• U56

88-3875

1988

C.2

U.S. DEPARTMENT OF COMMERCE

National Institute of Standards and Technology
1 .>1 ->5''

''ii
NISTIR 88-3875 Center for

Analytical

Chemistry

1988

Technical Activities

November 1988

Harry S. Hertz, Director

Center for Analytical Chemistry

National Measurement Laboratory

U.S. Department of Commerce, C. William Verity, Secre^^j^"^"

National Institute of Standards and Technology, Ernest Ambler,

Table of Contents

Page

Center for Analytical Chemistry 1 A. Center Overview 1 B. Outputs and Interactions 6

C. Service Analysis 7

Inorganic Analytical Research Division 8

A. Division Overview 8

B. Selected Technical Activities 18

1 . Development of Ion Chromatographic Methods for the Determination of

Transition Metals Using Chelating Resins 18

2. Interlaboratory Test Studies for the Development of Reference

Materials for Potentiometric Sodium and Potassium Measurements in

Human Serum 19

3. Establishment of Absolute Values for the Specific Conductance of Aqueous

Solutions of Potassium Chloride for Improved Measurement Accuracy 20

4. Advancement of Robotics in Analytical Chemistry and Applications to Chemical

Separations for SRM Certification 21

5. A Prototype Expert System for Developing Microwave Dissolution Procedures 22

6. Development of Rapid Dissolution Procedures for the Determination of Such Volatile

Elements such as As, Se, S, and Hg 23

7. A Direct Solid Sample Introduction Method for the Determination of Trace

Elements in Glass Using Zeeman AAS 23

8. The Development of Modern Approaches to Classical Analytical Chemistry 24

9. The Determination of Tributyltin in Sediment Using Liquid Chromatography with

Laser-Enhanced Ionization as a Tin-Selective Detector 26

10. The Determination of Ba-Y-Cu Oxide Stoichiometry in Superconducting Materials

Using ICP Optical Emission Spectrometry 26

1 1 . The Technical Planning and Execution of a Certification Program for the Buffalo

River Sediment SRM 27

12. Measurement of Chromium in Human Blood and Blood Fractions at Natural

(sub-ppb) Levels 29

13. Measurement of Long-Term Stability of Human Livers 30

14. Quantitative Determination of Proteins Using Polyacrylamide Gel Electrophoresis

and Neutron Activation 31

15. Determination of As, Cd, Cr and Mo in the NIST Bovine Serum Standard

Reference Material at the PPB Level 31

16. Standard Reference Materials 33

1 7. Analysis of U.S. Dietary Collections in Conjunction with the lAEA-NIST-FDAUSDA International Nutrition Project 36

18. Particle-Particle Coincidence Neutron Depth Profiling (NDP) 37

1 9. Measurement of Superconductor Stoichiometry by Prompt and Delayed Neutron

Activation 38

20. Development of an Intentional Isotopic Tracer for the Study of Particulate

Emissions into the Atmosphere 38

21 . Production and Analysis of Ultrapure Acid from a Large Teflon Still 40

22. The Development of Multielement Procedures for Analysis of Diverse

Materials by ICP-MS 40

23. Applications of ICP/MS Detection with Sample Introduction by Flow

Injection and Liquid Chromatography 42

24. Automated Mass Spectrometers for Inorganic Analysis 42
Table of Contents (Continued)

Page

25. Investigation of Atomization Processes for High Sensitivity

Measurements by RIMS 43

C. Outputs and Interactions 46

III. ORGANIC ANALYTICAL RESEARCH DIVISION 72

A Division Overviews 72

B. Selected Technical Activities 89

1 . Investigation of the Relationship between Stationary Phase Thickness and Selectivity

for Isomeric Compounds in Reversed-Phase Liquid Chromatography 89

2. Evaluation of the Quantitative Capabilities of Thermospray LC/MS 90

3 Thymine-Tyrosine Crosslinks: The Identification of a New Group of Radiation-Induced

Compounds of Potential Biochemical Importance 90

4. Liposome-Enhanced Flow Injection Immunoanalysis 91

5. Laser-Induced Modification of Electrode Surfaces 92

6. Synthesis and Characterization of a Novel "Capped" Cobalt(ll) Metalloporphyrin:

Electrochemical Evidence for a Mixed Coordination Sphere about the Central Metal Ion 93

7. Adaptation of Definitive Method Technology for the Certification of Food-Related

Reference Materials 94

8. Determination of PCB Congeners In Complex Matrices Using Two-Dimensional

Gas Chromatography 95

9. Organic Chemical Markers for the Identification of Residential Wood and Mobile

Source Combustion 96

10. Proteins of Human Liver: Two-Dimensional Gel Electrophoretic Mapping of

Human Liver Tissue 96

1 1 . Results of an Interlaboratory Study to Assess Reproducibility of Rehydratable

Isoelectric Focusing Gels 98

12. Two-Dimensional POMMIE Carbon-Proton Chemical Shift Correlation 98

13. QA Activities for the National Cancer Institute: Establishment of an Accuracy Base for

Measurements of Micronutrients In Serum 99

14. Preliminary Investigations Directed Toward the Development of Reference Materials

for DNA Adducts in Body Fluids 100

15. Protein Modulation Studies of Human Colon Tumor Cell Line HT-29 101

16. Establishment of a New Five-Year Agreement with EPA for Development of

Reference Materials 102

1 7. Determination of the Catalytic Activity of Aspartate Aminotransferase (AST)

Reference Material (RM 8430) 102

1 8. Development of SRMs for Marine Pollution Monitoring 103

19. Development of SRM 1597, Complex Mixture of Polycyclic Aromatic Hydrocarbons

from Coal Tar 104

20. Development of SRMs for Cholesterol in Human Serum 105

21 . Development of SRMs for Drugs of Abuse In Urine 107

22. The Expanded Role of the NIST Specimen Banking Program 109

IV. GAS AND PARTICULATE SCIENCE DIVISION 120

A. Division Overviews 120

B. Selected Technical Activities 132

1 . The Use of Experimental Design Methodology for Effective Sample Selection:

Application to Aerosol Source Apportionment 132

2. A New Approach to the Determination of the Origins of Individual Carbonaceous

Particles through Accelerator Mass Spectrometry (AMS) and Laser Microprobe

Mass Spectrometry (LAMMS) 133

iv
Table of Contents (Continued)

Page

3. Improved Accuracy in the Radiocarbon Dating of Bone and the Tracing of

Atmospheric Carbon via Micro-organic Isotopic Measurements 1 34

4. Application of Radiocarbon Measurements and Multivariate Analysis

to the Source Apportionment of Polycyclic Aromatic Hydrocarbons 136

5. Maintaining the Primary Ozone Standard for the Domestic and International

Communities 137

6. Ion Implantation Artifacts Detected by Secondary Ion Mass Spectrometry 138

7. Electron Optical Bench for the Measurement of Fundamental X-ray Parameters 139

8. Implementation of a Laboratory Accreditation Program (LAP) for the Analysis of

Asbestos in Bulk Materials and in Air 139

9. Molecular Compositional Mapping of Organic Compounds by Secondary

Ion Mass Spectrometry 141

10. Compositional Mapping with a Camera-Based Imaging System on an Ion

Microscope 141

1 1 . Concentration - Concentration Histograms: Scatter Diagrams Applied to

Quantitative Compositional Maps 142

12. Compositional Mapping by Electron Probe Microanalysis of Bulk and

Thin-Fllm Superconductors 143

13. Fundamental Studies of Matrix Correction Models for Quantitative Electron

Probe Microanalysis 144

14. Raman Microprobe Spectroscopy Applied to the Characterization of

Superconducting Materials 145

15. XRF Analysis of SRM 2704 (Buffalo River Sediment) by Automated Borate

Fusion 146

16. Total Reflection XRF Analysis with a Rotating Anode Source - Some Preliminary

Observations 146

17. Development of Immobilized Chelator Membranes for Preconcentration of Trace

Elements 148

18. Preparation and Verification by Electron Capture Detection of Primary Gravimetric

Standards of Volatile Toxic Organic Compounds (VTOC’s) at the 1 5-500

Parts-Per-Trllllon Level 148

19. Developed and Certification of the First SRM Containing ppb Levels of Multiple

Volatile Toxic Organic Compounds 149

20. Development and Application of Coulometric Titration as a Direct as a Direct

Measurement of CO2 Compressed Gas Cylinder Mixtures 149

21 . Isotope Dilution Mass Spectrometry for Absolute Determination of Carbon

Dioxide Abundance In Air 150

22. Development of a Low-Level Nitric Acid Generator 151

23. Characterization of the Output of a Nitric Acid Generation System Using

Tunable Diode Laser Spectrometry and Chemiluminescence Detection 151

24. Study of the Chemistry of NO2/HNO3/H2O in Compressed Gas

Cylinder Mixtures 152

25. Development and Characterization of a Low Concentration H2O2

Generation System 153

26. Development and Evaluation of a New Preparation Technique for Producing

High Accuracy Carbon Dioxide in Air Gravimetric Standards 154

27. Measurements of Sulfur-Containing Gases (OCS and CS2) in Ambient Air 155

C. Outputs and Interactions 157

V

I. Center for Analytical Chemistry

Harry S. Hertz, Director

Richard A. Durst, Deputy Director (Acting)

A. Center Overview

The Center for Analytical Chemistry (CAC) develops and maintains the scientific competences and the

experimental facilities necessary to provide the Nation with the basis for uniform measurements through

development of measurement methodology and reference materials and provision of measurement services

in the field of analytical chemistry. Analytical measurements provide a foundation for scientific and

technological research and development concerning materials and their practical application. Analytical

measurements are routinely used as a basis for regulatory decisions. Moreover, analytical measurements

are increasingly used as the basis for industrial quality and health-related decisions. The Center serves as

the National Reference Laboratory for assuring the reliability of analytical measurements.

The principal means by which the Center has served as a National Reference Laboratory is through the

development of measurement concepts and methods, provision of quality assurance services, and

certification of Standard Reference Materials (SRMs). The ubiquity of, and demand for, analytical

measurements in modern society is reflected in the many SRMs produced in the Center. These reference

materials are widely used in such diverse areas as the semiconductor and chemical industries, and in clinical

and environmental laboratories. Each SRM 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

- high-technology materials, body fluids, plant and animal tissues, and foods. Increasingly, analytical values as a function of location within a sample are needed. As the demands upon analytical chemistry become

more sophisticated, the problem of standardization becomes more challenging, both in terms of the number

and the complexity of the needed measurement methods and reference materials. Since it is not reasonable

to develop SRMs to deal with every measurement problem, the Center’s program must be multifaceted and

selective, seeking a variety of avenues to influence the quality of analytical measurements made in the United

States. In addition to research publications and the certification of reference materials, the Center exerts

influence through close contacts with various communities by means of workshops, symposia, and

participation in professional societies and voluntary standards committees. Through such contacts,

priorities are established for the development of measurement methods and the production of reference

materials, and mechanisms are set in place for their effective use.

The expanded responsibilities which we have been given in becoming the National Institute of Standards

and Technology, as reflected in our revised mission statement in the enabling legislation, provide a challenge

for us to more directly couple with industrial needs in the United States and, in particular, to serve the

metrology needs of emerging industrial technologies. A major component of industrial competitiveness is quality. With the emphasis currently being placed on quality at all levels of activity, the Center for Analytical

NOTE: Certain commercial equipment, instruments, or materials are identified in this report to specify

adequately the experimental procedure. Such identification does not imply recommendation or endorsement by the National Bureau of Standards, nor does it imply that the materials or equipment

identified are necessarily the best available for the purpose.

1
Chemistry has also been focussing attention on this issue. This has been accompiished through increased

support of quality assurance functions in major national monitoring programs (such as the National Cancer

Institute Chemoprevention studies and the NCAA Status and Trends Program), as weli as through more

carefuily documenting our internal quality assurance practices.

This documentation, which is continuousiy updated and expanded has recentiy been combined with

information on traceability of chemicai measurements into a Center for Analytical Chemistry Quality

Assurance Handbook. This document, in addition to being distributed to our own staff, has been made

available to the analytical chemistry community. As a result, in the last several months, we have responded

to over 800 requests for copies of the Handbook.

it is clear to us that the analytical laboratory is changing and will continue to change in the near future.

Techniques we are developing and using today were unheard of several years ago. During the past year,

we have implemented isotope dilution mass spectrometric procedures using combined LC/MS/MS and been

abie to demonstrate a relative precision of 1% for measurement of uric acid in serum. We have expanded

our research efforts in the development of bioanalytical sensors, using liposome technology and flow

injection immunoassays. With the installation of a cold neutron source in our research reactor, we are looking

forward to significantly enhanced sensitivity in our ability to depth profile chemical concentrations of key

elements in high technology materials utilizing a neutron beam, and to significantly enhance our ability for

performing prompt gamma activation analysis. Characterization of large biomolecules (proteins and nucleic

acids) is also receiving increasing attention with our enhanced capabilities for electrophoretic separations

and digital imaging of two-dimensional electrophoreograms. Optimization of experimental design and of

information utilization from multivariate chemical measurements is a focus of our growing effort in chemometrics. It is the intent of our research staff eventually to explore the total chemical measurement

process.

One technique that is seeing a tremendous resurgence in CAC is wet chemistry. We are committed to

renewing our capabilities in this area and to bringing this classical art into the 21st century. We have

expanded our research base in laboratory robotics, to facilitate wet chemical separations. We are trying to

capture the knowledge available so that wet chemistry can be applied to critical elemental assays and to the

growing field of speciation, i.e., chemical analysis with retention of information on oxidation and binding

states.

This year we were pleased to jointly dedicate with NIH, a new field emission scanning transmission electron

microscope facility which has a one nanometer special resolution for analytical probes. We were also pleased

this year to receive our seventh R&D 100 (formerly IR-100) Award since 1984. This track record clearly

demonstrates the contributions that scientists in the Center for Analytical Chemistry are making to technology

development. This year’s award was for a newly designed conductance cell, which makes it possible to

measure the cell constant directly, thereby improving the accuracy by a factor of 5 and establishing a better

reference basis for conductivity measurements.

This past year also has included a notable increase in collaborative activities, through the sponsorship of

research associates at NIST. The Motor Vehicle Manufacturers Association has sponsored a new research

associate to improve reference technology and reference material availability for automobile emissions

testing. The College of American Pathologists expanded its reference laboratory at NIST with the addition

of a second research associate. These are two examples of our work to improve the accuracy base for

chemical measurements on a collaborative basis.

In several weeks, we will cosponsor a conference at NIST with 13 professional, government, and industrial

organizations on Clinical Laboratory Measurements: Accuracy and Patient Needs. This is a unique

2
consensus building conference to look at accuracy issues associated with drugs of abuse, HIV (AIDS),

cholesterol, and cytopathology (Pap) testing.

We are excited about our new ventures and look fon^/ard to playing an increasingly important and responsive

role in setting a measurement accuracy base and in meeting the quality assurance needs of the American

analytical chemistry community.

The programs of the Center strive to achieve a balance between the provision of currently needed reference

materials and research efforts on new types of reference materials and methods of measurement. The work

of the Center is performed in three divisions, each focusing upon specific analytes-inorganics, organics, and

gases and particles. Within each division there are several groups representing separate analytical chemical

disciplines, e.g, mass spectrometry and electrochemistry. Each division is responsible for a program in basic

and applied research and maintains contacts with appropriate scientific and user communities.

In the following pages, some of the recent activities, technical directions, and outputs of the Divisions and

groups are summarized.

3
B. Outputs and Interactions

(Center for Analytical Chemistry)

1. Publications

Hertz, H.S., Are Quality and Productivity Compatible in the Analytical Laboratory? Anal. Chem. 6Q, 75A-80A

(1988).

Hertz, H.S., The How and Why of An Accuracy Base for Proficiency Testing Programs (with Michael J. Welch), Archives of Pathology and Laboratory Medicine 112. 343-345 (1988).

Taylor, J.K., "Defining the Accuracy, Precision, and Confidence Limits of Sample Data," in Principles of

Environmental Sampling. L. Keith, Ed., ACS Symposium Series No. 360 (1987).

Taylor, J.K., "Quality Assurance of Chemical Measurements," Lewis Publishers, Inc., Chelsea, Ml 48118,

335 (1987).

Taylor, J.K., "How Good is your Data?," CHEMTECH, 74-77, March 1988.

Taylor, J.K., "Taking Relevant Samples," CHEMTECH, 294-296, May 1988.

Taylor, J.K., "Importance of Quality Assurance," Proceedings of the Accuracy in Trace Analysis

Symposium, Journal of Research of the National Bureau of Standards, Vol. 23. Number 3, p. 232,

May-June 1988.

Taylor, J.K., "Quality Control Data," Proceedings of the Ecological Quality Assurance Workshop, USEAP,

Forest Response Program, Corvallis, Qregon 97333, September 1988.

Taylor, J.K., "Statistics in Chemical Measurement," MGI Management Institute, Harrison, NY 10528, 122,

(1988).

2. Talks

Hertz, H.S., "The What, Why, and How of Future Chemical Measurements," International Conference on

Laboratory Automation, Boston, MA, Qctober22, 1987. Invited

Hertz, H.S., "Quality Assurance, Reference Materials and the Role of a Reference Laboratory in Environmental Measurements, International Symposium on Trace Analysis in Environmental

Samples and Standard Reference Materials, Honolulu, Hawaii, January 6, 1988. Invited

Hertz, H.S., "What is Accuracy," Media Workshop on Accuracy In Medical Testing, National Institutes of

Health, Bethesda, M D, April 12, 1988.

Hertz, H.S., "An Overview of NCCLS," National Committee for Clinical Laboratory Standards Regional

Meeting at the Gaithersburg Marriott, Gaithersburg, MD, April 26, 1988. Invited

Hertz, H.S., "An Overivew of NCCLS," NCCLS Executive Committee Meeting, New Orleans, LA, July 23,

1 988. Invited

4
Taylor, J.K., "The I mportance of Quality Assurance," Accuracy in Trace Analysis - Accomplishments, Goals,

Challenges Symposium, NIST, Gaithersburg, MD, September 28-October 1, 1987.

Taylor, J.K., "Quality Control Data," Ecological Quality Assurance Workshop -USEPA, Denver, CQ, March

30, 1988.

Taylor, J.K., "The Role of Statistics in Reference Material Measurements," 3rd International Symposium on

Biological Reference Materials, Bayreuth, Germany, May 7, 1988.

Taylor, J.K., "Systematic Approach to Chemical Analysis," ACS Meeting, Toronto, Canada, June 6, 1988.

Taylor, J.K., "The Importance of Data Quality in Understanding and Controlling Emissions from Combustion

Sources," ACS Meeting, Toronto, Canada, June 1988.

Taylor, J.K., "Assessing the Quality of Data," 30th Rocky Mountain Conference, Denver, CQ, August 2,

1988.

3. Committee Assignments

Harry S. Hertz

Chairman, Education Committee, American Society for Mass Spectrometry

ASTM, Committee D19 on Water

ASTM, Committee E48 on Biotechnology

President, National Committee for Clinical Laboratory Standards

Analytical Laboratory Managers’ Association

Department of Energy Health and Environmental Research Advisory Committee

FDA, Device Good Manufacturing Practice Advisory Committee

John K. Taylor

ISQ/TC48, Glassware and Related Apparatus

ISQ/TC48/SC01, Volumetric Glassware

ISQ/TC146, Air Quality

ISQ/TCl 46.01, Stationary Source Emission

ISQ/TCI 46.02, Work Place Atmospheres

ISQ/TCl 46.03, Ambient Atmospheres

ISQ/TCI 46.04, General Aspects

ASTM D19.01, International Standards

ASTM D22, Sampling and Analysis of Atmospheres

ASTM D19, Water

ASTM D10.02, General Specifications and Technical Resources

ASTM D19.05, Inorganic Constituents in Water

ASTM D19.07, Sediments

ASTM D22.01, Quality Control

ASTM D22.02, Source Measurements

ASTM D22.03, Ambient Measurements

ASTM D22.04, Analysis of Work Space Atmospheres

ASTM D22.05, Indoor Atmospheres

ASTM D22.06, Acid Deposition

ASTM D22.09, ISQ TAG for ISQ/TC146

5
ASTM E34, Occupational Safety and Health

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

ASTM E36.10, Generic Criteria

ASTM E36.30, Nomenclature and Definitions

ASTM E41 , Laboratory Apparatus

ASTM E41.01, Glass and Plastic Apparatus

ASTM E41 .06, Weighing Devices

ASTM E41.07, Microchemical Apparatus

Collaborative Testing Subcommittee - Standard Methods

Advisory Committee - CHEMTECH (ACS)

ACS Committee on Environmental Chemistry - Subcommittee on Environmental Analytical

Chemistry

Member, Editorial Board, AOAC

4. Sessions Chaired. Workshops and Conferences Organized

Harry S. Hertz

Symposium on Mass Education Introduction Lectures from Our Short Courses at the 36th

American Society for Mass Spectrometry Conference on Mass Spectrometry and Allied Topics,

San Francisco, CA, June 3-10, 1988.

5. Center Colloquium Series

October 15, 1987

Sushma Palmer, National Academy of Science, Recommended Dietary Allowances Sciences

November 18, 1987

Haleem Issaq, Frederick Cancer Research Center, Analytical Chemistry In Cancer Research

February, 9 1987

John Bradley, McCrone Associates, Electron Microscopy of Interplanetary Dust

January 13, 1988

Devendra Lai, Scripps Institute, Terrestrial Cosmogenic Isotopes

March 19, 1988

Dale Schoeller, University of Chicago, Isotope Ratio Mass Spectrometery for Validating Dietary

Intake

May 11, 1988

Peter Jurs, Pennsylvania State University, Prediction by Physiochemical Properties by Computer

Methods

May 19, 1988

T.M. Thompson, NOAA Air Resources Laboratory, Trichlorofluoromethane (CFCll) and

Dichlorodifluoromethane (CFC12) in the Western Pacific and Eastern Indian Oceans’

Atmosphere and Surface Water

6
June 8, 1988

William Fateley, Kansas State University, Hadamard Transform Spectroscopy Analytical

Application

September 28, 1988

William Betts, Supelco, Inc., Use of Class I Non-Specific Adsorbents for the Adsorption and

Subsequent Thermal Desorption of Organic Contaminants in Air, Water, Soil, and Other Sample

Matrices

C. Service Analysis

J.R. Moody and N.M. Crockett

The availability of Center for Analytical Chemistry analytical expertise to other institutions is an important

service function. In addition to service analyses, CAC is frequently called upon to consult or advise, to

provide various metrological calibrations of a chemical nature on a wide variety of industrial and research

materials, and to provide analytical services of a unique nature such as compositional mapping, depth

profiling, or ultra-trace analysis. These services are available to private industry when the uniqueness of

the CAC capability has been demonstrated, and similar services are not available in the private sector.

All outside work is performed on a purchase order, while within NIST funds are obligated on an inter-division

work order. The CAC staff Is committed to providing the most timely, cost effective, and scientifically valid

data possible. The time required varies upon such factors as size of the job and the availability of personnel.

The simpler calibrations or analyses are typically completed in a few days to a few weeks. In all cases,

work is performed on a cost reimbursable basis.

In FY88, CAC staff provided analyses or recalibrations for a total of 1 34 requests with a total reimbursable

cost of $367,000. These requests and their associated funding were split among the three categories of

customers as follows: NIST - 16 jobs ($108,700); other government agencies - 17 jobs ($129,000); and

private industry - 1 01 jobs ($1 29,300). Requests for service work from private industry are now the largest

category, reflecting a slow but steady growth in these requests. Overall, the dollar volume of service

analytical and calibrations performed in FY88 are up about 23% from FY87.

7
II. Inorganic Analytical Research Division

James R. DeVoe, Chief

William F. Koch, Deputy Chief

A. Division Overview

The Inorganic Analytical Research Division conducts research that is directed toward improving the accuracy

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

form of basic studies on potential new directions in chemical analysis as well as improvements to existing

methods. In addition, the Division uses accurate methods to certify Standard Reference Materials, to provide

analytical services for other government agencies, and to provide analytical support for solving problems

related to national needs. The Division is organized into four Groups which are oriented to specific technical

disciplines. The Groups are: Analytical Mass Spectrometry, Atomic and Molecular Spectrometry,

Electroanalytical Research, and Nuclear Methods.

Our basic research program is directed toward the understanding of physico-chemical phenomena that will lead to an improvement in the accuracy of inorganic elemental analysis. This effort consumes some 5-10

percent of our budget and involves such studies as material transport of conducting solids by spark erosion,

use of cold neutrons for nuclear methods of analysis, use of lasers in optical and mass spectroscopies, and

the electrochemical properties of liquid junctions between half-cells. Out of our previous research efforts

has come an important contribution to the measurement of conductance of electrolytes. A newly designed

conductance cell makes it possible for the first time to measure directly the cell constant, thereby improving

the accuracy by a factor of five. For this work we are pleased that Drs. Wu, Pratt and Koch have been awarded

an R&D-100 award for 1988.

By far the largest effort, comprising approximately 60 percent of our budget, is the development of methods

suitable for the accurate analysis of a variety of materials of interest to industry, other government agencies,

and the Standard Reference Materials program. The paragraphs to follow discuss some of this effort in more

detail.

This is the third year in our effort to regain lost expertise in wet chemical methods of analysis. We have now

demonstrated a capability for both gravimetric and titrimetric methods. These methods have been selected

to be complementary to existing capabilities. In addition, with contemporary methods of trace element

analysis, we are in a position to measure the purity of separations by precipitation or extractions with a much

higher degree of sensitivity than in the past. This should result in improvement in the accuracy of these

methods. At the same time, we are exploring the possibility of automating some of these procedures to

improve the reproducibility and to reduce tedium.

We have had a number of very important interactions and scientific exchanges with industry encompassing

all facets of method development. For example, one of our staff spent six weeks at the Perkin-Elmer

Corporation learning more about the coupling of instrument design with analytical applications and studying

how accuracy in the measurements can be improved. We have a scientist from Eastman Kodak spending

an extended period of time with us learning clean room sample processing and chemical separations for

ICP-MS and OES. Over the years we have developed an unique expertise in the purification of acid reagents

for sample dissolution. We are currently providing, for their evaluation, ultra-pure hydrofluoric acid to several

chemical companies that produce analytical reagents. In addition, we have active collaborations with other

companies to help them develop accurate methods of chemical analysis. These interactions are with the

GEM Corporation on microwave methods of sample dissolution, Zymark Corporation on the use of laboratory

robotics to prepare samples (chemical dissolution as well as separations) prior to instrumental analysis.

8
Finnigan Mat on the evaluation of multi-element capabilities of thermal ionization mass spectrometry, and

Dionex Corporation on the use of liquid chromatography for chemical separations. We have, for a number

of years, had interactions with semi-conductor manufacturers, such as Intel, IBM, Eastman Kodak (EK) and

Motorola, on trace elemental content using both trace element bulk analysis and neutron depth profiling

(NDP). As a result of these efforts EK has provided funds for a new NDP instrument to be used with the cold

neutron facility operated by the Nuclear Methods Group. Finally, under the auspices of the NCCLS we have

a major program with eight instrument manufacturers of clinical potentiometric analyzers to improve

accuracy in and to bring uniformity to the measurements of electrolytes in blood.

In view of the exponential growth in our capability to acquire and process information via desktop personal

computers, whether it be quantitative analytical results or bibliographic data on analytical methods, we have

explored the use of computer-based decision support systems to aid in the management of this information.

Professor Frank A. Settle from Virginia Military Institute (VMI) has been with us this past year and has

developed a prototype "expert system" that demonstrates an approach to handling analytical procedures

using microwave heating of samples for dissolution.

Considerable effort has been placed within the Division on evaluating our methods development for the

certification of Standard Reference Materials. Many of our studies have centered around the experimental

design that includes all facets of the certification process. Out of these deliberations have come a number

of ancillary studies such as a more detailed investigation of dissolution processes and possible elemental

losses therein, the generation of proper conditions for establishing constant weight of samples to be analyzed

along with possible elemental losses, and the establishment of valid methods to determine the homogeneity

of concentration of the elements throughout the bulk of the material to be certified. In addition, when

discrepancies between methods occur detailed experimental designs are generated at the Group Leader

and Division Chief level to correct the source of error.

The remainder of our budget, approximately 20%, is devoted to the certification of Standard Reference

Materials (SRMs). We have had a productive year in certifying SRMs with over 280 elements measured in more than 1 0 materials. As part of our commitment to improve the quality and expand the use of SRMs, we

have instituted the policy of assigning a senior scientist within the Division as the technical focal point for the

certification of a specific reference material. This "technical champion" is responsible for all technical and

scientific aspects of the process from the sampling and collection of the material through the design of the

certification to the interpretation of the results. This person is the primary contact on technical matters with

the corresponding person in the Office of Standard Reference Materials. The first major material to be

certified using this process is SRM 2704, Buffalo River Sediment, and from all indications this will be an

outstanding reference material.

Our plans for new areas of research have been selected from a large number of excellent ideas generated

by some of our most talented senior scientific staff. The number of projects is unfortunately constrained by

our funding and available staff. Those projects that have been selected are the focussing of cold neutrons

for the development of a neutron activation analysis microprobe, the applications of a UV-visible Fourier

transform spectrometer, the thermodynamics of the sample dissolution process, and the use of ion sputtering

in laser mass spectrometry. For method development, emphasis will continue on the use of "wet" chemistry,

but using it in conjunction with the latest developments in instrumental methods. It is unfortunate that the

universities have all but ceased adequate training in the wet chemistry area, and that analytical laboratories

such as ours must take on this educational role. Considerable effort will be spent in the future on preliminary

evaluation and validation of proposed reference materials at a much earlier time than is currently done.

Validation includes most of the parameters which we have studied these past few years as indicated in the

above paragraphs. Our staffing plans include replacement of senior staff where the need exists and adding

new expertise in areas that we consider of new importance. In addition, we intend to hire more junior staff

9
(e.g., at the BS level of education) to support our senior staff. This will lead to much better time utilization as well as potentially reducing the cost of analyses for the certification of SRMs.

This past year, we have established a pure reagents committee which has the responsibility for evaluating

materials to be used as calibration standards and/or reagents for chemical processing. This committee will be responsible for obtaining the purest materials available and for the characterization of such materials.

With increasing emphasis on the purity of materials and their stoichiometry, such as with super- and

semi-conductors, we intend to be the focal point for the purest available materials.

1. Analytical Mass Spectrometry Group: Overview

The Analytical Mass Spectrometry Group performs compositional measurements using the analytical

sciences of chemical separation and mass spectrometry. For many years, the Group has been involved in making isotope ratio measurements with the highest precision and accuracy. These measurements are done

using thermal ionization mass spectrometry on highly purified elemental materials. The separation of

elemental species, often from very complex matrices, with high efficiency and low contamination, is an

expertise that is required to complement the capabilities of thermal ionization mass spectrometry for making

precise and accurate isotope ratio measurements. The Group has applied these measurements to the

determination of the atomic weights of the elements and chemical analysis by the technique of isotope

dilution. While maintaining the basic thrust in the traditional areas, the horizons of the Group have broadened

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

spectrometry have been introduced.

An inductively coupled plasma mass spectrometer (ICP-MS) has been in operation in the Group since 1985.

This instrument is becoming one of the most popular new analytical tools for elemental determination

because of its high sensitivity, direct sample introduction, and broad elemental coverage. It has been applied

to a variety of programs within the Group. The ICP-MS has replaced the spark source mass spectrometer

as the method of choice for the characterization of high-purity reagents that are produced in the Group. The

sensitivity of ICP-MS is higher for all elements, some by an order of magnitude and more; sample throughput

is dramatically improved; and, the total number of elements quantified is almost double (37 versus 19).

Isotope dilution analysis has been done for SRM certification which required no chemical separations. The

best isotope ratio precisions to date have been made in the calibration of standard solutions, approximately

0.25%. The instrument has been used in concert with liquid chromatography as a species-specific element

detector and mercury compounds have been quantified in a variety of materials. Also, the ICP-MS is being

applied to determine trace Nd in a number of materials, including La, as part of a program to produce efficient

optical fibers. The development of procedures to separate Nd from La is required in this project and the

ICP-MS has been used interactively in developing this difficult separation as well as for the ultimate analysis.

High precision thermal ionization mass spectrometry (TIMS) is now done in the Group using the traditional

NBS-built instruments and a multicollector, fully automated commercial instrument. The redetermination of

the atomic weight of nickel is essentially complete, except for the statistical analysis of the data. This work

was done on both types of instruments and a comparison of the results is of considerable interest. The ratio

measurement precisions of a few parts in 10^ will result in an atomic weight determination improved by a

factor of 10-100. The multicollector TIMS instrument has also been applied to other programs of high

precision isotope ratio measurement, including Nd tracer work and isotope dilution analysis of lead in a new

series of fuel SRMs. The instrument has demonstrated parts-per-million internal precisions. Procedures

have been developed for the high precision isotopic measurement of both boron and lithium, which will allow

the more accurate measurement of these elements by isotope dilution. In the past, measurement precisions

for these elements have been poor because of the relatively large mass difference between the isotopes. In the last year, an effort has begun to develop multielement isotope dilution TIMS procedures. We hope this

10
effort will make isotope dilution more generally applicable and economically competitive by increasing

analytical throughput, while maintaining the highest precision and accuracy. The Group has made significant

contributions to the certification of various Standard Reference Materials by TIMS in the past year, especially

for the determination of sulfur.

The laser resonance ionization mass spectrometry (RIMS) program has continued, primarily on the basis of

interactions and collaborations with scientists both within and outside National Institute of Standards and

Technology (NIST). The NIST program was highlighted at the 4th International Symposium on Resonance

Ionization Spectroscopy (RIS), which was held at Gaithersburg in April 1988. The unique application of RIMS

to Os/Re problems in isotope geology has created much excitement and a demand for instrumentation. The

Group has helped in the building of a RIMS instrument at the Carnegie Institute of Washington. RIMS is also

being applied to the analysis of high purity semiconductor devices. Vanadium has been chosen to

demonstrate the selectivity of the resonance ionization process; interferences by chromium and titanium

make mass spectrometric measurement of vanadium at ultratrace levels extremely difficult.

The Group has designed and built several pieces of analytical instrumentation in the past year. A

state-of-the-art magnet controller is presently being evaluated. A filament degas vacuum system has been

redesigned and built. It promises faster and more reliable preparation of sample filaments. The Group has

provided a duplicate of this system and built a quantity of other NIST-designed electronic components,

including the IR-100 award winning parametric amplifier, as a service to academic, governmental, and

industrial organizations. The Group designed and built a high-capacity still this year, which initially has been

used to produce ultrapure hydrofluoric acid. This acid is absolutely essential in the preparation and analysis

of several high technology materials, including optical fibers and semiconductors.

In the future, the general research program of the Analytical Mass Spectrometry Group will continue to be

directed toward goals of improving sensitivity, applicability, precision and accuracy of isotopic ratio

measurements. The program will continue to encompass state-of-the-art instrumentation and emerging

ideas and concerns in inorganic analysis. The use of isotopic tracers in environmental and other studies will certainly play a major role in the activities of the Group. An anticipated continuation of the feasibility study

that was done for the Electric Power Research Institute on the use of rare earth isotopes as tracers of power

plant emissions is one example of our activity in this area. The development of new atomization techniques

in laser mass spectrometry and the measurement of radioactivity by mass spectrometry are both areas with

potential for the future.

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

Emile C. Joel, John W. Gramlich, W. Robert Kelly, George M. Lambert, John R. Moody, Thomas J. Murphy,

Paul J. Paulsen, Liu Qi, Ronald W. Shideler, Richard J. Walker, and Xiao Yingkai.

2. Atomic and Molecular Spectrometry Group: Overview

The Atomic and Molecular Spectrometry Group investigates fundamental processes in atomic and molecular

spectroscopies to develop new analytical techniques and to improve existing analytical methodology.

Research and development activities include areas of atomic emission, absorption, and fluorescence

spectrometry, as well as resonance ionization mass spectrometry (RIMS), and the application of laser

enhanced ionization (LEI) processes in flames and photoionization processes in mass spectrometry. The

developmental research emphasizes the detection of all random and systematic errors and applying these

resulting methodologies to the certification of Standard Reference Materials (SRMs).

LEI spectrometry has proven to be a very sensitive method for determining certain trace elements. Complex

matrices have been analyzed accurately by incorporating chemical separations prior to the instrumental

11
measurement step. Separations are necessary because background levels, line shapes, and noise are

related to the presence of easily ionized species in the flame. Research on the fundamental processes of

laser excitation and ionization has been undertaken with the development of an instrumental system for

simultaneous LEI and laser induced fluorescence (LIF) measurements in the flame. This capability is being

used to characterize and correlate noise sources, as well as to investigate excitation wavelength profiles.

Understanding these phenomena is crucial to dealing with interferences caused by easily ionizable elements

in analytical samples. Other methods for reducing the effects of eiemental interferences have been developed

including the use of liquid chromatography (LC) with LEI spectrometry. Tributyltin (TBT) has been

successfully separated from dissolved samples of marine sediment using LC. LEI has then been used as a

tin-selective detector with a detection limit of 9 ng Sn/g sediment.

A number of analytical methods are being investigated which involve direct sampling of the solid material to

be analyzed. The goal of this research is to improve sensitivity by eliminating the diiution of analyte inherent

in the chemical dissolution step and to improve accuracy by avoiding analyte losses due to incomplete

dissolution of complex samples. LIF has been used to examine the direct solid sampling characteristics of a commercial glow discharge sputtering source. Back-scattered fluorescence has been detected for Fe in a copper matrix, but further refinements in the collection optics are still necessary to realize our goal of ppb

detection limits in the solid. Direct solid sampiing also has been investigated to improve the sensitivity of

trace contaminant detection in silicon-based glasses using atomic absorption spectrometry (AAS) with

Zeeman effect background correction. Direct injection of the solid powder with the appropriate matrix

modifier allows in-situ digestion and quantitation of trace elements using aqueous standards. For SRM 61 4,

Trace Elements in Giass, Co, Cu, Fe, and Ni were found to be within the certified range for these elements.

The analysis of aluminum- and zirconium-based glass matrices is also being investigated. A related technique

of slurry sample introduction also has been developed to assess the homogeneity of sediment Standard

Reference Materials. This approach allows a rapid means of monitoring the blending process for a candidate

SRM and for determining its sampling constant.

The attainment of accuracies and precisions to better than 0.2% relative for major and minor constituents is another active area of research and methods development in the Group. Methods for measuring the

stoichiometry of superconducting materials have been devised using inductively coupled plasma (ICP)

spectrometry. Stoichiometry is measured in a highly precise and accurate mode of analysis using

simultaneous internal standardization to reduce correlated noise. The principal advantage of the ICP

approach is its speed and overall uncertainty of less than 0.5% relative for the elements Cu and Y in Ba-Y-Cu-0

superconducting compounds. Detection of trace element contaminants in these materiais is aiso

accomplished in a survey sequential mode of analysis that checks for the presence of 36 elements.

The continued development of integrated techniques involving both instrumental spectrometry and classical

chemical analysis has enabled the Group to determine major and minor constituents in geological materials

with high accuracy and precision. Analysis of filtrates and redissolved precipitates has significantly

decreased the number of chemical separation steps required to correct for interferences in gravimetric

analyses. This effort has also included the utilization of automated titrimetry, automated separation methods,

and microwave dissolution techniques to improve the accuracy and to shorten the time required to complete

the analyses.

Homogeneity testing and analysis for certification of SRMs continue to be principal activities in the Group.

This year, approximateiy 100 elements in over 75 materials were determined. Calibration studies have

focussed on the need for more accurate values for boron in a number of low alloy steel SRMs to be used by

spark emission spectrometry. Sixty-three single element spectrometric calibration solution SRMs have been

produced, and a number of other SRMs, including bovine serum, oyster tissue, total diet, and apple and

peach leaves were analyzed by a variety of methods in the Group. Optical filter absorbance SRMs continue

12
to be certified and special calibrations of other optical filters have been completed for customers. The

process of certifying elements in the candidate Buffalo River Sediment SRM was completed this year. This

effort began three years ago by one of the Group members, who designed and coordinated the entire

certification process including both NIST and outside laboratory analysis activities.

Materials also have been analyzed for other government agencies. For example, the correlation between

material failure and chemical composition of machine bolts has been carried out in cooperation with the NIST

Institute for Materials Science and Engineering. Welds and baseplates from the collapsed oil tank in Pennsylvania were examined using spark optical emission spectrometry. Participation in round-robin studies

has continued in support of a National Cancer Institute study of Ca, Se and Zn in blood, and Al has been

determined by atomic absorption spectrometry in a Food and Drug Administration serum albumin reference

material.

The effort to update and automate analytical instrumentation in the Group has continued with the modification

of the high-accuracy optical filter spectrophotometer system and the acquisition of a computer-controlled

microwave oven for sample dissolution. The Group continues to benefit from programming and computer

application expertise which leads to both precise and accurate control of instrumental systems, as well as complete statistical analysis of data.

The Group has maintained its high level of cooperative research with NIST and visiting scientists. For

example, we have worked with Joseph Bodkin at the Mineral Constitution Laboratory of Pennsylvania State

University to become familiar with classical methods of analyses. Mr. Bodkin has also worked in the NIST

laboratories continuing the development of gravimetric and titrimetric analyses. Dr. Michael S. Epstein has

spent six weeks working in the product development laboratory of Perkin-Elmer Corporation to study the

application of new commercial atomic spectrometric instrumentation for high accuracy analysis of SRMs

and the slurry sample introduction for AAS homogeneity assessment. A number of foreign guest scientists

continue to work in our laboratories investigating methods of analysis of pure reagents and compounds. Dr. Radu Mavrodineanu returns to the Group periodically to consult on the calibration of optical absorbance

filters. This consultation has assisted us in maintaining our high-accuracy absorbance measurement

capabilities since Dr. Robert W. Burke retired from the Group.

In the future, the Group plans to continue applying laser techniques to the accurate analysis of SRMs, using

chemical separations to reduce or eliminate matrix effects. We will pursue LIF in the glow discharge

sputtering device, as well as investigate opportunities for determining C, N, and P using multiphoton

ionization. Both Nd-YAG and diode lasers will be used to probe the glow discharge as a source of atomic

vapor for spectrometric analysis, and work will continue on LIF and LEI in a power-modulated ICP. There

will be an increase in focus on the accuracy of dissolution methods. Incomplete dissolution and losses of

volatile elements will be examined. Several methods including neutron activation analysis, available in the

Nuclear Methods Group, will be used to detect such phenomena. Group chemical separations will continue

to be examined to provide both spectrometric techniques and classical methods with matrix interference-free

samples for analysis. A new area of research in ultra-high resolution spectroscopy using Fourier transform

spectrometry will be instituted in the Group. Accurate spectral line identification and unambiguous

characterization of line interferences will be among the goals of this effort.

Robert L. Watters, Jr., Group Leader; Therese A. Butler, Alissa M. Conklin, Nicole M. Eaton, Katherine S.

Epier, Michael S. Epstein, Roger T. Fang, Robert C. Gauer, Radu Mavrodineanu, John A. Norris, Theodore

C. Rains, Fillmer C. Ruegg, Theresa A. Rush, Francis H. Shen, Johanna M. Smeller, Melody V. Smith, John

C. Travis, Gregory C. Turk, Thomas W. Vetter, H.S. Wang, Laura J. Wood, and Z. Xu.

13
3. Electroanalytical Research Group: Overview

The Electroanalytical Research Group conducts basic research and utilizes electrochemical principles and

chromatographic separations to develop new techniques, to improve existing techniques, and to apply them

to chemical analyses. The techniques in practice include amperometry, chelation chromatography,

conductimetry, coulometry, ion chromatography, polarography, potentiometry, robotics, supercritical fluid

chromatography, titrimetry and voltammetry. Research activities are directed toward attaining a more

thorough understanding of electrochemical systems, thermodynamics and exchange mechanisms

encountered In the development and implementation of electroanalytical and separation methods.

The Electroanalytical Research Group continues to expand its resources and scope of research through a

number of professional collaborations such as the Research Associate Program (RAP), and by utilizing guest

scientists from both Industry and universities. In addition, the Group maintains its involvement with ASTM,

the American Water Works Association (AWWA), the International Union of Pure and Applied Chemistry

(lUPAC), and the National Committee for Clinical Laboratory Standards (NCCLS).

There are three RAP projects in the Group. A research program with CEM Corporation, a producer of

microwave equipment for research purposes, has the goal of developing techniques for the dissolution of

samples in closed vessels within a microwave heating chamber. A second RAP Is sponsored by the NCCLS

and Is funded by a consortium of eight manufacturers of potentiometric analyzers for clinical applications.

The purpose of this project is to develop reference materials and methodology for measuring the activity of

free ionized sodium, potassium, and calcium in serum with Ion-selective electrodes. The third RAP is with

the Dionex Corporation to develop ion chromatographic separations of the transition metals. The

applicability of chelating resins to ion chromatography Is being investigated and has led to the development

of a new procedure for which a joint patent application with the Dionex Corporation has been submitted.

Progress is being made in electrolyte theory with the help of a number of noted experts such as Harold

Friedman (State University of New York at Stony Brook), Walter Hamer (NIST retired), Vincent Bower (NIST

retired), Rabindra Roy (Prof, of Chemistry, Drury College), Robert Wood (Prof, of Chemistry, U. Delaware),

Robert Kay (Prof, of Chemistry, Carnegle-Mellon Inst.), and Arthur Covington (Prof, of Chemistry, U. of

Newcastle-Upon-Tyne, GB). The plan to improve the state of pH measurements and standards may

ultimately lead to a single, unified pH scale. The problem of standardizing high ionic strength pH

measurements has been approached in two ways. First, with the help of several guest scientists including

Feng Darning, a guest scientist from Guangzhou Research Institute of Non-ferrous Metals, Peoples Republic

of China, Prof. R. Roy and P. Lord, Drury College, studies have been initiated to better understand and

characterize the liquid junction potential. A flowing liquid junction cell has been designed that has a highly

reproducible and predictable liquid junction potential. Second, the thermodynamics and transport

phenomena of multi-component systems have been explored using the cross-square rule which is a theory

describing ion-ion interactions. A paper has been prepared describing these Investigations. To aid in the

measurement of pH in physiological solutions, such as serum, a zwitterionic buffer (HEPES/HEPESATE) has

been certified as a pH Standard Reference Material. This SRM is the first pH standard with certified values

given at an ionic strength of 0.15, similar to that found In serum.

Work has been completed, in collaboration with Division 553, on the automation of the separation of the

transition elements from the alkali and alkaline earths for biological samples that are to be analyzed by X-ray

fluorescence. In addition, a study has been initiated on the applicability of supercritical fluid chromatography

and reversed-phase HPLC for metal separations. Ion chromatography has been extensively used for

determining sulfur and chloride In a variety of SRMs (coals, oils, oyster tissue, total diet). Two new Anion

Standard Solutions (nitrate and phosphate) at concentrations of 1000 g/g have been tested and shown to

14
be stable for at least one year. Fluoride in timothy grass and oyster tissue has been determined using oxygen

bomb combustion, followed by ion-selective electrode potentiometry.

Research is continuing in the development of aqueous electrolytic conductance standards. A novel

conductance cell using a variable, but accurately known cell length, has been designed and implemented.

This approach has resulted in an absolute measure of the cell constant and has confirmed and improved the

accuracy by a factor of five for the secondary standard, as recommended by the International Organization

of Legal Metrology (OIML) for the specific conductance of aqueous solutions of KCI. Drs. Wu, Pratt and

Koch have received an R&D-100 Award for this unique cell design. Two new Standard Reference Materials

have been produced and certified with this new system.

This year there have been a number of new procedures for dissolving samples by microwave heating. For

example, methods have been developed to replace current EPA procedures for the dissolution of solids in

water, oil, soil, and sediments. These procedures will result in considerable time savings as well as Improving

the accuracy of the analyses. The first reference book on microwave-assisted sample preparation has been

completed. It contains fundamental theory and reference data for predicting temperature conditions from

estimates of input power. A very sensitive electrochemical means of determining if trace organics or metal-bound organics remain after microwave-assisted sample digestion has been developed .

The project to Investigate the utility of robotics for laboratory use is well underway with the successful

demonstration of a chelation separation of metals under computer-assisted robotic control. Work this year

has concentrated on upgrading the hardware and software needed to improve reliability. The system was

used to separate a number of transition elements for several SRMs, such as the river sediment, mixed diet,

and orchard leaves which are currently in the process of certification.

Dr. Frank A. Settle from Virginia Military Institute has completed a sabbatical at NIST. Using a commercial

"shell" type of expert-system software, he has completed a prototype system to assist the analyst in selecting

appropriate conditions and thereafter to set up and control microwave equipment for acid decomposition of

samples. This work is believed to be the forerunner of software which will aid the analyst in selecting proper

conditions for performing a variety of chemical analyses.

Of particular significance was the preparation and certification of a frozen bovine serum SRM (1598) under

the technical guidance of Dr. H.M. Kingston. This SRM, a cooperative effort with USDA, has several elements

certified at the lowest concentrations in any standard material of this type.

Research In pH will continue as a long-term commitment to provide reliable and thermodynamically

significant measurements and standards. The development of a series of matrix-specific pH standards is a

high priority. The group plans to prepare and certify additional zwitterionic pH Standard Reference Materials

for use In physiological pH measurements. Investigations in aqueous conductance will continue in

collaboration with the Hungarian Office of Measures.

An important research direction for the Group is, and will continue to be, in the area of separations science.

Most, if not all, instrumental techniques can perform at their optimum sensitivity, selectivity and accuracy

only if sample matrices identical in nature to the calibration standards are used. The goal of this separations

research will be to develop the means of providing such samples through the exclusion of interfering metals,

the removal of major constituents, and the preconcentration of trace metals. Speciation of the metals by

valence and complexation may also be possible. Novel chelating resins are in the developmental stages

and will be applied in conjunction with ion chromatographic separations. The direct combination of chelation

chromatography with spectroscopic Instrumentation Is being evaluated.

15
Advances in ion chromatography will be explored to lower the detection limit and expand its applicability to

new elemental species. Flow-injection analysis with electrochemical detection will be implemented for the

determination of ultra-trace metals in complex matrices. Voltammetry will be used extensively as a valuable

analytical research technique in metal determination and speciation.

Expert systems coupled to automated equipment and robots can provide the flexibility required to achieve

fully automated procedures for sample preparation. Research in the use of laboratory robotics for

microwave-assisted acid decomposition has been initiated. A demonstration project has been started to

adapt a commercial shell expert system to address the needs of analytical chemists and to assist them in seiecting the best method of decomposition from an ensemble of procedures. Ultimately, this expert system

will drive the laboratory robot.

Howard M. Kingston, Acting Group Leader; Jeffrey H. Barr, Zou Chun, Courtney A. Clements, Feng Darning,

Xie Guirong, P. Chandrani Gunaratna, Lisa A. Holland, Lois B. Jassie, William F. Koch, Pamela J. Lord, George

Marinenko, Margo D. Palmieri, Kenneth W. Pratt, Rabindra Roy, Frank A. Settle, Archava Siriraks, Peter J. Walter, and Yung Chi Wu.

4. Nuclear Methods Group: Overview

The development and application of nuclear analytical techniques for greater accuracy, higher sensitivity

and better selectivity are the goals of the Nuclear Methods Group. A high level of competence has been

developed in reactor-based activation analysis, which includes instrumental and radiochemical neutron

activation analysis (INAA and RNAA). In addition, the group has a unique capability in neutron beam anaiysis

with both prompt gamma activation analysis (PGAA) and neutron depth profiling (NDP). The NDP technique

utilizes prompt charged particle emission to determine elemental distributions within the first few micrometers

of a surface, while the PGAA technique utilizes prompt gamma-ray emission to measure the total amount of

an element in a sample regardless of its distribution. These techniques provide an arsenal of tools to address

a wide variety of analytical problems in science and technology.

The activities of the past year have been highlighted by the initiation of the National Facility for Cold Neutron

Research to be established at the National Institute of Standards and Technology (NIST) during FY89. The

Group’s involvement includes the design and construction of second generation instruments for PGAA and

NDP. During FY88, the cold source was installed and became operational, and construction of the guide

hall will be completed during the first quarter of FY89. The Group’s efforts have been aided substantially by

its ability to use the existing cold neutron beams at the KFA Julich (West Germany) facility. Plans are underway to include both the PGAA and NDP experimental systems in the first phase of implementation. A

major grant from the Eastman Kodak Company is contributing to the timely development of NDP using cold

neutrons.

The Group’s contribution to the certification of Standard Reference Materials is illustrated by the multielement

measurements done on the SRM Bovine Serum, Buffalo River Sediment, and glass-film XRF standards. Work

has been initiated on the new Orchard Leaves, Total Diet, Oyster Tissue, and a carbonaceous marine

sediment, with Group members serving as the Technical Champions on each of these new SRMs. A new

ability to quantify nitrogen in biological samples has resulted from this year’s research to develop a NAA

liquid-scintillation beta-counting method exploiting the thermal neutron reaction ^"^N(n,p)^"^Cand measuring

the radioactive CO2 . This project is being done in collaboration with the University of illinois.

The Group has taken an active role in the NIST’s program on high-temperature superconductivity, both in the measurement of impurities in starting materials and in final products, and in the determination of the

16
actual stoichiometry of the metallic constituents. The effort this year has been in the development of accurate,

rapid measurements of these materials by both NAA and PGAA.

The Biomonitoring Specimen Bank Research Project continued its support for other agencies’ monitoring

programs. These included the EPA human liver project, the NOAA National Status and Trends program, the

NCI Micronutrient program, the lAEA/FDA/USDA Total Diet Study, and most recently, the NOAA Alaska

Marine Mammai Project. Research has centered on developing protocols and improved analytical

methodology. Our participation in intercalibration exercises with the project participants and the

deveiopment of marine QA materials helped to enhance the quality of the analytical results used in the

assessment of the Nation’s environmental health. Of major importance this year has been the completion

of the re-analysis of 30 livers each, from the 1 982 and 1 984 collections, to quantify the stability of key elements

under the carefully controlled storage conditions.

Bioanalytical research focused on the determination of metal species in various materials. Elements at trace

and ultratrace levels have been determined in separated proteins and other macromolecules. The use of

autoradiography to determine selenium has been added to the INAA and RNAA techniques. The occurrence

of inorganic and organic compounds of tin in marine tissues is also being studied.

The strong interactions with industrial scientists using NDP, PGAA, and NAA has continued with a growing

number of guest workers, research associates, and joint publications. An important development this year

has been the demonstration of two-parameter, coincidence spectroscopy for thin samples in collaboration

with the group under Professor W.-K. Chu at the University of North Carolina and with Scientists at the

Eastman Kodak Company. For appropriate samples, this technique will increase the measurement sensitivity

equivalent to a ten-fold increase in reactor neutron flux. The measurement of distributions of iithiurn and

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

The joint NIST/FDA/USDA study of trace elements in human diet, sponsored by the International Atomic

Energy Agency, has completed its fourth year. A total of 40 minor and trace elements have been measured

on the U.S. total diet material collected from several regions. In addition, measurements have been carried

out.on selected elements in diets received from countries participating in this global study. A candidate total

diet material prepared in cooperation with OSRM is being evaluated as an elemental standard.

Special emphasis will be given to the completion of the initial phases of the design of the cold neutron NDP

and PGAA systems. In addition, a facility is envisioned at which we will study the technique for focusing

neutron beams onto a small area thereby increasing the neutron intensity, with the ultimate goai of generating

an activation analysis milli- or microprobe.

Particular attention will be paid to count rate dependent effects, gamma-ray self-absorption, detector

efficiency calibration, and monitor activation analysis. Maintaining full accuracy at high count rates using

current-generation data-acquisition electronics is the goal of our count rate dependent studies. Accurate

quantification of gamma-ray self-absorption and measurement of the shape of the efficiency curve are

required for accuracy in monitor activation analysis since matching of sample with primary standards is not

done. The development of monitor activation analysis is part of the high-temperature superconductivity effort

to achieve rapid sample turnaround with minimum sacrifice of accuracy; however, the approach will also

provide good quality control when used in parallel with traditional primary standard NAA.

Ronald F. Fleming, Group Leader; M. James Blackman, Donald A. Becker, David M. Byron, R. Gregory

Downing, Kathleen A. Fitzpatrick, Brent L. Grazman, Robert R. Greenberg, G. Venkatesh iyengar, John K. Langland, Richard M. Lindstrom, J. Emien Meyers, Eline R. Mykiebust, Bruce R. Norman, Craig A. Stone,

Susan F. Stone, Theresa M. Sullivan, Dana K. Weiss, and Rolf L. Zeisler.

17
B. Selected Technical Reports

(Inorganic Analytical Research Division)

1. Development of Ion Chromatographic Methods for the Determination of Transition Metals Using

Chelating Resins

A. Siriraks and H.M. Kingston

A new procedure has been developed for coupling chelator chromatography to ion chromatography. The

procedure involves introducing a sample, altering the matrix and integrating the chelation chromatography

into an ion chromatograph. The process allows the elements of interest to be concentrated and separated

from other groups of elements and matrix components that would prevent the use of ion chromatographic

procedures. The equipment configurations and processes makes possible the use of ion

chromatographic analysis for transition elements in many sample categories that could not be analyzed by

simple ion chromatographic procedures for transition metals. This research has led to a joint patent

application between NIST and the Dionex Corporation.

Materials that must be analyzed for trace elements are usually the least compatible with the ion

chromatograph. Because of the natural distribution of elements in real materials, the matrix contains large

amounts of salts as compared to the transition and rare earth elements. This concentration difference can

be from one thousand to one million times greater than the trace transition elements of interest. Ion

chromatography is not used for these common samples but is limited to aqueous samples with salt

concentrations only a few times higher or equal to that of the elements of interest. Using conventional ion

chromatography, these problems prevent many samples from being analyzed (biological, botanical,

geological, and environmental).

With this new method, an iminodiacetate chelating resin is packed in a plastic high pressure (2000 psi) column

and placed before the concentrator column. The alkali and alkaline earth elements are removed and the

counter ion replaced with the ammonium ion. Tests with the traditional chelation resins proved incompatible

and they were replaced by a highly cross-linked iminodiacetate resin to provide stability under pressure.

New conditions were developed to perform chelation chromatography. The chelator column was used to

preconcentrate and preseparate high salt containing samples. The column was then stripped of its remaining elements and a method of placing these ions directly onto the concentrator column was

developed. This procedure required precise control of pH, flow rate, reagent mixing, and ion

concentration. Column capacity matching was used to control the availability of competing ions and the

removal of the metal from the concentrator column. A procedure of controlled reverse flow for removal of

the ions from the concentrator column was used to recombine and compress the element band prior to its entry onto the analytical column. At this point classical ion chromatographic separation procedures and

post-column derivatization are possible for element detection. These procedures have previously been

limited to samples containing no interfering salts. The procedure requires less than one hour for each

sample being analyzed for a group of elements.

The applications for this procedure are divided into several categories. The most obvious is a new type of

chromatography identified as ChIC for Chelation Ion Chromatography. Its uses include the direct analysis

of trace transition metals in a wide variety of real samples. In general, acid-decomposed biological,

botanical, geological and environmental samples are appropriate sample matrices for trace transition and

rare earth element analysis. The elements that can be analyzed are those that can be retained by the

chelating resin. Different elements may require totally different detection systems. Seawater and digested

animal tissues have already been tested for this application. The technique has been used to quantify six

18
elements in sea water at the 1 -5 ppb level and three elements in oyster tissue at the 20-800 ppm level. ChIC

can also be used as a separation system for another analytical instrument that performs the element detection

and quantification. This can be done in two different modes. The first is in a batch mode, where the separated

element or group of elements from the chromatographic instrument is collected in a beaker. This becomes

the sample in a modified matrix on which another analytical instrument performs analysis. The second is the

direct coupling of the chromatographic instrument to another analytical instrument to retrieve the element

or group of elements from the chromatographic stream. The chelator column can be used alone to produce

a group separation and thereby to provide on-line separations whose products can be introduced into other

analytical instruments, thus, increasing sensitivity and removing interfering elements.

2. Interiaboratory Test Studies for the Development of Reference Materials for Potentiometric

Sodium and Potassium Measurements in Human Serum

W. F. Koch, P. C. Gunaratna, and R. C. Paule

Ion selective electrodes (ISEs) have gained widespread acceptance as the method of choice for measuring

electrolyte concentrations in biological fluids. Since such measurements can be performed in undiluted

specimens, the measurements can be made with less sample preparation, and hence tend to be faster and

more reliable. The required instrumentation for ISE determinations is less complicated than flame

photometers, and generally less training is required to operate ISE apparatus on a routine basis than that for

flame measurements. Furthermore, because ISEs respond to the ionic activity rather than to the

concentration, the measurements may be physiologically more relevant, at least in the ideal. However, the

theory necessary to determine electrolyte activity accurately in biological fluids has yet to be developed.

Because of the historical acceptance of flame photometric values for electrolytes (especially for sodium and

potassium) in biological fluids, it is desirable that the values obtained by ISEs in undiluted specimens be

consistent with the flame values. This avoids complications in defining different reference ranges and

minimizes confusion and possible errors in diagnosis and treatment. However, as alluded to above, there are fundamental differences in the measurements, which make consistency in the reported values more a

matter of convention than of hard science. In brief, the flame method (and to a certain extent, ISE

measurements in diluted samples) measures total concentration of a given electrolyte (e.g., sodium) in a

given volume of solution. On the other hand, the ISE method applied to undiluted specimens responds to

the thermodynamic activity of free sodium ion in the volume of solvent, not the total volume of solution.

Protein-bound electrolyte is not sensed by an ISE. Furthermore, the ISE method is subject to biases due to

residual liquid junction potentials and protein effects at the electrode. Thus, calibration of the ISE method

according to a strict protocol and with well-designed reference materials is critically necessary to bring

conformity and consistency to ISE measurements. An accurate calibration solution should simulate the

actual sample, to minimize the effects of liquid junction, activity, protein volume and other factors which affect

the electrode potential.

The objective of our present study, funded by the instrument manufacturers through the National

Committee for Clinical Laboratory Standards, is to develop suitable reference materials and to certify them

for the concentrations of Na^ and K^. As part of this study, a four-stage interiaboratory test has been

carried out. Eight instrument manufacturers and three independent hospital laboratories participated in these tests. The primary purpose of the initial interiaboratory test was to check the test protocol. The

second interiaboratory test was designed to find a suitable material which could minimize the deviation

between laboratories. The purpose of the third interiaboratory test was to test the linearity of the ISE

measurements and the performance of the material selected in the second round robin. The fourth test was

intended to test a prototype reference material, and is still in progress.

19
As. If standards can be prepared to closely match sample matrix, such as a standard reference material

(SRM), calibration of the ETAAS instrument is not a major problem. But SRMs matrices are limited and the

analyst has resorted to the standard addition method. Standard addition has long been considered as an

effective way to combat the multiplicative interferences in aqueous samples. The application of standard

addition is based on the assumption that the analyte added is in the same chemical form as in the unknown

sample. Usually this is not the case in solid samples.

The data for sera which had been lyophilized and then reconstituted have indicated that these materials do

not perform well as calibrants for ISE measurements. However, the development of Standard Reference

Materials made of frozen human sera should be feasible. Such materials should help individual laboratories

make more precise ISE measurements for both Na"*" and K"^.

3. Establishment of Absolute Values for the Specific Conductance of Aqueous Solutions of

Potassium Chloride for Improved Measurement Accuracy

Y.C. Wu, K.W. Pratt and W.F. Koch

Electrolyte conductance is an important property of electrolyte solutions. The specific conductance k,

Siemens per centimeter, S cm‘\ is determined by the ratio G/R, where the cell constant G is the ratio of the

effective length I to the electrode area a (i.e.. I/a), and R is the resistance of the solution contained in the cell. Generally, R can be determined to the desired degree of accuracy. If G is known, k can then be determined.

On the other hand, one can use a material of known k, such as mercury, to determine the cell constant G,

from which the k of other solutions can be measured. The latter is the basis for the determination of the

conductivity standard for KCI solutions that have been used for the past 50 years.

After reviewing these standards, with the necessary corrections for the changes in the values of the basic

units, viz., the ohm; the temperature scale; and the volume unit, the corrected values differ numerically from

the originals. Moreover, the concentration unit for the old standards is the demal, which is defined as the

number of grams of KCI per kilogram of solution and is defined only for specific values, i.e., 71.1 352: ID; and

0.745263: 0.01 D. It is therefore desirable to redetermine the specific conductance of a primary standard with

greater precision and accuracy using modern technology, to eliminate its dependence on the resistivity of

mercury, and to replace the demal unit with molality.

