REFERENCE

NBSIR 85-3272

NBS

PUBLICATIONS

echnical

Activities 1985

Genter for

Analytical

Chemistry

-QC

100

- U 5 6

85-3272

1985

November 1985

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

NBSIR 85-3272

NBS

RESEARCH

INFORMATION CENTER

Center for

Analytical

Chemistry

Richard A. Durst Harry S. Hertz John K. Taylor

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory Center for Analytical Chemistry

Gaithersburg, MD 20899

November 1985

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

National Bureau of Standards, Ernest Ambler Director

TABLE OF CONTENTS

Page

I. CENTER FOR ANALYTICAL CHEMISTRY

A. Center Overviews 1 B. Output and Interactions 13

C. Voluntary Standardization and Quality Assurance 19

1. Voluntary Standards 19

2. Quality Assurance 19

D. Service Analysis 21

II. INORGANIC ANALYTICAL RESEARCH DIVISION

A. Division Overviews 22

B. Selected Technical Reports 32

1. Three-Dimensional Atomic Sepectra in Flames Using

Stepwise Excitation Laser-Enhanced Ionization

Spectroscopy 32

2. Evaluation of Several Pulsed Dye Lasers as Excitation

Sources for Flame Atomic Fluorescence Spectrometry 33

3. Determination of Cr(VI) in Natural Waters by LC/AAS

after Separation and Preconcentration 34

4. Development of an SRM to Calibrate

Microspectrofluorimeters 35

5. Spectrometric Analysis of Spark-Generated Aerosols 35

6. Resonant Laser^-Induced Ionization of Atoms in an Inductively-Coupled Plasma 37

7. An X-Y Scanning Photometer for Verifying the

Transmittance Uniformity of Solid Filter SRMs 37

8. Statistical Ruggedness Testing of Acid Rain pH

Measurements 38

9. Improvements in the Determination of Sulfide by Ion

Chromatography 39

10. Direct Microwave Coupling Closed-Vessel Acid

Dissolution 40

11. Leaching of Trace Metals from High Purity

Fluor opolymers 41 12. Development of an Electrometer for Use with Thermal

Ionization Mass Spectrometers 42

13. Determination of the Lead Isotopic Composition in

Human Blood from the Italian Isotopic Lead Experiment.. 43

14. Studies on Ion Optics - Stray Fields 44

15. Automation of RIMS 45

16. Methodology Development for Sub-ppm Boron

Measurements 46

17. Time-Resolved, Magnetic-Dispersion for Large Isotope

Ratio Measurements By Resonance Ionization Mass

Spectrometry (RIMS) 47

18. A New Method for the Accurate and Precise

Determination of Se at Nanogram Levels 48

19. The Determination of Iodine in Foods and Other

Biological Materials by Epithermal Neutron Activation

Analysis 49

20. Multielement Analysis of Biological Macromolecules

iii
TABLE OF CONTENTS (Continued)

Page

21. Light Element Determination by Neutron Activation

Analysis 51 22. Neutron Depth Profiling: Industrial Interaction and

Application 52

23. Re-Characterization of the NBSR at 20 MW 53

24. Determination of Gold and Platinum in Urine at

Picogram Concentrations 54

25. Optimized Measurement of Iodine Isotopic Ratio by

Neutron Activation 55

26. Laboratory Information Management Systems (LIMS) 57

27. Development of a Standard Reference Material for

Rainwater Analysis 57

28. Standard Reference Materials 58

C. Outputs and Interactions 62

III. ORGANIC ANALYTICAL RESEARCH DIVISION

A. Division Overview 81 B. Selected Technical Reports 95

1 . Investigations of Substrate Morphology in

Chromatographic Sorbents by Small-Angle Neutron

Scattering 95

2. Investigation of Secondary Chemical Equilibria in

Liquid Chromatography: Verification of Optimization

Theory for Acid-Base Equilibria and Identification of

Factors which Influence Self-Selectivity 96

3. Optimization of Selectivity Using Sequentially

Coupled Capillary Gas Chromatographic Columns 97

4. On-Line Two-Dimensional Chromatography Using

Supercritical Carbon Dioxide as a Mobile Phase 99

5. Development of a Supercritical Extraction Procedure

for the Removal of Trace Organic Species from Solid

Samples 99

6. Development of a Method for the Stabilization of

Ascorbic Acid in Solution and in Human Serum 100

7. Investigations of the Stability and Recovery of Toxic

Organic Gases Adsorbed on Tenax 101

8. Design and Implementation of a Comprehensive

Laboratory Information Management System to Acquire,

Manipulate, and Archive Chromatographic Data Bases 102

9. Photodissociation of Ions Generated by Cesium Ion

Bombardment for Determination of the Structures of

Organic Molecules 103

10. Comparison of Two Methods for the Calibration of Gas

Chromatography/Mass Spectrometry Instrumentation Used

for the Analysis of Volatile Organic Compounds 104

11. Comparison of the College of American Pathologists

Proficiency Testing Program Results and NBS Definitive

Method Results for Four Organic Analytes in Serum 105

12. Stabilization of Polymer-Film Electrode Morphology by

Thermal and Photochemical Crosslinking 106

IV
TABLE OF CONTENTS (Continued)

Page

1

3

. Polyvinylf errocene-Modif ied Reference Electrode for

Nonaqueous Electrochemistry 107

14. Investigation of the Electrochemical Behavior of

Metal-Dithiolene Complexes 109

15. Investigation of the Electro-oxidative Products of

Retinol and B-Carotene 110

16. Development of Two-Dimensional DEPT CH J-Resolved

1 ^C NMR Spectrum Editing Ill

17. Investigation of Metal-Protein Interactions

18. Viral Proteins from Vaccine Studied by Two-Dimensional

Electrophoresis 112

19. Proteins from Honey Differential by Ultra-Thin

Isoelectric Focusing and Two-Dimensional

Electrophoresis 113

20. Results from Interlaboratory Analyses of Vitamins

and Trace Metals 113

21. Preparation and Certification of Standard Reference

Materials for Dioxins, Chlorinated Pesticides and

PCBs 114

22. Certification of Standard Reference Material 1587

Nitrated Polycyclic Aromatic Hydrocarbons in

Methanol 117

23. NBS Participation in the Certification of a Canadian

Marine Sediment Reference Material 118

C. Outputs and Interactions 119

IV. GAS AND PARTICULATE SCIENCE DIVISION

A. Division Overview 132

B. Selected Technical Reports 145

1. Development of Ultra-Trace (1 ppb) and SRM

Multi-Component Toxic Organic Gas Standards 145

2. Sampling and Analysis of Nitrous Oxide, Carbon

Dioxide, and Methane to Characterize Nitrogen and

Carbon Cycles During NITROP-85 Cruise in the Peru

Coastal Upwelling Region 146

3. Application of Electrochemical Methods for the

Absolute Measurement of SO2 Gas SRMs 147

4. Measurement of Nitric Acid in High Concentration N02 SRMs Using Diode Laser Spectroscopy Coupled with

Chemiluminescence Analysis 148

5. Development of New SRMs for C0 2 in Air at Atmospheric

Concentrations for World-Wide Monitoring of

Atmospheric C0 2 Changes 149

6 . Indoor Air Measurements for Sulfur Dioxide, Nitrogen

Oxides, and Ozone in the National Library of Medicine.. 149

7. Development of NBS Traceable Standards for

Measurements of U.S. Natural Gas Quality 150

8 . Development of Tritiated Methane Standards for

Atmospheric Monitoring 1 51

v
TABLE OF CONTENTS (Continued)

Page

9.

Characterization of Stable NBS Traceable Standards of

SO2 in Air at 100 ppb for Dry Acid Deposition Studies.. 152

10. Intercomparison of Tunable Diode Laser,

Chemiluminescent Detector, and Fourier Transform IR

Measurements of High Concentration NOj/Air SRMs 153

11. Identification and Characterization of Systematic

Error Sources in Tunable Diode Laser Absorption

Measurements 154

12. The Investigation of Simulated Test Data (STD) for

Basic Research and Accuracy Evaluation in

Chemometrics 155

13. Improved Measurements of Environmental Radiocarbon

via Chemical and Isotopic Separation Coupled to

Accelerator Mass Spectrometry 156

14. Carbon Isotope Measurements for Source Apportionment

of Pollutant Aersols and Gases 157

15. Quantitative Compositional Mapping with the Electron

Microprobe Using Wavelength and Energy Dispersive

Techniques 159

16. Development of New Techniques for Light Element and

Trace Element Compositional Mapping. 160

17. Determination of the Half-Life of '°^Re by Laser

Microprobe Mass Spectrometry for Geochemical Dating.... 1 6

1

18. Unique Molecular Characterization of Complex Minerals

by Micro-Raman Spectroscopy 161

19. Development of Digital Imaging on the Analytical

Electron Microscope 162

20. The Development of a Particle Collector for

Microanalysis of Fine Particulate Matter 1 63

21 . The Determination of the Visibility of Chrysotile

Asbestos Fibers Imaged in the Scanning Electron

Microscope 164

22. Magnification Calibration of the Scanning

Transmission Electron Microscope by Hough-Transformed

Images of Grating Replicas 165

23. A Comparison of Two Transient Recorders for Use with

The Laser Microprobe Mass Analyzer 166

24. Automated Method for Analyzing Images Containing

Electron Diffraction Spots 167

25. Determination of the Radiation Damage to

Polycarbonate Film SRMs Used in X-Ray Spectrometry 168

26. Improvements in NBSGSC - A Fortran Program for

Quantitative X-Ray Fluorescence Analysis 169

C. Outputs and Interactions 171

vi
I. Center for Analytical Chemistry

Harry S. Hertz, Director

Richard A. Durst, Acting Deputy Director

A. Center Overview

The Center for Analytical Chemistry develops and maintains the scientific

competences and the experimental facilities necessary to provide the Nation

with the basis for uniform measurements through development of measurement

methodology and reference materials and provision of measurement services in

the field of analytical chemistry. Analytical measurements provide a foundation for scientific and technological research and development concerning materials and their practical application. Moreover, analytical measurements are increasingly used as the basis for industrial, regulatory, and

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 diversity of SRMs

produced in the Center. These reference materials are widely used in such

diverse areas as the metal and chemical industries and in clinical and

environmental laboratories. Each standard is supported by research on homogeneity and stability and is certified as to chemical composition using

the most reliable analytical methods available.

Analytical chemistry is increasingly being called upon to provide key

data for highly complex sample types - hazardous chemical wastes, body

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

Increasingly, analytical values as a function of location within a sample are needed. As the demands upon analytical chemistry become more sophisticated,

the problem of standardization becomes more challenging both in terms of the

number and the complexity of the needed measurement methods and reference

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

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

measurements made in the United States. In addition to research publications

and the certification of reference materials, the Center exerts influence

through close contacts with various communities by means of workshops,

symposia, and participation in 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.

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
In an effort initiated in 1983, we are devoting considerable attention in

the Center to better definition of our user communities and the various

mechanisms for interacting with these communities. During the past year

several new activities have been initiated, as well as maintaining our traditional contacts with user communities. We have initiated a process of

visits to keys members of our industrial constituency, to obtain direct input

to our planning process and to identify chemical measurement needs for the

next few years and for the future. Companies visited included Monsanto,

DuPont, Air Products, and Eli Lily. A meeting of the Analytical Group of the

Directors of Industrial Research was held at NBS in February 1985. Ongoing

interactions with this group are taking place and should prove beneficial.

We have become members of the Analytical Laboratory Managers Association and are finding this a valuable mode for interacting with industrial, government

and academic laboratory managers. Also, during the past year our direct

research for industry has increased with Center for Analytical Chemistry

scientists performing both proprietary and nonproprietary research, where our unique expertise could not be matched in the private sector.

A concerted effort is being made to bring the research accomplishments of

the Center for Analytical Chemistry to the attention of the general public

through press releases and direct written contributions to the general media.

Several examples of these activities are contained on the next few pages.

The general quality assurance concerns of chemical laboratories within

the country have had a direct impact on our activities during the past year.

We, of course, have always provided quality assurance services to our constituency and have considered this our major organizational commitment.

During the last year these activities have been increased through the

formation of a CAC Quality Assurance Task Force. This Task Force has two

responsibilities, an ’’inward" one and an "outward" one. The "inward"

responsibility involves a review of quality assurance practices within the

Center and the issuance of guidelines documents to improve or standardize

those practices. The "outward" responsibility deals with the relationship

of NBS services to constituency claims and constituency needs. Some of the

guideline documents issued during the past year are on the meaning of

traceability of chemical measurements, the contents of NBS Reports of

Analysis, and laboratory record keeping.

Directly related to our interactions with user communities is our major

planning effort in chemical measurement services. As part of this activity,

we have been seeking advice from constituents on the measurement science,

measurement technology, and technology transfer needs which the Center must

prepare for today, to deliver relevant services in the 1990's. A major

factor in our planning is the realization that in an era of increased

reliance on voluntary standards it is vital, in our opinion, to assure the

integrity of the measurement system through traceability to nationally

accepted measurement standards. In this era, a scientifically accurate

measurement base is the best support mechanism for both the industrial and

regulatory sectors of the communities we serve.

2
The program of the Center strives to achieve a balance between the

provision of currently needed reference materials and research efforts on new

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

Center is performed in three Divisions, each focusing upon specific analytes

- inorganics, organics, and gases and particles. Within each Division there

are several groups representing separate analytical chemical disciplines,

e.g., mass spectrometry and electrochemistry. Each Division is responsible

for a program in basic and applied research and maintains contacts with

appropriate scientific and user communities.

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

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

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

3
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4
Chemical Business - January 1985

NBS metallurgist can map elements on and below

a sample’s surface with this instrument.

The National Rnrpflu of Standards

may have a portentous-sounding name^

but its activities are essential to the

day-to-day operations of industry.

For instance, under the government

agency's research associate program,

founded in 1921, some 500 industry,

university and government representatives annually work alongside NBS

researchers in the government's laboratories. Under the program this fall, researchers from Mobil Research &

Development Co. investigated the ef- fectiveness of various distillation methods in removing arsenic impurities from

coal and shale oil. Other investigators

from Exxon Chemical Co. used the NBS

Measuring the Nation’s

Measurement Capability

By DONALD VERASKA

nuclear reactor in a neutron-scattering

experiment designed to measure the

compatibilities of polymer blends. In addition to working relationships

with industry laboratories, the government metrology agency also maintains

close ties with a number of industry

groups. As explained by John A. Blair,

manager of standards development, at the polymer products department of E.

I. du Pont de Nemours & Co., Wilmington, DE, “I’d say the bureau plays a key role in working with industry. I don’t know how it would be replaced.

Certainly, industry would have to be

doing a lot more if there were no National Bureau of Standards. Du Pont,

Dow [Chemical Co., Midland, MI],

Monsanto [Co., St. Louis, MO] and all the companies would have to be doing

what the bureau is now and there’d be

a lot of overlap.” In one of these industry relationships

the American Chemical Society, along

with the American Institute of Physics,

publishes and distributes the quarterly

Journal of Chemical & Physical Refer- ence Data. Something of a bible for the

two disciplines, it contains tables of

physical and chemical properties of

materials as well as articles about the

research on those data.

The information had been printed and

distributed through the Government

Printing Office, but that changed in 1972 when the journal was created to assure a more effective dissemination

of the data.

NBS also has research contracts with

the Chemical Manufacturers Association, in which CMA represents a con- sortium of chlorofluorocarbon manufacturers seeking data about the measurement of CFC in the atmosphere.

CMA regularly conducts workshops

with the bureau on this and other topics

of mutual concern.

Specifically, the CFC manufacturers

want NBS help in developing methods

to determine atmospheric ozone changes

that are actually occurring, as a way

to prove or refute current conclusions

based on theoretical or calculated ozone changes. Such a determination would

help both parties in regulatory matters concerning the commercial uses of

chlorofluorocarbons

.

This national metrology agency also has a close relationship with the National Research Council of the National

Academy of Sciences, which, since 1958. has reviewed and evaluated the functions and operations of the bureau

through a series of appointed panels.

The panels, whose members repre- sent research and administration in in- dustry, universities and government,

meet annually with counterparts in NBS program areas. They examine the

importance and set priorities for NBS

projects, quality of staff, equipment

needs, finances and the relationship of

the programs to its overall mission.

Founded in 1901, three years before

the creation of the Department of

Commerce, the agency was directed to develop and maintain the measurement

capabilities required to advance science,

industry and commerce and to carry

out research to determine the properties

of materials.

As far as the chemical industry is concerned, that charter has evolved to create a number of programs, among

them the Standard Reference Materials

(SRMs). Produced by the bureau since

1905, when the American Foundrymen’s

Association asked for help in producing

standard samples of cast iron, there

are more than 1,000 SRMs today. The

bureau develops and sells them to users wanting to develop accurate testing

methods and to calibrate instruments

and measurement systems for quality

5
Chemical Business - January 1985 (Continued)

control. The 174-page Standard Ref- erence Materials Catalog is the Sears

catalog of industry, listing such items

as a 65-gram unit of potassium iodide

for $200.

Another program produces Standard

Reference Data (SRD). Although the

bureau has provided data on the properties of materials almost since its in- ception, the formal system did not take

shape until 1963 when the Federal

Council for Science & Technology asked

NBS to take responsibility for promoting and coordinating the evaluation of

numerical data in the physical sciences.

A formal legislative mandate for the

program came in 1968. Under the SRD program, the properties of hundreds of thousands of materials are determined, cataloged and

distributed through the ACS/AIP

journal. Some 1,000 corporate and in- dustrial subscribers pay $200 a year

per copy. The data are also distributed on magnetic tape, using six databases

which are leased for up to $7,500. There

is also an on-line computer network op- erated by the bureau, along with the

Environmental Protection Agency, the

National Institutes of Health and other

federal agencies.

Physically, NBS facilities are at two

principal locations. Within the Joint Institute for Laboratory Astrophysics,

operated with the University of Colorado in Boulder, are 380 staffers car- rying out studies in atomic and

molecular physics and astrophysics.

At the main headquarters on a campus-like 576-acre setting in Gaithersburg, MD, some 2,300 full-time

employees work in 27 buildings that

include a high-flux nuclear research reactor, an electronic accelerator, a fire

research laboratory, an experimental

computer facility and several environmental test chambers.

The agency is considered free from

political pressures, although its director

is a presidential appointee. Dr. Ernest

Ambler has filled the post since 1978

(he was acting director for three years

before that) and his appointment was

continued during the Reagan Administration. His agency's budget for fiscal 1985 comes to $207.4 million, up from

$196.7 million in FY 1984 and from $186.5

million for FY 1983. The Gaithersburg facility is organized J into the National Measurement Laboratory, the National Engineering

Laboratory, the Institute for Computer

Sciences & Technology and the Center

for Materials Science. Within them are

three groups with a direct relationship

with the chemical industry.

The Center for Chemical Physics.

It conducts research into such subjects

as environmental monitoring, fossil fuel combustion and biotechnology. Its re- searchers develop advanced measure- ment techniques in surface science,

chemical kinetics, thermodynamics and

molecular foundations of complex physicochemical systems.

Among the practical applications of

this center’s work are proposals to monitor the effectiveness of the burning

of hazardous waste, using sulfur hexafluoride tracer compounds, and a pro- cess to help limit acid rain through

removal of sulfur dioxide from industrial gas streams by converting sulfur and

nitrogen to more easily removed acids. Q The Center for Chemical Engineering. It provides industry with

measurements and databases through

research into chemical process technology, thermophysical properties of

fluids and solids, and chemical engineering science. Results of the research

include calibration and measurement

services to the chemical, petrochemical,

plastic and petroleum industries.

The center is about to publish data

gathered in a three-year study of orifice meters to measure pipeline flow of gas

and oil. With existing data, such meters now measure flow only to within 1 per6
Chemical Business - January 1985 (Continued)

cent accuracy. Dr. Merrill Hessei, deputy director of the center, says that the new data will help improve that accuracy

by a factor of 10. The Toxic Chemicals Handling

Laboratory. This facility stores, handles and analyzes organic compounds

that are extremely toxic or possess undesirable biological activity. The lab- oratory allows scientists to characterize or analyze such materials in a safe manner.

Dr. Stephan Chesler, group leader of

chromatography at the laboratory, notes that the facility recently prepared and

certified a Standard Reference Material

solution of 2,3,7,8-tetrachlorodibenzop-dioxin, known commonly as dioxin.

This SRM will be available soon and

will permit industry and health laboratories to standardize and calibrate

their laboratory measurements in eval- uating dioxin samples.

The Center for Analytical

Chemistry. According to its director. Dr. Harry S. Hertz, it probably impacts more directly on the chemical industry

than any other division within the bureau. The center helps ensure the ac- curacy of the more than 30 billion

chemical analyses performed annually

in the US by government, industrial

and public and private testing laboratories. It is a reference laboratory for chemical compositional measurements

of inorganic, organic, gaseous and particulate materials.

Beginning this year, the center for the first time is making its facilities available for proprietary testing re- search by industry. Says Dr. Ambler

in the bureau's annual report, “By in- creasing industry's access to our advanced measurement capabilities, we

hope to help industry improve its products and processes and thus its inter- national competitiveness.”

It may be worth noting that the bu- reau is organized within the Department of Commerce, whose primary

function is to promote US business.

Until this spring, the bureau's policy was to disseminate openly all measurement and standards information

coming from industry requests for

testing; the new policy will, in certain

instances, allow the results to be given

only to the contracting party.

Use of the bureau’s facilities for outside parties, including other government

agencies, is on an at-cost basis. In fact,

perhaps 40 percent of this center's budget comes through work performed for such other agencies as the Environmental Protection Agency and the military. Perhaps the one exception is the

Food & Drug Administration, which,

says Dr. Hertz, has its own substantial

in-house laboratory capability.

While the center normally does not

duplicate testing that can be done by

private laboratories, it may take on such

a project when federal regulatory policy

is a consideration. Last year, for in- stance, it tested surgical implant devices—hip joints, lenses for cataract

patients and cardiac pacemakers were among them—for residues of ethylene

oxide, a sterilant. The results from in- dustrial and private testing showed wide

discrepancies. The $40,000 cost of the

project was reimbursed by FDA.

“I’d say the bureau

plays a key role.”

An example of the more direct working relationship between the bureau and

the chemical industry is seen in its as- sociation with the Chemical Manufacturers Association. During the past

decade it has centered on the Fluorocarbon Research Program of CMA’s

Special Programs Division. A consor- tium of 19 worldwide chemical companies

that manufacture chlorofluorocarbons

has financed hundreds of programs designed to assess the impact of CFCs

on the environment, particularly in the

stratospheric ozone layer. The group

includes Allied Corp., Du Pont, Essex

Chemical Corp., Kaiser Aluminum &

Chemical Corp., Pennwalt Corp. and

Union Carbide Corp.

Eight of those studies have been

awarded to the National Bureau of

Standards. Five have been completed

and three—kinetic measurements of

atmospheric constituents, temperature

dependence of the infrared bond

strength for CFC 11 and CFC 12 and

high-resolution infrared spectroscopy

of hydrogen chloride—are continuing

at a cost of $140,000. ED

7
UNITED STATES DEPARTMENT OF

NATIONAL BUREAU

OF

STANDARDS

GAITHERSBURG, MO 20899

A National Bureau of Standards

News Feature

John Henkel

301/921-3181

HOLD FOR RELEASE UNTIL

March 29, 1985

TN-5531

MEASURING THE TWO "PERSONALITIES" OF OZONE

IT’S A STANDARD PROBLEM AT FEDERAL LAB

Ozone is the Jekyll and Hyde of the environment: It's both a boon and a

bane to humanity.

Consider its "split personality." Ten miles or so into the earth’s

atmosphere, ozone is a lifesaver. It acts as a screen for keeping

humans—and every other living thing—from being scorched by the sun’s

ultraviolet rays. But on the earth's surface, ozone is a noxious gas—

a

byproduct of auto exhaust that federal and local governments go to much

trouble to regulate.

At the heart of ozone's odd nature is its behavior as gas. Unlike most

others, it is impossible to contain and difficult to measure. While

scientists labor over just how much this gas is harming or helping the

environment, they need another party to help determine if the sophisticated

instruments used to measure ozone concentration on the ground or in the

upper atmosphere are providing accurate numbers. The place they turn to is

the Comnerce Department's National Bureau of Standards (NBS), where making

such acute measurements is a specialty.

8
The Elusive Gas

Scientists in the NBS Center for Analytical Chemistry routinely provide

reference materials for checking how well gas analysis equipment performs.

But ensuring such accuracy for ozone is tricky. Regulatory agencies

responsible for measuring ground-level ozone must periodically calibrate the

instruments that gauge ozone concentration. Such calibrations are fairly

easy when using the equipment that measures many of ozone's pollutant gas

cousins such as sulfur dioxide or nitrogen dioxide. This is because

bottled, pre-measured standards of these gases can be bought from NBS to

ascertain equipment performance.

But ozone is different.

"If you have a steel cylinder and you put pure oxygen in it, you can come back in 100 years and the oxygen will still be there,” says Dr. Arnold

Bass, who manages the NBS ozone calibration laboratory. ”But put ozone in

there and by the time you finish putting it in and closing the valve, most

of it will be gone.” What happens, he explains, is that ozone reacts

quickly with the container material and is destroyed almost instantly.

With containment out of the question, scientists look to other ways of

measuring the elusive gas. Though there are several techniques for

determining ozone concentration, the current method of choice is photometry,

developed cotranercially in the 1970s as an alternative to the messier, less

reliable "wet chemical” methods used for years. (Environmental ozone is

regulated by EPA, but controls are administered by local governments which

can use EPA photometry standards to ensure accurate readings. EPA then

turns to NBS, which has no regulatory authority, for technical assurance

that the standards are accurate.)

NBS uses a device, appropriately dubbed an ozone reference photometer,

to calibrate the EPA standards. First developed at the bureau in 1976 at

the request of EPA, this standard began as a bulky, 10-foot-long device.

With the help of Dr. Richard Pauer of EPA, it has since been reinvented and

shrunk to about one-third its original size. Now it's portable and 50 times

more sensitive than the earlier device, which can be attributed, Bass says,

to "improved technology and streamlined design.”

Shedding Light on a Sample

Photometers—whether they are used in the field for environmental

measurements or in the laboratory as standards—work on the principle that

ozone absorbs light in the ultraviolet (UV) portion of the spectrum

proportionate to the concentration of the gas. By shining UV light through

an air sample, scientists can calculate the ozone concentration in that

sample by determining the difference in light intensity between the entrance

and exit points of the air sample container. At NBS, researchers have

worked out methods where a known quantity of ozone can be produced by the

NBS reference photometer, then fed into another monitoring instrument, such

as a photometer maintained by EPA, to check its accuracy. If the monitoring

instrument comes up with the same readings as the NBS standard, it is

working properly. Otherwise, the instrument will have to be recalibrated.

9
EPA requires local agencies to use photometry for ozone measurement and

depends on NBS to assure the accuracy of ozone instruments. NBS initially

accomplished this by having agencies come to the bureau to calibrate their

instruments against the NBS standard. But now NBS is in the process of

building photometer standards that can 'be placed in EPA regional

laboratories across the country so local governments can bring their

photometers to those labs for calibration. The EPA labs then periodically

will check their instruments against the NBS reference photometer. EPA's

central laboratory near Raleigh, N.C., is equipped with a photometer

standard supplied by NBS, as are EPA labs in California and New Jersey.

Four more of the devices will be delivered by the end of this year.

"Without a photometer standard, all the user in the field can do is

check his instrument's results against those of a neighboring locality, and

in that situation, both instruments may be wrong," says Larry J. Purdue,

acting director of the quality assurance division of EPA. "What [the NBS

reference photometer] will do is find photometers in the field that are not

working properly. Users then will have to do maintenance on their defective

equipment."

Ozone measurements also have been a concern of industrial firms which

have consulted NBS. For example, one manufacturer of office machines has

requested assistance in determining the levels of ozone that might be

produced by photocopiers. And a large aircraft company has asked for

measurement help from NBS in its study of the effects of breathing ozone

from the stratosphere when aboard a plane.

The bad name ozone gets as a pollutant underscores its highly reactive

nature—that is, the gas reacts chemically with just about everything it comes in contact with. If inhaled, ozone can act as a strong oxidant,

reacting with lung tissue and irritating the respiratory tract. And it can cause wear on car tires by reacting with rubber. "Just how much an effect

it has on tires we don't know," says Bass. "We do know that if you leave a box of rubber bands in an ozone environment in the laboratory, then come back in a month, they'll just fall apart."

There's a Good Side Too

Ozone is not all bad. In fact, if the layer of ozone that surrounds the

earth 10 to 30 miles up—which screens the harmful UV rays of the sun—were

to be seriously diminished, scientists predict that crops would dry up, the

earth's oxygen cycle would be interrupted, and skin cancer would become an epidemic. That's why researchers worldwide have studied the ozone layer

extensively to determine if it is being depleted, and if so, how to head off

disaster.

Many suspected causes of ozone depletion have been studied in the last

decade, the most celebrated probably being the chlorofluorocarbons formerly

found in nearly all refrigeration equipment, hairsprays, and spray

deodorants. These compounds have since been removed from many products, but

the effects of when they were used as propellants in spray cans remain.

10
"The problem with chlorofiuorocarbons is that they are stable and inert,

so when they are released they just drift up into the atmosphere and there's

nothing to remove them on the way up. They just keep going,” says Bass.

"When they get high enough the action of the sun can release chlorine atoms

and start a chain reaction that reacts very quickly with ozone, destroying

many ozone molecules. It could take as .long as 100 years to decompose the

fluorocarbons that are already in the atmosphere.” There are other

suspected ozone destroyers, such as methane gas produced by rice paddies and

grazing animals, and even airplane exhaust.

Resetting the Table

Before any conclusions can be made about the state of the earth's ozone

layer, scientists must find out just how much ozone is in the atmosphere

compared to how much was once there. This is done by sophisticated

instruments that measure the ozone layer from the earth and from the sky

through balloons, high-altitude planes, rockets, satellites, and in the

future, from the space shuttle. Many of these instruments work on the same principle of UV absorption as photometers. However, in order to reliably

monitor the ozone composition of the high atmosphere as contrasted with that

determined at ground level—two measurements that ideally should

agree—scientists need an accurate system of measuring the transmission of

UV radiation through the atmosphere.

NBS has contributed to these measurements by developing—in cooperation

with the NASA Upper Atmosphere Research Office—a table of 1 ,200 measurement

points that indicates how much UV radiation will be absorbed at various

temperatures and at different wavelengths of ultraviolet light. This table

of values, or cross sections, refines a French study done in 1953 under

which ground-based and airborne instrument results varied as much as 8

percent. The NBS research has cut these differences to no more than 2

percent.

"What we've done is greatly reduce the discrepancy between the two

methods of observing atmospheric ozone so the differences that remain may

reflect differences in other aspects of the monitoring,” Bass says. "Now someone who is making these measurements , and needs to interpret what the

distribution of ozone is in the atmosphere, can use these cross sections for

that interpretation. The measurement system is much more accurate now.”

The bureau's work in this area has been recognized internationally as evidenced in September 1984 at the Quadrennial Ozone Symposium in Halkidiki,

Greece. There, the International Ozone Conrnission recommended that the NBS ozone cross-section table be accepted as the international standard for

determining ozone concentration from satellite instruments.

Ozone's strange nature will no doubt continue to prompt debate over whether the ozone layer is depleting, as well as concern over the gas as a pollutant. The environment's Jekyll and Hyde isn't about to go away anytime

soon. But, as NBS f Bass says: "Whether the ozone is on the ground or in

the upper atmosphere, someone needs to be responsible for the accuracy of ozone measurements. And that's what our job is."
Wall Street Journal - September 11, 1985

Taking Measures Against Poisons

P. J. Wingate i Aug. S editorial-page »rtide* on (ox:c substances contains * convincing argument (or carefully considering

tfte amount of a toxic material present be- fore jumping to conclusions about tile dan- ger to tile environment. However, tile actual measurement accuracy for many pol- lutants is a source at major concern and

discrepancy.

Numerous federal studies over tfte last decade have mown vide-ringing results wnen several laboratories were called on

to measure tfte same sample. Sometimes it ha* (seen difficult for regulatory agencies

to say Jim flow mueft of an environmental

hazard Ls present and. tfterefore. Just .low hazardous tt Is. Part of tfte proolem ts that

for many pollutants (Here nas oeen no mlaoie reference material: that is. no pre- measured samples tftat labs can analyze to ensure tftat equipment and metftods are

accurate. But tftls is changing.

Take tfte measurement of uoestca. u a

1977 Snvtronmenui Protection Agency

study exemplifies. The SPA tftat year wanted to examine Montgomery County.

McL. roads surfaced witft crusned stone to determine tfte amount of asoestos fibers—

wntcfl occur naturally In some roexs— in

tfte air around tfte roads. Zlgm labs are nved at vastly different figures: one said

1.S00 fibers were In a cubic-meter sample,

anotfter arrived at 25 million fibers for tfte same sample. Tftls amazing disparity

prompted tfte SPA to have itieJ^USE^L

Jjjjjsu^ofSfandam^develop a reierence

material lar Ufiesios? Tftat material—par-

• tlcuiarly difficult and time-consuming to produce— became available last year and

ts tfte first definitive standard (or asbestos measurements.

•Tftere are otfier “horror none*.'- rang- ing from measurement of toxic PC2s In oil to determining tfte concentration ot lead in blood samples to tfte very identification of

tfte different toxic cftemicats present in contaminated water and soil. In eacn of

tftese studies, disparate results were re- ported from't variety of sources. In tfte last case, not only tfte amount of a pollu- tant was tn question, but even tfte Identity

of tfte pollutants.

These problems are being addressed by

tfte bureau. However, measurement and Us

accuracy are not Issues one can relegate

strictly to tfte domain o< tfte lab. Tfte social and economic tmpllcailons of bad meas- urement mane tftls an issue of relevance to everyone. Pad measurements lead to diffi- culty in detecting pollution trends, hinder- ing society from evaluating regional differ- ences or making progress tn pollutant control. Sad data cause delays in voluntary

and regulatory action owing (3 tfte incon- clusive nature of tfte information. Most se- riously. bad data can lead to erroneous

conclusions. All of tftese social costs have

tfte potential for delaying health-effects re- searen.

Tfte economic coats of bad measure- ment to industry are also great. Studies are likely to be overdesigned, resulting in costly repeat analyse*. Tfte price of Inter- preting inaccurate data and sorting good

data from bad is great because poor dau

la a large study dimtmsA tfte value ofTfle good data also present. Appropriate environmental actions cannot be taken based on inconclustve^data. But since tfte price is htgn people are be- ginning to pay attention. Authorities seem

to agree tftat environmental measurements

are gradually improving. MBS standard

reference materials can take some of tfte credit along witft more reilaole equioment

and better quality control tn tfte laos. But

It ts a slow process to ensure tftat lab*- pro- duce data tftat are more fact tftan fiction. Until we reaefl tftat measurement nirvana,

tfte question not only is going to be “How

mueft Is too mud?" as Mr. Wingate

pointed out. but “How mueft Is really

tftere f" Hajuy S. Harrs

Olrector Center for Analytical Chemistry

National Bureau of Standards

Gaithersburg. Md.

Blood lead standards available from NBS

A reliable standard for determining the accuracy of

analyses of lead leveis in blood is now available

from NBS. The new Standard Reference Material is in the form of four vials of porcine blood, containing

lead at concentrations ranging from 5.7 to 732. ^g

per deciliter. The standards can be used by clinical chemistry laboratories both to calibrate their analytical instruments and to verify the accuracy of differ- ent analytical procedures. The material is available

from the Office of Standard Reference Materials.

B311 Chemistry 3tdg., National Bureau of Standards.

Gaithersburg, Md. 20899, and costs 5104.

August 12. IMS CAEN

12
B. Outputs and Interactions

(Center for Analytical Chemistry)

1 . Publications

Taylor, J. K., Quality Assurance of a Measurement Program , ACS Symposium

Series 267 ( 1 984)

.

Velapoldi, R. A., Hertz, H.S., and Taylor, J. K., Technical Activities 1984,

Center for Analytical Chemistry, NBSIR 84-2979 (1984).

Velapoldi, R. A. and Hertz, H. S. , The Bases for Quality Assurance of

Chemical Measurements and Standards for Speciation, Dahlem Konferenzen,

Proceedings of Workshop on the Importance of Chemical Speciatlon In

Environmental Processes , Berlin, Federal Republic of Germany, 1984 (in

press)

.

Hertz, H. S., Search for Hay in a Needlestack, Book Review, Nature, 315 , 163

(1 985).

Hertz, H. S. , Wolf, W. R. , Chapter 7 — Open Discussion On Needs and Uses

for Biological Reference Materials, Biological Reference Materials:

Availability, Uses and Need for Validation of Nutrient Measurement , Wolf, W. R., ed., John Wiley & Sons, Inc. (1985).

Hertz, H. S. , Taking Measures Against Poisons, Letters to the Editor, Wall

Street Journal, September 11, 1985.

Hertz, H. S. , Accuracy in Clinical Chemistry: The Roles of Definitive

Methods and Roger K. Gilbert, Archives of Pathology and Laboratory

Medicine 1985, in press.

Taylor, J. K., Principles of Quality Assurance of Chemical Measurements,

NBSIR 85-3105 (February 1985).

Taylor, J. K., State Measurement Laboratories: Part 1, Certification of

Capability; Part 2, Authorization for Type Evaluation, (with H. V.

Oppermann), NBS Handbook 143 (1985).

Taylor, J. K., Handbook for SRM Users , NBS SP 260-100 (1985).

Taylor, J. K., The Quest for Quality Assurance, accepted for publication in

American Laboratory (1985).

Taylor, J. K., The VD Conspiracy (with E. Goldberg), Marine Pollution Bull.

1_6 , No. 1 (1 985).

Taylor, J. K. and Kratochivil, B G., Sampling of Bulk Substances for Chemical

Analysis, ISAS Newsletter (submitted 06-20-85).

Taylor, J. K. and Stanley, T. W., eds., Quality Assurance for Environmental

Measurements , STP 867, ASTM, Philadelphia, PA 19103 (1985).

13
Taylor, J. K., What is Quality Assurance?, Quality Assurance for Environment- al Measurements , ASTM STP 867, J. K. Taylor and T. W. Stanley, eds.,

American Society for Testing and Materials, Philadelphia, 1985, pp.

5-11.

Velapoldi, R.A. and Burke, R. W., Recommended Reference Materials for

Realization of Physicochemical Properties: Wavelength and Transmittance, IUPAC Commission on Physicochemical Measurements and Standards,

in press.

2. Talks

Hertz, H. S. , "Ten Years of Quantitative Analytical Chemistry - A Decade to

Trace", Federation of Analytical Chemistry and Spectroscopy Societies,

Philadelphia, PA, September 1984.

Velapoldi, R. A., "What is the NBS Research Associate Program?", College of

American Pathologists, Industrial Liaison Committee, New Orleans, LA,

October 28, 1984.

Hertz, H. S. , "Quality Assurance, Reference Materials and Environmental

Specimen Banking: Three Important Components of Environmental

Monitoring Programs", The 1984 International Chemical Congress of

Pacific Basin Societies, Honolulu, Hawaii, December 1984.

Taylor, J. K., "Guidelines for Data Acquisition and Data Quality Evaluation

in Environmental Chemistry," Coastal Empire Section, ACS, Savannah, GA,

November 12, 1984. Invited

Taylor, J. K., "Quality Assurance of Chemical Measurements," Savannah River

Section, ACS, Aiken, SC, November 1 3 » 1984. Invited

Taylor, J. K., "Standards for Chemical Analysis," South Carolina Section,

ACS, Florence, SC, November 14, 1984. Invited

Taylor, J. K., "Quality Assurance of Chemical Measurements," CarolinaPiedmont Section, ACS, Charlotte, NC, November 15, 1984. Invited

Taylor, J. K., "The Professional Practice of Chemistry," Northeast Tennessee

Section, ACS, Kingsport, TN, November 16, 1984. Invited

Taylor, J. K., "Principles of Quality Assurance," NBS-NOAA Workshop on QA,

National Bureau of Standards.

Velapoldi, R. A., "Spectrophotometry/Spectrof luorimetry" , 4th Annual ADABSE

Workshop, November 1984.

Taylor, J. K., "The Use of Control Charts in Chemical Analysis," PACHEM

Meeting, Honolulu, Hawaii, Dec. 21, 1984.

Taylor, J. K., "General Aspects of Quality Assurance," Brazosport Local

Section ACS, Lake Jackson, TX, January 15, 1985. Invited

Taylor, J. K., "General Aspects of Quality Assurance,", Sabine-Neches Local

Section ACS, Beaumont, TX, January 16, 1985. Invited
Taylor, J. K., "Principles of Environmental Analysis," Southwest Louisiana

Local Section ACS, Lake Charles, LA, January 17, 1985. Invited

Taylor, J. K., "Professional Practice of Chemistry," Louisiana Local Section,

New Orleans, LA, January 18, 1985. Invited

Taylor, J. K., "General Aspects of Quality Assurance," University of

Cincinnati, Institute of Environmental Health, Cincinnati, Ohio, January

30, 1985. Invited

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

Course, New Orleans, LA Feb. 22-24, 1985

Taylor, J. K., "Statistics for Chemists," Pittsburgh Conference, New Orleans,

LA, March 1, 1985. Invited

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

Course, Nashville, TN March 7-8, 1985.

Taylor, J. K., "Quality Assurance of Chemical Measurements," NBS/FDA,

Rockville, MD March 18-19, 1985.

Taylor, J. K., "Principles of Quality Assurance," Johnson Controls,

Milwaukee, WI, April 17, 1985. Invited

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

Miami, FL - April 27 - 28, 1985.

Hertz, H. S. , "Quality Assurance, Reference Materials and The Role of a Reference Laboratory in Pollutant Measurements", Analytical Techniques

in Water Pollution Control, Water Pollution Control Federation

Conference, Cincinnati, Ohio, May 1985.

Taylor, J. K., "Quality Assurance of Chemical Measurements," NBS - May 1,

1 985.

Taylor, J. K., "Quality Assurance of Chemical Measurements," NBS - May 8-9,

1 985.

Taylor, J. K., "Control Charts for Chemical Analysis" - NBS Div. 551 Seminar,

May 14, 1985. Invited

Taylor, J. K., "The Quest for Quality Data," Chemical Institute of Canada,

Queen's University, Kingston, Ontario, Canada, June 5, 1985. Inv itec

Taylor, J. K., "Quality Assurance of Chemical Measurements," Kingston, Canada

Short course, June 4-7, 1985.

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

Course, Toronto, Canada, June 25-26, 1985.

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

Center, Edgewood, MD, July 2-3, 1985.

15
Taylor, J. K. f "Quality Assurance of Chemical Measurements," ACS Short

Course, Denver, CO, July 17-18, 1985.

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

Course, Edmonton, Canada, July 23-24, 1985.

Taylor, J. K., "Principles of Calibration," ASTM Conference, Boulder, CO

August 12, 1985. Invited

Taylor, J. K., "Quality Assurance of Chemical Measurements," Los Alamos

National Laboratory, Los Alamos, NM, August 29~30, 1985.

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

Course, Chicago, IL, Sept. 7-8, 1985.

Taylor, J. K., "The Impact of Instrumentation of Analytical Chemistry," ACS

Meeting, Chicago, IL, September 9, 1985. Invited

Taylor, J. K., "Statistics for Chemists," ASTM Committee E-2 Meeting,

Hershey, PA, September 11, 1985. Invited

Taylor, J. K., "Quality Assurance of Chemical Measurements," EPA Office of

Toxic Substances, Washington, DC, September 17-18, 1985.

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

Center, Edgewood, MD, September 23-24, 1985.

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

Course, Philadelphia, PA, September 27-28, 1985.

3. Committee Assignments

Harry S. Hertz

Secretary, American Society for Mass Spectrometry (Term completed July

1 985)

Chairman, Education Committee, American Society for Mass Spectrometry

Member, ASTM, Committee D1 9 on Water

President-Elect, National Committee for Clinical Laboratory Standards

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

for Calibration of Instruments Meant for Checking Substances During

Medico-Biological and Research Analyses

Member, Analytical Laboratory Managers' Association

Member, Department of Energy Health and Environmental Research Advisory

Commi ttee

Member, Editorial Advisory Board, Analytical Chemistry

Ranee A. Velapoldi

Member, Interagency Toxic Substances Data Committee

Working Advisor, ASTM, Committee E7 on Nondestructive Testing,

Subcommittee E7.03 on Liquid Penetrant and MPI Methods, Task Group

E7.03.03 on E-270 Glossary Revision

16
Member, ASTM, Committee El 3 on Molecular Spectroscopy,

Subcommittee El 3.06 on Molecular Luminescence

Task Group El 3.06.01 on Presentation of Corrected Fluorescence

Spectra

Task Group El 3.06.02 on Recommended Practices on Molecular

Fluorescence Spectroscopy

John K. Taylor

Member, IS0/TC48, Glassware and Related Apparatus

IS0/TC48/SC01 , Volumetric Glassware

IS0/TC1 46, Air Quality

IS0/TC01 , Stationary Source Emission

ISO/TC02 , Work Place Atmospheres

IS0/TC03, Ambient Atmospheres

IS0/TC04, General Aspects

Chairman, ASTM D19.01, International Standards

ASTM D22 , Sampling and Analysis of Atmospheres

Member, ASTM D19, Water

ASTM D19.02, 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 D22.09, ISO TAG for IS0/TC1 46

ASTM E34, Occupational Safety and Health

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

Agencies

ASTM E36.10, Generic Criteria

ASTM E36.30, Nomenclature and Definitions

ASTM E41 , Laboratory Apparatus

ASTM E41.01, Glass and Plastic Apparatus

ASTM E41.06, Weighing Devices

ASTM E41.07, Microchemical Apparatus

Collaborative Testing Subcommittee - Standard Methods

Advisory Committee - CHEMTECH (ACS)

ACS Committee on Environmental Chemistry - Subcommittee on Environmental

Analytical Chemistry

NBS Museum Committee

NBS Representative - Interagency Advisory Committee on Water Data

4. Other

a. Conferences

H. S. Hertz, Analytical Group of the Directors of Industrial Research,

National Bureau of Standards, Gaithersburg, MD, February 8, 1985.

5. Center Colloquium Series

October 17, 1984 - Professor Milton L. Lee, Department of

Chemistry, Brigham Young University, Provo,

UT, "Stationary and Mobile Phases in

Capillary Chromatography".

17
December 13. 1984 Professor Konrad Mauersberger , University of

Minnesota, Minneapolis, MN, "Ozone: Laboratory Studies and Stratospheric

Measurements"

.

January 9, 1985 Professor Roland F. Hirsch, Seton Hall

University, South Orange, NJ, "Application of

DARC Topological Analysis to Research in

Analytical Chemistry".

February 13, 1985 Dr. Jack M. Holl , U. S. Department of Energy,

Germantown, MD, "The Great Nuclear Debate:

The Management and Control of Nuclear Energy

Since World War II".

March 4, 1985 Dr. Christopher Burgess, Glaxo Operations,

Durham, Great Britain, "Documentation,

Analytical Control, and Robotics in

Analytical Chemistry".

March 13, 1985 Dr. Seymon Suckewere, Princeton University,

Princeton, NJ, "Soft X-Ray Laser Gain

Measurements in a Recombining Plasma

Column"

.

April 1, 1985 Dr. Ivo Allegrini, Instituto

Sull* inquinamento Atmosferico, Rome, Italy,

"Recent Developments in Instrumentation and

Methods for Air Pollution Measurements".

August 1, 1985 Dr. U. Haas, University of Hohenheim, West

Germany, "The Capabilities of Photoacoustic

Spectroscopy in Depth-Profiling and Thickness

Measurement"

.

September 11, 1985 Dr. Edward M. Chait, E. I. DuPont de Nemours

and Co., Inc., Wilmington, DE, "An

Industrial Perspective of Biotechnology".

18
c. Voluntary Standardization and Quality Assurance

1. Voluntary Standardization

The Center continues to play an important role in standardization

activities. Thirty-six members of the staff hold 149 memberships on standards committees, including positions of leaderships on 10 of these, as follows:

ASTM C-26 Nuclear Fuel Cycle

ASTM D-1

9

Water

ASTM D-22 Sampling and Analysis of Atmospheres

ASTM E-02 Emission Spectroscopy

ASTM E-03 Chemical Analysis of Metals

ASTM E-07 Nondestructive Testing

ISO/TCI 46 Air Quality

ISO /TCI 47 Water Quality

IUPAC Commission on Atomic Weights

NCCLS National Committee for Clinical Laboratory Standards

Leadership was provided in organizing a "Conference on Sampling and

Calibration for Atmospheric Measurements", sponsored by ASTM Committee D22.

Center personnel presented 5 papers at the conference which will be published

in the proceedings.

2. Quality Assurance

The Center's program to provide quality assurance education and

assistance to other government agencies and to the public has been very

active during the past year. A key feature of this is the Quality Assurance

Seminar series initiated in 1983. These seminars are of two types: those

held at NBS consist of 10 hours of lectures and 4 hours of small-group

discussions (mini-workshops) in selected measurement areas; those presented

away from NBS consist entirely of 16 hours of lectures given during a two-day

period. Essentially the same material is presented in the lectures of both

seminars, except that the content is enlarged in the case of the latter type.

Three seminars of the first type were presented at NBS to a total of 150

persons. Seminars were presented at the Food & Drug Administration, EPA

office of Toxic Substances; Army Chemical Center, Lawrence Livermore Laboratory, and Los Alamos National Laboratory. A seminar co-sponsored by NBS and

the National Research Council of Canada was presented at the meeting of the

Chemical Institute of Canada held at Kingston, Ontario in June 1985. Eight

seminars were presented under ACS sponsorship and two in cooperation with the

1985 Pittsburgh Conference and Exposition. Since its inception in 1981, 58

seminars have been presented to a total audience of 2500 persons.

An experimental Chemical Measurement Assurance Program (CHEMAP) is in

the planning stage. This will consist of the systematic use of SRMs together

with control charts to assure statistical control of a measurement system.

The Center will provide guidance in the selection of appropriate SRMs and in

the evaluation of the measurement data. The program has been presented to

several groups and several laboratories have expressed interest in participating during the coming year. Based on the experience gained, it is

expected that the CHEMAP Program will be made available to a wider audience

in the following year.

19
The center has organized a quality assurance task group that is

developing selected aspects of its QA program. During the year, the group

has developed a document on Traceability which discusses the concept and

describes how SRMs may be used for this purpose. A second document establishes the format for analytical reports and gives guidance for their

preparation. A document setting forth policy and guidance for laboratory

record keeping has been prepared as well as a form for use in defining the

work to be done in service analysis or for SRM certification measurements. A

document providing guidance for the more uniform statistical treatment of

measurement data is now in preparation.

John K. Taylor

20
D. Service Analysis

The performance of service analyses continues to be an important

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

this activity, the technical staff gives advice, performs accurate chemical

analyses, and provides state-of-the-art calibrations on a wide range of

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

NBS staff and to all f Moral, State, and Local government groups. It is also

available for use by the private sector in those special instances for which

CAC possesses a unique measurement capability. Within the latter category,

the two most frequent types of requests are for the verification of

spectrophotometric transmittance SRMs and for the recalibration of SRM gas

mixtures

.

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

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

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

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

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

is performed via a purchase order.

During the first 11 months of FY85, CAC staff provided analyses or recalibrations for some 130 requests at a cost of $290,200. These requests

and their associated funding were divided among the three categories of

customers as follows: NBS - 29 jobs ($77,200); other government agencies

- 28 jobs ($1 31,600); and private industry - 73 jobs ($81,400).

Other government agencies continue to be the largest user (on a funding

basis) of our analytical services. It is also noteworthy that there was a significant increase in the number of NBS requests during FY85; this increase

was in sharp contrast to the slow but steady decline that has been observed

for in-house requests over the past five or six years.

R. W. Burke and M. V. Smith

21
II. Inorganic Analytical Research Division

James R. DeVoe, Chief

Barry I. Diamondstone , Deputy Chief

A. Division Overview

The Inorganic Analytical Research Division conducts research that is

directed toward improving the accuracy of compositional measurements of inorganic constituents in a variety of materials. This research takes the form

of basic studies on new principles of chemical analysis as well as improvements to existing methods. In addition, the Division uses accurate methods

to certify Standard Reference Materials, to provide analytical services for

other government agencies and to provide analytical support for solving problems related to national needs. The Division is organized into four Groups

which are oriented to specific technical disciplines. The Groups are: Analytical Mass Spectrometry, Atomic and Molecular Spectrometry,

Electroanalytical Research, and Nuclear Methods.

We believe that, in order to increase our expertise in certification

capability, developmental research pursuant to the preparation and certification of SRMs should be significantly increased. The developmental effort can

take many forms. For example, there is a need to investigate exhaustively

the reason for analytical biases. More time should be taken to study the

process by which a new reference material is made, and to design carefully

homogeneity testing particularly when element specific problems are sus- pected. We have established the concept of a technical champion who is re- sponsible for the scientific considerations associated with the fabrication

and certification of an SRM. This person works with the coordinator for the

Division and the Office of Standard Reference Materials. We also need to

investigate methodology for certain elements or group of elements sometimes

associated with a particular material or group of materials. For example,

the analysis of gases in metals is an area where considerable effort must be

placed in order to provide a high level of accuracy. Quite often, special

dissolution techniques must be developed in order to be assured that the

sample is totally decomposed to the solvated ion. These and others need

immediate attention.

There have been significant advances in the developmental research area

this past year, and some of these can be read in the various reports to follow. Several have not been included but are of equal importance. For example, progress has been made toward automating some of the radioactive sample

handling for activation analysis. Isotope dilution mass spectrometric methods (IDMS) have been developed for selenium which is the sulfur analog that won an IR-100 award last year. A fast neutron activation analysis method has

been developed for minor and trace amounts of silicon which is difficult to

analyze by other methods. Good progress has been made on the reinstitution

of voltammetry for the certification of SRMs. We are very pleased that a third IR-100 award has been received (within the last two years) by a member

of our Division. Ronald W. Shideler has won this latest one for his design

of a parametric amplifier which has extremely low noise and high input sensitivity. The design concept is currently being evaluated by instrument

manufacturers.

22
In addition, developmental projects have supported other agencies as evidenced by the fact that we have developed a method for the direct collection and injection of aerosols into an inductively coupled plasma. We were

the initiators of an ASTM task group on Nuclear Methods of Chemical Analysis.

We have established a multi-agency program involving the Food and Drug Administration, Department of Agriculture, and International Atomic Energy Agency

to develop methodology for the trace element analysis of foods. We have

analyzed for the EPA, several series of secondary water reference materials

containing trace elements.

The analysis of SRMs continues to occupy a major part of our effort. We

have begun to implement a laboratory data management system by incorporating

many of our reports of analysis for the certification of SRMs over the past

years. This database is expected to provide much improved information on previous methods used for certification, agreement between methods, etc.

This past year, we have carefully studied our role in this program and

believe that we can contribute in all areas of standards development.

We have had a good year in research. There are a number of studies in

addition to those described in the reports to follow. For example, in collaboration with the Organic Analytical Research Division, it has been found

possible to identify the presence of phospho- proteins in 2-dimensional electrophoresis layers by autoradiography. Neutron depth profiling continues to

reveal new surface properties of materials with the completed study of

helium-3 transport in nickel. This study may lead to understanding of how

gases migrate through metals and change structural characteristics. Initial

results on the IDMS measurements of carbon dioxide show accuracies to better

than one part per thousand. Our initial research in aqueous electrolyte

conductance has provided impetus to begin experimental studies preparatory to

the certification of an SRM.

During this past year, the Division has continued to have excellent

collaboration with many guest workers and research associates. This provides

us with added stimulation from exposure to new ideas.

Our future plans involve consolidating our research ideas into areas in

which significant funding can generate an effort that can be most effective.

This means that group element separations and preconcentration techniques

utilizing robotics and automation will be investigated in most of the Groups

within the Division. Chemical dissolution techniques which have been long

neglected should now be reexamined in the light of new technology which is

available for measuring the efficacy of the methods. Other plans include

development of a cold neutron source for neutron depth profiling and prompt

gamma activation analysis, resonance ionization mass spectrometry for studying sputter atomization and time-of-flight processes, ion optics in mass spectrometry, material transport and new atom reservoir design in atomic

spectroscopy and generation of new basic considerations for standardization

of pH.

1 . Analytical Mass Spectrometry Group; Overview

The Analytical Mass Spectrometry Group develops and maintains the

capabilities required to perform compositional measurements using the analytical sciences of chemical separation and mass spectrometry. For many years,

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

and accurate isotope ratio measurements required to determine the atomic

23
weights of the elements and to make very accurate measurements of trace

element concentrations. While maintaining the basic thrust in the traditional areas, the horizons of the Group have broadened markedly in the past

few years. Predicated on the competence building program in ionization

mechanisms and related basic research, substantial changes have been initiated to develop new capabilities for chemical separations and ion spectroscopy. By combining the foundation evolved from many years of measurement

research and applications with the recently initiated fundamental changes

described below, we anticipate that a new generation of measurement

capabilities for analytical mass spectrometry and compositional analysis will

be achieved.

Rapid progress in the ionization mechanisms competence building program

has accelerated the maturation of resonance ionization mass spectrometry

(RIMS) as a major new analytical tool for elemental and isotopic analysis.

Accordingly, this competence will be brought into the mainstream of analytical research and development within the Center during the next year. During

the past year, efforts in this area have focused on the auto-ionizing states

of magnesium in collaboration with researchers in the Center for Radiation

Research, design and construction of an instrument for ion bombardment and

laser ablation studies of solids, preparation for multicomponent isotope

dilution analysis, studies of osmium and rhenium resonance ionization and

spectroscopy, and the study of time-resolved magnetic dispersion mass spectrometry to improve isotopic selectivity measurements.

