amounts of certain priority inorganic and organic pollutants

which are leached from the wastes under a set of empirical extraction

conditions

.

Late in FY 79, NBS entered into an interagency agreement with EPA

to evaluate the several extraction procedures that were being considered

as acceptable tests for the identification of hazardous wastes.

In order for NBS to fulfill its obligation to EPA, it was necessary

to develop a procedure which would reproducibly extract the leachable

priority pollutants from the waste material. Although a number of

extraction techniques are presently in use, the results of various

interlaboratory studies indicate that variations in concentrations of

orders of magnitude for the priority pollutants are not uncommon. Although this can be a result of poor analytical technique and/or sample

inhomogeneity, the possibility of poor extractor designs must also be

considered. In fact, data presented at a number of ASTM meetings in

which several members of NBS staff participated, clearly indicated that

the reproducibility of the extraction procedures was extremely poor.

Thus, in order for meaningful measurements to be made on an interlaboratory basis, an improved extractor design was of paramount importance.

Based on our interpretation of the EPA Federal Guidelines, a model

extractor was designed which allowed four samples to be run simultaneously

in 2-liter containers. The sample containers were tumbled end-over-end

at 29 rpm permitting intimate contact between the waste and the extracting

solution. Although extensive testing of this rotary extractor at NBS is

72
incomplete, EPA has chosen to include this design as an acceptable model

in the latest Federal guidelines. Presently, studies are In progress to

evaluate the efficiency and abrasion characteristics of this design on selected wastes. An Illustration of this rotating extractor Is shown In

figure IP.

At the moment, NBS Is In tEie process of providing to ERA a number

of units of representative waste material which will be a fly ash that

Is totally characterized for chemical composition using NBS standards.

Information will also be provided on the concentrations of the priority

pollutants which can be leached from the material under specific extraction conditions. In addition, NBS Is Initiating studies on some sludge materials to be used as more complex quality assurance standards.

Work in this area Is expected to continue in FY 81.

As a parallel effort, NBS has provided the Department of Energy

Laramie Energy Technology Center tDOE-LETC) with a set of quality

assurance standards for the area of fossil fuel wastes. This effort has

required the collection of ton-quantities of coal, coal fly ash, and coal

bottom ash which were sieved, ground, blended, bottled, and delivered to

DOE-LETC. As in the case of the EPA material, these samples were fully

characterized for chemical composition of both the solid and the extract.

Additionally, as part of the quality assurance program, two levels of

synthetic leachate solution were prepared, each fully characterized for

18 inorganics. Work is expected to continue In these areas through

FY 81

.

R. W. Burke, B. I. Diamondstone

73
Figure

12.

NBS-designed

fork-unit

rotary

extractor.
9 . Development of an Improved Gravimetric Method for the Determination

of Aluminum in Bauxite

Increasing numbers of reports of difficulties of many analysts in

the determination of aluminum in bauxite and bauxite SRMs have led to an investigation that would result in a reference method for this analysis.

This is a very important problem, because bauxite ore is the primary

source for the production of aluminum.

There are several different types of bauxite, only one of which,

Arkansas, is domestic to this country. The production of aluminum is

tailored to the particular compositions of bauxite used in order to

achieve the desired end product. Since the U.S. is not self-sufficient,

we usually import Dominican, Jamaican, and Surinam bauxites for blends

refined in this country. Bauxite SRMs and accurate definitive methods

of analysis applicable to any of the different types are of prime importance in trade equity in the world market place and for process control

in the manufacture of aluminum and aluminum-base alloys. Not only is the

accurate knowledge of the aluminum content of the ore important for the

methodology of production control and quality assurance program for

efficient plant operation with attendant energy savings, but also,

original ore content must be determinable within certain narrow fixed

limits to satisfy the buyer-seller needs. Bauxite SRM's have been

issued by NBS for at least 50 years to provide industry with a means of

calibrating their methods.

Aluminum determinations in bauxite at the high concentrations present

percent AI 2 O 3 ) have always presented difficulties because of the

necessity to make quantitative separations. The task of repeated filtrations, the handling of the voluminous, gelatinous precipitates, boiling

large volumes of solutions, without losses or contamination is laborous,

onerous, and difficult even for experienced wet analytical chemists.

The chief sources of error for aluminum determinations in bauxitetype materials by the classical analytical ammonium hydroxide-cupferron

precipitation includes: failure to completely decompose the material;

failure to fuse the residue remaining after HF-H2SO4 treatment to remove

silica; failure to correct for compounds normally precipitated with

ammonia; failure to correct for materials that are co-precipitated with

the aluminum hydroxide; precipitation of the alkaline earths as carbonates; failure to remove alkali salts which are carried down with the

aluminum hydroxide precipitate; incomplete re-dissolution of the hydroxide

precipitate prior to the second reprecipitation; improper ignition of the

hydroxide precipitate; failure to protect the ignited alumina from

moisture before or during weighing; failure to correct for silica

carried down by the hydroxide; and misleading blank corrections.

The Hoffman-Killebrand ammonium-hydroxide-cupferron method is long

and tedious, but attempts at short cuts have led to erroneous results.

Some of the other separation techniques have been tried, such as ion

exchange which failed as a result of overloaded columns.

75
The investigation here involved some modifications of the HoffmanHillebrand method to eliminate some of the sources of error and include:

slightly higher drying temperatures of the ore; additional fusions to

get al 1 of the residue in solution; electrolysis of the sample solutions

with a mercury cathode; a single cupferron precipitation followed by a cupferron-CHCl 3 extraction of the solution of the first precipitate; a triple rather than a double ammonium hydroxide precipitation; ignition

in covered, platinum crucibles at 1200 ®C (this is done in the HoffmanHillebrand method but has been omitted by many recent analysts); evaporation of the residues to dryness with HF and H 2 SO4 to remove traces of

silica; reignition at 1200 ° to constant weight; examination of the alumina

residues for contaminants by emission spectroscopy and subtracting the

amount found from the alumina residue.

DTA studies of the bauxite SRM 69a indicated that samples should be

dried at 170 °C to constant weight instead of at 140 °C as previously

recommended. It was also observed that often two separate fusions

with sodium carbonate and sodium pyrosulfate after filterings and ignitions were necessary to completely dissolve the residue. At additional

steps in the procedure, a residue was sometimes observed, necessitating

an additional filtration, ignition, and fusion. The mercury cathode

electrolysis step was added to remove materials which are removed incompletely or not at all by the cupferron separation. These elements are:

chromium; manganese, in part; zinc; silver; cadmium; indium; thallium;

lead, in part; bismuth; platinum metals, in part; etc. It also removes

the bulk of the iron, making the cupferron separation easier to handle.

An extraction was substituted for the second cupferron precipitation to

minimize the contamination from the slight solubility of the cupferrates.

These cupferrates can be extracted more quantitatively than they can be

precipitated. An extraction is not recommended for the first cupferron

separation, because such a large amount of aluminum is present at that

step, its mechanical loss in the process would be possible owing to

pressure build-up in the extraction funnel. The triple ammonium hydroxide

precipitation minimizes the contamination resulting from hydroxide

co-precipitation, precipitation of alkaline earth carbonates, and the

alkali salts carried down with the hydroxide. No problems with hygroscopicity were experienced when the crucibles were ignited, covered at

1200 °C. In the Hoffman-Hil 1 ebrand method, each alumina residue was analyzed individually and corrected for Si 02 , Fe203 , Ti 02 , Zr02 , P2 O 5 * Cr203 , and V2 O 5

. With much less effort, emission spectroscopy can determine these constituents (with the exception of phosphorus) as well

as barium, cobalt, magnesium, manganese, sodium, potassium, vanadium,

tungsten, zinc, and zirconium, etc. A result of 55.03 percent was obtained for SRM 69 which was carried along as a control. This value

should be compared with the average value of 55.00 percent obtained by

J. I. Hoffman by three separate methods and its certified value of

55.06 percent and is consistent with the confidence limits for each of

these.

E. J. Maienthal

76
10. Fission Track Monitor

One of the activities completed within the Division during the last

fiscal year was the field testing and evaluation of a fission track

reactor power monitor for the International Atomic Energy Agency (IAEA).

The purpose of this task was to evaluate the capability of the tracketch monitor for providing an independent record of the nuclear reactor's

power history and to provide information concerning the neutron energy

spectrum.

The track-etch monitor evaluated was an externally-powered device

designed to record the neutron flux from operating reactors and similar

sources for extended periods of time. A strip of 35 mm wide polymer tape

is drawn past a group of fissionable deposits which have been exposed to

the local neutron flux. A fraction of the fission fragments generated

penetrate the tape producing radiation-damaged tracks that are subsequently

etched and counted to permit a reconstruction of the temporal flux history

to which the monitor was exposed. Each monitor is equipped with sufficient

tape to cover a year of reactor operation time. The monitor is designed

to operate at a neutron flux of 106 ncm~2s~i

.

In one of the actual field tests, a monitor was installed above the

shroud at the Maine Yankee Power Reactor in Wiscassett, Maine, for ten

months. During this period of time, the 855 Megawatt reactor underwent

four unscheduled shut-downs and over eight changes in reactor powerlevels. The 14.5 meter tape was removed from the monitor, chemically

etched to reveal the fission tracks, which were measured. The investigation of the tape indicated that the monitor was able to record the changes

in reactor power but had suffered several mechanical malfunctions, and

furthermore was location-dependent for optimum neutron flux measurement.

A second monitor was placed in the Wisconsin Public Service Corporation's

Kewaunee Nuclear Power Plant for a shorter period of time and similar

information was obtained.

The final conclusion reported to the IAEA, was that the monitor would

technically perform the functions that were required of it; however, it

would not be completely reliable due to frequent mechanical failure. The

IAEA was also advised that the only means to achieve the unattended

monitoring of power reactors was to completely redesign the motor-gear

train assembly of the monitor.

B. S. Carpenter

1 1 . Interferences in the Inductively Coupled Plasma (ICP) Technique

In the application of the ICP technique to high-accuracy analysis of

Standard Reference Materials (SRM's), interferences have been found which

can degrade the quality of analytical results. These interferences can

be traced to spectral and matrix-related interactions which must be

characterized and corrected for in order to minimize their effect. The

problem of spectral interference in the ICP technique is well known.

77
Procedures for background and spectral overlap corrections have been

established and are presently being employed in this laboratory. The

first step is to expose a photographic plate with spectra of the sample

and pure-element standards. Spectral lines are then chosen from considerations of sensitivity and absence of spectral overlap. The exit-slit

carriage is mounted on the microdensitometer with the reference photographic

plate, and slits are positioned in alignment with the chosen lines on the

plate. Final alignment is accomplished by adjustment of a refractor plate

in front of each slit.

A wavelength scan of each element is stored in the computer for

output on the terminal. From plots of intensity-versus-wavelength for

each element, the spectral peak position is checked and background correction points on either side of the peak are chosen. Spectral scanning and

background sampling are accomplished by computer-controlled rotation of a refractor plate positioned behind the spectrometer entrance slit. In this

manner, true net intensities for the spectral lines are calculated and

either stored in the computer for calibration or displayed on the terminal.

Evidence has been found indicating differences in analytical response

between pure-element standards and samples of complex matrices which are

not due to spectral interference. These effects become significant when

applying the ICP technique to high-accuracy analysis of SRM's. Chemical

matrix effects in the plasma itself can cause up to a 15-percent relative

enhancement or depression of the analyte element intensity depending on the spectral line and plasma operating conditions. Complete definition

of the problem has involved examination of compromise conditions for

simultaneous multielement analysis both from the point of view of sensitivity as well as matrix effect suppression.

One way to estimate a suspected matrix effect is to record net

intensities for various elements at constant concentrations, with and

without an excess (3000 yg/mL) of potassium present. The ratio of intensity with potassium to intensity without potassium can be plotted with

respect to an instrument variable such as power, or observation height.

The objective is to find operating conditions which result in a ratio

close to 1.00 without significantly affecting the signal -to-background

ratio. At present, no serious degradation in signal-to-background ratio

has been caused by tuning the ICP for minimum matrix effect. However,

the data include only five elements thus far, therefore the results must

be considered to be preliminary. This data, as well as its extension to

additional elements and matrices, will provide the information necessary

to minimize analytical bias in simultaneous multielement analysis using

the ICP technique.

R. L. Watters, Jr.

78
5-

12. Atomic Weight of Silver

A redetermination of the atomic weight of silver has been accomplished with an estimated accuracy of 1.4 parts in 10^ (based on a preliminary statistical evaluation of the data). The project was undertaken to serve the needs of the CODATA Task Group on Fundamental

Constants. A high accuracy determination of the atomic weight of silver

is of crucial importance because only with such a result in hand can

full use be made of Bower and Davis' [1] sub-ppm determination of the

electrochemical equivalent of silver to calculate a high accuracy value

of the Faraday constant. The Bower-Davis Faraday value is presently

based on the atomic weight of silver as determined 20 years ago at NBS

[2]. This atomic weight, however, has an uncertainty twice as large as that obtained by Bower and Davis for the electrochemical equivalent of

silver. By reducing the uncertainty in the atomic weight of silver by an order of magnitude, the Faraday constant could be improved by a factor of

two. A reliable value of the Faraday will, in turn, permit the critical

testing of the measured values of a number of constants including the

I Avogadro constant, the magnetic moment of the proton in units of the

I nuclear magneton, the ratio of the NBS as-maintained ampere to the absolute ampere, and the gyromagnetic moment of the proton. The new atomic

weight data are to be turned over to representatives of the CODATA Task

Group on Fundamental Constants who will be conducting a new least squares

;| adjustment of the fundamental constants. The resulting recommended

i values are to be adopted for international use by the CODATA General

;j Assembly at its 1981 meeting.

A high accuracy determination of the atomic weight of a polynuclidic

element requires the combination of classical wet chemistry and high

precision mass spectrometry. The methods developed for each must be

I precise to one part in 10^. For redetermination of the atomic weight of

silver, a high precision chemical assay procedure was developed so that

! accurately known quantities of ^°^Ag and ^'^^Ag separated isotopes could

I be mixed to produce standards for calibration of the mass spectrometer.

I The el ectromagnetical ly separated silver isotopes (approximately 1 g of

I each) were purified by a method in which silver was precipitated as silver

I chloride, dissolved in ammonium hydroxide and el ectrodeposited as

' metallic silver on a platinum dish. Each purified silver isotope was

; taken into solution with nitric acid and a portion was analyzed for

! impurities by isotope dilution spark source mass spectrometry. No

I impurity element was found at a concentration level greater than 10 ppm.

'l

i The concentration of each separated isotope solution was determined

|i by a high precision-high accuracy method developed for natural silver

|j solutions. The method is based on the gravimetric determination of the

;i major portion of the silver (>99.7 percent) as silver iodide and the

*! determination of the soluble residual silver by isotope dilution mass spectrometry. The uncertainty in the assay of these solutions at the

95 percent confidence level is 0.006 percent.

I Eight calibration mixtures were prepared, by weight, from the separated isotope solutions. Six were within a few percent of the natural

i

79
isotopic ratio and two were significantly altered, i.e. 1:2 and 2:1. The

uncertainty in mixing the isotopes by weight is less than a few parts in

10 ^

The relative isotopic compositions of the calibration mixes were determined by thermal -ionization mass spectrometry using a platinum

single-filament silica gel technique. This technique, which involves

loading sequential layers of silica gel, sample, and phosphoric acid onto

the filament surface, has never been used before in high accuracy atomic

weight determinations because the method of ionization enhancement is not

well understood. However, in the case of silver, it proved to be the key

to achieving levels of precision not possible with other modes of ionization. Thirty-two determinations of the relative isotopic composition of

the silver standard, SRM 978a, were conducted with a standard deviation

of 5.4 parts in 10^. It is hoped that the high level of precision

obtained using the silica gel technique will encourage a more thorough

investigation of this method of ionization enhancement.

Two complete sets of measurements of the calibration mixes and the

silver standard (SRM 978a) were made by two different operators using

different mass spectrometers. Each set consisted of four measurements

of each calibration mix and thirty- two measurements of the reference

standard. The samples were measured in a pattern alternating randomly

selected mixes with the standard. Application of the correction factors

obtained from the analysis of the calibration mixes to the relative

isotopic composition of the silver standard allows the calculation of

the absolute isotopic composition of that standard. The atomic weight

of silver can then be calculated by summing the products of the absolute

isotopic abundance of each isotope and its nuclidic mass.

Based upon preliminary calculations, the absolute isotopic abundance

of the silver standard, SRM 978a, was found to be 1.0764, yielding an atomic weight of 107.8682. This determination of the atomic weight of

silver will lead to a reduction of the uncertainty in the Faraday constant

from 2.5 ppm/S.D. to approximately 1.5 ppm, the original target value.

This reduction in uncertainty will greatly enhance the usefulness of the

silver Faraday in the CODATA least squares adjustment of the physical

constants

.

This determination of the atomic weight of silver will be published

in the Journal of Research of the National Bureau of Standards.

References

[1] Bower, V. E. and Davis, R. S., Res . Nat . Bur . Stand . (U.S.),

85 0980).

[2] Shields, W. R. , Craig, D. N., and Dibeler, V. H. , jJ. Amer . Chem. Soc., 82 , 5033 (I960).

L. P. Dunstan, J. W. Gramlich, T. J. Murphy, P. J. Paulsen

80.
13. High Accuracy Mass Spectrometric Isotopic Analysis of Uranium

Standards of known uranium isotopic composition are recognized as essential in the control and safeguarding of nuclear materials. NBS has

traditionally provided Standard Reference Materials of known uranium

isotopic composition to meet the needs of the nuclear community. Most

of these SRM's are certified with an uncertainty of 0.1 percent. Trends

indicate that in the near future this level of uncertainty will no longer

meet the needs of regulations governing the nuclear industry because of

the large quantities of materials involved. It is, therefore, essential

that methodology be developed to allow measurement and certification of

uranium isotopic compositions with approximately an order of magnitude

smaller uncertainty.

The limiting factor in the accuracy and precision of mass spectrometric isotope ratio measurements for most elements is the ability to

control and reproduce the rate of isotopic fractionation during the

thermal ionization process. This rate of fractionation is influenced by

the molecular weight of the species being voli tali zed from the sample

filaments, as well as by the chemical and crystalographic form of the

sample on the filament.

Standard procedures employed at NBS and most other laboratories

performing uranium isotopic analysis involve conversion of the uranium

to the oxide either as UO3 or U 3 O 8 before analysis in the mass spectrometer. During the past year, the uranium oxide sample deposits were

microscopically examined at various stages of the loading procedure.

Since the uranium oxides are strongly colored and various crystal forms

and degrees of hydration of UO 3 show different coloration, it was easy

to observe that reproducing the chemical and crystalographic species on the filament is extremely difficult. This difficulty is intensified

when working with "real world" samples as opposed to high purity standards.

In an attempt to avoid the problems associated with the uncertain

stoichiometry of the uranium oxide system, a new sample loading procedure

was developed. A solution of uranium in nitric acid is evaporated at

low temperature onto a rhenium filament to produce a deposit of uranyl

nitrate hexahydrate. The filaments are then heated to approximately

60 ®C to melt the hexahydrate, producing a uniform sample- filament

coating. The hexahydrate is then converted to the di hydrate by heating

at 100 °C before loading into the mass spectrometer. At these low

temperatures, formation of oxides is avoided. Use of this procedure

over a six month period, has resulted in a precision for the analysis

of the 235y/238y ^^tio of 22 samples of SRM U-500, of 0.006 percent

relative (1 std. dev.).

This procedure was recently used to certify the concentration and

isotopic composition of SRM 995, a 233(j spike solution. Eight ampoules

of the SRM were calibrated by isotope dilution against both SRM 993, a spike solution, and SRM 960, a uranium metal standard. In addition,

SRM 993 was calibrated against SRM 960, providing a direct correlation

between the three SRM's. Statistical analysis of this work showed the

uncertainty in the measured concentration of uranium in the SRM, including

81
both random and possible systematic errors, to be less than 0.05 percent

relative at the 99 percent confidence level. This procedure will also

be used to certify the uranium isotopic composition in a series of three

new uranium SRM's.

J. W. Gramlich, L. A. Machlan

14. Half-Life of 24ipu

Accurate half-life values of the plutonium isotopes are needed to

accurately certify and to keep current the isotopic composition of the

NBS plutonium Standard Reference Materials. In addition, the accurate

half-life values are needed in the fulfillment of the NBS commitment to

provide essential standardization for nuclear safeguards and related

measurements, especially the effort to develop SRM's for non-destructive

assay techniques. An accurate value for the half-life of ^^^^Pu has been

a particularly elusive parameter for more than a decade with measurements

by alpha counting, calorimetry, and mass spectrometry giving values ranging from 13.8 ± 0.3 to 15.16 ± 0.19 years. Since the essence of a half-life determination is either the precise and/or accurate measurement

of the number of atoms present at two points in time, or a series of

isotopic ratio measurements as a function of time, the high precision

(approaching 1 in 10^) capability of mass spectrometry is an attractive

approach. The mass spectrometric measurements are divided into two parts,

the chemical preparation of the sample and the isotopic ratio measurements

using the mass spectrometer. The general sources of error recognized in

the measurement are interference, isotopic fractionation, and analytical

blank. The error due to analytical blank was found to be insignificant

for the analysis of plutonium. The interference can be traced to isobars,

background contributions from either organic or inorganic molecules and

ion scatter or signal suppression from intense ion beams from other than

plutonium. The major concern is for isobaric interference at mass 241

(americium), decay product of ^^^Pu.

The chemical separation procedure, two passes through anion exchange

columns in the nitrate form, were proven effective for the separation by gamma spectrometric analysis of a freshly separated plutonium

sample and by mass spectrometric analysis of samples after repeated

column separations. The other potential interference problems were

reduced to an insignificant level by use of high-purity reagents, proper

cleaning of the filament assembly and the ion exchange separation.

With 2'^^Am removed from plutonium, the next greatest potential source of error is isotopic fractionation. The correction for isotopic fractionation for each of the six plutonium samples at time zero was determined

by analyzing uranium SRM U500 under equivalent analytical conditions as plutonium. After the initial correction of the isotopic abundance ratios

of each sample the ^^^Pu/^^^^Pu ratio, after adjustment for radioactive

decay, was used to determine the isotopic fractionation for all subsequent

measurements. In addition, all analyses were made according to a strict

analytical protocol to precisely reproduce the isotopic fractionation

effect.

82
The half-life results for independent decay curves for six

different plutonium samples, including three SRM's varied from 14.32 to

14.36 years. The proposed half-life value is 14.34 ± 0.04 years where

the indicated uncertainty is the sum of the precision of the measurement

and allowances for known sources of possible systematic error.

E. L. Garner, L. A. Machlan

15. High Precision Pulse-Counting

Pulse-counting detection provides the highest sensitivity for measuring mass spectrometric ion beam currents and is the method of choice

when ion beam currents are limited by sample size. For radioactive

samples, the desirability of making measurements on minimum size samples

is obvious to minimize safety risks to the analysts and contamination of

the mass spectrometer. For this reason, a pulse-counting thermal ionization mass spectrometer has been put into operation and calibrated to

provide measurements needed in the nuclear safeguards field. In the past

year, this instrument has been used to study the resin bead sample loading

technique, to certify plutonium and uranium standards, and to provide

quality assurance for Faraday cup mass spectrometric measurements by the

more accurate evaluation of loading blanks. Research has demonstrated

that both uranium and plutonium can be analyzed, using nanogram samples,

with precisions and accuracies less than 0.1 percent.

The resin bead sample loading technique in which the sample is

absorbed onto an ion exchange resin bead that is subsequently loaded

directly onto the ionization filament of the mass spectrometer, has been

singled out by the international safeguards community for its promising

advantages of facilitating shipping as well as minimizing sample size

and sample handling in the analysis of uranium and plutonium. The

advantages of the technique are (1) the selective absorption of U and Pu

by the beads from the fission and actinide products in dissolver solutions,

(2) the convenience of handling the nanogram quantities on beads including

the ability to analyze beads directly in the mass spectrometer, and (4) the

minimization of the radioactivity involved. The role of NBS in the resin

bead program is to provide measurement assurance for the accurate isotopic

analysis of uranium and plutonium. To fulfill this role, both chemical

and mass spectrometric methodology for calibration and standardization

have been investigated. Furthermore, a round robin has been organized

which includes a majority of laboratories in the U.S. with the proven

capability of making high sensitivity mass spectrometric measurements.

The intent of the round robin is to generally investigate the reliability

of the technique in terms of precision and accuracy achievable and to

introduce this novel procedure to a broader range of laboratories.

A systems calibration, consisting of the determination of the

235y/238u p^tio in the well characterized SRM series U-050 to U-930, is

the standard procedure in this laboratory for determining the limit of

error in the isotopic measurement process. Systematic biases in this

calibration are an indication of systematic errors which could result

83
from lack of control of fractionation, discrimination, or inaccurate

counting-loss correction. The results of a calibration in this laboratory using beads loaded with U-100, U-350, U-500, U-750, and U-900,

respectively, exhibited a standard deviation of theoretical/experimental

values of 0.045 percent. There were no significant discrimination or counting loss errors observed. Variability can be attributed to the

differential isotopic fractionation behavior of individual beads.

In the preparation and evaluation of uranium loaded beads, it was found that the composition of the beads (nitrate-versus-chloride) and

size of the beads drastically affect not only the loading efficiency of

uranium from solution but also the ionization efficiency of the material

absorbed on the bead in the mass spectrometer. Research is continuing

on identification of the optimum parameters for preparing beads containing

1-3 nanograms of uranium that can be efficiently ionized in the mass spectrometer.

Research has been invested in the development of a procedure for the mass spectrometric determination of nanogram quantities of plutonium.

The traditional procedure utilizirrg.a triple-filament loading technique,

microgram quantities of material, and Faraday cup detection was deemed

impractical for a large number of measurements in present laboratory

facilities. This research culminated in a procedure in which 0.1 to 0.4

nanograms of plutonium were directly electroplated on a single rhenium

filament and subsequently analyzed by the pulse counting mass spectrometer.

This procedure was utilized in the characterization of a ^^'^Pu reference

material by isotope dilution. In this characterization work, standards were analyzed with a standard deviation of 0.058 percent in the measurement of the ^^°Pu/^^^Pu ratio. The concentration of the ^^^Pu material

was determined with a standard deviation of 0.06 percent. This assayed

^'^^Pu reference material will allow both isotopic abundance and assay

determinations to be made in a single isotope dilution mass spectrometric

analysis, thus reducing the number of characterization measurements of

unknown plutonium material by half.

J. D. Fassett, W. R. Kelly

1 6 . High Accuracy Method for Determining Sulfur in Iron Base Alloys

The knowledge and control of minor and trace concentrations of

sulfur in iron and steel is exceedingly important for obtaining final

products that possess desirable rather than deleterious properties. By

far the most useful function of sulfur is its ability to improve the

machinabil i ty of steels. For sulfur concentrations up to almost 0.3

percent, there is a concommitant improvement in the ease of machining

with increasing amounts of sulfur. Paralleling this increase in machinabil ity, however, is a decrease in strength and hardness, the loss of

either of which may or may not be desirable. An area in which trace

concentrations of sulfur definitely produce a detrimental effect in

steels is stress corrosion. At concentrations above 0.01 percent, weldability is poor and the strengths of the welds are reduced appreciably.

84
In terms of large tonnage production , the greatest effort to keep sulfur

below 0.01 percent is made tn the manufacture of ductile iron.

Because sulfur possesses this capability of imparting both positive

and negative properties to iron and steel, the analytical need for standards whose sulfur content is known accurately is paramount. The present

interest of CAC in the question of the accuracy of sulfur values in

certified standards was initiated by two publications in the open literature which were brought to our attention [1,2]. Both publications came

from the same Japanese laboratory and employed an isotope dilution gas mass spectrometer (IDGMS) procedure for analysis. Because of the

widespread acceptance of IDMS as a definitive technique and the implication in these two papers that the certified sulfur values in several

NBS SRM's might be as much as 20 percent high, the need to resolve this

problem was considered particularly important.

After examining the experimental details of the two Japanese

publications, it was concluded that the discrepancy between their IDGMS

results and the certified values could possibly be accounted for by loss

of sulfur before spike equilibration had occurred. This explanation

certainly seemed feasible since, in the Japanese procedure, the samples were invariably dissolved before the spike was added.

To eliminate the possibility of losing sulfur through volatilization

and at the same time to optimize conditions for sample and spike sulfur

equilibration, we elected to perform all dissolutions in sealed, borosilicate tubes at elevated temperature and pressure. Since a gas mass spectrometer was not available, we further elected to use a spark source instrument for measurement of the ^ 45/325 ^atio. To prepare the sample

for spark source analysis, the sulfur was separated by reduction to H2 S

and collected as Ag 2 S by bubbling through a solution of AgNOs. The Ag 2 S

precipitate was centrifuged down, washed, mixed with high-purity gold

powder and pressed, with repetitive folding, into the desired mounting

form.

Using the sealed tube dissolution, the four NBS SRM's identified in

the two Japanese publications (SRM's 32e, 33d, 72f, 133a) were reanalyzed

for sulfur. In addition, five newer SRM's (361-365) were reanalyzed by

the sealed tube procedure at NBS. The same SRM's were analyzed by the

Japanese laboratory using their open-beaker procedures. Exchange and

comparison of the data clearly indicate that whenever a discrepancy

exists, the sulfur results obtained by open-beaker dissolution followed

by ^‘^S spiking are invariably lower than the sealed tube results. Using

the open beaker dissolution followed by ^‘^S spiking, we have been able to

demonstrate that significantly lower results can be obtained. An even more disconcerting observation is that, even though the results are significantly lower, the precision is scarcely affected. For example,

open beaker dissolution of NBS SRM 362 followed by spiking yielded

sulfur concentrations of 318, 328, and 320 ppm for three separate sample

analyses. Sealed tube dissolution, on the other hand, yielded sulfur

values of 360, 364, and 357 ppm. The NBS observations were transmitted

to the Japanese laboratory together with a request to analyze SRM's 362

85
and 364 by the sealed tube technique. These two SRM's were selected

because the IDMS data from the two laboratories were most different for

these. Using the sealed tube technique, the Japanese analyses of three

separate samples of SRM's 362 and 364 yielded values of 358, 357, 360,

and 247, 245, 247 ppm, respectively. These results may be compared

directly to the NBS sealed tube results obtained previously on SRM 362

(see above) and to the NBS results obtained on SRM 364, i.e., 247, 251,

and 251 ppm for three separate analyses.

The sealed tube dissolution technique in combination with IDSSMS

has established that the NBS certified values for sulfur in those SRM's

identified above are in close agreement with the IDMS measurements. The

lower IDMS results reported earlier by the Japanese laboratory can best

be accounted for by loss of sulfur before spike equilibration. Work is now underway to reanalyze additional SRM's in order to assess the

accuracy of the certified sulfur values. Special attention is being

given to establishing the accuracy of the sulfur values in the three

major types of iron base alloys that are necessary for improving the

accuracy of automated analyzers, namely low-alloy steels, high temperature

alloys, and cast irons.

References

[1] Watanabe, K. , Anal . Chim . Acta , 80 , 117 (1975).

[2] Watanabe, K. , Talanta, 26, 251 (1979).

R. W. Burke, G. M. Lambert, E. J. Maienthal, P. J. Paulsen

1 7 . Standard Reference Materials

The analysis and certification of Standard Reference Materials

(SRM's) are a major part of the total scientific effort of this Division,

amounting to about 25 percent of the total budget with input from almost

all of our scientists. The SRM's completed or started this year are

shown in the following list. They include a wide variety of matrices

(aqueous, botanical, zoological, fossil fuel, rock, metal, etc.) and were certified for concentration levels ranging from ultratrace to

major.

A notable accomplishment was the certification of the inorganic

electrolytes (Na, Ca, K, Li, and Cl) in SRM 909, Human Serum. This is

the first human serum certified by NBS for inorganic constituents con_

tinually measured by clinical laboratories. It was certified using the

definitive methods which were previously developed for the evaluation of

the accuracy of clinical reference methods. A definitive method may be

defined as one which has a valid and well defined theoretical foundation,

has been experimentally evaluated so the reported results have neglible

systematic errors, and has high levels of precision.

86
other significant efforts include the certification of a large

number of trace and major constituents in an animal tissue (SRM, Bovine

Liver), and a plant tissue CSRM, Citrus Leaves). Utilization of these

SRM's will lead to improved accuracy of measurements used in health and

environmental areas.

In the area of nuclear SRM's, a spike and a ^’^‘^Pu spike have

been certified for both isotopic composition and concentration. These

SRM's will permit the determination of both properties in the same sample, reducing the sample's load by one half. Work was started on the

certification of four new uranium isotopic standards for non-destructive

analysis (NDA). These will be the first nuclear SRM's issued for MDA.

Work Carried Out on Standard Reference Materials

by Division 551 During FY 80

• t SRM # Title Effort 1

1620, 1621a, 1622 Sulfur in Fuel Oil 0.3

966 Pu 244 Spike 0.4

995 U 233 Spike 0.3

1577a Bovine Liver 2.1

1643a Trace Elements in H

2

O 0.1

1646 Estuarine Sediment 0.4

76a, 77a, 78a Zirconium in Burnt Refractories 0.1

1174,1175,1145,

1146,1150

White Cast Irons 0.1

Cl 287, Cl 288, Cl 289,

Cl 287a, Cl 288a, Cl 289a High Alloy Steels 0.5

83d Arsenic Trioxide 0.1

930d Glass Filters for Spectrophotometry 0.3

1285,1286 Low A1 loy Steels 0.2

1572 Citrus Leaves 1.0

1084,1085 Wear Metals in Oil 0.1

Uranium Non-destructive Analysis Standard 0.5

329 Zinc Concentrate 0.1

1636a, 1637a, 1638a Pb in Reference Fuels 0.1

C1173,C1173a Cast Steels 0.1

1590 Stabilized Wine 0.1

909 Human Serum 0.9

87
Work Carried Out on Standard Reference Materials

by Division 551 During FY 80 (continued)

SRM # Title

890,891 ,892 A1 loy Cast Irons

1270 2 1/4 Cr-1 Mo Steel

1634 Trace Elements in Fuel Oil

1234,1235,1236,

1237,1238.1239

Zirconium Base Alloys

1269 Line Pipe Steel

2030 Glass Filters for Spectrophotometry

723(a) TRIS

1224, 14f Basic Open Hearth Steel

1261a, 1262a, 1263a,

1264a, 1265a

Low Alloy Steels

136d Potassium Di chromate

691 ,691a Reduce Iron Oxide

350 Benzoic Acid

1155a Stainless Steel

729,1225 Low A1 loy Steel

Total

Effort M/Y

0.9

0.3

0.9

0.1

0.3

0.1

0.2

0.3

0.3

0.1

0.2

0.1

0.1

0.3

12.0

88
C. Outputs and Interactions

(Inorganic Analytical Research Division)

1 . Publ ications

Omenetto, N. , Epstein, M. S., Bradshaw, J. D., Bayer, S., Horvath, J. J.,

and Winefordner, J. D., "Fluorescence Ratio of the Two D Sodium

Lines in Flames for D1 and D2 Excitation," J. Quant. Spectrosc.

Radiat. Transfer, 287 (1979).

Epstein, M. S., Nikdel, S., Omenetto, N., Reeves, R., Bradshaw, J. D.,

and Winefordner, J. D., "Inductively-Coupled Argon Plasma as an Excitation Source for Flame Atomic Fluorescence Spectrometry,"

Anal. Chem., 2071 (1979).

Failey, M. P., Anderson, D. L. , Zoller, W. H., Gordon, G. E. , and

Lindstrom, R. M., "Neutron-Capture Prompt y-Ray Activation Analysis

for Multi-Element Determination in Complex Samples, Anal. Chem.,

2209 (1 979).

Alvarez, R. A., and Rains, T. C., "National Bureau of Standards Standard

Reference Material for Quality Control of Nutrient Element Determinations in Food," Proc. of Nutrient Analysis Symposium, 93rd

Annual Meeting of the Association of Official Analytical Chemists,

Washington, DC, October 15-18, 1979, p. 86.

Carpenter, B. S., Pilione, L. J., Schroder, I. G., Roe, J. W., and

Sanatini, S., "Evaluation of Reactor Track- Etch Power Monitor,"

ANS Transactions, Vol . 33,

^ (1979).

Mielenz, K. D. , "Beam Splitter and Cell Window Errors in Fluorescence

Spectrometry," Appl . Optics, 1_8, 4134 (1979).

Brill, R. H. , Yamasaki, K. , Barnes, I. L., Rosman, K. J. R., and Diaz, M.,

"Lead Isotopes in Some Japanese and Chinese Glasses," Ars Orientalis,

11, 87 (1979).

Epstein, M. S., Omenetto, N., Nikdel, S., Bradshaw, J. D., and Winefordner,

J. D., "Inductively-Coupled Argon Plasma as an Excitation Source

for Flame Atomic Fluorescence Spectrometry," Anal. Chem., 284

(1 980).

Greenberg, R. R. , "Simultaneous Determination of Mercury and Cadmium

in Biological Materials by Radiochemical Neutron Activation

Analysis," Anal. Chem., 676 (1980).

Lux, F., Zeisler, R. , and Reher, J., "Aktivierungsanalytische Untersuchungen

liber die Probenmengenabhangigkeit der Streuung der Spurenelementgehaltswerte von Bleiweiss sowie liber den cisalpinen Typ von Bleiweiss aus einem Rubens-Gemalde, " Radiochem. Radioanal . Letters,

42, 341 0980).

1^
Lindstrom, R. M. , "Measuring Trace Elements in Semiconductors: Methods

and Pitfalls," Solar Cells, 1 (2), 117 O9S0).

Koch, W. F., "The Value of the Faraday Via 4-Ami nopyridine," in Atomic

Masses and Fundamental Constants 6, J. A. Nolen, Jr. and W. Benenson,

eds . , (Plenum Press, NY, 1980), p. 167.

Epstein, M. S., Nikdel, S., Bradshaw, J. D., Kosinski, M. A., Bower,

J. N. , and Winefordner, J. D. , "Atomic and Ionic Fluorescence

Spectrometry with Pulsed Dye Laser Excitation in the InductivelyCoupled Plasma," Anal. Chim. Acta, 113 , 221 (1980).

Epstein, M. S., Bayer, S., Bradshaw, J. D. , Voigtman, E. , and Winefordner,

J. D. , "Application of Laser-Excited Atomic Fluorescence Spectrometry to the Determination of Iron," Spectrochim. Acta, 35B, 233

(1980).

