sLjA . ^5 0

NBSIR 81-2425 c^;

Annual Report 1981

Center for Analytical Chemistry

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory

Washington, DC 20234

October 1 980

Final

ssued December 1981

Prepared for U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington, DC 20234

NBSIR 81-2425

ANNUAL REPORT 1981

CENTER FOR ANALYTICAL CHEMISTRY

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

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory

Washington, DC 20234

October 1 980

Final

Issued December 1981

Prepared for U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington, DC 20234

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

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

this report to specify adequately the experimental procedure. Such

identification does not imply recommendation or endorsement by the National

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

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

Page

I. CENTER FOR ANALYTICAL CHEMISTRY

A. Center Overview 1 B. Voluntary Standardization and Quality Assurance 5

C. Pilot National Environmental Specimen Bank Program 9

D. Service Analysis 16

E. Instrument Development Group 18

1. Group Overview 18

2. Selected Technical Accomplishments 19

a. High Reproducibility Analysis with the Infrared

Diode Laser 19

b. LEI Ion Collection Dynamics 23

c. Stepwise Excitation Laser Enhanced Ionization

Spectrometry 25

d. Spatially- and Temporally-Resolved Studies of

Laser-Perturbed Atom Populations in an Analytical Flame 29

e. The Use of Microcomputers in the Center for

Analytical Chemistry 33

f. Inorganic Ion-Doped Glass Beads as Potential

Microspectrofluorimetric Standards 34

3. Outputs and Interactions 37

II. INORGANIC ANALYTICAL RESEARCH DIVISION

A. Division Overview 41

B. Selected Technical Accomplishments 51

1. Application of Sampling Theory to Particulate

Biological Samples 51

2. Determination of Ultratrace Platinum in

Biological Materials 53

3. A New Method for the Determination of Sulfur by

Thermal Ionization Mass Spectrometry 54

4. An Investigation of Biases in the Determination of

Sulfur in Steel by Emission Spectrometry 56

5. Determination of Chlorine and Sulfur in

Cadmium Sulfide 58

6. Determination of 1-129 in Biological Matrices 59

7. Analysis of Human Liver for Baseline Lead and

Thallium 60

8. Development of a Radiochemical Separation

Procedure for Tin 62

9. Development of a Fluorescent Glass Standard for

Calibration of Instrumentation Used for the

Evaluation of Dye Penetrants 63

10. Determination of Halogens in Organic Liquids by

Neutron Activation Analysis 64

11. The Determination of Trace Elements in

Biologicals and Injectables 66

i
Page

12. Application and Evaluation of High Sensitivity Mass

Spectrometry for Isotopic and Elemental Abundance

Measurements of Uranium and Plutonium 67

13. Development of Improved Matrix Modifiers for Use in

Atomic Absorption Spectrometry 70

14. Development of Silica-Gel Procedures for the Analysis

of Trace Quantities of Copper and Nickel 72

15. Research to Develop High Accuracy Coulometric Assay

Methods for Uranium Metal and Uranium Oxides 73

16. Development of a High Precision Method for the

Assay of Milligram Samples of Uranium 74

17. Research to Develop ID/MS for Trace Concentrations

of Vanadium 75

18. Investigation of Ionic Chromium Speciation 77

19. Transfer and Analysis of Inductively Coupled Plasma

(ICP) Emission Data Using a Mini- and a Main-Frame

Computer on the NBS Data Network 78

20. Evaluation of Sources of Error in D.C. Plasma

Spectrometry 79

21. Research to Develop Acid Rain Reference Materials. ... 81

22. Design and Implementation of a Solid State Filament

Control for Thermal Ionization Mass Spectrometers. ... 82

23. Digital Control Modification for the Varian FR-41

Gaussmeter/Control ler 83

24. Evaluation of a Collimated Ion Collector for Thermal

Ionization Mass Spectrometry 83

25. Standard Reference Materials 86

C. Outputs and Interactions 90

III. ORGANIC ANALYTICAL RESEARCH DIVISION

A. Division Overview 101

B. Selected Technical Accomplishments 114

1. Relationships Between Liquid/Liquid Partitioning and

Retention in Reversed-Phase Liquid Chromatography. ... 114

2. Development of an On-Line Multidimensional HPLC

System for Quantitative Analysis of Individual

Constituents in Complex Samples 116

3. Methods for the Determinaton of Selected Polycyclic

Aromatic Hydrocarbons and Aza-arenes on an Urban

Air Particulate Sample and SRM Certification of

the Sample 120

4. Methods for the Analysis of Polynuclear Aromatic

Hydrocarbons (PAH), Amino-PAH, and Phenols in

Alternate Fuels and Effluents 122

5. Methodology for Certification of a Polychlorinated

Biphenyl (PCB) in Oil SRM 125

6. Identification of Polychlorinated Biphenyl (PCB)

Isomers Using Combined Gas Chromatography/Fourier

Transform Infrared (GC/FT-IR) Spectrometry 128

7. Chemically Modified Electrode Detector for

Halogenated Hydrocarbons 130

ii
Page

8. Electrochemical Oxidation of Croconate Salts and

Their Implication in Semiconductor Behavior and

Electrochromic Displays 133

9. A Multipurpose Cell for Nonaqueous Electrochemistry. . . 136

10. Chronoamperometry at Unshielded and Collarless Disk

Electrodes 140

11. Spectroelectrochemical Research: Surface-Enhanced

Raman Spectroscopy of Pyridine Derivatives 144

12. Measurements of the Optical Rotatory Dispersion of

Internationally Exchanged Quartz Control Plates and

Long Quartz Rotators Between 400 and 650 nm 145

13. Nitrogen-15 NMR Spectroscopy of Neomycin B at High

Field 147

14. Nitrogen-15 NMR and Mass Spectral Characterization of

Doubly 15 N-Labeled 2-Amino Oxazoline Derivatives of

the Pentoses and Hexoses 152

15. Two-Dimensional Proton NMR Spectroscopy of Hydroxyl

Proton Coupled a- and e-Q-Gl ucopyranose 155

16. Comparison of Two Isotope Dilution Definitive Methods

for the Determination of Glucose in Serum and

Evaluation of the American Association for Clinical

Chemistry Candidate Reference Method for Glucose .... 160

17. Comparison of Two Isotope Dilution/Mass Spectrometry

(ID/MS) Methods for the Determination of Total Serum

Cholesterol 162

18. Identification of Components Leached from Implants

Made of Siloxane Polymers and Influence on Prolyl

Hydroxylase Activity 163

19. Combined LC/MS Techniques: Development of an Interface System Compatible with Reversed-Phase LC . . . 164

20. Laser Induced Photodissociation of Ions 166

21. A Method for the Mass Calibration of Photoplates in

Field Desorption Mass Spectrometry and Its Application

to Some Peptides 170

22. Design of a Toxic Chemicals and Carcinogens Handling

Laboratory 173

C. Outputs and Interactions 175

IV. GAS AND PARTICULATE SCIENCE DIVISION

A. Division Overview 187

B. Selected Technical Accomplishments 196

1. Development of a Monte Carlo Electron Trajectory

Simulation 196

2. Empirical Quantitation in Raman Microprobe Analysis. . . 198

3. Automation of the NBS Laser-Raman Microprobe 201

4. Development of Standards for Single Particle Analysis

of Fly Ash 202

5. Development of a Candidate Thin Film Standard Reference

Material 205
Page

6. Intercomparison of NRLXRF Semi-Empirical and NBS

Interelement Correction Methods 207

7. Measurement of the Temperature Dependence of the Ozone

Absorption Cross-Sections in the Ultraviolet 211

8. Measurement of Infrared Intensities of Atmospheric

Species 215

9. Continuation of the Intercomparison of 0 3 , NO, and N02 Measurement Standards by Gas Phase Titration 219

10. Studies of the Photochemistry of Trace Airstream

Impurities in Ozone Generators 221

11. Determination of Trace Gas Concentration by Infrared

Tunable Diode Laser and Fourier Transform Infrared

Spectroscopic Techniques . 224

12. Development of Ambient Nitrous Oxide and Halocarbon

Standards 227

13. Standards for Measuring Toxic Organic Vapors in the

Workplace Atmosphere 229

14. Nitrogen Dioxide Standard for Stationary Source

Emission Measurements 231

15. Intercomparison of Aitken and Cloud Condensation

Nuclei Counters 233

16. Nuclear Environmental Analytical Chemistry 236

17. Development and Evaluation of Personal Particulate

Dosimeters 238

C. Outputs and Interactions 243
I. Center for Analytical Chemistry

Curt W. Reimann, Director

Ranee A. Velapoldi, Deputy Director

A. Center Overview

The Center for Analytical Chemistry develops and maintains the

scientific competences and the experimental facilities necessary to provide

the Nation with the basis for uniform measurements through development of

measurement methodology and provision of measurement services in the field of

analytical chemistry.' Analytical measurements provide a foundation for

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 medica 1 decisions. The Center serves as the National reference laboratory for

assuring the reliability of analytical measurements.

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

laboratory is through the development and issuance of standard reference

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

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

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

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

chemical composition using the most reliable analytical methods available.

Analytical chemistry is increasingly being called upon to provide key

data for highly complex sample types - hazardous chemical and nuclear

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

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

sophisticated, the problem of standardization becomes more challenging both

in terms of the number and the complexity of the proposed standard materials.

As it is not reasonable to contemplate the development of standards to deal

with every measurement problem, the Center's program must be multifaceted,

seeking a variety of avenues to impact the quality of analytical measurements

made in the U.S. In addition to the issuance of standards, the Center exerts

influence through close contacts with various communities by means of workshops, symposia, and participation in standards committees. Through such

contacts, priorities are established for the production of standards and

mechanisms are set in place for their effective use.

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

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

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

three divisions, each focusing upon specific sample types - inorganics,

organics, and gases and particles. Within each division there are several

groups representing separate analytical chemical disciplines, e.g., mass spectrometry and electrochemistry. One group, the Instrumentation Development Group, is attached to the Center office. Each division is responsible

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

appropriate communities.

1
In the following, the major recent activities and technical directions

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

is omitted but will be included in subsequent Annual Reports.

1. Outputs and Interactions

a. Publications

Reimann, C. W. , Velapoldi, R. A., Hagan, L. B., Taylor, J. K., "Technical

Activities 1980, Center for Analytical Chemistry", NBSIR 80-2164

(December 1980).

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

Jugoslavia 16 (2/3), 111-123 (1980).

Kratochvil, B. G. and Taylor, J. K. , "Sampling for Chemical Analysis", Anal.

Chem. 53, 924A-938A (1981).

Demas, J. N., Bowman, W. D., Zalewski, E. F., and Velapoldi, R. A., "Determination of the Quantum Yield of the Ferrioxalate Actinometer with

Electrically Calibrated Radiometers", accepted: J. Phys. Chem.

(October 1981).

Reimann, C. W. and Uriano, G. A., "Letter to the Editor on Lead in Albacore:

Guide to Lead Pollution in Americans", Science , in press.

Reimann, C. W. , "Letter from America", European Spectroscopy News , in press.

b. Tal ks

J. K. Taylor, "Quality Assurance and Traceability", Pullman-Kellogg Company,

Houston, TX, December, 1980.

J. K. Taylor, "Quality Assurance and the National Measurement System", 1981

Measurement Science Conference, Anaheim, CA, January 31, 1981.

C. W. Reimann, "Projections and Directions for Analytical Chemistry",

American Chemical Society Meeting, New York, New York, August 27, 1981.

W. B. Crummett and J. K. Taylor, "Guidelines for Data Acquisition and Data

Quality Evaluation in Environmental Chemistry", IUPAC International

Symposium on Harmonization of Collaborative Studies, Helsinki, Finland.

August 21 , 1981

.

c. Committee Assignments

Lucy B. Hagan

Member, ASTM D-5, Coal and Coke

Member, ASTM D-34, Waste Disposal

Member, CAC Committee on Computer Requirements

2
Curt W. Reimann

Member, Regulatory Affairs Committee, American Chemical Society

John K. Taylor

Member, IS0/TC48, Laboratory Glassware and Related Apparatus

IS0/TC48/SC1 , Volumetric Glassware

IS0/TC146, Air Quality

I SO/TCI 46/SC3 , Ambient Measurements

Chairman, IS0/TC147, Water Quality

Member, I SO/TCI 47/SCI , Terminology

I SO/TCI 47/SC2 , Chemical, Physical, Biochemical Methods of Analysis

I SO/TCI 47/SC6 , Sampling

ANSI TAG, IS0/TC147, Water Quality

ANSI TAG, IS0/TC172, Optical Instruments

ASTM D19, Water

Chairman, ASTM D19.01.07, International Standards

Member, ASTM D19.02, General Specifications

ASTM D19.05, Inorganic Constituents

ASTM D19.07, Sediments

ASTM D22, Atmospheric Analysis

ASTM D22.04, Workplace Atmospheres

Vice Chairman, ASTM D22.05, Calibration-Precision-Accuracy

Member, ASTM D22.07, Precision and Accuracy

ASTM D22.09, USTAG to TC 146

ASTM E34, Occupational Safety and Health

ASTM E36, Criteria for the Evaluation of Testing & Inspection

Laboratory

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 80th Anniversary Celebration Committee

NBS Advisory Committee, State Measurement Needs Survey

Ranee A. Velapoldi

Working Advisor, ASTM, Committee E7 on Nondestructive Testing,

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

Group E7.03.03 on E-270 Glossary Revision

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

E13.06 on Molecular Luminescence

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

Task Group E13.06.02 on Recommended Practices on Molecular

Fluoresence Spectroscopy

3
d. Center Colloquium Series

November 12, 1980 - Typhoon Lee, Carnegie Institution, Washington, D.C.

"Origin of the Chemical Elements: New Clues from High

Precision Mass Spectrometry"

December 10 Glen Gordon, University of Maryland, College Park, MD,

"Receptor Models for Urban Atmospheric Particles"

January 14, 1981 A. R. Findeis, National Science Foundation, "Analytical

Chemistry Research: Options and Opportunities"

February 11 Merle A. Evenson, University of Wisconsin, Madison,

Wisconsin, "Prospectus for Analytical Chemistry in

Clinical Analysis Laboratories"

April 15 - James G. Anderson, Harvard University, "Free Radicals

in the Stratosphere: Measurement and Interpretation"

May 6

“ Tomas Hirschfeld, University of California, Lawrence

Livermore Laboratory, "Hyphenated Methods in Analytical

Chemistry"

May 22 - G. J. Wasserburg, California Institute of Technology,

"New Inferences on the Structure and Evolution of the

Earth", Joint NBS and CAC Colloquium

4
B. Voluntary Standardization and Quality Assurance

1. Voluntary Standardization

Participation of the staff in the voluntary standardization process is

recognized as providing important benefits. It furnishes:

o an important mechanism to transfer technology to the user public;

o a vital means of communication to learn the problems that confront

the analytical community; and,

o a window to the state-of-the-art of analytical measurements as practiced in important applied situations.

Accordingly, standardization activities are an important part of the Center's

external program and may be considered as one side of a coin which may be

called scientific-technical interactions. The other side is, of course, the

attendance at and participation in scientific organizations which provide

direct contact with the science of analytical chemistry as it is developing.

Historically, the Center has a long involvement in standardization

activities. The early staff participated actively in the highly industrially

oriented committees of ASTM. In fact, such association provided the mechanism for much of the SRM development for the metals industry, for example.

Tenures of 10 to 20 years on ASTM committees were not uncommon for such staff

members.

As ASTM has extended its area of interest from a largely industrial

orientation to include a wide variety of measurement problems, a number of new committees have been established. Many of these address problem areas in

which the Center has become concerned, such as the environmental area. Center personnel have become involved in them at the expense of some diminution of effort in the industrial area.

Much of the national standardization activity has international parallelisms. Although several foreign countries' standardization programs are of

long standing and are highly advanced, particularly those of France, Germany,

and the United Kingdom, American standards are often believed to be the best

and/or need to be promoted for international adoption, in the interest of

facilitating U.S. commercial interests. Prestigious analytical chemists,

highly knowledgeable of American standards, can be very influential to this

end. Accordingly, several Center scientists have become very active in

international standardization activities and have assumed positions of

leadership which have proven to be beneficial to U.S. standardization

interests

.

There are many parallels in the area of purely scientific standards.

Center chemists have long been involved in the important activities of

standardizing atomic weights and compiling electrochemical data, in particular. They have not only personally made contributions to the determination

of physical constants that need to be promoted for adoption, but they often

have a keener feeling for the importance of accuracy in chemical measurement

5
than many of their counterparts on the committees. When highly knowledgeable

chemists reinforced by the prestige of NBS are the U.S. representatives on such committees, the interests of U.S. science are well represented. Accordingly, such participation needs to be encouraged and supported.

The present standardization participation of CAC personnel may be

classified in two general categories:

o Active - attendance at meetings; participation in writing standards;

leadership

o Passive - participation by correspondence; review of standards

The statistics are as follows:

o 31 members (approximately 37% of full-time professional staff)

participate in standardization activities

o representation on 109 separate committees, subcommittees, or task

groups

o ASTM participation is the largest

11 ASTM Committees

71 Subgroups

o representation on 12 international committees

One further activity of standardization needs to be mentioned. This is

concerned with participation in collaborative testing of proposed standards.

Sometimes specific technical points need to be investigated by a peer laboratory. The CAC is often exceptionally well qualified to provide such a service.

There is also the need to actively participate in the actual collaborative

tests. A related matter is the provision of test samples for such tests. The

Center's expertise in SRM development and certification knows no peer in this

respect and the furnishing of test samples, as possible, is a major contribution, often eliminating an impossible roadblock.

2. Quality Assurance

The quality assurance tempo has increased considerably during the past

year. A formal quality assurance plan for both the research and applied

analytical measurements programs of the Center has been developed for expected

implementation next year. In addition, assistance has been provided in the

writing of quality assurance plans for the Office of Standard Reference

Materials and for the Office of Environmental Measurements. The Center, of

course, is a major contributor to both of these program areas; hence, it is

important that all of the quality assurance plans be compatible.

The quality assurance plan developed formalizes the measurement practices

developed over the years, as the Center has strived to provide the best

analytical measurements possible, especially for reference material certification. The policy with respect to sampling, analytical methodology, laboratory

6
records, and data review and reporting is described in some detail. It

affirms the importance of maintaining control charts and the present policy

of data verification by use of multiple techniques, multiple operators,

replicate measurements, and the systematic use of SRM's and other reference

materials for quality assessment. The dependence of quality data on planned

experimentation, backed by statistical advice, is emphasized. Copies of the

plan are available on request to others who may wish to consult it with

respect to developing or revising their own quality assurance plans.

As part of the Center's program to assist the technical community by

encouragement of quality assurance and good measurement practices, the first

NBS Precision Measurement Seminar in the chemical area was organized and held

May 7-8, 1981. The seminar, "Quality Assurance of Chemical Measurements" is

a two-day seminar concerned with techniques to improve the precision and

accuracy of analytical measurements such as those needed in the compositional

analysis of materials, process control, and regulatory enforcement. It is

designed for supervisors of analytical laboratories, experienced analytical

chemists, and those responsible for the development and/or supervision of

laboratory quality control programs. The seminar consists of in-depth discussions of the following topics: general aspects of quality assurance; the

role of Standard Reference Materials in quality assurance; statistical

considerations used in the evaluation of data quality; good laboratory

practices for precise and accurate chemical measurements. An additional

feature is small -group discussions of good measurement practices (GMP) for

selective measurement techniques with NBS experts. Each participant elects

to participate in 3 of these, selecting from the following areas: atomic

absorption spectrometry; gas analysis; gas chromatography ; gas chromatographymass spectrometry; general analytical chemistry; ICP spectroscopy; ion

chromatography; isotope dilution mass spectrometry; liquid chromatography;

polarography- voltammetry; neutron activation analysis; spectrophotometry;

statistical concepts; UV-IR organic spectroscopy; standard reference materials

quality assurance program development.

Twenty persons, largely from industry, attended the first seminar. Four

such seminars are scheduled to be held on December 1-2, 1981, May 4-5,

May 6-7, and May 13-14, 1982, respectively.

A series of quality assurance seminars for Center personnel, but also

attended by other staff members of NBS and to some extent from other government agencies, was held during the past year. This lecture series is

designed to inform the Center of quality assurance practices and needs of the

analytical community and also to provide a means to present discussions of

specific techniques by experts in the field. The seminar series will continue

during the coming year. The list of subjects of the previous seminars is

given below.

7
Quality Assurance Seminar Series

Feb. 18, 1981 Robert Belfit, Dow Chemical Company, "Methods and

Standards at the Dow Chemical Company"

March 23, 1981 J. Stuart Hunter, Princeton University, "A Statistical

Look at Calibration Uncertainties"

April 30, 1981 Byron G. Kratochvil, University of Alberta, "Sampling

for Chemical Analysis"

May 26, 1981 Dexter Olsson, Bethlehem Steel Corporation, "Quality

Assurance Practices in the Steel Industry"

John K. Taylor

8
C. Pilot National Environmental Specimen Bank Program

1 . Introduction

Since 1975, the Center for Analytical Chemistry at the National Bureau

of Standards (NBS), in conjunction with the U.S. Environmental Protection

Agency, has been involved in research relating to the establishment of a National Environmental Specimen Bank. The purpose of such a national system

would be (1) to detect changes in the environment, using bioaccumulators as indicators, on a real-time basis (i.e., monitoring), (2) to distinguish such

changes from natural inputs, and (3) to provide a "bank" of samples for

retrospective analyses in future years as analytical techniques improve or as new pollutants are identified. In 1979, a special "clean" laboratory/storage

facility was completed at NBS to initiate a five-year Pilot National Environmental Specimen Bank Program. This pilot program is designed to evaluate the

feasibility of a national program by: (1) developing analytical protocols

for sampling, processing, and storage of four types of environmental samples

(i.e., human liver, mussels, grain/milk, and air filters/ moss/lichen);

(2) evaluating and improving analytical methods for the determination of both

trace element and organic pollutants in biological matrices; (3) evaluating

the feasibility of long-term storage at various conditions; and (4) providing

a "bank" of valid samples for retrospective analyses in future years.

During the past year, several important accomplishments have been

achieved: (1) completion of the first-year human liver sample collection and

evaluation of the liver sampling protocol; (2) improvements in development,

evaluation, and application of a cryogenic homogenization technique for

biological samples; (3) analyses of 36 liver samples for trace elements by

several analytical techniques; (4) development of analytical methodology for

organochlorine pesticides in human liver samples; (5) development of a liquid

chromatographic/amperometric detection method for the determination of

methylmercury in human livers and mussels; (6) development of a neutron

activation analysis procedure for the determination of platinum; and

(7) development of a sample collection and storage protocol for the marine

bivalve sample, mussels.

2. Sample Collection

During the first year, 300 liver samples from three geographical locations were collected using the sampling protocol developed at NBS. During the

remaining years of the pilot study, liver samples will be received at a reduced

rate of approximately 100 per year because of financial /manpower constraints.

At the completion of the first year of human liver collection, the sample

collection protocol and strategy were evaluated with respect to such items

as: initial set-up cost for contractors, sample procurement costs (i.e.,

contractors' cost, protocol materials, and shipping), transport time, time

required for receipt of hepatitis screening results and histological slides,

and suitability of donor selection criteria. Regarding donor selection

criteria, one contractor summarized the total cases available for sampling,

types of cases, number of cases (donors) rejected, and reasons for rejection.

This contractor reported that the major factor for rejection was the time

requirement that the autopsy be performed within 24 hours of death. The

most likely sources of liver samples for this contractor were found to be

9
(1) natural deaths, (2) suicides, and (3) traffic accidents. Legal constraints

prevented the use of any tissue from a probable homicide case in that particular state. However, homicide cases provided a major source of samples for

a contractor in another state where such legal restrictions do not exist.

Information and experience as described above for the liver sampling protocol

will be used to evaluate the feasibility (i.e., costs, legal aspects, sampling

difficulties, etc.) of initiating a National Environmental Specimen Bank

Program.

3. Sample Preparation and Analysis

Specimen banking, as part of biological monitoring efforts, includes the

important task of developing and establishing a credible analytical measurement system. Each type of specimen considered for monitoring and banking

places certain demands on a measurement system; hence, the measurement capabilities should be developed in conjunction with the design and implementation

of a banking program.

An important part of the first phase of the pilot program, i.e., the

banking of human liver specimens, has been the development of a state-of-theart protocol for the chemical analysis of these specimens. Research efforts

in CAC have resulted in the currently applied analytical protocol which

covers three major areas: (1) the preparation of the sample for analysis,

i.e., subsampling to obtain a representative analytical test portion;

(2) the implementation of a comprehensive inorganic analytical scheme, which

is suitable to provide credible results for all aspects of specimen banking

studied in the pilot program; and (3) the evaluation of methods and procedures

for selected organic pollutants.

The pilot program and possibly any biomonitoring and banking program has

to operate under certain constraints regarding the amount of material available from which the desired set of data must be obtained. The analytical

increment must be representative of the sample and be homogeneous for subsampling of the analytical test portions on which the results are based.

Sample preparation research has focused on the expansion of the cryogenic

brittle fracture technique to sample sizes up to 250 g. To allow a one-step,

contamination-free homogenization of the analytical increment, i.e., half a left lobe of a human liver, a Teflon disk mill has been designed at NBS, and

its performance evaluated. (See page 51 for detailed discussion of this

evaluation.) Ingamells' sampling constant, K

s

, has been determined by

radiotracer experiments, showing that test portions of one gram of fresh

liver provide a sampling uncertainty of less than one percent. More homogeneous samples allow detection of smaller changes in concentrations during

the storage evaluation and/or the use of smaller test portions which allows

multiple analyses of the same sample.

Research in trace element analysis has resulted in the improvement of

existing methods and the development of new procedures emphasizing higher

sensitivity for many of the elements. The result is an analytical protocol

which includes the determination of most of the first-priority elements

proposed by the 1978 International Workshop on Monitoring Environmental

Materials and Specimen Banking [1]. Other elements regarded as possible

10
pollutants have been added to the protocol, as well as biological major

elements and trace elements, which can provide information about the "normal"

state of the specimen. The analytical protocol includes about 40 elements,

which are determined by the following methods: atomic absorption spectrometry (AAS), isotope dilution mass spectrometry (ID/MS), neutron activation

analysis (NAA), and voltammetry (VOLT). The specific elements determined and

the analytical techniques employed for each measurement are summarized in

figure 1. The analytical protocol was applied to the analysis of 36 liver

specimens collected during the first year of the pilot program. The quality

assurance procedures include parallel determinations of Standard Reference

Materials, determination of several elements by more than one technique, and use of high precision, high accuracy techniques, e.g., ID/MS.

HMO AAS

Be

Al Mn Ni Cu As Se Cd

Figure 1. Analytical techniques used for the

determination of trace elements in

human liver samples.

11
AAS, NAA, and VOLT provided precise and accurate results for the majority

of the elements of interest. The relative standard deviation of repetitive

analyses using these methods varied between 1 and 7 percent with the exception of the determination of A1 , Cd, and Pb, where the precision ranged from

10 to 15 percent. ID/MS provided accurate and precise data (^1 percent

error) on Cu, T1 , and Pb. For the evaluation of storage conditions, a relative standard deviation of 5 percent or less is essential to detect changes

smaller than 10 percent. Some important elements, e.g., Be and Mi, are at or below the detection limits of the currently applied analytical procedures;

research will be directed to develop the needed methodology for these elements.

Determination of elements by more than one method illustrates the high degree

of accuracy achieved with the applied protocol. Data on A1 , Cl, K, Mn, and

Se agree among the methods. The results of the multielement determinations

of the 36 liver specimens are shown in figure 2. The concentrations agree

with the ranges reported previously [2,3]. Of particular interest is the

very narrow concentration spread of some of the essential trace elements,

especially selenium, when compared to the widely scattered concentrations of

non-essential or pollutant elements. These results will contribute significantly to the existing trace element data base for human livers. For the

purpose of biomonitoring and specimen banking, the data obtained during the

first phase of the pilot program indicate that the analysis of individual

specimens is preferable to the analysis of a large composite of several

livers. Results based on individual specimens may provide a more realistic

picture of pollutant levels, since high levels in single individuals may be

uncharacteristic for the sampled population because of specific circumstances.

Figure 2. Elemental concentrations (yg/g) determined in

36 liver specimens.

12
Analytical methodology for the determination of organochlorine pesticides

has been developed and applied to several liver samples. The major chlorinated compound in each sample was identified as p,p'-DDE (a metabolite of

DDT) by gas chromatography (GC) and mass spectrometry (MS). This compound

was determined in three different samples using both GC and GC/MS. The

results of these analyses are summarized in Table T. Table 1 also includes

the result of an interlaboratory sample split with the U.S. EPA Health

Effects Research Laboratory. Trace quantities (^1 0-1 00 times less than p,p'-

DDE) of hexachlorobenzene, 3-hexachlorocyclohexane, oxychlordane, hepachlor

epoxide, tvans-wonochlor, and dieldrin have also been found. This methodology will be applied for the analysis of ^30 liver samples during the coming

year.

Table 1. Determination of p,p'-DDE in Human Livers,

(pg/g wet weight)

Sample I.D. GC

a GC/MS GC (EPA)

d

B0025 A. 0.72 + 0.04 0.77?

B. 0.75 + 0.04 0.81°

M0136 0.23 + 0.01 0. 23

c 0.26

S0129 0.35 + 0.01

Uncertainty based on four determinations, reported as one standard deviation from the mean. ^Single determinations.

cMean of two determinations, range of ±7 percent.

^Single determination.

Recent research on the determination of additional pollutants has

resulted in the development of an NAA procedure for the determination of

platinum and a liquid chromatographic procedure with amperometric detection

for the determination of methyl mercury. The NAA procedure via radiochemical

separation techniques is capable of measuring platinum at naturally occurring

levels of 5 x 10" 11 g/g in human livers, thus providing the first baseline

data for this element in human liver. The procedure for the determination of

platinum is described in detail in another section of this report. Of the

various forms of mercury, which has long been recognized as an important

environmental pollutant, the alkyl mercury cations have been found to be the

most toxic. Thus, the determination of the levels of various organomercury

species in biological tissues is important in addition to the measurement of

the total mercury concentration. As an alternative to time-consuming gas

chromatographic methods which involve chemical derivatization for the determination of methylmercury in tissue samples, a simplified procedure based on liquid chromatography (LC) with amperometric detection has been developed.