Building upon the IR-100 award-winning sulfur work of last year, the

thermal formation of arsenic-containing molecular ions has been extended to

include selenium as the AsSe

+ ion, which has been used successfully with

newly developed chemical separations to determine trace selenium in SRMs

using isotope dilution mass spectrometry. Utilizing negative ion mass spectrometry and the BO^ ion, a method has been developed in collaboration with

Dr. Heinz Zeininger to determine boron concentrations at the sub-ppm level.

We are most pleased to announce that Ronald W. Shideler has been awarded

one of the highly competitive IR-100 awards for his development of the NBS

parametric amplifier electrometer (see Technical Report 12). This amplifier

provides significant improvement in signal-to-noise ratio over others that we have used. It is currently being installed on mass spectrometers in our laboratory and we have (ICP-MS) requests from others as well.

An inductively coupled plasma mass spectrometer has been acquired,

installed and its performance characteristics demonstrated at solution detection limits of 0.1 ppb and isotope ratio precisions of 0 . 25 %, RSD for

selected elements. Although there are still a few start-up problems to

resolve, this technology appears to offer potential as a cost-effective means

to provide the analytical reliability inherent in isotope dilution mass spectrometry.

A wide variety of analytical services has been provided to other

government agencies and private sector businesses. Examples of these outputs

are participation in the international lead isotope tracer experiment in

Turin, Italy, elemental and isotopic analyses of boron and chlorine in

nuclear reprocessing plant construction materials, and in collaboration with

DuPont an assay of trace element contamination in fluorocarbon polymers used

in the semiconductor industry. In addition to these services, the Group has

24
carried a much larger component of SRM analyses this past year, providing

high accuracy trace element analysis using isotope dilution mass spectrometry

.

Research plans for next year include the investigation of robotics

applications in the chemical separations laboratory, development of microwave

dissolution and automated separations, diagnostic and analytical studies of

ion bombardment and laser ablation of solids, modeling studies of continuous

and pulsed ion transport and manipulation in electric and magnetic fields,

thermal formation of negative ions, and metal speciation and isotope dilution

studies using the ICP-MS. Sufficient progress has been made on the chemical

assay and isotopic analysis of nickel that we anticipate completion of the

atomic weight and absolute isotope abundance measurements during next year.

Also next year a study, funded by the Electric Power Research Institute, of

the feasibility of using rare earth element stable isotopes as surrogate

tracers to follow the path of coal fired power plant sulfur emissions will be

initiated.

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

Bowman, III, Karen A. Brletic, Courtney A. Clements, Emile C. Deal, Jack D.

Fassett, John W. Gramlich, Scott A. Hotes, Lois B. Jassie, W. Robert Kelly,

Howard M. Kingston, George M. Lambert, Larry A. Machlan, John R. Moody,

Thomas J. Murphy, Paul J. Paulsen, Lura J. Powell, Ronald W. Shideler,

Heinz Zeininger, and Richard J. Walker.

2 . Atomic and Molecular Spectrometry Group: Overview

The principal objectives of the Atomic and Molecular Spectrometry Group

are to conduct research in the fundamental processes associated with analytical atomic spectroscopy, to conduct developmental research on methodology

using existing analytical spectroscopies, to evaluate all types of errors,

and to apply the results of these efforts to the certification of Standard

Reference Materials and to the publication of technical results.

In July a few changes were made in the organizational structure of the

Group. The Laser Analytical Chemistry Group was combined with this Group. In

order to more effectively carry out our major program in certification of

Standard Reference Materials, T. Rains returned to the laboratory and will

continue to provide assistance to the Group via his many contacts in the

field of atomic absorption spectroscopy. The Group is temporarily headed by

the Division Chief.

The characterization of Standard Reference Materials and the analysis of

highly complex samples from other government agencies as well as other Divisions at NBS via the service analysis program comprise major areas of effort

within the Group. A few of the accomplishments using the techniques of the

Group include the characterization of major, minor and trace elements in 55

SRMs which include matrices listed in Technical Report 28. The recently

released nine Aqueous Spectrometric Standard Solutions are being widely

accepted by instrument manufacturers, supply houses, service and research

laboratories. At present, this series of SRMs provides standard solutions

for 36 elements.

25
One of our Group members (R. L. Watters, Jr.) co-chaired a conference on chemometrics held at NBS. This conference was unique in bringing statisticians together with chemists in a forum in which the impact of research in

statistics and probability on research in chemistry could be discussed. The

proceedings of the conference will be published in a special issue of the NBS

Journal of Research.

Research on material transport via the spark discharge revealed a previously unrecognized phenomenon. It appears that the atomic composition of

the vapor from which optical emission signals are produced is not representative of the bulk composition. The vapor is enriched in the more volatile

component and is depleted in the less volatile one. More studies need to be

performed in order to determine if this is a prevalent phenomenon among a number of materials. If this is the case, the accuracy of spark-inductively

coupled emission plasma systems may have to be reevaluated.

The NBS-developed laser enhanced ionization (LEI) technique has evolved

into a more routine chemical analysis system, and was used for the analysis

of several Standard Reference Materials. In addition, a computer controlled

two-wavelength calibrated instrument was developed to further enhance the

accuracy of the method by utilizing the resultant three dimensionality of the

data

.

The Group now contains the necessary expertise to automate most types of

instruments by interfacing to microcomputers. Several projects are already

underway including an automated chemical separator for the alkali metals.

Collaborative research is proceeding well in the Group. This past year

we have instituted research projects with the following: Dr. C. Spiegelman,

Center for Applied Mathematics, with Dr. R. Watters, Jr., on the statistical

interpretation of calibration curve data; Dr. L. Moore, Analytical Mass Spectrometry Group with Dr. J. Travis on the mechanism of laser ionization in the source of a mass spectrometer; Dr. K. Mielenz, Radiometric Physics Division

with Dr. R. Mavrodineanu on the development of spectrophotometric standards;

Prof. A. Syty, Indiana University of Pennsylvania, and R. Christensen, Liquid

Chromatography Group, with T. Rains on the combination of liquid chromatography with atomic absorption spectroscopy; Dr. L. Moore, Analytical Mass

Spectrometry Group ( IARD) , with F. Ruegg on the development of an interface

for a transient digitizer with a microcomputer for high speed readout; Dr. N. Valette-Silver , Carnegie Institute of Washington, with Dr. R. Watters, Jr., on the trace element analysis of deep oceanic springs; and Dr. B. Davis, EPA,

with T. Rains on the use of atomic absorption spectroscopy for the analysis

of residues from chemical waste disposal. In addition, we have had a number

of Chinese guest workers who have spent from one to two years with us.

The type of work performed for other government agencies has varied from

method development to the analysis of a variety of materials that are to be

used as secondary standards. The level of effort which goes into these materials is frequently equivalent to that used for the certification of Standard

Reference Materials. When this is the case, every effort is made to arrange

for the material to be treated as an SRM. We are now characterizing

micrometer-sized spheres of glass (inorganic-ion doped) with the goal of producing an SRM to calibrate microspectrofluorimeters. Such an SRM, with suitable stability and spectral characteristics, will be extremely useful in the

standardization of fluorescence-tagging procedures used in medical research.

26
The gases in metals program is progressing well, but is limited in available

diagnostic studies that can measure systematic error in the measurement process. Alternate methodology such as manometric measurement of fixed volumes,

qualitative identification of gaseous mixtures, and totally different methods

such as neutron activation analysis will be studied.

Development of transmittance filters for spectrophotometers has

progressed well. The stray light problem which existed for some spectrometers in the past has been corrected by design changes incorporated by the

manuf acturers . Future developments which are described below will be coor- dinated with the manufacturers, concurrently with the filters development,

so that technical problems with the standard can be minimized.

Spark optical emission spectroscopy which is the mainstay for

homogeneity testing of all SRMs continues to provide excellent results. The

statistical analysis program which is used on all of the spectroscopic data

will be rewritten this next year to improve its overall capability and to

consolidate the processing thereby reducing the cost of analysis.

James R. DeVoe, Acting Group Leader; Robert W. Burke, Therese A. Butler,

Barry I. Diamondstone , Michael S. Epstein, Robert C. Gauer, Radu

Mavrodineanu, De M. Mo, John A. Norris, Theodore C. Rains, Fillmer C. Ruegg,

Teresa A. Rush, R. L. Sams, Melody V. Smith, John C. Travis, Gregory C. Turk,

J. Nathalie Valette-Silver , Thomas W. Vetter, Robert L. Watters, Jr., Jesse

Wen, and Yang Z. Zhang

3. Electroanaly tical Research Group: Overview

The Electroanalytical Research Group conducts basic research and

utilizes electrochemical principles to develop new techniques, to improve

existing techniques, and to apply them to chemical analyses. The techniques

in practice include amperometry, conductimetry , coulometry, ion chromatography, polarography , potentiometry , and voltammetry. Research activities

are directed toward attaining a more thorough understanding of the complex

electrochemical systems encountered in the development and implementation of

electroanalytical methods.

A major project in this past year has been the development, production,

and analysis of a Standard Reference Material for acid rain analyses, (SRM

2694, Simulated Rainwater). The primary goal of this material is to provide

a control standard for pH measurements in rainwater, which will compensate

for residual liquid junction potential, thereby minimizing a major source of

bias in this critically important measurement. This material represents the

first issuance of a matrix-specific pH standard by the National Bureau of

Standards. This material is also the first SRM certified for aqueous electrolytic conductance, albeit not a high-accuracy standard. In addition, the

SRM is certified for trace anions, and for trace alkali, alkaline earth and

ammonium ions, representing another first in the SRM program. Problems with

the stability of the ammonium ion have recently been discovered, and research

has been initiated to determine the cause and to identify and implement an appropriate correction. Research must also be conducted to develop a new generation of storage container, one which h$s the inertness and freedom from

contamination of fluorocarbons or polyethylene, but without the transpiration

27
problems of these materials. This work is essential to this project and to

other projects in the division requiring long-term storage of dilute aqueous

solutions

.

A joint project was conducted with Robert C. Paule, statistical

consultant to the National Measurement Laboratory and ASTM. This project was

a statistical ruggedness test of a procedure for pH measurements in rainwater, in which several selected parameters were varied in order to determine

and quantify their individual and interactive effects on the measurement. The

parameters were stirring, temperature, immersion depth, addition of neutral

salts, dilution, and equilibration time. Of these, the factors which have

the greatest effects, (and hence must be carefully controlled), are stirring

and addition of neutral salts. Based on these results, a recommended procedure for pH measurements in rainwater is included as part of the "Certificate

of Analysis" of SRM 2694 and has been submitted to ASTM for acceptance as a standard method. A complete report of the ruggedness test is being

published.

Voltammetry is becoming a viable analytical tool within the Group with

the successful demonstration of anodic stripping voltammetry (ASV) directed

toward the determination of copper, cadmium and lead in SRM 1643a, Trace

Elements in Water, and of differential pulse polarography toward the determination of copper and zinc in SRM 1577a, Bovine Liver. A most notable advance

in the precision and accuracy of ASV was achieved through the use of indium

(III) as an internal standard. This is the first use of an internal standard

in ASV, and aids the determination by taking into account and correcting for

variations in mass transport to the electrode during the plating step.

Research in conductance has continued this year. Dr. Walter J. Hamer

has contributed to this effort by providing a thorough review of this discipline and by recalculating the historical and widely accepted values of the

specific conductance of select concentrations of potassium chloride on the

basis of the currently adopted fundamental constants, base units, and atomic

weights. Instrumentation for temperature control and measurement, critical

to high accuracy conductance measurements, is now operational. Commercially

manufactured two-electrode conductance cells have been purchased and tested.

Still to be acquired is a Jones Bridge. Next year, in collaboration with the

Office of National Measures of Hungary, it is intended to develop the working

basis for a high accuracy SRM for aqueous electrolytic conductance. Longer

term research involves the development of a four- terminal cell (with an adjustable cell constant), and, in conjunction with the Electricity Division

and the Electrosystems Division, the development of a new generation of con- ductance measurement instrumentation. The ultimate goal of this research is

to link the conductance measurement to basic metrology.

Research in ion chromatography was active on several fronts, most

notably in improving the precision and accuracy of the advanced instrumentation purchased the previous year. This effort, aided by the Dionex Corporation, led to the development by Dionex of a substantial improvement in their

anion separator columns and to a better understanding of the various factors

affecting peak shapes, retention times, and linearity of response. The capability for cation determinations was demonstrated via SRM 2694, Simulated

Rainwater. Research in ion chromatography with amperometric detection was highlighted by improvements in the determination of ultra-trace (sub-ppb)

concentrations of sulfide (see below), and by improvements in the

28
determination of trace iodide in difficult matrices, such as table salt and

cadmium sulfide. A project to develop a rapid method for the accurate determination of fluoride in vegetation is in progress. A new data acquisition

device has been acquired for the advanced ion chromatograph and is being

implemented.

Based on high accuracy potentiometric measurements, the thermodynamic

properties of DC1 in D

2 0 and of phthalic acid in D

2

0, including the first and

second dissociation constants, have been evaluated, and submitted for

publ ication.

The Electroanalytical Research Group continues to expand its resources

and scope of research through active use of the guest worker program, and

industrial, international, and academic collaborations. Two scientists from

the National Office of Measures of Hungary have visited for one month each to

exchange information on pH and conductance measurements and research. The

Group maintains its involvement with ASTM and NCCLS through participation in

meetings and task groups, and is active in Task Group D (Monitoring) of the

National Acid Precipitation Assessment Program.

Research in pH will continue as a long-term commitment to provide

reliable and thermodynamically significant measurements and standards in this

most widely used analytical parameter. The development of a series of

matrix-specific pH standards is a high priority. Investigations of aqueous

conductance will continue; advancements in ion chromatography will be

explored. Voltammetry will be used extensively as a valuable analytical

research technique within the Group. Flow-injection analysis with electrochemical detection will be implemented for determinations of trace metals in

complex matrices.

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

Pratt, Jr., Melissa Knoerdel, Lisa A. Holland, and Han Kai

4 . Nuclear Methods Group; Overview

The development and application of nuclear analytical techniques for

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

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

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

Group has a unique capability in neutron beam analysis 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 four techniques

provide an arsenal of tools to address a wide variety of analytical problems

in science and technology.

The activities during the past year have been dominated by the upgrade

of the NBS Research Reactor (NBSR) to an operating power of 20 MW from its

previous 10 MW level. The power increase and the associated repositioning of

the irradiation tubes resulted in the NBSR being shut down during the first

half of the year and required a total recharacterization of our irradiation

facilities. The reactor characterization has been completed and the Group'.

29
irradiation capability has been significantly improved. The result has been

a doubling of the neutron flux available for both our beam and in-core

measurements, and for the nearly-installed cold neutron source.

With the NBSR unavailable for use for the first half of the year, we had

the opportunity to gain experience with other reactors. The ability to irradiate large samples in a well-thermalized neutron flux made the MIT reactor

the facility of choice for bioanalytical measurements, especially for the

activation of whole electrophoresis gels. The nearby light-water reactors at

the University of Maryland (College Park) and the University of Virginia

(Charlottesville) were used for a variety of irradiations. The relatively

high fast-to- thermal neutron flux ratio at these latter two facilities made

epithermal and fast neutron activation analysis convenient, especially for

iodine and silicon.

Radiochemical neutron activation analysis continues to make significant

contributions to the Group’s measurement capability. The determination of

tin in the milk powder, wheat flour and rice flour SRMs at the few ng/g level

and the determination of gold and platinum in the human urine SRM at the few

pg/mL level are examples of this work. The determination of platinum, in

particular, at environmental baseline levels means that this important element can be added to the list of those which can be monitored in real

samples

.

Largely at the instigation of the Group's members, a new ASTM task group

on Nuclear Methods of Chemical Analysis (El 0.05. 12) has been formed to insure

that the ASTM standards in this area reflect the current state of the art and

to enhance communication within this community. After three meetings, the

task group has over forty members and six active subgroups: Quality Assurance, Biology Medicine and Health, Geochemistry and Archeometry, Reactors,

Neutron Generators, and Forensic Applications.

The Group's collaborative research with industry and other government

agencies continues to increase. Thirteen f luoropolymer materials were ana- lyzed for over twenty elements for Dupont, and a series of high purity quartz

samples were analyzed for Fort Monmouth. Our research in neutron depth profiling continues to enjoy a strong interaction with U.S. industry on the

measurement of elemental distributions in high-technology materials. In

addition to our ongoing bio-analytical collaborations with NOAA, NIH, USDA

and FDA, a new IAEA program in nutritional monitoring of the human diet has

been initiated jointly with FDA and USDA.

The National Environmental Specimen Bank, which in prior years has been

devoted solely to a pilot program of collecting, analyzing and banking human

liver samples under EPA sponsorship, has expanded this year to include several new sample types. Preliminary banking has begun on honey bee samples

from EPA and on the USDA/FDA human diet samples. In collaboration with the

NOAA National Status and Trends program, samples of marine sediment and fish

liver and muscle are being banked. A goal for the coming year is the

development of one or more of these materials as standard reference

materials.

The past year has seen a major upgrade in our detection and data

analysis capability. A second front-end detector system (ND 6700) has been

installed for low level counting with two new germanium detectors. A

30
duplicate ND 6620 counting system with an automated sample changer has been

obtained for the analysis of the diet samples in the nutritional program. The

VAX computer is now fully operational for data acquisition with its own sample changer. The addition of this improved data acquisition and computational capability for modeling the measurement process will continue to

enhance our accuracy and throughput for activation analysis.

During the coming year, the Group will continue to consolidate the

development of its data acquisition and computation capability and to apply

nuclear methods to elements which are not done well presently. These new elements will include nickel, silicon and iodine by fast or epithermal NAA,

nitrogen and phosphorus by thermal NAA with beta counting, and lithium and

boron by a relatively new technique, neutron activation mass spectrometry.

In addition to the ongoing application programs, work will continue in reducing and quantifying the various sources of systematic error in analysis by

nuclear methods.

Ronald F. Fleming, Group Leader; M. James Blackman, Donald A. Becker, B. Stephen Carpenter, R. Gregory Downing, Kathleen A. Fitzpatrick, Robert R. Greenberg, G. Venkatesh Iyengar, John K. Langland, Richard M. Lindstrom,

George J. Lutz, John T. Maki, Bruce R. Norman, Susan F. Stone, and Rolf L.

Zeisler

31
B. Selected Technical Reports

(Inorganic Analytical Research Division)

1 . Three-Dimensional Atomic Spectra in Flames Using Stepwise Excitation

Laser-Enhanced Ionization Spectroscopy

G. C. Turk, F. C. Ruegg, J. C. Travis, and J. R. DeVoe

The collisional ionization of the excited state atoms produced by laserexcitation in a flame forms the basis of the spectroscopic method called

laser-enhanced ionization (LEI). Among the variety of modes of laser excitation which have been used, the technique called stepwise excitation offers

significant advantages in both sensitivity and selectivity. Stepwise excitation is a double resonance method which utilizes two independently tunable

synchronized pulsed dye lasers. In the most common situation, the first

laser excites the analyte atoms from the ground state to some intermediate

excited state, and the second laser further excites these atoms from the

intermediate level to a higher level. Since collisional ionization rates

from excited states increase exponentially as the ionization energy is

approached, sensitivity is enhanced.

Previously, stepwise excitation LEI spectra have been recorded by scan- ning one of the lasers while the other laser was kept fixed on the resonance

wavelength. We have now developed a computer controlled LEI spectrometer

which is capable of measuring and storing LEI signals while scanning both

laser wavelengths. The result is a three-dimensional LEI spectrum — first

step wavelength vs. second step wavelength vs LEI signal amplitude. When

plotted as a 3“D projection or as a contour, features are revealed which have

not previously been observed.

The wavelength drives of both lasers are stepper motor-controlled by a 16 bit microcomputer which also collects and stores the LEI signal output

from a gated integrator. In addition, the computer calculates the wavelength

of the lasers by analyzing the fringe pattern of a Fizeau interferometer

which is projected on a photodiode array interfaced with the computer. This assures accurate wavelength axes of the spectrum.

The most interesting feature which has been revealed is a diagonal ridge

which corresponds to the points where the sum of the energies of the two

wavelengths equal that of the upper energy level. This ridge represents a two-photon transition, which is resonantly enhanced by the intermediate

level. Unlike the typical two-photon transition, the two photons in this

situation are of different wavelengths. This diagonal ridge feature is very

difficult to observe without measuring the 3 -D spectrum, and can be quite

confusing when encountered in complex samples containing many elements. The

new system will be utilized to verify the spectral purity of analysis lines

for samples being analyzed by LEI spectrometry.

32
2 . Evaluation of Several Pulsed Dye Lasers as Excitation Sources for Flame

Atomic Fluorescence Spectrometry

M. S. Epstein, J. C. Travis, and G. C. Turk

The sensitivity, precision, and accuracy of spectrochemical methods of

analysis are the f igures-of-merit which determine their usefulness for quantitative analytical measurements. In Laser-Excited Atomic Fluorescence Spectrometry (LEAFS), these f igures-of-merit are primarily determined by the

characteristics of the laser source used for excitation. For pulsed lasers,

such characteristics are the peak power (kW), the temporal pulse width (ns),

the spectral bandwidth (nm), and the repetition rate (Hz). Since the pertinent characteristics of tunable dye lasers vary significantly, we have

investigated the performance of Nd: YAG-laser-pumped and Cu-vapor-laser pumped

dye lasers as excitation sources for LEAFS. The study included evaluation of

detection limits, calibration linearity, noise sources, and accuracy in real

sample analysis. Results were compared to previous investigations of these

parameters using a flashlamp-pumped dye laser.

Non-resonance transitions of iron (296.690/373.487 nm) and nickel

( 300. 249/~342 nm) were used in the study. Fluorescence was measured in an argon-separated air-acetylene flame using a 0.1 m monochromator and boxcar

integrator detection system. Detection limits for the Nd:YAG laser were approximately 2 orders of magnitude poorer than those obtained with the Cuvapor laser; the latter were essentially equivalent to those from the

flashlamp-pumped dye laser. This was a result of scattered light/background

fluorescence noise sources which limited detection using the Nd:YAG laser

source. The high peak power of the Nd:YAG laser caused saturation of the

fluorescence transitions which magnified the effect of these noise sources.

Beam expansion to reduce the laser intensity below the saturation region did

not improve detection limits significantly and magnified the effect of source flicker on the analyte flicker noise.

Detection limits using the Cu-vapor laser were defined by a combination

of radio-frequency noise and photomultiplier shot noise. The high repetition

rate (5 KHz) of this laser reduced the effect of source flicker noise to the

extent that the relative standard deviation for concentrations significantly

higher than the detection limit was less than 1%.

The determination of nickel in SRM 1645 (River Sediment) using LEAFS

required background correction to compensate for background fluorescence

induced by wing excitation of iron transitions lying near to the nickel resonance line. Analytical results agreed closely with the certified value.

This study illustrates the major concepts to be considered in choosing a laser system for LEAFS. The Cu-vapor laser appears to be the ideal excitation source for LEAFS, particularly if radio-frequency noise can be reduced.

The high repetition rate makes it ideal for continuous atomization sources,

such as the flame, where high precision can be obtained, as well as for transient atomization sources, such as electrothermal atomizers and gas generation systems. The application of the Cu-vapor-laser-pumped dye laser to

these dynamic atomizers will be investigated in the future.

33
3 . Determination of Cr(VI) in Natural Waters by LC/AAS after Separation and

Preconcentration

A. Syty, R. G. Christensen, and T. C. Rains

Chromium is an element of considerable environmental significance and

exists in solution predominantly in +3 and +6 oxidation states. Hexavalent

chromium is considered to be toxic because of its oxidizing potential,

whereas, trivalent chromium is an essential micronutrient required for maintenance of normal glucose tolerance. Hexavalent chromium finds its way into

natural waters chiefly from industrial effluents, such as electroplating and

tanning industries, from dyeing operations, as teachings from sanitary land

fills, and from water cooling towers. With current maximum concentration of

Cr(VI) of 50 ng/mL permitted in potable water, the goal of this work was to

develop a rapid and accurate method for the determination of Cr(VI) in

natural waters.

In order to improve the sensitivity of chromium analysis, several

preconcentration approaches have been used in the past. These include coprecipitation, solvent extraction, ion exchange, and thin-layer, gas, and

adsorption chromatography. All of these methods of preconcentration introduce additional labor-intensive and time-consuming sample manipulation steps

into the analysis, and are subject to all the attendant sources of variability. The method developed here utilizes a rapid on-line chromatographic preconcentration technique coupled with a flame atomic absorption spectrometer

(AAS) as the detector. The sample of natural water is treated with tetrabutyl-ammonium phosphate, an ion-pairing agent, and then pumped through a C^g

bonded silica column. The Cr(VI) is selectively preconcentrated on the

column while Cr(III) passes through unretained. By switching to a 50/50

methanol/water solvent, the Cr(VI) is rapidly eluted from the column which

produces a sharp peak with the AAS instrument.

With a short 4-cm column the preconcentration or trace enrichment factor

is about 10, while the 25~cm long column gave an enrichment factor of 300. A

detection limit of 0.8 ng/mL was obtained using a 25-cm column and a flame

AAS as the detector.

Samples of NBS pond water were collected in early spring and in late

spring when the organic content of the water was very high. Cr(VI) could not

be detected in either sample [Cr(VI) < 1 ng/mL]. As a check of the recovery

of the method, each sample was spiked with varying amounts of Cr(VI) and

Cr(III). When these samples were analyzed on the same day of spiking, com- plete recovery of the Cr(VI) was obtained. After one day of standing, the

recovery of Cr(VI) was 80 to 85 percent with a corresponding increase in the

Cr(III) concentration. In all cases, the rate of Cr(VI) reduction was higher

in the water collected in late spring than in water collected earlier.

Future directions for this project include application of the method for

the determination of Cr(VI) in a variety of fresh and saline waters. In

addition, the general technique will be tested as a means of preconcentration

of other ions in aqueous systems. A further modification of the method would

be the use of electrothermal atomization AAS to improve its detection limits.

34
4. Development of an SRM to Calibrate Microspec trof luorimeters

M. Epstein, R. Velapoldi, and D. Blackburn

A joint program involving the National Bureau of Standards and the Food

and Drug Administration is concerned with the development of standards for

the calibration of mi crospectrof luorimeters used for the quantitative measurement of immunofluorescence of species tagged with fluorescein isothiocyanate (FITC) . Research at NBS is being performed using a Leitz MPV3 microspectrofluorimeter modified by the addition of a 0.25 m scanning emission

monochromator and a N

2 -laser-pumped dye laser excitation source. Several

approaches are being investigated:

(a) Inorganic Ion Doped Glass Microspheres

Small spheres of glass ( < 20 ym diameter) doped with Mn, U, Tb , or Nd

ions have been prepared by flowing crushed glass particles through a high

temperature furnace. These spheres are homogeneous and exhibit the theoretical (diameter)^ proportionality to fluorescence intensity when excited via

epi-illumination in a microspectrofluorimeter . Ideally, in order for these

standards to be useful to the clinical laboratory, they should mimic the

excitation and emission spectra of FITC. Of the several glass compositions

investigated, only uranyl glass exhibits a fluorescence intensity (with excitation in the 450-490 nm wavelength range) and an emission spectrum identical to FITC. The excitation maximum, however, is at 423 nm rather than at

the 490 nm maximum observed for FITC, possibly limiting the use of these

glass spheres as absolute intensity standards for FITC measurements without

prior calibration against a stable FITC standard on the user’s microscope.

Excitation bandpass and source spectra may vary significantly between different microscopes, resulting in varying intensity ratios between the glass

and FITC. Nevertheless, the glass microspheres should be quite useful as general purpose standards, both as a source of corrected spectra and as a measure of instrument stability.

(b) FITC Doped Latex Microspheres

Since a relatively stable FITC standard is required for initial

calibration of the uranyl glass microspheres on the user’s microscope, we are currently studying commercially produced latex microspheres with a surface

coating of FITC. These spheres exhibit rapid fading of fluorescence intensity under continuous irradiation, but are relatively stable under

nanosecond-pulse laser irradiation. We are attempting to develop a methodology to stabilize these standards for short periods of time to make them useful for calibration of the uranyl glass microspheres. The latter may then be

used for long term calibration purposes.

5. Spectrometric Analysis of Spark-Generated Aerosols

R. L. Watters, Jr., T. C. Rains, M. S. Epstein, and G. C. Turk

Analytical techniques such as inductively coupled plasma (ICP) and

atomic absorption spectrometry (AAS) are usually applied to the analysis of

liquid samples or solid samples that have been dissolved. Over the past several years there has been increased interest in developing direct solid

sample introduction systems for use with these techniques. We have beer.

35
studying the use of a spark discharge as a sampling device for ICP spectrometry. Although this technique has shown promise, it does not presently

exhibit the accuracy needed for the analysis of Standard Reference Materials

(SRMs). In order to study further the sampling processes of the spark

discharge, we have examined the physical characteristics and chemical

composition of aerosols produced by sparking certain SRMs.

The preliminary results for brass SRMs, reported in the 1984 Annual

Report, indicated systematic errors in the Zn/Cu ratios for aerosols produced

by the spark and collected on coarse and fine filter media. This year we have verified these results and have shown that although there are differences between the SRM Zn/Cu ratios and the aerosol Zn/Cu ratios, the aerosol

ratios fall on a linear calibration curve for the series of 6 SRMs. Furthermore, the aerosol Zn/Cu ratio for a given material is a function of spark

repetition rate and peak discharge current.

We have extended these measurements to include the determination of Mn,

Cu, Cr, Ni, and Mo ratios to Fe in a number of ferrous SRMs and have found

similar systematic errors in aerosol composition. In general, more refractory elements, such as Mo, are depleted in the aerosol, and others, such as Mn and Cu, are concentrated in the aerosol, when compared to their respective concentrations in the bulk sample. The successful applications of

spark-ICP spectrometry for the analysis of metals, which have been previously

reported, have therefore depended on the calibration process of the spark-ICP

spectrometer system to normalize this sampling bias.

As a further extension of this work, we have examined the feasibility of

making real-time measurements of metal aerosols in air using both ICP and AAS

techniques. Low concentrations of Fe in aerosols were generated by sparking

the same set of brass SRMs that contain certified trace amounts of Fe. The

aerosol was carried in the argon stream from the spark chamber to the sample

input of the ICP torch or the AAS flame. Although the fractional amount of

Fe in the aerosol is likely to be different than the certified concentration

of the sampled material, satisfactory calibration curves for Fe were obtained

using ICP and AAS detection. The expected systematic error due to bias in

the Fe aerosol concentration compared to the SRM value is 20$. The detection

limit for Fe in a stream of argon was found to be 0.002 pg/L.

The effects of ICP input power, observation height in the plasma, and

air/argon gas mixtures were used to optimize the response for Fe in a stream

of air. The sample aerosol was produced by solution nebulization in this

case. One of the most critical parameters of the system is the physical

geometry of the plasma torch. With a specially designed low-flow torch, the

best sensitivity for Fe in air was obtained using an rf power of only 1.5 kW.

Ambient air was sampled by a regenerative blower and forced into the plasma.

The same approach was used to introduce the aerosol into the AAS flame.

Calibration curves were obtained as before using spark sampling of the series

of brass SRMs and placing the outlet from the spark chamber near the blower

inlet. Linear calibration curves and a detection limit of better than 0.01

pg/L were obtained for Fe in air using either the ICP or AAS.

Aerosol characterization work will continue for solid samples other than

ferrous materials. Calibration of the ICP or AAS systems for the analysis of

aerosols in air will be studied using a conventional solution nebulization

36
system and a desolvation apparatus to produce dry aerosol. The output characteristics of this aerosol generation system will be measured by total collection of the analyte on filters. The collected aerosol will be dissolved

and analyzed by conventional ICP or AAS. This system will eliminate changes

in the calibration curve caused by the presence of argon in the sample

stream.

6. Resonant Laser-Induced Ionization of Atoms in an Inductively-Coupled

Plasma

G. C. Turk and R. L. Watters, Jr.

The use of tunable dye laser radiation to selectively ionize atoms in an inductively coupled argon plasma (ICP) has been investigated. Our objective

in this research was to determine if the method of laser-enhanced ionization

(LEI) spectrometry, which normally utilizes a flame as an atomization source,

could be applied to the ICP. If successful, the adaptation of LEI to the ICP

would have the benefit of an environment which has been demonstrated to be

less susceptible to many of the chemical interferences encountered in flamebased spectroscopic methods. In addition, this application may prove to be an effective mechanistic probe for elucidating excitation and collisional

processes in the ICP.

Laser induced enhanced ionization was measured as an increase in current

between biased electrodes on either side of the laser irradiated volume of

the ICP. Interaction between the radio-frequency plasma and the detection

circuitry required that an extended ICP torch be used with the electrodes

placed 19 cm above the load coil. This is well above the observation zone

used in ICP emission spectroscopy and the atom population is much lower. As

a consequence, the sensitivity of the measurement was found to be unsuitable

for analytical application, but was found to be sufficient for some diagnostic studies. A study of the effect of laser power on the magnitude of laserinduced ionization was undertaken as a means of determining the mechanism of

the ionization. In addition, a series of previously unobserved two-photon

transitions of copper were recorded.

Several possibilities for improvement of the sensitivity of the

measurement are being considered. The radio-frequency loading circuitry of

the ICP can be modified to prevent arcing between the plasma and the ionization detection electrodes. This would enable detection in regions of the

plasma with higher atom densities. Another possibility is the use of a nitrogen ICP, which has characteristics which are more favorable for LEI than

the Ar ICP.

7. An X-Y Scanning Photometer for Verifying the Transmittance Uniformity of

Solid Filter SRMs

R. Mavrodineanu, R. W. Burke, M. V. Smith, F. C. Ruegg, and W. A. Bowman

Long-term stability and transmittance uniformity are the critical

parameters that ultimately determine the quality and general usefulness of

solid transmittance standards. Experience has shown that the stability of

both the colored glass and thin-film type standards is largely dependent on

the conditions of preparation, i.e., grinding, polishing, coating, etc., and

37
can be adequately monitored on a batch-to-batch basis. Such is not the case

for transmittance uniformity, however, and each filter must be individually

verified to guarantee this parameter.

Previously, the transmittance uniformity of NBS SRM 930 Glass and SRM

2031 Metal-on-Quartz Filters was monitored on the CAC high-accuracy spectrophotometer. This check involved manual movement of the filters and was both

time consuming and an inappropriate use of this instrumentation. This situation was remedied during the past year by the design and construction of a dedicated instrument for checking the transmittance uniformity of candidate

solid filter standards. The major features of this instrument include: (a)

the use of a tritium-activated phosphor as a stable radiation source, (b) an automated x-y scanning system consisting of two stepping motors interfaced to

a microcomputer , and (c) a conventional photomultiplier preceded by a quartz

diffuser. The system is operated in an AC mode and has a short-term stability of 1 part in 10,000. This instrumentation is now being used routinely to

check the transmittance uniformity of every filter being considered for issuance as an SRM. This check is presently being made at nine locations over

the 6 mm x 20 mm area of the filter. The size of the monitoring beam is 1 mm

x 4 mm. The accuracy with which the transmittance uniformity can be established varies with the transmittance level of the filter under test. For filters having transmittances of 0.5 and above, this verification can be made

with an uncertainty of one or two parts in 10,000; for filters having

transmittances near 0.01 the uncertainty is about one part in 1000.

In the future, the measuring capability of the new instrument will be

used to guarantee the transmittance uniformity of current SRMs and also to

develop an expanded range of new SRMs.

8. Statistical Ruggedness Testing of Acid Rain pH Measurements

G. Marinenko, M. Knoerdel, and W. F. Koch

The purpose of a statistical ruggedness test is to establish the factors

which strongly influence the measurement results, and to determine how

closely one needs to control these factors. The measurement of pH in several

dilute strong acid solutions, including simulated acid rain reference materials, was subjected to the ruggedness test. The Plackett-Burman (PB) experimental design was used with seven factors and eight different factor

combinations per experiment. The design specifies that each factor is used

at one of two chosen high and low levels. In this symmetrical, experimental

design of eight measurements, each factor appears an equal number of times

(4) at its high and low level. The main effect of any factor, then is calculated simply as the average of the measurements made at the high level

minus the average of the measurements made at the low level for that factor.

Making some assumptions and conducting 16 measurements (in our case) one can separate the effects from the two factor interactions. The factors

investigated were temperature, stirring, dilution, electrode immersion depth,

addition of NaNO^, addition of KC1 , and equilibration time.

Stirring has adverse effects on the measurement of pH of dilute acid

solutions. It not only amplifies the signal noise but also biases the mean measured value. Moderate temperature control (±0.5 °C) is sufficient for

maintaining measurements accurate to 0.01 pH. Addition of neutral salts

(NaNO^ or KC1) cannot be tolerated in accurate pH measurements, as these

38
salts predictably change the mean activity coefficients of solutions, and

hence pH. The ruggedness test has revealed not only the above main effects,

but also two effects involving two-factor interactions, not determinable by

experimental design which entails changes of one parameter at a time.

Two sets of two-factor interactions were isolated and examined. The

two-factor interactions result either from the partial compensation of the

main factors such as stirring and salt addition or from a nonlinear relationship in the additivity of the effects as is the case with two salt additions.

9. Improvements in the Determination of Sulfide by Ion Chromatography

H. Kai and W. F. Koch

Previous research in the Division has enhanced the determination of

cyanide through the use of ion chromatography with electrochemical detection

( IC/EC ) . The detection limits for cyanide were lowered to below 10 _y g/g

(ppb). From thermodynamic considerations, sulfide should be even more sensitive than cyanide, and yet earlier attempts to measure sulfide at levels

below 20 ppb had failed. A research effort was launched to determine the

reasons for this anomaly and to optimize the conditions for the determination

of sulfide at the ppb level. Several factors were investigated which were

suspected of having an adverse affect on the determination of sulfide by

IC/EC: the instability of sulfide due to oxidation; the complexation of

sulfide with impurities; the adsorption of sulfide on the anion exchange

column; the condition of the surface of the silver working electrode; the

applied potential of the silver electrode; the composition of the eluent; and

temperature

.

A stock solution of sulfide was prepared and assayed by iodometric

titration. Standard solutions were made by serial dilution of this stock

with the chromatographic eluant (an admixture of ethylene diamine, sodium

borate, and sodium carbonate with a pH of about 11). A stability test of a 20 ppb sulfide solution was conducted by monitoring the peak height response

using IC/EC over a four-hour period. It was concluded that air-oxidation of

sulfide was not a limiting factor. The effect of temperature was studied

over the range of 1 1 °C to 35 °C. Below 25 °C, the temperature coefficient

was 2. 9% / K ; above 25 °C the effect of temperature became non-linear.

The electrochemical detection system consisted of a three-electrode

potentiostat in the amperometric mode. The condition and applied potential

of the silver working electrode was critical to high sensitivities toward

sulfide. The electrode had to be polished daily and then reconditioned with

several injections of sulfide before stable readings were obtained. Although

excellent chromatographic resolution of cyanide and sulfide can be achieved,

care must be exercised in the choice of applied potential to the working

electrode to avoid fouling of the electrode with silver-cyano complexes. The

optimum applied potential was determined to be +0.06 volts versus a silversilver chloride reference electrode. The anion exchange column appeared to

adsorb sulfide and had to be conditioned with repeated injections of sulfide

to saturate the adsorption sites before reproducible results could be

obtained

.

39
The major problem affecting the quantitation of sulfide at levels below

20 ppb was found to be loss of sulfide due to impurities. Metal impurities

which had become concentrated on the anion exchange column after several

years of use complexed the sulfide and retarded its elution. The metals, as determined by spark source mass spectrometry, are conjectured to come from

various sources: tin from the distilled water lines, iron, chromium, and

nickel from the IC pump, and copper, lead, and zinc from the reagents used in

preparing the eluent. Organic impurities, especially from discolored ethylene diamine, also caused a reduction in the sulfide signal at the detector.

To remedy this, it was necessary to develop a column cleaning procedure which

in itself would be non-contaminating. The recommended procedure involves the use of high-purity sulfuric acid (0.5 mol/L) which is passed through a guard

column prior to the column to-be-cleaned in order to trap the impurities in

the sulfuric acid. Only freshly opened bottles of ethylene diamine which do

not show signs of oxidation can be used to prepare the eluant. Finally, it was necessary to install a guard column in the ion chromatograph before the

sample injection loop (rather than in the conventional place after the loop)

to remove impurities from the eluant immediately prior to the introduction of

sulfide

.

This effort has resulted in a method for determination of sulfide which

exhibits excellent linearity over the range of 0.1 to 1000 ppb. The relative

standard deviation is 1 percent for 20 ppb and above, 4 percent for 1 ppb,

and 10 percent for 0.1 ppb. Research in IC/EC is continuing with the development of an improved procedure for the determination of trace levels of

iodide in complex matrices.

10, Direct Microwave Coupling Closed-Vessel Acid Dissolution

H. M. Kingston and L. Jassie

Sample preparation is an essential step in achieving both accuracy and

precision in the analysis of materials. It is also one of the most time con- suming portions of many analyses and has become the limiting step for such

multi-element techniques as ICP, DCP, XRF, and atomic absorption and emission. Acid digestion of biological and botanical samples can take from 4 to

48 hours using classical digestion techniques. Feasibility studies have previously shown the potential for accelerating the process of sample preparation by using microwave ovens as a direct coupling heat source in acid

digestion of samples. However, no systematic research linking microwave

interaction with acid dissolution has been done. All previous work has been

experimentally based.

During the past year, research has been conducted into the basic parameters governing microwave-acid coupling. The development of real time

monitors of temperature and pressure in the microwave environment permits the

investigation of closed vessel digestion using microwave energy as the heat

source. This technique uses Teflon (PFA) vessels (torqued closed) for the

evaluation of temperature and pressure acid digestion of biological and

botanical samples. This procedure has been used to successfully digest

samples in less than 10 minutes. Additionally, the digestion appears to be more complete due to the high temperatures and pressures achieved. Typical

sample temperatures of 200 °C and pressures of 945 kP are achieved in 90

seconds.
Microwave dissolution has been tested on all the major classes of

samples (biological, botanical, geological, metallic, and glassy) and has

advantages for each of these sample types. Because the digestion is done in

closed vessels the technique can be applied to sample preparations where

volatile components are a prime consideration. Not only is it a much more

rapid digestion technique, but it also produces a more complete digestion

that results in a reduction of instrumental intef erences

.

The fundamental relationships between the mineral acids, the 2*150 MHz

microwave and the vessel limitations are being investigated to provide a theoretical basis for calculating final temperature and pressure conditions

directly from microwave power (including: time, volume, acid composition,

and sample type). These relationships will allow the use of the technique by

most laboratories performing acid digestions, without specialized equipment

for applications development.

This work has opened up many new and inviting applications. For

example, because microwave digestion is a well defined system, it is suitable

for integration into an automated application. Acid digestions have previously been too judgmental and variable for automation to be practical. This

technique has direct control over the exact power and time of the digestion

and has become structured to the point it may be possible to automate. Additionally, new vessels currently being engineered will allow the use of higher

temperatures and pressures in the future, allowing the use of other reagents

and making this form of digestion even more efficient.

Currently over 200 industries, universities or research laboratories

have requested help with their specific development applications. We have

been able to provide many of them with enough information to allow them to

proceed efficiently and safely with closed vessel microwave acid digestion of

their particular samples. The research into these basic microwave relationships has led to a cooperative research program with the CEM Corporation. The

collaboration not only has addressed basic understanding but also safety

aspects. A safety valve which works in the microwave environment has been

invented which automatically limits the pressure in the Teflon digestion

vessel and makes it impossible to over pressurize this closed system.

1 1 . Leaching of Trace Metals from High Purity Fluoropolymers

J. R. Moody, E. S. Beary, and P. J. Paulsen

The availability of suitable, clean labware of fluoropolymers is one of

the major determining factors in the size of the analytical blank. Efforts

to improve analytical reagent purity and lower apparatus blanks must focus on identifying or developing the appropriate fluoropolymer of the highest

purity. Commercially, the contamination from fluoropolymers is important to

the semiconductor industry since the wafer fabrication process is extremely

sensitive to contamination. Aside from an earlier NBS publication on polymer

purity which included 3 fluoropolymers, no reliable estimate of trace metals

in all fluoropolymers is available.

Thus, because of unique experience and facilities, as well as interest,

NBS agreed to perform basic analytical research on fluoropolymer purity for

the E.I. DuPont Co. Large amounts of twelve fluororesins were obtained from

commercial sources. Portions of these samples were analyzed for gross trace

*41
element composition at NBS by neutron activation analysis. The same resins

were carefully blow-molded by the DuPont Co. into 1.5 liter bottles convenient for use in the laboratory. All of the samples and replicates were exhaustively cleaned in the trace element laboratories at NBS.

The clean containers were then charged at the same time and in the same

place using a single lot of ultrapure nitric acid (70$ HNO^ by wt . ) distilled

by the mass spectrometry group. All samples were stored in Class 10 air in a clean laboratory and subsampled (350g) at 3.7 and 37 days. These samples were split and processed as necessary for isotope dilution analysis by spark

source mass spectrometry (20 elements) and for atomic absorption (AAS and

AES) analysis (6 elements).

The crucial elements in the design of the experiment were the

availability of appropriate high purity reagents for the leaching experiment

as well as non-contaminating laboratory facilities for sample manipulation

and pre-concentration for analysis. The size of the analytical blank was known to be critical in establishing an upper limit of impurities that could

be leached from the fluoropolymers

.

The actual results confirmed this expectation since only one element

(Ca) was found in the 37 day leachates at concentrations greater than the

analytical blank. Thus, for most polymers, the elemental impurities found

were statistically indistinguishable from the blanks which except for Fe were

less than 1 ppb. Results for split samples processed by IDSSMS and AAS agreed

within a factor of two which is extraordinary agreement for Ca, Mg, Na, K,

Pb , and Zn at levels of 0. 1-1.0 ppb. A new sampling is planned in the fall

of 1985 (370 days) and further experiments with ultrapure H

2

0, HC1, and NH^CM

are planned for FY86.

12. Development of an Electrometer for Use with Thermal Ionization Mass

Spectrometers

R. W. Shideler, G. M. Lambert, and W. A. Bowman III

The development of an electrometer for use with thermal ionization mass spectrometers has been completed. There has been a long standing need for an electrometer which has features specifically designed for this area of low

current measurement. Several fine instruments, marketed both presently and

in the past, have been used. Most notably the Cary 401 (no longer manufactured) is widely used in the data systems of the mass spectrometers for

which this instrument has been designed. This instrument differs chiefly by

its generally improved performance and the ability to select, in six well

characterized steps, the best response time and, thereby, the optimum noise

performance for a given task.

The newly designed electrometer is a precision instrument capable of

measuring extremely low levels of current while having exceptional noise performance with improved speed of response as well as outstanding linearity.

The unit is designed to be used in the computer controlled data collection

system of thermal-ionization mass spectrometers, and is tailored to that

application. A commercially available parametric electrometer operationalamplifier module is used as the input current-to-voltage device in a circuit

carefully designed for optimal frequency response. This circuit is followed

42
by a unique averaging filter having a near-ideal step response characteristic. The filter is constructed with six switch-selectable response times

giving the operator control over the tradeoff between response time and noise

level. The accurate characterization of noise bandwidth also permits a highly refined statistical analysis of data obtained using this instrument.

The instrument is constructed entirely of off-the-shelf electronic

components and is quite inexpensive to construct. Compared to other general

purpose electrometers currently available, it has significantly better linearity than those units tested. The principle aspect of improvement however,

lies in the low levels of noise obtained for a given speed of response and

the ability to select that response over a range of values in order to match

the measurement both to instrumental and experimental considerations. Using a 1x10 ohm input feedback resistor with a one second response time (step

response >99$) the measured noise is about 37 microvolts RMS, which

corresponds to 3.7x10” b

amperes.

The instrument may be used on all similar types of mass spectrometers

and other measurement systems where slowly changing small current signals

must be measured with high precision. Examples are ionization chambers,

alpha detectors, low light photomultiplier detectors, and leakage measurement

systems. Future applications may include other low level measurement systems

where the ability to control the trade-off between response time and noise

can be of advantage.

The instrument may represent a turning point in the measurement of low

level signals by virtue of its enhanced capabilities of control over the

fundamental parameters of base line noise and speed of response and also by

making the analyst more aware of the consequences of this relationship. The

better characterization of these parameters can have considerable impact on the subsequent statistical treatment of data obtained for the analysis of

very low level signals. These factors and the superior measurement

performance of low noise and excellent linearity will contribute to

substantially improved accuracy of analysis.

This instrument was submitted to the IR-100 awards competition and was selected as one of the 100 most important developments of 1985.

1 3. Determination of the Lead Isotopic Composition in Human Blood from the

Italian Isotopic Lead Experiment

W. R. Kelly and K. A. Brletic

The Italian Isotopic Lead Experiment (ILE) was a large scale field study

designed to determine the fraction of Pb in human blood derived from leaded

gasoline. To accomplish this general objective, Pb of a different isotopic

composition was substituted for that normally used in the fuel. The usual

;Pb/ 2 ^Pb ratio is about 1.18. Lead from Broken Hill, Australia, which has

a

' kpb/ 2 'Pb ratio of 1.04, was substituted almost completely for that nor- mally used in the Northern Italian Piedmont region for the period 1977-1979

and then was allowed to return to normal. During the main phase of the experiment the airborne Pb in the city of Turin contained about 90% Australian Pb

and that in the rural areas about 60$.
The specific objectives of the ILE project were the following:

1. to determine the contribution of gasoline lead to total lead in

urban and rural areas.

2. to determine the contribution of gasoline lead to blood lead levels

in various population groups.

3. to follow more generally the pathway of gasoline lead through the

environment

.

The NBS role in this experiment was to provide quality assurance and to serve as a reference laboratory. One hundred whole blood samples of 0.5-2 mL were delivered to us for isotopic analyses. The established Pb separation

procedure was minaturized by about a factor of 5 in an effort to reduce the

chemical blank and the separation time. The blood samples were wet ashed and

the residue was subjected to anion exchange separation for Pb. The Pb fraction was purified by electrodeposition onto high purity Pt wires and the Pb

isotopic ratios were determined by thermal ionization mass spectrometry using

Faraday cup detection.

The results from this study were presented at the ILE Steering Committee

meeting hosted by NBS on November 26 thru 28, 1984. A number of common

samples had been analyzed by CEC laboratories in Brussels and Ispra, and by

NBS, The agreement among the three laboratories was within 0.55& which is

considered excellent for environmental data.

The experimental data are being interpreted using a model that assumes

there is thorough isotopic mixing among three reserviors: blood, soft

tissues, and skeleton. The model determined that the percentages of local

petrol affecting the blood reservior were 26/6, 1756, and 1456, for Turin, near,

and far countryside, respectively. The data are still being interpreted and

additional samples have been received by NBS.

1 4. Studies on Ion Optics - Stray Fields

I. L. Barnes, P. Morales (Univ. of Mexico), and K. R. Eberhardt

(Statistical Engineering Division)

The stray fields generated by sector magnets have relatively small

effects on ion beams that enter and leave the magnet normal to the pole

faces. The major effect is to cause a small shift in the position of the

focal point of the magnetic system, i.e., a deviation from "Barbers Rule".

With newer ion optical systems, however, knowledge of the stray magnetic

field is of great importance since the field is a component of the focusing

properties of the system in both the X and Z directions.

To gain some information about the magnitude of this force on the ions

in a typical mass spectrometer with non-normal entry, a careful study was made of the field around sector magnets operated at various values of magnet

field. Using a precision X,Y,Z positioner and several calibrated gaussmeters, we have mapped the magnetic fields at 4,6, 8, and 9 kG of several 60

and 90 degree radius magnets from a point of constant field inside the gap to
a distance 35-40 cm away from the pole face. This process was also repeated

with one magnet using various gap widths ranging from 1.27 to 3.18 cm (0.5 to

1 . 25 inches )

.

A non-linear least squares fit of the data to various models was performed and in all cases, the data show an excellent fit to an equation of

the type:

K

Y = (BX + E) + /(BX + E) ^ - 4C ( AX^ + DX + 1)

1 + exp ( — ———

— —— )

where:

Y = field (G)

X = distance from the pole edge (in gap widths)

K = maximum field inside the gap

A , B, C , D , and E are constants

The values for the constants for any magnet of gap width, W, may be obtained

by:

A = -0.0398460 - 0.13051 36 W

B = -0.784763 - 0.098426 W

C = -0.0653538 - 0.0102984 W

D = -1.99784 + 0.0149582 W

E = -0.512966 + 0.0251027 W

The above equation may be integrated by numerical methods to determine both

the total value of the stray field and the effective pole edge. These values

have been incorporated into the programs TRANSPORT and TRIO to give much more realistic mass spectrometer designs.

In addition, this information is being used in a computer program now under development which will permit the examination of the perturbation of

real ion beams at any point in the flight path. Preliminary results indicate

that smaller, more efficient mass spectrometers may be designed using new ion

optic systems and an experimental instrument using these designs is now under

construction.

15. Automation of RIMS

F. C. Ruegg

In order to time-average the data produced by the Tektronix transient

digitizer at a rate of 10 Hz or greater, it was necessary to interface the

digitizer to a more powerful computer than the HP 9845. A 8086/8087 16 bit

I.E.E.E. 696(S100) based microcomputer with 33 megabyte hard disk was Interfaced to the digitizer. A data acquisition program was written in Fortran-77

with 8086 assembly language I/O drivers to average digitizer data at rates up
to 42 Hz (1024 points). The HP 9845 is connected as the 8086's console, and

is the master computer. The 9845 controls data acquisition by sending

commands to the 8086, such as, when and for how long to take data.

The computer hardware is based on the I.E.E.E. 6 96 ( SI 00 ) bus, and

consists of the following components:

1) Lomas Data Products 8 MHz Lighting One 8086/8087 cpu board

2) Lomas Data Products floppy disk controller board

3) Lomas Data Products Hazitall 1/0 board

4) Macrotech Max-384k - 384k byte memory board

5) Scion MA-520 51 2 X 480 graphics display board

6) National Instruments I.E.E.E. 488 interface

7) Video-100 graphics display

8) Dual Qume-242, 8 inch double sided disk drives

9) Quantum Q540, 40 Megabyte 5-1/4 inch hard disk

10)

Qume QVT-102 terminal

The computer software runs under the CP/M-86 disk operating system and was written in Digital Research’s Fortran-77 and RASM-86. The program

performs the following functions:

1) Initialization of the I.E.E.E. 488 interface bus

2) Clear all I.E.E.E. 488 devices

3) Turn remote enable on

4) Get disk drive and root data filename from operator

5) Get ’N' number of laser pulses to average from operator. If *N’=0

then stop

6) Command Tektronix digitizer to digitize ’N’ laser pulses and

transmit each data set to the computer

7) The data is summed for each laser pulse in array in memory for ’N’ pulses

8) The data is then scaled and displayed on CRT graphics display

9) The data is written to the named (root. ext) disk file

10) The filename extension is incremented

11) Loop through item 5-11

The 8086 microcomputer and the HP 9845 computer are connected together

using RS-232 interfaces with the HP 9845 acting as the console to the 8086

microcomputer. An HP Basic program has been written utilizing an HP supplied

binary program which allows the 9845 to emulate a terminal. This program

allows the HP 9845 to control the microcomputer's data acquisition program

and to exchange data with it.

16. Methodology Development for Sub-ppm Boron Measurements

J. W. Gramlich, L. A. Machlan, H. Zeininger, and K. A. Brletic

The Mass Spectrometry Group several years ago developed a procedure for

the accurate measurement of boron at high concentrations. This technique was used to certify the absolute isotopic abundance of boron in SRMs 951 and 952

(boric acid) and the boron concentration, by isotope dilution mass spectrometry, in several Standard Reference Materials. Although this technique is

definitive for high concentrations, it is not applicable to ppm or lower

levels of boron.

46
During the past year, the group was fortunate to have as a guest worker

from Germany, Dr. Heinz Zeininger. Dr. Zeininger developed unique chemical

and mass spectrometric procedures for trace level boron analyses as part of

his Ph.D. research at the University of Regensburg. A major effort was undertaken to take full advantage of this opportunity to develop the capability for trace level boron measurements at NBS.

Mass spectrometric procedures have been developed to allow the precise

measurement of nanogram quantities of boron. The mass spectrometric technique involves the mixing of lanthanium nitrate with the sample, in the form

of boric acid. It is postulated that the lanthanium and boric acid react to

form lanthanium hexaborate, which is known to provide an extremely low work

function filament surface (-2.7 eV), conducive to negative ion formation; the

species observed in the mass spectrometer spectrum is the BO2 ion.

Research on the chemical separation and purification of trace amounts of

boron have resulted in the construction of specialized quartz apparatus for

the refluxing and distillation of the samples. The chemical and mass spectrometric procedures have been tested on samples of milk powder and steel

(considerably different matrices) and have shown the general technique to be

successful. Major problems still exist in the control of the analytical

blank. Current research is focusing on identification of sources of the

blank, sample recoveries, and complete sample decomposition.

The boron contents of numerous nuclear reprocessing plant construction

materials were determined during the year using the large sample positive ion mass spectrometric technique. Many of these samples have been archived and

will be re-analyzed using the newly developed negative ion technique as a verification of accuracy.

17. Time-Resolved, Magnetic-Dispersion for Large Isotope Ratio Measurements

By Resonance Ionization Mass Spectrometry (RIMS)

J. D. Fassett, H. Zeininger, and L. J. Moore

The measurement of large elemental isotopic ratios by conventional mass spectrometry is limited primarily by molecular isobaric interferences and ion

scattering. Both of these problems can be addressed by resonant, multiphoton

ionization using pulsed lasers. Resonance ionization mass spectrometry

(RIMS) uses tunable lasers to selectively and efficiently ionize gas phase

atomic species. Thus, RIMS can be used to characterize and reduce molecular

isobaric interferences, which typically result from non-selectivity in the

ionization process combined with impurities in the sample or residual gases

in the mass spectrometer. Time-resolved, magnetic dispersion of the pulsed

ion beams, which are formed by the laser, combines time-of-fiight (velocity)

and magnetic (momentum) mass filterings. Ions scattered from a large peak

into adjacent mass channels of a magnetic sector mass spectrometer can y distinguished from unscattered ions by their respective times-of-fl ight . Thus, the abundance sensitivity of the mass spectrometer increases along wind

the ability to make large iostope ratio measurements. We have experimentally

verified the feasibility of time-resolved, magnetic dispersion in the past

year, and are preparing to apply the technique to the measurement of the 1 >w

level, long-lived radioisotope

' 2 ^I.