Epstein, M. S., Bradshaw, J. D., Bayer, S., Bower, J., Voigtman, E.,

and Winefordner, J. D., "Application of Laser-Excited Atomic Fluores- cence Spectrometry to the Determination of Nickel and Tin,"

Appl . Spectrosc., 372 (1980).

Epstein, M. S., and Winefordner, J. D., "Precision and Linearity of

Determinations at High Concentrations in Atomic Absorption Spectrometry with Horizontal Rotation of the Burner," Talanta,

177 (1980).

Christian, G. D. , and Epstein, M. S., "Atomic Absorption Spectroscopy,"

American Chemical Society Audio Course, American Chemical Society,

Washington, DC (1980).

Deardorff, E. R. , Rains, T. C. , and Koch, W. F., "Simulated Precipitation

Reference Materials, III," NBSIR 79-1953, April 1980.

Carpenter, B. S. , and Jones, F. E. , eds., "Measurements and Standards

for Nuclear Materials Safeguards," NBSIR 80-2033, May 1980.

Velapoldi, R. A., Paule, R. C. , Schaffer, R. , Mandel , J. , Machlan, L. A.,

Garner, E. L. , and Rains, T. C. , "Standard Reference Materials:

A Reference Method for the Determination of Lithium in Serum,"

NBS Spec. Publ . 260-69, U.S. Department of Commerce, 1980, p. 1.

Dunstan, L. P. , Gramlich, J. W., Barnes, I. L. , and Purdy, W. C.,

"Absolute Isotopic Abundance and the Atomic Weight of a Reference

Sample of Thallium," J. Res. Nat. Bur. Stand. (U.S.) 1 (1980).

Stacey, J. S., Delevaux, M. H. , Gramlich, J. W., Doe, B. R., and Roberts,

R. J. , "A Lead Isotope Study of Mineralization in the Arabian Shield,"

U.S. Geological Survey Saudi Arabian Mission Technical Record 8,

1 980.

90
Canada, T. R., and Carpenter, B. S., eds., "Measurement Technology for

Safeguards and Materials Control," NBS. Spec. Publ . 582 0980).

Mitchell, J. W., Riley, Jr., J. E., and Carpenter, B. S., "Major

Elemental Boron Determination by the Nuclear Track Technique,"

ANS Transactions, Vol . 34, 143 (1980).

Kelly, W. R., and Wasserburg, G. J., Letter in response to article

"Did the Solar System Start with a Bang?", Sky and Telescope,

14 (1980).

Fassett, J. D., Kelly, W. R., Machlan, L. A., and Moore, L. J., "Mass

Spectrometric Isotope Metrology of Uranium on Resin Beads," in

Radioelement Analysis Progress and Problems, W. S. Lyon, ed.,

Ann Arbor Science, p. 357, 1980.

Kaiser, T. , Kelly, W. R. , and Wasserburg, G. J., "Isotopical ly Anomalous

Ag in Two Iron Meteorites," XI Lunar and Planetary Science Conference Abstracts, Vol. 2, The Lunar and Planetary Institute,

Houston, TX, p. 527 (1980).

Kaiser, T. , Kelly, W. R., and Wasserburg, G. J., "Isotopical ly

Anomalous Silver in the Santa Clara and Pihon Iron Meteorites,"

Geophys. Res. Letters, 7^, 271 (1980).

Lindstrom, R. M. , and Fleming, R. F. , "Accuracy in Activation Analysis:

Count Rate Effects," to be published in Proc. of 4th International

Conference on Nuclear Methods in Environmental and Energy Research

(Univ. of Missouri, Columbia), 1980.

Mavrodineanu , R. , and Baldwin, J. R. , "Metal -On-Quartz Filters as a Standard Reference Material for Spectrophotometry--SRM 2031,"

NBS Spec. Publ. 260-68 (1980).

Harrison, S. H., Maienthal, E. J., Gills, T. E., and Zeisler, R.

,

"Protocol for the Collection, Storage, and Analysis of Human Organs

the Pilot Bank Project of the National Environmental Specimen

Bank," in Trace Substances in Enviromental Health, XIII,

D. P. Hemphill, ed., U. of Missouri, Columbia, June 1980, in press.

Paulsen, P. J., Burke, R. W. , Maienthal, E. J., and Lambert, G. M.

,

"Isotope Dilution Spark Source Mass Spectrometric Determination

of Sulfur in Some Current NBS-SRMs CFe- based Alloys), Proc. ASTM

Symposium on New Analytical Techniques for Trace Constituents

of Metal-Bearing Systems, Chicago, IL, June 1980, in press.

Carpenter, B. S., and Pilione, L. J., "Lithium and Lithium-6 Analysis

in Solutions by the Nuclear Track Technique," Anal. Chem, in press.

91
Moore, L. J. , Heald, E. F. , and Barnes, I. L., " Thermodynamic and

Empirical Studies of Fractionation in the Thermal Ionization

Multiple Filament Source," Proc. of the 8th International Conference

on Mass Spectrometry, Oslo, Norway, in press.

Harrison, S. H., Zeisler, R., and Wise, S. A., "Pilot Program for the

National Environmental Specimen Bank--Phase I," to be published

as an NBS Tech. Note.

Kingston, H. M. , and Pella, P. A., "X-Ray Spectrometric Analysis of

Trace Metals in Environmental and Biological Samples Using Exchange

Resin-Loaded Filters," submitted to Analytical Chemistry, July 1980.

Horvath, J., Bower, J., Bradshaw, J. , Epstein, M. S., and Winefordner,

J. D. , "Comparison of Nebulizer-Burner Systems for Laser-Excited

Flame Atomic Fluorescence Spectrometry," submitted to Anal. Chem.

Kaiser, T. , Kelly, W. R. , and Wasserburg, G. J., "Hoba and Tlacotepc:

Two New Meteorites with Isotopically Anomalous Ag," submitted to

43rd Meteoritical Society Meeting, San Diego, CA, Sept. 2-6, 1980.

Zeisler, R., Greenberg, R. R., and Gills, T. E., "Standard Reference

Water and Its Mul ti-El ement Assay by Nuclear Activation Techniques,"

submitted to J. Environ. Anal. Chem.

Wynn, T. , Clardy, P., Bower, J., Bradshaw, J., Epstein, M. , and Winefordner,

J. D. , "Wavelength-Modulated Continuum-Source Atomic Fluorescence

Spectrometer for Wear Metal Analysis in Jet Engine Oils Using

Electrothermal Atomization," submitted to Anal. Chim. Acta.

2. Talks

Fassett, J. D. , Kelly, W. R., Machlan, L. A., and Moore, L. J. , "Mass

Spectrometric Isotope Metrology of Uranium on Resin Beads,"

Twenty- Third Conference on Analytical Chemistry in Energy Technology, Gatlinburg, TN, October 10, 1979.

Rains, T. C. , "NBS Standard Reference Materials for Quality Control of

of Nutrient Element Determination in Foods," 93rd Annual Meeting of

Official Analytical Chemists, Washington, DC, October 15, 1979.

Harrison, S. H., "The Sampling and Storage Protocols for the Collection

of Human Livers," Joint U.S. /German Bilateral Meeting on Specimen

Banking, National Bureau of Standards, Washington, DC, November 15,

1 979.

Zeisler, R. L. , "Development of an Analytical System to be Applied in the

NESB Program," Joint U.S. /German Bilateral Meeting on Specimen Banking,

National Bureau of Standards, Washington, DC, November 15, 1979.

92
Greenberg, R. R. , "Simultaneous Determination of Arsenic, Antimony, Cadmium,

Chromium, Copper, Molybdenum, Selenium, and Silver in Tissue Samples

by Radiochemical Neutron Activation Analysis, Joint U.S. /German

Bilateral Meeting on Specimen Banking, National Bureau of Standards,

Washington, DC, November 16, 1979.

Maienthal, E. J. , "Voltammetry," Joint U.S. /German Bilateral Meeting on Specimen Banking, National Bureau of Standards, Washington, DC,

November 16, 1979.

Gramlich, J. W., "Lead Isotopic Analysis of Glass," Centennial Meeting of

the Archaeological Institute of America, Boston, MA, December 28, 1979.

Watters, Jr., R. L., "Sampling and Analysis Strategies for Plasma Spectrochemical Analysis," International Winter Conference 1980--

Developments in Atomic Plasma Spectrochemical Analysis, San Juan, PR,

January 10, 1980.

Burke, R. W. , "NBS Studies on ASTM Special Fly Ash," ASTM Winter Meeting,

Ft. Lauderdale, FL, January 30, 1980.

Kingston, H. M., "A Prospective of Ultra Trace Elemental Analysis in

Chesapeake Bay Water with a Discussion of Clean Laboratory and

Field Sampling Technology, National Oceanic and Atmospheric Administration, Rockville, MD, January 31, 1980.

Rains, T. C. , "Atomic Absorption Spectrometry," ACS Short Course, Pittsburgh

Conference, Atlantic City, NJ, March 8, 1980.

Zeisler, R. L., "The National Environmental Specimen Bank--EPA/NBS Pilot

Program," Center for Trace Characterization Seminar, Texas A&M

University, College Station, TX, March 15, 1980.

Kaiser, T. , Kelly, W. R. , and Wasserburg, G. J., "Isotopical ly Anomalous

Silver in Two Iron Meteorites," XI Lunar and Planetary Science

Conference, Houston, TX, March 21, 1980.

Kingston, H. M. , "Analytical Chemical Techniques as Applied to Analysis

of Water In the Chesapeake Bay," Student Affiliation of the American

Chemical Society, Thiel College, Greenville, PA, March 27, 1980.

Lindstrom, R. M. , "Accuracy in Activation Analysis: Beyond Net Areas,"

Fourth International Conference on Nuclear Methods in Environmental

and Energy Research, Columbia, MO, April 14, 1980.

Rains, T. C. , "The State-of-the-Art of Atomic Absorption Spectrometry

with Electrothermal Atomization," St. Louis Section of the Society

for Applied Spectroscopy, St. Louis, MO, April 17, 1980.

Zeisler, R. L. , "The U.S. National Environmental Specimen Bank Program,"

Institut fur Radiochemie Seminar, Technische Universitat Munchen,

Munich, F. R. Germany, May 23, 1980.

93
Rains, T. C., "State-of-the-Art--Ul tra Metal Analysis in AAS," Mayo Clinic,

Rochester, MN, May 30, 1980.

Gramlich, J. W., "Sample Mounting Techniques for High Accuracy Uranium

Isotopic Analysis," 29th Annual Conference on Mass Spectrometry

and Allied Topics, New York, NY, June 4, 1980.

Kingston, H. M. , "Chesapeake Bay Trace and Toxic Elemental Measurement;

What'Do We Have and Where is the Value," NBS Colloquium on Mathematical Modeling in Science and Engineering, National Bureau of

Standards, Washington, DC, June 11, 1980.

Paulsen, P. J., "Isotope Dilution Spark Source Mass Spectrometric Determination of Sulfur in Some Current MBS-SRMs (Fe-Based Alloys),"

ASTM Committee E-03 Symposium on "New Analytical Techniques for

Trace Constituents of Metallic and Metal -Bearing Ores," Chicago, IL,

June 24, 1980.

Kelly, W. R., "Palladium-107 Isotopic Heterogeneity in the Early Solar

System," Department of Terrestrial Magnetism, Carnegie Institute

of Washington, Washington, DC, June 25, 1980.

Maienthal, E. J., "Vol tammetric Analysis of Things as They Are,"

Harvey Diehl Symposium, Second Chemical Congress of the North

American Continent, American Chemical Society Meeting, Las Vegas,

NV, August 29, 1 980.

Gramlich, J. W., "Recent Advances in High Accuracy Thermal Ionization

Mass Spectrometry," Symposium on Scientific Instrumentation,

University of Mexico, Mexico City, Mexico, September 2, 1980.

Greenberg, R. R. , Kingston, H. M., and Beary, E. S., "Analysis of

Estuarine Water and Associated Suspended Solids," VII Federation of

Analytical Chemistry and Spectroscopy Societies, Philadelphia, PA,

September 29, 1980.

3. Committee Assignments

I. Lynus Barnes

Member, Department of Health, Education, and Welfare, The Chemistry

Task Force of the National Shellfish Sanitation Program

Washington Editorial Review Board

International Union of Pure and Applied Chemistry, Commission

on Atomic Weights

Secretary, lUPAC, Commission on Atomic Weights, Subcommittee for

Assessment of Isotopic Abundances

Robert W. Burke

Member, ASTM E-03 Chemical Analysis of Metals

94
B. Stephen Carpenter

Member, American Nuclear Society Board of Directors

American Nuclear Society 16, Isotopes and Radiation

American Nuclear Society, Neutron Activation Analysis

Institute for Nuclear Material Management, Workgroup 9.3,

Standa»^ds for Nondestructive Assay

Barry I. Diamondstone

Member, ASTM D- 34. 02. 01, Section on Batch Extractions

ASTM D-19.2, Section on Hazardous Wastes in Water

ASTM E-03, Chemical Analysis of Metals

Michael S. Epstein

Secretary, Bal timore-Washi ncton Section of the Society for Applied

Spectroscopy

Member, ASTM D- 19. 07. 04, Section on Chemical Characterization of

Fluvial Sediment

ASTM D-19, Water

Registrations Chairman, VII Annual Meeting of the Federation of

Analytical Chemistry and Spectroscopy Societies

Ronald F. Fleming

Member, Program Committee, Fifth Symposium on X- and Gamma-Ray

Sources and Applications

Thomas E. Gills

Member, ASTM C-26, Committee on Nuclear Fuel Cycle

Howard M. Kingston

Member, NPS Nuclear Waste Study Group

William F. Koch

Member, ASTM D-19, Water

ASTM D-19.02, General Specifications

ASTM D-19.05, Inorganic Constituents

and Technical

in Water

Resources

Lawrence A. Machlan

Member, ASTM C-26, Nuclear Fuel Cycles

ASTM C-26. 01 , Editorial and Terminology

ASTM C-26. 05, Test Methods

E. June Maienthal

Member, ASTM D-19, Water

ASTM D-19.05, Inorganic Constituents in Water

ASTM D-19.06, Methods for Analysis for Organic Substances

in Water

ASTM D-19.07, Methods of Testing of Water-Reformed Deposits

and Properties of Water

ASTM D-19. 07. 04. 03, Trace Metals and Sediments

ASTM D-19. 11, Methods for the Analysis of Water for Power

Generation and Process Uses

95
ASTM E-03, Chemical Analysis of Metals

ASTM E-03. 01, Ferrous Metals

ASTM E-03. 02, General Analytical Practices

ASTM E-03. 05, Nonferrous Metals

Standard Methods for Examination of Water and Waste VJater

Joint Task Group for Pol arographic Methods

George Marinenko

Member, ASTM D-19, Water

ASTM D-19. 02, Specifications

ASTM D-19. 05, Inc’^ganic Constituents in Water

ASTM D-19. 09, Saline Water

ASTM D-19. 05. 03. 06, Ozone

Program Chairman, National Capital Section of the Electrochemical

Society

Jerry D. Messman

Assistant Registrations Chairman, VII Annual Meeting of the Federation

of Analytical Chemistry and Spectroscopy Societies

Coordinator, Science Fair Program for the Bal timore-Washington

Section of the Society for Applied Spectroscopy

Klaus D. Mielenz

Member, TC-3, Luminescence Subcommittee, International Commission

on Illumination

TC-2.3, Materials Luminescence

ASTM E-13, Molecular Spectroscopy

ASTM E-13. 06, Molecular Luminescence

John R. Moody

Member, ASTM D-19, Water

ASTM D-19.05, Inorganic Constituents in Water

Delegate, Middle Atlantic Regional Meeting, Chemical Society of

Washi ngton

Thomas J. Murphy

Chairman, Audit Committee, Chemical Society of Washington

Councilor, Chemical Society of Washington

Member, American Chemical Society Committee on Analytical Reagents

American Chemical Society Committee on Membership Affairs

American Chemical Society Admissions Committee

International Union of Pure and Applied Chemistry (lUPAC),

Commission on Atomic Weights and Isotopic Abundances

Member, International Union of Pure and Applied Chemistry (lUPAC),

Subcommittee for the Assessment of Isotopic Abundances, Commission on Atomic Weights and Isotopic Abundances

96
John A. Norris

Secretary, ASTM E-02, Emission Spectroscopy

Lecturer, Annual Short Course, "Modern Industrial Spectroscopy,"

Arizona State University, Tempe, AZ

Lura J. Powell

Chairman, Budget and Finance Committee, Chemical Society of Washington

Manager, Chemical Society of Washington

Financial Chairman, 1981 Middle Atlantic P>egional Meeting, American

Chemical Society

Member, Publicity Committee, VII Annual Meeting of the Federation of

Analytical Chemistry and Spectroscopy Societies

Chairman, Committee on Isotope Ratio Measurements, American Society

for Mass Spectrometry

Theodore C. Rains

Chairman, International Conference Committee of the Society for

Applied Spectroscopy

Member, Proposal Evaluation Committee for National Science Foundation

AOAC Committee on Automated Methods

Nominating Committee for the Society for Applied Spectroscopy

Editorial Board of Annual Reports on Analytical Atomic Spectroscopy (The Chemical Society of London) and the Canadian Journal

of Spectroscopy

ASTM E-02. 10, Non-Metal lie Materials

ASTM E-02. 13, Nomenclature

ASTM D-01 , Paint and Related Coatings

ASTM D-19, Water

Co-chairman, Program, VII Annual Meeting of the Federation of

Analytical Chemistry and Spectroscopy Societies

Director, Professional Development Program for the BaltimoreWashington Section of the Society for Applied Spectroscopy

Column Editor, Journal of Applied Spectroscopy

Professor-in-charge, ACS Short Course on "Atomic Absorption Spectroscopy"

Task Force Leader for Project Scientific Instrumentation Information

Network and Curricula (SUNG) on Atomic Absorption Spectroscopy

Robert L. Watters, Jr.

Secretary, I CP Detection Limits Committee

National Correspondent and Reviewer Designate, ICP Information

Newsl etter

97
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.rr. Organic Analytical Research Division

Harry S. Hertz, Chief

Dennis J. Reeder, Deputy Chief

A. Division Overview

The activities of the Organic Analytical Research Division encompass a wide variety of research capabilities and measurement procedures. Generic

research In organic analytical chemistry has resulted in the development of

new analytical methods for the detection, characterization, and quantitation

of trace amounts of organic compounds found in complex matrices. The

analytical capabilities of the Division are applied to measurement problems

in environmental, health/clinical, and energy-related areas. Results of

the work performed by the Division are utilized by other federal agencies,

public and private institutions, and by research programs at NBS.

The year just completed has been very productive. The accomplishments

have been numerous and the products of research exciting. We have summa- rized some of these accomplishments below and many are presented in more

detail in the individual technical accomplishments which follow. In reading

the group overviews and the technical accomplishments, there are several

points of particular note. The division is organized into groups by areas

of specialization: organic spectroscopy, gas chromatography, liquid

chromatography, mass spectrometry, bioanalytical techniques, and organic

electrochemistry. Projects, however, usually cross group lines and, in the

past year, we have witnessed an extensive number of successful intergroup

(and interdivision) task forces being formed and succeeding on difficult

problems. The groups have begun research along the lines presented in last

year's five-year research plans. The organic electrochemistry competence

building group has successfully started many of their projects and initiated

collaborative research efforts with other groups on several projects.

Three very significant Standard Reference Materials were completed this

year: SRM 1&44, Generator Columns for Polynuclear Aromatic Hydrocarbons in

Water; SRM 1580, Shale Oil; and SRM 909, Human Serum. A patent was awarded

on the NBS liquid chromatograph-mass spectrometer (LC-MS) interface and

considerable additional research has been performed on LC-MS this past year.

The first NBS "definitive" method for the determination of an organic

chemical in serum (cholesterol) was published in Clinical Chemistry and four

additional definitive methods either are completed or well along in their

development (glucose, uric acid, urea, and creatinine). In a study of the

retention behavior of polynuclear aromatic hydrocarbons on high-performance

liquid chromatographic (HPLC) bonded phases, it was found that the retention

could be predicted on the basis of the length to breadth ratio of the molecules. Research in the area of multi-dimensional gas chromatography has

expanded and the certification of 5,6-benzquinoline in the shale oil SRM

was achieved through use of this new capability. Installation of the 400

MHz nuclear magnetic resonance (NMR) spectrometer has been completed and

the instrument already has been used for several research problems,

including the high-accuracy quantitative analysis of trace constituents in

several existing and proposed SRM's.

99
During the past year, two new NRC post-doctoral fellows have joined

our division. One fellow will be investigating electrode reaction

mechanisms using surface enhanced Raman spectroscopy to provide molecular

spectra of adsorbed reactants, intermediates, and products. The second

NRC fellow will be investigating synthetic routes to and the NMR spectra

of uniquely labeled ^^N aminoglycosides, nucleotides, and nucleosides.

In the year ahead, we look forward to increasing our emphasis on more

basic research programs in spectroscopy by development of total lumines- cence techniques for mixture analysis, in the use of enzymes in analytical

chemistry, in gas chromatography by continued development of multicolumn

techniques, in liquid chromatography by investigating post-column reaction

systems, in mass spectrometry by investigating ionization mechanisms and

ion structures, and in electrochemistry by development of chemically modified electrodes as well as research in spectroel ectrochemistry . With the

completion of several major SRM's and a decrease in some of our programmatic commitments, we eagerly are anticipating the opportunity to expand

our efforts at the state-of-the-art in organic analytical chemistry.

1 . Organic Spectroscopy Group: Overview

The Organic Spectroscopy Group has continued its general responsibility

for; 0) research on determination of the fundamental molecular and system

parameters that affect measurement accuracy; (2) qualitative and quantitative analyses of compounds and mixtures; and (3) characterization and

certification of SRM's using nuclear magnetic resonance (NMR), polarimetry,

and fluorescence techniques.

Work this past year in the area of optical spectroscopy has dealt mainly

with research on development of "on-stream" analysis of aqueous solutions

of polynuclear aromatic hydrocarbons (RAM's) at the ppb level, developing

capabilities for on-stream total fluorescence spectroscopy, proving the

feasibility of using laser polarimetric techniques for optical rotatory

dispersion, and verifying the efficacy of derived equations for the optical

rotation of sucrose and quartz at different wavelengths. Additionally,

certification of SRM 1644 (Generator Columns) for production of known

aqueous standards of RAM's for use in the environmental and energy effluent

areas, and of SRM 17c [Sucrose) using the high-accuracy polarimeter has been

completed. Measurements on ym-sized fluorescence glass beads as potential

standards for microspectrofl uorimetry have also been completed. Expansion

of research in the analytical application of FT-IR and development of new

total luminescence techniques for the analysis of mixtures is anticipated

during the next year.

Much of the effort this year in NMR spectroscopy has been devoted to

the installation and testing of two, high- field superconducting NMR

spectrometers, which together form the high- field NMR facility of the

National Measurement Laboratory. Members of the group have had the major

responsibility for operation of the 400 MMz spectrometer, while personnel

of the Chemical Corrosion and Stability and Polymer Divisions have had the

main responsibility for a new 200 MMz instrument.

100
In spite of a number of quality control and testing problems, the new 400 MHz spectrometer has generally exceeded specifications for proton,

carbon-13, and nitrogen-15 sensitivity and resolution by about 30 percent.

During this year, proton NMR spectroscopy at 400 MHz has been applied to

high-sensitivity, high-accuracy, quantitative analysis of trace impurities

in sodium pyruvate and to studies of the stability in aqueous solution of

isotopically-labeled marker compounds for pollutant analysis. This powerful

technique has allowed complete resolution for the first time of the proton

NMR spectra of methyl 4,6-0-benzyl idene and 2,6-anhydro-a-O-al tropyranosides

,

compounds which are of interest to us as intermediates for the synthesis of

nitrogen-15 labeled amino sugars in which the nitrogen isotope has a defined

stereochemical orientation.

Another program in nitrogen-15 NMR spectroscopy uses materials in which

the nitrogen-15 isotope is either enriched or at natural abundance. Included

in this program is the exploration of nitrogen-15 NMR for characterization

of antibiotics and other biochemically important nitrogenous materials.

Carbon-13 NMR at high field has permitted increased detectability and

accuracy of quantitation for aromatic components of recycled oil and methods

have been investigated for increasing this accuracy further by removal of

variable nuclear Overhauser effects. The accuracy of quantitation is also

influenced by carbon-13 spin-lattice relaxation times and basic information

on these parameters of the recycled oils is being generated by measurements

at both high and low field strengths.

In the future, we plan to refine our competence in homonuclear, twodimensional NMR techniques and extend these techniques to measurement of

heteronucl ear interactions between protons, and carbon-13 and nitrogen-15

nuclei. Assuming the availability of certain key accessories for the

400 MHz spectrometer, we also plan to investigate the potential of nuclear

cross-polarization techniques in liquids for sensitivity enhancement in

NMR analysis. The multi-nuclear capability of the instrument will also

be extended by installation of one or more broad-band probes. This

capability will allow NMR analysis at high field of magnetically active

nuclei other than protons, carbon-13, nitrogen-15, and phosphorus-31.

Bruce Coxon, Group Leader; Robert E. Botto, Robert M. Davidson,

Diane K. Hancock

2 . Bioanalytical Techniques Group: Overview

The publication of a first NBS definitive method for the determination

of an organic chemical in serum entitled "Total Serum Cholesterol by Isotope

Dilution/Mass Spectrometry ," appeared in Clinical Chemistry [1]. This paper

is the forerunner of a series on NBS research on organic definitive methods.

The newest organic ID/MS method, for serum creatinine, is now undergoing

evaluation as a definitive method. The definitive and reference methods for

chloride in serum and lithium in serum were published as NBS-260 reports

[2,3]. These reports describe the ID/MS methods and the respective electrometric and atomic absorption methods used as reference methods for these

101
electrolytes, and provide the data and a statistical summary of the results

obtained on use of the two reference methods in groups of clinical laboratories that prove the methods' applicability.

The definitive methods developed thus far are now being applied to

certifying the values of a number of analytes in a human serum that is to

be issued in 1980 as an SRM. The organic analyses are carried out by the

joint effort of the Bioanalytical Techniques and Mass Spectrometry Groups

of this Division and the inorganic analyses are performed by the Inorganic

Analytical Research Division. The enzyme activity levels in the human serum SRM are also being measured; the data is being produced in a group

effort in a large number of clinical laboratories. We are participating

with measurements of lactate dehydrogenase activity.

We have completed work on the certification of crystalline 4-nitrophenol as an SRM. It is issued for use as a spectrophotometry standard

for assays of alkaline phosphatase activity. Our group determined the

purity of the 4-nitrophenol , and the Inorganic Analytical Research Division

cooperated by performing the spectrophotometric measurements.

A study is underway to isolate and identify the low molecular weight

organic chemical substances which, under physiological conditions, leach

from the polymeric materials that are employed with medical devices,

including the silicone polymers used in surgically implanted prostheses.

We are also undertaking to establish the effect that the substances

leached from the silicone polymeric material have on the activity of the

enzyme prolyl hydroxylase. The formation of masses of neoplastic tissue

around each implant are thought to be related to the activity of that

enzyme. Methods development for the purification of the enzyme for the

purpose of improving the activity assay is also part of the study.

Another project in our continuing research on the use of enzymes in

organic analytical chemistry involves the preparation of pyridoxamine

pyruvate transaminase and related enzymes from a bacterial source. The

enzymes are being purified for the purpose of developing analytical

procedures for the measurement of pyridoxine and pyridoxamine, as parts

of a Vitamin Be assay.

A literature survey and a research plan have been prepared on the

development needed for personal monitoring devices for toxic organic

compounds in the ambient atmosphere.

A fluoroimmunoassay for 2 ,4-dinitrophenol in water has been developed

and is now being refined to increase its sensitivity. This assay utilizes

specific rabbit-antibody , immunoglobulin molecules that are attached

covalently to solid-phase polymeric beads by coupling with a carbodiimide

reagent. 2 ,4-Dinitrophenol in the test system competes for the specific

antibody and thus reduces the amount of fluorescently labeled tracer bound

by the antibodies. Fluorescence is measured by photon counting of the bound

fractions after they have been separated from the unbound reagents. This

study is intended as a model for the potential use of rapid, small molecule,

immunoassay procedures in the analysis of aqueous environmental samples.

1Q2
The need to provide the base for ensuring accuracy in the analysis of

biological samples fin particular, analytes in serum and other body fluids)

prompted our development of definitive methods for a number of organic

analytes. Many such methods are needed, and we plan to continue our development of these methods in 1981. Current high-priority analytes include

creatinine, digoxin, and thyroxine.

Biological reagents can provide a novel means for determining analytes

in non-biological samples. In 1981, we expect to continue to explore such

possibilities through further development of immunochemical methods and

through assays employing enzymes.

References

[1] Cohen, A., Hertz, H. S., Mandel , J., Paule, R. C., Schaffer, R.,

Sniegoski, L. T., Sun, T., Welch, M. J., and White V, E., Total

Serum Cholesterol by Isotope Dilution/Mass Spectrometry: A

Candidate Definitive Method, Clin. Chem. 26 (7), 854-860 (1980).

[2] Velapoldi, R. A., Paule, R. C., Schaffer, R. , Mandel, J.,

Murphy, T. J., and Gramlich, J. W. , A Reference Method for the

Determination of Chloride in Serum, NBS Special Publication

260-67 (1979).

[3] Velapoldi, R. A., Paule, R. C., Schaffer, R., Mandel, J.,

Machlan, L. A., Garner, E. L., and Rains, T. C., A Reference

Method for the Determination of Lithium in Serum, NBS Special

Publication 260-69 [1980).

Robert Schaffer, Group Leader; Alex Cohen, Alexander J. Fatiadi,

Barbara F. Howell, Dennis J. Reeder, Pieter VanDerLijn

3. Electrochemistry Group: Overview

The recently initiated [competence building) program in organic electrochemistry is progressing well in the directions originally proposed for

this research effort, i.e., spectroelectrochemistry, automation, and

chemical modification of electrodes. During the second year of this

program, the organic electrochemistry group has reached full staffing.

Most of the major pieces of essential instrumentation have been acquired,

although a variety of important ancillary instruments are still needed to

permit maximum effectiveness in achieving our planned research goals.

In the area of spectroelectrochemistry, the setting up of the vidicon

optical multichannel analyzer system has been completed, and evaluation of

the system using the well-characterized compound, o-tolidine, has demonstrated that the performance of the system is excellent for studies of this

type. Using an optically transparent thin-layer cell with a gold minigrid

working electrode, it was possible to obtain the formal potential and

stoichiometry of the o-tolidine from the spectroelectrochemical data. The

values obtained showed excellent agreement with literature data obtained

103
by rapid scanning spectrometers. However, the vidicon system is more

sensitive than scanning spectrometers which will become important in

future research into transient redox reactions.

The computer-controlled electrochemical system (CCES) has been con- structed and most of the necessary software written to permit a diversity

of excitation waveforms, data manipulations, and graphic displays to be

performed. A commercial potentiostat has been incorporated into the CCES

in order to evaluate its performance. To improve the operational characteristics of the CCES, the analog/digital data conversion system was located

external to the computer mainframe and a direct memory access was designed

and is being constructed. A specially designed cell for studies using

rapidly changing excitation signals has also been constructed and is in the

process of evaluation.

Research into the development of improved electrochemical detectors

for liquid chromatography has resulted in a high-sensitivity, dualelectrode cell which will minimize noise and drift problems caused by traces

of residual oxygen. A comparison of the dual-electrode with a conventional

electrochemical detector for selected organic and organometal 1 ic analytes

demonstrated the superior sensitivity of the new approach. Further studies

are in progress to evaluate this detector for improved selectivity by using

modulated excitation waveforms and phase-sensitive detection.

Research into the chemical modification of electrodes is underway in

two studies. In one, several nickel (II) Schiff-base complexes have been

synthesized and will be attached to a platinum electrode via a polyphenylene oxide film. It is expected that these bound complexes will undergo

electrocatalysis with aliphatic and aromatic halogenated hydrocarbons.

If this type of modified electrode is stable, it will be developed as a selective detector for liquid chromatography.

The other type of modified electrode is a semiconductor, n-type Ti02>

which when irradiated by UV light is capable of oxidizing carboxylic acids

at very low potentials thereby avoiding interfering redox processes. By means of this photo-Kolbe reaction, it is planned to develop a photoelectrochemical high-performance liquid chromatography detector for organic

acids. A specific application of this system will be the certification of

valproic acid in serum as an SRM.

The potassium salt of croconate violet was investigated using cyclic

voltammetry and spectroel ectrochemistry . From these experiments, plus

digital simulation of the data, it was possible to calculate thermodynamic and kinetic parameters and to demonstrate that the redox site was independent of the chromophoric center in this molecule.

Plans for next year include the initiation of a surface enhanced Raman

spectroelectrochemical research project. Using the optical multichannel

analyzer system with a Reticon Cphotodiode array) detector, the electrode

reaction mechanisms of substituted pyridines on silver and mercury electrodes will be investigated by surface enhanced Raman spectroscopy (SERS).

104
SERS IS expected to yield new insights into electrode mechanisms by providing molecular spectra of adsorbed reactants, intermediates and products.

The major development in instrumentation will be the construction of

a microprocessor which will be interfaced to several instruments to assist

in data acquisition, experiTnental control, data reduction, and display.

In addition, potentiostats are being constructed to provide individual

group members with dedicated electrochemical control of their experiments.

Beyond this, our plans call for continued research on the projects

noted above, e.g., (1) application of the CCES to chemical systems of

interest such as the croconate compounds, C2) study of the spectroelectrochemical behavior of ceruloplasmin, (3) further improvements in

electrochemical LC detectors, and [4) elucidation of the electrochemical

behavior of various types of chemically modified electrodes. By these

studies, we expect to develop the competences in organic electrochemistry

which can be effectively utilized in the future to address analytical

needs of the Center.

Richard A. Durst, Group Leader; Elmo A. Blubaugh, Kathryn A. Bunding,

Lawrence M. Doane, Mary L. Fultz, William A. MacCrehan, William T. Yap

4. Liquid Chromatography Group: Overview

Research in the group continues to be focused on the analysis of

polynuclear aromatic hydrocarbons [PAH's), phenols and nitrogen heterocyclic compounds which are important in the energy and environmental area,

and anticonvulsant drugs and peptides which are important in the clinical

and biomedical areas.

During the past year, we have utilized several procedures that were

developed in previous years in the certification of two new Standard

Reference Materials, SRM 1580 (Organics in Shale Oil) and SRM 1644

(Generator Columns for Polynuclear Aromatic Hydrocarbons in Water). A

high-performance liquid chromatographic (HPLC) fractionation procedure

was used for isolating five phenols from a shale oil matrix prior to

final quantitation by gas chromatography/mass spectrometry (GC/MS). A

sequential HPLC procedure was used for the determination of six PAH's and

two nitrogen heterocyclic compounds in SRM 1580. In addition, we have

used sequential HPLC procedures in the measurement of several PAH's,

nitrogen heterocycl ics , and amino-PAH's in a petroleum crude oil and a solvent refined coal as well as tissue, air particulate, and sediment

extracts. We also devoted some effort to the determination of polychlorinated biphenyls in waste and recycled oils.

The dynamic coupled column HPLC procedure developed in our group and

used in the certification of the anthracene, benz(a}anthracene, and

benzoCa) pyrene generator columns, is now also being utilized to determine

ambient temperature vapor pressures and heats of sublimation of several

PAH's.

1Q5
In the biomedical area, the strategies developed in previous years

are being used in the analysis of a candidate Angiotensin I SRM. In addition, we have used these strategies for comparative analyses of

Luteinizing Releasing Hormone (LRH), somatostatin, endorphins, and the

hypothalmic peptide Substance P from several commercial sources. Alkaline rearrangement products of NAD have been isolated by preparative HPLC

for NMR analysis. From these experiments, we have obtained sufficient

data to propose an alternate reaction mechanism to the currently accepted

one for the rearrangement.

Three independent HPLC procedures have been developed and are being

evaluated for certification of valproic acid in human serum. This assay

is particularly difficult because valproic acid is very volatile, does

not contain an ultraviolet (UV) chromophore, and is not readily resolved

from protein and other serum components on reverse-phase columns. The

three procedures are; (1) a multi-dimensional procedure where the

valproic acid is isolated from the serum on a precolumn and selectively

eluted onto an analytical column for separation and quantitation with

detection at 195 nm; (2) a method based on the extraction and derivatization of the valproic acid so that it can be monitored at 254 nm; and

(3) analysis of underivatized serum extracts by LC-MS.

Some other noteworthy research efforts during the past year include:

the development and evaluation of a quenchofluorometric detection system

for chlorinated pesticides, and PAH's containing the fluoranthene moiety;

investigation of the retention behavior of PAH's on both polymeric and

monomeric HPLC bonded phases. In this context, it was observed that the

retention of both parent and alkylated PAH can be predicted from the length

to breadth ratio of the molecule; assessment of the stability of several

phenols in distilled and industrial effluent waters under various conditions of storage; and direct quantitative LC-MS analysis of several phenols

in shale oil and solvent refined coal.

In 1981, we plan to continue our present efforts in the environmental

and biomedical areas and begin to develop expertise in food and nutritional

analysis. In this context, we are sponsoring with FDA and USDA a Workshop

on Reference Materials for Organic Nutrient Measurement. Specific research

plans for next year include interfacing an optical multichannel analyzer

(OMA) to a spectrofluorimeter in order to obtain fluorescence spectra of

HPLC column effluents on-the-fly. Necessary optical modifications to the

spectrofluorimeter have been made this year in preparation for this work.

This project will be carried out in conjunction with the Organic Spectroscopy Group. In addition, we plan to develop a competence in chemical

derivattzation which will allow us to better measure compounds that do

not have strong UV chromophores

.

Willie E. May, Group Leader; Jeanice M. Brown- T^iomas

,

Richard G. Christensen, Walter F. Kline, Sam A. Margolis,

William J. Sonnefeld, Patricia A. White, Stephen A. Wise

106
5, Mass Spectrometry Group: Overview

The major research emphasis for the Mass Spectrometry Group Is 1n the

development of mass spectrometrlc methods for the accurate quantitation of

Individual compounds In complex mixtures, development of hlgh-resolutlon

mass spectrometrlc techniques for the analysis of high molecular weight

compounds, and continued development of a liquid chromatography-mass

spectrometry fLC-MS) Interface for the analysis of non-volatile analytes.