This method consists of (1) acidification to liberate the organomercury

cations bound to the proteins, (2) complexation with a mercaptan,

(3) followed by LC separation of methyl-, ethyl-, and inorganic mercury with

amperometric detection to achieve the necessary selectivity. Research is in

progress to improve the recovery of the various mercury species, particularly

the inorganic mercury(II), to achieve simultaneous determination of all of

the expected forms of mercury in tissue.

13
4. Mussel Protocols

The second type of environmental sample for incorporation into the pilot

program will be marine mussels ( Mytilus edulis)

.

A sampling/storage protocol

has been developed in cooperation with investigators familiar with mussel

collection, i.e., the U.S. EPA "Mussel Watch" Program. The cryogenic homogenization technique has also been evaluated for use with mussel samples and

will be modified to accommodate larger sample sizes.

The development of sampling, processing, and storage protocols for the

second specimen type, mussels, offered somewhat different problems and

required the addressing of different questions than those for human livers,

e.g., how many mussels constitute a sample, what is the variability between

"pools" of 50-100 mussels from the same site, and should the mussels be

stored in the shell, shucked, or as homogenates? The sampling and storage

evaluation strategies were designed, in cooperation with NBS statisticians,

to address these questions. Initially, sample collection will be directed at one site to determine the expected "variabil ity" of "pools" of mussels.

These data will then be used to evaluate the probability of detecting changes

during the storage of mussel samples. Several sites (both polluted and

unpolluted) will be evaluated in a similar manner in the future. Currently,

we are developing analytical methods for the measurement of both trace

elements and trace organics (i.e., organochlorine pesticides and polycyclic

aromatic hydrocarbons) in these "pooled" mussel samples.

5. Interactions with National and International Programs

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

Republic of Germany (FRG) have been pursuing collaborative research in the area of environmental specimen banking as part of a bilateral agreement on the environment. Participants in the specimen banking programs of the U.S.

and the FRG meet annually to exchange information and experience. As a result of these meetings, for example, participants in the FRG program

provided NBS with their methodology for extraction/isolation of organochlorine

pesticides from liver samples. This methodology has been incorporated into

the NBS program. Information concerning the formatting of data/sample

information has been exchanged to make the results of the two programs

intercomparable. The FRG program is currently investigating the use of

cryogenic homogenization patterned after the work at NBS. These are several areas where the U.S. and FRG programs have exchanged information/experience

for the benefit of both programs. In May 1981, NBS scientists attended the

annual meeting in Julich, Germany, and reported the research activities of

the pilot program. This meeting was held in conjunction with the dedication

of the Pilot Environmental Specimen Bank facility for the FRG. At this

meeting, several sample splits were arranged between the two programs (i.e.,

liver samples from both programs and a human blood reference material from

the FRG program). An additional interlaboratory comparison for the determination of methylmercury was planned for early 1982.

The U.S., through the NBS/EPA Pilot National Environmental Specimen Bank

Program, is looked upon as a leader in specimen bank research. NBS representatives have been invited to prepare two position papers for the "International

Workshop on Environmental Specimen Banking and Monitoring as Related to

Banking" to be held in May 1982 in Saarbrucken, Germany.

14
As a result of NBS specimen banking activities with human livers, NBS

researchers have also been invited to participate in a select panel concerning

"Collection and Preservation of Samples" and "Analytical Methodology" for a follow-up meeting to the "Workshop on Research Needed to Improve Data on Mineral Content of Human Tissue," which was sponsored by the American

Institute of Nutrition and the National Science Foundation. The goal of this

upcoming workshop, entitled "Protocol s--Mineral /Element Analysis of Human

Tissues," is to prepare specific protocols for sample collection, preservation, and analyses of human tissues.

References

[1] N.-P. Leupke, editor. Monitoring Environmental Materials and

Specimen Banking , Martinus Nyhoff, The Hague-Boston-London (1979).

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

Composition of Human Tissue and Body Fluids , Verlag Chemie,

Weinheim-New York (1978).

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

National Environmental Specimen Bank - Phase I, EPA Research

Report , in press.

S. A. Wise, Project Manager; K. A. Fitzpatrick, S. H. Harrison, R. L. Zeisler

The following members of CAC have participated in providing analytical

research and data for the program:

S. N. Chesler, R. R. Greenberg, L. R. Hilpert, W. F. Kline, B. Kratochvil,

J. K. Langland, W. A. MacCrehan, E. J. Maienthal , T. J. Murphy, P. A. Pella,

L. P. Powell, T. C. Rains, T. A. Rush, R. L. Watters.
D. Service Analysis

An accepted and important function of the Center for Analytical Chemistry

is the provision of consultation, advice, and accurate chemical analyses on the diverse materials that are utilized in the research programs at NBS.

This service is also available to other federal, state, and local government

agencies on request. In addition, in special instances where CAC has a unique analytical capability, this service is likewise extended to the

private sector.

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

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

analyses. At the same time, an extensive effort is made to provide this

function with a minimum of disruption to ongoing programs within the Center.

The turnaround time for the more straightforward analyses typically ranges

from several days to about two weeks. All work is performed on a cost

reimbursable basis. Within NBS, funds are transferred by means of an interdivision work order; outside work is handled on a purchase order.

In FY 81, some 134 service analyses were performed within the Center at

a cost of $181 K. These were distributed among the three types of customers

as follows: NBS, 51 requests ($38,000); other government agencies, 20

requests ($44,800); and private industry, 63 requests ($97,800). More than

half of the industry requests were in two areas, recalibration of glass

transmittance standards and recertification of gas mixtures.

Of the service analyses carried out in FY 81, two stand out as good

examples of the kind of analytical services performed and the value that can

be derived from them. One was concerned with a problem of a decrease in the

temperature coefficient in platinum resistance thermometers. The other

analysis involved a new type of superconductor material and required the

development of a new analytical method.

An important program within the Temperature and Pressure Measurements

and Standards Division of the Center for Absolute Physical Quantities involves

the development of high temperature platinum resistance thermometers suitable

for use as interpolating instruments to the gold point on a revised international practical temperature scale. Many of the thermometers made during

the past year have undergone an unexpected decrease in temperature coefficient

upon prolonged exposure to high temperature (1100 °C). In an effort to trace

potential causes for this decrease, CAC was requested to analyze some of the

thermometer components.

The first analyses, by arc emission spectrometry, of samples of platinum

taken from the resistance elements of two thermometers revealed the presence

of copper, an unexpected contaminant, at about the 200 ppm level. Subsequently, samples of all platinum materials were analyzed similarly, and

samples of all fused silica materials used in thermometer construction were analyzed by neutron activation analysis. Some of the less pure platinum

used for thermometer leads and general structures was found to contain

appreciable amounts of copper; the fused silica, considered to be an unlikely

source of copper contamination, was found to be essentially copper free. As

a result of these analyses, a higher grade platinum is being substituted for

16
the lead and ground structures and all external processing equipment is being

examined for possible sources of copper contamination.

The other service analysis, performed for the Ceramics, Glass, and Solid

State Science Division, entailed the measurement of the chloride concentrations in a series of specially prepared cadmium sulfide samples. Interest in

cadmium sulfide, doped with chloride, is increasing because this material

exhibits potentially superconductor-like properties at temperatures that are

well above the cryogenic level. To provide the desired measurements, a procedure was developed in which the samples were dissolved in alkaline

hydrogen peroxide and analyzed by ion chromatography. It was also possible

to determine sulfur in the same samples because the dissolution procedure

quantitatively converts sulfide to sulfate, an anion that is easily measureable by ion chromatography. The chloride and sulfate data were subsequently

used to calculate and demonstrate mass balance. A summary of this work has

been submitted by W. F. Koch and J. W. Stolz for publication in Analytical

Chemistry.

R. W. Burke

17
E. Instrument Development Group (proposed name: New Analytical Techniques

Group)

1. Group Overview

The main objective of the group is to develop new approaches to performing

accurate chemical analyses. The focal point continues to be the use of laser

radiation in two ways. First, the inherent high power, time and space

coherence, and spectral purity of laser radiation are attributes that lead to

highly accurate spectroscopic analytical methods. Second, laser radiation is

proving to be a powerful diagnostic tool for studying plasmas of analytical

significance (e.g., the solution aspirated flame used in atomic absorption,

fluorescence, or emission).

Major progress has been made this past year in the areas of IR diode

laser instrumentation development and two color laser enhanced ionization

(LEI) in flames. In the first area, the IR laser diode system was completely

redesigned and was put under computer control. It shows greatly improved

reliability and provides compensation for some instabilities observed in the

operation of the diode itself. In the second area, two-color LEI in flames,

we have acquired a Nd-YAG laser to act as a pump for one dye laser head and

borrowed a second dye laser. This system allows the population of high

atomic energy levels that were unreachable with a single dye laser. With the

two wavelength system, elements have been analyzed with high selectivity and

with detection limits at the 10-100 pg/mL level, both of which imply a highly

accurate, trace analytical, spectroscopic technique. The reliability of the

system is excellent and there appears to be no impediment to the use of this

laser in routine analytical systems.

The first major paper on the LEI signal collection mechanism will soon

be published in the Journal of Physical Chemistry. This paper incorporates

much of the imaging data discussed in last years annual report. In research

this year, we have observed a significant bleaching of ground state atoms in

the laser beam. A mapping in two dimensions of the depleted area has been

carried out as a function of time so as to make an interesting, time-lapsed

"movie" of the phenomenon. A number of properties of flames can be studied

by these techniques (diffusion, ion-electron recombination, and chemical

reaction rates).

Collaboration with scientists in the other divisions is proceeding and

several of the projects that are being worked on jointly are reported in

other sections of this report. These include the organic molecular ion

fragmentation studies in Division 552, the N 2 0 SRM gas analysis in Division

553, and the mass spectroscopy source diagnostic studies and ion beam

fluorescence studies in Division 551.

Implementation of the NBS storeroom microcomputer system is proceeding

well. The software is becoming powerful with convenient file managers,

editors and applications languages becoming available at an ever increasing

rate for use with the operating system called CP/M. These systems must be

rated significantly more powerful per-dol lar-invested than even the most

economical minicomputer or desk calculator on the market. On an absolute

18
scale of computing power, the system ranks near the middle of the minicomputer market.

Our general plans in the laser enhanced ionization area are to study the

signal collection processes over short time intervals and to attempt to model

mathematically the dynamic process of ion/electron transport over these time

frames. Our collaborative efforts within the Center will continue to focus on multiphoton atomic-ionization and organic molecular fragmentation processes.

Considerable attention has been placed upon new atom reservoirs. A new competence building program involving sample transport mechanisms has been

proposed. Sample transport concerns the study of fundamental processes

involved in removing analyte atoms from the sample and putting them into the

form best suited for quantitative analysis (see section on new competence

proposals). Collaboration on flame diagnostic studies outside of the Center

will continue, but at a reduced pace because of insufficient staffing.

Finally, of great importance, is our plan to characterize the LEI two-color

excitation spectrum of the elements and to analyze an increasing number of

materials to confirm our expectations that the LEI in flames is a viable

analytical method for most of the elements.

James R. DeVoe

2. Selected Technical Accomplishments

a. High Reproducibility Analysis with the Infrared Diode Laser

The narrow linewidth and moderately high intensity of infrared semiconductor diode lasers (of the Pb, Sn Te type) provide an ideal radiation

1 “ X X source for IR spectrophotometric analysis. Moreover, of the possible techniques that could be used (e.g., Fourier transform infrared spectroscopy,

optoacoustic techniques), the laser diode system shows outstanding promise

for making highly accurate and reproducible measurements. If high

reproducibility can be realized, then analysis of Standard Reference

Materials (SRM's) using comparative methods and the measurement of isotope

ratios of, for example, carbon or nitrogen in small molecular gaseous

species, becomes feasible and it also may be able to compete with classical mass spectrometric techniques. In addition, the narrow linewidth removes

much of the interference due to line overlap from other species so that the

measurement should be accurate. To obtain the necessary reproducibility,

major changes were made to the diode system. These changes were a redesign

of the optics and the entire electronic detection system.

Superimposed sinusoidal ripples in the spectral baseline coming from

combined orders of various etalons unintentionally introduced via the lens

system were observed. The optical lenses of the system were replaced by

off-axis parabolic mirrors (see figure 3) which substantially reduced this

instability.

Another source of optical instability results from a very small change

in the geometric position of the laser beam with time. Since it is desirable

to use small surface radiation detectors to minimize the magnitude of background signal and its accompanying noise, this positional instability moves

19
Q.<o on

co

k.(0 o.

COX<O

II Q.<o

20

Figure

3.

Diode

laser

optical

system.
the IR beam on the detector surface, thereby causing intensity fluctuations.

This spatial instability comes from two sources. One is from inconsistencies

in the solid state properties of the diode, thereby causing a specific lasing

mode to move to a position of optimal power output on the face of the diode

crystal. The second source is dimensional instability of the optical components due to temperature fluctuations and building vibration. The former

instability is under study. Its time response is slow so that adequate

computer control may be able to reduce this effect. The latter instability

was improved by installation of a thermal curtain and ruggedized supports for

the optical components.

The above instabilities, coupled with diode dependent frequency and

intensity fluctuations in the laser radiation plus background fluctuations,

required a change in the philosophy of the entire operation of the system. A

variety of modes of operation were desired and this is best done by computer.

A storeroom microprocessor system was assembled (see description in Section

E.2.e of this report). The computer sends an analog signal to the current

amplifier which sets the frequency (wavelength) of the diode. The infrared

detector's analog signal is digitized and stored by the computer. A number

of system control routines have already been written and more are required.

To date, a spectrum averager mode which sweeps at the maximum rate of 160 ys

per wavelength unit has been completed. A jump scanning mode is also in

operation including graphical display of data on a CRT.

In order to discriminate from background as well as to remove certain

noise contributions, wavelength modulation is used in several operational

modes. In addition to the sequential wavelength scanning and averaging,

modulation is used to maintain frequency stability of the laser. Part of the

beam is extracted through an absorption cell containing pure analyte gas.

The wavelength is then modulated using an external signal generator at kHz

frequencies. The output of the detector is locked to this frequency using

the usual first derivative technique and any difference signal is fed to the

current amplifier - control circuit. The primary gas sample system's

detector goes to a similar lock-in and the second derivative spectrum is

collected by the computer (see schematic, figure 4). Using this procedure

and repeatedly measuring the second derivative output, a stability of 0.08

percent relative standard deviation (RSD) of the average of 500 measurements

has been achieved. Long term stability over several hours decreased to about

0.1 percent RSD. In summary, the above improvements have provided at least

a factor of ten increase in reproducibility. This technique has been used

to measure N 2 0 samples (see report in Section IV. B.12).

It is believed that the stability of the system can be further improved

by using a detector with a greater signal -to-noise ratio. However, the

limiting factor on stability now appears to be in gas handling and pressure

measurements. These operations will be put under computer control in the

near future.

R. L. Sams, J. W. Elkins (Division 553)

L

21
To

Gas

Handling

System

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4.

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laser.
b. LEI Ion Collection Dynamics

When electrons and ions are produced in a flame by laser enhanced

ionization, 10~ 6 - lCf 4s are required to transport the charged species

through the flame by an electric field for collection on an electrode. For

this reason, a steady state condition for the extraction of LEI-generated

electrons and ions only exists for laser excitation lasting »10“ 6 s. Transient behavior showing a two-component (bimodal) current pulse with a 10" 6 s flash! amp-pumped dye laser was the original inspiration for the postdoctoral proposal [1]. Since then, the phenomenon has been observed with

better time resolution using ^10~ 8 s laser pulses [2,3]. It is suspected that

the bimodal signal observed with <10" 6 s excitation is due to a very fast

signal corresponding to electron movement which tracks the laser intensity,

and a slower pulse which results from ion migration. In the continuous wave

(CW) regime, a signal that is a combination of both electrons and ions is

observed.

As described in previous panel reports, the addition of an easily

ionizable species to the flame produces ions that migrate to the cathode,

thereby causing a sheathing or passivation of the electric field produced by

the signal collecting electrodes. With a water cooled cathode in the flame

above the burner base which is the anode, significantly different behavior is

observed between the use of a pulsed laser and a CW laser (figure 5). A

simplified explanation relates to the experimental results described in the

first paragraph above. With the pulsed laser, the detection circuit is gated

to measure only the electron signal that occurs simultaneously with the

laser pulse and a signal will be observed only when the laser irradiates the

sheath region. No signal is observed if the pulsed laser is directed in the

field free region (outside the sheath) because the electrons penetrate the

sheath well after the measurement period. With CW laser irradiation on the

other hand, a reasonably constant signal is observed independent of field and

thus laser beam position. This is a consequence of "steady state" conditions

in which electron-ion transit times are inconsequential, i.e., charges

carried by large fields or at flame flow velocities are indistinguishable

with the chopping frequencies used. This implies that matrix interferences

of easily ionizable species in the flame can be significantly reduced by

using CW lasers and the geometry with the cathode immersed in the flame.

Detection limits using the CW laser system were measured for potassium

and rubidium. The limits of detection (LOD) are defined as the species

concentration in water solution which gives a signal amplitude three times

that of the blank noise level. A krypton ion laser was used to pump oxazine

725 dye. The limit of detection for potassium at an excitation wavelength of

776.5 nm was 100 pg/mL and the LOD for rubidium at 780 nm excitation was

90 pg/mL. A calibration curve was linear over four orders of magnitude. The

insensitivity of this method to matrix effects caused by samples with easily

ionizable elements was demonstrated by determining Rb in pine needles (SRM No.

1575) using aqueous solutions for calibration. A measured concentration of

11.1 yg/g ±0.5 yg/g agreed well with the reported amount of 11.6 yg/g ± 0.1 yg/g.

(The value ±0.5 yg/g is the standard deviation of a single determination

excluding reproducibility for sample weighing and solution preparation. The

value ±0.1 yg/g is that appearing on the certificate of analysis.)

23
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References

[1] Havrilla, G. J. NAS/NRC Postdoctoral Research Proposal (1980).

[2] Mallard, W. G.; Smyth, K. C. Combustion and Flame, in press (1981).

[3] Turk, G. C. Anal. Chem. 53: 1187-1190; 1981.

G. J. Havrilla, J. C. Travis

c. Stepwise Excitation Laser Enhanced Ionization Spectrometry

Laser stepwise excitation, utilizing two electronic transitions connected

by a common intermediate level, is an effective technique for populating high

energy electronic levels in an atom. Such excitation can be very useful for

laser enhanced ionization (LEI) spectrometry, since sensitivity is often

limited by the ability to populate an excited state which is close enough to

the ionization limit to be efficiently ionized. The feasibility of stepwise

LEI was demonstrated in 1979 [1] using a dual N 2 laser-pumped dye laser, but

relatively poor limits of detection were achieved. An improved stepwise LEI

system has been assembled for the present work, based on dye lasers pumped by

a Nd:YAG laser.

Detection limits for stepwise LEI using the present system are given in

Table 2, along with the single photon detection limits achieved with the Nd:YAG

based system and with the flashlamp pumped dye laser system. The detection

limit is defined as the concentration which gives a signal amplitude three

times that of the blank noise level. In each case studied, the stepwise LEI

detection limits are major improvements over previous LEI results and are comparable to or better than those which can be achieved by other methods of

analysis. For the first time, sensitive LEI detection of elements with ionization potentials >9 eV is possible. A complete listing of the best values of

all LEI detection limits measured to date is given in the periodic table,

figure 6. Comparison of the stepwise excitation results (Table 2) to those

measured using single photon Nd:YAG excitation shows the signal enhancement

obtained by using the second excitation step. In addition to improved sensitivity, the added dimension of a second excitation wavelength improves the

selectivity of the method.

Table 2. LEI Detection Limits (ng/mL).

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K>

11

5.1 Na 285.3 0.05

K> 3-

O) 37

4.2 Rb 572.4 1

OIK> 73 m Um 0d

?H

Ph

CO 26 1l

Figure

6.

The

best

values

of

LEI

detection

limits

measured

to

date,

including

both

single-photon

and

stepwise

excitation

results.

Data

given

for

each

element

as

follows:

upper

left

hand

corner

atomic

number;

upper

right

hand

corner —

ionization

potential

in

eV;

mid-center —

excitation

wavelength(s)

in

nm

(2

wavelengths

given

when

stepwise

excitation

is

used);

lower-center —

the

limit

of

detection

in

ng/mL.
Several Standard Reference Materials were used to study the performance

of stepwise excitation LEI in "real sample" analyses. All samples were dissolved (1 g/100 mL) by wet-ashing using NBS purified acids. The results,

given in Table 3, show agreement between the stepwise LEI results and the

certified values. The determination of tin in SRM 396 (Copper Benchmark III)

is a difficult measurement. Figure 7 shows the LEI signal measured for this

sample while scanning the second excitation wavelength over the Sn line at

597.0 nm with the first step LEI transition fixed at the 284.0 nm Sn line.

The concentration of the Sn in the dissolved sample was 6.7 ng/mL. The determination is made possible by the low detection limit for Sn and the absence

of any significant spectral background interferences.

Table 3. LEI Analysis of Standard Reference Materials

SRM 396

(Unalloyed Copper)

LEI Result

9 Certified Valueb

Ni 4.3 + 0.2 yg/g 4.2 ± 0.1 yg/g

Sn 0.67 + 0.05 yg/g 0.8 ± 0.3 yg/g

SRM 362

(Low Alloy Steel

Sn 0.0156 + 0.0008 Wt. % 0.016 ± 0.001 Wt.

SRM 363

(Low Alloy Steel

Pb 0.0022 + 0.0001 Wt. % 0.0022 ± 0.0001 Wt

Sn 0.107 + 0.001 Wt. % 0.104 ± 0.005 Wt.

a The imprecision quoted is ± one standard deviation, as determined from 10

replicates (not including sample weighing and solution preparation).

Uncertainty as stated on the certificate of analysis.

Continued study and development of the technique is planned in a number of

areas. In many cases, the sensitivity which is now possible exceeds that for

which the present burner system, developed for atomic absorption, was intended,

and many of the detection limits reported in Table 2 are limited by contamination and memory effects. An improved atom reservoir is needed. There remain a number of fundamental areas which require study in order to improve further the

limits of detection and selectivity of LEI. Those which we hope to study in

the near future are the signal collection mechanism for pulsed lasers, and the

spectral background signals which have been observed, but are not fully understood. In addition, much will be learned by continued SRM analysis using LEI.

Reference

[1] Turk, G. C.; Mallard, W. G.; Schenck, P. K. ; Smyth, K. C. Anal.

Chem. 51: 2408-2410; 1979.

G. C. Turk

27
8 rO

(A

m

— 4

111

>

I-

<

111

OC 2

TIN IN UNALLOYED COPPER

1 1 1 1 i 1

596.40 596.55 596.70 596.85 597.00 597.15 597.30 597.45 597.6<

WAVELENGTH (nm)

Figure 7. Second step Sn transition at 597.028 nm in unalloyed copper

SRM 396 with first step wavelength fixed at 283.999 nm. Sn

concentration in solution is 6.7 ng/mL.

28
d. Spatially- and Temporally-Resolved Studies of Laser-Perturbed Atom

Populations in an Analytical Flame

During the course of the studies previously reported concerning the

collection of ions in flames [1], it was noted that the efficiency of the CW

laser enhanced ionization (LEI) process is sufficiently high to significantly

(>50%) deplete the original free Na atom concentration in the laser-irradiated

volume of the H 2 /air flame. Because of the relative slowness of the diffusion

and recombination processes by which this atom-depleted "hole" should return

to equilibrium with the surrounding environment, measurable atom depletion

persists for several cm above the position of the perturbing laser beam,

e. g., ("down-stream" in the ^10 m/s flame gas flow).

The optical system shown in figure 8 was devised in collaboration with

Dr. P. K. Schenck (Chemical Stability and Corrosion Division) to study the

spatial and temporal evolution of the "hole" formed by Na atom depletion. A

beam splitter (BS) is used to generate a small (<10%) portion of the irradiating laser beam for use as a "probe" beam in spatially resolved absorption

experiments. The probe beam is optically isolated with a quarter wave plate

(QWP), monitored for laser intensity with a photodiode (PD), and directed by

mirrors (M) through a lens (L) and refractor plates (S

v

, S^) into the flame

(B). The refractor plates are rotated under stepper motor control to shift

the beam horizontally (S|_|) and vertically (S v

), providing a Mmm x 4mm

raster for spatially resolved absorption. After passing through the flame, a portion of the probe beam is directed onto a photomultiplier (PM) through a lens and optical filter (F). The perturbing, or "pump" beam may be modulated

or pulsed with an acousto-optic modulator (A0M)/aperture (A) combination

before being focused into the flame.

As the pump beam is turned on and off by the AOM (at M kHz), the

transmission of the probe beam is modulated by the periodic atom depletion

via an optical absorption process. Lock-in detection of the PM signal

coupled with rastering of the probe beam is thus used to generate a contour

plot such as shown in figure 9. The contours are linearly spaced at

1 percent increments in transmitted beam intensity. Contours for >10 percent

are omitted because of their density near the pump beam position. The flamelike appearance of figure 9 results from the equilibrium production of ions

at (0.0, 0.0), the steady upward flow of the flame gases, the diffusion of

atoms, and the recombination of electrons and ions.

A less complex picture is obtained by pulsing the pump laser for 20 ys—

a time comparable to the transit time of an atom across the beam--and plotting

the contour map at 5 ys intervals after the laser pulse. This is done by

averaging the PM signal in a 5 ys/channel signal averager at each raster

point. A 12-frame subset of the 40-frame "movie" thus obtained is shown in

figure 10. The displacement of the hole with time is a ready measure of the

burnt gas velocity [2]. Diffusion coefficients and recombination times are currently being extracted by fitting the holes to theoretical functions.

29
OPTICAL

LA

YOU

T

30

Figure

8.

Optical

schematic

of

raster-scan

probe

of

laser

atom

depletion.

See

text

for

symbol

definitions.
Vertical

Displacement

(m

-Figure 9. Contour plot of steady state Na atom depletion resulting from

continuous laser ionization. Scales are relative to the pump beam

position which is 9.5 mm above the burner head. Contours are 1%

increments in transmitted light intensity, with an upper limit of

10% to avoid contour bunching. Blank spot in the region 0. _< y £ 0.6,

-0.2 £ x £

+0.2 mm is an artifact of the 10% upper limit.

31
Figure 10. Time-resolved non-linear contour plots of Na atom depletion at

10 ys intervals measured from the beginning of the 20 ys laser

pulse. Contours are 1% increments in transmitted light intensity

up to a maximum of 15%. Blank region in the center of the

15-35 ys frames is an artifact of the 15% upper limit. 5 ys

frame marks pump laser position and tick marks represent 0.2 mm increments in both vertical and horizontal axes.

32
The raster-probe technique with time resolved detection could be used to

study transient atomic excesses as well as depletions. We hope to conduct

such a study using UV laser pulses to photo-dissociate refractory oxides in

the flame and map the history of the resultant metal atoms.

References

[1] Schenck, P. K. ; Travis, J. C.; Turk, G. C.; O'Haver, T. C. "Collection of Ions Produced by Continuous Wave Laser-Enhanced

Ionization in a Hydrogen/Air Flame", J. Phys. Chem. 85: 2547;

1981.

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

"Laser Enhanced Ionization Flame Velocimeter", in internal review.

J. C. Travis , G. C. Turk

e. The Use of Microcomputers in the Center for Analytical Chemistry

More than two years have passed since components of microcomputers have

been stocked in the NBS storeroom. Once each month a committee made up of

knowledgeable users reviews the components that are available and recommends

renewal or replacement with totally new or updated ones. The selection of

the S-100 bus which is now the IEEE standard 696, along with software based

upon the CP/M operating system proved to be a good one, because literally

hundreds of hardware components and software packages are available for this

system.

There are over 100 microcomputers at NBS that have been assembled from

storeroom components. The following systems have been installed in the

Center for Analytical Chemistry (Division in parenthesis): a) High Accuracy

Spectrophotometer (551); b) Automatic Gas Handling (3) (553); c) Laser (LEI)

(2) (550); d) Laser ( I R) (550) (see section F-l,a above); e) Low Background

Counting (2) (553); f) Electrochemistry (552); g) Software Development (3)

(550), and h) Emission Spectrograph (551).

The following are systems now under development: a) Gas ChromatographyMass Spectrometer (552); b) High Accuracy Spectroradiometer (552); c) Laser

Wavelength Meter (550), and d) Carbon-14 Detecting System (553).

A major advantage to this approach is the ability to upgrade the computer

by purchasing new components that simply plug into the power-supplied main

chassis. For example, our early microcomputers used Intel 8080 microprocessor

chips with a clock rate of 2 Mhz with 16-48K bytes of RAM memory and 5 1/4

inch single-density floppy disk drives. The costs for a system began at $1500

and as capability increased, the cost increased to about $3000. The microcomputers which are presently in use contain a Zilog Z8QA microprocessor with

4 Mhz clock, 64K bytes of RAM, double density floppy disks and a variety of

other peripherals which include: a) A-D and D-A converters; b) Real time and

time of year clocks; c) Telephone modems; d) Hardware floating point processors; e) IEEE 488 interfaces; f) CRT terminals; gl Printers; h) Parallel and

serial 1/0 controllers; i) Interrupt controllers, and j) CRT and plotter

graphics.

33
The software available for these microcomputers includes the following:

a) CP/M disk operating system; b) Basic interpreter and compiler; c) FORTRAN;

d) PASCAL; e) Macroassembler; f) CALCOMP-like graphics library for FORTRAN;

g) Word processor, and h) Hardware floating point FORTRAN and BASIC library.

The current average cost of such a system including software is $6000.

Interfacing is no more difficult than that required for any type of computer.

For example, we installed on the NBS microcomputer an experiment running on a PDP 11-03 microprocessor in 3 days including all software changes from the

FORTRAN.