47
We have demonstrated time-resolved, magnetic dispersion by doing RIMS of

both Re and Ta. Since Ta has a naturally large isotopic abundance ratio

(^°Ta/ 1 ° 1 Ta = 10~^), it provides a good demonstration of the effective

improvement of abundance sensitivity. The normal position of the laser in

the RIMS instrument was changed to minimize the width of the laser-generated

ion pulse and to maximize the time-of-flight resolution. By focusing the

laser between the first and second plates of the ion source, a timeresolution of 25 nsec was achieved. The ion signal was detected using a 17-

stage electron multiplier whose output was preamplified using a high-speed,

inverting pulse amplifier with 100 MHz frequency response. The output of the

preamplifier was directed into a 200 MHz digitizer, which was operated at the

maximum time resolution of 5 nsec per channel. Extensive signal averaging of

the time-of-flight spectra was done as the magnetic field was stepped. Both

the elastically and inelastically scattered ions are readily apparent in the

plane defined by the magnetic field and time. Furthermore, for Ta a non- selectively ionized interference at m/e 1 80 position was simply identified by

focusing the laser away from the Ta resonance wavelength.

We have further explored the resonance ionization mass spectrometry of

iodine in the past year, in order to define an optimal measurement strategy

for the determination of 12^i in real, environmental samples. A threephoton, single-color resonance ionization process is required for iodine

because of its large ionization potential. Achievement of efficient ionization with this three-photon scheme necessitates the tight focusing of the

laser beam, which has both positive and negative ramifications. A negative

result is that specificity is reduced, both iodine and hydrocarbon interferences are non-selectively ionized. A positive result is that the focused ion

beam produces iodine by the dissociation of Agl, the prominent species that

is thermally vaporized. We discovered that the resonance wavelength at 298.2

run possesses a number of important advantages over the previously studied

resonant wavelengths for RIMS of I. Apparently, because of the lower energy

of the photons at this wavelength, the selectivity of resonance ionization

increases tremendously, with no major decrease in the overall sensitivity of

the ionization process.

A high-speed system has been developed by Fillmer Ruegg, Atomic and

Molecular Spectroscopy Group, to acquire and signal-average the magnetically

dispersed, time-of-flight spectra in real time. The system will allow the

efficient determination of the very low ion count rates that must be detected

in the measurement of large isotopic rates. In the coming year, we plan to

combine the time-resolved, magnetic dispersion technique with real-time

signal-averaging or pulse-counting in order to make RIMS measurements of

’I/^ 2 ^I ratios of less than 10 D

.

1 8 . A New Method for the Accurate and Precise Determination of Se at

Nanogram Levels

P. J. Paulsen and E. S. Beary

In recent years, there has been increased interest in the precise and

accurate determination of Se at low concentrations. Industrial interest

stems from the fact that Se contamination alters chemical and physical properties of metals. In agriculture and medicine, both standards and techniques are desired to determine selenium in biological materials at the
nanogram level. The role of Se in nutrition is not well understood, however

the devastating effects of both Se deficiency and Se toxicity are well

documented

.

During the method development for the determination of sulfur as AsS

+

, it was noted that an AsSe

+ ion beam could also be produced directly from a reaction on a silica-gel H^PO^-Re filament (between SeO^ and As

+ ^). When

the filament is heated to 900 °C, a 75 As°0 Se

+ ion beam of 3x10 -12

amps is

obtained from a loading of 60-100 ng of SeLAsSeO^ j. The Se iostoDic abundances were measured between mass 157 ('^As°2 Se) and mass 149 (''’As'^Se).

The ^ 2 Se/^°Se isotopic ratio measured from AsSe

+ ions, can he determined

with ±0.1 % precision for both natural Se and the enriched 2 Se isotopic

spike. Mixes of 02 Se spike solution and accurately known amounts of natural

Se were analyzed to determine the S2 Se spike concentration. Replicate mea- surements yielded values agreeing to ±0.1$ rsd. These analyses proved that

this procedure has the potential of accurately determining the concentration

of Se at the nanogram levels.

An analytical scheme was developed for the determination of selenium in

copper (SRM 1251). The separation involved the initial separation of Se and

other volatile elements by use of a quartz combustion tube at 1000°C. Selenium was isolated by selective reduction to the metal. This analysis yielded

a Se concentration of 10.45 ± 0.05 ug/g. This is in excellent agreement with

the NBS certified value of 10.5 ug/g based on values obtained by IDSSMS and

Atomic Absorption Spectroscopy. These data proved to be encouraging and

improved understanding of Se chemistry makes future determinations of Se in

organic matrices promising.

19. The Determination of Iodine in Foods and Other Biological Materials by

Epithermal Neutron Activation Analysis

George Lutz

Epithermal neutron activation analysis (ENAA) has been used for the

rapid reliable nondestructive determination of iodine in foods and other biological materials. Samples are encapsulated in boron nitride containers with

wall thickness of several millimeters. The boron serves to substantially

absorb thermal neutrons, but to allow epithermal neutrons to activate the

sample. Iodine exhibits neutron capture resonances in the epithermal

region, enhancing the productivity of the neutron capture reaction of iodine

relative to that of interf erring elements, such as sodium, potassium,

manganese, chlorine, and bromine. There are three primary applications of

this technique in the CAC.

(1) Iodine is used as a stable tracer in the NAA of 12 ^I. The first

step of the analytical procedure is the lyophilization of the sample and

subsequent pulverizing and homogenization. An aliquot of the sample is taken

and analyzed by ENAA. Stable iodine in the sample can be determined at other

¥24£

(2) The second application is the determination and certification of

iodine in Standard Reference Materials. Although instrumental photon activation analysis (IPAA) has been used successfully in the group for iodin<-

fso

in1 the analysis serving as a measure of the radiochemical yield of
determinations, ENAA gives results with comparable reliability and somewhat

better sensitivity at a small fraction of the personnel and measurement time

relative to IPAA.

(3) ENAA is being used for the rapid routine determination of iodine in

foods for measuring total dietary content. This work is being done in

collaboration with Dr. W. Stroube of FDA.

Irradiations have been conducted at the reactors at the University of

Virginia and Maryland, in addition to that at NBS. The reactor power level

is not very relevant to sensitivity. The nature of the neutron moderation

and proximity of the sample to the reactor core are more significant.

Sensitivities are of the order of 0.1 ppm and analysis time is 30-60 minutes.

20. Multielement Analysis of Biological Macromolecules

S. F. Stone, R. Zeisler, and D. Hancock

The importance of the role of trace elements associated with biological

macromolecules has become increasingly apparent in the last twenty years. For

example, studies of metalloproteins has revealed the structural and functional importance of certain trace metals associated with proteins. The biological specificity of metalloenzymes depends on the presence of both the

protein and the metal ion. Removal of the metal ion results in a loss of

biological activity. Trace metals have also been found to be structurally

important in stabilizing secondary, tertiary, or quarternary protein

structures. Detection of trace elements associated with proteins may be

accomplished with a newly-developed combination of biological separation

techniques with analytical nuclear methods.

Polyacrylamide gel electrophoresis (PAGE) separation of proteins by

molecular weight is one technique that we have used. Several proteins were separated by electrophoresis on a 10-20% gradient polyacrylamide gel. The

whole gel was then irradiated with neutrons, and following a short time, an autoradiograph was developed to detect any beta-emitting isotopes of fairly

high energy that had been produced. The location of a phosphoprotein phosvitin, was visualized in this way. Phosphorous the isotope detected in the

autoradiograph, indicates the location of the phosvitin on the gel. The autoradiography technique has a much more sensitive threshold of detection for

this protein than does the non-specific protein stain, Coomassie Blue. As

protein band corresponding to phosvitin is barely visible on a duplicate gel

that was stained with Coomassie Blue.

In addition to autoradiography , gamma-counting has also been used for

other metalloproteins using neutron activation analysis. Protein electrophoresis is often carried out in the presence of the denaturing detergent,

sodium dodecyl sulfate (SDS). An electrophoretic separation of the zinc

metalloprotein carbonic anhydrase was done using SDS, and a trace element

analysis of gel sections was performed. A marked increase in zinc, was found in the protein band (gel section 5), compared to the background, as expected. However, many other trace elements, which have no known association with the enzyme, increased as well. In addition, the zinc concentration

found in the protein band was more than should have been present from the

50
amount of protein applied. Studies are currently in progress to learn more

about trace element associations with proteins under both denatured and non- denatured conditions.

21 . Light Element Determination by Neutron Activation Analysis

R. Fleming

Determination of the light elements, hydrogen through neon, by neutron

induced activation is seldom exploited because of the small cross sections,

short half-lives, and often decay without gamma emission. It is true that

prompt gamma activation analysis (PGAA) has demonstrated the capability of

measuring hydrogen and boron at the ppm level and can determine carbon and

nitrogen at major constituent levels. Photon activation analysis (PAA) can also determine carbon at high levels using the 1

2

C (Y,n , a) ^Be reaction. The

near-surface regime can be profiled for ^He, °Li, °B, and using neutron

depth profiling, but the ability to quantify elemental concentrations in this

part of the periodic table remains less than satisfactory. Two new approaches are being taken to improve this situation.

The advent of modern liquid scintillation counters makes possible the

simple, reliable and accurate measurement of nuclides that decay by pure beta

decay over a large dynamic range. As is typical with beta counting, a preseparation of the beta emitting element is necessary. The most attractive

element to quantify by neutron activation with beta counting is nitrogen,

using the 1 ^N(n,p)^C reaction and carbon-14 assay. In this way nitrogen can

be determined at below the nanogram level. Possible interferences from

-’CCn.Y) C or '0(n,ot) C reactions or from natural carbon-14 levels can be

shown to be small in most cases of interest. Extension of the beta counting

approach to the determination of sulfur and of phosphorous appears promising,

as well.

A collaboration with Professor W. Brian Clarke of McMaster University

has provided us with the opportunity to determine both lithium and boron

using neutron activation followed by ^He/^He mass spectrometry. The samples

are irradiated in evacuated lead capsules along with lithium and boron standards. The reactions °Li(n,a)^H and 1C) B(n,a)'Li both produce helium-4 from

the alpha particle production and the tritium produced from the lithium

reaction decays with a 12.3 year half-life to helium-3. Because both these

reactions have very large cross sections, there are few potential interferences when a well-thermal ized neutron flux is used. Measurements at the ng/g

level for lithium and yg/g level for boron are possible with good accuracy.

The method is now limited to materials such as botanicals or biologicals that are permeable to helium. With heating of the sample to release the helium

prior to mass spectrometry, accurate determination of lithium and boron in

metals could be achieved.

Work will be continued to improve our ability to quantify elements in

this important part of the periodic table. A capability to assay nuclides

with short half-lives and improvement of the prompt gamma sensitivity are obvious steps in this direction.

51
22. Neutron Depth Profiling: Industrial Interaction and Application

R. G. Downing, J. T. Maki , and R. F. Fleming

The industrial interactions have steadily increased at the neutron depth

profiling (NDP ) facility during the last year. The capability of NDP to

quantitatively and nondestructively analyze one-of-a-kind samples so that

they are available for studies using other techniques or further processing

is quite unique. These capabilities also allow intertechnique calibration on

the same specimen. Consequently, a research associate and five guestworkers

have formalized agreements between their companies and the Center for Analytical Chemistry for the use of the NDP facility. This brings the total number

of outside industrial and academic users of NDP to over 15.

Electronic and high technology materials have dominated the types of

investigations being performed, resulting in numerous technical papers and

formal presentations. The increase in the NBS Reactor power level from 10 to

20 MW has doubled the neutron beam intensity at the NDP facility making the

investigation of nitrogen-rich materials practical. Profiles of silicon

nitride, an optical wave guide material, and titanium nitride, a metallic

film surface coating, are examples of recently completed studies. In addition, the profiling of lithium migration in corroding aluminum-lithium alloys

(a new ultra-light material), measuring implant profiles of boron in mercury

cadmium tellurides (an IR sensor material), and analyzing boron profiles in

lanthanum boride (a thermionic electrode material) are a few of many new

areas of research pursued this year. All of these studies have been initiated by the firms to understand current process related problems associated

with the fabrication of products.

Two major facility improvements are currently being implemented. First,

a spectral transfer system is being developed to allow direct transmission of

NDP spectra and evaluated data from the facility computer to the computers of

industrial and academic users. This will greatly enhance and expedite the

usage of the information in solving process and research related problems.

With the system, the now tedious and involved process of data reduction will

be transferred to faster computers making deconvolution of the acquired NDP

profiles readily available. Secondly, a turbomolecular vacuum pump is being

installed at the reaction chamber to improve system stability. The pump will

minimize system down time by reducing routine maintenance.

In the coming year, several new materials studies and facility upgrades

are being planned. Using separated isotopes (i.e., oxygen-17 and

beryllium-7), sensitivity can be enhanced thereby allowing specific process

related problems to be addressed. Also planned is the incorporation of a goniometer into the sample chamber for more careful alignment of sample and

detector. This piece of equipment will give greater positional control for

enhanced depth resolution at interfacial boundaries and for the profiles of

the near surface of specimens.

52
23. Re-Characterization of the NBSR at 20 MW

D. A. Becker

Recently, the National Bureau of Standards nuclear reactor (NBSR) was upgraded to 20 MW (thermal). With the higher neutron flux densities and

modification to one of the pneumatic tube irradiation facilities, an extensive recharacterization was undertaken. This recharacterization extended the

previous work on the NBSR, and several new techniques were developed which

simplified data accumulation and resulted in better information about these

facilities

.

The measurements were designed to fulfill two primary purposes. First,

knowledge of the neutron flux density and its variability over the irradiation volume are important for accurate and precise neutron activation analysis. All samples and standards must receive the same (or well known) neutron

fluence. Further, information about the thermal/fast neutron ratios is very

important for the selection of an optimum irradiation facility in a reactor

or between different reactors. In one case, reactor characterization

revealed that a small reactor (University of Maryland, at 150 kW power)

provided greater sensitivity for a fast neutron activation analysis than was available at the NBSR.

The second purpose of these measurements was to establish maximum

allowable irradiation conditions for the NBSR at the new power level. A

thorough understanding of the relative neutron flux density before and after

upgrading, along with extensive evaluation of the temperature and pressure

limitations of the NBSR at 20 MW, significantly improved our ability to

obtain approvals for the sample types and quantities needed for the NBS

activation analysis program.

The parameters measured included the following: thermal neutron flux

density; flux variations within an irradiation volume and between irradiations; relative fast neutron flux density; maximum temperatures generated by

different sample matrices in the various irradiation facilities; and pres- sures generated in sealed containers by radiolytic decomposition. For the

pressure measurements, a system was developed which utilized a hypodermic

syringe and a mercury manometer to provide simple, yet accurate, measurements

of small amounts of gaseous radiolytic decomposition products. This system

substantially improved the pressure measurement data, and for the first time was able to show linear gas production with neutron fluence for a specific

irradiation facility.

This effort has resulted in the NBSR having perhaps the most highly

characterized irradiation facilities available, and provides the information

needed for the high accuracy analyses required by the Nuclear Methods Group.

At present, it appears that the NBSR upgrade to 20 MW will provide a usable

neutron fluence 50? greater than that available at 10 MW.

53
24. Determination of Gold and Platinum in Urine at Picogram Concentrations

R. R. Greenberg and R. Zeisler

There is continuing concern about the possible impact of platinum on the

biosphere due to the increasing industrial and medical uses of this metal.

Approximately 18700 kg (600,000 troy ounces) of platinum are used annually by

the automotive industry, while therapeutic utilization of platinum compounds

for their anti-cancer properties is increasing. Due to this expanding use of

platinum, it is important to be able to measure it at the naturally occurring

levels.

Accurate determination of Au and Pt at concentrations below 1 ng/g is

extremely difficult and requires rigid control of the blank. Radiochemical

neutron activation analysis (RNAA) provides an ideal method to determine

these elements in that it can be performed in an almost blank-free manner. After irradiation, but before chemical manipulation of the samples, unirradiated carriers of the elements of interest can be added to minimize losses

which typically occur when processing extremely dilute solutions of the noble

metals. Several years ago a procedure was developed to determine both gold

and platinum in solid biological samples via RNAA. This procedure has been

modified to allow the determination of these metals in both the elevated and

the natural level fractions of the Trace Elements in Urine Standard Reference

Material (SRM 2670). Urine is a difficult matrix for NAA for two reasons.

First, the high salt level in urine produces a large amount of background

radiation which must be removed prior to gamma-ray spectroscopy, and second,

a liquid is considerably more difficult to irradiate than is a solid, and

often requires a pretreatment step, such as lyophili zation , which can increase the blank.

The concentrations of Au and Pt observed in the elevated fraction of the

Trace Elements in Urine SRM were 244.4 ± 8.2 and 125.1 ± 8.0 ng/mL, while the

concentrations observed in the normal fraction of this SRM were 8.0 ± 1.4 and

8.0 ± 2.7 ng/mL. These concentrations are given for the specified dilution

of the contents of each bottle of freeze-dried urine to 20.0 mL. The uncer- tainties for these measurement were calculated by combining the standard

deviation of the mean for each set of values mutliplied by the appropriate

t-value for the 95# confidence level, and then adding the estimated systematic error. For the Au measurements in both the elevated and normal level

urine samples, the estimated systematic error was 2# which was due mainly to

potential counting geometry errors between the unknown samples and the standards since the samples were counted directly on top of the detector. The

estimated systematic error for the Pt in the elevated urine was 4#: 2 % from

counting geometry and an additional 2% from possible bias in peak integration

of the 158 keV peak of Au-199 which lies directly upon the backscatter peak

of Au-198. The estimated systematic error for the Pt in the normal urine was

12# (2# from counting geometry and 10# from the determination of the Au

interference; this 10# error also includes the bias from peak integration.

The observed sample standard deviation for Au in the elevated fraction

of the urine (1.1#, relative) was slightly greater than expected from counting statistics. This excess variance is probably due to counting geometry

errors (discussed above). The observed sample standard deviation for Au in

54
the normal fraction of the urine was significantly greater than the counting

statistics. This may be due to variable losses of Au onto the walls of glass

bottles (prior to lyophilization)

.

With an apppropriate separation procedure, RNAA can be used to determine

the concentrations of Au and Pt in biological samples at the picogram per

gram level. Both solid and liquid samples can be analyzed, however a lyophilization step prior to irradiation may be advantageous.

25. Optimized Measurement of Iodine Isotopic Ratio by Neutron Activation

R. M. Lindstrom and G. J. Lutz

A procedure has been developed to perform reliable measurements of

iodine-129 concentrations and 1 29 j/127-

[

- rati OS i n a f ew grams of sample, down

to the present-day background level, of approximately 10° atoms/gram (5

aCi/g) with acceptable precision and low blank. 129 j/127j ratios as low as

6x1

0~ ^ have been measured in natural materials. Neutron activation is used

to measure both iodine isotopes simultaneously from the ratio of to °I

activities, produced by thermal and fast neutrons respectively. By tailoring

the irradiation conditions, such systematic errors as chemical yield and

counting efficiency are made to cancel in the measurement of the ratio.

In a space of thermal neutron flux versus fast (fission spectrum)

neutron flux, the analytically optimum region is defined by four boundaries:

to produce a large enough ^ I signal to be detectable, the thermal neutron

flux must exceed 5x1

0

1 n/cm 2 s; however, to avoid interference from the

triple capture reaction on

12^I it cannot exceed 8x1 o'* n/cm 2 s. For the 12 °I

signal to be detectable, the fast flux must exceed I.MxlO 11 n/cm2 s, but in

order that both radionuclides to be measurable in the same spectrum the

fast/thermal flux ratio must not exceed unity.

A powerful heavy-water reactor like the NBSR offers a variety of neutron

environments which span the ideal range. An irradiation facility tailored

and dedicated specifically for this task will provide high quality iodine

isotopic ratio measurements. When this is done, the ultimate sensitivity

will have been reached as far as the irradiation parameters are concerned.

26. Laboratory Information Management Systems (LIMS)

B. I. Diamondstone and M. S. Epstein

A database has been established in the Division during the past year

that contains important information regarding the analysis of Standard Reference Materials (SRMs). The database is menu-driven and can be used without

any knowledge of the database management system operation. The information

contained in this database is derived from the Reports of Analysis that have

been generated for approximately the last five years and includes the

following information:

55
-Element of interest

-Matrix

-SRM number

-Analyst

-Technique

-Date of Report

-Value

-Uncertainty

-Units

-Control

- SRM #

- Certified value

- Determined value

These data fields have been selected as the minimum amount of information needed for each analysis. As more experience is gained with using the

system, additional fields can be added. If an elemental concentration is

recommended by the analyst it is entered in the field labeled value. If not,

the mean of all values listed in the report is used in this field. Similarly,

the uncertainty entered is one recommended by the analyst or is one sigma of

the mean. If a control sample has been analyzed, the certificate value is

listed along with the recommended uncertainty when this information is available. If this value is an information-only value, then no uncertainties are listed. The value (s) obtained for the control sample and the uncertainty

are also listed.

The concept of LIMS is not new and, in fact, systems like the one described have been used in industry for many years. For the most part, the

industrial systems are designed to handle large numbers of samples and are intended to carefully document the history of samples, from the time they

arrive in the laboratory to the completion of all analyses. Although the

heart of these systems is simply a data base management system, the systems

are often directly connected to various instruments and use baseline information on calibration samples and controls to determine whether the analyst can proceed with the analysis. The results of analyses are fed directly into the

system, a statistical evaluation is done, and a final report of analysis is

produced.

The system which has been developed in the Division is intended to

provide more of an information source rather than to control a total operational procedure. The information compiled will have many uses in the pro- cess of estimating and planning work on future Standard Reference Materials.

For example, as plans are developed for a new SRM, the data base can be

searched to provide information on which techniques have been used for analyses on specific matrices, which techniques have the capability to analyze

specific elements, and what are typical levels of detection for each element.

In addition, the database can provide information on analysts who have had

experience with certain matrices or elements. Another potential use of this

system would be in the critical area of resolution of discrepant data. Data

collected for previous analyses can provide information on possible bias

trends for particular analytical techniques. Values obtained on control

samples can be evaluated for particular elements, over a series of different

matrices, and compared to the certified values. This type of information

would be useful to a statistician in resolving differences between techniques

if one technique has shown a tendency to be either higher or lower on the

control samples.

56
As more uses for this information become apparent, the database can easily be expanded and updated to provide additional information that can be

extracted from Reports of Analysis. In fact, it would be possible to electronically provide interested individuals with copies of the Reports of Analysis for their own use. The availability of databases such as the one described here emphasize the need for providing complete and accurate information in the Reports of Analysis. In the future, this system could be used

to assign sample identification numbers and establish sample custody when

many analyses are to be done. In addition, it could conceivably be used to

schedule analytical work in the Division and to assign recommended control

samples and procedures for specific analyses.

27. Development of a Standard Reference Material for Rainwater Analysis

W. F. Koch, G. Marinenko, and Y. C. Wu

Wet deposition is monitored by various laboratories and agencies as part

of national and international networks to record accurately the composition

of rainfall. These efforts are intended to determine the extent of the problem of "acid rain", and to establish spatial and temporal trends. Discrepancies in data often occur due to differences in instruments and techniques.

These discrepancies limit the conclusions which may be drawn from the data.

To establish a common basis for chemical measurements in rainwater, a multiyear research effort in the Inorganic Analytical Research Division, Center

for Analytical Chemistry has been established. This effort has resulted in

the issuance of

Rainwater

.

a Standard Reference Material (SRM) 2694, Simulated

The decision to prepare simulated rainwater

,

rather than collecting

natural rainfall was based on the need to minimize contamination and unwanted

components which would compromise the overall stability of the solutions.

Thus, simulated rainwater prepared by the dissolution of salts and acids in

water was the best recourse. Low density polyethylene (LDPE) bottles (60-mL

capacity) were chosen for this project based on earlier research. The bottles were cleaned by a rigorous and tedious procedure to minimize contamination. At all times, the bottles were kept clear of areas with acid fumes.

Two levels of simulated rainwater containing the cations and anions commonly

found in acid rain were formulated in such a way so as to span a useful ana- lytical range of concentrations of all components. It should be noted that

the measurement of pH was the primary driving force behind the development of

this SRM. Hence, the stability of the solutions with respect to pH was an over-riding constraint. It has been found that unbuffered solutions above

about pH 4.5 are extremely susceptible to fluctuations in pH and acidity due

to absorption and desorption of atmospheric carbon dioxide. These processes

occur even through the walls of the polyethylene bottles. For this reason,

although it would have been desirable to issue a solution of pH 5.0, SRM

2694-1 was targeted at pH 4.3 to be on the safe side.

Approximately 170 liters of 2694-1 and approximately 150 liters of 2694-

II were prepared in February 1985. The solution was thoroughly homogenized

by intermittent vigorous stirring over a 24-hour period. Note that although

care was taken to add exact amounts of each component and to dilute with the

correct amount of water, there was no convenient way to accurately assess the

final volume. Hence, one cannot use the weights and volumes as an analytic.il

measure of the concentrations of the various components. Before the bottling

57
commenced, a sample of each level was analyzed by ion chromatography and

potentiometry to verify that the target values had been met. The bottles were filled manually, capped immediately, and placed sequentially in numbered

cartons. Concurrent with the bottling operation, a homogeneity test was run. One out of every 120 bottles was pulled from the line and tested for specific

conductance. After establishing the homogeneity of the solutions, the statistical design for the sampling and analysis of the other components was configured. It involved the determination of each component in triplicate in

each of three bottles (selected from the beginning, middle and end of the

bottling operation) by each technique. Because of experimental exigencies of some techniques, this analysis design was not strictly adhered to in every

case, but was followed whenever possible.

The techniques used in the analysis of SRM 269*1 were ion chromatography

(IC), conductivity, potentiometry, coulometry, isotope dilution mass spectrometry (IDMS), spectrophotometry , laser enhanced ionization flame spectrometry

(LEIS), flame emission spectrometry (FES), inductively coupled plasma (ICP),

and flame atomic absorption spectrometry (FAAS) . Details of the analytical

procedures for each technique will be published in a forthcoming special publication. Values for fluoride, nitrate, sulfate, sodium, potassium, calcium,

magnesium, pH, acidity, and specific conductance have been certified in SRM

269*1. Values for chloride and ammonium are listed for information purposes

only. Chloride was not certified because it was felt that the potentiometric

method had insufficient precision and accuracy at these levels to corroborate

the ion chromatographic data. Ammonium ion was not certified because of very

real concerns about the stability of this ion in these solutions.

The problem with the stability of ammonium ion was first noticed upon

re-analysis of RM 8*409 eight months after its preparation. The concentration

of ammonium in RM 8409-1 had decreased from 0.085 mg/L to 0.025 mg/L. On

rechecking other samples of simulated rainwater which were part of a longterm stability study of pH and conductivity, similar decreases in ammonium

ion were observed. The decrease was quite significant when the initial con- centration of ammonium was extremely low [below 200 mg/L] and the pH was

above 4.0. The cause of this decrease is not known at this time, but it is

suspected to be bacteriological. The loss of ammonium does not appear to

have affected significantly any other components.

Investigations are underway to remedy this problem with the instability

of ammonium. Also this year it is planned to explore new types of bottles

which are inert and free from contamination, and at the same time which do

not have problems with transpiration. Related research will involve the

stabilization of phosphate in acidic media and investigations into the needs

for standards and methods in dry deposition. The primary foci will be on the

assessment of analytical errors and on the stability of solutions containing

inorganic species at the sub-ppb level.

28. Standard Reference Materials

B. I. Diamondstone

The analysis and certification of Standard Reference Materials (SRMs)

has again been a major part of the total scientific effort of this Division.

As in the past, there are three sources of support for work on SRMs: the

58
Office of Standard Reference Materials (OSRM) provides STRS (Scientific and

Technical Research Services) and WCF (Working Capital Funds), and the Technical Division also provides STRS funds. The OSRM portion of the STRS funding is intended for the preliminary research necessary to develop the methodologies required for the actual production of SRMs. Input in these areas is

provided by the entire scientific staff with a considerable portion

representing cooperative efforts between groups within the Division.

This year a new concept has been implemented in the Division, the designation of selected senior staff personnel as "technical champions". The purpose of a technical champion is to interact closely with the OSRM technical

coordinator and to provide scientific oversight for the entire process of

producing an SRM. It is hoped that by being involved with the SRM from con- cept to certification, the technical champion will provide continuity

throughout the certification process by giving the analysts a better understanding of the sample history and by providing the technical coordinators

with a direct and continuous link to the analytical process. This year, about

six technical champions were designated for a variety of potential SRMs such

as simulated rainwaters, oyster tissue, and river sediment.

Listed below are ten different areas of research that were funded by

OSRM during the past year.

STRS Projects Supported by OSRM during FY85

Task Description

Transmittance SRMs Research leading to the development of methods and

the evaluation of materials for the production of

transmittance SRMs for the near IR. All components

are in hand and evaluation is in progress.

Voltammetry Research leading to the development and implementation of anodic stripping voltammetry for trace and

ultratrace levels of electroactive metals in SRMs. A

method has been implemented for the determination of

cadmium and copper in SRM 1 643b using indium as an internal standard.

Gases in Metals Research leading to the evaluation of two

independent procedures for the analysis of carbon in

SRMs. Emphasis on the manometric procedure with some interaction between NBS and Univ. of Ghent for PAA

analysis. Work is completed on the determination of

total carbon in a series of biological SRMs using a fusion technique. Manometric measurements are in

progress.

ICP-Mass Spec Research leading to the application of Inductively

Coupled Plasma Mass Sepctrometry to the analysis of

SRMs. The new ICP-MS instrumentation is operational

and preliminary experiments to evaluate accuracy are

in progress.

59
Aqueous Electrolytic

Conductance Stds

Continued research leading to an understanding of the

fundamentals of conductivity and the feasibility of

producing aqueous conductivity SRMs. Literature

review and recalculation of existing values is complete. Instrumentation for preliminary measurements

is operational.

LEI Measurements Research leading to the adaptation of Laser Enhanced

Ionization instrumentation to trace element analysis

in SRMs. Proposed work is completed and various parameters of the system have been optimized for the

analysis of SRMs.

Diode Laser Research leading to the identification and quantitation of gas species in NBS gas SRMs. Work in progress on intercomparing high concentrations of

NO^/air compressed gas mixtures by tunable diode

laser absorption spectrometry and chemiluminescense

detection.

F in Biologicals Research leading to the development of an ion

chromatographic procedure for the analysis of

fluoride in biologicals. Work is in progress.

State-of-the-Art SRMs Research leading to the development of measurements

Trace Boron

and procedures for a series of new state-of-the-art

reference materials. The first material will be

human liver. Work is in progress to evaluate the

collected human liver samples as a potential SRM.

Research leading to the development of the necessary

chemical separations and ionization technology

required for isotope dilution mass spectrometric

determination of boron. Instrumental procedures have

been developed for the measurement of boron as a negative ion as work continues on developing the

necessary sample preparation procedures.

The actual certification for chemical composition on a marketable

standard is carried out as a WCF project. Once again, analyses were carried

out on approximately 70 different SRMs covering a wide variety of matrices

including metals, fossil fuels, foods, glasses and environmental materials.

In many cases, each certification involves several or all of the Groups in

the Division and can require 20-30 individual analyses on each SRM. Examples

of the SRMs worked on during the past year are listed below:

60
Standard Reference Materials Analyzed During FY85

SRM Number Title

1645a

97a

98a

1616, 1617

1621c, 1622c

88b

2031

930d

2123-2128

2677

2415-2418

1761-1767

1295-1296

1255-1256

Cl 248

C2423-C2425

C2423a-C2425a

7g

1871-1873

2030

1567a, 1568a

2694

1549

2695, 2696

1632b

2423

120c

2689-2691

1 638b

332

1261-1265

River Sediment

Flint Clay

Plastic Clay

Kerosene

Residual Fuel Oil

Dolomitic Limestone

Metal on Quartz Filters

Glass Filters for Spectrometry

Spectrometric Solutions

Be/As on Filter Media

High Purity Lead

Low alloy Steels

Ferritic Stainless Steel

Aluminum Alloys

Cast Monel

Alloy Cast Irons

Cast Iron

Microchemical Standards

Neutral Glass Filter

Rice and Wheat Flours

Simulated Rain

Powdered Milk

Fluoride in Vegetation

Coal

Ductile Iron

Phosphate Rock

Fly Ash

Reference Fuel

Copper Concentrate

Boron in Low Alloy Steels

Additional elements were determined this year in some SRMs which were originally certified during FY84. These materials include coal, fuel oil and

milk powder. In addition, test samples were collected and analyzed for the

replacement River Sediment SRM, carbon was determined by gas fusion in nine

biological SRMs in which this element had not previously been determined, and

work was started on the replacements for the rice flour and wheat flour SRMs.

A number of new materials for which certification analyses were started

this year include kerosene, simulated rainwater, fluoride in vegetation, and

Be/As on Filter Media.

61
C. Outputs and Interactions

(Inorganic Analytical Research Division)

1 . Publications

Barnes, I. L. , Gills, T. E. , and Reed, W. P. , Copper Standard Reference

Materials (Benchmark Series), Sampling and Analysis of Copper Cathodes , W. M. Tuddenham and R. J. Hibbeln, eds., ASTM Special Technical

Publication No. 831, (1984).

Becker, D. A., Quality Assurance Techniques for Activation Analysis,

Proceedings Fifth International Conference on Nuclear Methods in

Environmental and Energy Research , U.S. DOE Publ . C0NF-840408, U.S.

Dept, of Energy, Washington, DC (1984).

Blackman, M. J., Provenience Studies of Middle Eastern Obsidian from Sites

in Highland Iran, Archaeological Chemistry III , Joseph Lambert, ed.,

American Chemical Society, Washington, D.C. (1984).

Burke, R. W., Mavrodineanu , R. , and Smith, M. V. , Standard Reference

Materials for Verifying the Accuracy of Spectrophotometers, American

Clinical Products Review and American Laboratory, 12-20 (1984).

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

of the Isotopic Abundance Sensitivity of Mass Spectrometry by DopplerFree Resonance Ionization, Resonance Ionization Spectroscopy 1984 , G.

H. Hurst, M. G. Payne, eds., The Institute of Physics, Bristol, 107-117

(1984).

DeBievre, P. J., Gallet, M., Hendrickx, F., Lycke, W., Wolters, W. H.

,

Eberhardt, K. R., Fassett, J. D., Gramlich, J. W., Machlan, L. A.,

Maimka, E. , and Wertenbach, H. , The IDA-80 Measurement Evaluation

Programme on Mass Spectrometric Isotope Dilution Analysis of Uranium and

Plutomium; Volume II: Preparation, Characterization and Transport of

the Test Samples , KfK 3761 /EUR 7991e (1984).

DeBievre, P. J., Gallet, M., Holden, N. E., and Barnes, I. L., Isotopic

Abundances and Atomic Weights of the Elements, J. Phys . Chem. Ref. Data

V3, 809-891 (1984).

Diamondstone , B. I., Wise, S. A., and Sander, L. C., Carbon Analysis for the

Study of Bonded Phases in Liquid Chromatography, J. Chrom., (321),

319-324 (1984).

Downing, R. G., Fleming, R. F. , Maki , J. T. , Simons, D. S. , and

Stallard, B. R., Near-Surface and Interfacial Profiling by Neutron

Depth Profiling (NDP) and Secondary Mass Spectrometry (SIMS), Proc

.

of Materials Research Society, Thin Films and Interfaces II , Vol. 25,

J. E. Baglin, D. R. Campbell, and W. K. Chu , eds., North Holland,

655-666 (1984).

Fassett, J. D., Powell, L. J., and Moore, L. J., Determination of Iron in

Serum and Water by Resonance Ionization Isotope Dilution Mass

Spectrometry, Anal. Chem., 56, 2228-2233 (1984).

62
Fassett, J. D., Travis, J. C., and Moore, L. J., Thermal Atomization Sources

and Resonance Ionization Mass Spectrometry (RIMS), Applications of

Laser Chemistry and Diagnostics , A. B. Harvey, ed., Proc . SPIE 482 , 36-^3 (1984)

.

Greenberg, R. R. , Radiochemical Procedures Used for Improved Low-Level

Determinations of Critical Elements in Biological Materials, Use and

Development of Low and Medium Flux Research Reactors, Supplement to

Atomkernenergie-Kerntechnik 44_, 659 ( 1 984).

Greenberg, R. R. and Carpenter, B. S., High Accuracy/High Precision

Determination of U-235 in Nondestructive Assay Standards by Gamma-Ray

Spectrometry, Proc. Fifth Inti. Conf. on Nuclear Methods in

Environmental and Energy Research , 644 (1984).

Greenberg, R. R., Multielement Analysis of NBS Coals by Instrumental Neutron

Activation Analysis, Methods and Procedures Used at the National Bureau

of Standards to Certify Sulfur in Coal SRM's for Sulfur Content,

Calorific Value, Ash Content , T. E. Gills, ed., NBS Spec. Publ. 260-94,

32 (1984).

Greenberg, R. R. , Fleming, R. F. , and Zeisler, R. , High Sensitivity Neutron

Activation Analysis of Biological/Environmental Standard Reference

Materials, Environ. Intern., 1_0, 129-1 36 ( 1 984).

Kelly, W. R. and Paulsen P. J., Precise and Accurate Determination of High

Concentrations of Sulfur by Isotope Dilution Thermal Ionization Mass

Spectrometry, Talanta, 3J_, 1063-1068 ( 1 984).

Kelly, W. R. and Paulsen P. J., Determination of Sulfur in NBS Coals by

Isotope Dilution Thermal Ionization Mass Spectroscopy, Methods and

Procedures Used at the National Bureau of Standards to Certify Sulfur in

Coal SRMs for Sulfur Content, Calorific Value, Ash Content , T. E. Gills,

ed., NBS Spec. Publ. 260-94 (1984).

Kingston, H. M. and Greenberg, R. R. , An Elemental Ratioing Technique for

Assessing Concentration Data from a Complex Water System, Environ.

Intern. \0 , 153 (1984) .

Kingston, H. M., Paulsen, P. J. , and Lambert, G. M., The Determination of

Selenium and Tellurium in Stainless Steel, White Cast Iron, and Nickel

Base Alloy Standard Reference Materials by Isotope Dilution Spark Source

Mass Spectrometry, Appl . Spectrosc., 3 &_, 385 ( 1 984).

Koch, W. F., Marinenko, G., and Wu, Y. C., The Development of Reference

Materials for Acid Rain Research, Environ. Intern., 1_0, 1 17-121 (1984).

Koch, W. F. and Stolz, J. W., Determination of Sulfur in NBS Coals by Ion

Chromotography , Methods and Procedures Used at the National Bureau of

Standards, to Certify Sulfur in Coal SRMs for Sulfur Content,

Calorific Value, Ash Content , T. E. Gills, ed., NBS Spec. Publ. 260-94

1-6 (1 984).

63
Lutz, G. J. f Rook, H. L. , and Lindstrom, R. M., Determination of 1-129 at

Natural Levels by Thermal Neutron Activation Analysis, Journal of Trace

and Microprobe Techniques, 2 (1), 33~51 (1984).

Michel, R., Iyengar, G. V., and Zeisler, R., Current Aspects of Multielement

Analysis in the Life Sciences, Proc. Symp. Instrumental Multielement

Analysis , Julich, FRG, April 2-5, (1984).

Moody, J. R., New Developments in Laboratory Design in the USA, Chapter 6 in

Design, Construction and Refurbishment of Laboratories , R. Lees, and

A. F. Smith, eds., Ellis Horwood Ltd, Chichester, UK (1984).

Moore, L. J. , Fassett, J. D., and Travis, J. C., Systematics of Multielement

Determination with Resonance Ionization Mass Spectrometry and Thermal

Atomization, Anal. Chem., 56_, 2770-2775 (1984).

Moore, L. J., Kingston, H. M., Murphy, T. J., and Paulsen, P. J., The Use

of Isotope Dilution Mass Spectrometry for the Certification of Standard

Reference Materials, Environ. Intern., 1_0» 169-73 (1984).

Powell, L. J., Murphy, T. J., and Gramlich, J. W., A New Determination of

the Atomic Weight of Silver and an Improved Value for the Faraday, NBS

Spec. Publ . 617, 357-8 (1984).

Powell, L. J. and Murphy, T. J. , How Do You Know That's the Atomic Weight?

Chem. Tech., 1_4, 726-730 ( 1984).

Pratt, K. W., Chronoamperometric Determination of Diffusion Layer

Thicknesses at Hydrodynamic Electrodes, Anal. Chem., 56_, 1967-1970

(1984).

Rains, T. C., Watters, R. L. Jr., and Epstein, M. S., Application of Atomic

Absorption and Plasma Emission Spectroscopy for Environmental Analysis,

Environ. Intern., 1_0, 163-168 (1984).

Riley, J. E. Jr., Mitchell, J. W., Downing, R. G., Fleming, R. F., Lindstrom,

R. M., and Vincent, D. H. , Materials Analysis Using Thermal Neutron

Reactions: Applications, Materials Science Forum 2, 123-132 (1984).

Stone, S. F. and Zeisler, R., Evaluation of Biological Samples for Specimen

Banking and Biomonitoring by Nuclear Methods, Proc. 5th Conference on Nuclear Methods in Environment and Energy Technology , J. R. Vogt, ed.,

NT IS U.S. Dept, of Commerce, Springfield, VA, C0NF-840408 (1984).

Wilson, S. R. , Paulson, W. M., Gregory, R. B. , Krause, R. J., Gressett,

J. D., McDaniel, F. D., and Downing, R. G., Properties of Ion Implanted

Polysilicon Layers Subjected to Rapid Thermal Annealing, Journal of the

Electrochemical Society; Solid State Science and Technology, 1 32 (4),

922-929 (1984).

Wise, S. A. and Zeisler, R. , The Pilot Environmental Specimen Bank Program,

Environ. Sci. Technol . , 1_8, 302A-307A ( 1984).

Wu , Y. C., Koch, W. F., and Marinenko, G., A Report on The National Bureau

Of Standards pH Standards, J. Res. NBS 89, 395-400 (1984).
Blackman, M. J., The Provenience of Obsidian Artifacts from Late

Chalcolithic Levels at Aphrodisias, Turkey, Prehistoric Aphrodisias , M.

Joukowsky, ed . , Archaeologia Transatlantica , IV Louvain-la-Neuve

,

Institut Superieur D’Archelogie et Histoire de L’Art, Brown University

(1985).

Blackman, M. J., Chemical Characterizations of Sealing Clays from Fourth

Millenium B.C. Sites in Iran, in The Transactions of the American

Nuclear Society, 49_, 168-169 (1985).

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

of Autoinizing States of Beryllium by Resonance Ionization Mass

Spectrometry, J. Opt. Soc . Am. B, 2, 891-896 (1985).

DeBievre, P. J. and Barnes, I. L., Table of the Isotope Composition of the

Elements as Determined by Mass Spectrometry, Int. J. Mass Spect., Ion

Process, 65, 211-230 (1985).

Gramlich, J. W. and Machlan, L. A., Isotopic Variations in Commercial

High-Purity Gallium, Anal Chem., 57_, 1788-1790 (1985).

Jornet, A., Blackman, M. J., and Olin, J. S., Xlllth to XVIIIth Century

Ceramics from the Paterna-Manises Area (Spain), Ceramics and

Civilization , D. Kingery, ed., American Ceramic Society (1985).

241 Kelly, W. R. , On the Precise and Accurate Determination on the Pu

Half-life by Mass Spectrometry, Int. J. Mass Spect., Ion Process, 64 , 85-90 (1 985).

Lindstrom, R. M . and Anderson, D. L. , Analytical Neutron-Capture Gamma-Ray

Spectroscopy: Statues and Prospects, Capture Gamma-Ray Spectroscopy

and Related Topics-1984 , S. Raman, ed., (AIP Conf . Proc. No. 125), Am.

Inst. Physics, New York, 810-819 (1985).

Marinenko, G. and Koch, W. F. , A Critical Review of Measurement Practices

for the Determination of pH and Acidity of Atmospheric Precipitation,

Environ. Intern., 1_0, 31 5-31 9 (1 985).

Marinenko, G. and Koch, W. F. , Evaluation of Methods for the Determination

of Acidity in Acid Rain Samples , National Bureau of Standards, NBSIR

85-31 1 4 (1 985).

Messraan, J. D., O’Haver, T. C., and Epstein, M. S. , Evaluation of a DirectCurrent Argon Plasma as a Primary Pseudocontinuum Radiation Source for

Wavelength-Modulated Atomic Absorption Spectrometry, Anal. Chem., 57,

416-420 (1985).

Moody, J. R. , Sampling, Storage and Handling of Materials for Trace Elements

Analysis, Sample Preparation Technology, Zymark Corp, Hopkinton, MA

(1 985).

Myers, J. E. and Blackman, M. J., Conical Plates from Medieval Qsar

es-Seghir, The Proceedings of the Third International Congress on Medieval Ceramics (1985).

65
Stroube , W. B. and Lutz, G. J. , Epithermal Neutron Activation Analysis of

Powdered Infant Formula for Iodine, Trans. Amer . Nucl . Soc., 49_, 164-165

(1985).

Tanaka, T., Marinenko, G., and Koch W. F. , Further Developments in the High

Precision Coulometric Titration of Uranium, Talanta, 32, 525-530 (1985).

Turk, G. C. and Watters, R. L. Jr., Resonant Laser-Induced Ionization of

Atoms in an Inductively Coupled Plasma, Anal. Chem., 57, 1979-1983,

(1 985).

Weidner, V. R. , Mavrodineanu, R. , Mielenz, K. D., Velapoldi, R. A., Eckerle,

K. L., and Adams B., Spectral Characteristics of Holmium Oxide in

Perchloric Acid Solution, J. of Res. NBS 90., No. (2), 1 15-125 (1985).

Barnes, I. L., Brill, R. H. , Deal, E. C., and Piercy, G. V., Lead Isotope

Studies of Some of the Finds from the Serce Liman Shipwreck, Proc. 1984

Symposium on Archaeometry , J. S. Olin and M. J. Blackman, eds.,

Smithsonian Institution, Washington, DC, in press.

Barnes, I. L. , Deal, E. , Chase, W. T. , Holmes, L. , Myers, P. , and Sayre,

E. V., The Nine Tripods and the Six Formulas: Lead and Lead Isotope

Ratios in Ancient Chinese Bronzes, Proc. 1984 Symposium on Archaeometry,

J. S. Olin and M. J. Blackman, eds., Smithsonian Institution,

Washington, DC, in press.

Barnes, I. L. , Brill, R. H. , and Deal, E. C., Lead Isotope Studies of Early

Chinese Glasses, Proc. Symposium on Ancient Glass and Glass Making , Beijing, August 27 — 3 1 »

1 984, Special Publication, American Ceramic

Society, in press.

Becker, D. A., The Role of Reactor Characterization in NBS Quality

Assurance, Journal of Radioanalytical and Nuclear Chemistry, in press.

Brill, R. H. and Barnes, I. L. , Examination of Some Glasses from Timna,

Proc. Symposium on Examination of Objects from the Timna Excavation , B. Rothenberg , ed . , The University Press, Athens, in press.

Downing, R. G., Maki , J. T. , and Fleming R. F. , Application of Neutron Depth

Profiling to Microelectronic Materials Processing, Special Proceedings

of the Industrial Chemical Division Session for the 187th National

Meeting of the American Chemical Society , L. A. Casper, ed., in press.

Fassett, J. D. and Kingston, H. M., Determination of Nanogram Quantities of

Vanadium in Biological Material by Isotope Dilution Thermal Ionization

Mass Spectrometry with Ion Counting Detection, Anal. Chem., in press.

Fassett, J. D., Moore, L. J. , Travis J. C., and DeVoe, J. R. , Laser

Resonance Ionization Mass Spectrometry, Science, in press.

Imbalzano, J. F. and Moody, J. R. , Preliminary Studies of the Effects of

Semiconductor Reagents on Polymers Containing Fluorine and of Trace

Metallic Leachated from Molded Fluorocarbon Resin, J. Environ. Science

1985, in press.

66
Vandervost, W., Shepherd, F. R. , and Downing, R. G., High Resolution SIMS

and Neutron Depth Profiling of B through Oxide-Silicon Interfaces, J. of

the Amercian Vacuum Society, Sci. Technol., A3 (3), 1318-1321 (1985).

Koch, W. F. , ed., Direct Potentiometric Measurements in Blood, Proceedings

of the Workshop on Direct Potentiometric Measurements in Blood , Gaithersburg, MD, May 18-20, 1983, National Committee for Clinical

Laboratory Standards, Villanova, PA, in press.

Lindstrom, R. L., Activation Analysis of Semiconductor Materials, in ACS

Books, in press.

Michael, R. , Iyengar, G. V., and Zeisler, R. , Current Aspects of

Multielement Analysis in the Life Sciences, Proc . Symp. Instrumental

Multielement Analysis , Julich, FRG, April 2-5, 1985, in press.

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

C. W., Resonance Ionization Mass Spectrometry of Carbon, J. Opt. Soc.

Am. B, in press.

Pratt, K. W. and Koch, W. F. , Determination of Trace-Level Cr(VI) in the

Presence of Cr(III) and Fe(III) by Flow-Injection Amperometry without

Prior Separation, Anal. Chem., in press.

Sams, R. L. and Fried, A., Potential Sources of Systematic Errors in Tunable

Diode Laser Absorption Measurements, Appl . Spect., in press.

Stroube, W. B. and Lutz, G. J., Determination of Iodine in Liquid Infant

Formula by Epithermal Neutron Activation Analysis, in press.

Velapoldi, R. A. and Burke, R. W., Recommended Reference Materials for

Realization of Physicochemical Properties: Wavelength and Transmittance, IUPAC Commission on Physicochemical Measurements and Standards,

in press.

Burke, R. W., Smith, M. V., Powell, L. J. , and Mavrodineanu, R. , Performance

Characteristics of NBS Glass and Metal-on-Quartz Transmittance

Standards, submitted for publication.

Diamondstone , B. I. and Gauer, R. C., Total Carbon Determinations in

Biological Materials, submitted for publication.

Fried, A. and Sams, R. L., Tunable Diode Laser Absorption Spectrometry for

Ultra-Trace Measurement and Calibration of Atmosphere Constituents,

submitted for publication.

Koch, W. F., Marinenko, G., and Paule, R, C., Development of an SRM for

Rainwater, J. Res. NBS, submitted for publication.

Koch, W. F., Marinenko, G., and Paule, R. C., An Interlaboratory Test of pH

Measurements in Rainwater, J. Res. NBS, submitted for publication.

Leifer, R. , Juzdan, Z. R. , Kelly, W. R. , and Fassett, J. D., Detection of

Cosmos-1 ^02 in the Stratosphere, submitted for publication.

67
Paule, R. C., Marinenko, G., Knordel, M., and Koch, W. F. , Ruggedness

Testing I: Theory and Statistical Experiment Design, J. Res. NBS,

submitted for publication.

Paule, R. C., Marinenko, G., Knordel, M., and Koch W. F. , Ruggedness Testing

II: Practical Application to pH Measurements in Rainwater, J. Res. NBS,

submitted for publication

Marinenko, G., Paule, R. C., and Koch, W. F., Ruggedness Testing III:

Multifactor Interactions in Rainwater, J. Res. NBS, submitted for

publication.

Rains, T. C., Reference Materials: Development and Characterization, Pure

App. Chem., submitted for publication.

Syty, A., Christensen, R. G., and Rains, T. C., Trace Determination of

Cr(VI) by LC/AAS with On-line Preconcentration, Atomic Spectroscopy,

submitted for publication.

Wu, Y. C., Koch, W. F. , and Marinenko, G., Thermodynamic Properties of DC1

in D

2 O Solution, (0.002 to 1m) from 5 to 50 °C, J. Soln. Chem, submitted

for publication.

Wu, Y. C. and Koch, W. F. , The First and Second Dissociation Constants of

Deuterio-o-phthal ic Acid in D

2 0 from EMF Measurements from 5 to 50 °C,

J. Soln. Chem., submitted for publication.

2. Talks

Pratt, K. W. and Koch W. F. , "Electrochemical Flow-Injection Analysis Using

Vibrating Electrodes: Application to the Determination of Cr(V_I)," 27th

0RNL/D0E Conference on Analytical Chemistry in Energy Technology,

Knoxville, TN, October 2, 1984.

Marinenko, G. and Koch, W. F. , "Evaluation of Acidity and pH Measurements

for Acid Rain Studies," 1 66th Meeting of the Electrochemical Society,

New Orleans, LA, October 9, 1984.

Fleming, R. F., "Analysis of Materials Using Neutron Beam Techniques,"

Institute for Materials Research Seminar, McMaster University, Hamilton,

Ontario, Canada, October 15, 1984.

Elkins, J. W. and Sams, R. L. , "Current Laboratory Spectroscopy Techniques

by FT-IR," NASA Langley Research Center Spectroscopic Parameters

Workshop, Hampton, VA, October 17, 1984.

Downing, R. G., "Nondestructive Depth Profiles of Light Elements by Neutron

Depth Profiling," Kodak Laboratories, Rochester, NY, October 25, 1984.

Invited

Moody, J. R. , "Chemical Methods for Improved Precision and Sensitivity in

Trace Metal Analysis," Baltimore-Washington Section of the Society for

Applied Spectroscopy, Gaithersburg, MD, October 25, 1984. Invited

68
Epstein, M. S. , "DC Plasma Emission/Laser-Excited Atomic Fluorescence

Spectrometry," 4th NBS-A DBASE Analytical Chemistry Workshop, National

Bureau of Standards, Gaithersburg, MD, November 6, 1984.

Rains, T. C., "State of the Art of Atomic Absorption Spectrometry," 4th

NBS-ADBASE Analytical Chemistry Workshop, National Bureau of Standards,

Gaithersburg, MD, November 6, 1984.

Turk, G. C., "Laser-Enhanced Ionization Spectrometry," 4th NBS-ADABSE

Analytical Chemistry Workshop, National Bureau of Standards,

Gaithersburg, MD, November 6, 1984.

Watters, R. L., Jr., "Atomic Emission Spectrometry," 4th NBS-ADABASE

Analytical Chemistry Workshop. National Bureau of Standards,

Gaithersburg, MD, November 6, 1984.

Barnes, I. L. , "The Atomic Weights of the Elements," 4th NBS-ADBASE

Analytical Chemistry Workshop, National Bureau of Standards,

Gaithersburg, MD, November 7, 1984. Invited

Gramlich, J. W., "Inorganic Mass Spectrometry Applications," 4th NBS-ADABSE

Analytical Chemistry Workshop, National Bureau of Standards,

Gaithersburg, MD, November 8, 1984. Invited

Downing, R. G., "Neutron Beams," Conference on the Use of Small Accelerators

in Research and Industry, Denton, TX, November, 11-15, 1984. Invited

Zeisler, R., "Sampling and Analysis of Human Livers," American Nuclear

Society and European Nuclear Society 1984 International Conference,

Washington, DC, November 13* 1984. Invited

Fassett, J. D., "Resonance Ionization Mass Spectrometry for Elemental

Analysis, Eastern Analytical Symposium, New York, NY, November, 1984.

Invited

Moody, J. R. , "Contamination Control for Laboratory and Manufacturing,"

Comsat Laboratories, Clarksburg, MD, December 6, 1984. Invited

Kingston, H. M., "Microwave Digestion,” CEM Corporation, Indian Head Trail,

NC, December 12, 1984. Invited

Moody, J. R. , "Clean Chemistry for Trace Analysis," Eastman Kodak Research

Laboratories, Rochester, NY, December 17, 1984. Invited

Koch, W. F., "Reference Materials and Methods for the Measurements of pH in

Acidic Precipitation," 1984 International Chemical Congress of Pacific

Basin Societies, Honolulu, HI, December 21, 1984. Invited

Barnes, I. L., "The Shipwreck of Serce Liman - Lead Isotope Studies," Center

for Chemical Physics, Surface Science Division Seminar, National Bureau

of Standards, Gaithersburg, MD, January 8, 1985. Invited

Moody, J. R., "The Application of Clean Room Concepts in Analytical

Chemistry," International Symposium on Artificial Radioactivity,

University of Pune, Pune, India, January 9, 1985. Inv lted

69
Moody, J. R. , "Clean Room Technology: Present and Future for Analytical

Chemistry," Departmental Seminar, Bhabha Atomic Research Centre, Bombay,

India, January 14, 1985. Invited

Moody, J. R. , "The Use and Design of Clean Room and Pure Reagent Facilities

at NBS," Departmental Seminar, National Meteorological Institute,

Tsukuba, Japan, January 22, 1985. Invited

Moody, J. R., "The Use of NBS Clean Rooms in Standard Reference Material

Certification," Departmental Seminar, National Institute for

Environmental Studies, Tsukuba, Japan, January 22, 1985. Invited

Downing, G. R., "Neutron Depth Profiling (NDP) for the Nondestructive

Analysis of Light Elements," Aluminum Company of America, Alcoa,

PA, January 24, 1985. Invited

Kingston, H. M., "Legislative Alternatives in the 99th Congress," Society

for Risk Analysis, McLean, VA, February 8, 1985. Invited

Downing, G. R., "Neutron Depth Profiling: The Technique and Applications,"

University of Missouri-Rolla , Rolla, MO, February 11, 1985. Invited

Rains, T. C., "The Art of Sample Preparation for Atomic Spectroscopy,"

George Washington University, Washington, DC, February 15, 1985.