Work during the past year has been concentrated In the environmental and

clinical areas. During the past year, quantitative gas chromatography-mass

spectrometry CGC-MS) methods have been developed and applied to the determination of Individual analytes In complex samples such as shale oil,

solvent refined coal, energy process effluents, and human serum. Several

phenols and polynuclear aromatic hydrocarbons have been quantitated in a shale oil sample and the shale oil has been released as SRM 1580.

Isotope dilution definitive methods have been developed for the quantitation of a number of human serum constituents including cholesterol,

glucose, and uric acid. The methods result in the determination of the

analytes with a precision of better than ±0.5 percent relative standard

deviation (RSD). A human serum Standard Reference Material, SRM 909, is

expected to be released in 1980.

The high-resolution mass spectrometry facility is now fully operational. Accurate mass measurements above m/z 1000 are very important for

the analyses of non-volatile compounds. Silver sulfonates have been used

successfully for high mass calibration of high-resolution field desorption

mass spectra to m/z 1400. High-resolution mass spectra of several polypeptides have been obtained using field desorption with photoplate

detection and silver salts for mass calibration.

Work has continued this year on development and refinement of an LC-MS interface. A patent has been obtained for an LC-MS interface

employing continuous sample preconcentration. Considerable refinements

have been made In the design of the probe; these changes allow the use of

aqueous mobile phases and allow Introduction of an atomizer gas which can

be either inert or a chemical ionization reagent gas. The LC-MS system

has been used In the quantitative analysis of individual compounds in

shale oil and solvent refined coal. Valproic acid, an anticonvulsant

drug, has been quantitated in human serum with the LC-MS system operating

in the chemical ionization mode using selected ion monitoring. Spectra

of non-volatile compounds, such as adenosine, have been obtained using

aqueous chromatographic mobile phases.

The chemical and Isotopic purities of about thirty deuterated com- pounds have been evaluated for use as Internal standards In the proposed

Environmental Protection Agency CE^PA) "Master Analytical Scheme" for

priority pollutant analysis. Solutions of these internal standard

mixtures have been supplied to EPA. Tw of the Internal standards, a deuterated naphthalenesulfonlc acid and deuterated r[-dodecyl phosphate, were not available commercially and were synthesized at NBS.

107
Research planned for the coming year Includes: continuation of the

ongoing environmental projects with extension to new matrices and the

Investigation of negative ion chemical ionization for quantitation using

recently acquired instrumentation; new isotope dilution definitive methods

for urea and creatinine and the investigation of improvements to the

instrumentation used; continued refinement and the beginning of application of high-resolution field desorption mass spectrometry; and changes

in the NBS developed liquid chromatography/mass spectrometry system to

improve its performance with polar compounds.

The competence-building program on "Analysis of Ionization Mechanisms

and Ion Structures" will be initiated in 1981. Specifically, two research

programs will be started in the area of probing the structure of organic

ions. The first project will involve laser induced metastable ion generation as a selective probe for molecular structure. The second project

will involve collisional activation of ions with reactive gases as a means of directing fragmentation.

Edward White V, Group Leader; Rafael Espinosa, Laurence R. Mil pert,

Stanley Meiselman, Kristy L. Richie, Lorna T. Sniegoski, Michael J. Welch

6. Gas Chromatography Group: Overview

The general thrust of research in the Gas Chromatography Group is

aimed at multi-dimensional chromatographic techniques for use in quantitation of individual compounds in complex organic mixtures. Also, the

possibility of utilizing combined gas chroma tography-Fourier transform

infrared tGC-FTIR) spectrometry to identify toxic organics in difficult

matrices is being pursued.

Over the last year, the group has certified three additional phenols

and two nitrogen heterocycles in the Shale Oil Standard Reference Material

(SRM 1580). The heterocyclic compounds were certified using the dual

capillary multi-dimensional GC system developed last year.

The development of an analytical method for polychlorinated biphenyls

CPCB) in recycled oils is almost complete. This has been aided by addition of a Hall conductivity detector to the group's equipment. The method

developed utilizes both high-performance liquid and gas chromatography

,

where liquid chromatography is used to remove analytical interferences

prior to gas chromatographic quantitation. The use of the Hall detector

removes the variation in detector response factors inherent in electron

capture detectors.

A proposed ethanol -in-wine SRM has been certified and the recertifications of the heptane and iso-octane SRM materials have been completed. Gas

chromatographic methods of analysis for the anticonvulsant drugs, carbamazepine and valproic acid, have been developed. In our program on the

analysis of alternate fuels, a solvent refined coal liquid and a Wilmington

petroleum crude oil have been analyzed for phenols and dibenzothiophene.

108
A new on-column capillary injector (modeled after that published by

K. Grob [1]) has been designed, built, and tested. Several new refinements

have been added to our multi-dimensional GC capability. These include a new, low dead-volume, pneumatic switching valve, a dual capillary capability, and a more efficient oven configuration. The GC-FTIR system is now operational and the capillary interfacing is proceeding at a rapid

rate; we can currently obtain good quality infrared spectra on many

samples. A capillary, on-column injection technique has been devised for

the analysis of trace levels of volatile halocarbons in drinking water.

Also, standards to be used by the Environmental Protection Agency's

"Master Analytical Scheme" for water analysis have been prepared and

their stability has been monitored.

During the coming year, the group plans to increase its capability

in the area of multi-dimensional chromatography, including back-flushing

and cyclic techniques so that more complex quantitations can be performed.

Also, the FTIR-capillary system will be expanded and automated to make

it easier to collect, manipulate, and store data from lengthy GC-FTIR

chromatograms. In the future, we plan to acquire a microwave detection

system for one of our gas chromatographs and subsequently be able to

perform both organic and inorganic multi-element analyses on gas

chromatographabl e samples.

Reference

[1] Grob, K., Journal of High Resolution Chromatography and

Chemical Communications, ^ 45 (1979).

Stephen N. Chesler, Group Leader; Sharon L. Bowie, Delmo P. Enagonio,

Franklin R. Guenther, Reenie M. Parris

109
B. Selected Technical Accomplishments

(Organic Analytical Research Division)

1 . Isotope Dilution/Mass Spectrometry Definitive Method Developed for

Creatinine in Serum

Elevation in serum creatinine signifies impaired kidney function.

Its measurement is a useful diagnostic test since the relative creatinine

concentration is fairly constant in individuals. Patients having kidney

transplants are routinely monitored for creatinine for evidence of transplant failure. The commonly used method for measuring creatinine levels

is based on the color produced by its reaction with alkaline picric acid.

Unfortunately, a number of keto-acids found in serum also form colored

products under these conditions and that elevates the apparent creatinine

level. Methods to obviate this problem, e.g., sample pretreatment by

chromatography, have given results that are also controversial. An

isotope dilution/mass spectrometry (ID/MS) method already in the literature has not clarified the issue because the results it gives are imprecise and some possible sources of bias in the method were not investigated. Our ID/MS method is designed to overcome these uncertainties.

We synthesized creatinine labeled with three deuterium atoms in the

methyl group that is attached to one of the ring-nitrogen atoms. This

labeling avoids a potential isotope effect that could arise by use of

creatinine having nitrogen-15 labeling (^^N-labeled creatinine was used

in the published method). A derivative of creatinine, making it volatile, is needed for the gas chromatography step in the ID/MS method. In our method the creatinine is condensed with acetylacetone, and the product

is then esterified to produce the known compound N-(4, 6-dimethyl -2-

pyrimidinyl )sarcosine, for GC/MS analysis. (In the published method,

creatinine is treated with propylene oxide and then with tri fl uoroacetic

anhydride to give a product whose exact structure is not known.)

The wet-chemical steps in our ID/MS method entail mixing a quantity

of the creatinine-d 3 with an aliquot of a sample, separating the fraction

containing the labeled and unlabeled creatinine from the sample by use of

HPLC, and converting the creatinine into the sarcosine derivative. The mass spectrometric measurement to obtain the ratio of labeled and unlabeled molecules is initiated by injecting a small volume of the derivative

mixture into a gas chromatograph that is equipped with a capillary column

to effect a further purification, and then by directing the creatinine

derivative into the mass spectrometer. Multiple ion monitoring (one ion

each for the labeled and unlabeled forms of the creatinine derivative) is

used to measure the ratio of the forms over the entire GC peak.

Known mixtures containing different proportions of SRM creatinine

and the creatinine-d 3 are converted into the creatinine derivative for use as calibration mixtures. Two of these mixtures, having ratios of

labeled and unlabeled creatinine closely bracketing the ratio found for

the sample, are measured in sequence with the sample and in a second

run are remeasured in the reverse sequence. Interpolation of the data

no
provides the desired ratio. The concentration of the unlabeled creatinine

in the sample is calculated from the ratio and from the known amount of

labeled creatinine initially added.

The method has thus far been tested with only two samples. Each was analyzed as three independent replicates. The precision of the results

('^>0.36 CV) is deemed adequate for a definitive method. By use of chemical ionization instead of electron impact ionization for generating ions,

thereby obtaining other principal ions from which to measure the ratio of

the forms of creatinine, we could find no evidence of interfering ions.

Their presence would have led to different ratios being found. Additional serum samples must now be analyzed to assemble the data needed to establish

the precision obtainable for the method and the absence of systematic

error.

A. Cohen, H.' S. Hertz, R. Schaffer, L. T. Sniegoski, P. VanDerLijn,

M. J. Welch, E. White V

2. Human Serum Reference Material (SRM 909)

This SRM for clinical chemistry is certified for its concentrations

of clinically important organic and inorganic analytes. NBS has used

definitive methods because such methods afford analyte values that are highly precise and free from significant bias; thus, they are accepted

as most accurate. In addition, the certificate accompanying the SRM

will provide state-of-the-art values for the activities of several of

the enzymes that are also present in the serum. These values are based

on results obtained by several expert groups from clinical laboratories

who jointly selected and used an optimized enzyme activity method for

measuring each enzyme.

The freeze-dried serum is in the form of small, bead-like particles,

quantities of which had been weighed into the vials. The uniformity in

vial-to-vial content of freeze-dried serum was measured, by performing

differential refractometry with a very sensitive instrument, on 170 vials

of the serum after reconstitution. The between-vial variability was found

to be within acceptable limits for a calibration reference material,

according to Approved Standard ASC-2 of the National Committee for Clinical

Laboratory Standards; i.e., the variability did not exceed ±1 percent of

the mean value in more than 5 percent of the vials. Because a variability

of that magnitude would lead to unacceptably high levels of uncertainty

for definitive method value, that consequence was obviated by weighing the

quantity of freeze-dried serum in each vial during the process of recon- stituting the serum. The certified values and their uncertainties, which

apply to 99 percent of the vials of the SRM with 95 percent confidence, are applicable when the entire content of each vial is reconstituted and are given per gram of freeze-dried serum .

Thus, users of the SRM will have to measure the mass of freeze-dried

serum in each vial of SRM if they are to benefit from the accuracy of the

certified values. A simple procedure for weighing the contents of dry serum in each vial is described in the certificate.

Ill
If vials of the SRM are reconstituted without weighing the freezedried serum, the certificate provides the mean concentration values and

the resultant wider limits of uncertainty that apply to 95 percent of the

vials with 95 percent confidence.

The SRM is being issued even though the values for all the analytes

and enzyme activities that are eventually to be reported have not been

determined. Values will be sent to the users of the SRM automatically

as soon as the work is completed for each additional analyte and enzyme

activi ty

.

Definitive method values based on isotope dilution/mass spectrometry

are certified for glucose and uric acid. Values for cholesterol and urea are in process. The creatinine value will be determined as soon as the

ongoing work to develop an ID/MS method for creatinine is completed.

None of the enzyme activity values are ready to be reported at the time

of the present writing (August 1980).

A. Cohen, R. G. Christensen, H. S. Hertz, D. J. Reeder, R. Schaffer,

L. T. Sniegoski, M. J. Welch, E. White V

3. FI uoroimmunoassay Procedure Developed for Dinitrophenol s in Water

Detection of trace amounts of the toxic pollutant 2,4-dinitrophenol

in water is an analytical problem that presents many challenges to the

analytical chemist. Laboratory investigations have shown that gas

chromatography and high-performance liquid chromatography, while suited

for analytical determinations of most of the toxic pollutants, are not as efficient in the separation and identification of the ni trophenol s . The

development of an immunochemical procedure for detection and quantitation

of dini trophenol s in water has been the focus of efforts during 1980.

Development of suitable reagents for the assay entailed the preparation of a suitable material (immunogen) to be injected into rabbits for

production of antibodies. Highly purified bovine albumin was combined

with dinitrophenol and characterized. The immunogen most successful in

eliciting antibodies had 23 dini trophenyl groups per mole of albumin.

The antiserum was produced under contract by a commercial supplier who

injected rabbits with the prepared immunogen and bled them periodically

for determining antibody development. A procedure that used double

diffusion of antiserum versus the immunogen in a gel matrix was the

preferred method for following antibody development.

Specific immunoglobulins (_IgG) were separated from serum by use of

an ion-exchange gel preparation. Purity of the IgG was ascertained by use of cellulose acetate strip electrophoresis. The IgG was then

covalently bound to solid-phase polymeric beads by coupling with a carbodiimide reagent.

The antibody, thus attached to the beads, was able to bind 2,4-dinitrophenol. However, in order to use this capability in a quantitative

assay, a compound that could act as a tracer needed to be synthesized.

112
In order to be suitable, the tracer requires dual functionality, i.e.,

dinitrophenol reactivity as well as physical properties that can be

measured, such as radioactivity or fluorescence. A dinitrophenolated

fluorescent tracer with dichlorotriazinylaminofluorescein as the fluorescent moiety is currently being synthesized. Alternatively, the use of

other fluorescein derivatives, such as fluorescein isothiocyanate, are being considered as substrates for dinitrophenylation.

The first tracer that we have had success in using in a quantitative

competitive assay is a double-labeled rabbit albumin molecule to which

both dinitrophenol groups and fluorescein isothiocyanate chromophores are covalently bound. In the competitive assay, the tracer and free dinitrophenol compete for antibody sites on the specific antibody solid-phase

beads. Maximum sensitivity of the assay is determined by the amount of

antibody-bound beads added, the quantity of the competing tracer in the

mixture, and the time and temperature of assay incubation.

The solid-phase beads are separated by centrifugation, washed, and

then counted in an instrument designed for photon counting, of fluorescence at 510 nm with excitation at 490 nm. Binding curves are then

generated from the resulting counts. Typical specific counts range from

30,000 to 600,000 in a two-second counting period, with background and

control counts ranging from 15,000 to 25,000. Plots of the binding

versus the amount of dinitrophenol added are linear over two orders of

magnitude. Work is now focused on extending the sensitivity range of

the assay.

By combining the specificity of the assay with capabilities of

concentrating dinitrophenols with an affinity "accumulator" column,

detection of ultra-trace amounts of dinitrophenol pollutants in water

should be achieved. This will be of importance in the monitoring of

industrial effluents.

P. Cooper, D. J. Reeder, R. Schaffer

4. Development of Methods for Determination of the Aromatic Carbon

Content of Recycled Oils by High- Field ^^C NMR Spectroscopy

Installation of the high- field NMR facility of the National Measurement Laboratory facilitated work on characterization of recycled oils as

a result of the higher sensitivity and availability of more versatile

pulse programming.

In efforts to improve the [\j|vir method for measurement of aromatic

carbon content, the use of carbon disulfide as a phase reference has been

investigated. Carbon disulfide shows a narrow, well-defined ^^C resonance

(see figure 13) and its addition to solutions of the oils in chloroform-^

- tetramethylsilane has allowed more accurate phasing of the low lying

aromatic ^^C envelope which increases the accuracy of integration.

113
114

Figure

13.

i3c

NMR

spectrum

of

a

solution

of

recycled

oil

sample

BC71

70

in

chloroform-d

at

100.6

MHz.

Tetramethylsilane

and

carbon

disulfide

have

been

added

as

chemical

shift

and

phase

references,

respectively,

and

the

nuclear

Overhauser

effect

(MOE)

has

been

removed

by

a

combination

of

inverse

gating

of

the

decouplinq

frequencv

fo

and

the
Since variable nuclear Overhauser effects (NOE) can degrade the

accuracy of quantitative measurements of quaternary aromatic carbon

resonances, studies of two methods for removal of the NOE have been made:

(a) inverse gating of the proton decoupling frequency and (b) the use of

organic complexes of gadolinium as highly potent, paramagnetic relaxation

reagents. Because removal of the NOE causes loss of sensitivity by up

to a factor of three (resulting in a nine- fold increase in acquisition

time), these studies have been conducted with the new, high-field superconducting NMR spectrometer, operating at 100.6 MHz for and at

400 MHz for protons. The spectra obtained show increased resolution

in the aliphatic region and greatly increased resolution and definition

of the weak signals in the aromatic region.

The solubility in chloroform of three organic complexes of gadolinium has been tested and the following order of solubilities found:

gadolinium (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate)3

> gadolinium (acetylacetonate )3 > gadolinium (trifluoroacetylacetonate) 3

. On this basis, the octanedionate complex Gd(fod )3 was selected for the

initial studies. For example, NMR analysis of oil sample BC7170 at

high field using a combination of the inverse gating and Gd(fod )3

techniques yielded an aromatic carbon content of about 7 percent (see

figure 13).

Because of the influence of spin-lattice relaxation times (T^) on quantitation, measurements of these parameters have been conducted at

both low and high field (22.6 and 100.6 MHz, respectively). A stacked

plot of recovery of the magnetization of the aliphatic nuclei at

22.6 MHz is shown in figure 14, and the Ti values computed by a twoparameter exponential fit in Table 6. The Ti values of the nuclei

represented by the 24 most intense resonances in the aliphatic carbon

region range between 0.2 and 0.4 seconds, and the Tj values measured for

five bands in the aromatic carbon region range between 0.15 and 1.3

seconds and are given in Table 7. The broad hump at 139.9 ppm (Ti 1.3

sec) was assigned on the basis of its chemical shift to quaternary

aromatic nuclei and the sharper bands at 129.0-125.7 ppm to protonated aromatic nuclei. The shorter Ti values for the latter group

are consistent with more effective dipolar relocation by the protons

attached directly to these nuclei.

115
T’s

BY

FAST

INVERSION

RECOVERY

OIL

BASESTOCK

5183, I

116

Figure

14.

Measurement

of

the

spin-lattice

relaxation

times

(Ij)

of

oil

basestock

5183

by

the

fast

inversion

recovery

method.

The

figure

shows a

stacked

plot

of

the

recovery

of

the

magnetization

of

the

aliphatic

nuclei

for a

series

of

interpulse

delays

D1

ranging

from

0.001-60

sec.
Table 6 . Carbon-13 Spin-Lattice Relaxation

Carbons in Oils Basestock #5183.

Times (Ti ) of A1 i phatic

Chemical Percent

Shift Intensity Ti Assignment

(ppm) Ccorrected) (sec)

78.3 36.0

76.9 31 .0 CDCI 3 75.5 41.7

37.6 3.4 0.23 A

37.3 3.2 0.24 L 34.6 1.7 0.27 I 33.9 1.6 0.21 P 33.6 1.9 0.20 H 33.3 2.2 0.25 A

33.0 3.8 0.34 T

32.6 1.9 0.32 I 32.5 2.0 0.33 C

32.2 5.6 0.81

31 .6 1.6 0.20 C

30.3 6.0 0.30 A

29.9 23.3 0.37 R 29.6 8.4 0.48 B 28.8 2.2 0.22 0

28.1 2.6 0.35 N 27.7 1.8 0.24 S

27.3 3.1 0.27

27.0 2.5 0.24

26.6 1.9 0.21

24.7 1.9 0.23

22.9 7.4 1.31

19.8 3.9 0.68

14.2 6.0 2.39

0 11 .06 Me 4 Si

117
Table 7. Carbon-13 Spin-Lattice Relaxation Times CTj) of Aromatic

Carbons in Oil Basestock #5183.

Chemical

(ppm)

Shift Average T^

(sec)

Assignment

139.9 1.30 Quaternary Aromatic 13c

129.0 0.28

128.2 0.28

Protonated Aromatic 13c

126.6 0.15

125.7 0.23

For measurements of Tj values at high field (100.6 MHz), the

values were computed using a three-parameter exponential fit. Under

these conditions, the ^^C Ti values of the aliphatic carbons ranged

between 0.5 and 2.0 seconds, and the values for the protonated aromatic

carbons ranged betv^een 0.2 and 0.6 seconds. These relaxation times are expected to assist interpretation of the quantitative results and the

design of new experiments.

B. Coxon

5. Research on Two-Dimensional Proton NMR Spectroscopy and Its

Application to SRM D-Glucose

Implementation of two-dimensional, Fourier transform NMR spectroscopy on the new superconducting spectrometer (operating at 400 MHz for

protons) has indicated the tremendous potential of the method for the

structural and quantitative analysis of organic materials that are of

interest to NBS.

The method has been applied initially to a solution of Q-glucose in

methyl sul foxtde-^6 , a type of solution that was used at MBS ten years ago

for the analysis and characterization of this clinical SRM by continuous

wave, proton NMR spectroscopy at 90 MHz. Three novel types of proton NMR

spectra have been measured for D-glucose at 400 MHz: (1) two-dimensional

stacked plots (data matrix 8K x~128) in which chemical shift and coupling

constant information is separated and displayed in two different dimensions (see figure 15); (_2) a proton decoupled, proton NMR spectrum

obtained by rotation and projection of the data matrix onto the chemical

shift axis (see figure 16); and (3) a series of cross sections ('J'-

spectra) of the two-dimensional NMR spectrum in which coupling constant

information is displayed independently of chemical shifts.

118
II II II O o r- I— «—

II II II II It — CVJ *-< Qi 3 I/) s: s: cx: iJ- 3 QCVJ o O o o o

1— o O o o o

LT> o O o o o • • • • • • o\ o in o in in

CT» *;T [ r-‘ 1

CT>

'

II II II II II II

, CVJ X >- X >-

U. Lu o o o o

'll

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'•M'I;:

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,

‘J-'.-'iu. 'StiSS'

Jl liill

. ••:••.. -sy/jj,. j.,;;:. ' O'!

: , 0>, O

O.

..M rr>' r I. 'll .1 I rW ;i

' • " '

'.i'i

r rr-- --^'Wiku.'' ’;>•••!! :--i' .i- ••X'-v.-ii"'

Wiilil'

llilfi

j|li.i: i-.ji. J

• . •

\^£>r

H;,

119

CHEMICAL

SHIFT

Figure

15.

Two-dimensional

proton

NMR

spectrum

ofa

solution

of

Q-glucose

(SRM

917)

in

methyl

sulfoxide-dc

at

400

MHz.
GLUCOSE

2D

Projection

120

Figure

16.

'Proton

decoupled'

proton

NMR

spectrum

ofa

solution

of

D-glucose

(SRM

917)

in

methyl

sulfoxide-^e

at

400

MHz,

obtained

by

projection

of

the

two-dimensional

spectrum.
Proton NMR spectroscopy of Q-glucose at 400 MHz has revealed a wealth of spin coupling information that was not available from our earlier studies at 90 MHz. However, even in the one-dimensional proton

NMR spectrum at 400 MHz, there is still some overlap of the proton signals of the complex twelve-spin system formed by the seven ring protons

and five hydroxyl protons of Q-glucose. The undesirable effects of this

overlap are neatly removed in the two-dimensional method since the 'J'-

spectra are displayed in separated form. Since the method involves a spin-echo technique, refocusing of the magnetization vector removes

the effects of magnetic field inhomogeneity, with the result that the

'J'-spectra show resolution that is superior to that available in the

one-dimensional spectrum, even after substantial resolution enhancement

by Gaussian filtering. This has allowed more accurate measurements of

several of the proton-proton coupling constants of Q-glucose and also

the unequivocal detection of several small couplings that have not been

observed previously.

The proton decoupled, proton NMR spectrum (see figure 16) of

Q-glucose (obtained as the projection of the two-dimensional spectrum)

displays twelve clearly separated singlets which indicate the great

analytical potential of the method. The content of 3-Q-glucose in the

SRM is indicated by the presence of a small singlet in the projection

spectrum at low field.

B. Coxon

6 . Analysis of Sodium Pyruvate and Its Impurities by Proton NMR

Spectroscopy at 400 MHz

The high sensitivity and large dynamic range of the 400 MHz spectrometer has facilitated development of a new method for quantitative analysis

of sodium pyruvate which has been used to complete certification of the

SRM. For example, this allowed ^50 percent solutions of the sodium

pyruvate in 9:1 v/v H20 :D20 to be analyzed effectively either with or without presaturation of the water resonance by narrow-band irradiation

of the water protons prior to data acquisition. For the purpose of

identifying impurities in the pyruvate, a solvent having a low D 2 O content

(necessary for fieldrfrequency stabilization) is desirable, so as to

minimize the deuterium exchange of labile CH protons (for example, the

CH2 group in pyruvate oligomers). However, similar results were obtained

by the use of 9:1 H2 O: (CD 3 ) 2 S 0 , a solvent mixture which avoids the problems of deuterium exchange.

The high sensitivity of the spectrometer allows data acquisition for

the analysis to be completed rapidly (7 minutes or less) before significant dimerization of the pyruvate has occurred. The results obtained for

solutions at pH 6 (the natural pH of the SRM) by integration of methyl

signals (see figure 17) are shown in Table 8 . The methanol impurity in

the pyruvate appears to be an integral part of the crystal structure since

it is not readily removed by drying. The final column of Table 8 shows

the increased proportion of dimer produced by subjection of the pyruvate

121
ch3

100

Scans

122

Figure

17.

Proton

NMR

spectrum

ofa

solution

of

sodium

pyruvate

(SRM

910)

in

9:1

v/v

H20:D20

at

400

MHz.
Table

8.

Quantitative

Analysis

of

Sodium

Pyruvate

by

Proton

NMR

Spectroscopy

at

400

MHz.

CO T3 S- <U N 3

+J 3:

O

«0 S 3=

C\J f- <n 00 CM

•o o uo . • « • o

<a CTi 1

iCT> CO

CM o z

S- +J S- I—I ro O«4- o •o CO

CO <U CT>

•r—S_ +J O roX

w

C •!- <U K£> IT) CO CM

rO CO 3 • . • • O) I— r** o o S M- fO O >

O)

ro

00 CO CM (/) CO • . . • O) o o >-

cn

CO CM CO CO • • • . <u o o >-

cr»

Lf) rv CM CO CM • . . • <D r“ P'- o o >-

LO 00 CM CM • . . . o P>. o o z;

CTi

00 in in CM

r“— • . . . o

r— p«. o o CTi

LD CO CM • • • • o o o z <n

s-(U

OJ •r—

4-> •o

ns o <L) s- 03

+-> T3 O) 10

03 >1 +-> CO > ns 03

+-> 3 > &- c i- 03 3 Q.

<u >> +J S- o Q. c Q. ns >> c 3 o > Q. »o CO Q. O 3 fO .£Z E +-> S- S- +J O o 03 <o 03 CM CJ O- o. :n

123
to the conditions of NMR spectroscopy at 22.6 MHz, during which, for

the purpose of proton decoupling, the solution is broad-band irradiated

at 90 MHz for 15 hours. Analysis by proton NMR is much faster and avoids

any problem due to RF heating of the sample.

The non-equivalence of the methylene protons of the dimer I (see

figure 18) is striking at 400 MHz and an AB analysis yielded the parameters 51.3 Hz and 18.1 Hz. This research has been done in

'AB 'AB

conjunction with the development of improved separations of pyruvate

dimer by HPLC.

B. Coxon, S. A. Margolis

7. Analysis of Boat Conformations of a-D-Al tropyranoside Derivatives

by Interpretation of Highly Coupled Proton NMR Spectra

Bicyclic derivatives of the rare sugar altrose are of interest as intermediates in the synthesis of ^^N labeled amino-sugars in which the

^^N isotope has a well-defined stereochemical orientation. These isotopically labeled derivatives are being used in basic studies of the angular

dependence of ^^N-proton coupling constants, a relationship which is

expected to facilitate the NMR analysis of the aminoglycoside antibiotics.

The availability of a 400 MHz proton NMR spectrometer has allowed, for

the first time, complete dispersion of the proton spectra of a number of

a-Q-al tropyranoside derivatives that had previously resisted complete

analysis at such lower field strengths as 100 and 220 MHz.

Complete analysis of the proton NMR spectrum (figure 19) of methyl

4, 6-^- benzyl idene- 3-deoxy- 3- phthalimido-a-D-al tropyranoside (I ) at

400 MHz has revealed vicinal proton-proton’coupl ing constants that are substantially different from those measured previously for many other

a-D-al tropyranoside derivatives. The first order coupling constants for

I (see Table 9) indicate that its pyranose ring adopts the ^B^(Q) boat

conformation in which the substituents at C-1, C-2, C-3, C-4, and C-5

all have the equatorial orientation. By contrast, the values of the

vicinal proton coupling constants for methyl 3-amino-4,6-0-benzylidene3-deoxy-a-Q-al tropyranoside (II) and methyl 4,6-O^benzyl idene-2-deoxy2-phthal imido-a-Q-al tropyranoside (III) confirm that these derivatives

adopt the ‘^^i(D) conformation. Evidently, the conformational locking

effect of the phthalimido substituent is not sufficient to cause III to

adopt a boat conformation. However, in the *^^

1 ( 0 ) conformation of I,

this effect is combined with a 1,3-diaxial interaction between the

phthalimido and methoxyl substituents, with the result that I favors a boat conformation. Stabilization of this boat conformation is possible

by hydrogen bonding between the hydroxyl and carbonyl groups. This is

supported by the observation of less extreme coupling constants for the

2-^-acetyl and 2-^-benzoyl derivatives (IV and V, respectively) of I (see Table 9). An alternative class of boat conformations is represented

by methyl 2,6-anhydro-a-Q-al tropyranosides , in which the 2,6-anhydro ring

forces adoption of a boat conformation [^B^(D)] in which all substituents

124
1

,020

Scans

S-dJ IOI N N X X

CO• . LO -5—

55 CO ^ < I 125 L

3.27

2.39

1.38 60

Figure

18.

400

MHz

proton

NHR

spectrum

of

an

aqueous

solution

(9:1

v/v

H20:D,0)

of

pyruvate

di

separated

from

sodium

pyruvate

(SRM

910)

by

HPLC.
10

mg, 8

Scans

126

k

Figure

19.

Proton

NMR

spectrum

ofa

solution

of

methyl

4,6-^-benzyl

idene-3-deoxy-3-phthal

imidoal

tropyranoside

(I)

in

chloroform-^

at

400

MHz.
Table

9.

Proton

Coupling

Constants(Hz)

of

Methyl

4,6-0-Benzyl

idene-a-D-Al

tropyranoside

Derivatives

at

400

MHz. I1 1

fO CM 00 '5d‘ A . • • « . <U o o CD o O KO r— 1—

•s

ra cnO 00 o CM

VO • • . • . CTt o CD o o LO r—

'-D

O) VO 1

CM o 1

•s « • • • • to to lO to LO

to o LO , O . • • • . o <J^ CD o o“

CM CD CO LO

A * • . • . CO CT> CO CO 00 00

•T3

CO CM n . • . • • C\1 CO CM CM to LO

'S

CO , <Ti 1 I 1 1 • 1 1 1 1 O 1 1 1 ’-3

CM 00 o 'd' VO . • . * • r— VO r_ CM *!3’ o +-> CO CO C_) CO CO C r— r— CSl r— r—

CL) C_J

OO

O > Q Q CO Q o O O Q C_) o

"o

O CO O

O o

T3 -o

a •r“ •r* •1“ £ E E

•r- CSJ •r— •p" ro r— IC 3= r— r*“ o; fO -21 O CO (O .c JZ Jd

4-> +J O. Q- Q. o

T3E

•r—

U

N

CM c HI r— c CO

q; o o (0 o O .£=

+-> O.

(U>

•t—

-)-> fC> h—1

1—1 (—( > > H-4 1—1

f—1

s- 1—1

<u o

127
are axtal . Proton NMR at 400 MHz has now made conformational analysis of

this unique bicyclooctane-like ring system feasible for the first time.

The methyl 2 ,6-anhydro-a-D-al tropyranosides have been studied in the form

of the 3,4-diol (VIII), its di-£-acetyl derivative (VI), and the recently

synthesized 3,4-anhydro derivative (VII). The proton NMR spectrum of the

latter 2,6:3,4-dianhydro derivative (VII) at 400 MHz is extraordinarily

complex due to the presence of a large number of long-range coupling con- stants (see figure 20a and Table 10). The many small long-range coupling

constants (<1 Hz) were detected by resolution enhancement techniques

using Gaussian filtering of a 64K data set and were confirmed by com- puterized simulation of the seven-spin system (figure 20b) and by

homonuclear decoupling. The large number of long-range coupling constants

of VII may be attributed to enhanced transmission of spin coupling

information through the electron delocalization or multiple pathways of

the epoxide (3,4-anhydro) ring.

We plan to use the dianhydride (VII) for the synthesis of ^^N

labeled amino-sugars in which the ^^N and proton nuclei have the rare

dihedral angles of either 0° or 120°.

B. Coxon, M. L. Luzarraga, R. C. Reynolds
Figure

20.

Proton

NMR

spectra

of

a

solution

of

methyl

2,6:3,4-dianhydro-a-D-al

tropyranoside

(VII)

in

chloroform-^

at

400

MHz:

(a)

experimental

spectrum

obtained

by

resolution

enhancement

of

a

4000

scan,

64K

data

set

by

Gaussian

multiplication,

and

(b)

simulated

spectrum

from

seven-spin

computation.
Table

10.

Proton

Coupling

Constants(Hz)

of

Methyl

2,6-Anhydro-a-D-Al

tropyranoside

Derivatives

at

400

MHz. o . • . CO 1 m 1 o o n 1 . 1 f— r— Sj- 1 o 1

CO o m CO 1 CO 1 . • . f. 1 . 1 o o CO 1 o 1 •-3

CO *o

cn 00 CM c CO 1 CD 1 . • . o A 1 . 1 CM CVJ CO QQ CM 1 o 1 "-3 COA

CM CO CD 1 CO 1 . • . O) 0* 1 . 1 CM . CO CM CT CM 1 o 1 C

fC ai CO 1 cn LT> CO CTi . • 1 c • . • CO 1 o CM O o O

_I • o o r>. 1 in . • . A 1 « • CO CM r— 1 o o

CM oo CO CO <£) . • . 0% • • • CM CsJ CM r— r— r— r—

•D zm o m

O o CM +-> o CM

IT) CO o C lO CO

O o . • (U o r— • • • • o 00 > • • O CO

ro o r— 1

CO

O

f— C-) C_) o o o O a c/^ o o Q o o Oo a

<c

a 'd' <c o o LU o cc o LU o O Q 1—1

1—1 X X o o a a. o. c LlJ o CO <c LU

Q o o a: o O

(U>

-t-> (-H )—t 1—1

fO t—1

1—( —1 > 1—1 1—1 > > 1—1

t—1 > 1—4 •r“ > (—1 > S- > <u o

130

k
1

8. Laser Polarimetry and Its Application to Recertification of Sucrose

SRM (SRH 17c)

Due to instrumental advances and more accurate moisture determination techniques of recent years, industrial and academic groups have

found needs for more precise and accurate certified optical rotation

values. This resulted in the recertification of the sucrose Standard

Reference Material, SRM 17c.

To accomplish this, we determined the optical rotatory dispersion of

standard quartz plates and SRM sucrose solutions using the high-accuracy

polarimeter designed and built at NBS. Argon, helium-cadmium, heliumneon, and dye lasers, as well as a mercury arc were used as light sources

in these studies. Our experimental results at different wavelengths were

in agreement with results calculated from empirical formulas for the

wavelength dependence of the optical rotations. Extensive determinations

of optical rotation values were made for both quartz plates and SRM

sucrose. Solutions using both the mercury arc with filter pack (546 nm)

and the helium-neon laser (632.8 nm) showed excellent agreement and

further verified the validity of the empirically derived rotatory dispersion equations. Thus, the optical rotations of the SRM sucrose and quartz

plates at a given wavelength may be calculated from the optical rotation

determined at 632.8 nm. In addition, use of the laser in place of the

mercury arc reduces the measurement time by an order of magnitude. We,

therefore, recommend the use of lasers as light sources in general and,

more specifically, the helium-neon laser as a light source in routine

polarimetry because its stability, increased intensity, and monochromaticity result in more precise and accurate measurements.

In addition to certifying the optical rotation, we are completing

certification of the physical parameters of density and refractive index

for the SRM. These data, along with certified values for purity will be

of great interest to industry.

R. V. Bostelman, A. L. Cummings, D. K. Hancock, S. A. Margolis,

D. J. Reeder, L. T. Sniegoski, R. A. Velapoldi

9. Certification of Generator Columns for Polynuclear Aromatic

Hydrocarbons in Water (SRM 1644)

In the fall of 1975, the National Bureau of Standards (NBS) and the

Environmental Protection Agency (EPA) jointly sponsored a series of workshops entitled "Standards and Reference Materials for Environmental

Analysis Associated with Energy Development". The objective of these

workshops was to obtain input from experts in the field of the methodology

and certified standards needed for the accurate analysis of environmental

samples associated with the production of alternate fuels.

At the conclusion of these workshops, a number of Standard Reference

Materials (SRM's) were recommended by the participants for NBS consideration. One of the SRM's recommended was a polynuclear aromatic hydrocarbon

131
CPAH) in a water matrix. Although many PAH's have demonstrated mutagenic

properties, this SPvM was given a low priority because of the presumed

difficulties associated with the preparation and stabilization of such a material

.

Shortly thereafter, we discovered that saturated solutions of PAH

could be produced by simply passing distilled water through a column

packed with glass beads coated with the compound of interest. The

aqueous solubility of a compound is a well-defined thermodynamic quantity. Therefore, saturated aqueous solutions produced by these

"generator columns" may also be defined as standard solutions at a given temperature.

Generator columns for anthracene, benz(a)anthracene, and benzo(a)-

pyrene constitute SRM 1644. The columns were prepared commercially and are currently being certified by two independent analytical techniques.

The first technique involves quantitative extraction of the PAH from

the aqueous stream by an "extractor column" packed with Cis bonded phase, use of an acetonitrile-water eluent to transfer components from the

extractor column to an analytical Cjs column for separation of the

analyte from non-analyte components, and detection of the analyte by

absorbance at 254 nm.

The second technique uses a "standard addition" technique for "on

stream" analysis. The effluent from the generator column is mixed with

PAH standards dissolved in acetonitrile, and the resultant PAH in the

mixed solvent determined by fluorescence.

Preliminary data from the certification are given in Table 11.