To this end, we have designed an all glass conductance cell with a well defined geometry. The cell constant

can be determined accurately to 0.02% based solely on geometric measurements. The cell is assembled

from a single pair of electrode housings, fitted with interconnecting flanges, and a set of removeable

intermediate tubes of accurately known cross-section and length. The distance between the electrodes can

be adjusted by inserting individual tubes of this set.

The theory behind this approach is as follows. The specific conductance for a known concentration of

electrolyte Is a constant. The total effective cross-sectional area is a fixed value for a given cell and is composed of two parts in the NIST cell: Ao, the portion of the cell between the electrodes and the

connecting flanges; and Aj, the diameter of the replaceable center tube. Ai must be accurately known and

it is expedient if it is constant for all the center tubes. The distance I has two components: lo, the portion

of the fixed but unknown length between the electrodes and the connecting flanges; and li, the accurately

known length of the i’th center tube. The resistance Ri is the measured quantity, and can be separated into

two components: ro, due to lo and Ao; and n, due to the i’th center tube. Thus,

Ri = (1/k) (ro ri) = (1/k) (ro h/Ai)

20
and

R2 = (1/k) (ro + X2) = (1/k) (ro + I 2/A2) By performing the experiment with two center tubes of different lengths (but with Ai = A2 = A) and solving

the simultaneous equations, k can be determined:

K = (li-l2)/(Ri-R2)A

Experimental results show that the values for 0.1 D and 0.01 D KCI at 25 °C agree with the Organisation

Internationale de Metrologie Legale recommended values (which are based on k for mercury) to within 0.02%

which is the uncertainty for both sets of data.

4. Advancement of Robotics in Analytical Chemistry and Applications to Chemical Separations for

SRM Certification

H. M. Kingston and F.C. Ruegg

Chemical measurement technology is undergoing extraordinary transformation and expansion from

labor-intensive, single-parameter chemical measurements to automated, multi-parameter measurements.

Applications include materials processing, food processing, waste management, and diagnostic

technologies, affecting about two-thirds of the GNP. Rapid growth in applications has made chemical

measurement technology the largest measurement technology used in the industrial and governmental

sectors, accounting for more than half of the economic value of all measurements made each day with total

annual expenditures estimated at $50 billion.

At the forefront of research in the areas of process and quality control techniques for chemical

characterization is research in laboratory robotics and automation. Simple robotic systems already are being incorporated into industrial laboratories for high volume analyses. Development of expert systems

control will greatly expand the capability of laboratory automation.

Analytical chemists and instrument manufacturers agree that sample preparation is a major impediment to

fast, accurate Instrumental analysis. As a sample preparation technique, separations procedures can be one

of the most labor intensive. This system uses open-column ion exchange and chelation chromatography to

isolate single elements or groups of elements at minor to trace (1 % to 1 0 ng/g) concentration levels from the

other components of a sample. These separations are necessary prior to quantitative determinations of the

elements by instrumental techniques. The analyst enters parameters into a program that resides in a master

computer which then converts these instructions into a robot control program for the desired separation.

The robot is responsible for manipulation of samples and reagents through a series of preprogrammed

operations activated by the master computer.

Entry of a new separation procedure into the master computer requires approximately 15 minutes while

modifications of existing procedures require less than 5 minutes. Neither requires reprogramming of the

robot.

This system applies new methods in the field of laboratory robotics. A major development is an interface

control program that is "chemist friendly"; the chemist must only know the chemistry of the separation and

not how to program robots. The system provides a hierarchical method for computer control of robotics

and provides a functioning instrument capable of versatile chemical separations.

21
The robot and separation apparatus are located inside a small class 100 clean air chamber. This chamber

provides the environment required for handling trace element samples to prevent contamination. Verification

of each robot operation is accomplished by sensors, several of which were specifically designed for this

system. A record of the operations performed on each sample during the separation is stored by the master

computer and thus becomes a quality control document that is useful in quality assurance.

This system has been used to certify 4 elements in the new River Sediment, SRM 2704. Laser Enhanced

Ionization was used to certify Mn, Nl and Pb while Graphite Furnace Atomic Absorption was used to certify

Cd. Standard separations were also done by a separations chemist and compared with the robotically

produced sample. No significant difference between the measurements was observed. This automated

system is now being used to separate samples for certification in support of several instrumental analytical

techniques. The concepts developed for this application are now being incorporated into a second system

being developed for the EPA. The new system will be used to demonstrate the feasibility of applying new

robot control technology to the decomposition of environmental samples using microwave preparation

technology.

5. A Prototype Expert System for Developing Microwave Dissolution Procedures

F.A, Settle, Jr. and H.M. Kingston

Closed vessel microwave dissolution has proven to be an effective procedure for preparing a variety of sample

types for analysis by several techniques. To function properly, a microwave procedure requires values for

the sample mass, the identity and volume of the reagent(s) used for the dissolution as well as the temperature

and time required for the digestion. These values depend upon four analytical descriptors that characterize

the analysis: (1) the type of matrix represented by the sample, (2) the analyte(s), (3) the expected

concentration level of the analyte(s), and (4) the technique to be used for the measurement.

A prototype expert system has been developed to assist the analyst in establishing procedures for microwave

dissolution. The system first guides the analyst In selecting analytical descriptors for the sample and then

uses these descriptors to recommend conditions for digestion of the sample. Once a procedure has proven

successful, it can be stored for future reference. Thus, the system has the ability to "learn" new procedures.

The knowledge base of the expert system contains rules for : (1 ) matching the matrix of the sample with that

of an SRM and (2) Inducing the conditions for digesting the sample. A separate database component of the

system contains detailed information on the elemental composition of the SRMs. This database was

developed by the Inorganic Analytical Division to monitor the progress of SRM analyses.

The initial component of the system identifies the SRM most closely resembling the sample to be digested.

If the analyst knows the name or number of the SRM corresponding to the sample, either can be entered

directly. If, however, the analyst is uncertain as to the choice of SRMs, he can characterize the sample by

responding to a series of multiple choice questions that allow the system to match the sample with an

SRM.

Once the appropriate SRM has been determined, the analyst can review information in the database and

select the set of analytical descriptors for the current analysis. The expert system now queries the analyst

for the following additional Information on the digestion: (1) the estimated moisture content of the sample;

(2) the sample vessel (e.g., 120 mL Teflon PFA); (3) the number of samples per digestion; (4) the maximum

power (watts) delivered to the sample cavity by the microwave unit. With this information and the analytical

descriptors, the system recommends specific conditions for the dissolution.

22
While the prototype furnishes the conditions directly to the analyst, future versions will permit the system to

interact with laboratory equipment Including robots and programmable microwave units, to produce

automated procedures. Work Is also In progress to develop a system capable of storing successful

microwave procedures developed in a number of laboratories and retrieving them for use in one of several

laboratory environments: (1) totally manual; (2) manual sample preparation and automatic microwave

dissolution; and (3) totally automated.

6. Development of Rapid Dissolution Procedures for the Determination of Volatile Elements such

as As. Se. S. and Hq

M.S. Epstein

Dissolution procedures designed to prepare samples for the analysis of elements such as As, Se, S, and Hg

by atomic spectrometric techniques are often time-consuming, since special measures must be employed

to eliminate volatilization losses. The recent development of microwave digestion methods has made rapid

sample preparation (1 hr) a reality, and the closed-system nature of this technique makes possible the

determination of volatile elements using digestion parameters similar to those used for nonvolatile elements.

We are presently investigating the application of microwave digestion as a sample preparation method for

the determination of volatile and nonvolatile elements in sediment samples by ICP-MS, ICP-ES, and GFAAS.

Results for SRM 2704 (Buffalo River Sediment) show significant promise.

Samples (0.5 g) are weighed into Teflon PFA vessels along with 9 g of HNO3 and 4 g of HF. The vessels are sealed and exposed to 579 W of microwave energy for 1 5 minutes. Pressure and temperature are monitored

throughout the digestion, with maximum values of 180 °C and 100 p.s.i., respectively. After completion of

the digestion, the samples are cooled and transferred to plastic storage containers.

7. A Direct Solid Sample Introduction Method for the Determination of Trace Elements in Glass

Using Zeeman AAS

Li-jian Yu and T. C. Rains

Solid sampling techniques for atomic absorption spectrometrywith electrothermal atomization (ETAAS) have

been considered for years to be an attractive approach for trace elemental determinations. The technique

offers advantages such as a minimum of sample pretreatment which minimizes the chance of contamination

or loss of analyte, speed of analyses, and low detection limits. However, the technique is not as precise and

calibration is a major problem. With the advent of the L’vov platform, and Zeeman background correction,

it is now possible to calibrate ETAAS for some types of materials using aqueous standard solutions. However,

the technique is reported to suffer poor precision and many Interferences. One possible explanation of the

poor precision and accuracy is that the residence time of the analyte is changed by the additional convection

gas flow induced by the expending matrix gases. If standards can be prepared to closely match sample

matrix, such as a standard reference material (SRM), calibration of the ETAAS instrument is not a major

problem. But SRMs matrices are limited and the analyst has resorted to the standard addition method.

Standard addition has long been considered as an effective way to combat the multiplicative interferences

In aqueous samples. The application of standard addition is based on the assumption that the analyte added

is in the same chemical form as in the unknown sample. Usually this is not the case In solid samples.

In this work a new concept called in-situ digestion has been introduced. After the solid sample is Introduced

into the furnace a matrix modifier is added to dissolve the sample. As the sample is digested inside the

absorption cell, the basis of the calibration for the solid sample can be set on the well-established solution

ETAAS calibration technique. As a result, standard addition becomes effective for calibration of the solid

23
sample. In our experiments with SRM 61 4 Trace Elements in Glass, we found that the analyte signal displayed

a Gaussian distribution on the absorbance vs. T scale. In addition the background is greatly reduced, tube

life is prolonged, and the precision and accuracy of the determination is improved.

The procedure involves weighing 0.2 to 1.5 mg of the solid material on a microbalance and then transfer it with the aid of a pipette tip, into the furnace on the Lvov platform. The matrix modifier which consists of a

mixture of H2SO4 and HF is added. The temperature is raised and the glass matrix is volatized. Finally the

analyte is atomized and absorption measured. The procedure is repeated except that after the volatization

of the matrix, the tube is cooled and analyte spike added. Then the temperature is raised, the sample is charred and atomized, and the absorption is measured. The concentration is then calculated by the standard

addition method.

At the beginning of our solid sampling experiment, SRM 61 4 was introduced directly onto the platform without

any modifier. The analyte signal was erratic and after 100 determinations a round hole was found on the

platform at the site where the solids were deposited. The graphite tube remained in good condition. This

suggested that the matrix in the solid sample was attacking the graphite. A possible explanation is that the

graphite platform is oxidized bythesilicateforming silicon carbide. When the experiment was repeated using

a matrix modifier, the effect was not observed.

Standardization using an aqueous standard calibration curve was also investigated. It was found that the

analyte concentrations were consistently higher then the certified values for SRM 614. This would indicate

that multiplicative interferences were being encountered and proper matrix matching should be used. Since

Ca is present at a relatively high concentration in SRM 614, Ca was added to all standards to match the

analyte matrix. As a result the analyte values for Co, Cu, Fe, and Ni were in good agreement with the standard

addition methods and with the certified values. The overall precision of the method for Co, Cu, Fe, and Ni

in the 0.5 to 1 .5 mg range in SRM 61 4 was 1 0 to 1 2 percent.

Solid sampling is an attractive technique for its simplicity and straightfonA^ardness. With in-situ digestion,

matrix modification, and aqueous standardization, the technique is being investigated as a unique method

for the determination of trace elements at the submicrogram level in highly refractory materials.

8. The Development of Modern Approaches to Classical Analytical Chemistry

T.W. Vetter, J.M. Smeller, and M.S. Epstein

Classical wet chemistry (titrimetry and gravimetry) is augmented by instrumentation-based trace analysis

methods to decrease the analysis time required for classical analysis yet retain and often improve its high

accuracy and precision. Direct-current plasma emission spectrometry (DCPES), inductively-coupled plasma

emission spectrometry (ICPES) and flame atomic emission (FAES) or absorption spectrometry (FAAS) are used to characterize reagent blanks, to insure precipitate purity, and to monitor procedures (i.e., separations,

extractions) for loss of analyte. Since the instrumental methods are used to determine only a small

percentage of the analyte, their poorer precision and increased bias do not significantly degrade analytical

results. Silica, sodium, calcium, iron, copper and nickel have been determined using this modern approach

to classical analytical chemistry as described in the following examples.

(a) The classical gravimetric determination of silica in clays and sediment involves a double

dehydration with HCI followed by filtration of a silica precipitate that is ignited and weighed.

When the silica precipitate is filtered, a small amount of silica dissolves and is washed into the

filtrate. The filtrate (containing 1% or less of the total silica) is usually recovered by precipitation

with ammonia followed by additional tedious steps. Instead, silicon dissolved in the filtrate after

24
the second filtration is determined by DOPES. In the analysis of 0.5 g of Buffalo River Sediment,

SRM 2704 (Si02 = 62.22 ± 0.28 wt%), the silica dissolved in the filtrate ranged from 0.3 to 0.7

mg representing 0.1 -0.2% of the total silica in the sample. Addition of this relatively small silica

fraction to the total silica gives a more accurate and precise value.

(b) The classical determination of sodium involves several separations with a final weighing as sodium sulfate. For the determination in a river sediment matrix, a combination of HCIO4, HNO3

and HF is used for dissolution. Iron, aluminum and co-precipitating elements are separated

out by a double precipitation with ammonium hydroxide. Nearly all the sodium plus some other

elements remain in solution. The small quantity of sodium trapped in the ammonia group

precipitate is determined by FAES after dissolving the precipitate. The sodium remaining in

solution after the ammonia group precipitation is separated from the remaining elements by

elution on a cation exchange column (AG 50W-X8, 100-200 mesh) with 0.4 M HCI. The eluent

collected prior to and after the elution of sodium is checked for trace amounts of sodium by

FAES. After the eluted sodium solution is evaporated and H2SO4 is added, the solution is again

evaporated to convert NaCI to Na2S04. The Na2S04 precipitate is ignited at 900 °C to constant

weight. Possible contaminants in the Na2S04 precipitate are determined by ICPES after fusing

the precipitate with lithium metaborate and dissolving the melt in dilute HNO3. Significant

amounts of residual sodium have been found in the ammonia precipitate, but no significant

contaminants have been detected in the Na2S04 precipitate.

(c) Calcium is determined using an EDTA complexometric titration and a photometric endpoint.

Calcium concentrations are determined in reagent sample blanks by DCPES.

(d) Iron is determined by titration with potassium dichromate. Ion-exchange or solvent extraction

procedures used to separate matrix components are evaluated for recovery of separated iron

by FAAS or DCPES. Contamination in reagents and sample blanks are also monitored.

(e) Copper in monel is determined by electrolysis of a sulfuric acid solution of the metal. Copper

in solution is plated out onto a clean, pre-weighed platinum electrode. After plating is judged

complete, the platinum electrode is reweighed to determine electroplated copper. Copper

remaining behind in the solution, usually 0.1 to 0.2 percent of the total electroplated copper, is determined by ICPES. The copper plated on the electrode is dissolved with HNO3 and

contaminants are determined by ICPES.

(f) The gravimetric determination of nickel as nickel dimethylglyoxime is a widely accepted

classical method. ICPES analysis of nickel in fractions separated from the nickel

dimethylglyoxime and of contaminants in the nickel dimethylglyoxime precipitate is used to

confirm results. In monel, copper must be separated from nickel prior to precipitation of the

dimethylglyoxime. Copper is separated from nickel by electrolysis. The electroplated copper

is analyzed for traces of nickel by ICPES. Nickel is separated from solution as a nickel

dimethylglyoxime precipitate by the addition of dimethylglyoxime dissolved in ethanol. The

nickel precipitate is collected on a clean, pre-weighed, fritted glass crucible. The crucible is dried and weighed to determine the weight of nickel as nickel dimethylglyoxime. The nickel

precipitate is dissolved in HNO3 and analyzed by ICP to determine possible contaminants. The

solution separated by filtration from the nickel dimethylglyoxime is analyzed by ICPES to

determine nickel.

25
9. The Determination of Tributyltin in Sediment Using Liquid Chromatography with

Laser-Enhanced Ionization as a Tin-Selective Detector

G.C. Turk, K.S. Epier, and W.A. MacCrehan

A method has been developed for the determination of the antifouling agent tributyltin (TBT) in estuarine

sediment based on liquid chromatographic separation of TBT from other tin compounds coupled with

laser-enhanced ionization (LEI) as an atomic spectroscopic tin-selective detector. The cation exchange

separation procedure provides a considerable advantage over other separation procedures developed for

TBT in that it does not require chemical derivatization of the TBT cation. Other existing separation methods

for TBT require the formation of TBT hydride or alkylation of TBT via the Grignard reaction. Concerns about

the accuracy of methods requiring these derivatization reactions for the determination of TBT in sediments

have been raised. The cation exchange method avoids this problem, but is a relatively low-efficiency

separation, with plate counts of only 2800/m. Consequently, considerable chromatographic dispersion is encountered and a 100-fold dilution of the injected sample Into the chromatographic mobile phase occurs. The high sensitivity of LEI allows detection of trace quantities of TBT despite this dilution factor. The limit of

detection using the LC/LEI instrument is 3 ng/mL for tin as TBT using a 20-jxL injection for an absolute

detection limit of 60 pg.

For the determination of TBT in sediments, a n-butanol extraction procedure has been developed. An

extraction efficiency of 97% with a relative standard deviation of 8% was achieved using this simple procedure,

which can be performed in less than 30 minutes. A wavelength modulation technique was devised which

can perform real-time spectral background correction. The relative complexity of the laser instrumentation

required for LC/LEI is certainly a drawback, but the avoidance of chemical derivatization has a significant

accuracy benefit, and the rapid extraction procedure is suitable for large scale survey studies.

10. The Determination of Ba-Y-Cu Oxide Stoichiometry in Superconducting Materials Using ICP

Optical Emission Spectrometry

Laura J. Wood and Robert L. Watters, Jr.

Inductively coupled plasma (ICP) spectrometry was used to determine the stoichiometry of superconductor

material. The chemical formula was known to be approximately YiBa2Cu307, and an ICP sequential

spectrometer was used to scan the spectral analysis lines for Y, Ba, and Cu. Since oxygen is difficult to

determine directly, the overall stoichiometry can be obtained by determining the other elements by chemical

analysis and calculating the oxygen difference. However, the cumulative effect of errors in the individual

determinations of Y, Ba, and Cu will result in a magnified uncertainty in the result for oxygen. Therefore, it

is essential that random and systematic errors be minimized in the determinations of Y, Ba, and Cu. We used

ICP spectrometry with simultaneous internal standardization to determine these elements with high precision.

The typical relative error for ICP analysis at concentrations well above the detection limits is about 2%. This

error is due to photomultiplier shot noise, plasma flicker noise and sample introduction flicker noise. In addition, long-term drift may cause errors of a few percent relative over hour-long periods if the instrument

is not re-calibrated. When the chemical matrix of the sample Is not complex and the spectral lines of interest

exhibit signal-to-noise ratios of over ten, significant portions of the overall noise and drift characteristics are

correlated from element to element. Under these circumstances a simultaneous measurement of the signal

from a constant concentration of an internal standard element can be used to correct for correlated noise

and drift.

Sequential ICP spectrometer systems measure spectral intensities of different elements at different times.

Therefore, the measurement of an internal standard element spectral line intensity simultaneous with that of

26
an analyte line is not always possible. The particular ICP spectrometer system used for these measurements

has a separate filter photometer channel that continually monitors the 424.683-nm spectral line of scandium.

This element is a suitable internal standard for many ICP applications. As each analyte spectral line is sequentially scanned, the scandium signal is also measured simultaneously. The background signal Is subtracted from both the measured Sc intensity and the measured analyte intensity. The net analyte and Sc

intensities are then divided for a final concentration value.

The superconductor material was supplied in powdered form. Several different samples were dissolved with

an acid digestion procedure using 50% (VA/) HCI. The resulting solutions were then diluted to reduce the

elemental concentrations to within the linear response range for ICP spectrometry. Scandium was added

to each calibration standard and sample solution so that its final concentration was 50 ng/mL. Standard

calibration curves for each element were established using a mixture of single-element stock standard

solutions made from pure materials. Replicate integrations of each element scanned were used for each

solution analyzed. When using internal standardization, the relative standard deviations of the replicate

integrations are less than 0.4%. Without internal standardization, the relative standard deviations are approximately 2.0%. Yttrium, barium, and copper were determined in each sample analyzed. The Y and

Cu values agreed with those reported by the Nuclear Methods Group for the same material, and the precision

was approximately four times better than the nuclear technique.

The final calculation of the oxygen content also depends on an accurate assessment of the presence of trace

impurities. The ICP system was also used to scan the spectral lines of 36 elements for a prototype sample

of superconducting material. The following elements were detected: Al, B, Ca, Fe, Mg, and Si.

The Ba values were consistently low and varied by more than the expected uncertainty for analyses using

internal standardization. This source of error is due to incomplete dissolution of Ba. Undissolved particles

in the sample solutions were separated and analyzed by DC arc emission spectrometry. Ba was found in

this residue, which was probably in an insoluble form resulting from the physical treatment associated with

the superconducting material preparation. This point will be investigated further by analyzing a variety of

superconducting materials resulting from different treatment procedures, and by employing high-pressure

dissolution methods. Presently, the ICP method can be used to determine Y and Cu with accuracies and

precisions of about 0.5% relative. The method requires about 2 hours to complete, which is rapid enough

to be useful in evaluating prototype superconducting materials and processes.

11. The Technical Planning and Execution of a Certification Program for the Buffalo River Sediment

SBM

M.S. Epstein

The program for the certification of SRM 2704, Buffalo River Sediment, was concluded in FY88. The program

involved close cooperation between the technical coordinator designated by the Office of Standard

Reference Materials and the technical champion designated by the Inorganic Analytical Research Division

in the planning and execution of the SRM project. The implementation of well-defined quality control

procedures for collection, processing, and analysis of the sediment, as well as improvements in analytical

methodologies, have resulted in a reference material that is more completely characterized than previous

NBS sediment reference materials. The sediment will be certified for at least 25 elements, with information

values provided on more than 20 other elements.

27
Highlights of the certification program are as follows:

(a) Planning (April 1985) - Preliminary samples of sediment were evaluated for inorganic and

organic constituent concentrations, homogeneity, and yield after freeze-drying and sieving.

Material handling and preparation procedures were designed to be similar to those to be used

for the bulk sample in order to identify potential difficulties. Homogeneity was assessed for 4

elements (C, Ca, Fe, Si), and semi-quantitative information obtained on 13 others. PAHs, PCBs,

and pesticides were also identified in the preliminary samples. Sediment collected from the

vicinity of the Ohio Street Bridge over the Buffalo River was chosen for the SRM.

(b) Collection (November 86) - The sediment was collected with the cooperation of the U.S. Army

Corps of Engineers using a clamshell bucket suspended from the crane of a derrick boat. The

sampling protocol was a compromise between the methods used in the collection of previous

sediment reference materials (SRM 1645 and SRM 1646) in that small-scale sampling from a

large collected sample was employed. A Teflon-coated shovel was used to transfer sediment

from the clamshell bucket to Teflon-coated bags nested inside polyethylene-lined, 55-gallon

steel drums.

(c) Processing and Preliminary Evaluation (FY87). The sediment was refrigerated and transported

to a facility where it was mixed, freeze-dried, screened to pass a 100-mesh sieve, remixed, and

placed into polyethylene-lined aluminum cans. The gross homogeneity was evaluated using 4

elements (Cr,Fe,Na,Si) and analysis of variance (ANCVA) to separate can-to-can,

sample-to-sample, and instrument variance. Inhomogeneity was observed for Cr and Fe, and

the sample was reblended in a cone blender. Subsequent evaluation of the reblended material

indicated satisfactory homogeneity for these elements.

(d) Humidity/Drying Study (FY87). The behavior of SRM 2704 under varying environmental

conditions was evaluated using a chamber equipped to do accelerated humidity and drying

studies. The composition of SRM 2704 was found to be reproducible at a given %relative

humidity and a sample dried to a reproducible composition when the recommended drying

procedure (2 hours at 1 10 °C) was used. The nominal weight loss was 0.8%.

(e) Evaluation of Sediment Homogeneity (FY87-FY88). The homogeneity of bottled units of SRM

2704 was assessed using x-ray fluorescence (XRF) spectrometry for 12 elements (Al, Ca, Fe,

K, Mn, P, Rb, Si, Sr, Ti, Zn, Zr) and graphite furnace atomic absorption spectrometry with slurry

sampling for 4 elements (As, Fe, Mn, Pb). Homogeneity information for other elements was

also obtained from certification analysis results by applying ANOVA to information provided by

each analytical method.

(f) Analytical Measurements (FY87-FY88). The certification analyses were performed by 5 different

laboratories using 19 different analytical methods. Each laboratory was provided with a set of

instructions which detailed the number of samples to be analyzed, the drying procedure, the

dissolution procedure, the control samples, and information which should be included with the

reports of analysis. Analytical methods for a specific element were chosen to maintain

maximum "independence" and both dissolution procedures and analysis methodology were

included in the decision-making process.

(g) Statistical Evaluation of Data (FY88). The certified values were calculated as the weighted mean

of results from two or more independent analytical techniques. The uncertainty in each certified

28
value was calculated as the sum, in quadrature, of estimates for material inhomogeneity, and

random and systematic errors among the methods used for certification.

As a result of the NIST certification program for SRM 2704, not only was the sediment characterized for more

elements than previous NIST sediment SRMs, but also the confidence limits for certified values were

decreased by almost two fold.

12. Measurement of Chromium in Human Blood and Blood Fractions at Natural (sub-ppb) Levels

R.R. Greenberg and R.L Zeisler

Chromium was recognized as one of the elements essential for humans more than twenty-five years ago.

However, at elevated concentrations, some forms of Cr are toxic and possibly even carcinogenic. In recent

years, several analytical techniques have demonstrated the capability to accurately determine chromium at

the naturally-occurring, ultratrace-levels normally found in uncontaminated samples of human serum. A

variety of problems, however, have limited the determination of Cr to this single fraction of human blood. In view of the importance of this element, more detailed investigations of its occurrence and role at natural

levels are needed, requiring even more sensitive analytical methods.

A reliable radiochemical procedure for Cr has been developed based upon neutron activation followed by a

radiochemical separation. The separation procedure involves the liquid/liquid extraction of Cr(VI) into a 5%

solution of tribenzylamine/chloroform, back-extraction into an aqueous solution (2 mol/L) of sodium

hydroxide and precipitation as barium chromate. Radiochemical neutron activation analysis (RNAA) is one

of the best analytical techniques currently available for trace and ultratrace level determination of Cr in

biological materials. It possesses the sensitivity required to determine sub-nanogram amounts of Cr, and

the nearly blank-free nature of the technique allows chemical dissolution and separation of Cr from the sample

matrix (after irradiation) without regard to reagent blank. In addition, NAA is free from chemical interferences,

and most types of matrix effects which can interfere with other, non-nuclear, analytical techniques. However,

the nuclear interference from the fast neutron reaction Fe-54 (n, alpha)Cr-51, can be significant. This

interference can be minimized, however, by using a highly thermalized facility such as the RT-4 facility of the

NIST Research Reactor. In this facility, the measured Fe interference is 0.087 ^ig of Cr per gram of Fe, or approximately two orders of magnitude lower than that experienced in a typical light water reactor. The RT-4

interference is equivalent to a Cr blank of 0.039 ng of Cr per gram of whole blood for men, and 0.035 ng/g

for women.

Chromium concentrations have been determined in whole-blood samples from nine individuals. The Cr

concentrations for eight of these people were between 0.04 and 0.3 ng/g on a fresh weight basis. The ninth

individual had a considerably higher level of Cr, and this is discussed below. Serum samples have been

analyzed for seven of these individuals, and packed cells for two. Duplicate samples from a single collection

have been run for the whole blood from one person and for the serum from a second. Both duplicate values

are consistent with the observed counting statistics. In addition, blood from these two individuals has been

sampled on two occasions more than one year apart. No differences in the Cr concentrations, greater than

the analytical uncertainties, can be seen for subject B2. A small, but real, increase in both the whole blood

and serum Cr levels from B1 was observed. It should be noted that between the 1986 and 1987 sample

collections, individual B1 was taking a daily dietary supplement containing 200 \ig of Cr in the form of an

amino-acid chelate, while no supplement was taken prior to the 1986 collection. This factor of five increase

in Cr intake, compared to the average American dietary intake of approximately 40 ^ig/day, resulted in a Cr

increase of approximately 50%, by weight, for whole blood in men. There appears to be no change in the

Cr concentration in the packed cells of this individual. The large increase in dietary Cr had only a relatively

small effect, elevating the serum level for B1 from the second lowest concentration observed in this study.

29
to the median value. Thus, at least for this individual, Cr levels in the blood may be under some type of

bioregulatory mechanism.

An interesting observation can be made concerning individual T2. This person had concentrations of Cr in both whole blood and serum which were elevated by factors of 5-20 compared to the other individuals studied.

Subsequent questioning revealed that this person has been diagnosed as a borderline diabetic, and has a

family history of diabetes (mother). In view of the possible link between Cr and glucose metabolism, further

studies of the Cr concentrations in whole blood and blood fractions from diabetics may be indicated.

However, in view of the difficulty in making accurate Cr determinations, at the naturally occurring levels in these materials, carefully validated analytical methods and rigorous quality assurance procedures should be

used for these studies.

13. Measurement of Long-Term Stability of Human Livers

R.L Zeisler, R.R. Greenberg, S.F. Stone, and T.M. Sullivan

At present, only limited data are available on the long-term storage of biological materials. For the storage

of biological tissues and fluids, rapid freeze drying immediately after sampling has been recommended.

However, this technique suffers from the disadvantage that some volatile components may be lost. In freeze-dried materials, trace element concentrations are stable over an extended time period even if stored

at room temperature, as has been shown in various NIST Standard Reference Materials. Another approach

is the immediate freezing of the sample or sub-sample to the lowest conveniently attainable temperature.

This approach serves two purposes: 1) it reduces or stops chemical and biological processes which could

result in sample changes, and 2) it reduces the mobility of constituents in the sample and/or container

material, thereby lessening the possibility of contamination and/or losses due to absorption/adsorption or

volatility. A subsampling, storage, and analysis program was designed to lead to a complete evaluation of

the storage processes with respect to the long term preservation of the originally present trace constituents over a several years storage time. To solve the question of the most appropriate temperature for sample

storage, aliquots of the specimens were stored under four different conditions: freeze dried at room

temperature, frozen at -25 °C, at -80 °C, and in liquid nitrogen vapor (LN2) at -120 °C to -150 °C. The

concentrations of trace constituents found after storage under those conditions were compared to the data

found in the analysis of each specimen. The statistical assessment of the probability for discovery of changes

included consideration of sample inhomogeneity, variations among aliquots, analytical error, and number of

specimens analyzed. A 98% probability existed to detect a 6% change in the concentrations if 30 livers

specimens were analyzed, and the errors due to Inhomogeneity and analysis would be limited to 5% each.

The human liver specimens were collected in the pilot National Environmental Specimen Bank (NESB). They

were cryogenically homogenized, aliquoted into Teflon jars and distributed to the different storage facilities

and the baseline analysis in 1980. For the initial investigation, aliquots from 24 specimens were removed

from the -25 °C and LN2 storage in 1987 and analyzed by neutron activation analysis. The results were

compared to the baseline data.

This study covered elements that form stable ionic and/or molecular species in tissues as well as elements

that form or are converted to volatile species in metabolic processes. No difference was observed between

those categories. No deviation could be determined that exceeded the calculated statistical boundaries,

although physical segregation into ice and lumps of material instead of powder was observed in the -25 °C

storage. Although storage at -25 °C is easier to achieve, the observed sample degradation points towards

sample storage at -80 °C or LN2 as the storage condition of choice. These results confirm that Specimen

Banking is a feasible tool in environmental monitoring. In addition, the established total element stability of

30
fresh frozen biological materials may very well be valid also for elemental species. Consequently, this type

of storage should be used as reference in speciation studies.

14. Quantitative Determination of Proteins Using Polyacrylamide Gel Electrophoresis and Neutron

Activation

S.F. Stone, R.L Zeisler, and G.E. Gordon

The accurate determination of trace element content and function in macromolecules requires an analytical

scheme that combines a highly sophisticated biochemical separation with a highly sensitive and accurate

analytical technique. Polyacrylamide gel electrophoresis (PAGE) is a rapidly developing and widely used

biochemical separation technique. It has excellent resolution for proteins and other charged

macromolecules. Much of the work done with PAGE has involved using radionuclides as "tracers" for the

detection of proteins following separation. This work utilized both in vivo labeling prior to electrophoresis

and in vitro labeling after separation, where an exchange of non-radioactive for radioactive trace elements

has taken place. These studies have used radiotracers as a qualitative detection technique in lieu of staining

methods, rather than for the quantitative determination of the trace elements associated with the proteins.

To overcome the necessity of radioactive labeling, we have investigated the possibility of identification and

analysis of these separated proteins with neutron activation analysis (NAA).

A method has been developed that combines the powerful separation capacity of PAGE with the sensitivity

of NAA. This method involves the neutron irradiation of the whole gel containing the separated proteins, and

detection and quantitation of the produced radionuclides by autoradiography and gamma spectrometry.

The principle of PAGE/NAA applied to some macromolecules has already been shown in previous work; i.e., the qualitative detection of phosvitin and carbonic anhydrase. Similarly, phosphorous in adenosine

triphosphate (ATP) separated by thin layer chromatography has been quantified following irradiation. In our

work, phosphoproteins were selected as a model to study this method. Quantitative measurements of

phosphorus in phosphoproteins separated by both sodium dodecyl sulfate (SDS)-PAGE and non-denaturing

PAGE have been accomplished. Linear concentration relationships are being demonstrated with

absorbance measurements of developed autoradiographs using laser densitometry. The method is also

being applied to determine the concentration of caseins in a "natural matrix" sample. Standard Reference

Material (SRM) 1549, milk powder.

This protein quantitation method has been shown to be feasible for phosphoproteins. The method provides

an important research tool for protein investigations, such as in human samples, where labeling is difficult,

and, in most cases, simply cannot be done. PAGE/NAA will also be useful in speciation studies, where the

excellent resolution of PAGE coupled with the sensitivity of NAA will be well suited. The work is currently

expanding to include other proteins, e.g., selenoproteins, and appears to be applicable to protein samples

within normal concentration ranges.

15. Determination of As, Cd. Cr and Mo in the NIST Bovine Serum Standard Reference Material at

the PPB Level

R.R. Greenberg, R.L. Zeisler, and T.M. Sullivan

As bioanalytical methods for trace element determinations have become more sensitive, biological and

medical trace element research has included studies of many of the "difficult" elements such as Al, As, Cd,

Cr, Mo, Mn, Sb and V. These elements are currently of interest, for example. In human blood-serum where

they typically occur at the low ng/g level or below. The accurate determination of trace elements at these

levels usually requires certified reference materials for method evaluation, and for quality assurance

31
purposes. This need for low-level reference materials for accurate analyses of human-blood serum and

related materials has been well-documented. To help meet this need the National Institute of Standards and

Technology and the Department of Agriculture have cooperated in the production and certification of a frozen

Bovine Serum Standard Reference Material (SRM) with uncontaminated, or nearly uncontaminated, levels

of a wide variety of trace elements.

The certification of trace elements in this Bovine Serum (SRM 1958) was particularly difficult due to the very

low levels of many of the elements of interest. A variety of analytical techniques has been used at NIST for

the Bovine Serum certification. For several of these techniques, it has been necessary to extend their

applicability beyond previously demonstrated measurement competence. One of these analytical

techniques, neutron activation analysis (NAA), was used to determine the concentrations of most of the

elements desired for certification. In addition to the instrumental measurements, a number of difficult,

low-level elements have been determined with appropriate pre- or post-irradiation chemical separations.

Two radiochemical separations have been used to reduce interferences from matrix activities such as from

Na, Br and P, or in some cases to totally isolate the element of Interest from essentially all other radionuclides.

Post-irradiation separations are particularly useful for low-level determinations since no reagent blank has

to be considered. Arsenic, along with Mo, has been determined using the inorganic ion exchanger HMD,

and Cd along with Cu, have been determined in the eluent from the same samples using sequential extractions

into solutions of bismuth and zinc diethyidithiocarbamate in chloroform. This previously-developed

procedure was modified to include a predigestion setup using a microwave oven. Dissolution was then

completed with nitric and perchloric acids in a conventional manner (on a hot plate). The predigestion step

allowed complete sample decomposition in two to three hours instead of the two days previously required

to insure complete destruction of the organic sample matrix. This reduction in sample decay time improved

the signal (number of counts) for As and Cd by factors of four and two respectively, and resulted in a

comparable improvement in the detection limits. Arsenic and Cd were observed in the Bovine Serum at 0.15

and 0.093 ng/g respectively, while Mo was present at 1 1 ng/g.

Chromium has also been determined in the Bovine Serum SRM following a post-irradiation extraction of

Cr(VI) into a solution of tribenzylamine in chloroform. This newly developed procedure has been applied to

human blood and blood fractions, and is described elsewhere in this report. The Cr concentration in the

Bovine Serum was 0.18 ng/g.

In addition to the elements determined after a radiochemical separation, three other biologically-important

elements, Al, Mn and V, which are present at ng/g and sub-ng/g levels, have been determined previously In this material utilizing NAA combined with a pre-irradiation, chemical separation. These NAA results, when

combined with the results from other analytical techniques, will allow the certification of many of these difficult

elements In a natural matrix material. The new Bovine Serum SRM should be of great value for method

development, and for quality assurance purposes when researchers analyze blood-serum or related

materials.

32
16. Standard Reference Materials

W. F. Koch

This year marks a milestone for the Division’s Implementation of the "Technical Champion", with the

completion of the first two major Standard Reference Materials (SRM) under this program. The Technical

Champion (TC) is selected from the senior research staff to interact with the designated Project Managers

in the Office of Standard Reference Materials (OSRM) for a specific SRM or class of SRMs. The TC is responsible for all technical aspects of an SRM from the selection and collection of a material, through the

experimental design for analysis, to the assignment of certified values. The TC coordinates his efforts with

Division management, OSRM, the analysts, and the statistician. The two SRMs formally issued under this

approach are SRM 2704, Buffalo River Sediment, and SRM 1598, Bovine Serum. Both are the finest quality

reference materials available for environmental and clinical applications, respectively, and stand as testimony

to the effectiveness of the TC approach. Several other projects utilizing TC’s are underway, most notably

replacement SRMs for Oyster Tissue and Citrus/Orchard Leaves, and a new Total Diet SRM.

As the demand for high quality reference materials increases, especially those certified for ultra-trace levels

of elements, the specifications for material suitability and homogeneity become more stringent. Considerable

emphasis is now placed on preliminary research on candidate materials to identify potential problem areas

that could be encountered during the actual certification process. This research includes careful material

selection and processing, sample dissolution studies, homogeneity determinations, and weighing form

(drying) studies. New methods of analysis are developed and existing methods are improved to keep ahead

of the demands. Whereas this deliberate approach guided by a TC must begin two or three years before the

actual certification process can begin, it is felt that in the long run it will provide better, more cost-effective,

and more timely reference materials.

Funding for the reference materials program within the Division comes from various sources. An estimated

50% of the Division’s base funding is directed toward reference materials. OSRM provides research and

materials development support, and analytical services funding for actual SRM certification. This last item

accounts for approximately 1 8% of the total budget of the Division. Of this amount, 80% is for renewal SRMs.

Other government agencies, as well as private sector institutions, are often the prime sources of funding for

the development of new reference materials.

Listed below are some of the areas of research specifically funded by OSRM during FY88. These projects

often involve cooperative work by the scientific staff from all four groups In the Division.

33
STRS Projects Supported by OSRM in FY88

TasK Description

Mercury in Soils Research to develop methods and procedures for determining mercury in soils and sediments using ICP. Work is in progress studying the application

of combustion/absorption method of mercury introduction into the ICP.

Marine Sediments Research to develop procedures for characterizing marine sediment in terms

of physico-chemical parameters and trace constituent profile. Selected

marine sediments have been collected and are being evaluated. This work

should lead to an SRM.

Classical Analysis Research to refine and adapt classical gravimetric and titrimetric procedures

for use in the certification of elements such as Ca, Mg, Al, Na, Si, Fe, Ti, and

K in select SRMs. Primary objective is to improve precision and accuracy of

the certified values of major constituents.

Transient Standards Research to develop methods and procedures for producing standards for

metal speciation. The approach is to perfect a method of sealing small

amounts of methyl mercury, ethyl mercury and mercuric chloride in glass

and of providing the means to achieve dilution to working concentrations in the ppb range by the user.

Mercury Speciation Research to develop procedures for the determination of mercury species in selected biological and environmental SRMs, using LC-ICP/MS. The LC is used to resolve the species; the ICP/MS provides high sensitivity for

quantitation at the ppb level.

High Ionic Strength pH Research leading to the certification of pH buffers in moderate to high ionic

strength. This year a new pH buffer SRM, intended for use in physiological

measurements, has been certified.

Phosphate/Nitrate Stability Research to establish the stability of phosphate and nitrate anion standard

solutions at the 1000 mg/L level. Results indicate that these solutions are

stable to within 1% for at least one year. SRMs will be considered for next

year.

This year analyses were carried out on more than 100 different SRMs covering a wide variety of matrices

including metals, fossil fuels, foods, glasses, and environmental materials. Also included in this number are over 50 spectrometric solution standards. In most cases, each certification involved several or all of the

Groups in the Division and required 20-30 individual analyses on each SRM. Examples of the SRMs worked

on during the past year are listed below.

34
Standard Reference Materials Analyzed During FY88

SRM Number

112b

136e

679

919a

930d

935

935a

955

1074b

1515

1547

1548

1566a

1598

1616-1617

1623b

1624b

1634b

1764

1766

1834

2034

2137

2165

2181

2182

2416-2418

2677a

2692

2694-1

2694-

11

2695-

High

2695-Low

2704

2712 through 2715

3101 through 3169

3171

3172

3181

3182

3183

3191

3192

3193

3194

3195

Silicon Carbide

Potassium Dichromate

Brick Clay

NaCI

Glass Filters

Potassium Dichromate

Potassium Dichromate

Lead in Blood

Calcium 2-ethyihexanoate

Apple Leaves

Peach Leaves

Total Diet

Oyster Tissue

Bovine Serum

Sulfur in Kerosine

Residual Fuel Oil

Distilltae Fuel Oil

Trace Elements in Fuel Oil

Low Alloy Steel

Low Alloy Steel

Simulated Fused Ore

Holmium Oxide Wavelength Standard

Boron Implant in Silicon

Low Alloy Steel

HEPES pH Buffer

HEPESate pH Buffer

Lead

Arsenic and Beryllium on Filters

Sulfur in Coal

Simulated Rainwater

Simulated Rainwater

Fluoride in Vegetation

Fluoride in Vegetation

Buffaio River Sediment

Reference Fuel

Spectrometric Solutions

Multi-Element Spectrometric Solution A

Multi-Element Spectrometric Solution B

Anion Solution SO4

Anion Solution Cl

Anion Solution F

Conductance Standard 100 ^iS

Conductance Standard 500 ^iS

Conductance Standard 1000 \iS

Conductance Standard 10000 ^iS

Conductance Standard 100000 \iS

35
Among the SRMs being considered for next year are replacements for SRM 909, Human Serum, SRM 1 043b

Trace Elements in Water, and new materials for carbonaceous marine sediment, electrolytes in human serum,

and trace elements in bone.

17. Analysis of U.S. Dietary Collections in Conjunction with the iAEA-NIST-FDA-USDA International

Nutrition Project

V. Iyengar

An international human nutrition project sponsored by the International Atomic Energy Agency (IAEA), and

supported by the U.S. National Institute of Standards and Technology (NIST), the U.S. Food and Drug

Administration (FDA), and the U.S. Department of Agriculture (USDA) is in progress. This study is designed

to assess the daily intake of certain dietary components by selected target populations in several countries.

The countries involved are Australia, Brazil, China, Iran, Italy, Spain, Sudan, Sweden, Thailand, Turkey and

the U.S.A. Mixed total diets from these countries are being analyzed for caloric energy, phytate and fiber

content, and minor and trace elements. Analyses for these constituents are being carried out in selected

reference laboratories identified by the IAEA. The NIST is one such reference center asked to determine a

select group of inorganic elements.

The U.S. is involved both as a collection center and as a reference laboratory. A part of the study was

concerned with evaluating analytical approaches. Mainly neutron activation analysis was used in both the

instrumental and radiochemical modes. Guidelines were developed for the preparation of mixed diet

reference standards for quality control, and one material (Mixed Diet SRM 1548) is currently being

characterized for certification. Simultaneously, collection of U.S. mixed diets based on the FDA Total Diet

Study scheme was initiated. Until now, six such collections have been completed from the following regions:

Southeast (GA, TX, WV), North Central (lA, KS, OH), Northeast (NY, PA, Rl), South (AL, LA, TX), West (AZ,

CA, OR), and Central (IL, IN, Wl). One portion of mixed diet, from each of the six collections has been stored

in the Specimen Bank. Studies are also in progress to assess long-term stability of organic nutrients in mixed

diets, under different storage conditions.

Five of these diets have already been analyzed for vitamins, fiber, phytate, and several minor and trace

elements. The results obtained for several elements show remarkable agreement with the daily intake data

calculated from the individual food analysis results of the FDA-TDS study, confirming the validity of the mixed

diet approach for monitoring the daily intake of minor and trace elements. The results did not indicate any

significant inter-regional variations in the overall daily intake. This is attributable to the fact that these U.S.

collections represent national diets due to standardized collection procedures of the TDS scheme. In the

present study, analytical results obtained for over 30 elements for the mixed diet samples

provide a basis for establishing baseline values for the daily intake of a number of elements that are not

covered by the FDA-TDS scheme.

36
18. Particle-Particle Coincidence Neutron Depth Profiling (NDP)

W.-K. Chu, N.R. Parikh, E.C. Frey, M.L Swanson, and Z.H. Zhang, University of North Carolina,

T.Z. Hossian, Eastman Kodak, and R.G. Downing and R.F. Fleming, National Bureau of

Standards

During the previous year, NDP was modified to use a particle-particle coincidence technique which has the

advantages of reducing the background, providing greater sensitivity, and increasing the depth of analysis.

NDP takes advantage of the fact that a few nuclides of significant technological importance decay upon the

absorption of a low-energy neutron by emitting a light charged particle, the recoil particle, and in some cases

a photon. The two recoiling fragments are emitted isotropically from the reaction but along diametrically

opposing paths. Initially, each reaction product has a known, well-defined energy. In conventional NDP, a

single detector is used to determine the residual energy of a small fraction of the particles that escape one

surface of the sample in order to establish the concentration versus depth profile of the element. However,

given a sufficiently thin sample, both particles will escape from the sample and two appropriately positioned

detectors will detect, in coincidence, both of the particles from a single reaction. Thus, for coincidence NDP

the sample of interest, illuminated with neutrons, is placed between two facing detectors that are separated

by a few centimeters. A decay event is recorded only when the products are detected simultaneously in two

detectors. The energy of the first particle is determined and plotted against the energy of the second particle.

The third axis indicates the number of events occurring with that particular energy combination. Imposing

these criteria, a three-dimensional histogram is generated.

The background correction is much reduced by this approach because random coincident events are

infrequent at the count rates typically encountered with NDP. As a result, the lower energy portion of the

spectrum can be used, thereby increasing the depth of analysis without extensive background corrections.

Because the background is reduced, detectors can be moved closer to the sample, thus increasing the

counting efficiency. On the other hand, reducing the detector to sample distance increases the acceptance

angle of the detectors which degrades the overall depth resolution of the profile. This is because the range

of particle path lengths accepted in the detector is increased for a given depth of reaction. By using the

mathematical method of Jacobians to convert the data from energy space to distance and angular space,

the energy broadening from the measured spectrum can be effectively removed. Also, the model for the

detector response function suggested by Lee, et. al., is being investigated in order to improve the overall

depth resolution. By adapting these methods for use in coincidence NDP, the detectors are being used in

a closer configuration than previously possible.

An additional logical constraint may be imposed upon the data since both the stopping power of the sample

and the total energy of the reaction is known. The residual energies measured in the two detectors must be

consistent with a single value for the depth of the reaction, within the energy resolution of the measurement.

Those events which are inconsistent with this test are rejected. This provides additional confidence and

greater accuracy in defining the depth profile.

Particle-particle coincidence NDP will have important applications in the study of interfacial distributions of

lithium and boron found in many of today’s advanced semiconductor and optical signal processing materials.

Specialized equipment has been obtained and computer programs are being developed to perform the

decision logic on data collected by this technique. The technology developed by this approach will be

especially important for lower flux research reactors, allowing effective use of NDP at these facilities.

37
1 9. Measurement of Superconductor Stoichiometry by Prompt and Delayed Neutron Activation

Richard M. Lindstrom

Materials analysis provides essential information for understanding the physics of high-temperature

superconductors and developing the production processes for their industrial application. Knowledge of the

stoichiometry of sample materials, particularly the oxygen content, is important. Although oxygen is difficult

to measure by activation with reactor neutrons, it may be determined by difference if the concentration of

other elements are known. Prompt and delayed neutron activation analysis has been applied to the

measurement of the metals in YBa2Cu307 superconductors, starting materials, and intermediate products.

The low production cross section and low gamma energies of Y-90m make the determination of yttrium

imprecise in the presence of high Cu-64 activity. The Poisson precision for Y determinations is 2% in practice,

which is helpful but inadequate for the needs of researchers.

The physical parameters for neutron-capture prompt gamma-ray activation analysis (PGAA) are more

attractive than delayed counting for stoichiometry measurements. The PGAA spectra of Y, Ba, and Cu show

three, four, and six analytically useful gamma-ray lines respectively. Moreover, the relative intensities from

the three elements are comparable for the composition range of interest. In the Maryland-NIST PGAA facility, a 100-mg sample gives a Poisson precision for yttrium (the weakest element) better than 1% in an 8-hour

irradiation, which is adequate for determining stoichiometry of laboratory samples. Since the concentrations

and mole ratios Y/Cu and Ba/Cu can be calculated immediately after the irradiation ends, the results can be

available within a day.

Compositional measurements of substituted superconductors have been made in collaboration with the

neutron scattering group. In these materials nominally 3-8% of the Cu had been substituted by Al, Fe, Ni,

Zn, or Ga. Classical delayed activation analysis was used to measure the substituent and copper. The M/Cu

ratios were not always as expected.

20. Development of an Intentional Isotopic Tracer for the Study of Particulate Emissions into the

Atmosphere

W.R. Kelly, NIST, J.M. Ondov, UMD (co-PIs), L-T. Chen, I.L Barnes, J. D. Fassett, NIST, J.M.

Hoff, C. LeCompte, S. White, University of Maryland

It is commonly believed that emissions from industrial and power plant stacks can travel great distances and

cause deleterious environmental effects at sites far removed from their sources. One of the most important

problems in atmospheric science is to determine the relative contributions of regional and distant sources

on air and deposition quality. Chemical elements and compounds believed to be indigenous to particular

types of sources have been used as tracers of opportunity in efforts to distinguish between regional versus

long range transport of emissions from oil-fired and coal-fired sources. It is claimed that by using a

multielement tracer system, the signatures of North America and Europe can be resolved several thousand

kilometers downwind. However, tracers of opportunity are not unique to single sources, rather they can be

common to a large category of sources, and thus do not yield definitive source-receptor relationships. The

true relationship between emissions from a particular source and a receptor site have never been determined

by direct experimental measurement. The ability to trace fly-ash emissions from utility coal-fired power plants

and to measure particulate deposition to natural surfaces is important to the electric utility industry.

38
Many of the difficulties discussed above can be overcome by the use of an intentional tracer to tag primary

emissions from utility sources. If successful, this approach would readily permit direct determination of

source Impacts on air quality and deposition independent of dispersion models, receptor models, or micrometeorological methods and thus permit their independent evaluation. While intentional tracers have

been used successfully in dispersion and deposition studies, they have not been widely used to tag primary

particulate emissions from large high-temperature combustion sources such as coal-fired power plants. The

principal reasons for this lack of application Include toxicity, chemical or radiologic instability, inadequate

sensitivity, and high cost of the tracer material. The application of enriched rare-earth (RE) isotopes as

intentional tracer materials may avoid all of the above difficulties.

The use of enriched RE isotopes as intentional tracers is a new technique and promises to be a powerful

approach to aerosol particulate tracing well suited for use in power plant studies. The concept is very simple

and consists of four parts; injection of the tracer, tagging of the particulate emissions, collection of the

samples, and chemical and mass spectrometric analysis of the sample. In principle, the use of enriched

isotopes of a single rare earth-element such as Nd or Sm, permits the simultaneous tagging of 5 different

power plants. The measurement by thermal Ionization mass spectrometry (TIMS) of the isotopic composition

of airborne particles and natural surfaces at some distance from the plants permits the contributions of the

individual plants to be apportioned at a receptor site. Since there are no natural or industrial sources of

enriched RE isotopes, the detection of an enrichment is definitive evidence that emissions from a tagged

plant have been measured. Use of additional RE isotopes would permit definitive and simultaneous

resolution of multiple source impacts on individual receptor sites.

An enriched isotope of the rare earth element (REE) neodymium (Nd) has been investigated to demonstrate

feasibility of the technique. Since the relative isotopic abundances of the REE are constant in nature, and

can be measured with high precision (0.002%, relative) by mass spectrometry, a small induced enrichment

can be readily resolved. Measurement of this enrichment would constitute definitive evidence that the tagged

source had been detected. The uniqueness and power of the technique is that each tagged source has a

unique isotopic signature which permits the relative and perhaps absolute contributions of multiple sources

at a single location to be de-coupled by mass spectrometric analysis of the sample. Chemical and mass

spectrometric procedures were developed to dissolve various types of samples, separate Nd with high purity

and yields by cation exchange chromatography, and measurement of the isotopic composition and

concentration of the Nd by thermal ionization mass spectrometry. In field tests in which the ^^®Nd tracer

was injected into the stack of a coal-fired power plant, we were able to detect large induced isotopic effects

at mass 148 by mass spectrometric analysis of size fractionated samples collected down stream from the

injection port.

Phase I of the project has been successfully completed. Isotopically enriched 148Nd was injected into the

stack of a coal-fired power plant in the form of highly mobile and highly charged ultrafine particles. Thermal

ionization mass spectrometry analyses of size-segregated stack-emitted fly-ash particles show that nearly

all of the tracer material becomes attached to fly ash particles and that all sizes are tagged. Our original

calculations suggested that ^"'^Nd could be detected with a 500:1 signal-to-noise ratio in ambient aerosols

100-km distant from a 425 MW(e) coal-fired power plant tagged with an injection rate of only 1 40 mg ^^®Nd/hr.

Results of the Phase I study suggest, however, that effective tagging can be achieved with even less tracer

material because of the high tagging efficiency achieved for all particle sizes. Results of a preliminary

experiment conducted in a soybean field further suggest that measurement of deposited plume particles can

be made directly on vegetative surfaces in the vicinity of the tagged plant. The high precision and accuracy

of TIMS, combined with improved air-flow monitoring techniques now available, should permit more accurate

measurement of deposition by the gradient technique.

39
Based on the results of Phase I the enriched rare-earth isotopic tracer technique is believed to have potential as a research tool for application in studies of plume dispersion, source apportionment, and particle

deposition. The Phase I reseach was supported by a grant from the Electric Power Research Institute, Palo

Alto, CA.

21. Production and Analysis of Ultrapure Acid from a Large Teflon Still

J.R. Moody, E.S. Beary, D.S. Bushee, and P.J. Paulsen

The sub-boiling method of distillation from quartz stills has been employed at NIST. Aside from limitations

of distillation rate ( ~ 0.5 - 2l_/day), the only dissatisfaction with these stills has been the inability to significantly

improve reagent purity. As instrumental techniques have improved, the demand for lower analytical blanks

has increased.

High throughput was seen as a possible method of improving distillate quality while retaining the advantages

of sub-boiling distillation. The services of the Fluoroware Corp. were engaged in order to fabricate a large

still wholly from Teflon PFA, using designs provided by NIST.

In one year, three versions of these stills have been fabricated and evaluated at NIST. Distillation rates of up

to 45 LVday have been achieved for the more volatile reagents such as HCI (10 N), H2O, HF, and HNO3. The

ICP/IMS has been employed to measure the resultant reagent purity.

Recently, we have been able to expand upon our published work by increasing the number of elements,

measured (from 35 to >60), improving our detection limits to <0.1 pg/g in some cases. We have now been

able to demonstrate a 10-fold improvement in HF purity as a result of the new still.

Other acids such as acetic acid are also amenable to distillation and will be evaluated in the near future. Both

the quantity and quality of reagent have been improved by the new still. The ICP/MS technique has been

developed to the point where significant differences in purity at the pg/g level can be measured.

22. The Development of Multielement Procedures for Analysis of Diverse Materials by ICP-MS

P.J. Paulsen and E.S. Beary

The inductively coupled plasma mass spectrometry (ICP-MS) is a highly sensitive technique that has broadly

applicability across the periodic table. We have continued to investigate its capability for accurate and

precise measurement using isotope dilution. We have also developed methods for multielement analysis

using internal and external standards. As the instrumentation has evolved, its capabilities for accurate and

sensitive measurement have continually improved.

Isotope dilution analysis with ICP-MS has been applied to the determination of Cu, Sr, Ag, Cd, and Pb in Oyster Tissue SRM 1566a. Although the chemistry for the SRM was handled as a true multielement

procedure, the elements were initially analyzed one at a time on the ICP-MS. This approach utilized a rapid

repetitive scan of a mass range limited to just the element of interest. It provides both high sensitivity and

the lowest error due to changes in instrument sensitivity and mass bias with time. The results of the spike

calibrations yielded precisions of ±0.3% and agreed with thermal mass spectrometry calibrations of the same

spikes to 0.3% accuracy. The samples themselves showed one percent or more variation due to sample

homogeneity problems.

40
The same sample solutions were then reanalyzed for Sr, Ag, Cd, and Pb simultaneously, using the peak hop

mode. Since only two masses per element need to be measured for isotope dilution, only a moderate loss

of sensitivity was encountered compared to the single element scan mode. We had not used the peak hop

mode previously since accurate data requires a much more stringent control of the mass scale stability than

with the scan mode. Recent instrument improvements have made the peak hop mode a more practical

alternative. Comparison of the peak hop isotope dilution results with the scan mode data showed good

agreement. However, we did observe minor but real differences in concentrations between the two

techniques of data collection. The differences were traced to errors from the higher count rates for the peak

hop mode (instrument sensitivity was improved between the two experiments). Further experiments

indicated that these errors are caused by gain losses in the ion multiplier (between 2x1 0^ to 1 x1 0® cps) which

drop pulses below the pulse height discrimination set point. We are currently trying to determine if this is caused by the known drop in multiplier gain in this count range, or if it Is an early indication of multiplier failure

from catastrophic gain losses which occurs only at the very high count rates.

Multielement analysis using external standards alone, and in combination with internal standards, was

evaluated in the analysis of air filter samples. An external standard containing ~30 elements at 30 ppb and

internal standards of Sc (45 amu) and Tm (169 amu) were run often throughout these analysis. Data from

these standards was used to evaluate the possibility of compensating for shifts of instrument sensitivity with

time.

The external standard program assumes a linear shift in sensitivity with time on an element by element basis.

The "internal standard" method ratios all signals in the standard and samples to the internal standard signal

to correct for sensitivity with time. This comparison showed:

(1 ) Internal standardization was better two-thirds of the time.

(2) Most of the internal normalization data is good to 1 0%.

(3) Shifts in instrument sensitivity are mass dependent with the largest shifts occurring at lower

masses.

(4) Internal standards methods should use 3 or 4 elements evenly spaced across the mass scale.

Instrumentation Affecting ICP-MS Performance

New alignment jigs and a complete realignment from torch to multiplier has resulted in a 3 to 5 fold

improvement in Instrument sensitivity. We are presently obtaining >3x10® cps for 1 ppm (100% isotope) of

solution for most elements above mass 50 amu. Photon background is 10 to 20 cps. This translates into

both lower detection limits and better counting statistics. A new MCA has been installed with double the

channels. The new unit gives higher mass resolution on a full mass scan, better precision, and solves the

instrument "lock-up" problem that was occurring when data was transferred between the old MCA and the

computer. The much shorter dead time found with the new system permits higher count rates for a given

dead time error than the original system.

41
23. Applications of ICP/MS Detection with Sample introduction by Flow Injection and Liquid

Chromatography

D.S. Bushee and J.R. Moody

The excellent sensitivity and selectivity of the inductively coupled plasma/mass spectrometer (ICP/MS) have

been used to advantage in combination with flow injection (FI) and liquid chromatographic (LC) methods of

sample introduction. Flow injection analysis provides total metal information which compliments the species

specific data obtained from chromatographic analysis. Chromatography can be used to separate the various

species of the same element as well as to isolate interferences from the element of interest in complex

samples. We have coupled a liquid chromatograph to an inductively coupled plasma/mass spectrometer to

obtain both speciation and isolation of elements.

Thimerosal (sodium ethylmercurithiosalicylate) is a mercury containing bactericide used in a number of

biological products. The LC/ICP/MS method has been used to investigate the stability of this preservative

in a series of injectable solutions and vaccines obtained from the Food and Drug Administration. These

include two Lots of Diluent (of different ages), a Lot of Tetanus Toxoid Adsorbed Vaccine and an Influenza

Vaccine. Stoppers from the sample bottles, as well as unused, "blank" stoppers were extracted and their

total mercury content determined by FI/ICP/MS.

The nominal mercury content for all the samples was 49.6 ng/mL as mercury (1 00 g/mL as thimerosal). The

manufacturers quality control specifies that a lot is acceptable if the thimerosal levels are within ± 5 i^g/mL

Hg of this level. In each case, FI results agreed with the results obtained by LC, indicating that all mercury

species present were accounted for by LC-ICP/MS. The Influenza Vaccine showed a significant loss of

thimerosal, almost 50% of the expected level. This loss was traced to the stopper, which contained a

substantial quantity of mercury. Qualitative analysis of the newer diluent and the Tetanus and Influenza

Vaccine reveal no degradation products. Chromatograms of the year old diluent contain a peak which could

not be identified, but which represents a very minor constituent.

In addition, the multielement capabilities of the LC-ICP/MS method have been investigated with the

determination of rare earth elements (REE) in NIST Fly Ash SRM 1633a. The REE concentration,patterns in

fly ash samples can be used to determine whether its source is an oil-fired or coal-fired power plant. In this

case, the LC separates the rare earth isobars from each in a ten minute scheme. The detection limits for the

REE by LC-ICP/MS are In the sub-ppb range and the response is linear over four orders of magnitude. This

technique promises to reduce the time required for analysis by a factor of ten compared to the present

technique. Results obtained on SRM 1633a compare favorably to reference values obtained by neutron

activation analysis. Future experiments will be done combining isotope dilution with LC-ICP/MS to investigate

improvements in precision and accuracy that can be achieved by combining isotope dilution with LC-ICP/MS

for fly ash analysis.

24. Automated Mass Spectrometers for Inorganic Analysis

I.L. Barnes and J.W. Gramlich

Thermal ionization mass spectrometers are now produced with many features for automated, high precision

isotope ratio measurements. To investigate the advantages of these features, we obtained a new mass

spectrometer commercially produced by the Finnigan-MAT Corporation as a Model 261. The instrument

contains an automated source region with a turret loading device that permits the loading of up to 1 3 samples

at one time for sequential analysis under computer control. The instrument was also constructed using a

new ion optical system called "stigmatic" or non-normal geometry which gives twice the dispersion of

42
equivalent size normal geometry systems. The particular advantage gained is the room to put multiple

collectors in a instrument of reasonable dimensions. In our instrument, seven Faraday collectors and one

electron multiplier are installed. A further advantage of the non-normal optical system is that focussing is obtained in the vertical or "Z" direction with the result that increased numbers of ions are obtained at the

collector.

After a period of adapting previously developed NIST methods to the software and hardware of the new

instrument, experiments were designed to test the new features and to compare them with results obtained

using the conventional, but highly developed, NIST mass spectrometers. A summary of the experience to

date in several areas is given here. For those elements which normally exhibit low mass fractionation or for

those with high sensitivity, where small samples can be mounted on the filament, the automated source

performs extremely well. In several cases, up to 26 samples were analyzed in one continuous period.