Invited

Rains, T. C., "Atomic Absorption and Plasma Emission Spectroscopy," ACS

Short Course, 36th Pittsburgh Conference on Analytical Chemistry and

Applied Spectroscopy, New Orleans, LA, February 22-24, 1985.

Fried, A., Sams, R., and Dorko, B. , "Simultaneous Quantitative Tunable Diode

Laser and Chemiluminescent Detector Measurements of High Concentration

N02 in Air Gas Mixtures," 36th Pittsburgh Conference on Analytical

Chemistry and Applied Spectroscopy, New Orleans, LA, February 25-March

1, 1985.

Mo, D. M., Ueda, J., Watters, R. L. , Jr., and Rains, T. C., "Determination

of Molybdenum, Titanium, and Vanadium in Refractory Materials by ICPES,"

36th Pittsburgh Conference, on Analytical Chemistry and Applied

Spectroscopy, New Orleans, LA, February 25, 1985.

Powell, L. J. , Burke, R. W., Smith, M. V., and Mavrodi neanu , R. , "Performance

Characterstics of NBS Glass and Metal-on-Quartz Transmittance

Standards," 36th Pittsburgh Conference on Analytical Chemistry and

Applied Spectroscopy, New Orleans, LA, February 26, 1985.

Turk, G. C., "Applications of Laser-Enhanced Ionization Spectrometry at

NBS," Shell Development Company, Houston, TX, February 26, 1985.

Invited

Fassett, J. D. , "Application of Resonance Ionization Mass Spectrometry to

Elemental Analysis," University of Maryland, College Park, MD,

March 29, 1985. Invited

70
Barnes, I. L. , "Modern Ion Optics," Inorganic Analytical Research Division

Seminar, National Bureau of Standards, Gaithersburg, MD, April 9, 1985.

Invited

Rains, T. C., "Zinc and Selenium Methods Used at NBS," NBS/NCI Micronutrient

Analysis QA Workshop, National Bureau of Standards Gaithersburg, MD,

April 11, 1985.

Moody, J. R. , "Clean Laboratories and Their Use for Trace Metal Analysis,"

Society for Applied Spectroscopy Tour Lecture, Toronto, Canada,

April 15, 1985. Invited

Moody, J. R. , "Chemical Methods for Enhancement of Trace Metal Analysis,"

Society for Applied Spectroscopy Tour Lecture, National Science Foundation, Ottowa, Canada, April 16, 1985. Invited

Moody, J. R., "Chemical Methods for Enhancements of Trace Metal Analysis,"

Society for Applied Spectroscopy Tour Lecture, McGill University,

Montreal, Canada, April 17, 1985. Invited

Moody, J. R., "Ultra-Pure Reagents and Clean Rooms, Their Use in Analytical

Chemistry," Society for Applied Spectroscopy Tour Lecture, Dalhousie

University, Halifax, Canada, April 18, 1985. Invited

Watters, R. L., Jr., "Quality Assurance and Data Reporting," 6th Midwest

Analytical Symposium, Society for Applied Spectroscopy, St. Louis, MO,

April 18, 1985. Invited

Rains, T. C., "Reference Materials: Development and Character i zati on , " 2nd

International Symposium on Analytical Chemistry in the Exploration,

Mining and Processing of Materials, CSIR Conference Centre, Pretoria,

South Africa, April 19, 1985. Invited

Rains, T. C., "The Characterization of Standard Reference Materials by AAS

and ICP," University of Cape Town, Cape Town, South Africa, April 24,

1985. Invited

Rains, T. C., "The Art of Sample Preparation," University of Port Elizabeth,

Port Elizabeth, South Africa, April 26, 1985. Invited

Watters, R. L., Jr., "Quality Assurance and Data Reporting," Professional

Development Program, Bal timore-Washington Section, Society for Applied

Spectroscopy, USDA, Beltsville, MD, April 29, 1985. Invited

Imbalzano, J. F. and Moody, J. R., "Preliminary Studies of the Effects of

Semiconductor Reagents on Polymers Containing Fluorine and of Trace

Metallic Leachate from Molded Fluorocarbon Resin," 31st Annual Meeting

of the Institute for Environmental Science, Las Vegas, NV, May 1,

1985.

Blackman, M. J. and Wright, R. P. , "Technological and Stylistic Changes in

Ceramics from the 4th Millenium B.C. in Highland Iran," 87th Annual

Meeting of the American Ceramic Society, Cincinnati, OH, May 6, 1985.

71
Jornet, A., Blackman, M. J., and Olin, J. S. , "Investigations on PostMedieval Glazed Ware from the Sevilla and Talavera Puente Areas

(Spain)," 87th Annual Meeting of the American Ceramic Society,

Cincinnati, OH, May 6, 1985.

Rains, T. C., "Flame Atomic Absorption Spectrometry," Assay and Weights

Administration, Gamalia, Egypt, May 6-9, 13, 1985. Invited

Wolf, W. R., and Zeisler, R. , "Biomonitoring of Dietary Intakes," 9th

U.S. -German Seminar of State and Planning on Environmental Specimen

Banking, Schloss Reisenburg, FRG, May 13, 1985. Invited

Rains, T. C., "Trace Elemental Analysis by AAS," Egyptian Organization for

Standardization and Quality Control, Cairo, Egypt, May 14, 1985.

Invited

Zeisler, R. and Stoeppler, M., "Intercomparison of Analytical Techniques

Used for the Characterization of Human Livers," 9th U.S-German Seminar

of State and Planning on Environmental Specimen Banking, Schloss

Reisenburg, FRG, May 14, 1985. Invited

Stone, S. F. and Zeisler, R., "Sequential Analysis of 44 Trace Elements in

Marine Bivalves," 9th U.S. -German Seminar of State and Planning on Environmental Specimen Banking, Schloss Reisenburg, FRG, May 15, 1985.

Invited

Imbalazano, J. F. , and Moody J. R. , "The Effect of Selected Aqueous

Semiconductor Reagents on Commercial Piping of Perfluoroalkoxy Fluorocarbon Resin and of Ethylene-Chlorotrifluoro Ethylene Fluoropolymer

Resin, Millipore Corporation Technical Symposium, San Mateo, CA, May 20,

1 985.

Rains, T. C., "Application of Electrothermal Atomization Atomic Absorption

Spectrometry," Professional Development Program for Scientists,

Baltimore-Washington Section of Society for Applied Spectroscopy,

Department of Agriculture, Beltsville, MD, May 20, 1985. Invited

Vetter, T. W. and Diamondstone, B. I., "Affect of Accelerator on Sulfur

Determination in Low Sulfur Ductile Iron," 19th Middle Atlantic Regional

Meeting, American Chemical Society, Monmouth College, West Long Branch,

NJ, May 21 , 1985.

Imbalazano, J. F. and Moody, J. R. , "The Effect of Selected Aqueous

Semiconductor Reagents on Commercial Piping of Perfluoroalkoxy Fluorocarbon Resin and of Polyvinyldene Difluoride Fluoropolymer ," Semicon

West San Mateo, CA, May 22, 1985.

Zeisler, R. , "Applications of Instrumental Neutron Activation Analysis in

Biological Research," Mini-Symposium on Neutron Activation Analysis and

Trace Element Research in Biology and Medicine, Studsvik Energiteknik,

Nykoping, Sweden, May 23, 1985. Invited

72
Fassett, J. D. f "Observation of New States of Beryllium by Resonance

Ionization Mass Spectrometry," 33rd Annual Conference of the American

Society for Mass Spectrometry and Allied Topics, San Diego, CA,

May 27, 1985.

Paulsen, P. J. and Beary, E. S. , "Selenium Isotopic Ratio Measurements from

ASSE

+ Ions Generated with SEO^, As

+

^ Loaded Silica Gel," 33rd Annual

Conference of the American Society for Mass Spectrometry and Allied

Topics, San Diego, CA, May 29, 1985.

Fassett, J. D., Kelly, W. R., Leifer, R., and Judzan, J. R., "Detection of

the Atomspheric Burnup of the Cosmos 1402 Satellite by Thermal Ionization Mass Spectrometry," 33rd Annual Conference of the American Society

for Mass Spectrometry and Allied Topics, San Diego, CA, May 28, 1985.

Downing, R. G., "Near-Surface Analysis of Light Elements by Neutron Depth

Profiling," Aluminum-Lithium Workshop, Hidden Valley, PA, June 5, 1985.

Invited

Greenberg, R. R. and Carpenter, B. S. , "High Accuracy Determination of U-235

Abundances in Nondestructive Assay Standards by Gamma Spectrometry,"

International Symposium on Nuclear Analytical Chemistry, Halifax,

Canada, June 5, 1985. Invited

Becker, D. A, "The Role of Reactor Characterization in NAA Quality

Assurance," the International Symposium on Nuclear Analytical Chemistry,

Dalhousie University, Halifax, Canada, June 6, 1985.

Zeisler, R., "Advances in Instrumental Neutron Activation Analysis of

Biological Materials," International Symposium on Nuclear Analytical

Chemistry, Dalhousie University, Halifax, Canada, June 6, 1985.

Invited

Wu, Y. C. and Koch, W. F. , "The First and Second Dissociations Constants of

Deuterio-o-ph 1 ati'c Acid in D

2 0 from EMF Measurements from 5 to 50 °C,"

Conference on Electrolyte Solutions, National Bureau of Standards,

Gaithersburg, MD, June 11, 1985.

Zeisler, R. , "The Determination of Trace Elements in Biological

Macroraolecules by Neutron Activation Analysis," American Nuclear Society

1985 Annual Meeting, Boston, MA, June 11, 1985. Invited

Fleming, R. F., "An Assessment of the Induced Radioactivity in Foods Using

Isotopic Gamma-Ray Sources," American Nuclear Society 1985 Annual

Meeting, Boston, MA, June 13, 1985. Invited

Moody, J. R., "The Selection of Materials for Ultra-Pure Water Systems,"

Mill'ipore Corporation Symposium on High Purity Water, Bedford, MA,

June 20, 1985. Invited

Klouda, G. A., Currie, L. A., Tompkins, G. B. , Wise, S. A., and Diamondstone

,

B. I., "Reference Materials and Blank Evaluation Techniques for 1 t

Measurements on Small Aerosol Samples," 12th International Radio Carbon

Conference, Trandhiem, Norway, June 24, 1985.

73
Barnes, I. L. , "The Analysis of Carbon Dioxide," The Summer Seminar of the

Center for Analytical Chemistry, National Bureau of Standards,

Gaithersburg, MD, July 25, 1985. Invited

Downing, R. G., "Light Element Profiling in Electronic Materials," Aerospace

Corporation, Los Angeles, CA, July 25, 1985. Invited

White, V. E., Welch, M. L., Pereles, D. J., and Sams, R. L., "Laser

Photodissociation of Ions from Soft Ionization Techniques," 10th

International Mass Spectrometry Conference, Swansea, U.K., September

9-1 2, 1985.

Koch, W. F. , "The Development of a Standard Reference Material for Wet

Deposition," Review Meeting of the National Acid Precipitation

Assessment Program, Boulder, CO, September 10, 1985.

Turk, G. C., Ruegg, F. C., Travis, J. C., and DeVoe, J. R., "ThreeDimensional Atomic Spectra in Flames Using Using Stepwise Excitation

Laser-Enhanced Ionization Spectroscopy," CSI XXIV, GarmischPartenkirchen , FRG, September 20, 1985.

Butler T. A., Rush, T. A., and Rains, T. C., "Determination of Trace

Elements in Coal by Atomic Absorption and Inductively Coupled Plasma

Spectrometry," 12th Annual Meeting of the Federation of Analytical

Chemistry and Spectrometry Societies, Philadelphia, PA, September 30,

1 985.

Rains, T. C., "The Art of Sample Preparation," 12th Annual Meeting of the

Federation of Analytical Chemistry and Spectroscopy Societies,

Philadelphia, PA, September 30, 1985.

Zhang, Y. Z., Watters, R. L., Jr., and Rains, T. C., "Determination of

Phosphorus in Refractory Materials by Inductively Coupled Plasma Atomic

Emission Spectrometry," 12th Annual Meeting of the Federation of

Analytical Chemistry and Spectroscopy Societies, Philadelphia, PA,

September 30, 1985.

3. Committee Assignments

I. Lynus Barnes

Member, Department of Health, Education, and Welfare, Chemistry Task

Force of the National Shellfish Sanitation Program

Washington Editorial Review Board

International Union of Pure and Applied Chemistry, Commission of

Atomic Weights and Isotopic Abundances

Chairman, IUPAC, Commission on Atomic Weights and Isotopic Abundances,

Working Group on Statistics Applied to Atomic Weights
Donald A. Becker

Member, ASTM E-10, Nuclear Technology and Applications

ASTM E-10.05, Nuclear Radiation Metrology

ASTM D-1 9, Water

ASTM D— 19.01 , Statistical Methods

ASTM D-1 9.02, General Specification and Technical Resources

ASTM D-1 9. 03 , Sampling of Water and Water-Formed Deposits, and

Surveillance of Water

ASTM D-19.04, Methods of Radiochemical Analysis

ASTM D-1 9.05, Inorganic Constituents in Water

ASTM D-1 9.07, Sediments

ASTM D-1 9. 33, Water Associated with Synthetic Fuel Production

Member, ANS, Activation Analysis Committee, Isotopes and Radiation

Division

Member, ANS, Trace Element Analysis Committee, Technical Group on Biology and Medicine

Chairman, ASTM E-10. 05. 12, Task Group on Nuclear Methods of Chemical

Analysis

Ellyn S. Beary

Member, Inorganic Analytical Research Division Safety Committee

Robert W. Burke

Member, ASTM E-03, Chemical Analysis of Metals

ASTM D-34, Standards for Waste Characterization

Theresa A. Butler

Secretary, Balti more-Washi ngton Section of the Society for Applied

Spectroscopy

Member, Inorganic Analytical Research Division Safety Committee

Barry I. Diamondstone

Member, ASTM D-34, Waste Disposal

ASTM D-34.02.01, Section on Batch Extractions

ASTM E-03, Chemical Analysis of Metals

ASTM E-03. 01, Gases in Metals

ASTM E-03* 93, Long Range Planning

Chairman, Task Force on Oxygen in Metals

Robert G. Downing

Member, ASTM E-10, Nuclear Methods for Chemical Analysis

Member, Inorganic Analytical Research Division Seminar Committee

Chairman, Inorganic Analytical Research Division Safety Committee

Michael S. Epstein

Member, ASTM D-1 9, Water

Editorial Advisory Board, Progress in Analytical Atomic

Spectroscopy

Treasurer, National Society for Applied Spectroscopy

Chairman, Baltimor e-Washington Section of the Society for Applied

Spectroscopy

Executive Secretary, Review Committee, Society for Applied Spectroscopy

75
Ronald F. Fleming

Member, ASTM E-10.05, Nuclear Radiation Metrology

ASTM E-10.07, Radiation Effects on Materials

Organization Committee, Sixth Symposium on X- and Gamma-Ray

Sources and Applications

John W. Gramlich

Member, Institute of Nuclear Materials Management Committee N1 5.9.3,

Non-Destructive Assay (Physical Methods)

Robert R. Greenberg

Member, ASTM E-10.05, Nuclear Radiation Metrology

Member, NBS Chemistry Storeroom Committee

Member, ANS, Trace Analysis Committee, Technical Group for Biology and

Medicine

Howard M. Kingston

Member, ASTM C-26.05, Methods of Test

ASTM C-26.07, Waste Materials

Task Group Leader, C-26.05, Leachate Analysis Methods

Technical Consultant, Congressional Science and Technology Committee

William F. Koch

Member, ASTM D-19, Water

ASTM D-19. 02, General Specifications and Technical Resources

ASTM D-19.05, Inorganic Constituents in Water

ASTM D-22, Air

Personnel Officer, NBS Child Care Association, Board of Directors

John K. Langland

Chairman, NBS Electronics Storeroom Committee

Richard M. Lindstrom

Alternate Member, NBSR Safety Evaluation Committee

Lawrence A. Machlan

Member, ASTM C-26, Nuclear Fuel Cycles

ASTM C-26.05, Test Methods

ASTM C-26. 01 , Editorial and Terminology

George Marinenko

Member, ASTM D-19, Water

Chairman, D-1 9.05.04.03, Voltammetry

D-19. 09. 06, Redox Potentials in Saline Water

D-1 9.09.07, pH in Saline Water and Brines

D-19. 09.01, Chlorine Residuals in Saline Water

Councilor, National Capital Section of the Electrochemical Society

First Vice-Chairman, National Captial Section of the Electrochemical

Society

76
John R. Moody

Member, ASTM D— 19, Water

ASTM D-19.05, Inorganic Constituents in Water

Chemical Society of Washington, Audit Committee

Contamination Control Standards and Practices for Federal Standard

209c, Institute for Environmental Sciences

Delegate, Society for Applied Spectroscopy

Representative, FACSS Governing Board

Chairman, Society for Applied Spectroscopy, Video Short Course Committee

Thomas J. Murphy

Member, American Chemical Society Committee on Analytical Reagents

American Chemical Society Committee on Meetings and Expositions

Member, International Union of Pure and Applied Chemistry (IUPAC),

Commission on Atomic Weights and Isotopic Abundances

Member, American Chemical Society, Admissions Committee

Chairman, Chemical Society of Washington, Audit Committee

Councilor, Chemical Society of Washington

John A. Norris

Member, ASTM E-02, Emission Spectroscopy

ASTM E-02. 02, Statistics

ASTM E-02.0M, Sampling and Standards

ASTM E-02. 05, Copper, Cobalt, Nickel, and High Temperature

ASTM E-02. 06, Lead, Tin, Zinc

ASTM E-02. 07, Aluminum

ASTM E-02. 08, Refractory Metals

ASTM E-02. 09, Ferrous

ASTM E-02. 13, Terminology

Member, Joint Committee on Atomic and Atomic and Molecular Physical Data

Chairman, ASTM E-02. 01, Fundamental Practices

Representative, Society for Applied Spectroscopy

Lura J. Powell

Member, Chemical Society of Washington

Board of Directors, NBS Child Care Association

Chairman, American Society for Mass Spectrometry, Committee on Isotope

Ratio Measurements

Treasurer, Chemical Society of Washington

President, Standards Committee for Women

Kenneth W. Pratt

Secretary, National Capital Section of the Electrochemical Society

Member, NBS Inorganic Analytical Research Division Safety Committee

Member, Inorganic Analytical Research Division Seminar Committee

Theodore C. Rains

Member, Proposal Evaluation Committee for National Science Foundation

Editorial Board of Annual Reports on Analytical Atomic Spectroscopy (The Chemical Society of London) and the Canadian Journal of

Spectroscopy

Subcommittee No. 6 on Methods of Air Sampling and Analysis

ASTM E-02. 10, Non-Metallic Materials

ASTME-02.13, Nomenclature

77
ASTM D-01 , Paint and Related Coatings

ASTM D-1 9 , Water

Past-Chairman, FACSS Governing Board

Professor-in-Charge, ACS Short Course on Atomic Absorption and Plasma

Emission Spectroscopy

Task Force Leader, Scientific Instrumentation Information Network and

Curricula (SUNG) for project on "Atomic Absorption Spectroscopy"

Column Editor, Journal of Applied Spectroscopy

Ronald W. Shideler

Member, NBS Electronics Storeroom Committee

John C. Travis

,

Chairman, Analytical Laser Ionization Spectrometry

Thomas W. Vetter

Member, ASTM E-02, Emission Spectroscopy

ASTM E-02. 02, Statistics

ASTM E-02. 04, Sampling and Standards

ASTM E-02. 06, Lead, Tin, Zinc

ASTM E-02. 07, Aluminum

ASTM E-02. 09, Ferrous

ASTM E-03, Chemical Analysis of Metals

ASTM E-03. 01, Ferrous

ASTM E-03. 91 , Editorial

ASTM E-03. 92, Standards

Chairman, ASTM E-03. 01 , Task Group on Low Concentration of Sulfur in

Cast Iron, Combustion Method

Yung-Chi Wu

Member, ASTM D-1 9, Water

Rolf L. Zeisler

Member, NBSR Safety Evaluation Committee

Chairman, ANS, for Trace Element Analysis Committee, Technical Group for

Biology and Medicine

4. Other

a. Seminars

October 15, 1984 - Dr. David W. Crawford, New Brunswick

Laboratory, "The Utilization of Mass

Spectrometry in a Nuclear Material

Laboratory ."

October 15, 1984 - Mr. John S. Beaty, Allied Analytical

Systems, "Uses of a Finely Divided Metal

Aerosol ."

November 29, 1 984 - Dr. R. Ganapathy, J. T. Baker Chemical

Company, "Major Meterotie Impacts on the

Earth ."

78
January 9, 1985 Professor 0. K. Manual, University of

Missouri, "Chemical and Isotopic Heterogeneities in the Sun and its Planetary System:

Remnants of Local Element Synthesis."

January 29, 1985 - Professor Richard D. Sacks, University of

Michigan, "Direct Determination of

Metallic Elements in Solid Powder Samples

Using Magnetically Tailored Plasmas from

Electrically Vaporized Thin Metal Films."

February 11, 1985 - Professor Nicholas Winograd, Pennsylvania

State University, "Surface and Solids

Characterization by Multiphoton Resonance

Ionization of Sputtered Atoms."

March 15, 1 985 - Dr. Jacques P. Guertin, Electric Power

Research Institute, "Recent Solar-Lunar

Eclipses ."

March 20, 1985 - Dr. Henry N. Blount, III, National Science

Foundation, "Electrochemical and

Spectroelectrochemical Studies of

Heterogeneous Electron Transfer in

Micelles and Bilayers."

April 11, 1985 - Professor Rabin Roy, Drury College, "pH

Measurements of Biochemical Buffers in

Aqueous and Mixed Solvents at Nominal and

Subzero Temperatures."

May 3, 1985 - Professor James A. Holcombe, University of

Texas, "Recent Advances in Graphite

Furnace Atomic Absorption."

May 9, 1985 - Dr. Daniel W. Beekman, Atom Sciences,

Inc., "Laser Ablation as an Atomization

Source for Resonance Ioniztion Spectroscopy."

May 17, 1985 - Professor Dr. Klaus G. Heumann , Institute

for Inorganic Chemistry, "Accurate Anion

Trace Analyses Using an Economical Thermal

Ionization Mass Spectrometer."

June 3> 1985 - Professor J. Hoste, Institute for Nuclear

Studies, "Determination of Light Elements

in Metals and Semiconductors by Charged

Particle Activation Analysis."

June 14, 1985 - Dr. Kaj Heydorn, Risri National Laboratory,

"Improvements in the Characterization of

Reference Materials."

79
June 28, 1985 Professor Gary M. Hieftje, Indiana

University, "New Chemical Separations and

Measurements

September 19, 1985 Professor Robert L. Kay, Carnegie-Mellon

University, "Aggregation Numbers and

Micellar Charge from Transport

Properties ."

September 24, 1985 Professor Harold Friedman, State

University of New York at Stony Brook,

"Real Electrolyte Limiting Laws,"

September 26, 1985 Professor Roger G. Bates, University of

Florida, "Ion Selective Potentiometry and

the Ion Activity Problem."

b. Conferences Sponsored

November 26-28, 1984 W. R. Kelly, Isotope Lead Experiment

Steering Committee Meeting, Gaithersburg,

MD

March 19-22, 1985 R. Zeisler, Research Coordination Meeting

Coordinated Research Program on Human

Daily Dieting Intakes of Nutritionally

Important Trace Elements, Gaithersburg,

MD.

May 20-22, 1985 R. L. Watters, Jr., Chemometrics Research

Conference, Gaithersburg, MD.

80
III. Organic Analytical Research Division

Willie E. May, Chief

Dennis J. Reeder, Deputy Chief

A. Division Overview

The Organic Analytical Research Division conducts research to develop

and improve techniques for the preparation, purification, and analysis of

organic compounds and employs these techniques in the solution of problems

related to national needs. The Division’s research is carried out in five

groups that are organized along the following functional lines: Bioanalytical Techniques, Electrochemistry, Gas Chromatography, Liquid Chromatography,

and Mass Spectrometry. Current activities in each of the groups will be discussed in the Group Overviews and Technical Reports that follow. Results

from the Division's research activities are utilized by industry, other

government agencies, public and private institutions and associations, and

other research programs at the National Bureau of Standards. Research

efforts in the Division during the past year have resulted in the publication

of over 35 articles in archival journals and other technical media. An additional 21 articles are currently in press. Division scientists also presented more than 85 talks at technical meetings and conferences during the

past year

.

In FY85, approximately 50 percent of our efforts were directed toward

basic research in organic analytical chemistry. The remainder of our efforts

were in support of other Federal Agency programs and to a limited degree in

short-term projects performed on a service analysis basis. The Division

continues to be actively involved in three Competence Building Programs that

have been selected for funding by the NBS Director: Organic Electrochemistry; Analysis of Ionization Mechanisms and Ion Structures in Organic Mass

Spectrometry; and the Use of Proteins in Analytical Chemistry. Research in

liquid chromatographic retention mechanisms has continued and a new effort in

selectivity optimization in multidimensional gas chromatography has been

initiated. Accomplishments in these areas will be discussed in the Group

Overviews and Technical Reports that follow.

As in the past, the major portion of our other agency support has come

from the Environmental Protection Agency (EPA), with substantial support also

coming from the Department of Energy (DoE) , Department of Defense (DoD), and

the Food and Drug Administration (FDA). In addition, this year marked the

commencement of a major multi-year program with the National Cancer Institute

(NCI). Specific research efforts in support of other Federal Agency programs

included: continued development of reference materials and the provision of

analyses to establish NBS traceability on audit, quality control and proficiency testing samples for EPA; continuing in our role as Reference Laboratory for a network of DoE laboratories involved in the analysis of polar

organic compounds in complex samples; development of SRMs for drugs of abuse

in urine and an isotope-dilution gas chromatography/mass spectrometry method

for the measurement of chemical warfare agent BZ in urine for the DoD; con- tinued evaluation of methods for the determination of ethylene oxide on surgical tools for the FDA; and serving as a Reference Laboratory for NCI

grantees involved in the determination of micronutrients in serum as part of

chemoprevention clincial trials. We also collaborated with the Air Pollution

Research Advisory Committee of the Coordinating Research Council Inc. (CRC81
APRAC) in conducting an international inter laboratory study on the

measurement of polycyclic aromatic hydrocarbons and related compounds in

ambient air and diesel particulate extracts. The CRC is a non-profit memberbased corporation organized to conduct research of mutual interest to the

petroleum and automotive equipment industries and government. The objective

of CRC-APRAC is to provide data on the environmental consequences of automotive emissions. Additional details concerning these activities are given in

the Group Overviews and Technical Reports that follow.

During the past year, we have been involved in collaborative research

programs with the Inorganic Analytical Research and Gas and Particulate

Science Divisions, as well as several other NBS groups. Our studies concerning the separation of metal-binding proteins in acrylamide gels have con- tinued to be supported and assisted by neutron activation analyses performed

by scientists in the Inorganic Analytical Research Division. We are involved

in two collaborative programs with scientists in the Gas and Particulate

Science Division. Laser ionization mass spectrometric and Raman spectroscopic measurements were performed to assist in determining the structures of

poly(4-vinylpyridine) (PVP) and PVP-metal complexes, chromatographic supports

for biomolecule affinity chromatography. A series of SRM cylinders and

several additional cylinders with known concentrations of selected volatile

toxic aromatic compounds were prepared and provided to us for measurement by

GS/MS as part of a program to establish direct NBS traceability on EPA's

measurements of toxic organics in air.

Collaborative research efforts are also ongoing with other Centers

within NBS. We have collaborated with scientists in the Center for Chemical

Physics in the development of a comprehensive sampling and analysis scheme

for the determination of organic-chlorine species produced during the combustion of refuse derived fuels. We continued our collaboration with the Center

for Fire Research in the development of an analytical method for arson accellerant detection. Additional details concerning this program are provided in the Gas Chromatography Group Overview. Scientists in our Liquid

Chromatography Group have collaborated with scientists in the Center for

Materials Science in the development of a small angle neutron scattering

procedure for physical characterization of liquid chromatographic supports

and bonded phases.

We have continued our active support of the NBS Standard Reference

Materials program. SRM related activities represented approximately 12 percent of our budget. Six SRMs were certified during the past year and analytical measurements are in progress for certification of ten additional

materials. We also provided polycyclic aromatic hydrocarbons measurements on four marine sediments to the Marine Analytical Standards Program of the

National Research Council of Canada. These sediments are being certified by

interlaboratory concensus utilizing data from a selected group of

laboratories "qualified" in the determination of PAH in complex mixtures.

Our research programs in gas chromatography and bioanalytical chemistry

have been strengthened by the additions of Dr's. Howard Mayfield and Jesse

Edwards. Howard Mayfield came to us from the University of Alabama and is

completing the first of a two-year appointment as a Postdoctoral Research

Associate. Jesse Edwards joined us in early summer from the University of

North Carolina and brings to us expertise in biochemistry and a wealth of

experience in two-dimensional electrophoresis. Dr. Polly Ellerbe has joined

82
us as the Roger K. Gilbert/College of American Pathologist Research

Associate. She replaces Dr. Kwokei Ng who has accepted an industrial position. Richard Durst has temporarily assumed the duties as Deputy Director of

the Center and William MacCrehan has assumed Dr. Durst’s responsibilities as Electrochemistry Group Leader. Dr’s. Timothy Wozniak and Joe Foley have com- pleted their postdoctoral appointments and accepted industrial and academic

positions, respectively. They will be replaced by Dr’s. Michael Ambrose

(Bioanalytical Techniques/NMR) and Damian Shea (Electrochemistry/LC-EC)

.

In FY86 we will continue to direct a major portion of our efforts

towards basic research in each of the five groups in the Division. Development of bioanalytical sensors is a very challenging and exciting new area of

research that will be undertaken in the coming year. This research effort

will be supported through the Competence Building program. We expect to make

a key new hire in this area early in the coming year. Details concerning

other specific basic research activities are provided in the respective Group

Overviews that follow. Our support of EPA, DoE, and DoD programs will continue at FY85 levels. However, our efforts in the NCI Chemoprevention Program will be increased significantly in FY86 and we are planning a joint

program with the Center for Radiation Research and other Federal Agencies to

investigate the possible use of chemical markers as post-irradiation

dosimeters for food products.

1 . Bioanalytical Group: Overview

The Bioanalytical Techniques Group continues to focus its research

efforts in three major areas: (1) separation methods applicable to biotechnology, (2) organic synthesis of compounds labeled with stable isotopes for

high accuracy work in clinical/nutritional chemistry, and (3) maintenance of

expertise and performance of research in high-field nuclear magnetic resonance spectroscopy. Our work has continued to be directed towards gaining a better understanding of the chemical processes involved in separations of

biomolecules by isoelectric focusing, electrophoresis , and liquid chromatographic techniques, in improving our NMR spectroscopy capabilities, and in

continuing our work in development high-accuracy methods for important

analytes in clinical chemistry.

Our current goals include developing marker proteins for use in

electrophoretic systems, studying sensitive techniques for specific staining

of selected biomolecules, expanding our research on immobilized enzymes, com- pleting development of an isotope dilution-mass spectrometric definitive

method for serum creatinine and triglycerides, and implementing new capabilities in NMR techniques through research utilizing an improved data

system for the 400 MHz Spectrometer.

Our studies on marker proteins have led to the tentative selection of a molecular weight mixture which may be commercially produced as an SRM. Negotiations are currently underway to assess the capabilities of a company to

produce this material in sufficient quantity. Development of stable, widerange isoelectric point markers is expected to be a more difficult problem

and will be addressed in the coming year.

Research has continued in development of more sensitive and selective

detection methods for electrophoretically separated proteins in polyacrylamide matrices. A collaborative study with the Inorganic Analytical Research

83
Division is underway to study the experimental conditions necessary for

successful detection of specific metal-binding proteins and phosphoproteins

by neutron activation techniques. Prosphorproteins have been detected using

neutron activation followed by autoradiography. This technique has been

applied to one-dimensional molecular weight separations and preliminary work

on two-dimensional electrophoretic gels is currently in progress. These

studies should be of interest to research laboratories that are measuring

levels of phosphoproteins in brain metabolism and in hormonal regulation.

Due to its high sensitivity, silver stain continues to gain popularity

as a general protein stain despite its mysterious and troublesome nature.

The mechanism of this stain is being probed in several ways in an effort to

establish staining conditions on a more scientific basis than the current

empirical approach. Neutron activation analysis has been used to compare the

silver distribution in polyacrylamide gels that have been stained using both

ammoniacal and non-ammoniacal silver stain procedures. These studies clearly

indicate that silver is concentrated in the proteins bands in the ammoniacal

stains but not necessarily in the non-ammoniacal gels. Negative images

appear to arise from silver exclusion.

Preliminary studies have been carried out to determine the feasibility

of studying some aspects of silver stain mechanisms on the molecular level

using 1(^Ag nmr. Despite literature reports of low sensitivity and extraordinarily long T-| values (1000s) for 1(^Ag, our measurements indicate that

ammoniacal silver solutions have sufficiently small T

1 (8s) and high enough

sensitivity to make continued studies feasible. Research is planned to

determine the specific Ag binding sites on amino acids and polypeptides and

the effect of pH and temperature on this binding.

Research on immobilized enzymes had been focused on following the

stability of urease that was coupled by several different covalent binding

techniques to Sepharose supports. Some of the columns made with the bound

enzymes on the supports are still fully active after four months storage.

We have started research in HPLC separation of proteins and peptides.

Initial studies have been focused on the determination of monomer/dimer

ratios in SRM 927a, Bovine Albumin Solution. We have also evaluated

materials for three candidate SRMs: 1) creatinine, 2) cholesterol, and 3)

bilirubin.

A series of new metal polymers were prepared and used for the study of

the mechanism of separation of serum proteins by metal-chelate affinity

mechanisms. Immobilized metal-ion affinity columns were prepared by chelating transition metal ions such as Cu(II), Ni(II), Zn(II), Co(II), and Mn(II)

to iminodiacetate derivatives of styrene-divinylbenzene beads. This work is

reported in Technical Report 17.

In collaboration with the Inorganic Analysis Division, the structure of

poly( il-vinylpyridine) (PVP) and PVP-metal complexes has been examined by

laser ionization mass spectrometry and by Raman spectroscopy. Two communications were prepared from this work. One has been accepted in Polymer

Communications and the other has been submitted to the NBS Journal of

Research

.

8H
In our continuing efforts in f, def initive" methodology, we have

investigated the use of a silyl derivative of uric acid as a replacement for

the previously used tetraethyl derivative. This less time-consuming procedure will provide another method for assessing the accuracy and precision of

the IDMS work on serum uric acid.

This year a quality assurance program was established in our division to

support clinical laboratories involved in the analysis of selected vitamins

in human serum and plasma as part of the National Cancer Institutes Chemoprevention Program. In addition to the tasks involved in assuring measurement

compatibility among laboratories performing vitamins in serum measurements,

we began a research effort to improve some of the methodology. Work in our group has focused on the synthesis of isotoptically labeled vitamins A and C.

Guest worker J. Miller developed procedures for determining vitamin C in

natural samples by isotope dilution gas chromatography/mass spectrometry

.

That work is currently being refined to optimize the yield obtained in the

extraction procedure.

A major effort in the NMR program has involved the development of an experimental method for two-dimensional, DEPT CH J-resolved _ C NMR spectrum

editing. This method facilitates the generation of separated, twodimensional CH, CH2

, and CH^ J-resolved 1 ^C NMR sub-spectra for complex molecules. The work has entailed substantial software development, as a result

of which new Pascal programs have been written for construction of linear

combinations of two-dimensional, rat data matrices and Fourier-transformed

data matrices, and also for simulation of the NMR spectra of oligomers con- taining two of four components by co-addition of the theoretical spectra of

the monomeric components. Other research efforts directed toward chemical

synthesis of bilirubin glucuronide (needed for isotope dilution studies) have

yielded and unexpected carbohydrate intermediate. The structure and conformation of this new intermediate (a glucuronate 1,2-cyclic carbonate) have

been determined by a combination of proton and 1 NMR, including DEPT

multiplicity editing and two-dimensional, CH chemical shift correlation with

proton decoupling in both dimensions.

NMR methods have also been used in analytical surveys of candidate

materials for renewal of the cholesterol and creatinine SRMs , for analysis of

walnut shell oils of interest to the National Park Service, and for monitoring incorporation of 1 °0 isotope into quinuclidone. This compound is needed

for use in the development of an iostope dilution gas chromatography/mass

spectrometry method for the determination of chemical warfare agent BZ and

metabolic products in serum.

Our staff has grown this year with two new staff members joining the

group. Margaret Kline brings experience from industry in separations of biomolecules, and Dr. Jesse Edwards brings experience in biochemistry and twodimensional electrophoresis which will help meet stated goals in several

areas of research. Several guest workers have come to our group to add their

enthusiasm and expertise; Paul Vetter from Rutgers University, Ken Keiler on his way to Stanford University, and Rita Choudry a protein biochemist from

Texas A&M University.

In FY86 we will increase efforts in the electrophoresis area, as well as in the separation techniques for selected proteins by HPLC and by metal-ion

affinity chromatography. Future plans for NMR research include two85
dimensional and polarization

15, ^ transfer studies of peptides and proteins,

synthesis and N NMR studies of labeled aminoglycosides (by a new postdoctoral research fellow), and installation of a new data system for the MOO

Hz spectrometer, including an array processor and process controller module.

Dennis J. Reeder, Group Leader; Lyle A. Alexander, Rita R. Choudry, Alex

Cohen, Bruce Coxon, Jesse Edwards, Alexander J. Fatiadi, Joyce F. Graf, Diane

K. Hancock, Cindy L. Hsu, Ken Keiler, Margaret C. Kline, Millard Maienthal,

Kristy L. Richie, Robert Schaffer, and Paul Vetter

2. Electrochemistry Group; Overview

A continuing need exists for the development of new approaches for trace

organic and organometal analyses. Until recently, electrochemical techniques

have not been widely used for such analyses because of their lack of resolution. The combination of chromatography with electrochemical detection and

the advent of electrocatalysis at polymer-modified electrodes have provided new impetus for novel approaches for the analysis of organic compounds.

Our research efforts have continued to be focused on the study of

organic and organometallic redox reactions using state-of-the-art electrochemical techniques: cyclic voltammetry, chronoamperometry , chronocoulometry , and rotating ring-disk electrochemistry; hybrid techniques, such as spectroelectrochemistry and liquid chromatography with electrochemical detection; the preparation and evaluation of chemically modified electrodes; and

mathematical modeling of electrochemical processes in support of the Group

research activities.

In the organic electrochemistry competence building program we have

continued to make good progress toward our research objectives and have

applied these results to NBS programmatic needs. In recent years, we have

demonstrated the power and versatility of liquid chromatography with electrochemical detection (LCEC) for biochemical analyses. Most successful to date

has been the development of novel electrochemical detectors for chromatographic analysis. Multiple electrode designs and various excitation waveforms have resulted in significant advances in selectivity and sensitivity.

In addition, we have pioneered the use of reductive electrochemistry which

has greatly extended the applicability of this method of detection. For

example, a new method was developed for the determination of nitrated polycyclic aromatic hydrocarbons using gradient elution chromatography in

combination with computer-controlled, potential-optimized, differential-pulse

detection

.

The most promising area of research in terms of both understanding

fundamental processes at electrode surfaces and providing a novel class of

chemical sensors is that of the chemical modification of metal, semiconductor, and carbon electrodes. Problems associated with polymer-film stability

and loss of activity of the electrocatalytic redox centers are being overcome

and highly selective and sensitive analytical devices are anticipated to be

feasible soon.

Spectroelectrochemistry, in combination with cyclic voltammetry and

double potential step chronocoulometry , has been effectively employed to

study the electrochemical behavior of electron-withdrawing, dithiolene

86
complexes of transition metals in acetonitrile. Correlations have been made

between the formal potentials of the complexes and the structural character

of the ligands.

In the area of LCEC, our plans call for continued research to enhance

the sensitivity of this technique by the development of microarray electrodes

to increase the signal-to-noise ratio and the use of chemically modified

electrode detectors to provide increased analyte specificity. Unfortunately,

demands from a major National Cancer Institute program have hampered the

development of microarray detectors, but this obstacle was offset by an interesting study of the electrochemical behavior of two fat-soluble

vitamins, retinol and g-carotene. At a glassy carbon electrode in aqueous

media, the oxidation of both these compounds are mutli-step processes following the initial formation of unstable cation radicals. The oxidation of

these compounds is being investigated chromatographically following the

coulometric generation of the products. Knowledge of the electrochemical

behavior will be employed to help optimize conditions for the electrochemical

detection of these compounds in serum samples.

Until now, one of the major deterrents to the successful application of

chemically modified electroanalytical sensors has been the instability of the

polymer films used to attach electroactive or catalytic agents to the electrode surface. To increase stability without deleteriously affecting the

immobilized catalyst, we have developed both thermal and photochemical cross- linking to provide enhanced bonding of the polymer film to the electrode.

Crosslinking provides greater resistance to polymer dissolution and degradation in hostile matrices and solvents. Electrochemical characterization of

these crosslinked films reveals facile charge transport across the membrane

and permits the incorporation of large proportion amounts of metal-porphyrin

catalyst

.

The first important application of stabilized polymer-film electrodes

has been the development of reference electrodes for non-aqueous electrochemistry. The absence of a convenient, broadly applicable reference redox system has long hindered research and the intercomparison of electromotive force

(emf) data in nonaqueous solvents. Using the f errocene/ferrocenium ion redox

couple (recommended by the Electrochemistry Commission of the International

Union of Pure and Applied Chemistry), we have developed a crosslinked, polyvinylf errocene-f ilm electrode which exhibits excellent reference electrode

potential in a variety of nonaqueous solvents. The stability of this

electrode far exceeds any polymer reference electrode previously reported.

Substantial progress has been made in the development of a precise,

mathematical model for the charge-transport through polymer-modified electrode. The accurate description of this phenomena will permit the prediction

of the optimum parameters for electrode modification. In this past year's

effort, the effect of the resistance/capacitance of the modifiedelectrode/solution interface has been added to the effect of charge migration

in the electric field. For many possible values of resistance and capacitance, the current response to an applied potential step is dominated initially by the resistance/capacitance effect but later becomes dominated by

the charge-migration effect. Experimental measurements of the current

response of a polymer-modified electrode follow the model-predicted response

quite well.

87
The development of these chemically-modified electrodes will not be

limited to inorganic metal-complex catalysts but, as a result of Biosensor

Competence funding in FY86, will be extended to enzymatic and immunological

reactions via immobilized enzymes and antibodies confined to the electrode

surface. The use of sensitive marker compounds encapsulated in synthetic

biomembranes (liposomes and vesicles) which rupture when contacted by specific analytes, e.g., antigens or other types of biocomponents, also are feasible using electrode modification procedures. It is expected that biotechnological approaches will become more widely used based on their high

reaction specificity and which, when combined with the sensitivity of

electrochemical methods, will lead to unique classes of analytical sensors.

Our permanent staff has remained stable and we have enjoyed the addition

of several ’'temporary'1 scientists. On August 12th, however, R. A. Durst

assumed the duties of Deputy Center Director and W. A. MacCrehan became Group

Leader. Another graduate co-op student (R. M. Kannuck) and a guest scientist

from Israel (Dr. E. Schonberger) have joined the group. In October, a NRC/NBS Postdoctoral Associate from the University of Maryland (D. Shea) will

begin a research project concerned with trace metal complexation by natural

ligands in seawater. To expand our research efforts into the area of bioanalytical sensors, both electrochemical and optical, we are currently

recruiting a biochemist knowledgeable in the areas of enzymology, immunology,

and biomembranes.

While most of the major pieces of equipment acquired in previous years

are now operational and automation is proceeding on schedule, we are still in

need of a versatile, rapid-scanning uv-visible spectrophotometer and, as part

of our Biosensor program (and shared with the Bioanalytical Techniques

Group), a phase-resolved, scanning subnanosecond spectrofluorometer . Additional LC and data acquisition equipment will also be needed to support the

new postdoctoral research program.

Richard A. Durst; Group Leader; Elmo A. Blubaugh, Rosanne M. Kannuck, William

A. MacCrehan, Gwendolyn S. Marbury, Emil Schonberger, and William T. Yap

3. Gas Chromatography Group: Overview

The Gas Chromatography Group conducts research in the areas of high

resolution gas chromatography and computer automation to allow development of new techniques and maintain state-of-the-art competence, which are used to

certify complex Standard Reference Materials (SRMs), meet other agency

milestones, and disseminate technical information.

The group constantly produces large data bases of chromatographic

analyses which must be statistically and mathematically manipulated and then

presented in a clear and concise manner. To do these operations by hand, as we have done in the past, is inefficient, and sometimes statistical information is lost and both systematic and random errors can remain undetected in

the process. For these reasons we have acquired computer hardware which is

being used to build a state-of-the-art laboratory information system (LIMS).

This equipment consists of two IBM 9000 data handling systems which serve to

integrate the output signals of nine gas chromatographs, as well as act as one of the inputs to the LIMS system. Also purchased was a super microcomputer which operates on a UNIX system and acts as the LIMS controller.

Additionally, we have obtained an IBM AT personal computer which, in

88
addition to its main function as a component of the Divisions managerial AT

network, will be utilized as a high resolution color terminal of the LIMS

system. This system also will allow us to conduct applied research in the area of chromatographic LIMS applications and development. For detailed

information on this subject see the Technical Report 8.

We would like to expand our range of analyzable compounds to include

thermally labile compounds such as vitamins, non-chlorinated pesticides and

high molecular weight compounds such as 7“ to 10-ring polycyclic aromatic

hydrocarbons (PAH). We have therefore embarked on a program to develop com- petence in the field of capillary column supercritical fluid chromatography

(CSFC). This program has concentrated in two areas of development, first the

modification of existing gas chromatographic instrumentation to run the CSFC

experiment and second the development of a detector which will be compatible

with the wide range of mobile phases we would like to use. A Varian 3700 GC

has been successfully modified but is only capable of relatively unsophisticated measurements. We are optimistic that we will obtain support to procure

a state-of-the-art instrument early in FY86. The detector development has

produced a microwave cavity which is capable of sustaining a highly energetic

helium plasma. The effluent of the CSFC will be introduced into this plasma

to excite the eluted solutes; the resulting optical radiation will be monitored using a grating monochrometer. Initial results from this detector,

using only gas chromatographic effluents, have been successful.

The research activities in the area of multidimensional gas

chromatography are covered in Technical Report 3, and will not be discussed

here. During the last year we participated in a cooperative program with

the Center for Chemical Physics which involved the qualitative and quantitative determination of organo-chlorine species produced by the combustion of

refuse derived fuels (RDF). Researchers within the GC group developed a com- prehensive sampling and analytical procedure and have isolated and

identified chlorophenols , chlorobenzenes , and polychlorinated biphenyls

(PCBs) in fugitive emissions from the burning of RDF.

We have continued to refine our arson accellerant detection method, as described in last year’s annual report, and are engaged in planning a joint

study with the Bureau of Alcohol, Tobbacco, and Firearms in which we will

field test the method under controlled conditions. This method is based upon

the observation that hydrocarbon accelerants, used to start intentional

fires, produce an inordinate amount of PAH. We can perform a PAH analysis on soot found deposited at a fire scene and the presence of a relatively high

level of PAH in that soot should be indicative of the presence of a hydrocarbon liquid at the scene prior to the fire. During the past year, we have

modified the method to add a dimethyl formamide partition procedure to remove

almost all nonpolar interferences.

In FY85 the GC group has participated in the certification of four

Standard Reference Materials (SRMs) (see Technical Report 23), and has performed several service analyses including an analysis of the PCB content of

transformer fluids taken from the White House. The group also has been very

active in other agency programs. We have continued our work for the U.S.

Environmental Protection Agency (EPA) Cincinnati laboratories , providing NBS

traceability to their Performance Evaluation Samples. We also have entered

into an agreement with EPA to prepare, package and provide benchmark values

for three separate PCBs-on-sediment materials for use in their performance

89
evaluation program. We are involved in a program for the EPA at Research

Triangle Park, NC, to evaluate the stability of low molecular weight com- pounds stored in Tenax-filled columns. If these solvent molecules prove to

stable in this storage configuration, then these Tenax columns can be used to

trap gaseous components from a CRM cylinder (produced in The Gas and Particulate Science Division) and used as secondary standards for GC/MS calibration of EPA instrumentation. Pesticide and PCBs analyses of human liver

tissue samples are continuing for the EPA/NBS Pilot Specimen Bank. Methods

are being developed for the analysis of polycyclic aromatic hydrocarbons,

pesticides and PCBs in marine sediments and tissues for a NOAA project.

The Gas Chromatography Group personnel has been increased by the

addition of a part-time high school student, Mr. Steven Olson. Mr. Olson

will be working mainly on our hierarchically configured computer system.

During the coming year, we will continue to work in the areas of

multidimensional gas chromatography, capillary column supercritical fluid

chromatography, and laboratory information management systems. In particular, we will apply our multidimensional model to a real world separation

problem, the dual column chromatographic behavior of nitrogen heterocycles

extracted from a shale oil matrix (SRM 1580). If this application is suc- cessful we will be able to better determine the composition of this SRM,

which should lead to the certification of additional compounds. We plan to

investigate the effect of the mobile phase in CSFC on elution behavior of

various model compounds to elucidate the mechanism of separation. Once our LIMS system is fully operational we will begin the development of an integrated software package, which will be downloaded to other systems within our division. Other areas of interest include picogram-per-gram analyses (chlorinated dioxins and furans), supercritical fluid extraction of matrixed

solutes, and the development of an automated on-column injection system.

Stephen N. Chesler, Group Leader; Delmo P. Enagonio, Franklin R. Guenther,

Howard T. Mayfield, Michelle M. Miller, Steven Olson, Reenie M. Parris, and

Richard F. Rebbert.

4. Liquid Chromatography Group: Overview

The activities of the Liquid Chromatography Group are directed towards

(1) gaining a better understanding of the mechanisms of retention and selectivity in LC, and (2) applying this information to the development of methods

for the isolation, separation, identification, and quantification of

individual compounds in simple and complex mixtures.

Research in the understanding of retention mechanisms has focused on the

influence of both the stationary phase and the mobile phase on the retention

process. Previous work in our laboratory has indicated that polymeric C^g

phases have significantly different retention and selectivity characteristics

when compared to the more conventional monomeric C^g phases. These selectivity differences are particularly evident when planar and nonplanar or linear and nonlinear solutes are compared on the two phases. A series of

planar/nonplanar and linear/nonlinear solute pairs were compared on a mono- meric phase and three polymeric phases with varying surface coverage. The

selectivity factors (i.e., relative retention) for the solute pairs were

small for the monomeric phase and increased significantly on the polymeric

phases, with further increases as the surface coverage of the polymeric

90
phases increased. The observed influence of solute shape and planarity on retention and selectivity has been explained in terms of a schematic representation of the bonded phase referred to as the "slot model". This work was recently reported in Journal of High Resolution Chromatography and

Chromatography Communications (8:248, 1985).

Further investigations of the influence of the stationary phase on selectivity have been directed towards the physical characterization of these

bonded phases to determine which properties are responsible for the unusual

properties of polymeric C-jg phases as compared to the more conventional monomeric C i g phases. Traditional methods of characterization, such as elemental

analysis for the determination of percent carbon and gas adsorption methods

for the determination of surface areas, have been employed on a variety of

bonded phases. Surface areas for the bonded phases were observed to decrease

as carbon loading increased regardless of the phase type or alkyl chain

length. The application of small angle neutron scattering (SANS) for the

characterization of silica substrates and bonded phase substrates is under

investigation. SANS has considerable potential for the characterization of

chromatographic substrates since this technique can probe structural details

in the range of 1-100 nm. Of particular interest was the use of SANS to

determine if any of the silica pores were closed or inaccessible using a procedure known as contrast variation. The results of these SANS studies, which

were conducted in conjunction with C. J. Glinka of the Center for Materials

Science, were published in the September 1985 issue of Analytical Chemistry

and are summarized in Technical Report 1. Based on our initial experiments

with bonded phases, SANS offers considerable potential for the investigation

of alkyl bonded phase morphology, e.g., information on pore blockage and

perhaps phase thickness may be obtainable. SANS experiments are currently in

progress in this area.

The role of the mobile phase in LC selectivity has been studied by

Dr. Joe P. Foley, an NBS/NRC Postdoctoral Fellow who recently completed his

two-year stay at NBS, and accepted a faculty position at Louisiana State University. Dr. Foley investigated the optimization of selectivity in isocratic

reversed-phase LC via control of secondary chemical equilibrium (SCE). New

equations were developed to predict the optimum conditions (e.g., pH). The

new equations were verified with several test systems and the factors which

influence the self-selectivity, a fundamental parameter in SCE-LC theory,

were identified. The details of these studies are described in Technical

Report 2.

In the area of supercritical fluid chromatography (SFC), we have

developed a novel multidimensional chromatographic procedure using supercritical carbon dioxide as the mobile phase on conventional LC columns. In the

past we have used extensively an off-line multidimensional LC procedure for

the determination of polycyclic aromatic hydrocarbons (PAH) in complex mixtures (i.e., normal-phase LC on an amino phase followed by reversed-phase LC

on an octadecylsilane phase). However, because of the use of incompatible

solvents in the normal-phase and reversed-phase LC steps, it was difficult to

implement an on-line procedure. This problem was overcome by using supercritical carbon dioxide as the mobile phase which provides similar retention and

selectivity characteristics on both the amino phase and the C-jg phase as in

the conventional LC procedure. This application of SFC is described in Technical Report 4, and will be published in an upcoming issue of the Journal of

High Resolution Chromatography and Chromatography Communications.

91
In the past year, the LC group has been heavily involved in LC methods

development and analyses in support of the National Cancer Institute (NCI)

Chemoprevention program. LC methods have been developed for the measurement

of selected fat-soluble vitamins (retinol, alpha-tocopherol, and betacarotene) and ascorbic acid in calibration solutions and in human serum. A

method for stabilizing the ascorbic acid in solution and in serum using

di thiothrei tol has been studied. In addition, LC has been used extensively

for the determination of the purity of the commercial vitamin standards.

Semi-preparative-scale LC was also used to isolate and purify vitamin A (all

trans-retinol ) in order to determine accurate UV extinction coefficients for

use in quantification. More details concerning the NCI program are included

in Technical Report 20.

Two environmentally significant SRMs were certified during the past

year using LC as one of the analytical techniques, SRM 1650 "Diesel Particulate Matter" and SRM 1587 "Nitrated Polycyclic Aromatic Hydrocarbons in

Methanol". For the diesel particulate sample, 12 polycyclic aromatic hydrocarbons (PAH) and four nitro-PAH were quantified using a multidimensional LC

procedure with fluorescence detection. The nitro-PAH, which do not exhibit

fluorescence, were converted, on-line, to fluorescent amines prior to detection. SRM 1587 is a mixture of seven mono-nitrated polycyclic aromatic

hydrocarbons in methanol. Reversed-phase LC was one of the techniques used

to determine the seven nitro-PAH compounds in this SRM (see Technical Report

22). A third SRM, "Cholesterol in Coconut Oil", is currently in preparation.

This material will consist of a coconut oil matrix to which cholesterol and

selected vitamins have been added (e.g., retinol acetate, tocopherol acetate

and vitamin D

2

). This material will be certified for the content of the

added cholesterol and vitamins and for the natural content of

alpha-tocopherol. LC procedures will be used to measure the vitamins in this

matrix

.

Two guest scientists have worked in the LC group during the past year.

Dr. Azza Aziz Moustafa, from the Cairo University in Egypt and sponsored by an AMIDEAST Peace Fellowship, has been involved in the measurement of vitamins in the coconut oil SRM. Mr. Hui-Cong Liu from the People’s Republic of

China participated in several of the LC projects involving the measurement of

environmental pollutants.

In the coming year, research in the area of LC retention mechanisms will

continue to focus on the characterization of chromatographic phases, with

particular emphasis on polymeric alkyl phases, using both physical and chromatographic methods for this characterization. For the physical characterization of the bonded phase, the use of SANS will be a major area of research.

We will be funded next year by the Office of Standard Reference Materials to

investigate the feasibility of developing an SRM for the chromatographic

characterization of LC columns (i.e., bonded phases). This SRM would consist

of one or more test mixture solutions to characterize various column properties such as carbon loading, selectivity, phase type, residual silanols,

efficiency, etc. Work will also continue on the influence of PAH structural

features on retention and selectivity.

92
In the area of SFC research, the LC group, in conjunction with the GC

group will continue to develop competence in the understanding and the analytical use of this technique. Using a Hewlett Package HPLC unit that has been

upgraded to include SFC capabilities, we intend to investigate the feasibility of utilizing this technique for solvent-free purification of some of the

vitamins in the NCI project to overcome the photosensitivity problems encountered in conventional procedures. Our basic research efforts in understanding SFC mechanisms will be expanded with the addition to the LC Group of a graduate co-op student (A. M. Natoli, Georgetown University) who will compare

the retention mechanisms in reversed-phase LC and SFC through the combination

of thermodynamic and chromatographic measurements on appropriately selected

systems. The dependence of retention on mobile phase density in SFC and the

similarity between variations in SFC mobile phase density and LC mobile phase

composition will be examined.

Development of methods and analyses in support of SRM work (e.g., PAH in

acetonitrile (renewal), PAH in coal tar, vitamins in solution, drugs of abuse

in urine, and dinitro-PAH in solution) and other agency programs (NCI, EPA,

DoE, and DoD) will continue.

Stephen A. Wise, Group Leader; Bruce A. Benner, Jeanice Brown-Thomas

,

Richard G Christensen, Joe P. Foley, Walter F. Kline, H. C. Liu, Sam A.

Margolis, Azza A. Moustafa, and Lane C. Sander

5. Mass Spectrometry Group: Overview

The mass spectrometry group has conducted research in a number of areas involving both basic and applied research. Efforts are continuing in the

development of mass spectrometric methods for the accurate quantitation of

individual organic compounds in complex matrices and in the laser induced

photodissociation of ions as part of the mass spectrometry competence

building program, "Analysis of Ionization Mechanisms and Ion Structures"

.