The next step is the entrance into the 16 bit microprocessor era which

is now just beginning. Microprocessors with sufficient hardware components

and good software to consider stocking in the storeroom are ready for evaluation by the committee at the present time but lack of funds for this purpose

is impeding progress. These new microprocessors can directly address one to

eight megabytes of main memory. They will have clock speeds of up to 10 Mhz

and powerful instruction sets. The high level languages written for this

system are to be highly compatible between microprocessors. Some of the

16 bit microprocessors and their approximate computing power compared to an 8080 are shown below. These numbers are approximately the inverse of running

time derived from five benchmarks published in EDN magazine: a) Intel 8080

(8 bit) 1; b) Zilog Z80A (8 bit) 2.2; c) Zilog Z800 (8 bit) 5; d) Intel 8088

(8 bit) 7; e) Intel 8086 10; f) Zilog Z8000 13; g) Digital Equipment LSI

11-23 18.6; h) Motorola 68000 21.

Peripherals include all of those for the eight bit microprocessors plus

Winchester disks and math coprocessors. A significant new component for the

8088 and 8086 is the mathematics coprocessor which processes math functions

using parallel processors. Computation bound jobs can be completed in about

a factor ten less time than without the coprocessor. All of the software

that exists for the 8 bit systems will be available including some of the

popular 16 bit minicomputer operating systems, such as UNIX. The average

cost of these systems including 256 K bytes of RAM and a Winchester hard

disk (8 M bytes) is about $10,000. Utilization of these microcomputers for

equipment control opens new possibilities for the type of computer-experiment

interaction that should help to improve the accuracy of analytical techniques.

F. C. Ruegg

f . Inorganic Ion-Doped Glass Beads as Potential Microspectrofluorimetric

Standards

Expanding use of fluorescence in immunochemical and cytological analyses

as well as particulate analysis has made development of microluminescence

standards of increasing importance. The microspheres could be used to:

(1) calibrate instruments for stability in intensity measurements and

wavelength accuracy; (2) as the basis for interlaboratory comparisons of

data; and (3) as relative standards (on absolute standards with absolute

calibrations) in the measurement or luminescence intensities. The main

spectral regions of interest to microscopists for measurement standardization

are in the green (500-575 nm, cellular fluorescing tags using fluorescein

34
isothiocyanate-FITC) and red (6QQ-65Q nm, tags using tetramethyl rhodamine

isothiocyanate-TRITC). The basic purpose of this research was to develop a series of stable, microspheres that fluoresce in the green and red spectral

regions

Inorganic ions in glass matrices were chosen as prime candidates for

these reference materials based on previous work £lj. These ion-doped

glasses, unlike organic fluorophors, demonstrated excellent stability to

photon irradiation. Several experimental glass melts containing different

pairs of inorganic fluorophors were produced to determine their spectral

emission characteristics. Among the fluorophors used with narrow band spectra were samarium, terbium, europium, and dysprosium ions as well as uranyl and

copper ions with broad band spectra. Based on spectral analysis of the

preliminary melts, glasses doped with europium and terbium ions were chosen

for in-depth studies. Silicate glasses doped with varying concentrations of

these fluorophors, were formed into beads 5-100 pm in diameter by flowing

sieved, crushed glass particles in air through an oven at ^1 000 °C with

subsequent cooling and sphere collection on filters. A microscope equipped

with an incident-light excitation system and a scanning monochromator for

determining emission spectra was used as the basic microspectrofluorimetric

system. A high pressure mercury lamp with appropriate filters was used as the

excitation source. Excitation radiation impinged on the luminescent bead and

the emitted radiation, dispersed by the 0.1 m monochromator, was measured by

a photomultiplier tube. The photomultiplier tube output was fed to an amplifier and then directly to a plotter or multichannel analyzer.

Typical emission spectra of the beads doped with terbium, europium, and

terbium + europium are given in figure 11. Irradiation for more than 20 hours

of the europium + terbium-doped bead gave a constant europium to terbium

emission ratio and no indication of fluorophor "fade". Reproducibility

studies of the ratios gave standard deviations of approximately 1 percent.

The peak maxima of both europium and terbium emissions were proportional to

the fluorophor concentration, and at constant fluorophor concentrations, were

proportional to the cube of the bead diameter over the range of bead sizes

5-50 ym thereby indicating a homogeneous medium. A very small amount of beads

are available for research purposes only and plans to produce these SRM's are underway.

Reference

£1] Velapoldi, R. A. J. Res., National Bureau of Standards,

(U.S.). 76A: 641-654; 1972. Velapoldi, R. A.;

Travis, J. C.; Cassatt, U. A.; Yap, W. T. J. Microscopy,

103: 203-303; 1975.

J. R. DeVoe, D. K. Hancock, R. A. Velapoldi, D. H. Blackburn, (Center for

Materials Science)

35
WAVELENGTH, nm

Figure 11. Typical luminescence spectra of inorganic

ion-doped microspheres: A-Tb only;

B-Tb+Eu; C-Eu only.

I

36
3 . Outputs and Interactions

a. Publ i cations

Havrilla, G. J. and Green, R. B., "Evaluation of Plate Electrodes for LaserEnhanced Ionization Spectrometry", Anal . Chem . , 52 , 2376-2383 (1980).

Sams, R. L. and Olson, W. B., "Analysis of the High-Resolution Infrared

Spectrum of the v 2 Bending Mode of H0C1 at 1238 cm” 1 ", J. Mol. Spec.,

84,113-123(1980).

Turk, G. C. , "Reduction of Matrix Ionization Interference in Laser-Enhanced

Ionization Spectrometry", Anal . Chem . , 53 , 1187-1190 (1981).

Travis, J. C. and DeVoe, J. R. , "The Optogalvanic Effect", Lasers in Chemical

Analysis , Chapter 5, Hieftje, G. M., Travis, J. C., and Lytle, F. E.,

eds.. The Humana Press, NJ, 93 (1981)

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

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

Spectrochem . Acta , 36B , 373 (1981)

Scheeline, A., Travis, J. C., DeVoe, J. R., and Watters, J. P., "Discovery of

an Electrical Post-Pulse in the Surroundings of a High Voltage Spark

Discharge", Spectrochem . Acta , 36B , 153 (1981).

Havrilla, G. J. and Green, R. B., "Electrode Positioner for Laser-Enhanced

Ionization Spectrometry", Anal . Chem. , 53 , 134-135 (1981 ).

Havrilla, G. J. and Green, R. B. , "Pre-Amp! ifier for Laser-Enhanced Ionization

Spectrometry", Chem. Biomed. Environ. Instrum. , 4, 11 (1981).

Schenck, P. K. , Travis, J. C., Turk, G. C. , and O'Haver, T. C., "Collection of

Ions Produced by Continuous Wave Laser-Enhanced Ionization in a Hydrogen/

Air Flame", J. Phys . Chem . , 85^, 2547-2557 (1981).

Sweger, D. M. and Sams, R. L. , "Diode Laser Spectra of the v2 Band of H2 12 C0

and H 2 13 C0", Mol- Spec . , 87, 18-28 (1981 ).

Maki , A. G. and Sams, R. L., "High Temperature, High Resolution Infrared

Spectral Measurements on the HNC-HCN Equilibrium System", J. Chem . Phys . (accepted for publication 1981).

Maki, A. G. and Sams, R. L., "High Resolution Infrared Spectrum and Structure

Determination for Carbon Diselenide (CSe 2 )", J. Mol. Spec, (accepted for

publ i cation 1981 )

Frommer, C., Lovejoy, R. W., Sams, R. L., and Olson, W. B., "The Infrared

Spectrum of the Vt Band of SiDc,H", J. Mol. Spec, (accepted for publication

1981).

37
b. Talks

Travis, J. C. , "Laser Enhanced Ionization in Flames for Trace Metal Analysis",

Chemistry Department Seminar, University of Florida, Gainesville, FL,

October 22, 1980. Invited

Travis, J. C. , "Trace Metal Analysis by Laser Enhanced Ionization", Chemistry

Department Seminar, University of Maryland, College Park, MD, October 31,

1980. Invited

Travis, J. C., "Metres, Meters, and Bovine Liver: A Biased View of the National

Bureau of Standards", Austin College Alumni Lecture Program, Sherman, TX,

November 20, 1980. Invited

Ehrlich, D. J., Osgood, R. M., Deutch, T. F., Turk, G. C., and Travis, J. C.,

International Conference on Lasers 1980, New Orleans, LA, December 15,

1980. Plenary Lecture

Travis, J. C., "Laser-Excited Ionization Spectroscopy", Short Course, Department of Chemistry, University of Arkansas, Fayetteville, AR, January

26-28, 1981. Invited

Travis, J. C., "Ion Production and Collection Following Laser Excitation of

Atoms in Flames", Department of Chemistry Seminar, University of Arkansas,

Fayetteville, AR, January 26, 1981. Invited

Travis, J. C., "Ion Production and Collection Following Laser Excitation of

Atoms in Flames", University of Arkansas at Little Rock, Little Rock, AR,

January 29, 1981. Invited

Travis, J. C., Turk, G. C., Schenck, P. K. and 0'Haver, T. C., "Neutral Atom

Depletion by cw Laser Enhanced Ionization", The Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Atlantic City, NJ,

March 10, 1981.

Travis, J. C., Turk, G. C., and Schenck, P. K. , "Time Evolution of the Depleted

Atom Density 'Hole' Following Laser Enhanced Ionization in Flames", VIII

Federation of Analytical Chemistry and Spectroscopy Societies,

Philadelphia, PA, September 24, 1981.

Turk, G. C. and Travis, J. C., "Stepwise Excitation Laser Enhanced Ionization

Spectrometry", VIII Federation of Analytical Chemistry and Spectroscopy

Societies, Philadelphia, PA, September 24, 1981.

Havrilla, G. J. and Schenck, P. K. , "LEI Detection of Potassium and Rubidium

by Infrared cw Dye Laser Excitation", VIII Federation of Analytical

Chemistry and Spectroscopy Societies, Philadelphia, PA, September 24,

1981.

Travis, J. C., Discussion Leader for Presentation by Mary J. Wirth on "Spectroscopic Measurements of Molecular Dynamics using Picosecond Lasers",

Gordon Research Conference, New Hampton, N. H., Aug. 10, 1981.

38
Moore, L. J.; Travis, J. C., "Laser Induced Ion Fluorescence in Magnetic

Sector Mass Spectrometry", VIII Federation of Analytical Chemistry and

Spectroscopy Societies, Philadelphia, PA, Sept. 22, 1981.

c. Committee Assignments

James R. DeVoe

CAC Committee on Computer Requirement

NBS Committee on Selection of Microprocessor for the Storeroom

NBS Ad Hoc Committee on Equipment

Fi Timer C. Ruegg, Jr.

NBS Committee on Selection of Microprocessors for the Storeroom

39
.
II. Inorganic Analytical Research Division

Ernest L. Garner, Chief

Thomas J. Murphy, Deputy Chief

A. Division Overview

The diverse analytical methodology in the Inorganic Analytical Research

Division is organized functionally into the four broad areas of activation

analysis, atomic and molecular spectrometry, analytical mass spectrometry,

and electroanalytical chemistry. This structure provides both the flexibility and the analytical capability to address a wide variety of research

problems, as well as to carry out the full range of analyses required for

the various research activities at NBS, other Federal agencies and other

institutions, either private or public, when requested and appropriate.

Within this framework, the research and measurement priorities of the

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

analytical chemical metrology, (2) providing the basis for chemical standardization which is of maximum public benefit, and (3) addressing the need for

accurate chemical characterization of inorganic species to make a substantial

contribution to the problems of national importance confronting government

and industry.

During the past year, the ratio of research to analytical support

activities has increased significantly and now reflects a more favorable

climate for initiating new areas of research. This improvement is primarily

attributable to an infusion of competence research funds for compositional

mapping via neutron depth profiling and for studies of ion structures/

mechanisms. As a result, significant first-year progress has been made in

designing and constructing a facility for neutron depth profiling. When

completed, this new research tool will add to our knowledge of particle or compositional distribution in materials of critical importance to the nuclear

and solid-state electronics industries. In parallel with neutron depth

profiling, new opportunities and approaches to improve the quality of mass spectrometric measurements are being explored by using lasers to develop a better understanding of vaporization and ionization processes in thermal and

spark-source mass spectrometry. In conjunction with this effort, other

agency proposals offer the opportunity to investigate, in collaboration with

the Instrument Development Group, laser-induced fluorescence as a new approach to providing ultra-high sensitivity and selectivity for detection

and measurement of isotopes. Additional benefits include the use of laser

ionization and laser-induced fluorescence as new diagnostic tools for

ionization and ion optics studies.

With competence research as the focal point for exploring new directions

in analytical chemistry, the major thrust in the remainder of the Division's

research program is directed toward targets-of-opportuni ty to maintain and

improve chemical metrology. During the past year, these broad areas included

specimen bank research, industrial related SRM research, methods research

for trace elements in hazardous waste, speciation, iodine standards for

biological materials, high precision/high accuracy methods development and

atomic weight. Within this array of activities, significant progress has

been made to extend the sensitivity and selectivity of trace and ultra-trace

41
element determinations. For example, a radiochemical, neutron activation,

analytical procedure for the determination of ultra-trace levels of platinum

and tin in biological matrices was developed and applied to tissue samples.

Another example is the improved method for measurement of sulfur by isotope

dilution mass spectrometry which is 10-fold more sensitive than the previous

method of choice. Similar distinct breakthroughs in methods research were

made for the elements iodine, vanadium, nickel, copper, lead, thallium,

cadmium, sulfur, uranium and plutonium in various matrices.

Analytical support of major NBS programs and of programs of other

agencies reflects a close linkage with problems of national importance in

the areas of Standard Reference Materials, environmental measurements,

hazardous waste, recycled oil, nuclear waste, and nuclear safeguards. The

intensity of analytical effort required in each of these areas has been

gradually reduced and has lead to a better balance between analytical services

and methods research. This gradual improvement has been a significant and

contributing factor in raising the Division's research posture. Perhaps one of the more significant highlights illustrating the analytical support

provided for other agencies has been the production and characterization of a set of quality assurance standards for hazardous waste measurements, an area for which very little standardization exists. With the addition of a sludge

quality assurance material, to be completed this year, this set of standards

will consist of a coal feedstock, fly ash, bottom ash, and two synthetic

leachate standards for use as quality assurance materials on a national

scale. The general availability of these materials to both government and

industry is expected to provide the basis for overall improvement in determining the concentration of priority pollutant elements in waste materials.

Of all the national problem areas currently addressed by the Division,

hazardous waste is the only one which seems destined for real growth. All

others, including Standard Reference Materials, will probably remain at a constant level of effort or reflect a significant decrease.

Major instrumentation development in the utilization of existing equipment is directed at improving the capability for automation and high accuracy

multi -element measurements. Research and development outputs within atomic

and molecular spectroscopy have been particularly noteworthy. At present,

the inductively coupled plasma (ICP) system can simultaneously determine up

to 10 elements. With the interfacing of the ICP to the NBS computer, there

has been a substantial enhancement in the ability to correct for interferences

and background, and to take advantage of curve fitting and inter-element

corrections. These basic developments, along with projected improvements,

are expected to yield an increased capability for accurate multi -element

determination. In parallel with these developments, major advances are being

made with the direct current plasma (DCP) system. One of the more significant advances in DCP has been a better understanding of the possible sources

of errors and the modification of the instrumentation for the determination

of either 10 or 20 elements in a multi -element mode. Another development has

been the acquisition of a new computer and some upgrading of existing

detection equipment in the Activation Analysis Group. The Mass Spectrometry

Group has made substantial improvements in many of the sub-assemblies which

will lead to a fully automated instrument.

42
For the immediate future, the combination of competence research and

better balance of analytical support and research within the NBS program

structure will form the foundation for continued improvement in the Division's

research climate. This foundation will be expanded with new proposals for

competence. Director's reserve, and STRS funds. Where practical, the

creative and innovative ideas of the staff will be directed at other government agency programs in a manner which will augment the existing research

base provided by the various sources at NBS. In addition, the Division will

pursue, in collaboration with the Center, those areas of analytical chemistry

which have been identified in the Long-Range Plan as appropriate for increased

growth or new direction.

1 . Activation Analysis Group: Overview

Basic and applied research in activation analysis continues to be

focused on procedures leading to better sensitivity, higher selectivity, and

increased accuracy. The major goal is to fulfill the needs of analytical

chemistry for simultaneous determination of many constituents in complex

matrices over a broad dynamic range. The utilization of activation analysis

as a versatile and sensitive tool in all branches of science and technology

and the development of novel applications are further objectives. Building

on the fundamental principles of activation analysis which have remained

unchanged, the Group's research efforts resulted in incremental and crucial

improvements of the technique. Emphasis is given to procedures, which can leave the sample intact for other uses after analysis, as well as destructive

procedures, which enhance sensitivity and selectivity following the analytical irradiation step. A high level of competence has been developed for

various activation analysis techniques which include instrumental and radiochemical neutron activation analysis (INAA and RNAA), photon activation

analysis (PAA), prompt gamma activation analysis (PGAA), and nuclear track

technique (NTT). Concurrently, the Group is expanding its research activities

to include questions of general analytical importance such as sampling and

sample preparation for analysis.

Recent research accomplishments in the area of activation analysis

methodology are highlighted by the development of RNAA procedures for the

determination of platinum and tin in biological matrices. In both cases,

radiochemistry lowers the limit of detection and provides essentially "background-free" counting of the specific signals, free of interferences from

chemical blanks. Unprecedented low levels of platinum have been determined

using this new RNAA technique. Other research efforts are directed towards

the determination of light elements as major constituents of complex matrices

using PAA and PGAA. The accuracy and precision are currently being evaluated.

A newly developed RNAA technique for the ultra-trace determination of 1-129

will make possible the issuance of a certified material.

In connection with the pilot National Environmenal Specimen Bank (NESB)

program, research efforts have resulted in a better understanding of the

sampling characteristics of particulate biological matter. Methods to better

homogenize these materials have been investigated and developed. Investigators, in collaboration with NBS statisticians, are examining the question of

43
proper subsampling in order to produce more meaningful analytical results.

Among the problems being studied are the appropriate number of samples to be

taken as well as the proper sample size to be used for analysis.

INAA multielement determinations have provided a huge data-base for

Chesapeake Bay, NESB, and Hazardous Waste, the major environmental programs

participated in during the past year. The wide dynamic range of activation

analysis, along with its multielement capability, is especially useful for

the determination of various concentrations of expected elements as well as the detection of unexpected elements. INAA multielement results have been

reported for the certification of up to 20 elements in each of a variety of new or renewal SRMs: Bovine Liver, Orchard Leaves, Cast Iron Alloys, Basalt,

Obsidian, Reduced Iron Ore, and Fuel Oil. INAA has provided vital information to another NBS Group on fused silica glass insulators. INAA has also

been used for the determination of halogens as well as other constituents in

organic liquids in support of the NBS Recycled Oil Program and the Office of

Standard Reference Materials.

Continued emphasis is placed on the importance of acquiring and utilizing

state-of-the-art equipment to assure that INAA, the Group's strongest competence, will continue to contribute to the mission of analytical chemistry at

NBS in the same way in the future. Major additions to counting equipment and

the acquisition of a computer will help achieve this goal. In addition, the

Group will continue to take advantage of the specifics of nuclear techniques

in ultra-trace determinations and chemical speciation studies by developing

RNAA techniques and applying activation analysis to problems such as the

rapidly expanding field of bio-technology . The new depth-profiling facility

provides entry into a new and important field in analytical chemistry.

Rolf L. Zeisler, Group Leader; David M. Allen, M. James Blackman,

B. Stephen Carpenter, Kathleen A. Fitzpatrick, Ronald F. Fleming,

Robert R. Greenberg, Sally H. Harrison, John K. Langland, Richard M. Lindstrom,

George J. Lutz, Trudi E. Mitlehner, Michael D. Vinocur, James R. Vogt

2. Analytical Mass Spectrometry Group: Overview

The primary objectives of the Analytical Mass Spectrometry Group continue

to be the development and maintenance of a capability for high accuracy

isotopic ratio measurements. The increasing need for such high quality

analytical measurements on sub-microgram amounts of material has required

continual improvement in chemical separation and purification techniques and mass spectrometric instrumentation. To accomplish these tasks, the Mass

Spectrometry Group is composed of essentially two sub-groups. The chemistry

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

Expertise in separations technology, isotope equilibration, sample dissolution, purification, and "contamination-free" sample handling are primary concerns in this area. The other sub-group specializes in inorganic mass spectrometry. This sub-group has considerable expertise in high accuracy

mass spectrometric isotope ratio measurements and is responsible for developing improved methodology and instrumentation for thermal ionization, spark

source, electron impact, and surface ionization mass spectrometry.

44
During the past year, the Group had a very favorable research to

analytical support ratio, due primarily to the additional research funds

received through the Competence Building Program for the investigation of

ionization mechanisms and ion structures. Extensive research plans have been

formulated for this activity, a laboratory has been modified, and special

purpose equipment either has been ordered, purchased, designed, or constructed.

A Neodymium-Yttrium Aluminum Garnet (Nd :YAG) laser is scheduled for installation late this year and will be used for ion fluorescence measurements to

study vaporization and ionization mechanisms.

Considerable progress has been made on modifications of instrumentation

and on the development of fully automated, high-accuracy mass spectrometers.

A prototype automatic magnetic field controller has been constructed and

successfully tested. A new prototype filament control unit was built,

tested, and found to improve stability by two orders of magnitude. A "new"

collector without transmission grids has been designed and evaluated. A new electrometric amplifier has been designed and a prototype constructed. These

advances will improve existing instrumentation as well as provide the foundation for fully automated high accuracy instruments in the near future. In

addition, because of the potential safety hazard from mercury, most of the

mercury diffusion pumps have been replaced with turbomolecular pumps.

In atomic weight research, two of the more recently redetermined atomic

weights, strontium and silver, have been accepted as international values by

the Commission on Atomic Weights of IUPAC. The silver atomic weight impacted

on the recently NBS-determined value of the Faraday, reducing the uncertainty

in that value by one-half. Research programs to obtain new atomic weights

for gallium and lithium are underway.

Important accomplishments in the area of improved methodology for

isotope dilution mass spectrometry include the development of chemical and mass spectrographic procedures for elements not previously measured or at

lower levels than previously determined. For example, a new thermal ionization silica gel method for sulfur has been developed which offers a 10-fold

improvement in precision and accuracy over the spark source method. A method

for the determination of pi cogram quantities of uranium in environmental

samples was developed. The first IDMS determination of vanadium was success- fully accomplished for the Trace Elements in Oil SRM. Silica-gel procedures

were developed which make possible the determination of nickel and copper at

much lower concentrations than have been accomplished in the past. A method

was developed for the determination of low concentrations of both Pb and T1 on small samples of liver. An IDMS method for Cd in Blood at the nanogram

level was developed and applied to "round-robin" samples obtained from the

World Health Organization.

The most sample intensive program was measurements on the IDA-80 samples,

a joint effort with the Central Bureau for Nuclear Measurements (Belgium) to

characterize samples which will be used in a worldwide interlaboratory test

program to assess the state-of-the-art of uranium and plutonium measurements

by IDMS. In other related research for the nuclear community, high sensitivity pulse counting mass spectrometry was utilized to determine the

isotopic composition of nanogram quantities of uranium and plutonium for

"round robins" designed to evaluate the state-of-the-art for resin bead

45
technology. These "round robins" involved the distribution of uranium-loaded

beads, plutonium-loaded beads, and beads containing both uranium and plutonium.

The results indicate measurement precisions comparable to what is achieved

with large samples and conventional detectors.

The expertise of the Group was utilized for several programs not involving

mass spectrometry. A high accuracy ti trimetric method for uranium has been

developed in which the sample size requirement has been reduced from 2 g to

less than 100 mg with no loss in precision. A program was initiated to

evaluate the parameters influencing the accuracy and precision of leachability tests on storage materials proposed for nuclear waste disposal. In addition, reference samples were prepared and/or evaluated for both drilling

mud and synthetic "synfuel discharge." Both of these materials will be

utilized on a national scale by other government agencies as quality assurance

standards.

During the past year, the activities of the Group have been augmented by

several long term guest workers. These include scientists from the National

Institute of Metrology, Beijung, Peoples of Republic of China; the Central

Bureau of Nuclear Measurements, Geel , Belgium; the Institute of Physics,

University of Mexico; and the Smithsonsian Institute, Washington, DC. Gas

isotope dilution mass spectrometry, the origin of artifacts by lead isotopic

composition, theoretical studies of isotopic fractionation, and research in

isotope dilution to determine Pb and Cd in blood, serum, and other biological

fluids are representative of the more significant activities of guest

workers.

Near-future research plans are focused on the competence research for

ion mechanisms, the atomic weight program, and the development of chemical

and mass spectrometric procedures for isotope dilution analyses. The use of

a laser as an alternative ionization mode for spark source mass spectrometry

remains high on the Group's priority list. Another signficant project is the

investigation of simultaneous dual collection of ion currents as an alternate

means of increasing precision and accuracy. In parallel with competence and

related research activities, Group plans will focus on more automation of ion

exchange chromatographic procedures and mass spectrometric analysis. New

chemical separation techniques and mass spectrometric methodology to lower

detection limits for all elements presently determined will be given major

attention. As part of the continuing effort to upgrade existing methodology,

research to develop methods to detect and analyze elements currently beyond

the Group's capability will be pursued.

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

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

John W. Gramlich, Billy R. Hardas, Emerson F. Heald, Mark S. Hutzler,

William R. Kelly, Howard M. Kingston, George M. Lambert, Lawrence A. Machlan,

Eddy A. I. Michiels, John R. Moody, Larry J. Moore, Pedro A. Morales,

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

46
3. Atomic and Molecular Spectrometry Group: Overview

The Atomic and Molecular Spectrometry Group strives to advance the

development and analytical applications of emission and absorption processes

occurring in the spectral region of 2000 to 8000 A for the improved characterization of a wide variety of materials in an efficient and cost-effective

manner. The areas currently being addressed to achieve this goal include the

development of: (1) more accurate methodologies; (2) expanded multi-element

capabilities; and (3) state-of-the-art calibration standards.

The Group's research efforts in atomic spectrometry have centered

primarily on the continued development and evaluation of the analytical

capabilities of the inductively coupled plasma (ICP) and the direct current

plasma (DCP)/echel le spectrometers. Up to 10 elements can presently be

determined simultaneously with the ICP system; 10 and 20 element dedicated

cassettes have been installed and aligned for use in the DCP instrument.

In order to characterize and correct for matrix effects, the ICP minicomputer has been connected to the NBS computer via the NBS network. This

data transfer capability should significantly improve the accuracy of ICP

analyses. In addition, laser machining is presently being investigated as a possible technique for precisely machining slit arrays with slit widths of 20

micrometers or less. To date, in-house capabilities have been successful in

producing arrays containing a maximum of only three slits with minimum widths

of about 70 micrometers.

Two principal factors have been identified that seriously affect the

accuracy of measurements with the DCP instrument. One is related to the

types of spectral interferences encountered; the other is related to the

significant wavelength shift produced in the echelle spectrometer by small

changes in room temperature. Both single and multielement studies of spectral

interference are under study and various ways for thermos tat ing the spectrometer are being considered.

Two important research projects were initiated in atomic absorption (AA)

with potentially large long-term payoffs. One is concerned with the search

for a universal matrix modifier to eliminate interferences in graphite

furnace measurements and the other involves an initial evaluation of a coupled

high performance liquid chromatograph-AA detector for performing metal

speciation measurements. Both of these projects, over the next several

years, are expected to eventually lead to improved accuracy and sensitivity

for trace element analysis.

Spark emission spectrometry is presently used extensively to provide

acceptance, homogeneity, and elemental data for metal SRM's. In providing

these services during the past year, two areas were identified that merited

further study. In the first one, work was carried out to understand and

correct for the general problem of sample contamination during analytical

preparation; in the other area, work was done to evaluate an apparent bias in

spark emission sulfur values for certain iron-base SRM's.

47
Two major research efforts have been carried out in molecular spectrometry this year. The first effort involved the identification and elimination

of the polarization problem that has hindered the production of the chromiumon-quartz transmittance standard (SRM 2031). By more carefully controlling

the rate of evaporation of the chromium and spinning the quartz plate during

deposition, the polarization effect, which in severe instances was larger

than 10 percent, has been reduced to less than 1 percent. The second effort

involved the development of a prototype luminescent uranium glass standard

for use in calibrating instrumentation employed in the evaluation of fluorescent dye penetrants used in non-destructive crack testing.

Again this year, the large effort in analytical support activities by

the Group represents a very substantial contribution to programs of national

importance. Programs to which the Group made major contributions were Standard Reference Materials, Recycled Materials, Hazardous Waste, Nuclear

Waste, Environmental Specimen Bank, FDA Injectables, and Service Analyses. A

few of the programmatic accomplishments made during the past year include:

The collection, processing, and characterization of a fly ash, a sludge, and

two levels of a 17-element simulated solid waste leachate for use by DOE and

EPA as quality assurance standards; the multielement graphite furnace-AAS

analysis of 36 liver specimens, and approximately 60 injectable materials;

and initial characterization of leachates obtained from various glasses being

evaluated as underground storage containers for nuclear wastes.

Future plans entail expanding the current but modest efforts in metal

speciation studies, initiating research for the direct analysis of solids by

graphite furnace-AAS, developing a capability for measuring the particle size

distribution in spark-generated aerosols, adapting the DCP instrumentation

for vacuum UV applications, and continuing the systematic investigation of

matrix modification techniques.

Robert W. Burke, Group Leader; Carol G. Blundell, David E. Brown,

Therese A. Butler, Erie R. Deardorff, Barry I. Diamondstone,

Michael S. Epstein, Shigeki Hanamura, Radu Mavrodineanu, Jerry D. Messman,

John A. Norris, Theodore C. Rains, Theresa A. Rush, Roger M. Stone,

Robert L. Watters, Jr.

4. Electroanalytical Chemistry Group: Overview

The Electroanalytical Chemistry Group has as its objective the development and utilization of electrochemical principles for chemical analysis.

The techniques of interest include amperometry, conductimetry , coulometry,

ion chromatography , polarography , and potentiometry . Research is aimed at

attaining a more thorough understanding of the complex chemical systems

encountered during the development and implementation of high-accuracy

procedures ranging from ultra-trace determinations in a myriad of matrices to

assays of ultra-pure chemicals. Electrochemistry is experiencing a resurgence

in popularity and this Group intends to take an active role through innovative

research incorporating all of these techniques, particularly in the areas of

speciation and multi-component analysis.