Examples of this kind of analysis are neodymium, samarium and strontium, where isotopic ratios for a large

number of samples were measured with high precision. However, for elements where ionization is more

difficult or very stable temperature is required (for example, with lead), control over the heating pattern by

an operator still gives better results and is essential for the highest precision. Under all circumstances, the

use of multiple collectors is a major advantage. High precision data was collected during times when the

signais from the sample were so unstable that the analysis would have been aborted using a conventional

instrument. The multiple collector system also allowed the analysis of very small samples. In one case, ratios

of 6 pg of neodymium were measured with a precision of 4 ppm.

The most recent major work consisted of the measurement of the isotopic ratios of several hundred samples

of nickel for the determination of the atomic weight of this element. The same samples were also measured

on a conventional NIST mass spectrometer. A comparison of the data indicated that for samples and

standards of near normal ratios the data from the commercial instruments was only slightly less precise than

the data from the NIST instrument. We believe that this may be due to the much smaller magnet gap width

of the commerciai instrument. For samples with very large isotopic ratios, the NIST developed measurement

system produced far better results due to a much wider linear dynamic range in the detection systems. Such

is the case where separated nickei isotopic measurements are required for the atomic weight determination.

The net results of these experiments are that the automated, multi-collector instrument has major advantages

for the analyses of many kinds of samples and for a number of elements, while for many other frequently

analyzed samples, the NIST type mass spectrometer will still give superior results. We have determined that

there are a number of areas in which further work will lead to major improvements and we are currently

working, in co-operation v/ith the manufacturer, to make these improvements.

25. Investigation of Atomization Processes for High Sensitivity Measurement by RIMS

J.D. Fassett, R.J. Walker, J.C. Travis, T.B. Lucatorto, L Bengtsson, and S. Mayo

Resonance ionization mass spectrometry (RIMS) is a technique that combines the ability of laser radiation

to photoionize gas phase atomic species selectively and efficiently with the mass resolution capabilities of

mass spectrometry. We have been using this technique with the production of atomic species from resistively

heated filaments. The mismatch between the duty cycles of thermal vaporization and pulsed laser ionization

has continued to limit our ultimate measurement sensitivity. Thus, we have investigated laser ablation as an

alternative means of vaporization and, at the same time, systematically studied overall measurement

efficiencies using thermal vaporization for our current RIMS analytical programs. These programs include

the elemental and isotopic measurement of Os and Re in geological materials and the elemental

determination of V in high purity semiconductor material.

43
Laser induced sputtering (desorption or abiation) has been an area of interest for some time. Our initiai experiments were directed to the vaporization of Be from a fiiament substrate. These experiments were very

positive in that the time response for atom desorption was very narrow, indicating efficient utiiization of the

sampie. Yet, the common probiems with iaser abiation from soiid substrates were observed: non-iinear

coupiing of the iaser radiation with the surface resuiting in very iarge puise-to-pulse variations of the signai

as weii as the emission of "chunks" of materiai. In order to overcome this source of irreproducibillty, we

developed a thin film ablation technique with a "compact disk" format. The laser completely evaporates a

series of 100 ^im spots from a rotating quartz disk substrate. For a 50 angstrom thick film, approximately

10^^ atoms/spot are evaporated. The thin films are formed by co-sputtering a suitable matrix material with

the analyte onto the quartz substrate. In principle, with proper geometric overlap, about 1 in 20 of the

evaporated atoms will be interrogated by the RIMS laser. This sampling utilization efficiency is probably

close to the maximum achievable using pulsed RIMS.

The initial efforts with the compact disk have been directed at finding matrix materials and co-sputtering

techniques which produce the maximum sensitivity. The matrix materials studied to date are Pt, Ta, C, Ag,

Zn, and a Ni alloy. The thin film was created in each case by argon ion sputtering from a solid target using

a planar magnetron plasma. Impurity elements such as Pb, Sn, in, Ni, Mn Mg and Y in the matrices were

used to estimate the overall sensitivity of the technique. All experiments were done using a Nd:YAG laser

for ablation. To date, both the sensitivity of the method and the shot-to-shot reproducibility have been far

from theory. The observed sensitivities are in the ppm range instead of the expected ppb range. We have

demonstrated that the ionization associated with the high temperature produced is a significant problem,

especially for matrices with high vapor pressures and low ionization potentials. Using a Zn matrix, an ablation

laser with longer pulse duration, should reduce this effect. These changes are presently being studied.

Our laboratory has become world reknown for the application of RIMS to the determination of Re and Os

concentrations (through isotope dilution) and Os isotopic compositions of chemically purified separates from

geologic samples. We have utilized a pulsed, thermal filament to increase the sample utilization efficiency.

We have previously estimated a 100-fold improvement in efficiency relative to a continuously heated filament

by measuring the emission of Ta atoms from the filament. However, Os emission from the filament is much

slower and indicates only a factor of 10- to 20-fold Improvement in sensitivity for this analyte. We have

considered two explanations for this phenomenon. The first explanation is related to the differences in the

heat of sublimation of the two substances. The second explanation is that Os forms a metal solution with

the bulk Ta filament, and the Os emission is limited by the rate of diffusion from the bulk to the surface of the

filament. Despite the sample which Is lost (10^ times that measured) because of the low laser duty cycle,

the pg sensitivity for isotopic analysis of Os has proven sufficient for a number of different studies, completed

and ongoing.

Our newest analytical effort with RIMS has been its application to the characterization of high-purity

semiconductor material. There are two issues of sensitivity that we are addressing, trace analysis and

microanalysis. We have demonstrated ppb sensitivities in the bulk analysis of silicon. We are presently

adapting methods to do controlled stripping of thin surface layers, which will then be subsequently analyzed

using isotope dilution. Measurement of pg (or less) of impurities in micrograms of sample is the planned

goal. We have chosen to develop our method with the determination of vanadium because transition metal

impurities are of importance and because RIMS is particularly well suited to the V measurement-the

selectivity of the ionization process is critical for success.

44
We have studied the ionization process for vanadium and compared the measurement sensitivity with thermal

ionization. The Saha-Langmuir relationship predicts that the ratio of ionic species to atomic species of V

emitted from a rhenium filament at 1342 K is 3.0x10*®. The duty cycle loss factor calculated for RIMS is 1.3x10^. Thus, theory predicts that RIMS is 25 times more sensitive than thermal ionization for these

conditions. We have made measurements of thermal ions and photoions that are generated from the same

sample on a rhenium filament. The ratio of signals, RI:TI, ranged from 23 (1350 K, 24 ions/s, Rl) to 2.1 (1540

K, 38000 lons/s, Rl) which is qualitatively in agreement with theory. An important point is that the two

techniques are comparable in sensitivity despite the duty cycle losses of resonance ionization. In fact, the

RIMS measurements have an important advantage relative to thermal ionization in that the titanium and

chromium backgrounds need not be monitored, and corrections need not be made for these interferences.

Thus, even with today’s lasers and unpulsed sources of atoms, RIMS has analytical advantages in inorganic

mass spectrometry for selected, and important, problems.

45
C. Outputs and Interactions

(Inorganic Analytical Research Division)

1. Publications

Barnes, I.L, 1987 Table of the Isotopic Composition of the Elements, Report to the lUPAC Commission

on Atomic Weights and Isotopic Abundances, February 1988.

Atomic Weights of the Elements - 1 987, (co-authors. Members of the Commission on Atomic Weights and

Isotopic Abundances), Pure Appl. Chem. SQ, 841-854 (1988).

Barnes, I.L, Yener, K.A., Ozbal, H., Brill, R.H., and Joel, E.C., Anatolian a Metal Trade and Lead Isotope

Analysis, Proceedings of the 34th Rencontre Assyriologique Internationale, Istanbul, Turkey 6-11

July, 1987, Accepted for publication (in press).

Barnes, I.L, Joel, E.C., Olin, J.S., and Blackman, M.J., Lead Isotope Studies of Spanish, Spanish-Colonial

and Mexican Majolica, Proceedings of the 26th International Archaeometry Symposium, Toronto,

Canada, March 1988, Accepted for publication (in press).

Barnes, I.L, The Development of High Precision Mass Spectrometry, Proceedings of the Symposium on

Elemental and Isotope Analyses by Mass Spectrometry, 36th ASMS Conference on Mass

Spectrometry and Allied Topics, San Francisco, June 5- 10, 1988, (in press).

Barnes, I.L., Murphy, T.J., and Eberhardt, K.R., A Redetermination of the Absolute Abundance Ratios and

the Atomic Weight of a Reference Sample of Strontium, Proceedings of the 11th International Mass

Spectrometry Conference, Bordeaux, France, August 29 - September 2, 1988, Hayden and Sons,

Oxford.

Beary, E.S., "Comparison of Microwave Drying and Conventional Drying Techniques for Reference

Materials," Anal. Chem. SQ, 742-746 (1988).

Beary, E.S., Paulsen, P.J., and Lambert, G.M., "Determination of Selenium and Tellurium in Copper

Standard Reference Materials Using Stable Isotope Dilution Spark Source Mass Spectrometry,"

Anal. Chem. sa, 733 (1988).

Becker, D.A., "Quality Assurance Techniques for Zinc Analysis by Neutron Activation," Trans. Am. Nucl.

Soc. 174 (1987).

Becker, D.A., "Fast-Neutron INAA: Nickel Sensitivities and Fluence Variations at Three Reactors," Trans.

Am. Nucl. Soc., 193 (1988).

Becker, P.R., Wise, S.A., Koster, B.J., and Zeisler, R., Alaskan Marine Mammal Tissue Archival Project: A

Project Description Including Protocols, NBSIR 88-3750, National Bureau of Standards,

Gaithersburg, MD, 53 (1988), 53.

Bengtsson, L, Travis, J., Lucatorto, T.B., Kreider, K., and Brown, L., "Laser Ablation of Thin Films as a Free

Atom Source for Pulsed RIMS," Accepted for publication in the proceeding of the 1 988 International

Conference on Resonance Ionization Spectroscopy and its Applications (1988).

46
Bowers, G.N., Jr. and Rains, T.C., The Measurement of Total Calcium in Biological Fluids; A Flame Atomic

Absorption Spectroscopy Method, Chapter in Metallobiochemistry. J. Riordan and B. Vallee, Eds.,

Academic Press, New York (1988).

Bowman, R.C., Jr., Downing, R.G., and Knudsen, J.F., "NDP Evaluations for Boron Implanted Compound

Semiconductors," Transactions of the American Nuclear Society 212 (1 987).

Bowman, R.C., Jr., Marks, J., Downing, R.G., Knudsen, J.F., and To, G.A., "Effects of Boron Implantation

of Silicon Dioxide Passivated HgCdTe," Proceedings of the Materials Research Society Symposium,

2Q, 279 (1987).

Clarke, W.B., Koekebakker, M., Barr, R.D., Downing, R.G., and Fleming, R.F., "Analysis of Ultratrace Lithium

and Boron by Neutron Activation and Mass-Spectrometric Measurement of ^He and "^He," Inter. J. of Appl. Radiation and Isotopes 38(9) . 735-743 (1987).

Cox, J.N., Hsu, R., McGregor, P.J., and Downing, R.G., "NDP and FTIR Studies of Borophosphosilicate

CVD Thin-Film Glasses," Transactions of the American Nuclear Society 55., 207 (1987).

Davis, R.S. and Koch W.F. "Weighing and Density Determinations," in Physical Methods of Chemistry. B. W. Rossiter, J.F. Hamilton, and R.C. Baetzold, Eds., Interscience Publishers, Rochester, NY, (in

press).

Durst, R.A., Koch, W.F., and Wu, Y.C., "pH Theory and Measurement," Ion Selective Reviews 2, 173-196

(1987)

Epier, K.S., O’Haver, T.C., Turk, G.C., and MacCrehan, W.A., "Laser-Enhanced Ionization as a Selective

Detector for the Liquid Chromatographic Determination of Alkyltins in Sediment," Anal. Chem. SQ,

2062 (1988).

Epstein, M.S., Koch, W.F., Epier, K.S., and O’Haver, T.C., "Determination of Phosphorus in Copper-Based

Alloys Using Ion-Exchange Chromatography and Direct-Current Plasma Emission Spectrometry,"

Anal. Chem. 52, 2872-2876 (1987)

Epstein, M.S., Turk, G.C., and Travis, J.C., "Application of a Nd:YAG Laser-Pumped Dye Laser to the

Determination of Nickel in River Sediment Using Nonresonance Flame Atomic Fluorescence

Spectrometry," JAAS 5, 523 (1988).

Epstein, M.S., Turk, G.S., and Travis, J.C., "Evaluation of Nd:YAG and Copper-Vapor Pumped Dye Laser

as Excitation Sources for Nonresonance Flame Atomic Fluorescence Spectrometry," Journal of

Analytical Atomic Spectroscopy, Submitted for publication.

Epstein, M.S., Diamondstone, B.I., and Gills, T.E., "A New River Sediment Standard Reference Material,"

Talanta, USA Honor Issue, (in press).

Epstein, M.S., Carnrick, G.R., Slavin, W., and Miller-lhli, N.J., "Slurry Sampling in Graphite Furnace Atomic

Absorption Spectrometry for Homogeneity Evaluation of a River Sediment," Analytical Chemistry,

Submitted for publication.

47
Epstein, M.S., Jenkins, R.E., Epier, K.S., and O’Haver, T.C., "Automation and Application of a Direct Current

Plasma Emission Spectrometer," Proceedings of the Symposium on Accuracy in Trace Analysis - Accomplishments, Goals and Challenges, J. Res. Natl. Bur. Stand. 22, 458 (1988).

Epstein, M.S., Diamondstone, B.I., Gills, T.E., and Adams, J.R., "A New River Sediment Standard Reference

Material," Proceedings of the Symposium of Accuracy in Trace Analysis - Accomplishments, Goals

and Challenges, To be published in the NBS Journal of Research, J. Res. Natl. Bur. Stand. 22, 234

(1988).

Epstein, M.S., "Book Review - Separation and Spectrophotometric Determination of Elements," Anal.

Chem. 62, 631A(1988).

Epstein, M.S. and Smeller, H., "Living with Radon, Part II," DEAIHA Newslett. 4, 3 (1988).

Fassett, J.D., Inn, K.G.W., and Watters, R.L, Jr., "Development of the NBS Beryllium Isotopic Standard

Reference Material," in Resonance Ionization Spectroscopy (1988), Inst. Phys. Conf. Ser. (1988),

(in press).

Fassett, J.D. and Travis, J.C., "Analytical Applications of Resonance Ionization Mass Spectrometry (RIMS),"

Spectrochim. Acta B (1988), (in press).

Fassett, J.D., Walker, R.J., Travis, J.C., and Ruegg, F.C., "Measurement of Low Abundance Isotopes by

Laser Resonance Ionization Mass Spectrometry," Anal. Instrum. 17, 69-86 (1988).

Feng, Darning, Wu, Y.C., and Koch, W.F., "The Second Dissociation Constant and pH of HEPES from 0

to 50 °C," (in review).

Fleming, R.F. and Lindstrom, R.M., "Precise Determination of Aluminum by Instrumental Neutron

Activation," J. Radioanal. Nucl. Chem. 113. 35-42 (1987).

Greenberg, R.R. and Zeisler, R., "A Radiochemical Procedure for the Determination of Chromium in Biological Materials," J. Radioanal. Nucl. Chem. (1987), (in press).

Greenberg, R.R., Zeisler, R., and Malozowski, S., "Investigation of Natural Chromium Levels in Human

Blood," J. Trace Elem. Electrolytes Health Dis. (1988), (in press).

Greenberg, R.R., "Evaluation of Precision and Accuracy of Selenium Measurements in Biological Materials

Using Neutron Activation Analysis," Transactions of the American Nuclear Society 62, 1 48-9 (1 988).

Greenberg, R.R., Zeisler, R., Kingston, H.M., and Sullivan, T.M., "Neutron Activation Analysis of the NBS

Bovine Serum Standard Reference Material Using Chemical Separations," To be submitted to

Fresenius Z. Anal. Chem.

Greenberg, R.R., "Analysis of Atmospheric Particulate Samples Via Instrumental Neutron Activation

Analysis," To be submitted to Proc. of Conf. on Recent Developments in Monitoring Methods for

Toxics in the Atmosphere.

Greenberg, R.R. and Zeisler, R., "A Radiochemical Procedure for the Determination of Chromium in Biological Materials," J. Radioanal. Nucl. Chem. (1987), (in press).

48
Gunaratna, P.C., Marinenko, G., and Koch, W.F., "Sodium Activity Measurements in Protein Solutions with

Sodium Amalgam Electrodes," (in review).

Gunaratna, P.C., Paule, R.C., and Koch, W.F., "Interlaboratory Test Studies for the Development of

Reference Materials for Potentiometric Sodium and Potassium Measurements in Serum," (in review).

Gunaratna, P.C., Paule, R.C. and Koch, W.F., "Development of Reference Materials for Potentiometric

Sodium and Potassium Measurements in Serum," Proceedings of the International Symposium on

the Measurement of Blood Electrolytes, Danvers, MA, Sept 24, 1987.

Han, Kai and Koch W.F., "Ion Chromatographic Determination of Magnesium and Calcium at the

Part-per-Billion Level with Concentrator Columns," LC-GC£, 156-160 (1988).

Inn, K.G.W., Raman, S., Coursey, B.M., Fassett, J.D., and Walker, R.L, "Development of the ^°Be/^Be

Isotopic MBS Standard Reference Material," Nucl. Instrum. Meth. Phys. Res. B29. 27 (1987).

Iyengar, G.V., "Dietary Intake Studies of Nutrient and Selected Toxic Elements in Human Subjects:

Analytical Approaches," Clin. Nutr. g, 105-117 (1987).

Iyengar, G.V., "Dietary Collection Procedures," Clin. Nutr. g, 143-153 (1987).

Iyengar, G.V., Practical Constraints in Monitoring Micronutrient Intake," Clin. Nutr. g, 156-158 (1987).

Iyengar, G.V., Jones, J., Cook, K., Tanner, J.T., and Wolf, W.R., "Comparison of Zinc Determination in Foods by Different Analytical Techniques," Trans. Am. Nucl. Soc. gg, 177-178 (1987).

Iyengar, G.V., Stoeppler, M., Thomassen, Y., and Welz, B., "Quality Control," in Trace Elements in Health

and Disease. Symposium Report, Environmental Health Series, World Health Organization,

Regional Office, Copenhagen 2g, 33-36 (1987).

Iyengar, G.V., "The Role of Neutron Activation Analysis in Nutritional Biomonitoring Programs," Trans. Am.

Nucl. Soc. gg, 233-234 (1 988).

Iyengar, G.V., "Biological Trace Element Research: A Multidisciplinary Science," Sci. Total Environ. 71,

1-5 (1988).

Iyengar, G.V. and Behne, D., "Appropriate Reference Parameters for the Evaluation of Elemental Analysis

Data from Biomedical Specimens," J. Res. Natl. Bur. Stds., (U.S.) 92, 326-328 (1988).

Iyengar, G.V. and Gopal-Ayengar, A.R., Human Health and Trace E Elements Including Effects on High

Altitude Populations, Ambio, XVII, 31-35 (1988).

Iyengar, G.V. and Woittiez, J.R.W., "Trace Elements in Human Clinical Specimens: Evaluation of Literature

Data to Identify Reference Values," Clin. Chem. 24, 474-481 (1988).

Iyengar, G.V., Tanner, J.T., Wolf, W.R., Zeisler, R., "Development of Multi-Purpose Biological Reference

Materials," J. Res. Natl. Bur. Stds. (U.S.) 92, 360-362 (1988).

49
Jamieson, D.N., Bowman, R.C., Adams, P.M., Knudsen, J.F., and Downing, R.G., "Study of Boron

implantation in CdTe," in Fundamentals of Beam-Solid Interactions and Transient Thermal

Processing. M. J. Aziz, L E. Rehn, and B. Stritzker, Eds., 101. 299-304 (1988).

Jassie, LJ. and Kingston, H.M., Eds., "Introduction to Microwave Acid Decomposition," in Introduction to

Microwave Sample Preparation: Theory and Practice. Reference Book Series, American Chemical

Society, Washington, DC, September 1988, (in press).

Kingston, H.M. and Jassie, L.B., "Fundamental Relationships in Acid Decomposition of Environmental

Samples for Elemental Analysis Using Microwave Energy," in Proceedings of the USEPA

Symposium on Waste Testing and Quality Assurance. July 13, 1988, Washington, DC, Vol. 1, p. D-44.

Kingston, H.M. and Jassie, L.B., Eds., Introduction to Microwave Sample Preparation: Theory and

Practice, Reference Book Series, American Chemical Society, Washington, DC, September 1988

(in press).

Kingston, H.M. and Jassie, L.J., Eds., "Monitoring and Predicting Parameters in Microwave Dissolution,"

in Introduction to Microwave Sample Preparation: Theory and Practice . Reference Book Series,

American Chemical Society, Washington, DC, September 1988 (in press).

Kingston, H.M. and Jassie, L.J., Eds., "Safety Guidelines for Microwave Systems in the Analytical

Laboratory," in Introduction to Microwave Sample Preparation: Theory and Practice. Reference

Book Series, American Chemical Society, Washington, DC, September 1988, (in press).

Kingston, H.M. and Jassie, L.B., "Microwave Acid Sample Decomposition for Elemental Analysis," J. Res.

Natl. Bur. Stds. 93 (31 . 269 (1988).

Kingston, H.M. and Jassie, LB., "Fundamental Relationships in Acid Decomposition of Samples for

Elemental Analysis Using Microwave Energy," Proceedings of Symposium on Microwave

Processing of Materials, Material Research Society, (in press).

Kingston, H.M., Binstock, D.A., Grohse, P.M., Gaskill, A., Luk, K.K., and Swift, P.L, "Validation of Methods

for Determining Elements in Solid Waste by Microwave Digestion," Processings of Waste Testing

and Quality Assurance, Volume I, U.S. EPA Symposium, D1-D12 (1988).

Kingston, H.M. and Hawk, G.L., "Laboratory Robotics for Trace Analysis," In Quantitative Trace Analysis

of Biological Materials, H.A., McKenzie and LE. Smythe, Eds., Elsevier Science Publishers, New

York (in press).

Kingston, H.M., Patterson, K.Y, and Veillon, C., "Microwave Digestion of Biological Samples for Selenium

Analysis by Electrothermal Atomic Absorption Spectrometry," In Fuandmental of Microwave

Techniques for Sample Preparation, Kingston, H.M., and Jassie, L.B., Eds., Qther Book Series,

American Chemical Society, Washington, DC, (in press).

Kingston, H.M., Strachan, D.M., Tymochowicz, S., and Schubert, P., "Preconcentration of Trace Transition

Metai and Rare Earth Elements from Highly Saline Solutions," Analytica Chemica Acta, Accepted

for Publication.

50
Knudsen, J.F., Downing, R.G., and Simons, D.S., "NDP, SIMS, and Modeiing of Boron Impiantation Profiles

in Silicon," Transactions of the American Nuclear Society SS, 210 (1987).

Koch, W.F. and Liggett, W.S., Jr., "Critical Assessment of Detection Limits for Ion Chromatography" ACS

Symposium Series 361, "Detection Limits: From Basic Concepts to Practical Applications," LA.

Currie, Ed., American Chemical Society, Washington, DC (1988).

Koch, W.F., "Ion Chromatography: From Anions to Metals," Proceedings of the Symposium on Accuracy

in Trace Analysis - Accomplishments, Goals and Challenges, Gaithersburg, MD, September 30,

1987, J. Res. Natl. Bur. Stand. 93(31 . 411-412 (1988).

Lauenstein, G.G., Wise, S.A., Zeisler, R., Koster, B.J., Schantz, M.M., and Golembiewska, S.L, National

Status and Trends Program for Marine Environmental Quality Specimen Bank Project: Field

Manual, NOAA Technical Memorandum NOS OMA37, Rockville, MD, December 1987.

Leifer, R., Juzdan, R.Z., Kelly, W.R., Fassett, J.D., and Eberhardt, K.R., "Detection of Uranium from

Cosmos-1402," Science 2M, 512-514 (1987).

Lindstrom, R.M., Zeisler, R., and Rossbach, M., "Activation Analysis Opportunities Using Cold Neutron

Beams," J. Radioanal. Nucl. Chem. 112. 321-330 (1987).

Lindstrom, R.M., Nuclear Analytical Methods in Standards Certification, in H. H. Ross, Ed., "Comparison

of Nuclear Analytical Methods with Competitive Methods," (IAEA-TECDOC-435), International

Atomic Energy Agency, Vienna, pp. 187-193 (1987).

Lindstrom, R.M., "Measurement of Superconductor Stoichiometry by Prompt and Delayed Neutron

Activation," Trans. Am. Nucl. Soc. 231 (1988).

Lindstrom, R.M., Analytical Standards in Silicon Analysis, Proc. IAEA Consultants’ Meeting on the Need

for Intercomparison and Reference Materials for Characterization of Silicon, (Gaithersburg, Md,

1987: lAEA-TECDOC), Internationai Atomic Energy Agency, Vienna (1988), (in press).

Lindstrom, R.M., Fleming, R.F., and Rook, H.L, Neutron Microprobe: Prospects and Potential

Applications, "Microbeam Analysis 1988": San Francisco Press, 407-408 (1988).

Lindstrom, R.M., Neutron Activation Analysis in Electronic Technology, Submitted for pubiication to the

Electrochemical Society (1988).

Losee, D.L, Hossain, T.Z., Lavine, J.P., and Downing, R.G., Neutron Depth Profiles of Ion-Implanted Boron

in Polymeric Thin Films," Transactions of the American Nuciear Society 5^, 209 (1 987).

Marinenko, G., Gunaratna, P.C., and Koch, W.F., "Research at NBS in Direct Potentiometric Measurements

in Blood" in Methodology and Ciinical Applications of Ion-Selective Eiectrodes. Volume 8,

Proceedings of the IFCC 8th EWGISE Meeting, October 2-4, 1986, Graz, Austria.

Messman, J.D., O’Haver, T.C., and Epstein, M.S., "Precision of Wavelength-Modulated Atomic Absorption

Measurements of High Calcium Concentrations in a Nitrous Oxide-Acetylene Flame," Analytical

Chemistry, Submitted for publication.

51
Moody, J.R., Greenberg, R.R., Pratt, K.W., and Rains, T.C., "Recommended Inorganic Chemicals for Use

as Calibrants," Submitted to Anal. Chem.

Moody, J.R., Wissink, C.E., and Beary, E.S., "Design for a Large High Efficiency Sub Boiling Still," Prepared

for Analytical Chemistry, WERB.

Moody, J.R., Beary, E.S., Bushee, D.S., and Paulsen, P.J., "High Purity Fluoropolymer Materials: Trace

Element Content and Leaching," Journal of Crystal Growth S3, 43-48 (1988).

Moody, J.R. and Paulsen, P.J., "Isotope Dilution Spark Source Mass Spectrometric Determination of Total

Mercury in Botanical and Biological Samples," Analyst 113. 923 (1988).

Palmieri, M., "An Introduction to Supercritical Fluid Chromatography, Part 1: Principles and

Instrumentation," Journal of Chemical Education (1988), (in press)

Palmieri, M. and Frtiz, J.S., "Detection of Metal Ions by Liquid Chromatographic Separation of Their

1,3-Dimethyl-4-acetyl-2-pyrazolin-5-one Chelates," Anal. Chem. (1988), (in press).

Paulsen, P.J., Beary, E.S., Bushee, D.S., and Moody, J.R., "Inductively Coupled Plasma Mass

Spectrometric Analysis of Ultrapure Acids," Anal. Chem. SQ, 971 (1988).

Paulsen, P.J., Beary, E.S., Bushee, D.S., and Moody, J.R., "Analysis of Ultra-Pure Reagents from a Large

Teflon Sub-Boiling Still," Submitted to Anal. Chem.

Pratt, K.W. and Koch, W.F., "High-Accuracy Differential Pulse Anodic Stripping Voltammetry Using Indium as an Internal Standard," Anal. Chim. Acta, Accepted July 2, 1988 (in press).

Pratt, K.W., Kingston, H.M., MacCrehan, W.A., and Koch, W.F., "Voltammetric and Liquid Chromatographic

Identification of Organic Products of Microwave-Assisted Wet Ashing of Biological Samples," Anal.

Chem. m, 2024 (1988)

Riley, J.E., Jr. and Downing, R.G., "Quantitative Determination of Boron in Semiconductors Using Neutron

Depth Profiling," Transactions of the American Nuclear Society 207 (1987).

Riley, J.E., Jr., Downing, R.G., and Fleming, R.F., "Neutron Depth Profiling of Lithium in Lithium Niobate,"

Transactions of the American Nuclear Society 214 (1987).

Riley, J.E., Jr. and Lindstrom, R.M., "Determination of Boron in Borosilicate Glasses by Neutron Capture

Prompt Gamma-Ray Activation Analysis," J. Radioanal. Nucl. Chem. 109. 109-115 (1987).

Rossbach, M., Scharpf, O., Kaiser, W., Graf, W., Schirmer, A., Faber, W., Duppich, J., Zeisler, R., "The Use

of Focusing Supermirror Neutron Guides to Enhance Cold Neutron Fluence Rates," Nucl. Instrum.

Meth., Submitted.

Rossbach, M., Zeisler, R., and Lindstrom, R. M., PGNAA with Cold Neutrons - A Challenge for Chemical

Analysis, Proc. International Symposium on the Utilization of Multi-Purpose Research Reactors,

(Grenoble, France, 19-23 October 1987: IAEA-SM-300-016), (1988), (in press).

52
Settle, F.A.A. and Pleva, M., "The Expert System - A Tool for the Analytical Chemist?," Accepted for

publication in American Laboratory, scheduled for October 1988.

Settle, F.A., Diamondstone, B.I., Kingston, H.M., and Pleva, M., "An Expert Syste for Sample Preparation

by Microwave Dissolution: I. The Selection of Analytical Parameters," Submitted for publication in the Journal of Chemical Information and Computer Sciences.

Settle, F.A., Dean, J., and Merritt, L, Instrumental Methods of Analysis. 7th Ed., Wadsworth Publishing

Co., Belmont, CA (1988).

Settle, F.A., Karasek, F., and Pleva, M., Gas Chromatography - Mass Spectrometry: A Knowledge Base.

Elsevier Scientific Software, Amsterdam, the Netherlands (1988).

Stone, S.F., Zeisler, R., Gordon, G.E., "Quantitative Determination of Proteins Using Polyacrylamide Gel

Electrophoresis and Neutron Activation," J. Trace Elem. Electrolytes Health Dis. (1988), (in press).

Stone, S.F., Zeisler, R., and Koster, B.J., "Neutron Activation Analysis of Major, Minor, and Trace Elements

in Marine Sediments", Trans. Am. Nucl. Soc. 228-229 (1988).

Stone, S.F., Becker, D.A., Koster, B.J., Pella, P.A., Sleater, G.A., Tillekeratne, M.P.M., and Zeisler, R.,

Inorganic Analytical Methods and Results for Marine Bivalves and Sediments, in Progress in Environmental Specimen Banking, NBS Spec. Publ. 740, U. S. Government Printing Office,

Washington, DC, 62-73 (1988).

Syty, A., Christensen, R.G., and Rains, T.C., "Determination of Added Chromium (III) and Chromium (VI)

in Natural Water by Ion-Pairing High-Performance Liquid Chromatography with Detection by Atomic

Absorption Spectrometry," JAAS 3, 193-197 (1988)

Turk, G.C., MacCrehan, W.A., Epier, K.S., and O’Haver, T.C., "Laser-Enhanced Ionization as an Element

Specific Detector for Liquid Chromatography," in "Resonance Ionization Spectroscopy 1988," G. S.

Hurst, Ed., lOP Publishing, Ltd. (Bristol, England).

Ueda, J., Miyanaga, K., and Rains, T.C., "Electrochemical Atomisation Atomic Absorption Spectrometric

Determination of Tin After Coprecipitation with Hafnium Hydroxide,: JAAS, October (1988).

Velapoldi, R.A. and Epstein, M.S., "Luminescence Standards for Macro- and Microspectrofluorimetry,"

Chapter in ACS Symposium Series, Submitted for publication.

Walker, R.J., Fassett, J.D., and Travis, J.C., 'The Use of Resonance Ionization Mass Spectrometry for

Measuring the Isotopic Compositions of Rhenium and Osmium Extracted from Silicate Rocks," in Resonance Ionization Spectroscopy 1988, Inst. Phys. Conf. Ser. (1988), (in press).

Watters, R.L., Jr. and Wood, L.J., "The Role of the Blank in the Measurement of Detection Limits in Atomic

Spectrometry: Real-World Limitations to Detection" in Detection in Analytical ChemistryI mportance. Theory, and Practice. LA. Currie, Ed., ACS Symposium Series 361 , Ch. 1 6, pp. 300-306,

American Chemical Society, Washington, DC (1988).

Watters, R.L, Jr., Carroll, R.J., and Spiegelman, C.H., "Heteroscedastic Calibration using Analyzed

Reference Materials as Calibration Standards," Proceedings of the Symposium of Accuracy in Trace

53
Analysis - Accomplishments, Goals and Challenges, published in the NBS Journal of Research, J. Res. Natl. Bur. Stand. 264 (1988).

Watters, R.L, Jr., DeVoe. J.R., Shen, F.H., Small, J.A., and Marinenko, R.B., "Characteristics of Aerosols

Produced by the Spark Discharge," Submitted to Analytical Chemistry.

Wen, J., Travis, J.C., Lucatorto, T.B., Johnson, B.C., and Clark, C.W., "Measurement of Isotope

Shifts of Two-Photon Transitions in Beryllium," Phys. Rev. A. 2Z, 4207-4212 (1988).

Wise, S.A., Zeisler, R., and Goldstein, G.M., Eds., Progress in Environmental Specimen Banking, NBS

Spec. Publ. 740, U. S. Government Printing Office, Washington, DC, 217 (1988).

Wise, S.A., Koster, B.J., and Zeisler, R., Status of Specimen Banking Activities at the National Bureau of

Standards, in Progress in Environmental Specimen Banking, NBS Spec. Publ. 740, U. S. Government Office, Washington, DC, 10-18 (1988).

Wu, Y.C., Pratt, K.W., and Koch, W.F., "An Absolute Determination of the Specific Conductance of Primary

Standard KCI Solutions," Approved by WERB, Submitted to J. Soln. Chem.

Wu, Y.C., Koch, W.F., Hamer, W.J., and Kay, R.L, "A Review on the Electrolytic Conductance Standards,"

J. Soln. Chem. 16(121 . 985-997 (1987).

Wu, Y.C., Koch W.F., and Durst, R.A., "Standard Reference Materials; Standardization of pH

Measurements," Natl. Bur. Stand. (U.S.) Spec. Pub. 260-53 (1988).

Wu, Y.C., Koch, W.F., Zhong, En Ci, and Friedman, H.L, "The Cross-Square Rule for Transport in Electrolyte Mixtures," J. Phys. Chem. 22, 1004-1008 (1988).

Wu, Y.C., Feng, Darning, and Koch, W.F., "Evaluation of Liquid Junction Potentials and the Determination

of pH Values of Strong Acids at Moderate Ionic Strengths," Submitted to J. Soln. Chem.

Xiao, Y.-K., Beary, E.S., and Fassett, J.D., "An Improved Method for the High-Precision Isotopic

Measurement of Boron by Thermal Ionization Mass Spectrometry," Int. J. Mass Spectrom. Ion Proc.

203-213 (1988).

Zeisler, R. and Becker, D.A., "Determination of Zinc in a Monel Alloy by Compton Suppression

Spectrometry," Trans. Am. Nucl. Soc. 175, (1987).

Zeisler, R., Stone, S.F., and Sanders, R.W., "Sequential Determination of Biological and Pollutant Elements

in Marine Bivalves," Anal. Chem., (in press).

Zeisler, R., Greenberg, R.R., and Stone, S.F., "Radiochemical and Instrumental Neutron Activation Analysis

Procedures for the Determination of Low Level Trace Elements in Human Livers," J. Radioanal. Nucl.

Chem. (1987), (in press).

Zeisler, R., Greenberg, R.R., Stone, S.F., and Sullivan, T.M., "Selenium Determinations for the Assessment

of Sample Stability in Specimen Banking," Trans. Am. Nucl. Soc. 56, 153-154 (1988).

Zeisler, R. and Greenberg, R.R., "Determination of Baseline Platinum Levels in Biological Materials," J. Trace Elem. Electrolytes Health Dis. (1988), (in press).

54
Zeisler, R., Greenberg, R. R., and Stone, S. F., The Determination of Trace Elements in Human Livers, in Progress in Environmental Specimen Banking, MBS Spec. Publ. 740, U. S. Government Printing

Office, Washington, DC, 82-90 (1988).

2. Talks

Barnes, I.L, Trace Element Analyses - State of the Art., Science Awareness Day, Prince Georges

Community College, November 10, 1988. Invited

Barnes, I.L, The Development of High Precision Mass Spectrometry, Symposium on Elemental and

Isotope Analyses by Mass Spectrometry, 36th ASMS Conference on Mass Spectrometry and Allied

Topics, San Francisco, June 5- 10, 1988. Invited

Barnes, I.L, Experiences with an Automated, Multi-collector Mass Spectrometer, Workshop on "Isotope

Ratio MS: A Look to the Future", 36th ASMS Conference on Mass Spectrometry and Allied Topics,

San Francisco, June 5-10, 1988. Invited

Barnes, I.L, A Redetermination of the Absolute Abundance Ratios and the Atomic Weight of a Reference

Sample of Strontium, (T.J. Murphy and K.R. Eberhardt, co-authors), 11th International Mass

Spectrometry Conference, Bordeaux, France, August 29 - September 2, 1988.

Barnes, I.L., A Redetermination of the Absolute Abundance Ratios and the Atomic Weight of a Reference

Sample of Strontium, (T.J. Murphy and K.R. Eberhardt, co-authors). Central Bureau for Nuclear

Measurements, Geel, Belgium, Septembers, 1988. Invited

Beary, E.S. and Paulsen, P.J., "Trace Metal Determinations in NBS Bovine Serum Using ICP/MS Isotope

Dilution," 30th Rocky Mountain Conference, Denver, Colorado, July 1988.

Beary, E.S. and Paulsen, P.J., "Trace Element Determinations in Bovine Serum Using Stable Isotopic

Dilution," 30th Rocky Mountain Conf., Denver, CD, July 1988.

Becker, P.R., Koster, B.J., Zeisler, R., and Wise, S.A., "The Alaskan Marine Mammal Tissue Archival

Program - Development of a Contaminant Monitoring Resource," 11th U.S. German Seminar of

State and Planning on Environmental Specimen Banking, Bayreuth, FRG, May 2, 1988. Invited

Becker, D.A., "Determinationo f Zinc in a Monel Alloy by compton Supression Spectrometry," American

Nuclear Society Winter Meeting, Los Angeles, November 16, 1987. Invited

Becker, D.A., "Fast-Neutron INAA: Nickel Sensitivities and Fluence Varaitions at Three Reactors,"

American Nucler Society Symposium, San Diego, CA, June 15, 1988. Invited

Becker, D.A., "Neutron Activation Analysis: A Unique Tool for Reference Material Certification,"

Czechoslovak Spectroscopy Society Conference, Ceske Budejovice, Czechoslovakia, June 23,

1988. Invited

Becker, D.A., "Neutron Activation Analysis at NBS," Nuclear Research Institute, Rez, Czechoslovakia, June

24, 1988.

Becker, D.A., "Accuracy and Precision in NAA at NBS," International Atomic Energy AGency, Seibersdorf

Laboratory, Seibersdorf, Austria, July 5, 1988.

55
Bengtsson L, Travis, J.C., Fassett, J.D., Kreider, K., Lucatorto, T.B., and Brown, L, "Atomization by Laser

Ablation of Thin Films for Pulsed RIMS," 4th RIS Symposium, Gaithersburg, MD, April 12, 1988.

Downing, R.G., "Neutron Depth Profiling: Current Developments of the Technique in the United States,"

American Nuclear Society Conference on Industrial Radiation and Radioisotope Measurement

Applications, Pinehurst, N.C., September 6, 1988. Invited

Downing, R.G., "On Neutron Depth Profiling," Radiation Reactor Division Staff Seminar, NBS, August 4,

1988.

Epier, K.S., O’Haver, T.C., and Turk, G.C., "Laser-Enhanced Ionization Spectroscopy for Biological Trace

Metal Analysis," North American Chemical Conference, Toronto, Canada, June 8, 1988. Invited

Epier, K.S., O’Haver, T.C., Turk, G.C., and MacCrehan, W.A., "Applications of Liquid

Chromatography-Laser Enhanced Ionization Spectroscopy," FACSS ’88’, Boston, October 31,

1988.

Epstein, M.S., "Computer Communication and Information Services for the Scientist," Department of

Chemistry and Biochemistry Seminar, University of Maryland, College Park, MD, October 1987.

Invited

Epstein, M.S., Watters, R.L, Jr., Kingston, H.M., and Miller-lhli, N.M., "Successful Atomic Spectrometric

Determinations", SAS Short Course, Detroit, Ml, October 3-4, 1987. Invited

Epstein, M.S., Watterls, R.L, Jr., Kingston, H.M., and Miller-lhli, N.M., "Successful Atomic Spectrometric

Determinations," SAS Short Course, New Orleans, LA, February 20-12, 1988. Invited .

Ewing, K., Rains, T.C., Paulsen, P.J., and Beary, E.S., "Purification and Analysis of Fluoride Raw Materials

at Sub-ppb Levels," Japan, April 1988.

Fassett, J.D., Inn, K.G.W., and Watters, R.L, Jr., "Development of the NBS Beryllium Isotopic Standard

Reference Material," 4th RIS Symposium, Gaithersburg, MD, April 12, 1988.

Fassett, J.D. and Travis, J.C., "Laser RIMS-From Conception to Reality," 1988 Gordon Research

Conference on Analytical Chemistry, New Hampton, NH, August 8, 1988.

Fleming, R.F., "Advances with Neutron Beam Techniques," Symposium on Accuracy in Trace Analysis,

Gaithersburg, MD, September 30, 1987.

Fleming, R.F., "The Medium Flux Reactor as a Research Tool in Materials Analysis," McMaster University,

Hamilton, Ontario, Canada, December 21, 1987.

Fleming, R.F., "Elemental Analysis Using Neutron Beam Techniques," Indo-US Workshop on Advanced

Techniques for Microstructural Characterization," Bombay, India, January 13, 1988.

Fleming, R.F., "Elemental Analysis with Neutron Beams," Indira Gandhi Centre for Atomic Research,"

Kalpakkam, India, January 19, 1988.

56
Fleming, R.F., "Advances with Neutron Beam Techniques," Chemistry Department Seminar, University of

Maryland, College Park, MD, February 26, 1988.

Fleming, R.F., "Neutron Depth Profiling with Cold Neutrons," NBS Workshop on Microstructure and

Macromolecular Research with Cold Neutrons, Gaithersburg, MD, April 21, 1988.

Fleming, R.F., "Study of Polymers with Neutron Depth Profiling," Staff seminar. Polymer Research Institute,

University of Massachusetts, Amherst, Massachusetts, May 6, 1988.

Fleming, R. F., "Neutron Interrogation and Diagnostics," Symposium on the Research Potential of the

Georgia Tech Reactor, Georgia Institute of Technology, Atlanta, Georgia, May 12, 1988.

Fleming, R.F., "A Nuclear Engineering Approach to Neutron Activation Analysis," Nuclear Engineering

Department Seminar, University of Michigan, Ann Arbor, Michigan, July 26, 1988.

Greenberg, R.R., Zeisler, R.L, and Malozowski, S., "Investigation of Natural Chromium Levels in Human

Blood," 5th International Workshop on Trace Element Analytical Chemistry in Medicine and Biology,

Neuherberg, FRG, April 15, 1988.

Greenberg, R.R., Zeisler, R., Kingston, H.M., and Sullivan, T.M., "Neutron Activation Analysis of the NBS

Bovine Serum Standard Reference Material Using Chemical Separations," Third International

Symposium on Biological Reference Materials, Bayreuth, FRG, May 6, 1988.

Greenberg, R.R. and Inn, K.G.W., "Determination of Uranium-238 in Environmental radioactivity Standard

Reference Materials by Instrumental Neutron Activation Analysis," Thirty-third Annuai Conf. on

Bioassay, Analytical and Environmental Radiochemistry, Berkeley, CA, October 7, 1987.

Greenberg, R.R., "Evaluation of Precision and Accuracy of Selenium Measurements in Biological Materials

Using Neutron Activation Analysis," American Nuclear Society Summer Meeting, San Diego, CA,

June 14, 1988. Invited

Greenberg, R.R., Zeisler, R., and Malozowski, S., "Investigation of Natural Chromium Levels in Human

Blood," 5th International Workshop on Trace Element Analytical Chemistry in Medicine and Biology,

Neuherberg, FRG, April 15, 1988.

Inn, K.G.W., Fassett, J.D., Coursey, B.M., Walker, R.L., and Raman, S., "Development of the NBS Beryllium

Isotopic Standard Reference Material," DOE Workshop on Advanced Laser Technology for

Chemical Measurements, NBS, Gaithersburg, MD, Novembers, 1987.

Iyengar, G.V., Clarke, W.B., Downing, R.G., and Tanner, J.T., "Boron and Lithium in Biological and Dietary

Materials," 5th International Workshop on Trace Element Analytical Chemistry in Medicine and

Biology, Neuherberg, FRG, April 15-18, 1988.

Iyengar, G.V. and Wolf, W.T., "Multi-Purpose Biological RMs," Third International Symposium on Biological

Reference Materials, Bayreuth, FRG, May 4-7, 1988.

Iyengar, G.V., "Nutritional Chemistry of Chromium," Symposium on Chromium Paradox in Modern Life

sponsored by Association of Government Toxicologists, NIH, Bethesda, MD, May 23-24, 1988.

Invited

57
Iyengar, G.V., "Total Quality Control Procedures for Biological Trace Element Research Studies," Expert

Panel on Quality Control, International Conference on Trace Elements in Health and Disease,

Qdense, Denmark, August 16-21, 1987. Invited

Iyengar, G.V., Wolf, W.R., and Tanner, J.T., "USDA-FDA-NBS Project in the Coordinated Research Program

on Human Dietary Intake of Minor and Trace Elements," Third Conference for Federally supported

Human Nutritional Research Units, NIH, Bethesda, MD, February 24-25, 1987. Invited

Iyengar, G.V., "ICRP Reference Man Update," IV Task Group Meeting of the International Commission on

Radiological Protection, Paris, June 26-July 1, 1988.

Iyengar, G.V., "Nutritional Chemistry of Chromium," Symposium on Chromium Paradox in Modern Life

Sponsored by Association of Government Toxicologists, NIH, Bethesda, MD, May 23-24, 1988.

Iyengar, G.V. and Woittiez, J.R.W., "Trace Elements in Human Clinical Specimens," An Evaluation of

Literature Data to Identify Reference Values, 5th International Workshop on Trace Element Analytical

Chemistry in Medicine and Biology, Neuherberg, April 15-18, 1988.

Iyengar, G.V., Wolf, W.R., Tanner, J.T., and Zeisler, R., Working Report on investigations carried out during

1987-1988, "IAEA Coordinated Research Program on Human Daily Dietary Intake of Nutritionally

Important Trace Elements," Meeting of the Analysts, Vienna, April 9-10, 1988.

Iyengar, G.V., "ICRP Reference Man- an Update," III Task Group Meeting of the International Commission

on Radiological Protection, ORNL, Oak Ridge, Tennessee, December 2-4, 1987.

Iyengar, G.V., Wolf, W.R., Tanner, J.T., and Zeisler, R., Working Report on investigations carried out During

1986-1987, "IAEA Coordinated Research Program on Human Daily Dietary Intake of Nutritionally

Important Trace Elements," III Research Coordination Meeting, Kona, Hawaii, April 6-11, 1987.

Iyengar, G.V., "Radiochemical Separations for Trace Elements in Total Diets," International Conference on

Methods and Applications of Radioanalytical Chemistry, ANS Topical Conf., Kona, Hawaii, April

5-10, 1987.

Iyengar, G.V., "ICRP Reference Man- an Update," II Task Group Meeting of the International Commission

on Radiological Protection, Chiba, Japan, March 9-14, 1987.

Iyengar, G.V., Clarke, W.B., Downing, R.G., and Tanner, J.T., "Boron and Lithium in Biological and Dietary

Materials," 5th International Workshop on Trace Element Analytical Chemistry in Medicine and

Biology, Neuherberg, FRG, April 16, 1988.

Iyengar, G.V. and Wolf, W.R., "Multi-Purpose Biological RMs," Third International Symposium on Biological

Reference Materials, Bayreuth, FRG, May 4, 1988.

Jassie, L.B. and Kingston, H.M., "Some Aspects of the Chemistry of Acid Dissolution in a Microwave

System," 30th QRNL-DOE Energy Technology Conference, Qctober, 20-22, 1987.

"The Development and use of Fast Microwave Acid Sample Decomposition for Elemental Analysis", Beijing

Conference and Exhibition on Instrumental Analysis, Beijing, Peoples Republic of China, Qctober

20, 1987. Invited

58
"Development of a computer-Controlled Robot System for Analytical Separations by Column

Chromatography", Beijing Conference and Exhibition on Instrumental Analysis, Beijing, Peoples

Republic of China, October 21 , 1987. Invited

"Microwave Energy for Sample Preparation", Shanghai Institute of Testing Technology, Shanghai, People’s

Republic of China, November 2, 1987. Invited

"Laboratory Robotics", Shanghai Institute of Testing Technology, Shanghai, People’s Republic of China,

November 2, 1987. Invited

"Microwave Assisted Digestive Techniques and Chemical Robotics," EPA EMSL - Cincinnati, Cincinnati,

OH, December 2, 1987. Invited

"Microwave Assisted Sampie Decomposition for Trace Analysis", Short course, 1988 Winter Conference

on Plasma Spectrochemistry, San Diego, CA, January 2, 1988. Invited

"Microwave Assisted Decomposition of Soils", part of a short course on Sampie Preparation at the 1988

winter conference on Plasma Spectro-chemistry, San Diego, CA, January 2, 1988. Invited

Panel Discussion: "Solving Difficult Problems with Microwave Assisted Sample Decomposition", 1988

Winter Conference on Plasma Spectrochemistry, San Diego, CA, January 6, 1988. Invited

"The Use of Microwave Technology for Sample Digestion and Preparation", Phillips Petroleum Company,

Bartlesville, OK, February 19, 1988. Invited

"Microwave Energy for Sample Preparation and Robotics for Analytical Analysis", Arco Oil and Gas

Company, Plano, TX, February 24, 1988. Invited

"Microwave Acid Sample Decomposition for Elemental Analysis", Pittsburgh Conference, New Orleans,

LA, February 26, 1988.

EPA Seminar: "Computer Controlled Laboratory Robotics and Microwave Sample Preparation", Las Vegas,

NV, April 4, 1988. Invited

Kingston, H.M. and Jassie, L.B., "Fundamental Relationships in Acid Decomposition of Environmental

Samples for Elemental Analysis using Microwave Energy," presented at the Symposium on

Microwave Processing of Materials, paper #M5.1, Reno, NV, April 5-8.

"High Temperature Microwave Sample Decomposition for Elemental Analysis", Materials Research

Society, Reno, NV, April 7, 1988. Invited

Kingston, H.M. and Jassie, L.B., "High Temperature and Pressure Acid Decomposition of Materials in a Microwave System," presented to a joint ASTM D-34 and D-1 9 committee meeting, Toronto, Ontario,

May 17, 1988.

"Fundamentals of Microwave Sample Preparation: With Practicum" Training Course of the Society for

German Chemists, No. 349/88, Sample Preparation for Trace Analysis for Trace Elements and

Radionuclides, Kernforschungsanlage, Centeral Department for Chemical Analysis, Julich GmbH,

West Germany, May 19, 1988. Invited

59
"Laboratory Robotics", Meeting of ERA Regional Laboratory Directors and Branch Chiefs, Mayflower Park

Hotel, Seattle, WA, June 14, 1988. Invited

"Microwave Sample Preparation for Environmental Testing". Meeting of EPA Regional Laboratory Directors

and Branch Chiefs, Mayflower Park Hotel, Seattle, WA, June 14, 1988. Invited

Kingston, H.M. and Jassie, LB. "Fundamental Relationships in Acid Decomposition of Environmental

Samples for Elemental Analysis Using Microwave Energy" EPA OSW Symposium on: Waste Testing

and Quality Assurance, Westin Hotel, Washington DC, July 13, 1988.

Koch, W.F., "Ion Chromatography: Trace Analysis," Department of Chemistry Distinguished Lecturer

Series, Drury College, Springfield, MO, December?, 1987. Invited

Koch, W.F., "Reference Materials for Sodium and Potassium: National Bureau of Standards Efforts,"

American Association for Clinical Chemistry, 40th National Meeting, New Orleans, LA., July 25, 1 988.

Invited

Koch, W.F., "Development of a Reference Material for ISE Measurements of Sodium and Potassium," 10th

Meeting of the European Working Group on Ion Selective Electrodes, Stresa, Italy, September 23,

1988. Invited

Koster, B.J., Wise, S.A., and Zeisler R.L, "Technical Improvements in the Operation of the U. S. National

Biomonitoring Specimen Bank Facility," 11th U.S. German Seminar of State and Planning on

Environmental Specimen Banking, Bayreuth, FRG, May 3, 1988. Invited

Lindstrom, R.M., "Analytical Standards and Silicon Analysis," International Energy Agency Consultants’

Meeting on the Need for Intercomparison and Reference Materials for Characterization of Silicon,

National Bureau of Standards, Gaithersburg, MD, October 2, 1987. Invited

Lindstrom, R.M., "Prompt-Gamma Activation Analysis," Test, Research, and Training Reactors Meeting,

National Bureau of Standards, Gaithersburg, MD, October 15, 1987. Invited

Lindstrom, R.M., "Cold Neutron Facility at the National Bureau of Standards," Department of Nuclear

Engineering, University of Illinois, Urbana, May 9, 1988. Invited

Lindstrom, R.M., "Analysis Using Neutron Beams at NBS," Environmental and Medical Sciences Division,

United Kingdom Atomic Energy Authority, Harwell, U.K., June 7, 1988. Invited

Lindstrom, R.M., "Measurement of Superconductor Stoichiometry by Prompt and Delayed Neutron

Activation," American Nuclear Society Annual Meeting, San Diego, CA, June 16, 1988.

Lindstrom, R.M., "Stoichiometry Measurement by Neutron Activation," Third NBS Superconductivity

Program Review, Boulder, CO, July 15, 1988.

Lindstrom, R.M., "Neutron Microprobe: Prospects and Potential Applications," Microbeam Analysis

Society - Electron Microscopy Society of America Joint Meeting Milwaukee, Wisconsin, August 10,

1988. Invited

60
Lindstrom, R.M., "Neutron Activation Analysis in Electronic Technology," Symposium on Diagnostic

Techniques for Semiconductor Materials and Devices, 174th Meeting of the Electrochemical

Society, Chicago, III., October 12, 1988. Invited

Lucatorto, T.B., Travis, J.C., Fassett, J.D., Clark, C.W., and Brown, L, "Enhanced Isotope Abundance

Sensitivity and Sample Utilization Efficiency in Pulsed RIMS," DOE Workshop on Advanced Laser

Technology for Chemical Measurements, NBS, Gaithersburg, MD, Novembers, 1987.

Marinenko, G., "Constant Current Coulometry - A Versatile High - Precision Titration Technique,"

International Symposium on Titration Techniques, Lund, Sweden, June 13, 1987. Invited

Mills, C.F., Golden, M., and Iyengar, G.V., "Trace Element Nutritional Problems in the Developing

Countries," International Conference on Trace Elements in the Developing Countries, Karachi,

Pakistan, February 6-10, 1987. Invited

Moody, J.R., Paulsen, P.J., Beary, E.S., and Bushee, D.S., "Inductively Coupled Plasma - Mass

Spectrometric Analysis of Ultrapure HF," 1st International Conference on Plasma Source Mass

Spectrometry Durham University, UK, September 1988.

Moody, J.R., Paulsen, P.J., Beary, E.S., and Bushee, D.S., "ICP-MS Analysis of Ultrapure HF," First

International conference on Plasma Source Mass Spectrometry; Durham Univ. England, September

1988.

Norris, J.A., "Major Minor and Trace Elemental Analysis as Seen by an Instrumentalist:, Iron and Steel

Chemists’ Association Annual Meeting, Pittsburg, PA, October 1987.

Palmieri, M. and Fritz, J.S., "Detection of Metal Ions by Liquid Chromatographic Separation of Their

1,3-Dimethyl-4-Acetyl-2-Pyrazolin-5-one Chelates," HPLC’88, Washington DC June 1988.

Paulsen, P.J., "Techniques for SSMS Isotope Dilution Analysis of Standard Reference Materials," Central

Bureau for Nuclear Measurements Commission of the European Communities, Geel, Belgium, July

1988. Invited

Paulsen, P.J., "ICP-MS Analysis of Trace Elements Using Isotope Dilution and/or External Standardization,"

Central Bureau for Nuclear Measurements Commission of the European Communities, Geel,

Belgium, July 1988. Invited

Paulsen, P.J., Moody, J.R., Beary, E.S.,and Bushee, D.S., "ICP-MS: Applicationtothe Analysis of Ultrapure

Acids," University of Maryland, Analytical Chemistry Seminar, College Park, MD, October 23, 1987.

Invited

Paulsen, P.J., Beary, E.S., and Bushee, D.S., "Stable Isotope Dilution Analysis of Oyster Tissue Using

ICP-MS," 11th International Mass Spectrometry Conference, Bordeaux, France, August 1988.

Rains, T.C., Paulsen, P.J., Beary, E.S., and Turk, G., "New Analytical Techniques for Fluoride Materials,"

Fiber Optics Conference, McLean, VA, March 1988.

Rains, T.C., Paulsen, P.J., Beary, E.S., Turk, G., and Ewing, K., "Purification and Analysis of Fluoride Raw

Materials at Sub ppb Levels,"

61
Rains, T.C., "The Art of Sample Preparation for Spectrochemical Analysis," FACSS Workshop, Detroit, Ml,

Octobers, 1987. Invited

Rains, T.C., "The Art of Sample Preparation," Beijing Reagent Chemical Institute, Beijing, China, October

15, 1987. Invited

Rains, T.C., "Chemical Interference in Atomic Absorption Spectrometry and Ways to Alleviate Them,"

Beijing Reagent Chemical Institute, Beijing, China, October 17, 1987. Invited

Rains, T.C., "New Innovation in AAS," Beijing Reagent Chemical Institute, Beijing China, October 17, 1987.

Invited

Rains, T.C. and Syty, A., "Determination of Trace Elements Species by HPLC/AAS in Environmental

Samples," 2nd Beijing Conference and Exhibition on Instruments Analysis, Beijing China, October

20, 1987.

Rains, T.C., "Research Atomic Absorption and Emission Spectrometry at NBS," National Spectroscopy

Society of China, Beijing, China, October 21, 1987. Invited

Rains, T.C., "Trace Analysis in Ultra Pure Materials," Beijing Reagent Chemical Institute, Beijing, China,

October 22, 1987.

Rains, T.C., "The Art of Sample Preparation" and "New Innovation in Atomic Spectroscopy," Northwest

Nonferrous Geological Institute, Xian, China, October 26, 1987. Invited

Rains, T.C., "Interference in Atomic Spectroscopy" and "Quality Assurance," Northwestern Nonferrous

Geological Institute, Xian, China, October 27, 1987. Invited

Rains, T.C., "The Art of Sample Preparation," Tong Ji University, Shanghai, China, October 28, 1 987. Invited

Rains, T.C., "Trace Element Determination by AAS and FES," Tong Ji University, Shanghai, China, October

29, 1987. Invited

Rains, T.C., "Interference in AAS," "Calibration of AAS Instrumentation," and "Quality Assurance in the

Analytical Laboratory," Tong Ji University, Shanghai, China, October 30, 1987. Invited

Rains, T.C., "The Art of Sample Preparation" and "Trace Elemental Analysis in Environmental Media,"

Shanghai Institute of Ceramics, Shanghai, China, October 31, 1987. Invited

Rains, T.C., "The Art of Sample Preparation," and "Trace Elemental Analysis in Environmental Media,"

Thongsham University, Guangzhon, China, November 2, 1987. Invited

Rains, T.C., "New Innovation in Atomic Spectroscopy," and "Why Quality Assurance," Thongshan

University, Guangzhon, China, Novembers, 1987. Invited

Rains, T.C. and Taylor, H.E., "Analytical Atomic Spectrometry: Absorption, Emission and Mass," ACS Short

Course, New Orleans, LA, February 19-21, 1988. Invited

Rains, T.C., "2nd Annual Trace Analysis for Environmental and Fuel Related Materials," Short Course,

Florida Power, Tampa, FL, March 18, 1988. Invited

62
Rains, T.C., "Art of Sample Preparation" and "Quality Assurance in the Modern Laboratory," Paffenbarger

Research Center, Bldg. 224, NBS, May 10, 1988. Invited

Rains, T.C., "Improved Precision and Accuracy in an Analyses by Electrothermal Atomic Absorption

Spectrometry," Gordon Research Conference on Analytical Chemistry, New Hampton School, NH,

August 12, 1988. Invited

Rains, T.C. and Taylor, H.E., "Analytical Atomic Spectrometry: Absorption, Emission and Mass," ACS Short

Course, Los Angeles, CA, September 23-25, 1988. Invited

Settle, F.A. and Pleva, M., "An Expert-Database System for Surface Analysis," Pittsburgh Conference, New

Orleans, LA February 25, 1988. Invited

Settle, F.A., "Applications of Expert Systems to Chemical Problems," University of North Carolina at Wilmington, Wilmington, NC, April 14, 1988.

Settle F.A. and Kingston, H.M., "An Expert System for Sample Preparation," Third Chemical Congress of

North America, Toronto, Canada, June 9, 1988.

Settle, F.A., Altman, L, McClintock, D., and Pleva M., "The Role of Expert Systems in Chemical Education,"

Third Chemical Congress of North America, Toronto, Canada, June 7, 1988.

Stone, S.F., Zeisler, R., and Gordon, G.E., "Quantitative Determination of Proteins Using Polyacrylamide

Gel Electrophoresis and Neutron Activation," 5th International Workshop on Trace Element

Analytical Chemistry in Medicine and Biology, Neuherberg, FRG, April 18, 1988.

Stone, S.F., Koster, B.J., and Zeisler, R., "Inorganic Analyses of Marine Specimens from the National

Oceanic and Atmospheric Administration’s National Status and Trends Program," 1 1 th U.S. German

Seminar of State and Planning on Environmental Specimen Banking, Bayreuth, FRG, May 2, 1988.

Invited

Stone, S.F., Zeisler, R., and Koster, B.J., "Neutron Activation Analysis of Major, Minor, and Trace Elements

in Marine Sediments," ANS Annual Meeting, San Diego, CA, June 16, 1988.

Tanner, J.T., Smith, J.S., Angyal, G., Defibaugh, P.W., Villalobos, M.C., Bueno, M. P., Iyengar, G. V., Wolf,

W. R., and Zeisler, R., "Organic Nutrient Standards," Accuracy in Trace Analysis, Accomplishments,

Goals, Challenges, NBS, Gaithersburg, September 28-October 1, 1987.

Travis, J., "Resonance Ionization Mass Spectrometry for Ultra-Sensitive Determination of Isotope Ratios,"

V. M. Goldschmidt Conference (Geochemical Society), Baltimore, MD, May 13, 1988.

Travis, J., "Developing the Ultimate Analytical Potential of Resonance Ionization Mass Spectrometry," 41 st Annual Summer Symposium on Analytical Chemistry, Stanford University, Palo Alto, CA, June 28,

1988.

Turk, G.C., Kingston, H.M., Epier, K.S., and O’Haver, T.C., "Applications of Laser-Enhanced Ionization

Spectroscopy," FACSS XIV, Detroit, Ml, Qctober 6, 1987.

Turk, G.C., "Tributyltin Measurements," EPA, Cincinnati, Qhio, December 2, 1987.

63
Turk, G.C., MacCrehan, W.A., Epier, K.S., and O’Haver, T.C., "Laser-Enhanced Ionization as an Element

Specific Detector for Liquid Chromatography, Fourth International Symposium on Resonance

Ionization Spectroscopy and Its Applications," Gaithersburg, MD, April 15, 1988.

Turk, G.C., "Fundamentals and Applications of Laser-Enhanced Ionization Spectroscopy,"

Vancouver/Victoria Section of the Spectroscopy Society of Canada, Vancouver, BC, Canada, April

18, 1988. Invited

Turk, G.C., "Applications of Laser-Enhanced Ionization Spectrometry," Eastern Analytical Symposium,

New York City, October 4, 1988. Invited

Turk, G.C., "Simultaneous Measurement of Laser-Indiced Fluorescence and Ionization," FACSS ’88’,

Boston, October 31, 1988.