Quantitative measurements made in the mass spectrometry group in the

last year have been used in the certification of several SRMs including: SRM

1586 (Priority Pollutants in Methanol), SRM 1614 (Dioxin in Isooctane), SRM

1650 (Diesel Particulate Matter), and SRM 909 (Human Serum). The preparation

and certification of SRM 1614 is described in Technical Report 21. Measurements of polycyclic aromatic hydrocarbons (PAH) were also made on a series of

Canadian marine sediments. These results are being used in combination with

results from several other laboratories for the certification of the concentrations of PAH in the materials by the Marine Analytical Chemistry Standards

Program of the National Research Council of Canada. The NBS participation in

this program is described in Technical Report 24.

Two methods for the calibration of GC/MS instrumentation used for the

analysis of volatile organic compounds have been compared using GC/MS systems

at NBS and EPA/RTP. A cryogenic trapping apparatus developed at NBS was evaluated on the system at EPA/RTP which is routinely calibrated using static

dilution bottles. While the trap produced the same values at both locations,

using calibration curves for analytes in gravimetrically prepared cylinders

a systematic bias was found between the standard gas cylinders and the static

dilution bottles. Further measurements are planned to resolve the

discrepancy. This work is described in Technical Report 10.

93
The use of isotope dilution definitive methods for the quantitative

determination of constituents in human serum has continued in collaboration

with the Bioanalytical Techniques Group. The glucose level in serum SRM 909

has been observed to decline with time and therefore the concentration has

been remeasured and a new certified value assigned. After delays caused by a great diversity of opinion in the clinical community about exactly what con- stituted "triglycerides", work is again in progress on the development of an ID/MS method for triglycerides. The necessary measurements include triglycerides, a sum of di- and mono-glycerides, and free glycerol. The results of

definitive method measurements and clinical chemistry laboratory measurements

of four organic analytes in sera used by the College of American Pathologists

in their proficiency testing program have been compared. The results are summarized in Technical Report 11, and will appear in Archives of Pathology

and Laboratory Medicine.

Investigations into the laser induced photodissociation of ions, which

are part of a competence building program in mass spectrometry, have con- tinued and been extended. The photodissociation of both positive and negative ions generated by cesium ion bombardment has been observed. The

technique appears to have considerable potential for the determination of the

structures of large molecules, particularly those of biological origin. The

results are presented in Technical Report 9.

In the year ahead we plan to continue work on the projects with which

the group is presently involved. Specific efforts will include: the development of methods for the analysis of polar compounds in air particulates

and diesel particulates; the extension to more volatile constituents of the

cryogenic trapping method; the development of a method for triglycerides and

a new method for uric acid, followed by use of these methods to certify

values for these analytes in serum; and, as part of the mass spectrometry

competence building program, modifications to permit use of the data system

for acquisition of data from photodissociation experiments, extension of the mass range for which photodissociation is observable, and increasing the

extent of photodissociation achieved. A project for the Department of the

Army, begun in March 1985, and intended to provide an analytical method for

the detection of 3 - quinuclidinyl benzilate (BZ) and its metabolities in urine

for the purpose of monitoring workers during the decommissioning of chemical

weapons, will be completed.

We have been fortunate to have with us Dr. Kwokei Ng as the Roger K.

Gilbert/College of American Pathologists Fellow. Dr. Ng has left to join

private industry. We are also pleased to have had with us in the group, Professor James M. Miller of Drew University, Nydia Rodriguez, a student at the

University of Puerto Rico, Dr. Timothy Wozniak, an NRC Postdoctoral Research

Associate now with private industry, Mrs. H. X. Gu who contributed greatly to

several of our projects, and Mr. Y Gao of the People's Republic of China. Dr.

Polly Ellerbe has joined us as the new College of American Pathologists

Fellow.

Edward White V, Group Leader; Gary D. Byrd, Polly Ellerbe, Laurence

R. Hilpert, Stanley Meiselman, Larry R. Phillips, Lorna T. Sniegoski, and

Michael J. Welch

94
B. Selected Technical Reports

(Organic Analytical Research Division)

1 . Investigations of Substrate Morphology in Chromatographic Sorbents by

Small-Angle Neutron Scattering

L. C. Sander, S. A. Wise, and C. J. Glinka

The careful measurement of physical and chemical properties of

chromatographic sorbents in liquid chromatography is fundamental to the study

of solute retention. A better understanding of retention mechanisms may

permit the optimization of separations and the preparation of new types of

sorbent materials. As part of our continuing research into the properties of

chromatographic sorbents, the Liquid Chromatography Group has utilized smallangle neutron scattering (SANS) to assess structural characteristics of

silica microparticles. Small-angle neutron scattering can be used to probe

details within the size range of 1-100 nm. Since most chromatographic substrates have pore diameters within the range of 6-30 nm, SANS is well suited

to the study of these materials. Three properties can be assessed using

SANS: pore size, surface area, and pore accessibility.

Small-angle neutron scattering measurements on narrow and wide pore

silica substrates were carried out on the SANS spectrometer at the NBS

research reactor. Surface area measurements were also performed using a nitrogen adsorption technique similar to the classical BET measurement. The

results of the measurements on three representative substrates are presented

here: Zorbax 60 silica, Partisil silica, and Vydac TP silica (see Table 1).

Table 1. Comparison of SANS and BET Results

Silica

Area (SANS)

nr/g

Area (N 2

) m

2 /g

Cord Length

nm

Pore

Diameter, nm

Zorbax 60 375 ± 50 430 ± 5 4.6 6

Partisil 450 ± 60 430 ± 5 3.7 8.5

Vydac TP 60 ± 10 80 ± 10 30 33

Good agreement exists between area values obtained by SANS and by nitrogen

adsorption. The mean cord length listed in Table 1 is a measure of the avei

age dimensions of the silica skeleton and does not directly correspond to

pore diameter. Even so, we have found a high degree of correlation between

these mean cord length values and pore dimensions provided by the

manufacturer

.

Pore accessibility in silica substrates was determined by using a SANS

technique referred to as density matching. The pores of the sample are filled using a liquid that has the same index of refraction (for neutron

scattering) as bulk silica. The reduction in scattering intensity that

results is directly proportional to the fraction of filled pores. For th»' three silicas listed in Table 1, essentially no scattering was observed in

the presence of a matching solvent (H2 O/D2 O mixture). Thus, essentially ali

of the pore volume 099?) was found to be accessible to the H

2 O/D2 O mixture.

95
The density matching technique was further applied to the study of three

alkyl bonded phase substrates. Monomeric alkyl phases (C^, Cg, C-jg) were

prepared on Zorbax 60 silica by reaction with dimethylalklyehlorosilane

.

Scattering patterns were collected for the bonded substrates in the presence

of a mixture of methanol and deuterated methanol, prepared to match the

silica portion of the sorbent. Scattering was reduced but not eliminated in

each case. Since no scattering was observed for the unbonded Zorbax control

sample, scattering for the bonded phase sorbents must be attributed to the

bonded phase itself. It is hoped that detailed analysis of the scattering

patterns will lead to a direct evaluation of the thickness of the bonded

monomeric layer.

2. Investigation of Secondary Chemical Equilibria in Liquid Chromatography:

Verification of Optimization Theory for Acid-Base Equilibria and

Identification of Factors which Influence Self-Selectivity

J. P. Foley and W. E. May

The purpose of this study was twofold: to verify our theory for the

optimization of secondary chemical equilibria in liquid chromatography (SCELC); and to identify which factors influence "self-selectivity", a fundamental parameter in the SCE-LC optimization theory.

The SCE-LC theory which we have derived is summarized in the equations

below: AX and A represent the associated and dissociated forms of a given

analyte; X represents the equilibrant in the mobile phase; K is an equilibrium constant; k' AX and k' A are limiting capacity factors; and FAX and F

A are stoichiometric fractions. For the separation of a pair of compounds, the

optimum concentration of equilibrant in the mobile phase may be calculated

from either the linear or quadratic optimization equations. The linear equation is a simple approximation, accurate whenever the self-selectivity — the

ratio of limiting capacity factors, k' A ^/k’ A — is similar for a pair of com- pounds. The quadratic equation is more general and is applicable under all

conditions. The parameters, A, B, and C in the quadratic equation are functions of the limiting capacity factors and equilibrium constants of the

analytes

.

AX l

A + X K = [A][X]/[AX]

k' =

PX0PT

A[X] 2

FAX k *AX + FA

k

'

A

= PKAVG + 1/2 LOG

Qp-j> + b[x]qp T

+ c =

(k 'AX/k 'A )

secondary equilibrium

retention model

linear optimization equation

quadratic optimization equation

The retention model upon which the optimization equations are based was verified experimentally using various combinations of solutes, mobile and

stationary phases. The behavior of amino acids, dinitrophenols , and substituted benzoic acids were evaluated using acetate or formate buffered organic

solutions with conventional reversed-phase columns. The behavior of methylated phenols was evaluated using bicarbonate-carbonate buffered organic

solutions with poly(styrene-divinylbenzene) columns.

96
More important than the verification of the retention model was the

direct verification of the optimization equations using several pairs of com- pounds. Shown in Table 1 are results for two pairs of compounds, 3~chloro

and 4-chlorobenzoic acid and 2,6-dinitro and 2, 4-dinitrophenol . As seen from

Table 1, the agreement between theory and experiment is excellent.

Because the self-selectivity (k* AX^’ determines the mobile phase

composition for maximum resolution of two solutes, the effects of several

experimental parameters on were investigated. These parameters are listed below in order of decreasing significance:

1. nature of stationary phase

2. identity of the acid-base buffer

3. alkyl chain length of the stationary phase

4. identity and amount of organic solvent in the mobile phase

5. temperature.

Only the nature of the stationary phase and the identity of the acidbase buffer had significant affect on the self-selectivity. Variations of as much as two orders of magnitude were observed by varying reversed-phase

packings. Changes of up to a factor of 3 were observed due to differences in

acid-base buffer systems. Variations of the remaining parameters resulted in

self-selectivity changes of less than 10 percent.

Table 1. Direct Verification of the SCE-LC Optimization Equations

Day Solute Pair a pH0PT,expt

b PHqpt,

quadratic

c theory

linear aexpt

l “theory

1 3CBA/4CBA 4.57 ± .05 4.58 4.38 1.133 1 .131

2 3CBA/4CBA 4.57 ± .10 4.60 4.36 1.133 1.133

20 3CBA/4CBA 4.42 ± .25 4.56 4.37 1.133 1.140

20 2, 6DNP/2, 4NDP 3.99 ± .25 3.89 3.98 1.375 1.373

aCBA = chlorobenzoic acid. DNP = dinitrophenol

.

^Uncertainties reflect pH increments between successive measurements.

Calculated via the optimization equations given in text. Values of k, AX/k

’

A

were averaged in obtaining linear solution.

Calculated via the quotient of a pair of retention model equations.

3. Optimization of Selectivity Using Sequentially Coupled Capillary Gas

Chromatographic Columns

H. T. Mayfield and S. N. Chesler

In this project we have sought to develop the means for predicting

conditions for optimized selectivity for systems of sequentially coupled GC

capillary columns. The systems considered consisted of two or more columns

97
coupled sequentially and mounted in separate ovens so that the individual

column temperatures can be independently controlled. Such systems offer the

potential for separating mixtures which cannot be separated on single columns

coated with single component phases. These systems also offer greater flexibility for selectivity optimization than do systems made up of single columns

coated with mixed phases. The retention behavior in a sequentially coupled

column is a combination of the retention behaviors for the individual columns

of the system. This can be described by a parameter of the system called the

effective capacity factor, k eff . The effective capacity factor is defined in

equation 1, and its calculation is analogous to that of the capacity factor

of an analyte on a single column where t is the retention time of solute

and tm

is the gas holdup time.

The effective capacity factor can be related to the capacity factors of

the individual columns of the systems through

where is the fractional carrier gas holdup time for the i-th column in the

system, and k

i is the capacity factor of an analyte on column i. The capacity factor of a compound on a single column is a function of temperature

which can easily be determined experimentally. The carrier gas holdup time

for each column, and hence P

i

, is dependent upon column length and cross section, operating pressures and temperatures, and is difficult to determine

experimentally. Several methods of calculating tm ^

, or P^, have been investigated with promising results. These make it possible to calculate ke ^ for

a compound given its k^ values and the set of operating parameters for the

system. The selectivity for a sequentially coupled column system is analogous to that of the individual columns, such that between any pair of

compounds, designated by subscripts, i and j, the selectivity s^j is given by

For a sequentially coupled column system, k e ff values are used instead

of k values. For a given mixture of compounds, the lowest possible value of

s^j describes the separation between the two compounds in the mixture which

separate least. The term smin will be used to denote the lowest value of

selectivity between compounds of a mixture. Low values of sm ^ n

, near 1.0,

indicate conditions where at least two of the components of the mixture are poorly separated. High values of smin indicate conditions where all com- pounds of the mixture are well separated. In order to optimize selectivity

for a mixture of compounds, their capacity factors are measured on the individual columns, at several temperatures. The capacity factors are then

expressed as functions of temperature for each compound. A computer program

is then used to calculate ke ff values for the compounds for all temperature

combinations possible within certain limits. The limits are set to bracket

reasonable values of temperatures, based on the working ranges of the

individual columns. The largest value of smin encountered in the designated

temperature ranges is reported, along with the temperatures of the two

columns from which it results. Also, a response surface of sm ^ n versus temperature of columns 1 and 2 can be displayed on a graphics terminal or plotted. From these results, optimal operating temperatures for the columns

of the combined system can be chosen.

(1)

(2)

s

i j = MAX(k

i ,kj)/MlN(ki ,k

J

) ( 3 )

98
4 . On-Line Two-Dimensional Chromatography Using Supercritical Carbon

Dioxide as a Mobile Phase

R. G. Christensen

Two properties of supercri tical carbon dioxide which differ from the

properties of ordinary liquid chromatographic (LC) mobile phases have been

used to effect a two-dimensional chromatographic separation. The first

unusual property is that supercritical CO 2 provides separations on aminebonded columns similar to the normal-phase LC separations obtained on these

columns with hexane, and separations on octadecyl-bonded columns similar to

reversed-phase separations obtained with aqueous/ organic solvents. The second

property which differs from that of other solvents is that its solvating

power can be varied in different parts of the stream by changing the pressure

or temperature to alter the density.

To achieve a two-dimensional supercritical fluid chromatographic

separation using the columns mentioned above, we connected the two columns in

series, with provision for switching either column in or out of the stream,

and with a restriction between them. A sample of aromatic hydrocarbons

extracted from coal tar was injected onto the amine column and was separated

according to increasing number of aromatic carbon atoms. When a desired

fraction was about to elute, the octadecyl-bonded column was switched into

the mobile phase stream. The pressure drop across the restrictor lowered the

pressure, and hence the density, to a point where the eluting fraction was retained on the octadecyl-bonded column. The amine-bonded column was then

switched out of the stream, and the components of the trapped fraction were

eluted by lowering the temperature, thus increasing the density. Baseline

resolution of many of the compounds containing 1 6— to— 1 8 aromatic carbon atoms

was attained from single injections of this complex mixture. Analysis time

is 10-to-20 minutes, compared with several hours required for the off-line

separations with conventional solvents. If routine analyses of this type

were required, it would be easy to automate the operation using valves

controlled by the existing microprocessor in the instrument.

5. Development of a Supercritical Extraction Procedure for the Removal of

Trace Organic Species from Solid Samples

S. N. Chesler, R. G. Christensen, and M. M. Miller

Prior to this study, analysts at NBS could only rely upon solvent

extraction as the sole method for removing organic analytes from solid

matrices in which they were bound. It is well known that supercri tical

fluids have high solubilization powers. For that reason, a supercritical

fluid extraction should be as effective as continuous solvent extraction in

removing matrix-bound compounds. We, therefore, modified an existing packed

column supercritical fluid chromatograph so that it could be used to extract

polychlorinated biphenyls(PCBs) from a sediment sample. A stainless steel

extraction column 25 cm in length and O .63 cm (1/4 inch) o.d. was packed with

approximately 6 grams of sediment. The inlet of the extraction column was then connected to the CO2 outlet of the chromatograph, and the outlet of the

column was attached to a 66 cm section of 60 pm i.d. fused silica capillary

by use of a low dead volume reducing union. The end of the capillary was connected to a solute trap constructed from a 5 cm section of O .63 cm (1/4

inch) o.d. stainless steel tubing filled with C— 1 8 liquid chromatographic

99
packing material held in place by frits. The capillary acted as a pneumatic

resistor and provided essentially all the pressure drop for the flow system,

such that the C0 2 is maintained in the fluid phase in the extraction column

and in the gas phase in the trapping column. The extraction column and most

of the fused silica capillary were maintained at 40 °C inside the chromatographic oven while the trapping column was located outside of the oven and was maintained at room temperature. A flow of 1 mL of supercritical C0 2 per

minute was pumped through this extraction apparatus for approximately 4 hours

at an inlet pressure of 33.8 MP. After this extraction period, the trapping

column was disconnected from the extraction apparatus and connected to an HPLC pump which was used to elute the solutes from the trap with methylene

chloride. The trap was eluted with 40 mL of solvent, which was then

evaporati vely concentrated prior to analysis.

To compare relative extraction efficiencies, samples of the PCB

containing sediment was subjected to a 12 hour Soxhlet extraction as well as the supercritical fluid extraction. Two internal standards, PCB #10 and

#198, were added to the extracts after extraction to measure the absolute

amount of solute PCB removed. The amounts extracted for each of the two

methods are presented in the Table below:

Concentration (ppm) of Arochlor 1254 in Sediment

Extraction Soxhlet SFC

6.61 ± 0.21

6.71 ± 0.16

6.84 ± 0.18

6.61 ± 0.19

As can be seen from the table, the results from the 4 hour SFC extraction

were comparable to the 24 hour Soxhlet extraction. During the SCF extraction

a second trapping column was connected in tandem with the primary column to

test for solute breakthrough. Analysis of this second column showed there

was no breakthrough from the first C— 1 8 column.

6. Development of a Method for the Stabilization of Ascorbic Acid in

Solution and in Human Serum

S. A. Margolis

The development of a method for the stabilization of ascorbic acid was a threefold process: stabilization during HPLC analysis, stabilization of

solutions of the analyte alone, and stabilization of ascorbic acid in a serum

matrix. The ascorbic acid was stabilized during chromatography by using

argon sparged solvents. Under these conditions the coefficients of variation

for the HPLC analyses of solutions of concentrations 4.04 yg/mL and 29.01

yg/mL were 5.2% and 0.5%, respectively (n=10). We followed the stability of

these solutions for 67 days. This study indicated that ascorbic acid in a solution of acetonitrile : water (3:1 v/v), in the presence of the antioxidant dithiothreitol (1 mg/mL) was stable for 67 days when it was stored at

-20 °C under argon in a sealed amber glass ampoule. Examination of these

solutions after eight months of storage indicated that approximately 30% of

100
the ascorbic acid had degraded. Additional studies will be performed to assess more accurately the ascorbic acid stability between the second and

eighth months.

In serum, ascorbic acid degrades unless a stabilizer is added.

Classically, metaphosphoric acid is added to serum to achieve this objective.

However, this stabilizing agent precipitates serum proteins and renders

impossible the aliquoting of serum samples for laboratory testing. This

problem was circumvented by the addition of dithithreitol at a concentration

of 1 mg/mL. Lower concentrations of dithiothreitol were tested and found to

incompletely protect the ascorbic acid. These results were confirmed by one

of the laboratories participating in the NCI/NBS study and by the results of

the first round robin study on serum, spiked with either 51 or 99 yg of

ascorbic acid per mL of serum. These samples appear to be stable for at

least 10 days. Longer-term stability studies on ascorbic acid in serum are

in progress.

In the most recent study on serum obtained from a donor ingesting large

doses of ascorbic acid, 13*6 yg of ascorbic acid/mL was measured in the serum. These serum samples will also be studied for long-term stability of

the ascorbic acid.

7 . Investigations of the Stability and Recovery of Toxic Organic Gases

Adsorbed on Tenax

F. R. Guenther and S. N. Chesler

Adsorption tubes, which contain Tenax as the trapping medium, are used

by the U.S. Environmental Protection Agency (EPA) to collect remote ambient

air samples for analysis of volatile organic carbon (VOC) content. The EPA

laboratory analysis method calls for the thermal desorption of the Tenax

traps directly into the inlet of a gas chromatograph-mass spectrometer

(GC/MS). However, the stability of compounds stored on Tenax has not been

fully established nor has the feasibility of using tubes dosed from SRM gas

cylinders as secondary standards been determined. The objectives of this

project are fivefold: 1) to measure the magnitude and reproducibility of

Tenax blanks over a period of time; 2) to determine the best method of charging the traps, specifically using Certified Reference Material (CRM; gas

cylinders which contain precisely known amounts of organic gases; 3) to

ascertain the stability of volatile organic species on the charged traps over

time; 4) to determine the efficacy of repetitive use of the traps; and 5) to

evaluate two commercially available Tenax adsorbants, Tenax GC and Tenax TA.

A thermal desorber was constructed and installed on a Varian 3700 gas

chromatograph (GC). The desorber was capable of heating 10 cm x 0.9 cm Tenax-filled columns to 250 °C within 30 seconds. The Tenax traps are con- nected to the injection port of the GC using a specially constructed fitting.

The desorber unit is secured around the trap and a tube supplying a helium

carrier gas is then connected to the other end of the trap. A flow con- troller is used to maintain a minimum flow of 10 mL of helium gas/min through

the trap and a pressure regulator is used to maintain any desired minimum

system pressure. Prior to desorption, the head of the GC capillary column is

immersed in a liquid nitrogen bath to thermally trap and focus any desorbed

solutes. The desorber is then ballistically heated to 250 °C and desorption

101
is allowed to proceed. When desorption is complete, the GC oven is heated to

its operating temperature, which acts to evaporate the liquid nitrogen bath

and allows the trapped solutes to move and separate along columns.

The apparatus used to remotely load the Tenax traps consists of a calibrated sample loop in a thermostated water bath and attached to an eight

port gas sampling valve. The valve can alternately place the loop in series

with a CRM gas cylinder or a Tenax trap. The sample loop is loaded with the

gaseous solutes by continuously flushing. Since the gas in the CRM cylinder

can be extremely high pressure (1800 psig), a stainless steel needle valve is

used to drop the delivery pressure to a usable value. The valve is then

switched and the gas in the sample loop is transferred to the Tenax trap by a 10 mL/min flow of helium delivered from a flow controller attached to the

valve. After the transfer is complete, the Tenax trap is removed and capped.

The eight solute molecules investigated in this study were benzene,

toluene, carbon tetrachloride, chlorobenzene, bromobenzene , vinyl chloride,

tetrachloroethylene , and chloroform. The measurement precision of the chromatographic system was found to be 1-2%. This was determined by directly

coupling the sample loop to the injection port, thereby passing the Tenax

columns. The data obtained from the initial stability studies of VOC on Tenax demonstrated large irreproducibility (10-100%); this problem has been

traced to irregularities of the Tenax bed within the trap itself. The Tenax

traps are thermally precleaning by heating the traps to 280 °C for 4 hours

under a flow of an inert gas. This process seems to physically change the

adsorption bed by ’clumping* the Tenax. The alteration of the Tenax bed is

such that channels form allowing the gas being trapped to bypass most of the

Tenax and escape. Studies will be undertaken to determine a better way to

pack the Tenax within the columns to avoid the deterioration of the bed upon

thermal stress.

At the time of this report, not all the data have been collected and

analyzed. However, certain conclusions can be drawn from the available data.

1) There is no advantage in using either of the two commercially available

Tenax adsorbants. After the recommended cleanup procedure, the blanks were

the same and neither one performed superior to the other. 2) Tenax cartridges can be reproducibly charged using CRM cylinders (±5%). The rate is

obtained by charging the cartridges and immediately desorbing them.

8. Design and Implementation of a Comprehensive Laboratory Information

Management System to Acquire, Manipulate, and Archive Chromatographic

Data Bases

F. R. Guenther, S. J. Olsen, and S. N. Chesler

The time of the simple gas chromatograph/recorder combination is way in

the past. The modern chromatography laboratory is now equipped with microprocessor controlled chromatographs feeding into multi-processing microcomputers running chromatography software that acquires up to four channels of raw data, analyzes and reports the results, and stores the raw signal on a high density storage medium. The modern laboratory may have many of these

combinations within a group which may want to share data or use common programs to organize and analyze the data. Within the past two years, we have

102
attempted to link all our laboratory computers together such that any

chromatogram or chromatographic report produced in our lab can be processed

and analyzed on a central computer.

At present, the system consists of two IBM 9000 laboratory computers and one Varian 401 integrator processing data from 10 gas chromatographic channels. Raw data and result files can be stored on floppy disk and hard disk

media for future transfer to our host computer, a Cromemco 3000 system running Unix System V. The host is configured with 1 Mbyte of memory, 50 Mbytes

hard disk storage, 13 serial ports, 2 parallel ports, a fast floating point

processor, and one 1.2 Mbyte floppy disk drive. At present, the computer can accommodate 5 users simultaneously. Software is available to receive and

report raw data from the dedicated integrators and to prepare and analyze

these data.

A comprehensive software package was written in the Pascal programming

language and includes a graphics program to display, manipulate, and analyze

the raw chromatographic data, and to prepare presentation quality graphics.

Also, there are programs to search and extract data from result files for

insertion into a spreadsheet program for further analysis. Commercially procured programs are also available for word processing, communications to

remote computers (such as the NBS supercomputer) for access to statistical

packages, and programming languages (Pascal, C, Basic) for special purpose

programs.

During the next year, the network should be in place and fully

functional. Plans include an inventory program for the Toxic Chemical Handling Facility with a remote terminal within the lab, increased memory so the

additional load can be handled by the computer, a tape backup system to

insure the safety of our data, and perhaps integration of the LC laboratory

within the network.

9. Photodissociation of Ions Generated by Cesium Ion Bombardment for

Determination of the Structures of Organic Molecules

M. J. Welch and E. White V

Techniques such as field desorption, fast atom bombardment, and cesium

ion bombardment (CIB) , are very useful for ionizing large and thermally

labile molecules not amenable to electron impact ionization, but are soft

ionization processes which generally produce little fragmentation. Photodissociation is a promising approach for obtaining increased fragmentation, and

hence increased structural information, from ions generated by such techniques. Photodissociation has been extensively used in studies of the

thermodynamics and kinetics of gaseous ions and molecules but, until

recently, only relatively low molecular weight species ionized by electron

impact have been studied.

We have investigated the use of photodissociation for obtaining

structural information from ions, both positive and negative, generated by

CIB. An argon ion laser is used to irradiate the first field-free region of

a double-focusing mass spectrometer. Ions formed by dissociation of ions in

this region are detected by the use of linked scans. To measure those dissociations which are photon induced, we utilize a mechanical chopper in the

laser beam and phase-sensitive detection of the product ions with a lock-ir.

103
amplifier. Maximum photodissociation occurs when the laser beam enters

through the source so that it is colinear with the ion beam. For cesium ion

bombardment, however, the sample target in its usual position blocks the

laser beam. Modification of the source to allow for separate control of the

two half-extraction plates permitted moving the target out of the laser beam

without serious loss of sensitivity.

A variety of compounds were tested for photodissociation activity under

irradiation by visible light. For both positive and negative ions, detectable activity was found to correlate with chromaphores in the ions. Thus for

compounds such as methyl red, bisbenzimide , rhodamine B, and riboflavin, the

photodissociation of positive ions gave signals sufficiently strong to permit

the acquisition of a complete spectrum of daughter ions generated by photodissociation. For each of these compounds, the daughter ion spectrum generated by photodissociation was distinctly different from the non-irradiated

daughter ion spectrum. A number of peptides and nucleosides were tested and

no photodissociation activity was found, as might be expected considering the

lack of chromaphores which absorb in the visible range in these types of compounds. For negative ions, photodissociation competes with electron detachment. The parent ion decreases in intensity with either, of these processes,

but only with photodissociation are increased daugther ion levels found. For

most negative ions tested, the decrease in parent ion was much greater than

the production of daughter ions (relative to what is observed for positive

ions), thus indicating that both photodissociation and electron detachment

are occurring.

Our results demonstrate that ions generated by soft ionization

techniques, such as cesium ion bombardment, can be photodissociated and that

information useful for the determination of the structure of the molecule is

obtained. We have also observed that, as expected, the photons must be

within the energy range absorbed by the ions. For this technique to become a generally useful tool for structure determinations, significantly shorter

wavelengths of light, capable of photodissociating a wider range of compounds

are necessary. In addition, the photon-ion interaction and the detection of

ions generated by photodissociation must be improved.

10. Comparison of Two Methods for the Calibration of Gas Chromatography /Mass

Spectrometry Instrumentation Used for the Analysis of Volatile Organic

Compounds

G. D. Byrd and E. White V

A gas chromatography/mass spectrometry (GC/MS) method based on cryogenic

trapping was developed that permits a direct comparison of the concentration

of trace components from two gas sources. In this method, the concentrations

of selected analytes in an unknown gaseous sample are determined based on a calibration curve that is established using a reference gas. When used in

conjunction with an SRM gas cylinder, traceability of measurements on the

gaseous sample to the SRM is achieved. This method of using a calibration

curve to determine analytes at unknown concentrations was successfully demonstrated on several samples at NBS and also at an EPA laboratory at Research

Triangle Park, NC ( EPA/RTP) . Using the cryogenic trap on the GC/MS instrument at EPA/RTP afforded an opportunity to compare the amount delivered by our system (trap and cylinders of known concentration) with the amount mea- sured using EPA/RTP* s static dilution-bottle calibration of their instrument.
The cryogenic trap consists of a coil of stainless steel tubing with

provision for connection to a gas cylinder at one end and a needle at the

other end for insertion into a GC injection port. The device also contains

its own heated injection port to allow for the addition of liquid samples to

permit measurements by isotope dilution. When trapping gas samples, the

coils of the trap are immersed in a cryogenic bath and the volume of gas

passed through is measured with a wet test meter. The needle on the trap is

then inserted into the GC and the trap coils are resistively heated while

flushing the trap with helium.

Experiments showed that the system provides a linear response between

the amount trapped and the amount measured. A multicomponent aromatic mixture (benzene, chlorobenzene , and bromobenzene) was selected for the evaluation of the system. Well-characterized gases were selected as calibrants and

used to establish a calibration curve by trapping different measured volumes

from the cylinders. Volumes from cylinders of test gases containing between

10 and 200 ppb of the analytes were then trapped and analyzed by GC/MS using

selected ion monitoring. Good agreement was obtained between the measured and

the prepared concentration values for all analytes. When the same analyses

were repeated at EPA/RTP, no significant differences were found in the

results. This agreement demonstrates the efficacy of the use of the cryogenic trap for precisely transferring gaseous mixtures to GC/MS systems. Measurements made on an SRM cylinder using isotope dilution GC/MS, in which the

isotope diluent was added as a liquid, confirmed the accuracy of the

measurements

.

The data system on the EPA/RTP instrument was calibrated for certain

compounds, including the ones used in the evaluation, using a rigorous calibration curve generated by analyzing gaseous mixtures from static dilution

bottles. This permitted a direct comparison of the values measured by our calibration curve method and the values routinely generated by the EPA/RTP

system. The results showed a bias in all cases with 1

1 —to—35 percent more of

the sample being delivered than detected by the EPA/RTP instrument, with

agreement best for benzene and progressively worse for the less volatile

chlorobenzene and bromobenzene. The source of this systematic bias is not

known at this time and further measurements will be required to resolve this

discrepancy. Research is also planned for evaluating the cryogenic trap on

more volatile compounds using isotope dilution measurements.

1 1 . Comparison of the College of American Pathologists Proficiency Testing

Program Results and NBS Definitive Method Results for Four Organic

Analytes in Serum

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

The College of American Pathologists (CAP) operates a large, voluntary

proficiency testing program for clinical laboratories. They have long recognized the need for an accuracy base for evaluating participant results and

have interacted with NBS for many years regarding such an accuracy base.

Early collaboration involved several electrolytes, and for one in particular,

calcium, definitive method results demonstrated the lack of accuracy in many

of the commonly used procedures. In 1 978, the CAP sponsored a Research

Associate (later named the Roger K. Gilbert Fellowship) at NBS for work in
the Organic Analytical Research Division on the development of definitive

methods for organic constituents of serum. This position continues to this

day, and the third fellow, Dr. Polly Ellerbe, has recently begun her duties.

Isotope dilution/mass spectrometric definitive methods have now been

developed for five organic analytes in serum and all have been used to accu- rately determine analyte concentrations in selected CAP sera. Recently, a group under the direction of Dr. Alfred Hartmann of the McKennan Hospital,

Sioux Falls, SD, has evaluated results from over 7000 clinical laboratories

for glucose, cholesterol, urea, and uric acid in 1979, 1980, 1981, and 1983

CAP Survey Sera and compared them with NBS definitive values.

Overall agreement between the CAP mean values and NBS results was quite

good. For glucose, the data (were subdivided) into 75 methods of five general types. Most of the methods exhibited a small positive bias versus the

NBS results, with the largest relative bias at low glucose concentrations.

The glucose oxidase methods which electrochemically measure oxygen consumption rates gave the best overall agreement. For cholesterol, the data were subdivided into 26 methods of two general types, Liebermann-Burchard and

enzymatic. Both gave results in good agreement with the NBS values, but the

former generally had a positive bias while the latter had a negative bias.

For uric acid, the data were subdivided into 58 methods of four general

types. The two less commonly used types of methods exhibited considerable

bias, one high and one low. Both of the commonly used types gave good

results overall, but some of the individual methods had large biases. For

urea, the data were subdivided into 44 methods of seven types. Two of the

less commonly used types showed significant bias versus the NBS results,

while the others generally had a small positive bias.

This comparison demonstrates that the most commonly used clinical

methods generally give reasonably accurate mean results. However, for all

the analytes in this study, methods which have significant biases are cur- rently being used in clinical laboratories. The results of this comparison

study will appear in Archives of Pathology and Laboratory Medicine and should

result in greater utilization of accurate methods by clinical laboratories.

12. Stabilization of Polymet—Film Electrode Morphology by Thermal and

Photochemical Crosslinking

E. A. Blubaugh

Our interest in chemically modified electrodes (CME) is focused on the

development of these modified surfaces for analytical sensors. However, one

of the major deterrents to the successful application of modified electroanalytical sensors is the instability of the polymer films used to attach the

catalytic agents to the electrode surface. To increase the stability without

deleteriously affecting the immobilized electrocatalyst, we have investigated

both thermal and photochemical crosslinking to provide enhanced bonding of

the polymer film to the electrode and greater resistance to polymer

degradation and dissolution in hostile matrices and solvents.

Thermal crosslinking was promoted by a free-radical initiator (benzene

radical) which undergoes reaction with both the copolymer [poly- (vinylpyridine-styrene) 9:1] (PVP-costy) and the crosslinking agent (triallyltrimellitate). These reactions may involve deprotonation of the copolymer and

106
triallyltrimellitate to form free radicals which then couple to generate

crosslinked polymer macromolecules. We found that crosslinking agents with

larger molecular radii gave more stable polymer-film electrodes (vs. the

smaller molecular radii for the monomeric agents). Additional work involved

using polymeric crosslinking agents (e.g., poly-trans-isoprene) produced

equally stable polymer-film electrodes but requiring only about one-fifth the

amount of crosslinking agent. The poly-trans-isoprene crosslinking agent at

2 wt % was the best crosslinking agent of the 11 monomeric and polymeric

agent tested.

The photochemical crosslinking procedure involves photo-excitation of a 3-ketocoumarin dye sensitizer. The coumarin dye sensitizer is used in con- junction with a cosensitizer, such as ethyl-p-dimethylaminobenzoate , which

acts to initiate the crosslinking reaction. The photochemically crosslinked

films gave analogous stability to the thermally crosslinked films with

respect to the particular crosslinking agent.

Photoacoustic-FTIR spectroscopy has shown that the crosslinking agent is

retained in the film and that all available crosslinking sites (carbon-carbon

double bonds) have been utilized.

The electrochemical response of these electrodes has been encouraging. A

large amount of metalloporphyrin (e.g., rhodium( III )tetraphenlyporphyrin

chloride) has been successfully immobilized as evidenced by the large values

of current passed (-10 mA/cm 2

) in potential step experiments. The films

retain their electroactivity for periods of up to 5 hours.

Work in progress involves combining these polymer films with different

electroactive catalysts, choosing the optimum amount of crosslinking and film

thickness for maximum stability and electrochemical response.

1 3* Polyvinylferrocene-Modif ied Reference Electrode for Nonaqueous

Electrochemistry

R. M. Kannuck

The ability to measure meaningful electromotive force (emf ) data of

species in aprotic solvents has been hampered by the common practice of mea- suring these values versus aqueous reference electrodes or soluble redox

couples. In the former case, an unknown and/or irreproducible liquid junction potential occurs at the aqueous/nonaqueous interface. Furthermore, the

test solution is susceptible to contamination by foreign ions (such as K or Cl when employing a saturated calomel electrode) or water. Reference redox

couples in solution are inconvenient to use and may interact with test

species

.

In an attempt to establish a basis for intercomparison of these types of

measurements, the Electrochemistry Commission of the International Union of

Pure and Applied Chemistry has recommended utilizing the ferrocene/

ferrocinium ion redox couple as one possible reference system. Extending the

original work of Peerce and Bard [J. Electroanal. Chem. 1 08 (1980) 121-125],

we used our thermal crosslinking procedure to increase the stability of

polyvinylferrocene (PVF) in a variety of solvents.

107
The polymer film is first electrodeposi ted in its oxidized form onto Pt

disk electrodes. An aliquot of the crosslinking agent, triallyltrimellitate

(TATM) is pipetted onto the polymer-film electrode surface and the solvent

is allowed to evaporate. The resulting electrodes are heated for 2.5 hours

at 95 °C. Crosslinking is promoted by benzoyl peroxide (a radical initiator)

undergoing a thermal reaction with the polymer and the crosslinking agent to

form free radicals. These radicals can then couple to generate crossl inked

PVF macromolecules. This increase in the average molecular weight of the

polymer gives rise to a less soluble and, consequently, more stable film.

The stability of this type of electrode exceeds any nonaqueous reference

electrode previously reported. The addition of a 4 0 $ (by weight) aliquot of

TATM onto the electrode resulted in stability for up to 24 hours if the

reference electrode was stored continuously in the test solvent. These electrodes, if removed from the solvent at the end of each day, could be used for

A days with a maximum variation in the reference potential of ±2.5 mV.

In methanol solutions, we found that the addition of 40$ TATM improved

the stability of PVF/Pt electrodes for 24 hours with a maximum deviation of

±3.2 mV. If removed from the methanol overnight, the electrodes could be

used for 2 days. Without the addition of the crosslinking agent, PVF/Pt

electrodes drifted -50 mV in 4 hours.

Thermal crosslinking has proven to be effective in situations where the

polyvinlyf errocinium (perchlorate) is extremely soluble. In aqueous solutions, for example, a 40$ addition of TATM stabilized PVF films for 7 hours.

This same amount of TATM also improved the behavior of PVF/Pt reference electrodes in dimethylformamide (DMF). Where potentials of the uncrossl inked

polymer films drifted more than 500 mV in 15 minutes, this procedure reduced

the drift to within 18 mV over 30 minutes. In this case, doubling the amount

of TATM resulted in a reference electrode that was stable to within 2 mV for

approximately 3 hours. It is clear that, while further improvements are still needed, the thermal crosslinking process significantly improves the

stability of PVF reference electrodes in a number of widely used solvents.

1 4. Investigation of the Electrochemical Behavior of Metal-Dithiolene

Complexes

G. Marbury

Dithiolene ligands derived from oxocarbon anions have been used

successfully to synthesize complexes with nickel, palladium, platinum, copper

and gold. These new, highly electron-withdrawing ligands include dithiosquarate (dtsq) , dithiocroconate (dtcr) and dicyanomethylenedithiocroconate

(dcmdtcr). These complexes exhibit a 2:1 ( ligand: metal ) stoichiometry.

This work focused primarily on the electrochemical characterization of

the Cu(II)/Cu(I) redox couple as it is influenced by varying the dithiolene

ligand. The electron transfer process was studied in aprotic solvents using

cyclic voltammetry (CV), double potential step chronocoulometry and

spectroelectrochemistry

.

108
Cyclic voltammetric studies of the complexes in dimethyl formamide (dmf

)

showed reversible behavior with formal potentials (E 0 ') of -0.384 V (dtsq),

-0.328 V (dtcr), and -0.059 V (dcmdtcr) vs. SCE, respectively. Spectroelectrochemical Nernst plots gave E

0 ' values of -0.380 V, -0.328 V, and -0.063 V,

respectively, again showing the expected trend toward less negative reduction

potential with increased electron-withdrawing ability of the ligand. In

addition, anodic/cathodic peak potential separation and current ratios

indicated that these systems were electrochemically well behaved.

Unlike other metal dithiolenes, the electron transfer reactions of these

complexes in acetonitrile are significantly less well behaved than in

dimethyl formamide . The E

0 ' values were estimated to be -0.407 V, -0.333 V,

and -0.179 V, respectively. Cathodic/anodic peak potential separations suggest significant departure from Nernstian behavior. The E

0 ' values were not

related to electron-withdrawing properties of the ligands in a systematic

way.

The diffusion coefficients calculated from chronocoulometric data follow

the expected trend of decreasing with increasing size of the complex in both

solvents

.

Spectroelectrochemical studies of the complexes in DMF gave a range of

electron transfer (n) values instead of the expected single-integer value.

The spectroelectrochemical studies are based on two premises: (1) Nernstian

charge transfer in the complex, and (2) adherence to 3eer’s Law. Since C

V

studies had already suggested Nernstian behavior, the electronic spectral

behavior was investigated as a possible cause of this non-ideal behavior.

Non-adherence to Beer’s Law was confirmed in an experiment in which the product of path-length times concentration was held constant. At high concentrations and short path lengths, the absorbance values were not constant;

behavior consistent with dimerization. Because of this spectral difficulty,

a non-spectrophotoraetric method was sought to confirm the n values. The

technique chosen was thin-layer staircase coulometry. This technique is

presently being used to determine n and the formal potentials for the

dithiolene complexes.

15. Investigation of the Electro-oxidative Products of Retinol and

6-Carotene

W. A. MacCrehan and E. Schonberger

Retinol and B-carotene are two fat-soluble vitamins currently under

investigation by the National Cancer Institute for their anti-tumor behavior.

To determine in-vivo concentrations of these compounds, we are developing a liquid chromatographic method for their determination in serum using both

UV/visible absorbance and oxidative electrochemical detection.

To fully optimize the oxidative detection approach, we must first study

the electrochemical processes that occur. Both retinol and B-carotene are all-trans poly-enes which undergo oxidation at glassy carbon electrodes at

applied potentials of +0.6 to +1.0 V (versus a Ag/AgCl reference electrode).

Preliminary investigation of the reaction of retinol by cyclic voltammetry

indicates that the oxidation is highly irreversible. In the first step, an electron is transferred to the electrode from one of the many carbon-carbon

109
double bonds, creating a radical cation. This highly reactive species undergoes a subsequent nucleophilic attack by protic solvents used for the electrolysis. The remaining free radical portion of the molecule may undergo

dimerization or further electro-oxidation. Our goal is to sort out the

details of the events occurring during the oxidation process by separating

and identify the electrode reaction products. Since both vitamins have

multiple double bonds which may be susceptible to attack, more than one product may be formed in the reaction. Furthermore, the nature of the solvent

used is also crucial to the nature of the products formed, since it reacts to

form the adducts with the radical cation.

To investigate the progress of the electrochemical oxidation, we have

used small-volume coulometric experiments. The electrolysis cell consists of

a glassy carbon rod, porous vycor sample tube, isolated reference and auxiliary electrodes, and 500 pL of test solution. Not only can the potential of

the working electrode be controlled, but also small volumes (i.e., 20 pL) of

the solution may be withdrawn periodically for LC analysis during the electrolysis. The total charge that passes can be related to the number of

electrons transferred per vitamin molecule. Preliminary results for retinol

in methanol and methanol/water mixtures indicate that between one and four

electrons are transferred per retinol molecule depending on the applied

potential. At all potentials tested, many different oxidation products are formed. The nearly equivalent electron density around all five of retinol’s

double-bonds, as well as the delocalization of the charge of the radical,

contribute to the formation of the multiple products.

The solvent has a strong influence on the products as well. In pure

methanol, methoxy derivatives are formed. The addition of as little as 1?

water changes the nature of the products completely, with the presumed formation of hydroxy and epoxy derivatives. We are currently trying to sort out

these products using a liquid chromatographic separation, evaporative con- centration, and mass spectrometric identification of the electrochemical

oxidation products.

1 6. Development of Two-Dimensional DEPT CH J-Resolved NMR Spectrum

Editing

B. Coxon

In a previous report (Annual Report, 1983, CAC, NBSIR 83-2786, p. 149-

152), the development of an ejuierimental method for two-dimensional (2D),

DEPT heteronuclear J-resolved 1 NMR spectroscopy was described (DEPT is an acronym for Distortionless Enhancement by Polarization Transfer). This

method facilitates separation of ' chemical shift and -*C —H spin-spin

coupling information into different dimensions, with enhancement of -*C NMR

sensitivity by magnetization transfer from the protons to the nuclei.

The DEPT technique has proved to be an outstanding method for one-dimensional

(ID) spectrum editing, for example, the decomposition of a complete >C NMR

spectrum into separate CH, CH2

, and CH^ sub-spectra. Our interest, therefore, lay in the experimental realization of a method for 2D DEPT CH Jresolved 1 ^C NMR spectrum editing, a technique that could be expected to

facilitate the disentanglement of complex, overlapped proton coupled 1 -*C NMR

spectra of biomolecules. One goal of this study was to develop automated

data acquisition and processing methods that could be employed with current

disk-interactive software packages.
1 3 The pulse sequence for 2D DEPT CH J-resolved JC NMR reported previously

has been modified to include an additional delay (D) just prior to the proton

pulse (0

y

) that effects polarization transfer:

1 H: tt/2 — 1 /2J — it — 1 /2J — D — 0 y — ir decouple

• •

• •

1 3C : tt/2 t-| / 2

tt — t-j /2 — acquire — t

2

(J =

1 JqH

, minimum value of t 1/2 = 1 /2J + D + 0 y

)

By using three different flip angles (0 = 30°, 90°, and 150°) for the

polarization transfer pulse, an automation program is used to collect a sequence of three, 2D CH J-resolved NMR data matrices. The prepolarization transfer delay (D) causes polarization transfer to be complete

at the same time for each sequence, thus minimizing phase differences between

the three data matrices that lead to inaccurate editing. For the 0y

= 30°,

90°, and 150° sequences, the values D = P-] ” ^30’ ^150 “ ^90’ anc* respectively, were used, where P^q, Pqg, and p

i 50 are the corresponding pulse

widths. The different values of D compensate for the different widths of the

0 y pulse, with normalization to the timing of the 150° sequence.

The use of these three pulse angles with an equal number of acquisitions

for each sequence allows the 2D J-resolved ^CH sub-spectra to be constructed

as the simple combinations:

CH = Matrix^

CH2

= Matrix^ - Matrix-]

CH

3 = Matrix^ + Matrix-]^ - Matrixg0

Two software methods have been developed for calculation of these

combinations. In a first approach, a sequence of microprograms was used to

combine the matrices by sequential handling of files. In a more efficient

approach, a Pascal program was written, using BLOCKREAD and BLOCKWRITE functions to compute the CH2 and CH

3 sub-spectra within a single compound

statement

.

The methods have been tested by generation of CH, CH2

, and CH

3 2D

J-resolved sub-spectra from the useful carbohydrate intermediate: - methyl

2, 3~anhydro-4, 6-0-benzyl idene-a-g-mannopyranoside . This compound was chosen

because its -'C assignments are not immediately obvious, i.e., the signals at

highest field are not the CH2 and CH

3

resonances.

17. Investigation of Metal-Protein Interactions

L. Alexander, A. J. Fatiadi, S. A. Margolis, and D. J. Reeder

A series of new metal polymers was prepared and used for the study of

the mechanism of separation of serum proteins by metal-chelate affinity chromatography. Immobilized metal-ion affinity columns were prepared by chelating transition metal ions such as Cu(II), Ni(II), Zn(II), Co(II), and Mn (II)

to iminodiacetate derivatives of styrene-divinylbenzene beads. The ability of

these materials to resolve proteins was tested at various pH values by

adsorbing human serum to column packings to which a single metal had been

chelated. The proteins were eluted by increasing the buffer concentration
and by increasing metal-ion concentrations. The fractions were analyzed by

ultra-thin isoelectric focusing techniques, with sensitive silver staining.

Generally, three protein fractions were obtained as the buffer strength was increased: (a) albumin and acidic proteins, (b) very basic and some neutral

species, and (c ) slightly basic proteins. Similar results were obtained with

columns of Sepharose 6B chelated with metal ions. However, a comparison of

the two types of column materials includes the capacity of the Sepharose

columns and the recovery of proteins were much better.

This study suggests that hydrophobic, crossl inked polystyrene matrices

are not as good as the more commonly used agarose carriers, such as Sepharose. The results suggest also that those polymers that bind metal ions

by charge-transf er complexing behave as ion-exchange resins.

In a correlated experiment, the stability of a copper chelate to

poly (4-vinylpyridine ) was examined by laser ionization mass spectrometry and

by Raman spectroscopy.

18. Viral Proteins from Vaccine Studied by Two-Dimensional Electrophoresis

J. Edwards, D. K. Hancock, and D. J. Reeder

We are currently engaged in a cooperative study with the Uniformed

Services University of the Health Sciences (USUHS) in an effort to discover

why a formal in- treated vaccine for respiratory syncitial virus (RSV) not only

failed to provide protective immunity, but also suggested that RSV humoral

immunity might dispose infected infants to a potentiation of bronchiolitis.

Using our high-resolution, two-dimensional electrophoresis (2DE)

techniques, we compared a virus-infected cell line with a control non- infected cell line. High sensitivity silver staining used to visualize the

2DE gels revealed minor differences between the infected and non-infected

cell samples. It is unknown whether these observed differences reflect the

presence of viral proteins or alternations in the host cell as a response to

the virus.

In an attempt to further enhance detection of the viral proteins with

regard to both sensitivity and selectivity, immuno-blotting procedures were applied to the 2DE gels. Here the proteins were electrophoretically transferred from the polyacrylamide gels to a nitrocellulose membrane. The nitrocellulose membrane was then serially treated with blocking proteins, cottonrat IgG, rabbit anti-cotton-rat IgG, goat anti-rabbit-glucose oxidase and

finally with the substrate for glucose oxidase color development.

Unfortunately, background staining was high and sensitivity too low to give

definitive results.

We are now preparing to use a more sensitive biotin-avidi n alkaline

phosphatase immuno-detection system which we believe should give us the

required sensitivity and specificity to detect conclusively the viral proteins in the 2DE gels. This will allow more complete characterization of

these viral proteins. In addition, we are attempting to recover sufficient

viral particles from the cell culture medium to be able to examine the viral

proteins themselves, in the absence of cellular proteins from the host cells.

Finally, cells which have been cultured with virus for varying time periods
(

n

— 36 hr.) are being examined by two-dimensional gel electrophoresis for

alterations in the protein components of the host cells resulting from viral

infection.

19. Proteins from Honey Differential By Ultra-Thin Isoelectric Focusing and

Two-Dimensional Electrophoresis

D. K. Hancock, D.J. Reeder, and K. L. Richie

In a collaborative study with the Food and Drug Administration (FDA), we

used high resolution techniques to compare proteins from honey. Although

honey is primarily a carbohydrate material, approximately three percent is of

a proteinaceous nature. The proteins in honey might originate from the plant

nectar, from the enzymes in the gut of the honeybee, or from pollen. However, relatively little has been published regarding the nature of the honey

proteins

.

The proteins content in honey has been used in Europe as a test of

adulteration with such materials as corn syrup or other non-honey products.

It was suggested that a detailed analysis of the protein patterns provided by

isoelectric focusing and two-dimensional electrophoresis could provide additional information about the source of the honey and the types of adulterants

that could be used to extend pure honey.

We examined several types of floral honey provided by the FDA. Sample

preparation involved dialysis and centrifugation. The supernatant was then

stored frozen until examined by the different techniques.

Using ultra-thin (-160 pm) polyacrylamide gels followed by a silver

staining method for protein visualization, we found that there were significant differences in the protein patterns in honey that originated in the

United States, Argentina, Hungary, and China. Honey protein patterns from

the United States and Argentina appeared to be the most similar, while that

of China had few bands in common with the other honey samples.

With two-dimensional electrophoresis, preliminary results showed that

the patterns from the different honey samples were similar in many respects.

However, the China samples showed only major spots to be present and the

Hungarian honey did not focus as well as the other samples. Of interest is

the observation that although the honey proteins from Argentina gave the best

overall gels, with well-focused spots, one major low molecular weight protein

present in the other honeys was missing from this honey sample. Further

studies with additional samples are being planned.

20. Results from Interlaboratory Analyses of Vitamins and Trace Metals

W. E. May and R. Schaffer

The Organic Analytical Research Division has organized a quality assurance (QA) program for laboratories involved in determinations of retinol

(vitamin A), 6-carotene (provitamin A), ascorbic acid (vitamin C),

a-tocopherol (vitamin E), selenium and zinc in serum and plasma. The

Chemoprevention Branch of the National Cancer Institute (NCI), sponsors thi3

program. The NCI also supports studies that are being conducted at several

medical centers, on the influence of these micronutrients on the occurrence

113
of certain forms of cancer, and the objective of the QA program is to help ensure the quality of the analytical measurements made at those institutions.

Laboratories in addition to those involved in NCI-supported studies have been

recruited into the QA program, so that the number of labs participating would

be larger for statistical purposes.

In developing the QA program for selenium and zinc, no significant

problems were expected, given the prior NBS experience with analytical methods and standards for those analytes. For the vitamins, however, we started

from the beginning. We had to investigate the quality of the commercially

available; "reagent-grade” materials, since we needed standards for our analyses and for preparing surrogate samples. We needed to learn how to

determine the purity of available materials and we needed methods for determining these analytes in serum and plasma samples. We found commercial

samples of ascorbic acid and a-tocopherol that were fairly pure, but all of

the g-carotene and retinol samples were impure; some were highly impure.

In working with the participating laboratories, we at first sent them

surrogate samples to analyze, i.e., aqueous solutions of selenium and zinc,

aqueous acetontrile solutions of ascorbic acid (with dithiothreitol added as stabilizing agent), and ethanolic solutions of the trace fat-soluble vitamins. The labs were asked for analyses based on their normally used standards

and separately based on the use of standard solutions prepared at NBS. From

the enormous variability in the purity of the retinol and g-carotene available to laboratories and also from the instability of solutions of ascorbic

acid prepared without a stabilizing agent, we expected the results with the

NBS standards to be significantly better than the others; that is what was

found. Between-laboratory variability, nevertheless remained the major source

of variability in results.

Serum-based samples with the two trace metals and with the vitamins were

also analyzed by the labs. The results for the trace metals in serum showed

a 2- to 3-fold higher relative standard deviation than the results for the

surrogate samples. A corresponding comparison for the vitamin analyses is

awaiting reports of analysis from just a few more laboratories before being

calculated

.

21 . Preparation and Certification of Standard Reference Materials for

Dioxins, Chlorinated Pesticides and PCBs

S. N. Chesler, L. R. Hilpert, M. M. Miller, R. M. Parris, R. E. Rebbert

,

and M. J. Welch

The accurate determination of 2, 3, 7 , 8-tetrachlorodibenzo-p-dioxin

( 2, 3» 7 , 8-TCDD) , commonly but imprecisely known as dioxin, is an important

national measurement problem because of the potential widespread distribution

of dioxins in the environment and their reported mutagenicity/

carcinogenicity. During the past year, we have prepared and certified a dioxin Standard Reference Material. SRM 1614 consists of separate solutions

of unlabeled and ^C-labeled 2, 3, 7, 8-TCDD in 2, 2, 4-trimethylpentane

(isooctane)

.

1 1 4
The dioxin solutions were prepared by adding accurately known amounts of

the unlabeled and 13C-labeled 2,3,7,8-TCDD materials to isooctane. Measurements leading to certification were made on randomly selected ampoules using

capillary gas chromatography with electron capture detection.

During the course of the certification measurements, both the unlabeled

and 13C-labeled 2,3,7,8-TCDD used in the preparation of SRM 1 61 4 were found

to contain a trichlorodibenzo-p-dioxin impurity. Determinations of the con- centration of the trichlorobenzo-p-dioxin in the SRM solutions were made

using gas chromatography/mass spectrometry with electron impact ionization

and the method of standard additions. Because the 2, 3, 7-trichlorodibenzo-pdioxin was the only trichloro isomer available, it was not possible to positively identify which isomer was present in the SRM solutions. However, the

gas chromatographic retention time of the impurity peak was coincident with

that of the 2, 3> 7-trichlorodibenzo-p-dioxin.

The certified concentrations and estimated uncertainties of the

unlabeled and 1 -^C— labeled 2,3,7,8-TCDD solutions as well as the

concentrations of the trichlorodibenzo-p-dioxins are given in Table 1 .

SRM 1614 is intended primarily for use in the evaluation and calibration

of analytical methods used for the determination of 2,3,7,8-TCDD in environmental samples. The use of SRM 1 61 4 should help to improve the accuracy and

precision of measurements for 2,3,7,8-TCDD especially as more sensitive,

isomer-specific analytical techniques are developed.

Table 1. Concentrations of Dioxins in SRM 1 61

4

Concentration

Solution Compound ng /g

Unlabeled 2,3,7,8-TCDD 98.3 + 3.3'

Unlabeled trichlorodibenzo-p-dioxin 1.5 + 0.4

Labeled 2,3,7,8-TCDD- 13C 95.6 + 1 .5'

Labeled trichlorodibenzon-p-dioxin 1 3 C 3.9 ± 0.4

aThe uncertainties given represent two standard deviations of the certified

values. These uncertainties include the gravimetric and GC/ECD 2,3,7,8-TCDD

measurement variability, and the trichlorodibenzo-p-dioxin measurement

variability

.