Upon completion of the certification process, one equation will be

derived from a compilation of the data obtained from the two methods

which will allow the user to interpolate the certified concentration

between 10 ®C and 30 ®C. This SRM will be certified and available by

October 1980.

132

k
Table 11. Preliminary Results of Anaalysis Using Two Techniques for

Generator Column Aqueous Effluents.

Anthracene

Temperature Concentration Cppb)

(°C) Technique 1 Technique 2

30 58.8 59.6

25 42.8 42.9

20 31 .1 30.9

15 22.6 22.2

BenzCalanthracene

0 Temperature Concentration Cppb)

(°C) Technique 1 Technique 2

30 12.3 13.0

25 8.86 9.32

20 ^

6.37 6.67

15 4.58 4.78

Benzo (.a) pyrene

Temperature Concentration (ppb)

(”C) Technique 1 Technique 2

30 2.28 2.26

25 1.62 1 .60

20 1.14 1.14

15 0.80 0.81

10 0.57 0.58

J. M. Brown-Thomas , W. E. May, W. J. Sonnefeld, R. A. Velapoldi,

P. A. White

133
10. First Natural Matrix Trace Organic $RM Issued for Shale Oil

(SRM 1580)

The current energy demand and the inevitable depletion of our petroleum reserves has resulted in a national program with a goal to insure an adequate supply of energy having minimum impact on public health and the

environment. The conversion of coal to gaseous or liquid fuels and the

utilization of oil shale and tar sands are some of the energy sources that appear promising because of their relative abundance. To evaluate

the potential environmental consequence of these activities, it will be

necessary to analyze a feedstock, process streams, plant effluents, and

final products for tra.ce element and organic compound content. The

results of these analyses cannot be assessed adequately without knowledge

of the accuracy of the analytical techniques used to obtain the data.

We have in the past conducted several collaborative studies aimed at

assessing the accuracy of data obtained from trace organic analytical

methodologies. The results of a recent study involving the determination

of specified phenols, polynuclear aromatic hydrocarbons, and N-heterocyclics in a shale oil sample by several laboratories revealed large

systematic biases among laboratories. One method for enhancing the

accuracy of analytical measurements is the use of suitable quality assurance standards or Standard Reference Materials (SRM's). However, until

now, SRM's for environmental trace organic analyses were nonexistent due

to the lack of analytical methodologies necessary for certification.

Over the past few years, analytical methodologies have been developed and used to certify the first natural matrix SRM for trace-level

organic constituents. Organics in Shale Oil, SRM 1580. The quantitation

of individual compounds in the complex shale oil matrix necessitated the

use of mul ti-dimensional chromatographic procedures, i.e., gas or liquid

chromatography on two columns of different selectivity and/or extremely

selective detection methods.

Three different methods of sample preparation were used prior to

analysis: simple dilution of the shale oil with methylene chloride

(or other suitable solvent); acid/base extraction to isolate acidic,

basic, and neutral components; and a high-performance liquid chromatographic fractionation. Two of the following techniques were employed to

determine the certified values for the organic compounds in shale oil:

capillary gas chromatography (GC), gas chromatography/mass spectrometry

(GC/MS) with single ion monitoring for selective detection, and highperformance liquid chromatography (HPLC) with selective fluorescence

detection. All GC/MS analyses used the standard addition method for

quantitation. The GC and HPLC analyses employed either internal standard, external standard, or standard addition methods. The excellent

comparabil ity of the values determined by these different analytical

methods is illustrated in Table 12. Table 13 lists values for other

compounds determined by only one technique. These values will appear on the SRM certificate for information only. The methods developed for the

certification of this SRM are applicable to the determination of similar

compounds in other complex natural matrices. Standard Reference Material

134
Independent

Techniques.

taCO 00 CO 00 CO CJ5 in 1— CO C55 00 00 00 00 I— 00 00 co

•I

+-> in CM in

<d

i- oi M

1— OO CD CM

O I— COO in ^ COCM C55 CO CM

CM 1— o c oi

<U 3 O —

c

+1 +1 +1 +1 +1 +1 +1 +1

CX5O

+1 +1 +1 +1 +1 +1 +1 +1 +1 +1 1— CO o O CO o cr> CO CM ^ 1— CO CM CM CO <d- CO 00 in CO CJ CM CM 1— CM CO LO o o 1— O 00 00

CO CO 00 CO

a(Uc

s-

(U

+-> (U oo

0)

<o

C/0

(d QJ a 3

•1“ cr

>0 c

I— x:

(d o c (U < hC/O

cj a.

CD oc

C/O o a. CD 3C«/1

O o o. O 3=

C/5

CJ Q. C3 3:

oo CJ

<_) Q_

CD 33

00o o

C3O

OO

CJ CJ

CUCD'

C/5 s:

C_) CJ

CD CD

CJ

CD

fdco

COc

O) a

+j o3 Q.

s: zc

CO T3c3O

Q.O

CJUc

rd05

c. o c C

C SZ

O o o o

£= •r" '1— •r- •f— O +-> 4-> 4-> c c c c sz O o O O o o o o o Id Id Id Id

Id •r- •r" •r" •r~ •f" s- s- s- sS- (U -•-> +J -M !-> -!-> +-> +-> +-> Id 3 U O O O o X X X X

£3. cr (U cu 05 0) 05 UJ UJ UJ UJ

0) T- •1-5 •1^ •o •1-5 •1-5 i- c c c c C c 05 05 05 05 o. sz •—1 —t

•—t

1—11—1

to lO 10 to

u Id Id Id Id <U O) +-> +-> +-> 4-> +J CO oo CO 03 1— 1— o o o O CJ — CL <U CJ (U o <u o (U o 05 CJ O -o CJ -O o -a •o CJ E S 1 t. -1 s > S 1 S 1 —1 'r— _1 -1- —I -i- •1- —i

Id <r- CL •r- CL •r- Q. •r- Q. •1- Q- CL

a CL o CLa

O CL

ooQ 3: C3 3:

Q 3: C3 3:Q 3: DZ <C DZ < 3C < C DZ

CM 1

05 1

o C c

05 05 1

r— 05 05 .c o

jQ c C CL c

Id 05 05 05 f— ^r— 1— •o s- S- C >) 3

sz >> >) 05 .£= cr 3 CL CL JZ o o ^ 

+J 05 05

N

CL Id l 05 1 c SZ o E c E Id 05 05 1

to •r" 05

O o O s- r—

C o 05 -o J3

CJ

NN o 05 sz S- 1 1 SZ C 3 C. S- 05 o cn CD

05 05 (U >, 1 A J3 JO M- CL CL CL o CM in

135

number

of

ampoules

analyzed.
Table 13. Summary of Results for Organic Compounds in Shale Oil

Determined by One Technique.

Compound

Sample Preparation

Techni que

Analytical

Technique Concentration

(yq/q)

benzo(k)fl uoranthene HPLC HPLC 13

phenanthridi ne HPLC HPLC 45

m-cresol Acid/Base Extraction GC 330

p-cresol Acid/Base Extraction GC 270

2 ,4-dimenthyl phenol Acid/Base Extraction GC 380

2,5-dimethyl phenol Acid/Base Extraction GC 320

2 ,5,6-trimethyl phenol HPLC GC/MS 360

2, 4, 6- trimethyl phenol HPLC GC/MS 120

1580, Organics in Shale Oil, is intended primarily for evaluating the

reliability of analytical methods used for the determination of trace

level polynuclear aromatic hydrocarbons, phenols, and nitrogen heterocyclic compounds in shale oil, coal-derived liquids, or petroleum products.

In addition, this SRM may be used as a surrogate standard for any complex

environmental extract containing classes of compounds for which the SRM

is certified.

J. M. Brown-Thomas , S. N. Chesler, F. R. Guenther, H. S. Hertz,

L. R. Hilpert, P. L. Konash, W. E. May, R. M. Parris, K. L. Richie,

S. A. Wise

1 1 . Synthesis, Isotopic and Purity Analyses, and Preparation of Solutions

of Stable Isotope Labeled Marker Compounds for Priority Pollutant

Analysis

A "Master Analytical Scheme" being developed for the Environmental

Protection Agency by the Research Triangle Institute and Gulf South

Research Institute' is intended to allow qualitative and quantitative

analysis of organic chemicals in water by gas chromatography/mass

spectrometry. The "Master Analytical Scheme" requires the use of internal standards to be developed by NBS. The standards each consist of seven to eleven deuterated compounds in a solvent. Three different

mixtures for "purgeable", "extractable", and "intractable" organic

compounds, each at two concentration levels (ranging from 0.25 yg/L to

2500 yg/L per component), are needed.

136
Of the 25 deuterated compounds required, two, 2-naphthalenesulfon1c

actd-d 7 and dodecyl phosphate-d 2 s, were synthesized at NBS because they were

not commercially available. The reaction sequences used are as follows:

2-Naphthalenesulfonic Acid-d^

Dodecyl Phosphate-d

2 g

(CgHcO-POCl 'i 003(002)^100 pyridine

' 0O3(0O2)iiOP(OOgH5)2

H,/Pt 2

HOAc

’ C03(002)iiOP(OH)2

All dehydrated compounds were checked for chemical purity by mass spectrometry and either gas or liquid chromatography, and for isotopic

purity by mass spectrometry.

Since some of the compounds were potentially unstable when stored in

mixtures, several test mixtures similar to the internal standards, but of

undeuterated compounds in deuterated solvents, were prepared. These were

subjected to conditions to accelerate aging, and examined by nuclear

magnetic resonance spectrometry. Although some decomposition was observed,

the rates were such that properly stored mixtures are expected to be usable

for the required several months of evaluation of the "Master Analytical

Scheme".

Approximately 600 individual sealed vials of the various internal

standard mixtures were prepared, and the 400 required for initial tests

of the "Master Analytical Scheme" have been delivered. The remaining

vials have been retained at NBS for stability tests, which are in progress.

S. N. Chesler, B. Coxon, P. Konash, W. E. May, R. M. Parris,

L. T. Sniegoski, M. J. Welch, E. White V
12. Evaluation of a Spectroel ectrochemical System Using ^-Tolidine

A wide range of spectroscopic instrumentation has been used in

conjunction with optically transparent electrodes in performing spectroel ectrochemi cal experiments. The development of rapid-scanning spectrophotometers has permitted the entire spectrum of an absorbing species at

an electrode to be obtained sufficiently fast to allow the extraction of

useful kinetic and mechanistic information. To date, the rapid-scanning

spectrophotometers used have been based on a motor-driven oscillating

mirror. As an advance in this field, a silicon intensified target

detector was selected as a state-of-the-art detector for our optical

system. The light passing through the optically transparent thin-layer

electrode is focused on the entrance slit of a grating polychromator

.

The dispersed spectrum falls on the vidicon, a matrix of discrete sensors which are interrogated electronically to generate spectral information.

This type of system eliminates the problems associated with mechanically

scanned spectra, and additionally, offers greater signal -to-noise ratios

than rapid-scanning systems because of continuous integration of the

signal by the vidicon.

After completion of the vidicon optical multichannel analyzer installation, the system was evaluated using the well-characterized compound,

^-tolidine. A gol d-mini grid optically transparent thin-layer electrode

served as the working electrode in the spectroel ectrochemical cell. A

potentiostat was used to control the potential of the working electrode.

In the thin-layer electrode, the potential applied to the working electrode determines the ratio of oxidized to reduced species for the entire

solution. In the optically transparent cell, the concentration ratio is

spectrally monitored for the absorbing species (figure 21). The formal

reduction potential and stoichiometry of electron transfer of the

absorbing species is precisely calculated from the spectral information

obtained at various applied potentials. Values obtained for o^-tolidine

from solution concentrations ranging from 2.8 mmol/L to 0.01 mmol/L

gave excellent agreement with literature data obtained by rapid-scanning

spectrometers. The vidicon proved capable of detecting changes of less

than 0.002 absorbance unit, showing it to be more sensitive than the

rapid-scanning spectrometer.

The spectroel ectrochemtstry system will be used to study the redox

properties of ceruloplasmin, a serum copper-transport protein. The thinlayer spectroel ectrochemical technique is well suited to the study of

biological molecules with redox centers surrounded by a protein matrix.

Since such centers often exchange electrons poorly with an electrode,

a mediator-ti trant molecule which transports electrons between the

electrode and biological molecule can be added to the test solution or bound to the electrode. Redox information can then be obtained by

monitoring the chromophore spectrum of the protein.

M. L. Fultz

XX 138
1 X

hCDz

LJ

_J

LiJ >

X

Figure

21.

Spectra

of

^-tolidine,

0.2

mmol/L

in

0.5

mol/L

acetic

acid,

1.0

mol/L

perchloric

acid.

A)

fully

oxidized,

+0.80V;

B)

+0.68V;

C)

+0.64V;

D)

+0.63V;

E)

+0.62V;

F)

+0.60V;

G)

+0.58V;

H)

fully

reduced,

+0.40V.

All

potentials

vs.

Ag/AgCl

reference

electrode.
13. Development of a System for Computer-Controlled Rapid Electrochemical Measurements

Applications of rapid electrochemical measurements have increased

from their original use in quantitative single-drop polarography to such

scan-rate-sensitive areas as fast Fourier transform voltammetry and

electrochemical detection in high-pressure liquid chromatography. A

computer-controlled electrochemical system (CCES) enhances the implementation of such rapid electrochemical experiments by providing

experimental flexibility through software control and by providing

precise signal timing. The CCES consists of a Z80 central processing

unit, 64 K random access memory, and 240 K dual drive disk memory. An

I/O interface has been built to connect the CCES with a commercial

potentiostat and provides the digital/analog conversion for the rapid

electrochemical experiments. Construction of the CCES has been completed

and is undergoing testing in conjunction with a commercial potentiostat.

The scan rates of the CCES are as fast as any digital system developed,

capable of a staircase potential scan rate of 5 volts/second for a one millivolt step height and of 2 volts/second for a similar step height in

the differential pulse mode. The CCES has been programmed to signal

av'erage in real time. This is acheived, however, at the expense of

erasing the individual scan records and at a slight reduction in scan

rate. We have also incorporated a graphics monitor that displays the

response function with respect to the applied working electrode potential

in real time. It is, therefore, possible to determine immediately

whether the experiment is proceeding properly. Previously, the data had

to be graphed on a rather slow plotter before it could be evaluated.

The rate at which the potential range of an electrochemical experiment can be scanned and still be an accurate representation of the

applied potential is determined by the cell time constant. Because the

time constant is determined by the series combination of uncompensated

resistance between the working and reference electrodes and the doublelayer capacitance of the working electrode, we have constructed an electrochemical cell which minimizes the inter-electrode separation by

the use of a pseudo-reference electrode and by using a working electrode

of minimal surface area.

The CCES has a decided advantage over commercial electrochemical

systems in its increased flexibility and speed. Combined with the lowtime-constant cell, the CCES should be a valuable tool in determining

fast electrode kinetics.

L. M. Doane

140
14. Development of a High-Sensitivity Dual-El ectrode Detector for

Liquid Chromatography

Reductive electrochemical detection in liquid chromatography (LC)

is potentially a very powerful measurement technique in the determination

of trace organic pollutants by virtue of its sensitivity and selectivity.

However, for the best sensitivity, oxygen exclusion is required. This

makes the technique cumbersome to use and has restricted its application.

A new approach for reductive LC detection that eliminates the need

for complete oxygen exclusion has been developed. A two-electrode,

thin-layer cell is used in a manner conceptually similar to a ring-disc

system. Two closely spaced electrodes are poised at different potentials.

The first electrode encountered by the flowing electrolyte is held at a potential sufficiently negative to reduce the analyte. The second

detector electrode is held at a potential sufficiently positive to

reoxidize the generated species and also to avoid the reduction of oxygen.

The low residual current at this potential assures a low background

noise, upon which the analytical current is easily measured with high

sensitivity.

The best analytical response is obtained for analytes that either

are reversibly reduced or that have chemical follow-up reactions that

generate easily oxidized products. The reductive/oxidative behavior of

three important industrial/environmental pol lutants--nitrobenzene, dichlone, and tributyl tin--have been studied by reverse pulse voltammetry.

The sensitivity and linearity of the dual electrode technique has

been evaluated by comparison to direct reductive detection. Two chromatograms with equal concentrations are pictured in figure 22. The baseline

noise of direct reductive detection without use of an inert atmosphere

box is apparent (upper figure). The lower chromatogram shows the very

low baseline noise of the dual electrode approach achieved with a minimum

of difficulty.

Current experiments involve the evaluation of the technique's

selectivity by application to the measurement of organic analytes in

environmental samples. Also, investigation is in progress on the use of

modulated waveforms and phase selective detection to improve selectivity.

W. A. MacCrehan

15. Estimation of Thermodynamic and Kinetic Data from Spectroel ectrochemical Studies Using Digital Simulations

Croconate compounds, a class of pseudo-oxocarbons , are interesting

from both the electrochemical and spectroscopic points of view. These

compounds, which are highly colored in their various forms, exhibit very

rich electrochemical behavior during cyclic voltammetric studies. We have

continued the study of the electrochemical reactions of the potassium

141
Oxidation at + 0.08 V

(Second Electrode)

1 nA

<§)-NOi

CiS

O

- 2.3 nA j

Offset rV, , , ,

I 4 8 121620

Inject 20^iL Minutes

of 10'* moi/l

Figure 22. Different Reductive Detection Modes. Conditions: Analytes--

1.0 X 10'^ mol/L of nitrobenzene and dichlone; Solvent--60

percent Me 0H/H 20 , 0.1 mol/L NH 4OAC pH 5.2 at 1.0 mL/minute;

Column--Whatman Partisil PXS 5 ym. Upper figure--direct reductive detection at - 0.8 V without enclosure of the LC in an inert atmosphere box. Lower figure--dual electrode detection,

-0.8 V on generator electrode, +0.08 V on detector electrode.

142
salt of croconate violet. Cyclic vol tammetry, done with rotating ringdisc electrodes, showed a reversible wave when scanned between +0.2V to

+0.8V, with respect to the SCE, on glassy carbon electrodes. The experimental cyclic voltammogram was fitted, by non-linear regression, with

the theoretical curve for a simple reversible electrode reaction. This

gives an E® of +0.57V and a diffusion coefficient of about 0.3 x 10”^

cm^/second. However, the experimental value for the separation of the

cathodic and anodic peaks (75 mV) is significantly larger than the

theoretical value of 57 mV for this case. We tried the simple reversible

scheme first because of the relative ease of doing a regression calculation for this case and because the current can be expressed explicitly

as a function of the potential. For more complex cases, we had to use numerical simulation to obtain theoretical curves. For instance, in the case of a chemical reaction following the electrode reaction, the peak

separation and also the shift in the position of the peaks are shown to

be dependent both on the equilibrium constant and on the ratio of the

potential scan rate to the chemical reaction rate. We are now exploring

the possibility of using these correlations in the determination of the

mechanism and the kinetic parameters.

Preliminary experiments performed in the spectroelectrochemical

thin-layer gold-minigrid cell showed only minor changes in the spectrum

of croconate violet after the application of potentials ranging from

+0.8V to -0.3V, indicating differences in the redox and chromophore

centers of the molecule. We intend to study this effect further.

Theoretical working curves for various electrochemical processes

were computed since they are important aids in the interpretation and

elucidation of the kinetics and mechanisms of the electrochemical reactions. For example, figure 23 shows the ratio of the charges transferred

during the forward and backward steps in double potential step chronocoulometry as a function of the duration of Step 1 for different values

of the rate constant for the homogeneous chemical reaction following the

electrode reaction. Figure 24 illustrates the numerical simulation of

the process

Ox + ne~ i Red ^ Z

in a thin-layer spectroelectrochemical cell. Here the logarithm of the

absorbance is shown as a function of time for cases where the extinction

coefficient of Z is ten times that the reduced species. This simulation

is needed to determine the feasibility of using the optically transparent

cell to obtain kinetic information for electrochemical reactions (in

contrast to the usual equilibrium case).

E. A. Blubaugh, Jr., M. L. Fultz, W. T. Yap

143
AN0DIC

CHflRGE/CflTHODIC

CHARGE

0.00

0.10

0.20

0.30

0.40

0.60

0.60

0.70

0.80

-2.00 -1.50 .00 -0.50 0.00 0-50

1.00 -0.50

LOG SORT T

Figure 23. Theoretical working curves for the ratio of anodic charge to

cathodic charge as a function of log square root of time.

Where A through E are the working curves obtained for

increasing magnitude of the rate constant.

144

0.00

O.IO

0.20

0.30

0.40

0.50

0.60

0.70

0.80
91

8

00 * 0

^“ Oe'*'o- 09*0- 06'd- 0 Z‘ l- os* l- aONd0«0S8b Q01

08* I- 01 OVZ145

Figure

24.

Numerical

simulation

of

the

absorbance-time

behavior

of

a

chemically

reactive,

electrogenerated

intermediate.

Red.

The

various

E-E°

(millivolts)

values,

represent

the

difference

between

E

applied

and

the

formal

redox

potential.

The

E-E°

value

determines

the

[0X]/[Red]

value.
16. Method Developed for Determination of Ambient Temperature Vapor

Pressures of Polynuclear Aromatic Hydrocarbons

The feasibility of developing a Standard Reference Material for

organic compounds in air is being investigated. A gas-saturation technique is being used to produce a saturated vapor solution of an organic

compound at its thermodynamic equilibrium vapor pressure. The vapor is

cryogenically trapped and then analyzed by coupled-column high-performance liquid chromatography.

The gas saturation method for the determination of vapor pressures

dates back to 1845. However, due to the lack of sufficiently sensitive

analytical techniques, this method has not been extensively used until

recently. M. M. Cliath and W. F. Spencer [1], in a series of experiments, utilized the method to study desorption isotherms of pesticides.

P. Pella [2] coupled a gas-saturator to a gas dilution system to produce

a calibration system for exploring vapor detectors. W. E. May [3] used

the dynamic-coupled-column HPLC technique to determine the vapor pressure

of naphthalene. Comparison with published data showed that a systematic

error was present in this work.

This study has been concerned with eliminating the systematic errors discovered earlier and extending the technique to vapor-phase studies of

the larger polynuclear aromatic hydrocarbons. The dynamic-coupled-column

HPLC system has been modified to include dual 6-port valves which allow

for purging of the collection assembly by an inert gas. The techniques

of column conditioning used for the water SRM generator columns have been

applied to this work in order to properly remove any impurities from the

starting material. The system is designed to permit continuous flow

through all channels so as to eliminate sorption effects. Thus, the

system is dynamic in nature. The generator columns and all connecting

flow lines are constantly submerged in an isothermal bath. The vapor is

concentrated on either an octadecyl silane-packed column (C-18) or via a cold trap assembly. The initial work has used an anthracene generator

column. The concentration at 25 °C has been determined as 60.2 ng/L with

a precision of 1.4 percent relative.

Studies of the dependence of the flow rate upon the vapor density

have shown that the vapor density remains constant for flow rates below

14 cm^/min.

Initial temperature studies (Table 14) have shown excellent agreement with extrapolated data obtained by other techniques.

Future work will include studies of several columns containing

varying concentrations of anthracene-coated Si02- The effects due to

the presence of other compounds and that due to the water vapor concen- tration will also be studied. Finally, a systematic check will also be

used to determine if any systematic errors are present.

146
Table 14. Preliminary Determination of the Anthracene

Vapor Pressures as a Function of Temperature.

Temperature

(“C)

Temperature

{°K) Pressure torr x 10^

15.3 288.5 2.68

2.57

2.75

20.4 293.6 4.51

4.71

4.59

25.0 298.2 6.29

6.39

6.19

30.1 303.3 11 .4

11.6

11.1

34.9 308.1 20.3

19.9

19.4

As soon as the technique has been completely verified, it will be

used to obtain the vapor pressure curves at ambient temperature for a series of polycyclic aromatic compounds. This data is presently available only by extrapolation of data obtained at higher temperatures.

Further applications will involve the use of the generator columns

for calibration of high-volume atmospheric sampling systems.

References

[1] Spencer, W. F. and Cliath, M. M., Environ. Sci . Technol . 3,

670 (1969).

[2] Pella, P. A., Anal. Chem. 48, 1632 (1976).

[3] May, W. E., Annual Report 1978, Center for Analytical

Chemistry, National Measurement Laboratory, to NAS-NRC

Evaluation Panel, 141 (1978).

W. E. May, W. J. Sonnefeld

147
17. Combined LC/MS Techniques for Direct Quantitative Analysis of

Individual Organic Compounds in Complex Mixtures

An interface for a conventional liquid chromatograph and a conventional mass spectrometer has been constructed which operates on the

principle of pre-concentrating a liquid stream and then admitting part of

it to the ionization region of the mass spectrometer. The selectivity of

the mass spectrometer and the reproducible behavior of the entire system

allow the direct quantitation of substances in complex mixtures.

The pre-concentration is accomplished by allowing the effluent from

the liquid chromatograph to flow down a heated wire. The evaporation of

solvent has yielded up to a 20-fold enrichment of analyte, and it is

believed that 100-fold enrichment is feasible.

The flow into the mass spectrometer is controlled by a small needle

valve built into the tip of the inlet tube. The valve is formed by a 0.05 mm teflon film at the tip of the tube pierced by a pointed 0.1 mm

wire which passes through the bore of the tube. Flow rate into the mass spectrometer can be controlled in the range of 0-20 yL/minute. Since all

of the pressure drop occurs at the high vacuum end of the tube, boiling

within the tube with consequent unstable flow is avoided.

The stability of the system is such that quantitation can be done

with external as well as internal standards. Figure 25 shows typical

chromatograms from the determination of phenol in a shale oil matrix

using external standards. The level found was 400 ± 40 ppm, a value in

good agreement with, and with precision comparable to, two other methods

requiring lengthy sample pretreatment. The direct shale oil determination by LC/MS required about 15 minutes per run.

Preliminary experiments suggest that it will be possible to quantitate valproic acid, an anticonvulsant drug, in serum utilizing direct

injections of serum in reversed-phase chromatography. Other methods of

determining the levels of this drug (which is typically 100 ppm) involve

extracting the drug and preparing derivatives, which are then analyzed

by conventional liquid or gas chromatographic techniques.

R. G. Christensen, H. S. Hertz, S. Meiselman, E. White V

18. Correlation of Liquid Chromatographic Retention Data with

Molecular Shapes for Polycyclic Aromatic Hydrocarbons

Reverse-phase liquid chromatography (LC) on chemically-bonded Cie

stationary phases is presently the most popular liquid chroamtographic

separation mode. The mechanism of separation on these C^s materials

has not been established and is a topic of much discussion and research

The study of the reverse-phase retention characteristics of polycyclic

aromatic hydrocarbons (PAH's) provides valuable information because

(1) PAH's are ideal model compounds for investigating the mechanism of

148
Ion

Intensity

UV

Absorbance

Time, minutes

Figure 25. Chromatogram of shale oil obtained during phenol quantitation.

Upper trace: ultraviolet detector recording at 254 nm. Lower

trace: single ion record at m/z 94.

149
retention due to their nonpolarity, and (_2l the separation and identification of PAH'S are of environmental interest because of the production of

PAH's during combustion of fuel and their suspected carcinogenic properties.

Reverse-phase LC on phases provides unique selectivity for the

separation of isomeric PAH's and particularly methyl-substituted PAH's.

A relationship was observed between the shape of PAH solutes, particularly the 1 ength-to-breadth ratios and the reverse-phase LC retention

on C 28 bonded phases. In nearly all cases, this ratio was successful

in predicting the LC elution order of isomeric PAH's for more than 40

unsubstituted and 40 methyl-substituted PAH's, i.e., the retention

increases with increasing 1 ength-to-breadth ratio. These ratios were

found to be particularly useful in predicting the selectivity of reversephase LC for methyl-substituted PAH's. The linear correlation for the

LC retention vs the 1 ength-to-breadth ratio for 23 methyl-substituted

isomeric benzo[£]phenanthrenes , benz[£]anthracenes , and chrysenes is

illustrated in figure 26 (correlation coefficient = 0.936).

This relationship suggests the importance of solute shape in the

LC mechanism. In GC, a similar relationship exists between shape and

retention on liquid crystal phases, suggesting the possibility of a liquid crystal effect or "ordering" of the Cis phase in LC. The retention characteristics on polymeric Cjs phases exhibit greater selectivity

and a greater correlation with the shape data than on the monomeric

phases. This observation indicates that polymeric phases may be more

"ordered" than the monomeric phases.

W. J. Bonnett, F. R. Guenther, W. E. May, S. A. Wise

19. Application of Multi-Dimensional Chromatography to Trace Organic

Compound Quantitation

A multi-dimensional gas chromatographic technique has been devised

for the analysis of single compounds in complex matrices. A simple

switching device was constructed which allows the transferring of a portion of the effluent from one capillary column to another capillary

column. Under proper conditions, this transfer can be done without the use of cryogenic trapping on the second column.

This technique was used to certify 5,6-benzoquinoline in the shale

oil SRM. An acid/base extraction scheme was used to isolate the

N-heterocycl ic containing fractions. The fraction was then concentrated

under a stream of dry nitrogen to approximately 100 yL. Two yL was then

injected onto the first column, a non-polar SE52 capillary column, to

give a boiling point separation. Subsequently, a portion of the effluent

containing the compound of interest waa transferred from the first column

to a carbowax 20M capillary column. Separation on this column is based

on polarity. The analyte was easily separated from all other compounds.

A standard addition technique was used with phenanthridine as an internal

volume corrector. This procedure was used on eight separate groups of

ampoules from the SRM lot. The final concentration was determined to be

150
4.4 i

|i

:j

!!

—I 1 h

CM

O 00 • • • ^ ^ CO I Boi

0*2 I 0

•p1

4->cn 8* 1.

O) >,

+-> O) O)

T3 ^c

lO

T3

C30)

ri. Io

u>c0 3* 1. '— to I—I (U CD <U O S- —I — +-> c

lO to

+-> E

to <u -o sz

Q. E I—I O O

•I- I—I O E N

CU E

+J O)

d) jQ E4- O)

X

OE E to O O CU

•I- «4- E

+-> CU

rd

C/1

O I— O fC

CU T- E E -P E fO +-> O E E

CJ fO SZ I—I E -P (C

fO -O I—I

CU fC

N E CU E

•I- E CU _I -Q 0* 1. VO

CM

(UEE

CD

151 ,

and

methyl

chrysenes

(•).
15.1 ± 1.2 ppm (.one standard deviation). This compares favorably with

the liquid chromatographic determination of 16.3 ± 1.8 ppm.

S. N. Chesler, F. R. Guenther

20. Development of a Procedure for the Analysis of Polychlorinated

Biphenyls in Recycled Oil

Polychlorinated biphenyl (PCB) mixtures (Aroclors) have been extensively used in this country in high-voltage electrical components. These

toxic compounds find their way into the environment when the electrical

components containing them are discarded. The Aroclor fluid physically

resembles lubricating oil and many instances have been reported where

toxic PCB's have been mistakenly added to oils being collected for

recycling purposes. It has, therefore, been necessary to develop an analytical procedure for the determination of PCB's in waste oils. PCB's are organic compounds which possess no simple chemical characteristics

which will allow them to be easily separated from a hydrocarbon matrix

such as found in lubricants. Direct determination of PCB's in waste oils

using electron capture gas chromatographic methods is not feasible due to

the large number of electron-capturing organic impurities present in this

matrix; e.g., sulfur and oxygen containing compounds, and polynuclear

aromatic hydrocarbons . Solvent extraction and normal column chromatography

were found ineffective for the removal of these interferences. We, therefore, developed a HPLC cleanup technique which removes the major interfering components. A small amount (140 yL) of oil is injected onto an aminosilane preparatory scale LC column and an appropriate volume fraction

of the eluate, containing the PCB's, is collected. This fraction has

been shown to contain very few organic compounds which acted as analytical

interferences. The PCB's are then quantitated using an SE-52 WCOT (nonpolar) column. If the sample is found to contain more than one PCB

mixture, the ratio of mixtures is determined by a matrix algebra technique

using a newly developed computer program.

The presence of PCB's at a level of 10 yg/g has been verified in a number of used and recycled oil samples obtained for testing the methodology. The type(s) of PCB mixtures present in these samples were successfully identified using standard retention data and visual pattern

recognition techniques. Mixture ratios were determined to ±20 percent

using the computer program. Since the electron capture detector normally

used in PCB analyses exhibits large variations in response factors toward

different PCB compounds, accurate quantitation has been found to be

difficult. A different type of detector is now being employed. This

detector CHall detector) operates by measuring the amount of HCl released

from the PCB's when they are reacted at high temperatures in the presence

of H 2 gas. The Hall detector does not have the limitation of the electron capture detector and simple calibration techniques can be used.

S. N. Chesler, F. R. Guenther, R. M. Parris, P. A. White

152
21 . Development of a Fourier Transform Infrared Spectrometer-Gas

Chromatograph Interface and Its Application to Pollutant

Identification

Installation of a Nicolet 7000 Fourier transform infrared (FTIR)

spectrometer was begun in September 1979, and essentially completed by

January 1980. The instrument was found to meet all design specifications

and even exceeded some, such as resolution and signal-to-noise ratio.

The instrument is being used for four distinct research and/or service

functions: high-resolution low-pressure gas work, liquid samples, liquid

chromatography, and gas chromatography.

The studies of gas chromatographic applications have progressed

through the utilization of packed column chromatography to the construction and testing of an interface for wall coated open tubular gas

chromatographic columns CWCOT), which will allow real-time FTIR analysis

of compounds eluting from the WCOT. The use of packed columns was not

pursued because they were not found to have the resolving power required

for the separation of the complex samples we wished to analyze. The WCOT

columns used in this project were chosen to maximize sample capacity of

the column, since the FTIR instrument requires 'v^lOO ng of component for

the collection of a reasonably identifiable spectrum. Also, an on-column

injector was fabricated to facilitate injection of a maximum amount of

sample onto the column without undo loss of efficiency. The first interface design consisted of a Pt/Ir tube which connected the output of the

thermal conductivity detector (TCD) to the FTIR light pipe. This interface was found to be unsuitable because too much dead volume (located

mostly in the TCD and connecting fitting) caused unacceptable peak

broadening. In addition, the Pt/Ir tube thermally trapped out and/or

reacted with all solutes boiling above 300 °C.

The present interface consists of a 50 cm length of deactivated,

methyl silicone-coated quartz capillary of 0.15 irm internal diameter.

The TCD has been bypassed and no other gas chromatographic detectors are

used. This interface is connected to a glass WCOT by use of AgCl cement;

if a quartz WCOT were used, then the last 50 cm of the capillary itself

could act as the interface. The quartz interface does not appear to

react with or retard eluting compounds and spectra have been obtained for

compounds such as methyl di benzanthracene (b.p. <500 °C). Reconstructed

gas chromatograms (from IR data) still show large losses in efficiency

over those obtained from normal gas chromatographic detectors. This loss

is most likely due to the large volume of the FTIR light pipe, and a new low volume light pipe is being procured. Even though the FTIR data does

not fully reflect the high-efficiency separations obtained on the WCOT

columns, very recognizable and identifiable spectra are being obtained

from environmental samples being analyzed (e.g., phenols in shale oil,

PCB's, etc.). This is, to a large extent, being made possible by some newly developed manipulative computer software which numerically regains

some of this lost column efficiency.

S. N. Chesler, F. R. Guenther

153
C. Outputs and Interactions

(Organic Analytical Research Division)

1 . Publications

Coxon, B. and Hough, L., Revision, by Proton, Carbon-13, and Nitrogen-15

NMR Spectroscopy, of the Structure Assigned a Bis (hexopyranosyl )-

amine Derivative, Carbohydr. Res. 73 , 47-57 (1979).

Durst, R. A., Container Materials for the Preservation of Trace Substances

in Environmental Specimens, in Monitoring Environmental Materials

and Specimen Banking , N. P. Luepke, ed., Marti nus Nyhoff Publishers,

Boston, MA, 195-202 (1979).

Hertz, H. S., Certification of Clinical and Environmental Trace Organic

Research Materials, Proc. Inter. Sym. on the Prod, and Use of Res.

Matls

.

, West Berlin (1979).

MacCrehan, W. A. and Durst, R. A., Measurement of Organometal Species in

Biological and Water Samples Using Liquid Chromatography with

Electrochemical Detection, Interagency Energy/ Environment R&D

Progress Report, EPA-600/7-79-21 1 , 63 pages (1979).

Margolis, S. A. and Schaffer, R., Development of a Standard Reference

Material for Angiotensin I, Final Report on Agreement #1-Y01-HU70042-06 (1979).

Mighell, A. D. , Hubbard, C. R. , and Cohen, A., 2- Ethoxy-1 ,7, 9-Tri ethyl -7,

9-Dihydro-l][-Purine-6,8-Dione, a Tetraethyl Derivative of Uric

Acid, Acta Cryst , B35 , 1280-1282 (1979).

Reeder, D. J., Place of Reference Materials and Reference Methods in the

Evaluation of Drug Effects, Proc. of Workshop Under the Aegis of the

Comm, of Med. Res. and Public Health of the Comm, of Eur. Communities

TT^).

Sweeting, L. M., Coxon, B., and Varma, R., Conformational Analysis of

Peracetylated Hexononitriles , Carbohydr. Res. 72 , 43-55 (1979).

Velapoldi, R. A., Paule, R. C., Schaffer, R., Mandel , J., Murphy, T. J.,

and Gramlich, J. W., Standard Reference Materials: A Reference

Material for the Determination of Chloride in Serum, NBS Special

Publication 260-67 (1979).

Wise, S. A., Mowery, R. A., Jr., and Juvet, R. S., Jr., A Universal

Detector for Liquid Chromatography: The Flame Aerosol Detector,

J. Chromatogr. Sci. 17 , 601 (1979).

Bowers, G. N., Jr., McComb, R. B., Christensen, R. G., and Schaffer, R.,

High-Purity 4-Nitrophenol : Purification, Characterization, and

Specifications for Use as a Spectrophotometric Reference Material,

Clin. Chem. 26 (6), 724-729 (1980).

154
Chesler, S. N., Guenther, F. R., and Christensen, R. G., An Electrically

Heated Sample/Injector for Use with High-Effici ency Gas Chromatographic Columns, J. High Res. Chrom. and Chrom. Comm., 351-352

(1980).

Cohen, A., Hertz, H. S., Mandel , J., Paule, R. C., Schaffer, R.,

Sniegoskt, L. T. , Sun, T. , Welch, M. J., and White V, E., Total

Serum Cholesterol by Isotope Dilution/Mass Spectrometry: A Candidate

Definitive Method, Clin. Chem. 26 (7), 854-860 (1980).