Turk, G.C., "Fundamentals and Applications of Laser-Enhanced Ionization Spectroscopy," Pacific

Northwest Section of the Society for Applied Spectroscopy, Seattle, WA, April 19-20, 1988. Invited

Turk, G.C., "Fundamentals and Applications of Laser-Enhanced Ionization Spectroscopy," Intermountain

Section of the Society for Applied Spectroscopy, Idaho Falls, ID, April 21,1 988. Invited

Walker, R.J., Fassett, J.D., and Travis, J.C., "The Use of Resonance Ionization Mass Spectrometry for

Measuring the Isotopic Compositions of Rhenium and Osmium Extracted from Silicate Rocks," 4th

RIS Symposium, Gaithersburg, MD, April 15, 1988.

Watters, R.L, Jr., Shen, F.H., Newbury, D.E., and Small, J.A., "The Chemical Characterization of Spark

Erosion and Spark-Produced Metal Aerosols," Fourteenth Meeting of the Federation of Analytical

Spectroscopy Societies, Paper 325, October 5, 1987, Detroit, Ml.

Woittiez, J.R.W. and Iyengar, G.V., "Trace Elements in Human Clinical Specimens: An Evaluation of

Literature Data to Identify Reference Values," 5th International Workshop on Trace Element

Analytical Chemistry in Medicine and Biology, Neuherberg, FRG, April 15, 1988.

Woittiez, J.R.W. and Iyengar, G.V., "The Use of NAA in Dietary RM Analysis," Third International Symposium

on Biological Reference Materials, Bayreuth, FRG, May 6, 1988.

Wolf, W.R. and Iyengar, G.V., "Mixed Diet RMsfor Nutrient Analysis: Preparation of SRM 1548 Total Diet,"

Third International Symposium on Biological Reference Materials, Bayreuth, FRG, May 6, 1988.

Zeisler, R., Iyengar, G.V., Tanner, J.T., and Wolf, W.R., "Development of Multi-Purpose Reference

Materials," Symposium on Accuracy in Trace Analysis - Accomplishments, Goals, Challenges,

Gaithersburg, MD, September 29, 1987.

Zeisler, R. and Becker, D.A., "Determination of Zinc in a Monel Alloy by Compton Suppression

Spectrometry," ANS Winter Meeting, Los Angeles, CA, November 16, 1987. Invited

Zeisler, R. and Greenberg, R.R., "Determination of Baseline Platinum Levels in Biological Materials," 5th

International Workshop on Trace Element Analytical Chemistry in Medicine and Biology,

Neuherberg, FRG, April 15, 1988.

64
Zeisler, R., Stone, S.F., Greenberg, R.R., and Sullivan, T.M., "Reanalysis of Banked Human Liver Samples

for the Determination of Inorganic Constituents," 11th U.S. German Seminar of State and Planning

on Environmental Specimen Banking, Bayreuth, FRG, May 2, 1988. Invited

Zeisler, R., Iyengar, G.V., Tanner, J.R., and Wolf, W.R., "Specimen Banking of U.S. Mixed Total Diets," 11th

U.S. German Seminar of State and Planning on Environmental Specimen Banking, Bayreuth, FRG,

May 2, 1988. Invited

Zeisler, R. and Wise, S.A., "Long Term Sample Stability -The Key to Specimen Banking," 1 1th U.S. German

Seminar of State and Planning on Environmental Specimen Banking, Bayreuth, FRG, May 3, 1988.

Invited

Zeisler, R., Greenberg, R.R., Stone, S.F. and Sullivan, T.M., "Studies on the Long Term Stability of Biological

Materials for Trace Elements," Third International Symposium on Biological Reference Materials,

Bayreuth, FRG, May 5, 1988.

Zeisler, R., Greenberg, R.R., Stone, S.F., Sullivan, T.M., "Selenium Determinations for the Assessment of

Sample Stability in Specimen Banking," ANS Annual Meeting, San Diego, CA, June 1 4, 1 988. Invited

3. Committee Assignments

I. Lynus Barnes

Department of Health and Human Resources, Chemistry Task Force of the National

Shellfish Sanitation Program

International Union of Pure and Applied Chemistry,

Commission on Atomic Weights and Isotopic Abundances

Chairman, lUPAC Sub-commission on Isotopic Abundance Measurements

Vice-Chairman, Washington Editorial Review Board

Donald A. Becker

ASTM E-10, Nuclear Technology and Applications

ASTM E-10.05, Nuclear Radiation Metrology

ASTM E-1 0.05.02, Radionuclide Metrology

ASTM E-1 0.05.08, Nuclear Environmental Metrology

ASTM E-1 0.05. 10, Neutron Metrology

ASTM D-19, Water

ASTM D-19.01, Statistical Methods

ASTM D-19.02, General Specification and Technical Resources

ASTM D-19.03, Sampling of Water and Water-Formed Deposits, and Surveillance of Water

ASTM D-19.04, Methods of Radiochemical Analysis

ASTM D-19.05, Inorganic Constituents in Water

ASTM D-19.07, Sediments

Chairman, ASTM E-1 0.05. 12, Task Group on Nuclear Methods of Chemical Analysis

ANS, Trace Element Analysis Committee, Biology and Medicine Division

ANS, Activation Analysis Committee, Isotopes and Radiation Division

M. James Blackman

Smithsonian Institution;

Materials Analysis Academic Program Committee

SARCAR Advisory Committee

65
Extramural Committees:

ASTM E-10.05.12, Task Group on Nuclear Methods of Chemical Analysis

Barry I. Diamondstone

ASTM E-03, Chemical Analysis of Metals

ASTM E-03.1, Ferrous Metals

ASTM E-03.95, Long-Range Planning

ASTM E-03.97, Meetings and Arrangements

ASTM D-34, Waste Disposal

R. Gregory Downing

ASTM E-10.05, Nuclear Methods for Chemical Analysis

ASTM F-01 .1 1 , Task Group on Alpha Particle Induced Soft Errors

Center for Analytical Chemistry Colloquium Committee

Inorganic Analytical Research Division Seminar Committee

Organizer and Session Chairman, "Material Characterization Using Neutron Depth Profiling,"

American Nuclear Society, 1987 Winter Meeting Los Angeles, CA

Michael S. Epstein

ASTM D-19, Water

Advisory Board of Analytical Chemistry (1988-1990)

Course Director, Society of Applied Spectroscopy Course on "Successful Atomic Spectrometric

Determinations"

Federation on Analytical Chemistry and Spectroscopy Societies (FACSS-89) Program Committee

Chairman-Elect, Nominating Committee, Society for Applied Spectroscopy (SAS)

Chairman, Outstanding Award Committee, Balitmore-Washington Section of SAS

Ronald F. Fleming

ASTM E-10.05, Nuclear Radiation Metrology

ASTM E-10.07, Radiation Effects on Materials

NSERC Visiting Committee on the McMaster Nuclear Reactor

Robert R. Greenberg

ASTM E-10.05, Nuclear Radiation Metrology

NIST Chemistry Storeroom Committee

ANS, Trace Analysis Committee, Division of Biology and Medicine

Secretary/Treasurer, ANS, Division of Biology and Medicine

G. V. Iyengar

International Commission on Radiological Protection, Task Group on Reference Man

International Union of Pure and Applied Chemistry, Subcommittee on Risk Assessment (SORA)

International Union of Pure and Applied Chemistry, SORA Coordinator for Working Group on

Selenium

International Union of Pure and Applied Chemistry, Sub-committee on Quality Assurance and

Harmonization

International Scientific Committee, Modern Trends in Activation Analysis

Editorial Board, Science of the Total Environment (U.K.)

Advisory Board, Food Laboratory News Letter (Sweden)

66
Howard M. Kingston

ASTM C-26.05, Methods of Test

ASTM C-26.07, Waste Materials

lUPAC, Analytical Chemistry Division, Commission V.3, Analytical Nomenclature

Session Chairman, Eastern Analytical Symposium on Microwave Technology

Technical Consultant, Congressional Science and Technology Committee

Chairman, Inorganic Analytical Research Division Seminar Committee

William F. Koch

ASTM D-19, Water

ASTM D-19.02, General Specifications and Technical Resources

ASTM D-19.05, Inorganic Constituents in Water

ASTM D-22, Air

ASTM D-22.06, Atmospheric Deposition

Chairman, ASTM D-22. 06.03, Task Group on pH

NIST Child Care Association

National Committee for Clinical Laboratory Standards

American Water Works Association

John K. Langland

Chairman, NBS Electronics Storeroom Committee

Richard M. Lindstrom

NIST Reactor Safety Evaluation Committee

Co-Organizer and Chairman, IAEA Workshop on "The Need for Intercomparison and Reference

Materials for Characterization of Silicon," Gaithersburg, October 1988.

Lawrence A. Machlan

ASTM C-26, Nuclear Materials

ASTM C-26.01, Editorial

ASTM C-26.05, Analytical Methods

George Marinenko

The National Capital Section of the Electrochemical Society Counselor, 88/89

ASTM, Committee D-19 Water, Voltammetry Task Group

Chairman, ASTM, Redox Potential Task Group, 1981/88

Chairman, ASTM, pH in Saline Water Task Group, 1981/88

Chairman, ASTM, Chlorine Residuals Task Group, 1981/88

John R. Moody

ASTM D-19, Water

ASTM D-19.05, Inorganic Constitutents in Water

American Chemical Society Committee on Analytical Reagents

John A. Norris

1st Vice Chairman ASTM E-02, Emission Spectroscopy

ASTM E-02. 01, Fundamental Practices

ASTM E-02. 02, Statistics

ASTM E-02. 04, Sampling and Standards

ASTM E-02. 05, Copper, Cobalt, Nickel, and High Temperature

67
ASTM E-02.06, Lead, Tin, Zinc

ASTM E-02.07, Aluminum

ASTM E-02.08, Refractory Metals

ASTM E-02.09, Ferrous

ASTM E-02.13, Terminology

Consultant-Chemists Committee-American Iron and Steel Institute

Kenneth W. Pratt

NIST Research Information Center, Div. 551 Subject Specialist

Inorganic Analytical Research Division Seminar Committee

Division 551 Lunch Bunch organizer, Jan-May 1988

Division 551 High Purity Reagents Committee

Margo D. Palmieri

Washington Chromatography Discussion Group

Theodore C. Rains

Proposal Evaluation Committee for National Science Foundation

Editorial Board of Annual Reports on Analytical Atomic Spectroscopy (The Chemical Society of

London) and the Canadian Journal of Spectroscopy, and the Journal of Analtyical Atomic

Spectrometry

Subcommittee No. 6 on Methods of Air Sampling and Analysis

ASTM E-02.10, Non-Metallic Materials

ASTM E-02.13, Nomenclature

ASTM D-19, Water

NIH Proposal Evaluation Committee for Instrumentation

Past-Chairman, FACSS Governing Board

Professor-in-Charge, ACS Short Course on Atomic Absorption and Plasma Emission

Spectroscopy

Column Editor, Journal of Applied Spectroscopy

Chairman, International Organization for Standardization, Technical Committee 17

Convener of ISO/TC 17/SCl, WG16, Steel and Iron - Determination of Manganese Content - Flame

Atomic Absorption Spectrometry

Theresa A. Rush

Inorganic Analytical Research Division Safety Committee

Frank A. Settle

Advisory Board, Journal of Chemical Information and Computer Sciences

Editor of the "Chemical Instrumentation" feature for the Journal of Chemical Education

John C. Travis

Recording Secretary, Research Advisory Committee, NIST

Gregory C. Turk

Editorial Board, Atomic Spectrometry Updates

Local Organizing Committee, 4th International Symposium on Resonance Ionization Spectroscopy

and It’s Applications

Section Chairman, FACSS Program Committee

Inorganic Analytical Research Division Seminar Committee

68
Thomas W. Vetter

ASTM E-03, Chemical Analysis of Metals

ASTM E-03.01, Ferrous

ASTM E-03.91, Editorial

ASTM E-03.92, Standards

Robert L. Watters, Jr. ASTM E-03, Chemical Analysis of Metals

ASTM E-03.01, Ferrous

Yung-Chi Wu

ASTM D-19 Water

Rolf Zeisler

NIST Reactor Safety Evaluation Committee

Chairman, Trace Element Analysis Committee, Technical Group for Biology and Medicine, American

Nuclear Society

CAC Quality Assurance Committee

General Chairman, International Conference on Nuclear Analytical Methods in the Life Sciences

International Committee on Nuclear Analytical Methods in the Life Sciences

4. Other

a. Seminars

October 8, 1987

Dr. Biserka Raspor, Center for Marine Research, Rudjer Boskovic Institute, Zagreb, Yugoslavia,

"Cadmium Induced Proteins from Mytilus Galloprovincialia - A Possible Biological Reference

Material for Environmental Analysis". (Division Sponsor: W. F. Koch)

October 8, 1987

Dr. Subrahmanyam Gangadaharan, Bhahba Atomic Research Center, Bombay, India, "Potential

Applications of Neutron Beams at BARC". (Division Sponsor: R. G. Downing)

October 19, 1987

Dr. Halina Rubinsztein-Dunlop, Department of Physics, Chalmers University of Technology,

Gothenburg, Sweden, "Laser Enhanced Ionization Spectrometry in Analytical Flames and

Furnaces". (Division Sponsor: J.C. Travis)

November 19, 1987

Ms. Theresa M. Sullivan, Department of Chemistry, University of Maryland, College Park, MD, "Ko

Method of Analysis: Data and Results". (Division Sponsor: R. F. Fleming)

November 19, 1987

Dr. Robert L. Kay, Department of Chemistry, Carnegie-Mellon University, Pittsburgh, PA,

"Electroanalytical Research". (Division Sponsor: W. F. Koch)

69
December 4, 1987

Dr. Richard L McCreery, Chemistry Department, Ohio State University, Columbus, OH, "Novel

Spectroscopic and Electroanalytical Techniques for Trace Analysis: Fiber. Optic Raman

Spectroscopy and Double Modulated Electrochemistry". (Division Sponsor: K. W. Pratt)

December 7, 1987

Dr. David M. Coleman, Department of Chemistry, Wayne State University, Detroit, Ml, " Segregated

Sampling and Excitation". (Division Sponsor: R. L. Watters, Jr.)

January 12, 1988

Dr. Viliam Krivan, University of Ulm, Ulm, West Germany, "High Purity Analysis of Semiconductor

Materials". (Division Sponsor: R. G. Downing)

January 22, 1988

Dr. Vincent P. Guinn, Department of Chemistry, University of California, Irvine, CA, "Short-lived

Isotopes in NAA: Analysis of Flourine and Use of the Advance Prediction Computer Program".

(Division Sponsor: D. A. Becker)

March 8, 1988

Ms. Theresa M. Sullivan, Department of Chemistry, University of Maryland, College Park, MD,

"Monitor Neutron Activation Analysis Applied to Superconductor Materials". (Division Sponsor: R. G. Downing)

March 21, 1988

Dr. M. Tezer Esat, Research School of Physical Sciences, Department of Nuclear Physics, Australian

National University, Canberra, Australia, "Physico-Chemical Isotope Anomalies: Cr". (Division

Sponsor: I. L. Barnes)

March 28, 1988

Dr. Kurt V. Irgolic, Department of Chemistry, Texas A&M University, College Station, TX, "The

Speciation of Arsenic Compounds in Biological Tissues". (Division Sponsor: H. M. Kingston)

April 20, 1988

Dr. Muhammad Arif, Research Reactor, University of Missouri at Columbia, Mo, "Analytical

Applications of Focused Neutrons". (Division Sponsor: R. G. Downing)

April 22, 1988

Dr. Ira Krull, Chemistry Department, Northeastern University, Boston, MA, "New Analytical

Approaches for the Determination and Speciation of Volatile Organomercury and Organotin

Species". (Division Sponsor: H. M. Kingston)

April 29, 1988

Dr. Yaoqi Zhou, Department of Chemistry, SUNY at Stony Brook, NY, "pH and Absolute EMF Scale".

(Division Sponsor: Y. C. Wu)

June 10, 1988

Dr. Anne P.Thorne, Blackett Laboratory, Imperial College of Science and Technology, London,

England, "High Resolution Spectroscopy in the Ultraviolet with a Fourier Transform Spectrometer".

(Division Sponsor: R. L. Watters, Jr.)

70
June 22, 1988

Dr. Helmut Kaiser, Missouri University Research Reactor, Columbia, MO, "Neutron Interferometry

and Its Applications and Some Ideas of Focussing a Neutron Beam". (Division Sponsor: R. G.

Downing)

June 24, 1988

Professor Harold L. Friedman, Chemistry Department, SUNY at Stony Brook, NY, "New Electrolyte

Limiting Law". (Division Sponsor; W. F. Koch)

June 24, 1988

Dr. Franz Lux, Institute for Radiochemistry, Technical University of Munich, Garching, Federai

Republic of Germany, "Application of Neutron Activation Analysis in the Development of Anticancer

Drugs". (Division Sponsor: R. L Zeisler)

July 26, 1988

Professor Chai Chifang, Institute of High Energy Physics, Academia Sinica, Beijing, People’s

Republic of China, "Present Status of Nuclear Activation Analysis in China". (Division Sponsor: R.

L. Zeisler)

August 5, 1988

Dr. Jerry D. Messman, Research Chemist, Columbus, Ohio, "Applications of Atomic Spectrometry

in a Contract Research Environment." (Division Sponsor; R. L. Watters, Jr.)

b. Conference Sponsored

October 2, 1987

G. Venkatesh Iyengar, International Workshop on Practical Analytical Approaches to the

Assessment of Humna Dietary Intake of Nutrients, Toxic Constituents and Radioisotopes, National

Bureau of Standards

October 2, 1987

Richard M. Lindstrom, Workshop on Silicon Characterization, National Bureau of Standards.

November 1987

R. Gregory Downing, Workshop on Neutron Depth Profiling for the American Nuclear Society, Los

Angeles, CA.

71
III. Organic Analytical Research Division

Willie E. May, Chief

Michael J. Welch, Deputy Chief

A. Division Overview

The Organic Analytical Research Division conducts research to develop and improve techniques for the

preparation, purification, and analysis of organic compounds and uses these techniques in the solution of

problems related to national needs. The Division’s research is carried out in five groups that are organized

along functional lines: (1 ) Bioanalytical Techniques, the activities of which are directed toward development

and refinement of methods for the separation and characterization of proteins and other biomolecules,

multivariate analysis of two-dimensional electrophoretic protein patterns, and the characterization of

reference compounds using nuclear magnetic resonance, polarimetry, and fluorescence: (2), Analytical

Sensors, the activities of which focus on the development of novel electrochemical methods for the selective

and sensitive detection of organic and organometallic species in liquid chromatographic effluents,

development of detectors based on thin-film planar waveguide and thermal lensing/deflection approaches,

characterization of electrode surfaces modified with polymer-immobilized organometal catalysts, modelling

of the transport processes within polymer films and viscous polyelectrolytes, use of Immunochemical

reactions to provide selectivity for the detection of biomolecules, and development of a generic

liposome-based flow injection immunoassay system (3) Liquid Chromatography, which involves research

focussed on gaining a better understanding of the mechanisms responsible for retention and selectivity in reversed-phase liquid chromatography, development of selective detection systems and multidimensional

chromatographic approaches for the analysis of individual compounds in environmental, clinical, and

food/nutritional samples; (4) Gas Chromatography, which conducts research in high resolution gas and

supercritical fluid chromatography, multidimensional gas chromatography, advanced sample preparation

techniques (e.g., solid phase and supercritical fluid extraction), and computerized automation of

Immunochemical reactions to provide selectivity for the detection of biomolecules; and (5) Mass

Spectrometry, the research of which involves development and use of definitive methods of analysis for

clinically important analytes, collision induced dissociation of ions for structure determination, and a variety

of mass spectrometric techniques (including thermospray LC/MS) for the quantitation of organic analytes in complex mixtures.

The Division responds to the measurement and standards needs of industry, other government agencies

(federal, state, and local), public and private sector institutions and associations, and other research

organizations within the National Institute of Standards and Technology. Research efforts in the Division

have resulted in the 43 technical articles being published or in press. Division scientists presented 57 talks

at technical meetings and conferences during FY88.

During the past year, approximately 50% of our efforts were directed toward research In organic analytical

chemistry, another 10% of our research and measurement program provided support to the NIST Standard

Reference Materials program, and the remainder of our efforts were in support of other agency programs

and to a limited degree, short-term projects performed on a service analysis basis.

A large portion of the Division’s support for research (- 42%) is provided through four "Competence Building"

programs. In 1977, the Office of Management and Budget (0MB) recommended, and Congress, approved,

$2M for NBS to develop technical competence in various measurement disciplines in support of the core

mission and long-range goals. Two of our four Competence programs, "Organic Electrochemistry" and

"Protein Stabilization and Characterization" have been ongoing for more than five years and will cease to

have Competence funds in FY89. Our program in Organic Mass Spectrometry was evaluated two years ago

72
and will continue this year. Our "Bioanalytical Sensors" Competence Program, is entering it’s fourth year.

The excellent progress that is being made in this program is described in detail in the Technical Activities

and in the Analytical Sensors Group Overview.

The accomplishments made in our Competence and STRS supported research programs will be described

in the Group Overviews that follow. There are, however, two major research accomplishments that merit

mention here as well. Results from a joint research project conducted in our Liquid Chromatography and

Mass Spectrometry Groups demonstrated the potential accuracy and precision of quantitative trace organic

measurements using thermospray LC/MS and thermospray LC/MS/MS in conjunction with isotope dilution

techniques. We were able to quantify uric acid in our "Human Serum" SRM (909) with an imprecision of ±1 %

using a simple protein precipitation followed by direct injection of the resulting supernate on a reversed-phase LC column. The results of both the LC/MS and LC/MS/MS experiments agreed with the

certified value (81 ppm) to within 1%. Additional details concerning this activity can be found in Technical

Activity No. 2. The Gas Chromatography Group has developed a multidimensional GC system that provides

resolution never before attained for PCB congeners. This system is based on the on-line coupling of columns

that separate RGB’s based on volatility and molecular shape respectively. Many of the important congeners

coelute on conventional GC columns and have identical mass spectra, thereby eliminating the possibility of

definitive determination by mass spectrometry. The multidimensional system provides the capability for

unambiguous identification and a means for quantitation of environmentally significant PCB congeners.

Further information concerning this research effort can be found in Technical Activity No. 8.

Our longstanding programs with the National Cancer Institute (NCI), National Oceanic and Atmospheric

Administration (NOAA), Environmental Protection Agency (EPA) and the Department of Energy (DoE) have

continued. A new multi-year program with the Department of Defense (DoD) is being established and an

effort with the U.S. Department of Agriculture (USDA) initiated in FY86 has resumed. Specific research efforts

in support of these other federal agency programs were: serving as the Ouality Assurance Center and

Reference Laboratory 1) for a network of NCI grantee laboratories that measure blood levels of vitamins A,

C, E, and beta-carotene as part of the process of investigating their efficacy as cancer chemopreventive

agents and 2) in a pilot effort to determine the efficacy of the use of two-dimensional electrophoresis with

computer image analysis in protein modulation studies of human colon tumor cells; developing SRMs,

providing specimen banking support, and serving as the reference laboratory for contractors of the NOAA

Oceans Assessment Division involved in the National Status and Trends Monitoring program; providing

reference materials and analyses for establishing NIST benchmark values for EPA quality control and

proficiency testing samples for EPA EMSL Laboratories at Cincinnati and Las Vegas; establishing a program

for the provision of reference materials to support the measurement of DNA-adducts of toxic organic species

in body fluids; providing QA services for the Army demilitarization of chemical agents program and

development of procedures for the immobilization of biomolecules on nylon and fiber optic supports. Our

program with the USDA involves the critical evaluation of the proposed "o-tyrosine method" for performing

post-irradiation dosimetry on meats and poultry. Further discussion of many of these activities follow in the

Group Overviews and Technical Activities.

We have continued our active support of the NIST Standard Reference Materials (SRM) program. Our direct

funding for SRM related activities continues to represent approximately 10% of our budget. However,

reference materials related activities and research on matrix stability constitute a much larger portion of our

total research and measurement efforts within the Division. Over the past ten years, the number of SRMs

certified for organic constituents has increased from ten pure crystalline materials to more than fifty materials

that include instrument calibration and performance materials, as well as clinical, environmental and

food/nutritional matrices with certified values for trace organic constituents. Nineteen SRMs have been

certified during the past two years. Among these SRMs was the first of a series of Drugs of Abuse in Urine

SRMs and two Cholesterol in Serum materials. SRM 1507 contains the primary urinary metabolite of

73
marijuana at a concentration of - 20 ng/mL upon reconstitution of the freeze-dried urine matrix. This SRM

will provide an accuracy benchmark for the drug monitoring community. SRMs 1951 and 1952 are each

comprised of three serum pools with certified levels of total cholesterol. SRM 1951 is being issued as a frozen

liquid and SRM 1952 is a freeze-dried serum. These materials will directly assist manufacturers and clinical

laboratories in improving the accuracy of cholesterol determinations. Improved accuracy will result in better

and more cost-effective health care for the public. Details concerning the Division’s other R'SS SRM activities are provided in the Group Overviews and Technical Activities that follow.

The following SRM projects are in progress and should be completed during the coming year: the

certification of a Cocaine in Urine SRM in collaboration with the College of American Pathologists; the

development of a vitamins in serum SRM in collaboration with NCI; the development of a marine sediment

and a marine tissue SRM, each having certified values for selected PAH, pesticides, and PCB congeners in collaboration with NOAA; hexane/isooctane-based calibration solution SRMs for PAH, pesticides, and PCB

congeners; development of a Diesel Particulate SRM for Bloassay in collaboration with EPA and the World

Health Organization; providing values for selected organic nutrients and clinically significant compounds in a Mixed Diet reference material.

Research efforts in the Division continue to be bolstered by the contributions of a number of Guest Scientists

(8), Research Associates (4), and high school, undergraduate and graduate students (5). Their individual

contributions to specific programs are described in the Group Overviews and Technical Activity 4.

The overall objective of our research program continues to be directed toward the refinement of existing,

and development of new, approaches to performing accurate and precise determinations of both macro and

micro quantities of organic constituents in a wide variety of matrices. In that regard, significant progress was

achieved in all five of the research thrusts identified for Pi'88:

(1 ) to commence the evaluation of the uniformity of Immune-response on immune-mediated lysis

of liposomes to release marker compounds for a variety of antibody-antigen reactions, and to

optimize silanizatlon reaction conditions for the derivatization of glass beads to be used In the

immunoreactor column of the associated flow-injection based biosensor devices; (see

Analytical Sensors Group overview and the Technical Activity 2)

(2) to develop a liquid chromatography-laser enhanced ionization method for the determination of

alkyl tin species in extracts from environmental samples; (see Analytical Sensors Group

Overview)

(3) to evaluate the accuracy and precision provided by isotope dilution thermospray LC/MS;

(mentioned previously, also see MS Group Overview)

(4) to evaluate the use of supercritical fluid chromatography for the separation of non-chlorinated

pesticides; (see GO Group overview and the Technical Activities)

(5) to develop chromatographic and electrophoretic techniques for the separation and quantitation

of biomolecules In complex mixtures and for the isolation of milligram quantities of pure

proteins. (See Bioanalytical Techniques Group Oven/iew).

Research thrust areas for the coming year are discussed in detail in the Group Overviews that follow. Our

most pressing staffing need is a mass spectrometrist with trace organic analytical experience, to fill the void

created by the loss of two Ph.D. level staff. We also are Interested in attracting a spectroscopist with

experience in GO- and LC-FTIR.

74
1 . Bioanalytical Techniques Group: Overview

The activities of the Bioanalytical Techniques Group are directed primarily towards (1 ) developing means for

separating and characterizing proteins, peptides, and other biomolecules to address standards needs in biotechnology, (2) developing nucleic acid standard materials, (3) performing of research in high-field nuclear

magnetic resonance spectroscopy, and (4) investigating of the use of immunochemical reactions to provide

selectivity for the detection of biomolecules.

Research efforts with proteins and peptides have been focused on improving ultra-sensitive methods for

protein separation, visualization, and Identification. We have continued to apply our capabilities for protein

separation and identification to specific problem areas. We have become proficient In the use of the Visage imaging system for two-dimensional electrophoresis and

have now upgraded our imaging capabilities by the procurement of a CCD camera capable of providing

resolution of about 1 75 micrometers per pixel. Enhanced hardware and software are providing the capability

of imaging and processing many more two-dimensional gels per day than was previously possible with the

older system.

In work designed to enhance capabilities for NMR analysis of complex biomolecules, a number of new

two-dimensional (2D) spectrum editing methods have been explored during the past year. In extension of

previous work on two-dimensional POMMIE (POMMIE = Ehase Oscillations to MaxiMIze Editing)

il(CH) -resolved ^^C NMR spectrum editing, we have Investigated the feasibility and limitations of 2D POMMIE

pulse sequences for the separation of carbon-proton chemical shift correlation ^^C NMR spectra into CH,

CH2, and CH3 subspectra (2D spectrum editing). The purpose of these experiments is to simplify the 2D

NMR spectra of complex molecules, thus facilitating spectral interpretation, assignment, and the separation

of overlapped peaks. Selected carbohydrate, macrolide antibiotic, and tri- and tetra-peptide derivatives

have been used as model compounds In these studies. By this means, very good 2D carbon-proton

chemical shift correlated CH and CH3 subspectra could be obtained, but, for typical carbohydrate and

peptide derivatives, the generation of good CH2 subspectra was more difficult. Based on our results, a

number of strategies for refinement of 2D POMMIE spectral editing have been investigated, including

consideration of factors Involved in both data acquisition and processing. The use of these methods, either

alone or in combination, has generally yielded 2D POMMIE subspectra of better quality, for both

J(CH)-resolved and carbon-proton shift correlation techniques.

We are continuing to work on developing capabilities for enzyme and other protein immobilization by

solid-phase binding with novel binding "spacer-arm" chemistries. We have continued our studies with the

Army in evaluating long-term stability of enzymes bound on glass fibers. This work was presented at a

meeting in Aberdeen, MD in April 1988, and a paper is now being completed for publication.

We have continued to concentrate some of our efforts on characterizing protein structure. As a probe

molecule, we are establishing the three-dimensional structures of the chelated and non-chelated forms of

pyoverdine Pf244. This fluorescent siderophore, produced by growing Pseudomonas fluorescens 244 in an

iron-poor medium, has been isolated and purified (>200 mg total yield) and analyzed for amino acid content

using phenylisothiocyanate derivatization and HPLC analysis. Structure determination has started by the

completion of baseline one-dimensional NMR experiments on the de-ferrated peptide and on the peptide

chelated with gallium. Homo- and heteronuclear two-dimensional NMR techniques also have been initiated.

A second objective in this program Is to establish the binding site of the siderophore of interest for the tri-butyl

tin cation. Two-dimensional proton NMR spectroscopy methods (COSY, SECSY, NOESY) will establish the

primary and secondary structures. Heteronuclear NMR analysis of ^®N-labeled (produced biosynthetically)

75
and (natural abundance) material will be used to refine PMR-based assignments and to establish the

conformational dynamics in molecules.

Research in carbohydrate-protein interactions is proceeding through the detailed examination of the

chemical specificity that occurs In the heparin-fibronectin system. This information will help in understanding

the role of complex carbohydrate binding to protein sequences and the implication in recognition and control

processes within cells and their environment. Such work includes 1 ) separation of fragments of heparin and

fibronectin by HPLC and electrophoresis, 2) structural analysis by NMR and mass spectrometry, and 3)

analysis of binding by equilibrium dialysis and spectral perturbation. Studies on the interaction of heparin

with fibronectin have been performed in collaboration with K. Ingham and S. Brew at the American Red Cross

Biomedical Research and Development Laboratory, Rockville, MD. These studies have characterized the

stoichiometry and affinity of heparin binding to fibronectin and the isolated domains of fibronectin.

Subsequent studies are aimed at determining the specific sulfate groups on heparin and the specific peptide

sequence within the heparin binding domains of fibronectin that are required for this interaction. In addition,

thermodynamic studies of heparin interaction with fibronectin have been performed in collaboration with F. Schwarz of the Chemical Thermodynamics Division. Preliminary studies show large changes in the

cooperativity of the temperature-induced unfolding transition in fibronectin in the presence and absence of

heparin. This indicates that conformational changes in the protein are induced by heparin binding. Further

studies are aimed at determining specific interactions of heparin with the isolated domains of fibronectin.

As part of our QA efforts with the National Cancer Institute, serum-based control materials for retinol,

a-tocopherol, and beta-carotene have been prepared and tested routinely to study the effects of storage

time and temperature. In addition, these sera have been very useful in interlaboratory studies to measure

the beneficial effects of value assigned reference materials on the quality of measurements. A graphical

reporting procedure has been developed that greatly facilitates interpretation of data.

High performance liquid chromatographic techniques were extended from protein and peptide separations

to nucleic acids and high molecular weight DNA fragments. Our diode-array HPLC system has been

upgraded by the addition of new software and hardware. We now have the capability of performing amino

acid analysis by use of the phenylisothiocyanate derivatization procedure. This enhances the sensitivity and

reproducibility of our amino acid studies.

During the past year, a new system for DNA electrophoresis has been obtained and is operating successfully.

The unit is based on a technique termed 'Transverse Alternating Field Electrophoresis" and allows the

separation of DNA up to several million base pairs. We have separated yeast chromosomal materials and

are using the system to monitor the size and quality of DNA to which various adducts will be attached. These

materials are being prepared for contract laboratories of the Department of Energy.

We have also successfully set up and operated a system for preparative isoelectric focusing. Using the

technique, we are preparing purified fractions of selected proteins for use as two-dimensional electrophoretic

markers. This work was necessary because none of the protein markers currently available from commercial

sources are sufficiently pure for standards work.

For the upcoming three years, planning details for the various programs in the Bioanalytical Techniques

Group include:

(1) Separating and characterizing proteins, peptides, and other biomolecules; a) investigate

analytical methods which are able to detect proteins and peptides at the sub-nanogram level:

develop mass spectrometric methods for probing peptide structure: improve techniques for

neutron activation of metal-binding proteins: b) provide standards to the research community

76
that utilizes separation methods for analytical studies of proteins and peptides: c) continue

research on interactions of selected proteins with chemically modified supports: continue with

hydrophilic supports and extend to mixed-bed supports: selectively immobilize enzymes on

hydrophilic beads and other supports to improve stability: improve silver staining procedures

by understanding interactions of metals with proteins: investigate "spacer-arm" binding to

selected polymeric materials: d) develop database capabilities with imaging of two-dimensional

electrophoresis: e) study the interactions of immobilized proteins on surfaces through use of

Diffuse Reflectance Infrared Detection: and f) develop capabilities in Capillary Zone

Electrophoresis.

(2) High-field NMR Spectroscopy: a) develop optimal pulse sequences for NMR studies of peptide

structures: b) continue to develop expertise in structural studies of biomolecules.

(3) Protein stabilization: a) immobilize enzymes and antibodies for specific applications In biosensor methodology.

(4) DMA Adducts: develop materials to be used in a quality assurance program for the Department

of Energy and as potential reference materials.

This coming year we will be joined by an NRC post-doctoral researcher, Ms. Edith Grabbe, who is completing

her Ph.D. work at the University of North Carolina and will be joining us at the end of the year. Her proposed

work will be focused on mechanisms of enzyme and protein immobilization to surfaces.

Dennis J. Reeder, Group Leader: Donald Atha, Bruce Coxon, Jesse J. Edwards, Alex J. Fatiadi, Diane K. Hancock, Margaret C. Kline, Millard Maienthal, Kristy L. Richie, Robert Schaffer, P. V. Sundaram,

2. Analytical Sensors Group: Overview

While this Group has historically focused on electroanalytical methods, optical methods have taken on a

more significant role in our activities. The principal areas of ongoing research include: 1) development of

novel-methods for selective/sensitive electrochemical detection in liquid chromatography, 2) characterization

of electrode surfaces modified with polymer-immobilized organometal catalysts, 3) modeling of transport

processes within polymer films and viscous polyelectrolytes, 4) silanization and derivatization of glass

surfaces for planar waveguide and immunoreactor applications, 5) development of liposome-based flow

injection immunoanalysis systems, and 6) investigation of novel optical detectors based on thin-film planar

waveguide and thermal lensing/deflection approaches. The common goal of this work is to increase the

sensitivity and selectivity of electrochemical and optical measurements for trace organic analysis. The

research tools we are using to achieve this goal include: square-wave, differential-pulse, rotating ring-disk,

and cyclic voltammetry: chronoamperometry and chronocoulometry: frequency-dependent and

steady-state fluorescence and internal reflectance spectroscopy: hybrid techniques such as

spectroelectrochemistry and liquid chromatography with uv/visible and electrochemical detection.

We have continued to make good progress on the research goals targeted in the Organic Electrochemistry

and Bioanalytical Sensors Competence Building Programs. Polymer-modified electrodes have been

developed and are undergoing evaluation. Chemical and electrochemical characterization of

cobalt-containing "capped" metalloporphyrins for use as eiectrocatalytic sensors is nearing completion and

a paper on this work is in preparation. Also, a new type of porphyrin polymer-modified electrode has been

prepared which shows excellent coating characteristics (uniformity and stability), a high degree of

electroactivity, and selective permeability. This process, which is described in a recent paper In J,. Electroanal. Chem.. involves the production of a tetra-quaternized porphyrin which can hydrolyze to form

77
the desired polymeric film. Another polymer modification process under investigation involves the thermal

polymerization of the copolymer formed between bismaleimide and diene-containing ruthenium complexes

and deposition on glassy carbon electrodes. These polymer films displayed stable redox behavior and facile

electron transfer between the ruthenium (ll/lll) redox centers and the carbon electrode in a variety of solvents

at ambient and elevated temperatures. As part of our efforts to understand and model the kinetics and

transport processes in polymer films, we have Investigated the electrochemical behavior of ferrocene in polyethylene oxide (PEO-400), a solid/viscous liquid solvent. Using a variety of electrochemical techniques,

the redox behavior of ferrocene was studied at various temperatures. In spite of large resistive effects, we

were able to compare the experimental results with simulated results and obtain heterogeneous

electron-transfer rate constants for this quasi-reversible system. In addition, large-step chronoamperometry,

while not showing simple Cottrell behavior, provided data for the calculation of estimated diffusion

coefficients. A paper on this work has been submitted for publication, as well as another paper on the

application of discontinuous integrals In chronoamperometry using planar disk electrodes.

The goal of the Bioanalytical Sensors competence building project is to use the specificity of immunological

recognition coupled to chemical and/or biochemical amplification to provide highly selective and sensitive

measurement of organic analytes. While we do not expect the present design of our system to have increased

sensitivity over current immunoassays, we do expect significant improvements in convenience,

reproducibility, and accuracy. The first step toward this goal, the encapsulation of electrochemical or

fluorescent markers, or biocatalysts (enzymes), in the aqueous volume of a liposome has been successfully

achieved. Amplification of a competitive immunological binding event may then be achieved by the lysis of

the liposome, thereby releasing thousands of marker molecules for detection or enzyme molecules for

subsequent reaction and product detection (double amplification). We have been approaching this objective

from two parallel directions; a homogeneous immunoassay and a heterogeneous flow injection

immunoassay.

The development of a homogeneous immunoassay, based on the preconcentration and measurement of

liposome-released ferrocyanide by a dual-function polymer modified electrode, has been completed, and a

paper describing the characterization of the ferrocyanide-loaded liposomes and preliminary investigations

of the electrode behavior has been published in Anal. Chem. The physical parameters and stability of the

ferrocyanide-loaded liposomes were studied by electrochemical and spectroscopic methods. Studies were

performed in which the marker ions were released from within the liposome by surfactant or complement

lysis. In the classical complement pathway, an antigen/antibody-specific reaction occurs when an

antigen-sensitized liposome immuno-specifically binds with the corresponding antibody in the presence of

complement. Complement is activated and forms a membrane attack complex which results in the lysis of

the liposome and release of the encapsulated ferrocyanide which is then detected by differential pulse

voltammetry. To further increase the sensitivity of the method and to prevent fouling of the electrode surface

by serum proteins and membrane lipids, a special dual-function anion-exchange polymer modified electrode

was developed. Studies with this modified electrode have demonstrated the ability of the anion-exchange

polymer to preconcentrate the ferrocyanide at the electrode surface as well as to protect the electrode from

fouling. A paper describing the homogeneous immunoassay for the model analyte, anti-dinitrophenol IgM,

Is in preparation.

The flow injection immunoanalysis (FIIA) system underdevelopment is discussed in Technical Activity No.

4 and is based on an immunochemical reaction taking place in a packed-bead column in which the antibody

fragments (Fab’) are covalently bound to small, nonporous-glass beads. Competitive binding occurs in this

column when a solution of the antigen-derivatized, marker-containing liposome is mixed in the flow injection

system with the antigen sample solution and flowed through the reactor column. Unbound liposomes are

carried downstream for non-selective detergent lysis to release the marker molecules which then pass into

78
the detector for quantitation. This flow injection scheme is but one of many that can be used to provide the

desired immunoassay.

The purpose of developing this FI I A approach is to provide a fully automated immunoassay system which

can be regenerated for sequential analysis and calibration. At the present time, several of the critical elements

needed to complete this flow injection immunoassay system have been achieved and the remaining

components are nearing completion. The stability of the liposomes, both in storage and under flow

conditions, has been successfully demonstrated. Their hydrodynamic behavior, which is unique compared

to molecular and particulate species under flow injection conditions, has been carefully characterized, and

a paper on these results has been published in Anal. Chem. Silanization of the glass beads has been a

particularly difficult problem which now seems to be on the verge of solution. As part of this study, we have

developed sensitive and fluorescent assays for the quantitation of the degree of silanization of the bead

surface. We are now also studying ways to immobilize antibodies so that their activity is preserved, as well

as ways to gently dissociate the antigen-antibody complexes to regenerate the binding activity of the

immobilized antibodies. Finally, we have developed a novel generic approach to liposome derivatization

which Involves the use of a biotinyl-phosphatidylethanolamine as a component of the iiposome membrane.

Biotinylated analyte analog is then linked to the biotinylated liposomes using avidin, a multivalent

biotin-binding protein. A paper on this work has been submitted to Biochim. Biophvs. Acta.

Research is continuing to extend this flow injection immunoassay one step further in sensitivity. Instead of

loading the liposomes with electroactive or fluorescent markers, an enzyme (horseradish peroxidase) will be

encapsulated and subsequently released in the presence of its peroxide substrate and p-fluorophenol which

reacts enzymatically to produce fluoride ion which will be detected by a fluoride ion-selective electrode. This

approach will provide a double amplification of the immunoreaction; one being the release of the

encapsulated enzyme and the other being the enzymatic production of fluoride product. After some serious

problems with electrode fouling, which were overcome by introducing a special wash channel containing

Triton X-100 to the FIA system, most of the components of this scheme have been shown to function

independently, and testing is now in progress to optimize their performance in the flow injection mode of

operation.

At the recommendation of last year’s Panel, we have chosen a more relevant analyte than our original mode!

compound, dinitrophenol, for development and testing of this FI I A system. Our current prototype uses

anti-theophyliine antibody for the determination of the therapeutic drug, theophylline. It is estimated that over 100,000 clinical assays are performed annually for this clinically important analyte. Since we have no

facilities for producing antibodies, one of the most important considerations in choosing an antigen-antibody

system for prototype development was the availability, in research quantities, of an antibody of reasonable

affinity. Because of the generic nature of the antibody immobilization and liposome derivatization

procedures, once the prototype system is completed and characterized it should be easily adaptable to a

wide variety of analytes. We have been encouraged in the importance and relevance of this work by the

interest the FilA system has received for commercial development. A patent application on this system was

filed in June. In addition, we anticipate that our work on antibody immobilization will aid in the development

of other techniques such as large-scale purification of biotechnology products (including affinity HPLC),

extracorporeal detoxification, and fiber-optic sensor applications. In our research, we are addressing very

important quantitative aspects such as the maintenance of binding activity after immobilization, the ability to

regenerate immobilized antibody activity for reuse, and long-term stability; all of which are problem areas which are currently limiting the development of these technologies.

Work has been initiated towards developing absorption- and fluorescence-based optical sensors for

immunoassay methods using planar thin-film dielectric waveguides. These waveguides have been fabricated

from silicon nitride using low-pressure chemical-vapor deposition. While these devices are currently

79
undergoing evaluation, the initial results are promising as the Si3N4 waveguides are more durable, easier to

derivatize, and offer a wider range of optical properties than similar waveguides fabricated from polymeric

materials. The detection system for the fiuorimetric sensor, an optical-fiber bundle coupled to a

poiychromatorwith an optical multichannel analyzer detector, has been assembled. Work remaining on the

planar waveguide sensors Involves improving their performance at blue wavelengths, covalently derivatizing

the waveguides, and incorporating the derivatized sensor into an FIA system.

Concomitantly, we are developing thermo-optical methods of detection using the thermal lens phenomenon

as an optical detector for the FI I A project. Currently, a two-laser, pump/probe system is being evaluated as a suitable geometry for FIIA. Sensitivity approaching that of fluorescence methods is expected while

reducing the system complexity. In addition, experiments are underway to determine the feasibility of using

semiconductor lasers for these measurements. The expected advantages would be lower cost, increased

durability, and miniaturization of the optical layout.

Liquid chromatography with electrochemical and optical detection has continued to prove its usefulness in a variety of programmatic applications. As part of the continuing NCI Cancer Chemoprevention Program,

work is in progress to develop and apply an LC/UV method for the determination of the drug

4-hydroxyphenylretinamide and its major metabolite in serum. A new method for the determination of organic

thiois in marine sediments was developed using LC(oxidative)EC detection at a gold/mercury thin-film

electrode. The separation of these hydrophilic compounds was enhanced using trihaloacetic ion-pairing

buffers. One paper on organic thioi detection was published in Anal. Chem. : another on the separation

chemistry of organic thiols has been accepted for publication in J. Chromatog. : and a third paper on modeling

interreiationships of organic thiols and trace metal concentrations in marine sediments is in preparation.

Work is in progress on the pulsed LCEC detection of thiois and disulfides. In collaboration with G. Turk of

the Inorganic Analyticai Research Division, organotin cations have been determined in marine sediments by

LC/LEI (laser enhanced ionization). Suitabie separation and detection conditions were devised, and a method was deveioped for the extraction of the tributyltin compounds from the sediments. A paper on this

technique has been accepted for publication in Anal. Chem. In addition to the LEI detection of the tributyitins,

studies have been initiated on the iaser activation and modification of glassy carbon electrodes for two

applications: 1) selective activation of small areas of a polymer-deactivated electrode surfaces to make

microarrays (currently using photopolymerized allyi sulfide to form the inert polymer film on the electrode

and a focussed laser beam to vaporize selected micrometer-sized areas of the polymer film) and 2)

application of laser activated electrodes to the determination of organic analytes.

In the coming year, we plan to continue our efforts in the ongoing projects discussed above as well as expand

into the new areas of microarray-electrode and thermal-lensing/deflection detectors for application in HPLC,

SFC, and FIA. In addition, we plan to test, evaluate, and optimize the FIIA system and compare its performance to existing immunoassay techniques.

Richard A. Durst, Group Leader; Elmo A. Blubaugh, Marius V. Brizgys (GARB), Steve Choquette (GARB),

Rosanne M. Kannuck, Laurie Locascio-Brown, William A. MacGrehan, Anne L. Plant, Terry Wu (U.Md.), and

William T. Yap.

3. Gas Chromatography Group; Overview

The Gas Ghromatography Group conducts research in the areas of high resolution gas, multidimensional

and supercritical fluid chromatography, advanced sample preparation techniques and micro-computer

applications. To maintain state-of-the-art trace organic analytical competence, which is used to certify

complex Standard Reference Materials (SRMs), address the measurement and quality assurance needs of

other Federal and State agencies, and disseminate technical information.

80
Our efforts in capillary supercritical fluid chromatography (SFC) have been greatly accelerated with the arrival

of Dr. Albrecht Munder, an Alexander Humboldt Fellow from the University of Ulm in West Germany. Because

of his efforts, we now have an empirical understanding of the SFC experiment and have the capability to

arrive at initial conditions for most analyses. Dr. Munder has also obtained the precision and accuracy levels

for which our instrument was designed. He has obtained enough data to start initial physicochemical

modeling of the SFC separation process. We have developed a series-coupled dual-detection apparatus

which allows both UV and FID detection without effluent splitting. While most of our work has been on

nitro-group containing compounds, we have shown that SFC is amenable to the separation of large PAH

isomer (MW >302) non-chlorinated pesticides, and vitamins.

We have used our multidimensional gas chromatographic system for the analysis of extremely complex

chemical mixtures. During this past year, we have shown the feasibility of using this technique for the

congener-specific determination of polychlorinated biphenyls and will shortly use it for certification of SRM

1939-40 (polychlorinated biphenyls on terrestrial soil).

We are constantly improving our abilities in sample preparation for chromatographic analysis. We are using

a number of HPLC techniques to cleanly remove analytes from difficult matrices such as tissue, contaminated

sediment and biological fluids. While we continue to very successfully use conventional methods such as

Soxhiet extraction, normal phase and size exclusion chromatography, we are also investigating some novel

techniques, such as the use of on-column chemical modification of congeneric mixtures for class

determinations and supercritical fluid extraction of matrix samples.

The controlling CPU of the laboratory information management system (LIMS) that the GC Group developed

and used for the past three years, has been replaced by an IBM series PS/2 model 80 CPU. This

microprocessor not only supports all existing MS/DOS software, such as LOTUS 123, WordPerfect, etc., but

has the required speed, memory capacity and disk storage to handle the amount of data acquired by the

Group. This year, novel LIMS software has been written to allow user manipulation and recalculation of

chromatographic data. These programs are window oriented for ease of operation and provide a tremendous

amount of versatility. Also, to improve the stability of stored data, we now store raw chromatographic data

on optical disks instead of the more volatile magnetic diskettes.

As in past years, the Group has spent a great deal of effort contributing to the solLrtion of Other Agency

measurement problems. Our quality assurance program for the National Oceanic and Atmospheric

Administration’s (NOAA), National Status and Trends Program has continued to expand in scope. We have

formulated and completed certification measurements on two new calibration solution Standard Reference

Materials (SRMs) to complement those certified in FY87. These SRMs, 2261 and 2262, are comprised of 15

chlorinated pesticides and 28 polychlorinated biphenyl congeners, respectively, and are at a concentration

approximately ten times greater, 3 ^ig/g, than the similar solution SRMs produced in FY87. A sediment

material (SRM 1941) and a tissue homogenate material (SRM 1974) are also in progress. Certification

measurements for polycyclic aromatic hydrocarbons have been completed and information values for

selected pesticides and polychlorinated biphenyl congeners have been generated for the sediment material.

We are pre.‘f^ently finishing the homogenization step for a tissue homogenate material and hope to begin

certification early in FY89. This SRM consists of cryogenically homogenized mussel tissue and will be

certified for selected polycyclic aromatic hydrocarbons with information values for selected chlorinated

constituents. We have also conducted three intercomparison exercises both using gravimetricaliy prepared

solutions of analytes and a cryogenically homogenized tissue material. Results of the solution

intercomparison exercises have indicated that most of the participating laboratories are outside of the desired

performance criteria set by NOAA. FY89 NIST/NOAA QA milestones will address this shortcoming by

81
conducting additional intercalibration exercises with similar solution materials and other methods such as

training courses and on-site guidance on laboratory procedures.

We have analyzed a number of sediment and tissue samples as part of a specimen banking component of our Reference Laboratory function for NOAA’s Mussel Watch and Benthic Surveillance Program. We are using high resolution, 60-meter capillary columns in conjunction with an improved HPLC sample clean-up

procedure, developed in FY87. The visual quality of the resulting chromatograms and the analytical precision

of the data have improved significantly.

A number of additional human liver samples, from the National Biomonitoring Specimen Bank were analyzed

for pesticides and PCB congeners using a modified sample preparation procedure. Two sets of Quality

Assurance Materials from EPA/Cincinnatl were analyzed as part of the process of establishing NIST

traceability. A twenty-eight component concentrated (3 |ig/g) PCB congener calibration solution was

prepared, analyzed and delivered to EPA/Cincinnati for use as a multipoint calibration standard for EPA

Standard Method 624 (PCB congeners by GC/MS). A volatile organics in human whole blood reference

material, requested by EPA/Las Vegas, has been prepared, measured, and delivered.

We have initiated a new program sponsored by the Department of Defense. Under this program, NIST will develop reference methods for the analysis of surety materials based upon the use of internal standards.

We will also establish relative response factors to be used with the methods so that DoD contractors will not

require authentic standards to perform analyses. Development of these "reference" methods will involve the

evaluation and selection of appropriate internal standards for each surety agent. Most of the effort this year

has been in the modification of the Toxic Handling Laboratory so that the toxic surety materials can be used

in a safe and secure environment. We have, however, identified over 15 possible internal standards for use

with the surety agents.

The Group has made a significant contribution to the Division’s SRM program. In addition to the NOAA

supported activities, we have commenced certification measurements of two terrestrial soils (SRM 1939-40)

containing high concentrations (ng/g) of polychlorinated biphenyls. Additionally, we have developed and

improved a protocol for the determination of the purity of chemical materials used in the SRM program. This

protocol employs both chromatographic and calorimetric data for the purity determination. We have

obtained a differential scanning calorimeter and are using this instrument to confirm the gas chromatographic

purity measurements of 68 compounds used to make up calibration SRMs. This year, using this protocol,

we have confirmed the purity of over 75 lots of chemicals.

While the Group Is heavily committed to its Other Agency and SRM work, we realize the need to concurrently

pursue an active research program to maintain our cutting-edge measurement capabilities. We hope in the

next three years to make substantial progress in four areas. First, we want to continue to develop our

expertise in multi-dimensional gas chromatography and utilize this technique to make both trace organic

analytical and purity measurements. We desire to delve further into the retention mechanisms of capillary

supercritical fluid chromatography and are hopeful that we will be able to maintain the momentum given to us by Dr. Munder. We will also investigate the use of the new capillary column technological breakthroughs

such as ultra-thin films and high temperature phase coated columns. We hope to use these state-of-the-art

columns for high resolution separation of biomolecules of interest to other Groups within the Division. Finally,

we want to continue to carry on research In sample preparation methodology and on-column chemical

modification of congeneric and isomeric analytes for accurate total class quantitative determination.

If we are to maintain our current level of research activity and also fulfill our Other Agency commitments, we

will need a permanent staff member to replace Dr. Munder at the end of his postdoctoral appointment. We

plan to expand our measurement capabilities to include a capillary compatible FTIR GC detector which will

82
allow nanogram level isomer-specific detection of congeneric classes of compounds such as PAC,

chlorinated naphthalenes and biphenyls, volatile nutrients and polar non-chlorinated pesticides. Such an

instrument can be series coupled with the MSD, to remove an additional degree of freedom for molecules

to escape detection and identification. This detector, with some modification, also be compatible with our

capiilary SFC instrumentation.

Stephen N. Chesler, Group Leader; Franklin R. Guenther, John C. Leak, Albrecht A. Munder, Reenie M. Parris,

Richard E. Rebbert, Michelle M. Schantz, and Eric B. Wold.

4. Liquid Chromatography: Overview

The activities of the Liquid Chromatography Group continue to be focussed on gaining a better understanding

of the mechanisms responsible for retention and selectivity in liquid chromatography (LC), and applying this

information to the development and improvement of methods for the isolation, separation, identification, and

quantitation of individual components in various matrices.

Physical and chromatographic characterization of alkyl-bonded phases continues to be a major area of

research In the understanding of reversed-phase LC retention mechanisms. An investigation of the

relationship between the alkyl-bonded phase thickness and the selectivity (i.e., relative separation) for

isomeric compounds is described in Technical Activity No. 1 and has been published in Analytical

Chemistry 59:2309-2313 (1987). Fora series of alkyl-bonded phases with chain lengths ranging from Csto

C30, selectivity for polycyclic aromatic hydrocarbons (PAH) increased with increasing phase thickness. In several of our studies, we have used a mixture of three PAH to characterize the selectivity of reversed-phase

LC stationary phases. This mixture contains benzo[a] pyrene (a planar solute) and

phenanthro[3,4-c]phenanthrene and tetrabenzonaphthalene (nonplanar solutes). The differences in elution

order of these three components are useful In classifying Cis stationary phases (e.g., monomeric or polymeric

synthesis) and predicting their ability to separate more complex mixtures of PAH isomers. This mixture was

used recently to evaluate the selectivity of over 25 commercial Cis columns and as a result, we have proposed

a stationary phase classification system based on this test mixture (J. High Resolut. Chromatogr. Commun.

11:383-387 [1988]). This mixture has been distributed to a number of LC researchers to determine its potential as a LC column performance SRM.

Polymeric Cis phases exhibit shape selectivity for the separation of isomeric PAH that is similar to the shape

selectivity observed for liquid crystalline phases In gas chromatography (GC). Relative retention

measurements for several sets of isomeric PAH on a polymeric Cis phase (reversed-phase LC) and

liquid-crystalline polysiloxane stationary phase (capillary GC) were compared and correlated with the simple

length-to-breadth shape descriptor of the solute. Similar retention behavior was observed for both

chromatographic systems. In fact, anomalies In elution order relative to length-to-breadth ratios were

generally found to be consistent in both chromatographic systems and could often be ascribed to secondary

shape factors such as the planarity of the molecule. The similarity in selectivity for reversed-phase LC and

liquid-crystalline GC should extend beyond PAH (and other polycyclic aromatic compounds) suggesting

that excellent separations of other isomeric compounds that are resolved on liquid-crystalline phases in GC

may be achieved by reversed-phase LC on polymeric Cis phases. The results of this study have been

published in Chromatographia 25:473-479 (1988). Investigations in progress indicate that the temperature

of the column greatly influences the monomeric-like or polymeric-like behavior of the stationary phase. One

goal of all of the above studies involving characterization of stationary phases is to gain a better understanding

of the exact nature of polymeric vs. monomeric alkyl phases and the mechanisms responsible for separations

in reversed-phase LC.

83
A major new measurement-oriented research effort initiated during the past year involves the evaluation of

the quantitative capabilities of thermospray liquid chromatography-mass spectrometry (LC-MS). Our initial approach to evaluate quantitative LC-MS, in collaboration with the Mass Spectrometry Group, has focussed

on the use of isotope labeled internal standards to quantify uric acid in SRM 909. These results are described

in Technical Activity No. 2 and indicate that LC-MS can provide an additional analytical technique for accurate

trace organic analysis in complex matrices.

The LC Group is heavily involved in the application of LC to the determination of trace-level analytes in a

variety of sample matrices as part of the SRM program and in support of other agency projects sponsored

by the National Cancer Institute (NCI), Environmental Protection Agency (EPA), National Cceanic and

Atmospheric Administration (NCAA), and the American Petroleum Institute (API). Four SRMs were

completed and issued during the past year for which LC was one of the analytical techniques used for the

certification measurements: (1) SRM 1597, Complex Mixture of Polycyclic Aromatic Hydrocarbons from

Coal Tar; (2) SRM 1563, Cholesterol and Fat-Soluble Vitamins in Coconut Cil (Fortified and Natural): (3) SRM

1647a, Priority Pollutant Polycyclic Aromatic Hydrocarbons in Acetonitrile: and (4) SRM 1507,

1 1 -nor-delta-9-tetrahydrocannabinol(THC)-9-carboxylic acid in Freeze-Dried Urine. The certification of SRM

1597, Complex Mixture of Polycyclic Aromatic Hydrocarbons from Coal Tar, is described in Technical Activity

No. 19 and the analytical methods for the certification measurements have been published in Analytical

Chemistry 60:887-894 (1988). SRM 1563, Cholesterol and Fat-Soluble Vitamins in Coconut Oil, is the first food-related SRM specifically prepared for the determination of organic nutrients. SRM 1507, THC in Freeze-Dried Urine, is the first in a series of SRMs for use in the determination of drugs of abuse in urine (see

Technical Activity No. 21). The LC methods used in the certification of the coconut oil SRM have been

published in Analytical Chemistry and methods for certification of the THC in Urine SRM have been

submitted for publication.

The LC Group has contributed to the development of five SRMs and a RM that are in the process of

certification: (1) NBS/EPA Reference Material 8444, Cotinine in Freeze-Dried Urine; (2) SRM 1588, Organics

in Cod Liver Oil; (3) SRM 1941, Organics in Marine Sediment; (4) SRM 1974, Organics in Mussel Tissue

(Mytilus edulis), (5) SRM 1508, Cocaine in Freeze-Dried Urine; and (6) SRM 916a, Bilirubin. The cotinine in urine reference material consists of three urine samples that mimic the cotinine urinary levels representative

of: (1 ) nonsmokers with no exposure to cigarette smoke, (2) nonsmokers with passive exposure to cigarette

smoke, and (3) smokers. SRM 1588, Organics in Cod Liver Oil, is intended primarily for use in the

determination of chlorinated pollutants. However, cod liver oil also contains a relatively high level of

a-tocopherol (vitamin E) and is representative of an edible oil. Therefore, two LC procedures were used to

obtain data for the certification of a-tocopherol in this SRM. A marine sediment (SRM 1941) and a mussel

tissue (SRM 1974) have been collected and prepared for certification as SRMs for use in the measurement

of marine contaminants (see Technical Activity No. 1 8). Certification measurements on the sediment material

have been completed using LC with wavelength-programmed fluorescence detection as one of the analytical

techniques. Similar LC methodology will be used for the certification of the mussel tissue which has been

prepared using cryogenic homogenization to provide a homogeneous frozen powder as the SRM.

Measurements of cocaine and cocaine metabolites in SRM 1508 by LC are currently in progress to certify

the second SRM for the determination of drugs of abuse (see Technical Activity No. 21 ). LC measurements

were performed on SRM 91 6a, Bilirubin, to determine the homogeneity of the isomer content and the relative

amounts of the three isomers (Ilia, IXa, and Xllla) which will be provided as information values on the

certificate of analysis. During the coming year, the LC Group will be involved in the development and

certification of SRMs for fat-soluble vitamins in human serum and total human diet, pollutants in marine tissue,

and additional drugs of abuse in urine.

A major effort within the LC group continues to be analytical support for the National Cancer Institute’s

Micronutrients Measurement Program. This project is described in detail in Technical Activity 13. As the

84
quality assurance laboratory for this program, NIST regularly supplies human serum samples to

NCI-supported laboratories for the determination of ascorbic acid, retinol, a-tocopherol, and a-carotene. LC

analyses are performed to determine the NIST "reference values" for these samples.The separation of

p-carotene Isomers Is an illustration of the application of knowledge gained from our fundamental

investigations of selectivity in reversed-phase LC to achieve challenging separations. Based on our previous

studies of the factors that affect LC selectivity for the separation of PAH, we investigated the influence of

stationary phase type and synthesis on the separation of p-carotene isomers. As in previous studies with

PAH isomers, we found that a polymeric Cis phase (trifunctional silane synthesis) provided greater selectivity

for the separation of the p-carotene isomers than the monomeric Cis phase (monofunctional silane

synthesis). Increasing the alkyl chain length or increasing the surface coverage of the stationary phase

altered the column selectivity. Polymeric alkyl bonded phases with chain length greater than Cu separate

trans-p-carotene and the various cis isomers, whereas the monomeric phases would not resolve these

isomers. Based on these investigations, we are preparing ’tailored" stationary phases to optimize the

separation of these isomers. It also appears that the shape and planarity of the carotenoid isomers can be

used to predict the order of elution. These studies have allowed us to characterize various p-carotene

preparations used in NCI intervention studies to determine the purity and distribution of ds- and

trans-p-carotene isomers. By knowing the distribution of these various p-carotene isomers in these

preparations, NCI can use formulations that contain only the active (more potent) isomer in their intervention

studies. Investigations are continuing to better understand the mechanism of separation of these carotenoids

in reversed-phase LC.

Members of the LC Group are involved In another continuing, long-term activity known as the National

Biomonitoring Specimen Bank. This program, which is a joint effort with the Inorganic Analytical Research

Division, consists of the collection, processing, long-term storage, and analysis of a variety of environmental

and biological specimens. These specimen banking activities are supported by several different agencies

including ERA, NOAA, and NCI. The expanding scope of the NIST specimen banking activities is described

in the Technical Activities.