^Values not certified; provided for information only.

c The concentration given represents the total concentration for all isotopic

forms of 2,3,7,8-TCDD in the solution. The fully 13C-labeled 2,3,7,8-TCDD

accounts for 80.7 ± 0.5 percent of the 2,3,7,8-TCDD molecules in the

sample

.

dThe concentration given represents the total concentration for all isotopic

forms of the trichlorodibenzo-p-dioxin in the solution.

115
We are also making measurements on two materials that will be issued as

NBS Research Materials (RMs). The designation RM is given to those samples

which are available through the NBS Office of Standard Reference Materials

(OSRM) but are not certified, usually because values on various constituents

have been determined by one technique only.

RM 1588, Cod Liver Oil, is a natural material in which the biogenic

concentrations of seven chlorinated pesticides and five PCBs have been measured by a single method. This material has also been gravimetrically

fortified with six polychlorinated dibenzodioxins and one polychlorinated

dibenzof uran

.

Components of RM 1 588

PCBs: Pesticides

:

PCDDsPCDFs:

PCB #101 he xa chlorobenzene 1 ,2,7-T

3

CDD

1 ,2,3,4-TnCDD

o

8 cdf

PCB #153 transnonchlor

PCB #138 4, 4’ -DDE 2,3,7,8-T^CDD

PCB #180 4,4 '-DDT 1 ,2,3,6,7,8-H6 CDD h

6 cdd

PCB #170 a-chlordane

a-BHC

Y-chlordane

1 ,2,3,7,8,9-H6 CDD

OqCDD

h

6 cdd

The components of the RM were measured using a combined chromatographic

procedure which includes a dimethylformamide/hexane partition to remove the

majority of the biogenic interferences, a normal phase HPLC fractionation to

isolate and separate the PCB and pesticide fractions and a high resolution

GC/ electron capture detection analysis of the separate fractions. Until the

constituent concentrations can be certified by a second set of independent

measurements , the material will be released by OSRM as a Research Material.

Another Research Material that has not been assigned a number as yet is

a mixture of three sediment materials collected by the U.S. Environmental

Protection Agency and which is contaminated with ug/g (ppb) levels of two

industrial PCB mixtures, Aroclor 1242 and 1260. These sediments were homogenized at NBS using a "V" blender and a 30-mesh sieve. This material will

be made available to allow researchers to use a universally available, wellhomogenized sample material for such uses as methods development, round robin

exercises, and consensus standards. NBS will possibly certify the concen- trations of some components of this material and issue it as an SRM in the

future

.

SRM 1589, PCBs in Human Serum, is a freeze-dried serum which contains a gravimetrically added PCB mixture, Aroclor 1260. The Aroclor 1260 was added

as an acetone solution at a level of 100 ng/g to the serum prior to lyophilization. This SRM was certified by high resolution electron capture GC. Prior

to analysis the material was reconstituted by addition of water. An internal

standard (PCB #198) was then introduced into the sample and the PCBs were

separated from the serum matrix by extraction with a 1:1 ethyl ether:hexane

solution. These extracts were then passed through silica microcolumns to

further remove analytical interferences. After evaporative concentration,

aliquots of these samples were injected onto the GC for final quantitation.
22. Certification of Standard Reference Material 1587 Nitrated Polycyclic

Aromatic Hydrocarbons in Methanol

W. F. Kline, W. E. May, R. E. Rebbert , and S. A. Wise

Since 1980, interest in the determination of nitrated polycyclic

aromatic hydrocarbons (N-PAH) has grown because N-PAH are present in a number

of environmental samples and commercial products, and because some N-PAH have

direct-acting mutagenic properties. To assist in the accurate measurement of

these environmentally important compounds, NBS has prepared and certified

Standard Reference Material (SRM) 1587 "Nitrated Polycyclic Aromatic Hydrocarbons in Methanol". This SRM is intended primarily for use in calibrating

chromatographic instrumentation used for the determination of N-PAH but can also be used to add known amounts of these compounds to methanol-miscible

extracts

.

SRM 1587 was prepared from N-PAH synthesized by Midwest Research

Institute, (MRI) Kansas City, MO, under a contract from the Coordinating

Research Council, Inc., Atlanta, GA. Compound purities were determined at

MRI to be at least 99 percent; therefore, no correction was made for purity.

Instability of N-PAH in organic solvents stored at room temperature and

exposed to light has been observed. Consequently, amber ampoules were selected to inhibit photochemical degradation and the ampouled material was stored at -25 °C.

Each unit of SRM 1587 consists of four vials, each containing

approximately one mL of a methanol solution containing seven N-PAH. Because

of concerns about the thermal instability of the SRM, each unit will be

shipped via an overnight carrier and packaged in dry ice.

The concentrations of N-PAH in SRM 1587 were determined by both gas

chromatography and liquid chromatography. Table 1 shows the certified values

for six of the seven N-PAH in this SRM. The certified values were derived

from the concordant results obtained from the two independent techniques. The

uncertainties represent two standard deviations of the certified values. The

statistical design allowed for analysis of both the within- and between-vial

homogeneity. The value for 6-nitrobenzo[a]pyrene reported in Table 1, is not

certified, and is provided for information only. The analytical data for

this compound exhibited the largest uncertainty and between-vial variability.

Also, its solubility in the SRM solution appeared to be borderline.

Table 1. Certified Values for N-PAH in SRM 1587

2-

Nitrofluorene

9-Nitroanthracene

3-

Nitrofluoranthane

1 -Nitropyrene

7 -Nitrobenz [a] anthracene

6-Nitrochrysene

6-nitrobenzo[a]pyr ene

Certified Values (yig/g)

9..67 + 0 ..39

5.,01 + 0 ., 1 1 9. C\J + 0 ..06

8..95 + 0 .,28

9..27 + 0 ..27

8..13 ± 0 ..11

6., 1

117
23. NBS Participation in the Certification of a Canadian Marine Sediment

Reference Material

W. F. Kline, G. D. Byrd, H. X. Gu, and W. E. May

In 1976, at the recommendation of the Canadian Committee on Oceanography, the National Research Council (NRC) of Canada established the

Marine Analytical Chemistry Standards Program to support analytical aspects

of marine chemistry. One of the outputs of this program has been a series of

reference materials designed to assist analysts in obtaining accurate determinations of selected trace elements and organic constituents in marine

samples. Trace elements in sea water, trace elements in sediment, and polychlorinated biphenyls in sediment are among the reference materials currently

available through the NRC program. The sediment material is similar to

NBS/SRM 1646 (Estuarine Sediment). The reference materials issued by the NRC

are certified through small-scale interlaboratory comparison studies

involving selected laboratories based upon previously demonstrated

capabilities

.

The next reference material to be released by this group is a suite of

sediment samples with recommended values for the sixteen polycyclic aromatic

hydrocarbons (PAH) on the EPA list of priority pollutants. In the spirit of

international cooperation, we agreed to perform analyses for the certification of this material. A marine sediment material with certified values for

organic constituents has been requested frequently, but is not currently

available from NBS. Values for the requested sixteen PAH and perylene were

determined using two independent procedures based on slight modifications of

the liquid chromatography/fluorescence wavelength programming and gas chromatography/mass spectrometry procedures that have been developed previously

at NBS for the determination of PAH in complex mixtures. These procedures

have been utilized in the certification of several SRMs including: 1580

(Organics in Shale Oil), 1581 (Petroleum Crude Oil), 1649 (Urban Air

Particulates/Organics), and 1650 (Diesel Particulate Matter).

118
C. Outputs and Interactions

(Organic Analytical Research Division)

1 . Publications

Blubaugh, E. A., Chiang, C. K., and Yap, W. T. , Electrochemical Behavior of

Doped Polyacetylene Films, Polymer, 25., 1112-1116 (1984).

Burke, R. T., Blubaugh, E. A., Yap, W. T., and Durst, R. A., Electrochemical

Investigation of N-Methyl-4-(5-phenyl-2-oxazolyl )pyridinium

p-Toluenesulfonate , J. Electroanal. Chem., 1 77 , 77-88 (1984).

Durst, R. A., Chemically Modified Electrode Sensors for Biocomponents,

Proceeding of the Symposium on Biosensors , A. R. Potvin and M. R. Neuman,

eds., IEEE/EMBS Publishing Services, Piscataway, NJ, 56-58 (1984).

Fatiadi, A. J. , Priority Toxic Pollutants in Human Urine: Their Occurrence and

Analysis, Environment International, 1_0> 175-205 (1984).

Foley, J. P. and Dorsey, J. G., Clarification of the Limit of Detection in

Chromatography, Chromatographia, 1_8, 503-51 1 (1984).

Hilpert, L. R., Byrd, G. D., and Vogt, C. R., Selectivity of Negative Ion

Chemical Ionization Mass Spectrometry for Benzo[a]pyrene , Anal. Chem., 56_,

1 842 (1 984).

Kamat, P. V., Fox, M. A., and Fatiadi, A. J., Dye Loaded Polymer Electrodes,

Photoelectrochemical Sensitization by Croconate Violet in Polymer

Solutions and Films, J. Amer . Chem. Soc. 1 06 , 1191-1197 (1984).

Maas, A. H. J., Weisberg, H. F., Zijlstra, W. G., Durst, R. A., and

Siggard-Andersen , 0., Reference Method for pH Measurement in Blood, IFCC

Recommendations and Related Documents, Vol . I, N. E. Saris, ed., W. de

Gruyter, NY, 124-132 (1984).

MacCrehan, W. A. and May, W. E. , Determination of Nitro-Polynuclear Aromatic

Hydrocarbons in Diesel Soot by Liquid Chromatography with Fluorescence and

Electrochemical Detection, Polynuclear Aromatic Hydrocarbons: Mechanisms,

Methods, and Metabolism , M. Cooke and A. J. Dennis, eds., Battelle Press,

Columbus, OH 1413-1427 (1985).

Margolis, S. A. and Coxon, B. , Amino Acid Analysis of Angiotensin I by Proton

NMR Spectroscopy, Anal. Biochem., 141 , 355-360 (1984).

Mattammal , M. B., White V, E., Zenser, T. V., and Davis, B. B., Mass

Spectometry of 2-Substi tuted-4-Arylthiazoles , 3. Identification of

Micrososmal Nitroreduction Products by Mass Spectrometry, Biomed. Mass

Spectrom., n_ (4), 149-154 (1984).

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

C. R., and Wise, S. A., Characterization of Polycyclic Aromatic

Hydrocarbons in Air Particulate Extracts by Liquid and Gas Chromatographic

Methods, Identification and Analysis of Organic Pollutants in Air , L. R. Keith, ed., Butterworth Publishers, Woburn, MA, 197-229 (1984).

119
Roberts, G. D. and White V, E. , Silver Sulfonates as Mass Standards in Field

Desorption Mass Spectometry , Bioraed. Mass Spectrora., 1J_ (6) 273-275

(1984).

Sander, L. C. and Wise, S. A., The Influence of Substrate Parameters on Column

Selectivity with Alkyl Bonded Phase Sorbents, J. Chromatogr. 31

6

, 163-181

(1984).

Wasik, S. P., Schwarz, F. P., Tewari, Y. B. , Miller, M. M., and Purnell, J. H.

,

A Head-Space Method for Measuring Activity Coefficients, Partition

Coefficients, and Solubilities of Hydrocarbons in Aqueous Solutions, NBS

J. Res., 89, 273 (1984).

Wise, S. A., Fitzpatrick, K. A., Harrison, S. H. , and Zeisler, R. , Operation of

the U.S. Pilot National Environmental Specimen Bank Program, Environmental

Specimen Banking and Monitoring as Related to Banking , R. A. Lewis, N. Stein, and C. W. Lewis, eds., Martinus Nijhoff Publishers, Boston, 108-126

(1984).

Wise, S. A. and Zeisler, R. , The Pilot Environmental Specimen Bank Program,

Environmental Science Technology, 1_8 302A-307A (1984).

Zeisler, R., Harrison, S. H., and Wise, S. A., Analysis of Human Liver

Specimens in the U.S. Pilot National Environmental Specimen Bank Program,

Environmental Specimen Banking and Monitoring as Related to Banking , R. A. Lewis, N. Stein, and C. W. Lewis, eds., Martinus Nijhoff Publishers,

Boston, 331-351 (1984).

Christensen, R. G. and White V, E. , Determination of Dibenzothiophene in Oils

by Liquid Chromatography — Tandem Mass Spectrometry, J. Chromotogr . , 323*

33-36 (1985).

Covington, A. K., Bates, R. G., and Durst, R. A., Definition of pH Scales,

Standard Reference Values, Measurement of pH and Related Terminology, Pure

Appl . Chem., 57, 531-542 (1985).

Diamondstone , B. I., Wise, S. A., and Sander, L. C., Carbon Analysis for the

Study of Bonded Phases in Liquid Chromatography, J. Chromatogr. 321 , 318-324 (1985).

Guenther, F. R. and Chesler, S. N., Gas Chromatographic Analysis of Soot,

Report to LESC, (1985).

Kline, M. C., Kotola, A. W., and Young, E. P. , Effect of Aqueous Chlorine (600

PPM) on the Protein and the Lipid Fractions of Ground Beef, J. Food

Quality, 7, 229-235 (1985).

Kline, W. F. , Wise, S. A., and May, W. E. , The Application of Perdeuterated

Polycyclic Aromatic Hydrocarbons (PAH) as Internal Standards for the

Liquid Chromatographic Determination of PAH in a Petroleum Crude Oil and

Other Complex Mixtures, J. Liquid Chromatogr. 8 (2), 223-237 (1985).

Margolis, S. A., Reference Materials for Organic Nutrient Content in Biological

Reference Materials: Availability, Uses, and Need for Validation of

Nutrient Measurements, W. R. Wolf, ed., John Wiley & Sons, NY (1985).

120
Mayfield, H. T. and Chesler, S. N. , Optimization of Selectivity Using

Sequentially Coupled Capillary Columns, Proceedings of the 6th

International Symposium on Capillary Chromatography, P. Sandra, ed., Riva

del Garda, Italy, 772-785 (1985).

Mayfield, H. T. , Mar, T. , Bertsch, W., and Staroscik, J. , Varietal

Classification of Orange Essence Oils by Capillary Column Gas

Chromatography and Pattern Recognition, Proceedings of the 6th

International Symposium on Capillary Chromatography, P. Sandra, ed., Rivea

del Garda, Italy, 555-567 (1985).

Miller, M. M., Wasik, S. P. , Huang, G.-L., Shui , W.-Y., and Mackay, D.,

Relationships Between Octanol-Water Partition Coefficient, Aqueous

Solubility, and Bioconcentration Factors, Environmental Science & Technology, 1_9> 522 (1985).

Pandey, R. C., Kalith, C., Gustafson, M. E. , Kline, M. C., Leidhecker, M. F.

,

and Ross, J. T. f Process Developments in the Isolation of Largomycin F-II,

a Chromoprotein Antitumor Antibiotic, Purification of Fermentation

Products: Applications to Large Scale Processes , ACS Symposium Series,

No. 271 (1985).

Sander, L. C. and Wise, S. A., Synthesis and Characterization of C-jg Stationary

Phases for the Liquid Chromatographic Separation of Polycyclic Aromatic

Hydrocarbons, Polynuclear Aromatic Hydrocarbons: Mechanisms, Methods,

and Metabolism , M. Cooke and A. J. Dennis, eds., Battelle Press, Columbus,

OH, 1 1 33-1 1 44 (1985).

Welch, M. J., Pereles, D. J., and White V, E. , Photodissociation of the

Molecular Ion of n-Butylbenzene : Effect of Photon Energy, Org. Mass

Spectrom., 20, 425-426 (1985).

Wise, S. A., Chesler, S. N. , Hilpert, L. R. , May, W. E. , Rebbert, R. E. , and

Vogt, C. R., Characterization of Polycyclic Aromatic Hydrocarbon Mixtures

from Air Particulate Samples Using Liquid Chromatography, Gas

Chromatography, and Mass Spectrometry, Polynuclear Aromatic Hydrocarbons : Mechanisms, Methods, and Metabolism , M. Cooke and A. J. Dennis, eds.,

Battelle Press, Columbus, OH 1413-1427 (1985).

Wise, S. A. and Sander, L. C., Factors Affecting the Reversed-Phase Liquid

Chromatographic Separation of Polycyclic Aromatic Hydrocarbon Isomers, J.

High Resolution Chromatogr. and Chromatogr . Comm., 8, 248-255 (1985).

Wise, S. A., Recent Progress in the Determination of Polycyclic Aromatic

Hydrocarbons by High-Performance Liquid Chromatography, Handbook for

Polycyclic Aromatic Hydrocarbons: Volume II , A. Bjrirseth and T. Ramdahl

,

eds., Marcel Dekker, New York, NY, 73-191 (1985).

Zeisler, R. and Wise, S. A., Quality Assurance and Protocols in Sampling and

Sample Preparation of Biological Samples, Biological Reference Materials:

Availability, Uses, and Need for Validation of Nutrient Measurement , w . R

.

Wolf, ed., John Wiley and Sons, Inc., New York, 257-279 (1985).

121
Byrd, G. D., Fatiadi , A. J. , Simons, D. S. , and White V, E. , Laser Desorption

Mass Spectrometry of Some Salts of Squaric Acid, Org. Mass Spectrom., in

press

.

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

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

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

Durst, R. A., Chemically Modified Electrode Sensors, Ion-Selective Electrodes , Vol. 4, E. Pungor and I. Buzas, eds., Akademisi Kiado, Budapest, 115-128

(1985)

.

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

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

Koch , ed . , in press

.

Fatiadi, A. J., Development of Metal Chelate Affinity Chromatography (Review),

NBS J. Res., in press.

Fatiadi, A. J., The Classical Permanganate Ion: Still A Novel Oxidant in

Organic Chemistry, Synthesis, in press.

Fletcher, R. A. and Fatiadi, A. J., Laser Ionization Mass Spectrometry of

Affinity Chromatography Column Packing Materials: Poly(4-Vinylpyridine)

,

NBS J. Res., in press.

Fletcher, R. A. and Fatiadi, A. J., Laser Ionization Mass Spectrometry of

Poly(4-Vinylpyridine) , Polymer Commun., in press.

Glinka, C. J., Sander, L. C., Wise, S. A., Hunnicutt, M. L. , and Lochmuller, C.

H., Determination of Pore Accessibility in Silica Microparticles by Small

Angle Neutron Scattering, Anal. Chem., in press.

Hartmann, A. E., Naito, H. K., Burnett, R. W, and Welch, M. J., Accuracy of

Participant Results Utilized as Target Values in the CAP Chemistry Survey

Program, Archives of Pathology and Laboratory Medicine, in press.

Lee, M. L. , Goates, S. R. , Markides, K. E. , and Wise, S. A., Frontiers in

Analytical Techniques for Polycyclic Aromatic Compounds, Polynuclear

Aromatic Hydrocarbons: Chemistry, Characterization, and Carcinogenesis,

M. Cooke, and A. J. Dennis, eds., Battelle Press, Columbus, OH, in press.

Miller, M. M., Zielinski, W. L. , Jr., Ulma, G., and Wasik, S. P. , GLC

Separation Behavior of Polychlorinated Biphenyl Isomers Between a Nematic

Liquid Crystal Stationary Phase and a Nonpolar Hydrocarbon Phase, Anal.

Chem., in press.

Murray, R. W., Ewing, A. E. , and Durst, R. A., Chemically Modified Electrodes,

Anal. Chem., in press.

Reeder, D. J., Standards for Forensic Electrophoresis, Proceedings of the

International Symposium on the Forensic Applications of Electrophoresis , B. Brow, ed., in press.
Sander, L. C., Glinka, C. J. , Wise, S. A., Recent Advances in the

Characterization of Bonded Phases, Chemically Modified Surfaces , D. E. Leyden, ed . , Gordon and Breach Science Publishers, in press.

Sander, L. C. and Wise, S. A., Investigations of Selectivity in Reversal-phase

Liquid Chromatography of Polycyclic Aromatic Hydrocarbons, in Advances in

Chromatography Volume 25 , J. C. Giddings, E. Gruska, and P. R. Brown,

eds., Marcel Rekker, New York, NY, in press.

West, W. R. , Wise, S. A., Campbell, R. M., Bartle, K. D., and Lee, M. L. , The

Analysis of Polycyclic Aromatic Hydrocarbon Minerals Curtisite and

Idrialite by High Resolution Gas and Liquid Chromatographic Techniques,

Polynuclear Aromatic Hydrocarbons; Chemistry, Characterization and

Carcinogenesis , M. Cooke and A. J. Dennis, eds., Battelle Press, Columbus,

OH, in press.

Wise, S. A., Campbell, R. M., West, W. R. , Lee, M. L. , and Bartle, K. D.,

Characterization of Polycyclic Aromatic Minerals Curtisite, Idrialite, and

Pendletonite Using Liquid Chromatography, Gas Chromatography, Mass

Spectrometry, and Nuclear Magnetic Resonance Spectroscopy, Chem. Geology,

in press.

Wise, S. A., Chesler, S. N. , Hilpert, L. R. , May, W. E. , Rebbert, R. E. , Vogt,

C. R., Nishioka, M. G., Austin, A., and Lewtas, J., Quantification of

Polycyclic Aromatic Hydrocarbons and Nitro-Substituted Polycyclic Aromatic

Hydrocarbons and Mutagenicity Testing for the Characterization of Ambient

Air, Environment International, in press.

Wise, S. A., Sander, L. C., and May, W. E., Investigations of Selectivity in

Reversed-phase Liquid Chromatography on Chemically Bonded C-jg Phases,

Chemically Modified Surfaces , D. E. Leyden, ed., Gordon and Breach Science

Publishers, in press.

Wise, S. A. and Zeisler, R. , eds., International Review of Environmental

Specimen Banking , NBS SP 706, in press.

2. Talks

E. A. Blubaugh, "Electrochemical and Spectroelectrochemical Investigation of a Series of Ruthenium(bpy ^ Dithiocarbamate Complexes," American Chemical

Society 1 88th National Meeting, Philadelphia, PA, August 27, 1984.

E. A. Blubaugh, "Synthesis, Characterization, and Electrochemistry of Cationic

Transdihalo Technetium( III) Arphos Complexes," American Chemical Society

188th National Meeting, Philadelphia, PA, August 29, 1984.

W. E. May, "NBS: Its History, Mission, and Organizational Structure,"

Chromatography Science Seminar, Shanghai Institute for Testing Technology,

Shanghai, China, September 17, 1984. Invited

W. E. May, "Overview of the Organic Analytical Research Division,"

Chromatography Science Seminar, Shanghai Institute for Testing Technology,

Shanghai, China, September 18, 1984. Invited

123
W. E. May, "HPLC: Basic Principles and Instrumentation," Chromatography

Science Seminar, Shanghai Institute for Testing Technology, Shanghai,

China, September 18, 1984. Invited

W. E. May, "GC: Basic Principles and Instrumentation," Chromatography Science

Seminar, Shanghai Institute for Testing Technology, Shanghai, China,

September 19, 1984. Invited

W. E. May, "Qualitative and Quantitative Analysis," Chromatography Science

Seminar, Shanghai Institute for Testing Technology, Shanghai, China,

September 19, 1984. Invited

W. E. May, "Quantitative Analysis of Complex Mixture by Selective Detection I,"

Chromatography Science Division, Shanghai Institute for Testing

Technology, Shanghai, China, September 20, 1984. Invited

W. E. May, "Quantitative Analysis of Complex Mixture by Selective Detection

II," Chromatography Science Seminar, Shanghai Institute for Testing

Technology, Shanghai, China, September 21, 1984. Invited

W. E. May, "Results from Several Interlaboratory Comparison Studies,"

Chromatography Science Seminar, Shanghai Institute for Testing Technology,

Shanghai, China, September 21, 1984. Invited

W. E. May, "Multidimensional Chromatographic Analyses of Complex Mixtures,"

Chromatography Science Seminar, Shanghai Institute for Testing Technology,

Shanghai, China, September 22, 1984. Invited

W. E. May, "Preparation and Certification of Standard Reference Materials,"

Chromatography Science Seminar, Shanghai Institute for Testing Technology,

Shanghai, China, September 24, 1984. Invited

W. E. May, "Determination of Physico-chemical Properties by HPLC,"

Chromatography Science Seminar, Shanghai Institute for Testing Technology,

Shanghai, China, September 24, 1984. Invited

W. E. May, "Determination of Trace Organic Constituents in Complex Mixture by

HPLC," Chromatography Science Seminar, Shanghai Institute of Organic

Chemistry, Shanghai, China, September 25, 1984. Invited.

W. E. May, "Selectivity Differences Among Liquid Chromatographic Phases,"

Chromatography Science Seminar, Shanghai Institute for Testing Technology,

Shanghai, China, September 26, 1984. Invited

R. A. Durst, "Chemically Modified Electrode Sensors," 4th Scientific Session on Ion-Selective Electrodes, Federation of European Chemical Societies,

Hungarian Academy of Sciences, Matrafured, Hungary, October 10, 1985.

Invited

W. F. Kline, "The LC Determination of PAH in Petroleum Crude Oil and Other

Complex Mixtures," Chemistry Seminar, American University, Washington, DC,

October 12, 1984.
R. A. Durst, "Analytical Aspects of Chemically Modified Electrodes," Department

of Chemistry, E. Kardelj University, Ljubljana, Yugoslavia, October 15,

1985. Invited

R. A. Durst, "Organic Electrochemical Research at NBS," Department of

Chemistry, E. Kardelj University, Ljubljana, Yugoslavia, October 16, 1985.

Invited

R. G. Christensen, "Quantitative LC/MS/MS and MS/MS Selectivity," Analytical

Chemistry Department Seminar, University of Ulm, Ulm, West Germany,

October 23, 1984. Invited

R. G. Christensen, "MS/MS Selectivity by Adduct Formation," 3rd Workshop on LC/MS and MS/MS of the International Association of Environmental

Analytical Chemistry, Maison des Congres, Montreux, Switzerland, October

24, 1984. Invited

R. G. Christensen, "Quantitative Application of LC/MS/MS," 3rd Workshop on LC/MS and MS/MS of the International Association of Environmental

Analytical Chemistry, Maison des Congres, Montreux, Switzerland, October

24, 1984. Invited

J. J. Edwards, "Demonstration of Protein Markers by 2-Dimensional

Electrophoresis After Exposure to Carbon Tetrachloride and Furans," Center

for Analytical Chemistry, National Bureau of Standards, Gaithersburg, MD,

October 24, 1984.

G. D. Byrd, "Preparation and Analysis of a Quality Assurance Solid Sludge

Material," 36th Southeastern Regional Meeting ACS, Raleigh, NC, October

26, 1984.

S. A. Wise, "The Analysis of Polycyclic Aromatic Hydrocarbon Minerals Curtisite

and Idrialite by High Resolution Chromatographic Techniques," 9th

International Symposium on Polynuclear Aromatic Hydrocarbons , Battelle

Columbus Laboratories, Columbus, OH, October 30, 1984.

E. A. Blubaugh, "Investigation of a Series of Ru(bpy) 2 Dithiocarbamate

Complexes," Chemistry Department, Villanova University, Villanova, PA,

October 30, 1984.

B. Coxon, "Two-Dimensional NMR Spectroscopy of Carbohydrates," Argonne NMR

Workshop/Midwest NMR Discusssion Group, Argonne National Laboratory,

Argonne, IL, November 3, 1984. Invited

B. Coxon, "Two-Dimensional NMR Spectroscopy," ADABSE Meeting, National Bureau

of Standards, Gaithersburg, MD, November 5, 1984. Invited

W. E. May, "Liquid Chromatographic Methods for the Analysis of Nitro-Polycycl ic

Aromatic Hydrocarbons," NBS/DOE Analytical Characterization Group Meeting,

Battelle Conference Facilities, Seattle, WA, November 8, 1984.

E. White V, "Laser Induced Dissociation of Ions from Soft Ionization

Techniques," Eastern Analytical Symposium, New York, NY, November 15,

1984. Invited

125
S. A. Wise, "The Determination of Organic Species of Atmospheric Interest,"

Analytical and Environmental Chemistry Division Seminar, University of

Maryland, College Park, MD, November 1 6 , 1984. Invited

R. G. Christensen, "Quantitative LC/MS/MS and MS/MS Selectivity," Analytical

Chemistry Department Seminar, University of Nebraska, Lincoln, NE,

November 19, 1984. Invited

J. P. Foley, "Selected Topics in Modern Liquid Chromatography: Optimization

and Secondary Chemical Equilibria," University of Massachusetts,

Department of Chemistry, December 10, 1984.

S. A. Margolis, "Separation of Angiotension Isomers by Ion Exchange

Chromatography," 4th International Symposium on HPLC of Proteins, Peptides

and Polynucleotides, December 11, 1984.

J. P. Foley, "Selected Topics in Modern Liquid Chromatography: Optimization

and Secondary Chemical Equilibria," University of Michigan, Department of

Chemistry, December 17, 1984.

J. P. Foley, "Optimization of Secondary Chemical Equilibria in Liquid

Chromatography," Ohio State University, Department of Chemistry, January

8, 1985.

J. P. Foley, "Optimization of Secondary Chemical Equilibria in Liquid

Chromatography," University of Georgia, Department of Chemistry, January

10, 1985.

S. A. Wise, "Factors Affecting Selectivity in Reversed-Phase Liquid

Chromatography of Polycyclic Aromatic Hydrocarbons , " Chemistry Department

Seminar, Duke University, Raleigh, NC, January 10, 1985. Invited

J. P. Foley, "Optimization of Secondary Chemical Equilibria in Liquid

Chromatography," Ohio University, Department of Chemistry, January 14,

1 985.

J. P. Foley, "Optimization of Secondary Chemical Equilibria in Liquid

Chromatography ," University of Maryland, Department of Chemistry, January

28, 1985.

J. P. Foley, "Optimization of Secondary Chemical Equilibria in Liquid

Chromatography," Georgia Institute of Technology, School of Chemistry,

January 29, 1985.

D. J. Reeder, "Chromatography in the Life Sciences," Washington Chromatography

Discussion Group, February 21, 1985. Invited

L. R. Hilpert, "Certification of a Diesel Particulate Standard Reference

Material," Pittsburgh Conference on Analytical Chemistry and Applied

Spectroscopy, New Orleans, LA, February 25, 1985.

M. J. Welch, "The Development of Definitive Methods for Organic Serum

Constituents," 1985 Pittsburgh Conference on Analytical Chemistry and

Applied Spectroscopy , New Orleans, LA, February 26, 1985.

126
J. P. Foley, "Optimization of Secondary Chemical Equilibria in Liquid

Chromatography," 36th Annual Pittsburgh Conference on Analytical Chemistry

and Applied Spectroscopy, New Orleans, LA, February 28, 1985.

J. P. Foley, "Optimization of Secondary Chemical Equilibria in Liquid

Chromatography," Lousiana State University, Department of Chemistry,

March A, 1 985.

J. P. Foley, "Optimization of Secondary Chemical Equilibria in Liquid

Chromatography," Federal Bureau of Investigation, Forensic Science

Division, Quantico, VA, March 8, 1985.

S. A. Wise, "Specimen Banking of Biologicl Indicators," Interagency Toxic

Substances Data Committee, Washington, DC, March 12, 1985. Invited

B. Coxon, "Two-Dimensional Spectrum Editing," NBS Staff Research Seminar on Measurement Method, useful to the Biological Sciences, National Bureau of

Standards, Gaithersburg, MD, March 21, 1985. Invited

R. A. Durst, "Bioelectrochemical Sensors," NRL Electrochemistry Group Seminar,

Naval Research Laboratory, Washington, DC, April 3, 1985. Invited

K. L. Richie, "Isoelectric Focusing: Principles and Applications," National

Bureau of Standards, Gaithersburg, MD , April 3, 1985.

L. C. Sander, "Determination of 3~Carotene and Tocopherol Purities by HPLC,"

NBS /NCI Micronutrient Analysis QA Workshop, National Bureau of Standards,

Gaithersburg, MD, April 12, 1985. Invited

S. A. Wise, "Specimen Banking for Micronutrient Analysis," NBS/NCI

Micronutrient Analysis Quality Assurance Workshop, National Bureau of

Standards, Gaithersburg, MD, April 12, 1985. Inv ited

B. Coxon, "Two-Dimensional DEPT CH J-Resolved ^C NMR Spectrum Editing," 26th

Experimental NMR Conference, Asilomar, CA, April 24, 1985. Invited

L. R. Hilpert, "Mass Spectrometric Methods for the Determination of Amino Acid

Sequence in Polypeptides," American University, Washington, DC, April 26,

1 985.

W. A. MacCrehan, "Determination of 1-Nitropyrene and Selected Other N-PAH in

Diesel Exhaust Particulate Extracts Using Liquid Chromatography with

Reductive Electrochemical Detection," 1 89th ACS National Meeting, Miami,

FL, April 29, 1985.

R. A. Durst, "Chemically Modified Electrode Sensors," Northeastern University

Chemistry Department Colloquium, Boston, MA, May 7, 1985. Invited

B. Coxon, "One- and Two-Dimensional NMR Spectrum Editing," National Heart & Lung Institute, National Institutes of Health, Bethesda, MD , May 7, 1985.

Invited

S. A. Wise, "Pilot Environmental Specimen Bank Program at NBS,

Petrolium Institute, Washington, DC, May 7, 1985. Invited

American
R. A. Durst, "Bioanalytical Sensors," Nova Biomedical, Waltham, MA, May 8,

1985. Invited

S. A. Wise, "Development of a Biomonitoring Specimen Bank in the United

States," 9th U.S. -German Seminar of State and Planning in Environmental

Specimen Banking, Giinzburg, West Germany, May 1 3 » 1985. Invited

S. A. Wise, "Determination of Organochlorine Pesticides and PCB’s in

Environmental Samples," 9th U.S. -German Seminar of State and Planning in

Environmental Specimen Banking, Giinzburg, West Germany, May 15, 1985.

Invited

S. A. Margolis, "Studies on the Measurement of Ascorbic Acid," Infant Formula

Conference, Norfolk, VA, May 15, 1985. Invited

S. A. Margolis, "The Current State of Vitamin Analysis and the Role of Standard

Materials," Infant Formula Conference, Norfolk, VA, May 15, 1985.

Invited

S. A. Wise, "Selectivity in Reversed-Phase Liquid Chromatography," Analytical

Chemistry Division Seminar, University of Stockholm, Stockholm, Sweden,

May 22, 1985. Invited

G. D. Byrd, "Determination of Trace Levels of Organics in Gaseous Samples Using

ID/MS," 33rd Annual Conference on Mass Spectrometry and Allied Topics, San

Diego, CA, May 27, 1985.

M. J. Welch, "Photodissociation of Ions Generated by Fast Ion Bombardment,"

33rd Annual Conference on Mass Spectrometry and Allied Topics, San Diego,

CA, May 27, 1985.

E. A. Blubaugh, "The Detection of Organohalide Compounds at Rhodium Porphymin

Derivatized Polymer Filter Electrodes," Chicago, IL, May 28, 1985.

L. R. Hilpert, "GC/MS Methods for the Analysis of PAH in Diesel Particulates:

Certification of a Diesel Particulate Standard Reference Material," 33rd

American Society for Mass Spectrometry Meeting, San Diego, CA, May 28,

1 985.

R. A. Durst, "Electrochemical Sensors for Monitoring Metabolic Activity in

Biochemical Reactors," Process Measurements for Biotechnology, NBS and

Lehigh University, National Bureau of Standards, Gai thersburg , MD, May 29,

1985.

L. R. Hilpert, "Trace Organic SRM's for Environmental Measurements," 33rd

American Society for Mass Spectrometry Meeting, San Diego, CA, May 29,

1985. Invited

M. J. Welch, "The Certification of Organic Analytes in SRM 909 Human Serum by

Isotope Dilution Mass Spectrometric Definitive Methods," Workshop on Standard Reference Materials for MS, 33rd Annual Conference on Mass

Spectrometry and Allied Topics, San Diego, CA, May 29, 1985. Invited

128
G. S. Marbury, "A Thin Layer Spectral and Coulometric Approach to the

Characterization of a Series of Copper Dithiolene Complexes," 1985

Electroanalytical Symposium, Chicago, IL, May 31, 1985.

D. K. Hancock, "Structural Elucidation of Proteins by NMR," Department of

Chemistry, University of Maryland, May 1985.

R. A. Durst, "Sources of Error in Ion-Selective Electrode Potentiometry ,

Chemistry Department Seminar, Shanghai Normal University, Shanghai, China,

June 7, 1985. Invited

R. A. Durst, "Ionic Activity Standards for the Calibration of Ion-Selective

Electrodes," Chemistry Department Seminar, Shanghai Normal University,

Shanghai, China, June 8, 1985. Invited

R. A. Durst, "Chemically Modified Electrode Sensors," International Symposium

on Ion-Selective Electrodes, Shanghai, China, June 12, 1985. Invited

D. J. Reeder, "Electrophoresis: Techniques and Applications in Analytical

Chemistry," Food and Drug Administration, Washington, DC, June 1 -4

, 1985.

Invited

R. A. Durst, "Analytical Applications of Chemically Modified Electrode

Sensors," Departments of Physical and Analytical Chemistry, Peking

University, Beijing, PRC, June 20, 1985. Invited

L. C. Sander, "Recent Advances in the Characterization of Bonded Phases,"

Silanes, Surfaces, and Interfaces Symposium, Snowmass, CO, June 21, 1985.

S. A. Wise, "Investigations of Selectivity in Reversed-Phase LC on Chemically

Bonded C -j g Phases," Silanes, Surfaces, and Interfaces Symposium, Snowmass,

CO, June 21, 1985. Invited

L. C. Sander, "Physical Properties of Alkyl Bonded Phase Sorbents," 9th

International Symposium on Column Liquid Chromatography, Edinburgh,

Scotland, July 1, 1985.

3. Committee Assignments

Willie E. May

Chairman, ADABSE, Analytical Workshop Committee

Member, ASTM , Committee D1 9 on Water,

Committee El 9 on Chromatography

Member, ACS, Environmental Chemistry Division

Board of Directors, Washington Chromatography Discussion Group

Member, CRC-Air Polluation Research Advisory Board

Member, Status and Future Reseach Needs for a Database on Polycyclic

Aromatic Hydrocarbons Working Group

Member, NIH Minority Biomedical Instrumentation Review Board

129
Bruce Coxon

Secretary, ASTM, Committee El 3. 07 on Nuclear Magnetic Resonance,

Committe El 3 on Molecular Spectroscopy

Member, Program Committee, 12th International Carbohydrate Symposium

Member, Program Committee, 27th Experimental NMR Conference

Richard A. Durst

Member, ASTM, Committee D1 9 on Water

Member, Board of Advisory Editors, Ion-Selective Electrode Reviews

Member, IUPAC, Committee V on Analytical Chemistry,

Subcommittee 5 on Electroanalytical Chemistry

Member, NCCLS, Subcommittee on Electroanalytical Methods

Subcommittee on pH and Blood Gases

Member, NBS, Research Advisory Committee

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, Subcommittee 6 on Quartz Control Plates

Laurence R. Hilpert

Member, ASTM, Committee D34 on Waste Disposal

Member, ASMS, Environmental Committee

Dennis J. Reeder

Member, AACC, Committee on Standards

Study Group on Total Serum Protein

Associate Member, IFCC, Expert Panel on Drug Effects in Clinical Chemistry

Member, NCCLS, Subcommittee on Total Protein

Robert Schaffer

Member, Area Committee on Evaluation Protocols

Subcommittee on Creatinine

Subcommittee on Thiophylline

Member, NCCLS, Area Committee for Clinical Chemistry

Member, Council for National Reference System in Clinical Chemistry

Other

a. Seminars

September 5, 1984

September 6, 1984

December 17, 1984

L. S. Lee, General Electric Research Center,

"Applications of Molecular Biology to Protein

Modification and Vice-Versa." (Division Sponsor: D. J. Reeder)

Jan T. Andersson, University of Ulm, "Analysis of

Polycyclic Aromatic Sulfur Heterocycles." (Division

Sponsor: S. A. Wise)

Ira S. Krull, Northeastern University, "A New

Photoelectrochemical Detector for HPLC and Flow

Injection Analysis (HPLC-PED and FIA-PED)." (Division

Sponsor: W. A. MacCrehan)
March 18, 1985

March 26, 1 985

April 10, 1985

July 19, 1985

Anne L. Plant, Naval Research Laboratory,

’’Complement-Mediated Vesicle Lysis." (Division

Sponsor: R. A. Durst)

Arthur Hubbard, University of California at Santa

Barbara, "Structure and Composition of the Double

Layer and Electrochemistry of Oriented Molecular

Adsorbates." (Division Sponsor: R. A. Durst)

Martin Blank, ONR, "Surface Processes in Ion Transport

and Nerve Excitation." (Division Sponsor: R. A. Durst)

J. Janata, University of Utah, "Chemically Sensitive

Field-Effect Transistors." (Division Sponsor: R. A. Durst)

b. Conferences Sponsored

October 4-9, 1 984 - W. E. May, NBS/ADABASE Analytical Workshop

October 4-9, 1984 - W. E. May and R. S. Schaffer

,

1 st Annual NBS/NCI

Micronutrient Analysis Q.A. Workshop

• SRM

1) SRM

2) SRM

3) SRM

4) SRM

5) SRM

6) SRM

7) SRM

Certification/Information Values

972A Human Serum Albumin

1614, Dioxin in Isoctane

1650, Diesel Particulate Matter

1580 Organics in Shale Oil

1588 Cod Liver Oil

1589, PCB's in Human Seru,

1829 Alcohols in Reference Fuel

131
IV. Gas and Particulate Science Division

Harry L. Rook, Chief

William D. Dorko, Deputy Chief

A. Division Overview

The Gas and Particulate Science Division conducts research leading to

(a) improved analytical methods for quantitative electron, ion, and photon

microanalysis; (b) improved quantitative x-ray fluorescence analyses; (c)

improved measurements of gaseous species in the atmosphere and in specially

prepared gas mixtures; (d) new or improved methods of laser spectrometry for

the analysis of specific gaseous molecules; (e) new chemometrics techniques

for improved chemical measurements; and (f ) the preparation and certification

of standards for measurement quality assurance in analytical chemistry. The

Division responds to the measurement and standards needs of other federal

agencies, industrial organizations, universities, and state and local

governments. The Division's programs are carried out by five groups with the

research efforts divided approximately equally between the two general areas

of gas analytical chemistry and microanalytical chemistry.

During the past year, the Division has been reorganized to provide an increased focus on new methods of gas analysis using the wide and increasingly versatile range of laser techniques. Dr. Alan Fried has been appointed

as Group Leader of the new Laser Analytical Spectrometry Group. Joining

Dr. Fried are Dr. Barry C. Cadoff of the Gas and Particulate Science Division, Mr. Robert Sams formerly of the Inorganic Analytical Research Division,

and Dr. Lindsay Lloyd, an NAS/NRC Postdoctoral Research Fellow.

Research in laser spectrometry has been carried out in both fundamental

and applied areas. In collaboration with scientists in the Molecular Spectrometry Division, research has been conducted to develop improved lineshape

and fitting algorithms for more accurate diode laser absorption measurements.

The model-calculated lineshapes, which properly compensate for both the phe- nomenon of collisional-broadening or collisional-narrowing , have been shown

to improve the quantitative accuracy of high resolution infrared measurements

by 1 . 5% . Other sources of systematic errors in diode laser measurements have

been studied and substantial improvements have been achieved in analytical

accuracy. The obtainable accuracy has been demonstrated on NO2 in air SRMs.

Diode laser measurements carried out in collaboration with the Gas Metrology

Group have indicated the presence of variable amounts of HNO^ in the NO2 SRMs. The certification measurements have traditionally been made with the

chemiluminescence detector (CD) N0

X analyzer. Intercomparisons carried out on a set of N02/air SRMs resulted in systematically high N02 measurements by

chemiluminescence when compared to diode laser absorption. Subsequent

research has proven that the CD was responding to the HNOt in addition to the

NO2. The results of this research have improved tne Division's most

important output, accurate data on NBS SRMs.

With the separation of laser spectrometry from the Atmospheric Chemistry

Group, research has now focused on the use of car bon- 1 4 and other atmospheric

molecular and isotopic tracers for source identification and apportionment

studies. A second and rapidly growing area of research has been chemometrics. Research accomplishments this year include the first jase of methane,

carbon monoxide, and other carbonaceous gases coupled with 1 ^C measurements
to establish potential sources and balances of these gases. The continuing

research in small sample input to accelerator mass spectrometry (AMS) was essential in determining the 1 content of the methane and CO. Gas samples

can now be analyzed which contain as little as 50 yg-carbon. One of the most

important Chemometrics research developments has been the application of

Simulation Test Data (STD) to the assessment and control of quality in the

evaluation of analytical data. For the complex data-evaluation phase of

chemical analysis, STD thus play a role analogous to SRMs; their importance

is therefore likely to increase substantially with increased and automated

data evaluation systems.

The Gas Metrology Group has initiated several new projects to provide

standard test atmospheres or compressed gas standards not currently available

as well as continuing research in long term projects such as trace toxic

organic gas standards, dry deposition acid rain standards, and new Standard

Reference Material gases. Research has been completed on a method to produce

predictable test atmospheres containing natural levels of tritium. A prototype standard delivery system has been designed to dilute a known concentration of HT in clean air using either the output of an electrolysis cell or a dilute compressed gas standard. This calibration system will be completed,

tested and delivered to the U.S. Air Force for the evaluation of error sources in their Ground Moisture Unit (GMU). This program is a component in

the new quality assurance system being implemented by the Division for the

Air Force laboratory system.

In the toxic organic gas standards program, two new traceable gas

standards have been completed to provide data quality assurance in EPA's

national monitoring programs. The standards each contained four components

at a nominal concentration of 1 ppb. A second and a more ambitious standards

research project has been initiated. A 17 component gas mixture of selected

toxic organic compounds at approximately 10 ppb concentration has been prepared gravimetrically with predicted concentrations for each component. A

gas chromatographic method has been developed using multiple column, multiple

detector sample processing to simultaneously analyze all 17 components. Analytical data have been obtained for this standard consistent with the

gravimetric preparation data. Stability studies are currently underway.

Other group activities include; the development of two new C0 2 gas

standards at concentrations of 200 and 1000 ppm to complete the atmospheric

C02 standards set; the development and evaluation of standards and a predictable dilution system to provide calibration mixtures of S02 in air at concentrations ranging from 100 to 1 ppb. This standards system will be used for

quality assurance in the EPA national dry deposition acid precipitation program; the completion of several new gas SRMs and special gas analyses in the areas of respiratory gases and natural standards; and the evaluation of

pollutant gas levels in indoor air.

During the past year, research in microanalysis has focused on four

areas: compositional mapping; improved quantitative analysis techniques;

improved particle identification procedures; and the development of new SRMs

and other standards for microanalysis.

Research in compositional mapping is a continuing program with partial

funding from the Director's Competence Building program and partial funding

from the U.S. Air Force. Substantial progress has been made in producing

133
direct quantitative digital image maps from the scanning electron microscope

(SEM) and the Analytical Electron Microscope (AEM). Procedures have been

developed to form digital images, corrected for background, which maintain

quantitative integrity in the intensity scale through the entire signal

transformation sequence. These maps may then be combined in the computer to

create new maps where elemental or isotopic ratios are imaged rather than the

original data. Applications of this technology have been developed to

identify particles or small regions of space which have a unique chemical or isotopic signature.

Research on new types of standards for microprobe analysis has received

increased emphasis with the advent of new probes such as the ion microscope,

the Laser Microprobe Mass Analyzer (LAMMA) and the use of combined techniques

on one sample. A new ultrathin glass film on a support substrate has been

fabricated and studied for compositional and structural uniformity. A series

of proposed standards has been prepared, analyzed for homogeneity and composition by electron microprobe and is now ready for analysis by a bulk technique. These standards will provide an important addition to those currently

available to the microanalysis community. Other standards under development

include submicrometer particle standards, a new asbestos standard, and

selected bulk glasses with special compositions to study interelement effects

in quantitative probe analysis.

Other research activities of the group include: the development of

computer-aided imaging for the AEM; investigation of isotopic ratio imaging

using the ion microscope; implementation of an advanced multichannel microRaman spectrometer; a study to define the visibility of chrysotile asbestos

in scanning electron microscopy; and the development of compositional maps of

light element and trace element distributions with the ion microscope.

In x-ray fluorescence (XRF) , research has continued on the development

of a model and computer program for the treatment of interelement x-ray

absorption/enhancement effects. An important advance in this program is the

addition of an algorithm to calculate the spectral output of various types of

x-ray tubes. After extensive testing of this program at NBS, the program was found suitable for the routine analysis of alloys, powdered minerals and

fused specimens. In the area of XRF standards, a cooperative study, with the

NBS Polymers and Radiation Physics Divisions, was undertaken to study radiation damage to polycarbonate substrates which have been used in SRMs. A quantitative relationship has been developed to determine the loss in tensile

strength as a function of X-radiation. As in past years a major output of

the group has been the homogeneity testing and certification analysis of numerous SRMs.

Future research plans for the Division will be influenced by the Center

thrusts in compositional mapping, multicomponent analysis, service delivery,

and to a lesser extent, biotechnology. Research in compositional mapping has

now progressed to where quantitative maps are feasible from most microprobes.

However, combining information from different techniques is difficult at best

because of the large amount of data and the necessity of point by point verification of combined image composition. This problem will be addressed using

direct computer-aided image processing of multiple images, first on previously stored images, and then in an interactive mode as quantitative images

are being developed. A major improvement in multicomponent analysis is being
addressed by the Division’s research in chemometrics . Methods using multivariate analysis techniques to optimize data output and to determine the most

sensitive parameters in a multicomponent analysis procedure are being

studied. This research will be directly coupled with research going on in

all three divisions. In the area of the delivery of NBS services, the Division has consistently been at the leading edge of user needs. This year, a program is being planned with the U.S. Air Force to implement a measurement

quality assurance program which has been tested on a pilot basis. This program will include blind standard materials for the most sensitive analyses,

as well as an automated data verification system. The program will be

implemented throughout all of the Air Force analytical laboratories by next

year

.

1 . Microanalysis Group: Overview

The Microanalysis Research Group carries out research to advance the

development and application of microbeam analysis techniques for the chemical, crystallographic, and morphological characterization of matter on the

micrometer and sub-micrometer spatial scale. The analytical techniques

utilized are based on primary (excitation) particle beams of electrons, ions,

or photons, and secondary (analytical) signals of x-rays, inelastically scattered electrons, inelastically scattered photons, and ions. The techniques

include electron microprobe x-ray analysis, scanning electron microscopy,

electron energy loss spectrometry, secondary ion mass spectrometry, laser

micro-Raman spectrometry, and laser microprobe mass analysis. Research is

conducted on several aspects of each technique, including (1) advancing

understanding of the basic physics of sample excitation and attenuation of

the secondary radiation; (2) developing methods of quantitation; (3) producing standards and techniques as a means of disseminating developments; and

(4) applying results of the research to developing improved compositional

mapping techniques and to the study of specific analytical problems in aid of

NBS and other government agency activities as well as national scientific

priorities

.

During FY85, Group research activities included (1) the development of

quantitative compositional mapping by means of the electron probe microanalyzer; (2) development and investigation of computer-aided imaging in the analytical electron microscope, including the formulation of advanced image analysis techniques for calibration of the magnification; (3) investigation of

isotopic ratio imaging in the ion microscope; (4) implementation of a multichannel micro-Raman spectrometer system; (5) development of a particle

collector for sample submission to the analytical electron microscope and

laser microprobe mass analyzer; (6) study of the visibility of chrysotile

asbestos in the scanning electron microscope; (7) micro-Raman characteri za- tion of a complex borate/carbonate new mineral species; (8) implementation of

advanced signal acquisition and processing for the laser microprobe mass

analyzer; (9) compositional mapping of light elements and trace element distributions with the ion microscope; and (10) measurement of the half-life of

rhenium-187 by laser microprobe mass analysis.

A major accomplishment during FY85 has been the first achievement of

quantitative compositional maps by means of the electron microprobe. This

development has required the extension of the complete procedure used for

135
analysis at individual locations to every point in a matrix array image. In

addition to the usual deadtime, background, standardization, and matrix cor- rection procedures, the effect of spectrometer defocusing, which is peculiar

to scanned images, had to be corrected. The resulting quantitative compositional images had similar accuracy and precision to individual point

analyses. The additional problem of presenting compositional information in

a quantitative fashion in an image viewed by an observer was investigated. A

color encoding scheme based upon the "black body curve" ("thermal scale") was

found to provide an intuitive representation.

Future Plans :

Further development of computer-aided imaging and compositional mapping

is planned, with special emphasis on combining images from different techniques to take advantage of the special attributes of each, such as scanning

electron microscopy for structural imaging combined with ion microscopy for

trace element imaging. In the area of analytical electron microscopy, we plan to implement computer-aided imaging of the conventional static transmission electron image and static electron diffraction modes to complement the

digital imaging capabilities which have now been established for the scanning

imaging functions. Further development of advanced image processing software

is planned to carry out high level automated analyses of particle arrays with

minimal operator intervention. Automatic interpretation and analysis of

electron diffraction patterns will be investigated as an important analysis

mode to complement morphological and compositional information. Acquisition

of quantitative secondary ion images in the ion microscope will be investigated. Studies of signal generation and detection in the laser microprobe

mass analyzer will seek to place that analysis method on a quantitative

basis. In the area of molecular microanalysis, we will continue to improve

the multichannel micro-Raman spectrometer. Studies of the molecular

microanalysis by laser microprobe will attempt to define sensitivity and

spatial resolution.

Dale E. Newbury, Group Leader; Adville A. Bell, David S. Bright, Peter H.

Chi, Edgar S. Etz, Robert A. Fletcher, Ryna B. Marinenko, Raymond L. McKenzie, Robert L. Myklebust, Thomas R. Pereles, Patrick J. Sheridan, David

S. Simons, John A. Small, Eric B. Steel, and Barbara B. Thorne.

2. X-Ray Fluorescence Group: Overview

Major continuing efforts of the X-Ray Fluorescence Group have been

directed to the improvement of the accuracy and sensitivity of x-ray fluore- scence spectrometry for the determination of elemental composition. To

achieve these goals, research on first principle data reduction methods has

continued with the intent of increasing the accuracy of elemental quantitative analysis. Development of improved sample preparation techniques to

increase the analytical sensitivity also remains an important activity of the

group. A considerable portion of our work is oriented towards the quantitative analysis and homogeneity testing of new, and renewal SRMs. In addition,

we maintain current expertise in the fabrication and characterization of new thin glass films for XRF calibration.

During the past year, we have published a first principle computer

program which uses theoretical corrections for treatment of interelement

x-ray absorption/enhancement effects in bulk specimens. An important feature

136
of this program is an NBS-developed algorithm for the calculation of the

spectral output distribution of x-ray tubes. The computer program called

NBSGSC is a result of a cooperative effort between NBS and the Geological

Survey of Canada and was developed primarily in response to a need in the

x-ray fluorescence community for a generally available first principles com- puter program specifically for minicomputers. The fact that NBSGSC is not a proprietary document, unlike most software available from vendors, allows

maximum flexibility in its implementation. After extensive testing of this

program at NBS including intercomparison with other data reduction

procedures, we propose that NBSGSC is suitable for routine analysis of alloys

and minerals, both as powders and as fused specimens.

A closed-system apparatus has been constructed for automated

preconcentration of trace elements from solutions onto films impregnated with

either ion-exchange resins or various specific chelating ligands. This procedure will allow rapid equilibration of the collected ions with the active

sites of the filter, substantially reducing the time for obtaining quantitative recovery of the ions, and therefore preconcentration will no longer be

the limiting step in a separation. An evaluation of this apparatus is cur- rently in progress, and the experience gained from this prototype will enable

us to advance preconcentration methodology for x-ray analysis.

A cooperative study with the NBS Polymers and Radiation Physics

Divisions has been undertaken to characterize the radiation damage to polycarbonate substrates which occurs when the films are exposed to X-radiation

from high-powered x-ray tubes. The substrates are used in NBS/SRM thin film

standards for XRF calibration. This work was performed to establish guidelines regarding expected film lifetime for users of these SRMs. A quantitative relationship was found between the amount of X-radiation a film received

and loss of tensile strength. Further work is in progress with radiation

dosimeters to intercompare radiation levels from various types of

spectrometers with the intent of establishing guidelines for users.

Finally, during the past year several kinds of samples such as cements,

coal, refractories, glasses, tungsten carbide, and over two hundred austenite

samples were measured for either elemental homogeneity and/or quantitative

analysis.

Future Plans :

Future plans in x-ray fluorescence research focus on shedding more light

on the uncertainties in the fundamental parameters used in first principle

calculations of elemental composition, in an effort to determine their influence on accuracy. We plan to study the influence of different sources of mass absorption coefficients in XRF analysis. The fabrication of a limited

number of new thin glass films for calibration and quality assurance studies

will continue. These films will be used as research materials by the

Environmental Protection Agency.

Our efforts in preconcentration methodology are expected to increase

significantly next year with the arrival of a guest worker who will devote

full time to this project. We intend to automate the quantitative collection of trace elements from solution and to initiate work on filters

containing specific chelating ligands for preconcentration.

137
In the area of SRM characterization, we plan to evaluate the homogeneity

and analyze several types of alloy materials.

Peter A. Pella, Group Leader; Anthony A. Marlow, John R. Seiber, and Gerald

A. Sleater.

3. Atmospheric Chemistry Research Group; Overview

The mission of the Atmospheric Chemistry Research Group comprises: a)

the development of advanced measurement techniques, plus standard materials,

instruments and data for the scientific investigation of trace gases and particles in the atmosphere; and b) basic studies of the design and evaluation

of the Chemical Measurement Process, using modern mathematical and statistical methodology, in order to enhance the precision, accuracy and sensitivity

of analytical measurements. Research emphasis during the past year has been

on high-accuracy atmospheric ozone photometry, source apportionment of atmospheric carbon plus advances in 4 C accelerator mass spectrometry, and the

application of simulation test data to the assessment of accuracy in the

evaluation of analytical data.