48
One of the major responsibilities of this Group is in support of the

Standard Reference Material program, both in research and in analysis for

certification. This year, basic research was undertaken to extend the

capabilities of ion chromatography to the determination of sulfur in steel

and in copper alloys, and preliminary results appear promising. It is

expected that this method development will be completed next year and that

its application to real samples can begin. High-precision coulometry was

used to certify three primary standard chemicals, tris (hydroxymethyl ) ami no

methane, benzoic acid, and potassium dichromate. Extensive measurements

were made on the dichromate samples during an exhaustive statistical study

to establish homogeneity. At the same time, systematic uncertainties in

coulometry were also studied. Aluminum was determined in several samples

of cast irons by polarography. River Sediment, Urban Particulate, and

Washington Dust were analyzed by ion chromatography for total sulfur,

chlorine, and soluble sulfate and chloride. Several oils were analyzed for

sulfur content using ion chromatography.

The major effort of polarographic analysis this year focused on the

analysis of human liver samples for trace metals as part of the National

Environmental Specimen Bank. In addition, another project was initiated to

analyze biological and injectable materials for trace metals, particularly

aluminum. These analyses are part of a program to establish the trace metal

composition of the different types of injectables currently in use. After

establishing normal trace levels for the various product types, a suitable

matrix will be selected and a reference material will be characterized to serve as a control or standard for the determination of trace metals in

biologies.

The Acid Rain program is continuing with an increased emphasis on research. The goal in this area is the development of an SRM which will

provide traceability to the national measurement system through a few well

characterized standards rather than a large number of audit samples. Longterm stability of acid rain reference materials in various containers is

being investigated. Serious shortcomings have been found in the methods for

pH and acidity measurements as well as in subsequent interpretation of the

data. For instance, residual liquid-junction potentials can severely bias

the pH measurement. Acidity titrations can be similarly affected by errant

end-point selection or end-point detection by inappropriate techniques.

Revised measurement protocols are being investigated to correct these

deficiencies

A small synfuel waste discharge project was completed which involved a critique of the sampling and measurement procedures recommended by EPA, and

the preparation and analysis of two sets of solutions containing select

elements and anions for use as control standards. Standards used to calibrate

the ion chromatograph were put on an absolute basis through the use of

coulometric standardization of high-purity acids. Methods were developed for

the complete anionic characterization of chloride-doped cadmium sulfide by

ion chromatography . Additionally, the distilled water in the Chemistry

Building is checked regularly by this Group using conductimetry and ion

chromatography to ensure its quality.

49
Significant advances have been made in the high-precision coulometric

assay of uranium. A comprehensive study of current efficiency was made

involving different electrode materials and surfaces in a variety of electrolytes. This study has resulted in a procedure with twice the precision of

earlier high-precision methods.

This past year, the major instrumentation acquired was an electrochemical

detector to complement the conductimetric detector of the ion chromatograph.

It is expected that it will be used in the coming year for cyanide determinations and halogen speciation.

A major effort will be initiated next year toward upgrading the pH

facility and reestablishing the expertise for recertification of NBS pH

buffers. Paralleling this effort will be research in pH measurements of low

ionic strength solutions such as encountered in acid rain samples. Commencing with these two projects, it is hoped to generate vigorous research

activity in pH and potentiometry. Research in high-precision coulometry will

continue with studies of current efficiency and other systematic errors which

may adversely affect the accuracy of the method. Voltammetric research will

tend toward the utilization of anodic stripping voltammetry for precise trace

and ultra-trace metal analyses. Investigations in ion chromatography will

concentrate on incorporating the electrochemical detector into the system to

enhance selectivity and sensitivity and to augment the types of anions

determinable. Methods for determining speciation of halogens, nitrogen,

sulfur, and possible metal anionic complexes will be explored. A joint

project coupling the selective pre-concentration of trace metals by electrodeposition with the sensitivity and specificity of atomic absorption is

antici pa ted.

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

Jeffrey W. Stolz, Tatsuhiko Tanaka

50
B. Selected Technical Accomplishments

(Inorganic Analytical Research Division)

1 . Application of Sampling Theory to Particulate Biological Samples

The quality of the analytical sample, as distinguished from the quality

of the chemical measurement, is a too often disregarded factor in analytical

chemistry. The sample on which the results of a chemical analysis are finally

based depends very much on the properties of the bulk sample and the analytical test portion taken from the bulk sample. Programs like the pilot

National Environmental Specimen Bank (NESB) are critically dependent on the

credibility of the analytical results, e.g., on the bulk sample representation

found in the analytical test portion. The NESB tasks of evaluating storage

conditions and analytical quality are carried out by means of multiple

analysis of many samples. This represents an ideal test case for studying the

application of sampling theory to the investigation of the properties of

particulate biological materials.

Biological specimens, (e.g., human liver, mussel, etc.) are homogenized

at cryogenic temperatures under contamination-free conditions, in Teflon ball

and disk mills to provide analytical test portions for comparative analysis.

The samples are always handled in a cryogenic state and maintain particulate

appearance after homogenization. Assuming a particulate homogenate, the

performance of the two types of mills, ball and disk, was investigated. A

radiotracer experiment was carried out and Ingamells sampling constant, K , was determined after collecting the data for a sampling program [1]. Using

the ball mill, a K

$ = 32 g was determined. Based on the Kg value, one can conclude whether the material has been adequately ground and adequately mixed.

As a result of this study a disk mill was designed that yielded a K of

0.95 g.

To verify the particulate model, efforts were undertaken to actually

measure the particle size distribution of the homogenate obtained from the two

different milling procedures.

In general, sieving experiments are an easy way to determine particle

sizes; however, cryogenic sieving of frozen samples is much more difficult.

After some procedure development, the sieving experiments were carried out in

a large LN 2 freezer which provided the necessary cold and dry atmosphere to

avoid melting and particle agglomeration due to moisture condensation. The

results of sieving split liver samples, previously ground in the two different

mills, show that the disk mill produces somewhat finer particles with virtual

elimination of the coarse (>40 mesh) fraction. Twenty five percent of the

material ground in the ball mill remained in the coarse (>40 mesh) fraction.

The obvious affect on subsampling is that smaller particles produce better

homogeneity.

Using the information about particle size distribution and some assumptions as to the chemical nature of the liver, the weight of sample required to

hold the sampling standard deviation to a preselected level can be theoretically calculated starting with the computation of N, the number of particles.

51
The value of N may be calculated from the relation

d

l d2

2

_ ioo(p

1 - p2 r

U 2

J R P - P(1 - P)

where dj and d 2 are the densities of the two kinds of particles, d is the

density of the sample, P 2 and P 2 are the percentage compositions of the

component of interest in the two kinds of particles, P is the overall average

composition in percent of the component of interest in the sample, R is the

percent relative standard deviation (sampling error) of the sampling operation, and p and 1-p are the fractions of the two kinds of particles in the

bulk material [2]. For a two component particle mix made up of cells and

fluids and for 40 mesh particles, the element Na requires a one gram sample

to reduce the sampling error to one percent. This is very consistent with the

sampling constant of 0.95 g found as described above.

In addition, trace element analysis experiments were carried out to

provide support data for the theoretical evaluations. In one experiment, ten

subsamples of homogenized liver were analyzed using nuclear methods for about

30 elements. The element specific homogeneity was determined to be two to

three percent for most elements and one percent or less for Na, Fe, and Zn.

In another experiment, mussel (Mytilus edulis) samples were homogenized in a disk mill before being sieved. The sieved fractions were then analyzed by

Instrumental Neutron Activation Analysis (INAA) for trace elements. Representative percentages of the amount of material in each sieve fraction are also

given. Some interesting results from this experiment are shown in Table 4.

These results indicate a fraction containing NaCl , probably due to the salt

water contained in the mussel shell at the time of shucking, which being ice

crystals, grinds to a finer particle size than the organism material.

Table 4. Na and Cl in Mussel Sieve Fractions,

(concentration in mg/g dry weight)

Sieve Fraction <40 40-60 60-80 80-100 100-140 140-200 <200 Unsieved

Mesh Range

Weight Percent 2 25 18 14 26 12 3

Na 54.0 53.8 57.2 61.9 65.5 70.7 71.8 61.0

Cl 79.8 96.7 102 110 116 121 128 111

The work shows that theoretical calculations of sampling parameters

compare favorably with experimental results. This information can provide

important knowledge on the relation of the analytical test portion to bulk

material and therefore the quality and usefulness of the analysis.

References

[1] Ingamells, C. 0. Geochim. Cosmochim. Acta 38: 1225; 1974.

[2] Kratochvil , B. ; Taylor, J. K. Sampling for Chemical Analysis,

Anal. Chem. 53: 924A; 1981.

K. A. Fitzpatrick, S. H. Harrison, B. G. Kratochvil, R. L. Zeisler

52
2. Determination of Ultratrace Platinum in Biological Materials

Increasing interest in the determination of platinum has been spurred

recently by the widespread use of the element in industrial and medical

applications. Two possible major sources contributing to the human body

burden are the noble metal catalysts used to reduce automobile emissions, and

the administration of platinum-containing drugs used in cancer chemotherapy.

The intense interaction of platinum and its complexes with biological systems

makes it desirable to establish baseline data and to monitor possible increases

in human body burden. Previous attempts to measure baseline concentrations of

platinum have failed because the reported sensitivities were several ng/g for

the various techniques, while the actual concentrations were at least one order of magnitude lower. Many analytical techniques including neutron

activation, however, have been successfully applied to monitor elevated

platinum levels, e.g., after administration of anticancer drugs consisting of

platinum complexes of the cis-(PtCl 2 L 2 ) type [1].

To measure the naturally occurring concentrations in human tissues and

other biological materials, a new neutron activation analysis scheme based

upon radiochemical separation of the activation products has been developed.

This method fully utilizes the inherent sensitivity of the activation reaction

198 Pt (n,y) 199 Pt and counting of the daughter nuclide 199 Au after radiochemical separation. The separation applied here is highly specific for gold,

thus avoiding common interferences as well as providing "background free"

counting of the respective gamma activities. A decontamination factor of

>10 7 for 24Na has been achieved. The only remaining interference to be

considered is the reaction 197Au (n,y) 198Au (n,y) * 99 Au from the naturally

occurring gold in the samples. This reaction can be quantitatively assessed

with high precision and taken into account by the determination of the gold

using the same separation step. This analytical procedure, therefore, also

provides excellent results for gold at the 10" 12 g/g level.

The results of a number of applications of the method to biological

Standard Reference Materials and human liver specimens are given in Table 5.

The results for platinum are found to be far below previously reported data

for Orchard Leaves, SRM 1571, and below the current limit of detection in this

material. The gold values, however, are in good agreement with the previous

data, thus confirming the completenesss of the analytical scheme [2]. For

Bovine Liver, SRM 1577, both elements seem to be inhomogenously distributed,

which would explain the wide scatter of the previously reported data for gold.

The platinum concentrations found here are the first data reported for a presumably natural baseline in these materials which were collected more than

ten years ago. It would be of interest to analyze similar materials collected

recently. Possibly an increase of platinum in the environment could be

detected.

The application of the technique to the analysis of human liver specimens

collected in the National Environmental Specimen Bank Program will help to

establish baseline information on human body burden.

53
Table 5. Platinum and Gold in Biological Materials.

-12

Concentration, IQ g/g (dry weight)

- - - This

Pt

Work - - - Au Pt

Literature £2]

Au

SRM 1571 , Orchard Leaves 0,200 1430 ± 80a (89.2 to 1200°)* 10

J 1970 to 3500

SRM 1572.

Citrus Leaves 60 ± 3Q

a 107 ± 9 NR

b

NR

b

SRM 1577,

Bovine Liver 70 ± 30 56 ± 13 NR 200 to 30000

Human Liver 50 to 240 69 to 2650 NR

b

30 to 100000

Experimental error, fewer degrees of freedom.

b

No data reported previously.

References

[1] Zeisler, R.; Lux, F. ; Seidenberger , H. ; Schoenenberger , H.;

Beck, W. Nuclear Activation Techniques in the Life Sciences

1978, p. 467, IAEA Vienna, 1979.

[2] Gladney, E. S. Compilation of Elemental Data for NBS Biological

and Environmental Standard Reference Materials, Los Alamos

Scientific Laboratory Informal Report, LA-8438-MS, 1980 and

Anal. Chim. Acta 118: 365; 1980.

D. M. Allen, R. R. Greenberg, R. L. Zeisler

3. A New Method for the Determination of Sulfur by Thermal Ionization

Mass Spectrometry

The determination of sulfur in ferrous and copper materials at concentrations below 5Q ppm is necessary to control critical chemical and physical

properties of these materials. Classical chemical methods for measuring

sulfur are not applicable to concentrations much below 50 ppm and the newer instrumental techniques applicable at these concentrations rely on calibration

curves based on standards. To produce Standard Reference Materials for these

instrumental determinations, it is necessary to have an independent technique

capable of yielding an absolute sulfur determination with microgram sensitivity. A thermal ionization mass spectrometric isotope dilution procedure

has been developed to meet these needs.

This procedure utilizes much of the chemistry previously developed for

the isotope dilution spark source mass spectrometric (JD/SSMS) determination

of sulfur [Q.5 pg blanks, and ±3 percent rsd). The reason for adopting

isotope dilution thermal ionization mass spectrometry was two-fold, first to

54
lower blank levels (ID/SSMS blanks are limited by sulfur content of the gold

powder necessary for sample preparation) and second to utilize the inherently

more precise thermal ionization method.

Sample and 34 S spike are equilibrated in a sealed pyrex tube to prevent

loss of volatile sulfur compounds prior to equilibration. The sulfur is

isolated, converted to As 2 S 3 , dissolved in NH 3 plus excess As (III), and

loaded onto a Re filament with silica gel. Sulfur isotopic ratios are measured as the AsS

+

ion. Since As is mono-nuclidic, the ion intensities at masses 107, 108, 109, and 111 from As

+ are directly proportional to the

abundances of sulfur 32, 33, 34, and 36, respectively

Currently, the blank is 0.1 yg or less and the measurement precision for

the 34 S/ 32 S ratio is better than 0.2 percent. This represents a five-fold

improvement in blank levels and a ten-fold improvement in precision and

accuracy compared to ID/SSMS.

Sulfur determinations have been obtained for two copper base SRM's and are given in Table 6. Three aliquots of a 2.7 gram spiked sample of SRM 184 were chemically processed and measured independently. The results are affected by

blank from the chemistry and the mass spectrometry as well as the precision of

ratio measurements.

Table 6. Parts Per Million Sulfur by Weight

(yg/g)

SRM 184 SRM 1035

17.70 22.30

17.74 22.15

17.63 22.19

Average 17.69 22.21 ppm

The blank correction was about one percent in each case. The measured values

show a 0.6 percent range which indicates the present level of control over the

three sources of error and imprecision mentioned above. Also given in Table 6 are three separate determinations on a composite chip sample of SRM 1035. In

this case, the values obtained are affected by the three previously mentioned

factors as well as sample heterogeneity. The relative range in SRM 1035 is

also about 0.6 percent. These sulfur determinations indicate that precise

sulfur determinations can be obtained at the 20 ppm level and that sample

heterogeneities of one percent could be resolved at this level on one gram

samples.

Blank control is critical in sulfur analysis due to the high sulfur

levels inherent in chemical laboratories plus the ambient levels due to

internal combustion engines and fossil fuel power plants. Isotope dilution

sulfur blanks are now being held below 0.1 yg by excluding room air with a nitrogen gas blanket whenever the samples are not in a sealed system.

55
The mass spectrometric sample requirements for a single analysis are in

the submicrogram range. With this level of sensitivity, the three major

isotopes can be measured very precisely. This eliminates a potential bias of

one percent due to the natural variation of the sulfur isotopic composition.

The precision with which the 32 S/ 34 S ratio can be measured by this

technique permits the possible identification of distinct sulfur sources. One

important application would be the study of the sulfur isotopic ratios in rain

as a means of identifying the sulfur source as coming from coal, oil, gas, or

soils. This technique, while not yet as precise as "gas" mass spectrometric

isotopic ratio measurements, has the advantage of using simpler chemical

premeasurement processing and an approximately 10-fold smaller sample.

The high precision of this thermal silica gel procedure makes it suitable

for high sulfur levels in addition to the low levels reported so far. With

precisions of better than ±0.2 percent rsd, this technique will be competitive

with any other method at concentrations up to and above 1000 ppm. The method

will be applied shortly to determining sulfur in Citrus Leaves and Bovine

Liver SRM's.

W. R. Kelly, P. J. Paulsen

4. An Investigation of Biases in the Determination of Sulfur in Steel by

Emission Spectrometry

Over the past several years, the need to accurately determine sulfur in

steel has assumed greater importance. This is particularly true where certain

physical properties of steel are adversely affected by concentrations of

sulfur greater than 0.005 percent. The acute need for reliable quality

assurance materials with accurately known trace sulfur concentrations for

steel production is reflected in industrially related SRM research to develop

definitive methods. With the availability of such data, calibration of other

instrumentation utilized to characterize reference materials or provide

quality control analyses for the steel production process is the next essential

step.

Most of the sulfur values reported by emission spectrometry over the

last few years have been based on calibration data obtained from the NBS SRM

1260 series of low alloy steels. Prior to the recent isotope dilution spark source mass spectrometric (ID/SSMS) validation of the sulfur content of

these five SRM's, the emission spectrometric calibration curve was established

by drawing the best line through five data points.

Considering that isotope dilution mass spectrometric values are in

general the most accurate available, it was noted that when emission intensity

was plotted as a function of the ID/SSMS value, two distinct curves could be

drawn. One curve came from SRM 1265 and SRM 1262 and the other from SRM

1261, SRM 1263, and SRM 1264 (figure 12). The displacement between these

two curves corresponds to a discrepancy in sulfur concentration of about

0.002 percent. These curves are best defined using the Walters adjustable

waveform excitation source but are also seen with the recent new source from

56
57

*

SULFUR

Figure

12.

Analytical

curves

for

sulfur

in

steel

-

AWS

80:30.
Baird Corporation (KH-3). As new production SRM's have become available,

they also divide between the two curves. Other special research materials

show the same pattern although most materials fall on the same curve at

concentrations below 0.01 percent. The SRM's evaluated thus far are grouped

as follows:

Curve A 1265, 1262, 1138A, 1134, 1167, 1165, 1166, 1270,

131b, and high purity iron

Curve B 1263, 1261, 1264, 1138, 1163, 1161, 1222, 1161,

and 1269

Values for SRM 1164, SRM 1162, and SRM 1168 do not fall on either curve

but are found above curve B. No values have been found for SRM's below curve A.

Reference materials from other sources have also been evaluated. Since

the given sulfur values are not related to the present definitive values,

the data are scattered between the two curves. New chemical determinations

directly related to the new sulfur values are needed to properly place these

materials.

The identification of a bias of 0.002 percent in the determination of

sulfur in steel by emission spectrometry has profound and far reaching

implications in the understanding of excitation chemistry mechanisms. Until

additional research is conducted to identify the source of the bias, reliable

quality control by emission spectrometry in the production of steels with

less than 0.005 percent sulfur will be difficult.

D. E. Brown, J. A. Norris

5. Determination of Chlorine and Sulfur in Cadmium Sulfide

Cadmium sulfide, doped with various elements, has been used extensively

in the photoconductor and solar energy industries. Recently, there has been

renewed interest in cadmium sulfide doped with cadmium chloride for use as a possible super-conductor at non-cryogenic temperatures. The concentration

of chloride and its manner of incorporation (either within the crystal

lattice or merely as an intimate mixture) may be critical parameters to the

effectiveness of the compound as a super-conductor. Previous methods for

the determination of halogens in these types of materials required expensive

instrumentation, extensive sample preparation, or were plagued with severe matrix interferences and non-specificity. Procedures have now been developed

for the rapid determination of not only chlorine but all the anionic components in cadmium sulfide samples.

To determine total sulfur and chloride content, the samples were dissolved in a 1:1 mixture of a carbonate buffer solution (pH 9.8) and

hydrogen peroxide (30 percent), with gentle heating. Under these conditions,

all sulfur species were oxidized to sulfate, whereas the chloride was unaffected. After destroying the excess peroxide by boiling, the sulfate

and chloride were quantitated using ion chromatography. Total sulfur and

58
chloride were then computed, as well as mass-balance, assuming the sample

contained only cadmium sulfide and cadmium chloride.

In order to determine the soluble anionic components, the cadmium

sulfide samples were sonicated in an ultrasonic bath using a carbonate

buffer solution as the solvent. Identification and quantitation of the

anions were performed by ion chromatography. In the materials analyzed,

only chloride and sulfate have been found as soluble components. However,

had other soluble anionic species (such as fluoride, bromide, nitrate, or phosphate) been present as contaminants, they would also have been determined

Eighteen samples have been analyzed with total chloride ranging from

0.7 to 4.0 percent by weight and soluble chloride ranging from 0.1 to 2.5

percent by weight. Those samples wherein all the chlorine was present as soluble chloride did not exhibit super-conducting properties. All the

samples contained some sulfur as sulfate, but at a concentration always less

than 0.4 percent by weight. The estimated precision of these analyses is

five percent (one standard deviation). This uncertainty could be reduced to one percent by additional research if future studies require better precision

In conclusion, a new method has been developed for the analysis of

cadmium sulfide samples for anionic constituents. Speciation of the chlorine

and sulfur components has been demonstrated. Work is proceeding to extend

the method to bromine as well. An alkaline hydrogen peroxide procedure has

proved to be effective in the dissolution of cadmium sulfide. It is anticipated that such a dissolution procedure could be applied to other metal

sulfides and sulfur-bearing materials, with the subsequent determination of

total sulfur as sulfate by ion chromatography.

W. F. Koch, J. W. Stolz

6. Determination of 1-129 in Biological Matrices

Iodine-129 is present in the environment in both natural and man-made

forms. The major man-produced sources are nuclear weapons tests and irradiated nuclear fuel reprocessing plants. Recent emphasis on increasingly

reliable 1-129 measurements has prompted modification of existing methods in an effort to improve accuracy and to develop a Standard Reference Material

certified for 1-129 content.

Neutron activation analysis is used for the measurement of the fission

produced 1-129 in biological and environmental samples. The determination

consists of a pre-irradiation separation, irradiation in the reactor, and a post-irradiation separation. The pre-irradiation separation involves the

combustion of the sample in a stream of oxygen; the "off gases" are filtered

through glass wool to trap out any particulate material and the iodine is

trapped on activated charcoal. This pre-irradiation filtering removes uranium, cesium, and tellurium which interfere with the determination of I129 by yielding, upon irradiation, the activation product 1-130.

59
The charcoal trap containing the iodine is then sealed in quartz and

irradiated in the reactor at a thermal neutron flux of 1 . 5x1 0

1

3

for a period

of 16 hours. After a short cooling period, a few milligrams of inactive

iodine carrier is added. The charcoal and carrier are burned in a stream of

oxygen. The gases evolved are again passed through a plug of glass wool to

filter out particulate material. The collecting trap consists of a bed of

hydrated manganese dioxide (HMD) followed by a charcoal trap for collecting

the iodine. HMD is one of a series of selective ion retention media developed

during the past several years. It is usually used for separations from

aqueous solutions but has been applied to gas phase separations.

Over a fairly wide temperature range, HMD will remove in excess of

99 percent of chlorine and bromine from the gas stream while passing greater

than 90 percent of the iodine. However, decontaminations of approximately

10 8 are required for radiobromine; hence, three or four passes are required.

The preliminary studies have been completed and work is commencing on the measurement of the 1-129 content of the SRM's 1648, Urban Particulate

Material and SRM 1572, Citrus Leaves. Samples of these SRM's have been

distributed to three other laboratories in the United States active in the

field of 1-129 analysis. It is expected that this round robin can be used

to certify the 1-129 content of the samples.

G. J. Lutz

7. Analysis of Human Liver for Baseline Lead and Thallium

The National Environmental Specimen Bank is involved in a pilot program

to monitor the effect of the increasing influx of anthropogenic sources of

trace elements on human health. To accomplish this, it is imperative to

collect accurate baseline data regarding the concentration of environmentally

important substances in the present population so that future changes can be

detected. Lead and thallium are two elements that are known to be toxic at

trace levels. To achieve the required levels of sensitivity and accuracy,

an isotope dilution mass spectrometric (IDMS) method was developed and

applied to tissue samples. Since the available samples were small (0.5 g)

and the expected concentrations low (1-5 ppb T1 ) , blanks for the procedure

would have to be extremely low. A method that accomplished these objectives

was developed using SRM 1577a, Bovine Liver, as a control sample.

A number of 0.5 g samples of this material were spiked with 206 Pb and

203T1, wet ashed using nitric and perchloric acids, and heated to remove

excess acid by evaporation. Lead and thallium were then simultaneously

separated by anodic electrodeposition as Pb02 and T1 2 0 3

. The mixed deposits were dissolved from the electrodes and their altered isotope ratios were determined by thermal ionization mass spectrometry. Thallium isotope ratios were measured first, at a low temperature (700 °C), and then lead isotope

ratios were measured at a higher filament temperature (1200 °C).

The results of the determinations of Pb on 0.5 g samples of SRM 1577a,

Bovine Liver, yielded an average value of 0.136 ± 0.012 yg Pb/g compared to

0.134 ± 0.08 yg Pb/g for one gram samples using a more extensive separation

60
technique (Pb only). The thallium concentration was found to be 3.1 ± 0.1 ng

Tl/g. Lead blanks for the procedure averaged 2.0 ng Pb and the thallium

blanks averaged 0.03 ng T1

Lead and thallium concentrations were then determined in thirteen

samples of human liver using the same procedure. The results are shown in

Table 7.

Table 7. Concentrations of Lead and Thallium and Their Relative

Concentrations Ratios

Sample ygPb/g nqTl/g Pb/Tl

1 4.38 1.70 2576

2 3.21 2.11 1521

3 2.15 1.85 1162

4 2.56 5.31 482

5 1.31 1.24 1056

6 1.11 6.24 177

7 2.83 1.02 2774

8 0.90 1.31 687

9 4.16 1.21 3436

10 0.71 7.07 100

11 3.41 1.32 2583

12 6.05 4.66 1298

13 1.15 2.16 532

SRM 1577 , Bovine Liver 0.134 3.1 43

Earth's Crust

3

20

Granite3

33

Shale320

Basalt3

40

3

Source - R. D. Reeve and R. R. Brooks, "Trace Element Analysis i Geological Material," J. Wiley & Sons, N. Y., NY, 1979, pp. 80-1

The results are interesting in that they show that while thallium

concentrations in human liver are in the same range as for bovine liver

(1-7 ng Tl/g compared to 3 ng Tl/g), lead in human liver is considerably

elevated over bovine liver (1-6 yg Pb/g compared to 0.1 yg Pb/g). This

increase becomes more evident when one compares the ratio of lead to thallium.

For most of the human liver samples, this ratio exceeds 1000/1 while the

ratio for bovine liver is near that of the earth's crust and various rocks,

20-40/1. This could be due to the fact that cattle are less exposed to

61
major anthropogenic sources of either lead or thallium. On the other hand,

humans are exposed to anthropogenic sources of lead but not of thallium. Thus

monitoring the trend of Pb/Tl ratios could be an indicator of the degree of

lifetime exposure to anthropogenic lead sources.

J. W. Gramlich, T. J. Murphy

8. Development of a Radiochemical Separation Procedure for Tin

Although tin has been shown to be essential for mammalian nutrition [1],

it can be highly toxic in some forms [2]. Unfortunately, tin cannot be

readily determined in biological materials because of the naturally occurring

low levels. For example, very few biological reference materials with known

tin concentrations are available. None of the eight NBS biological SRM's

issued have either certified or "information only" values for tin. Relatively

little reliable data concerning the tin concentrations in human and animal

tissues and fluids exists.

Neutron activation analysis can be used to determine tin in most biological materials at the naturally occurring levels if a radiochemical procedure

is used to separate tin from interfering elements and the background level of

radiation (noise) is reduced. Both the 113 Sn and 117m

Sn isotopes can be used

to quantify tin if the interfering 160Tb (for 113Sn) and 47Sc (for 11 ^Sn)

isotopes are removed. This has been accomplished with a separation procedure

based on the extraction of Snl 4 into toluene. The sample is initially

dissolved with nitric, sulfuric, and hydrofluoric acids along with hydrogen

peroxide, followed by a filtration step to remove precipitated oxides and

sulfates from the final sulfuric acid Solution before extraction into toluene.

Carriers are used to assure a quantitative recovery (>99.8 percent) and

maximize the decontamination.

Five samples of SRM 1571 (Orchard Leaves) have been analyzed by the above

procedure. The resulting preliminary value for concentration of 290 ± 17 (Is)

ng/g agrees favorably with two of the literature values (294 ± 16, 290 ± 20,

and 4100 ng/g) compiled by Gladney [3]. The resulting reduction in background

radiation was better than a factor of 1000, and no Sc or Tb could be detected

using other, more intense, y-rays, indicating decontamination factors of

>20,000 for Sc and >1000 for Tb.

Research is continuing to further improve this method. A small fraction

of the selenium, ^1 percent, accompanies the tin through the separation and can elevate the background around the tin peaks in some matrices. Therefore,

efforts will be directed at selenium reduction. Other SRM's with lower tin

concentrations, such as Bovine Liver (SRM 1577), will be analyzed to evaluate

the suitability of this procedure to provide certification quality data for new SRM's.

References

[1] Schwarz, K. ; Milne, D. B.; Vinyard, E. Biochem. Biophys.

Res. Commun. 40: 22; 1970.

62
[2] Schroeder, H. A. Environment 13: 18; 1971.

[3] Gladney, E. S. "Compilation of Elemental Concentration Data

for NBS Biological and Environmental Standard Reference

Materials," Los Alamos Informal Report LA-8438-MS (1980).