The LC Group has also been involved in several additional other agency projects such as the determination

of herbicides in ERA QA materials (as part of the process of providing NIST traceability), the determination

of RAH in marine sediments and tissues (NOAA), the identification of organic markers for residential wood

combustion (ERA) (see Technical Activity No. 9), and the development of procedures to isolate benzene

from breath samples for subsequent carbon isotopic measurements (ARI). In research related to the

investigation of chemical markers as a means of radiation dosimetry, we have used LC in the isolation and

identification of thymine-tyrosine crosslinks, which may serve as such markers (see Technical Activity No.

3).

During the past year, we added one permanent staff member to the LC Group, Dr. Bruce A. Benner. Dr. Benner has worked part-time in the LC Group for the past four years while working on his Rh.D. at the

University of Maryland. He has experience in LC, GC, and GC-MS with particular emphasis on environmental

sampling and analyses. Marit Olsson, a guest scientist on leave from Kabi Vitrum, a pharmaceutical

company in Stockholm, Sweden, has joined the LC Group for one year. Ms. Olsson is using her background

in pharmaceutical chemistry to assist us in expanding our investigations of LC column selectivity to include

additional classes of compounds (e.g., tetracyclines). Apryll Stalcup, a graduate co-op from Georgetown

University, completed her Rh.D and accepted a postdoctoral appointment at the University of Missouri at

Rolla.

During the next several years, research in the understanding of LC retention mechanisms will continue to

focus on (1) methods for physical and chromatographic characterization of stationary phases, (2) factors

affecting selectivity, and (3) comparison of LC and supercritical fluid chromatography (SFC) retention

85
mechanisms. We will continue to develop LC methods for the determination of trace organic constituents

in various matrices. For environmental samples, we will continue to improve LC methods for the isolation

and determination of the compounds of Interest. In the past year, we have focussed a great deal of attention

on the measurement of vitamins in serum and food matrices and drugs of abuse and cotinine in urine. We

expect that this trend will continue In the upcoming years. In addition to analytical separations, LC has been

used more extensively for isolating the analytes of interest from the serum or urine matrices (I.e., sample

cleanup) prior to quantitation by other techniques. There is currently a great deal of interest within the liquid

chromatography community in the use of micro columns, i.e., microbore and packed capillary LC. We wiiS investigate the applicability of such systems to our measurement problems. To expand our separations

capabilities and expertise, we intend to actively recruit graduate students, postdoctoral research associates,

and guest scientists with expertise in supercritical fluid chromatography, capillary zone electrophoresis,

micro column (microbore or capillary) LC, retention mechanisms, and/or stationary phase characterization.

Stephen A. Wise, Group Leader; Bruce A. Benner, Jeanice M. Brown-Thomas, Richard G. Christensen, Neal

E. Craft, Barbara J. Koster, Sam A. Margolis, Marit Olsson, Lane C. Sander, and Xin Zhang.

5. Mass Spectrometry Group: Overview

The Mass Spectrometry Group conducts research in a number of areas which include both basic and applied

efforts. The major part of our work continues to be the development of mass spectrometric methods for the

accurate quantitation of individual organic compounds in complex matrices. In addition, there is work on the

characterization of pure materials for the reissue of Standard Reference Materials (SRMs), and there are continuing efforts to acquire expertise in techniques new to us, such as thermospray and collision induced

dissociation, and to gain further understanding of the mechanisms involved in negative ion chemical

ionization.

The College of American Pathologists (CAP) Reference Laboratory, established at NIST last year, is fully

operational with two full-time Research Associates. About half of the effort is devoted to the continued

development of definitive methods and their use to certify NIST SRMs and to assigning values for CAP survey

sera and reference materials. This work and related efforts on human serum based SRMs are described

below and in the Technical Activities. Work Is also in progress on an SRM for cocaine and its metabolites in urine. These cooperative ventures are progressing well: the nature of the materials required has been defined

jointly by CAP and NIST; the materials have been procured by the CAP, thus providing economies of scale;

the characterization has been done at NIST by the joint efforts of the CAP Research Associates and NIST

personnel; and the resulting reference materials may be obtained from either organization. In the other part

of our program with the CAP, reference methods have been set up at NIST by a CAP Research Associate

and applied to CAP materials. These have included colorimetric methods for calcium, chloride, ethyl alcohol

in water, and glucose. The last method required considerable refinement in order to produce satisfactory

precision, 0.5%, on more than very small numbers of samples. An additional significant effort has been

devoted to the testing of cyanmethemoglobin standards by the accepted reference method, and to serving as a referee laboratory for the International Committee for Standardization in Haematology (ICSH)

international cyanmethemoglobin standards. Developing competence In these methods provides NIST with

expertise not otherwise available and the CAP with ready access to NIST analytical capability.

The isotope dilution GC/MS definitive methods developed for the quantitative determination of constituents

in human serum have been applied extensively. Cholesterol, uric acid, and glucose were measured again

this year in SRM 909, Human Serum. The uric acid concentration has shown no statistically significant change

over the eight-year lifetime of the material. Glucose continued the previously observed decline at a rate of

about 0.7% per year, and, for the first time, a rate of decline for cholesterol, just under 0.2% per year, was

established. The certification of two new human serum based SRMs for cholesterol is described in the

86
Technical Activities. Measurements were also completed on several survey and reference materials for the

CAP. These SRMs, reference materials, and survey materials together provide one of the essential elements

necessary for reliable and accurate clinical chemistry measurements.

The definitive methods developed for analytes in matrices of clinical interest have much broader potential

applications. Examples of this are the adaptations of the method for cholesterol to three different food-related

materials which are described in the Technical Activities.

Two new techniques, thermospray for LC/MS and collision induced dissociation, became available to us this

year with the acquisition of a triple quadrupole mass spectrometer. The use of these techniques for

quantitation, particularly for materials not easily amenable to GC and present in complex matrices, is very

promising. The results, achieved in cooperation with the Liquid Chromatography Group, of applying these

techniques to the determination of uric acid in serum as a trial material are described in the Technical

Activities.

A project for the Department of the Army requiring the development and validation of a method for the

determination of 3-quinuclidinyl benzilate (BZ), a chemical agent scheduled for demilitarization, and two of

its metabolites in urine was completed a year ago. A new related project has begun. Pure materials and

solutions, which will serve as standards for control of the analytical chemistry required for the demilitarization

process, will be produced and delivered over a two-year period.

Certification of the first, in an anticipated series, reference material for drugs of abuse has been completed

and is described in Technical Activity 21. This SRM (1507) contains 1

1 -nor-delta-9-

tetrahydrocannabinol-9-carboxylicacid, the primary urinary metabolite of the active component of marijuana,

in lyophilized urine. Stability surveillance measurements are in progress on this material. The isotope dilution

GC/MS method developed will also be used to assign values to a similar CAP reference material.

Replacements for two pure material SRMs, Creatinine (SRM 914), and Cholesterol (SRM 911a), have been

certified, and the measurements necessary for the certification of a new Bilirubin material are in progress.

The determination of the purity of very pure materials and the assignment of uncertainties remains an

analytical challenge. Extensive use was made in these efforts of the wide range of capabilities available within

the Division and elsewhere in the Center.

The research reported in previous years on the negative ion chemical ionization (NICI) of polynuclear

aromatic hydrocarbons provided a useful analytical capability. Continuation of this work is being undertaken

by Dorothy Falcone, a graduate student at The American University, who has joined the group as a Guest

Scientist.

Investigation of the laser induced photodissociation of Ions as a technique for the determination of the

structure of large molecules has been terminated. The project succeeded in producing the first observations

of the photodissociation of ions generated by field ionization, field desorption, and fast atom (cesium ion in our case) bombardment. The limits of our present instrumentation and straightforward approach had been

reached. Alternate approaches Including chemical derivatization to increase absorptivity and the

construction of a high intensity resonant cavity would require currently unavailable personnel and equipment.

Other laboratories now have pursued photodissociation as a technique for structure determination. One

particular variation of this technique has practical applications.

In the year ahead we plan to continue work on many of the projects with which the group is presently involved.

Specific efforts will include: completion of the work required for the reissue of SRM 91 6, Bilirubin; completion

of the drugs of abuse SRM for cocaine; the issue of SRM 1952, Cholesterol in Freeze Dried Human Serum;

87
measurements required on a material to replace SRM 909, Human Serum; the assignment of values on CAP

survey materials; the set up of a reference method for protein for the CAP; refinement of the analytical method,

developed a year ago, for measuring the dose of radiation to which meats have been exposed; and,

application of collision induced dissociation and thermospray on the triple quadrupole mass spectrometer

for high accuracy quantitation. Longer range plans include: the development of a definitive method for

triglycerides in serum; the quantitative determination of DMA adducts; and the adaptation of

photodissociation experiments to instrumentation other than the high resolution double focusing magnetic

instrument presently used.

The instrumentation available to the group improved near the end of last year with the installation of a

completely equipped triple quadrupole mass spectrometer and we have now learned to use the LC/MS

(thermospray ionization) and collision induced dissociation techniques not previously available to us. The

group presently has five mass spectrometers: the triple quadrupole instrument; a "mass selective detector," a GC/MS with electron impact capability only; another quadrupole GC/MS instrument, a magnetic sector

GC/MS instrument, and a high resolution double focusing instrument. These presently provide us with all of

the capabilities we need, with the exception of full scanning at high resolution. The oldest instrument, at 14

years, is the magnetic GC/MS on which the definitive methods are dependent. However, provision has been

made, in the agreement with the CAP, for funding to assist with replacing this instrument in a few years.

The personnel in the group has changed considerably over the last year. We are seeking one new mass

spectrometrist for the group and also postdoctoral candidates whose interests are compatible with our

interests and programs.

Edward White V, Group Leader; Alex Cohen, Polly Ellerbe, Stanley Meiselman, Lorna T. Sniegoski, Susan

Tai, and Michael J. Welch.

88
B. Selected Technical Reports

(Organic Analytical Research Division)

1. investigation of the Relationship between Stationary Phase Thickness and Selectivity for

Isomeric Compounds in Reversed-Phase Liquid Chromatography

LC. Sander and S.A. Wise

Differences in retention behavior of supposedly similar or identical stationary phases have prompted

investigations concerning the influence of bonded phase parameters on retention. Solute retention in

reversed-phase liquid chromatography is often described in terms of solvophobic interactions between the

solute, the mobile phase, and the stationary phase. Unfortunately, this model does not adequately explain

stationary phase contributions to selectivity. In previous work we have demonstrated that differences exist

in selectivity for the separation of polycyclic aromatic hydrocarbons (PAH) on monomeric and polymeric

Ci8 stationary phases. In our present investigation, we studied the effect of alkyl phase length on selectivity

for phases prepared using both monomeric and polymeric modification chemistries. This work has added

to our understanding of retention mechanisms for PAH and has implications that may help to improve

separations of other classes of compounds.

Monomeric and polymeric phases were prepared with chain lengths ranging from Cs to C30. Chromatographic properties of each column were assessed with PAH probe solutes. A mixture of three PAH

(benzofa] pyrene, BaP; phenanthrophenanthrene, PhPh; and tetrabenzonaphthalene, TBN) has been found

to be particularly useful in classifying phase selectivity. This mixture has been used in past work to distinguish

monomeric- and polymeric-like selectivity in over 25 commercial Cis columns. Recently, we proposed the

use of this mixture as a column evaluation mixture to determine the selectivity of Cis phases. For the alkyl

phases of different chain lengths, overall selectivity toward PAH increased with increasing chain length (phase

thickness). For both monomeric and polymeric synthetic routes, short chain length phases exhibited

monomeric-like selectivity, whereas polymeric-like selectivity was exhibited for long chain length phases.

The biggest difference in retention behavior for the two phase types was observed for phases of intermediate

length, i.e., Cis phases. Small angle neutron scattering (SANS) was used to directly measure differences in phase thickness using a technique known as contrast variation. The bonded phase materials were placed

in solvents containing known hydrogen/deuterium ratios (methanol/methanol-ds). By matching the

scattering length density of the silica, scattering from the pore structure was eliminated and information about

the bonded phase thickness was obtained. Poiymerically bonded Cis phases were found to be about 50%

thicker than monomerically bonded Cis phases.

The ability of a particular column to discriminate between PAH isomers (shape selectivity) has been described

by a schematic representation of the bonded phase referred to as the "slot model". The retention of narrow

planar PAH in preference to square, nonplanar PAH can be visualized in terms of penetration of the molecules

into imaginary slots in the bonded phase. Because narrow molecules will fit into these slots more completely

than bulky molecules, solute-bonded phase interactions are stronger and retention is greater. Phase

thickness adds a third dimension to the picture. Extending this model, phases with deep slots (thick phases)

will exhibit more shape selectivity than phases with shallow slots (thin phases).

This study has demonstrated that phase selectivity toward PAH can be controlled by altering phase thickness as well as phase type. Separations carried out on other classes of solutes (e.g., carotenoid compounds)

have suggested that "thick phases" may, in general, have potential for enhanced resolution of structural

isomers. Our studies of stationary phase characteristics that affect selectivity in reversed-phase liquid

chromatography are continuing.

89
2. Eyaluation of the Quantitative Capabilities of Thermospray LC/MS

R.G. Christensen, P.M. Ellerbe, and MJ. Welch

The combination of liquid chromatography with mass spectrometry (LC/MS) is a powerful new tool for the

analysis of organic compounds. This technique has been used widely to identify and characterize substances

which are difficult or impossible to analyze by gas chromatography. The application of LC/MS to quantitation

has been much more limited, in part because of large imprecision caused by fluctuations in the signal level

that are generally observed. One promising approach to precise quantitation by LC/MS involves the use of

stable isotope labeled internal standards. These compounds would co-elute with the analyte and thereby

allow the affect of source pressure fluctuations to be minimized. We have been investigating this approach

to determine if LC/MS can be used to accurately and precisely quantify analytes which are difficult to measure

by other techniques.

The determination of uric acid In serum by LC/MS was chosen for investigation. Reconstituted serum (SRM

909) was spiked with a known amount of uric acld-^^N2 and treated with trichloroacetic acid to precipitate

protein. Fifty microliters of the supernate were then Injected directly onto a C-18 LC column which was

interfaced to a triple quadrupole mass spectrometer via a thermospray device. The best results were obtained

when the thermospray Ion source was tuned for best signal stability rather than for maximum sensitivity. The

eluting solvent was an aqueous solution of 0.075 M ammonium acetate and 0.003 M tetrabutylammonium

hydroxide adjusted to pH 5.2. The (M-H)- Ions for the unlabeled and labeled forms of uric acid were measured

and their ratio calculated. To determine the quantity of uric acid in the serum, such ratios were compared

with ratios from uric acid standard solutions spiked with a concentration of labeled uric acid similar to that

in the samples. The results for the three serum samples tested were within about 1 % of the certified value

(81 ppm) determined by the isotope dilution/gas chromatography/mass spectrometry definitive method. The

LC/MS method is less precise (coefficients of variation about 1%) than the definitive method, (c.v. ~0.3%)

but requires far less sample pretreatment.

The evaluation was carried one step further as a test for specificity. The triple quadrupole mass spectrometer

is designed to allow collision-induced dissociation (CID) of ions. Therefore, we selected the (M-H)- ions from

LC/MS, performed CID on them, and measured the intensity of specific fragment ions. This process

(LC/MS/MS) eliminates most likely interferences, thereby minimizing the probability of bias. The LC/MS/MS

results agreed well with the LC/MS and GC/MS results.

These evaluations demonstrate that the combination of isotope dilution with thermospray liquid

chromatography/mass spectrometry can provide accurate and precise results and should provide both

another tool for use in the certification of SRMs and a means for the determination of many substances that are not readily determined by GC/MS.

3. Thymine-Tyrosine Crosslinks: The Identification of a New Group of Radiation-Induced

Compounds of Potential Biochemical Importance

S.A. Margolis, B. Coxon, E. Gajewski*’ and M. Dizdaroglu*

DNA-protein crosslinks have been induced in both procaryotic and eucaryotic cells by UV, X-, and gamma

radiation. The frequency and repair of such crosslinks is directly proportional to the dose of radiation and

the survival of irradiated cells. The methods for quantifying the formation of crosslinks is complex, lengthy

*Center for Chemical Physics.

90
and prone to error. The identification of the chemical nature of the crosslinks and the development of

chemical methods of analysis provide a solid basis for the development of a biochemical method for radiation

dosimetry and the measurement of DNA repair.

In a model system composed of an irradiated mixture of tyrosine and thymine we have isolated

thymine-tyrosine crosslinks using liquid chromatography. The mass spectrum of the crosslinked product

revealed a fragmentation pattern characteristic of such a dimer, and the proton and carbon NMR spectra

proved that the dimer consisted of equal amounts of tyrosine and thymine with a carbon-carbon bond

between the methyl group of thymine and the 3-carbon of the phenolic ring of tyrosine. By high resolution

mass spectrometry, the molecular weight of the dimer ion was within 5 milli-mass units of that expected.

These results have been accepted for publication in Biochemistry. We have subsequently demonstrated

that the identical compound is formed upon the irradiation of calf thymus nucleohistone and that the formation

of this dimer is proportional to the dose of gamma radiation between 1 4 and 300 Gy. This would suggest that

it is possible to detect these crosslinks in animal tissues exposed to 1 x 10^ to 1 x 10® Gy and to use this

method as a radiation dosimeter. In addition, Gajewski, et al. [(1988), have identified by gas

chromatography-mass spectrometry, the occurrence In irradiated nucleohistone of the crosslinks of thymine

and the amino acids glycine, alanine, valine, leucine, isoleucine, and threonine. These show a similar

dose-concentration response and may also serve as alternative or secondary dosimeters. However, the

advantage of the tyrosine-thymine crosslink and other crosslinks over monomer products, such as

ortho-tyrosine, is their high molecular weight, thus reducing the possible interference from low molecular

weight compounds when single-ion monitoring gas chromatography-mass spectrometry techniques are used for Identification and quantitation.

The preliminary results from their investigation provide a chemical basis for the measurement of the effect

of radiation on cellular nuclear material, particularly nucleohistone, and thus open up several new avenues

for research which are:

(1) The in-vitro formation, isolation and characterization of other amino acid nucleic acid dimers

(some of which have been detected in gamma irradiated calf thymus nucleoprotein) by use of

the methods described for the thymine-tyrosine dimer;

(2) The demonstration of the occurrence of these dimers in gamma radiated viruses, cells and

tissues;

(3) The development of a method of biochemical dosimetry for irradiation exposure of animal and

plant cells and tissues.

4. Liposome-Enhanced Flow Injection Immunoanalysis

A.L. Plant, L. Locascio-Brown, M.V. Brizgys, and R.A. Durst

Immunoglobulin (antibody) proteins are potentially powerful analytical reagents because of several

important characteristics. They typically bind their ligands with very large affinity constants, in the range of

10*® M*^ to 10*^° M*\ and in addition can exhibit a high degree of specificity in molecular recognition of their

ligands. Antibodies can be prepared, for example, which can distinguish between optical or positional

isomers of otherwise identical molecules. As a result, they are extremely effective agents for isolating and

identifying analytes of interest which are present in complex mixtures. Antibodies can be produced against

almost any molecule, and cells producing monoclonal antibodies can be stored for long periods of time to

ensure a constant supply of antibody reagent with discrete affinity and specificity characteristics.

91
The interaction between antigens and antibodies is the basis of sensitive diagnostic techniques such as radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA). Although these techniques are very sensitive and widely used, they can be time-consuming and technically cumbersome, and are only

semi-quantitative. The optimal Immuno-based assay should be fast, quantitative, and able to be calibrated

and automated.

Our current approach to the development of such an analytical system is a combination of the technique of

flow injection analysis (FIA) with immunochemistry, which we call flow injection immunoanalysis (FilA). FIA

is a continuous-flow method based on the introduction of a sample aliquot into a moving nonsegmented

carrier stream. All introductions and directions of flow are determined by a series of

microprocessor-controlled solenoid valves.

Immobilization of antibodies which bind an analyte of interest in an FIIA reactor is the first step in developing a reusable, automated immunoanalyzer. The basis of our immunoreactor is a small column of solid glass

beads which have been prepared by derivatizing with monofunctional aminopropylsilane. We have

characterized the stability of this silane coverage under flowing conditions and found that less than 1% of

the silane is lost during 24 h of continuous flow in pH 7 aqueous buffer. The amino group of silane is then

derivatized with a bifunctional reagent, to which an antibody F(ab)' fragment is then attached. We are

currently testing some novel chemistry which will provide stable, oriented, and active immobilized antibody

protein. We are using fluorescence techniques as well as radiolabel approaches to characterize antigen

binding activity of antibody in solution, for the purpose of quantifying the effect of immobilization.

Detection and quantitation of the interaction between analyte in a sample and the immobilized antibodies on

the immunoreactor column are mediated through the use of lipid vesicles (liposomes). Liposomes are prepared with approximately 10^ fluorescent molecules contained within each. When liposomes which are appropriately derivatized, compete with analyte molecules in a sample for binding to immobilized antibodies,

every liposome which does not bind, due to the presence of a bound analyte molecule, flows downstream

into a fluorescence detector. We have developed a generic method of derivatizing liposomes so that it is relatively easy to prepare reagent liposomes for different analytes. A small molecule, biotin, is attached to

the polar headgroup of some of the phospholipid molecules comprising the liposome membrane. These

biotinylated liposomes are then attached to biotinylated analyte-analogue molecules through the protein,

avidin, which has multiple binding sites for biotin.

The practical application of an automated, reusable, and quantitative analytical system of such sensitivity

and specificity should have enormous impact in the areas of clinical, environmental, and industrial

measurements. In additfon, this approach poses serious challenges in the area of antibody protein chemistry,

and the results of this work is of direct importance to all immobilized antibody applications, including affinity

chromatography and extracorporeal detoxification. In the area of FIA, the study of liposomes as model

systems for macromolecules and microorganisms in flowing systems has already received attention. Work

on derivatization of liposomes is also applicable to other forms of immunoassay as well as to the area of drug

delivery.

5. Laser-Induced Modification of Electrode Surfaces

W.A. MacCrehan

The electrochemical current response at a solid-surface electrode is highly dependent on the condition and

history of the surface. Many procedures have been developed to provide a clean, reproducible surface at glassy carbon electrodes. However, in many systems the current resulting from changing the applied voltage

still shows a kinetically sluggish response. A new approach to cleaning and activating carbon electrodes

92
has been demonstrated recently by Prof. Richard McCreery of Ohio State University, who applied a single,

hIgh-power laser pulse to the surface of the electrodes. The pulse energy is sufficient to desorb all impurities

and to generate a short-lived plasma at the surface. Not only is the electrode made atomically clean by

removing impurities and surface oxides, but some restructuring of the graphitic crystal structure may occur. The transfer of electrons to organic molecules in solution is often substantially enhanced at the activated

surface, as evidenced by a lower over-potential required to cause the electrochemical reaction to occur, and

by enhanced current signals. For example, the oxidation of ascorbic acid (vitamin C) occurs at a potential

of -1-700 mV at a conventionally polished carbon electrode, but at the laser-activated surface the

electrochemical process occurs at a potential of -t-350 mV with improved current response. This allows

detection of ascorbic acid with improved selectivity and sensitivity.

Until now, the reproducibility of the activation process using a single neodymiumiYAG laser pulse has been

relatively poor, caused by pulse-to-pulse variations and spatial inhomogeneity of the laser beam intensity.

We are investigating ways to improve the activation process. Another difficulty has been the limited lifetime

of the activation, which lasts for only a few minutes. Chemical reactions that deactivate the surface are

currently under investigation so that this process might become better understood. In particular, the

formation of thin polymeric films to cover the electrode with an inert layer is under study. Following this

treatment, high-intensity micron-sized laser pulses could be rastered over the surface creating activated

"microelectrodes arrays" on the surface of the larger, easily manipulated electrode. Microelectrodes have

significantly enhanced the ratio of the desired analytical signal to background noise, which makes it possible

to detect smaller quantities of material.

Additionally, since only a very few organic analytes have been tested, we are investigating the application of

activated electrodes to the detection of a diversity of organic compounds. A particularly attractive approach

will be to use the laser-activated electrodes in flowing streams such as those coming from a liquid

chromatograph. Periodic laser activation could enhance the sensitivity and selectivity of the detector.

6. Synthesis and Characterization of a Novel "Capped" Cobalt(ll) Metalloporphyrin;

Electrochemical Evidence for a Mixed Coordination Sphere about the Central Metal Ion

E.A. Blubaugh and R.A. Durst

The chemical modification of electrodes imparts specific and predictable properties to the surface of these

electrodes. One avenue of research involves the utilization of these modified electrodes as electrochemical

detectors in combination with liquid chromatography. Parameters such as film stability and fast-ion/electron

transport through the film are important, but the chemical nature and stability of the incorporated

electrocatalysts are just as important. Porphyrins are an obvious choice for immobilized electrocatalysts

because of their robust chemical nature, excellent catalytic behavior and variability in their redox potentials as a function of ligand substituents.

Recent work in the area of porphyrin synthesis has resulted in the discovery of a type of porphyrin, where,

by synthetic design, one of the two axial sites is encumbered. These porphyrins provide a binding site which

is analogous to the binding site for oxygen in hemoprotein biomolecules. Our contribution to this family of

"capped" porphyrins is the synthesis of a new member, which differs from the previous members by changing

the capping portion from benzene to pyrazine. The pyrazine moiety should change the chemical nature of

the binding pocket and will allow fundamental studies on the chemical influence that the pocket has on

metal-centered chemical reactions for these porphyrins. In addition, these "capped" porphyrins have a

built-in size exclusion due to the capping moiety, which will also be beneficial to their use a catalysts.

93
The metalioporphyrin of interest is the cobalt(SI) derivative of these "capped" porphyrins. The coba!t(ll)

derivatives display a reversible and stable redox chemistry associated with the cobalt(ll)/coba!t(!) couple.

However, under appropriate conditions, such as in the presence of organohalides, the Co(H)/Co(l) couple

becomes irreversible due to the reaction of the nucleophilic Co(l) species with the carbon-halide bond. Our

capped cobalt metalloporphyrins (both benzene and pyrazine derivatives) display reversible redox behavior

for the Co(ll)/Co(l) couple with a formal potential of -0.930 volts vs. SSCE. The pyrazine capped porphyrin

shows an additional wave at -1 .035 volts vs. SSCE. This second redox couple is the reduction of a cobalt(ll)

center, which has been stabilized by coordination of the pyrazine cap in either a side-on or end-on orientation.

The particular condition of axial binding for pyrazine will require additional spectroscopic work.

For both cobalt metalloporphyrins, the Co(l) species shows a marked sensitivity to the presence of an

organohalide (i.e., ethylene dibromide, EDB). The redox couple becomes totally irreversible with a plateau

for the electrolysis current in the potential range of -1.1 to -1.3 volts vs. SSCE. These results indicate that

the cobalt(l) does indeed reduce the organohalide, and does so in a catalytic manner, since the direct

reduction of EDB occurs at -1 .750 volts vs. SSCE.

Future work will include the characterization of these novel metalloporphyrins incorporated in polymer films

and their evaluation as electrocatalysts for the reduction of organohalides.

7. Maptation of Definitive Method Technology for the Certification of Food-Related Reference

Materials

PM. Ellerbe, LX Sniegoski, MJ. Welch, and E. White ¥

For over a decade, NIST has been involved in the development of definitive methods for serum constituents.

These methods are highly accurate and precise, and are used to certify analyte concentrations in reference

serum pools. The technique on which the methods are based is isotope dilution/gas chromatography/mass

spectrometry. Samples are spiked with a stable isotope labeled form of the analyte of interest. After an

equilibration period, the samples are processed to isolate the analyte and internal standard from the matrix.

The analyte is derivatized and injected into a gas chromatograph/mass spectrometer system. The ratio of

uniabeied to labeled analyte is determined by comparing of ion abundance ratios for each sample with those

of standard mixtures. Great care is exercised in the sample preparation and measurement steps, resulting

in data with small imprecisions and no evidence for systematic bias. These methods, which have been

thoroughly tested on serum samples, are now being adapted for determining analytes in other matrices.

Research into the relationship of dietary intake and health status has generated great interest in both the

scientific community and the general population. Cholesterol, which has been linked to risk of coronary

heart disease, is a food component of major concern. We have adapted our definitive method for serum

cholesterol to the certification of cholesterol in three food-related matrices. Such materials can then serve as a means for evaluating the accuracy of methods used for determining the composition of foods.

The first food-related material in which cholesterol was determined was SRM 1 563, cholesterol and fat-soluble

vitamins in coconut oil. This SRM consists of a two materials, one natural oil and one fortified with a known

amount of cholesterol. The certification of the fortified oil was straightforward with good precision, and

confirmatory measurements provided evidence for the absence of bias in the measurement process. A

combination of the GC/MS data and gravimetry yielded a certified value of 64.2 ± 0.6 mg/1 00 g oil. Because

the level in the natural oil was very low, we were not able to do confirmatory measurements and the precision

was not as good as we normally observe. The certified concentration for this material is 0.344 ± 0.01 4 mg/100

g oil. Nevertheless, the precision for both materials exceeded the recommended guidelines for such a

material.

94
The second material is a freeze-dried composite food, representative of a typical American diet. This material

was prepared by the U.S. Dept, of Agriculture and will have certified values for a variety of organic arid

inorganic constituents. Certification of the cholesterol content is in progress. In addition, we will investigate

the modification of our definitive method for serum glucose to determine glucose, fructose, and possibly

other sugars in this material.

The third material is a composite freeze-dried whole egg material. For other matrices we have used a standard

alkaline hydrolysis to free cholesterol from Its esters. The AOAC method for cholesterol in eggs calls for an

acid hydrolysis. We studied both approaches and found evidence that cholesterol is partially destroyed by

the acfd hydrolysis. The alkaline hydrolysis was found to be complete, and thus, will be used for the

certification measurements.

The extension of definitive method technology to food matrices provides a means of accurately and precisely

certifying important analytes in materials that can then be used to evaluate the performance of more routine

methods used for making health and nutritional decisions.

8. Determination of PCB Congeners In Complex Matrices Using Two-Dimensional Gas

Chromatography

F.Rc Guenther and S.N. Chesler

A multidimensional gas chromatographic technique has been developed to quantitatively determine

individual PCB congeners. This method utilizes a high resolution capillary precolumn to separate the PCB

congeners according to volatility. Pure PCB congeners are chromatographed to verify elution time, and

published Retention Indices alert us to possible coeluters. The specific congener and co- or closely eluting

compounds are then cut from the effluent of this column, using a differential pressure switch, and transferred

to the head of the second column, which does the final separation of the closely eluting congener pairs. The

second column is a high resolution capillary column coated with an immobilized liquid crystal phase. The

separation on this column is based on molecular shape and, to a lesser extent, polarity. The effluent from

the second column flows into a Hali Electrolytic Conductivity detector which is sensitive to, and selective for,

chlorinated compounds.

It has been demonstrated that this two-dimensional method provides the capability for identifying (based on

retention) and quantifying important PCB congeners, that are known to coelute with other congeners in every

other known chromatographic system. It is hoped that this system v^/ill provide the primary means for

certifying selected PCB congeners In two sediment-based SRMs during the coming year.

Several improvements to this method are contemplated for the near future. This includes the substitution of

ECD detectors for the present detectors to improve the detection limits of the system, and the possible use

of the mass selective detector to improve the specificity of the method. Also possible is the use of a 60 m

precolumn that will e«iable much higher accuracy in the timing of the heartcut. In the coming year this

approach will be applied to other analyte groups where close elution of isomer pairs make quantitative

analysis difficult, if not impossible.

95
9. Organic Chemical Markers for the Identification of Residential Wood and Mobile Source

Combustion

B.A. Benner, Jr., S.A. Wise, and A. Sheffield

In an effort to better delineate source contributions to atmospheric particulate matter at an urban site, a

project was undertaken to determine if there were any differences in the relative concentrations of polycyclic

aromatic hydrocarbons (PAH) in atmospheric particulate matter from different combustion sources. The

dichloromethane extracts of three ambient air particulate matter samples from the Integrated Air Cancer

Project (lACP), sponsored by the Environmental Protection Agency, were characterized for their PAH content

by combined liquid and gas chromatographic techniques, including gas chromatography with mass

spectrometric detection (GC-MS). These three samples were selected to be representative of samples

influenced by (1) high residential wood combustion (RWC), (2) mixed RWC and mobile source combustion,

and (3) high mobile source combustion. Concentrations of 23 analytes were determined in the PAH fractions

of the three lACP extracts. When compared on a ^g/mg residue basis, the concentrations of most of the

PAH in these three samples were of a similar magnitude, particularly the PAH with molecular weights greater

than 226 amu. The four most abundant species in the PAH fraction of the RWC sample were tentatively

identified as the methyl ester of dehydroabietic acid, 1-methyl-7-isopropyIphenanthrene (retene), the

co-elution of the methyl ester of abietic acid (tentative) and a methylfluoranthene or methylpyrene isomer,

and 1,7-dimethylphenanthrene (pimanthrene). The four most concentrated species in the PAH fractions of

the mixed source sample and the mobile source sample were the methyl ester of dehydroabietic acid, the

co-elution of benzofb, j and kjfluoranthenes, benzo[ghi]perylene and retene. Derivatives of abietic acid in wood combustion extracts have been reported previously. The presence of retene

(1-methyl-7-isopropylphenanthrene) in wood smoke has also been reported and it has been suggested that

it could serve as a residential wood combustion marker for resinous woods (conifers). Single-ion

chromatograms of m/z 192 (dimethyl- and ethylphenanthrenes) for the RWC sample and samples collected

in a highway tunnel display similar relative levels of dimethylphenanthrene isomers except that the relative

concentration of 1,7-dimethylphenanthrene is much higher (a factor of 10) in the RWC compared with the

tunnel samples. The predominance of 1,7-dimethylphenanthrene in the RWC sample suggests that this

alkylated phenanthrene may also serve as a marker for residential wood combustion. The identification of

chemical markers indicative of the influence of residential wood combustion and mobile source emissions

for these samples as determined by GC-MS analysis of the PAH fraction was consistent with the ^"^C source

apportionment analyses performed on these same samples. The use of these chemical markers to

distinguish source contributions to ambient particulate matter will be investigated further with additional

comparisons of ^"^C and GC-MS analyses of ambient particulate matter extracts.

10. Proteins of Human Liver: Two-Dimensional Gel Electrophoretic Mapping of Human Liver Tissue

J.J. Edwards and D.J. Reeder

The assessment of liver function is of crucial importance in clinical chemistry. Evaluation of normal liver

function or the detection of malfunctioning processes has required the development of numerous assays

which indirectly monitor function by measuring the activities of selected enzymes or by detecting

components released from damaged cells. These assays, however, offer little in the way of describing the

complex nature of a human tissue or the processes occurring within that tissue that are either the cause or

result of abnormal function. A better understanding of tissue function requires that the complex relationship

between individual cellular components be defined from a molecular viewpoint.

Analysis of human liver tissue at the molecular level requires the use of reproducible high-resolution

separation techniques, sensitive detection methods, and accurate recording and data handling capabilities.

96
These requirements are best met by two-dimensional gel electrophoresis, silver staining, and computerized

image analysis. Also required for this type of study is the availability of a large sampling pool of tissue that

has been obtained and processed in a rigidly prescribed manner. This requirement was met through the

use of human liver tissues from the NIST/EPA National Biomonitoring Specimen Bank, which currently has

an inventory of over 500 samples. Tissue stored in the Specimen Bank are samples taken at the autopsy of

accident victims. Samples were taken under conditions which were specifically designed to prevent

contamination and degradation. Samples used in this study were, upon collection, frozen in liquid nitrogen,

homogenized, and stored in Teflon containers at liquid nitrogen temperatures. Prior to being added to the

Specimen Bank inventory, all samples underwent routine pathological examination. Only samples found to

be free of recognizable diseases including hepatitis, were selected for storage. Selected samples were

removed from liquid nitrogen storage and maintained at -80 °C until analyzed. Patient history, including

documented cause of death, was available for all samples analyzed.

We have analyzed, by two-dimensional electrophoresis protein mapping, a limited number of samples of

presumably normal human liver tissue. Unlike easily obtained samples of human origin such as blood

components and other body fluids, the direct analysis of organ tissue has been limited by the unavailability

of normal tissue samples, with the exception of skeletal muscle and brain. This study on human liver tissue

was prompted by the large number of samples made available by the Specimen Bank. Some of the questions

asked during the course of this study were: (1) Can samples taken at autopsy be used to construct reliable

high-resolution protein maps?; (2) Can procedures designed for the analysis of other tissues be modified to

yield reproducible solubilization and separation of protein components?; (3) How many proteins or protein

subunits can be reproducibly resolved and visualized using two-dimensional electrophoresis and silver

staining?; (4) Can any known cellular proteins be identified?; and (5) Are contaminating proteins present and

do they interfere with the analysis of cellular components?

Homogenized frozen tissue was solubilized, mixed, and centrifuged to prepare a known concentration of

sample. First dimension isoelectric focusing was performed on ten samples in duplicate using the ISO

apparatus before they were electrophoresed at 600V for a total of 1 0,000 volt-hours. Electrophoresis on slab

gels (second dimension) in the presence of sodium dodecyl sulfate (SDS) was performed with the DALT

apparatus. Proteins were fixed, stained and developed using a modified silver staining procedure.

We have scanned the two-dimensional gels by use of a high-resolution imaging system and have identified a number of comparison proteins for further analysis. Correlation of protein spot similarities and differences are being pursued as a database system is being established.

Characterization of the protein composition of normal liver tissue should assist future research efforts in resolving issues relating to such topics as; (1 ) the identification of protein gene products common to a distinct

tissue type; (2) the identification of major normal human variants; (3) normal variability of protein species

found in the population; and (4) differential gene expression resulting from disease, disease treatment,

toxicity, and aging.

97
11 . Besutts of an Interlaboratory Study to Assess Reproducibility of Rehydratable Isoelectric

Focusing Gels

K.L Richie and D.J. Reeder

During the past year, we conducted an interlaboratory collaborative study to test the effectiveness of

rehydratable gels in obtaining consistent patterns with standard protein preparations. Rehydratable gels,

which represent a relatively new type of support medium for isoelectric focusing, were developed in part to

meet the demand for convenience, flexibility and reproducibility in a gel support system. Rehydratable gels,

unlike in-house prepared gels, can be prepared under well-standardized conditions, thus minimizing a

number of undesirable or unknown characteristics; the end result being a more defined gel that requires no

prefocusing because of the extensive washing to remove any by-products of polymerization. A major

advantage of using these rehydratable gels is the low initial current obtained, thereby allowing the application

of higher voltages which result in increased resolution. These gels are easily rehydrated in an

ampholyte-glycerol mixture and can be ready for focusing in as little as thirty minutes. Furthermore, the dried

gels may be stored for over a year at room temperature without any loss in resolving capabilities.

In this two-part study, each of the participating laboratories was provided with a package containing a

standard protein sample, rehydratlon media with instructions, rehydratable gels and a protocol. In the first phase of the study, laboratories were allowed to run gels by their existing methods or by whatever method

they felt would give the best results. In comparing these laboratory results, we noted large variations in the

protein band patterns for the same protein. These differences were caused mostly by the wide variety of

operating procedures that were employed. In the second phase of the study, participants were provided

with a commercially available set of pl charge markers to ensure sample uniformity and were asked to closely

follow a set of specified running conditions. Overall, the results from the second study were more uniform

than those in the first study, thus indicating the importance of standardizing as many of the running conditions

as possible. Differences could be attributed to: (1) voltage gradient applied, (2) temperature during the run,

(3) electrode separation distance, (4) relative humidity at the time of the run and (5) type of apparatus used.

Currently, these gels are being scanned by densitometry from as many different types of scanners as

possible. Results will be statistically compared and reported.

12. Two-Dimensional POMMIE Carbon-Proton Chemical Shift Correlation ^^C NMR Spectrum

Editing

B. Coxon

In an extension of previous work on two-dimensional (2D) POMMIE J(CH) -resolved ^^C NMR spectrum

editing [B. Coxon, Magn. Reson. Chem. 2S (1988), in press; POMMIE = phase pscillations to maximize

editing], we have investigated the feasibility and limitations of 2D POMMIE pulse sequences for the separation

of carbon-proton chemical shift correlation ^^C NMR spectra into CH, CH2, and CH3 subspectra (2D spectrum

editing). The purpose of these experiments is to simplify the 2D NMR spectra of complex molecules, thus

facilitating spectral interpretation, assignment, and the separation of overlapped peaks.

Our initial studies have focused on unique pulse sequences to optimize signal acquisition. Selected

carbohydrate, macrolide antibiotic, and tri- and tetra-peptide derivatives have been used as model

compounds in these studies. Initially, the raw data for shift correlation editing were acquired as three 2D

data matrices, using the phase angle set <|) = 307907150®, as we have used previously for 2D DEPT and

2D POMMIE J(CH)-resolved ^^C NMR spectrum editing. This allowed the shift correlated CH, CH2, and CH3

subspectra to be computed as 1 :1 linear combinations of the three 2D data matrices.

98
By this means, very good 2D carbon-proton chemical shift correlated CH and CH3 subspectra could be

obtained, but, for typical carbohydrate and peptide derivatives, the generation of good CH2 subspectra was

found to be more difficult. The residual CH and CH3 signals in the CH2 subspectra were often unexpectedly

large. This effect appears to be due partly to the fact that the methylene protons in these derivatives are commonly non-equivalent, due to the presence of asymmetry in the molecules. The combined effect of

chemical non-equivalence and mutual spin coupling of the geminal methylene protons reduces the intensities

(peak heights) of the cross peaks in the CH2 correlation subspectra by a factor of « 4, so that the intensities

of the CH and CH3 residues appear to be more prominent by a factor of ~ 4. These limitations also apply

to 2D DEPT shift correlation editing. For 2D POMMIE, it was also observed that use of the value <|) = 90° did

not yield the best CH subspectrum. The use of these methods has generally yielded 2D POMMIE subspectra

of better quality, for both jl(CH) -resolved and carbon-proton shift correlations.

We have also studied a pulse sequence for 2D POMMIE chemical shift correlation editing which incorporates

a BIRD (iiilinear rotation decoupling) sequence for ^H-^H decoupling in the Fi dimension and a composite

^^C 180° pulse for improvement of sample excitation, and where the symbols have the same meaning as

before. This sequence has been tested on oleandomycin, which has yielded CH2 subspectra in which several

of the methylene correlation crosspeaks are sharper due to removal of vicinal ^H-^H spin couplings in the

Fi dimension.

In summary, although the 2D POMMIE method has several advantages, one particular disadvantage is that

the theoretical dependence of intensities on the phase shift (j> is not followed, with the result that

adjustment of one or more values in the phase angle set is required. It appears, however, that the generation

of good CH2 chemical shift correlation subspectra by either the 2D DEPT or 2D POMMIE methods requires

use of more time-consuming Pascal computations in the floating-point mode.

13. QA Activities for the National Cancer Institute: Establishment of an Accuracy Base for

Measurements of Micronutrients in Serum

J. Brown-Thomas, R.G. Christensen, N.E. Craft, M.C. Kline, W.E. May, W.A. MacCrehan, R.

Paule, and R. Schaffer

Forthe pastfour years, the Center for Analytical Chemistry has operated a multi-component quality assurance

program for laboratories that measure serum and plasma levels of selected fat- and water- soluble vitamins,

zinc and selenium as part of investigations supported by the National Cancer Institute, Division of Cancer

Prevention and Control, to study the possible cancer-prevention benefits of these micronutrients in

populations of humans at high risk of contracting certain forms of cancer.

Two of the main components of the program have been (1) interlaboratory proficiency testing, and (2)

reference materials development. Serum-based samples with assigned values for the target analytes are

distributed to participating laboratories (10-35 depending on the analyte) three times during the course of

the year. The labs receive feedback concerning their performance and suggestions for improving their

measurement capabilities on an as needed basis. The results from the proficiency testing exercises (round

robins) are used to establish a laboratory performance database for use by NCI to evaluate the quality of the

analytical data from which clinical conclusions are to be drawn, in addition to assessing lab performance,

the program is designed to provide a framework for assisting laboratories in improving their measurement

capabilities. During the past year, serum-based reference materials with assigned values for retinol,

alpha-tocopherol and beta-carotene were developed and distributed, along with instructions for their use, to

the labs for use as controls. The assigned values were based on the mean from the interlaboratory grand

average and two independent NIST measurement procedures. The uncertainty associated with the assigned

value derived from this process was in the 4-6% range.

99
Use of the value-assigned reference materials provided to the labs had a significant impact on the quality of

the data obtained from the round-robin exercise conducted several months after their distribution. For retinol

measurements, the relative standard deviation of the interlaboratory measurement had been 12-1 5% for the

past two years. The relative standard deviation of results from the most recent round robin dropped to 8-9%.

Approximately 67% of the participating labs reported results that were to be acceptable (i.e., results on all five sera provided were biased by <15%). In the previous round robin, results from five laboratories were

unacceptable (data biased by >30%). In the most recent exercise, three of these five laboratories reported

results with biases of 10%; one laboratory dropped out of the program; one laboratory again reported

unacceptable results. The one laboratory that again reported unacceptable resuits did not run the control

materials.

For alpha-tocopherol measurements, the relative standard deviation for the interlaboratory measurements

was 12-15% for the past year. The relative standard deviation of results for the most recent round robin

dropped to 8-1 0%. Approximately 60% of the participating laboratories reported results that were acceptable.

None of the laboratories reported results that were unacceptable.

For beta-carotene, interlaboratory precision improved from 20% to 15% in the most recent round robin. In the most recent round robin, the four labs that reported unacceptable data did not run the control materials

provided to them.

The data from the most recent fat-soluble vitamins round robin exercise clearly demonstrate the benefit of

value-assigned reference materials in improving interlaboratory measurement quality.

14. Preliminary Investigations Directed Toward the Development of Reference Materials for PNA

Adducts in Body Fluids

D.J. Reeder and M.C. Kline

As part of the Department of Energy’s interest in adverse effects of environmental pollutants from fossil energy

sources, we have started a project to develop reference materials for DNA adducts. Preliminary studies

included literature searches and a visit to several national laboratories to assess the analytical methods being

developed for sensitive detection of DNA adducts. We have also established methods for separating DNA

by HPLC and have qualified a system for DNA characterization by electrophoresis.

For highly sensitive measurements of PAH-DNA adducts, fluorescent line narrowing is performed with a high-powered pulsed dye laser with the sample cooled to 4 K with liquid helium at Ames Labs. At Battelle,

researchers are performing separations by reversed phase LC with adduct detection by on-line fluorescence

measurements. Measurements are also made by gas chromatography on derivatized adduct materials

(measuring tetrols), with detection by a mass-selective detector. At Argonne Labs, the techniques more

frequently involve in hemoglobin. They use the diol-epoxide of benzo[a] pyrene (BAP) to modify the

beta-chain of hemoglobin. Shifts in retention time are observed by HPLC with fluorescence detection.

As a starting point for providing materials to other laboratories, we plan to provide authentic DNA with varying

amounts of adducts starting with BAP, followed by chrysene and 5-methyl chrysene. In addition, we plan to

provide different sizes of DNA, and DNA adducts, given our present capabilities of separating DNA by HPLC

and characterizing electrophoretically (by size) yeast chromosomal pieces of DNA.

We also may consider making DNA adducts by a method employing rat liver homogenates. Rat liver is made

into a homogeneous slurry by treating with enzymes. This preparation is used to place adducts on calf

thymus DNA. About 10 mg of DNA, incubated with the cells from one rat, will yield about one or two

100
micrograms of adducted DNA. This procedure is required because of a possible need to have the

cytochrome P-450 system coupled with the aryl hydrocarbon hydroxylase (AHH) enzyme system, which is responsible for the adducting of polycyclic aromatic hydrocarbons to DNA.

15. Protein Modulation Studies of Human Colon Tumor Cell Line HT-29

D.J. Reeder and J.J. Edwards

In a collaborative study with Dr. Martin Lipkin of the Memorial Sloan-Kettering Cancer Center, we have applied our capabilities for separating and quantifying small amounts (picograms) of proteins to investigating the

modulation of selected proteins in human colon cancer cells. The human colon tumor cell line HT-29 has

been extensively studied by researchers at Sloan-Kettering and is known to undergo, under chemical

treatment, a transformation from normal pathology through a pre-cancerous state to that of a carcinoma.

We received two sets of cells treated with sodium butyrate as inducing agent from Dr. Lipkin’s laboratory.

Each set consisted of untreated controls, treated samples taken at various time intervals up to 96 h, and a

96 h untreated control.

Cells from the 5 mM butyrate treated set and controls were chosen for initial analysis. It was assumed that

each cell pellet contained 2 to 3 million cells which we solubilized by sonication in a dissolution buffer.

Electrophoretic separation by isoelectric focusing in the first dimension was performed in duplicate on all samples. The gels containing the focused proteins were then equilibrated for separation on SDS slab gels

in the second dimension.

Separated proteins were visualized following silver staining. Gels from each time period were then analyzed

by digital imaging on the Biol mage Visage system. Image analysis included global quantification of all spots

on each gel and automatic gel matching (between control and experimental samples). Information archived

on a spot list for each gel included spot number, x and y coordinates, integrated intensity, area, and shape.

We found at least 14 proteins that changed significantly after being treated by the inducing agent. Four of

the proteins which were not present in control cells were rapidly induced and peaked in intensity at twelve

to twenty-four hours. Five other proteins, which were present in the control cells, disappeared or became

very faint by twelve to twenty-four hours. Of the other proteins observed, a more gradual appearance or disappearance was noted.

Correlations of molecular weight and isoelectric point information with protein modulation are currently being

made. Future investigations will focus on identification of the proteins through immunological means or by

performing peptide sequencing of the N-terminal amino acids. This information will be useful in correlating

the known details about the genetic makeup and gene sequences of HT-29 cells with the proteins being

regulated and modulated in these experiments. This work may have an important impact in determining

efficacy of cancer-modifying agents.

101
16. Establishment of a New Five-Year AgreemeriS with EPA for of

W.E. May

The Environmental Monitoring Systems Laboratory of the Environmental Protection Agency at Las Vegas,

(EMSL-LV) has the responsibility for providing reference materials to support EPA’s hazardous v/aste

program. Because of the nature of the problems inherent in preparation of the reference materials needed

to address this mission, EPA’s EMSL-LV, in 1982, established the first of two interagency agreements with

NBS to provide technical advice and prepare several of the reference materials needed in this program.

During the period covered by the first five-year agreement, several reference materials were prepared and

delivered to EPA EMSL-LV for their internal QA use including: PCBs in serum, organics in a liquid sludge,

organics in a solid sludge, phenols and phthalates in urine, and volatile organics in whole blood.

During the past year, a new five-year agreement has been put in place which establishes a formal program

for NIST to work with the EMSL-LV to develop reference materials for (1 ) solid and liquid wastes and (2) body

fluids, with certified values for selected organic constituents. These materials will be called EPA/NIST

Reference Materials and will be distributed to the entire measurement community through sales by the NIST

Office of Standard Reference Materials. EMSL-LV will receive 1 0% of each reference material lot for their

internal use. The protocols used for certification of these materials will be comparable to those used to certify

NIST SRMs, and the funds recovered v^ill be utilized to reissue these reference materials when necessary.

The first of these EPA/NIST Reference Materials will be "Cotinine in Freeze Dried Urine". Cotinine

(5-3’-pyridyl)-1-methy!pyrrolidone-2) is a major metabolite of nicotine that is commonly measured to

determine the impact of passive exposure of non-smokers to side-stream cigarette smoke, it has a biological

half-life of approximately 20 hours, is found in both the blood serum and urine of smokers, and has been

shown to be linearly related to nicotine intake. This material consists of three lots of freeze-dried urine at

different cotinine concentrations: (1) a blank level, containing cotinine at < 1 ppb, (2) a low level, containing

cotinine at approximately 50 ppb, and (3) a high level, containing cotinine at approximately 500 ppb. The

low, and high levels were prepared gravimetricaliy by spiking the blank urine with known quantities of cotinine

perchlorate. The gravimetric values were verified by GC/MS.

17. Determination of the Catalytic ActivityLOf Aspartate Aminotransferase (AST) Reference MaMal

(RM 84301

J.J. Edwards

Aspartate aminotransferase (AST) is present in most animal and plant tissues. In mammals, highest levels

of AST are in liver, muscle and nerve tissue. Two distinct forms of AST exist; a soluble cytoplasmic isoenzyme

and a mitochondrial isoenzyme. The cytoplasmic form is present in circulating erythrocytes and exhibits

kinetic properties indistinguishable from the cytoplasmic forms found in liver and muscle, in most human

pathological disturbances associated with increased AST activities in serum (e.g., acute hepatitis, hepatic

malignancy, myocardial infarction) the predominant form found is cytoplasmic AST. Therefore, AST from

human erythrocytes give qualitatively and quantitatively similar reactions to the isoenzymes found in normal

serum and in the serum of most patients exhibiting an increased activity as a result of disease.

The work reported here was designed to measure the catalytic activity concentration of AST (AST E.C.2.6. 1.1)

and to provide a reference material (RM) for clinical laboratory use in evaluating and improving the precision

of AST assays. The project was coordinated by members of the National Committee for Clinical Laboratory

Standards (NCCLS) and by the Center for Analytical Chemistry. Two round robin exercises were conducted.

102
The second round-robin, in which the final activity values were determined, involved participants from seven

U.S. and three European laboratories. Material for analysis was a lyophilized form of cytoplasmic AST

isoenzymes obtained from human erythrocytes prepared by Dade/Baxter Travenol Inc., Miami, Florida. All cooperating laboratories used the International Federation for Clinical Chemistry (IFCC) reference method

for AST to assign a numerical value for enzyme activity concentration in terms of U/L. In each laboratory,

duplicate assays were performed on two vials of material on each of five days for a potential total of 200

discrete results. An analysis of variance with use of weighting factors gave a value for RM 8430 of 96.1 U/L

that has an uncertainty of ± 2.6 U/L. This activity concentration and uncertainty value is equivalent to 1602

± 43 nanokatals per liter. The reported concentration is a consensus value, i.e., the mean of results of the

ten participating laboratories. The uncertainty is two standard deviations of the mean and included an

allowance for observed vial-to-vial variability.

The details of this study are described In Clin. Chem. M: 450-9 (1988). Based on the findings of this study

an NBS certificate for RM 8430 has been Issued.

18. Development of SRMs for Marine Pollution Monitoring

S.N. Chesler, M.M. Schantz, B.J. Koster, R.M. Parris, R.E. Rebbert, and S.A. Wise

During the past three years, the National Oceanic and Atmospheric Administration (NO/\A) has supported

the development of both calibration solution and natural matrix SRMs to assist in providing an accuracy base

for their National Status and Trends monitoring program. Six calibration solution SRMs containing selected

polycyclic aromatic hydrocarbons (PAH), chlorinated pesticides, and polychlorinated biphenyls (PCB) have

been prepared and certified or are currently in progress. A marine sediment and mussel tissue material are

currently being prepared and certified as natural matrix SRMs for organic contaminant measurements.

The solution-based SRMs were developed to provide accurate calibration solutions to determine

chromatographic detector response factors and retention times primarily for gas chromatography (GC) and

gas chromatography-mass spectrometry (GC/MS). We have prepared a series of six calibration solutions

that contain selected members of the three compound classes of interest (PAH, PCB, and chlorinated

pesticides) at two concentration levels: SRM 1491 Aromatic Hydrocarbons in Hexane/Toluene, SRM 1492

Chlorinated Pesticides in Hexane, SRM 1493 Polychlorinated Biphenyls in2,2,4-Trimethylpentane, SRM 2260

Aromatic Hydrocarbons (Nominal 75 jxg/g Concentration) in Toluene, SRM 2261 Chlorinated Pesticides

(Nominal 3 ^g/g Concentration) in Hexane, and SRM 2262 Chlorinated Biphenyls (Nominal 3 pig/g

Concentration) In 2,2,4-Trimethylpentane. SRMs 1491 and 2260 contain 24 analytes: SRMs 1492 and 2261

contain 15 analytes; and SRMs 1493 and 2262 contain 20 and 28 PCB congeners, respectively. SRMs 2260,

2261, and 2262 were requested by NOAA and EPA to provide more concentrated solutions that could be

diluted to prepare multipoint calibration curves for quantitation. In addition, the higher levels of the

chlorinated pesticides and PCBs in SRMs 2261 and 2262 are sufficient to allow quantitation by GC/MS and

GC-flame Ionization detection (FID) rather than the more sensitive GC with electron capture detection (ECD).

Eight additional congeners, which were recommended by EPA, were included in SRM 2262 for use in

determining response factors for GC as specified in EPA Method 680. Certification of all the calibration SRMs

was based on GC and gravimetric measurements.

For the development of SRM 1941 Organics in Marine Sediment, a large quantity of sediment was collected

in Baltimore Harbor with the assistance of a NOAA contractor. This material was air dried, ground, sieved,

homogenized, and bottled in 60-g aliquots as the SRM. Measurements for the determination of PAH, by

GC-FID and LC with fluorescence detection, have been completed with good agreement between the two

techniques. About 10-12 PAH will be certified with concentrations ranging from about 200 ng/g for

anthracene to 1000-1100 ng/g for fluoranthene and pyrene. Selected PCB congeners and chlorinated

103
pesticides have been determined by GC-ECD and additional measurements by multidimensional GC will be

made In FV-89. Trace element analyses have been performed by neutron activation analysis to provide

noncertified information values.

The second SRM under development for use in monitoring marine pollution is SRM 1 974, Organics in Mussel

Tissue (Mytilus edulis). Approximately 3000 mussels were collected at two sites near Boston, MA:

Dorchester Bay in Boston Harbor and Buzzards Bay near New Bedford, MA. Aliquots of samples from the

two sites were homogenized and analyzed to determine the suitability of the materials as the proposed SRM.

After analysis of the samples by GC-MS, it was determined that the Dorchester Bay material had suitable

levels of the analytes of interest: PAH (e.g., fluoranthene and pyrene at 200 ng/g dry weight), RGBs (10-50

ng/g dry weight for individual PCB congeners), and chlorinated pesticides (10-20 ng/g dry weight for

4,4'-DDE, 4,4'-DDT, and 4,4'-DDD). The 28 kg of material from Dorchester Bay will be cryogenically

homogenized and distributed frozen in 15-g aliquots as SRM 1974. SRM 1974 will be the first tissue SRM

issued specifically for the determination of organic constituents and the first tissue to be issued as a fresh

frozen material rather than a dried material. SRM 1974 will have certified concentrations for selected PAH,

PCB congeners, and chlorinated pesticides. Homogenization and mixing of this material are currently in progress and analytical measurements (LC/fluorescenceand GC-MS for PAH; GC-ECD and multidimensional

GC-ECD for the PCB and pesticides) will commence at the beginning of FY-89.

19. Development of SRM 1597. Complex Mixture of Polycyclic Aromatic Hydrocarbons from Coal

lar

S.A. Wise, B.A. Benner, G.D. Byrd, R.E. Rebbert, and M.M. Schantz

Since 1933 when several polycyclic aromatic hydrocarbons (PAH) were isolated from coal tar and found to

be highly carcinogenic, PAH have been one of the most widely measured groups of environmental pollutants.

To assist in validating the accuracy of PAH measurements, several Standard Reference Materials (SRMs)

have been issued by the National Bureau of Standards since 1980 for use in the determination of these

compounds. These SRMs range in analytical difficulty from a simple calibration solution of the 16 priority

pollutant PAH (SRM 1647) to several complex, natural matrix materials such as shale oil (SRM 1580), crude

011 (SRM 1582), air particulate material (SRM 1649), and diesel particulate matter (SRM 1650). A new SRM,

which is intermediate in complexity when compared to existing SRMs, has been prepared and certified for

use in the determination of PAH. SRM 1597 Complex Mixture of Polycyclic Aromatic Hydrocarbons from

Coal Tar consists of a natural mixture of PAH isolated from a crude coke-oven tar and dissolved in toluene.

This complex combustion-related PAH mixture is suitable for direct analysis (i.e., without sample cleanup

or concentration) using such techniques as liquid chromatography (LC), gas chromatography (GC), or gas

chromatography-mass spectrometry (GC-MS).

For quantitation of the compounds in SRM 1 597, GC with flame ionization detection and LC with fluorescence

detection were used as the two independent analytical techniques. Certified concentrations are reported for

12 PAH, and concentrations for an additional 18 compounds are reported as informational values. SRM 1597

has the largest number of certified and informational values for PAH of any of the natural matrix SRMs. For

the majority of the compounds measured, both the GC and LC analyses were performed without

concentration or cleanup of the sample (i.e., direct analysis). Using a direct analysis LC method made it impossible to obtain accurate data for triphenylene or benzo[ghi]perylene because of low detection

sensitivity or selectivity. To obtain LC data for these two compounds, a normal-phase LC fractionation

procedure was employed to isolate separate fractions containing these components which were suitable for

reversed-phase LC analysis. Chrysene and triphenylene are not routinely quantified by GC analyses since

they coelute on conventional nonpolar stationary phases. To provide the necessary data from a second

104
technique for certification, these two isomeric PAH were determined by GC analysis on a liquid crystalline

stationary phase. SRM 1597 is the first SRM with certified concentrations for chrysene and triphenylene.

Approximately 60 compounds were identified in SRM 1597 based on molecular weight information from

GC-MS analysis and on the comparison of GC retention data with reference standards and literature data.

GC retention indices were determined for a number of the compounds in this material and are compared

with literature data on the Certificate of Analysis. In addition to the PAH, SRM 1 597 contains numerous other

polycyclic aromatic compounds as minor components, including sulfur heterocycles, nitrogen heterocycles,

and oxygen heterocycles. PAH mixtures from coal tar have already found use in a number of laboratories

for the evaluation of gas chromatographic performance (e.g., column efficiency and/or selectivity).

Therefore, SRM 1597 will serve as a common reference sample for such comparisons among laboratories.

The preparation and certification of this SRM have been described recently in Anal. Chem. 60:887-894 (1 988).

20. Development of SRMs for Cholesterol in Human Serum

P.M. Ellerbe, L.T. SniegoskI, M.J. Welch, and E. White V

Large epidemiological studies have shown a direct link between the level of cholesterol in a person’s

and their risk of coronary heart disease. Since heart disease is the number one cause of mortality

United States, a major effort is underv\/ay to make people aware of the importance of knowing their

cholesterol levels and taking appropriate action if the level is too high.

The accurate measurement of cholesterol levels in serum is a matter of public concern. Proficiency testing

programs have shown wide discrepancies in cholesterol results among clinical laboratories and among the

commonly used methods. Reference materials with accurately determined concentrations of cholesterol in

appropriate matrices are an important component in assessing the quality of measurements in clinical

laboratories. In cooperation with the College of American Pathologists and the Centers for Disease Control,

NIST has developed such a series of Standard Reference Materials (SRMs) for human serum.

Two new serum-based SRMs have been certified for total cholesterol in the past year. One of these (SRM

1951) consists of three levels (210, 242, and 282 mg/dL) in a frozen serum matrix. The other (SRM 1952)

consists of three levels (207, 262, and 357 mg/dL) in a freeze-dried serum matrix. Because of the demand

for these SRMs, 1 952 sold out within a few months and 1 951 is selling rapidly. A replacement material, SRM

1 952a, consisting of three levels in a freeze-dried serum, is now being certified. Certification is also underway

for SRM 909a, a replacement material for SRM 909, a freeze-dried serum certified for a large number of

organic and inorganic analytes. This new material will have two levels of all of these analytes. The certification

measurements for total serum cholesterol are made using the isotope dilution mass spectrometric definitive

method. This method has been carefully and thoroughly tested for sources of bias and imprecision, and

found to exceed the guidelines for accuracy and precision recommended for definitive methods. Briefly, the

method involves the following steps: (1) A known weight of cholesterol-^ ^Cs is added to a known weight of

serum; (2) the serum is subjected to alkaline hydrolysis to free cholesterol from its esters; (3) the cholesterol,

both labeled and unlabeled, is extracted and converted to a trimethylsilyl derivative; (4) the derivatized

material is injected into a GC/MS system equipped with a fused silica capillary column with a nonpolar bonded

phase; (5) the mass spectrometer is set to monitor the intensities of the molecular ions for the unlabeled and

labeled cholesterol derivative; (6) standard mixtures consisting of known amounts of pure unlabeled

cholesterol (SRM 911a) and cholesterol-^ are measured immediately before and after each sample to

bracket the sample in both ratio and time. Each sample is measured twice with the order of bracketing

standards reversed. A subset of each group of samples is remeasured using different ions and/or different

chromatographic conditions as a test for bias in the original measurements. Because of the soundness of

blood

in the

blood

105
the procedure and the careful attention to detail in the sample preparation and measurements, we routinely

achieve results with relative standard deviations of < 0.4% and no evidence for systematic bias.

The availability of such matrix reference materials with accurately determined analyte concentrations

provides a means for evaluating and improving the accuracy of field methods used in clinical laboratories.