Coxon, B., Carbon-13 Nuclear Magnetic Resonance Spectroscopy of FoodRelated Disaccharides and Trisaccharides, Developments in Food

Carbohydrate-2 , C. K. Lee, ed.. Applied Science Publishers Ltd.,

Barking, England, 351-390 (1980).

Coxon, B., Fatiadi, A. J., Cohen, A., Hertz, H. S., and Schaffer, R.,

Nitrogen-15 NMR Evidence for the Structures of N-9H-Xanthen-9-yland N,N' -Di-9H-Xanthen-9-yl-Ureas , Org. Magnetic Reson. 13, 187-192

(1 980).

Coxon, B. and Reynolds, R. C., The Synthesis and NMR Spectroscopy of

Derivatives of 6-Amino-6-deoxy-D-galactose-6-^^N, Carbohydr. Res.

78, 1-16 (1980).

Farrington, J. W., Albaiges, J., Burns, K. A., Dunn, B. P., Eaton, P.,

Laseter, J. L., Parker, P. L., and Wise, S. A., Fossil Fuels,

The International Mussel Watch , National Academy of Sciences,

Washington, DC, 7-77 (198^)^

Fatiadi, A. J. , Infrared Spectra of Pectic Substances (Book Review),

Carbohydr. Res. 80, C25-C26 0980).

Fatiadi, A. J., Pseudo-Oxocarbons . Synthesis of 2,1,3-Bis-, and 1,2,3-

Tris (Dicyanomethyl ene) Croconate Salts. New Bond-Delocalized

Dianions, "Croconate Violet" and "Croconate Blue", J. Res. Nat.

Bur. Std. 85, 73-86 0980).

Fatiadi, A. J., Pseudo-Oxocarbons. Synthesis of 1,2,3-Tris (Dicyanomethylene) Croconate Salts. A New Bond-Delocalized Dianion,

Croconate Blue, J. Org. Chem. 45 , 1338-9 (1980).

Himes, V. L., Mighell, A. G., Hubbard, C. R., and Fatiadi, A. J., New

Bond-Delocalized Dianions: The Crystal Structure of 1,3-Bis (Dicyanomethyl ene) Croconate Salt, (Cn Nu 0 <^K;>‘ 2 H 90 ) , J. Res. Nat.

Bur. Std. 85, 87-97 (1980).

Howell, B. F., Kinetic Methods for Detecting Inhibitors in NADH and

NADH-Dependent Enzymes, Methods in Enzymology 66 , 55-62 (1980).

Hubbard, C. R. , Mighell, A. D., and Fatiadi, A. J., Dixanthylurea

(N,N' -di-9H-Xanthen-9-ylurea) , J. Res. Nat. Bur. Std. 85 , 205-210

(1980).

155
Margolis, S. A. and Konash, P. J., Non-Peptide Impurities in Angiotensin I and Other Commercial Peptides, J. of High Res. Chrom. and

Chrom. Comm. 3, 317-318 (1980).

May, W. E., The Solubility Behavior of Polycyclic Aromatic Hydrocarbons

in Aqueous Systems, ACS Advances in Chem. Series 185 (7), 143-192

(1980).

Wise, S. A., Chesler, S. N. , Hertz, H. S., May, W. E., Guenther, F. R.,

and Hilpert, L. R. , Determination of Trace Level Hydrocarbons in

Marine Biota, Anal. Tech, in Environ. Chem. , J. Albaiges, ed.,

Pergamon Press, 41-51 (19807.

Velapoldi, R., Paule, R., Schaffer, R., Mandel , J., Machlan, L.,

Garner, E., and Rains, T. , A Reference Method for the Determination

of Lithium in Serum, NBS Special Publication 260-69 (1980).

Brown, J. M., Wise, S. A., and May, W. E., Determination of Benzo(a)pyrene

in Recycled Oils by a Sequential HPLC Method, Inter. J. of Environ.

Anal . Chem. , in press.

Chesler, S. N., May, W. E., White, P. A., Parris, R. M., and

Guenther, F. R., Determination of Polychlorinated Biphenyls in

Waste and Lubricating Oils, Proc. of Joint Conf. on Meas. and Stds.

for Recycled Oil /Systems Perfor. and Durability , to be published

as an NBS Special Publication (1980).

Christensen, R. G., Hertz, H. S., Meiselman, S., and White V, E., A

Liquid Chromatograph/Mass Spectrometer Interface Incorporating

Continuous Sample Preconcentration, Anal. Chem. , submitted for

publication.

Durst, R. A. and Bates, R. G., Hydrogen Ion Activity, Encyclopedia of

Chem. Tech. , third edition, John Wiley & Sons, New York, in press.

Hertz, H. S., Brown, J. M., Chesler, S. N., Guenther, F. R., Hilpert,

L. R., May, W. E., Parris, R. M., and Wise, S. A., Determination of

Individual Organic Compounds in Shale Oil, Anal. Chem. , in press.

Hodgeson, J. A. and Fatiadi , A. J., A Survey of Research Needs on Personal Samplers for Toxic Organic Compounds, to be published as an NBS Special Publication (_1980).

Kaplan, A. E., Weiss, E. R., Byrne, S. T., El-Torkey, N. M., and

Margolts, S. A., The Effect of Purified NADH on the Activity of

Lactate Dehydrogenase from Control and Chemically Transformed

Cells, Nature , in press.

MacCrehan, W. A., Advantages of Differential Pulse Detection in Liquid

Chromatography and the Application to the Measurement of Organometal

Cations, Anal . Chem. , submitted for publication.

156
Schaffer, R., Velapoldi, R. A., Paule, R. C., Mandel , J., Bowers, G. N.,

Jr., Copeland, B. E., Rodgerson, D. 0., and White, J. C., Reference

Method for Determination of Serum Sodium, Clin. Chem. , in press.

Wise, S. A., Bonnett, W. J., and May, W. E., Normal- and Reverse-Phase

Liquid Chromatographic Separations of Polycyclic Aromatic Hydrocarbons, Polynuclear Aromatic Hydrocarbons: Chemistry and

Biological Effects , A. Bjorseth and A. J. Dennis, eds., Battelle

Press, Columbus, OH, in press.

Wise, S. A., Chesler, S. N., Guenther, F. R., Hertz, H. S., Hilpert, L. R.,

May, W. E., and Parris, R. M., Interlaboratory Comparison of Determinations of Trace Level Hydrocarbons in Mussels, Anal. Chem. , in

press

.

2. Talks

A. J. Fatiadi, "Synthesis of 1 ,3CDicyanomethylene)Croconate Salts.

New Bond-Delocalized Dianions: Croconate Violet and Croconate Blue,"

National Meeting of the American Chemical Society, Washington

Hilton, Washington, DC, Sept. 12, 1979.

B. Coxon, "Synthesis of Nitrogen-15 Labeled Amino Sugar Derivatives by

Addition of Phthal imide-^^N to Carbohydrate Epoxides," 178th

National Meeting of the American Chemical Society, Capitol Hilton,

Washington, DC, Sept. 13, 1979.

E. White V, "Organic Isotope Dilution Mass Spectrometry for the Definitive

Measurement of Serum Constituents," 6th Annual Meeting of the

Federation of Analytical Chemistry and Spectroscopy Societies (FACSS),

Philadelphia, PA, Sept. 17, 1979.

H. S. Hertz, "Standard Reference Materials for Clinical Analysis," 6th

Annual Meeting of the Federation of Analytical Chemistry and

Spectroscopy Societies (FACSS), Philadelphia, PA., Sept. 25, 1979.

S. A. Wise, "Normal and Reverse Phase Liquid Chromatographic Separations

of Polycyclic Aromatic Hydrocarbons," 4th International Symposium

on Polynuclear Aromatic Hydrocarbons, Battelle Columbus Laboratories,

Columbus, OH, Oct. 4, 1 979.

B. Coxon, "Nitrogen-15 NMR Spectroscopy of Amino Sugars," 31st Southeastern Regional Meeting of the American Chemical Society, Virginia

Blue Ridge Section, Roanoke, VA, Oct. 24, 1979.

R. A. Durst, "Sources of Error in Using Ion-Selective Electrodes,"

EXPOCHEM '79-, Astrohall, Houston, TX, Oct. 25, 1979.

H. S. Hertz, "Certification of Clinical and Environmental Trace Organic

RMs," International Symposium on the Production and Use of Research

Materials, Bundesanstal t fur Material prlifung, Berlin, West Germany,

Nov. 16, 1979-.

157
D. J. Reeder, "Place of Reference Material and Reference Methods in the

Evaluation of Drug Effects," Workshop Under the Aegis of the Committee of Medical Research and Public Health (CRM) of the Commission of

European Communities, Abbaye des Premontres, Pont-A-Mousson , France,

Dec. 17, 1979.

H. S. Hertz, "Chromatography and Mass Spectrometry: A Love-Hate Relationship?" Washington Area Chromatography Discussion Group, HewlettPackard, Rockville, MD, Dec. 20, 1979.

H. S. Hertz, "Quantitative Aspects of Trace Organic Analysis,"

Knoxville College Chemistry Department Seminar, Knoxville, IN,

Jan. 16, 1980.

W. E. May, "Quality Assurance in Trace Organic Analysis," Staff Seminar,

Waters Associates, Milford, MA, Feb. 11, 1980.

W. E. May, "The Development of a PAH/Water SRM," Environmental

Protection Agency, Cincinnati, OH, Mar. 5, 1980.

W. E. May, "Quantitative Analysis of Trace Organics in Shale Oil by

Sequential Liquid Chromatographic Analyses," 1980 Pittsburgh

Conference on Analytical Chemistry and Applied Spectroscopy.

Atlantic City, NJ, Mar. 11 , 1980.

W. E. May, "Use of Fluorescence in HPLC Analysis," 1980 Pittsburgh

Conference on Analytical Chemistry and Applied Spectroscopy,

Atlantic City, NJ, Mar. 12, 1980.

H. S. Hertz, "Standard Reference Materials for Trace Organic Environmental

Analysis," 1980 Pittsburgh Conference on Analytical Chemistry and

Applied Spectroscopy, Atlantic City, NJ, Mar. 13, 1980.

B. Coxon, "Carbon-13 NMR Spectroscopy of Pyruvate Dimers," 179th National

Meeting of the American Chemical Society, Houston, TX, Mar. 24, 1980.

W. E. May, " Interlaboratory Comparison of Environmental Analyses

Associated with Synfuel Production," 179th National Meeting of

the American Chemical Society, Houston, TX, Mar. 25, 1980.

W. E. May, "Use of High Performance Liquid Chromatography in Trace

Organic Analysis," Chemistry Dept., University of Arkansas at

Pine Bluff, Pine Bluff, AR, Mar. 28, 1980.

E. White V and M. J. Welch, "The Accurate Determination of Organic Serum

Constituents by Isotope Dilution GCMS or Making Sense of a Bloody

Mess," Washington Area Mass Spectrometry Discussion Group, Hewlett

Packard, Rockville, MD, Apr. 7, 1980.

S. A. Wise, "High Performance Liquid Chromatographic Separation of Polycyclic Aromatic Hydrocarbons," Analytical Chemistry Division Seminar,

University of Maryland, College Park, MD, Apr. 18, 1980.

158
D. J. Reeder, "Spectrometric Studies of Alkaline Hydrolysis of Croconate

Blue Salts," 14th Middle Atlantic Regional Meeting, American Chemical

Society, King of Prussia, PA, Apr. 23, 1980.

L. R. Hilpert, "Mass Spectrometric Methods for the Quantitative Analysis

of Trace Organic Constituents in Alternate Fuels," American Society

for Mass Spectrometry 28th Annual Conference, New York, NY, May 26,

1980.

M. J. Welch, "An Isotope Dilution Mass Spectrometric Method for the

Accurate Determination of Urea in Human Serum," American Society for

Mass Spectrometry 28th Annual Conference, New York, NY, May 26, 1980.

K. L. Richie, "GC-MS Quantitation of Several Nitrogen Heterocycles in

Solvent Refined Coal," American Society for Mass Spectrometry 28th

Annual Conference, New York, NY, May 28, 1980.

S. A. Margolis, "Separation of Angiotensin I & II Analogs by Reverse

Phase High Performance Liquid Chromatography," American Society

of Bio Chemists, New Orleans, LA, June 4, 1980.

R. E. Botto, "Intramolecular Hydrogen-Bond Energies Derived from N-15

Spin Lattice Relaxation Measurements," Gordon Research Conference

on Physical Organic Chemistry, Brewster Academy, Wolfeboro, NH,

June 9, 1980.

R. A. Durst, "Current Status of the pH Scale," International Federation

of Clinical Chemistry Expert Panel on pH and Blood Gases, Herlev

Hospital, Copenhagen, Denmark, June 16, 1980.

R. A. Durst, "Reference Materials for Blood pH and Gases," International

Federation of Clinical Chemistry Expert Panel on pH and Blood Gases,

Herlev Hospital, Copenhagen, Denmark, June 17, 1980.

S. A. Wise, "Chemical Characterization of Organic Compounds by HighPerformance Liquid Chromatography," 2nd Symposium on Environmental

Analytical Chemistry, Brigham Young University, Provo, UT, June 18,

1980.

R. A. Durst, "NBS pH Scale Recommendations - Single vs. Multiple Primary

pH Standards," lUPAC Conference on the Harmonization of pH Scale

Recommendations, Calouste Gulbenkian Centre, Lisbon, Portugal,

June 19, 1980.

R. A. Durst, "International Practical pH Scale," lUPAC Conference on the

Harmonization of pH Scale Recommendations," Calouste Gulbenkian

Centre, Lisbon, Portugal, June 19, 1980.

R. Schaffer, "SRM's and Definitive Methods for Providing the Accuracy

Basis for Clinical Chemistry," Joint Meeting of the American

Association for Clinical Chemistry and Canadian Society of

Clinical Chemists, Boston, MA, July 24, 1980.

159
S. A. Wise, "A Relationship Between Liquid Chromatographic Retention and

the Shape of Polycyclic Aromatic Hydrocarbons," Gordon Research

Conference on Analytical Chemistry, New Hampton School, New Hampton,

NH, Aug 11 , 1980.

B. Coxon, "Analysis of Pyruvate Solutions by Proton NMR Spectroscopy at

400 MHz," Second Chemical Congress of the North American Continent,

Las Vegas, NV, Aug 25, 1980.

B. Coxon, "Characterization of Boat Conformations of a-D-Al tropyranoside

Derivatives by Proton NMR Spectroscopy at 400 MHz,^ Second Chemical

Congress of the North American Continent, Las Vegas, NV, Aug 25,

1980.

W. A. MacCrehan, "Liquid Chromatography Using Dual Electrode Reductive

Electrochemical Detection," Second Chemical Congress of the

North American Continent, Las Vegas, NV, Aug. 25, 1980.

H. S. Hertz, "Development in the Analysis of Priority Pollutants by Liquid

Chromatography-Mass Spectrometry and by Immunoassay Procedures,"

Second Chemical Congress of the North American Continent, Las Vegas,

NV, Aug. 27, 1980.

M. J. Welch, "Isotope Dilution/Mass Spectrometri c Methods for Accurate

Determinations of Organic Serum Constituents," Second Chemical

Congress of the North American Continent, Las Vegas, NV , Aug 28,

1980.

S. A. Margolis, "Nutrient Analysis Standards," Interagency Technical

Committee ClATC) Working Group on Nutrient Composition of Foods,

National Institutes of Health, Bethesda, MD, Sept. 10, 1980.

W. E. May, "Quality Assurance in Environmental Trace Organic Analysis,"

Chemistry Dept., University of Maryland, College Park, MD,

Sept. 12, 1980.

S. A. Wise, "The Pilot Environmental Specimen Bank Program," EPA

Narragansett , Narragansett, RI, Sept. 15, 1980.

3. Committee Assignments

Harry S. Hertz

Chairman, ASMS, Committee on Education

Member, ASTM, Committee D19 on Water

Member, CEQ, Interagency Task Force on Environmental Data and

Monitoring Air Polution Data and Monitoring Working Group,

Task Group in Anticipatory Monitoring

Board of Directors, NCCLS

Member, Program Advisory Committee, ACS, Division of Analytical

Chemistry

160
Bruce Coxon

Secretary, ASTM, Subcommittee E13.07 on Nuclear Magnetic Resonance,

Committee El 3 on Molecular Spectroscopy

Associate Referee, International Commission for Uniform Methods of

Sugar Analysis, Subcommittee 5 on 100 °S Point of Sugar Scale

Referee, U.S. National Committee on Sugar Analysis, Subcommittee 5 on 100 °S Point of Sugar Scale

Richard A. Durst

Member, ASTM, Committee D19 on Water

Member, Department of the Interior, Office of Water Data Coordination, Task Group 5 on Chemical and Physical Quality of

Water and Sediments

Secretary, IFCC, Scientific Committee, Analytical Section, Expert

Panel on pH and Blood Gases

Member, lUPAC, Committee V on Analytical Chemistry, Subcommittee 5 on Electroanalytical Chemistry

Member, NCCLS, Subcommittee on Electroanalytical Methods

Member, NCCLS, Subcommittee on pH and Blood Gases

Member, SAMA, Instrument Section, Electroanalytical Task Group

Consultant on Electrochemistry, U.S. Army, Task Group on Medical

Bioengineering R&D Laboratory

Barbara F. Howell

Alternate Councilor, ACS

Treasurer, ACS of Washington, DC

Member, ASTM, Committee E7 on Nondestructive Testing

Subcommittee E7.03 on Liquid Penetrant and Magnetic Particle

Task Group E07.03.02 on Magnetic Particle and Penetrant Testing

Penetrant Method

Task Group E07.03.05 on Magnetic Particle and Penetrant Testing

Task Group E07.03.06 on Magnetic Particle Methods

Task Group E07.03.07 on Magnetic Particle and Penetrant Testing

Magnetic Glossary

Willie E. May

Member, ASTM, Committee D19 on Water

President, Washington Chromatography Discussion Group

Dennis J. Reeder

Member, AACC

Study Group on Cortisol

Study Group on Total Serum Protein

Associate Member, IFCC, Expert Panel on Drug Effects in Clinical

Chemistry

Chairman, NCCLS, Subcommittee on Specific Plasma Proteins

Member, NCCLS, Subcommittee on Total Protein

161
Robert Schaffer

Member, AACC, Committee on Standards

Subcommittee on Cholesterol

Subcommittee on Creatinine

Subcommittee on Electrolytes in Serum

Subcommittee on Glucose

Subcommittee on Serum Iron

Subcommittee on Theophylline

Subcommittee on Urea

Subcommittee on Uric Acid

Member, NCCLS, Area Committee for Clinical Chemistry

Subcommittee on Calibration Reference Materials

Subcommittee on Quantities and Units

Member, NCCLS, Committee on National Reference System in Clinical

Chemistry, Subcommittee on Nomenclature and Definitions

Ranee A. Velapoldi

Working Advisor, ASTM, Committee E7 on Nondestructive Testing,

Subcommittee E7.03 on Liquid Penetrant and MPI Methods, Task

Group E7.03.03 on E-270 Glossary Revision

Member, ASTM, Committee E13 on Molecular Spectroscopy, Subcommittee

El 3.06 on Molecular Luminescence

Task Group El 3.06.01 on Presentation of Corrected Fluores- cence Spectra

Task Group El 3. 06.02 on Recommended Practices on Molecular

Fluorescence Spectroscopy

4. Other

a. Seminars

September 5, 1979 - Ellen Miseo, Polytechnic Institute of New York,

"Applications of Correlation Functions to the

Study of Relaxation Processes in Liquid Crystalline Systems".

September 6 David Grieble, University of Ohio, "Infrared

Spectroscopic Analysis of Hot Gases".

October 5

— George Turrel 1 , Laval University, "Some Applications of Fourier Transform in Infrared

Spectroscopy"

.

November 8 • Henry Blount, University of Delaware, "Heterogeneous Electron Transfer Kinetics of Biological

Molecules".

December 17 - William R. Heineman, University of Cincinnati,

"Optically Transparent Thin-Layer Electrodes:

Studies of Inorganic and Biological Systems".

162
January 29, 1980 Otto Grubner, Harvard University, "Improvement

in Gas Chromatographi c Separation by Specific

Activation of Compounds".

February 20 - Jimmie Ward, University of Florida, "Some

Analytical Applications of Phosphorescence at

Room Temperature and Below".

February 28 “ Jon Maple, University of Tennessee, "Dye Laser

Excitation in Matrix Isolation Molecular Fluores cence Spectroscopy".

March 6 - Alan Maxwell Bond, Deakin University, "The Use

of Microprocessors in Chemical Instrumentation".

March 21 - Ed Cehelnik, Governors State University, "Organi

Spectroscopy and Photochemistry of DPH"

.

April 2

— Mike Welch, National Bureau of Standards,

"Organic Isotope Dilution Mass Spectrometry as a Definitive Method in Clinical Chemistry".

Apri 1 1

6

- James Westgard, University of Wisconsin, "Statis

tical Control in the Chemical Laboratory".

May 2 - Alex Fatiadi, National Bureau of Standards,

"Chemistry of Oxo- and Pseudo- Oxocarbons".

May 16 - Allen J. Bard, University of Texas, "Photoelectrochemistry at Semiconductors".

June 6

— Harry S. Hertz and Edward White, National Bureau

of Standards, "Mass Spectrometry Competence

Building".

June 18 - John T. Stock, University of Connecticut, "Historic Instruments: The Scientist's Heritage".

July 3 - Electrochemistry Group, National Bureau of

Standards, "Review of Progress on the EC Competence Building".

August 4 - Petr Zuman, Clarkson College, "Some Applications

of Organic Polarography "

.

163
b. SRM Certification

1 ) SRM 17c, Sucrose

2) SRM 909, Human Serum

3) SRM 910, Sodium Pyruvate (In Progress)

4) SRM 912a, Urea

5) SRM 938, 4-Nitrophenol (In Progress)

6) SRM 1580, Organics in Shale Oil

7) SRM 1590, Stabilized Wine (In Progress)

8) SRM 1644, Generator Columns for PAH in Water (In Progress)

164
IV. Gas and Particulate Science Division

Harry L. Rook, Chief

Ernest E. Hughes, Deputy Chief

A. Division Overview

The Division is responsible for research on measurement methods for

gaseous molecules and for research in the general area of microanalysis.

The research is carried out in five groups with scientific effort divided

approximately equally between gas measurement research and microanalytical

research.

During the past year, substantial progress has been made in the

measurement of trace quantities of halocarbons and toxic organic gases.

Three new research gas chromatographs (GC) with multiple detectors have

been purchased and integrated into the research efforts. The first set

of stable gas mixtures containing 0.2 to 20 ppm benzene have been made

and a GC procedure has been developed for analysis with a precision of

better than one percent. The concentrations of these standard mixtures

are currently being verified by comparison to benzene permeation tubes

which have been calibrated gravimetrical ly. This will ultimately lead

to a benzene in air Standard Reference Material (SRM) which has its

accuracy derived from two independent bases. The procedure developed

for benzene will serve as a prototype for the development of other high

priority toxic organic gas standards.

The measurement research on N 2 O and halocarbons has been more difficult in that the target concentrations of interest are in the part per

billion (10"^ g/g) and in the part per trillion (10"^^ g/g) range respectively. Since no absolute preparative or analytical methods exist for

these concentration levels, we are developing two independent analytical

methods capable of measuring the species of interest. The result of this

year's efforts, concentrated on electron capture gas chromatography

(EC/GC), are described in detail in the technical accomplishment section.

Other plans for next year include the upgrading of the Center infrared

(IR) diode laser system and the development of an IR photometric method

of analysis for N 2 O as a target species. This work hopefully will offer

a new technique for the measurement of diverse gaseous species.

The particulate and microanalysis groups in general have experienced

substantial gains in the area of improving existing equipment and obtaining state-of-the-art microprobes. The need to upgrade existing equipment

and to obtain new second and third generation equipment has been stressed,

in recent years. This area is a cornerstone of the Division 5-year plan.

Since last year we have completely refurbished the ion-microprobe,

purchased a new 200 KV transmission electron microprobe, and placed an order for one of the first production models of the new laser microprobe

mass analyzer (LAMMA). In addition, a complete laboratory automation

facility has been planned and initiated. New microprocessers have been

165
purchased for all of the microprobes which require automated data acquisition and processing. An order has been placed for a central controller to

tie all of the local microprocessors to a central automated system for

analytical control and large scale data processing. The complete system,

linking the Division's six microprobes into one system should be installed

and operating by this time next year. The system will substantially

increase analytical speed and versatility on all microprobes. This is

very important as the future research emphasis in the microanalytical

group will shift to the quantitative analysis of arrays of particles in

the two micrometer and smaller size range. Also it is hoped that this

automated laboratory system will be a model for other areas in the Center

with similar automation needs.

Other areas of progress have been the development of a procedure

which allows direct measurement of light absorbing particles in the laser

Raman microprobe, the completion of the first asbestos counting grid

standard, and the development of a calculation technique to estimate

electron beam spreading in thin samples. These research accomplishments

will be discussed in detail in the technical accomplishments section of

this report.

The future thrust of the Microanalytical Research Group will clearly

be in developing analytical procedures for multidimension microanalysis

on complex samples or arrays of particles. This will include research

conducted under the new competence program in Compositional Mapping.

In summary, the Division has made substantial progress in research

related to trace gas measurement and small particle analysis. The

personnel level has been stable and significant improvements have been

made in equipment necessary to conduct meaningful research at the

forefront of analytical science.

1 . Gas Metrology Group: Overview

The primary responsibility of the Gas Metrology Group is to develop

and supply gaseous standards for all areas of science and technology where

accuracy in gas measurement is required either by mandate or necessity.

To this end, the group has two functions, the development of Standard

Reference Materials (SRM's) and the performance of research essential for

the characterization of gas standards. In addition a limited gas analysis

service, utilizing the unique capabilities of the group, is provided to

other groups at NBS and to other government agencies.

Research in the Gas Metrology Group has focused on improving the precision and accuracy of measurement of atmospheric concentration of carbon

dioxide, nitrous oxide, halocarbons, and physiological ly significant

concentrations of several organic species. Development of standards for

the accurate measurement of carbon dioxide have progressed to where excellent agreement with accepted international standards has been achieved.

As a result a large number of samples are being prepared commercially

which will be used to study the feasibility of large scale production of

166
highly accurate and stable CO2 gas standards. If production on a large

scale TS feasible then these standards, as SRM's, will be integrated into

the existing measurement network for atmospheric carbon dioxide.

A laboratory has been equipped with state-of-the-art chromatographs

for the measurement of trace concentrations of nitrous oxide and halocarbons. Research to improve the precision of measurements has begun and

studies are continuing in an effort to assess the accuracy with which

these measurements can be made. Concurrently , research is being conducted

on new spectroscopic techniques using diode lasers. These techniques,

have the potential for sensitivity, reproducibility and specificity equal

to or greater than currently employed gas chromatographic methods and, in

addition, the nature of the techniques is such that absolute measurements

may be possible.

Methods for preparation of accurate and stable standards of benzene

and perchloroethyl ene in air have been studied. These particularly difficult gas systems have required the development of special techniques

both for preparation of mixtures of predictable concentrations and for

their subsequent analysis.

As in the past the major output of the group has been the analysis

and certification of gaseous Standard Reference Materials (SRM's). Over

3400 individual samples of SRM's have been analyzed during the past year.

In addition, 85 gaseous SRM's sold by the Office of Standard Reference

Materials have been returned by the users for reanalysis as part of a continuing study of the stability of gas standards. It is anticipated

that seventeen new SRM's will be issued by the end of FY 1981. These

new SRM's include low concentrations of sulfur dioxide in air, nitric

oxide in nitrogen, oxygen in nitrogen, and propane in nitrogen, all at

concentrations extending the range of existing SRM's.

The joint program between NBS and the Motor Vehicle Manufacturers

Association will be successfully completed with the issuance of the last

three of twenty-six SRM's intended for measurement of emission from

heavy duty motor vehicles.

A document defining the process by which industry-produced gas

standards can be related to SRM's has gone through several evolutions

of both text and philosophy and is expected to be in a form acceptable

to both users and producers within the next few months.

Service analyses performed by the group have included gases

obtained from armament compartments of naval aircraft during inflight

test firing and analysis of gases generated by lithium batteries under

various operating conditions in an attempt to define conditions which

result in extremely hazardous situations. In addition, gas standards

used by the Mine Safety and Health Administration for quality control of

mine atmosphere and the standards used by the State of California as primary reference standards for motor vehicle testing have been analyzed.

167
Preliminary v;ork is in progress concerning the accurate measurement

of atmospheric oxygen to develop a method sensitive enough to recognize

changes in oxygen concentration of one part in 100,000 or less. Modification to a method developed more than a decade ago will be investigated

initially with the objectives of improving the accuracy and establishing

a new "base line" concentration for oxygen in the atmosphere in 1981 or

1982.

Ernest E. Hughes, Group Leader; William D. Dorko, James W. Elkins,

Joseph A. Mackey, Walter R. Miller, Richard C. Myers, George Rhoderick,

William P. Schmidt, Gerald Sleater, James E. Suddueth, William Thorn

2. Atmospheric Chemistry Group: Overview

The major thrust of , the Atmospheric Chemistry Group has been in the

development of measurement techniques for atmospheric species with

emphasis on new and improved instrumental procedures. The principal areas of technical expertise are in molecular spectroscopy and radiochemistry.

These resources are used in research on determination of fundamental con- stants required for spectroscopic measurements, molecular cross sections

in the ul traviol et, and line intensities and line broadening parameters in

the infrared. Research is also conducted on advanced spectroscopic methods

for trace analysis, e.g. optoacoustic methods of detection, and in the use of stable and radioisotopes for the characterization of the atmosphere.

Major continuing projects include the following: (a) the measurement of absolute ultraviolet (UV) absorption cross sections for application

to the measurement of trace atmospheric gases; (b) development of smallsample radiocarbon measurement techniques for the determination of sources of individual atmospheric chemical species; (c) development of

acoustically-detected Raman gain spectroscopy for the detection of

species in the condensed phase; (d) the development of gas phase titration procedures for the intercomparison of measurement standards for O 3 , NO, and NO2 ; and (e) the development and evaluation of personal samplers

for determining individual exposure to gaseous atmospheric pollutants.

Major new projects initiated during 1980 were: (a) the measurement

of absolute infrared band and line intensities for application to the

trace measurement of molecules in the gas phase with a tunable infrared

diode laser and/or a Fourier transform infrared spectrometer (FTIR); and

Cb) the development of an improved absolute ultraviolet photometer as a primary standard for the quantitative measurement of ozone.

Some signtficant accomplishments of the group during 1980 were:

(a) the completion of the spectrometer for measuring the temperature

dependence of ozone cross sections Cat stratospheric temperatures), the

determination of the temperature dependence in a critical region (310-320

nm) of the Huggins band; (b) an intercompartson among NO, O3 , and NO2 measurement standards by gas phase titration using the simple bimolecular

168
reaction, NOCexcess )+03 =N02 +02 . Agreement to better than one percent was obtained between the NO gravimetric cylinder and the NO2 permeation tube

Standard Reference Materials and a bias of ca. 4.5 percent was observed

between these standards and the current UV photometer measurement standard

for O 3 ; (c) an intercomparison of infrared band intensity measurements

obtained by the FTIR spectrometer with integrated band intensities

obtained from individual line intensity measurements by the tunable diode

laser spectrometer; (d) completion of a Raman spectroscopy study on and structure of adsorbed species; and (e) the discovery of a large

biogenic (natural) contribution to the volatile organic component of the

particulates comprising the Denver brown cloud and a predominately fossil

contribution to the elemental carbon portion of the particulate.

Significant research efforts for next year include the following.

Measurements of the temperature dependence of O 3 cross sections in the

most critical region of the Hartley-Huggins bands are planned. Work will

be completed and a report prepared describing a personal sampler for

nitrogen dioxide, including a wind tunnel evaluation. A major effort

will be underway on the development and evaluation of passive personal

samplers for toxic organic compounds. A new absolute O 3 photometer with

improved accuracy and precision will be completed and available for

calibration. Ultraviolet cross section measurements will be made for

application to the absolute measurement of a series of toxic atmospheric

organic compounds. Research will continue in the use of radiocarbon

measurements and the new techniques of accelerator mass spectrometry for

the characterization of the nature and sources of micro-quantities of

atmospheric gases and particulates. Finally a major effort will be

initiated on the development of infrared diode laser and FTIR techniques

for the absolute measurement of trace gaseous species.

Jimmie A. Hodgeson, Group Leader; Arnold M. Bass, Barry C. Cadoff,

Ilan S. Chabay, Lloyd A. Currie, Alan Fried, Robert H. Kagann,

George A. Klouda, Juan C. Lerman, James E. Norris

3. X-ray Fluorescence Group: Overview

The X-ray Fluorescence Spectrometry Group conducts research in sample

preparation including preconcentration methodology applied to a wide range

of sample types, develops new techniques for instrument calibration and

standardization, and conducts certification analyses on a wide variety of

NBS Standard Reference Materials.

The X-ray Fluorescence Spectrometry Group has devoted a major effort

in 1980 to the development and characterization of thin films containing

known concentrations of metals to serve as calibration standards in the

x-ray analysis of collected airborne particulate matter. This work, which

was part of a joint program between NBS and the United States Environmental Protection Agency (EPA), has recently been published in an NBS/EPA

report ( EPA-600/7-80-1 23 , June 1980). Our work in extending the sensitivity of the x-ray technique to sub-ppm concentration levels through

preconcentration as described in NBSIR 80-1995 report is continuing with

169
applications to the analysis of SRM biological and botanical samples.

The performance of our automated wavelength-dispersive x-ray spectrometer

which was acquired last year has been evaluated with SRM's with regard to

long term stability and measurement precision under computer control and

was found to be comparable to the most carefully conducted analyses done

manually. In connection with these studies several series of renewal

SRM's (alloys and glasses) have been analyzed for homogeneity and elemental composition. Progress has also been made in the development of a comprehensive matrix correction and x-ray line overlap computer program

for energy-dispersive x-ray spectrometric analysis.

In addition to the above programs we plan to investigate the x-ray

absorption spectroscopic technique using synchrotron radiation of the

Stanford facility for speciation type studies. This work will be con- ducted jointly with workers at the Lawrence Berkeley Laboratory.

Peter A. Pella, Group Leader; Edwin C. Kuehner, John S. Sieber

4. Particle Research Group: Overview

The objective of the Particle Research Group is to develop quantitative methods for chemical and physical characterization of single particles

and of arrays of particles. This includes research into new techniques

to interrogate individual particles such as the Particle Doppler Shift

Spectrometer and also research into improving current techniques such as our new sulfate aerosol analyser. The group interacts closely with the

Microanalytical Research Group but has historically been more concerned

with atmospheric particulate research.

The major foci of the Particle Research Group this year have been:

(1) completion of the initial stage of the development of the Personal

Ambient Aerosol Sampler (PAAS) which includes the design, construction,

and characterization of a wind tunnel facility, the characterization

of sampler collection efficiency and particle cut-off size, and the

evaluation of sampler pumps; (2) completion of the characterization,

calibration, and data acquisition-reduction procedures for the Pulsed

Electrostatic Precipitator-Flame Photometric Detector (PEP-FPD) Particle

Sulfur Analysis System and evaluation of the limiting factors of the

system resulting from the response time of the FPD.

The emphasis of our research and development activities in the coming

year will be on the use of the wind tunnel facility and aerosol generation

techniques for the design and performance evaluation of the PAAS and the

preparation of a respirable quartz Standard Reference Material. In both

these projects, we will continue to develop techniques for the generation,

sampling, dispersion, and size characterization of respirable aerosols and

particulates. A smaller effort will also be devoted to the development

and characterization of a fast-response FPD to be used in conjunction with

the PEP-FPD particle sulfur analysis system.

170
Next year the Particle Research Group will be able to take the

initiative in responding to both the desire of NBS to provide a respirable quartz SRM and the requests from both the National Institutes for

Occupational Safety and Health and ASTM Committee D-22 on Standard

Reference Materials for such a material. We will determine the size

distribution and distribution stability of candidate materials,

coordinate the chemical and phase purity measurements of the samples,

and take responsibility for the production of the SRM.

Raymond L. McKenzie, Group Leader; David S. Bright, Robert A. Fletcher

5. Microanalysis Research Group: Overview

The Microanalysis Research Group seeks to advance the development

and application of instrumental microanalysis techniques for the chemical,

crystallographic, and morphological characterization of matter on a micrometer scale of spatial resolution. The techniques utilized include

electron probe x-ray microanalysis, scanning electron microscopy, transmission electron microscopy, scanning transmission electron microscopy,

electron diffraction, energy and wavelength dispersive x-ray spectrometry,

secondary ion mass spectrometry, Raman spectroscopy, and laser microprobe

mass analysis. Research activities take place on several aspects of each

technique, including (1) advancing the understanding of the basic physics

of the primary excitation and secondary radiation attenuation;

(2) developing methods of quantitation; (3) developing standards appropriate to each method; and (4) applying the methods to selected problems

as a means of assessing limitations in practical analytical situations as well as aiding other NBS research activities.

Highlights of group activities in each area of interest include:

(1 ) X-ray microanalysis - Further development of the NBS characteristic/

continuum method for analysis of particles and rough samples has necessitated determination of an accurate function relating the intensity of the

x-ray continuum to beam energy, continuum energy, and sample composition.

This work is nearly complete and should also lead to useful applications

in conventional bulk specimen analysis where the background due to the

continuum must be accurately determined.

The requirement for accurate peak overlap corrections in quantitative

energy-dispersive analysis has led to the development of a calibration

method for high resolution wavelength spectrometers so that x-ray peak

ratios can be directly measured. This spectrometry is combined with an advanced mathematical spectrum fitting technique, the sequential simplex,

developed in a joint program with the National Institutes of Health.

A study of the spatial resolution of qualitative and quantitative

measurements in analytical electron microscopy has been carried out with

Monte Carlo electron trajectory simulation. This study is being expanded

to develop deconvolution methods to separate beam spreading effects in

thin foil analysis.

171
(2) Secondary ion mass spectrometry [SIMS) - The activity in SIMS

has been expanded with the hiring of a new SIMS specialist. The ion

microprobe mass^ analyzer is being upgraded to include automatic control

of the secondary ion spectrometer. A laboratory mini-computer has been

procured for this task and work is currently progressing on interfacing

the system to the ton mtcroprobe.