Basic measurements of the ozone absorption cross section as a function

of wavelength and temperature are being continued, under Air Force sponsorship, to cover the region 350-700 nm. This work extending into the visible

part of the spectrum will complement the NBS UV absorption cross section data

which has been recommended by the World Meteorological Organization’s meeting

of experts for the determination of atmospheric ozone concentrations from

satellite UV radiance measurements. Modification of the apparatus used for

the earlier UV work is underway in order to attain sufficient sensitivity to

measure the small absorption cross section in the visible region.

Two additional Standard Reference Ozone Photometers have been fabricated

and calibrated, and delivered to the EPA, for inclusion in the national monitoring network. The network will be further augmented by Standard Photometers No. 7 and 8; these are under construction, and scheduled for delivery

in December 1985.

Atrirospheric carbon research has emphasized advances in the measurement

capabilities for 1 samples containing less than 100 pg-C and also for

natural materials having extremely small ^ C/^C ratios — ca. 1x10 and

below. These measurement advances are being pursued in collaboration with

accelerator mass spectrometry (AMS) groups at the Universities of Arizona and

Rochester, and ETH in Zurich. Approaches include extremely clean, singlecompartment chemical processing, and isotopic enrichment via electromagnetic

(E-M) ion separation and micro-thermal diffusion. A manuscript in press

gives the first application of the E-M method to AMS; in this experiment

we detected a signal equivalent to just 1^0 ng of modern carbon.

1 H The objectives of the extended natural C measurement capabilities

include the study of very rare nuclear processes in nature and the investigation of individual organic fractions of atmospheric gases and particles to

identify sources of toxic and climatically - active species. During FY85 we published the first data on

4 C in ambient methane; such data are quite

important in terms of natural vs. anthropogenic sources of the increasing

atmospheric concentrations of this important ’’greenhouse" gas. The importance of ' 4 C measurements in establishing the woodburning contribution to
local air pollution has led to our participation in the EPA Integrated Air

Cancer Project. Samples obtained from Raleigh and Albuquerque during last

winter's woodburning season will be separated into selected chemical fractions for individual 1 measurements. In this way we may obtain reliable,

quantitative information on the woodburning contribution to such noxious

species as the polycyclic aromatic hydrocarbons.

Work in the area of chemometrics has included participation in Center

and international committee activities related to: a) quality assurance and

statistics in analytical chemistry; and b) interlaboratory data-evaluation

quality assessment and improvement through the use of multivariate (MV) simulation test data (STD). Committee activities have included work on the CAC

Quality Assurance Task Force, the thrust of which has been with the quality

of laboratory records, reports of analysis, and (statistical) characterization of methods and reporting of data. Work with Commission V.3 of IUPAC has

been directed toward internationally-accepted nomenclature for the evaluation

of analytical methods. Two drafts on this topic have been prepared for IUPAC

during the current year.

The original NBS Receptor Modeling multivariate STD chemometric

intercomparison exposed a number of subtle, assumption and modeling pitfalls

in the evaluation of multivariate data. The STD have, as a result, become a research data set (in analogy with research SRM applications), important for

developing improved and robust methods of MV chemical data evaluation. We

reported on the role of STD in chemometric QA and method development at the

first NBS Chemometrics Symposium in May, 1985.

Research activities for FY86 will include: a) completion of the final ozone Standard Reference Photometers (No. 9 and 10) for the EPA National

ozone monitoring network, plus establishment of a definite protocol for maintenance and recertification of network instruments relative to the NBS primary standard; b) measurements of the ozone absorption cross section extending to 700 nm, plus initiation of absolute cross section measurements at the

wavelengths of the Hg UV lines; c) completion of the first phase of the

Integrated Air Cancer Project, including further development of microradiocarbon chemistry for the assignment of sources of individual classes of

toxic organic species; d) continued investigations of carbon isotopes in

atmospheric gases and volatile organic matter; e) application of isotopic

enrichment - AMS methods to the study of rare nuclear reactions and rare geological or archeological samples; and f) basic studies of experimental design

and multicomponent data analysis with emphasis on modeling accuracy,

detection limits, and the incorporation of 'scientific intuition'.

L. A. Currie, Group Leader; A. M. Bass, G. A. Klouda, J. E. Norris, W.

Ollison, A. E. Sheffield, T. Stafford, J. M. Sullivan, and R. M. Verkouteren.

4 . Gas Metrology Research Group: Overview

The Gas Metrology Research Group conducts fundamental and applied

research leading to a) the improvement of measurements for ambient, trace,

and ultra-trace gas analysis, and b) the development of accurate and stable

gas standards for a wide variety of inorganic and organic species ranging in

concentration from the percent level to 1 ppb.
Reliable inorganic and organic gas standards are developed to provide

data quality assurance in measurements made in federal and state programs and

by the U.S. industrial community. Analytical measurements and research are carried out to ensure that the resultant standards are both accurate and

stable. Research also is carried out in an attempt to improve the scientific

understanding of the causes of chemical instability of gas mixtures, to more fully characterize spectroscopic and chromatographic detection parameters,

and to gain a better understanding of the basic properties of gas molecules

that affect accurate gas analysis and the certification of gas standards.

The Group directly responds to and interacts with gas measurement and

standards needs of other agencies, industrial organizations, and standardssetting bodies at the local, state, and national levels, and also performs a limited degree of gas analyses for external organizations.

Activities and accomplishments of the Group during the past year are highlighted in the following sections:

During the past year, new C02 in air SRMs at 340 and 375 ppm were certified in a program jointly sponsored by the U.S. Department of Energy's

Carbon Dioxide Research Division and the NBS Office of Standard Reference

Materials. These SRMs are intended for research and monitoring programs to assess global changes in atmospheric C02

. The addition of these two SRMs

makes a total of five such SRMs now available in the 300-400 ppm range of

interest. These new SRMs also have been certified for N

2 0 at 300 and 335

ppb , with information values provided for methane and for halocarbons F— 1

1

and F— 1 2 . Confirmatory analyses of C02 by absolute manometry at the Scripps

Institution of Oceanography further validated the Group's absolute

gravimetric procedure used for preparing primary gas standards. Work on an isotope-dilution technique using a specially designed mass spectrometer system developed in the Inorganic Analytical Research Division is nearing

refinement as an independent NBS reference method for accurate measurements

of C02 in air.

In a continuing NBS/EPA program to provide data quality assurance in

national ambient and hazardous waste incineration measurements, two stable

multi-component toxic organic gas standards were prepared at the 1 ppb level.

One of these contained benzene, toluene, bromobenzene , and chlorobenzene; the

other contained vinyl chloride monomer, chloroform, carbon tetrachloride, and

tetrachloroethylene. In addition, the Group evaluated the feasibility of

developing a 17-component accurate and stable mixture of toxic organics at

the 10 ppb level. Such mixtures are needed for the accurate analysis of

ambient air samples using capillary GC-MS. Research also was carried out for

the development of eight-component standards at 150 and 10 ppb (representing

EPA's "Group Three Organics") and a five-component mixture at 2 ppm (representing EPA's "Group One Organics"), for EPA's hazardous waste incineration

program. SRMs completed during the past year included two multi-component

SRMs at 10 ppm and 250 ppb containing benzene, toluene, chlorobenzene, and

bromobenzene, and a tetrachloroethylene permeation device. The Group's present inventory of primary standards for this program comprises over 80 gas

cylinder mixtures, covering about 25 organics over a range of 50 ppm to 1 ppb.
Work under the Group's Air Force (AFTAC) project included the development of a stable source of tritium as a calibrant for the detection of

changes in the atmospheric tritium level (nominally, about 10~ -5 ppm).

Work also was completed on the development of a set of homogeneous gas standards of tritiated methane for use by AFTAC laboratories in measurements of

atmospheric tritiated methane. A new electrolysis cell was developed and

evaluated as a stable, predictable source of tritium. A prototype tritium

calibration system is presently being designed and fabricated for delivery

to AFTAC in early 1986.

A new NBS/EPA project focusing on the development of calibration

mixtures of SO2 in air for dry acid deposition studies, validated the feasibility of such standards at 100 ppb. A dynamic dilution system intended for

field use has been designed and is being evaluated for the predictable dilution of such standards down to 1 ppb. Calibrations have been based on the

use of an SO2 dilution system using pulsed fluorescence and flame photometric

detectors. Temperature and input pressure effects on the performance of the mass flow controllers used for the dilution system have been quantified.

Work in two related areas also was initiated: viz., an evaluation of the feasibility of developing stable standards of NO in N

2 at 100 ppb and of H2 S in

N

2 at 5-20 ppm. The latter standards also are needed for calibrating

reduced sulfur emissions produced by the U.S. pulp and paper industry.

In a program supported by the Chemical Manufacturers Association,

research was carried out to quantify the temperature dependence of band

strengths for halocarbons F — 1 1 and F-12 at stratospherically-relevant temperatures. This research was conducted using Fourier-transf orm infrared

spectroscopy and a specially-designed cryogenic gas cell. The results of

this research will provide base-line data for quantifying and predicting

fluorocarbon levels in the earth's upper atmosphere.

Other research accomplishments of the past year have included:

o The certification of four new SRMs containing carbon dioxide and

oxygen specifically designed for blood gas measurements. Such mea- surements are made at a level of hundreds of thousands annually in

hospitals throughout the U.S. These are the first such standards

produced by NBS, and were developed at the request of a national

committee for clinical laboratory standards.

o A detailed analytical characterization of natural gas standards to

provide NBS traceability to both GC and calorimetric measurements of

natural gas made throughout the U.S. These measurements were made to

minimize the potentially significant fiscal error associated with

the uncertainty of such measurements as the U.S. converts from

billing by volume to billing by BTU and changes from calorimetry to

GC analysis for such measurements.

o A study involving real-time measurements of pollutant gases (SO2

, N0X , and 0^) in storage and reading room areas was carried out at

the request of the National Library of Medicine to allow it to assess

its potential needs for upgrading the facility's air handling systems. A detailed report of the findings has been prepared and

submitted.
o Research studies using chemiluminescence and diode laser spectroscopy

resulted in the detection and quantification of nitric acid as a heretofore undetected species in N02 SRMs.

o Research was carried out for the development of an electrochemicallybased analysis system for S02 mixtures, representing the first serious venture of the Group into the development of absolute electrochemical methods (i.e., traceable to the coulomb) for gas analysis.

The first prototype system designed for this purpose (based on the use of electrodes and photocells) has provided a precision error of

less than \% for the analysis of a number of 50 ppm S02 SRMs.

Future activities of the Group will involve: a) the certification of

C02 in air SRMs at 100 and 1000 ppm to assist agricultural research on the

potential effects of changing levels of atmospheric C02 on vegetation growth;

b) the continued development of NBS-traceable toxic organic standards for

ambient monitoring and hazardous waste incineration audits (including two new multi-component toxic aliphatic organic mixtures as SRMs); c) the continuation of research on the development of electrochemically-based systems for

the analysis of polar gases; d) automation of the Group's inorganic mass spectrometer; e) the development of low ppb mixtures of S02

, NO, and H

2 S dry

acid deposition research; and f) continued research on fundamental

spectroscopic properties of important gas species.

Group staff changes during the year have included the transfer of

Dr. Barry Cadoff to a new Analytical Laser Spectrometry Group. Francois

Abbo, from the Center for Research and Development of L'Air Liquide, Paris,

France spent eight months in the Group as a Research Associate in the areas

of reactive gas instability and statistical methods for gas analysis. The

appointment of a second scientist (Zhong-tao Cai , from the Shanghai Institute

of Ceramics) was renewed for a second year as a Guest Worker involved in the

analysis of ultra-trace levels of reactive gases. Another Guest Worker from

the People's Republic of China will be joining the Group in November of this

year

.

More detailed write-ups of selected activities and accomplishments of

the Gas Metrology Research Group are provided in the following section.

Walter L. Zielinski, Jr., Group Leader; Z.-T. Cai, William F. Cuthrell,

William D. Dorko, James W. Elkins, Ernest E. Hughes, Patricia, A. Johnson,

Rudolph Von Kelly, Gerald D. Mitchell, W. Robert Miller, Richard D. Myers,

George C. Rhoderick, James E. Suddeuth

5. Analytical Laser Spectrometry Group: Overview

Research in analytical laser spectrometry has been carried out in

previous years in the Atmospheric Chemistry Group. However, because of the

extensive and rather specialized nature of this field a new group, the Analytical Laser Spectrometry Group, has been formed this year. The Analytical

Laser Spectrometry Group conducts research on the development, characterization and application of state-of-the-art laser-based spectroscopic techniques

for the detection of trace and ultra-trace level gaseous atmospheric constituents. The analytical techniques utilized include a) photoacoustic spectroscopy, b) phase fluctuation optical heterodyne detection, c) photothermal

deflection, and d) tunable diode laser and Fourier Transform IR (FTIR)

1 1J2
absorption spectrometry . A primary objective of the research carried out in

the group is the improvement of measurement sensitivity, selectivity and

accuracy of these various techniques for the analysis of trace reactive

atmospheric gases. Other objectives include: (1) development of new calibration approaches for the above laser-based techniques; (2) measurement of

fundamental molecular parameters necessary for quantitative spectrometry such

as infrared absorption, pressure-broadening and collisional-narrowing coefficients; (3) intercomparison of concentration determinations by various techniques; and (4) application of tunable diode laser spectrometry in the

verification of gas standards and in kinetic measurements of transient

species

.

Research this past year, both fundamental and applied, has focused on tunable diode laser absorption spectrometry (TDLAS). In collaboration with

the Molecular Spectroscopy Division, research has been conducted to develop

sophisticated lineshape and fitting algorithms for accurate quantitative

diode laser measurements. These sophisticated lineshapes, which not only

incorporate the phenomenon of collisional-broadening but also collisionalnarrowing, have been shown to improve the quantitative accuracy of high reso- lution infrared measurements by 1-5?. In addition, studies have also been

completed that identify and characterize much larger systematic error sources

(in the 5~30? range) in diode laser measurements carried out in the direct

absorption mode. Such sources, which are caused by multi-mode lasing, can be

manifested in a variety of different ways. This will be further discussed in one of the selected technical reports that follow.

Significant progress has also been achieved this past year on a number

of other fronts to improve the accuracy of direct absorption tunable diode

laser measurements for the determination of trace atmospheric constituent

concentrations and fundamental molecular parameters. First, all direct

absorption measurements are now carried out simultaneously with relative frequency measurements from a high resolution confocal interferometer using a double beam set-up. This instrument, as discussed in last year’s report,

allows the laser linewidth to be determined for each absorption feature under

study. The double beam configuration implemented this year, further eliminates relative frequency drifts due to drifts in temperature that arise when

the absorption and interf erometer spectra are recorded at different times.

Secondly, we have adopted the technique of sweep integration in our direct

absorption measurements. In this data acquisition mode, the diode laser is

repetitively swept at high repetition rates through each spectral region of

interest and the data from many such repetitive scans is averaged in a dualchannel signal averager. This technique was found to significantly reduce

the problems associated with frequency instabilities which can occur using

the more traditional slow scan (fixed frequency integration) procedure. As a final improvement in our set-up achieved this past year, we have interfaced

the signal averager to a laboratory microcomputer. Data analysis can now t- carried out using the newly developed line fitting algorithms directly on th<

digitized absorption spectra output from the signal averager.

In the area of applied research, TDLAS has been employed this past yea^

in the analysis of high concentration NC^/air (250-2500 ppm range) compressed

gas standards. Such studies are part of our long term effort to verify gas

standards employing independent measurement techniques. This resear:,,

carried out in collaboration with the Gas Metrology Research Group, was initiated because the traditional technique of Chemiluminescence Detection < ",
is not specific to N02

. Other nitrogen oxide species, if present, would also

be simultaneously detected thus causing systematically high CD N02 determinations. TDLAS, on the other hand, is very selective and is therefore not sus- ceptible to this systematic error. Inter comparisons carried out on a selected group of N02 /air cylinders resulted in systematically high CD determinations of N02 in the 5—1 5% range. Additional TDL measurements in a different spectral region unequivocally identified the presence of HNOo in each

of the cylinders examined. Subsequent measurements revealed that the CD was

in fact responding to HNO^ in addition to N0?

. This gas has since been found

in each and every high concentration N02 cylinder (over 25) examined to date.

The Group has also been active this past year in recommending, and

subsequently in providing guidance and oversight, to NASA in the design and

construction of an ultra- trace level N02 calibration system. This system

will play an integral part in field experiments carried out later this year

as part of NASA’s Global Tropospheric Experiment. Because of this importance, significant group effort is being expended in planning and implementing a series of laboratory intercomparisons utilizing Gas-Phase-Titration

(GPT) , N02 permeation, and TDLAS to calibrate the NASA system.

Research planned for the upcoming year will continue many of the efforts

initiated this past year. In particular, research will focus on employing

TDLAS in: (1) the re-investigation of GPT, (2) the determination of absorption and pressure-broadening coefficients for selected lines of N02

, (3)

studies to characterize HNO^ in high concentration N02 /air compressed gas

cylinders, (4) in research efforts to develop a dynamic HNO^ generation and

calibration system for ppm and sub-ppm concentration levels, (5) the implementation of procedures and protocols by which EPA can calibrate a mobile

TDLAS for field measurements of N02 , (6) the continued investigation of systematic error sources, and (7) in the determination of absorption

coefficients for H02

.

Alan Fried, Group Leader; Barry Cadoff, and Linda Nunnermacker

.

1
B. Selected Technical Reports

(Gas and Particulate Science Division)

1 . Development of Ultra-Trace (1 ppb) and SRM Multi-Component Toxic Organic

Gas Standards

W. F. Cuthrell, G. C. Rhoderick, and W. L. Zielinski, Jr.

Two of the major accomplishments during the past year in a continuing

NBS/EPA program for the development of standards of toxic organic gases for

national ambient air monitoring programs have been: a) the development of

multi-component aromatic and aliphatic toxic gas mixtures at nominal concentrations of 1 part-per-billion (ppb); and b) the certification of two fourcomponent aromatic gas SRMs at nominal concentrations of 10 part-per-million

(ppm) and 250 ppb.

a . Multi-component Toxic Organic Gas Standards at 1 ppb :

Two NBS-traceable toxic organic gas standards were gravimetrically

prepared in the 1 ppb range and were analytically verified. The first was a four-component aromatic mixture of benzene, toluene, chlorobenzene, and bromobenzene in nitrogen, characterized at concentrations of 0.93, 0.88, 1.42,

and 1.22 ppb by mole, respectively. The uncertainties of these concentrations at the 95? confidence level were 0.07, 0.07, 0.06, and 0.08 ppb,

respectively. The second was a four-component aliphatic mixture of vinyl

chloride monomer, chloroform, carbon tetrachloride, and tetracholorethylene

in nitrogen, characterized at concentrations of 0.90, 1.08, 1.15, and 1.85

ppb by mole, respectively. The uncertainties of these concentrations were

0.08, 0.04, 0.03, and 0.04 ppb, respectively. These standards have been used

in EPA field studies to quantify and evaluate sampling procedures for toxic

organics in ambient air. A six-month reanalysis of these standards has shown

the concentrations of all of the analytes to be unchanged since the preparation of the standards. These standards represent the lowest concentrations

of gaseous toxic organics prepared to date which are both accurate and

stable

.

b . Certification of Multi-component Toxic Aromatic Gas SRMs :

Two fifty-cylinder batches of compressed gas containing benzene,

toluene, chlorobenzene, and bromobenzene in nitrogen were certified as SRMs

during the past year at nominal concentrations of 10 ppm and 250 ppb, respectively. The certification process involved: (a) the preparation of primary

gravimetric gas standards containing each of these analytes at concentrations

bracketing the two SRM concentrations; (b) characterization of randomlyselected samples ("internal standards") from each batch, using the primary

gravimetric gas standards; (c) intercomparative analyses of all samples in

each of the two batches with the characterized batch internal standards, to assess batch homogeneity and long-term stability of the samples; and (e)

final analytical rechecks. The uncertainty of the analyte concentrations at

the 95? confidence level in each batch varied from less than 1? relative for

benzene to less than 2? relative for bromobenzene. These SRMs represent the

first multi-component toxic organic gas SRMs certified by NBS, and are intended for the calibration of instruments and methods for the analysis of

these analytes in ambient air.
2. Sampling and Analysis of Nitrous Oxide, Carbon Dioxide, and Methane to

Characterize Nitrogen and Carbon Cycles During NITROP-85 Cruise in the

Peru Coastal Upwelling Region

J. Elkins

The coastal waters off Peru are an area of high biological productivity

which are fed by nutrient rich Antarctic seawater. Biological rates for the

transformation of both nitrogen and carbon into useful nutrients for plant

and animal life are the highest in this region of the ocean. High rates for

photosynthesis by plankton in the surface water yield an oxygen deficient

zone at 150-300 meters depth produced by the decay of falling organic material. The "Nitrogen Transformations in the Oxygen Minimum Zone off Peru" or NITROP-85 cruise between February 1 and March 4, 1985, was sponsored by the

National Science Foundation. This cruise offered an excellent opportunity to

study these transformations and compare these results with previous work com- pleted in March 1978. Scientists from four countries participated in this

expedition representing Bigelow Laboratory, Duke University, Harvard University, University of Copenhagen, Scripps Institution of Oceanography, and the

National Bureau of Standards.

Three biologically mediated gases, nitrous oxide (N2 0), methane (CH^),

and carbon dioxide (C02

) , were measured by gas chromatography on board Oregon

State University's ship, the R/V WECOMA. In total, more than 300 air samples

and 800 water samples were analyzed during the cruise. The gas standards

used to calibrate the gas chromatographs were prepared at NBS. These same standards were used to certify a series of gas Standard Reference Materials

(SRMs) for C0 2 and N

2 0 with information values for CHjj and halocarbons F— 1

1

and F-12. All three gases measured may contribute to the predicted "greenhouse effect" warming in the atmosphere by absorbing re-radiated infrared

energy from the earth's surface. Characterizing oceanic sources and sinks of

these gases may help in our understanding of the complex interaction between

the ocean and atmosphere.

The preliminary findings indicate that the highest N

2 0 saturations

occurred in the surface waters at stations exhibiting strong coastal

upwelling. Indeed, the highest value of N

2 0 (8.5 micrograms per liter) ever observed in the open ocean was at 8 meters depth near 10° S. Generally, N

2 0

varied inversely with the dissolved oxygen concentration, indicating a nitrification or ammonium (NH^) or nitrite (N02

) oxidation source. This trend

continued until mixing occurred with very low dissolved oxygen water ( < 0 .

1

mL/L) in the secondary nitrite maximum or region of denitrification (reduction of nitrate, NOo, to dinitrogen ga_s , N

2

). In this region, the concen- tration of N

2 0 was lowest where the N02 was the highest. This was indirect

evidence that N

2 0 is consumed during denitrification. Profiles of N

2 0 during

this cruise showed that regions for sinks of N

2 0 were closer to the coast and

existed in some locations as two distinct minima in the water column, whereas

data from 1978 had only one minimum at 200 meters. High supersaturations of

methane with respect to air were observed below 50 meters in coastal stations

near 15° when hydrogen sulfide (H2

S) was present. All surface water samples

were supersaturated with respect to atomspheric C02.
3 . Application of Electrochemical Methods for the Absolute Measurement of

SOg Gas SRMs

G. D. Mitchell and A. A. Bell

Gas Standard Reference Materials (SRMs) with few exceptions are certified from primary gas standards prepared gravimetrically . Sulfur

dioxide gas mixtures have been difficult to prepare as a stable primary standards. Because of the difficulty of preparing S02 standards gravimetrically,

the peroxide titration method is used to certify the concentration. The

peroxide method has problems of imprecision which require extensive analyses

in order to develop a satisfactory level of statistics to specify the

concentration of S02 in SRMs.

Recently, research on an electrochemical method was initiated in an attempt to establish an absolute method of analysis with traceability to the

coulomb. The chemistry involved in the electrochemical method is identical to

that of the peroxide titration method. The coulometric method explored here

is specific to the determination of S02 in a gas stream. This is realized by

feeding back the amplified photometric end-point detection output as a coulometric titration current. With sulfur dioxide, sodium hydroxide is generated

at the cathode at a rate equivalent to the rate of formation of sulfuric acid

(from the reaction of S02 with H

2 0

2

) and at equilibrium the current is

proportional to the concentration of sulfur dioxide in the gas stream.

The primary criteria for a successful procedure is recognized as (1)

complete current efficiency, and (2) complete reaction of S02 with H

2 02

.

Reaction ;

Sulfur dioxide reacts with hydrogen peroxide to form sulfuric acid:

S02

+ H

2 02 = H2

S0i, = 2H

+

+ SOj

When current flows through the electrochemical cell the cathode reaction

is

2 Na

+

+ 2 H

2 0 + 2e =2 NaOH + H

2 and the sodium hydroxide generated neturalizes the sulfuric acid

2 NaOH + H

2 S04 = Na2

S0ij + 2 H

2 0

The electrode system used in this study is a platinum cathode and a silver anode with an alternative cathodic and anodic reaction of

2H

+

+ 2e“ = H

2

Cl + Ag = AgCl + e

1 M7

and
The results to date using S02 in nitrogen SRMs at the 50 ppm level reveal

that the relative precision of the method is comparable to that of the

peroxide titration method.

Work is continuing on the assessment of precision and accuracy,

improving the current efficiency, and the sensitivity to the part-per-billion

level

.

4. Measurement of Nitric Acid in High Concentration NO? SRMs Using Diode

Laser Spectroscopy Coupled with Chemiluminescence Analysis

W. Dorko, A. Fried, R. Sams, and Z.-T. Cai

There are currently four gaseous SRMs of nitrogen dioxide (N02

) in air

available from NBS, ranging in concentration from 250 to 2500 ppm. The great

majority of users of these SRMs will employ them to calibrate chemiluminescent detectors (CD) to analyze for N02 in the atmosphere, or in emissions

from industrial stacks. Because of the predominant use of CD for this purpose, the SRMs were certified using this technique. The CD is basically a nitric oxide (NO) analyzer in which the detector responds to the light given

off by the gas phase reaction of ozone (0^) with NO. To measure N02

, the

sample is passed through a hot stainless-steel reaction chamber to convert

the N02 to NO, following which the sample passes into the detector where the

NO reacts with 0^ and is detected. Other nitrogen compounds, such as HNO^,

N

2 0jj, and N

2 0^ can also be converted to NO in the reaction chamber. In such

cases, the CD serves as an N0X detector. Research was carried out in which

the CD was coupled with a tunable diode laser absorption spectrometer (TDLAS)

to more specifically characterize the composition of the N02 SRMs. The N02 level determined by the TDLAS was found to be consistently lower than the N02 level as determined by the CD. The TDLAS was subsequently scanned through

other spectral regions, revealing the presence of nitric acid (HNO^) in the

N02 SRMs. When the HNO^ and N02 contents determined by TDLAS were added

together, the results came much closer to those obtained using the CD. This

finding indicated that both N02 and HNO^ are converted to NO in the CD reaction chamber. Literature reports indicated that nylon selectively scrubs

HNO^ from N02 mixtures; therefore, a nylon scrubber was fabricated, tested,

and found to be very selective for HNO^. This scrubber, in conjunction with

the CD, was then used to determine the HNO^ content in a number of cylinders

of each of the four SRMs. This was done by observing the difference in the

N0X signal with and without the scrubber.

At the 250 ppm N02 level (SRM #2653), ten cylinders were analyzed for

HNOo, providing HNO^ values ranging from 9 to 24 ppm. Nine cylinders of SRM

#2654 (500 ppm N02

) were analyzed, for which HNO^ ranged from 48 to 67 ppm.

For SRM #2655 (1000 ppm N02

), five cylinders had a range of 29 to 39 ppm. A

range of 49 to 116 ppm HNOo was detected in nine cylinders of the 2500 ppm

N02 (SRM #2656)

.

The finding of HNO^ in these cylinder mixtures at such relatively high

levels was unexpected. However, this finding does not adversely effect their

utility as N02 standards, since essentially all of the measurements for which

they are used are for total N0X.

148
5 . Development of New SRMs for C09 in Air at Atmospheric Concentrations

for World-Wide Monitoring of Atmospheric C02 Changes

E. E. Hughes, J. Elkins, and W. L. Zielinski, Jr.

During the past year, four important SRMs were certified for both C0 2

and N

2 0 in the ambient concentration range of 300-400 ppm by mole and 250-350

ppb by mole, respectively, in both 150 and 30 cubic-foot cylinders. These

SRMs are intended to serve the world-wide C0 2 research community’s needs for

standards to provide long-term quality data for accurate monitoring of the

upward trend of global C02 in the atmosphere. One of two fifty-cylinder

batches, representing two of the SRMs (separate SRM numbers are used for the

large and small cylinders in each of two batches), contains C0 2 and N

2 0 at

nominal concentrations of 340 ppm and 300 ppb, respectively; the second of

the two batches (representing two different SRMs), contains C0 2 and N

2 0 at

nominal concentrations 375 ppm and 334 ppb, respectively. The actual concentration of C02 is individually certified in each cylinder of these SRMs.

Information values also are provided for these SRMs for methane (1.7-1. 8 ppm)

and for halocarbons F — 1 1 and F-12 in the 300-500 parts-per-trill ion range.

Completion of these SRMs, encompassing a period in excess of two years,

involved the preparation of numerous gravimetric primary standards, extensive

analytical characterization, and intercomparative analyses of C02 in selected

samples by constant volume manometry (performed by C. D. Keeling and P. Guenther of the Scripps Institution of Oceanography of the University of

Cal ifornia-LaJolla)

.

The concentration of C0 2 in each of these SRMs is certified to a total

uncertainty not exceeding + /—0 . 1 % relative (0.3 ppm at 300 ppm) at 95 % confidence level. Primary standards of such mixtures have been found to be stable

over periods in excess of 3.5 years. The concentrations of C02 in the SRMs

are certified to be stable within their uncertainty for a period of two years

from date of purchase from NBS. A quality assurance program operated by the

Gas Metrology Group involves the routine reanalysis of samples of all gas

SRMs that have been certified to verify that their certified concentrations

have remained unchanged.

This work, supported by the U.S. Department of Energy's Carbon Dioxide

Research Office, completes the transfer of responsibil ity for C02 in air

standards from the Scripps Institution of Oceanography to NBS. With the

addition of the four new SRMs, NBS now offers seven SRMs of C0 2 in air, in

the 300-400 ppm concentration range. Research is currently underway to com- plete two additional SRMs of C02 in air at a nominal concentration of 300

ppm, as well as two new SRMs at 200 and 1000 ppm.

6. Indoor Air Measurements for Sulfur Dioxide, Nitrogen Oxides, and Ozone

in the National Library of Medicine

Richard C. Myers

Several locations of the indoor air environment at the National Library

of Medicine were evaluated for pollutant gases, specifically sulfur dioxid* , nitrogen oxides, and ozone. The measurements of these gases w f re :iv;

between April 8 and April 15, 1 985. Continuous monitoring analyzer:. •

1 49
used to collect data to determine the concentrations of these substances

entering the building from the outside atmosphere via the ventilation

system

.

The locations at which these species were monitored, were a stack area

used for the storage of reading material and a corner of the main reading

area. The air exiting the ventilation system was sampled for a period of

approximately 48 hours at each site. The air inside an unventilated room

containing 5 photocopy machines also was sampled for ozone. Measurements of ozone made in the photocopy room were intended only to quantify any ozone

produced by the photocopiers.

Ambient sulfur dioxide levels were measured with a pulsed fluorescent

sulfur dioxide analyzer. Nitrogen oxides, as N0X (NO + N02

)» were measured

with a chemiluminescence analyzer. A microcoulomb ozone sensing instrument

was used for measuring ozone levels.

Calibrations of the sulfur dioxide and nitrogen oxides analyzers were performed on a daily basis using sulfur dioxide and nitrogen dioxide permeation devices, previously calibrated at NBS. A flow of diluent air passed

over each tube was measured with a calibrated mass flow meter. The sensitivity of the ozone instrument was determined at NBS using an ultraviolet

adsorption analyzer and a standard reference photometer.

A conclusion which could be drawn from the measurements made, is that,

the interior atmosphere of the library will reflect almost without change the

external atmosphere. Increases in nitrogen oxide levels usually occurred

twice daily which could be correlated with nearby traffic patterns. Increases

in sulfur dioxide levels were observed when the wind direction was such that

it passed in line of a nearby powerplant before reaching the library. Ozone

also was detected in the air sampled from the ventilation vents. It was found that a significant amount of ozone was being generated and accumulated

within the photocopy room at times when the photocopy machines were in

frequent use.

7. Development of NBS Traceable Standards for Measurements of U.S. Natural

Gas Quality

G. C. Rhoderick

The natural gas industry has for years been assigning heating values

using calorimetric measurements. There have been discrepancies over what

the heating value of a specific natural gas sample is when measured by different companies and laboratories. Since natural gas is sold on the basis of

BTU/cubic foot, small but significant errors could equate to large amounts of

money for both the supplier and the user. A project, funded by the Institute

of Gas Technology (IGT), was undertaken by the NBS to certify, as reference

standards, several binary mixtures and a simulated natural gas mixture. The

samples were to be analyzed using gas chromatography and cross checked

against primary gravimetric standards prepared by NBS. The concentrations of

each component in these mixtures were determined and certified. The heating

value for the mixtures were calculated from the heating value and concentration of each constituent hydrocarbon, and then summing all the heating values

of each hydrocarbon in the mixture:
% concentration

Heating value C = [heating value C x — ] (where C is hydrocarbon)

Heating value mixture = [BTU + C2 + **• + Cn

]

Gas chromatography has been used as a means of determining the

concentration of each component found in natural gas and thus for determining

the heating value based on composition. This has been found to be a much

more accurate method for determining heating value.

Four mixtures were sent to NBS by IGT for certification. The first

sample was pure methane and it was analyzed for any impurities. The methane

was then determined by difference with low uncertainty since the impurities

found were at low levels. This pure sample was found to have concentration of

99.987 ± 0.007$ (.007$ relative uncertainty at the 95$ confidence interval).

The second sample contained nitrogen in methane. Insignificant amounts of

impurities were found, hence the concentrations determined by a ratio of the

responses of nitrogen and methane resulted in very low uncertainty levels:

18.49 ± 0.04$ (.2$ relative uncertainty) nitrogen and 81.51 ± 0.06$ (.07$

relative uncertainty) methane.

The third sample consisted of ethane in methane and it also had

insignificant impurities present, hence the ratio method, used for the sample

above, was applied. The concentration and uncertainty for these samples were determined to be: 25.03 ± 0.04$ (.2$ relative uncertainty) ethane and 74.97 ± 0.06$ (.08$ relative uncertainty) methane.

The fourth sample was a simulated natural gas sample. The minor

components were analyzed, concentrations determined, and uncertainties were

calculated which ranged from .26 to 3.8$ relative. The methane was determined by gas chromatography and by difference, with no significant difference

found between the two values. The uncertainty of the methane was determined

by summing the minor component uncertainties, as a ± percent. Hence, the

methane had a value of 90.64 ± .06$ (.06$ relative uncertainty at the 95$

confidence level). Thus, the main component of the natural gas had a low

uncertainty in its heating value which was the objective of the gas industry.

8. Development of Tritiated Methane Standards for Atmospheric Monitoring

E. Hughes and R. Miller

The object of this project was to produce a set of tritiated methane

standards (CTH^) for use in quality control between several laboratories

engaged in the measurement of CTH^ in the atmosphere. All standards were to

be made from a single batch of gas to insure that they would be as nearly

identical in concentration of CTHo as possible. The quantity of gas in each

standard was to be no less then 5 liters and the number of standards was to

be at least 6. The activity of CTH^ in the methane (CH^), which formed the

bulk of the mixture, was to be about 0.5 disintegrations/minute/cubic

centimeter (dpm/cm->) with a total uncertainty of less than 5$ relative.

Accordingly, it was decided to prepare the standards gravimetrically by

stepwise dilution of a high concentration of CTH^ to the desired level using

analysis of the CTH^ at each dilution level as a confirmation of the accuracy

151
of the dilution. The concentration of the final mixture therefore would be

based on two independent .numbers, the predicted value based on the measured

weights of each component and the measured value obtained at each step in the

process. In addition, agreement between the predicted value based on dilution and the measured value would confirm the validity of the dilution

process and the absence of selective adsorption of CTH^ within the container.

The samples were prepared, gravimetrically , by stepwise dilution of a sample containing a high concentration of CTH^ in CH^, to an intermediate

concentration, then finally to a concentration around 0.5 dpm/cm . The

diluent gas was methane containing no detectable concentrations of CTH^. The

gravimetric procedure involved adding the known mass of the minor component

(CTHo) to a pre-weighed, evacuated cylinder, and then adding a known mass of

the diluent (CH^).

All samples, after being oxidized to water, were analyzed by the

Radioactivity Group (532) at NBS using liquid scintillation counting. The

CHjj used as the diluent gas was analyzed for tritium content by scintillation

counting and for impurities using mass spectrometry and gas chromatography.

Samples for counting were prepared by oxidizing the CTH^/CHjj mixture

over hot (700 °C) copper oxide. The resultant water was collected by condensation in a glass ampoule which was then sealed and delivered to the Radioactivity Group for analysis. At least two samples from each cylinder were prepared and analyzed for tritium content. Periodically, between oxidation

of active samples, the diluent CH^ was passed through the combustion system

in order to detect residual contamination

.

Ten samples were prepared. The mean CTH-

,3 r ... concentration of all samples

was 0.550 dpm/cm^ CH^ ± 0.022 dpm/cm^. Agreement between the gravimetrically

calculated value of the final dilution and the analyzed value was 0.5^ . Six of the samples have been shipped to various laboratories involved in the

atmospheric monitoring for CTH^.

9. Characterization of Stable NBS Traceable Standards of S02 in Air at 100

ppb for Dry Acid Deposition Studies

W. Dorko, Z.-T. Cai , and F. Abbo

Currently, the NBS has a number of sulfur dioxide-in-nitrogen gaseous

SRMs in cylinders ranging in concentration from 50 ppm to 3500 ppm. Also

available from NBS are SO2 permeation tube SRMs which can be incorporated

into a gas dilution system to produce calibration gases. Permeation tubes

are generally used to produce mixtures with concentrations ranging from 0.1

ppm to 5 ppm S02

. By using the cylinder mixtures directly or by diluting them

with reasonable flow ratios, concentrations from 0.5 ppm to 3500 ppm can be

generated. Neither the cylinder mixtures nor the permeation tubes can be used

conveniently to achieve accurate calibration mixtures at 1 ppb. For meaningful dry acid deposition studies, the USEPA requires accurate measurements

approaching this level. To satisfy this need, cylinder mixtures of S02 in air

at 100 ppb are being studied; if these could be well characterized and remain

stable, they could be used in a dilution system with reasonable flow ratios

to produce S02 calibration mixtures as low as 1 ppb.

152
Mixtures of 100 ppb SO2 were obtained from two different commercial

suppliers; each claimed to be able to provide stable mixtures. A pulsed

fluorescence S02 analyzer is being used to intercompare the cylinders with

the output of a permeation tube dilution system. To provide the most accurate calibration mixtures using the permeation tube dilution system, the

three main features of the system (temperature of the chamber, permeation

•’ate, and flow over tube) have to be monitored or evaluated. For this purpose, the temperature of the constant temperature chamber is monitored and

the S02 permeation tube is periodically weighed. The flow rates are con- trolled by mass flow controllers, and these have been evaluated for both

input pressure and ambient temperature dependence. Both effects have to be

monitored to characterize system performance. To check the dilution system,

an experiment was performed in which the permeation tube system was adjusted

to produce 1 ppm S02

. A 50 ppm SRM mixture of S02

, analyzed by the standard

peroxide method, was incorporated into the dilution system and the flows were adjusted to achieve 1 ppm (i.e., a 50 to 1 dilution). The pulsed fluorescence detector was used to compare the diluted sample obtained from the

cylinder with the permeation tube system. The signal observed was within

0.2? of the predicted signal. This finding indicated that the controllers

were well characterized.

The controllers were subsequently used in conjunction with the

permeation tube dilution system to generate S02 calibration mixtures from 90

to 120 ppb to periodically analyze the nominal 100 ppb S02 cylinders. After

three months, there has been no sign of decay. The work will continue to assure stability over a longer period.

10. Intercomparison of Tunable Diode Laser, Chemiluminescent Detector, and

Fourier Transform IR Measurements of High Concentration NOg /Air SRMs

A. Fried, W. Dorko, R. Sams, and J. Elkins

The important reactive gas N02 is a key molecule in atmospheric studies.

It is well known that this gas plays an important role in the occurrence of

"acid rain" and the generation of photochemical smog. Concentrations of

several hundred parts-per-mill ion by mole (ppm) of N02 and NO are continuously produced by the combustion of fossil fuels from various stationary and

mobile sources. To meet the ensuing need for accurate standards by which

field instruments are calibrated, NBS has recently issued a new series of

compressed gas N0g/air standards at nominal concentrations ranging from 250

ppm to 2500 ppm. These mixtures, in addition, may also serve as convenient

source of high concentration N02 for atmospheric-related studies carried out

in the laboratory and the field.

Commercial chemiluminescent detectors (CD) have traditionally been

employed for measuring both NO and N02 gas mixtures. Detection is accom- plished via the chemiluminescent reaction between NO and 0^. In the case of

N02

, the gas sample must first pass through a converter to effect the conversion of N02 to NO. Such measurements of N02 are accurate as long no other

nitrogen oxide species are present. However, the chemistry of high pressure

cylinders is not well understood, and the possibility exists of converting

other nitrogen oxide species to N02 and subsequently to NO. While the mea- surement of total nitrogen oxide (N

x0y) may be correct under such conditions,

the N02 concentration would certainly be in error.

153
Because of this potential source of systematic error and the rather

widespread use of CDs for measuring N02

, we have undertaken in the present

study a detailed intercomparison between the extremely sensitive and selective technique of tunable diode laser absorption spectrometry (TDLAS) and CD

for a selected group of high concentration N02 /air cylinders. An intercomparison was also carried out on one particular cylinder using the above two

techniques along with FTIR.

Quantitative diode laser measurements were performed on both NO, eluting

from the converter, and N02 using direct absorption and second harmonic

detection. In all N02 cylinders examined, the CD consistently resulted in

"N02

" values 5 to 1 5% higher than TDALS. Subsequent TDL and FTIR absorption

studies revealed the presence of HNO^ in each and every cylinder examined.

After accounting for HNCU, as quantitatively measured by all three techniques, the N02 determinations by each technique were generally found to be

in good agreement within the measurement uncertainties. Future efforts will

focus on determining the source of such high HNO^ concentrations as well as assessing its stability as a function of various cylinder parameters.

1 1 . Identification and Characterization of Systematic Error Sources in

Tunable Diode Laser Absorption Measurements

A. Fried and R. Sams

In last year’s panel report, we described on-going efforts to improve

the accuracy of tunable diode laser (TDL) direct absorption measurements. The

studies presented here are a continuation of this important long-term

program.

Diode laser measurements can be made in both an absolute and a relative

mode. In the former, as in any direct absorption technique, the concentration of a species of interest is related to the incident and transmitted

intensities using the Beers-Lambert Law. Accurate concentration determinations employing direct absorption require not only highly accurate measurements of these parameters, but also accurate pathlength data and absorption

and pressure-broadening coefficients as well. Unfortunately, TDL direct

absorption measurements are susceptible to many different types of systematic

errors. Such error sources reported in the literature include: a nonuniform

laser scanning rate, an appreciable laser linewidth relative to the absorption features under study, and the presence of multi-mode lasing. Systematic

errors associated with this last source can be further manifested in a variety of different ways. In the present study, we have identified and characterized two such error sources which have not been discussed in the

literature previously.

When multi-mode lasing occurs, as is often the case in TDL studies, the

true photometric 100% absorption level (the opaque limit) cannot simply be

obtained by placing a shutter in the beam path. Instead, one must establish

this level for each absorption line under study by increasing the pressure of

the target gas of interest until the line center absorption becomes saturated, as evidenced by a flattened peak. Other lasing modes are generally

not absorbed. However, in the case of polyatomic molecules like N02 where

there is a high density of lines, additional lasing modes on occasion may be

absorbed by these lines simultaneously with the line under study. As we have

found in the present work, this causes a structured-opaque limit which can

15*1
affect the proper determination of the true 100$ absorption level.

Concentration determinations affected by this type of error were found to be

systematically low by as much as 10$. However, even larger systematic errors

can readily result from this cause. In addition, each lasing mode can be

emitted in a preferred direction. Since most diode laser spectrometers

utilize more than one beam, there is a strong possibility that systematic

errors in frequency and/or concentration may result due to a different

fraction of each spatial mode in each arm.

This past year, we have made significant progress in identifying,

characterizing , and devising procedures to eliminate these as well as other

systematic error sources. Employing a high resolution interferometer is very

important in this regard.

12. The Investigation of Simulated Test Data (STD) for Basic Research and

Accuracy Evaluation in Chemometrics

L. A. Currie

The development of methods for the analysis of complex materials and

systems, and the realistic evaluation of analytical uncertainties — especially for multicomponent systems — is one of the more important challenges

for current chemical and chemometric research. For the overall Chemical Measurement Process (CMP), Standard Reference Materials (SRMs) are recognized as vital for meeting these dual needs of method development and validation. In

recent years, however, there has been a growing awareness that the data evaluation step of the CMP also is in need of validation and research direction.

Common test data sets (STD) which are realistic and well-characterized have

provided important insight, through interlaboratory comparisons, concerning

the quality and research needs of the Analytical Data Evaluation process.

Real data analyzed by different groups, can indicate discrepancies (W. H.

Kirchhoff, Ed., NBSIR 82-2511, 1982), but data of known chemical-model and error structure are mandatory if one is to assess accuracy. The first major

STD exercise was organized by the International Atomic Energy Agency (IAEA)

for laboratories engaged in instrumental neutron activation analysis (R. M.

Parr, et al . , Computers in Activation Analysis and Gamma-Ray Spectroscopy,

DOE CONF -780421 , 1 979), the second, organized by NBS and EPA, was for those

engaged in aerosol source apportionment via multivariate chemical pattern

recognition (L. A. Currie, et al . , Atm. Environ. J_8 , 1984, 1517).

Research undertaken during FY85 grew out of the multicomponent

analytical 'chemometric 1 (experimental design, data evaluation) needs as demonstrated by the foregoing STD laboratory intercomparisons. Specific

research needs and directions were indicated by the following facts (STD

intercomparison outcomes): (a) a significant portion of the results from

both exercises exhibited large deviations from the "truth" as well as large

interlaboratory differences, even though such labs evaluated exactly the same

data, often reportedly using the same data evaluation techniques, b) uncertainty estimates were often missing, and when given were mostly too small or too large in comparison with the observed dispersion and/or deviations from

the truth, and (c) component detection limits and systematic error bounds

were totally absent. The importance of these matters is such that, following

the initial exercises, the IAEA has continued to supply the gamma-ray STD

together with their Certified Reference Materials as a regular part of their

155
Analytical Quality Control Service program; and our Group at NBS has

continued to meet requests of laboratories in the U.S. and Europe for

magnetic tapes containing the source apportionment STD.

New research in chemometrics has been stimulated and aided by the STD in

several institutions. The two-fold thrust of our work at NBS has been to:

(a) develop methods to investigate the quality of alternative multivariate

data evaluation techniques, plus causes of the discrepancies among STD

results, and (b) develop chemometric techniques which take into account

external ('expert') scientific knowledge or constraints, and robust techniques which can give reliable estimates for analyte concentrations, given

the intrinsic need for assumptions to solve most multicomponent analytical

problems. Among our results:

o An STD adaptation of the "Youden" concordance diagram has been

developed to expose laboratories applying different types of "scientific judgment" (implicit algorithm or assumption differences) while

using the same basic data evaluation technique (e.g., multiple linear

regression) [L. A. Currie, First NBS Chemometrics Research Conf., May

1 985].

o A compilation of guidelines and cautions for STD synthesis and

intercomparison organization; plus a summary of outstanding chemometric multicomponent research questions evolving from the STD exer- cises [L. A. Currie, idem].

o A more realistic approach to the estimation of analyte (or component)

uncertainty in connection with the use of non-negativity constraints

and systematic error arising from multiple applications of pure com- ponent patterns of spectra containing measurement error [D.

Lowenthal , K. Rahn, and L. A. Currie, internal report, August 1985].

Many important activities related to STD intercomparison and the

resultant chemometric research needs will continue in the coming years. We

expect to gain further information on the value of STD, as a complement to

SRMs in other areas of multicomponent chemical analysis. In addition, we plan to perform research on such outstanding questions as: a) the influence

(and optimization) of the experimental design — i.e., sampling and measurement strategies — on multicomponent resolution; b) the computation of realistic bounds for systematic (model) error, detection limits, and imprecision

for multivariate, multicomponent experiments; c) the systematic incorporation

of physicochemical constraints and "scientific intuition" into the design and

evaluation process.

1 3. Improved Measurements of Environmental Radiocarbon via Chemical and

Isotopic Separation Coupled to Accelerator Mass Spectrometry

R. M. Verkouteren and L. A. Currie

The utility of carbon isotope ratio measurements for the purposes of

carbon cycle geochemistry, environmental pollutant tracing, and radiocarbon

dating is dependent upon radiocarbon measurement processes able to differentiate indigenous sample levels of cosmogenic 4 C from background levels and
contamination. For uncontaminated samples containing at least one milligram

of total carbon of moderate to modern age (< 30 ka), accelerator mass spectrometry (AMS) has proven to give accurate measurements of carbon isotope

ratios with good precision. Beyond these bounds, however, analytical difficulties from ubiquitous carbon contamination and operator dependences have

limited the utility of AMS as a dating tool for measuring very old or very

small (< 10 ug/C) samples. A major objective of our work, therefore, is to

develop ultra-clean microchemical techniques which will allow AMS

measurements to reach their intrinsic potential.

Our research focuses on the characterization and optimization of a carbon isotope measurement process which is relatively simple and con- trollable, involving sample combustion, carbon dioxide separation, purification, and reduction to a target suitable for AMS isotope measurement. An

ultra-clean gas manifold equipped with a turbo molecular pump, furnace control systems, and high resolution capacitance manometers has been designed

and constructed in order to control and evaluate sources of analytical

inaccuracy and imprecision. Ongoing studies include assessing the importance

of reagent quality and pretreatment, characterization of chemical/isotopic

fractionation during the chemical and physical steps, and qualitative mea- surements of contamination carbon dioxide perfusion across quartz at

annealing temperatures.

Application of a radiocarbon enhancement technique (e.g., thermal

diffusion, electromagnetic enrichment-deposition, laser fractionation) to the

measurement process can enable measurement of carbon isotope ratios very much

lower than those attainable by conventional AMS, hence leading to an improvement in the radiocarbon dating range (L. A. Currie, G. A. Klouda, D. Elmore,

and H. E. Gove, Nucl. Instrum. Meth . , 1985, in press). To this end, a microthermal diffusion column has been designed and is under construction which,

when integrated with the ultra-clean sample preparation system, should allow

measurement of "ultimate" carbon isotope ratios; i.e., those hitherto unmeasured 4 C abundances arising solely from the environmental neutron flux in

the terrestrial subsurface. Initial estimates of such underground nuclear

reactions imply a natural limit to radiocarbon dating of - 100 ka . Our

chemical-isotopic enhancement studies thus are directed toward extending the

dating range toward this limit, as well as determining its magnitude experimentally. An important and interesting by-product of this research will be

the ability to study the rare terrestrial nuclear reactions, per se , possibly

also gaining thereby knowledge of "paleo" neutron fluxes in geological and

glaciological contexts.

14. Carbon Isotope Measurements for Source Apportionment of Pollutant

Aerosols and Gases

G. A. Klouda, W. Ollison, A. E. Sheffield, and L. A. Currie

Carbon isotope measurements of carbonaceous aerosols and gases serve as important inputs to Receptor Models for source apportionment. In particular,

u measurements unequivocally discriminate fossil fuel carbon from biogenic

(living) carbon emission sources. Radiocarbon results of specific subfractions of aerosols, e.g., the polycyclic aromatic hydrocarbon fractions

(PAH) extracted from Urban Dust SRMs 1648 and 16M9, have shown that 1 C mea- surements when coupled with chemical selectivity can significantly improvthe model resolution. Accelerator Mass Spectrometry (AMS) u measurement.: ,

157
with a sensitivity at less than 100 pg size samples (1984 Annual CAC Report),

now makes possible investigations into sources of specific fractions and

individual trace compounds.

This years’ progress in "carbon isotope chemistry" has focused on specific carbon species that have effects on visibility, human health or climate. Because the concentration of CO exceeds the National Ambient Air

Quality Standard (NAAQS) 9 ppm (8 hr) in some urban environments and because

of the importance of CO and CH^ in relation to the "Greenhouse Effect", a method was developed for extraction of CO and CH^ fractions from 0.1 m^ air

samples (cf. C. M. Stevens and L. Krout , Int. J. Mass Spectr. Ion Phys. 8,

265, 1972) for AMS ' X measurements. Radiocarbon measurements of these

species provide direct apportionments for fossil and biogenic combustion

sources. In addition, work is underway to develop and validate field

sampling and laboratory extraction methods for collection of Reactive

Volatile Organic Carbon (RVOC). RVOC is the controlled precursor used to assure attainment of the photochemical oxidant (0^) NAAQS.

In order to gain information concerning the impact of residential wood

combustion on the significant winter-time excesses of CO (> 9 ppm) in Las

Vegas, Nevada, we extracted CO (and CH^ ) fractions for 1 X assay from 0.1 m^

air samples collected in January 1984, by the Clark County Health District,

Air Pollution Control Division. Preliminary ^ X results for CO and CHjj fractions from two of the six samples suggest that vehicle emissions are primary

sources of CO and contribute to excess CH^ (above the natural background).

Also, the ambient CO and CH^ levels in these samples show a good correlation,

additional evidence f or a common source. Radiocarbon results for the remaining samples will indicate whether wood burning emissions contribute

significantly to ambient concentrations on other days.

The preliminary sampling method for RVOC employs a pumped, four-bed,

heated sampling train that separates the predominant ambient carbon species

(CO2

, CHjj, and particulate carbon) from RVOC, oxidizes the RVOC and subsequently traps the resulting CO2 on a LiOH bed for 1 X assay. Tests of trapping efficiency and background contamination are underway. A continuous 7 day

sampling period (10-20 of ambient air) is anticipated to yield 5-10 mg

C/ppm RVOC. Preliminary testing of field samplers is planned during the 1985

smog season in Washington, DC. Knowledge of the X content of RVOC at urban

sites will determine whether uncontrolled vegetative emissions constitute a significant emission source.

Research, which will continue into FY86, has been initiated in

cooperation with the EPA (Integrated Air Cancer Program) and with Sandia

National Laboratories on the application of ^ X measurements for source apportionment of organic particulate carbon and CO, respectively - in connection with elevated levels during the "wood burning season" in Albuquerque.

In connection with these and other studies, our future work on aerosol source apportionment will include the evaluation of thermal and/or chemical means

for separation and isolation of elemental carbon (EC), volatile organic carbon (VOC), and organic sub-fractions, e.g., the PAH fraction, for carbon

isotope measurements.
1 5. Quantitative Compositional Mapping with the Electron Microprobe Using

Wavelength and Energy Dispersive Techniques

R. Marinenko, R. Myklebust, D. Bright, and D. NewburyDigital compositional mapping with the electron microprobe is replacing

conventional x-ray area scans. The added flexibility during data acquisition

and the reliability of the final result make digital procedures preferable to

photographic records. True counts recorded from each point are preserved on

disk or tape and made available for subsequent manipulation by quantitative

image processing algorithms.

Mapping can be carried out with either energy-dispersive (EDS) or wavelength-dispersive (WDS) spectrometers . Mapping by EDS poses few technical problems and data for many elements, eight or more, can usually be

acquired simultaneously. There are many applications for which mapping with

WDS is desirable in spite of the fact that only a few elements can be

observed simultaneously. The higher count rates permitted in WDS analysis

make this technique preferable when observing low-concentration element distributions. There has been little application of WDS quantitative mapping

probably because of defocusing problems, which cause a large decrease in

spectrometer efficiency when the beam is scanned off-axis.

We have developed a program to control our automated commercial electron

probe to acquire either WDS or EDS maps with dimensions of 32 x 32, 64 x 64, or 128 x 128 pixels. This program moves the electron beam, point by point in

a raster, over the specified sample area, accumulating raw x-ray counts for

each element. Data is collected on a floppy disk and transferred to a large

computer where data reduction and display manipulations are done.

In order to quantitatively correct spectrometer defocusing which becomes

serious at magnifications below 8000X, a "standard map" procedure was developed. A map of each standard taken under the same conditions as the unknown

material is needed to determine appropriate unknown-to-standard intensity.

After background and dead-time corrections, each point in the unknown map is

ratioed to the corresponding point in the standard map. A data reduction

procedure (FRAME) developed in our laboratory, is used to calculate the con- centration of each point from the k-ratios. In order to test the procedure,

maps were prepared on homogeneous NBS SRM specimens. The resulting maps had

accuracy and precision equivalent to individual spot analyses.

The problem of quantitative presentation to an observer of the

compositional data in an image has been studied. Various color scales for

representation of data have been examined. The "black body curve" or "thermal scale", which is based upon the sequence of colors emitted by a body upon

heating, has been found to give a representation which can be interpreted

intuitively

.

159
1 6. Development of New Techniques for Light Element and Trace Element

Compositional Mapping

D. E. Newbury

Compositional mapping by microbeam analysis techniques can provide

direct evidence of elemental distributions on a micrometer scale in solids.

Such information is frequently useful in determining the relationship between

the microstructure and the macroscopic properties and behavior of the solid.