21. Development of SRMs for Drugs of Abuse in Urine

G.D. Byrd, N.E. Craft, R. Espinosa-Leniz, LR. Hilpert, S. Tai, and M.J. Welch

Substance abuse is a major concern in the United States. The number of organizations, both public and

private, which require drug testing for employees and job applicants is rapidly growing. The repercussions

of a positive test for drugs of abuse can be enormous, thus it is imperative that drug testing be highly accurate.

It is generally recognized that screening tests cannot be considered positive unless they are confirmed by

gas chromatography/mass spectrometry (GC/MS). GC/MS can generally provide unambiguous

identification of drugs of abuse in urine samples and can, with proper procedures, provide accurate

quantitation of the amount present. One major component in quality assurance for drug testing programs

is the use of reference materials to demonstrate that methods are being properly run.

We are involved in a program to develop and certify urine-based Standard Reference Materials for drugs of

abuse. The first of these materials, SRM 1 507, consists of two vials of freeze-dried urine with approximately

20 ng/mL (when reconstituted) of 1 1 -nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-9-COOH), the

primary urinary metabolite of the psychoactive component of marijuana. The SRM also includes a vial of a

blank urine. Certification of this material was recently completed and involved the use of a GC/MS method

and an HPLC method.

The GC/MS method used for certification involved spiking a 10-mL aliquot of the reconstituted urine with a

deuterated analog of the metabolite, isolating the analyte and internal standard with a solid phase extractor,

converting them to the trimethylsilyl (TMS) derivatives, and injecting the derivatized sample into the GC/MS

system for measurement. The GC was equipped with a 30-meter fused silica capillary column with a

non-polar bonded phase. The mass spectrometer was a single quadrupole instrument operated in the

electron impact mode at 70 eV with an ion source temperature of 200 °C. The molecular ions .at m/z 488

and 491 were monitored. Response factor solutions consisting of known amounts of the analyte and internal

standard (as the TMS derivatives) were run frequently for calibration. A total of 24 vials (one randomly

selected from each tray of vials produced) were analyzed in duplicate, yielding a concentration for the analyte

of 19.9 ± 0.6 ng/mL.

The HPLC method involved spiking a 1 0-mL aliquot of the reconstituted urine with the 1 1 -hydroxy isomer of

the analyte, extracting the analyte and internal standard with 3% isobutanol in hexane, evaporating this phase,

and dissolving the residue in methanol. The samples were analyzed by reversed-phase HPLC with a monomeric Cis analytical column and a mobile phase gradient. An electrochemical detector operated in the oxidative mode at -M.O V vs. the AgCI reference electrode was used for measurement. A total of 10

aliquots from 6 vials were analyzed, yielding a concentration of 19.7 ± 0.4 ng/mL. Based upon the GC/MS

and HPLC results, and an allowance for possible systematic error, the certified concentration for this SRM

is 20 ± 1 ng/mL. The blank urine contained less than 1 ng/mL of THC-9-COOH.

Certification measurements are now in progress for the second SRM in this program. This material consists

of three levels each of cocaine and two of its urinary metabolites, benzoylecgonine and methylecgonine plus

a blank urine. This freeze-dried material Is being developed in cooperation with the College of American

Pathologists (CAP), who will use part of the lot in their accreditation program for laboratories engaged in

106
testing for drugs of abuse. As with the marijuana metabolite, the certification process involves two

independent methods, isotope dilution GC/MS and HPLC for both cocaine and benzoylecgonine. Because

of difficulties in obtaining and analyzing pure samples of methylecgonine, this analyte will not be certified at

this time, but its gravimetric value will be provided as an information value.

Future plans include more cooperative projects with the CAP to develop reference materials for drugs of

abuse. The next analyte for both organizations will probably be phencyclidine (PCP).

22. The Expanded Role of the NIST Specimen Banking Program

S.A. Wise, B.J. Koster, R.M. Parris, M.M. Schantz, S.F. Stone, and R.L Zeisler

In 1979 the Center for Analytical Chemistry (CAC), in conjunction with the U.S. Environmental Protection

Agency (EPA), established a Pilot Environmental Specimen Bank Program to determine the feasibility of

long-term storage of environmental samples. Human liver specimens were selected as the first sample type

to be included in this pilot program. Over 550 liver specimens have been collected and stored in the specimen

bank facility since 1980. In recent years, interest in the concept of environmental specimen banking, i.e., the

archiving of biological specimens for retrospective analysis, has increased as such activities have been

recognized as an important complement to traditional environmental pollution monitoring programs. As a

result of this increasing interest, specimen banking activities at NIST have expanded beyond the original pilot

effort to include a variety of specimens.

For the past three years, the National Oceanic and Atmospheric Administration (NOAA) has sponsored the

banking and analysis of marine samples from their National Status and Trends Program. These marine

specimens include mussels and oysters, sediment, fish muscle, and fish liver. In 1987, we initiated a project

with the Alaska Office of NOAA to archive tissues from Alaskan marine mammals such as seals, walrus, and

whales. During 1987 and 1988, specimens of blubber, liver, and kidney from two different species of seals

(Northern fur seals and ringed seals) were collected on the Pribilof Islands and at Point Barrow, Alaska.

Two additional programs within CAC also have minor specimen banking activities associated with them. As

part of the quality assurance program for the National Cancer Institute’s (NCI) Micronutrient Measurement

Program, human serum samples have been banked to evaluate the long-term storage stability of

micronutrients (e.g., vitamins and trace elements) in these specimens. Finally, as part of a joint effort with

the Food and Drug Administration (FDA), U.S. Department of Agriculture (USDA), and the International

Atomic Energy Agency (IAEA), we are investigating the stability of human diet samples stored in the bank.

These four projects, combined with the original EPA Pilot Environmental Specimen Bank project, now make

up the National Biomonitoring Specimen Bank. The different projects have allowed NIST to gain experience

in sample collection, processing, long-term sample stability under various storage conditions, analysis, and

quality assurance for a variety of specimen types. As part of the development of specimen collection

protocols, NIST scientists have assisted in the field during sample collection to implement and modify the

sampling procedures as required for the specific circumstances.

Approximately 20% of the archived specimens in each of these projects are homogenized and analyzed to

provide accurate baseline concentrations for selected trace elements and organic constituents. These

baseline data are used for sample stability studies, for comparison with similar data from other laboratories,

and for long-term trend monitoring. Analytical data for selected trace elements and organic contaminants

(e.g., chlorinated pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons) are available

on about 100 human liver specimens; fish tissue, mussels, oysters, and sediment from about 20 U.S. coastal

sites; and selected seal tissues.

107
Asa result of these increasing specimen banking-related activities, the NIST specimen bank facility is currently

being expanded and upgraded. The addition to the specimen bank facility wili increase the current storage

capacity by a factor of three, thereby ailowing the National Biomonitoring Specimen Bank to continue to serve as a resource for national monitoring programs.

108
C. Outputs and Interactions

(Organic Analytical Research Division)

1. Publications

Alexander, LA., Reeder, D.J., and Budowle, B., A Method for Routinely Producing High Resolution Black

and White Journal Quality Photographs of Electrophoretic Gels, J. Forensic Sciences, (in press).

Becker, P.R., Wise, S.A., Koster, B.J., and Zeisler, R.L, Alaskan Marine Mammal Tissue Archival Project:

A Project Description Including Collection Protocols, NBSIR 88-3750, 1988.

Brown, E.D., Micozzi, M., Craft, N.E., Bieri, J.G., Beecher, G., Edwards, B., Rose, A., and Smith, J.C., Jr., Changes in Plasma Carotene in Normal Men After a Single Ingestion of Vegetables or Pure

Beta-Carotene, Am. J. Clin. Nutr., (in press).

Brown-Thomas, J.M., Moustafa, A.A., Wise, S.A., and May, W.E., The Determination of Fat-Soluble Vitamins

in Oil Matrices by Multidimensional High Performance Liquid Chromatography, Anal. Chem., (in

press).

Byrd, G.D., Craft, N.E., and Hilpert, L.R., Preparation and Certification of SRM 1507:

11-Nor-9-Tetrahydrocannabinol-9-Carboxylic Acid in Freeze-Dried Urine, Anal. Chem., ( in press).

Chang, H., Nishioka, M., Bartle, K.D., Wise, S.A., Bayona, J.M., Markides, K.E., and Lee, M.L, Identification

and Comparison of Low Molecular-Weight Neutral Constituents in Two Different Coal Extracts, Fuel

SZ, 45-57 (1988).

Coxon, B., Two-Dimensional POMMIE J [CH]-Resolved ^^C NMR Spectrum Editing, Application to Peptide

and Carbohydrate Derivatives, Magnetic Resonance in Chemistry 2£, 1449 (1988).

Craft, N.E., Brown, E. D., and Smith, J.C., Jr., Effects of Storage and Handling on Concentrations of

Individual Carotenoids, Retinol, and Tocopherol in Plasma, Clin. Chem. 24, 44-48 (1988).

Durst, R.A., Koch, W.F., and Wu, Y.C., pH Theory and Measurement, Ion-Selective Electrode Reviews 9,

173-196 (1987).

Durst, R.A., Hertz, H.S., and Velapoldi, R.A., Eds., Accuracy in Trace Analysis - Accomplishments, Goals,

Challenges, J. Res. NBS 92, U.S. Govt. Printing Office, Washington, 360, (1988).

Durst, R.A., Locascio-Brown, L, Plant, A.L, and Brizgys, M.V., Liposome-Enhanced Flow Injection

Immunoanalysis, Clin. Chem., 34, 1700-1701 (1988).

Ellerbe, P., Cohen, A., Welch, M.J., and White V, E., The Stability of Uric Acid in Ammonium Hydroxide,

Clin. Chem., (in press).

Epier, K.S., O’Haver, T.C., Turk, G.C., and MacCrehan, W.A., Laser-Enhanced Ionization as a Selective

Detector for Liquid Chromatography: Application to the Determination of Alkyltins in Sediment,

Anal. Chem., (in press).

109
Fatsads, AJ., Facile Synthesis of 1 -Nitropyrene-dg of High Isotopic Purity, Journal of Labeled Compounds,

(in press).

Fatiadi, A.J., New Synthetic Applications of Organoiron Complexes, Synthesis, (in press).

Gomiscek, S., Veber, M., Francetic, V., and Durst, R.A., Electrochemical Studies of Dithiocarbamates and

Related Compounds, Accuracy in Trace Analysis - Accomplishments, Goals, Challenges, J. Res.

NBS 92, U.S. Govt. Printing Office, Washington, 496-497 (1988).

Guenther, F.R., Chester, S.N., Gordon, G.E., and Zoller, W.H., Residential Wood Combustion: A Source

of Atmospheric Polycyclic Aromatic Hydrocarbons, J. High Resolut. Chromatogr. and Chromatogr.

Commun., (in press).

Kannuck, R.M., Bellama, J.M., and Durst, R.A., Measurement of Liposome-Released Ferrocyanide by a

Dual-Function Polymer Modified Electrode, Anal. Chem. SQ, 142-147 (1988).

Kannuck, R.M., Bellama, J.M., Blubaugh, E.A., and Durst, R.A., Crosslinked Po!y(viny!ferrocene)-Modified

Reference Electrode for Nonaqueous Electrochemistry, Anal. Chem. 59, 1473-1475 (1987).

Kannuck, R.M., Bellama, J.M., and Durst, R.A., Homogeneous Electrochemical Immunoassay Using a

Chemically Modified Electrode, Accuracy in Trace Analysis - Accomplishments, Goals, Challenges,

J. Res. NBS 92, U.S. Govt. Printing Office, Washington, 506-508 (1988).

Lauenstein, G.G., Wise, S.A., Zeisler, R.L, Koster, B.J., Schantz, M.M., and Golembiewska, S.L, National

Status and Trends Program for Marine Environmental Quality Specimen Bank Project: Field

Manual, NOAA Technical Memorandum NOS OMA, 37, Rockville, MD (1987).

Locascio-Brown, L, Plant, A.L., and Durst, R.A., Behavior of Liposomes in Flow Injection Systems, Anal.

Chem. 62, 792-797 (1988).

MacCrehan, W.A. and Brown-Thomas, J.M., Determination of Phenols in Petroleum Crude Oils.using Liquid

Chromatography with Electrochemical Detection, Anal. Chem. 59, 477-479 (1987).

MacCrehan, W.A. and Schonberger, E., Reversed-Phase HPLC Separation and Electrochemical Detection

of Retinol and Its Isomers, J. Chromatogr. 417. 65-78 (1987).

MacCrehan, W.A. and Schonberger, E., Determination of Retinol, a-Tocopherol, and p-Carotene in Serum

by Liquid Chromatography with Absorbance and Electrochemical Detection, Clin. Chem, 22,

1585-1592 (1987).

MacCrehan, W.A., May, W.E., Yang, S.D., and Benner, B.A., Determination of Nitro Polynuclear Aromatic

Hydrocarbons in Air and Diesel Particulate Matter Using Liquid Chromatography with

Electrochemical and Fluorescence Detection, Anal. Chem. 5Q, 194-199 (1988).

MacCrehan, W.A., Yang, S.D., and Benner, B.A., Catalytic Oxygen Scrubber for Liquid Chromatography.

Anal. Chem. 62. 284-286 (1988).

110
MacCrehan, W.A. and Shea, D., Separation of Hydrophilic Thiols Using Reversed-Phase Chromatography

with Trihaloacetate Buffers, J. Chromatogr., (in press).

Margolis, S.A., Coxon, B., Gajewski, E., and Dizdaroglu, M., Structure of a Hydroxyl Radical-Induced

Crosslink of Thymine and Tyrosine, Biochemistry, (in press).

Margolis, S.A. and Davis, T.P., The Stabilization of Ascorbic Acid in Human Plasma and Its Measurement

by Liquid Chromatography, Clin. Chem., (in press).

Marrese, C.A., Blubaugh, E.A., and Durst, R.A., Chemical Modification of Pt Electrodes by Tetr(4-Pyridyl)

Porphyrin Through Siloxane Polymer Formation, J. Electroanal. Chem. 243. 193-201 (1988).

Mattammal, M.B., White V, E., Lakshmi, W.M., Zenser, T.V., and Davis, B.B., Mass Spectral Identification

of 2-Amino-4-[5-nitro-2-furyl] thiazole Metabolites, Biomed. Environ. Mass Spectrom. 1&, 495-9

(1988).

May, W.E., Development of SRMs for Environmental Trace Organic Analysis, Proc. of International

Symposium on Trace Analysis in Environmental Samples and SRMs, (in press).

Parris, R.M., Chesler, S.N., and Wise, S.A., Improved Analytical Methodology for the Determination of PCBs

and Pesticides in Human Liver Specimens, in Progress in Environmental Specimen Banking, MBS

Spec. Publ. 740, U.S. Government Printing Office, Washington, DC, 40-52 (1988).

Plant, A.L, Locascio-Brown, L, Brizgys, M.V., and Durst, R.A., Liposome-Enhanced Flow Injection

Immunoanalysis, BioyTechnology £, 266-269 (1988).

Plant, A.L, Brizgys, M.V., Locascio-Brown, L, and Durst, R.A., Generic Liposome Reagent for

Immunoassays, Biochimica et Biophysica Acta, (in press).

Pratt, K.P., Kingston, H.M., MacCrehan, W.A., and Koch, W.F., Voltammetric and Liquid Chromatographic

Identification of Organic Products of Microwave Assisted Wet Ashing of Biological Samples, Anal.

Chem., (in press).

Sander, LC. and Wise, S.A., Determination of Column Selectivity Toward Polycyclic Aromatic

Hydrocarbons, J. High Resolut. Chromatogr. and Chromatogr. Commun. H, 383-387 (1988).

Sander, LC. and Wise, S.A., Effect of Phase Length on Column Selectivity for the Separation of Polycyclic

Aromatic Hydrocarbons by Reversed-Phase Liquid Chromatography, Anal. Chem. 52, 2309-2313

(1987).

Sander, L.C., Preparation of Glass Columns for the Demonstration of Reversed-Phase Liquid

Chromatography, J. Chem. Educ. 65, 373-374 (1988).

Sander, L.C., Evaluation of Column Performance in Liquid Chromatography, J. Chromatogr. Sci., (in

press).

Sander, LC. and Wise, S.A., Recent Advances in Bonded Phases for Liquid Chromatography, CRC Crit.

Rev. Anal. Chem. 15_(4), 299-413 (1987).

Ill
Schantz, M.M., Chesler, S.N., Koster, B.J., and Wise, S.A., Analytical Methods for the Determination of

Organic Contaminants in Marine Sediments and Tissues, in Progress in Environmental Specimen

Banking, NBS Spec. Publ. 740 U.S. Government Printing Office, Washington, DC, 10-18 (1988).

Shea, D. and MacCrehan, W.A., Determination of Hydrophilic Thiols in Sediment Porewater using Ion-Pair

Liquid Chromatography Coupled to Electrochemical Detection, Anal. Chem. SQ, 1449-1454 (1988).

Shea, D. and MacCrehan, W.A., Role of Biogenic Thiols In the Solubility of Sulfide Minerals, Sci. Total

Environ., (in press).

Sniegoski, L.T., Ellerbe, P., Welch, M.J., and White V, E., Determination of Total Cholesterol in Coconut

Oil Using an Isotope Dilution Gas Chromatography-Mass Spectrometric Method, J. Agric. & Food

Chem., (in press).

Sniegoski, L.T., Byrd, G.D., and White V, E., Synthesis of 3-Quinuclidinol-^®0, Benzilic-ds Acid, and

3-Quinuclidinyl-^®0 Benzilate-ds, J. Labelled Compounds and Radio-Pharmaceuticals, (in press).

Stalcup, A.M., Wise, S.A., and Martire, D.E., A Thermodynamic Comparison of Monomeric and Polymeric

Ci8 Bonded Phases using Aqueous Methanol and Acetonitrile Mobile Phases, J. Chromatogr. 442.

1-14(1988).

Syty, A., Christensen, R.G., and Rains, T.C., Determination of Added Chromium (111) and Chromium (VI) in Natural Water by Ion-Pairing High Performance Liquid Chromatography with Detection by Atomic

Absorption Spectrometry, J. of Anal. Spectro. 2, 193 (1988).

Velapoldl, R.A. and Durst, R.A., Accuracy in Trace Analysis (Meeting Report), TRAC 7, 49 (1988).

Welch, M.J. and Hertz, H. S., The How and Why of an Accuracy Base for Proficiency Testing Programs,

Arch. Pathol. Lab. Med. 112, 343-345 (1988).

Wise, S.A., Benner, B.A., Byrd, G.D., Chesler, S.N., Rebbert, R.E., and Schantz, M.M., Determination of

Polycyclic Aromatic Hydrocarbons in a Coal Tar Standard Reference Material, Anal. Chem. SQ,

887-894 (1988).

Wise, S.A., Benner, B.A., Liu, H., Byrd, G.D., and Colmsjo, A., Separation and Identification of Polycyclic

Aromatic Hydrocarbon Isomers of Molecular Weight 302 in Complex Mixtures, Anal. Chem. SQ,

630-637 (1988).

Wise, S.A., Sander, L.C., Chang, H.K., Markides, K.E., and Lee, M.L, Shape Selectivity in Liquid and Gas

Chromatography: Polymeric Octadecylsilane and Liquid Crystalline Stationary Phases,

Chromatogr. 2S, 473-479 (1988).

Wise, S.A., Zeisler, R.L, and Goldstein, M., Eds., Progress in Environmental Specimen Banking, NBS Spec.

Publ. 740, U.S. Government Printing Office, Washington, DC (1988).

Wise, S.A., Hilpert, L.R., Rebbert, R.E., Sander, L.C., Schantz, M. M., Chesler, S. N., and May, W. E., Standard Reference Materials for the Determination of Polycyclic Aromatic Hydrocarbons, Fres. Z. Anal. Chem., (in press).

112
Wise, S.A., Koster, B.J., and Zeisler, R.L, Status of Specimen Banking Activities at the National Bureau of

Standards, in Progress in Environmental Specimen Banking, NBS Spec. Publ. 740 U.S. Government

Printing Office, Washington, DC, 10-18 (1988).

Wu, Y.C., Koch, W.F., and Durst, R.A., Standard Reference Materials: Standardization of pH

Measurements, Revised Edition, NBS Spec. Publ., 260-53, Washington, pp. 56, (1988).

2. Talks

Benner, B.A., "Sampling and Determination of Gas- and Particle-Phase Compounds Emitted by Motor

Vehicles in a Roadway Tunnel," The 195th American Chemical Society Meeting and The Third

Chemical Congress of North America, Toronto, Canada, June 7, 1988.

Brown, L, "Liposome-Based Flow Injection Immunoassay System," Symposium on Accuracy in Trace

Analysis- Accomplishments, Goals, and Challenges, National Bureau of Standards, Gaithersburg,

MD, October 1, 1987.

Brown, L., "The Use of Liposomes in Continuous Immunoanalysis," American Association of Medical

Instrumentation, Washington, DC, May 17, 1988.

Brown-Thomas, J.M., "Chromatography," Seneca Valley High School, Germantown, MD, November 12,

1987.

Brown-Thomas, J.M., "Careers for Women in Science," Takoma Park intermediate School, Silver Spring,

MD, November 19, 1987.

Brown-Thomas, J.M., "Chromatography," Westland Intermediate School, Bethesda, MD, January 13, 1988.

Brown-Thomas, J.M., "Science," Glen Haven Elementary School, Silver Spring, MD, February 2, 1988.

Brown-Thomas, J.M., "Chromatography," Blair High School, Silver Spring, MD, April 18, 1988.

Brown-Thomas, J.M., "What is a Chemist?," St. John School, Columbia, MD, May 27, 1988.

Brown-Thomas, J.M., "Stability of Fat-Soluble Vitamins in Human Serum as Determined by High

Performance Liquid Chromatography," 102nd Annual International Meeting of the Association of

Official Analytical Chemists, Palm Beach, FL, August 30, 1988.

Christensen, R.G., "Determining the Purity of ’Pure’ Materials," Indiana University of Pennsylvania,

Chemistry Department, Indiana, PA, February 5, 1988.

Coxon, B., "Two-Dimensional NMR Spectrum Editing of Carbohydrates," The 195th American Chemical

Society Meeting and The Third Chemical Congress of North America, Toronto, Canada, June 8,

1988.

Craft, N.E., "HPLC-EC Determination of 11-Nor-Delta-9-Tetrahydrocannabinol-9-Carboxylic Acid in SRM

1507: 11-Nor-Delta-9-THC-9-Carboxylic Acid in Lyophilized Urine," Annual Meeting of Federation

of American Societies for Experimental Biology, Las Vegas, NV, May 5, 1988.

113
Durst, R.A., "Liposome-Enhanced Flow Injection Immunoanalysis System," University of Houston,

Department of Chemistry, Houston, TX, January 16, 1988.

Durst, R.A., "Liposome-Enhanced Flow Injection Immunoanalysis," The Oak Ridge Conference on

Advanced Analytical Concepts for the Clinical Laboratory, Savannah, GA, April 14, 1988.

Durst, R.A., "Dual-Function Polymer-Modified Electrode for the Measurement of Liposome-Released

Ferrocyanide," The 195th., Toronto, Canada, June 7, 1988.

Edwards, J.J., "Separation and Characterization of Fibronectic Domains by Two-Dimensional Gel

Electrophoresis," Electrophoresis Society, Charleston, SC, June 15, 1988.

Espinosa-Leniz, R., "A Solid Phase Extraction Method for GC/MS Analysis of Cocaine and its Major

Metabolites in Urine," American Society for Mass Spectrometry, Annual Meeting, San Francisco,

CA, June 9, 1988.

Guenther, F.R., "Residential Wood Combustion: A Source of Atmospheric Polycyclic Aromatic

Hydrocarbons," Ninth International Symposium on Capillary Chromatography, Monterey, CA, May

19, 1988.

Koster, B.J., 'Technical Improvements in the Operation of the U.S. National Biomonitoring Specimen Bank

Facility," 11th U.S.-German Seminar of State and Planning for Environmental Specimen Banking,

Bayreuth, Bavaria, Federal Republic of Germany, May 3, 1988.

Margolis, S.A., "Stabilization of Ascorbic Acid in Serum and Its Measurement by HPLC," Annual Meetings

of Federation of American Societies for Experimental Biology, Las Vegas, NV, May 5, 1988.

Margolis, S.A., "Structure of Thymine-Tyrosine Dimer," 14th International Congress of Biochemistry,

Prague, Czechoslovakia, July 15, 1988.

May, W.E., "Development of SRMs for Environmental Trace Organic Analysis," First International

Symposium on Trace Analysis In Environmental Samples and SRMs, Honolulu, HI, January 6, 1988.

May, W.E., 'The Aqueous Solubility Behavior of Polycyclic Aromatic Hydrocarbons," University of

Maryland, College Park, MD, February 4, 1988.

May, W.E., "NIST: What is it?? Where is it?? and What do they do??," Alabama A&M University, Chemistry

Department, Huntsville, AL, February 5, 1988.

May, W.E., "Reference Materials for Drugs of Abuse In Urine," Pittsburgh Conference & Exposition on

Analytical Chemistry and Applied Spectroscopy, New Orleans, LA, February 25, 1988.

May, W.E., "Fundamental and Applied Research Activities in Liquid Chromatography at the National Bureau

of Standards," 15th Annual National Conference, National Organization for the Professional

Advancement of Black Chemists and Chemical Engineers, Philadelphia, PA, April 5, 1988.

May, W.E., "Reflections on the Arthur S. Flemming Award from a Recent Recipient," Fortieth Annual Arthur

S. Flemming Awards Program, Washington, DC, May 6, 1988.

114
May, W.E., "Development of a Marijuana in Urine SRM," University of Maryland, College Park, MD, May 6,

1988.

May, W.E., "Role of the NBS Center for Analytical Chemistry in Assuring the Quality of Chemical

Measurements in the U.S.," Ohio Valley Chromatography Symposium, Miami University, Oxford,

OH, June 15, 1988.

May, W.E., "International Collaborative Study to Evaluate Bioassay Methods," NESCAUM, Symposium on

the Use of Biological Tests In Evaluation of Ambient Air Pollutants: Implications for Regulatory

Agencies, Princeton, NJ, September 14, 1988.

Parris, R.M., "Standard Reference Materials for Organic Environmental Analysis," Workshop on

Environmental Analysis-RCRA Methods, ACS, NBS, CMA, Water Pollution Control Federation,

National Bureau of Standards, Gaithersburg, MD, Octobers, 1987.

Parris, R.M., "Organic Analysis of Banked Human Liver Specimens to Determine Storage Stability," 11th

U.S.-German Seminar of State and Planning for Environmental Specimen Banking, Bayreuth,

Bavaria, Federal Republic of Germany, May 2, 1988.

Parris, R.M., "NBS Standard Reference Materials for the Determination of Chlorinated Biphenyls,

Chlorinated Pesticide, and Other Halogenated Compounds," 3rd International Symposium on

Biological Reference Materials, Bayreuth, Bavaria. Federal Republic of Germany, May 5, 1988.

Plant, A.L, "Biosensors," Biotechnology Lunch Group, Gaithersburg, MD, November 4, 1987.

Plant, A.L, "Current Research in Flowing Immunoassay Development," IGEN Corporation, Rockville, MD,

November 9, 1987.

Plant, A.L., "Flow Injection Analysis and Biosensors," Environmental Protection Agency, Cincinnati, OH,

December 2, 1987.

Plant, A.L, "Liposomes as Immunoreagents," Chemistry Club, University of Maryland, Baltimore, MD, April

13, 1988.

Plant, A.L, "Flow Injection Immunoassay," Gordon Research Conference on Bioanalytical Sensors, New

London, NH, June 17, 1988.

Reeder, D.J., "Electrophoresis in Bioanalytical Setting," NIH Meeting Sponsored by Eastman Kodak &

Subsidiaries, Bethesda, MD, February 17, 1988.

Reeder, D.J., "Electrophoresis Standards and their Development," Harvard Medical School, Boston, MA,

February 22, 1988.

Reeder, D.J., "Electrophoresis and Bioanalytical Research at NBS," University of Utah Center for

Biopolymers at Interfaces, Salt Lake City, UT, March 10, 1988.

Reeder, D.J., "Electrophoretic Principles and Standards," Rockfeller University, New York, NY, May 19,

1988.

115
Reeder, D.J., "Analysis of Proteolytic Digestion of Fibronectin by Computerized Image Processing of

Two-Dimensional Gels," Electrophoresis Society, Charleston, SC, June 14, 1988.

Richie, K.L, "Results of an Interlaboratory Study to Assess Reproducibility of Rehydratable Gels,"

Electrophoresis Society, Charleston, SC, June 16, 1988.

Sander, L.C., "Evaluation of Column Performance for Reversed Phase Liquid Chromatography," Pittsburgh

Conference & Exposition on Analytical Chemistry and Applied Spectroscopy, New Orleans, LA,

February 23, 1988.

Sniegoski, L.T., "Determination of Cholesterol in Human Serum Standard Reference Materials by Isotope

Dilution /Mass Spectrometry," Third Internationa! Symposium on the Synthesis and Applications of

Isotopically Labelled Compounds, Innsbruck, Austria, July 18, 1988.

Sundaram, P., 'The Past, Present and Future of Biosensors," IX Enzyme Engineering Conference, Santa

Barbara, CA, October 4, 1 987.

Welch, M.J., 'The Development of Definitive Methods for Organic Serum Constituents," University of

Maryland, Department of Chemistry, University of Maryland, College Park, MD, December 4, 1987.

Welch, M.J., "How Pure is Pure? The Certification of Cholesterol 911b," American Society for Mass

Spectrometry, Annual Meeting, San Francisco, CA, June 8, 1988.

Welch, M.J., "Criteria for Cholesterol Reference Materials," American Association for Clinical Chemistry,

Annual Meeting, New Orleans, LA, July 24, 1988.

Wise, S.A., 'The U.S. National Biomonitoring Specimen Bank - Summary of Recent Activities," 11th U.S.-

German Seminar of State and Planning for Environmental Specimen Banking, Bayreuth, Bavaria,

Federal Republic of Germany, May 1, 1988.

Wise, S.A., "Organic Analysis of Marine Specimens from the National Oceanic and Atmospheric

Administration’s National Status and Trends Program," 11th U.S.-German Seminar of State and

planning for Environmental Specimen Banking, Bayreuth, Bavaria, Federal Republic of Germany,

May 2, 1988.

Wise, S.A., "Standard Reference Materials for the Determination of Polycyclic Aromatic Hydrocarbons,"

3rd International Symposium on Biological Reference Materials, Bayreuth, Bavaria, Federal

Republic of Germany, May 5, 1988.

Wise, S.A., "Selectivity in Reversed-Phase Liquid Chromatography," Department of Analytical Chemistry,

University of Ulm, Federal Republic of Germany, May 10, 1988.

Wise, S.A., "Shape Selectivity in Liquid and Gas Chromatography: Polymeric Octadecylsilane (Cis) and

Liquid Crystalline Stationary Phases," The 195th Annual American Chemical Society Meeting and

The Third Chemical Congress of North America, Toronto, Canada, June 7, 1988.

Wise, S.A., "Experience in Environmental Specimen Banking," 18th International Symposium on

Environmental Analytical Chemistry, Barcelona, Spain, September 5-8, 1988.

116
Wise, S.A., "Reference Materials for the Determination of Polycyclic Aromatic Hydrocarbons in Environmental Samples," University of Bordeaux, Bordeaux, France, September 12, 1988.

3. Committee Assignments

Willie E. May

ACS Environmental Chemistry Division

ACS Education Committee

Coordinating Research Council-Air Pollution Research Advisory Board

Special Topics Sub-Committee Chairman, International Committee on Polycyclic Aromatic

Hydrocarbons

Board of Governors, International PAH Symposium

USDA/FDA/NIST Food Irradiation Research Steering Committee

Bruce Coxon

ASTM E-13 on Molecular Spectroscopy

Secretary, ASTM Subcommittee E-13.07 on Nuclear Magnetic Resonance

Richard A. Durst

ASTM D-1 9 on Water

ASTM E-48 on Biotechnology; Chairman, Subcommittee on Biosensors

Board of Advisory Editors, Selective Electrode Reviews

Secretary, lUPAC Division V on Analytical Chemistry: Commission 5 on Electroanalytical

Chemistry

Advisor, NCCLS Subcommittee on Electrolytes

NCCLS Subcommittee on pH and Blood Gases

Chairman, NCCLS Area Committee on Instrument Systems

Chairman, NIST Colloquium Committee

Board of Directors, Society for Electroanalytical Chemistry

Jesse J. Edwards

ASTM E-48 on Biotechnology

Diane K. Hancock

Referee, U.S. National Committee on Sugar Analysis, Subcommittee 6 on Quartz Control Plates

Associate Referee, International Commission for Uniform Methods of Sugar Analysis

Dennis J. Reeder

AACC Committee on Standards; Study Group on Total Serum Protein

Associate Member, IFCC Expert Panel on Drug Effects in Clinical Chemistry

NCCLS Subcommittee on Total Protein

Vice President, International Electrophoresis Society

Michael J. Welch

Standards Committee of the American Association for Clinical Chemistry

117
Stephen A. Wise

President, Washington Chromatography Discussion Group (1987-1988)

Co-Chairman, Sub-Committee on Chromatography, International Committee on Polycyclic

Aromatic Hydrocarbons

Chairman, Publicity Committee, Division of Analytical Chemistry, American Chemical Society

4. Other

a. Seminars

Octobers, 1987

Mr. Michael Zeece, Dept, of Food Science,

"Two-Dimensional Electrophoresis of Wheat Proteins" (Division Sponsor; Dennis J. Reeder)

November 30, 1987

Prof. Karl M. Kadish, Department of Chemistry, University of Houston, Talk entitled: "The

Chemistry and Electrochemistry of Metalloporphyrins" (Division Sponsor: Richard A. Durst)

January 7, 1988

Dr. G. Russell Warnick, Northwest Lipid Research Clinic, Seattle, WA, Talk entitled: "Cholesterol

Measurements in the Clinical Laboratory". (Division Sponsor: Robert Schaffer)

June 27, 1988

Ms. Kathryn S. Kalasinsky, Mississippi State University, Talk entitled: "Chromatographic

Infrared Techniques and Applications in Analytical Chemistry" (Division Sponsor: Willie E. May)

b. Conferences Sponsored

December 7 & 8

NOAA/NBS Quality Assurance Workshop, NBS, Gaithersburg, MD, Stephen N. Chesler.

Sept. 30 - Oct. 2

NBS/NCI Micronutrient Analysis Workshop, NBS, Gaithersburg, MD, Willie E. May.

June 13- 17

Gordon Research Conference on Bioanalytical Sensors, Colby-Sawyer College, New London,

NH, Richard A. Durst.

c. SRM Activities

Certification:

SRM 909a, Human Serum

SRM 91 1 b. Cholesterol (crystalline)

SRM 914a, Creatinine (crystalline)

SRM 916a, Bilirubin (crystalline)

SRM 1216, Carbon Modified Silica

SRM 1491, Polycyclic Aromatic Hydrocarbons in Hexane/Toluene

SRM 1492, Pesticides In Hexane

SRM 1493, PCB Congeners in Iso-Octane

Univer

118
SRM 1507, THC in Freeze Dried Urine

SRM 1563, Cholesterol and Fat-Soluble Vitamins in Coconut Oil (Natural and Fortified)

SRM 1588, Organics in Cod Liver Oil

SRM 1597, Complex Mixture of Polycyclic Aromatic Hydrocarbons from Coal Tar

SRM 1647a, Polycyclic Aromatic Hydrocarbons in Acetonitrile

SRM 1941, Marine Sediment/Organics

SRM 1951, Cholesterol in Human Serum (Frozen)

SRM 1952, Cholesterol In Human Serum (Freeze-Dried)

SRM 1952a, Cholesterol In Human Serum (Freeze-Dried)

SRM 8430, Aspartate (AST) Aminotransferase In 3% Albumin Solution

Stability Measurements:

SRM 909, Human Serum

SRM 1614, Dioxin in Iso-Octane

SRM 1649, Urban Dust/Organics

SRM 1650, Diesel Particulate Matter

119
IV. Gas and Particulate Science Division

Ranee A. Velapoldi, Chief

A. Division Overview

The Gas and Particulate Science Division conducts research to develop new and improved techniques for

the preparation and analysis of gas mixtures and macroscopic and microscopic regions of condensed phase

materials. This includes research leading to: (a) improved measurements of gaseous species in the

atmosphere and in specially prepared gas mixtures and standards, (b) new chemometric techniques for

improving the chemical measurement process and determining source apportionment, (c) improved

methods for quantitative electron, ion, and photon microanalysis, and (e) the preparation and certification

of reference materials. Including SRMs, for measurement quality assurance in analytical chemistry. The

Division responds to the measurement and standards needs of other Federal agencies, state and local

governments, industrial organizations, and universities.

The year 1988 was very satisfying and productive for the Division Staff in terms of funding and scientific

accomplishments. Although competence funding was discontinued at the 5-year ’sunset’ limit in the now

mature area of elemental compositional mapping, the Microanalysis Group was successful in competitive

presentations and obtained new competence funding for molecular compositional mapping, an area using

principles similar to elemental mapping, but generally using different instrumentation to obtain molecular

species information.

The efforts of the Division have supported the basic NIST mission to serve emerging technologies as well as

existing technologies by developing new measurement techniques, extending existing techniques to new

matrices, analytes, and lower concentrations, making more accurate measurements, and developing and

certifying materials as SRMs. This year has been no exception, with major efforts in all of these areas.

The breakthroughs and refinements made earlier by the Atmospheric Chemistry Group to apply accelerator

mass spectrometric measurements to microgram quantities of obtained from gases have been followed

by extending these measurement techniques to amino acids obtained from fossilized bones and to

organic species such as polynuclear aromatic hydrocarbons obtained from geologic samples. These two

major advances open vast new measurement areas for microchemical and molecular dating and to source

apportionment. Additionally, definitive treatises on detection limits and the chemical measurement process

have been published; both of these major works set the standards in, and advance, the field of analytical

chemistry.

After obtaining support of NIST CO2 SRMs at the World Meteorological Organization’s (WMO) annual

meeting, the Gas Metrology Group continued work on these standards and obtained a decrease in the

measurement uncertainty by a factor of more than 3, reducing the uncertainty at the 95% level from about

0.9 ppm to about 0.3 ppm over the concentration range of 300 to 410 ppm CO2. Additionally, an isotope

dilution mass spectrometric definitive measurement method was developed for determining atmospheric

CO2. These IDMS measurements gave results that agreed with the SRM CO2 concentrations within 0.2 ppm

over the 300 to 375 ppm range, providing excellent agreement with the gravimetric values, as well as providing

an extremely firm foundation to tie all global CO2 monitoring results to CO2 standards based on accurate

measurements.

To increase NIST leverage in the production and use of SRMs, the Gas Metrology Group has also signed a

two-year agreement with the Motor Vehicle Manufacturers’ Association which, working in conjunction with a MVMA Research Associate (William Thorn), should provide seven new gas standards and renewal of four

120
others. These standards are used to calibrate instrumentation in the automotive manufacturers’ laboratories

that determine adherence to automobile emission laws.

As reported last year, Congress mandated the Asbestos Hazard Emergency Response Act of 1 986 (AHERA)

and the Division was given major responsibility to provide the technical support for accrediting laboratories

conducting bulk and airborne asbestos measurements by polarized light microscopy (PLM) and analytical

transmission electron microscopy (ATEM), respectively. This first year the asbestos team, headed by Eric

Steel in the Microanalysis Research Group, performed extraordinarily well, providing measurement methods,

technical accreditation criteria, SRMs, and audit materials for bulk asbestos measurements. These were

presented to private testing laboratories. Federal, state, and local agencies, and the public during the

extremely successful Johnson Conference held in Vermont during July. Detailed discussions, and

acceptance of the criteria and methods took place at the Johnson Conference where the measurement

method for bulk asbestos was being submitted concurrently through the ASTM review process. The Division

staff worked closely with the National Voluntary Laboratory Accreditation Program (NAVLAP) staff at NIST

to address all facets of the laboratory accreditation program including developing the criteria, and selecting

and training the more than 60 auditors who will visit the laboratories desiring accreditation. The focus this

year will be on developing a similar program for the airborne asbestos measurements using the ATEM, as

well as continuing with the laboratory accreditation program for bulk asbestos measurement.

During the past year, the Microanalysis Research Group built an electron/x-ray optical bench to measure

more accurately fundamental x-ray parameters critical in quantitative chemical analysis using electron probes

on a microscale. The bench offers flexible control of the electron beam, specimen, and detection. This

versatility provides us with the ability to make more accurate measurements of the fundamental x-ray

parameters used in the quantitative analysis of thin films, particles, and specimens containing light elements

such as oxygen, as well as research on the use of low energy electron beams for quantitative analysis.

Preliminary measurements on the absorption of x-rays as a function of emergence angle have been made

and compared to existing literature expressions for absorption.

The success of using synchrotron radiation in the total reflection geometry to provide sensitive, quantitative

x-ray measurements for Se in serum was reported last year and published in Analytical Chemistry in April of

this year. Continued efforts to obtain more sensitivity using XRF measurements focussed this year on two

major themes: the development of chelation exchange membranes for element preconcentration and the

use of total reflection geometry combined with a rotating anode x-ray source. Experiments in the former are promising; however, increased membrane capacity and reproducibility have to be attained to provide a

reliable, accurate, quantitative measurement procedure. In the latter, components of the rotating source

instrument (double crystal spectrometer, capability for orienting detector/sample combinations, reduced

pressure/He path operation) have been purchased or designed, built, and assembled. Preliminary

measurements have been used to characterize the topography of metallurgical surfaces and efforts this year

will focus on determining minimum detection limits (mdl) for selected elements for comparison with those

mdl’s determined using the synchrotron technique.

The Gas Metrology and X-Ray Fluorescence Groups have continued their strong efforts this year in SRM

certification. More than 150 SRMs have been measured, certified, and/or recertified, ranging from gases

useful in studying atmospheric constituents and phenomena such as the greenhouse effect and ozone layer

depletion to establishing homogeneity for broadly-used biological SRMs including orchard and peach leaves.

121
Increased research capability continues to be a critical need and challenge in specific areas of the Division.

With the asbestos group firmly established, the focus this year will be on strengthening gas measurement

research, chemometrics, and molecular microprobe research.

1. Atmospheric Chemistry Group: Overview

The program of the Atmospheric Chemistry Group has two primary objectives: (1) the development and

application of advanced measurement techniques and standards to increase our knowledge for control of

trace atmospheric gases and particles; and (2) the investigation of mathematical and statistical methods with

application to contemporary analytical problems involving multivariable and multicomponent systems for

the assessment and control of analytical accuracy. Atmospheric gases receiving primary emphasis include

ozone, methane, and carbon monoxide. Particle research is directed toward experimental and mathematical

methods for apportioning sources of natural and anthropogenic carbonaceous particles. In this effort, and

in cooperation with the Organic Analytical Research Division and the accelerator laboratory at the University

of Arizona, our laboratory has become a recognized leader in the art of - microorganic chemistry. Current

activities in chemometrics have been directed at building a software base for the chemometrics program,

developing and applying a basic strategy for sample selection for chemical analysis, and investigating

"errors-in-variables" as applied to the evaluation of analytical data.

The Group continues to provide the benchmark for ambient measurements of ozone, through calibration

services plus the production of ozone Standard Reference Photometers (SRP’s). During the past year, three

SRP’s were manufactured: one for inclusion in the EPA ozone monitoring network, one for the Canadian

Atmospheric Environment Service, and one for the National Swedish Environment Protection Board. These

last two will provide links between the U.S. ozone measurement system and those in use in Canada and

Europe. Complementing work on standard reference photometry has been the development of a stable

ozone generator. The first working prototype was developed during FY88; its stability over the short term (8

hours) is better than 1 %.

Particulate ^"^C measurements performed in connection with the EPA’s Integrated Air Cancer Project (lACP)

have proven most valuable in providing reliable information on the apportionment of atmospheric carbon

compounds and mutagenicity. The "direct" ^"^C tracer technique, which is based on the known differences

in isotopic composition of wood and fossil fuel, has also permitted us to assess the limits of validity of the

EPA-proposed "indirect" elemental K, Pb tracer model. Knowledge of these limits has considerable impact

on the cost and accuracy of (1) future routine monitoring for woodburning pollutant and mutagen burdens

and (2) regional and global assessments of biomass burning contributions to carbonaceous particles.

The emergence of microorganic chemistry" has been made possible through the linkage of

contamination-free, pig-level isolation of organic species to state-of-the-art accelerator mass spectrometry

(AMS). The extreme sensitivity of AMS, combined with advances in target preparation in our laboratory

(through the efforts of two NRC postdoctoral fellows), has made possible reliable measurements of in tens of ng’s of selected organic species. This, in turn, has led to new insights into the origins of organic

carbon in the atmosphere, as well as ages of archeological artifacts. Knowledge concerning atmospheric

organic carbon was developed during the past year through (1) cooperative research with the Organic

Analytical Research Division (S. Wise and B. Benner) and the EPA (R. Merrill) and (2) the PhD thesis research

of Ann Sheffield (U. of MD advisor: G. Gordon). In both of these studies, the isotopic and chemical

composition of particulate polycyclic aromatic hydrocarbons (PAH) were investigated. Among the results

were the facts that wood combustion contributes disproportionately to the PAH fraction of ambient particulate

carbon, in comparison to motor vehicle emissions - i.e., the "soot" carbon is not isotopically homogeneous

with respect to chemical species. A principal result of the Sheffield thesis research was the first demonstrated

correlation of with chemical (PAH) "markers" for auto emissions and woodburning. The exciting

122
challenge ahead is to understand better the combustion chemistry behind these empirical (multiple linear

regression) findings.

Isolation and dating of individual amino acids from ancient bones comprised the postdoctoral research

of Tom Stafford. Painstaking isolation chemistry involving chromatographic separation of fulvic acids from

the amino acids, followed by separation of the individual amino acids for radiocarbon dating, gave a reliable

method for determining the age of ancient man and other ancient mammals exposed to varying degrees of

diagenesis. Concordance between the individual amino acid dates and those of the purified collagen

fractions appears to be the key criterion, long sought to ensure dating accuracy for skeletal remains.

Another powerful linkage between chemical and isotopic analysis for particulate studies has been found in the combination of AMS and laser microprobe mass spectrometry (LAMMS). Cooperating with the University

of Arizona and the Microanalysis Group, we applied chemometric techniques to link the isotopic source

signature of ambient particles with carbon cluster patterns obtained from individual combustion particles.

In effect, ^^C measurements of bulk particles have been used to "calibrate" structural patterns for individual

particles. Avery important consequence of such intercalibration is the possibility of quantifying combustion

sources for media (such as ice cores) in which particle concentrations are far below levels practicable for

AMS measurements.

Fundamental studies in chemometrics in FY88 have addressed two issues of broad importance in analytical

chemistry, namely, the treatment of multivariate chemical data having errors in two or more variables, and

sampling strategies designed to optimize the information gained when one is constrained (e.g., by cost) by

the number or types of measurements that may be performed. The first problem arises in many areas of

chemical analysis, ranging from accurate evaluation of univariate and multivariate calibration functions to

the estimation of parameters and uncertainties in multicomponent analysis. In cooperation with university

and NIST statisticians and mathematicians, we are investigating the reliability of several alternative

approaches to this problem. The study of optimal sampling design was engendered by a practical problem

requiring selection of the "best" subset of I AGP samples for mutagenicity testing and for measurement

-- both relatively expensive techniques. By optimizing with respect to a reasonable "objective function", we

were able to capture most of the potential information with less than half of the usual number of samples.

Significant contributions have been made during the year to quality assurance in analytical chemistry and to

the basic concept of detection, including societal, historical, and technical aspects. This latter work is contained in chapters published in December 1987, in the ACS Symposium Series 361 volume on Detection

in Analytical Chemistry (LA. Currie, Ed.). Contributions related to quality assurance have come about

through service on advisory panels for unversities, industries, other government agencies and national and

international societies/commissions.

Future plans call for expansion of the atmospheric carbon program to regional and global studies, with initial emphasis on the CO-OH-CH4 system. For this purpose, we have established contacts with scientists at the

National Center for Atmospheric Research (NCAR) and the Dept, of Scientific and Industrial Research (New

Zealand) to plan global sampling and organize complementary measurement programs. Research on

standard reference photometry will be enlarged, as a result of improved detector capabilities, to investigate

trace atmospheric levels of SO2 and NO2. LAMMS - pattern recognition research will be extended to

additional types of carbonaceous particles, and we shall endeavor to utilize the information gained from our

exploratory multivariate studies to learn more about the fundamental structural and mechanistic bases for

the LAMMS spectra. We anticipate a conclusion to the chemometrics study on errors-in-variables, including

recommended procedures for generating valid results and uncertainty estimates for such problems.

Chemometrics research will be directed also during the coming year to investigating systematic approaches

123
to the design and evaluation of the chemical measurement process, beginning with the selection of a problem

having broad importance and significant multivariable and multicomponent aspects.

Lloyd A. Currie, Group Leader; Donna Barraclough, Arnold M. Bass, Ken R. Beebe, P. Ed Hare, George A.

Klouda, James E. Norris, Will M. Ollison, Ann E. Sheffield, and Thomas W. Stafford.

2. Microanalysis Group: Overview

The Microanalysis Research Group carries out research to develop and apply microbeam analysis techniques

for the chemical, morphological, and crystallographic characterization of matter on the micrometer and

sub-micrometer spatial scales. The analytical techniques utiiized are based on primary (excitation) beams

of electrons, ions, or photons, and secondary (analytical) signals of x-rays, elastically and inelastically

scattered electrons, elastically and inelastically scattered photons, or ions. The techniques used include

electron probe microanalysis (EPMA), scanning electron microscopy (SEM), analytical electron microscopy

(AEM) with energy dispersive x-ray spectrometry (EDS) and electron energy loss spectrometry (EELS),

secondary ion mass spectrometry (SIMS), laser microprobe mass analysis (LAMMA), laser Raman

microanalysis (LRM), x-ray diffraction (XRD) and polarized light microscopy (PLM).

Research is conducted on several aspects of each technique to (1) understand the basic physics of sample

excitation by the primary radiation and of the propagation of the secondary radiation; (2) develop methods

of quantitation; (3) produce reference materials and techniques as a means of disseminating developed

technology; (4) apply results of the research to improve compositional mapping techniques; and (5) study

specific analytical problems to support NIST and other government agency activities as well as national

scientific priorities.

The 1988 fiscal year has been a particularly active year for the group, marked by significant expansion with

concomitant new responsibilities in the areas of asbestos analysis and characterization of superconducting

materials. Group members have been active in research in each of the major technical areas, including

electron, ion, and photon beam techniques, with the following progress in each area.

I. Electron Techniques

(a) Electron Probe Microanalysis

The need for fundamental data to support advancement in quantitative analysis procedures is being met by

the development of the electron/x-ray optical bench. The first version of this instrument, which incorporates

a conventional scanning electron microscope column and both flow proportional and energy-dispersive x-ray

spectrometers, has been successfully constructed and tested. The system has been evaluated with a

preliminary series of experiments to measure the x-ray absorption function on pure element and binary

compound targets.

Our activities in fundamental studies in electron microprobe quantitation are focussed on a detailed

examination of theoretical aspects of models for matrix correction procedures for quantitative electron probe

microanalysis. This work is complemented by efforts to re-evaluate and improve the standard computer

algorithm for microprobe analysis.

This year marked the 20th anniversary of the publication of the international workshop on quantitative electron

probe microanalysis held at NBS (NBS Special Publication 298, Quantitative Electron Probe Microanalysis),

a meeting which is widely regarded as a watershed in the development of the technique. Because of the

rapid progress in the past five years in new techniques of quantitative electron probe analysis we convened

124
a new workshop in conjunction with the annual conference of the Microbeam Analysis Society (August 1 5-1 7,

1 987). Experts from the U.S., Europe and Japan participated in detailed discussions on quantitative electron

probe analysis, which will appear as a new NIST special publication on the topic.

The development of compositional mapping with the electron microprobe was continued with emphasis on

combining wavelength-dispersive x-ray spectrometry (for sensitivity and spectral resolution of interferences)

with energy dispersive x-ray spectrometry (for detection of multiple elements) to expand substantially our mapping capabilities. Compositional mapping was also applied to a variety of problems in materials science,

with an especially large effort directed towards the study of bulk and thin-film high Tc superconductors. The

compositional maps of these materials aided NIST (IMSE) scientists to understand limitations to the

superconducting performance of these materials.

(b) Analytical Electron Microscopy

The first Standard Reference Material for AEM, a thin glass film (101 nm thick) containing major

concentrations of Mg, Si, Ca, Fe, and 0, designed for calibrating the x-ray spectrometer of the AEM for

quantitative elemental analysis, was issued. Further research to produce additional films in this series, to

expand the energy range of quantitative analysis, will be facilitated by the purchase of a large-beam ion

sputtering apparatus. By having the sputtering apparatus in-house, better control of the experimental

conditions to produce the potential SRMs will be possible. In addition, a new multichannel (parallel detection)

electron energy loss spectrometer (EELS) has been added to the 200 keV AEM. This EELS instrument

expands our capabilities for microanalysis of light elements, and provides the basis for developing and testing a new class of AEM standards specifically directed toward EELS microanalysis.

Two other related developments have substantially expanded our beam energy and beam resolution

capabilities in analytical electron microscopy. First, a new 300 keV computer-controlled AEM has been

procured to provide the in-house measurement basis for the airborne asbestos National Laboratory

Accreditation Program (NLAP). Second, the National Institute of Standards and Technology/National

Institutes of Health Nanometer Analysis Facility was dedicated in May. This faciiity is based upon a field

emission scanning transmission electron microscopy (FE-STEM), which has the capability of forming a 1 nm

analytical probe, in addition to imaging with probes as small as 0.5 nm.

(c) Asbestos Standards and Laboratory Accreditation Program

The Microanalysis Research Group has been active for ten years in developing and characterizing techniques

for analyzing asbestos in air, water, and solid samples. In response to regulations by the Environmental

Protection Agency, Occupational Safety and Health Administration, and laws propagated by Congress, we

are standardizing the analytical methods used for checking abatement and compliance with state and Federal

regulations for bulk and airborne asbestos. To accomplish this, we have set up a National Laboratory for

Asbestos Analysis. Instrumentation for this laboratory includes x-ray powder diffraction, light microscopy,

and transmission electron microscopy (TEM) systems with computer and image analysis support. We have

hired four people with skills in polarized light microscopy, mineralogy, x-ray diffraction, crystallography, and

transmission electron microscopy to perform characterization of standard methods and SRMs for asbestos

analysis and to provide technical support for the National Laboratory Accreditation Program at NIST.

125
Mass Spectrometry Microanalysis

(a) Secondary Ion Mass Spectrometry

The Microanalysis Group has continued its vigorous research program in secondary ion mass spectrometry

(SIMS). Our Ion microscope has been upgraded by the addition of a resistive anode encoder image detector,

a position-sensitive detector that can record single ion arrivals. A new control computer system based on

an IBM-PC-AT was also installed. A major new program in SIMS will begin with the delivery of a time-of-flight

secondary ion mass spectrometer that includes a pulsed liquid metal ion gun. This instrument will have an

ultimate spatial resolution of about 200 nm, and the capability to detect Ions of all masses for each pulse of

the ion gun.

In the past year, SIMS has been used for a variety of applications, many of which are In the field of

semiconductors. Progress has been made toward the first SRM for depth profiling by SIMS, a material which

consists of ion-implanted boron in pre-amorphized silicon. This work is being done in collaboration with the

Naval Research Laboratory (NRL) and the Aerospace Corporation. While characterizing a prototype

material, several ’unknown’ artifacts produced by the ion implantation process were detected. High-dose

implantations of oxygen and nitrogen in silicon have been studied in collaboration with the Center for

Electronics and Electrical Engineering (CEEE) and Sandia National Laboratory. Collaborative SIMS research

has also been carried out on MeV Be implants in GaAs (with NRL) and on Fe implants in InGaAs (with George

Mason University).

The imaging capability of the secondary ion microscope has been exploited in a study of the oxygen

distribution in high Tc superconductors, which was shown to be highly non-uniform in samples in which the

cations were also inhomogeneously distributed. A project is underway to measure local oxygen

compositions more quantitatively using in-situ implantation of to provide a localized isotopic spike for a

direct isotopic dilution measurement by SIMS.

A new thrust this year has been the investigation of secondary ion imaging of organic species in the ion

microscope. A post-doc has been added to the group to advance this work. It is often assumed that intact

molecular ions cannot be produced from a surface previously damaged by ion bombardment. We have

found that a sufficient molecular signal is often available for useful imaging with the sensitive imaging detector

that is now available on our machine, even after prolonged ion bombardment of an organic material. Studies

in progress are designed to look at the effects of various parameters such as primary beam species and

energy on the damage-induced decay of molecular ion signals from various model organic compounds.

(b) Laser Microprobe Mass Analyzer

We have continued to develop analytical methods and applications for the laser microprobe mass analyzer

(LAMMA). Detailed studies have been carried out on the response of the conventional ion detector of the

LAMMA, and a new detector has been designed and tested. A new computer-controlled sample stage has

been designed which will permit more precise positioning of particle targets. Interelement effects on

quantitative analysis have been studied, and the influence of sample geometry on ion signal has been

evaluated. Recent research directions have been in utilizing pattern recognition techniques for analyzing

and comparing the spectra of carbon aerosol particles that have been generated in the laboratory with

particles that have been collected from the atmosphere for use in source apportionment studies. In another

project, analysis of micrometeorite samples is underway using the laser microprobe, with the results to be

correlated with those from analytical electron microscopy of particle thin sections.

126
III. Photon Beam Microanalysis

Research in Raman microprobe spectroscopy is centered on the application of micro-Raman instrumentation

with monochannel (PMT/photon counting) and multichannel (optical array) detection in both fundamental

and applied problems in molecular/structural microanalysis. The NIST-developed scanning Raman

microprobe has been used this year in the study of several types of materials problems of high-technology

interest (e.g., diamond films, superconductor ceramics, and carbon and polymer composites). The superior

spectral resolution of this instrument has allowed the documentation of sharp structure resonances, both In the fluorescence and Raman emissions, of spherical microparticles, results which are of interest relative to

the predictions of current theoretical models of inelastic scattering.

The multichannel Raman microprobe, based on spectrographic dispersion, has been upgraded this year

with the acquisition of a state-of-the-art intensified diode array detection system. The improved performance

capabilities of the instrument have been evaluated in measurements on microsamples (explosives,

superconductors) potentially subject to time-dependent laser-induced modification, utilizing the multiplex

advantage for short-time integration of weak Raman signals. This effort in getting the new system fully

operational has been expedited with the help of Professor Thomas D. Schroeder of Shippensburg University

in Pennsylvania who spent the summer with us.

IV. Image Processing

A major component of our research in quantitative microscopy Involves the development of computer-aided

imaging techniques. Important progress in this area includes the development of scatter plots for analysis

of compositional maps with more than two compositional variables. This method permits rapid, quantitative

evaluation of concentration relationships in images, and provides high sensitivity for the recognition of

low-frequency events in such images. A critical advance supporting much of our image software activities

has been the development of a fast machine-code version of the "BLOBBER" function, which is used to

dissect images into basic units of contiguous picture elements sharing similar properties.

V. Particle Collection and Analysis

Experiments on characterizing particle aerosols have been undertaken in conjunction with external

collaborators, including Professor Gentry of the Department of Chemical Engineering of the University of

Maryland, to study collection of asbestos on filter media. Work is proceeding to characterize fully the

sub-micrometer particle collector developed several years ago. We have also developed important particle

handling methods, with detection of selected elements by nuclear track techniques.

Future Plans:

An amazing range of new research opportunities has opened up to group members as a result of the newly

available instrumentation. The 300 keV analytical electron microscope, NIST/NIH scanning transmission

electron microscope, and time-of-flight secondary ion mass spectrometer will provide opportunities to

perform analyses which can be spatially-resolved at the nanometer scale. Many new problems in quantitation

and standardization will have to be addressed to advance into this area. We will explore the fabrication of

the new class of thin-film Standard Reference Materials for these analytical applications by means of the new

ion beam sputtering apparatus. We will continue as well to improve the established analysis techniques such

as electron probe microanalysis, secondary ion mass spectrometry, laser microprobe mass spectrometry,

and laser Raman microanalysis.

127
Dale E. Newbury, Group Leader; Adville A. Bell, David S. Bright, Peter H. Chi, Edgar S. Etz, Robert A. Fletcher,

J.G. Gillen, K.F.J. Heinrich, S.M. Hoeft, M.D. Johansen, Ryna A. Marinenko, Robert L. Mykiebust, F. Scott

Percies, J.M. Phelps, Cindy J. Poston Patrick J. Sheridan, David S. Simons, John A. Small, Eric B. Steel,

Barbara Thorne, Shirley Turner, and Jennifer Verkouteren.

3. X-Ray Fluorescence Group: Overview

The principle objective of the X-ray Fluorescence Group is to maximize the accuracy and sensitivity of the

analysis of elemental composition in a variety of materials. A major, ongoing effort is devoted to improving

first principle methods of corrections for interelement matrix effects for non-destructive assay. To this end,

we are constantly updating the computer program NBSGSC developed by us to take advantage of more

accurate fundamental parameters when they become available. We plan to publish a major update of

NBSGSC in late 1989.

We have investigated several approaches to increase analytical sensitivity. First, we have characterized

several batches of commercial filters to which we have covalently bonded specific chelating groups, such

as dithiocarbamate and oxine, for the purpose of preconcentrating trace elements prior to analysis. So far,

this approach has met with limited success because of the variability of the elemental capacity of these

derivatized commercial filters. We are now seeking ways to increase the capacity and improve the

reproducibility by making the derivatized filters directly from paper pulp, working closely with D.B. Blanchard

and K.F. Hermsen of the NIST Fibrous Systems Division. In related work, we are continuing our efforts with

H.M. Kingston of the Inorganic Analytical Research Division to develop rapid HPLC separation methods for

sample preparation prior to preconcentration.

A second approach to increase analytical sensitivity has been initiated this year by construction of a total

reflection x-ray spectrometer. In early 1988, we published a paper describing the sensitivity (sub-ppb

detection limits) of this new instrumental technique for XRF analysis using a very bright synchrotron source. The principle components for a laboratory system consist of a high-intensity rotating anode x-ray source, a

double-crystal spectrometer, and a solid-state detector. We have purchased a double-crystal spectrometer

and interfaced it to the rotating anode x-ray source and are focusing efforts to demonstrate the sensitivity of

this system.

Several sets of thin films have been completed for use in interlaboratory quality assurance programs which

employ x-ray fluorescence methods of analysis. The purchase of a focused ion-beam sputtering system this

year will make the fabrication of such films much easier in the future. We intend to complete the development

of zinc sulfide thin films for XRF calibration during 1988, so that we can begin production of these films as SRMs next year.

A major part of our work continues to be the homogeneity testing and quantitative analysis of a wide variety

of materials of special interest to the Office of Standard Reference Materials. Among the new materials we

completed this past year was NBS/SRM 2704 (Buffalo River Sediment) where we contributed to the NBS

certification of twelve elements. Other materials analyzed consisted of minerals (SRM 600-Bauxite), alloys

(SRM 1219, 1250, 868, 1276a), cements (SRM 1884-1889), flows older powder (SRM 1129), and oils (SRM

1624b).

Future Plans:

An NIST Research Associate from Kevex Corporation will join the XRF group in November 1988, to work on

the development of instrumentation and software for performing x-ray imaging compositional mapping. This

will be a new long-term area of research for us. The use of a micro-focus x-ray tube or a crystal -focused

128
high-intensity source such as the rotating anode to obtain x-ray beam diameters of 10 ^m or iess makes this a viable technique for obtaining useful chemical compositional maps.

Activities of the Past Year:

(1) Determined performance offilters impregnated with dithiocarbamate and oxine ligands for trace

element preconcentration.

(2) Completed two sets of thin films for XRF laboratory quality assurance evaluation.

(3) Completed XRF analysis of NBS/SRM 2704 (Buffalo River Sediment) for NBS certification.

(4) Interfaced a new double-crystal spectrometer to a rotating anode source for performing total

reflection XRF analysis.

Peter A. Pella, Group Leader; Anthony F. Marlow, John Sleber, and Gerald A. Sleater.

4. Gas Metrology Research Group: Overview

The Gas Metrology Group and the Analytical Laser Spectrometry Group have been combined to form the

Gas Metrology Research Group. The combination is operating smoothly since both groups are involved in the same basic area, preparation and analysis of gas mixtures, and the goals of the combined group include

the same objectives as the two individual groups.