(3) Laser microprobe mass analysis - Procurement of a laser microprobe mass analyzer CLAMMA} has been initiated, with expected delivery in

December 1380. Preliminary experiments comparing the laser microprobe

mass analyzer with the ton microprobe and ion microscope have been made

at manufacturers' laboratories and at NBS.

(4) Laser-Raman microprobe - A Raman microprobe with multichannel

detection capability has been developed and tested in conjunction with

Instruments SA and McClellan Air Force Base (Air Force Technology Assessment Command, AFTAC). This instrument, in operation at McClellan AFB, is

being used to obtain Raman spectra from microparticulate samples of

specific interest to AFTAC. The multi-channel detection system can significantly shorten the time of data collection, as compared to the

single-channel detection system of the NBS instrument, and will prove

useful in obtaining Raman spectra from photo-or thermally-sensitive

materials. *

A major breakthrough has been made in the prevention of the destruction of thermally-sensitive materials when exposed to laser irradiation

for Raman analysis. The destruction of the materials made their investigation impossible. The new technique involves encapsulation of the

sensitive materials in a non-crystalline (amorphous) layer such as silicate.

The automation of the NBS Raman microprobe has been continued with

the procurement of a laboratory mini -computer.

(5) Standards - Substantial progress has been made on the development

of analytical electron microscopy standards for asbestos analysis in

conjunction with the Environmental Protection Agency (EPA). A correlated

counting method involving accurate stage position measurement has been

developed to evaluate uncertainties in operator counting data.

Other standards work includes the analysis of the NBS Research

Materials Glasses for Microanalysis to upgrade these materials to full

Standard Reference Materials (SRM's). In addition extensive work on the

characterization of the homogeneity of a stainless steel SRM has been

carried out.

In conjunction with other divisions within the Center for Analytical

Chemistry, the microanalysis group will initiate a program to develop

quantitative compositional mapping techniques on a micrometer scale.

This effort will initially involve the electron and ion microprobes, with

future extensions to the laser Raman microprobe, analytical electron

microscope, and laser microprobe mass analyzer. Crucial to the success

172
of this task will be an understanding of the effects of topography and

chemical and crystallographic heterogeneity on quantitative compositional

analysis. In addition to such fundamental studies, rapid data reduction

procedures will be developed so that an entire image can be processed

efficiently. The availability of diverse equipment and personnel at NBS

provides the basis for the Bureau to become a major center in this

rapidly developing area.

In addition to compositional mapping, we are also developing a program involving multi-technique analysis of particles. This program

will utilize electron microscopy, secondary ion mass spectrometry, Raman

spectroscopy, and laser microprobe mass spectrometry for the full characterization of individual particles. In order to implement the program,

it is necessary to develop specimen preparation procedures which will

be suitable for all techniques. The combination of instruments available

at NBS offers the unique opportunity for this investigation.

Dale E. Newbury, Group Leader; Adville A. Bell, John J. Blaha,

Edgar S. Etz, Patrica A. Johnson, Ryna B. Marinenko, Robert L. Myklebust,

Patrick J. Sheridan, David S. Simons, John A. Small, Eric B. Steel,

Barbara B. Thorne
B. Selected Technical Accomplishments

(Gas and Particulate Science Division)

1. Intercomparison of O 3 , NO and NO2 Measurement Standards by

Gas Phase Titration

Ozone (O 3 ), nitric oxide (MO), and nitrogen dioxide CNO2 ) are critical

constituents involved in the chemistry and physics of the troposphere and

stratosphere and are subject to considerable monitoring requirements. For

each of these gaseous constituents, an individual measurement standard is

currently employed for calibration. Ozone is measured on an absolute

basis by absorption photometry using the known O3 cross section at the

mercury 253.7 nm line. For NO and NO2 the measurement standards take the

form of Standard Reference Materials (SRM's); NO is gravimetrical ly

prepared in cylinders, while the NO2 SRM is a permeation tube. This is

the first concerted effort to intercompare gas standards by means of known

chemical reactions, in this case employing the rapid, bimolecular

reaction,

NO (excess) + 03 = NO2 + O2

.

At low concentrations of O 3 (sub-ppm levels) and in the presence of excess NO, the reaction is stoichiometric and the following relationship

holds

A(N0) = A(03) = a(N02).

Therefore a measurement of any one of the three components (A(N0) = reacted, A( 03 ) = added, A(N02 ) = produced) yields a measurement of the

other two.

In the experimental arrangement, NO from a standard cylinder

(50 or 100 ppm) is diluted with clean air by a flow dilution ratio,

R = 30 - 100, to obtain an initial NO concentration in the range of

0.5 - 1.5 ppm. The clean air stream passes through a variable O3 source

such that O 3 can be added in increments over the range, 0 - 1 ppm. The

output of the reaction vessel passes to a sampling manifold where the

concentrations are monitored with calibrated detectors.

Since the NO sample from the cylinder must be diluted, an accurate

determination of the initial NO cylinder concentration requires an accurate determination of the flow dilution ratio, R. Considerable

effort was expended in verifying the measurement of the NO and clean air

flows. A wet test meter calibrated gravimetrical ly was employed for the

air flow and the calibration of this meter was verified at the primary

flow calibration facility of the NBS Fluid Engineering Division. The

low flow rate NO measurement was performed with a soap bubble meter, a mercury sealed piston device and a wet test meter, the accuracy of which

was confirmed at the primary flow calibration facility. The estimated

uncertainty in the measurement of R is less than one percent.

174
Our initial objective was to provide an independent analysis of the

NO SRM based on photometric O 3 measurements. Our initial gas phase

titration (GPT) measurements, however gave NO cylinder analyses which were

consistently 4-5 percent lower than the gravimetric analysis. This in

turn indicates that the aCOs) photometric measurement is less than A(N0)

based on gravimetric calibration by the same amount. In an attempt to

resolve this bias a specially designed optoacoustic detector was constructed

to measure the NO2 produced. This detector uses an argon-ion laser for

excitation of the NO2 visible absorption band. The detector is calibrated

with an NO2 permeation tube standard and has a minimum detection limit of

.005 - .01 ppm. An important feature of the optoacoustic detector is that

it does not respond to NO. Previous attempts to make similar measurements

have used chemiluminescence NO detectors (NO = NO + NO2 ) which measure

X X NO2 differentially, i.e. NO - NO = NO2

. Considerable measurement

X uncertainty is introduced when NO is present at higher concentrations, as

in the GPT experiment.

A limited number of measurements have been made thus far on NO2 produced, based on a permeation tube calibration, A(N 02 )pt, but these

data are revealing. A considerable amount of data have been obtained

comparing A(N0) gravimetric, A(M0) , and aCOs) by photometry, aCOs) , g

u V over the range 0 - 1 ppm. These data were obtained over a one year time

scale by two independent operators and comprise 15 different GPT experiments with 44 valid data pairs. These data sets can be fitted by linearregression to yield the following relations:

A( 03 ) = (0.957 ± 0.002) A(N0) + (.0002 ± .001), n = 44

u V g

A(N02 ) . = (1.01 ± 0.01) A(N0) - (.0052 ± .0055), n = 8

P ^ 9

The intercepts are negligible within the uncertainty of the fit.

The precision of the GPT measurements is excellent and reflects the

precision of the flow measurements as well as the stability of the various

detectors. The apparent agreement between A(N0) and A(N 02 ) verifies the

reaction stoichiometry and that the GPT apparatus is working properly. We are left with the implication that the O 3 ultraviolet measurement may be

low by approximately 4 percent. This is a larger bias than can be explained

by estimates of the uncertainty in the presently accepted value of the O 3 cross-section. We are continuing the NO2 measurements for further verification of the above results. In addition a new and improved O 3 photometer

is being constructed to replace our e'xi sting system and an independent O 3 calibration will be available

soon.

J. A. Hodgeson, A. Fried

175
2 . Development of Atmospheric Nitrous Oxide and Halocarbon Standards

Atmospheric nitrous oxide, and certain halocarbons are considered

to be important in that they may have a long-term impact on the concentration of ozone in the stratosphere and consequently the radiation budget

of the earth. Measurements at low altitude are used as the basis for

predicting mass diffusion into the stratosphere where the critical

reactions between ozone and these substances may occur. Large variability

of measured concentration (sometimes as high as a factor of 2) have been

reported by various laboratories and it is probable that these variations

arise from inaccurate standards and from technical problems associated

with instruments used for ultra-trace analysis.

Participants at a Workshop on the Measurement of Atmospheric Halocarbons

and Nitrous Oxide, held at the National Bureau of Standards, recommended

that NBS should prepare a series of Standard Reference Materials (SRM's),

at ambient concentration levels for nitrous oxide and some halocarbons.

The suggested gas standards, concentration ranges of the standards

in air, and the minimum uncertainties are given in Table 15. The concen- tration ranges represent the lowest levels at which any gas standards

will have been certified as SRM's.

Table 15. Recommended Gas Standards

Concentration Range

Substance (in air)^ Uncertainty

1

.

Halocarbon F-11 50 - 250 ppt 0.7%

2. Halocarbon F-12 100 - 400 ppt 0.5

3. Nitrous Oxide 250 - 350 ppb 0.3

4. Methyl Chloroform 50 -100 ppt 2

5. Carbon Tetrachloride 50 - 100 ppt 5

6. Methyl Chloride 400 - 800 ppt 5

^ppb = parts-per-bill ion (10^),

ppt = parts-per-trill ion (10^^).

Work on the first three gas standards listed in Table 15 is being

funded for a three year period by both the National Aeronautics and Space

Administration (NASA) and NBS. The development and research for preparation of the last three gases will begin upon completion of production of

the first three standards.

Accordingly, we are investigating the preparation of accurate

standards and, as a necessary complementary effort, the improvement of

analytical techniques. A laboratory has been completed this year in

which state-of-the-art gas chromatographs have been modified to achieve

176
the high sensitivity and stability of operation necessary to evaluate the

preparation of standards and to accurately assess the concentrations. The

approach to the standards preparation involve both the improvement of

precision of measurement of these substances and the evaluation of

accurate methods of preparation of standards. A preliminary investigation of N2 O mixtures prepared by weight (gravimetric standards) and

mixtures prepared by pressure (manometric standards) indicates a difference between the two methods of no more than 1.5 percent relative at

the 300 ppb concentration level. These samples also will serve as references to evaluate the stability of similar mixtures. Preliminary results

indicate that no significant changes in the concentration of nitrous oxide

in compressed gas mixtures occur over a period of 25 months in aluminum

cyl inders

.

The necessity for extremely sensitive analytical methods has in

general resulted in the use of gas chromatography using electron capture

detectors for the analysis of atmospheric halocarbons and nitrous oxide.

However, the nature of the electron capture detector is such that great

skill and considerable experience are required in order to obtain consistent and valid results. Alternate methods of analysis have been surveyed

and an investigation was begun of a most promising technique - infrared

absorption spectroscopy using a tunable diode laser as a source. This

basic method modified by applying second derivative interpretation of the

specific lines has yielded most encouraging results in the analysis of

nitrous oxide. Figure 27 illustrates the analysis of two samples of

nitrous oxide with known concentrations in the ratio of 1.12/1.00. The

higher concentration is approximately 300 ppb. The sensitivity and

reproducibility is comparable to that of electron capture chromatography

and it is believed that with modification to the method it could be

improved substantially and accordingly a parallel investigation is

proceeding comparing the results obtained using the optical technique to

those obtained by gas chromatography.

177
259 ppb 300 ppb

Figure 27. Second derivative signal of the absorption line, P(26), at

2199.73377 cm"^ of the V 3 band of N 2 O for (A) 259 ppb N 2 O

and (B) 300 ppb N 2 O in air. The ratio of the peak heights

B/A is 1.12 ± 0.02 (4 measurements). The sample pressure is

11 torr with a total optical path length of 15.74 m.

J. W. Elkins, E. E. Hughes
3. The Determination of Infrared Line Intensities for Selected

Molecules Using Diode Laser and Fourier Transform Infrared

Spectroscopy

There are intensive measurement programs in this and other countries

which are a part of a comprehensive effort to investigate the earth's

atmosphere. The goal of these programs is to obtain accurate measurements of the concentration profiles of most atmospheric constituents and

the temperature profile of the atmosphere. The purpose of these

measurements is to predict the response of the ozone layer to changes in

concentrations of other constituents, to understand the role of the

atmosphere's composition in climate and climate variability, and to

monitor pollution. The investigators are increasingly relying on high

resolution infrared spectroscopy to make more accurate measurements. But

high resolution infrared atmospheric determinations require accurate

laboratory measurements of infrared line parameters (i.e. line strengths

and line widths as well as wavelengths of line centers). To fulfill

these needs, we in collaboration with personnel of the NBS Molecular Spec

troscopy Division have initiated a program to measure infrared line

strengths and pressure broadening coefficients of atmospheric gases

employing both diode laser spectroscopy (DLS) and Fourier transform

spectroscopy (FTS). The line parameters also will facilitate our program

to apply infrared spectroscopy to the absolute measurement of gas

standards

.

More than 600 DLS measurements were made on the vi band of N2 O.

We measured the line strengths of fully resolved absorption lines in the

vi band of the common isotope ^^N 2 ^^ 0 , the associated hot bands and the

vi bands of the isotopes, ^^N2^®0 and We also measured the

pressure broadening of these lines by the two major atmospheric constituents, N 2 and O2 , as well as self-broadening. The DLS measurements were

made in the 0.5 to 20 torr regime. We estimate the accuracy of our line

strength measurements to be within 5 percent and the accuracy of the

pressure broadening coefficients to range from 5 to 10 percent.

By least-squares fitting our data to the appropriate band model,

band parameters were obtained from which we calculated a band strength

for the entire vi band system. We also made direct FTS band strength

measurements of several N2 O absorption bands to enable us to cross-check

our DLS results.

We can compare the FTS measurements of the band strength of the vi

band system (1285 cm"^) with the value we determined from our DLS data.

We made two separate FTS measurements of this band and obtained the

values, 225.3 cm’^ atm"^ (295 K) , and 227.9 cm’^ atm”^ (295 K) . These

determinations were obtained with 3.62 torr and 6.52 torr N2 O gas samples

respectively; both samples were pressurized to one atmosphere with

nitrogen to ensure adequate pressure broadening. This was required

because the effective slit width of the FTS system (0.06 cm"^) was 100 times larger than the effective slit width of the DLS system. The

agreement of the determinations obtained by DLS and FTS is well within

179
our estimated uncertainty of the DLS measurement, 220 ± 11 cm ^ atm

This gives us confidence in the FTS values we obtained for the absolute

intensities of other absorption bands in N2O.

More cross-checks will be performed in the future to enable us to

better estimate uncertainties in the FTS determinations. The present

calibration is important because we now are measuring absolute intensities

in two other atmospheric species, HNO2 and HNO3.

R. H. Kagann

4. The Measurement of Temperature Dependence of Ozone Absorption

Cross-Sections in the Ultraviolet

The ozone layer in the stratosphere protects all forms of life

at the surface of the earth from excessive exposure to solar ultraviolet

radiation. There is great concern that the emission of substances such

as nitrogen oxides and halocarbons into the atmosphere may modify the ozone layer and cause possible harm to life on earth. Measurement of

ozone concentrations in the upper atmosphere of the earth is essential in

order to detect changes that may be caused by man's activities. Total

ozone column density and vertical profiles are determined mainly by means of ultraviolet (UV) absorption spectrophotometry. The interpretation of

the atmospheric measurements in terms of accurate ozone concentrations

requires a knowledge of the absorption cross-sections of ozone over the

range of wavelengths and temperatures involved. Since previously reported

cross-section determinations have been limited, both in wavelength and

temperature, we have undertaken to make a careful detailed measurement of

these absorption cross-sections.

An ultraviolet photometer of novel design was constructed and

coupled to a high-resolution scanning monochromator. The photometer is

capable of providing absorption measurements of great sensitivity and

high accuracy. Radiation from the exit slit of the spectrometer is

directed through two sample cells, each 1 meter long, and detected by a pair of photomultiplier tubes. The sample is prepared by ozonizing air

or oxygen either by electric discharge or by UV photolysis and then

flowing the air and ozone/air streams alternately through the two absorption cells. The changes in light transmittance are detected by the

photomultiplier tubes and are recorded in digital form in high speed

scalers. The ozone concentration in the sample is determined by measuring

the transmittance of the same sample in a short (1 cm) cell with a fixed

wavelength (253.7 nnm) source and detector system. The cross-section

determinations are therefore to be considered as made relative to the

accepted value at 253.7 nm and are not strictly absolute determinations.

The sample containers are installed in an adjustable temperature chamber.

The apparatus is automated and controlled by a computer so that the

spectrum can be recorded in great detail in a minimum amount of time.

Our plan is to record the ozone spectrum over the wavelength range 200 to

180
CR0SS-SECTI0N

(SQ.CM.

X

10

EXP20

)

700 nm and over the range of temperatures 200 to 300 K. Measurements

are now underway in the 290 to 350 nm region.

Figure 28 shows the spectrum recorded for 320 to 310 nm and at

two temperatures (298 and 244 K) . These spectra were recorded with a spectral resolution of less than 0.02 nm, in steps of 0.05 nm.

[y\)nn)

Figure 28. Absorption spectrum of ozone at 298 K and 244 K. Spectral

slit width 0.02 nm; wavelength scanned in steps of 0.05 nm.

A. Bass

181
5. Standards for Measurement of Atmospheric Carbon Dioxide

Since the early 1950s internationally accepted standards for the

measurement of atmospheric carbon dioxide have been traceable to a single

set of manometrical ly analyzed standards prepared by Dr. David Keeling of

Scripps Institute of Oceanography (SIO). Expansion of the monitoring

network and the necessity for assuring a continuing supply of standards

of high accuracy prompted the National Oceanic and Atmospheric Administration and the Environmental Protection Agency to involve the NBS in

a program to produce SRM's equal in accuracy to the standards maintained by Keeling. The production of such standards requires a method

of preparation of laboratory primary standards that are both accurate

and reproducible. An uncertainty of ± 0.1 ppm for a standard containing

330 ppm was considered the maximum tolerable error.

A unique microgravimetric technique was developed and a set of 14

standards varying in concentration from 290 to 370 ppm were prepared.

The gravimetric technique involves weighing the carbon dioxide contained

in a "micro cylinder" on a semi micro balance and accurately transferring

it to a large cylinder to which a weighed amount of air is added. The

internal consistency of the set was evaluated by intercomparing samples

in the set with each other using both gas chromatographic and non- dispersive infrared techniques. Painstaking care was taken to assure the

highest degree of precision of the measurements. The results showed that

the average of the deviations of the samples from the predicted value was

± 0.02 ppm and the standard deviation of the observed value relative to

the predicted value was 0.09 ppm. These standards were then used to

analyze three working secondary standard mixtures of 346.7, 340.0 and

333.3 ppm, respectively.

The three secondary standards were taken to SIO and were analyzed by

that laboratory in common with their own primary standards. A comparison

of the NBS and SIO results is shown in the data below:

Sample NBS Value Value Determined at SIO

1 346.7 ± .17 ppm 346.7 ppm

2 340.0 ± .09 ppm 339.9 ppm

3 333.3 ± .10 ppm 333.2 ppm

The limits shown for the NBS value is an estimate of the uncertainty

of the concentration of the secondary standard relative to the primary

gravimetric standard. The uncertainty of the value measured by SIO is

not known on an absolute basis but the repeatability of the measurement

is estimated to be about ± 0.1 ppm.

The agreement is excellent considering the complete independence of

approach of each laboratory. However, further work is planned to improve

the precision of the measurements and thereby to determine whether the

slight differences are random errors or biases between the methods. The

182
most probable source of error in the NBS value would be in the analysis

of the reagent gases while the most likely source of error at SIO would

be associated with volume calibrations. Both of these error sources are being investigated.

E. Hughes, G. Sleater

6. Industrial Preparation of Traceable Gas Certified Reference

Material

s

The demand for gas standards is increasing at an accelerated rate.

Improvement in instrumentation during the last two decades and mandated

requirements for accuracy in gas measurements related to environmental

concern have both contributed to the demand. NBS limitations imposed on the gaseous SRM program resulted in severe shortages of standards which

on occasion has caused concern among regulatory agencies, users and

producers. Since it is not realistic, either philosophically or physically,

to consider expanding the gaseous SRM program beyond its present bounds,

it has become essential to establish some alternative supply of accurate

standards. As a result of this need a protocol has been developed which

in essence transfers the responsibility for producing large numbers of

accurate standards (Certified Reference Materials) to the specialty gas

industry. The protocol makes provision for monitoring by the regulatory

agencies and at the same time NBS retains the responsibility for assuring

traceability of the Certified Reference Materials (CRM's) to NBS gaseous

SRM's.

According to the protocol, the specialty gas producer will prepare

CRM's at concentrations equal to or very close to the concentration of

existing SRM's. These will be prepared in large homogeneous batches.

The producer will analyze each CRM from the batch by comparison to an SRM. The regulatory agency will select samples from each batch for

analysis. The analysis by the regulatory agency will be performed using

SRM's as calibrants. Both the producer and the regulatory agency will

furnish NBS with complete information concerning the production and

analysis of the CRM's including the data for both calibration of the

instruments used and the analysis of the CRM's. NBS will then statistically compare the results reported by the producer with those found by

analysis by the regulatory agency. In addition, NBS will examine all the

results reported by the producer to ascertain the homogeneity of the

batch. From these data it will be possible to verify the total

uncertainty of the concentration claimed by the producer. At this point

the concerned parties will be notified that the particular batch of CRM's

has been prepared in accordance with the protocol and that the stated

concentration is correct within the defined limits of uncertainty.

The protocol in its present form has been extensively modified

in response to comments from the gas industry, users of SRM's and the

principal regulatory agency, the Environmental Protection Agency. It is

not a "cook book" by which CRM's can be prepared. Rather, it recognizes

the experience and expertise of the specialty gas industry while at the

183
same time it recognizes the reservations which the user may have regarding

the industry and which the industry may have regarding the regulatory

agency. It is expected that the role of NBS as an independent overseer

will inspire confidence not only in the quality of the CRM's but in the

integrity of the entire procedure.

The availability of CRM's should moderate the demand for the

corresponding SRM's, so that the latter would be used largely as primary

standards, which was the purpose for which they were originally produced.

E. E. Hughes

7 . Standards for Measurement of Benzene and Perchlorethyl ene in Workplace

Atmospheres

The increasing concern with the potential hazards associated with

certain organic compounds in industrial workplace atmospheres has

emphasized the need to solve the difficult problem of standardization of

the measurement of low concentrations of intermediate molecular weight

volatile organic compounds. The compounds of interest include benzene,

toluene, perchlorethyl ene, chloroform, carbon tetrachloride, ethylene

dichloride, and tetrachl oroethyl ene. Work completed several years ago at

NBS indicated that mixtures of these compounds in air at high pressure in

steel cylinders could not be prepared with predictable stability.

However, aluminum cylinders, which have reduced adsorptive and absorptive

properties of the inner surface compared to steel cylinders, appeared to

be capable of containing organic mixtures with reduced losses.

Consequently, mixtures of benzene in air and perchlorethyl ene

in air were prepared by a micro-gravimetric technique developed at NBS

and the concentrations were determined over a period of several months.

The benzene mixtures which ranged in concentration from 0.2 to 10 ppm were found to have the same relative concentration, within the uncertainty

of the analytical technique, over this period. The usual difficulties

associated with the analysis of sub-ppm concentrations of benzene in

air samples were encountered during these determinations. The effects

of the non-linearity of response to concentration ratios, the imprecision

of integration for small peaks and the drift of the flame ionization

detector response due to slow changes in instrument and sampling conditions were moderated by using multiple-standard calibration curves and careful

sampling techniques. The elimination of the interference caused by a cylinder contaminant (probably residual trichloroethylene) was accom- plished by the careful selection of the column parameter (i.e., length,

material, temperature), and carrier-gas flow rates.

The gravimetric method used to prepare the air mixtures of benzene

or perchlorethyl ene was devised to overcome the problem of transferring a vapor at low pressure into a cylinder without contamination by atmospheric

air. The organic liquid was introduced into a previously weighed

184
capillary tube which was then sealed and reweighed to determine the

weight of the organic. The capillary tube was then placed in a short

length of flexible tubing which in turn was connected to the weighed

sample cylinder. The capillary was broken inside the flexible tube and

the contents were flushed totally into the sample cylinder. The sample

cylinder was then filled with the diluent gas whose mass was determined

by difference after weighing the filled sample cylinder. Gravimetric

standards with uncertainties in their concentrations of less than ±

1 percent relative can be thus prepared.

Alternatively standards may be generated by permeation tubes containing the substance of interest. However, the accuracy of mixtures generated

with permeation tubes depend to a great extent on the stability of the

permeation rate. Tubes containing a number of different organic compounds

were studied over a period exceeding one year. The results showed that

tubes containing benzene required as much as one month to reach equilibrium at constant temperature. Tubes containing other organic compounds

required greater or lesser times depending on the particular organic

involved. The rates after equilibrium, however, were found to have

uncertainties of less than ± 1 percent relative.

It appears that permeation tubes may serve as adequate standards

providing the conditions under which they are kept are carefully controlled

and if frequent measurements of the permeation rate are made.

W. P. Schmidt

8. Motor Vehicle Manufacturers Association Program for Heavy Duty

Vehicle Emissions Standards

In 1978 a joint program was initiated between NBS and the Motor

Vehicle Manufacturers Association (MVMA). The goal of the program

was to produce twenty-six new gaseous SRM's which are required by the

motor vehicle industry for emission testing of heavy duty vehicles to

insure compliance with government regulations. The production of these new SRM's would have been impossible within existing NBS programs because

of constraints imposed by the already heavy commitments to produce other

gaseous SRM's.

This program ended successfully in September of 1980. Twenty

three new SRM's have already been issued by the Office of Standard

Reference Materials and the final three will be available in the near

future.

The program has benefited MBS in a number of ways. For instance,

the development of ten new carbon monoxide in nitrogen mixtures involved

measurements which demonstrated the usefulness of high-pressure injection

from large sample loops into a gas chromatograph to increase ultrasonic

detector response for carbon monoxide mixtures at concentrations of less

than 100 ppm. The technique allowed the intercomparison of samples with

185
standards with a precision of ± 0.2 percent. Certification of these

SRM's involved the first test of the software used to control the combined

gas chromatography NBS-developed computer operated-gas analysis system

(COGAS). COGAS had previously been used only with continuous flow gas

analyzers

.

The 100 ppm propane mixtures containing 0 percent, 5 percent and 10

percent oxygen, when used with an existing SRM containing 20.95 percent

oxygen, permits the study of flame ionization detector (FID) response

characteristics as a function of oxygen content. This is important to

allow the optimization of air to fuel ratios for individual FIDs used in

direct combustion exhaust measurements.

The final three SRM's to be issued under this program are 5, 10,

and 20 ppm nitric oxide in nitrogen. Nitric oxide is not particularly

reactive except toward oxygen with which it readily combines. The

resulting nitrogen dioxide is quite reactive and may be lost from the gas

phase of a cylinder by reaction on the cylinder walls. Careful cylinder

treatment and the elimination of all oxygen from the system is essential

for the preparation of stable mixtures of nitric oxide. A number of

mixtures of low concentrations of nitric oxide in nitrogen were prepared

manometrical ly in aluminum cylinders. Analyses were performed over a period of 18 months and no evidence of instability of the mixtures was found. Consequently, it was possible to prepare similar mixtures by the

more accurate gravimetric techniques. These mixtures were then used as laboratory standards for the analysis of the SRM's.

The potential SRM's were purchased commercially in lots of 50

at each concentration. Unlike most other SRM's, the lots were not

entirely homogenous and in addition some evidence of a very slow decrease

in concentration was observed for some samples in each lot. For these

low concentrations of nitric oxide each sample must be individually

certified.

All mixtures of nitric oxide in nitrogen contain small quantities of

nitrogen dioxide. The quantity may be relatively small in mixtures

containing large amounts of nitric oxide but these quantities of nitrogen

dioxide may constitute a significant fraction of the total oxides of

nitrogen (NO ) in low concentration mixtures. Chemiluminescent analysis

A may be used to differentiate the two species but the uncertainty is

great. A chemical method, the Saltzman Method, may also be used.

However, this method is quantitated by using mixtures of nitrites at

various concentrations. A factor of about 0.72 is usually applied to the

results to compensate for the "non-stoichiometric" reaction. A modification to this method has been developed which involves the use of high

nitrate concentrations in the absorbing solution which not only increases

the factor to 1.0 but eliminates a previously observed concentration

dependence of the factor. This method, using nitrite standards, in a high concentration nitrate solution, has been used to measure concentrations of nitrogen dioxide generated using permeation tubes and the

calculated and predicted values agreed within 1 percent relative.

186
The NBS/MVMA joint program is a good example of the type of positive,

synergistic venture between industry and MBS envisioned in the establishment

of the NBS Research Associate Program, leading to important accomplishments beneficial to all involved. The legacy of improved measurement

techniques and the more than 100 new gravimetric standards resulting from

the program will benefit MBS' ongoing programs; while the availability of

these desperately needed SRM's, not otherwise possible without the

program, will allow clean air milestones to be met by the motor vehicle

industry.

W. Thorn, R. Miller, E. E. Hughes

9. Evaluation of the Coherent Anti-Stokes Raman Spectroscopy (CARS)

Capillary Waveguide Detection System for High Performance Liquid

Chromatography

In previous characterizations of organic materials conducted with

coherent anti-Stokes Raman spectroscopy (CARS), a capillary waveguide

sample cell was found to increase the detectability of the CARS signal by

two orders of magnitude when compared to the 1 cm path length cuvette

cell normally used [1]. The capillary waveguide is most efficient when

it incorporates a very small internal diameter and a very long path

length and can be used to lower the detection limits for non-resonant

CARS to approximately 10”^ M. Resonant-enhanced CARS (pumping laser

frequency approaches an allowed electric dipole transition frequency)

shows a lowering of the detection limits to 10"^ M. A combination of

resonant-enhanced CARS and the capillary waveguide sample cell would be

expected to achieve detection limits to 10"® M.

Perylene (a polycyclic aromatic hydrocarbon) could easily be detected

at concentrations of 10"^^ M in toluene under non-resonant conditions in

the capillary waveguide. An example is presented in figure 29. The bands

of perylene are indicated by a P. No spectral features could be observed

when resonant-enhanced conditions were used. This is due to the fact

that all of the CARS signal is absorbed by the sample due to the extremely

strong absorbance at the wavelength of resonant-enhancement. Thus,

resonant-enhancement of the CARS signal is not possible with a capillary

waveguide. These results have given insight into the capabilities and

limitations of the capillary waveguide and have formed a basis for

further examinations of detection schemes using CARS.

187
T

Figure 29. Coherent anti -Stokes Raman spectrum of 2 x 10”^ M perylene in

toluene taken under non-resonant conditions. Toluene bends are marked "T" and perylene bands are marked "P". Pumping

laser wavelength is 540.00 nm. Scanning laser wavelength varies over the range 575.75 to 583.31 nm in 0.02 nm increments.

Thirty-six pulses per point data collection. Full scale is

0.02456 V analog signal normalized to 1.00.

In order to utilize resonant-enhanced CARS to obtain detection

limits at the lO""^ M level, a single pass cell with a very short pathlength appears to be necessary. A cell of this type has been developed

by Carreira, et al [2]. Detection limits for many organic materials have

been reported at 10”^ to 10”^ M levels. This type of detection system,

when coupled with such instrumentation as high performance liquid chromatography (HPLC), gives detection limits that are much lower than have

previously been realized by CARS and also allows molecular specificity

which is not present in other detectors currently used for HPLC.

References

[1] Schaefer, J. C., and Chabay, I., Generation of Enhanced Coherent

Anti -Stokes Raman Spectroscopy Signals in Liquid-Filled Waveguides,

Optics Lett. 4, 227-229 (1979).

188
[2] Carrei'ra, L. A., and Rogers, L. B., New Liquid Chromatographic

Detection System for Environmental Pollutants, EPA Research

Report EPA-600/4-80-01 5, February 1980.

J. J. Blaha, J. C. Schaefer

10. Measurement of Ambient Sulfur Aerosols By a New Fast Response

Flame Photometric Instrument

The development and characterization of the Pulsed Electrostatic

Precipitator-Flame Photometric Detector (PEP-FPD) system for the measurement of ambient level aerosol sulfur concentrations has been completed

this year and a final report to EPA is in the review process. The basis

of the technique is the use of the PEP to selectively modulate the

aerosol component of the sample while leaving the gas phase component

unaffected, resulting in a signal from the detector (FPD) which has two

separable components corresponding to the particle and gas phase sulfur

concentrations. Because the FPD response to sulfur concentration is

non-linear (Response where n = 1.5 to 2 depending on various flame

and flow parameters) the sensitivity of the FPD is a function of the

total sulfur concentration in the sample. The following data shows the

sensitivity (dl/dS) and sensitivity relative to sensitivity at 1 ppb for our FPD.

[s] (ppb) dl/dS (amp/ppb) dl/dS relative to 1 ppb

10

1 1.42 X 10 10 (

1 ) 5 4.81 X 10"io 3.4

10 8.13 X lO'g 5.7

50 2.75 X lO’g 19.4

100 4.65 X lO'g 32.7

200 7.86 X lO’e 55.4

500 1 .57 X lO'e 110.8

1000 2.66 X 10' 187.3

One consequence of this operational characteristic is that it is possible

to increase the sensitivity of the PEP-FPD system by increasing the total

sulfur concentration in the flame. We have verified this by adding a constant concentration of CH 3 CH2 SH to the hydrogen. A second consequence,

however is a complication of data reduction when one is attempting to

measure more than one sample component because the sensitivities are related to total sulfur concentration, not to sample component concentrations. We have solved this problem by developing a data acquisition/

reduction procedure that enables us to achieve simultaneous measurement of

aerosol and gas phase sulfur concentrations with sensitivities of 0.2

ygm S/m^ and 1 ppb respectively. Initial data comparison from an intercomparison study shows a very high correlation coefficient with data

obtained by a dichotomous sampler-x-ray-fl uorescence system.

189
We have shown the major limitation in response time of the technique

is in the FPD. (The commercially available FPDs have > 60 sec rise

times and ^ 1.5 sec fall times.) We have completed characterization of

a new FPD design which has symmetric rise and fall times of less than one second. This faster response time means the PEP-FPD system will be

capable of real-time measurements of ambient SO2 /SO4 concentrations under

conditions where the concentrations are dynamic, such as in plume traverses.

Additional research will be needed to improve the sensitivity and flow

stability of the fast-flame FPD to its full potential, though it now is

comparable to commercially available FPDs in those respects.

R. L. McKenzie, D. S. Bright, R. A. Fletcher

1 1 . Monte Carlo Electron Trajectory Calculation of Beam Spreading

Effects in Thin Foils in the Analytical Electron Microscope

Analytical electron microscopy (AEM) is a rapidly developing microanalytical technique with enormous potential for application throughout

the physical and biological sciences, as well as in many other problems

of technological importance. The AEM technique combines the transmission

electron microscope (TEM) with the scanning transmission electron microscope (STEM), resulting in a composite instrument which has the capability

of forming probes on the nanometer scale. Both energy dispersive x-ray

spectrometry (EDS) and electron energy loss spectrometry (EELS) are used

for analysis. A major question which is under current study at a number

of laboratories concerns the role of electron scattering in limiting the

spatial resolution of the technique, particularly at interfaces.

To investigate scattering in thin foils containing small structures

of different composition from the matrix, we have adapted the Monte Carlo

electron trajectory simulation technique previously developed in our group for bulk specimen analysis to the thin foil case [1]. Calculated

relative x-ray intensity profiles across interfaces in the FeO-MgO system

were found to be in good agreement with experiments published in the

literature [2,3]. These calculations were then extended to examine the

effects of beam spreading on quantitation methods for AEM analysis.

Quantitative analysis is usually carried out by means of a sensitivity

factor approach as suggested by Cliff and Lorimer [4]. This method

presupposes that the region under electron bombardment is homogeneous, a condition which is not achieved when beam spreading occurs at interfaces.

Monte Carlo calculations of the apparent concentration of iron in a pure

FeO slab at an MgO grain boundary as a function of slab width (w) and

foil thickness (t) are shown in figure 30. Only when the slab width is

large compared to the incident beam size does the calculated iron composition approach the true value (dotted line). The value of the broadening,

b, predicted by a simple model is shown for comparison [5]. Further

calculations and experiments will be made to develop deconvolution

techniques suitable for deriving accurate compositional values when fine

structures are analyzed in the AEM.

190
100- d

90-

Figure 30. Calculation of the apparent iron

concentration measured in a pure

FeO slab at an MgO grain boundary.

References

[1] Myklebust, R. L., Newbury, D. E., and Yakowitz, H., MBS Monte

Carlo Electron Trajectory Calculation Program, in NBS SP460,

Use of Monte Carlo Calculations in Electron Microscopy, 105-

128 (1 975).

[2] Hall, E. L., and Vander Sande, J. B., The Effect of Sample

Thickness on High Spatial Resolution Composition Profiles in

Dedicated STEM, in Proc. 37th Ann. Conf. Electron Microscopy

Soc. America, 474-475 (1979).

[3] Newbury, D. E., and Myklebust, R. L., Calculation of Electron

Beam Spreading in Composite Thin Foil Targets, in Microbeam

Analysis-1980, ed., D. Wittry, San Francisco Press, 173-175

(1980).

[4] Cliff, G., and Lorimer, G. W., The Quantitative Analysis of Thin

Specimens, Microscopy 103 , 230-207 (1975).

191
[5] Goldstein, J. I., Costly, J. L., Lorimer, G. W., and Reed, S. J. B.,

Quantitative X-ray Analysis in the Electron Microscope, in SEM/

1977, 31 5-324.

D. Newbury, R. Myklebust

12. General Expression Developed for the X-Ray Bremsstrahlung Intensity

Data

The quantitative electron probe analysis of samples with the

various methods based on peak-to-background measurements requires

detailed knowledge of the continuum (bremsstrahlung) as a function of

specimen and beam parameters [1-3]. During the developmental work on FRAME P, the NBS peak-to-background procedure for the analysis of

particles and rough surfaces, we attempted to use various functions from

the literature to describe the observed variations in the continuum

intensities, with respect to atomic number Z, accelerating voltage E^,

and x-ray energy E^ [4-6]. Since these functions did not adequately

describe the observed values of the continuum intensity we have been

developing an expression relating the continuum intensity, I, to Z, E and E . ° V

In this study, 1000 sec live-time spectra have been run for 44 pure

element targets at E^ values of 10, 15, 20, 25, 30, and 40 keV. Intensity

values for several different energy windows were determined for each

spectrum. The midpoint energy of each window was used as the value for

E^. The measured x-ray intensities, were converted to generated intensities by correcting for target absorption, electron backscatter loss,

detector absorption, and incomplete charge collection.