R. R. Greenberg

9. Development of a Fluorescent Glass Standard for Calibration of

Instrumentation Used for tbe Evaluation of Dye Penetrants

Fluorescent dye penetrant testing is used extensively for the non- destructive detection of flaws in a wide variety of test objects. As currently

practiced, the procedures lack both reproducibility and reliability both in

the dye application and development techniques as well as in the measurement

of fluorescence. Undoubtedly, at the present state-of-the-art, many components

with damaging flaws are now passed while others are wrongfully rejected.

In order to provide a valid basis for using fluorescent dye penetrant

testing as a reliable screening device, work has been undertaken to evaluate

uranium-doped glasses as comparative fluorescent standards for use in

standardizing instrumentation. Two types of standards are currently in different stages of preparation and evaluation. The first type consists of a single, rectangular piece of Corning 3750 glass mounted in a metal heat sink

that provides temperature stability of the glass during prolonged irradiation

periods. An engineering drawing of this assembly is shown in figure 13. The

main body of the metal block is type 2024 aluminum that has been anodized

flat black and the bottom plate is brass. The slot milled in one half of the

aluminum holder has been precision machined to provide a close fit with the

glass. Final positioning of the fluorescent glass, exactly flush with the

top of the holder, is accomplished under a microscope. It is subsequently

held in place by filling the 1 mm void between the bottom of the glass and

the brass plate with a black adhesive. Ten of these units have been built

thus far and are now undergoing extensive homogeneity and accelerated

stability testing. Initial measurements, obtained by mapping the surface of

these glasses in grid-fashion with a microspectrofluorimeter having a circular measuring aperture of 25 micrometers, indicate that the fluorescence

does not vary more than two percent.

In addition to the ten heat sink units, two other units modified for

water thermostating have also been fabricated. These will be used to

accurately measure the temperature coefficient of the uranyl fluorescence in

this particular batch of glass. As soon as the above studies are success- fully completed, these assemblies will be sent out to the manufacturers and users of fluorescent dye penetrants for further evaluation and comment.

A second type of standard in the early stages of design and production

employs glass fibers having various uranium concentrations and diameters in

order to obtain a graded series of fluorescent intensities and widths of

indication. Previously prepared fibers having nominal uranium concentrations

of 0.6 to 2.5 weight percent and diameters of 5 to 50 micrometers are being

considered for this purpose flj.

63
|4 50mm »|

2024 AL

Figure 13. Fluorescent uranium glass and heat sink assembly.

Present plans call for making two variations of these fiber standards.

One will have a fixed uranium concentration and various diameters that

approximate the widths of the indications commonly obtained in crack evaluation; the other will consist of a series of fibers having the same diameter

and various uranium concentrations. Each type will be sandwiched between two

nonfluorescent quartz plates with a transparent cement whose refractive index

closely approximates the refractive index of the fiber. The diameter and

relative fluorescent intensity of each fiber in a series will be specified.

The final production, characterization, and testing of these fiber standards

will form the main thrust of our effort in FY 82.

Reference

[1] Velapoldi, R. A.; Travis, J. C.; Cassatt, W. A.; Yap, W. T.

J. Microsc. 103: 293; 1975.

R. W. Burke, D. K. Hancock, R. A. Velapoldi

10. Determination of Halogens in Organic Liquids by Neutron Activation

Analysis

The technological usefulness as well as the environmental hazard of an organic liquid, especially an oil, is often directly related to its halogen

content. The partitioning of each halogen-containing component among the

various organic fractions of the liquid, in addition to being of scientific

interest, may point the direction toward effective purification. For these

reasons, an accurate and reliable means of halogen analysis over a broad

concentration range is desirable.

Organic liquids provide nearly ideal matrices for neutron activation

analysis since carbon, nitrogen, hydrogen, and oxygen produce no countable

radioactivity. Each of the halogens, on the other hand, produces an

64
activation product with its own unique half-life and gamma-ray energy, as shown in Table 8.

Table 8. Neutron Activation Products for the Halogens.

Element (N,y) Product Hal f-1 ife Gamma-ray Energies, keV

FI uorine 30

F 11.0 sec 1633.8

Chlorine o

CO 00 37.2 min 1642.2, 2167.6

Bromine 82Br 35.3 hr 554.3, 776.5, 1044.1 ..

Iodine 1 28 j 25.0 min 442.9

The short half-life of 20 F dictates accurate timing ability and for

that reason fluorine analysis has not been exploited routinely. On the

other hand, since the fluorine activity will decay away rapidly, its

presence at any level does not degrade the measurement of the other halogens.

Conversely, because it has the longest half-life, large amounts of bromine

will reduce the sensitivity for the other halogens, yet bromine can be

measured in the presence of any amount of them. In effect, the different

half-lives provide an automatic and complete "chemical separation" of

fluorine, bromine, and the other two halogens. Of course, since modern

gamma-ray spectrometry systems have energy resolution of better than 2 keV

(FWHM), the lines used for quantification are well resolved.

Significant progress has been made during the past year on the measurement of halogen concentrations in organic liquids. Among the several

developments are: (1) The reliable, accurate, simultaneous determination of

chlorine and bromine has been demonstrated in a variety of lubricating oils

as part of the ASTM/NBS basestock consistency study under the Recycled Oil

Program [1]; (2) The determination of total chlorine homogeneity in oils

doped with polychlorinated biphenyls (PCB) has been carried out in the

development of the PCB SRM-1581; (3) In collaboration with the Tribochemistry

Group of the Center for Materials Science, measurements have been made of

the chlorine and bromine contents of the saturated, polar, and aromatic

fractions resulting from the ASTM D2007 clay-gel separation of various

lubricating oils.

The dynamic range of the measurements can be from the ultratrace to the

major constituent levels. The measurement reliability demonstrated in the

basestock consistency work is ±3 percent (2a) relative uncertainty over

a twelve month period. Since the technique is generally non-destructive for

elemental composition, the sample can be available after analysis for

further measurement by this or other methods. Since the technique is nearly

matrix-independent and does not depend on the chemical species or on physical

properties such as viscosity, density, opacity, etc., it is well-suited for

the fractionation work. In summary, the increasing need for accurate,

sensitive, and unambiguous analyses of each of the halogens in organic

liquids has prompted the development of optimized activation analysis

techniques. The extension of this work to aqueous and other liquids will

broaden its impact beyond the important area of oils and liquid fuels.

65
Reference

[1] Frassa, K. "ASTM/NBS Base Stock Consistency Study," NBS

Spec. Pub. 584, p. 105 (1980).

R. F. Fleming

11 . The Determination of Trace Elements in Biological s and Injectables

A variety of biological and injectable product types are prepared and

used in the diagnosis, prevention, or treatment of hypersensitivity to such

factors as plants, pollen and food. As part of an extensive effort to

establish accurate baseline data to define the normal trace metal levels for

the variety of biological and injectable materials currently in use, a survey of 86 injectables of different types has been completed. The biological products or injectables included such materials as house dust, plasma,

normal serum, whole blood, meningococcal polysaccharide, yellow hornet and

honey bee venom, and tetanus, cholera, typhoid, rabies, and poliomyelitis

vaccines

.

Since the concentration of the 11 trace elements chosen for study was expected to be near the detection limits of atomic absorption spectrometry

(AAS) with electrothermal atomization, special chemical and instrumental

procedures were developed. The samples, stored under refrigeration, were

first allowed to come to ambient temperature. The sealed cap of each sample

vial was then removed in the plus 100 laminar flow clean room facilities in

CAC. Samples in the form of solids or powders were reconstituted as directed.

If the volume of the reconstituted samples was less than 15 mL, samples from

vials of the same lot were combined in a clean Teflon beaker. The samples

were placed in a hood and NBS purified acid was added. Digestion was carried

out on a hot plate and the resulting solutions were evaporated to approximately 1 mL. These solutions were cooled and transferred to suitable

volumetric flasks. The samples were then transferred to clean polyethylene

bottles prior to analysis. If the samples became cloudy on dilution with

water, they were redigested with HN0 3 , and the final acid concentration

adjusted to 20 percent HN0 3

. This high acid concentration was found to

stabilize the most difficult vaccine or plasma sample.

Biological matrices which have a relatively high concentration of Na,

Ca, or Mg are known to produce interelement effects on most analytes when

using electrothermal atomization with a graphite furnace. Graphite is a porous material that is easily penetrated by liquids and gases. Coating the

graphite tube with a thin layer of pyrolytic graphite greatly reduces the

effects of porosity and increases the sensitivity for some analytes. In

addition, interelement effects are further reduced by matrix modification

and the application of the L'vov platform, a small graphite platform placed

inside the absorption cell. This platform reduces analytical interferences

by allowing volatilization of the sample into a higher gas temperature than

is possible without it.

66
The analytical results obtained for these materials are summarized in

Table 9. Since similar SRM's were not available, the method of single

standard addition along with close bracketing of unknowns with standards was used to check the recovery of the analyte. The results of this study will be

used to develop candidate reference materials having suitable matrix characteristics and requisite trace metal compositions. When characterized, these

standards will serve as a control or quality assurance standards for the

determination of trace metals in biological and injectable materials.

Table 9. Concentration Range of Trace Elements in

FDA Biologicals and Injectable Materials.

Element Concentration Range, yg/mL

A1 0.02 - 250

As <0.01 - 0.6

Ba <0.01 - 1.0

Cd <0.005 - 0.04

Co <0.003 - 0.04

Cr <0.005 - 0.2

Hg <0.001 - 45

Pb <0.005 - 0.5

Se <0.01 - 0.1

T1 <0.02 - 0.06

Zn <0.05 - 50

Reference

[1] Dean, J. A.; Rains, T. C. Flame Emission and Atomic Absorption

Spectrometry , Vol. 3, Elements and Matrices, Marcel Decker, 1975.

T. A. Butler, E. J. Maienthal, T. C. Rains, T. A. Rush

12 . Application and Evaluation of High Sensitivity Mass Spectrometry for

Isotopic and Elemental Abundance Measurements of Uranium and Plutonium

The certification of materials for low-level or ultra-trace constituents

has become increasingly important to satisfy both present and future needs

for quality assurance in critical segments of industry, public health, and

environmental monitoring. The use of microchemistry combined with pulse

counting mass spectrometry results in the requisite sensitivity for the

determination of ultra-trace components from complex materials. Under clean room conditions, it is possible to separate an element from a few milligrams

of starting material and to determine the isotopic composition and elemental

concentration with a high degree of accuracy. The feasibility of high

accuracy measurements at the ultra-trace level has been demonstrated for the

67
elements U and Pu using new and innovative microchemical procedures coupled

with high sensitivity isotope dilution mass spectrometry (ID/MS). Two recent

applications which clearly demonstrate the capability of this technique are a round robin exercise to determine the isotopic composition of nanogram

quantities of U and Pu and the determination of U in Bovine Liver, SRM 1577a.

Research has been conducted at NBS as well as laboratories in the

nuclear industry to develop the ability to analyze accurately and precisely

nanogram quantities of U and Pu for isotopic composition. These data are essential to account for Pu and U throughout the nuclear fuel cycle and to

detect diversion if it should occur. The resin bead technique in which

several nanograms of both U and Pu have been extracted from dilute reactor

dissolver solutions provides the matrix for physical transport from reactor

to laboratory and is directly analyzable by mass spectrometry. To assess

the state-of-the-art for high sensitivity mass spectrometry in the nuclear

community, resin beads containing U and Pu separately, as well as both U and

Pu were prepared, distributed, and analyzed as part of a "round robin".

The results for one of the low level uranium unknowns containing

238y.235y.233y about 10:1:1 can serve to illustrate some of the information

gained. A minimum of four replicate measurements were made of this sample by

each laboratory with an average precision of 0.12 percent for the 235 y/ 238

y

ratio and 0.25 percent for the 233y/238y ra t-j 0 (i CT 0 f mean). The relative

standard deviations of the means (measured by the six participating laboratories) were 0.18 percent and 0.26 percent for the 235y/238y ra tio and

233 y/ 238 y ra tio, respecti vel y . If the measured 233 y/ 238

y ra tio were used as an internal standard to correct the 235y/238y ra tio for fractionation, the

am

of the latter ratio is substantially reduced to 0.05 percent. This

suggests that the primary cause of intralab and interlab variation is lack

of control of isotopic fractionation. The results reported here using

nanogram samples are comparable with those reported in the more extensive

round robins, IDA-72 and SALE, where microgram samples were analyzed using

triple filament thermal ionization and Faraday cup detection.

The expertise gained from resin bead research and measurements has been

applied to the determination of U in SRM 1577a, Bovine Liver (freeze dried,

powder form). This sample was chosen because it contains one of the lowest

U contents (^700 pg/g) of any biological SRM. Because U is a biotoxin, the

ability to measure its concentration at low levels in subgram samples with

high precision and accuracy is essential for establishing natural levels and

detecting anthropogenic contamination. A procedure has been developed for

the determination of picogram quantities of U by isotope dilution mass spectrometry using artifically produced 233 U (SRM 955) as a spike.

Typically 0.5 g of liver was decomposed using nitric and perchloric

acids. The U in an aliquot of known weight containing 0.1 - 0.2 g equivalent

of liver or about 10Q pg

238 U was chemically purified on two small anion

exchange columns. The chemically separated U is loaded onto a single anion

bead which is transferred to a rhenium v-shaped filament and loaded into the mass spectrometer. The ionization efficiency for U loaded in this manner is

about 0.2 percent. Therefore, 100 pg

238 U will yield an ion current of 10 4 ions per second for several hours which is sufficient for 0.1 percent precision.

68
However, the fundamental limitation on accuracy and precision is the magnitude

and uncertainty in the chemical blank. Note that to determine 100 pg of U to an accuracy of 1 percent requires the variability in the blank to be less

than 1 pg or 2.5 x 109 atoms 238 U. The chemical blank consists of (J which is

not indigenous to the sample. It can be considered as arising from three*

sources, each of which must be evaluated separately: 1. Dissolution blank - includes U from reagents and container (60 mL Teflon beaker) used for dissolution; 2. Column blanks - includes U from reagents, resins, and quartz ion

exchange columns; 3. Loading blank - includes U from the source that is

indigeneous to the bead and filament material. Four loading blanks were

determined and ranged from 12-40 femtograms 238 U. Single determinations were

made on all reagents used in the chemical separation. The total U added to

the chemical separation from these sources is 2.5 pg. Since 0.5 g of sample

contains about 350 pg of 238 U, the contribution from this blank is less than

1 percent. The major source of blank is the column blanks because aliquots

of 0. 1-0.2 g of sample or about 100 pg

238 U are passed through the chemical

separation. Ten column blanks have been measured and ranged from 2. 4-5. 2 pg.

Figure 14 is a graphical representation of U determinations on SRM

1577a. The figure illustrates four important points: (1) Duplicate determinations on a single aliquot agree within the stated uncertainty which is

typically 1.5 percent; (2) Aliquots of different sizes agree within the

stated uncertainties indicating that the chemical separation and mass spectrometric procedures as well as the data reduction are valid; (3) All

determinations agree within the stated uncertainties indicating SRM 1577a is

homogeneous to about 1 percent for 0.5 g samples; (4) Small quantities of U

(M0 11 atoms 238 U) can be chemically separated in high yield and determined

by pulse counting with an overall uncertainty of about two percent.

As can be seen from the extensive effort to identify and measure the sources of blank for analysis of Bovine Liver, clean and efficient chemical

separation procedures are necessary. In addition, the mass spectrometric

analysis requires extreme care in the prevention of contamination and an understanding of the nature of isobaric interferences and their prevention as well. The need to determine pi cogram quantities of critical elements in

small samples of organic and inorganic materials will undoubtedly increase in

the near future since their presence can markedly alter both chemical and

physical properties and affect the biochemistry of plants and animals. The

techniques described in this report should be applicable to other elements

with comparable success.

J. D. Fassett, W. R. Kelly

69
-5 5

Figure 14. Graphical representation of

concentration data. Dots

represent a single determination and its associated

error (2a). Legend on right

indicates bottle number,

letter denotes aliquot, and

decimal number denotes

replicate determination on aliquot. The middle vertical

line represents the mean of

the mean values for all

samples, which is 703.8 and

the outer lines represent 2a , which is 4.3 or 0.61 percent

1!1

% Deviation from mean

-3 -10 1 3

680 700

238

720

u pg/g

l

3A.1

3A.2

3B.1h

3C.1

3C.2

4A.1

4A.2

5A.1

5B.1

5B.2

6B.1

6B.2

13. Development of Improved Matrix Modifiers for Use in Atomic Absorption

Spectrometry

Atomic absorption spectrometry (AAS) is a widely used analytical technique

for the determination of metallic elements. Since AAS is a relative technique, a quantitative determination can only be carried out by comparison to

a reference solution. If the behavior of the sample is different than the

reference solution, it is implied that there is an interferent. Depending

upon the cause, the interference can be classified as chemical, physical,

background or spectral. While background and spectral interferences are based on the measurement of non-specific signals, chemical and physical

interferences have an influence (positive or negative) on the total number of

atoms formed per unit volume of the absorption cell. The most common interferences encountered in the analysis of biological tissue, environmental

samples or food samples are of the chemical variety. The interferences

encountered in flame sources for the production of atomic vapor in AAS are generally understood and methods have been developed to alleviate them.

However, in electrothermal atomization, the process is not clearly understood

and severe interference effects are encountered. Since the concentration of

many analytes are below the detection limits of flame AAS, electrothermal

atomization is used routinely because of its increased sensitivity.

70
In electrothermal atomization, controlling the sublimation of the analyte

during the processing step is of major importance. Since the atomization of a sample in a graphite tube furnace can only take place from the graphite surface,

it is essential that the sample remain in intimate contact with the hot graphite

surface for as long as required for complete atomization. In contrast to

flame AAS, the formation of sulfate, phosphate or oxides in the graphite tube

is often advantageous.

A number of publications have described matrix modification procedures by

which analyte losses during the preatomization stage with electrothermal

atomization may be minimized or eliminated [1-3]. In general, the methods

developed are for specific analytes and matrices. The absorption signals for

AI , As, Be, Cd, Co, Fe, Ni, Pb, Sb, and Se in AAS with electrothermal atomization are severely suppressed in matrices that contain relatively high concentrations of Na, Ca, and/or Mg (e.g. human tissue or serum). This suppression

has been observed to be as high as 100 percent for Cd and Pb in 1:5 aqueous

dilutions of sera.

In an attempt to minimize or eliminate analyte response suppression, a series of experiments was conducted to evaluate HN0 3 , HC1 , HC 104 , H 2 S04 , H 3 PO4 , K2 Cr 2 0 7 , ammonium orthophosphate [ (NH 4 ) 2 HP04 ] , and ammonium sulfide as matrix

modifiers. In general, a one percent nitric acid solution was found to give

the best precision and accuracy when the total solids in the samples were low. A one percent solution of (NH4 ) 2 HP04 and HN0 3 was the most efficient matrix

modifier for Cd, Co, Fe, Pb, and Ni in a variety of matrices. Several series

of solutions of low alloy steels (SRM's 364 and 1269) were prepared with and

without a one percent solution of (NH 4 ) 2 HP04

. Lead recoveries of 100 percent

were obtained from solutions with phosphate present while only 50 percent

recovery was obtained from solutions without phosphate. Matrix modifiers

which have been found to alleviate the largest number of interferences in AAS

with electrothermal atomization are listed in Table 10. While phosphate was found to alleviate interferences for many analytes, it was found to have an adverse affect on As analyses. A similar effect was observed for Se.

While a universal reagent for matrix modification in AAS has not been

found, the knowledge obtained in this study has led to an improvement in the

precision and accuracy of the analysis using AAS of trace elements in a wide

variety of materials. Presently, a study is underway to evaluate the effect

of combining (NH4 ) 2 HP04 with various organic compounds as a new approach to

improved matrix modification.

References

[1] Ediger, R. D. At. Absorpt. Newsl. 14: 127; 1975.

[2] Shum, G. T. ; Freeman, H. C.; Uthe, J. F. J. Assoc. Off.

Anal. Chem. 60: 1010; 1977.

[3] Hinderberger, E. J.; Kaiser, N. L.; Koirtyohann, S. R. Atomic Spectros. 2: 1; 1981.

T. A. Butler, T. C. Rains, T. A. Rush

71
Table IQ. Matrix Modifiers for AAS with Electrothermal Atomization.

Analyte Material

s

Matrix Modifier

Cd, Pb Natural Waters

Leachates

Human Tissue and Serum

Ores

Air Particulates

FDA Injectables

Solution of

(nh4

) 2 hpo

4

Fe, Ni, Co Au Stripping Solution

Human Serum

FDA Injectables

1 % Solution of

(nh

4

) 2 hpo

4

As, Se All Materials 1000 yg Ni/mL

A1 Human Tissue and Serum 0.5% H

2 S04

Be Natural Waters 25-50 yg Ca/mL

Sb Air Particulate 1% Solution of

(nh

4

) 2 s

Sn All Materials 10% HC1

14. Development of Silica-Gel Procedures for the Analysis of Trace Quantities

of Copper and Nickel

In recent years, the need to accurately determine elements at trace

level concentrations in environmental, biological, and industrial samples has

become critical. As a result, a number of isotope dilution procedures, which

were once considered to be state-of-the-art, have become obsolete. This was

the case for the procedures used for the determination of copper and nickel.

Both procedures required large amounts of sample while yielding low to

moderate signal intensities, thus limiting the sensitivity of the measurement. In addition, the chemical separation procedures which had been used to

prepare the samples yielded blanks which were sufficiently large and variable

to cause significant error at the sub-microgram level. The need to determine

nickel in human liver samples for the National Environmental Specimen Bank

ultimately led to the development of improved analytical procedures for both

nickel and copper. The nickel was separated from the matrix elements by

electrodeposition from ammonical solution, instead of by the previously used

dimethyl glyoxime solvent extraction procedure, which led to a three-fold

reduction in the analytical blank. The mass spectrometric sample mounting

procedure utilizes a single filament silica gel technique. This procedure,

which involved drying sequential layers of silica gel, sample, and phosphoric

acid onto the surface of a platinum filament, was a direct outgrowth of the

method developed for the determination of the atomic weight of silver. The

72
basic sample mounting procedure was followed by a high temperature drying

step where the filament temperature was rigidly controlled by use of an optical pyrometer.

During the analysis of nickel in human liver, it was observed that the

small amount of copper which remained after the separation gave an intense

ion beam. Slight modification in both the sample mounting technique and the

analysis procedure, led to a new silica gel procedure for copper which

yielded a four-fold increase in signal intensity with a twenty-fold reduction

in sample size.

As a result of this research, the elements copper and nickel can be

determined at the submicrogram level with improved accuracy. This increase

in both sensitivity and accuracy can now be used to facilitate the determination of these elements in Standard Reference Materials, as well as in the

large number of other standards and samples which require the analysis of

trace quantities of copper and nickel.

K. A. Brletic, T. J. Murphy, L. J. Powell

15. Research to Develop High Accuracy Coulometric Assay Methods for Uranium

Metal and Uranium Oxides

Over the past few decades, accurate analysis of uranium metal and

uranium oxides (mainly U 3 0 8 ) has assumed great importance. The nuclear

reactor industry requires accurate assays of uranium metal in reactor fuel

rods, while fuel rod manufacturers who handle isotopically enriched, and

therefore very expensive material, require accurate assays of U 3 0 8

. Nuclear

waste management and radiation public health regulations mandate accurate

accounting and radiation fuel mass balance, which in turn necessitates

accurate analyses of uranium. For its part, the National Bureau of Standards

has issued Standard Reference Materials of certified purity (SRM 960 Uranium

Metal and SRM 950 Uranium Oxide) to assure measurement comparability and

traceability both nationally and internationally. Considerable research has

been conducted at NBS to improve the methods of uranium analysis to better

meet the more exacting demands imposed by industry, government, and society

at-large.

In the last ten years, a control led-current coulometric method for

uranium assay, based on electrogeneration of titanous ion at a platinum

cathode with subsequent reduction of uranium(VI) to uranium(IV) has been

developed and refined at NBS. This past year, a major effort was launched to

investigate and correct the deficiences of the method which have limited the

precision of the assay to about 70 parts per million (relative standard

deviation). These deficiences include electrode poisoning, current inefficiences, and slow rates of reaction.

To gain a clearer understanding of electrode poisoning and the resultant

loss of current efficiency, a detailed study of the electrogeneration of

titanous ion in several electrolytes using different electrode materials was undertaken. Plots of current density versus electrode potential were

73
constructed from which the current efficiency was computed. The effects of

electrolyte composition and electrode material on the reaction rate of

uranium(VI) with titanium(III) were also monitored.

This research has led to the development of u new procedure for the

coulometric assay of uranium using a mercury-pool cathode and a supporting

electrolyte containing 9 mol/L sulfuric acid and 0.2 mol/L titanyl sulfate.

With this procedure, one gram samples of uranium have been titrated with a precision and accuracy of 30 parts per million (relative standard deviation).

This represents a considerable advance over the previous coulometric

procedures and offers distinct advantages over the Davies-Gray procedures in

the form of smaller sample size by a factor of two to three, increased

precision, and fewer operations. Furthermore, the coulometric method is

absolute, based directly on the Faraday constant, and not tied to other

chemical standards. Work is continuing to refine further the procedure with

particular attention being paid to identifying a catalyst to increase the

rate of reaction near the equivalence point of the titration.

W. F. Koch, G. Marinenko, T. Tanaka

16. Development of a High Precision Method for the Assay of Milligram Samples

of Uranium

For more than twenty years, NBS has maintained a set of 18 uranium

isotopic SRM's which cover in detail a 235/238 isotopic ratio range from less

than 0.01 to approximately 200. In this respect, the uranium isotopic SRM's are unique and are utilized both nationally and internationally to calibrate

instrumentation for the elemental and isotopic assay of uranium in the

nuclear fuel cycle. The current level of certification for the major isotopes

of these materials is inadequate for present and projected nuclear safeguards

requirements . A primary obstacle to improving the accuracy of these materials

has been the inability to assay mg quantities of highly enriched or depleted

separated isotope solutions which are then utilized to prepare standards of

known composition for instrument calibration.

The goal of this research project was to develop a method for the high

precision assay of 25-100 mg of uranium (separated isotope solutions) by a modified Davies-Gray titration technique. Under normal conditions, the

Davies-Gray is capable of high precision/high accuracy assay of 5 in 10 5

(1 standard deviation). However, to achieve this level of precision, at

least 2-3 g of material is required for each analysis. Since large quantities

of uranium separated isotopes are expensive, scarce, and in some cases, a radiation hazard, there is an acute need to develop a high precision assay

utilizing less than 100 mg of sample per analysis. When this work was initiated, no method existed which was capable of yielding an uncertainty

less than Q.01 percent for measurements on a sample of less than 100 mg.

A manual titration procedure has been developed, employing essentially

the same techniques as the standard Davies-Gray titration. However, the

precision of this new method, for a 100 mg sample, is nearly as good as would

be determined from a two to three gram sample by the conventional method.

Alternatively, samples of 10 mg or less might be titrated to the 0.05 percent

74
precision level of the standard Davies-Gray titration. The usefulness of

such an improvement in sample size requirement is obvious but equally

important are the facts that no significant changes in equipment and chemistry

are required.

These improvements were achieved through the methodical study of the

effects of various parameters upon the titration and through the application

of improved techniques to the basic method. The more significant changes are briefly described and explained below. First, a more stable and more sensitive

digital millivolt meter was substituted for the conventional pH meter for

end-point indication. Second, blanks and titrations were studied as a function of total reagent volumes and, as a result, a miniaturization of the

titration was achieved with minimum inconvenience and maximum benefit (endpoint sensitivity). Improved methods of dichromate reagent addition were developed to assure accuracy in the consumption of this primary standard

titrant. The result of these and other improvements is a weight titration

using 1/2 scale of all normal reagents. For samples of 100 mg, within set

precisions of better than 0.006 percent have been achieved.

The initial objective of this research, a highly precise assay capable

of assaying milligram quantities of uranium in separated isotope solutions,

has been accomplished. Although a consistent bias of -0.09 percent is

observed for a sample size of 25-150 mg, this will not hinder the preparation

of accurate calibration standards from two master solutions of uranium

separated isotopes. With the potential for preparing more accurately known

standards, it is now possible to make measurements which will lower the

uncertainty in the certification of the uranium isotopic SRM's to a level

which addresses the needs of the nuclear industry. With additional research,

the method could be modified to eliminate the bias. Either a modified method

or the high precision method shows promise as an alternate method for routine

assay of uranium in the nuclear fuel cycle. The widespread use of such a method to replace the more classical Davies-Gray titration would conserve the

large amounts of uranium that are now expended for assay purposes.

J. R. Moody

17. Research to Develop ID/MS for Trace Concentrations of Vanadium

There have been few SRM's certified for vanadium due to the extremely

low levels of this element in most natural, biological and environmental

materials (excluding fossil fuels). Many cases of vanadium toxicity have

been reported as connected with the use of fossil fuels [1]. It is significant that the most concentrated natural sources of V are fossil fuels such

as oil and coal; in oil, it is often the major inorganic component. Vanadium

is also ubiquitous in industry in the form of ferro-vanadium alloys or other

species used in dozens of processes as the major catalyst. The development

of an isotope dilution mass spectrometric (_ID/MS) procedure to analyze

vanadium will enable NBS to certify this important element in a large variety

of requested materials.

75
The first high accuracy measurement of vanadium by ID/MS was completed

during the year on proposed SRM 1634a, Trace Elements in Fuel Oil. The newly

developed chemical and mass spectrometric methods were applied initially to

this SRM because of its relatively high vanadium concentration (>50 ppm).

Future efforts will be directed at the ultra-trace level.

In developing the chemical procedure for determining vanadium by isotope

dilution, extensive research to decontaminate the spike material ( 50 V) was necessary. The isotope obtained for the spiking was found to be unsuitable

in its initial condition due to contamination by potassium and other elements.

A separation technique was developed to purify the 50 V isotope which also was tested for the removal of isobaric interferences; specifically, the mass 50

isotopes of titanium and chromium.

Before precise isotope ratio measurements were made, a thorough investigation of the various modes of thermal ionization was completed. Studies of

the ionization patterns and efficiencies of vanadium revealed distinct

differences between several pretreatment methods and between different

molecular forms. The final form chosen for loading the sample onto the mass spectrometer filaments was vanadium oxychloride; V0C1 3 is believed to be its

major constituent. This is produced by final treatment with HC1

0

4 and HC1

and filament drying with heat, in air.