Most compositional mapping is currently carried out with the electron probe

microanalyzer (EPMA), which is limited by the nature of the characteristic

x-rays to detecting elements with atomic number greater than 5. Moreover,

the detection limits in a mapping mode are typically greater than 1-5$

depending on the element of interest.

Imaging by the form of secondary ion mass spectrometry (SIMS) known as ion microscopy offers several special capabilities which do not suffer from

the limitations of the conventional elemental mapping techniques. These

special capabilities include isotopic, light element, and trace element

imaging. In this work, compositional mapping by ion microscopy has been

employed to attack two materials science problems: (1) the distribution of

lithium in Al-Li alloys and (2) the origin of differences in the secondary

electron coefficient observed in reaction-bonded silicon carbide (SiC). In

studying these systems, digital imaging techniques have been used to combine

information from several imaging methods, including ion microscopy, scanning

electron microscopy, and optical microscopy. The combination of compositional mapping from SIMS imaging with structural information from the other

forms of microscopy has proven invaluable in interpreting the structures of

these materials.

In the Al-Li alloys, structures observed by optical microscopy on the

surface of specimens after polishing have been found to be completely unre- presentative of the true lithium distribution in the bulk material, which can

be revealed by ion etching. These surface structures appear to result from

surface segregation due to preferential leaching of lithium during the

polishing process. The ability to separately image the surface and interior

of a sample can be used to study the leaching process, the understanding of

which is critical to employing the alloy in service. The general distribution of lithium-rich precipitates has been observed in bulk material after

heat treatment. Lithium segregates to grain boundaries and denuded zones develop adjacent to the boundaries. Such segregation may affect the mechanical properties of the alloy. Direct imaging is a useful adjunct to bulk

analysis to characterizing the behavior of the alloy as a function of

composition.

When viewed in the SEM, the reaction-bonded silicon carbide displays

anomalous secondary electron contrast within the partially melted and regrown

SiC grains. This unusual effect arises despite the lack of apparent compositional differences between the regions which show the strong contrast, as measured with the EPMA. Examination of the trace constituents by SIMS

reveals the presence of aluminum at an approximate level of 100 ppm. SIMS

images of the trace aluminum distribution show a significant degree of corre- lation with the secondary electron emission pattern seen in the SEM images.

The presence of the aluminum in the semiconductor SiC may alter its band

structure, leading to the differences in secondary electron emission.

160
i 7. Determination of the Half-Life of by Laser Microprobe Mass

Spectrometry for Geochemical Dating

D. Simons, M. Lindner (LLNL), and D. Leich (LLNL)

The long-lived naturally-occurring nuclide 'Re is important to

geochemists and to cosmochemists as a nucleochronometer that could be used to

determine independent terrestrial, solar-system and cosmic chronologies. For

such measurements, the half-life of iy^Re is a necessary parameter. Recent

literature points to a probable value around 45 billion years on measurements

normalized to accepted ages of meteorites and rocks.

We have conducted an experiment to make a direct determination of the

half-life of °'Re by observing the ingrowth with time of the decay product

18 ^0s relative to 1 TM0s and 1 ^2 0s spikes added to a purified solution con- taining 1 kg of rhenium. For this experiment we have developed a technique

to obtain isotopic analyses of nanogram quantities of osmium with relative

precision and accuracy of 2-3 % (1 o) on isotope ratios between 0.3 and 3.0

using the Leybold-Heraeus LAMMA 500 laser microprobe mass analyzer. We typically accumulate about 100 separate mass spectra from an individual sample

that contains less than 1 ng of osmium, perform channel-by-channel summations

of all spectra, and measure ratios of the resultant summed peak areas. This

allows us to achieve good ion statistics while minimizing detector nonlinearity effects and averaging out any electronic noise in the recorded spectrum.

Problems with isobaric interferences in the osmium mass range due to K^Clp , Cu^ , and W have been solved by using gold (instead of copper) electron

microscope grids with SiO films vacuum-evaporated from tantalum (instead of

tungsten) boats, and by using ultrapure (low-potassium) HC1 as the solvent

from which the samples are deposited by evaporation onto the filmed grids.

Four aliquots of the original rhenium solution have been extracted over

a time period of three vears since the addition of the osmium isotopic

spikes. The half-life of ~°'Re can be calculated from the slope of the bestfit line that correlates the ^°^0s to 0s spike ratio with the growth time.

The half-life determined in this way is 43.6 billion years, with an asso- ciated uncertainty of 3% (la). The osmium isotopic ratios of the individual

samples have been independently measured by inductively coupled plasma mass

spectrometry (ICPMS), and the agreement with LAMMA-determined ratios is

within 1 % in almost every case. Four additional kilograms of rhenium, for

which results are not yet available, will provide independent determinations

of the half-life.

1 8. Unique Molecular Characterization of Complex Minerals by Micro-Raman

Spectrosc opy

E. S. Etz

Modern analytical methods employing microprobe instrumentation are increasingly being applied to the task of comprehensive mineral characterization. Among these are the electron beam methods, ion beam techniques and,

more recently, optical microprobe methods such as microspectrofluorimetry

,

micro-Raman, and infrared microspectrophotometry. Microprobe methodlogies

become especially important in studies of new mineral or complex miner il phases where the specimen may indeed be of microscopic size only, and when- ever it is necessary to obtain spatially resolved analytical information. In

161
combination, these various methods provide information on homogeneity,

stoichiometric relationships, the chemical formula of the mineral, its crystal system and various other classifying parameters. Despite this array of

analytical techniques, a full description of an unknown or complex mineral is

often hampered by difficulties in the quantitative analysis of light elements

by electron and ion beam techniques.

Recognizing the limitations of electron and ion beam techniques in the

chemical analysis of minerals which contain light elements, we are applying

Raman microprobe spectroscopy to the kinds of problems where the vibrational

Raman spectrum can furnish the desired molecular and bonding information.

This approach of comprehensive, synergistic microanalysis is presently being

pursued in two research areas of complex mineral characterization. In collaboration with workers at the Smithsonian Institution, Washington, DC, and at

the National Musuem of Natural Sciences, Ottawa, Canada, we are elucidating

the compositions and structures of a series of new minerals containing borate

and carbonate species. The micro-Raman spectra furnish information on the

types of molecular units (e.g., CO^

2-

, BO^

-

, HBO^

2-

, B( OH ) i|

_

» SO^

2-

, POg , H

2 0) present in these structures and resolves questions pertaining to coor- dination and stoichiometry among the constituents of the sample. An example

is borate minerals containing either 3 - or 4- coordinated boron resulting in

trigonal or tetrahedral configuration. One case study furnished conclusive

spectral evidence that contributed to the identification of a new mineral —

named moydite — found in granitic pegmatite deposits at Evans-Lou mine in

Quebec province, Canada. The spectra support the presence of tetrahydroxo

borate groups and carbonate ions in what is deduced to be a compound yttrium

borate of chemical formula Y[B(OH) ^]COg in the orthorhombic crystal system.

A second area of mineral characterization with the Raman microprobe

addresses the detailed aspects of biological mineralization, involving the

study of mineralizing tissues (bones and teeth) and calcified tissues (aortic

plaques) with the aim to monitor mineral changes as a function of age and

maturation. This work is conducted in collaboration with researchers at the

American Dental Association and at several medical institutes involved in

mineralized tissue research. Of particular interest is the incorporation of

carbonate ions in the biological apatite (i.e., phosphate, POjj ) mineral

matrix, a process concurrently studied in the calcification of the connective

tissue of the human aortic wall leading to atheroscelerotic disease. This

work is extended to studies of the calcification of bioprosthetic circulatory

assist devices, such as heart pumps and aortic valves made of various natural

or synthetic materials, implanted in animals and man. The formation of calcified deposits upon implantation of such devices often serves as an indication of the biocompatibility of the materials used.

19. Development of Digital Imaging on the Analytical Electron Microscope

E. Steel, R. Myklebust, A. Bell, and B. Thorne

The analytical electron microscope (AEM) can provide a comprehensive

characterization of a sample, including morphology, crystal structure, and

major and minor elemental constituents, at a spatial resolution as small as

10 nm. Because of the potential for a high rate of information flow from

multiple signals available in the AEM and the frequent desire to reduce the

exposure of the sample to minimize radiation damage, we have undertaken a comprehensive program of automation to achieve efficient computer-aided

162
microscopy. Such a system will allow unattended operation to increase our capabilities for processing more samples. A first stage of such a development must necessarily involve computer control of the electron beam and

detectors for image formation.

A VAX 11/730 computer has been interfaced to a JEOL 200CX AEM for the

purpose of producing and manipulating digital images from the microscope, and

communicating in real time with a VAX 11/780. This combination of computers

allows fast acquisition and sophisticated manipulation of large image arrays.

The scanning coils (bright field and dark field) of the electron microscope

are controlled by the 11/730 and the output of the secondary electron, transmitted electron, and electron energy loss spectrometer (EELS) detectors on

the microscope are input to the computer. The x-ray emissions from the

specimen may be detected using two energy dispersive x-ray spectrometers

(EDS) (a zero degree take-off-angle ultra-thin window EDS, and a high-takeoff-angle, beryllium-window EDS) whose outputs are processed through a multiplexed multichannel analyzer (MCA) controlled by the 11/730. A network

and a direct memory access (DMA) channel link the VAX 11/730 to a VAX 11/780

equipped with an image processor. The network communicates between the two

computers at 19,200 baud, while the DMA communicates at a rate of greater

than 100,000 words per second. The 11/730 controls the image acquisition

process while the 11/780 handles all of the image processing and display.

The image analyzer has two independent stations, one at the AEM for viewing

images during live time experiments and another which is used for software

development or viewing of archived images. An array processor on the 11/780

will be used for accelerating computing times for complex algorithms.

The image acquisition software controls the microscope so that a scanning electron microscope (SEM) image, a scanning transmission electron

microscope (STEM) image, EDS x-ray or EELS image can be obtained concurrently

or sequentially. Image arrays up to 1024 by 1024 pixels at magnifications of

20X to 800.000X with each pixel having a signal resolution of 12 bits (4096

gray levels) can be acquired and manipulated. Typically, 512 by 512 pixels

by 8 bit images are collected for the electron images and, due to x-ray

signal limitations, selected area or 64 by 64 pixel by 8 bit images are collected for EDS x-ray images. The software for the system is written in a combination of Macro, Fortran, and LISP giving speed, flexibility, and com- puting power on a level currently unachievable by micro-computer based systems. Some early applications of the system included analyses of air particulates, thin film standards, asbestos, and several other mineral

particulates. Techniques which have been developed include the use of image

analysis for particle finding, image comparing, electron diffraction

analysis, magnification calibration and film thickness measurement.

20. The Development of a Particle Collector for Microanalysis of Fine

Particulate Matter

J. A. Small

Previous research in microbeam analysis has demonstrated the powerful

combination of analytical electron microscopy (AEM) and laser microprobe mass analysis (LAMMA) for comprehensive characterization of individual particles.

Morphology, crystal structure, major, minor, and trace elemental composition,

and isotopic composition can be determined by sequential application of AEM

and LAMMA techniques. In order to fully exploit these capabilities, r he

163
particles must be placed on an ultra-thin carbon film (ca 20 nm). Research

into particle collection methods has sought to develop methods to collect

particles directly onto thin films. In this way, the particles need not be

exposed to possibly damaging chemicals during dissolutions which must nor- mally be used to transfer particles from filter media to films. A particle

collector has been developed for direct collection on AEM/LAMMA film

substrates

.

The sampler consists of two separate collection devices, an electrostatic precipitator and a thermal precipitator. These two devices are designed to be connected in series but may be used independently if desired.

In addition, it is also possible to connect a back-up filter onto the collector. The sampler is made from lucite in the shape of a cylinder 6 cm in diameter by 20 cm long, weighs less than 1 kg and is usable for field

collections

.

In the electrostatic precipitator, the particles are charged with a negative 3~5 kV potential. The voltage is applied to a sharpened tungsten

needle which is used to create the charge field. Four collection surfaces

each holding one transmission electron microscope grid are arranged radially

1.2 cm downstream from the needle. The manifold is 1.9 mm in diameter at the

electrostatic preciptator and the four collection plates extend about 2 mm

into the manifold. An additional five samples are collected from the middle

of the air stream 2.4 cm downstream from the needle. All of the downstream

collection plates are held at ground potential. One plate which is located

directly opposite the needle is connected to a 600 V ac source. This plate,

which can also serve as a collection surface, is used to maintain the charge

zone. The flow rate through the electrostatic unit is 5-10 liters per

minute. The thermal precipitator can accommodate as many as ten grids and is

differentially pumped with respect to the electrostatic precipitator . The

collection plates are designed so that they can be cooled with water or other

recirculating liquids if necessary. The thermal precipitator is located

downstream about 5 cm behind the electrostatic unit. Flow rates through the

thermal unit are 0. 1-1.0 liters per minute.

Preliminary tests of the device with particle streams generated in the

laboratory indicate that it is effective in collecting particle size down to

0.02 micrometers in diameter, as verified by transmission electron microscopy. The device has been used to collect particles generated by spark

source emission spectrometer to study material transport during the "burn"

process and to study the particulate emissions as possible standards. In

addition, the device is currently being used by the Center for Fire Research

to collect smoke particles for microscopic analysis.

21 . The Determination of the Visibility of Chrysotile Asbestos Fibers

Imaged in the Scanning Electron Microscope

J. A. Small

The development of analytical methods for accurate characterization of

environmental samples which contain asbestos is an importance national problem which impacts on a variety of public health issues. Considerable debate

has occurred over the best microscopy methods to employ. In this work, the

scanning electron microscope has been compared to imaging with transmission

electron microscopy for characterization of asbestos.

164
Most manufacturers of conventional scanning electron microscopes (SEM's)

claim resolution on the order of 3—1 0 nm for their instruments, a value which

is substantially less than the diameters of 20-30 nm reported for singlefibril chrysotile. With this level of resolution, it appears that these

instruments should be able to image single fibrils of chrysotile asbestos

under normal operating conditions in a real-time imaging mode appropriate to

rapid sample searching. The limiting resolution performance of an SEM, however, can only be realized with an ideal high contrast sample such as a thin

edge or a strongly scattering particle viewed against a weakly scattering

background. In analyzing a material such as chrysotile asbestos with a low

electron scattering coefficient, the visibility of chyrsotile asbestos fibers

is limited by the contrast of the sample rather than the ultimate resolution

of the SEM used for the analysis.

The only practical method to unambiguously image all of the chrysotile

fibers in a sample is to use the transmission (TEM) or scanning transmission

electron microscope (STEM) which have sufficient contrast and resolution to

image even the smallest fibrils. We have studied the visibility of chrysotile asbestos in the SEM by making use of the superior imaging of the

TEM/STEM to record the size and locations of thin asbestos fibers in a test

sample. Once the thin fibers have been located and photographed, these same

fibers and fibrils were photographed with either the TEM/STEM, operating as

an SEM, or the conventional SEM. By increasing the thickness of the substrate

and/or decreasing the accelerating voltage of the beam, it was possible to

illustrate the difference in visibility for chrysotile fibers between a TEM/STEM analysis procedure at 100-200 keV with a thin substrate, and a conventional SEM analysis procedure at 25-^0 keV^with at thick substrate.

The results of this comparison show that the visibility in the SEM of

very thin chrysotile fibers, less than 0.2 micrometers in diameter, is

severely limited because of weak contrast when the fibers are prepared on a conventional bulk substrate. In addition, the results demonstrate that the

visibility of thin fibers in the SEM is improved when the fibers are prepared

on a thin-film substrate of low atomic number such as carbon and analyzed at

a beam energy of 30 keV or greater. These results suggest that if an SEM is

to be used for asbestos characterization, careful attention must be paid to

the specimen preparation method which is employed. Moreover, since the fiber

size range of interest extends to the limit of visibility in the SEM, the

results are likely to show substantial variability.

22. Magnification Calibration of the Scanning Transmission Electron

Microscope by Hough-Transformed Images of Grating Replicas

D. S. Bright and E. B. Steel

Accurate knowledge of the magnification of a mircoscope is a vital

parameter in any characterization procedure in which the physical dimensions

of the object are important. A traditional method of calibrating the magnification of a scanning transmission electron microscope (STEM) is to measure

the spacings of an optical diffraction grating replica. Typically the spacings are measured along an intensity profile taken perpendicular to the lines

of the grating. A small number of linear intensity profiles do not take into

account the local nonlinearities or bumps of the grating replica: many mea- surements are required. Our method uses an algorithm that averages the

grating spacings over the whole image rather than over a limited number of

165
linear traces across the image. The reproducibility of this algorithm is on the order of a tenth of a pixel for a given image, which is better than that

needed for our applications.

A JOEL 200CX analytical electron microscope was used in STEM mode, with

digital image acquisition controlled by a PDP 11/23 computer. The PDP 11/23 was linked to a VAX 11/780 equipped with a DeAnza IP8400 image processor

with 512 by 512 pixel resolution. The VAX was used for image analysis and

the image processor was used for viewing. The first step in analysis of the

grating images was to take the gradient of the images. The gradient operation emphasizes short range changes in intensity and enhances the lines of our shadowed gratings. The lines were adequately represented by the brightest five percent of the pixels in the gradient image. These pixels formed

lines that were slightly spotty and wavy, hence the need for averaging all

available data. The second step was to apply the Hough transform to our images. This had the effect of mapping each of the grating lines into a bright spot. The spots were then located automatically. Since the grating

lines were parallel and evenly spaced, the algorithm searched for three or more spots that were evenly spaced. Each spot position was determined by an intensity weighted average of all of the pixels in the spot. The line

spacing was then calculated by averaging the spacing of all of the spots.

The standard error of the magnification measurement was less than three

percent in all cases over a six month period. We believe that the system and

algorithm are stable enough for routine use. The algorithm also should be

useful for the characterization of many other linear features in all types of

microscopies

.

23. A Comparison of Two Transient Recorders for Use with The Laser

Microprobe Mass Analyzer

R. Fletcher and D. Simons

In the Laser Microprobe Mass Analyzer (LAMMA) , a transient waveform

recorder is used to capture the mass spectrum produced in a time-of-flight

mass spectrometer from a single pulsed ionization event. The recorder has

the characteristics of a digital oscilloscope. It incorporates a fast

analog- to-digital converter combined with a larger memory for storage of the

digitized waveform and is the key component that permits high sensitivity to

be achieved simultaneously for multiple elements in the LAMMA. The recorder

originally supplied with the LAMMA instrument had an A/D converter with a maximum digitization rate of 100 MHz, bandwidth of 25 MHz, a nominal resolution of 8 bits, and a memory capacity of 2048 locations (2 Kbytes).

Recently, a new generation of transient waveform digitizers has become available that offers modular design based on the CAMAC standard, maximum

digitization rate of 100 MHz, bandwidth of > 100 MHz, a nominal amplitude

resolution of 8 bits, and a memory capacity of 32,768 storage locations (32

Kbytes). The purpose of this comparison is to evaluate one of these new recorders and to compare its performance to that of the original recorder for

quantitative applications on the LAMMA instrument.

One experiment involved analyzing missing output codes in the A/D

converter using the histogram test. In this test, a full scale sine wave of

known frequency (100 KHz, 1 MHz, and 10 MHz) is sampled by each transient

recorder and the digitized waveform level is collected over many cycles. A

166
histogram is then produced giving the relative probability of occurrence of

the 256 amplitudes. While both 2Kb and 32Kb recorders have an increase in

lost codes for increasing slew rate, the 2Kb recorder had approximately 90

percent of its codes missing for the 10 MHz input. On the other hand, the

32Kb recorder missed less than 10 percent of the codes at this frequency.

This implies a dynamic amplitude resolution of greater than 7 bits, while the

2Kb recorder has only 4 bit resolution under the same conditions. For a direct comparison of the two recorders, each collected in a simultaneous

manner the waveform produced by the ion detector in the LAMMA 500. The

sample used in this comparative study was a sputtered glass film containing

oxides of 10 elements (similar to a zircon) at various weight percentages

which produce positive ion mass spectra with m/z values ranging from 1 to

270.

The main advantage of the 32Kb transient recorder is that a very large

portion of the mass range can be recorded at the maximum digitization rate of

100 MHz. Using only the 8 Kb memory fraction and the highest digitization

rate, spectra containing all the elements from hydrogen to uranium (actual mass range of m/z 0 to 367) can be recorded from a single laser ionization

event. The 2Kb recorder must have a digitization rate of 20 MHz (50 ns between samples) to gather the full elemental mass range (m/z 1 to 300). A

spectrum from the zircon glass film was recorded simultaneously at the same

input sensitivity by the 2Kb recorder operated at a digitization rate of 20

MHz and by the 32Kb recorder at 100 MHz. The 5X longer time between samples

of the 2Kb recorder results in very poor peak shape (due to the lack of point

density), often with only one data point per peak. This can lead to large errors in peak amplitude measurements. On the other hand, the 10 ns sampling

interval of the 32Kb recorder does not have this problem since there are a sufficient number of data points to define a peak. We conclude that the

larger memory, modular design, and better high frequency performance of the

32Kb recorder offer substantial advantages for quantitative work with the

LAMMA.

24. Automated Method for Analyzing Images Containing Electron Diffraction

Spots

D. S. Bright and E. B. Steel

The analytical electron microscope provides the possibility for

comprehensive charcterization of a sample at a spatial resolution as fine as

10 nm. Morphology can be determined from various imaging techniques, and

major and minor elemental constituents can be analyzed by means of x-ray and

electron energy loss spectrometries. A third major source of information is

available from the phenomenon of electron diffraction, which can provide the

crystal structure. In environmental samples, the solution of diffraction

patterns is often difficult because of the superposition of several different

patterns from the individual phases in complex aggregates. We have developed

an automated computer method for the analysis of electron diffraction images

of agglomerate particles. The method isolates the zone axis diffraction pattern in a polycrystalline diffraction image by isolating the spots from other

features of the image and by selecting the spots that belong to a regular

array. The method then determines the basis vectors for the array which can

be used to identify the particle by comparison with standard diffraction

data.

167
Several particles of differing crystal type often contribute to the

diffraction image yielding several superimposed diffraction patterns. The

particle of interest is oriented to a zone axis while the other particles are

at random orientations. Thus the diffraction maxima from the particle of

interest form a regular array amidst the less regularly positioned maxima

from the other particles. Automated analysis of such images is difficult

because of the overlapping diffraction images that yield complex combinations

of rings, arrays of spots, and randomly placed spots. Our automated method

includes image processing to locate all of the spots in the image and an algorithm to select groups of spots that belong to regular arrays. Each

array is described by a pair of basis vectors, which are then used for

compound identification by comparison with standard diffraction data.

The first step in processing such a diffraction image is to isolate the

spots from the rings, the background, and the image of the beam stop. The

next step is to select from all of the spots, a group or subset of spots that

represents a single crystal and thus gives a pair of basis vectors. The last

step is a more accurate determination of the basis vectors by averaging all

of their occurrences between the selected spots. The pattern thus identified

can be subjected to further analysis. The spacings between the diffraction

spots can be accurately measured and converted into equivalent lattice spacings, which can be used in conjunction with elemental analysis data to determine the crystal structure of the sample. In many cases, knowledge of the

crystal structure provides the information necessary to deduce the chemical

speciation and valence state of the elemental constituents of the sample.

25. Determination of the Radiation Damage to Polycarbonate Film SRMs Used

in X-Ray Spectrometry

G. L. Sleater , J. Crissman, and P. A. Pella

During the development of thin film XRF standards for calibration of

x-ray spectrometers issued as SRM 1832 and SRM 1833, both energy (EDX) and

wavelength-dispersive (WDX) spectrometers were used. Although no physical

change was observed in standards irradiated in the EDX spectrometer , specimens irradiated in the WDX spectrometer exhibited small cracks parallel to

the striation pattern of the polycarbonate substrates. Repeated exposure in

the WDX system caused further cracks to form which eventually led to failure

of the film. This failure was due to the effect of x-ray radiation from

high-powered x-ray tubes (up to 3 kW) used in conventional WDX spectrometers.

A study of radiation damage was undertaken to establish guidelines and to

make recommendations regarding use of these SRMs to potential users. Specimens of polycarbonate were irradiated at different x-ray tube power settings

for known periods of time in the NBS WDX spectrometer. The tensile strengths

of both irradiated and control (virgin film) specimens were measured using a servo-controlled hydraulic test machine in directions both parallel and perpendicular to the striation pattern of the polycarbonate films. These mea- surements showed that a quantitative relationship existed between irradiation

expressed as a function of x-ray tube power and exposure time and the loss of

tensile strength by the polycarbonate film. For control specimens which were

not irradiated, the mean value of the strain necessary to cause the specimen

to tear apart (i.e., strain at break) was 0.16 with a standard deviation of

0.02. Such a variation in the strain at break can arise from factors such as inhomogeneities in the films. With increased x-ray doses it was found that

the strain at break tends to decrease reaching a value of about one-half 100

168
kilowatt-minutes. Because of the significant variation in the strain at break

among the control specimens it can be argued that for doses below 30-40 kilowatt-minutes, there is little, if any deterioration in the mechanical properties of the films. These results showed that the effect of radiation exposure

is cumulative and not solely dependent on the x-ray tube power used.

a result of this investigation, some guidelines have been established warn potential users of these films that there exists a safety limit

(determined easily by measuring the x-ray power and exposure time) beyond

which significant deterioration of the standard will occur.

In the future, we expect to compare radiation levels from EDX with WDX

spectrometers using radiation dossimeters in order to obtain an estimate of

exposure limits for standards measured in EDX systems as well. A research

paper describing this study is currently in preparation and should be

submitted for publication before the end of 1985.

26. Improvements in NBSGSC - A Fortran Program for Quantitative X-Ray

Fluorescence Analysis

G. Y. Tao , P. A. Pella, and R. M. Rousseau

In a continuing effort to assess and improve interelement correction

procedures, we developed and published a computer program for performing

quantitative analysis of bulk specimens. The program (NBSGSC) written in

Fortran IV corrects for x-ray interelement effects from first principles

(fundamental parameter) calculations using hypothetical elemental compositions, and is available as "NBS Technical Note 1213". Fundamental parameter

methods are particularly attractive especially in analytical situations where

standards of the same type as the analyte specimens are not available.

Interelement effects are corrected by NBSGSC using the comprehensive

alpha coefficient algorithm proposed by Lachance (COLA). The program is a revision of ALPHA and CARECAL originally written by R. M. Rousseau of the

Geological Survey of Canada. Part one of the program (CALCO) performs the

calculation of theoretical corrections called alpha coefficients, and part

two (CALCOMP) computes the composition of the analyte specimens. The analysis of alloys, pressed minerals, and fused specimens can currently be treated

by the program. An important feature of NBSGSC is that in addition to using

measured x-ray tube spectral distributions, spectra from seven commonly used

x-ray tube targets could also be calculated with an NBS algorithm included in

the program. Other features include: 1) fundamental parameters required for

calculating alpha coefficients such as mass absorption coefficients, fluorescence yields, jump ratios, analyte line wavelengths, and absorption edge

wavelengths are either computed or stored in the program to minimize data

input by the user, 2) the user has the option of selecting the algorithm of

Heinrich, or Thinh and Leroux for calculating mass absorption coefficients,

3) one of three sample preparation conditions can be chosen when fusing specimens to allow greater flexibility in sample-to-flux ratios used in various

laboratories, and 4) when analyzing specimens, known concentrations of elements previously determined by other techniques and are not to be analyzed

can be entered as fixed concentrations. A menu procedure of operating NBSGSC

is followed where the user answers a question, selecting the appropriate

answers among the ones provided, and enters the required data.
An evaluation of the COLA algorithm has been performed and is the

subject of a technical paper submitted for publication in which results of

analysis are intercompared with another well-known program - NRLXRF. Theoretical alpha coefficients provide the general relationship of matrix influences on the analyte, and actual standard reference materials are used to

adjust calculations of specimen composition from theory. Therefore, appropriate standards are very important for obtaining best results as is the case with other fundamental parameter methods. An important element of the COLA

algorithm is that it is applicable over the entire analyte composition range

from 0 to 100$. We expect that NBSGSC will be of significant utility to the

x-ray fluorescence community and invite comments from users. Future research

in fundamental parameters will be directed to a critical examination of some

of the constants that are used in these theoretical calculations in an effort

to improve the accuracy of analysis.
C. Outputs and Interactions

(Gas and Particulate Science Division)

1 . Publications

Cadoff, B. C., and Hodgeson, J., Passive Sampler for Ambient Levels of

Nitrogen Dioxide, Analytical Chemistry, 55_, 2083-2085 (1983).

Dunn, P. J., Peacor, D. R., Simmons, W. B., and Newbury, D. E.,

Fredrikssonite, A New Member of the Pinakiolite Group, From Langban,

Sweden, Geologiska Foreningesn i Stockholm Forhandlingar , 1 05 , 335— 3^0

(1 983).

Zielinski, W. L. , Jr., Kirchhoff, W. H. , and Eberhardt, K. R.

,

Interlaboratory Testing of Newly Developed Physical/Chemical Property

and Transformation Tests: Interlaboratory Evaluation of Vapor Pressure

Test Standard Based on Gas Saturation Procedure, Final Report to EPA

(1983).

Bright, D. S. , Myklebust, R. L. , and Newbury, D. E. , Stereo Presentation of

Monte Carlo Electron Trajectory Simulations, J. Microscopy, 1 36 113-120

(1984).

Butrymowicz, D. B. , Newbury, D. E. , Turnbull, D., and Cahn, J. W.,

Diffusion-Induced Grain Boundary Migration in the Au-Ag System, Scripta

Metallurgica , 1_8, 1005-1010 (1984).

1 4 Currie, L. A., C As A Tracer for Carbonaceous Aerosols: Measurement

Techniques, Standards and Applications, Aerosols , B. Y. H. Liu, D. Y. H. Pui and H. J. Fisson, Eds., Elsevier Science Publishing Co., New York,

375 (1984).

Currie, L. A., Klouda, G. A., and Voorhees, K. J. , Atmospheric Carbon: The

Importance of Accelerator Mass Spectrometry, Nuclear Instrum. Methods,

233 , 371 (1984).

Klouda, G. A., Currie, L. A., Donahue, D. J., Jull, T. and Zabel, T, M.,

Accelerator Mass Spectrometry Sample Preparation: Methods for 1 V In

50-1000 Microgram Samples, Nuclear Instrum. Methods 233 , 265 (1984).

Newbury, D. E., Williams, D. B., Goldstein, J. I., and Fiori, C. E.,

Observations on the Calculation of k^g Factors for Analytical Electron

Microscopy, Analytical Electron Microscopy, San Francisco Press, 276-278

(1 984).

Taylor, H. F. W. and Newbury, D. E. , An Electron Microprobe Study of A Mature

Cement Paste, Cement and Concrete Research, 1_4, 565-573 (1984).

Williams, D. B., Newbury, D. E., Goldstein, G. M., and Fiori, C. E., On the

Use of Ionization Cross Sections in Analytical Electron Microscopy, J. Microscopy, 1 36 , 209-218 (1984).

Bass, A. M. and Paur , R. J. , The Ultraviolet Cross-Sections of Ozone,

Atmospheric Ozone, Symposium 1984 , C. S. Zerefos and A. Ghazi , Eds,

Rediel Publ. Co., 606-61 6 , (1985).

171
Bright, D. S. and Steel, E. B. , STEM Calibration of Analysis of Hough

Transformed Images of Optical Grating Replicas, Microbeam Analysis , San

Francisco Press, 155 (1985).

Bright, D. S. and Steel, E. B. , Automated Method for Analyzing Images

Containing Electron Diffraction Spots, Microbeam Analysis , San Francisco

Press, 163 (1985).

Byrd, G. D., Fatiadi, A. J., Simons, D. S. , and White, E. , Laser Desorption

Mass Spectrometry of Some Salts of Squaric Acid, Organic Mass

Spectrometry (submitted 1985).

Currie, L. A., Recommendations for Nomenclature in Evaluation of Analytical

Methods, International Union of Pure and Applied Chemistry, (submitted

1985)

.

Currie, L. A., On the Use of Simulation Data Sets for Assessing

Interlaboratory Pattern Recognition Accuracy, Optical Engineering

(accepted for publication 1985).

Currie. L. A., Klouda, G. A., Schjoldager, J., and Ramdahl , T. , The Power of

^ u Measurements Combined with Chemical Characterization for Tracing

Urban Aerosol in Norway, (submitted to Radiocarbon 1985).

Currie, L. A., Klouda, G. A., Elmore, D., and Gove, H. E. , Radiocarbon Dating

of Microgram Samples: Accelerator Mass Spectrometry and Electromagnetic

Isotope Separation, Nuclear Instrum. Methods, (in press 1985).

Currie, L. A., The Many Dimensions of Detection In Chemical Analysis, Chapter

5 , Chemometrics in Pesticide/Environmental Residue Analytical

Determination , D. Kurtz, Ed., ACS Symposium Series, No. 284, American

Chemical Society (1985).

Currie, L. A., The Limitations of Models and Measurements as Revealed Through

Chemometric Intercomparison, (to be published in NBS J. Res. 1985).

Etz, E. S. , Newbury, D. E. , Dunn, P. J. , and Grice, J. D., Application of

Synergistic Microanalysis Techniques to the Study of A New Mineral

Containing Light Elements, Microbeam Analysis, San Franciso Press, 60

(1985).

Fletcher, R. A. and Fatiadi, A. J., Laser Ionization Mass Spectrometry of

Poly ( 4-vinylpyridine) , Poly. Comm, (in press 1985).

Fletcher, R. A. and Simons, D. S. , A Comparison of Two Transient Recorders

for Use With the Laser Microprobe Mass Analyzer, Microbeam Analysis , San

Francisco Press, 319 (1985).

Fried, A. and Sams, R. , Tunable Diode Laser Absorption Spectrometry for

Ultra-Trace Measurement and Calibration of Atmospheric Constituents

American Society for Testing Materials, Volume Sampling and Calibration

for Atmospheric Measurements (submitted 1985).
Fried, A., Sams, R. , Dorko, W. and Elkins, J., Intercomparison of Tunable

Diode Laser, Chemiluminescence and Fourier Transform IR Detection for

the Determination of High Concentration Nitrogen Dioxide in Air Gas

Mixtures, Analytical Chemistry (submitted 1985).

Grice, J. D. , Van Velthuizen, J. , Dunn, P. J. , Newbury, D. E. , and Etz, E. S., Moydite, (Y . REE) [B(0H)4] (CO^), A New Mineral from Evans-Lou

Pegmatitie, Quebec, Canadian Mineralogist (submitted 1985).

Hughes, E. E. , Standards for the Measurement of Atmospheric Carbon Dioxide

Based on Absolute Gravimetry, Tellus (submitted 1985).

Klouda, G. A., Currie, L. A., Tompkins, G. B. , Wise, S. A., Allen, C. F. , and

Diamondstone, B. I., Reference Materials and Blank Evaluation Techniques

for 4 C Measurements on Small Aerosol Samples, Radiocarbon, (submitted

1985).

1 4 Klouda, G. A., Currie, L. A., Donahue, and Jull, A. J. T., Atmospheric CO

and and 1 uHjj Measurements by Accelerator Mass Spectrometry, Radiocarbon

(submitted 1985).

Lindner, M., Leich, D. A., Borg, R. J., Russ. G. P., Bazan, J. M., Simons, D.

S. , and Date, A. R. , The Half-Life of °^Re, Nature (submitted 1985).

Lowenthal , D. H., Hanamura, C. R., Rahn, K. A., and Currie, L. A., Estimation

and Error in Chemical Mass Balance Apportionments,- Atm. Environ,

(submitted 1985).

Marinenko, R B., Myklebust, R. L. , Bright, D. S. , and Newbury, D. E. , Wavelength-Dispersive Techniques for Compositional Mapping in Electron

Probe Microanalysis, Microbeam Analysis , San Francisco Press, 159

(1985).

Musselman, H. , Linton, R. W., and Simons, D. S., The Use of Laser Microprobe

Mass Analysis for Nickel Speciation in Individual Particles of

Micrometer Size, Microbeam Analysis , San Francisco Press, 337 (1985).

Mulholland, G. W., McKenzie, R. L., Marx, E., and Fletcher, R. A., Refractive

Index and Evaporation Rate of Individual Smoke Droplets, Langmuir 1_, No.

3, 367 (1 985).

Myers, R. C., Indoor Pollutant Measurements of Sulfur Dioxide, Nitrogen

Oxides, and Ozone in the National Library of Medicine, Final Report to

the National Library of Medicine (1985).

Myklebust, R. L, Marinenko, R. B., Newbury, D. E., and Bright, D. S.,

Quantitative Calculations for Compositional Mapping Techniques in

Electron Probe Microanalysis, Microbeam Analysis, San Francisco Press,

101 (1985).

Myklebust, R. L. , Marinenko, R. B. , Newbury, D. E. , and Bright, D. S.

,

Quantitative Compositional Mapping On An Electron Microprobe, The

Institute of Physics (to be published 1985).

173
Newbury, D. E. , Compositional Mapping of Thick Specimens, Microbeam Analysis , San Francisco Press, 204 (1985).

Pella, P. A., Feng, L. , and Small, J. A., An Analytical Algorithm for

Calculation of Spectral Distributions of X-Ray Tubes for Quantitative

X-Ray Fluorescence Analysis, X-Ray Spectrum, 1_4, 125 (1985).

Pella, P. A., Tao, G., Dragoo, A. L., and Epp, J. M., X-Ray Spectrometric

Determination of Ceria-Yttria Mixtures After Borate Fusion, Analytical

Chemistry, 57 1752 (1985).

Pella, P. A., Newbury, D. E. , Steel, E. B. , and Blackburn, D. H. , Development

of NBS Thin Glass Standard Films for X-Ray Fluorescence Spectrometry,

Analytical Chemistry, (submitted 1985).

Pella, P. A. and Tao, G., Intercomparison of Fundamental Parameter

Interelement Correction Methods — Part 2, J. of X-Ray Spectrometry,

(submitted 1985).

Pine, A. S. , Fried, A., and Elkins, J. W., "Spectral Intensities in the

Fundamental Bands of HF and HC1 , J. Molec. Spectros., 1 09 , 30-45

(1985).

Pine, A. S. and Fried, A., Self-Broadening in the Fundamental Bands of HF and

HC1, J. Molec. Spectros., (submitted 1985).

Rhoderick, G. C., Cuthrell, W. F. , and Zielinski, W. L. , A Gravimetric

Technique for the Preparation of Accurate Trace Organic Gas Standards,

Transactions, APCA International Specialty Conference, Quality Assurance

in Air Pollution Measurements, 239-246 (1985).

Rook, H. L. , The Role of Neutron Activation Analysis in Trace Analysis, J. of

Trace and Microprobe Techniques, 2, No. 3 & 4, 189-216 (1984-85)

Steel, E. B. and Small, J. A., Accuracy of Transmission Electron Microscopy

for the Analysis of Asbestos in Ambient Environments, Analytical

Chemistry, 57, No. 1, 209-213 (1985).

Steel, E. B., Myklebust, R. L., and Bell, A. A., Development of an Automated

Digital Image Acquisition System for Analytical Electron Microscopy,

Microbeam Analysis , San Francisco Press, 151 (1985).

Steel, E. B. and Small, J. A., Analytical Methods: Light and Electron

Microscopy, Proceedings of Workshop on the Monitoring and Evaluation of

Airborne Levels Following An Abatement Program.

Tao, G., Pella, P. A., and Rousseau, R. M., NBSGSC — A Fortran Program for

Quantitative X-Ray Fluorescence Analysis, NBS Tech. Note 1213 (1985).

Zielinski, W. L. , Jr., Miller, M. M., Ulma, G., and Wasik, S. P., GLC

Separation Behavior of Polychlorinated Biphenyl Isomers Between A Neumatic Liquid Crystal Phase and a Non-Polar Phase, Analytical

Chemistry (submitted 1985).
2 . Talks

Etz, E. S. , "Optical Microprobe Spectroscopy," Atlantic Richfield Company,

Exploration and Production Research Center, Plano, TX, October 9, 1984.

Invited

Rhoderick, G. C., "A Gravimetric Technique for the Preparation of Accurate

Trace Organic Gas Standards," APCA International Specialty Conference on Quality Assurance in the Air Pollution Measurements, Boulder, CO,

October 16, 1984.

Elkins, J. W., "Current Laboratory Spectroscopy Techniques by FTIR,

Spectroscopy Workshop, NASA Langley Research Center, Norfolk, V A,

October 17, 1984. Invited

Sheridan, P. J. , "Quantitative Elemental Analysis of Individual Particles

from Environmental Aerosols," Division of Analytical, Nuclear, and

Environmental Chemistry, Department of Chemistry, University of

Maryland, College Park, MD, November, 1984.

Newbury, D. E. , "Microbeam Chemical Analysis," NBS ADABSE Workshop, November,

5, 1984.

Simons, D. S. , "Laser Microprobe Mass Spectrometry," Symposium on Surface

Modification by Directed Deposition of Energy, Greater New York Chapter,

American Vacuum Society, IBM Thomas J. Watson Research Center, Yorktown

Heights, NY, November 8, 1984. Invited

Fletcher, R. A., "The Use of the Laser Microprobe Mass Analyzer in Analytical

Chemistry," Eighth Annual Users Conference, Major Analytical Instruments

Facility of Case Western Reserve University, Cleveland, OH, November 26,

1984. Invited

Sheridan, P. J. , "The Sources of Particles Collected on the GTE/CITE

Experiment," American Geophysical Union (AGU) Meeting, San Francisco,

California, December 4, 1984.

Currie, L. A., "On the User of Simulation Data Sets for Assessing

Interlaboratory Pattern Recognition Accuracy," US Army Conference on Spectral Pattern Recognition, Aberdeen, MD, December 11, 1984. Invited

Currie, L. A., "Lower Limits of Detection," Health Physics Society 18th

Midyear Topical Symposium, Colorado Springs, CO, January 8, 1985.

Newbury, D. E., "Elemental Analysis at the Nanometer Scale", National

Engineering Laboratory, February 11, 1985. Invited

Newbury, D. E., "Future Trends, Microanalysis Techniques," Microbeam Analysis

Society of Southern California, Scripps Institution of Oceanography,

February 15, 1985. Invited

Dorko, W. D., "Simultaneous Quantitative Tunable Diode Laser and

Chemilumenscent Detector Measurements of High Concentration NO2 in Air

Gas Mixtures," 1985 Pittsburgh Conference on Analytical Chemistry and

Applied Spectroscopy, New Orleans, LA, February 25, 1985.

175
Cadoff, B. C., ’’Cryogenic Preconcentration Technique for the Analysis of

Trace Organic Vapors in Gas Mixtures,’’ Pittsburgh Conference, New

Orleans, LA, February 26, 1985.

Sleater, G. L. , The Application of X-Ray Fluorescence Analysis to the

Certification of Standard Reference Materials," The 1985 Pittsburgh

Conference, paper No. 392, New Orleans, LA, February 26, 1985.

Zielinski, W. L., Jr., "Microgravimetric Development and GLC Verification of

Accurate, Stable Mixtures of Volatile Toxic Organics in the 10 ppm to 1 ppb Range," 1985 Pittsburgh Conference on Analytical Chemistry and

Applied Spectroscopy, New Orleans, LA, February 27, 1985.

Fried, A., "NO2 Standards Normalization in NASA's Cite 2 Global Tropospheric

Experiment," NASA’s Third Science Team Meeting for the Global

Tropospheric Experiment, Arlington, VA, March 18, 1985. Invited

Small, J. A., "Visibility of Chrysotile Asbestos in the SRM , " Asbestos Fiber

Measurements in Building Atmospheres Workshop, Organized by Ontario

Research Foundation on Behalf of Health and Welfare Canada, March 26,

1 985.

Newbury, D. E. , "Compositional Mapping for Microstructural Characterization

of Materials," Department of Metallurgy and Materials Engineering

Seminar Series, Lehigh University, Bethlehem, PA, March 28, 1985.

Invited

Small, J. A., "AEM-LAMMA Analysis of Particles," Joint Meeting of the

American Vacuum Society and Rocky Mountain Microscopy Society, Denver,

CO, May 8, 1985. Invited

Newbury, D. E. , "Compositional Mapping by Multiple Techniques," Center for

Materials Science Seminar, NBS, May 10, 1985. Invited

Currie, L. A., "The Limitations of Models and Measurements as Revealed

Through Chemometric Intercomparison," Chemometrics Research Conference,

Gaithersburg, MD, May 20, 1985.

Etz, E. S. , "Molecular Microanalysis with the Laser Raman Microprobe," 2nd

International Symposium on the Biology and Toxicology of Metals Using

Nuclear Analytical Methods," Brookhaven National Laboratory, Upton, Long

Island, NY, May 21, 1985. Inv ited

Newbury, D. E., "Compositional Mapping," Physics Discussion Group, May 28,

1985. Invited

Myklebust, R. L. , "Quanti tative X-Ray Microanalysis Using the ETEC SEM. The

Use and Abuse of NBS FRAME C," Center for Material Science Electron

Microscope Users Group Seminar, May 30, 1985. Invited

Newbury, D. E., "Quantitative X-ray Microanalysis Using the ETEC SEM; the Use

and Abuse of NBS FRAME C," Center for Materials Science, Electron

Microscope Users Group Seminar, May 30, 1985. Invited

176
1 4 Klouda, G. A., "Reference Materials and Blank Evaluation Techniques for C

Measurements on Small Aerosol Samples," 12th International Radiocarbon

Conference, Norwegian Inst, of Technology, Trondheim, Norway, June 24,

1985.

i ij Currie, L. A., "The Power of C Measurements Combined with Chemical

Characterization for Tracing Urban Aerosol in Norway," 12th

International Radiocarbon Conference, Norwegian Institute of Technology,

Trondheim, Norway, June 26, 1985.

Etz, E. S., "Advances in Micro-Raman Instrumentation Applied to Calcium

Phosphate Research," Gordon Research Conference on Calcium Phosphates,

Plymouth State College, Plymouth, NH, June 26, 1985. Invited

14 14 Klouda, G. A., "Atmopspheric CO and CH^ Measurements by Accelerator Mass

Spectrometry," 12th International Radiocarbon Conference, Norwegian

Institute of Technology, Trondheim, Norway, June 26, 1985.

Currie, L. A., "Chemometric , Isotopic and Organic Techniques to Study Man’s

Impact on the Atmosphere," Norwegian Institute for Air Research,

Lillestrom, Norway, July 1, 1985.

Currie, L. A., "Trace Carbon in the Atmosphere: Knowledge Gained Through

Receptor Modeline and ^C Accelerator Mass Spectrometry," RISO National

Laboratory, Roskilde, Denmark, July 3, 1985.

Currie, L. A., "Pitfalls in the Application of Linear Models to Atmospheric

Source Apportionment; Assumption-Testing and Validation via Isotope

Measurement," Instituut voor Nucleaire Wetenschappen , University of

Gent, Gent, Belgium, July 5, 1985.

Etz, E. S., "Application of Synergistic Microanalysis Techniques to the Study

of a Possible New Mineral Containing Light Element," 20th Annual

Conference of the Microbeam Analysis Society, Louisville, KY , August 5,

1 985.

Mykelbust, R. L. , "Quantitative Calculations for Compositional Mapping

Techniques in Electron Probe Microanalysis", Microbeam Analysis 1985,

Louisville, KY, August 5, 1985.

Steel, E. B. , "Development of an Automated Digital Image Acquisition System

for Analytical Electron Microscopy," 20th Annual Conference of the

Microbeam Analysis Society, Louisville, KY , August 5, 1985.

Newbury, D. E., "Compositional Mapping of Thick Specimens," Annual Conference

of the Microbeam Analysis Society, Louisville, KY , August 6, 1985.

Invited

Newbury, D. E. , "Trace Element and Light Element Imaging by Secondary Ion

Mass Spectrometry , " Annual Conference of the Microbeam Analysis Society,

Louisville, KY, August 6, 1985.

Fletcher, R. A., "A Comparison of Two Transient Recorders for Use With Laser

Microbeam Mass Analyzer," 1985 Microbeam Analysis Society, Louisville,

KY, August 8, 1985.

177
Etz, E. S., "Raman Microprobe Spectroscopy in Chemical Microanalysis," Gordon

Research Conference on Analytical Chemistry, New Hampton School, New

Hampton, NH, August 12, 1985. Invited

Newbury, D. E., "Compositional Mapping of Thick Specimens on A Micrometer

Spatial Scale," Gordon Conference on Analytical Chemistry, August 12,

1985. Invited

Currie, L. A., "Performance Characteristics of the Chemical Measurement

Process: Proposed International Nomenclature," NBS, August 13, 1985.

Invited

Dorko, W. D., "Special Calibration Systems for Reactive Gases and Other

Difficult Measurements," ASTM Conference on Sampling and Calibration for

Atmospheric Measurements, Boulder, CO, August 13. 1985. Invited

Mitchell, G. D., "Trace Gas Calibration Systems Using Permeation Devices,"

ASTM Conference on Sampling and Calibration for Atmospheric

Measurements, Boulder, CO, August 13. 1985. Invited

Fried, A. and Sams, R., "Tunable Diode Laser Absorption Spectrometry for

Ultra-Trace Measurements and Calibration of Atmospheric Constituents,"

ASTM Conference on Sampling and Analysis of Atmospheres, Boulder, CO,

August 14, 1985. Invited

Rhoderick, G. C., "Preparation of Standards for Gas Analysis," Symposium on Natural Gas Energy Measurement, Chicago, IL, August 26, 1985. Invited

Myklebust, R. L, "Compositional Mapping," A.E.R.E., Harwell, England, August

27, 1985. Invited

Myklebust, R. L. , "Compositional Mapping," University of Bath, Bath, England,

August 28, 1985. Invited

Pella, P. A., "NBSGSC — A Fortran Program for Quantitative X-Ray

Fluorescence Analysis," The 24th Colloquium Spectroscopicum

Internationale, Garmisch-Partenkirchen , Federal Republic of Germany,

September, 1985. Invited

Myklebust, R. L. , "Quantitative Compositional Mapping on An Electron

Microprobe," EMAG 85, Newcastle Upon Tyne, England, September 5, 1985.

Myklebust, R. L. , "Compositional Mapping," University of Cambridge, England,

September 6, 1985. Invited

Verkouteren, R. M., "Characterization and Optimization of Carbon Chemistry

Preceeding Accelerator Mass Spectrometry," ACS Symposium on Accelerator

Mass Spectrometry, Chicago, IL, September 11, 1985.

178
Simons, D. S. , "Laser Microprobe Mass Spectrometry," Microbeam Analysis

Society National Tour Speaker, Houston Area Microbeam Analysis Society,

Houston, TX, December 3, 1984; New Mexico Microbeam Users Group,

Albuquerque, NM, December 4, 1984; Arizona Society for Electron

Microscopy and Microanalysis, Phoenix, AZ, December 5, 1984; Southern

California Society for Electron Microscopy and Microbeam Analysis

Society of Southern California, Los Angeles, CA, December 6, 1984;

Washington Area Microbeam Analysis Society of Southern California, Los

Angeles, CA, December 6, 1984; Washington Area Microbeam Analysis

Society, NBS, April 18, 1985. Invited

Newbury, D. E., "Compositional Mapping: Future Trends in Microanalysis," New

England Society for Electron Microscopy, Newton, MA, December 5, 1985.

Invited

3. Committee Assignments

Harry Rook

Chairman, EPA Scientific Review Panel on Quality Assurance

Chairman, Office of Water Data Coordination, Committee 5F

Chairman, ASTM D-22.03 Sampling and Analysis of Ambient Atmospheres

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Member, ASTM D-22. 01 Quality Assurance

Member, IUPAC Commission V.3 (Analytical Nomenclature)

Arnold Bass

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Member, ASTM D-22. 01 Quality Assurance

Member, ASTM D-22.03 Sampling and Analysis of Ambient Atomspheres

Member, Ozone Science Guidance Comm., NESD/S

David Bright

Member, ASTM E-29 Particle Size Measurement

Member, ASTM SC. 10 Liquid Particle Measurement

Lloyd Currie

Member, CAC, Quality Assurance Task Force

Associate Member, IUPAC Commission on Analytical Nomenclature

Consultant, International Atomic Energy Agency, on Limit of

Detection

Member, Interagency Workshop on the Future of Accelerator

Mass Spectrometry in the U.S.A.

William Dorko

Member, American Chemical Society, Washington Section, Board

of Managers

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Edgar Etz

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Alan Fried

Member, NASA's Third Science Team Committee for the Global

Tropospheric Experiment

179
Ernest Hughes

Member, ISO/TC 158 Gas Analysis

Member, ISO/TC 1 58 /SC— 1 Methods for Preparation and Definition of

Gas Mixtures for Calibration

Member, ISO/TC 158/WG-2 Transfer Lines and Sampling

Member, ISO/TC 158/WG-3 Evaluation of the Characteristics of Analysis

Member, ISO/TC 159/WG-4 Analysis of Natural Gas

Member, ISO/TC 158/WG-1 Terminology

Raymond McKenzie

Member , ASTM

Member , ASTM

Member , ASTM

Member , ASTM

D-22 Sampling and Analysis of Atmospheres

D-22.01 Quality Assurance

D-22. 03 Sampling and Analysis of Ambient Atomspheres

E-29 Particle Size Measurement

Robert Myklebust

Member, ASTM E-2 Emission Spectroscopy

Member, ASTM E-2. 04 Standard Reference Materials

Dale Newbury

Member, ASTM E-42 Surface Analysis

Member Journal of Microscopy, Editorial Review Board

Member, Scanning, Editorial Review Board

Member, J. Trace and Microprobe Techniques, Editorial Review Board

Member, Journal of Electron Microscopy Techniques Editorial Review

Board

Peter Pella

Member, ASTM E-2 Emission Spectroscopy

Member, ASTM E-2. 02 Statistics, Calibration and Standardization

Gerald Sleater

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Member, ASTM D-22. 06 Source Sampling

Walter Zielinski

Member, Interagency Committee on C02 and Climate

Member, Interagency Committee for Stratospheric Ozone Protection

Member, Interagency Committee for Indoor Air Quality

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Member, Journal of Analytical Toxicology, Editorial Review Board

4. Other

a. Seminars

April 18, 1985 - Dr. David Joy, Bell Laboratories, "Modeling

Energy Dispersive X-Ray Spectrometers."

(Division Sponsor: D. Newbury)

May 1 4, 1 985 - Dr. Dae Won Moon, Chemistry Department,

Princeton University, "Study of Organic

Monolayers on Silver Surfaces by

Angle-Resolved SIMS." (Division Sponsor: D. Simons)

1 80
May 16, 1985 M. Keenlyside, Thor Surface Science, Oxford,

England, "Microarea Photoelectron Imaging and

Spectroscopy." (Division Sponsor: D. Newbury)

May 22, 1985 - Dr. Ulrich Seydel , Research Inst. Borstel, W.

Germany, "Desorption/Ionization Mechanisms at

High Irradiances in Laser Desorption Mass

Spectrometry." (Division Sponsor: D.

Simons

)

May 29, 1985 - Dr. Louis Codispoti, Bigelow Laboratory for

Ocean Science, "Effects of Man’s Impingement

and El Nino Events on the Biology and

Chemistry of the Ocean Off Peru." (Division

Sponsor: J. Elkins).

b. Standard Reference Materials

X-Ray Fluorescence

SRM 88b Dolomitic limestone

SRM 1 632b Trace elements in Coal

SRM 76a, 77a, 78a, Burnt refractories

SRM 888 Tungsten Carbide

SRM 1832 Orange Cap Cement

SRM 1833 Grey Cap Cement

SRM 141

1

Multi-Component Glass Sc SRM 1 41 2 Multi-Component Glass Sc SRM 141 3 Glass Sand

Gas Metrology

SRM 1626 SO

2 Permeation Tube

SRM 1629a NO2 Permeation Device

SRM 1 668b Propane in Air

SRM 1683b NO in N

2

SRM 1684b NO in N

2

SRM 1685b NO in N

2

SRM 1 686b NO in N

2

SRM 1687b NO in N

2

SRM 1693a SO2 in N

2

SRM 1700 Blood Gas CO 2 in N

2

SRM 1701 Blood Gas CO 2 and O

2 in

SRM 1702 Blood Gas CO 2 and O

2 in

SRM 1703 Blood Gas C0 2 and O

2 in

SRM 1912 Tetrachloroethylene Perr

SRM 2607 CO 2 and N

2 O in Air

SRM 2608 CO 2 and N

2 O in Air

SRM 2609 CO 2 and N

2 0 in Air

SRM 2610 CO 2 and N

2 O in Air

SRM 2626a CO 2 in N

2

1 81
Analytical Laser Spectrometry

SRM 1 686b Nitric Oxide in Nitrogen

SRM 1687b Nitric Oxide in Nitrogen

SRM 2630 Nitric Oxide in Nitrogen

SRM 2631 Nitric Oxide in Nitrogen

SRM 2653 Nitrogen Dioxide in Air

SRM 2654 Nitrogen Dioxide in Air

SRM 2655 Nitrogen Dioxide in Air

SRM 2656 Nitrogen Dioxide in Air

182
NBS-114A 'REV. 2-OC) U.S. DEPT. OP COMM. BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO. NBSIR 85/3272

2. Performing Organ. Report No.) 3. Publication Date

December 1985

4. TITLE AND SUBTITLE

Technical Activities, 1985, Center for Analytical Chemistry

5. AUTHOR(S)

R. A. Durst, H. S. Hertz, J. K. Taylor

6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions)

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8 . Type of Report & Period Covered

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City, State. ZIP)

Same as above.

10. SUPPLEMENTARY NOTES

Oocument describes a computer program; SF-185, FlPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

This report summarizes the technical activities of the Center for

Analytical Chemistry at the National Bureau of Standards. It emphasizes

activities over the Fiscal Year 1985 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; voluntary

standards

13. AVAILABILITY

rxi Unlimited

| | For Official Distribution. Do Not Release to NTIS —I Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. fg Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

189

15. Price

$16.95
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