The Gas Metrology Group conducts research on accurate preparation methods and highly precise and

definitive analytical techniques for the development of primary gaseous standards. The research and

standards are applied to the quantitative evaluation of gas mixtures ranging in concentration from the percent

level to the one part-per-trillion (ppt) level and in complexity from single to multicomponent gas mixtures.

Although the metrological outputs of the Group are primarily focused on the certification of a wide variety of

inorganic and organic gas Reference Materials (RMs) and Standard Reference Materials (SRMs', a

substantive portion of our activities involves measurement research covering the broad range of gas analysis.

Specific attention is given to detailed evaluations of preparative and measurement uncertainty, assessments

of the long-term stability of gas mixtures, and the development of fundamental data on the spectral,

chromatographic, and detection properties of gas mixtures.

Preparative techniques used to develop primary gravimetric standards for assuring the accuracy of trace

gas measurements are based on absolute gravimetry involving pressure-vacuum manifold systems, gas

blending, and other methodologies. Verification techniques to assess the efficacy of primary standards or a suite of primary standards include the use of dynamic dilution, permeation device systems, statistical

evaluation of correlation curves, and measurement methods such as spectroscopic absorption coefficients.

Analytical techniques inciude: gas chromatography (GC); mass spectrometry (MS); GC/MS; non-dispersive

infrared analysis: chemiluminescence spectrometry; tunable diode laser absorption spectroscopy (TDLAS)

and a variety of ancillary analytical systems for the determination of trace gaseous impurities. Data

acquisition and statistical data evaluation command a substantiai portion of the Group’s attention.

The gaseous standards developed by the Group are used to certify RMs or SRMs that serve as primary

calibrants for national and state regulatory programs, industrial, institutional, Federal measurements,

international collaborative programs, and global monitoring programs. The Group, working through the Gas

and Particulate Science Division, is responsive to and interacts with gas measurement and standards needs

129
of other agencies, industrial organizations, and standards-setting bodies at the local, state, and national

levels. Group members routinely provide advice and guidance to the private sector, and interact with

investigators on gas measurements and standards on a world-wide basis. Based on its expertise in gas

measurements and standards, the Group also performs a limited number of gas analyses for external

organizations.

During F^SS, the Group’s SRM work resulted in the certification of twelve 50-cylinder batches of gaseous

SRMs, including one new SRM and a new RM for multicomponent volatile toxic organic compounds, ranging

in concentration from 1 0 ppm to 5 ppb. Approximately 300 permeation tubes for SO2 and NO2 were also

certified. During this period, the Group’s research activities included: (1) the final development and

evaluation of the procedure to prepare primary gravimetric standards to certify CO2 in air mixtures used in global monitoring programs for atmospheric CO2: (2) the development of NIST-traceable standards

containing up to 6 volatile toxic organic compounds in the ppt to ppb range to provide data quality assurance

for the state of CA; (3) a calibration procedure for the TDLS to analyze for low concentration levels of H2O2:

(4) development and testing of a system to generate the atmospherically important trace constituent MONO,

and (5) a study of the reaction/equilibrium of NO2/H2O/HNO3 in high pressure compressed gas cylinders.

The important program to provide carbon dioxide in air SRMs for use by the scientific community and

especially the World Meteorological Organization (WMO) in monitoring the increase in global CO2

concentration is continuing. During the year, three aspects of the program have been finalized : (1 ) a primary

standards set of cylinder mixtures of CO2 in air prepared by gravimetry: (2) the recertification of five batches

of CO2 in air SRMs; and (3) the determination of the concentration of carbon dioxide in mixtures of CO2 in air by isotope dilution mass spectrometry (IDMS). During FY87, research was performed in developing single

and double dilution procedures for the gravimetric preparation of CO2 in air mixtures in high pressure gas

cylinders. This resulted in two suites of standards which proved to be slightly but statistically different.

Combining the two suites would have resulted in a higher analytical uncertainty than appropriate. Continued

research showed that in one step of the double dilution procedure, the CO2 was not quantitatively swept into

the containment cylinder. When this was rectified the standards produced by the single dilution method

were indistinguishable from those produced by the double dilution procedure. These new primary standards

were then used to recertify the CO2 in air SRMs. The work in the IDMS determination of CO2 was concluded

this year. All aspects of the gas handling and measurement systems were evaluated, some were changed

or modified, and all required calibrations were performed. The results from the analysis by IDMS agree within

the measuremenet uncertainty with the results generated by use of the gravimetricaliy prepared standards.

This is important because it demonstrates that there is no bias in the primary gravimetric standards.

Another important program, the development of reference materials for volatile toxic organic compounds,

is continuing and has been expanded this year to include mixtures at much lower concentration levels than

in the past. Primary standards containing up to eighteen organic compounds, each at the 1 5

parts-per-trillion

(ppt) level, have been developed as SRMs and for the California Air Resources Board. Working with mixtures

at the low ppt level required development of gas chromatographic procedures that incorporate an electron

capture detector, which is extremely sensitive for certain classes of compounds. Research has also been

completed in the development of a 24-component standard containing compounds from the EPA’s

Superfund Hazardous Substance list.

Hydrogen peroxide is an important trace atmospheric constituent of interest to EPA. It Is difficult to generate

calibration standards containing known amounts of H2O2: thus a procedure was developed to generate a

mixture of known amounts of H2O plus H2O2 in air and then pass it through a spectroscopic cell. The amount

of H2O Is determined by observing a known absorption band of H2O with a well-known absorption coefficient

and the amount of H2O2 calculated by difference. The spectrometer, in this case a TDLS, is then calibrated

by observing a band of H2O2 and determining its absorption coefficient.

130
Another trace atmospheric constituent which plays a significant role in atmospheric chemistry is HNO2

(MONO). No reliable calibration standards exist for this gas; therefore, a system was developed similar to

the one used to generate HNO3 (i.e., dilute gas mixture of HCI + AgNOs AgCI + HNO3). The silver

nitrate (AgN03) was replaced by silver nitrite (AgN02) and a dilute gas mixture of HCI passed over it. The

output of this generator was analyzed for MONO content using TDLS; only about 3% of what was expected

was found. Additional work is needed to establish conditions that affect MONO generation.

Cylinder mixtures of standards are frequently easier to use than more complex generation systems; therefore,

we investigated the possibility of providing cylinder mixtures of HNO3 even though we developed the HNO3

generation system. Mixtures of NO2 in air were doped with H2O to cause the reaction H2O + NO2 ^HNO3.

An equilibrium mixture of NO2/HNO3/H2O exists in these cylinders which are being studied for the stability

of the NO2 and the HNO3 content.

Other accomplishments of this year included: the use of the HNO3 generator with a dilution system to provide

calibration mixtures of 1 ppb HNO3 in air; the determination of the lower detectable level of the TDLAS for

many compounds (CO, SO2, OCS, CS2, NO2, HNO3, CO, CO2) ; the continued upgrade of one of two TDLAS

systems so that it can be more easily used for analytical work; the re-evaluation of twenty-five primary

standards to provide the Western Primary Standards Laboratory of the U.S. Navy with standards to support

their effort in ambient monitoring of enclosed areas of Navy installations and vessels; and, the development

and evaluation of thirty new primary standards to analyze breathing oxygen standards for Naval aviators.

A joint program between NIST and the Motor Vehicle Manufacturers Association (MVMA) has been

established to produce seven new SRMs and to restock four existing SRMs all of which are needed for either

engineering work in the auto industry or to provide standards for EPA emission compliance measurements.

The MVMA has supplied a research associate to work at NIST on this program.

Futuce.Pig ns :

Our future plans are to: develop dynamically prepared calibration standards of five sulfur gases (SO2, H2S,

COS, CS2, and (CH3)2S) and the analytical methodology to measure these gases at the 0.5 to 1 ppb level;

continue work on doped "zero gas"; establish better measurement capability for water vapor in gases; develop

a more sensitive statistical model to evaluate outlying or drifting standards in a suite of standards; determine

feasibility of producing stable, dry HNO3 cylinder mixtures using the output of the HNO3 generator; continue

to improve quantitative capabilities of TDLS; and establish a more rigorous quality assurance program to

assess long-term stability of the more than 100 primary standards of the Toxic Organic Gases program.

William D. Dorko, Group Leader; Barry C. Cadoff, Patricia A. Johnson, Steve Krauss, Rudolph von Kelly,

Gerald D. Mitchell, W. Robert Miller, Richard D. Myers, Linda Nunnermacker, George C. Rhoderick, Robert

L. Sams, James E. Suddueth, Nicholas Sylvain, R. Michael Verkouteren, and Walter L. Zielinski, Jr.

131
B. Seiected Technical Reports

(Gas and Particulate Science Division)

1. The Use of Experimental Design Methodology for Effective Sample Selection: Application to

Aerosol Source Apportionment

K.R. Beebe and LA. Currie

As part of the Integrated Air Cancer Project (lACP), the EPA used approximately 80 aerosol samples from

Boise, Idaho to estimate the effect of wood burning and automobile emissions on the mutagenic activity in the atmosphere. Forty samples were collected from each of two sites, Elm Grove Park (a residential site)

and Fire Station (a roadway site), over two, 1 2-hour sampling periods. For each sample, the concentrations

of potassium (K) and lead (Pb) were measured by x-ray fluorescence spectroscopy. These constituents

were used as unique tracers for wood burning and automobile emissions, respectively. The mutagenicity of

the organic fraction of the aerosol samples was measured by EPA, and multiple linear regression was used

to estimate the effect of the tracer elements on the mutagenicity.

Our involvement in the study was in testing the validity of the results based on the elemental (K,Pb) tracer

mode! using an independent measurement for source apportionment (^"^C). Theoretically, validation would

be best achieved by using all 80 samples. However, it was deemed impractical to analyze all the samples

for^^^C. Therefore, it was necessary to choose a smaller subset of samples for analysis. This subset selection

was subject to two constraints: a) equal representation from the four site-periods, and b) an overall "cost"

(time, personnel, analytical expenses, etc.) constraint in measuring the The second constraint set a

pro-tern maximum of 9 samples from each site-period to be used for validation. The major concern became

the selection of an appropriate subset of samples that would effectively use the available resources while

maximizing precision in the final model.

The two basic points that needed to be addressed were: a) What are the best samples to use? and b) How

much is the precision in the model compromised by using a reduced set of samples?

For a given number of samples selected for measurement, we were concerned with selecting the "best"

subset. "Best" is generally defined in terms of an "objective function" or measure which exhibits a maximum

or minimum for the chosen samples. The nature and magnitude of this function can then be related to the

adequacy of the validation test. We faced two questions: which objective function to employ, and how to

select the best subset of samples. To answer these questions, we first chose a validation model as follows:

Ci = bo + biKi + baPbi -i- ei

where Ci is the combined carbon (fossil and wood source): Kj is the potassium concentration; and Pbi is the

lead concentration, all for the ith sample. For linear models such as the one considered here, a natural choice

of objective function is the determinant of the Fisher information matrix | X’X | . This approach, using what is termed a "D-optimal" criterion, yields the minimum volume confidence ellipsoid for the parameter estimators.

In other words, thefinal subset of samples will yield a model with good properties, i.e., relatively small standard

errors (SE) for all of the model parameters (bo, bi, b2).

The following algorithm, based on a step-wise selection procedure using the D-optimal criterion, was used

to select the subsets:

132
We began by choosing two samples (by a replacement design) from the 20 samples at each site and period.

To this set we added a third sample from among the 1 8 remaining samples, and then calculated the resulting

determinant. This initial model was designated an N = 3 model as three samples were used to calculate the

determinant. This was repeated 1 8 times, each time using a different sample from the pool of 1 8. The sample

that yielded the best determinant (maximum) was retained and the resulting three samples were used as the

best N = 3 subset. Next, one sample at a time was added to the N = 3 subset from the remaining 20-3 = 17

samples until an optimal N = 4 subset was obtained. This process was repeated until the optimal set of nine

samples was selected.

To evaluate the reduction in precision resulting from the use of a smaller set of samples, we examined the

resulting SEs for the model coefficients as the samples were added one at a time. The value of the SEs

decreased monotonically and reached a plateau at approximately N = 8 for all of the model coefficients. It was clear that little is gained by going beyond the optimal set of 9 samples. For example, the N = 13 model

for one typical site-period sample set yielded further SE reductions of only 4% for bo,

2.7% for bi, and <0.1% for bb2

-

Selection of samples for measurement according to sound experimental design principles can greatly

increase the information gained per unit cost. When rather expensive or time-consuming operations are

involved, such planning is vital to (a) identify the most cost-effective measurement (sampling) scheme, and

(b) assess in advance the adequacy of the plan.

2. A New Approach to the Determination of the Origins of Individual Carbonaceous Particles

through Accelerator Mass Spectrometry (AMS) and Laser Microprobe Mass Spectrometry

(LAMMSI

LA. Currie, R.A. Fletcher, and G.A. Klouda

Parallel and "hybrid" analytical measurements applied to common samples can often provide far more

information than a simple "sum of the parts." Such is the case for AMS-LAMMS, as applied to atmospheric

combustion particles ("soot"). AMS measurements of have served a critical function in our research on

the origins of atmospheric gases and particles, in that it is a direct and unique tracer for biospheric ["living"]

carbon. When combined with carbon mass determinations of selected compounds, such measurements

yield direct estimates of fossil and biogenic source contributions. The great strength of LAMMS is that it allows one to discern structural information of individual carbonaceous particles, covering a broad range of

molecular weights. Interpretation of the rather complex LAMMS spectra, however, is not facile.

We have been able to take advantage of the strengths of each analytical technique through their iinkage.

Beginning with laboratory experiments ("test burns") of single source combustible materials, we have begun

to establish "fingerprint" characteristics of the resultant, high molecular weight soot particles. To obtain this

material, we took advantage of test burns by the NIST Center for Fire Research [G. Mulholland], in support

of the Nuclear Winter program. Particles from the combustion of heptane, cured wood, and polyurethane

were collected. LAMMS positive and negative ion mass spectra were examined for pure graphite, and

combustion particles from each of these source types. Pattern recognition techniques (selection of

discriminating masses followed by 2- and 3-dimensional principal component mapping) were successfully

applied to the positive ion spectra for combustion source identification. When these patterns were compared

to ambient atmospheric particles which were selected to be primarily fossil fuel or biogenic (wood fuel) in origin, on the basis of bulk analysis, discrimination failed. Evidently, assumptions concerning the

composition of laboratory combustion particles, in contrast to those in the atmosphere (from real motor

vehicles and woodstoves), are not fully valid.

133
Turning to the negative ion spectra, especiaily to cluster-ion features such as Cn‘ and CnH*. we found

consistent patterns for field and laboratory particles showing successful discrimination of the soot from wood

and fossil fuel sources. It should be noted that such discrimination is not necessarily a trivial matter, for the

high molecular weight soots tend to be largely graphitic in structure, regardless of fuel type, as a result of

the acetylenic radical polymerization processes that occur in the flame. Validation or calibration of the source

identification patterns for ambient particles therefore requires a quantitative discriminator of known reliability

such as

After investigating the validity of "end member" identification in the field, we took advantage of

measurements on a suite of samples collected in Albuquerque as part of the EPA’s Integrated Air Cancer

Project to assess the relative contributions from motor vehicles and woodburning to the serious levels of

carbonaceous pollutants and mutagens in the wintertime urban atmosphere. Negative ion LAMMS spectra

were obtained from individual particles from bulk samples that had been collected for measurement. A

very important outcome of this dual method study was a LAMMS pattern calibration curve, where quantitative

changes in selected pattern indices (cluster ion ratios) were related by regression to the concentration,

which in turn gave a direct measure of the wood/fossil fuel source apportionment. This approach thus

transfers the isotopic tracer information from the 10’s of jxg-C level to the pg-C level, as the points on the

calibration curve were obtained with 3 - 5 fine particles each.

The next goals of this project will be to confirm the findings in other airsheds and possibly in remote

atmospheres, and to begin to understand the physicochemical bases for the combustion source related

cluster ion patterns. Besides the prospect of learning more about these combustion and laser plasma

processes, we anticipate important applications to carbonaceous particle origins in areas, such as the

stratosphere and cryosphere, where concentrations are too low for direct AMS measurements.

3. Improved Accuracy in the Radiocarbon Dating of Bone and the Tracing of Atmospheric Carbon

via Micro-organic Isotopic Measurements

G.A. Klouda, T.W. Stafford, L.A. Currie, A.E. Sheffield, and D. Barraclough

Our accomplishments this past year include the development and application of micro-chemical separation

techniques for solving environmental radiocarbon problems. In atmospheric chemistry, the application of

the tracer technique to Individual compounds and chemical classes at the microgram level has

demonstrated that specific source information of improved accuracy is gained through chemical speciation.

Similarly, accurate ages of poorly preserved fossil bone have been obtained by dating specific amino acids

extracted from bone collagen. These studies involving measurements at the microgram level are possible

only through the use of accelerator mass spectrometry (AMS).

Investigations into the origin of environmentally important atmospheric pollutants, e.g., extractable organic

material (EOM), polycyclic aromatic hydrocarbons (PAH’s), elemental carbon (Ce), CO, and excess CH4, have involved micro-chemical separation techniques. AMS results of EOM and PAH fractions extracted

from wintertime Albuquerque, NM, source samples representing 1 ) motor vehicle emissions, 2) wood-burning

emissions, and 3) a mix of these two sources compared well with estimated impacts. A more extensive study

of Albuquerque PAH’s was completed this year (A.E. Sheffield) using measurements of this fraction to

validate the use of single PAH’s as tracers of wood burning and motor vehicle emissions. The tracer

technique for source apportionment is currently being applied to total carbon, EOM, and Ce collected in Boise, Idaho, for the EPA Integrated Air Cancer Project (iACP).

134
Emphasis was also placed this year on the chemical characterization of the so-called elemental carbon

fraction of air particles where this fraction has previously been operationally defined. Our approach utilizes

70% HNO3 to remove the organic carbon from the particulate material followed by thermal combustion of

the residue to C02for quantitation by manometry in a calibrated volume. The reproducibility of this technique

is 5-10% and results agree to within ~ 7% of the thermal optical technique. An important question remaining,

and currently under investigation, is the quantitation of polymeric and graphitic carbon; both are assumed

to make up the non-extractable and non-wet-oxidizable carbon fraction.

The selective oxidation technique to separate CO and CH4 from 0.1 m^ air, previously developed for urban

atmospheres, has been successfully applied to remote "clean air'' samples. This pilot study involved samples

collected over the Amazon Basin (by aircraft) and at a high elevation site (ground based) in Colorado to

evaluate the technique for pristine air samples where the concentration of CH4 was ~ 1.7 ppm and that of

CO was ~ 150 ppb. Additionally, the atmospheric CO2 cryogenically scrubbed from the gas stream was

Isolated for ^^C measurement. Methane results for these clean air samples substantiated estimates that

background CH4 is largely biogenic in origin. These results are also in accordance with results of Wahlen et

al. 1987. Plans are to test this separation procedure at higher flow rates to allow for processing 1 m^ air

samples. The increase in sample size will enable ^^C measurements on background CO at concentrations

ca. 50 ppb and improve the precision of ^"^CH4 measurements.

In comparison, CH4 results from a number of eastern U.S. cities and two western cities suggest that the

excess urban CH4 is largely of fossil origin. Additionally, measurements of ^^C in CH4, and other trace

measurements of gases, e.g., N2O (in collaboration with Gas Metrology Group), are under investigation for

their value in the identification of source strengths. We plan next to apply this micro-chemical technique to

the investigation of the global CH4 and CO cycles.

In the fields of archaeology, anthropology, and geochemistry, radiocarbon dating of selected chemical

fractions has shown great promise in situations where the presence of exogenous material may lead to

inaccurate dates. During this past year, postdoctoral work by T.W. Stafford included the development of a

fractionation scheme to isolate specific amino acids from fossil bone for accurate radiocarbon age

determinations when the quality of preservation is in question.

Amirio acid micro-chemical dating of fossil bone has been applied to known-age (1 1 ,000 yr) mammoths.

Our hope was to understand the diagenetic differences between collagenous and non-collagenous fossil

bone. Through micro-chemical separations, single amino acids were isolated using HCI elution from cation

exchange resin. These fractions were then combusted to CO2, and converted to graphite or FeC targets for

AMS dating. Results suggest that dating of fossil bone that has been poorly preserved (containing little collagen) could substantially underestimate the age. in contrast, valid dating was demonstrated when

residual collagen and isolated amino acids gave concordant ages.

Critical to these dating and tracer studies which involve multiple chemical steps is quality control and

estimations of overall uncertainties. A PC-database has been established for this purpose. The database

allows one to learn more about the chemical measurement process and the means to minimize the estimated

overall uncertainty.

135
4. Application of Radiocarbon Measurements and Multivariate Analysis to the Source

Apportionment of Polycyclic Aromatic Hydrocarbons

Ann E. Sheffield, Lloyd A. Currie, George A. Klouda, and Glen E. Gordon (University of Maryland)

The radiocarbon tracer technique was applied to the study of atmospheric, particle-borne polycyclic aromatic

hydrocarbons (PAHs) in Albuquerque, NM. Fifty-eight samples were collected during December, 1985. One

sampling site was located in a residential neighborhood, and a second site was near a busy roadway

intersection. Fine particles were collected from about 6:00 - 1 8:00 (day) and 1 8:00 - 6:00 (night). Residential

wood combustion (RWC) for home heat is common in Albuquerque, and we expected that the impact of

RWC would be highest at night, when temperatures are lower and people are more likely to be home.

Motor-vehicle emissions were expected to peak during the day, when traffic is heavier. Motor vehicles, a

fossil source, and RWC, a modern source, are the only significant sources of PAHs in Albuquerque.

The PAH-fraction was isolated from each sample by solvent extraction followed by liquid chromatography.

Levels of individual PAHs were determined by gas chromatography (GC) with flame ionization detection, and

compound identifications were confirmed by GC/mass spectrometry. Sixteen samples were selected for

radiocarbon analysis on the basis of a preliminary Factor Analysis (FA) and other relevant data. The

PAH-fractions from the chosen samples were analyzed for by Accelerator Mass Spectrometry (AMS)

using facilities at the University of Arizona.

Several compounds associated with softwood combustion were identified in the samples. The most

abundant of these were the methyl ester of abietic acid (MABA), the methyl ester of dehydroabietic acid

(MDHA), and 1 -methyl-7-isopropylphenanthrene ("retene"). Abietic acid and its methyl ester are components

of pine resin which decompose during combustion and in the atmosphere to give retene. Retene has been

suggested as a tracer for softwood combustion, as has MDHA, an intermediate compound in the reaction.

A number of common, unsubstituted PAHs were also identified, including benzo(ghi)perylene (BGP), a

potential tracer of motor-vehicle emissions.

The radiocarbon data were used to calculate the fraction arising from RWC (fpwc) in the PAH-fractions for

the sixteen samples analyzed by AMS. For each sample, normalized BGP concentrations were calculated

by dividing the observed BGP concentration by the sum of the concentrations of all PAHs in that sample.

These normalized BGP values gave strong, negative correlations with the fnwc data, which supports the use

of BGP as a motor-vehicles tracer in Albuquerque. While no single compound associated with softwood

combustion correlated with fnwc, when the concentrations of MABA, MDHA, and retene were added to give

a single value ('ADCS"), the normalized ADCS values gave strong, positive correlations with the radiocarbon

data. Presumably, the relative levels of MABA, MDHA, and retene are determined by a number of

factors (combustion temperatures, atmospheric chemistry, etc.), but their sum, ADCS, is less sensitive to

such variables and can serve as a tracer for RWC.

A Factor Analysis, performed on PAH data for 55 samples, indicated that two factors explained 95% of the

variance in the data set. One factor, attributed to RWC, had high loadings of ADCS and other softwood

products as well as low-molecular-weight PAHs such as fluoranthene and pyrene. The second factor,

attributed to motor-vehicle emissions, had high loadings of high-molecular-weight PAHs, including BGP.

Medium-weight PAHs such as benzo(a)anthracene and chrysene had moderate loadings on both factors,

which suggests that both emission sources contribute significantly to these species.

136
A combination of Multiple Linear Regression (MLR) and Target Factor Analysis (TFA) were used to estimate

source profiles for RWC and motor-vehicle emissions. These profiles were used to perform Chemical Mass

Balances (CMBs), a procedure which estimates how much of each compound in a sample is due to each

source. For samples with a high RWC contribution (i.e., large fRwc), RWC dominated the lower- and

medium-molecular-weight PAHs and contributed somewhat to the heavier PAHs. However, when the source

mixture was more balanced (fRwc = 55%), motor-vehicle emissions dominated the heavy and

medium-weight PAHs, and both sources contributed roughly equal amounts of the light PAHs. For the

samples analyzed by AMS, the RWC contribution predicted by CMBs give a strong, positive correlation with

the fRwc values.

In summary, both statistical methods (FA, MLR, TFA, and CMBs) and direct measurement (^"^C analysis)

were used to investigate the sources of PAHs in Albuquerque. While statistically based source apportionment

of PAHs is not new, the results have been subject to question because the degree to which PAHs degrade

or are formed in the atmosphere is poorly understood. Here, the radiocarbon results provide a critical,

independent measure of the source contributions and lend credibility to the statistical modeling results.

5. Maintaining the Primary Ozone Standard for the Domestic and International Communities

A.M. Bass and J. Norris

Since 1976, NBS has maintained an ozone standard calibration facility based on ultraviolet absorption

photometry. In 1982, the original photometer was replaced by an instrument of new design and greatly

improved performance. The new Standard Reference Photometer, which was developed as a collaborative

effort with personnel from the Environmental Protection Agency (EPA), is capable of performing assays of

ozone samples with an accuracy of ±1 .5%, which is the accuracy to which the ozone ultraviolet (253.7 nm)

absorption coefficient is known. The imprecision of such measurements is < 1 .0 ppb over the concentration

range of 0 to 1 00 ppb, and < 1 % over the range 1 00 to 1 000 ppb. The stability of the instrument is indicated

by a standard deviation of 0.4 ppb for 20 repetitive measurements of a fixed ozone concentration over the

working concentration range of 0 to 1000 ppb of ozone.

The stability and accuracy of the instrument led the EPA to adopt the NBS ultraviolet ozone photometer as

the instrument for primary ozone calibrations in the EPA regional laboratories. The EPA requested NBS to

construct ten of the NBS Standard Reference Photometers in order to establish their integrated, internally

consistent calibration network for environmental monitoring. The first instrument was certified and delivered

in 1982; eight more instruments have been delivered and installed since then, and the final one will be in place by the end of 1988. A regular schedule of intercomparisons between the EPA laboratory standard

instrument and the NBS Standard Reference Photometer assures the traceability of measurements in the

EPA network to the NBS primary standard.

During the past year we have similarly provided standard reference photometers to the National Swedish

Environment Protection Board and to the Canadian Atmospheric Environment Service. These will serve as

primary standards for Scandinavia and Northern Europe, and for the Canadian government network.

Periodic comparisons with the NBS primary standard will assure the integrity of the ozone standard in the

international community.

137
6. \on implantation Artifacts Detected by Secondary Ion Mass Spectrometry

D.S. Simons, P. Chi, J.F. Knudsen (The Aerospace Corp.), and H.B. Dietrich (Naval Research

Laboratory)

Secondary ion mass spectrometry (SIMS) is commonly used to measure the depth distributions of dopants

in semiconductors, where the dopant is introduced by high energy ion implantation. Often SIMS is used to

study the redistribution of the dopant brought about by subsequent thermal processing. In other cases, the

extent of ion channeling in a crystalline substrate is of interest, when the incident ion has been intentionally

aligned along a high symmetry axis. For these types of studies it is usually assumed that the ion implanter

is delivering a pure beam of the specified ion at a well-defined energy and current. Research done in our

laboratory during the past year shows that this assumption is not always valid, and that SIMS can be a very

useful diagnostic tool for detecting unexpected artifacts of ion implantation.

A series of arsenic implants in silicon, with implantation energies ranging from 25 keV to 200 keV, were profiled

by SI MS. The depths of the peaks in the arsenic implant profiles were plotted against the stated implantation

energies. A plateau in the data was seen between 50 and 1 00 keV. This anomalous behavior motivated a

direct measurement of the accelerating voltage by use of a high voltage resistive divider chain. It was

discovered that the energy meter on the implanter was not giving a reading proportional to the accelerating

voltage, and that the energy was overstated for values in excess of 50 keV, just as the SIMS measurements

had suggested.

Another example is related to a project designed to produce a Standard Reference Material for depth profiling

measurements by SIMS. The material selected for evaluation is amorphous silicon that has been

ion-implanted with at an energy of 50 keV and a dose of 1x10^^ atoms/cm^. The isotope was chosen

because independent profiles can be measured by thermal neutron depth profiling (NDP). Amorphization

of the silicon was carried out by implanting ^®Si at several energies up to 400 keV and at doses in excess of

10^^ atoms/cm^.

In one test sample it was found that the dose of ^°B was only 80% of the desired value, the remaining 20%

being ^ ^B. The ratio of doses of the two isotopes was determined from the SIMS profiles of the two isotopes,

whereas the absolute value of the ^°B dose was measured by NDP. In this case, the ion source of the

implanter produced a relatively weak boron beam so a large mass-resolving aperture had been used to

reduce the implantation time. However, this had the additional effect of allowing an unacceptable amount

of ^^B to be implanted along with the ^°B.

In this same experiment it was noted that the background level of ^°B in the SIMS profile was higher than

expected. A molecular ion interference at m/z 10 was suspected, possibly ®BeH'^. A SIMS profile of ^Be

was taken along with ^°B. A surprisingly large beryllium signal with an unusual 3-peak structure was seen,

which gave a clue to the origin of this contamination. Since the amorphization of the silicon wafer had been

done by implanting ^®Si at three different energies, it was very likely that the beryllium had been unexpectedly

introduced during the Si implantation. The cold cathode ion source of this implanter contains beryllium

components that are sputtered by the discharge, and silicon had been introduced into the source as SiP4

gas. Thus, beryllium was being implanted as the molecular ion ^Be^^F'*' along with the ^®Si. Since the level

of BeH'^ detected in the SIMS spectrum is typically between 0.1% and 1% of the Be'*' signal, the beryllium

present in this sample explains the high background level at m/z 10.

138
7. Electron Optical Bench for the Measurement of Fundamental X-ray Parameters

J.A. Small, D.E. Newbury, R.L. Mykiebust, and K.FJ. Heinrich

Since the development of the electron microprobe by Castaing in 1951 , quantitative x-ray microanalysis has

evolved into one of the most powerful methods of spatially resolved analysis. For most routine analyses, the

x-ray generation, absorption, and detection processes are well understood and correction procedures can

be used to perform routine quantitative analyses at a relative accuracy of ±2%. There remain, however,

several areas of microanalysis for which the electron beam-specimen interaction and the x-ray generation

and absorption are not well known. These areas include the analysis of particles and thin films, the analysis

of specimens containing light elements such as oxygen, and the analysis of specimens by the use of low

energy electron beams. One of the main limitations to further improvements in these areas is that our knowledge of the various physical interactions is derived principally from experiments and theoretical studies

performed in the period 1920-1960. The topic of medium energy (2-50 keV) electron-target interactions has

not been rigorously studied since that time. In a number of cases, data important to quantitative analysis

procedures are nonexistent or not measured with sufficient accuracy. Examples include the x-ray absorption

parameter and the backscattering correction, R, especially at low beam energies. Conventional electron

microprobes and scanning electron microscopes equipped with spectrometers are not suitable for such

measurements, because the design constrains the analyst to a single value of the angle between the beam

and the spectrometer axis.

During the past year, we have completed the construction of an electron/x-ray optical measurement bench

which offers flexible control of the electron beam, electron gun, and specimen. This system consists of an

electron gun and column, a specimen goniometer which is capable of three-axis orientation, and an x-ray

spectrometer mount which can be used to measure x-ray intensities at x-ray emergence angles of 0 to 70

degrees, where the x-ray emergence angle is defined as the angle between the detector and the specimen

surface. To achieve maximum flexibility in selecting experimental setups, the instrument was designed

around a vertical axis of symmetry with the electron-beam forming system mounted horizontally. Around

this vertical axis, the x-ray detectors have a freedom of movement that is limited only by the electron-gun

subsystem. The specimen may also be rotated on this vertical axis, creating a range of beam incidence

angles from 0-90 degrees. The combination of x-ray emergence and incidence angles allows for virtually

every conceivable beam/specimen and tilt/x-ray emergence angle arrangement of interest.

In the initial experiments on the instrument, we have measured the absorption of x-rays as a function of x-ray

emergence angle and compared the measurements to the existing literature expressions for x-ray absorption.

From these measurements, we hope to develop a more accurate term for x-ray absorption which can be

used in the quantitative analysis procedures for the electron probe.

8. Implementation of a Laboratory Accreditation Program (LAP) for the Analysis of Asbestos in

Bulk Materials and in Air

E.B. Steel, S. Turner, J.D. Verkouteren, J.M. Phelps, M.D. Johansen, V. Wang, and R.A. Fletcher

Regulations by the Environmental Protection Agency and laws propagated by Congress have propelled

asbestos abatement into a billion dollar a year industry. The need for standardizing the analytical methods

that determine the need for abatement and compliance with state and federal regulations is critical. The two

general areas requiring standardization are the analysis of bulk asbestos by polarized light microscopy (PLM)

and the analysis of airborne asbestos in buildings by transmission electron microscopy (TEM). To address

these needs, the Microanalysis Group has set up a National Reference Laboratory for Asbestos Analysis.

139
The new asbestos analysis laboratory includes new space, instrumentation, and personnel paid for initially

by a Congressionally mandated program with EPA. The new instrumentation includes x-ray powder

diffraction, light microscopy, and transmission electron microscopy (TEM) systems with computer and image

analysis support. We have hired four new people with skills in polarized light microscopy, mineralogy, x-ray

diffraction, crystallography, and transmission electron microscopy to develop and test standard

measurement methods and reference characterize materials for asbestos analysis.

The asbestos research program has three main goals:

(1 ) Develop standard methods, materials, and laboratory technical requirements for a laboratory

accreditation program for the analysis of asbestos in building materials;

(2) Determine methods of producing and characterizing air filter reference materials and quality

assurance requirements for transmission electron microscopic analysis of asbestos on air

filters; and

(3) Investigate air sampling methods for determining the concentration of asbestos in air for

application to abatement clearance projects.

The Microanalysis Group is helping the National Voluntary Laboratory Accreditation Program (NVLAP) set

up a laboratory accreditation program for bulk asbestos by developing four new bulk asbestos reference

materials, by determining the accuracy of the polarized light microscope method for the analysis of asbestos,

by developing and characterizing methods for the use of x-ray diffraction for the analysis of asbestos, by

writing technical and quality assurance guidelines and requirements for laboratories applying for

accreditation, by setting up a "model" laboratory In which the accreditation requirements and methods are

tested, by characterizing a set of lab proficiency testing materials, by selecting and training a team of over 50 laboratory assessors for site visits to the labs. This accreditation program will include more than 500

laboratories.

A TEM accreditation program for the analysis of asbestos in air, including approximately 100 labs, will start next year. To prepare for this program, we have developed methods of preparing proficiency testing

materials and run a round robin using these materials to test the main two steps in the measurement process,

sample preparation and fiber counting and identification techniques. Reference materials are being designed

and developed for use in calibrating identification techniques such as electron diffraction and energy

dispersive x-ray analysis. Quality assurance and other technical requirements are being determined and

realistically tested as we set up a "model" laboratory for the analysis of air filters. Other methods, such as scanning electron microscopy, are being investigated as alternatives or support techniques in the analysis

of asbestos in air.

Since techniques used in sampling the air and preparing air filters are poorly defined in asbestos

measurements, we are investigating the effects of various filter types, filter sampler designs, preparation

methods, as well as the effects of transportation on the concentration and distribution of asbestos and other

particles on the filter.

140
9. Molecular Compositional Mapping of Organic Compounds by Secondary Ion Mass

Spectrometry

J.G. Gillen and D.S. Simons

Desorption of intact organic molecules by keV ion impact and subsequent mass spectrometric analysis of

the sputtered secondary molecular ion flux has become one of the most widely used tools for analytical and

structural studies of thermally labile organic molecules. The techniques and instrumentation developed for

elemental ion imaging using Secondary Ion Mass Spectrometry (SIMS) are well established. We are attempting to extend these capabilities to the secondary ion imaging of molecular species.

A Cameca IMS-3f ion microscope was used for all organic SIMS studies. This instrument is equipped with a

resistive anode encoder digital imaging system. Molecular ion images were acquired with 8 keV Ar"^ ion

bombardment with typical primary ion current densities of 1-5 |iA/cm^. Model systems for imaging studies

were prepared by evaporating the compound of interest from aqueous or ethanolic solution onto copper

transmission electron microscopy grids. The presence of the deposited compound on the grid was

confirmed by observation of characteristic parent and fragment ions in the mass spectrum. In all cases,

molecular secondary ion images were generated using the parent molecular ion. Images with lateral

resolutions of ~ 1 ^m were obtained from a number of compounds including germicides, neurotransmitters,

neurotoxins, organic dyes, alkaloids, surfactants, and amino acids. Collaborations with NIH have been

initiated to study the capabilities of this technique for imaging organic compounds in biological tissue.

Another area of interest is the study of the fundamental interactions of energetic ions with molecular solids.

In general, molecular species are very susceptible to primary ion beam induced structural degradation. It is generally assumed that these degradation processes will limit the desorption of intact molecules to the first few monolayers of the sample; subsurface molecules are thought to be fragmented by the penetrating ion

beam well before they are exposed at the sputtered surface. Our results indicate that this is not the case. We

have routinely been able to detect and image parent molecular ions after sputtering some tens to hundreds

of nanometers into the sample. This suggests that molecular ion depth profiling is possible. The secondary

ion signal of these initially buried molecules may be optimized by an appropriate choice of experimental

parameters. For example, reduction of the primary ion energy by a factor of two increases parent molecular

ion signals by orders of magnitude. Related studies that will be initiated include measurement of the sputter

and secondary ion yields of organic molecules, the mechanisms by which compounds mixed in various

matrices used in organic SIMS become more resistant to primary beam induced degradation, computer

simulations of molecular sputtering, quantitative molecular analysis in solid materials, and the development

of a general model describing damage production in ion bombarded molecular solids.

10. Compositional Mapping with a Camera-Based Imaging System on an Ion Microscope

D.E. Newbury and D.S. Bright

In the technique of compositional mapping, the microstructure of a specimen is revealed in computer-generated digital images in which the gray or color scale is determined by the actual

concentrations of the various constituents and not by raw signal intensities. To achieve quantitative

compositional mapping, it is necessary to carry out a complete quantitative elemental analysis at each point

in an image. Rigorous corrections must be applied to the spectral data to account for all instrumental and

physical effects on the measured radiation, just as would be the case for conventional quantitative analysis

at a single location selected with a stationary beam. Digital compositional maps offer significant advantages

over conventional qualitative area mapping methods, including realistic depiction of quantitative

concentration information, greatly improved detection sensitivity, and flexibility for subsequent image

141
analysis. Previous work in our laboratory has established compositional mapping for the electron probe

microanalyzer.

Compositional mapping with secondary ion mass spectrometry (SIMS) carried out in the direct-imaging ion

microscope offers several advantages over mapping with the eiectron microprobe: (1 ) the SIMS signal rate

is of the order of MHz, so that images can be obtained in 10 seconds or less, even from trace constituents:

(2) the high peak-to-background leveis permit trace level imaging at the parts-per-million to parts-per-billion

level; and (3) elements across the periodic table can be detected at high sensitivity, including H, Li, Be, B,

and C.

To establish quantitative compositional mapping with ion images, a measurement technique has been

developed which relates the signals measured with the imaging detector system to signals measured with

the conventional pulse-counting multiplier detector as the reference. The imaging detector consists of

secondary ion-to-electron conversion at a two-stage channel plate, electron-to-photon conversion at a

transmission scintillator, photon-to-electrical signal conversion at a charge-coupled device TV camera, and

digitization of the electrical signal with an 8-bit analog-to-digital converter into a 512 x 512 image array.

Comparison of the signals measured on pure elements and homogeneous alloys with the two detectors

reveals that the response of the imaging detector depends strongly on the ionic species being measured.

Quantitative image measurements require the use of calibration curves to convert the image signal at each

picture element to the equivalent multiplier count. Compositional maps are then prepared by using sensitivity

factors measured on known alloys with the multiplier detector to convert the image intensities to equivalent

concentrations.

The SIMS compositional mapping technique has been applied to the characterization of chemical

microstructures in aluminum-lithium alloys and to high transition temperature (Tc) superconductors.

Microstructural features observed in Al-Li include second-phase particles, grain boundary segregation and

denudement, and surface segregation. In bulk, high Tc superconductors, complex microstructures are observed which include extensive segregation of a variety of chemical phases on a scale of 1 to 10

micrometers.

11. Concentration - Concentration Histograms: Scatter Diagrams Applied to Quantitative

Compositional Maps

D.S. Bright, D.E. Newbury and R.B. Marinenko

Compositional mapping with the electron microprobe requires standardization of, and instrumental and

matrix corrections to, the raw x-ray data to achieve a quantitative elemental analysis at each pixel location

in a map. The resulting arrays of compositional values are then displayed on a cathode ray tube as images

with selected gray or color scales to encode the range of compositional values. Often it is of interest to

establish the spatial correlation of two or more constituents. Such correlations can be conveniently presented

in visual form by the use of the well-known technique of primary color overlay, whereby two or three "single

band" (or single constituent) images are overlaid with the red, green, and blue guns of a color CRT. By the

laws of color addition, the appearance of secondary colors in the image field reveals regions of spatial overlap

of any two constituents. Whiie this is a powerful and widely used technique, it suffers from the deficiency

that it is difficult to visualize the compositional ranges of the single band images in a meaningful way in the

final color composite image. As an alternative, we have developed the concentration-concentration

histogram (CCH), which provides a visual display of the numerical relationships of the constituents and

promises to be useful for diagnosing experimental problems and evaluating data.

142
Histograms of images are often obtained by scaling the images to cover a concentration range of 0 - 255,

and then accumulating the intensities of each pixel in a one-dimensional array of 256 bins in the usual manner.

The concentration-concentration histogram is a two-dimensional analog of this, and is a type of scatter

diagram. Each pixel in one image, A(x,y), representing element A at coordinates (x,y), is associated with the

corresponding pixel in the other image B(x,y). The concentrations represented at this location are accumulated in a 256 x 256 pixel array CCH, where the abscissa of the CCH corresponds to the concentration

of A and the ordinate to the concentration of B. The accumulated number In each pixel in the CCH can be

displayed with selected gray or color scales to represent the CCH as an image. Such a visual display of the

CCH allows the analyst to recognize quickly and quantitatively those compositional value pairs which occur

commonly in the original single band images. The CCH often shows intense spots where most of the pixel

pairs tend to clump, along with some points or bins of very low intensity representing only one or two pixel

pairs for the original quantitative maps. We have found the scattered low intensity points to be as important

as the clumps. To visualize these low Intensity points as well as the high intensity clumps, the accumulated

number in each pixel in the CCH can be displayed by means of a scale which presents the wide dynamic

range of the data to an observer. A "thermal color scale" is especially effective for this application.

A powerful aspect of the CCH is the "trace back" capability to highlight selected spatial compositional features

in the original images according to concentration features recognized in the CCH. Once a feature of interest

In the CCH has been Identified, the procedure is reversed to identify the specific pixel locations in the original

compositional maps which correspond to selected concentration-concentration conditions. This

combination provides a powerful tool for the characterization of chemical microstructures.

12. Compositional Mapping by Electron Probe Microanalysis of Bulk and Thin-Film

Superconductors

R.B. Marinenko, D.E. Newbury, B.B. Thorne, E.B. Steel, and J.D. Verkouteren

Compositional maps are prepared by digitally stepping the electron beam of the electron probe

microanalyzer (EPMA) in a predefined array on the surface of the specimen. At each point in the array, x-rays

from the elements of interest are accumulated for a preselected time period, using wavelength dispersive

(WDS) and/or energy dispersive (EDS) spectrometers. With combined WDS/EDS spectrometry, as many

as ten elements can be mapped simultaneously. Each pixel in the resulting map is corrected for dead-time,

background, and when necessary, for spectrometer defocussing. The concentration of each element is calculated at each pixel with complete correction for matrix effects. The result is a map of quantitative

elemental distributions which can be displayed on a gray scale or in color on an image analysis system. This

mapping technique is ideal for studying regions from about 20 ^m to 1 cm along an edge. Map sizes can

be 64 X 64, 128 x 128, or 256 x 256 pixels.

Compositional mapping has been used in our laboratory to study bulk and thin-film specimens of the 1-2-3

Yttrium-Barium-Copper high-temperature superconductors which are being produced in NIST laboratories.

The bulk materials are prepared from intimate mixtures of the oxide powders which are subjected to a series

of mixing, pressing, grinding, sintering, and annealing steps. Thin films are prepared by RF sputtering or thermal evaporation of the oxides onto a substrate, which initially produces a homogeneous material that

must be subsequently annealed in oxygen to produce the high Tc state. The resulting product is dependent

upon the experimental conditions used in preparation. Physical properties, such as the critical current

density, magnetic susceptibility, brittleness, and sharpness of the superconducting temperature transition are related to the microstructure. Quantitative compositional mapping is providing a valuable link to correlate

and understand the processing procedures and the resulting physical properties. In addition, reactions

between the melt and the crucible walls have been studied in depth.

143
Maps of bulk specimens have shown that these superconductor materials are inhomogeneous and porous.

The superconductor phase, which has a composition of YBa2Cu307-x, is usually observed in conjunction

with other phases that have been identified as BaY2CuOs (called the "green" phase) and a combination of

Cu02 and BaCu02. The presence of these phases has not been attributed to unreacted material since the

grain size is five times larger than the starting material; rather, their presence has been attributed to

unexpected melting, during sintering, which results in segregation. The pores are believed to be an asset in the production of the superconductor phase as they allow excess oxygen needed in the formation of this

phase to enter the specimen during sintering. The RF sputtered films, which are about 1 ^im thick, have also

been shown to become inhomogeneous after annealing.

Recently, we have begun to study a new type of high-Tc superconductor, 1 -1 -1 -2 Bi-Sr-Cu-Ca oxides, which

is in the form of thin films. Laser ablation is used in the production of these films. Because there are more

than three elements of interest, EDS mapping has been used. Initial studies have shown that these films are more homogeneous than earlier preparations of other high-Tc superconductors.

13. Funda mental Studies of Matrix Correction Models for Quantitative Electron Probe

Microanalysis

K.F.J. Heinrich

The accuracy of quantitative electron probe microanalysis has not significantly improved in the last decade

and is below the levels thought to be achievable. Although several parameters of significance have not been

fully characterized as yet, work by competent investigators has diminished. Most present users depend on

the instrument manufacturers for the installation of data reduction software. Presently used routines are quite

complex and Involve many parameters: users rarely specify all pertinent parameters, and therefore,

statements concerning accuracy of methods are at best of limited usefulness. In particular, claims of

improvements in fundamental approaches must be considered doubtful when the methods used to prove

them are not fully specified. To further complicate this situation, the databanks on relative intensities obtained

from binaries which are used to prove such claims, are tainted by the inclusion of imprecise measurements,

some taken before accurate detector systems were available. It Is quite typical that such claims are not

supported by the application of the proposed method by other operators.

We have therefore begun the following efforts to increase accuracy in PMA by the classical model (normal

beam incidence upon a thick uniform specimen):

Use, in a menu-type program, a set of carefully purged data from which old or not self-consistent

groups of data will be eliminated "a priori". The menu will permit switching values of parameters and

algorithms for various correction aspects. Including the newest proposals of parameters and methods.

Use only those experimental data for the evaluation of each aspect of correction (absorption,

fluorescence, etc.) which depend significantly upon the choice of models and parameters. Therefore,

the random spread of the results will be reduced.

Propose Improved models and investigate uncertain parameters after evaluating and comparing

several sets of parameters and models, including the Monte Carlo technique. We will then use the

Monte Carlo method to investigate ways in which less traditional configurations (inclined electron

beam, thin films, layered specimens, fibers, and submicron particles) can be used quantitatively with

increased accuracy.

144
To make the comparison of approaches more objective, we will propose a minimum set of data that must

be given to fully characterize the process. Based on our overall results, we will also propose the best methods

for use by instrument manufacturers in their software programs.

14. Raman Microprobe Spectroscopy Applied to the Characterization of Superconducting Materials

E.S. Etz, T.D. Schroeder, and F.S. Pereles

The photon spectra of superconductor materials are of interest as they provide fundamental information on

structure-property relationships. Hence, Raman spectroscopy has come to play a central role in the

characterization of high-Tc superconductor materials. The technique provides a sensitive probe of both the

phonon structure of the superconductor and of impurity phases in these materials. Numerous reports,

principally from studies of bulk samples, on the Raman spectra of these materials have appeared, and the

literature is well developed with respect to the interpretation of these results. The spectra provide diagnostic

information on structure, bonding, and symmetry, as well as the dynamics of structural phase changes.

Micro-Raman spectroscopy extends these investigations into the realm of microscopic dimensions to

complement other (i.e., elemental) microprobe techniques for spatially resolved mapping of compositionally

different domains. We have applied the NBS-developed scanning Raman microprobe (with photon counting

detection) principally to the study of several types of samples in the yttrium-barium-copper-oxygen

(Y-Ba-Cu-0) system. These are among the first few micro-Raman studies reported to date. The goal is to

provide microstructural characterization with a spatial resolution of a few micrometers, specifically with

regard to crystal structures and phase relationships, compositional homogeneity, and oxygen stoichiometry.

These findings are examined with reference to various methods of preparation, processing, and heat

treatment, and are correlated with the physical properties determining superconductivity. In the Y-Ba-Cu-0

system, the samples examined are polycrystalline ceramic powders, sintered pellets, and single-crystal

material, all of the 1-2-3 composition YiBa2Cu307-x, with x varying between 0 and 1, the range over which

this system is known to lose its superconducting properties, and the crystai symmetry changes from

orthorhombic to tetragonal in this transition. The samples examined have all been prepared and extensively

characterized by other methods (e.g., x-ray diffraction, magnetic susceptibilty and resistance measurements)

in investigations by collaborators of the Ceramics Division of NiST. In the micro-Raman measurements of

these samples, we have obtained analytically useful room-temperature spectra of the principal phases in this

system with the intent to identify also the relevant parasitic phases of composition Y2 BaCu05, Y2CU2O5 , BaCu02, and CU2O. These results show that micro-Raman spectroscopy can provide unique information on

the identity of distinct microscopic phases not revealed by bulk methods of structure determination. Overall,

the spectra indicate a compositional heterogeneity which, at the same microscopic level, has also been

revealed by electron probe microanalysis. We are also applying the Raman microprobe with multichannel

detection (PARC OMA-3 with intensified diode array) to the study of these samples to elucidate the multiplex

advantage in the acquisition of the spectra of these weakiy scattering solids. Work in progress focuses on

some of the newer compositions of superconductors. As part of our research program to provide analytical

support to other NIST groups in the full characterization of these materials, future investigations will focus

on the study of precursor species of significance to several methods of synthesis, and the environmental

degradation of these samples due to their sensitivity to moisture.

145
15. XRF Analysis of SRM 2704 (Buffalo River Sediment) by Automated Borate Fusion

Z. Wang and P.A. Pella

A new SRM 2704 (Buffalo River Sediment) was analyzed in the past year by several methods in the Center

for Analytical Chemistry including x-ray Spectrometry. All measurements leading to the certification of this

material were coordinated through M.S. Epstein of the Inorganic Analytical Research Division. Eight samples

were submitted for the XRF determination of the elemental homogeneity and quantitative analysis of twelve

elements. A loss-on-ignition of 9.3% was determined by heating severai samples to 1050 °C in a muffle

furnace. Duplicate samples of 1.100 g each were fused with 6.000 g of lithium tetraborate in an automated

fusion apparatus in platinum-gold crucibles at 1050 °C and the resultant homogeneous solution as fused

glassy disks were ground and polished on one side prior to measurement. For determination of

inhomogeneity, a total of 16 fused specimens were measured for Al, Si, P, K, Ca, Ti, Mn, Fe, Zn, Sr, Rb, and

Zr. Nine fused specimens were measured for elemental composition. The computer program NBSGSC was

used to correct for interelement x-ray absorption effects. Standard samples were prepared from compounds

better than 99.95% pure, such as oxides or carbonates.

Analysis of XRF intensity data for sixteen specimens showed no statistically significant differences in the

elemental composition of this material. The XRF results of the quantitative analyses of this material for certain

key elements such as Al, Si, P, K, Ca, Ti, Mn, and Fe were found to be in excellent agreement with the certified

values. In addition, four SRMs were analyzed concurrently with SRM 2704 quality assurance samples and

analyzed.

16. Total Reflection XRF Analysis with a Rotating Anode Source - Some Preliminary Observations

P.A. Pella and R.C. Dobbyns (IMSE)

Energy-dispersive x-ray fluorescence spectrometry (EDXRF) is a widely used analytical technique because

it is non-destructive, rapid, and capable of multi-element analysis. However, a major drawback is its relatively

low sensitivity for trace analysis when compared to other trace element techniques such as neutron activation

and ICP. To improve (i.e., lower) the minimum detection limit (mdl) in EDXRF, techniques to enhance the

signal relative to the background need to be developed. This can be accomplished through the use of bright

x-ray sources such as synchrotron radiation or by a rotating anode source, both of which are well suited for

use with reflection geometry to reduce the background contribution.

Previously, we demonstrated sensitivity (mdl) below 1 ppb for selenium in SRM 1643b Trace Elements in Water and analyzed SRM 1598 Bovine Serum for selenium at the 42 ppb level. This work was published in 1988 this year in Anal. Chem. and described analyses using monochromatic, energy tunable, synchrotron

radiation in a total reflection mode. We plan to continue our work using synchrotron radiation during the

next year and to investigate the potential of the high flux white beam for trace analysis.

One alternative to synchrotron radiation is a high intensity commercial rotating anode source which can also

be used in the total reflection geometry for trace analysis. Although substitution of a rotating anode source

for synchrotron radiation will result in somewhat poorer detection limits, there are several advantages to be

gained with a laboratory based system such as convenience and access. Much of our work this year was

directed to the fabrication of an in-house total reflection spectrometer. A double-crystal spectrometer was

purchased for this purpose to interface with a rotating anode source. Additional instrumentation was

designed and constructed for orienting the x-ray detector with respect to the analyte sample. A tube was

built so that the path from the exit of the source to the entrance window of the double crystal spectrometer

is vacuum tight to allow either a reduced pressure or a Helium path. The double-crystal spectrometer

146
functions as a means to provide some tunability of x-ray beam energy and size, and to control and maintain

the required substrate reflector critical angles relative to the x-ray beam. Preliminary measurements have

been performed with this system using a focused x-ray beam to characterize the topography of some

metallurgical surfaces.

We now plan to determine minimum detection limits for selected elements using this system and make a

relative comparison of its sensitivity to the synchrotron source system in the total reflection geometry. Several

types of optically flat substrates will also be characterized in an effort to obtain chemically pure substrates

to minimize the chemical blank.

17. Development of Immobilized Chelator Membranes for Preconcentration of Trace Elements

P.A. Pella and Z. Wang

Increase in sensitivity of x-ray analysis by pretreatment of the sample prior to analysis has long been

recognized as an important goal in this field. We have developed several techniques during the past ten

years for preconcentration of samples to permit quantitative x-ray analysis at ppb levels, especially for liquid

samples where as much as one liter can be preconcentrated. These techniques have basically involved the

prior separation of the trace elements (usually transition elements) from the major constituents using column

chromatography. The trace elements can then be concentrated on paper filters impregnated with

Ion-exchange resins. The recent availability of commercial ion-exchange resins dispersed in thin films of

porous Teflon should spark a renewed interest In this technique.

To decrease the sample preparation time by eliminating the need for prior removal of major sample

constituents requires that thin substrates be developed that are much more selective than the

Ion-exchangers. For this reason, we have developed substrates from cellulose fibers to which we have

attached covalently bound chelating groups such as dithiocarbamate or oxine (8-hydroxyquinoline). We

have prepared derivatized filters from several grades of commercial filters of different thickness and evaluated

their performance with regard to analytically useful capacity, mean exchange rate, and suitability for trace

element preconcentration.

For purposes of evaluating trace element recoveries, we chose to analyze Fe, Cu, Zn, and Cd in NIST/SRM

1566 Oyster Tissue. The tissue samples were first treated with nitric acid in a microwave oven followed by

treatment with perchloric acid to ensure complete decomposition of organic material. The residue was

dissolved In acetate buffer at pH 6.0 and the solution pumped through a filter for a fixed time to collect the

trace elements. The calibration curves prepared using standard aqueous solutions of the trace elements

demonstrated good linearity and reproducibility of recoveries up to at least 500 micrograms of element per

filter. However, we found variable recoveries when the NIST/SRM Oyster Tissue was analyzed. We found

that the elemental capacity of these derivatized filters varied considerably, e.g., sometimes by as much as a

factor of two. We believe this has a marked influence on the recoveries of the trace elements in the Oyster

Tissue.

In an effort to overcome the variability of the elemental capacity of the filters, preliminary work has been

performed to prepare derivatized paper pulp from which sheets of appropriate size can be fabricated. This

procedure should result In filters of more uniform and reproducible elemental capacity. We are working

closely with the NIST Fibrous Systems Division to develop an Improved derivatized filter and expect to

evaluate its performance during the coming year.

147
18. Preparation and Verification by Electron Capture Detection of Primary Gravimetric Standards

of Volatile Toxic Organic Compounds (VTOC’s) at the 15-500 Parts-Per-Trillion Level

G.C. Rhoderick

The program to prepare standards of VTOC’s for EPA to use in the programs to monitor hazardous waste

sites and incinerator burns has been in existence for many years. Until now, all of the mixtures prepared

were at the ppm and ppb levels, but recent needs have required us to push our standards generation

capabilities at least an order of magnitude lower in concentration.

Gravimetric standards containing halogenated toxic organic compounds were prepared at the 15-500 ppt

level. These standards were blended using the NIST microgravi metric procedure for volatile organic

compounds. Compounds in these mixtures include bromomethane, chloroform, 1,2-dichloroethane,

1,1,1-trichloroethane (methyl chloroform), trichloroethylene, carbon tetrachloride, tetrachloroethylene,

1 ,2-dibromoethane and trichlorofluoromethane (CFC-11). Initially, standards were prepared at the 10 and

100 ppb levels and then ppt level standards were made by transferring a precalculated amount of gas from

these standards to new cylinders and adding nitrogen to the appropriate pressure. These standards are at very low levels and contamination could easily take place in the preparation procedure and the system.

Therefore, the pure organic reagents were analyzed to quantify impurities. The matrix nitrogen was also

carefully analyzed and impurities were quantified. The set of standards were analyzed on a gas

chromatograph equipped with an electron capture detector. The data were then plotted using the area counts

versus the gravimetric concentration for each individual compound and the predicted concentrations were

determined by a quadratic equation. The results showed good agreement between the gravimetric

concentrations and those predicted from the curve fit which confirmed the internal consistency of the set of

standards. The absolute average of the residuals (predicted minus gravimetric concentration) for a given

organic compound In the set of standards was 2 ppt maximum which is considered excellent at this

concentration level.

The standards have been used to certify mixtures containing these compounds for several research groups.

They have also been used to certify mixtures of toxic organic compounds for the State of California Air

Resources Board for use in their air quality programs.

19. Developed and Certification of the First SRM Containing ppb Levels of Multiple Volatile Toxic

Organic Compounds

W.L. Zielinski, Jr., G.C. Rhoderick, and W.R. Miller

Analyses of ambient air samples for volatile toxic organic compounds in the low ppb range are routinely

conducted using GC and GC/MS systems that previously have been calibrated with appropriate gas

standards. Such calibrations are tedious and prone to calibration errors when several standards must be

used to cover a sufficient number of organic compounds. In an attempt to relieve this situation, research

has been conducted at NIST over the past several years to assess the feasibility of developing a gas standard

containing a substantial number of these compounds. This research has led to the refinement of preparative

and analytical techniques that has resulted in the development of stable gas standards containing as many

as 18 volatile toxic organic compounds in the low ppb range in the same gas cylinder, and to the issuance

of a Research Material (RM) representing a limited number of cylinders containing a seven-component

mixture at 5 ppb (RM 851 1

). The compounds in the 1 8 component mixture are:

148
Benzene

Bromomethane

1,3-Butadiene

Carbon tetrachloride

Chlorobenzene

Chloroform

1

.2-

Dibromoethane

1

.2-

Dichloroethane

Dichloromethane

1 ,2-Dichloropropane

Ethylbenzene

Tetrachloroethylene

Toluene

1,1,1-Trichloroethane

Trichloroethylene

Trichlorofluoromethane

Vinyl Chloride

o-Xylene

The stability of the gases has been determined over a several month time period. Only 1 ,3-butadiene exhibits

questionable stability. Plans currently are underway for the development of the first NIST Standard Reference

Material (SRM) of a multicomponent mixture of volatile toxic organic compounds at the low ppb level. This

SRM will contain 18 pure compounds, each at a nominal concentration of 5 ppb by mole in a high-purity

nitrogen matrix gas. The concentrations will be certified by intercomparative gas chromatographic analysis

against absolute gas standards that are prepared by NIST using a microgravimetric procedure. The

1 ,3-butadiene stability question will have to be resolved before this gas can be certified in the mixture.

Based on extensive research and experiences with numerous gas standards containing the other 17

components and related compounds in the mid to low ppb range, it is anticipated that the uncertainty of the

certified concentrations in this SRM will probably be on the order of 10% relative at the 95% confidence level

with a stability of several years. A contract has been let for the commercial preparation of a lot of 20 cylinders

containing mixture in accordance with NIST technical specifications. Several state and Federal agencies

have already expressed interest in acquiring this SRM, which should be available from the NIST Office of

Standard Reference Materials by the summer of 1989.

20. Development and Application of Coulometric Titration as a Direct Measurement of COg

Compressed Gas Cylinder Mixtures

G.D. Mitchell

CoulOmetry has been established as an important and reliable method for the determination of sulfur oxides

and other electroactive compounds, especially at low concentrations. It is capable of producing analytical

results of very high precision and accuracy. A constant flow coulometric titration system for the analysis of

SO2 has been developed, exhaustively characterized and described in previous reports. The system was

designed and evaluated to determine that 1) the electrode reaction proceeds at a high current efficiency: 2)

no analyte species escapes analysis and no electroactive species enters the analytical compartment; and

3) the end-point indicator is of high precision and accuracy. The system was slightly modified for the analysis

of CO2 and consists of a dual compartment electrochemical cell, a semi-aqueous absorption solution and

electrolyte, an optical end-point detection system, a silver anode and platinum cathodes, and an accurate

and precise flow control system. One application of the system was in the atmospheric CO2 standards

program. At present the reference method for the analysis of atmospheric CO2 standards is non-dispersive

Infrared spectrometry (NDIR) using gravimetrically prepared reference standards as calibrants. Selected

CO2 mixtures were analyzed using the coulometric system to evaluate whether a bias existed in the reference

standards. This was done as part of our program to verify our standards by at least two methods. The

analysis of one particular mixture by coulometry showed it to be 341.7±1.7 ppm CO2 while the value from

gravimetry was 342.0±0.4 ppm. Within the analytical uncertainties, both methods give the same value.

149
The coulometric system was then tested to determine a lower detection level. Preliminary results showed

that without any further modifications, the lower level was about 1 ppm with a 3:1 signal to noise ratio. The

upper limit has not been established but will be dependent on the absorption capacity of the reactant solution

calculations Indicate that it can be as high as 7%. The system has not been evaluated for response to

Interfering gas species; therefore, it is presently being used to evaluate only cylinder gas mixtures.

21. Development of Isotope Dilution Mass Spectrometry for Absolute Determination of Carbon

Dioxide Abundance in Air

R.M. Verkouteren

Cooperation between the Gas Metrology and Mass Spectrometry Groups in the Center for Analytical

Chemistry has led to the development of an absolute method for the determination of the abundance of CO2

in air at levels of 300-400 ppmv. The method utilizes high-precision manometry and isotope dilution mass

spectrometry (IDMS).

In this method, an aliquot of air is precisely measured and equilibrated with a precisely measured amount of

C-1 3 depleted (spike) CO2. The isotopically altered mixture of CO2 is then isolated from the air and measured,

by mass spectrometry, to quantify the extent of isotopic alteration. The concentration (in ppmv) of CO2 in the original air can be calculated using the formula:

CCO2

• 10*® Pspk Vspk Tair Zair

Pair Vair Tspk ZCO2

Fmix - Fspk

Fair - Fmix

where the factors are ratios of pressure, volume, temperature and compressibility between the spike and air; the bracketed term is the ratio of differences in isotopic fractional abundances (F) between the CO2 of the

air, spike and mixture.