The chemical separation of vanadium from other metals was based on formation of the peroxide complex and cation exchange chromatography. The

peroxide complex prevented the ion exchanging of vanadium while reducing

chromium to its trivalent state which was bound as were the other metals by

the ion exchange column. The chemical separation, sample preparation and

final vanadium species adjustment were done under Class 100 clean room conditions. This procedure was found to produce blanks below 1 ng while

eliminating the chromium and titanium present at comparable concentrations.

During this separation, approximately 20 specific elemental components,

present at lower concentrations in the fuel oil matrix also were removed. A

series of oxidative steps, employed as a pretreatment, resulted in a sample

having uniform characteristics for mass spectroscopic analysis.

The mass spectrometry procedure developed for vanadium employs a rhenium triple filament ion source. Approximately 1 yg of vanadium supplied

as the oxychloride in 10 percent hydrochloric acid is dried onto each of the

two sample filaments. The vanadium is then heated in air to approximately

750 °C to convert it to a black oxide (probably V

0

2 or V2 0 3 ). A major effort

has been required to minimize the isobaric interference at mass 50 resulting

from chromium. Chromium is present in the mass spectrometer source components

and in the rhenium filament material. The chromium background for vanadium

analyses has been reduced by more than an order of magnitude during the past

year. Among the techniques used to reduce the chromium background are: use of zone refined rhenium which is acid leached prior to filament fabrication,

and use of tungsten posts to hold the filaments rather than the normally used

stainless steel. Although initial vanadium measurements have been at

relatively high concentrations, the sensitivity of the technique will allow

high accuracy determinations of vanadium concentrations at the sub-ppm level.

This is particularly important in view of the discrepant data which has

appeared in the literature in recent years regarding the concentration of

vanadium in botanical and environmentally related materials.

76
Reference

[1] "Vanadium," Medical and Biological Effects of Environmental

Pollutants Series, Committee on Biological Effects of Atmospheric

Pollutants, National Academy of Sciences, Washington, DC (1974).

J. W. Gramlich, H. M. Kingston

18. Investigation of Ionic Chromium Speciation

Chromium is present in a wide variety of materials, including plants

and minerals, industrial metal products, and waste effluents. It is an important trace metal that is both essential and toxic, depending on its

valence state and concentration [1]. Consequently, its determination has

been a subject of continued research for several decades.

Since studies have established that the tri valent form of chromium is

relatively harmless and that the hexavalent form is toxic, special efforts

have been undertaken to distinguish between the two valence forms of chromium

present in food and water. Anion exchange chromatography has been used to

separate Cr ( III) from Cr(VI); AAS then was used to measure Cr ( III) in the

column effluent [2]. Total chromium was measured by AAS in a portion of the

sample that had not been passed through the column and Cr(VI) then was determined by difference [2]. Solvent extraction has also been used to

separate Cr ( III) and Cr(VI). Ammonium pyrolidine dithiocarbamate (APDC) is

used to chelate Cr ( VI ) and the complex is then extracted into methyl isobutyl

ketone. Atomic absorption spectrometry was used to determine Cr(VI) in the

extract [3]. Chromium(III) can be coprecipitated from water samples with

Fe ( III) hydroxide. In another method, Cr(VI) is separated by coprecipitation

of lead chromate with lead sulfate in a solution of acetic acid. Numerous

other analytical techniques, yielding limited success, have been described

in the literature [4].

With the increased interest in ionic chromium speciation shown by the

Office of Standard Reference Materials and the Office of Environmental

Measurements, an evaluation of several analytical techniques for determining

Cr ( III) and Cr ( VI ) was undertaken. The first technique studied was an anion

exchange procedure. The aqueous samples were made 1 mol/L in HC1 and then

introduced onto a gravity-flow column. The Cr (III) was eluted from the

column with 1 mol/L HC1 while the Cr(VI) was adsorbed. After the Cr (III) was eluted from the column, a solution of 0.01 mol/L ascorbic acid in 0.01

mol/L HC1 was added to reduce the Cr(VI) to Cr ( III) directly on the column.

The newly-formed Cr ( III) species was then eluted from the column and AAS was used for online detection of Cr ( III), now representing the Cr(VI) content.

Since the direct measurement of Cr(VI) is of major interest, a study

was conducted using Chelex 100 resin. In the initial study, 50 yg of Cr(VI)

and 50 yg of Cr ( III) were transferred to a beaker and the pH of the solution

adjusted to 5 with pH 5.5 acetate buffer. The solution was transferred to

a 1x7.5 cm ion-exchange column containing Chelex 100 resin, 200-400 mesh

size (sodium form). Water was added to the column and 10 mL portions of the

effluent were collected. Each test portion was then analyzed for Cr by

flame AAS. After the Cr (VI) was eluted, the eluent was changed to 3 mol/L

77
HC1 to elute the Cr(III). Complete recovery of Cr(VI) was obtained in 50 ml. of eluent while Cr(III) showed extensive tailing with 95 percent recovery

after collecting 70 mL of effluent. Since our interest is Cr(VI) at the

nanogram level, the experiment was repeated using 50 ng of each of Cr(VI)

and Cr(III). The analysis of the effluent was made by AAS with electrothermal atomization. With these nanogram amounts, the Cr(VI) was completely

eluted in 25 mL of effluent with no detection of Cr (III).

The utility of the procedure was evaluated using two leachate samples from

solid waste and two samples of water taken from the pond located on NBS

grounds. Each sample was analyzed as described. No Cr(VI) was detected in

any of the samples. The experiment was repeated after each sample was spiked

with 25 ng of Cr(VI) and allowed to stand for 12 hours. The recovery of

Cr(VI) from the pond water varied from 0 to 30 percent with recoveries of 70-80

percent from the leachates. This result, coupled with the total recovery of

Cr (VI ) in the last experiment, suggests that Cr(VI) is being reduced by

species present in the water. Additional studies are being planned to

determine the stability of Cr(VI) in various types of aqueous media.

References

[1] Mertz, W. "Chromium and Its Relation to Carbohydrate

Metabolism," Symposium on Trace Elements, Medical Clinics

of North America, 60, 739 (1976).

[2] Cresser, M. S.; Hargett, R. Anal. Chim. Acta. 81: 196; 1976.

[3] Bergmann, H. ; Hardt, K. Z. Anal. Chem. 297: 381; 1979.

[4] Slavin, W. Atomic Spectrosc. 2: 8; 1981.

B. E. McClellan, J. D. Messman, T. C. Rains

19. Transfer and Analysis of Inductively Coupled Plasma (ICP) Emission Data

Using a Mini- and a Main-Frame Computer on the NBS Data Network

Two major sources of systematic error in the ICP technique can limit

the accuracy of analyses. The first is spectral interferences which are caused by spectral line overlap, and the second is matrix effects which are caused by the presence of various constituents in the sample itself. Approaches

to minimizing and correcting for these effects have been developed in this

laboratory. However, they cannot be immediately put to use without improved

computing capability. Spectral line selection requires the use of the ICP

minicomputer and microphotometer which is located outside of the ICP laboratory. Data acquisition for the matrix effect studies is accomplished by the

ICP minicomputer, but the analysis and result calculations are most efficiently

handled by the NBS main computer. In both cases, communication links and

protocols had to be developed to enable remote usage of the ICP minicomputer

and data transfer to the NBS main computer.

78
The procedure for identifying and selecting spectral lines involves the

examination of a photographic plate on the microphotometer. This instrument

has been modified to provide linearly encoded distance measurements in order

to characterize the spectral plate dispersion. Lines of known wavelength

are paired with their respective plate positions. A parabolic-fitting

program is used to calculate the plate dispersion. New line positions can then be used to calculate unknown wavelengths or unknown line positions can

be calculated for known wavelengths to identify intended analysis lines.

The interactive nature of this process made it necessary to establish multiuser capability on the minicomputer and to provide a remote terminal at the

microphotometer. This was accomplished by installing an additional interface

board in the computer and connecting both the interface and the remote

terminal to the NBS Data Network.

The existence of matrix effects in the ICP technique has been recognized

in this laboratory and steps have been initiated to eliminate or reduce them.

Their presence is significant when applying the technique to the high-accuracy

analysis required for the certification of Standard Reference Materials. In

order to characterize the extent of matrix effects for ten elements in a typical sample, the experiment would generate 5,000 raw data points and require

2,500 calculations for each matrix type. The best approach to analyze such a data set is to use the OMNITAB package which is supported on the NBS main

computer. During the experiment, data are automatically stored on the ICP

minicomputer data disc. Transfer of these data from the disc to the NBS

main computer involved extensive software development to connect the two

computers on the NBS Data Network. The connection actually employs the NBS

microcomputer as an intermediate device for temporary data storage.

Both the line identification and the matrix effect experiment take

approximately one-third the time previously required. Furthermore, incidences

of error in line identification and calculation have been virtually eliminated. These steps in interactive computing and data analysis have greatly

increased the efficiency of the set-up procedures for ICP simultaneous

multielement analysis.

R. L. Watters, Jr.

20. Evaluation of Sources of Error in D.C. Plasma Spectrometry

The Direct Current Plasma (JDCP) is a relatively new analytical emission

source in the Division. Within a relatively short time span, this source,

in combination with an echelle spectrometer, has been applied to trace

element determinations in a variety of complex matrices in support of programs

such as Nuclear Waste, Recycled Oil, and Standard Reference Materials. In

addition to this analytical role, research has heen conducted to evaluate the

factors that influence precision and accuracy for the purpose of developing

improved instrumentation and analytical methodologies. Most of this research

has concentrated on studies of noise (which affects detection limits and

precision) and interferences (which affect accuracy).

79
A study of some twenty elements has indicated that detection is limited,

under the high spectral resolution conditions used, by a combination of

photomultiplier dark current noise and plasma background emission flicker

noise. These are fundamental limitations meaning that improved detection

limits can be most simply obtained by increasing signal strength rather than

reducing noise.

Precision at high concentrations (at least two orders of magnitude

above the detection limit) is defined by analyte emission flicker noise

resulting from the sample transport system along with any temperature or vibration-induced wavelength drift of the spectrometer. We have somewhat

reduced wavelength drift through thermal stabilization of the spectrometer.

As a consequence of these studies, it is clear that the most direct

method to improve detectability and precision involves improvement of

sample transport efficiency and stability. To this end, alternate sample

introduction systems, including ultrasonic nebulization and discrete sample

injection, are being investigated.

Additive interferences resulting from spectral line overlaps and multiplicative interferences, produced by elemental interactions in the plasma

excitation volume, have proven to be the major limitations to analytical

accuracy in that they both influence the relationship of standard and sample

emission intensities. Spectral line width studies of the DCP indicate that

the echelle resolution, using the minimum slit width available, provides the

optimum spectral discrimination possible (i.e., the half-widths of broadened

spectral lines are approximately the same as the minimum spectral bandpass

of the echelle). This means that further improvement in spectrometer

resolution is useless and that reduction of spectral interferences must be

based on refinement of background-correction techniques.

Studies of multiplicative interferences resulting from interelement

effects in the DCP present an extremely complex picture, with interferences

being dependent on the observation area as well as the identity of the

interacting elements. Buffer solutions, such as lithium chloride, have

proven to be of some use in the reduction of interelement effects, but their

effect appears to be highly dependent on acid concentration. The result of

this study has led us to the use of a procedure combining matrix-matching of

acid concentration, a lithium buffer (1000 pg/mL), and single-point standard

addition.

The recent acquisition of two multielement cassettes has directed our studies towards problems in the application of the DCP to simultaneous

multielement analysis, the eventual goal being the development of a system

capable of high accuracy work. The primary problem which must be overcome

is the detection and correction for spectral interferences on a multielement

basis.

C. G. Blundell, M. S. Epstein

80
21 . Research to Develop Acid Rain Reference Materials

Within the last decade, the phenomenon of acidic precipitation has

attracted increased attention both on the national and international fronts.

The Inorganic Analytical Research Division, primarily in support of the

United States Environmental Protection Agency and the United States Geological

Survey, is taking an active role in the study of acid rain. This effort has

focused on analytical chemistry to ensure quality assurance, measurement

comparability, and consistency throughout the nation. Since 1975, NBS has

prepared and analyzed four series of reference materials to be used for the

chemical analysis of natural precipitation samples. These samples have

provided a means of intercalibrating atmospheric monitoring stations. These

solutions are also being monitored for stability, primarily with regard to

pH and conductivity. To improve the stability, alternatives to the present

use of glass ampoules for the storage of these solutions are being investigated. In addition, research is being conducted to improve the measurement

of pH and acidity in low conductivity, unbuffered solutions, such as encountered with acid rain.

In the past year, investigations have revealed serious problems in the

measurement and subsequent interpretation of pH in acid-rain-like solutions.

It is well known that the customary arrangement for measuring pH (glass/

reference electrodes) measures not a single quantity (i.e., hydrogen ion),

but rather a sum of potentials. The "unwanted" potentials include asymmetry

potentials, liquid junction potentials, streaming potentials, and several

others related to the non-ideal behavior of the solution and of the electrodes.

Insofar as these potentials are constant between standards and unknowns,

they can be electronically offset and therefore, cause no major problem.

Such is not the case in acid rain solutions which are unbuffered and low in

ionic strength. Data have been obtained revealing residual liquid junction

potentials which can easily bias the pH reading by 0.1. Because of this

bias, fundamental interpretation of the pH number of such solutions in terms

of hydrogen ion is totally impossible.

In a related way, the measurement of total acidity, in solutions of

extremely low acidity, is beset with potentially serious errors. Experiments indicate that these errors result from a combination of the manner in

which the end-point is determined and the effects of dilution.

The impact of these findings is clear; the discipline of analytical

chemistry has not kept up to the demand in regards to this far-reaching

environmental phenomenon. Research is underway to develop new standards and

measurement protocols intended to ensure measurement quality and comparability,

as well as to gain a better understanding of the problems encountered in the

measurement of pH and acidity in acid rain solutions.

W. F. Koch, G. Marinenko, J. W. Stolz

81
22. Design and Implementation of a Solid State Filament Control for Thermal

Ionization Mass Spectrometers

Precise and accurate isotope ratio measurements require the use of a highly

stable and well-regulated supply of current to the thermal ionization ribbon

filaments. The filament power supply and control unit which had been in use for many years utilized a set of Variacs in series to control the filament

current setting. Although relatively simple, low cost, and capable of being

AC-transformed near the source to maintain operator controls at ground potential

the unit had become the limiting factor in ion beam stability and was no longer adequate. In addition, maintenance was a constant problem and the

design was not amenable to automatic or computer control. To improve overall

performance, reduce down-time and maintenance, and provide facilities for com- puter control, a new triple filament power supply and control unit was designed.

The electronically regulated power supply contains three identical filament control circuits and is fully isolated to permit operation at the 10 kV

ion source potential. Substantial circuitry is employed to provide protection

from electrical transients generated by high voltage arc-over in the source

housing. Vulnerability to arc-over transients is responsible for the failures

of similar instruments designed for this purpose. Each circuit is current

controlled to provide up to 7.5 amperes at a maximum voltage of 7.5 volts

regulated to better than ±20 ppm typical stability. The current meters are autoranging for better readability at low filament current settings. Smooth

manual control is achieved by using 10-turn potentiometers with a response

tailored to enhance low range adjustments. Push-pull, on-off switches on each

control simplify the front panel operation, and provision is included for

future adaptation to digital control. Construction of the instrument is of a double box arrangement with no high voltage surfaces exposed in order to

eliminate personnel shock hazard. The meters are viewable through a large

ruby plexiglass face plate providing wide angle readability. Two of the three

special high voltage isolation transformers recovered from the previously used

circuitry are used in this instrument, eliminating a major cost item in its

construction. The bulk of electronic components are located on easily replaceable modules. Three interchangeable meter-pot assemblies, a power heat sink

assembly, and a control circuit board constitute the system. Modular construction of the electronics assures minimum down-time for repair when replacement

subassemblies are available.

Three slightly different hand-wired versions of the control unit have

been constructed and have been in use for almost one year. Essentially no problems have been encountered and the original performance specifications have

been realized. Printed circuit boards have been designed to make the unit

easy to assemble as well as to repair. Two of these have been constructed and * installed and additional units are planned as replacements for the control

units with Variacs.

The successful completion of this unit is an important step toward a fully automated mass spectrometer that will dramatically improve analytical

efficiency and output.

I. L. Barnes, R. W. Shideler

82
23. Digital Control Modification for the Varian FR-41 Qaussroeter/Controller

A fully digital control system has been added to a Varian FR-41 magnet

control unit to upgrade and enhance its utility and extend its useful life.

To automate fully the operation of a mass spectrometer, complete computer

control must be achieved for all components that function during the analysis.

A key component of this control is the gaussmeter used to control the magnetic

field. Currently, the gaussmeter is controlled by a combination of manual and

computer controlled switching, and does not have the flexibility required for

such operations as completely automated baseline measurement and isotope peak

centering.

The system interfaces to a digital computer or desktop calculator from

which a full five-digit number representing field gauss may be executed under

program control. The system is comprised of a series of digital registers

which receive a multiword sequence from the control medium and operate a series of analogue switches interconnected to the mechanical switches in the

Varian unit. Control may be returned to the mechanical switches for off-line

operation. The contact resistance reliability of the analogue switches is

superior to that of the mechanical rotary switches and improves the reliability

and stability of the gauss setting during digitally controlled operation. The

unit is built on a circuit board installed within the Varian chassis. A

separate five digit LED display panel is mounted on the front panel. The unit

is a hand-wired first prototype and will be replaced by a much improved second

generation design created to reduce construction and installation costs as well as further enhance system stability.

Implementation of this device, along with the other units leading to

complete automation, will have a large impact on the efficiency of mass spectrometric analytical measurements. For many applications, the instrument

operator will be free to perform other tasks and research.

I. L. Barnes, R. W. Shideler

24. Evaluation of a Collimated Ion Collector for Thermal Ionization Mass

Spectrometry

One of the fundamental conditions for collecting and detecting charged

particles is the suppression of stray electrons to the extent that the net

gain or loss in charge is zero. For many years, the high accuracy mass spectrometers at NBS have been equipped with a 50 percent transmission grid in

front of the final defining slit in the collector. The grid, typically a series of flat tungsten wires placed parallel to each other, was electrically

isolated and attached to an auxiliary electrometer. This grid, in conjunction

with a series of tungsten wire suppressor grids, was a very effective means of

collecting stray electrons. This particular configuration has been utilized

for 20 years of atomic weight research, the certification of all of the U and

Pu isotopic SRM's, and for numerous trace element determinations by isotope

dilution.

83
While useful and very effective for high accuracy measurements, this

system did present several drawbacks. Among these were the loss of signal due

to the transmission grid, and the increased ion scatter and electron production resulting from the ion beam striking the edges of the grid wires. With

the increased pressure to analyze micro amounts of material at high accuracy

and without major modification of the equipment, the loss of 50 percent of

signal to the transmission grid became very critical. Therefore, research to

develop an innovative system to collect 100 percent of the ion beam and also

suppress electrons has some very definite advantages in the analyses of micro

samples where the concentration of the analyte element is less than 1 ug/g.

An improved collector has been designed. The collector assembly, shown

in figure 15, completely eliminates all grids in front of the final defining

slit and utilizes a pair of identical slits, separated by 1.3 cm to collimate

the beam, reduce scattering, and eliminate stray electrons. All screws or other protrusions on the front of the slit assembly have been replaced by

small clips carefully placed to ensure that no part of the beam is intercepted.

This modification virtually eliminates any source of "stray" electrons. The

original deep Faraday cup ion collector and an electron suppressor plate

(maintained at -90 V) have been retained. A modification of this collector

has been designed with a movable Faraday cup. With this configuration, an ion counting detection system can be placed behind the Faraday cup, allowing

for rapid change between large ion current measurements with a Faraday cup

collector to ion counting detection of extremely small signals. In effect,

the combination of the collimated ion collector, movable Faraday cup and ion

counting detection system will increase by several orders of magnitude the

useful- signal intensity measurement range, for high accuracy analyses, of the

NBS thermal ionization mass spectrometers. Two of the collimated ion

collectors have been in routine use for nearly one year and have proven to be

very satisfactory. The increased signal intensity has resulted in improved

accuracy for elements with low ionization efficiencies and has allowed a reduction in sample size, without compromising analytical quality, for nuclear

materials where the amount of material handled is an important health and

safety consideration.

Several element spectra including Ca, Dy, Er, Ga, Pb, Sr, T1 , U, V,

and Zn have been extensively examined using the new collector. A typical mass spectral scan for one of these, uranium, is shown in figure 16. As is

shown, even with signals (235:236) differing by a factor of about 650 to 1,

excellent peak shape is maintained, no evidence of "tailing" by the large

peak is evident and no baseline disturbance by either scattered ions or electrons is detected. The measured signal is 100 percent larger than that

obtained using the more elaborate col lector with the same size sample at the same temperature. A recent, detailed examination of peak shape in a similar

scan of a lead sample indicates that the "flat top" portion of the peak is

"flat" to one part in 25,000, over 25 percent of the peak width, which is a significant improvement over that obtained with the old collector.

I. L. Barnes, W. A. Bowman, III, J. W. Gramlich

84
I

i

,1

85

Figure

15.

Thick

lens

collector.
Figure 16. A typical mass spectral scan for uranium.

25. Standard Reference Materials

The analysis and certification of Standard Reference Materials (SRM's)

has continued to be a major part of the total scientific effort of this

Division. Input from virtually the entire scientific staff goes into this

effort which accounts for about 25 percent of the total working budget. The

Division funding for work leading to the issuance of SRM's falls into two

categories; STRS--Scientific and Technical Research Services and WCF--

Working Capital Funds.

The STRS portion of the funding is intended for the preliminary research

necessary to develop the methodologies required for the actual production of

SRM's. This year seven different research projects were funded by the

Office of Standard Reference Materials. Once a sufficient technological

foundation has been established through STRS research, then the WCF funding

becomes operative. The WCF projects are those which result in the actual

production of a marketable standard. The SRM's on which work was carried

out this year and the STRS research projects, along with the relative effort

in staff-years, are shown in Tables 11 and 12. It is seen from these tables

that the work on SRM's was carried out on a wide variety of matrices (aqueous

biological, fossil fuel, metals, etc.). The concentration levels certified

on these materials ranged from ultra-trace to major. A number of items on the lists presented here are described in greater detail, as technical

accomplishments, throughout the Annual Report.

One important accomplishment this year was the recertification of three

widely used primary chemical Standard Reference Materials (TRIS, Benzoic

Acid, and Potassium Dichromate). The widespread use of these standards is

86
Table 11. WCF Work Carried Out on Standard Reference Materials.

Division 551, FY 81

SRM Number TITLE Effort S/Y

923 TRIS .2

909 Sodium in Serum .1 691a Reduced Iron Oxide .6

930d Glass Filters for Spectrophotometry.4

1 36d Potassium Di chromate .4

978a Silver Assay and Isotopic .1 1645 and 1648 River Sediments & Urban

Particulates

.9

931c Liquid Absorbance Filters for

Spectrophotometry

.4

994 Gallium Assay and Isotopic .1 962a and 963a Fission Track Glasses .2

1284a, 1285a, 72g, 1225, 1226,

1173

Low Alloy Steels .4

Cl 137 and Cl 137a White Cast Irons .2

350a Benzoic Acid .2

1221, 1227, 1228 Basic Steels .4

494-500, 1251-1253, 393-400 Copper Benchmarks .9

1646 Estuarine Sediment .2

U-002, U-020, U-050, U-200,

U-970, U-500, U-150

Nuclear SRM's .1

1034 and 1035 Sulfur in Unalloyed Copper and

Tin Bronze

.2

1815a, 1816a Lead in Reference Fuel Standards .1 864-867, 1244-1247 Inconels and Incalloys .3

Cl 1 51 -Cl 1 54, 1269, 1270, 1270a Low Alloy Steels .9

1223 Stainless Steel .1 1641b and 1642b Mercury in Water .2

125b, 1134, 854, 1254 Calcium in Low Alloy Steels .1 1620a, 1621a, 1622b, 1623b,

1632b, 1634a, 1635a

Sulfur in Fuel Oils and Coal .5

1649 Washington Dust .2

1572 and 1577 Bovine Liver and Citrus Leaves .2

1084 and 1085 Wear Metals in Oil .1

1 261 -1265a Low Alloy Steels A

9.0

87

cnj

c\j

cr>

cm
Table 12. STRS Projects Currently Underway.

Division 551, FY 81

Task

Sulfur Analysis

DC Plasma

Spectroscopy

Iodine in Foods

Tin and Vanadium in

Biologicals

Metal -on-Ouartz

Filters

Light Elements in

Complex Matrices

Copper Benchmarks

Description

Complete development of

IDMS procedure and develop

Leco CS-46 and ion

chromatography procedures for

application to a number of SRM's

Complete development of dc

plasma spectrometry technique

Application of the techniques

being developed for the

measurement of iodine in

existing natural matrix SRM's

Development of certification

procedures for tin and vanadium

and their application to biological

SRM's

Resolve research problems

required for full scale

production

Development of analytical methods

for the determination of C, H, N,

0, and S in matrices such as coal,

oil , and plant tissue

Complete technique development

necessary for certification of

Copper Benchmarks

Effort S/Y

.6

.4

.4

.6

.5

.6

.7

3.8

88
best illustrated by the fact that nearly 500 units of the three materials

are sold each year.

In the area of health and environmental standards, work has continued

on the certification of important elements in a variety of SRM's such as River Sediment, Estuarine Sediment, Urban Particulates, Washington Dust,

Bovine Liver, Citrus Leaves, and Mercury in Water. Additionally, work has

begun leading to the certification of a set of three coal samples and four

fuel oil samples which will be certified for sulfur content and issued as SRM's.

Each year significant effort goes into the analysis of a large number

and variety of metals. This work is done for acceptance testing, to determine homogeneity, and for eventual certification of both trace and major

constituents. The Division effort in this area accounts for about 40 percent

of the entire budget allotted for Standard Reference Materials.

B. I. Diamondstone

89
C. Outputs and Interactions

(Inorganic Analytical Research Division)

1 . Pub! ications

Barnes, I. L. , "The Use of Isotope Dilution Mass Spectrometry for the

Certification of CRM's," p. 161 (1980). Proc. of the International

Symposium, "Production and Use of Reference Materials," held at the

Bundesanstal t fur Material prufung , November 13-16, 1979, B. F. Schmitt,

ed.

Harrison, S. H. , Gills, T. E. , Maienthal, E. J., Rook. H. L., Wise, S. A.,

Zeisler, R. , and Goldstein, G. M. , "The National Environmental Specimen

Bank Pilot Program," Proc. of the 14th Annual Conference on Trace Substances in Environmental Health, Columbia, MO, June 2-5, 1980, p. 329.

Lindstrom, R. M. and Fleming, R. F. , "Accuracy in Activation Analysis: Count

Rate Effects," Proc. of the 4th Int. Conf. Nucl. Methods in Env. and

Energy Res., C0NF-800433, (Univ. of MO., Columbia), 1980.

Anderson, D. L. , Failey, M. P. , Zoller, W. H., Walters, W. B., Gordon, G. E.,

and Lindstrom, R. M. , "Facility for Non-Destructive Analysis for Major

and Trace Elements Using Neutron-Capture Gamma-Ray Spectroscopy,"

J. Radioanal. Chem. , 63^, 97 (1981 ).

Greenberg, R. R. , Zoller, W. H. , and Gordon, G. E., "Atmospheric Emissions of

Elements on Particles from the Parkway Sewage-Sludge Incinerator,"

Environ. Sci. Technol , 1_5 , 64 (1981 ).

Harrison, S. H. , Zeisler, R. , Wise, S. A., eds., "Pilot Program for the

National Environmental Specimen Bank - Phase 1," EPA-6001 SI -81 -025 , 1981.

Hervath, J. J., Bradshaw, J. D. , Bower, J. N., Epstein, M. S. , and

Winefordner, J. D. , "Comparison of Nebulizer-Burner Systems for LaserExcited Atomic Fluorescence Flame Spectrometry," Anal. Chem., 53, 6

(1981).

Janghorbani, M. , Young, V. R. , Gramlich, J. W. , and Machlan, L. A.,

"Comparative Measurements of Zinc-70 Enrichment in Human Plasma Samples

with Neutron Activation and Mass Spectrometry," Clin. Chim. Acta, 114,

163 (1981 ).

Kingston, H. M. and Pella, P. A., "Preconcentration of Trace Metals in

Environment and Biological Samples by Cation Exchange Filters for X-Ray

Spectrometry ," Anal. Chem., 53^, 2 (1981).

Messman, J. D. and Rains, T. C. , "Determination of Tetraal kyl lead Compounds in

Gasoline by Liquid Chromatography - Atomic Absorption Spectrometry,"

Anal. Chem., 53, 1632 (1981 ).

Paulsen, P. J., Burke, R. W. , Maienthal, E. J., and Lambert, G. M. , "Isotope

Dilution Spark Source Mass Spectrometric Determination of Sulfur in

Selected NBS Iron-Base Alloys," New Analytical Techniques for Trace

Constituents of Metallic and Metal Bearing Ores , ASTM STP 747, Adelina

Javier-Son, ed. , 1981, p. 113.

90
Scheeline, A., Norris, J. A., Travis, J. C., and DeVoe, J. R., "Particulates

Formed by a Stabilized High Voltage Spark Discharge," Spectrochimica

Acta, 36B, 373 (1981).

Wynn, T. F. , Clardy, P. , Vaughn, L., Bradshaw, J. D., Bower, J. N.,

Epstein, M. S. , and Winefordner, J. D. , "Wavelength-Modulated ContinuumSource Excited Atomic Fluorescence Spectrometric System for Wear Metals

in Jet Engine Lubricating Oils Using Electrothermal Atomization," Anal.

Chim. Acta, 124, 155 (1981).

Burke, R. W. , Paulsen, P. J., Maienthal, E. J., and Lambert, G. M.

"Validation of the Sulfur Concentration in Selected Iron-Base Standard

Reference Materials by Isotope Dilution Spark Source Mass Spectrometry,"

Talanta, in press.