A computer was used to fit equations for I vs. Z at the various E^

values. It was found that all the curves fit the general equation I=az'^.

Figures 31 and 32 are plots of [-£n(a)] and n as a function of (E^/E^)-l

where is equal to the overvoltage, U. Two important aspects of a and n which are shown by the plots are: First both plots follow the same

general family of curves, hence the overvoltage dependence is the same or similar for both terms; second, the plots show that the two terms have a minimum at a U-1 value of about 10. We are currently working on development of expressions to define the dependence of a and n on overvoltage.

References

[1] Small, J. A., Heinrich, K. F. J., Fiori, C. E., Myklebust, R. L.,

Newbury, D. E., and Dilmore, M. F., The production and characterization of glass fibers and spheres for microanalysis, SEM/1 978/1.,

445-454.

192
- Lna

-Ln a in equation I = aZ vs. U-l

Figure 31. Plot of -In a vs. U-l for different

values of E^.

0

Values of n in equation I = oZ" as function

Figure 32. Plot of n vs. U-l for different values

'o193
[2] Statham, P., and Pawley, J., A new method for particle x-ray

microanalysis based on peak-to-background measurement, ibid.,

469-478.

[3] Small, J. A., Newbury, 0. E., and Myklebust, R. L., Analysis of

particles and rough surfaces by FRAME P, a ZAF method incorporating

peak-to-background measurements. Microbeam Analysis--! 979,

San Francisco, San Francisco Press, 243 (1979).

[4] Kramers, H. A., On the theory of x-ray adsorption and the continuous x-ray spectrum, Phil . Mag . 48 , 836 (1923).

[5] Smith, D. G. W. , Gold, C. M., and Tomlinson, D. A., The atomic

number dependence of the x-ray continuum intensity and the

practical calculation of the background in energy dispersive

electron microprobe analysis. X-ray Spectroscopy 4, 149 (1975).

[6] Statham, P. J., Generation, absorption and anisotropy of thicktarget bremsstrahl ung and implications for quantitative energydispersive analysis. X-ray Spectroscopy 5, 154 (1976).

J. A. Small, D. E. Newbury, R. L. Myklebust

13. Development of a Sequential Simplex Procedure for Resolving

Spectral Interference in Energy Dispersive X-ray Spectrometry

The lithium-drifted silicon [Si (Li)] detector has become an established

tool in x-ray spectrochemical techniques such as x-ray fluorescence

spectrometry and electron probe microanalysis. The instrumental response

of the Si (Li) detector is closely approximated by a Gaussian distribution

having a width at 1/2 the peak height which is about 100 times the natural

peak width of an x-ray line. In order to resolve individual x-ray peaks

in an x-ray spectrum containing overlapping peaks, we have developed a sequential simplex procedure for optimal selection of the parameters in a mathematical expression that describes a spectral peak [1]. In this

procedure, each of the n independent variables in the function to be

fitted is assigned an axis in an n-dimensional coordinate system. A

simplex, in this coordinate system, is defined to be a geometric figure

consisting of n + 1 vectors. The simplex is moved toward the set of

independent variables that optimize the fit according to a set of specific

rul es

.

The energy-dispersive x-ray peaks were assumed to be Gaussian line

profiles; therefore, the function to be fitted is:

Y.=

J

n2

i=l

E.-E.

A,exp[-l/2{-!—!-)2]

y rr

.

(

1 )

194
where Y. is the intensity at energy E., n is the number of x-ray peaks

J 'J and A^. , E^. , and a. are respectively the amplitude, energy and width of

peak i. For each peak, the parameters to be determined are A^. , E^.

,

and . The total number of independent variables (n) is therefore 3n.

We have reduced the number of variables by: (1) determining the energies

of all minor peaks from the energy of the principal peak; and (2) determining the widths of all minor peaks from the width of the principal

peak. This reduces the number of independent variables to n + 2 thereby

improving the chance of obtaining a good fit with a minimum of computer

time [2].

This procedure has been used to determine the K^/ZK line ratios for

elements of atomic number 15-32 by energy-dispersive analysis [3].

The method allows us to separate x-ray lines that are separated by only

60 eV when the resolution of the detector is 160 eV. The procedure was extensively tested this year and is now being extended to the determination of the L line ratios.

References

[1] Spendley, W., Hext, G. R., and Hinsworth, J. R., Technometrics

4, 441 (1962).

[2] Fiori, C. E., and Myklebust, R. L., 1978 DOE Symposium Seris

CONF-780421 , p. 139.

[3] Heinrich, K. F. J., Fiori, C. E., and Myklebust, R. L., J. Appl

.

Phys . ^

(9), 5589 (1979).

R. L. Myklebust

14. Development of a New Procedure for Calibration of a Crystal

Spectrometer for Relative Line Intensity Measurements

In recent years quantitative electron probe micro-analysis (EPMA)

with energy-dispersive x-ray spectrometry (EDS) has been proved to be as valid as wavelength dispersive (WDS) analysis in most cases. The major

limitation though of EDS is its poor resolution, which necessitates

data reduction procedures to make peak-overlap corrections. Such corrections require accurate knowledge of relative x-ray line intensities.

For the elements phosphorus to germanium, K-line ratios have been

determined by several authors, including a group from this laboratory

[1 ] . Accurate determinations of the K-lines have been made possible by

EDS where detector efficiency corrections can be calculated for contribution from the beryllium window, gold contact layer, silicon dead

layer, and detector acceptance angle. Overlaps between lower atomic

195
number K and peaks can be easily handled by a modification of a a 3

simplex procedure [2].

Because the overlap of L-lines in EDS is far more extensive EDS

cannot be used for relative line intensity measurements in a large

number of cases. The resolution of the L-lines in WDS is far better.

Unfortunately, contributions to the detector efficiency of a crystal

spectrometer cannot be calculated as easily as in EDS.

We therefore have developed a procedure for calibrating a lithium

fluoride crystal spectrometer by using the and lines for elements

titanium through arsenic. The Cameca electron microprobe was used at a beam energy of 20 keV. A novel technique for recording WDS data was developed for this work. Using a multichannel analyzer (MCA) in the

multichannel scaling mode, we made a very slow pass through each characteristic x-ray line. The MCA memory is sufficient to store a single

x-ray line plus background on both sides of the peak. An example of a spectrum obtained in this way is shown in figure 33.

ENKR 1X20

Figure 33. Wavelength spectrometer scan of Zinc peak

as recorded on digital multichannel scalar.

A ratio of the background-corrected integrated intensity of the WDS

x-ray line divided by the corrected EDS integrated intensity

(Ieds^ x-ray line was calculated. This ratio is expressed

^WDS^^ ^EDS^^^E^

where is the EDS detector efficiency correction (the

sample absorption term cancels out as it appears in both numerator and

denominator.) A plot of this ratio versus x-ray line energy gave a smooth curve as illustrated in figure 34. This curve now can be used to

make appropriate detector efficiency corrections to the L-lines detected

196
Figure 34. Plot of ratio of net integral intensities

measured by wavelength and energy disper- ^ sive spectrometry techniques versus peak

energy.

with the same crystal spectrometer at the same excitation potential.

With this calibration, in addition to the overlap corrections, better

relative line intensity data for L-lines should soon be available.

References

[1] Heinrich, K. F. J., Fiori , C. E., and Myklebust, R. L., Relative

Transition Probabilities for the X-ray Lines from the K Level,

J. Appl . Phys . M, 5589 (1979).

[2] Fiori, C. E., and Myklebust, R. L., A Simplex Method for Fitting

Gaussian Profiles to X-ray Spectra Obtained with an EnergyDispersive Detector, Proc. of the ANS Conf. on Computers in

Activation Analysis and Gamma-ray Spectroscopy, Mayaquez, P. R.,

1978 DOE Symposium Series, CONF-780421 , p. 139.

R. Marinenko, R. Myklebust

1 5. Successful Raman Microprobe Analysis of Opaque Particles

The Raman microprobes now in use employ high intensity (from a few kW/cm^ up to 1 MW/cm^) visible CW laser excitation to elicit

197
diagnostically useful vibrational spectra from discrete microparticles or spatially resolved sampling volumes approaching one picogram in mass

[1-3].

While numerous applications have been successful, a major limitation

of Raman microprobe analysis arises when the measurement is performed on intensely colored, highly opaque microsamples that absorb a large fraction

of the exciting radiation. Dark materials (in the liquid or solid

phase), until recently, produced unusable results because of laserinduced heating of the sample with attendant modification or decomposition

even under the lowest practical irradiance conditions. The usual expedient of using an alternate excitation wavelength (e.g., choosing the 647.1

nm red line over the 488.0 nm blue line from an Ar-Kr ion laser) and

reducing the energy density focused into the sample often will neither

greatly minimize nor circumvent the problems associated with sample

heating from significant optical absorption. Thus, dark and opaque

microsamples, without some means of effective heat dissipation, are either too weakly scattering or highly reflecting to furnish useful

results, or yield spectra that are difficult to interpret due to sample

tranformation.

To better cope with these experimental difficulties, special sample

preparation techniques have come under study to permit obtaining the

spectra of deeply colored microsamples.

One of the most successful methods consists of encapsulating particles,

supported on a sapphire substrate, in a spectroscopically non-interfering

dielectric film which efficiently enhances thermal sinking into the

substrate. By embedment in a thin, glass-like layer of sodium silicate

(i.e., water glass), the spectra of opaque particles have been recorded

(with 514.5 nm green line excitation) where this was not possible before.

Particle samples are coated with this encapsulating, glass film either by

spreading of the liquid silicate or by forming the film through application

of the silicate solution as a finely divided spray. The initially liquid

film deposited by either of these procedures quickly dries to a hard,

transparent film. In measurements on samples without the silicate

overcoat, the mounting medium is air providing poor heat conduction

across the particle/substrate interface. The spectra of figure 35 are those of opaque microparticles of black uranium oxide [4] — a most

difficult scattering case — that could only be obtained by immersion in

the silicate matrix. The top spectrum is that of a mixed uranimum oxide/

thorium oxide microsphere showing the expected Raman bands at the respective characteristic frequencies (i.e., at 445 and 467 cm“M- The bottom

spectrum is that of a particle of synthetic, singl e-crystal uranium oxide

also embedded in the silicate overcoat. Similarly, the spectra of single

particles of many other types of highly absorbing solids (e.g., Fe203 , Cr203 , V2 O 3 , W2 C) have been recorded using this method of sample preparation. The technique has further proven itself in microprobe studies on particulate samples of black carbon materials, including coal, oil-soot

198
800 400 0

>-ICO

LU

hRAMAN SHIFT (A cm')

Figur© 35. Raman microprobG spGctra of uranium oxide particles embedded

in a silicate film. Measurement conditions are indicated.

Bands marked S arise from the Raman scattering by the

sapphire (,a-Al 203 ) substrates.

199
ash, and graphitized polymeric fibers. Intensely colored silicate

minerals (e.g., crocidolyte asbestos) and absorbing, photosensitive

organic solids (e.g., nitro compounds) have yielded spectra indicating

effective thermal stabilization of the irradiated sample by immersion in

the silicate matrix.

References

[1] Etz, E. S., Raman Microprobe Analysis: Principles and Applications, SEM/1979/I, SEM, Inc.: AMF O'Hare, IL 60666, 67-82.

[2] Blaha, J. J., and Rosasco, G. J., Raman Microprobe Spectra of

Individual Microcrystals and Fibers of Talc, Tremolite and

Related Silicate Minerals, Anal . Chem . 50 , 892 (1978).

[3] Abraham, J. L., and Etz, E. S., Molecular Microanalysis of

Pathological Specimens in situ with a Laser-Raman Microprobe,

Science 206, 716 (1979).

[4]

Keramidas, V. G., and White, W. B., Raman Spectra of Oxides with

the Fluorite Structure, Chem . Phys . 59 , 1561 (1973).

E. S. Etz, J. J. Blaha

1 6. Development and Characterization of a New Raman Microprobe With

Multichannel Optical Detector

The Raman microprobes that have come into use in recent years

employ CW laser excitation and basically make use of a scanning spectrometer (i.e., a monochromator) with conventional single channel (cooled

PMT) detection [1-3]. These instruments yield analytically useful

vibrational spectra from discrete microscopic objects (e.g., particles)

or sample regions with dimensions of a few micrometers (e.g., inclusions).

They have been applied with good success demonstrating detection limits

lower than 1 pg for scattering species in optically transparent sampling

volumes [2]. Yet, microanalysis performed with these scanning instruments

suffers from several shortcomings. Drawbacks result from primarily two

factors. These are (1) the long (tens of minutes to hours) instrumentallyimposed time required to obtain a spectrum with monochannel detection,

and (2) the often severe optical constraints of the measurement wherein

the sample absorbs a fraction of the incident (visible) laser light

leading to complications from sample heating or photochemistry. These

problems can, in principle, be minimized or circumvented by microprobe

instrumentation employing spectrographic dispersion with sensitive

multichannel detection.

We have explored the advantages of this approach by developing (in

collaboration with Instruments SA, J-Y Optical Division) a prototype

Raman microprobe with multichannel optical detection (figure 36). This

200
Figure 36. Schematic of the newly developed Raman

microprobe.

new instrument has just become fully operational and is presently undergoing extensive performance characterization. Results obtained with this

instrument demonstrate the spectral multiplex advantage in the analysis

of "difficult" (e.g., optically absorbing or photosensitive) microsamples.

This development has utilized commercially available equipment consisting

of (1) two gas lasers (Ar and Kr ion) as mul tiwavel ength excitation

sources, (2) a standard microscope for observation of the sample and

excitation/collection of the scattered radiation, (3) a triple spectrograph of novel design for dispersion of the Raman spectrum, and (4) a multichannel detection system utilizing a cooled SIT vidicon. A separate,

second detection system consists of a conventional photomultiplier tube

(PMT) with photon counting electronics and permits scanning or spectrometric recording of spectra.

A spectrum from the measurement on single microparticles using

the multichannel instrument is shown in figure 37. The sample examined

here is a microscopically small polymer latex particle. The experimental

parameters are indicated. The spectrum was acquired in only three minutes

of signal integration. This represents a time advantage in the acquisition of the spectral "fingerprint" of a factor of about 18 compared to

the corresponding spectrum of comparable signal -to-noise obtained in a

201
WAVELENGTH, nm

Figure 37. Raman spectrum of a latex microparticle obtained

with multichannel detection.

conventional microprobe with a scanning spectrometer. Moreover, since

the polymer is subject to time-dependent, slow decomposition even under

conditions of moderate laser irradiance, these potentially adverse

effects attributable to sample instability are in many cases not encountered

and not observed in the example given here because of the fast, signal

acquisition time.

The instrument was developed with support from the Air Force Technical

Applications Center (AFTAC) and is now in use at an Air Force materials

analysis laboratory on the West Coast.

Studies now in progress in cooperation with AFTAC are aimed at a more complete under-standing of the performance capabilities and intrinsic

limitations of the new instrument. Current developments in radiation

dispersion and detection systems are significant to further advances in

this field of spectroscopic instrumentation.

References

[1] Dhamel incourt, P., et al .

,

Laser Raman Molecular Microprobe

(MOLE), Anal . Chem. 51, 414A-421A (1979).

202
[2] Etz, E. S., and Blaha, J. J., Scope and Limitations of Single

Particle Analysis by Raman Microprobe Spectroscopy, in Characterization of Particles, NBS Spec. Publ . 533, K. F. J. Heinrich,

ed., U.S. Government Printing Office, Washington, D.C., 153-197

(1980).

[3] Rosasco, G. J. , Raman Microprobe Spectroscopy, in Advances in

Infrared and Raman Spectroscopy, Vol . 7, R. J. H. Clark, and

R. E. Hester, eds., Heyden & Son, Ltd., London, 223-282 (1980).

E. S. Etz

17. Ion Microprobe and Laser Microprobe Mass Analysis of Inorganic

Particulates

Three microbeam instruments that use mass spectrometers as detectors

have been investigated and compared with respect to the analysis of

individual particles. Two of the instruments are based on ion sputtering. The ion microprobe uses a sputtering beam diameter as small as 2 ym

to obtain a localized analysis. The ion microscope, on the other hand,

sputters with a considerably larger ion beam. However, in this case,

sputtered ions preserve their spatial relationship through the mass spectrometer, and localization of the analyzed area is achieved by

limiting the field of view of the detector with an appropriate aperture.

The laser microprobe uses a pulsed laser beam that can be focused to a diameter of 1 ym or less to vaporize and ionize a small volume of material.

Since the ionization event is localized in time, a time-of-fl ight mass spectrometer is employed for mass analysis.

Samples used for this investigation were microchips and microspheres

of research glasses manufactured at NBS. For the ion beam instruments

the samples were dispersed on 0.5 cm diameter high-purity gold disks.

For the laser microprobe they were dispersed on formvar-coated transmission

electron microscope grids. The size range of the glass particles was 1-

1 5 ym.

An example of comparative data from the three instruments is shown

in Table 16. In this case the samples were spheres of a glass containing

80 percent PbO and 20 percent Si02 by weight. The Pb and Si ion signals were measured from several particles of different sizes to determine the

relative sensitivity of the two elements and its variability from

particle to particle. The table indicates that the relative sensitivity

differs by less than a factor of 2 among the three instruments in this case. The relative standard deviation (RSD) of the sensitivity ratio is

highest for the laser microprobe. This result reflects a lack of

reproducibil ity of ionization conditions among particles of different

size as well as insufficient data density of two or three data points per mass peak when a wide mass range is recorded.

203
Table 16. Lead - Silicon Sensitivity Ratios from K227 Microspheres

Ion Ion Laser

Microprobe Microscope Microprobe

No. of particles 10 5 8

^Pb^^Si

2.13 3.44 2.67

SD 0.34 0.24 2.14

Relative SD 16 7 80

Table 17 indicates the capability of the three instruments to

measure isotopic ratios of Pb in these same microspheres. The higher

precision of the ion microprobe measurements is attributable to an electrostatic peak-switching system that allows isotope ratio measurements

to be taken without changing the magnetic-field setting of the mass spectrometer. The relatively low precision of the laser microprobe is a result of the 8-bit resolution of the transient recorder that is used to

measure and store the mass spectrum in 256 discrete levels. This characteristic also restricts the dynamic range of signals that can be measured

in one spectrum and sets a practical limit of about 10:1 on the magnitude

of an isotopic ratio that can be measured with the laser microprobe. The

ion microscope produces well-defined trapezoidal peaks that vary in

intensity by less than 0.2 percent over the flat portion of the peak top.

One would therefore expect the variation in isotopic ratio of a given

element among a group of particles to be less than one percent, but

that is not the case. A computer-controlled cyclic mass scan is used to

measure the peak intensities in sequence for the isotope ratio calculation. Improvements in interparticle precision may occur through the use of a different software routine that minimizes the effect of magnetic

hys teres i s

.

The true isotopic ratio of the Pb in these particles has not been

measured, but the best estimate for naturally occurring Pb is shown in

Table 17. Any bias in the measurement of the ratios in the particles

could be corrected by comparison with a standard of known Pb isotopic

composition

.

204
Table 17. Isotopic Ratios of Lead from K227 Microspheres.

Ion

Microprobe

Ion

Microscope

Laser

Microprobe

Natural

Lead

No. of particles 10 6 4

206/208 0.461 0.511 0.53 0.461

R.S.D. {%) 0.6 3.4 15.4

207/208 0.412 0.451 0.47 0.422

R.S.D. (%) 0.2 3.7 9.6

206/207 1 .098 1 .140 1 .15® 1 .093

SD 0.011 0.005 .09

Relative SD 1 .0 0.4 7.8

^13 particles for 206/207.

Table 18 summarizes some of the special features of each of the

three instruments as applied to particulate analysis. It is apparent

that no single instrument is the best choice for all situations. The ion

microprobe can measure isotope ratios with high precision. The ion

microscope has a variety of features that give it great versatility to

handle different analytical problems, for example, the ability to screen

a field of particles for a particular element by use of the ion-imaging

mode of operation. Finally, the laser microprobe can acquire full mass spectra from many particles at a very rapid rate, and is the easiest

instrument to use for the analysis of very small particles.

Table 18. Special Features of Three Instruments for Particle Analysis.

Instrument Special Features

Ion microprobe

Ion microscope

Laser microprobe

D. S. Simons

High precision isotopic ratios

Rapid ion imaging of a particle field

Faraday cup or electron multiplier detector

High abundance sensitivity spectrometer

Molecular ion rejection by energy offset

High mass resolution

High resolution optical microscope

Rapid analysis (30-60 particles/hr.)

Ease of analysis of small particles (0.5-2 ym)

205
18. Evaluation of Counter Error in the Development of Asbestos

Standards for the Electron Microscope

The Environmental Protection Agency (EPA) has been monitoring the

concentration of asbestos in ambient air, because of its potential

adverse health effects, using an electron-microscopic analysis of filtered

air particulates.

During a number of interlaboratory studies, EPA found that the

reported asbestos concentrations varied among laboratories by up to five

orders of magnitude on the same filter. Many laboratories consistently

reported relatively high or low results, in part due to operator bias or error, filter inhomogeneity and counting statistics. Generally, because

of the high magnifications used during analysis, only approximately

1/100,000 of the total filter area was observed. The data from this

small area was then extrapolated to the whole filter to determine the

relative concentration.

Because of these problems with asbestos analysis, EPA requested NBS

to prepare filters with known asbestos fiber concentrations that are homogeneous on the level of a . In attempting to approach as closely

as possible the true asbestos fiber concentration on the filter NBS has

used up to five microscopists to analyze the same areas of filters.

These areas were then sent to other experienced laboratories for analysis.

The results are shown in Table 19. The variability of these counts both

within NBS and at other laboratories was considered excellent by EPA.

But these results could not be correlated to determine where the errors

in analysis occurred. Also, it was felt that an average or mean value as reported in column 1 of Table 19 for the five NBS operators was not

necessarily an accurate description of the number of fibers on the areas counted. For these reasons a digital specimen positioner was designed at

NBS so that individual fibers could be uniquely identified by their X-Y

coordinates. Three to five NBS operators counted the same 75 ym x 75 ym

area, recording each fiber's X-Y position. Then the counts were correlated

and finally the area was reanalyzed to verify all fibers. In this way it was felt that the verified fiber count was as close as possible to the

true concentration. Table 20 shows some of the data recently collected

using this method. This table shows each operator's error as number of

fibers counted and how many of these were incorrect counts, how many

fibers were missed, and the verified concentration.

206
Table 19. A Comparison of Asbestos Fiber Counts from Four Laboratories

for Nine Areas. (Number of Fibers per '’W5 ym x 75 pm area).

Laboratory (NBS)

Area (Five Operators) (2) (3) ill

1 32.6 ± 2.5 23 42 22

2 31 .8 ± 1 .6 32 36 33

3 27.6 ± 1.5 22 23 22

4 15.8 ± 1.5 16 13 15

5 49.8 ± 4.4 33 32 40

6 51 .0 ± 2.3 37 40 45

7 53.2 ± 3.7 35 39 44

8 53.0 ± 3.5 33 38 42

9 39.0 ± 1 .6 22 30 40

Operator Error Data for a 75 ym X 75 ym Area Using a Verifi

Counting Technique Based Upon an NBS Designed Specimen Posi

Digital 1Readout.

Operator

Total Fibers

Counted

Fibers Not

Counted

Fibers Incorrectly

Counted

Verified Fi

Counted

1 31 2 7 26

2 24 2 0 26

3 20 8 2 26

4 25 1 0 26

Knowing the error associated with the five NBS operators and using

the verified fiber counts allows work to proceed in characterizing fiber

distribution and concentration of the final product, an asbestos filter

standard.

E. Steel

19. The Development of Thin Glass Films As Potential Standards

for X-ray Spectrometric Calibration"

X-ray fluorescence spectrometry has proven to be a versatile and

rapid method for multielement analysis in many analytical applications.

Of particular interest are substances which can be analyzed in the form

207
of a deposit on a filter, mesh or membrane, or as a thin pressed pellet.

Collected airborne particulate matter, particulates in waste water and

geochemical samples are just a few examples of this type. In some respects

such "thin samples" are ideal for x-ray fluorescence analysis because the

detection limits are suitably low and interelement effects such as x-ray

absorption and/or enhancement are negligible. The absence of any sizable

interelement effects makes possible a linear instrument response to

element mass per unit area. Spectrometer calibration for analysis of

such samples is usually performed with thin samples containing known

concentrations of the analyte(s) of interest. Some problems associated

with the "thin specimen model" are x-ray self-absorption in particles

(notably for the light elements such as A1 , Si, P, and S) commonly

referred to as particle-size effects, and self-absorption in the substrate.

Both of these effects require the application of correction factors.

Therefore, the basic premise is that accurate multielement analysis of

thin samples can be performed based on the thin specimen model, together

with empirical or theoretical correction factors.

There are several important criteria which need to be met if thin

samples are to be acceptable for calibration purposes. First, the

uniformity of the sample as well as its homogeneity must be within an acceptable well-defined tolerance limit. If the sample contains

particulate matter, both the size and distribution should be characterized.

Secondly, the mass loading of the sample must be known to an acceptable

degree of accuracy. And finally, the sample should possess sufficient

durability and integrity.

The goal of a joint program between NBS and the U.S. Environmental

Protection Agency (EPA) was to perform the research and development

required to produce thin standard samples especially useful for calibration

of x-ray fluorescence analysis of collected airborne particulate matter.

For this purpose we have investigated several candidate methods for

preparing such samples.

One method which shows great promise is the deposition of thin films

of glass containing known concentrations of several elements of interest

on polycarbonate substrates by a technique known as focused ion-beam

sputtering. Ion-sputtering essentially involves the transfer of atoms

and/or molecules from a target to a substrate by the action of an ion

beam (usually argon) incident upon the target. The ion beam is accelerated

at high potential (700-1100 volts with a flux of about 0.5 mA/cm^ toward

the target at a 45® angle. Since the substrate is not in the plasma

environment, substrate damage does not occur. This is a distinct advantage

of this particular sputtering technique. Other advantages to be gained

are: (1) production of thin films from synthetic materials such as glasses of known elemental composition which can be varied as desired;

(2) high adherence of the glass to the substrate which obviates the need

for overcoating to maintain sample integrity; and (3) easy control of the

glass mass loading on the substrate by variation of the sputtering time.

208
Several studies were performed with glass targets fabricated at NBS

which allowed up to eight 47 mm substrates to be coated at one time.

Instrumental parameters such as ion acceleration voltage and ion current

were systematically varied to determine their effect on film composition.

It was found that rather severe changes in these parameters often do not

affect the film composition by more than ± 15 percent. Glass films

sputtered from targets containing phosphorous and sulfur were also

prepared to demonstrate the feasibility of preparing films containing

elements of low atomic number.

In Table 21 are summarized the elemental composition of three

sets of films at mass loadings ranging from 167 to 185 yg/cm^ which were

prepared at various times. These data demonstrate that the compositional

reproducibility of thin films from set to set is satisfactory for the

purposes of preparing standard films.

Multi-element thin standards suitable for calibration purposes

can be fabricated by the focused ion-beam sputtering technique. In order

to include all the elements of interest in any particular film, several

glass targets would need to be fabricated. It is believed that these

films would be useful to monitoring agencies such as ERA for assessing

environmental impact of airborne particulate matter. Work is now in

progress to prepare several sets of films which will be certified by the

Office of Standard Reference Material as NBS Standard Reference Materials.

P. A. Pella, E. C. Kuehner, J. Sieber

209
Table

21.

Reproducibility

of

Thin

Glass

Films

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210
20. Low Velocity Wind Tunnel Facility for the Evaluation of Personnel

Dosimeters

A low velocity wind tunnel has been designed, constructed and

characterized. The tunnel enables us to produce aerosol and gas samples

of known component concentration and flow profiles for evaluation of the

efficiencies of aerosol and gas sampling devices. The tunnel consists of

a high efficiency absolute filter at the inlet, followed by a mixing grid

to flatten the flow profile and an injection section for the introduction

of aerosol or gas samples. The test or sampling section of the tunnel

(12 feet downwind of the injection section) has a 2-dimensional automated

traverser which enables us to accurately position and locate velocity or sample probes in order to measure the velocity and sample concentration

profiles in the tunnel. The maximum velocity is - 3 m/s. The velocity

profile is flat to better than 10 percent in the cross-section of the

tunnel beyond the 2 inch wall boundary layer. There is very low mixing

in the tunnel so that when a point-source injection system- is used, we obtain sample profiles that are quite steeply parabolic. For multiple

sampler testing we will need to use either multiple injection or more

severe mixing to broaden the sample concentration profile.

We have used the wind tunnel to evaluate a personal ambient aerosol

sampler (PAAS) that is currently under development at NBS. The two

components of the PAAS--the aerosol sampling/collection section and the

sampling pump--have been evaluated separately. Eight different pumps

have been evaluated for power requirements, pumping efficiency and flow

stability. A pump has been selected that provides 5-6 liters per minute

for periods greater than the desired sampling period of 8 hours and has

low power consumption (Bendix BDXX55). The pump was tested under load

conditions on the sampler that exceed loading conditions normally found

in field applications.

The aerosol sampler selected is a two stage series filter system

using a 37 mm diameter, 8 ym nucleopore filter followed by a high

efficiency teflon filter. The sampler is to divide and collect ambient

aerosol in two size fractions. The first filter (8 ym nucleopore) will

collect respirable particles (about 2 to 15 ym diameter) and the second

filter (teflon) will collect the remaining smaller particles. The cutoff size (particle size at which the filter is 50 percent efficient) was determined for the nucleopore filter using monodisperse aerosols generated

by a vibrating orifice aerosol generator. Fluorescein aerosol was used

to enable accurate spectrophotometric determination of low aerosol

concentrations on the filters. The filter collection efficiency for the

nucleopore filter is presented in figure 38 as a function of particle

aerodynamic diameter where aerodynamic diameter is a parameter that

normalizes particles (regardless of shape) in terms of aerodynamic

behavior for a unit density sphere. The collection efficiency for the

first filter is defined as the aerosol concentration on the first filter

divided by the sum of the concentrations on the first and second filter

(total aerosol collected by the sampler). The sampler has the desired

211
R. L. McKenzie, D. S. Bright, R. A. Fletcher

21 . Enhanced Detection of Molecules Near a Surface by Raman

Spectroscopy Excited by Evanescent Waves

Raman spectroscopy is an increasingly important technique for

specific detection of molecules. Its use has been severely limited in

detecting and identifying small numbers of molecules by the extremely

212
weak signal that usually results from Raman scattering. Recently a greatly (lO'^-lO^) enhanced signal has been observed for many types of

molecules adsorbed in vacuum and bound in solution to an electrode

surface for some metal surfaces. This surface enhanced Raman spectroscopic (SERS) signal has been used to study the identity, surface bonding

character, and orientation of adsorbed molecules.

In two related experiments performed at Yale University (with

Professors R. K. Chang and R. E. Benner in the Department of Engineering

and Applied Science), we examined the Raman spectra produced by molecules

at or near (within lOOOA) the surface of a prism. A hemicyl indrical

prism with a 500A layer of evaporated silver on the flat face was oriented with the flat face toward the Raman spectrometer. Molecules of

interest were placed on the flat side (see figure 39) and a laser beam was directed through the curved surface at angles with respect to the

flat face equal to or greater than the critical angle for total internal

reflection of that incident beam. The electromagnetic field which

oscillates at optical frequencies, does not propagate from the prism into

the less optically dense material (i.e., the sample), but does produce an oscillating electromagnetic field, called an evanescent field, which

decays exponentially in amplitude with distance from the interface. The

evanescent field decays to 1/e of its value at the interface in 100-200

nm. Evanescent excitation was used in our experiments to investigate the

role in SERS of collective excitation of electrons (surface plasmons) in

a silver film on the prism surface. A paper which discusses the one order of magnitude enhancement of Raman scattering by surface plasmons in

SERS is soon to be published in Surface Science. A second paper (in

preparation) describes the first use of Raman spectra as a probe of the

orientation of the evanescent field with respect to the surface with and

without surface plasmon enhancement. This new data and associated

calculation will provide a basis for useful measurement of molecular

orientations near an interface.

213
Figure 39. Geometry for evanescent wave-excited Raman

Spectroscopy.

I . Chabay

22 . Statistical Evaluations of the International Radiocarbon Cross Cali - bration Exercise, and of the Natural Radiocarbon Fluctuations

High accuracy natural radiocarbon measurements are of critical

importance in a number of fields, ranging from archeology to climatology

to environmental science. In addition to our current activities related

214
to the calibration of the new International Standard for Radiocarbon

Dating (replacement for SRM 4990B), we have contributed to the numerical

evaluation of interlaboratory data representing a) high precision measurements of homogeneous primary and secondary natural radiocarbon standards,

and b) the "calibration" relationship between radiocarbon concentrations

and calendar age as deduced from dendrochronology (tree ring measurements). The first activity is important for assessing the relative

activity of the three "standards" and for identifying error sources and

limits (random and systematic) among the best laboratories internationally.

Deliberations on the second topic culminated in the organization of the

International Committee for the Calibration of the Radiocarbon Time

Scale, to which NBS scientist, Lloyd A. Currie, is an advisor. The fine

structure of the radiocarbon dating calibration curve -- i.e., long-term

trends and short-term fluctuations about the simple exponential decay

model -- is important for two major reasons: a) fine structure must be

adequately evaluated/fitted to achieve accurate dating, b) modeling of

the fine structure provides a means for us to learn more about the

history of the earth (climate, environmental changes, ocean circulation,

solar activity, etc.).

a. Exploratory Analysis of the International Radiocarbon

Cross-Calibration Data: Consensus Values and Interlaboratory Error

Data from the international cross-calibration exercise have provided

an important opportunity to assess the state-of-the-art of high-precision

natural radiocarbon measurement and to derive consensus values for two

relatively pure and homogeneous materials relative to the international

radiocarbon dating standard (NBS Oxalic Acid, SRM-4990B) . Performance

was good: some fifteen laboratories returned results for the two independent ratios -- Australian National University Sucrose/Modern Standard

(S/M) and 1850 Wood/Modern Standard (W/M) -- with a typical imprecision

(standard deviation) of about five percent per mil; and the distribution

of results was relatively narrow. The primary limitations encountered

were incomplete laboratory data and variable reporting practices.

Analysis of the data led to the following observations:

• Imprecisions (standard deviations) reported varied from about two

percent per mil to eight percent per mil, with one laboratory

reporting 28 percent per mil. Most, but not all, imprecisions

represented counting statistics only.

• Apparent blunders (large deviations from consensus values) occurred

in a few cases, especially for estimates of the ratio S/M.

• "Laboratory error," a -- i.e., a non-Poisson error component --

A was estimated from the data distributions for both sample ratios.

Results were similar: for S/M, d = 3.5 percent per mil; for

A W/M, =1.8 percent per mil. These error estimates, though

215
rather uncertain because of the limited number of degrees of

freedom, are consistent with earlier estimates, and they may

reflect the accuracy limit for current counting techniques.

• Consensus ratios, following the use of exploratory techniques to

identify blunders, and taking into account "laboratory error" and

varying Poisson imprecision, were = 508.1 ± 2.0 percent per

mil (1850 Wood, age-corrected for decay to 1950). (Uncertainties

represent one standard error, and both S and W are normalized to

§130 = _25 percent per mil.)

Further results of the evaluation include distributions and the

search for measurement method-, sample nature-, and isotope fractionationrelated effects. (See figure 40 for histograms of the intercomparison

resul ts .

)

b. Calibration of the Radiocarbon Time Scale

Evaluation of the structure of the radiocarbon calibration curve is

critically important both for accurate dating (as shown in figure 41)

and for geophysics and climatology (figure 42). At the present time,

because of the remarkable precision of natural radiocarbon measurements

and the unique time (8000 year) record provided by dendrochronology,

radiocarbon is the only radionucl ide capable of giving us direct information on past fluctuations in solar activity. When combined with geophysical

modeling and ice core measurements of the ancient atmosphere (CO2 ), the

14c variations will yield further insight into the history of the carbon

cycle and prognosis for "the CO2 problem."

216
CROSS-CALIBRATION HISTOGRAMS

(corrected deviations, in o/oo)

S/M

530 W/M S/W

525

515

520 10 S 525 .'’1L 1 , 5 q 520 G k m

510 AAll 0 d j L 515

505 E F'L 0 -5 A B E G h| 510 A E F

500 B d m R -10 F k 0 505 B

495 hi -15 m P 500 d h L

490 495 c j P s

485 I

480 P

• S, M, W = Sucrose, Modern Standard, Wood

• Qj = 2°/oo - 40/00 (Cap.); 50/00 - 8 0/00 (Lower Case)

Figure 40. Histogram of the radiocarbon ratios for ANU sucrose (S), 1850

wood (W) and the modern standard (M; 0.95 x NBS oxalic acid).

Numerical scales are expressed as deviations (in parts-perthousand) from unity from each of the three ratios; and

laboratories are coded alphabetically.

217
CONVENTIONAL

RADIOCARBON

DATES

IN

RADIOCARBON

YEARS

BEFORE

PRESENT

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S-o c: >, O CD t- O

(O fD o

OJ > s- c O S- ^ o o OJ •!- S- M 1— ^ ^ c TO O C V- O O <L) •'— >> C 4-> +-> 4-> o O

(O

C JD 1—

U -r- S- o •r- TO TO to ‘4- -M O JD • 1- S- o et C O) TCD U -O -O

(O

C TO

C

s: o s- TO : ]i

OJ

S-cn

218
RADIOCARBON

AND

SOLAR

ACTIVITY

219

Figure

42.

Correlation

of

radiocarbon

fluctuations

with

solar

activity

(sunspots)

and

climate

in

figure

is

taken

from:

Eddy,

J.

A.,

The

Maunder

Minimum,

Science

192,

1189

(1976).

The

lower

figure

is

taken

from

figure

on

p.

615:

Mathews,

S.

W.,

What's

Happening

to

Our

Climate,

National

Geographic

150,

576

(Nov.