The gas mixing system consists of two electropolished and chemically passivated stainless steel volumes,

the ratio of which was determined by gas expansion methods. Air and spike CO2 are measured in these

volumes and then mixed through a pump-driven recirculating loop. Subsequently, the CO2 mixture is frozen

out nearly quantitatively in a liquid argon cold trap. Isotopic compositions of carbon dioxide are determined

using a mass spectrometer designed and constructed at the NIST. The instrument is a 30 cm radius, 90°

deflection magnetic sector mass spectrometer with extended flight path geometry and a triple,

deep-Faraday-cup collector.

The goal for absolute uncertainty at the 95% confidence level was set at 0.1 % with an analytical imprecision

at that level or better. Propagation of uncertainties in all accountable variables (e.g., ratios of pressure,

temperature, volume and isotopic composition) leads to an estimation of total absolute uncertainty of 0.13%.

Carbon dioxide abundance values generated by IDMS compare favorably with those of gravimetry, the

definitive method at present for SRM certification. For a particular sample of real air, IDMS gives 347.43 ±

0.45 ppm while gravimetry gives 347.6 ± 0.4 ppm. Analytical imprecision of replicate analyses via IDMS is also quite satisfactory: 0.1 1 %.

It is planned to measure a series of CO2 samples at different concentrations, to refine further the measurement

methodology, and to explore the possibility of applying the system to other gaseous components of our atmosphere.

150
22. Development of a Low-Level Nitric Acid Generator

L.J. Nunnermacker, R.R. Dickerson (University of Maryland), and W.D. Dorko

A calibration source has been developed and characterized, which can be used to generate HNO3

concentrations in the parts-per-million by volume (ppmv) and sub-ppmv range with verifiable accuracy. The

reaction which occurs is;

+ AgNOafs) HN03(g) + AgCI(s) AG° = 13.3 kcal mol

-1

Nitric acid was generated by passing a gaseous mixture of HCI in N2 (in this Instance a nominal value of 93

ppmv) through a 145 mm length of 4.0 mm I.D. teflon tubing containing 6.21 g (~6-8 mesh) of crystalline

silver nitrate. The concentration of the HCI mixture was found to be 94.3 ppmv ±2.1 (as measured by ion

chromatography (1C)) and was stable over a period of two and a half years. The flow of HCI was maintained

by a 0.5 L min'' mass flow controller (MFC) with Kalrez 0-rings to minimize corrosion and a low flow of

nitrogen was passed through the flow controller (when the HCI was not used) to keep the flow controller dry

and prevent corrosion. Lower HNO3 concentrations (< 87 ppmv) were obtained by dynamically diluting the

flow from the generator with "zero air". Background concentrations of HNO3 were determined by replacing

the HCI flow with an equivalent flow of nitrogen or zero air over the AgN03 column. All connections, solenoid

valves, and tubing in the system were TFE teflon unless otherwise specified.

The effluent of the AgNOs column was tested for HNO3, using three independent techniques:

chemiluminescent detection (CD), ion chromatography (1C), and tunable diode laser absorption

spectroscopy (TDLAS). At a column temperature of 20 ®C, the three distinctly different measurements of

HNO3 ([HNOsJcd = 85.2 ± 2.6 ppmv, [HNOsJiC = 79.6 ±6.1 ppmv, [HNOsItdlas = 76.9 ± 6.7 ppmv) agree

within the estimated accuracies of each technique. Dilution of the column effluent produced concentrations

of HNO3 at lower levels and was linear from 0.01 to 87.4 ppmv (as determined by CD) indicating good mixing

and negligible surface adsorption of nitric acid. The CD technique was used on a daily or weekly basis to

check the output of the generation system over a period of three months. The HNO3 produced during this

time was remarkably stable and no change in efficiency was observed.

The [HNO3] ultimately depends on the [HCI] and thus, the flow rate of the HCI could be an important factor.

However, this system demonstrates very little HCI flow dependence in the range of 100 to 500 cm^ min'\

and produced 3.6% less HNO3 at the lower flow rate. Additionally, the system was relatively insensitive to

temperature changes and the [HNO3] increased by only 4% from 20 to 70 °C.

23. Characterization of the Output of a Nitric Acid Generation System Using Tunable Diode Laser

Spectrometry and Chemiluminescence Detection

L.J. Nunnermacker and R.L. Sams

A new calibration source of gaseous nitric acid has been developed, based on the conversion of gaseous

hydrogen chloride to HNO3 on solid silver nitrate. A description of the generation system is given in the

previous report. Here we will describe the analytical efforts to characterize the generator output.

Three different analytical techniques were used to quantify the HNO3 content of the generator:

chemiluminescence detection (CD), tunable diode laser absorption spectroscopy (TDLAS), and ion

chromatography (1C). Fluorescence of NO2 is the heart of the commercially available CD system. First, all NOy’s are converted to NO by passing the gas over a hot stainless steel substrate, then the NO is converted

to excited NO2 by a reaction with ozone. The excited NO2 then fluoresces which is detected by a

151
photomultiplier tube and recorded on a strip chart recorder. TDLAS relies on the highly sensitive technique

of second derivative absorption spectroscopy. The diodes emit very narrow band infrared radiation which

is detected after passing through the gas of interest. Each gas has a unique infrared spectrum which leads

to a very selective and sensitive method of molecule detection. When the absorption cross section of a

rotation vibration line is known, the concentration of the molecule can be determined. In 1C, the sample gas

is bubbled through an absorbing solution after which aliquants of the solution are injected into an 1C to effect

the separation and then detection of Cl‘. The 1C is calibrated with a chloride salt solution for quantification.

The final concentration of 80.6 ppmv HNO3 was measured using these three different techniques. With the

conversion column operating at 20 ®C the HNO3 concentrations measured by the three different methods

were as follows: [HN03]cd = 85.20 ± 2.6 ppmv, [HN03]tdlas = 76.9 ± 6.7 ppmv, and [HN03]ic = 79.6 ±

6.1 ppmv (uncertainties are I 0). The effluent of the AgN03 column was also tested for residual HCI, in the

form of chloride ion (Cr), but no Cl' was detected using 1C. Other oxides of nitrogen tested included NO,

NO2, and MONO. TheHN03 gaswas >96% pure containing <2.5% MONO (estimated maximum) and 1.2%

NO2 as determined by TDLAS, and <0.1% NO as determined by CD.

Although 1C and TDLAS are more specific techniques for measuring HNO3, both techniques require much

sample preparation and analysis time. CD, as mentioned above, is commercially available and easy to use.

Nitric acid is measured using CD by alternating the sample flow through a nylon filter or bypassing the filter. The difference in the two signals is HNO3 (or other acidic gases including MONO and HNO4). Because this

method was the most non-specific of the three, it delivered the highest (85.2 ppmv) concentration of HNO3. The TDLAS system was then used to confirm that, indeed, HNO3 was being generated and to quantify the

concentration using the ro-vibration line at 1722.4390 cm'^ in the V2 band of HNO3. The relative precision

of the absorption measurements was ±2.6 ppmv, however, other factors such as reproducibility between

runs and the knowledge of the absolute cross section increased the uncertainty to ±6.1 ppmv at 76.9 ppmv.

The [HNO3] determined by TDLAS was definitely a lower bound, since most of the errors would tend to

decrease the observed concentration (losses to the White cell’s walls and possible laser broadening of the

line).

24. Study of the Chemistry of NQ^/HNOg/HgO in Compressed Gas Cylinder Mixtures

B.C. Cadoff, W.D. Dorko and J.E. Suddueth

Our interest in the study of the chemistry, kinetics and equilibria of compressed gas mixtures containing

NO2, HNO3 and H2O stems from the fact that virtually all cylinders containing NO2 in air, from the low to the

high ppm levels, are actually NOx mixtures containing both NO2 and HNO3. The concentration levels of

HNO3 have been quite variable, ranging from less than 1 % to approximately 50% of the NOx value. Different

cylinder mixtures exhibit different behavior. Some cylinders, after standing unused for months, will yield a

higher HNO3 level when first analyzed; and, with continued sampling over a period of an hour, the HNO3

level will drop to a constant level. However, the total NOx level will remain constant from the beginning.

Other cylinders will show constant HNO3 and NO2 concentrations throughout the analyses.

For many analytical purposes, a constant composition NOx cylinder is quite acceptable, and generally we

have found these cylinders to be stable in NOx concentration over a period of at least a year. One of the

analytical methods used in this laboratory, as well as many other laboratories is the chemiluminescent

detector equipped with a high temperature converter which quantitatively reduces the higher oxides of

nitrogen, such as NO2 and HNO3, to NO. The NO thus produced reacts with O3 to give the characteristic

chemiluminescence which is detected by the phototube in the analytical Instrument. When used in this type

instrument, a cylinder can contain varying levels of NO2 and HNO3 and still be a useful calibration standard.

152
However, there is also an interest in cylinders that contain either pure NO2 or pure HNO3. We are now trying

to produce pure HNO3 in cylinders and the known chemistry of the nitrogen oxides suggests that this may

be possible.

In the absence of light, the following reactions take place.

O2 + 2NO — 2NO2 ( 1

) 3NO2 + H2O = 2HNO3 + NO (2) 2NO2 = N2O4 (3) NO + NO2 = N2O3 (4) NO + NO2 + H2O = 2HNO2 (5)

Reaction (1) goes to completion and is a rapid reaction, especially in NO2 cylinders which contain air (21%

O2). The other reactions are equilibria for which the rate constants are not available. Reaction (2) is especially

interesting since this is the reaction that produces HNO3: it also forms NO, which would be expected to react

rapidly with the O2 present to form NO2. Thus, we predict that this reaction would go to completion as

follows;

4NO2 + O2 + 2H2O ^ 4HNO3 (6)

This reaction also shows that for each N02that reacts, an equivalent HNO3 is formed, which would explain

the observed constant NOx composition of these cylinders. Note too, that in the presence of O2, the above

reactions predict the presence of only NO2, HNO3 and H2O.

We have performed experiments in which we have introduced a H2O vapor in nitrogen mixture into cylinders

of NO2. In the first experiments with 1000 ppm NO2 cylinders, we have observed expected dilution of the

NOx, due to the addition of the wet nitrogen, and an Increase in HNO3 amounting to about half the expected

increase based on reaction (6) after a period of several days. These experiments will continue and the

cylinders will be examined periodically over a period of several months to note any changes In NO2 and

HNO3 concentrations.

25. Development and Characterization of a Low Concentration HpOp Generation System

R.L Sams, B.C. Cadoff, and W.D. Dorko

Hydrogen peroxide has been shown to be a significant atmospheric reactant in the chemical transformations

leading to acid rain. In particular, H2O2, which oxidizes SO2, is now regarded as an important contributor

to the ultimate H2SO4 concentration in the atmosphere. We have begun a program, supported by ERA, to

generate and analyze mixtures of H2O2 at the low ppb level to assess atmospheric H2O2 concentrations.

The generation of ppb levels of H2O2 has been reported by several workers and involves either flowing air

directly over a solution of H2O2 or more usually, flowing air through a permeable tube through which H2O2

enters from the surrounding solution. The concentration of H2O2 generated follows Henry’s law and the

concentration appears to be stable, provided the temperature of the H2O2 solution Is kept constant and the

solution concentration does not change. The output of such a generator could be analyzed directly, and

153
linearity of concentration with flow rate could be confirmed by successive dilutions down to the desired ppb

level.

The method to be used for the relative measurement of different concentrations of H2O2 involves the use of

the tunable diode laser absorption system (TDLAS): hydrogen peroxide generated by one of the appropriate

techniques described above will be diluted with dry nitrogen and passed through a White cell at a reasonable

flow rate keeping the White cell at a total pressure of about 1 0 torr. A strong absorption line from the strongest

infrared band ve at 1265 cm'^ will be used to monitor the H2O2 concentration. Second derivative

spectroscopy will be employed in conjunction with sweep averaging to use the most sensitive detection

available. The minimum detection when using this method is usually sub-parts-per-billion by volume If reasonably strong absorption lines (1-10 atom'Vm'^) are used.

An independent measure of the concentration of H2O2 can be performed in the following way. A sample of

high concentration hydrogen peroxide In water will be passed through a short cell at known pressures. Lines

of both H2O2 and H2O will be measured using TDLAS. The partial pressure of H2O will be determined and

the line strength of the H2O2 calculated as follows: three series of 10000 averaged scans of a particular

ro-vibration line of both H2O and H2O2 will be taken and stored on the micro-computer system. Also, high

concentration hydrogen peroxide or pure water will be put in the 1 00% absorption cell, and their spectra will be recorded to be used in the final analysis. All cells will be pumped out until no absorption is present and

the 100% transmission spectrum will be recorded to be used in the final analysis. The data files will then be

processed in a computer program which will fit the H2O2 line to the Voigt line profile fitting program by using

the calculated H2O2 concentration. Using these accurate line strengths, unknown H2O2 concentrations can

be measured independently of any other calibration techniques.

26. Development and Evaluation of a New Preparation Technique for Producing High Accuracy

Carbon Dioxide in Air Gravimetric Standards

R.C. Myers and G.A. Sieater

The atmospheric CO2 measurement community has emphasized the need to achieve an absolute uncertainty

of CO2 in air standards of less than 0.4 ppm at the 95 percent confidence level. A new blending procedure

for preparing high accuracy gravimetric primary standards has been developed in an attempt to evaluate the

feasibility of further reducing the total uncertainty levels of SRMs, currently at 0.8 ppm.

The two errors that contribute to the uncertainty associated with the preparation of gravimetric primary

standards are random errors and systematic errors or biases. These can be assessed to a high degree of

precision through the use of "state-of-the-art" NDIR instrumentation. The reproducibility of measurements

or precision of NDIR analyzers are numerically smaller than the total random error associated with preparing

a set of primary calibration standards. Thus, the total random error of an internal set or sets of primary

standards may be quantified by the deviation of predicted curve fit concentrations relative to the

concentrations of the standards assigned by gravimetry. In addition, small systematic errors can be

evaluated by the intercomparison of one set of primary standards to another.

One principal error which contributes to the total error in preparing gravimetric standards is the weighing of

the minor component, CO2. Previously, the reproducibility of the weighing measurements of the CO2 has

limited the uncertainty of primary standards to approximately ±0.3 ppm by mole at the 95 percent confidence

level. These primary standards were prepared using a single-step dilution method by weighing approximately

0.2 g of CO2 in a small cylinder on a semi-micro analytical balance.

154
A two-step dilution method was developed which allows a lower imprecision of CO2 weighing measurements.

In this method, a stainless steel cylinder having an approximate Internal volume of 0.1 5L and weight of 600

g was filled with approximately 6 g of pre-analyzed CO2. The cylinder was then weighed on a 0 to 1000 g

analytical balance having a sensitivity of 100 micrograms against a similar cylinder which served as a tare. A mixture of approximately 1 .5% CO2 was blended from this.

This process was then repeated using the 1.5% mixture In place of the CO2 reagent to produce several

primary standards ranging from 300-400 ppm by mole In concentration. Several ppm-levels of CO2 in air

primary standards have been prepared from four 1.5% mixtures which were prepared at various periods of

time over a nine-month period. Three different cylinders of reagent air were used In preparing the set of

standards.

The set of primary standards was evaluated for internal consistency and also intercompared with the primary

standards prepared using the single-step method. Predicted concentrations for each standard were

confirmed directly from their NDIR voltages using a quadratic regression over the range of the standards.

An average of the predicted concentrations from two NDIR analyses was calculated and compared to the

gravimetric concentration of each standard. The estimated coefficient of variance was calculated at the 95

percent confidence level to be less than ± 0.2 ppm for the two-step dilution standards. Concentrations were

predicted for the single-step dilution standards from the two-step dilution standards and the difference or systematic error was calculated to be 0.07 ppm. The two sets of primary standards are statistically

indistinguishable since their uncertainties overlap.

27. Measurements of Sulfur-Containing Gases (PCS and CS2) in Ambient Air

R.L. Sams

Tunable diode laser absorption spectrometry (TDLAS) is probably one of the most versatile methods in use

today for measuring trace atmospheric gases. This is especially true for the detection of the two

sulfur-containing gases OCS and CS2 which are well behaved and present no problem in detection and

measurement.

The mixing ratio of OCS in ambient air has been previously reported to be about 400-500 parts per trillion by

volume pptv; therefore, to adequately measure OCS in room air In real time, a very sensitive method has to

be used. Previous measurements have been made by using preconcentration and then gas chromatography

for the actual measurements. This is a slow (gathering samples) and uncertain (preconcentration factor)

method at best. TDLAS is a continuous, rapid (3 s time constant or less) and accurate method well suited

for measuring low concentrations of OCS encountered in the atmosphere. The strongest band for monitoring

OCS is vi at about 2060 cm*\ An appropriate line was selected, P(21), and investigated under second

derivative line-locked mode. The TDLAS was calibrated with an OCS permeation tube (20 ng/min) swept

with 1 L/min zero air (5.7 ppbv). If only a line-locked second derivative mode was used, the measurement

was subject to slow (minutes) background intensity fluctuations. This problem was overcome by adding a

small second modulation at about 100 kHz. This additional modulation reduced the background fluctuation

about two orders of magnitude to a more tenable size. Ambient air measured in this way was found to contain

about 640±33 ppt of OCS, somewhat higher than previously measured.

Carbon disulfide is expected to have a much lower mixing ratio than OCS in ambient air about 40 pptv. The

measurement of CS2 was accomplished using a second derivative sweep-averaging technique. In this

technique, the diode is modulated at about 1 1 kHz and also swept at 1 40 Hz. The detector signal is processed

through a high speed lock-in amplifier (time constant less than 30 ^is) and observed in the 2f mode. The

output of the lock-in amplifier is averaged with a signal averager and saved for additional data reduction. It

155
was found that a second modulation was helpful in reducing fringing effects with this technique. The addition

modulation was supplied at 100 kHz with only a small amplitude required. Initial measurements on the V3

band of CS2 leads to an ambient concentration of about 40±15 pptv. This large uncertainty is primarily due

to excessive fringing. The detector noise is a factor of 10 to 100 less (1.5-.15 pptv). Additional work must

be done on CS2 to calibrate the measurements (CS2 permeation tubes) and reduce the fringing noise to the

detector noise limit.

156
C. Outputs and Interactions

(Gas and Particulate Science Division

1. Publications

Bright, D.S. and Steel, E.B., "Automated Analysis of Regular Spot Patterns in Electron Diffraction Images,"

Journal of Microscopy. June 1988, (in press).

Bright, D.S., Newbury, D.E, and Marinenko, R.B., "Concentration-Concentration Histograms; Scatter

Diagrams Applied to Quantitative Compositional Maps," Microbeam Analysis (1988).

Bright, D.S., "Usefulness of Various Computer Algorithms for Locating Spots and Arrays in Electron

Diffraction Patterns," Microbeam Analysis (1988).

Cadoff, B.C., "Cryogenic Trapping of Organic Vapor Standards in the PPB to PPM Range: Applications to

Gas Chromatographic Calibration Over a 1 00-Fold Range," Analytical Chemistry (1 988), (in review).

Cadoff, B.C., "Kinetic Studies Using a Highly Sensitive Microphone Detector," W. Braun, Philippe Pagaut,

NBS Journal of Research (1988), (in press).

Chi, P.H.„ Simons, D.S, and Roitman, P., "Profiling Oxygen in SIMOX Material by Secondary Ion Mass

Spectrometry, " Microbeam Analysis-1988. San Francisco Press.

Christy, A.A., Tvedt, J.E., Karstang, T.V., and Velapoldi, R.A., "A Low Pressure, Automated, Sample Packing

Unit for Diffuse Reflectance Infrared Spectrometry," Review of Scientific Instruments (1988).

Currie, LA., Stafford, T.W., Sheffield, A.E., Klouda, G.A., Wise, S.A., Fletcher, R.A., Donahue, D., Jull, T.,

and LInick, T., "Microchemical and Molecular Dating," To be submitted to Radiocarbon (in review).

Currie, LA., "Control of Analytical Quality," lUPAC Working Group on Chemometrics (in review).

Currie, LA., Beebe, K.R., and Klouda, G.A., "What Should We Measure?" Presented at the 1988 EPA/APCA

Symposium on Measurement of Toxic and Related Air Pollutants, May 2-4, 1988, Raleigh, NC, To

be published In Proceedings of the 1988 EPA/APCA Symposium on Measurement of Toxic and

Related Air Pollutants (In press).

Currie, LA., Fletcher, R.A., and Klouda, G.A., "On the Identification of Carbonaceous Aerosols via ^^C

Accelerator Mass Spectrometry, and Laser Microprobe Mass Spectrometry," Nuclear Instruments

and Methods in Physics Research B29. 346 (1987).

Currie, LA., "Recommendation for Nomenclature in Evaluation of Analytical Methods," lUPAC Comm. V3. (WERB approved. May 1988).

Currie, LA., "Chemometrics and Standards," Journal of Research of the National Bureau of Standards. 93,

193 (May/June 1988).

157
Currie, LA., "Detection: Overview of Historical, Societal and Technical Issues," Ch. 1 in LA. Currie, Ed.,

Detection in Analytical Chemistry: Importance. Theory, and Practice. ACS Symposium Ser. 361

,

American Chemical Society (1988).

Currie, LA. and Parr, R.M., "Perspectives on Detection Limits for Nuclear Measurements in Selected

National and International Programs," Ch. 9 in LA. Currie, Ed., Detection in Analytical Chemistry: Importance. Theory, and Practice. ACS Sympos. Ser. 361, American Chemical Society (1988).

Currie, L.A., Fletcher, R.A., and Klouda, G.A., "Source Apportionment of Individual Carbonaceous Particles

Using ^'^C and Laser Microprobe Mass Spectrometry," Aerosol Science and Technology (in press).

Dennis, J.R. and McMurdie, H.F., "Phase Diagrams for Ceramists," Vol. VI. Roth, R.S., Ed., The American

Ceramic Society, Inc. (1987).

Dorko, W.D. and Cai, Z-t., "Characterization of a Low Concentration Level Acid Gas Calibration System:

Sulfur Dioxide in Air from 100 to 1 ppb," (in review) To be published in proceedings of ASTM

Conference held in July 1987.

Etz, E.S., Wong-Ng, W., Blendell, J.E., and Chiang, C.K., "Micro-Raman Spectroscopy of High-Tc

Superconductors In the Y-Ba-Cu-0 System," Microbeam Analysis - 1988. D.E. Newbury, Ed., San

Francisco Press (August 1988).

Etz, E.S., Robins, L.H., Farabough, E.N., and Feldman, A., "Raman Microprobe Spectroscopy in the

Characterization of Diamond-Like Films Grown by Chemical Vapor Deposition," Proceedings of the

SPIE’s 32nd Annual International Technical Symposium on Optical and Optoelectronic Applied

Science & Engineering. Symposium on Diamond Optics, San Diego, CA (1988).

Fehsenfeld, F.C., Dickerson, R.R., Huebler, G., Luke, W.T., Nunnermacker, L.J., Williams, E.J., Roberts,

J.M., Calvert, J.G., Curran, C.M., Delany, A.C., Eubanck, C.S., Fahey, D.W., Fried, A., Gandrud,

B.W., Langford, A.O., Murphy, P.C., Norton, R.B., Pickering, K.E., and Ridley, B.A., "A Ground-Based

Intercomparison of NO, NOx, and NOy Measurement Techniques," Journal of Geophysical

Research (1987).

Feldman, A., Farabough, E.N., Sun, Y.N., and Etz, E.S., "Diamond, A Potentially New Optical Coating

Material," Laser-Induced Damage in Optical Materials: 1987. Society of Photo-Optical

Instrumentation Engineers.

Fletcher, R.A. and Currie, LA., "Pattern Differences in Laser Microprobe Mass Spectra of Negative Ion

Carbon Cluster," Microbeam Analysis. San Francisco Press (1988).

Fletcher, R.A., "A New Way to Mount Particulate Material for Analysis by the Laser microprobe Mass

Analyzer," Analytical Chemistry (in press).

Fried, A. and Sams, R.L, "Tunable Diode Laser Absorption Spectrometry for Ultra-Trace Measurement

and Calibration of Atmospheric Constituents," ASTM STP 957. J.K. Taylor, Ed., American Society

for Testing and Materials (1987).

158
Fried, A., Nunnermacker, L.J., Cadoff, B.C., Sams, R.L, and Yates, N., "Reference NO2 Calibration System

for Ground-Based Intercomparisons During NASA’s GTE-CITE II Mission," Submitted to Journal of

Geophysical Research (1988).

Fried, A., Sams, R.L, Dorko, W.D., Elkins, J.W., Cai, Z-t., "Determination of Nitrogen Dioxide-In-Air

Compressed Gas Mixtures by Quantitative Tunable Diode Laser Absorption Spectrometry and

Chemiluminescence Detection," Analytical Chemistry (1988).

Hertz, H.S., et al., [CAC - Quality Assurance Task Force: R. Christensen, L. Currie, W. Dorko, R. Durst, H.

Hertz, J. Moody, R. Schaffer, G. Sleater, E. Steele, J. Taylor, R. Velapoldi, R. Zeisler], Quality

Assurance Handbook - Center for Analytical Chemistry. NBS (1988).

Kaushik, V.S., Datye, A.K., Kendall, D.L, Martinez-Tovar, B., Simons, D.S., and Myers, D.R., "Formation of

Silicon Nitride in (110) Silicon." Journal Materials Research. Submitted.

Klouda, G.A., Currie, LA., Verkouteren, R.M., Einfeld, W., and Zak, B.D., "Advances In Microradiocarbon

Dating and the Direct Tracing of Environmental Carbon," Journal of Radioanalytical and Nuclear

Chemistry. 123 (1988).

Klouda, G.A., Currie, LA., Sheffield, A.E., Diamondstone, B.I., Benner, B.A., Wise, S.A., Stevens, R.K., and

Merrill, R.G., "^"^C Source Apportionment Technique Applied to Wintertime Urban Aerosols and

Gases for the Integrated Air Cancer Project," Presented before the Division of Environmental

Chemistry, American Chemical Society, Toronto, Canada, June 5-1 1 1988, To be published by Lewis

Publishers (1988), (in press).

Klouda, G.A., Currie, LA., Donahue, D.J., Jull, A.J.T., Artaxo, P., Einfeld, W., Winchester, J.W., Sams, R.L,

Verkouteren, R.M, and LInick, T.W., "Urban Contributions to Atmospheric Methane and Carbon

Monoxide through Radiocarbon Measurements," To be submitted to Radiocarbon (In review).

Marinenko, R.B., Newbury, D.E., Bright, D.S, Mykiebust, R.L, and Blendell, J.E., "Application of Wavelength

Dispersive Compositional Mapping to High-Temperature Superconductors," Microbeam Analysis. San Francisco Press (1988).

Musselman, I.H., Simons, D.S., and Linton, R.W., "Effects of Sample Geometry on Interelement

Quantitation in Laser Microprobe Mass Spectrometry," Microbeam Analysis. San Francisco Press

(1988).

Newbury, D.E., "Elemental and Molecular Microanalysis in the Sub-micrometer Spatial Domain," Molecular

Electronic Devices II. F.L Carter, Ed., (Marcel Dekker, New York, 1987).

Newbury, D.E., "Surface Imaging by Secondary Ion Microscopy," Analytical Electron Microscopy. San

Francisco Press (1987).

Newbury, D.E. and Bright, D.S., "Compositional Mapping with a TV Camera-Based Imaging System on an

Ion Microscope," Microbeam Analysis. San Francisco Press (1988).

Newbury, D.E. and Mykiebust, R.L, "Performance of a ’Conventional’ Monte Carlo Program at Low Beam

Energy," Microbeam Analysis. San Francisco Press (1988).

159
Nunnermacker, L.J., Dickerson, R.R., Fried, A., and Sams, R.L, "A New Gas Phase Nitric Acid Calibration

System," Accepted by Environmental Science and Technology (1988).

Pella, P.A. and Dobbyn, R.C., 'Total Reflection Energy-Dispersive X-ray Fluorescence Spectrometry Using

Monochromatic Synchrotron Radiation: Application to Selenium in Blood Serum," Analytical

Chemistry (1988).

Pickering, K.E., Dickerson, R.R., Huffman, G.J., Luke, W.T., and Nunnermacker, L.J., "Clear Sky Vertical

Profiles of Trace Gases as Influenced by Upstream Convective Activity," Submitted to Journal of

Geophysical Research (1988).

Rhoderick, G.C. and Zielinski, W.L, Jr., "Development of Multicomponent ppb-Level Gas Standards of

Volatile Toxic Organic Compounds," For publication in ASTM STP Book: Recent Developments in Monitoring Methods for Toxics in the Atmosphere (1988).

Rhoderick, G.C. and Zielinski, W.L, Jr., "Preparation of Accurate Multicomponent Gas Standards of Volatile

Toxic Organic Compounds In the Low Part-Per-Billion Range," Analytical Chemistry. To be

published in November 1988, (in press).

Rouse, R.C., Peacor, D.R., Dunn P.J., Campbell, T.J., Roberts, W.L, Wicks, F.J., and Newbury, D.E.,

"Pahasapatite, a Beryllophosphate Zeolite Related to Synthetic Zeolite Rho, from the Tip Top

Pegmatite of South Dakota," Neues Jahrbach fur Mineralogie Hi (1 987)

.

Sams, R.L. and Lafferty, W.J., "The High Resolution Spectrum of the 1 + 2 Band of NO2 A Spin Induced

Perturbation in the Ground State," Journal of Molecular Spectroscopy (1987).

Sams, R.L. and Fried, A., "Spin Splittings in the 3 Band of NO2

," Journal of Molecular Spectroscopy (1 987).

Sams, R.L. and Fried, A., "Microphone Triggering Circuit for Elimination of Mechanically-Induced

Frequency-Jitter in Diode Laser Spectrometers: Implication for Quantitative Analysis," Applied

Optics (1987).

Sams, R.L. and DeVoe, J.R., "Diode Laser Measurement of the 3 Band of ^^C02," Journal of Molecular

Spectroscopy (1988).

Schenk, P.K. and Dennis, J.R., "PC-Access to Ceramic Phase Diagrams, " ASTM Committee E-49. 1 st international Symposium on Computerization and Networking of Materials Property Databases, (in

press).

Sheffield, A.E., Gordon, G.E., Currie, LA., Klouda, G.A., and Benner, B.A., "Radiocarbon Measurement

and Source Apportionment," Presented at the 1988 EPA/APCA Symposium on Measurement of

Toxic and Related Air Pollutants, May 2-4 (1988), Raleigh, NC, Proceedings of the 1988 EPA/APCA

Symposium on Measurement of Toxic and Related Air Pollutants.

Sheffield, A.E., Currie, LA., and Klouda G.A., 'Trace Radiocarbon Analysis of Environmental Samples,"

Journal of Research of the National Bureau of Standards. 93 289 (May/June 1988).

160
Simons, D.S., Chi, P.H.„ Downing, R.G., Ehrstein, J.R., and Knudsen, J.F., "Progress Toward a Semiconductor Depth-Profiiing Standard," Secondary ion Mass Spectrometry SIMS Vi . John Wiley

and Sons, London (1988).

Simons, D.S. and Chi, P.H.„ "Ion Implantation Artifacts Detected by Secondary Ion Mass Spectrometry,"

Microbeam Analysis. San Francisco Press (1988).

Small, J.A., Newbury, D.E., and Mykiebust, R.L, "X-Ray Bremsstrahlung Intensities from Elemental

Targets," NBS Technical Note 1245. (February 1988).

Small, J.A., Newbury, D.E., Mykiebust, R.L, Fiori, C.E., Bell, A.A., and Heinrich, K.F.J., "An Electron/X-Ray

Optical Bench for the Measurement of Fundamental Parameters for Electron Probe Microanalysis,"

Microbeam Analysis. San Francisco Press (1988).

Stafford, T.W., "Accelerator ^^C Dating of Late Pleistocene Megafauna," Current Research in the

Pleistocene. Submitted.

Stafford, T.W., "Accelerator Radiocarbon Dating of Fossil-Bone Amino Acids: Accuracy of North American

Human Skeleton Ages," To be submitted to Science.

Steel, E.B., "SEM Imaging and Analysis of Submicrometer Particles in Air and Water Samples," Microbeam

Analysis. San Francisco Press, (1988).

Stevens, R.K., Lewis, C.W., Dzubay, T.G., Baumgardner, R.E., Zweidinger, R.B., Highsmith, V.R., Cupitt,

L.T., Lewtas, J., Claxton, L.D., Currie, LA., Klouda, G.A., and Zak, B., "Mutagenic Atmospheric

Aerosol Sources Apportioned by Receptor Modeling," Proceedings of the ASTM Boulder

Conference (1987), (in press).

Stevie, F.A., Kahora, P.M., Simons, D.S., and Chi, P.H., "Secondary Ion Yield Changes in SI and GaAs Due

to Topography Changes During O2

''’ or As"'' Ion Bombardment," Journal of Vacuum Science

Technology A6. No. 1 (1988).

Turner, S. and Post, J.E., "Refinement of the Subcell and Supercell of Romanechite", American

Mineralogist, (in press).

Velapoldl, R.A., Tvedt, J.E., and Christy, A.A., "Sample Rotation in Diffuse Reflectance Fourier Transform

Infrared Spectroscopy," Review of Scientific Instruments (1987).

Velapoldi, R.A. and Epstein, M.S., "Luminescence Standards for Macro- and Microspectrofluorimetry,"

Submitted as chapter in ACS Symposium Series (1988).

VelapoidI, R.A. and Durst, R.A., "Accuracy in Trace Analysis," TRAC (1988).

Verkouteren, R.M., Currie, LA., Klouda, G.A., Donahue, D.J., Jull A.J.T., and LinickT.W., "Preparation of

Microgram Samples on Iron Wool for Radiocarbon Analysis via Accelerator Mass Spectrometry: A

Closed-System Approach." Nuclear Instrum. & Methods in Physics Research B29. 41 (1987).

Vrebos, B.A.R. and Pella, P.A., "Uncertainties in Mass Absorption Coefficients in Fundamental Parameter

X-Ray Fluorescence Analysis," X-Ray Spectrometry. Vol. 17 (1988) (John Wiley & Sons, Ltd.).

161
Williams, D.B., Levi-Setti, R., Chabala, J.M., and Newbury, D.E., "High Spatial Resolution Secondary Ion

Imaging and Secondary Ion Mass Spectrometry of Aluminum-Lithium Alloys," Journal of

Microscopy. V. 148 (1988).

Zielinski, W.L, Jr., Hughes, E.E., Dorko, W.D., Rhoderick, G.C., and Myers, R.C., "Accuracy in Gaseous

Standard Reference Materials," Proceedings, International Symposium on Trace Analysis in Environmental Samples and Standard Reference Materials (1988), (in press).

2. Talks

Bright, D.S., "Computer-Aided Imaging Techniques for Electron Microprobe Analysis" Spectroscopy

Society of Pittsburgh Continuing Education Seminar on Spectroscopic Techniques for Surface

Characterization, Duquesne University, Pittsburgh, PA, February 8, 1 988.

Bright, D.S., "Digital Image Processing for Electron and Ion Beam Microanalysis" New England Combined

Chapter of the American Vacuum Society, Bedford, MA, May 1 1

, 1988.

Bright, D.S., "Image Processing and Analysis Techniques Applied to Microscope and Microprobe Images

of Particles," West Coast Microbeam Analysis Society Symposium, Syntex Research, Palo Alto, CA,

May 1988.

Bright, D.S., "Usefulness of Various Computer Algorithms for Locating Spots and Arrays in Electron

Diffraction Patterns" Joint Meeting of the Electron Microscopy Society of America, the Microbeam

Analysis Society and the Microscopical Society of Canada, Milwaukee, Wl, August 7, 1988.

Bright, D.S., "Concentration-Concentration Histograms: Scatter Diagrams Applied to Quantitative

Compositional Maps," Joint Meeting of the Electron Microscopy Society of America, the Microbeam

Analysis Society and the Microscopical Society of Canada, Milwaukee, Wl, August 7, 1988.

Chi, P.H., "Artifacts Observed in Oxygen Profiles of SIMOX Samples by Secondary Ion Mass

Spectrometry," Microbeam Analysis Society, Milwaukee, Wl, August 9, 1988.

Currie, LA., "Detection in Analytical Chemistry," Statistical Engineering Seminar, NBS, Gaithersburg, MD,

November 10, 1987.

Currie, LA., "Sample Selection Strategies for Elemental Tracer Model Validation via ^"^C Measurement,"

EPA Research Triangle Park, December 16, 1987.

Currie, LA., "Detection, Identification, and Validation in Analytical Chemistry: Some Case Studies,"

Analytical Sciences, Dow Chemical, Midland, Ml, February 17, 1988.

Currie, LA., Beebe, K.R., and Klouda, G.A., "What Should We Measure? Aerosol Data, Past and Future,"

Presented at the 1988 EPA/APCA Symposium on Measurement of Toxic and Related Air Pollutants,

Raleigh, NC, May 1988.

162
Currie, LA., and the Investigation of Sources of Fossil and Contemporary Carbonaceous Pollution,"

V.M. Goldschmidt Conference, Hunt Valley, MD, May 13, 1988.

Currie, LA., Stafford, T.W., Sheffield, A.E., Klouda, G.A., Wise, S.A., Fletcher, R.A., Donahue, D., Jull, A.J.T.,

Linick, T.W., "Microchemical and Molecular Dating," 13th International Radiocarbon Conference,

Dubrovnik, Yugoslavia, June 20-25, 1988.

Currie, LA., "Chemical Design Decisions; When Measurement Costs Exceed Sampling Costs,"

Chemometrics Lab., Eastman Kodak, Co., Rochester, NY, July 28, 1988.

Currie, LA., "Detection in Radiobioassay: Concepts and Nomenclature," Environmental and Safety

Division, Martin Marietta Energy Systems, Inc., Oak Ridge National Laboratory, Oak Ridge, TN,

August 5, 1 988.

Dorko, W.D., "Preparation and Verification of Gas Standards at Low Concentration Levels," Invited

Continuing Education Seminar Series, Union Carbide Technical Center, Charlestown, WV,

November 1987.

Dorko, W.D., "Gas Standards: NBS and the Specialty Gas Industry," Annual Quality Assurance Meeting

of the Specialty Gas Division of MG Industries, December 1987. Invited

Dorko, W.D., 'The NBS Atmospheric CO2 Standards; Current Status," NOAA/GMCC Annual Meeting, Hilo,

Hawaii, March 29, 1988.

Dorko, W.D., "Proposed Method for Intercorrelating NBS Atmospheric CO2 Standards with those from the

WMO/CCL," Workshop on the Statistical Evaluation of CO2 Data, Hilo, Hawaii, March 25, 1988.

Etz, E.S., "Materials Characterization by Raman Microprobe Spectroscopy," Washington, DC, October 23,

1987.

Etz, E.S., "Materials Characterization by Micro-Raman Spectroscopy," Department Colloquium,

Department of Chemistry, Howard University, Washington, DC, October 23, 1987.

Etz, E.S., 'The Past, Present, and Future of Raman Microprobe Analysis," Department Colloquium,

Department of Chemical Engineering, University of Maryland, College Park, MD, Novembers, 1987.

Etz, E.S., "Raman Microprobe Characterization of Diamond Films," Third Annual SDIO/IST - ONR Diamond

Technology Initiative Symposium, Sheraton Crystal City Hotel, Crystal City, VA, July 12, 1988.

Etz, E.S., 'The Application of Raman Microprobe Spectroscopy in Studies of Superconductor Materials,"

Third NBS Superconductivity Program Review, NBS-Boulder, Boulder, CO, July 14, 1988.

Etz, E.S., "Micro-Raman Spectroscopy of High-Tc Superconductors in the Y-Ba-Cu-0 System," 1988 Joint

Meeting of the Electron Microscopy Society of America and the Microbeam Analysis Society,

Milwaukee, Wl, August 9, 1988.

Etz, E.S., "Raman Microprobe Spectroscopy in the Characterization of Diamond-Like Films Grown by

Chemical Vapor Deposition," Symposium on Diamond Optics, SPIE’s 32nd Annual International

163
Technical Symposium on Optical and Optoelectronic Applied Science & Engineering, San Diego,

CA, August 16, 1988.

Etz, E.S., "Observation of Sharp Resonances in the Spectra of Spherical Microparticles Examined in the

Raman Microprobe," Xlth International Conference on Raman Spectroscopy (ICORS-XI), Institute

of Education, London, England, September 8, 1988.

Etz, E.S., "Research in Raman Microprobe Spectroscopy at the National Bureau of Standards," Laboratoire

de Spectrochimie Infrarouge et Raman, C.N.R.S., Universite des Sciences et Techniques de Lille Randres Artois, Lille, France, September 13, 1988.

Fletcher, R.A., "Microprobe Techniques with Emphasis on Laser Microprobe and Raman Microprobe"

Department of Chemical and Nuclear Engineering, University of Maryland, College Park, MD,

November 5, 1 987.

Fletcher, R.A., "An Investigation into Aerosol Sampling of Asbestos Fibers," ASTM D-22 Conference,

Johnson, VT, July 12, 1988.

Fletcher, R.A. and Currie, LA., "Pattern Differences in Laser Microprobe Mass Spectra of Negative Ion

Carbon Clusters," Microbeam Analysis Society, 1988, Milwaukee, Wl, August 10, 1988.

Heinrich, K.F.J., "Quantitative Microanalysis by X-ray Spectrometry; Models and Parameters,"

Czechoslovak Spectroscopic Society, Budejovice, June 20,1988.

Heinrich, K.F.J., "Preparation of Spectrochemical and Microanalytical Standards" Czechoslovak

Spectroscopic Society, Budejovice, June 21, 1988.

Heinrich, K.F.J., "Calculation of the Depth Distribution of X-ray Generation by the Monte Carlo Technique,"

1988 Joint Meeting of the Electron Microscopy Society of America and the Microbeam Analysis

Society , Milwaukee, Wl, August 9,1988.

Heinrich, K.F.J., "Quantitative Electron Probe Microanalysis: Parameters, Error Propagation, and

Operating Conditions," NBS Workshop on Quantitative Electron Probe Microanalysis, August 16,

1988.

Klouda, G.A., Currie, LA., Fletcher, R.A., Verkouteren, R.M., Donahue, D.J, Jull, A.J.T., Linick, T.W.,

Stevens, R.K., Lewis, C., Merrill, R.G., Novakov, T., Dod, R., "Carbon-14 in Atmospheric Particles:

Measurement Advances and Urban Applications," Third International Conference on Carbonaceous

Particles in the Atmosphere, Lawrence Berkeley Laboratory, October 5-8, 1987.

Klouda, G.A., Currie, LA., Sheffield, A.E., Diamondstone, B.I., Benner, B.A., Wise, S.A., Stevens, R.K., and

Merrill, R.G., "^^C Source Apportionment Technique Applied to Wintertime Urban Aerosols and

Gases for the Integrated Air Cancer Project," Presented before the Division of Environmental

Chemistry, American Chemical Society, Toronto, Canada, June 5-11, 1988.

164
Klouda, G.A., Currie, LA., Donahue, D.J., Jull, A.J.T., Artaxo, P., Einfeld, W., Winchester, J.W., Sams, R.L„

Verkouteren, R.M., and Linick, T.W., "Urban Contributions to Atmospheric Methane and Carbon

Monoxide through Radiocarbon Measurement," 13th International Radiocarbon Conference,

Dubrovnik, Yugoslavia, June 20-25, 1988.

Marinenko, R.B., "Application of Wavelength-Dispersive Compositional Mapping to High-Temperature

Superconductors," Joint Meeting of the Electron Microscopy Society of America, the Microbeam

Analysis Society and the Microscopical Society of Canada, Milwaukee, Wl, August 9, 1988.

Mitchell, G.D. and Bell, A.A., "Precise Coulometric Determination of Sulfur Dioxide in Nitrogen at the

Part-Per-Million Level in Standard Gas Mixtures," Pittsburgh Conference, New Orleans, LA, March

1988.

Mykiebust, R.L, "Microanalysis Programs for Personal Computers," Microbeam Analysis Society

Workshop on Personal Computers in the Microprobe Lab, Milwaukee, Wl, August 9, 1988.

Mykiebust, R.L., "A Redetermination of X-ray Loss Due to Electron Backscatter by Monte Carlo Simulation,"

Annual Conference of the Microbeam Analysis Society, Milwaukee, Wl, August 10, 1988.

Mykiebust, R.L "X-ray Loss Due to Electron Backscatter in Electron Probe Microanalysis," NBS Workshop

on Quantitative Electron Probe Microanalysis, August 16, 1988.

Newbury, D.E., "Quantitative Isotopic and Elemental Ratio Measurements with a Camera-Based Digital

Imaging System on an Ion Microscope," International Conference on Secondary Ion Mass

Spectrometry - SIMS 6, Versailles, France, September 15, 1987.

Newbury, D.E., "Compositional Mapping: the New Electron Probe Analysis", Dept, of Metallurgy and

Science of Materials, the University of Qxford, Qxford, England, September 24, 1987.

Newbury, D.E., "Quantitative Compositional Mapping on a Micrometer Scale," Symposium on Accuracy

in Trace Analysis - Accomplishments, Goals, Challenges, NBS, October 1 , 1987.

Newbury, D.E., "Image Formation and Interpretation in the Scanning Electron Microscope," Materials

Research Society, Boston, MA, December 2, 1987.

Newbury, D.E., "An Overview of X-ray Microanalysis," Materials Research Society, Boston, MA, December

2, 1987.

Newbury, D.E., "Compositional Mapping for the Characterization of the Microstructures of High

Temperature Superconductors," NBS Superconductivity Program Review, Gaithersburg, MD,

December 7, 1987.

Newbury, D.E., "Compositional Mapping with the Electron Microprobe," Department of Geophysical

Sciences, California Institute of Technology, Pasadena, CA, January 29, 1988.

Newbury, D.E., "New Developments in Compositional Mapping," Solid State Physics Discussion Group,

NBS, Gaithersburg, MD, May 9, 1988.

165
Newbury, D.E., "New Developments in Compositional Mapping of High Tc Superconductors," NBS

Superconductivity Program Review, Boulder, CO, July 14,1988.

Newbury, D.E., "Performance of a ’Conventional’ Monte Carlo Program at Low Beam Energy," Annual

Conference of the Microbeam Analysis Society and the Electron Microscopy Society of America,

Milwaukee, Wl, August 9, 1988.

Newbury, D.E., "Quantitative Compositional Mapping by Electron Probe Microanalysis,"NBS Workshop

on Quantitative Electron Probe Microanalysis, August 16, 1988.

Newbury, D.E., "Quantitative Compositional Mapping with the Electron Microprobe," Midwest Society of

Electron Microscopist, Department of Physics, University of Wisconsin-Milwaukee, March 25, 1988.

Rhoderick, G.C., "Development of Eighteen Component Toxic Qrganic Gas Standards at the Low ppb

Level," Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, New Qrleans,

LA, February 1 988.

Rhoderick, G.C., "Standards for the Measurement of Halocarbons In the Atmosphere in the ppb Range,"

NQAA Geophysical Monitoring for Climatic Change, Annual Meeting, Hilo, Hawaii, March 1988.

Rhoderick, G.C., "Development of Eighteen Component Toxic Qrganic Gas Standards at the Low ppb

Level," Joint EPA/APCA Conference, Research Triangle Park, NC, May 1988.

Sams, R.L, 'The Detection of QCS in the Parts-Per-Trilllon Range Using Tunable Diode Laser

Spectroscopy," 30th Rocky Mountain Conference, Denver, CQ, August 1988.

Sheffield, A.E., Gordon, G.E., Currie, LA., Klouda, G.A., and Benner, B.A., "Radiocarbon Measurement

and Source Apportionment," Presented at the 1988 EPA/APCA Symposium on Measurement of

Toxic and Related Air Pollutants, Raleigh, NC, May 1988.

Silver, D.G. and Mitchell, G.D., "A Computer-Controlled Coulometric Titration System," Pittsburgh

Conference, New Qrleans, LA, March 1988.

Simons, D.S., "An Ion-Implanted Depth-Profiling Standard for SIMS: Progress and Pitfalls," Materials

Engineering Department, North Carolina State University, Raleigh, NC, January 12, 1988.

Simons, D.S., "Ion Implantation Artifacts Detected by Secondary Ion Mass Spectrometry," Microbeam

Analysis Society, Milwaukee, Wl, August 9, 1988.

Small, J.A., "AEM/LAMMA Analysis of Interplanetary Dust Particles," Winter Meeting of the California

Chapter of the Microbeam Analysis Society, California Institute of Technology, Pasadena, CA,

January 1988.

Small, J.A., 'The Visibility of Asbestos Fibers in the Scanning Electron Microscope," ASTM Johnson

Conference, Johnson, VT July 1988.

166
Small, J.A., "An Electron/X-ray Optical Bench for the Measurement of Fundamental Parameters for Electron

Probe Microanalysis," 23rd Annual Meeting of the Microbeam Analysis Society Milwaukee, Wl,

August 1988.

Small, J.A., 'The Chi Machine: An Old Idea Revisited," NBS Symposium on Electron Probe Ouantitative

Analysis, Gaithersburg, MD, August 1988.

Small, J.A., "Sample Preparation for Microanalysis," 23rd Annual Meeting of the Microbeam Analysis

Society, Milwaukee, Wl, August 1988.

Stafford, T.W., "Micromolecular Dating of Ancient Bones," 553 Seminar, NBS, Gaithersburg, November

30, 1987.

Steel, E.B., "Scanning Electron Microscopy: Analysis of Air Samples," National Asbestos Council Annual

Meeting, Atlanta, GA, February 1988.

Steel, E.B., "ASTM Standards for the Analysis of Asbestos," National Asbestos Council Annual Meeting,

Atlanta, GA, February 1988.

Steel, E.B., "Ouality Assurance Issues Associated with Asbestos Analysis," CA/OC Short Course

Sponsored by the National Asbestos Council, Atlanta, GA, February, 1988.

Steel, E.B., "New Developments in Analytical Electron Microscopy" Chemical Engineering Department

Seminar, University of Maryland, MD, March 1988.

Steel, E.B., "Developments In Asbestos Analysis by Scanning Electron Microscopy," ASTM Johnson

Conference on Sampling and Analysis of Atmospheres, Johnson, VT, July 14, 1988.

Steel, E.B., "SEM Imaging and Analysis of Submicrometer Particles in Air and Water Samples," Microbeam

Analysis Society, Milwaukee, Wl, August 1988.

Turner, S., "Use of High-Resolution TEM and Electron Diffraction to Study Fine-Grained Materials,"

American Crystallographic Association, Philadelphia, PA, May 1988.

Turner, S., 'The Application of Quality Assurance to TEM Asbestos Analysis," ASTM Asbestos,

Measurement Research and Laboratory Accreditation Conference, Johnson, VT, July 14, 1988.

Velapoldi, R.A., 'The Determination of the Geologic Maturation Process Using Diffuse Reflectance Infrared

Fourier Transform Spectroscopy", Pittsburgh Conference, Poster Session, New Orleans, LA,

February 1988.

Velapoldi, R.A., "Quality Assurance in Chemical Measurements," Quality Seminar Expo 88, Metrology

Session, American Society for Quality Control, Oklahoma City, OK, March 2-3, 1988.

Velapoldi, R.A., 'The Center for Analytical Chemistry and QA from Several Perspectives", IBM Analytical

Laboratory Managers Annual Meeting, Mannassas, VA, April 1 988.

167
Verkouteren, J.R., "PC-Access to Ceramic Phase Diagrams," ASTM Committee E-49, 1st International

Symposium on Computerization and Networking of Materials Property Databases, November 1987.

Verkouteren, M.R., "Development of Isotope Dilution Mass Spectrometry for the Absolute Determination

of Carbon Dioxide Abundance in Air," CAC Colloquium Series, June 13, 1988.

Zielinski, W.L, Jr., Hughes, E.E., Dorko, W.D., Rhoderick, G.C., and Myer, R.C., "Accuracy in Gaseous

Standard Reference Materials," International Symposium on Trace Analysis in Environmental

Samples and Standard Reference Materials, Honolulu, Hawaii, January 1988. Invited paper

Zielinski, W.L, Jr. and Rhoderick, G.C., "Cryogenic Preconcentration and GC-MS Analysis of

Multicomponent Gas Standards of Volatile Toxic Organic Compounds at the Low ppb Level,"

Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, New Orleans, February

1988.

Zielinski, W.L, Jr. and Rhoderick, G.C., "Assessment of Stability in Multicomponent Standards of Volatile

Toxic Organic Compounds in the ppb Range," Symposium on Emissions from Combustion

Processes: Origin, Measurement, Control: Sampling/Analytical Methodologies, 3rd Chemical

Congress of North America, Toronto, Canada, June 1988. Invited paper

3. Committee Assignments

Ranee A. Velapoldi

Interagency Toxic Substances Data Committee

ASTM E-07 on Nondestructive Testing

ASTM E-1 1 on Statistical Methods

ASTM E-1 3 on Molecular Spectroscopy

ASTM E-1 3.06 on Molecular Luminescence

ASTM E-1 3.06.01 on Presentation of Corrected Fluorescence Spectra

ASTM E-1 3.06.02 on Recommended Practices on Molecular Fluorescence

Spectroscopy

Council for Optical Radiation Measurements (CORM)

Liaison (550), Council for Chemical Research (CCR)

Interagency Collaborative Group on Environmental Carcinogenesis

Arnold M. Bass

ASTM D-22 Sampling and Analysis of Atmospheres

ASTM D-22.01 Quality Assurance

ASTM D-22.03 Sampling and Analysis of Ambient Atmospheres

Ozone Science Guidance Committee, NESDZS

David S. Bright

ASTM E-29 Particle Size Measurement

ASTM E-29.04 Liquid Particle Measurement

Lloyd A. Currie

Radiocarbon Dating Quality Assurance Group

lUPAC Working Group on Chemometrics

CAC, Quality Assurance Task Force

168
Titular Member, lUPAC Commission on Analytical Nomenclature

Chairman, Consultant’s Group, International Atomic Energy Agency, on Limit of Dete

University of Maryland Thesis Committee (A.E. Sheffield)

Editorial Board, Journal of Chemometrics

Organizing Committee, Mathematics in Chemistry Conference

Advisory Panel, Southern Methodist Univ. Geochronology Lab.

Advisory Group, Radiation Monitoring Quality Assurance and Quality Control Program, Martin

Marietta Energy Systems ORNL

William D. Dorko

ASTM D-22 Sampling and Analysis of Atmospheres

Secretary, ASTM D-22.03 Sampling and Analysis of Ambient Atmospheres

NASA’s Science Team for the Global Tropospheric Experiment Cite-3 Mission

Edgar S. Etz

ASTM E-13 Molecular Spectroscopy

ASTM E-13.08 Raman Spectroscopy

Robert L. Myklebust

ASTM E-2 Emission Spectroscopy

ASTM E-2.04 Standard Reference Materials

Dale E. Newbury

ASTM E-42 Surface Analysis

Journal of Microscopy, Editorial Review Board

Scanning, Editorial Review Board

J. Trace and Microprobe Techniques, Editorial Review Board

Journal of Electron Microscopy Techniques, Editorial Review Board

Peter A. Pella

ASTM E-22 Emission Spectroscopy

ASTM E-22.06 Statistics, Calibration and Standardization

Gerald A. Sleater

ASTM D-22 Sampling and Analysis of Atmospheres

ASTM D-22 Source Sampling

Walter L. Zielinski, Jr. Interagency Committee on CQ2 and Climate

Interagency Committee for Stratospheric Qzone Protection

Interagency Committee for Indoor Air Quality

ASTM D-22 Sampling and Analysis of Atmospheres

Journai of Analytical Toxicology, Editorial Review Board

Editor, Critical Reviews in Analytical Chemistry

169
4. Other

a. Seminars

September 21, 1988

Dr. David Lowe, NCAR & DSIR, New Zealand, "Application of Accelerator Mass Spectrometry in Atmospheric Chemistry." (Division Sponsor: L Currie)

July 7, 1988

B. Davis, South Dakota School of Mines & Technology, "A New XRD Method for Quantitative

Analysis of Bulk Asbestos." (Division Sponsor: D. Johansen)

b. Conferences Sponsored

July 10-15, 1988

Harry L. Rook and Eric B. Steel, Johnson Conference.

July 19, 1988

P.A. Pella, Problems In the XRFS Analysis of Major and Trace Elements In Whole Coal.

December 15, 1987

W.L Zielinski and W.D. Dorko, Workshop on Toxic Organic Gas Mixtures and the CRM Program.

August 1988

Dale E. Newbury, Workshop on Quantitative Electron Probe Microanalysis.

c. SRM Certification

Microanalysis

SRM 2063, Microanalysis Thin Film Mg-Si-Ca-Fe

X-Ray

SRM 600, Australian Bauxite

SRM 2704, Buffalo River Sediment

SRM 1219, Stainless Steel

SRM 1250 and 868, High Temperature Alloys

SRM 1276a, Cu-Ni Alloy

SRMs 1884 & 1889, Cements

SRM 1129, Electronic Flowsolder Powder

SRM 1623b & 1624b, Sulfur In Fuel Oil

SRM 1834, Simulated Fused Clay Materials

SRM 489, Ferrite in Austenite

SRM 1296, Stainless Steel

SRM 1568a, Rice Flour

SRM 1567a, Wheat Flour

SRM 1566a, Oyster Tissue

SRM 1548, Total Diet

SRM 1515, Apple Leaves

SRM 1547, Peach Leaves

170
Gas Metrology

SRM 1625 10 cm SO2 Permeation Tubes

SRM 1626, 5 cm SO2 Permeation Tubes

SRM 1627, 2 cm SO2 Permeation Tubes

SRM 1629, NO2 Permeation Tubes

SRM 1693, 50 ppm SO2 in Nitrogen

SRM 1694, 100 ppm, SO2 in Nitrogen

SRM 1674, 7% CO2 in Nitrogen

SRM 1675, 14% CO2 in Nitrogen

SRM 1700, 10% CO2 in Nitrogen

SRM 1701, 5% CO2 and 12% O2 in Nitrogen

SRM 1702, 5% CO2 and 20% O2 in Nitrogen

SRM 1703, 10% CO2 and 7% O2 in Nitrogen

SRM 1685, 250 ppm NO in Nitrogen

SRM 1686, 500 ppm NO in Nitrogen

SRM 1687, 1000 ppm NO in Nitrogen

SRM 2725. 600 ppm C3H8 and 1 .6% CO in Nitrogen

SRM 2726, 3000 ppm C3H8 and 8% CO in Nitrogen

SRM 2727, 600 ppm C3H2, 1 .6% CO and 11% CO2 in Nitrogen

SRM 2728, 3000 ppm C3H8, 8% CO and 14% CO2 in Nitrogen

SRM 1681, 1000 ppm CO in Nitrogen

SRM 2640, 4% CO in Nitrogen

SRM 2641, 2% CO in Nitrogen

SRM 1665, 3 ppm C3H8 in Air

SRM 1666, 10 ppm C3H8 in Air

SRM 1667, 50 ppm C3H8 in Air

SRM 2730, 5 ppm H2S in Nitrogen

SRM 2731, 20 ppm H2S in Nitrogen

171
M

J K.

'

' *

\K' '

;'",Yv,' : ..'V;'

'u.. Mieia' •-’*‘ .)j 4

' \

" ‘ ''Mr.t^y

"bt-,

iv W

':’ •.'%gei«M:{«' Oi4:i<kH3'i^';^t la

“'•'»» (. 3i-j«5( 4r<* .frt:vR, ,©*«!: 'JM«0?\C‘&t'»fe)>S’!€®®60iiS^^

^4;. _

• iweos'H fS; sxi' mSf«

.5,

:' m^m

>Vf - . r'.-?-. -i.

'HM

Oila'f. ‘Jl.n

l:V •

'1

' •

' ;^> V.'i , ji'

,

> ^ ,

, ^k^'-yp \!^wM

A ' '- ''

,' ;' " '

'

'

,

' "'' V • >'':

'’

' - ''''.N-''.^':'

'

[ : . V

^

’ \ • :.!, >

~s..

imA ’ 2.UI

f, «#•:• •' ..j7'^-i<t-:*--iM ..W>*Hfi^t

' V , '; ,' '

,

' ''''^';V;>S''-''- ('

‘ . ‘f.‘ ”'<• V , ' VTMiU. "5

/1-

‘

4j< C^; , k-\' ku^yA::A"f'M

.llj , ’. I, / ;. : ; -v , ’’ j,

' " ,fl^./.; " '

' ''' ' '

>•'£«

M

‘^ '

' ^ ; ;4

' ' " '"''• ' -V' ,>:'

- kiy^if fj '<iMh,' ,:;A

:.-X.:

, ' 'Y"

'•

•• P\i

...j . ‘ i'A:
NBS-n4A <REV. 2-8C) U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET CSee instructions)

4. TITLE AND SUBTITLE

PUBLICATION OR

REPORT NO.

NISTIR 88-3875

2. Performing Organ. Report No. 3. Publication Date

NOVEMBER 1988

Technical Activities 1988, Center for Analytical Chemistry

5. AUTHOR(S)

B. I. Diamonds tone , R. A. Durst, and Harry S. Hertz

6. PERFORMING ORGANIZATION (If joint or other than MBS, see instructions) 7. Contract/Grant No.

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City, State, ZIP)

SAME AS ABOVE.

10.

SUPPLEMENTARY NOTES

I I Document describes a computer program; SF-185, FlPS Software Summary, is attached.

11.

ABSTRACTfA 200-word or less factual summary of most significant information. If document includes a si gnifi cant

bi bliography or literature survey, mention it here)

This report summarizes the technical activities of the Center for Analytical Chemistry

at the National Institute of Standards and Technology. It emphasizes activities over

the Fiscal Year 1988 in the Inorganic Analytical Research Division, the Organic

Analytical Research Division, and the Gas and Particulate Science Division. In

addition, it describes certain special activities in the Center including quality

assurance and voluntary standardization coordination.

12.

KEY WORDS (S/x to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Analytical chemistry; analytical services; gas and particulate science; inorganic

analytical chemistry; organic analytical chemistry; quality assurance.

13. AVAILABILITY 14. NO. OF

PRINTED PAGES

Uni imited

1 1 For Official Distribution. Do Not Release to NTIS 177

1 1 Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402. 15. Price

[j^ Order From National Technical Information Service (NTIS), Springfield, VA. 22161 $18.95

ttU.S. GOVERNMENT PRINTING OFFICE: 1989-228-045 USCOMM-DC 0043-P80
fv' 5^ c

!>^<«^iwy ii^^^|tl>

^tiii>i|

ii» 'I '•li tfiM

' fc'Sw

. V '^ •wMy« ,

. |M<»»y-.*.ltll»iatii < *

f|*

. - fete:

' ,..x

,'

,' ' )

i' ’j'

. ;' ‘

,«ri, .•'. «K--<> • *jM ,

' - • " - - -i'-r"

' L'’

' cl' ^:, c

'

' '"

-,^ -.^yjVyu

'fc

- ,

^

'

j;!;WtS

’ ^*<1—Hf-HU •*»» WY|{X»- '•—I"- ' « m>yr J «f^ nailuy %oi - «.•>*«. ' -fc-^fY/yw^i^fc rull ' lljl l « ‘

- ' ' ( ^ -

' c -'' -.ar/

' i.^'i ^10 It ^iri- fp '^'.a.T jf’j- titsMil^^^

r^y *. 3 3-f 9 V-/ -'y.OAj « Jstf. .. iQffls- .?]f . e jb-.-j c'i&

d

' *' •.,3^7''' fr'- T'csivi'^

n',X Virn.i rvd 5-'><7s LUi'A

^

- , . , ^ -._•, ,, flr- .' ,?*lJ'Vjrar.

>>^ i5 i «n I d'i 00 -i AO »

‘i

’ >j» '^';y

•

I 'V

•: -vv'i

''r’l ; 'jit

-

,

. I' ,:;’

''<f-o: • •' ',-diH

•' -Knowm Hw« t" !?•*»»?•<»/ '^

, ,, >• , ,' •-., <* « /; •..,' ... ®"".. .i.-;S£-t.,ii-.^

' ,.,' " ^

. » ; ' : >> ...,, ' ; w"'v' . :

'

' ^ .'>*Av ,.". 1^'!*''^

' i

• c-Ti' I J iS ti »f- j'?*.

'^k «<*•»• ’v — ' •A'iC »

!.. OziTKV^'^i :,

-\Ttt.d“r^-' -l'^.\,.\v'^ .i'^«*»'