Diamondstone, B. I., "NBS Standard Reference Materials for Improving the

Accuracy of Priority Pollutant Analyses," Proc. of Fifth Seminar on Analytical Methods for Priority Pollutants, Hershey, PA, April 9-10,

1981, in press.

Diamondstone, B. I., Burke, R. W., and Garner, E. L. , "An NBS Approach for

Improving the Quality of Leach Measurements on Solid Wastes," Proc. of

International Conference on Solid Wastes, Sludges and Residual Materials:

Monitoring, Technology and Management," Rome, Italy, June 17-20, 1981, in

press.

Greenberg, R. R. and Kingston H. M. , "Simultaneous Determination of Twelve

Trace Elements in Estuarine and Sea Water Using Pre-Irradiation Chromatography," J. Radioanal. Chem. , in press.

Koch, W. F. and Stolz, J. W., "Analysis of Chloride-Doped Cadmium Sulfide

by Ion Chromatography," Anal. Chem., in press.

Moore, L. J., Murphy, T. J., Barnes, I. L., and Paulsen, P. J., "Absolute

Isotopic Abundance Ratios and Atomic Weight of a Reference Sample of

Strontium," J. of Res. Nat. Bur. Stand., Jan. -Feb., 1982, in press.

Moody, J. R. , "Sample Handling and Storage for Trace Analysis," Proc. of the

Royal Society of Chemistry, Talanta, in press.

Moody, J. R. , "Some Considerations of Analytical Methodology Relevant to

Radioactive Solid Leachate Testing," Nuclear and Chemical Waste Management, in press.

Zeisler, R. , "Trace Element Analysis," in Pilot Program for the National

Environmental Speciman Bank - Phase I, p. 29, National Technical Information Service, Springfield, VA, in press.

Bower, V. E. , Davis, R. S. , Murphy, T. J., Paulsen, P. J., Gramlich, J. W.,

and Powell, L. J., "Recalculation of the Faraday Constant Due to a New

Value for the Atomic Weight of Silver," to be published in J. of Res.

Nat. Bur. Stand.

91
Harrison, S. H. , Zeisler, R. , Anderson, D. L., "Evaluation and Analysis of

Environmental Specimen Bank Samples by Nuclear Methods," to be published

in J. Radioanal. Chem.

Powell, L. J., Murphy, T. J., and Gramlich, J. W. , "The Absolute Isotopic

Abundance and Atomic Weight of a Reference Sample of Silver," to be

published in J. of Res. Nat. Bur. Stand.

Zeisler, R. and Greenberg, R. R., "Ultratrace Determination of Platinum in

Biological Materials Via Neutron Activation and Radiochemical Separation,

to be published in J. Radioanal. Chem.

2. Tal ks

Rains, T. C. and Alvarez, R. , "Characterization of Standard Reference

Materials for Trace Metal Determination," 9th International Conference on Atomic Spectroscopy and XXII Colloquium Spectroscopicum Internationale,

Tokyo, Japan, September 5, 1980.

Moody, J. R. , "Sample Handling and Storage for Trace Analysis," Royal Society

of Chemistry Meeting, Cardiff, England, September 23, 1980. Invited

Harrison, S. H. , "The National Environment Specimen Bank Program at NBS,"

University of Maryland, Division of Nuclear and Environmental Chemistry,

College Park, MD, September 26, 1980. Invited

Lutz, G. J., "Photon Activation Analysis - A Review," 7th Annual Meeting

of the Federation for Analytical Chemistry and Spectroscopy Societies,

Philadelphia, PA, September 30, 1980. Invited

Epstein, M. S. and Rook, F. L., "An Evaluation of Noise Sources which Limit

Precision in the Optimum Analytical Range of Atomic Spectroscopic Methods,"

7th Annual Meeting of the Federation for Analytical Chemistry and Spectroscopy Societies, Philadelphia, PA, September 30, 1980. Invited

Moody, J. R., "Clean Air Fume Hoods for Trace Element Analysis," Laboratory of

the Government Chemist, London, England, October 1, 1980. Invited

Rains, T. C. , "A Comparison of Electrothermal Atomization and Hydride Generation

Atomic Absorption Spectrometry for As and Se," 7th Annual Meeting of the

Federation for Analytical Chemistry and Spectroscopy Societies, Philadelphia, PA, October 3, 1980.

Rains, T. C. , "A Method to Improve the Precision and Accuracy of Atomic

Absorption Spectrometry with Electrothermal Atomization," 7th Annual

Meeting of the Federation for Analytical Chemistry and Spectroscopy

Societies, Philadelphia, PA, October 3, 1980.

Fassett, J. D. , Kelly, W. R. , and Machlan, L. A., "Mass Spectrometric Analysis

of Nanogram Levels of Plutonium," 24th Conference on Analytical Chemistry

in Energy Technology, Gatl inburg, TN, October 7, 1980. Invited

92
Powell, L. J., "Career Opportunities in Science for the 80's," North Dakota

State University, Fargo, ND, October 25, 1980. Invited

Epstein, M. S. , "Review of Analytical Methods for Liquids and Solutions at NBS,"

Workshop on Compositional and Microstructural Analysis of Nuclear Waste

Materials, Battel le Pacific Northwest Labs, Richland, WA, November 11,

1980.

Lutz, G. J., "Analytical Method Review - Activation Analysis of Solids,"

Workshop on Compositional and Microstructural Analysis of Nuclear Materials,

Battel! e Pacific Northwest Labs, Richland, WA, November 11, 1980.

Invited

Epstein, M. S. , "Some Developments in Atomic Absorption and Emission Spectroscopy at the National Bureau of Standards," Cincinnati Section, Society

for Applied Spectroscopy, Cincinnati, OH, November 13, 1980. Invited

Zeisler, R. , "Phase I of the National Environmental Specimen Bank Pilot

Program at the National Bureau of Standards," Medical Science Colloquium,

University of Minnesota, Minneapolis, MN, December 1, 1980. Invited

Norris, J. A., "Splitting Hairs," New England Section, Society for Applied

Spectroscopy, Waltham, MA, December 4, 1980. Invited

Moody, J. R. , "Some Considerations of Analytical Methodology Relevant to

Radioactive Solid Leachate Testing," Oak Ridge Conference on the Leachability of Radioactive Solids, Gatl inburg, TN, December 9, 1980. Invited

Rains, T. C. , "Analysis of Trace Metals in Water by Atomic Absorption

Spectrometry," 1980 American Water Works Quality Technology Conference,

Miami Beach, FL, December 9, 1980. Invited

Diamondstone, B. I., "Extraction Procedures for Solid Wastes," 2nd Annual

Midwest Conference on Environmental Laboratory Technology, St. Paul, MN,

December 10, 1980. Invited

Kingston, H. M. , "State-of-the-Art Analytical Measurements of Trace Elements

in Aqueous and Other Matrices with an Emphasis on Chemical Manipulation,"

Rockwell International Labs, Richland, WA, January 27, 1981. Invited

Kingston, H. M. , "Trace Metal Analysis: The Effect of Chemical Manipulation

on the Results," Battelle Pacific Northwest Labs, Richland, WA,

January 28, 1981. Invited

Lutz, G. J., "Photon Activation Analysis," Analytical Nuclear and Environmental Chemistry Division, University of Maryland, College Park, MD,

January 30, 1981. Invited

Greenberg, R. R. , "Neutron Activation of Estuarine Water and Suspended

Solids," Analytical Nuclear and Environmental Chemistry Division Seminar,

University of Maryland, College Park, MD, February 6, 1981. Invited

Powell, L. J., "Careers in Chemistry," Seneca Valley High School, Gaithersburg,

MD, February 10, 1981. Invited

93
Koch, W. F. , "Anion Analysis by Ion Chromatography at the National Bureau of

Standards," Joint Meeting of the Chemical Society of Washington and the

Electrochemical Society, Montgomery College, Rockville, MD, February 12,

1981. Invited

Powell, L. J., "Careers in Chemistry," Gaithersburg High School, Gaithersburg,

MD, March 3, 1981. Invited

Epstein, M. S. and Rains, T. C., "Atomic Absorption Spectrometry," ACS

Short Course, Pittsburgh Conference, Atlantic City, NJ, March 8, 1981.

Moore, L. J., "Some New Approaches to Ion Production and Measurement," Chemical

Physics Laboratory, National Institutes of Health, Bethesda, MD, March

19, 1981. Invited

Rains, T. C. , "Modern AAS Techniques - Characterization of NBS Standard

Reference Materials," National Society for Applied Spectroscopy Tour

Speaker, Lehigh Valley Section, Reading, PA, April 6; Delaware Valley

Section, Philadelphia, PA, April 7; New York Section, New York, NY, April

8; and New England Section, Boston, MA, April 9, 1981. Invited

Diamondstone, B. I., "NBS Standard Reference Materials for Improving the

Accuracy of Priority Pollutant Analyses," 5th Seminar on Analytical

Methods for Priority Pollutants, EPA, Hershey, PA, April 10, 1981.

Invited

Norris, J. A., "Metal Homogeneity," Lehigh Valley Section, Society for Applied

Spectroscopy, Reading, PA, April 24, 1981. Invited

Powell, L. J., "A New Determination of the Atomic Weight of Silver and an Improved Value for the Faraday," Mass Spectrometry Discussion Group of

Washington, Washington, DC, May 18, 1981. Invited

Greenberg, R. R. , Kingston, H. M. , and Beary, E. S., "Non-Normal Distribution

of Blanks in Environmental Samples," 11th Annual Symposium on the Analytical Chemistry of Pollutants, Jekyll Island, GA, May 18, 1981. Invited

Wise, S. A. and Zeisler, R. , "Analytical Methods for Certification of

Standard Reference Materials," Chemistry Colloquium, Institut fur

Oekologische Chemie, GSF, and Institut fur Chemie, TU MLinchen, Weihenstephan,

F.R. Germany, May 18, 1981. Invited

Harrison, S. H. , "Implementation and Evaluation of Sample Collection for Human

Livers," Environmental Specimen Banking Project - Seminar of State and

Planning 1981, Kernforschungsanlage (KFA), Jiilich, F.R.G., May 20, 1981.

Invited

Harrison, S. H. and Zeisler, R. , "Development and Evaluation of Cryogenic

Homogenization of Tissue," Environmental Specimen Banking Project - Seminar of State and Planning 1981, Kernforschungsanlage (KFA), Jiilich,

F.R.G, May 20, 1981. Invited

94
Zeisler, R. and Harrison, S. H., "Specimen Storage and Storage Evaluation,"

Annual Bilateral Meeting on Specimen Banking by US/EPA and Ummel tbundesant

F.R.G., Jlilich, F.R.G., May 20, 1981. Invited

Zeisler, R. , "Inorganic Analysis of Liver Specimens Collected During the First

Year of the NESB Pilot Program," Annual Bilateral Meeting on Specimen

Banking by US/EPA and Ummel tbundesant, F.R.G., Jlilich, F.R.G., May 20,

1981. Invited

Paulsen, P. J. and Burke, R. W. , "Isotope Dilution Spark Source Mass Spectrometry - Determination of Sulfur in NBS Iron Base Alloys," 29th Annual

Conference of the American Society for Mass Spectrometry, Minneapolis,

MN, May 24, 1981. Invited

Kelly, W. R. and Fassett, J. D. , "The Determination of Subnanogram Quantities

of Uranium by Isotope Dilution Mass Spectrometry ," 29th Annual Conference

on Mass Spectrometry and Applied Topics, Minneapolis, MN, May 27, 1981.

Invited

Kingston, H. M. , "Workshops on Spiking Procedures for Isotope Dilution Mass

Spectrometry," 29th Annual Conference of the American Society for Mass

Spectrometry , Minneapolis, MN, May 27, 1981. Invited

Epstein, M. S. and Rains, T. C. , "Atomic Absorption Spectrometry," ACS Short

Course, National Bureau of Standards, Washington, DC, June 5, 1981.

Powell, L. J. , "A New Determination of the Atomic Weight of Silver and an Improved Value for the Faraday," 2nd International Conference on Precision

Measurements and Fundmental Constants, National Bureau of Standards,

Washington, DC, June 10, 1981. Invited

Garner, E. L. , "An NBS Approach for Improving the Quality of Leach Measurements

on Solid Wastes," International Conference on Solid Wastes, Sludges, and

Residual Materials: Monitoring, Technology, and Management, Rome, Italy,

June 17, 1981. Invited

Greenberg, R. R. and Kingston, H. M. , "Simultaneous Determination of Twelve

Trace Elements in Estuarine and Seawater Using Pre-Irradiation Chromatography," 6th International Conference on Modern Trends in Activation

Analysis, Toronto, Canada, June 18, 1981. Invited

Zeisler, R. and Greenberg, R. R. , "Ultratrace Determination of Platinum

in Biological Materials via Neutron Activation and Radiochemical Separation," 6th International Conference on Modern Trends in Activation

Analysis, Toronto, Canada, June 18, 1981.

Moore, L. J., "Application of Thermal Ionization to Stable Isotopic Trace

Measurements," Workshop on Stable Isotopic Measurements on Metals,

Children's Nutrition Research Center, Baylor College of Medicine, Houston,

TX, June 22, 1981. Invited

Fleming, R. F. , "Analytical Chemistry at the NBS Reactor," Analytical Chemistry

Division Seminar, Oak Ridge National Laboratory, Oak Ridge, TN, July 17,

1981. Invited

95
Koch, W. F. , "Anion Analysis by Ion Chromatography at the National Bureau of

Standards," International Symposium on Ion Chromatography, 23rd Rocky

Mountain Conference, Denver, CO, August 3, 1981. Invited

Rains, T. C. , "Atomic Absorption Spectrometry," ACS Short Course, 23rd Rocky

Mountain Conference, Denver, CO, August 6, 1981.

Fassett, J. D. , Moore, L. J. , and Travis, J. C. , "Innovations in High

Sensitivity Mass Spectrometry," Gordon Research Conference, New Hampton,

NH, August 12, 1981. Invited

Rains, T. C. and Messman, J. D. , "Application of Liquid Chromatograph - Atomic

Absorption Spectrometry for Determining Metal Species in Environmental

Samples," 9th International Conference on Atomic Spectroscopy and XXII

Colloquium Spectroscopicum Internationale, Tokyo, Japan, September 4,

1981.

Rains, T. C. , "Critical Evaluation of the Determination of Arsenic and Selenium

by Atomic Absorption Spectrometry," 9th International Conference on Atomic Spectroscopy and XXII Colloquium Spectroscopicum Internationale,

Tokyo, Japan, September 8, 1981. Invited

Rains, T. C. , "Sampling, Preservation, and Standardization in Trace Metal

Analysis," Seoul International Spectroscopy Conference, Seoul, Korea,

September 11, 1981

.

Moore, L. J. and Travis, J. C., "Laser-Induced Ion Fluorescence in Magnetic

Sector Mass Spectrometry," 8th Annual Meeting of the Federation for

Analytical Chemistry and Spectroscopy Societies, Philadelphia, PA,

September 22, 1981

.

Watters, R. L. , Jr., "Analytical Techniques Using the Inductively Coupled

Plasma," FACSS Workshop, 8th Annual Meeting of the Federation for Analytical Chemistry and Spectroscopy Societies, Philadelphia Sheraton,

Philadelphia, PA, September 22, 1981. Invited

Epstein, M. S. and Blundell, C. G. , "Analysis of Nuclear Waste Leachates for

Trace Elements by Atomic Spectrometry: Problems and Solutions," 8th

Annual Meeting of the Federation for Analytical Chemistry and Spectroscopy Societies, Philadelphia, PA, September 23, 1981. Invited

Epstein, M. S. and Blundell, C. G. , "Considerations for Obtaining the Utmost in

Accuracy Using D.C. Plasma," 8th Annual Meeting of the Federation for

Analytical Chemistry and Spectroscopy Societies, Philadelphia, PA,

September 23, 1981. Invited

Kingston, H. M. , "The Analytical Constraints That Influence Leachability

Measurements and Reference Materials" 8th Annual Meeting of the Federation for Analytical Chemistry and Spectroscopy Societies, Philadelphia,

PA, September 23, 1981. Invited

96
Rains, T. C. and Powell, L. J., "The Art of Sample Preparation," FACSS Short

Course, 8th Annual Meeting of the Federation for Analytical Chemistry and

Spectroscopy Societies, Philadelphia, PA, September 24, 1981. Invited

Zeisler, R. , "Pilot Environmental Specimen Bank - The Analytical Approach,"

Environmental Pathology Seminar, Harbor Grace Medical Center, Seattle,

WA, September 28, 1981. Invited

3. Committee Assignments

I. Lynus Barnes

Member, Department of Health, Education, and Welfare, The Chemistry Task

Force of the National Shellfish Sanitation Program

Washington Editorial Review Board

International Union of Pure and Applied Chemistry, Commission of

Atomic Weights

Secretary, IUPAC, Commission on Atomic Weights, Subcommittee for Assessment of Isotopic Abundances

Robert W. Burke

Member, ASTM D-34, Waste Disposal

ASTM E-03, Chemical Analysis of Metals

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

Michael S. Epstein

Member, ASTM D-19.07.04, Section on Chemical Characterization of Fluvial

Sediment

ASTM D- 19, Water

Chairman, Fellowship Award Committee, Baltimore-Washington Section of the

Society for Applied Spectroscopy

Secretary/Treasurer, Baltimore-Washington Section of the Society for Applied

Spectroscopy

Delegate, FACSS Governing Board for the Division of Analytical Chemistry

of the American Chemical Society

Budget Committee Member, FACSS Governing Board

Ronald F. Fleming

Member, Organizing Committee, Fifth Symposium on X- and Gamma-Ray

Sources and Applications

Organization and Planning Committee, The Fourth International

Conference on Neutron Transmutation Doping of Semiconductors

Committee on Accelerator-Based Neutron Research at NBS

John W. Gramlich

Member, Institute of Nuclear Materials Management Committee N15.9.3,

Non-Destructive Assay (Physical Methods)

William R. Kelly

Member, Center Colloquium Committee

97
Howard M. Kingston

Member, NBS Nuclear Waste Management Team

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

Lawrence A. Machlan

Member, ASTM C-26, Nuclear Fuel Cycles

ASTM C-26. 05, Test Methods

Secretary, ASTM C-26. 01, Editorial and Terminology

E. June Maienthal

Member, ASTM D-19, Water

ASTM D-19. 05, Inorganic Constituents in Water

ASTM D-19. 06, Methods for Analysis for Organic Substances in Water

ASTM D-19. 07, Methods of Testing of Water-Reformed Deposits and

Properties of Water

ASTM D-19. 07. 04. 03, Trace Metals and Sediments

ASTM D-19. 11, Methods for the Analysis of Water for Power Generation

and Process Uses

ASTM E-3, Metals

ASTM E-3. 01, Ferrous Metals

ASTM E-3. 02, General Analytical Practices

ASTM E-3. 05, Non-Ferrous Metals

George Marinenko

Member, ASTM D-19, Water

ASTM D-19. 01, Saline in Brackish Waters

ASTM D-19. 02, General Specifications and Technical Resources

ASTM D-19. 05, Inorganic Constituents in Water

ASTM D-19. 05. 03. 06, Ozone

Chairman, ASTM D-19. 05. 04. 03, Voltammetry

ASTM D-19. 09. 01 .04, Chlorine in Saline Water

ASTM D-19. 02. 02. 01 , Interpretation of Results

Vice-Chairman, National Capital Section of the Electrochemical Society

Program Chairman, National Capital Section of the Electrochemical Society

John R. Moody

Member, ASTM D-19, Water

ASTM D-19. 05, Inorganic Constituents in Water

Audit Committee, Chemical Society of Washington

Delegate, Middle Atlantic Regional Meeting, Chemical Society of Washington

Larry J. Moore

Contributing Editor, Journal of Applied Spectroscopy

98
Thomas J. Murphy

Member, American Chemical Society Committee on Analytical Reagents

American Chemical Society Committee on Membership Affairs

American Chemical Society Admissions Committee

International Union of Pure and Applied Chemistry (IUPAC),

Commission on Atomic Weights and Isotopic Abundances

International Union of Pure and Applied Chemistry (IUPAC),

Subcommittee for the Assessment of Isotopic Abundances, Commission

on Atomic Weights and Isotopic Abundances

Chairman, Audit Committee, Chemical Society of Washington

Councilor, Chemical Society of Washington

John A. Norris

Member, ASTM E-02.01, Fundamental Practices

ASTM E-02. 02, Statistics

ASTM E-Q2.Q4, Sampling and Standards

ASTM E-02.06, Lead, Tin, Zinc

ASTM E-02.07, Aluminum

ASTM E-02.08, Refractory Metals

ASTM E-02.09, Ferrous

ASTM E-02.10, Miscellaneous Non-Metal! ic Materials

Secretary, ASTM E-02, Emission Spectroscopy

Lecturer, Annual Short Course, "Modern Industrial Spectroscopy," Arizona

State University, Tempe, AZ

Lura J. Powell

Member, Audit Committee, Chemical Society of Washington

Program Committee, American Society for Mass Spectrometry

Investment Committee, Chemical Society of Washington

Board of Managers, Chemical Society of Washington

Chairman, Committee on Isotope Ratio Measurements, American Society for

Mass Spectrometry

Budget Committee, Chemical Society of Washington

Treasurer, 15th Middle Atlantic Regional Conference, American Chemical

Society

Assistant Registration Chairman, Federation of Analytical Chemistry

and Spectroscopy Societies

Theodore C. Rains

Member, Proposal Evaluation Committee for National Science Foundation

AOAC Committee on Automated Methods

Editorial Board of Annual Reports on Analytical Atomic Spectroscopy

(The Chemical Society of London) and the Canadian Journal of

Spectroscopy

Subcommittee No. 6 on Methods of Air Sampling and Analysis

ASTM E-02. IQ, Non-Metal lie Materials

ASTM E-02. 13, Nomenclature

ASTM D-01 , Paint and- Related Coatings

ASTM D-l 9, Water

President-Elect, Society for Applied Spectroscopy

Director, Professional Development Program for the Baltimore-Washington

Section of the Society for Applied Spectroscopy

Professor-in-charge, ACS Short Course on "Atomic Absorption Spectroscopy"

99
Task Force Leader in Scientific Instrumentation Information Network and

Curricula [SIING) for project on "Atomic Absorption Spectroscopy"

Column Editor, Journal of Applied Spectroscopy

Robert L. Watters, Jr.

Secretary, I CP Detection Limits Committee

National Correspondent and Reviewer Designate, ICP Information Newsletter

4. Other

a. Seminars

October 7, 1980

December 1 , 1980

December 11, 1980

March 13, 1981

July 1, 1981

July 27, 1981

Kenneth Grabowski , Argonne National Laboratories,

Argonne, IL, "Compositional Mapping Using MeV Ion

Beams"

John A. Norris, Atomic & Molecular Spectrometry Group,

Inorganic Analytical Research Division, National

Bureau of Standards, Washington, DC, "Mini -inhomogeneity

in Ferrous Standard Reference Materials"

Sharon M. Tomaski, Department of Chemistry, Rutgers

University Camden, NJ, "Collection and Treatment of

Hair Samples for Elemental Analysis"

Rebecca Koszykowski, Lawrence Livermore Laboratory,

Livermore, CA, "Analysis of Solar Grade Silicon by

Neutron Activation and ICP-OES"

Paul DeBievre, Central Bureau for Nuclear Measurements,

Geel , Belgium, "A Determination of the 241 Pu HalfLife of 90% Enriched Material"

Jan Lindberg and Mats Lindgren, Analytical Research,

Pharmacia AB, Uppsala, Sweden, "Some Applications of

IC and ICE in the Pharmaceutical Industry "_and

"Investigation of the Determination of S0§” with IC"

100
III. Organic Analytical Research Division

Harry S. Hertz, Chief

Dennis J. Reeder, Deputy Chief

A. Division Overview

The Organic Analytical Research Division conducts research to develop

and improve techniques for the preparation, purification, characterization,

and analysis of organic compounds and uses these techniques in the solution

of analytical problems related to national needs. The Division's research is

carried out by six groups organized along functional lines: Bioanalytical

Techniques, Electrochemistry, Gas Chromatography , Liquid Chromatography, Mass

Spectrometry, and Spectroscopy. During the past year, the Division has been

actively engaged in the application of organic analytical chemistry to measurement problems related to energy, the environment, health and clinical

chemistry, and food and nutrition (an area in which we foresee increasing need

for accurate analytical chemistry and Standard Reference Materials). Results

of Division research are utilized by other Federal agencies, industry, public

and private institutions, and research programs at the National Bureau of

Standards

Substantial progress has been made in research on basic techniques in

organic analytical chemistry and in furthering our understanding of measurement principles in this area. The Division is now actively involved in two

competence building programs, selected for funding by the NBS Director.

Results of our research in these two areas. Organic Electrochemistry and the

Analysis of Ionization Mechanisms and Ion Structures, as well as highlights of

other technical accomplishments during the past year, are contained in the

group overviews and individual technical highlights which follow.

A major achievement of the past year was completion of an international

collaborative study between NBS and the Karolinska Institute in Stockholm,

Sweden, which resulted in the first successful intercomparison of definitive

clinical chemical methodology. Results of the study indicate good agreement

between NBS and Swedish isotope dilution mass spectrometric measurements of

serum cholesterol. Research in two-dimensional NMR spectroscopy was extended

to the total analysis of the proton NMR spectra of a- and 3-Q-glucose, the

principal constituents of SRM D-glucose. Two-dimensional proton NMR has also

been applied to several additional molecules including digoxin, which is being

evaluated as a candidate SRM and for which a definitive method for its determination in serum will be pursued. A new interface has been designed and

installed to permit capillary column gas chromatographic operation of our Fourier transform infrared (FT-IR) spectrometer with simultaneous acquisition

of a flame ionization detector signal. In response to EPA needs in the

development of a Master Analytical Scheme for organic pollutants in water, NBS

has supplied "marker compound" solutions to be used in evaluating the quantitative accuracy and viability of the scheme. In the organic electrochemistry

program, research has been initiated on chemically modified electrodes and a mathematical model has been developed for electron transfer processes in

molecules with interactive multiple redox centers. We have also begun some exciting research on the use of on-line multidimensional liquid chromatography

for the quantitation of individual analytes in complex samples.

101
Research on a number of challenging SRM's has been completed or is

nearing completion. Amongst these SRM's are air particulate matter certified

for polynuclear aromatic hydrocarbons , a polychlorinated biphenyl (PCB) in

transformer and lubricating oil, a purified decapeptide (angiotensin), and a human serum certified for the two most recently approved anticonvulsant

drugs, valproic acid and carbamazepine.

As in past years, the Division continued to perform service analyses for

other groups. Analyses have included samples for the FDA relating to the

determination of the cause of Toxic Shock Syndrome, calibration of the optical

rotation of quartz control plates for the sugar industry, and identification

of oxidation products of polystyrene for the Polymers Division at NBS.

Recently, we have been fortunate to have two people on sabbatical leave from

universities temporarily join our staff through the Intergovernmental Personnel

Act. They are working on problems relating to the pilot National Environmental

Specimen Bank and the development of selective detection techniques in

chromatography.

In the coming year we hope to initiate a new program in bioanalytical

technology. A presentation on Proteins in Analytical Chemistry was recently

given to the NBS Director as one of this year's competence building proposals.

We believe that a major key to the future in sensitive, selective and precise

quantitation in complex samples will be through the use of proteins as analytical reagents. We look forward to initiating research in this area.

With the arrival of an advanced pulse programmer, currently on order, we plan on extending our NMR research efforts to include heteronuclear twodimensional NMR and sensitivity enhancement by cross polarization techniques.

We plan on extending our research effort in GC/FT-IR spectroscopy to isotope

dilution GC/FT-IR for the quantitative analysis of trace constituents in

complex samples. The competence building program on the analysis of ion

structures will be directed toward the investigation of collisional activation

and laser induced metastable ion generation for the analysis of large organic

molecules. In the competence building program in organic electrochemistry,

research on chemically modified electrodes will be expanded and recently

developed mathematical models will be used in understanding the redox phenomena which occur at polymer modified electrodes. Our research efforts in

on-line multidimensional LC will be expanded to the more difficult task of

quantitating polar compounds in complex samples.

Major programmatic thrusts during the next few years are seen in two areas. The first, already briefly mentioned, is food and nutrition; we see an increasing need for accurate analysis of organic nutrients, as well as food

contaminants and natural toxins. The proceedings of a workshop held at the

Bureau to discuss Reference Materials for Organic Nutrient Measurements have

been compiled and recommendations have been made for the currently most useful

and technically feasible SRM's for water-soluble and fat-soluble vitamins. The

second area of major impact will be the analysis of organic constituents in

hazardous wastes. Current indications are that a firm scientific basis will

be required for the promulgation of further regulations in this area. This

will put a heavy burden on developing accurate methods and reference materials

for the analysis of these wastes. In addition to our initial research in this

102
I

1

,1 area, we recently have been called upon to proyi.de a critical, peer review of

the EPA-sponsored analyses of samples from the Love Canal area.

In summary, the future shows many promising areas of research in organic

analytical chemistry and no shortage of problems for the application of

research results.

1 . Bioanalytical Group: Overview

The mission of the Bioanalytical Group is to enhance the accuracy of

measurement of simple-to-macromolecule organic compounds of widespread

bioanalytical importance, through research employing enzymologic, electrophoretic,

immunologic, radiochemical, spectrophotometric , and thin layer chromatographic

techniques

A major thrust during the past year has been the continued development of

definitive methods for organic analytes in serum. The candidate definitive

method for uric acid is complete and a manuscript is in preparation. The

accuracy of the NBS candidate, definitive isotope dilution/mass spectrometry

(ID/MS) method for total serum cholesterol has been compared with the ID/MS

method developed at the Karol inska Institute (KI) which KI uses as a reference

method. The initial interlaboratory comparison of five serum pools revealed a bias between the two methods: all the mean values (n = 8) obtained at the KI were lower than the NBS means, the average difference was -1.3 percent. NBS

traced the source of bias to the impure cholesterol KI used as primary standard. With NBS SRM cholesterol used at the KI and new analyses for comparison,

the bias was removed. The average difference in means was +0.2 percent, which

was not significant since the new KI mean values differed as much as ±1.5

percent from the NBS values. In both comparisons, the standard deviations of

the NBS results were several -fold smaller than the KI's. The intercomparison

is described in a joint paper submitted to Clinical Chemistry .