1976).
Objectives of the International Committee are to assemble high

quality data and to utilize geophysical and statistical -mathematical

approaches to "fitting" the data. More specifically, the Committee seeks

to identify means for combining all (reliable) ^‘^C measurements of treering dated wood specimens into a single radiocarbon scale calibration

scheme, preserving as much of the high frequency components as seem warranted by the data. During the past year cooperative efforts by

L. A. Currie (Center for Analytical Chemistry), C. Spiegelman (Center

for Applied Mathematics), and J. C. Lerman (Univ. of Arizona) have

produced important insights into measurement and interlaboratory errors

(see also part 1, above), assumed functional models, and best estimates

for the calibration curve and its uncertainty band.

L. A. Currie

?. 3 . Advances in Small Sample Radiocarbon Measurement Techniques; Application to the Assay of Individual Atmospheric Chemical Species

During the past year the NBS program to utilize natural radiocarbon

as a tracer for sources of carbonaceous pollutants has been directed

toward a) fundamental advances in measurement and data evaluation techniques

and b) critical studies of urban air pollution episodes (such as the

Denver "brown cloud") and basic investigations of sources of atmospheric

gases and particles. The importance of these investigations rests upon

the impact of both natural and man-made carbonaceous contaminants on health, stratospheric ozone, and climate. The success of this program,

the only such program extant, is due to the ability of NBS to perform

reliable radiocarbon measurements on ambient samples containing microgram

to milligram quantities of carbon.

Measurement advances are continuing through the development of

miniature gas proportional counter and nuclear accelerator ("atom-counting")

techniques which provide sensitivity gains of 10^ to 10^ compared to

conventional radiocarbon dating techniques. Important meetings treating

these topics (among others), organized by individuals in the group,

included an ACS Symposium ("Nuclear and Chemical Dating Techniques",

March 1980) and a meeting at NBS (August 1980) on sample preparation for

accelerator measurements. Our work with the accelerator, which last year

demonstrated the capability of precise measurement using less than 40 vg

(carbon) of the new international radiocarbon dating standard, is continuing with studies in alternative source preparation methods, isotopic

enrichment, and baseline tests with the first "dedicated" tandem accelerator constructed exclusively for atom-counting measurements. This

particular machine is considered a National Science Foundation

Regional Facility, and it will be located at the University of Arizona.

The accelerator approach will make possible the radiocarbon assay of

yg quantities of individual hydrocarbons and halocarbons, and individual

chemical and size fractions of non-urban atmospheric particulates.

220
Applications to urban pollution and source studies of carbonaceous

particles have centered on vegetative burning in the Portland, Oregon

region, vegetative oil shale aerosol contributions in a remote Utah

location, urban pollution in Los Angeles and Denver, and an international

effort (joint US - USSR AFAEX-79 project) to investigate "processes and

mechanisms of formation and transformation of natural aerosol" in a remote forested region in the Soviet Union. In all of these studies,

which were broadly interdisciplinary in nature, our group provided the

only isotopic data; and the natural radiocarbon results yielded the only

unique measure of the biogenic (non-fossil) contribution. This was especially important in the Denver and Portland studies where as a result of our measurements it was concluded that residential wood burning

constituted one of most significant sources of inhalable (< 2.5 ym) and

visibil ity-reducing particles. In Denver for example, it was concluded

that 18 percent of the visibility reduction of the winter time atmosphere

arose from wood burning. Furthermore, 39 percent of the most effective

visibity-reducing species -- elemental ("graphitic") carbon -- has been

ascribed to wood burning.

It should be noted that the foregoing regional studies have included

considerable data on chemical and physical characteristics of the ambient

particles, together with supporting emission inventory and meteorological

data. Although radiocarbon techniques provided the only direct measure

of contemporary carbon, the other (indirect) indicators supported the

conclusions from radiocarbon measurements in every case. A major challenge exists in selecting and evaluating the entire multidimensional data

patterns from such experiments; this need formed the basis for the first

Receptor Modeling Workshop (March 1980 in Durham) and the resulting

committee on chemical mass balance and multivariate analysis methods of source reconciliation. Our program at NBS has been expanded to include

such modeling efforts, in cooperation with NBS Center for Applied Mathematics. The combined use of isotopic data (^^C and ^^C) with particle

size and chemical data (pyrolysis mass spectrometry, inorganic composition

and elemental y^. organic carbon) has, in fact, been an intrinsic part of

the above urban and remote particulate studies.

A summary of our recent radiocarbon measurements, which now include

atmospheric gases as well as particles, is given in Table 22. Future

work will be directed toward further sampling of selected gases (hydrocarbons, carbon monoxide), sources of urban run-off and sediment studies,

high-altitude sampling, investigations of arctic haze and climatological

consequences, and pal eoatmospheric (isotopic) composition via ice core samples

.

L. Currie, G. Klouda

221
Recent

Radiocarbon

Results f co

fO 01 10 +J ro N O

<o +j c c t- cx o re o o cn E Q o o

cn 1- +J

M <u C_1 c cn C n- o •»- 1— T3

•1“ c_> o c re CO *r- (O

O E O +J ro 1 ro cn o c o •r— fO *r- s- +J s- cx re cx +J E o S- O E cn E X re Q. o c o X o re cn

Cl CD cx •—< o o o cx

X 3 E D, o

C/1 3 E o C/1 ft—4 *T

in

>>

sn

X

ro

s- c o S- c o o E o o

Q-"i- cn CM n— r— CX*r- CO in CO 1— in «ci- E +-> o <u CM CM CM 9\ E •-> 1— o r— CM r— f—

(U

O • to • • • S- d)

u

M (OO 1—

O o o (U +-> re o o o o o o o c s- 3 +-> C i~ O IJ- +1 CL +1 +1 +1 c O Lx +1 +1 +1 +1 +1 +1 +1

CJ) 1 3 «/) (_> c Lf> C_> cx) CD cn o 01 c cn CO ro (X) re- 1^ 1 o cr> j- C71 CO 1— o 1 o CD o CM CD cn o CD

JD • • • • o JO

M S- o — o o o *r“ 4-> S- o o o o O 1— o I— »C ro •4-> f— ro 3 O c S- 3 O C/) o ro to

(U cx O)

at: +-> DC o o

cx s- IC o (U -*-> +J

01 eC S- Jl= cz c N D. cx cx O) 01

•r- 4-> +J (/> c c •x> O) CO C (U Cf- A o 01 o o > <u oi O CO E > cx 01 re E E -o L- 4-> •r— E • E r- cx 3 (U CD «c O E o re E o E O o x: o <_3 O) o u 1—1 OJ s- +J 01 JZ o

•r-> c s_ J* 3 o 1— o 1— f— E c c o .Q ro 03 —

re

O z: uj C_1 C>0 o s- S- JD 3 3 X

ro 4J +J =D

ro re +J • «% ZZi z

-t-> c (/) oi o to *o 3.

01 I— O)

S_ Q. CJ

O •r- E <c •r- ^ T3 Q 1—1

+j CO r— ^

>1

V 1 01 re E 1— re 01 c_> J- +J o re re S 3C +j :e E •r- O JO s_ cn Lx DC

(U ns C_1 CO <c 0)

M > X 3

•o Li- Q. S- r— re 1 n DC

QQ o Q. c E ro +J E o o 01

fC o s- re fO > z > c/1 c O) +-> s- c/> r-" c (U re -M cn

+-» Q. (U E re E

tr> CO E OJ c O +j *1- o o ro 01 E o E o o J3 cn cn X

J" +J (L) <c s- 01 01 3

<C C/1 to =) DC > QQ

222

Residential

wood

combustion
C. Outputs and Interactions

(Gas and Particulate Science Division)

1 . Pubi i cations

Rosasco, G. J. and Blaha, J. J., "Raman Microprobe Spectra and Vibrational

Mode Assignments of Tale," Applied Spectroscopy, Vol . 34, No. 2,

October 1979, p. 140-144.

Blaha, J. J. and Etz, E. S., "Some Experimental Problems in the Raman

Analysis of Microsamples," Proceedings of the 15th Annual

Conference of the Microbeam Analysis Society (San Francisco Press,

1980) p. 183-184.

Blaha, J. J., "Trace Characterization of Drugs of Abuse," NBS Dimensions,

64(3), 18-19 (1980).

Bright, D. S., Fletcher, R. A., and Chabay, I. S., "Particle Doppler

Shift Spectrometry: Accurate Size Determination of 5-15 ym Aerosol,"

J. Phys. Chem. 1607-1611 (1980).

Currie, L. A., "Krypton-81" with (H. Oeschger) and "Small Radiocarbon

Samples," in Workshop on Dating Old Groundwater (S. N. Davis, Ed.),

University of Arizona, (1978).

Cooper, J. A., Currie, L. A., and Klouda, G. A., "Evaluation of

Carbon-14 as a Unique Tracer to Determine the Maximum Impact

of Contemporary Carbon Sources of Atmospheric Particulates in

the Portland and Eugene Airsheds," Final Report: Oregon Department

of Environmental Quality (1979).

Ritter, G. L. and Currie, L. A., "Resolution of Spectral Peaks: Use

of Empirical Peak Shape," Proceedings of the Topical Conference on Computers in Activation Analysis of the American Nuclear Society,

(B. S. Carpenter, M. D. D'Agostino, and H. P. Yule, Eds.), DOE

Symposium Series 39 (1979).

Currie, L. A. and Kropschot, R. H., "Foresight-Volume I. Societal

Aspects of Hydrogen Energy Systems," published by the U.S. House

of Representatives, Committee on Science and Technology, Part A,

p. 1-134 (1979).

Currie, L. A., Noakes, J. E., and Breiter, D. N., "Measurement of Small

Radiocarbon Samples: Power of Alternative Methods for Tracing

Atmospheric Hydrocarbons," in Radiocarbon Dating, R. Berger

and H. E. Suess, Eds., (University of California Press, 1979),

p. 158-175.

Currie, L. A. and Klouda, G. A., "Discrimination of Natural From

Anthropogenic Carbonaceous Pollutants Through Mini-Radiocarbon

Measurements," NBS Special Publication 572, (1980), p. 68-73.

223
Currie, L. A., "Scientific Uncertainty and Societal Decisions: The Challenge

to the Analytical Chemist," Analytical Letters, 1^, 1-31 (1980).

Elkins, J. W., "Determination of Dissolved Nitrous Oxide in Aquatic

Systems by Gas Chromatography Using Electron-Capture Detection and

Multiple Phase Equilibration," Anal. Chem. , 263-267 (1980).

Etz, E. S. and Blaha, J. J., "Laser-Raman Microprobe Analysis of Particles

in Pollution Studies," Trans. Am. Nucl . Soc., 241 (1979).

Abraham, J. L. and Etz, E. S., "Molecular Microanalysis of Pathological

Specimens in situ with a Laser-Raman Microprobe," Science 206,

716-718 (19791:

Etz, E. S. and Blaha, J. J., "Scope and Limitations of Single Particle

Analysis by Raman Microprobe Spectroscopy," in NBS Special Publication

533, Characterization of Particles (1980), p. 153-197.

Fletcher, R. A., Bright, D. S., and Chabay, I. S., "Low Reynolds

Number Fluid Flow Induced by Settling Aerosol and Detected by

the Particle Doppler Shift Spectrometer," J. Chem. Phys.

84, 1611-1614 (1980).

Marinenko, R. B., Heinrich, K. F. J., Myklebust, R. L., and Fiori, C. E.,

"Crystal Efficiency Determination for Relative Line Intensity

Measurements," Proceedings of the 15th Annual Conference of the

Microbeam Analysis Society, (San Francisco Press, 1980), p. 56-58.

Menis, 0. and Garn, P. D. , "The State-of-the-Art of Thermal Analysis,"

NBS Special Publication 580, (1980).

Fiori, C. E., Myklebust, R. L., and Newbury, D. E., "A Catalogue

of Artifacts Observed in Energy-Dispersive X-ray Spectrometry

and Their Influence on Analysis," in Microbeam Analysis in

Biology, (C. Lecheme, Ed.), Academic Press, New York, NY, (1979),

p. 225-263.

Fiori, C. E. and Myklebust, R. L., "A Simplex Method for Fitting Gaussian

Profiles to X-ray Spectra Obtained with an Energy-Dispersive Detector,"

Computers in Activation Analysis and Gamma-Ray Spectroscopy, DOE

Symposium Series 49, CONF-780421 , (1979), p. 139-149.

Myklebust, R. L., Newbury, D. E., and Small, J. A., "Backscatter Loss

in the X-ray Continuum," Proceedings of the 15th Annual Conference

of the Microbeam Analysis Society, (San Francisco Press, 1980),

p. 49-50.

Newbury, D. E., "Instrumental Effects on Quantitative Analysis by Secondary

Ion Mass Spectrometry," in Secondary Ion Mass Spectrometry II,

(A. Benninghaven , C. A. Evans, Jr., R. A. Powell, R. Shimizu,

and H. A. Storms, Eds.), Springer-Verlag, Berlin, (1979), p. 53-57.

224
Newbury, D. E. and Myklebust, R. L., "Calculation of Electron Beam

Spreading in Composite Thin Foil Targets," Proceedings of the

15th Annual Conference of the Microbeam Analysis Society,

(San Francisco Press, 1980), p. 173-175.

Newbury, D. E., "Secondary Ion Mass Spectrometry for the Analysis of

Single Particles," in NBS Special Publication 533, Characterization of Particles (1980), p. 139-152.

Newbury, D. E., Myklebust, R. L., Heinrich, K. F. J., and Fiori, C. E.,

"Specialist Workshop on Energy Dispersive X-ray Spectrometry,"

Scanning, 43-44 (1980).

Fiori, C. E. and Newbury, D. E., "Artifacts in Energy Dispersive X-ray

Spectrometry in the Scanning Electron Microscope (II)," Proceedings

of the Scanning Electron Microscopy/1980, the Annual Review of

Scanning Electron Microscopy, (0. Johari, Ed.), (1980), p. 251-258.

Newbury, D. E., Myklebust, R. L., Heinrich, K. F. J., and Small, J. A.,

"Monte Carlo Electron Trajectory Simulation - an Aid for Particle

Analysis," in NBS Special Publication 533, Characterization of

Particl es (1980), p. 39-62.

Pella, P. A., "The Development of Potential Thin Standards for Calibration

of X-ray Fluorescence Spectrometry, NBS/EPA Report No. EPA-600/7-80-031

,

February 1980.

Gills, T. E. and Rook, H. L., "Specimen Bank Research at the National

Bureau of Standards to Insure Proper Scientific Protocols for the

Sampling, Storage, and Analysis of Environmental Materials,"

in Monitoring Environmental Materials and Specimen Banking,

(N.-P. Luepke, Ed.), Martinus Nijhoff Publishers, (1979).

Simons, D. S., "Ion Microprobe, Ion Microscope, and Laser Microprobe

Mass Analysis of Particulates," Proceedings of the 15th Annual

Conference of the Microbeam Analysis Society, (San Francisco Press,

1980), p. 178-180.

Small, J. A. and Steel, E. B., "An Overview of NBS-EPA Program for

the Development of Standards for Use in the Analysis of Environmental

Samples for Asbestos by Electron Microscopy," to be published in

the Proceedings of the 3rd Colloquium on Dust Measuring Technique

and Strategy, Cannes, France (1980).

Small, J. A., Newbury, D. E., and Myklebust, R. L., "Instrumental Effects

on the Generation of Continuum from Pure Element Targets,"

Proceedings of the 15th Annual Conference of the Microbeam

Analysis Society, (San Francisco Press, 1980), p. 53-55.

Small, J. A., Heinrich, K. F. J., Newbury, D. E., Myklebust, R. L., and

Fiori, C. E., "Procedure for the Analysis of Single Particles with

the Electron Probe," in NBS Special Publication 533, Characterization

of Particles (1980), p. 29-38.

225
steel, E. B., "Optical Microscopy of Particles," in NBS Special Publication

533, Characterization of Particles (1980), p. 5-11.

Bass, A. M. , Glasgow, L. C. , Miller, C., Jesson, J. P., and Filkin, D. L.,

"Temperature Dependent Absorption Cross Sections for Formaldehyde

{CH2O): The Effect of Formaldehyde on Stratospheric Chlorine

Chemistry," to be published in Planetary and Space Science.

Blaha, J. J., Etz, E. S., and Heinrich, K. F. J., "Raman Microprobe

Analysis of Stationary Source Particulate Pollutants," to be published

as an EPA Final Report.

Blaha. J. J., "Raman Microprobe Spectroscopic Analysis," to be published

in Vibrational Spectra and Structure, Volume X.

Blaha, J. J. and Rosasco, G. J., "Raman Microprobe Characterization

of Urea: n-Paraffin Inclusion Compounds," to be published in the

J. Raman Spectroscopy.

Dornhaus, R., Benner, R. E., Chang, R. K. , and Chabay, I.S., "Surface

Plasmon Contribution to SERS," to be published in Surface Science.

Currie, L. A., Ed., Nuclear and Chemical Dating Techniques , to be published

as a monograph in the American Chemical Society Symposium Series.

Currie, L. A., Klouda, G. A., and Cooper, J. A., "Mini-Radiocarbon

Measurements, Chemical Selectivity, and the Impact of Man on Environmental Pollution and Climate," Proceedings of the 10th

International Radiocarbon Conference (in press).

Currie, L. A., "Contemporary Elemental Carbon," to be published in

the Proceedings of the Symposium on Particulate Carbon: Atmospheric

Life Cycle .

Currie, L. A., "The Origin of Carbonaceous Species in the Atmosphere

Deduced by Radiocarbon," ASTM Symposium on Sampling and Analysis

of Toxic Organics in the Atmosphere (in press).

Voorhees, K. J., Kunen, S. M., Durfee, S. L., Currie, L. A., and

Klouda, G. A., "The Determination of Source Contribution of Organic

Matter in Atmospheric Particulates by Pyrolysis/Mass Spectrometry

and 14c Analysis," submitted to Analytical Chemistry.

Currie, L. A. and Polach, H. A., "Exploratory Analysis of the International

Radiocarbon Cross-Calibration Data: Consensus Values and Interlaboratory Error," Proceedings of the 10th International Radiocarbon

Conference (in press).

Currie, L. A. and Klouda, G. A., "Counters, Accelerators, and Chemistry,"

to be published in Nuclear and Chemical Dating Techniques .

Swanson, J., Fairhall, A. and Currie, L. A., "Carbon Isotope Analysis

of Sedimentary Polycyclic Aromatic Hydrocarbons," submitted to

Nature.

226
Currie, L. A., "The Isotopic Dimension" and "Model, Error Structure and

Measurement Accuracy," Proceedings of the Workshop on Receptor

Modeling (in press).

Etz, E. S. and Blaha, J. J., "Raman Microprobe Spectra of Nearly

Opaque Particles," to be published in Analytical Chemistry.

Hodgeson, J. A. and Fatiadi, A. J., "A Survey on Research Needs on Personal

Samples for Toxic Organic Compounds," EPA Report No. EPA/600/4-80-042

,

(to be published).

Hughes, E. E. and Suddueth, J. E., "A Computer Operated Gas Analysis

System (COGAS) for the sequential Analysis of Multiple Samples of

Compressed Gases," to be published in Analytical Chemistry.

Myklebust, R. L., Small, J. A., and Newbury, D. E., "Quantitative

Electron Probe Microanalysis of Fly Ash Particles," to be published

in the Transaction of the American Nuclear Society.

Newbury, D. E. and Greenwald, S., "Observations on the Mechanisms

of High Resistance Junction Formation in Aluminum Wire Connections,"

Journal of Research (in press).

Joy, D. C., Newbury, D. E., and Davidson, D. L., "Electron Channeling

Patterns (ECP) in the Scanning Electron Microscope," to be published

in Physical Electron Microscopy, Volume 1, Von Nostrand, New York.

Newbury, D. E. and Myklebust, R. L., "Monte Carlo Electron Trajectory

Simulation of Signals at Interfaces in Analytical Electron Microscopy,"

to be published in the Proceedings of the 9th International Conference

on X-ray Optics and Microanalysis

.

Newbury, D. E., "Microanalysis of Individual Layered Particles by

Secondary Ion Mass Spectrometry," to be published as an EPA

Final Report.

Newbury, D. E., "The Impact of Instrumental Sensitivity Variations on Quantitative Analysis With the Local Thermal Equilibrium Model in

Secondary Ion Mass Spectrometry," to be published in the Proceedings

of the 9th International Conference on X-ray Optics and Microanalysis.

Stone, R. E., Walter, F. J., Blackburn, D. H., Pella, P. A., and Kramer, H. W.,

"A Standard Technique for Measuring Window Absorption and Other Efficiency

Losses in Semiconductor Energy Dispersive X-ray Spectrometry," to be

published in X-ray Spectrometry.

Kingston, H. and Pella, P. A., "X-ray Spectrometric Analysis of Trace

Metals in Environmental and Biological Samples Using Cation Exchange

Resin-Loaded Filters," to be published in Analytical Chemistry.

227
2. Talks

Bass, Arnold M., "Temperature Dependent Absorption Cross Sections for

Formaldehyde (CH2 O): The Effect of Formaldehyde on Stratospheric

Chlorine Chemistry," NATO Advanced Study Institute of Atmospheric

Ozone, Portugal, October 1979.

Currie, Lloyd A., "Cosmic Carbon," Washington, DC, October 1979.

Chabay, II an S., "Surface Plasmon Enhanced Inelastic Light Scattering From

Thin Films and Microspheres," New York, NY, November 2, 1979.

Etz, Edgar S., "Raman Microprobe Characterization of Nitrogen-Sulfur

Compounds in Stratospheric Aerosols," Moffet Field, CA, November 8, 1979

Chabay, Ilan S., "Raman Spectroscopy of Molecules Near Surfaces: Bulk

Liquids and Adsorbed Monolayers," New York, NY, November 9, 1979.

Etz, Edgar S., "Laser-Raman Microprobe Analysis of Particles in Pollution

Studies," San Francisco, CA, November 15, 1979.

Currie, Lloyd A., "Environmental Radiocarbon: Measurement by Low-Level

Counting and Accelerator Mass Spectrometry," Washington, DC,

November 15, 1979.

Steel, Eric B., "Mineralogical Characteristic of Asbestos," Tuscon,

Arizona, November 1979.

Chabay, Ilan S., "Two Flavors of Raman Spectroscopy: Concentration

Fluctuations in Turbulent Mixing and CARS in Waveguides," Wilmington,

DE, December 17, 1979.

McKenzie, Raymond L., "Measurement of Aerosol Sulfur Using an Electrostatic

Preci pita tor- FPD System," Ann Arbor, MI, December 18, 1979.

McKenzie, Raymond L., "Evaluation of a New Fast-FPD and Its Use With

the PEP," St. Louis, MO, December 20, 1979.

Elkins, James E., "Dissolved Nitrous Oxide in Coastal Waters Off Peru:

A Nitrification Source and Denitrification Sink," Los Angeles, CA,

February 7, 1 980.

Small, John A., "Particle Analysis at NBS," Washington, DC, February 15, 1980

Steel, Eric B., "Microscopic Characterization of Fibrous Minerals From

Pennsylvania Crushed Stone Quarries," Washington, DC, February 14,

1980.

Blaha, John B., "Microanalysis By Vibrational Spectroscopy With a Raman

Microprobe," Athens, GA, February 19, 1980.

228
Currie, Lloyd A., "The Isotopic Dimension," Durham, MC, February 26, 1980.

Chabay, Ilan S., "Evanescently Excited Raman Spectra of Liquid Benzene

and Adsorbed Monolayers," New York, NY, February 29, 1980.

Newbury, Dale E. , "Recent Progress in the Theory and Application of

Microprobe Analysis," Bethlehem, PA, February 29, 1980.

Currie, Lloyd A., "Counters, Accelerators, and Chemistry," Houston, TX,

March 25, 1980.

Etz, Edgar S., "Raman Microprobe Identification of Nitrogen-Sulfur

Compounds in Stratospheric Aerosols," Houston, TX, March 27, 1980.

Chabay, Ilan S., "Raman Measurements of Concentration Fluctuations

in Reactive and Non-Reactive Systems," New York, NY, April 9, 1980.

Newbury, Dale E., "Artifacts in Energy Dispersive X-ray Spectrometry

in the Scanning Electron Microscope." Chicago, IL, April 2, 1980.

Currie, Lloyd A., "Radiocarbon as a Tracer for Toxic Organics,"

Denver, CO, April 2, 1980.

Chabay, Ilan S., "Time, Frequency, and Probability Analysis of Raman

Signals From Concentration Fluctuations of Individual Species in

Turbulent Mixing Flow," Livermore, CA, May 2, 1980.

Kagann, Robert H., "The Determination of Absolute Infrared Absorption

Line Strengths of Nitrous Oxide With a Diode Laser Spectrometer,"

Washington, DC, May 14, 1980.

Chabay, Ilan S., "Time, Frequency, and Probability Analysis of Raman

Signals From Concentration Fluctuations of Individual Species in

Turbulent Mixing Flow," New York, NY, May 15, 1980.

Simons, David S., "Ion Microscope and Ion Microprobe Analysis of

Particulates," New York, NY, May 27, 1980.

Small, John A., "An Overview of NBS-EPA Program for Development of

Standards for Use in the Analysis of Environmental Samples for

Asbestos by Electron Microscopy," Cannes, France, June 11, 1980.

Kagann, Robert H., "Diode Laser Intensity and Line Width Measurements

in the yl and Adjacent Absorption Bands of N 2 O," Columbus, OH,

June 19, 1980.

Etz, Edgar S., "A New Raman Microprobe with Multichannel Optical

Detector--Characteristics and Applications," Postdam, NY,

July 1 , 1980.

229
Currie, Lloyd A., "On the Question of Detectability," Washington, DC,

July 8, 1980,

Rook, Harry L., "The Concept of Reality of Traceability in Gas Standards,"

Johnson, VT, July 16, 1980.

Hughes, Ernest E., "Preparation and Certification of Gaseous Standard

Reference Materials," Johnson, VT, July 15, 1980.

Etz, Edgar S., "Materials Characterization by Raman Microprobe Spectroscopy,"

Albuquerque, NM, July 17, 1980.

Etz, Edgar S., "The Development of Instrumentation for Microanalysis

by Raman Microprobe Spectroscopy," Livermore, CA, July 24, 1980,

Bass, Arnold M., "New Measurements of Ozone Cross-Sections," Boulder, CO,

August 4, 1980.

Myklebust, Robert L. "Back-Scatter Loss in the X-ray Continuum,"

Reno, NV, August 5, 1980.

Pella, Peter A., "X-ray Spectrometric Analysis of Trace Metals in

Environmental and Biological Samples Using Exchange Resin-Loaded

Filters," Reno, NV, August 1980.

Marinenko, Ryna B., "Crystal Efficiency Determination for Relative

Line Intensity Measurements," Reno, NV, August 5, 1980.

Steel, Eric B., "Sputtered Glass Thin Films for Analytical Electron

Microscope Standards," Reno, NV, August 6, 1980.

Simons, David S., "Ion Microprobe, Ion Microscope, and Laser Microprobe

Mass Analysis of Particulates," Reno, NV, August 6, 1980.

Newbury, Dale E., "Calculation of Electron Bea, Spreading in Composite

Thin Foil Targets, Reno, NV, August 6, 1980.

Blaha, John J., "Some Experimental Problems in the Raman Analysis

of Microsamples," Reno, NV, August 6, 1980.

Currie, Lloyd A., "Source Identification of Atmospheric Particulate

Matter By Py-MS/Pattern Recognition Procedures," Las Vegas, NV,

August 16, 1980.

Etz, Edgar S., "Raman Microprobe Spectroscopy with Applications to

Biomedical Studies," Bethesda, MD, August 18, 1980.

Newbury, Dale E., "Signal Processing and Video Display in Scanning Electron

Microscope," Brighton, England, August 18, 1980

230
Bright, David S., "A New Personal Sampler for Ambient Inhalable Particles,

Boston, MA, August 19, 1 980.

Chabay, Ilan S., "Raman Spectral Probe of Evanescent Field Components

At Metal and Dielectric Interfaces," Wolfeboro, NH, August 20, 1980.

Newbury, Dale E., "Methods of Quantitative Analysis in Secondary Ion

Mass Spectrometry ," Brighton, England, August 21, 1980.

Newbury, Dale E., "Monte Carlo Electron Trajectory Simulation of X-ray

Signals at Interfaces," The Hague, The Netherlands, Agust 26, 1980.

Newbury, Dale E., "The Impact of Instrumental Sensitivity Variations

on Analysis With the Local Thermal Equilibrium Model in Secondary

Ion Mass Spectrometry," The Hague, The Netherlands, August 28, 1980.

3 . Committee Assignments

Harry Rook

Member

,

ASTM D-22.05 Calibration

ASTM D-22.07 Precision and Accuracy of Methods

Office of Water Data Coordination, Committee 5F

Ernest Hughes

Member, ISO/TC 158 Gas Analysis

ISO/TC 158/SC-l Methods for Preparation and Definition of

Gas Mixtures for Calibration

Secretary,

ISO/TC 158/WG-2 Transfer Lines and Sampling

ISO/TC 158/WG-3 Evaluation of the Characteristics of Analysis

ISO/TC 158/WG-4 Analysis of Natural Gas

ISO/TC 158/WG-l Terminology

Arnold Bass

Member, ASTM D-22.02 Methods of Sampling and Analysis

ASTM D-22.03 Monitoring Instrumentation

ASTM D-22.05 Calibration

ASTM D-22.07 Precision and Accuracy of Methods

David Bright

Member, ASTM E-29.04 Liquid Particle Measurements

Ilan Chabay

Member, NBS Postdoctoral Selection Committee

Lloyd Currie

Member, Intersociety Committee - Methods of Air Sampling

and Analysis

Analytical Letters - Editorial Board

International Committee for the Calibration of the

Radiocarbon Time Scale

Model Validation Subcommittee - Receptor Modeling Workshop

231
William Dorko

Member, American Chemical Society, Washington Section,

Board of Managers

Edgar Etz

Member

,

ASTM D-22 Methods of Sampling and Analysis

of Atmospheres

Jimmie Hodgeson

Member, ASTM D-22 Atmospheric Analysis

ASTM D-22. 02 Manual Methods

ASTM D-22. 03 Instrumental Methods

ISO/TC 146/SC3 Air Quality/Ambient Atmospheres

Raymond McKenzie

Member, ASTM D-22 Sampling and Atmospheric Analysis

ASTM D-22. 03 Monitoring Instrumentation

ASTM E-29 Particle Size Measurement

ASTM E-29. 04 Characterization of Liquid Particles

Robert Myklebust

Member, ASTM E-2 Emission Spectroscopy

ASTM E-2. 04 Standard Reference Materials

Dale Newbury

Chairman, Microbeam Analysis Society

Member,

Technical Program Committee

National Council for the MAS

ASTM E-42 Surface Analysis

Journal of Microscopy, Editorial Review Board

Scanning, Editorial Review Board

Peter Pella

Member, ASTM E-2 Emission Spectroscopy

ASTM E-2. 02 Statistics, Calibration and Standardization

Gerald SI eater

Member, ASTM D-22 Sampling and Analysis of Atmospheres

4. Other

ASTM D-22. 06 Source Sampling

ASTM D-22. 07 Precision and Accuracy of Methods

a. Seminars

November 19, 1 979 Dr. Paul D. Garn

University of Akron

Akron, Ohio

Problem Solving Via Thermoanalytical Techniques

232
November 23, 1979 Dr. Sydney Leach

University of Paris

Paris, France

Radiationless Transitions in Molecular Ions

December 3, 1979 Dr. Bruce Kowalski

University of Washington

Seattle, Washington

Chemometrics in Analytical Chemistry

January 29, 1980 Dr. Otto Grubner

Harvard University

Boston, Massachusetts

Improvement in Gas Chromatographic Separation by

Specific Activation Compounds

March 17, 1980 Ernest Schumacher

University of Bern

Bern, Switzerland

Spectra and Electronic States of Metal Clusters and

their Ions

March 26, 1979 Dr. Ray F. Weiss

Scripps Institute of Oceanography

La Jolla, California

The Spatial and Temporal Distribution of Tropospheric

Nitrous Oxide

April 15, 1980 Dr. Ken Purser

General lonex, Inc.

Newbury Port, Massachusetts

Ultrahigh Sensitivity Mass Spectrometry

May 7, 1980 Walter Anthony Patrick Nicholson

University of Glasgow

Glasgow, Scotland

Determination of Elemental Concentrations in Low

Atomic Number Matrices by X-ray Microanalysis

June 4, 1980 Joseph P. Krasnec

National Center for Atmospheric Research

Boulder, Colorado

Electron Capture Detection Gas Chromatography

July 14, 1980 Dr. Yuk Ling Yung

Cal Tech.

Pasadena, California

Photochemistry of Heavy Hydrocarbons in the

Atmosphere

233
August 4, 1 980

August 6, 1980

August 28, 1980

Paul E. Wagner

Universitat Wien

Vienna, Austria

Nucleation and Droplet Growth in Supersaturated

Vapors

Jeff K1 ein

University of Pennsylvania

Philadelphia, Pennsylvania

Sample Preparation for Accelerator Mass Spectrometry,

and Fitting the Radiocarbon Calibration Curve

Pam Bumsted

Anthropology Department

University of Massachuetts

Amherst, Massachusetts

Dr. Thomas Hoering

Geophysical Laboratory

Carnegie Institute

Pittsburgh, Pennsylvania

Use of the Natural Stable Isotopes of Carbon, Hydrogen,

Oxygen and Nitrogen and Trace Elements to Reconstruct

Past Environments and Diets

b. Workshops

"Measurement of Atmospheric Fluorocarbons and Nitrous Oxide"

National Bureau of Standards - November 16-17, 1979.

"Symposium on Nuclear and Chemical Dating Techniques"

Houston, Texas - March 23-28, 1980.

c. Standard Reference Materials

A large number of analyses were performed leading to the certification of 64 SRM's. These are separated by group and are listed below:

Gas Metrology Group

1625 SO2 Permeation Tube, 10 cm 1626 SO2 Permeation Tube, 5 cm 1627 SO2 Permeation Tube, 2 cm

1658 CH4/Air, 1 ppm

1659 CH4/Air, 10 ppm

1660 CH4 and C3H3/Air, 4 and 1 ppm

234
1662 SO2 /N 2 , 1000 ppm

1663 SO 2 /N 2 , 1500 ppm

1665 CaHs/Air, 3 ppm

1666 CaHe/Air, 10 ppm

1667 CaHs/Air, 50 ppm

1668 CaHs/Air, 100 ppm

1669 CaHs/Air, 500 ppm

1674 CO2 /N 2 , 1 %

1675 CO2 /N 2 , 14%

1677 CO/N 2 , 10 ppm

1678 CO/N 2 , 50 ppm

1679 CO/N 2 , 100 ppm

1680 CO/N 2 , 500 ppm

1681 CO/N 2 , 1000 ppm

1683 NO/N 2 , 50 ppm

1684 NO/N 2 , 100 ppm

1685 NO/N 2 , 250 ppm

1686 NO/N 2 , 500 ppm

1687 NO/N 2 , 1000 ppm

2612 CO/Air, 10 ppm

2613 CO/Air, 18 ppm

2614 CO/Air, 43 ppm

2627 NO/N 2 , 5 ppm

2628 NO/N 2 , 10 ppm

2629 NO/N 2 , 20 ppm

2630 NO/N 2 , 1500 ppm

2631 NO/N2 , 3000 ppm

2643 C3HS/N2, 100 ppm

2644 C3H8/N2, 250 ppm

2645 C3HS/N2, 500 ppm

2646 C3HS/N2 » 1000 ppm

2647 C3HS/N2, 2500 ppm

2648 C3HS/N2 s 5000 ppm

2649 C3HS/N2, 1%

2650 C3HS/N2 s 2%

2651 C3HS/N2 + 5% O2,

2652 C3HS/N2 + 10% O2,

2653 N02/Air, 250 ppm

2654 N02/Air, 500 ppm

2655 N02/Air, 1000 ppm

2656 N02/Air, 2500 ppm

235
2657 O 2 /N 2 , 2%

2658 O2 /N 2

, ^ 0%

2659 O2 /N 2 , 21%

2682 SO2 /N2 , 50 ppm

2683 SO 2 /N 25 100 ppm

W. D. Dorko, E. E. Hughes, R. Myers, W. Thorn, R. Miller, J. Mackey,

G. Rhoderick, G. Sleater, W. P. Schmidt, J. Suddueth

Microanalysis Research Group

479a, Fe-Cr-Ni Alloy for Microanalysis

470, Mineral Glasses for Microanalysis (K-411 and K-412)

30, Glasses for Microanalysis

R. B. Marinenko, R. L. Myklebust

X-Ray Fluorescence Group

1622a Sulfur in residual fuel oil

Cl 173 Steel , low al loy

Cl 173a Steel, low alloy

477

1262a

1263a

1264a

1261a

P. A. Pella, J.

Glass disks, energy loss measurements, EDXRF

Steel, low alloy, AISI94B17(Mod) , renewal

Steel, low alloy, Cr-V (Mod), renewal

Steel, low alloy, high carbon (Mod), renewal

Steel, low alloy, AISI4340, renewal

R. Sieber

236

* U. S. GOVERNMENT PRINTING OFFICE : 1980 340-997/32T
MBS-1UA (REV. 9-76)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSIR 80-2164

4. TITLE AND SUBTITLE

Annual Report 1980, Center for Analytical Chemistry

5. Publication Date December 1980

7. AUTHOR(S)

C. W. Reimann, R. A. Velapoldi, L. B. Hagan, J. K. Taylor

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. Proiect/Task/Work Unit No.

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS fSfreef, City, state. ZIP) 13. Type of Report & Period Covered

15. SUPPLEMENTARY NOTES

I I Document describes a computer program; SF-185, FIPS Sofbware Summary, is attached.

IG. ABSTRACT (A 200^word or leas factual aununary of moat significant information. If document includes a significant bibliography or

literature survey, mention it here,) This report summarizes the technical activities of the Center for Analytical

Chemistry at the National Bureau of Standards. It emphasizes activities over the Fiscal Year, 1980 in the Instrumentation Development Group, the Inorganic

Analytical Research Division, the Organic Analytical Research Division, and

the Gas and Particulate Science Division. In addition, it describes certain

special activities in the Center including quality assurance and voluntary

standardization coordination, the National Environmental Specimen Bank, and

service analysis coordination.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name;

separated by semicolons)

chemistry*, analytical services; gas and particulate

science; inorganic analytical chemistry; National Environmental Specimen Bank;

organic analytical chemistry; quality assurance; voluntary standardization.

18. AVAILABILITY Unlimited

rX~l For Official Distribution. Do Not Release to NTIS

I I Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-003-

I I Order From National Technical Information Service (NTIS), Springfield,

VA. 22161

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF

PRINTED PAGES

22. Price

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