Multi laboratory test data have been gathered for evaluating the American

Association for Clinical Chemistry's (AACC) hexokinase/glucose-6-phosphate

dehydrogenase candidate reference method for serum glucose. The Bureau's

initially developed ID/MS method for glucose involving diacetone glucose

(DAG), was used for determining the target values for the serum pools employed

in the evaluation of the candidate reference method. The evaluation and the

ID/MS method are now the subjects of a manuscript undergoing NBS review.

Publication was withheld because after these studies were initially thought

to be complete subsequent analyses by both methods revealed different and

unexpected results. These are now known to be due to changes in serum glucose

levels that occurred during storage at -20 °C.

At the current time, and in FY 1982, research continues on the development

of definitive ID/MS methods for creatinine and urea. In 1982, it is anticipated that research will begin on triglyceride and digoxin definitive methods.

We have participated in the development of a reference method for total serum protein in cooperation with the Standards Committee of the AACC. NBS

SRM 927, Standardized Protein Solution, is used for calibrating the method.

i 103
Schaffer and Reeder are co-authors in the two papers on this subject,

published in Clinical Chemistry .

Following a protocol devised by Dr. Robert McComb at Hartford Hospital,

our Group participated in a round robin with four other laboratories performing accurate measurement of lactate dehydrogenase activity in lyophilized

human serum. It was necessary to know the reaction temperature within 0.1 °C,

with the further requirement that the reaction be run within 0.3 °C of 29.77

°C, the gallium melting point. For the most recent round robin, the activity

found was 233.7 U/L with a relative standard deviation of 4.99 percent.

For an FDA-sponsored study on the identification and physiological effect

of leachable materials from polymeric implants used for human patients, we developed a reliable assay for prolyl hydroxylase activity, using highly

labeled substrate and active enzyme, both prepared in our laboratory. The

enzyme is involved in the formation of collagen which is believed to be a cause for the failure of silicone polymer breast implants; it has been

postulated that the leachable compounds enhance enzyme activity.

In continuing research on the extension of immunoassay procedures to the

analysis of industrial effluents, considerable effort has gone into the

organic synthesis of a tracer compound that has both a fluorescent moiety and

a dinitrophenol structure. Pilot batches of such a tracer were prepared by

reacting fluoresceinamine (Isomer I) and 2,4-dinitrobenzene sulfonylchloride.

Although the compound is still not pure, there is good evidence that this

synthetic procedure produces sufficiently active tracer to make it useful in an immunoassay. Work has also been focused on the selection and purification

of specific antibodies by means of affinity column purification methods. In

the near future, we will be directing our efforts toward developing other

solid-phase reagents, and increasing the reproducibility and sensitivity of

the immunoassay system.

In conjunction with the Electrochemistry Group, we found evidence for the

chemical equivalency of carbonyl oxygen and dicyanomethylene groups in a series

of croconate salts, and have proposed a mechanism for the superconductivity of

potassium croconate violet. Three papers on these subjects are in preparation.

Finally, during the past year, we presented a competence proposal on Proteins in Analytical Chemistry to the Director of NBS. This area of

research, we believe, will play a major role in the future of analytical

chemistry and we anxiously look forward to our expanded involvement. Initial

efforts will be directed toward utilization and standardization of twodimensional electrophoresis.

Robert Schaffer, Group Leader; Alex Cohen, Alexander J. Fatiadi,

Barbara F. Howell, Dennis J. Reeder

104
2. Electrochemistry Group: Overview

The competence building program in organic electrochemistry has made

good progress in the chosen research directions and we have begun applying

this research to NBS programmatic areas. During the third year of this

effort, full staffing has been maintained and most of the major pieces of

equipment are now operational although some needs still exist for instrumentation to achieve our planned research goals.

Our activities are now focused on the study of organic redox reactions

using state-of-the-art electrochemical techniques: cyclic voltammetry and

rotating ring-disk electrochemistry; hybrid techniques such as spectroelectrochemistry and liquid chromatography with electrochemical detection; the

preparation, study, and application of chemically modified electrodes; and the

theoretical modeling of electrochemical processes in support of the other

research areas.

In the area of spectroelectrochemistry, the setting up and evaluation of

vidicon and diode array detectors for the optical multichannel analyzer has

been completed. Using an optically transparent thin-layer cell with a gold

minigrid working electrode, the spectroelectrochemical behavior of the very

complex blue copper protein, ceruloplasmin, is being investigated. Since

metal loenzymes of this type normally undergo irreversible heterogeneous

electron transfer, the first part of this research project involves the study

of redox mediators which facilitate electron transfer. Initially, these are being studied as homogeneous electron transfer mediators, but they may

eventually be bound to the metallic electrode substrate to function as chemically modified electrodes which will catalyze these redox reactions at the

electrode surface directly. Spectroelectrochemical studies have also been

performed on croconate salts (which are excellent model compounds because the

intense coloration of croconate solutions can be reversibly altered by

electrochemical means) and also interesting chemicals as a consequence of

their semiconductor behavior and potential use as el ectrochromic display

materials. As part of this research, a special multipurpose cell was designed

for performing spectroelectrochemical studies and other types of aqueous and

nonaqueous electrochemistry.

Surface-enhanced Raman spectroscopy has been the most recent project

initiated in the area of spectroelectrochemistry . While the initial research

has been concerned with the study of the interactions of pyridine derivatives

with silver and mercury electrodes, it is expected that this technique will

prove to be extremely useful in studying the orientation and conformation of

molecules bound to electrodes in our chemically modified electrode research.

In addition, it is expected that these studies will help to explain the

surface-enhancement phenomenon for which no accepted theory exists.

The development of electrochemical detectors for liquid chromatography

has continued with the use of dual -electrode sensors and modulated excitation

waveforms to achieve maximum selectivity and sensitivity for a variety of

important analytes. This technique is being applied to the determination of

organomercury species in fish tissue and the pilot National Environmental

Specimen Bank samples. In addition to the development of the electrochemical

detectors themselves, considerable effort is being applied to the elucidation

105
of the electrochemical processes occurring at the generator and detector

electrodes and to the sample extraction techniques that are required to

maintain the integrity of the analyte species.

The research project on chemically modified electrodes is being applied

to the development of an amperometric sensor for halogenated hydrocarbons such

as polychlorinated biphenyls and organochlorine pesticides. The proposed

sensor will electrocatalytical ly reduce these types of compounds via nickel

Schiff-base complexes which act as redox centers and are attached to the

metallic electrode by means of polyphenylene oxide films. An alternate

approach will employ a polyvinyl ferrocene polymer attached to the electrode

substrate. It is planned to use these electrodes directly as selective and

sensitive sensors and also as detectors in chromatographic systems.

In response to needs in several Division programs, research is continuing

on a photoelectrochemical sensor for carboxylic acids. This device is based

on a semiconductor electrode, n-type Ti02» which, when irradiated by UV light, causes the oxidation of carboxylic acids at very low applied potentials.

Since the oxidation of water interferes with the direct determination of the

carboxylic acids, an indirect approach monitoring the carbon dioxide produced

in the photo-Kolbe reaction has been employed. Initial experiments using a gas-permeable membrane and differential conductance measurements have

demonstrated the feasibility of this approach, but response was too slow for

practical use. Work is continuing using a carbon dioxide electrode in an attempt to increase the response time of this system.

Redox process modeling and digital simulation have been used to develop

models to obtain thermodynamic and kinetic reaction parameters. An example

of this work was the derivation of a mathematical model for electron transfer

in molecules with interacting multiple redox centers. It is expected that

these models will be useful in explaining the redox phenomena that occur at

polymer modified electrodes. More recently, theories and simulations have

been developed to describe the current-time behavior in chronoamperometry

employing unshielded disk electrodes and in determining diffusion coefficients

from such experiments.

Our plans for the coming year call for continued research on the above

projects with expanded efforts in the area of chemical modification of electrodes as selective organic sensors. These basic studies are expected to be

rapidly adapted to address the analytical needs of the Center.

Richard A. Durst, Group Leader; Elmo A. Blubaugh, Kathryn A. Bunding,

Lawrence M. Doane, Mary Lou Fultz, William A. MacCrehan, William T. Yap

106
3.

Gas Chromatography Group: Overview

During FY 1981 the Gas Chromatography (GC) Group has pursued basic

analytical research in the design and implementation of an advanced GC Fourier

Transform Infrared (FT-IR) interface. The interface now contains a Nicolet

experimental low dead volume light pipe which improves spectral sensitivity

and a flame ionization detector (FID) which allows simultaneous FID/FT - I

detection. A spectral library containing over 60 vapor phase IR spectra of

polychlorinated biphenyl isomers has been constructed and will be used for

PCB isomer identification and quantitation on real-world samples. The Group

also demonstrated that it is feasible to perform isotope dilution gas

chromatographic (ID/GC) analyses using FT-IR detection and in FY 1982 plans

on developing a method for I D/GC/FT- I R quantitation using polynuclear aromatic

hydrocarbons (PAH) in environmental samples. Additionally, a large amount of

software has been written in the last year in support of our GC/FT-IR research.

In the last year, we have prepared mixed liquid crystal -si 1 icone polymer

stationary phase wall-coated open tubular (WCOT) columns and have shown that

these columns yield superior separations of PAH over conventional silicone

phase WCOT columns. Software has been written for the determination of the

correlation between molecular structure and chromatographic retention, and

additional routines have been written for general data reduction.

The group has been actively involved in the Standard Reference Material

program. We have participated in the certification of five new SRM's:

1. Polynuclear Aromatic Hydrocarbons in Acetonitrile, SRM 1647

2. Polychlorinated Biphenyls in Oil, SRM 1581

3. n-Heptane (Engine Octane Number Standard), SRM 1815a

4. Polynuclear Aromatic Hydrocarbons on Air Particulate Matter, SRM 1649

5. Valproic Acid and Carbamazepine in Human Serum, SRM 1599

The certification of the PAH SRM's required the use of newly implemented

state-of-the-art on-column injection techniques. The Group has also completed

a study of the feasibility of the preparation and certification of a halocarbons in drinking water SRM and will begin certification measurements in

FY 1982.

During FY 1981 we have performed numerous service analyses and conducted

several studies for other agencies. We prepared, analyzed, and determined the

short range stability of a solution of organic compounds in hexane to be used

by EPA for calibration of its Level I analysis method. The solution contained

nine compounds of varying chemical polarity ranging from dodecane (nonpolar)

to benzoic acid (very polar), with specific compounds falling into the various

column chromatographic fractions of EPA's Level I method.

The stability of marker compound solutions for EPA's Master Analytical

Scheme was monitored by GC analysis. (More details of this collaborative

project are contained in the Mass Spectrometry Group Overview.) In addition,

analyses were performed for the pilot National Environmental Specimen Bank,

human polymeric implant leachables program, the NBS recycled oil program, a Department of Energy analytical quality assurance program, and a Department

107
of Energy program to identify compounds in aqueous leachates from hazardous

wastes.

During FY 1982 the Group will continue its research into multidimensional

chromatography and will apply this technique to the separation and quantitation of nitrogen-, sulfur-, and perhaps oxygen-heteroaromatic compounds found

on particulate matter. Research on selective detection will also be continued

using the existing FT-IR, conductivity, nitrogen, electron capture detectors,

and a new sulfur/phosphorus photometric detector requested in our equipment

planning.

Stephen N. Chesler, Group Leader; Sharon L. Bowie; Delmo Enagonio,

Franklin R. Guenther, Reenie M. Parris

4. Liquid Chromatography Group: Overview

The major emphasis of the research in the Liquid Chromatography Group

continues to be focused on the development of high-performance liquid

chromatographic methods for the analysis of individual compounds in complex

mixtures. The applications of our research continue to be concentrated in

the environmental and biomedical areas, although we have, during the past

year, begun to address separation problems in the food and nutritional area,

also.

Specific research accomplishments for the past year include: (1) Development of a relationship between polynuclear aromatic hydrocarbon (PAH) retention

in reversed-phase HPLC and PAH partition behavior in a n-heptadecane ( C- 1 7 )

/

acetonitrile/water model system. We found the solvent effects between the

C-17 partition model and reversed-phase C-18 columns to be equivalent,

indicating that differences in selectivity among C-18 columns are due to innate

differences in the stationary phase and not to "salting out" effects from the

mobile phase as proposed by Locke [1]. (2) Development of an on-line multidimensional system for the analysis of PAH in complex samples. This system

features the on-line coupling of normal- and reversed-phase chromatographic

systems using column affinity sequencing. (3) Continued development and use of our gas saturation-HPLC method for measuring ambient temperature vapor

pressures of non-volatile compounds. This procedure is an extension of our dynamic coupled-column liquid chromatographic procedure for determining

aqueous solubilities of PAH. Saturated vapor streams are generated by passing

dry nitrogen through a column packed with analyte-coated sand. The analyte is

extracted from the stream cryogenical ly either on a coil, or on a C-18 adsorption trap prior to quantitation by HPLC. We have been able to measure vapor

pressures down to 10" 4 Pa using this technique. (4) Development of a sequential HPLC-fluorometric method for determining amino-PAH in complex

mixtures. Amino-PAH are isolated from the matrix using chromatography on an aminosilane (NH2 ) column with a hexane/methylene chloride mobile phase.

Quantitation is performed on an octadecylsilane column using an acetonitrile/

water mobile phase and spectrofluorometric detection. This technique has

been used to determine naphthyl amines and aminoanthracenes in shale oil, coal

liquids, and petroleum products. (5) Development of a Soxhlet extraction,

nitromethane partition, HPLC-fluorometric procedure for quantifying selected

108
PAH on air particulate matter. (6) Initiation of a study of the retention

characteristics of aza-arenes and sulfur aromatics on C-18 and NH 2 columns.

The LC Group has actively participated in the NBS Standard Reference

Material (SRM) programs. During the past year, work on three SRM's has been

completed. In SRM 1647, PAH in Acetonitrile, we determined the concentrations of the sixteen PAH on the EPA Priority Pollutant List. This SRM will

be used as a calibrant in the liquid and gas chromatographic analysis of PAH.

In SRM 1599, Anticonvulsant Drugs in Serum, we determined carbamazepine and

valproic acid in a lyophilized human serum matrix. This SRM will be used as

a quality control standard by clinical laboratories doing such assays. In

SRM 910, Sodium Pyruvate, we have completed certification with comparative

NMR and HPLC determinations of the concentration of pyruvate dimer. Sodium

pyruvate is used as a substrate for measurement of the enzyme, lactic acid

dehydrogenase.

Several other SRM certification activities are currently in progress.

HPLC procedures are being used for purity determination of angiotensin,

determination of ten polynuclear aromatic hydrocarbons on an air particulate

sample, and certification of an indeno(l ,2,3-cd)pyrene generator column.

During the past summer, the Group has acquired the services of

Dr. Freeman Allen, Pomona College, Claremont, CA, and Dr. Cora Vogt, University

of Missouri Trace Analysis Group, Columbia, MO. Both are spending one-year

tours of duty at NBS as part of the Intergovernmental Personnel Act program.

In FY 1982, we plan to continue our program in reversed-phase retention

mechanisms. Emphasis will be placed on investigating the effects of surface

coverage and bonding type (monomer or polymeric) on chromatographic selectivity. A large portion of our research time will continue to be devoted

toward developing selective detection procedures for HPLC effluents. In this

regard, we plan to explore the use of electrochemical techniques for selective

detection of nitroaromatics, evaluate an in-house constructed light pipe as a tool for improving sensitivity in LC/Fourier transform infrared spectroscopy,

and evaluate an in-house constructed ultrasonic probe as a tool to allow us to perform quantitative reversed-phase LC/mass spectrometry.

We plan to further develop our on-line multidimensional HPLC system and

investigate the feasibility of determining more polar compounds ( i . e . , aza- arenes, amino-PAH, phenols) using this approach. Finally, as a continuing

effort in our food and nutrition research program, we plan to further

investigate the chromatographic behavior of fat-soluble vitamins in an attempt

to develop at least two independent analytical procedures for each of several

vitamins.

Reference

[1] Locke, D. E. J. Chromatog. Sci., 12: 433; 1974.

Willie E. May, Group Leader; C. Freeman Allen, Jeanice M. Brown-Thomas

Richard G. Christensen, William F. Cuthrell, Walter F. Kline, Pamela J. Leech,

Sam A. Margo! is, William J. Sonnefeld, Cora R. Vogt, Patricia A. White,

Stephen A. Wise

109
5. Mass Spectrometry Group: Overview

The major continuing efforts of the Mass Spectrometry Group have been

directed to the development of mass spectrometric methods for the accurate

quantitation of individual compounds in complex mixtures, the development of

high-resolution mass spectrometric techniques for the analysis of high molecular weight compounds, and the development of a new liquid chromatography mass spectrometry (LC/MS) interface suitable for the analysis of analytes requiring

reversed-phase LC. Other agency and programmatic research continues to be

concentrated in the environmental and clinical areas. A major new effort

which is part of the competence building program on "Analysis of Ionization

Mechanisms and Ion Structures" began this year.

Isotope dilution definitive methods development for the quantitation of

human serum constituents has continued in collaboration with the Bioanalytical

Techniques Group. A human serum Standard Reference Material, SRM 909, was released in September, 1980 with certified values for glucose and uric acid.

Cholesterol certification was completed this year. The results of a cooperative study with the Karol inska Institute comparing two isotope dilution/mass

spectrometry (ID/MS) methods for cholesterol have been accepted for publication

in Clinical Chemistry and a manuscript describing and comparing two ID/MS

methods for glucose developed at NBS has been prepared. Method development

is in progress for urea and creatinine in serum.

Further work has been done on the development of an LC/MS interface. The

LC/MS interface employing continuous sample preconcentration which was developed during the last several years and an example of quantitation using

the system has been published. A new design of the probe utilizing ultrasonic

nebulization allows the use of aqueous mobile phases.

Two projects utilizing the high resolution mass spectrometry facility are presently producing interesting results. In one, a method to obtain complete

high resolution field desorption spectra and accurate mass measurements using

silver sulfonate salts for mass calibration and photoplate detection has been

developed and tested on some peptides. The second project is part of the mass spectrometry competence building program, "Analysis of Ionization Mechanisms

and Ion Structures," and involves laser induced metastable ion generation as a selective probe for molecular structure. The photodissociation of ions created

by electron impact has been observed for a variety of molecules.

A survey of the literature and a limited series of GC/MS experiments have

been performed to explore the potential of negative chemical ionization mass spectrometry for quantitation. The first compounds studied were several

phenols and nitrogen-heterocycles. Neither gave better sensitivity than

positive chemical ionization. The phenols, however, produced interesting and

apparently unreported fragmentation which will be investigated further. Quantitative accuracy and precision will be explored for compounds with high

electron affinities such as halogenated pesticides and polychlorinated

biphenyls which are known to yield high sensitivities in the negative ion mode.

Methods have been investigated for the analysis of several aqueous

effluents from coal gasification, oil shale retorting, and petroleum refining

for selected phenolic and polynuclear aromatic hydrocarbon (PAH) species. A

110
simple extraction procedure followed by GC/MS using capillary columns and

selected ion monitoring was used for quantitative analysis. In an initial

survey, individual compound concentrations were determined for five PAH in the

range of 1 to 300 ppb and for five phenols in the range of 10 to over 1000 ppb.

Research has continued on development of isotopically labeled marker com- pound standards for use in the proposed Environmental Protection Agency (EPA)

"Master Analytical Scheme" for priority pollutant analysis. Additional sets

of internal standards consisting of two concentration levels each of three

mixtures and containing a total of twenty-one deuterated compounds have been

prepared and delivered to EPA. Work is in progress on establishing the

chemical and isotopic purity of compounds which are to be used for modified

internal standards sets to be delivered by the end of the year.

Research planned for the coming year includes: continuation of the

ongoing projects related to environmental problems with extension to new matrices and the investigation of negative ion chemical ionization for quantitation; further development of the isotope dilution definitive methods for urea and creatinine, initiation of work on methods for triglycerides and

digoxin, and implementation of improvements to the instrumentation used;

continued refinement and application of the NBS developed liquid chromatography/

mass spectrometry system; and, for the competence building program, completion

of major equipment installation and modification followed by the start of

investigations of the chemistry of several laser induced and collision induced

reactions of larger (molecular weights in the range of about 1000 daltons)

organic molecules.

Edward White V, Group Leader; Rafael Espinosa-Leniz , Laurence R. Hi! pert,

Stanley Meiselman, Kristy L. Richie, Lorna T. Sniegoski, Michael J. Welch

6. Spectroscopy Group: Overview

During the past year, the Spectroscopy Group has actively pursued research

in organic analysis by nuclear magnetic resonance (NMR) spectroscopy, polarimetry, and luminescence techniques, and has expanded its competence in the areas of (1) total carbon analysis by infrared methods and (2) the synthesis

of bioorganic intermediates needed in current research programs.

Our recent work in the area of microspectrofluorimetry includes demonstration of reproducibility of measurements and photomicrographs of Tb/Eu doped

fluorescent glass beads for a final report to the sponsoring agency, and

preliminary measurements on fluorescent standards for cracked plate analysis

and on diffusion of anti -oxidants in polyethylene (in collaboration with the

Polymers Division).

Preliminary fluorescence measurements with an optical multichannel

analyzer, necessary to produce excitation-emission matrices, have indicated

the presence of several instrumental and alignment problems in the system.

These are currently being studied in both static and flowing modes.

Ill
In connection with a Department of Energy program for analysis of waste

water, new instrumentation for analysis of total carbon content by infrared

techniques has been acquired and installed. The method is based on infrared

detection of carbon dioxide produced by combustion of the sample and has been

applied initially to DOE waste waters and an angiotensin SRM. Total carbon

measurements on Washington dust samples and leachates from blood storage bags are also in progress.

As part of an international effort to assure uniform methods of sugar

analysis, the optical rotatory dispersion of standard quartz control plates

has been investigated with the NBS high precision polarimeter, and the results

correlated by means of a four-parameter equation.

Activities of the Group in SRM certification include completion of the

sodium pyruvate and sucrose SRM's, determination of the ultraviolet absorptivities and fluorescence spectra of 16 polynuclear aromatic hydrocarbons

(PAH) to be used in SRM 1647 (Priority Pollutant PAH in Acetonitrile), and

completion of the testing of candidate materials for the tripalmitin SRM.

Procurement and packaging of the latter SRM are complete, and certification

measurements are underway.

Efforts this year in the area of NMR instrumentation have included

enhancement of the capability of the high field facility of the National

Measurement Laboratory by installation of a broad band probe and preamplifier,

and implementation of correlation NMR spectroscopy and the Redfield pulse

sequence. The broad band components give us a broad range of heteronuclear

capability in the high frequency range (45-165 MHz; 137 Ba- 31 P), whereas the

correlation and Redfield techniques permit improved suppression of strong

solvent signals, for example, the water signal from aqueous solutions of

biomaterials.

New methods for analysis of antibiotics by NMR are of considerable

interest to the pharmaceutical industry. In research designed to explore the

nitrogen-15 NMR capabilities of the WM-400 high field spectrometer, we have

studied the structural and conformational analysis of the fortimicin and

neomycin series of antibiotics. As a result of this collaborative research

with an NAS/NRC postdoctoral research associate, a new method for analysis of

the fortimicin series has been developed that is based on interpretation of

proton coupled nitrogen-15 spectra obtained by suppression of NH proton

exchange in trif luoroacetic acid solutions. Studies of neomycin B and its

components by high field proton and nitrogen-15 NMR and gadolinium cryptate

spin-labeling techniques have led to definition of the complete solution

conformation of neomycin B, and the measurement of pK

Q

values for individual

nitrogens in the antibiotic from nitrogen-15 NMR titration curves has been

used to characterize the major ionic form present in neomycin sulfate

preparations.

As part of another postdoctoral research associate project directed

toward the synthesis and analysis of anti -tumor nucleosides, a new, efficient

synthesis of 2-ami no-oxazol ine intermediates has been delineated which involves

the reaction of glycosylamine derivatives with cyanamide. The method has been

applied to the preparation of derivatives doubly labeled with nitrogen-15, and

112
the products have been characterized by 1 H, 13 C, and 15 N NMR spectroscopy,

mass spectrometry, and reversed-phase HPLC.

During the past year, high field proton NMR has also been used for characterization of compounds of interest to research projects in other Groups in the

Division and in other Centers. This has included leachables from silicone and

polyurethane implant materials, proposed antiepilepsy drug standards--valproic

acid, tegritol, and cyheptamide, a dinitrophenyl derivative prepared for use in

the immunoassay of nitrophenol s, analysis of the kinetics of the alkaline

degradation of NAD and characterization of the products of accelerated degradation of solar heat exchange fluids.

By means of two-dimensional, proton NMR at 400 MHz, the complex 12-spin

systems of a- and 3-Q-glucose (the principal components of SRM D-glucose)

have been analyzed completely for the first time. Two-dimensional (2D) NMR

spectroscopy has also been used to examine fortimicin B, and the purity of

digoxin and digitoxose, studies which are also expected to indicate the

feasibility of a complete analysis of the complex proton NMR spectra of

digoxin. Digoxin is a candidate SRM and an analyte for which a "definitive"

method for serum analysis is needed.

With the eventual delivery of an advanced pulse programmer for high field

NMR, we look forward to extension of our analytical capability into heteronuclear, two-dimensional techniques and into sensitivity enhancement by cross polarization methods. In the future, the availability of a broad band probe

will permit the NMR analysis of other low abundance, "organic" nuclei such as

2 H and 17 0, together with a range of metal nuclei.

Future plans in the area of low temperature fluorescence include the use

of a helium cryostat to facilitate development of quantitative matrix

isolation and Shpol'skii spectroscopic techniques.

Bruce Coxon, Group Leader; Robert E. Botto, Robert M. Davidson,

Diane K. Hancock

113
B. Selected Technical Accomplishments

(Organic Analytical Research Division)

1 . Relationships Between Liquid/Liquid Partitioning and Retention in

Reversed-Phase Liquid Chromatography

Despite the heavy use of high-performance liquid chromatography in

analytical chemistry, we lack the capability to utilize this chromatographic

technique to its maximum potential because of the absence of a thorough

understanding of the physico-chemical foundations for chromatographic

retention and selectivity. In order to better understand chromatographic

retention and selectivity, we are using polynuclear aromatic hydrocarbons

(PAH) as molecular probes to determine the roles that both the stationary

and mobile phases play in the retention mechanisms of reversed-phase highperformance liquid chromatography. The present work is an attempt to

relate reversed-phase retention to the simple thermodynamic partitioning

between ii-heptadecane (C-17) and acetonitrile/water mixtures.

On partition between C-17 and aqueous acetonitrile, the following

relationship was found to be valid for all PAH examined:

In K' = X ( 1 n Kq

H 3CN - In K^q) + In K^Q [1]

where K' is the molar-partition coefficient between C-17 and the aqueous

acetonitrile, and

q are the molar partition coefficients for

pure acetonitrile and pure water, and X is the volume fraction acetonitrile.

Since In - In

q

is equivalent to the natural log of the partition

coefficient between water and acetonitrile, this term is independent of the

other phase and is dependent only on the PAH and the temperature.

Reversed-phase liquid chromatography of the same PAH on both monomeric

and polymeric octadecylsilane (C-18) columns yielded a similar relationship

for the molar specific capacity k' and the volume percent acetonitrile.

In k

1 = X(ln k^^ - In k^

Q

) + In k^

0 [2]

The In k^

H CN

" ^H 0

term 1S independent column type and equivalent

to the corresponding partition term for each PAH.

This equivalence of solvent effects between the C-17 partition model

and reversed-phase C-18 columns suggests that differences of selectivity

between columns are due to innate differences in the stationary phase and

not to "salting out" effects from the solvent. Plots (Figures 17A and

17B) of the partition coefficient K vs. the specific capacity k' for each

individual PAH differ significantly between monomeric and polymeric C-18

columns. The monomeric column appears to be selective on the basis of

aromatic carbon number alone, while the polymeric column appears to be

selective on both an aromatic carbon number and shape basis. For six

unsubstituted PAH on the polymeric column, a relationship is being investigated between the 1 ength-to-breadth ratio, L/B, aromatic carbon number,

n, and the apparent phase ratio, <p (slope of K vs. k' plot). (Preliminary

work suggests that for the monomeric column <j> = A'n + B

1 .) Further

114
Figure 17A. Abbreviations. DBACA = Dibenz[a,c]anthracene, DBAHA = Dibenz-

[a ,h]anthracene, BCC = Benzo[b]chrysene, CHR = Chrysene, BBA = Benz[a]anthracene, ANTH = Anthracene, PHEN = Phenanthrene.

refinements to this model are necessary using data from other PAH including

methyl -substituted PAH.

If these relationships prove valid for additional PAH, capacity factors

and, hence, selectivities can be predicted for polymeric columns from monomeric

column data and vice versa.

Additional work on low, average, and high coverage polymeric columns

suggests that the retention process is not due to any single mechanism but

a mixture of two or possibly more processes. If a relationship can be

found between column coverage, retention, and molecular parameters such as L/B and n, the possibility exists for tailoring columns to specific PAH

separations for both regular and multidimensional chromatography.

115
Figure 17B. Abbreviations. DBACA = Dibenz[a,c]anthracene, DBAHA = Dibenz-

[a ,h]anthracene, BCC = Benzo[b]chrysene, CHR = Chrysene, BBA = Benz[a]anthracene, ANTH = Anthracene, PHEN = Phenanthrene.

W. E. May, P. A. White, S. A. Wise

2. Development of an On-Line Multidimensional HPLC System for Quantitative

Analysis of Individual Constituents in Complex Samples

The success of the quantitative and qualitative chemical analysis of

individual compounds in complex mixtures is dependent upon the resolving

power of the analytical system used. Both reversed-phase and normal -phase

high-performance liquid chromatography (HPLC) are useful for the separation

of organic compounds, yet even the most selective and efficient HPLC columns

currently available are unsuccessful in resolving all the components in

complex mixtures. The determination of individual species generally requires

the use of several chromatographic modes of analysis and/or selective detection. In the past we have advocated the use of normal-phase HPLC on a polar

chemically bonded amine phase for the separation of polycyclic aromatic

hydrocarbons (PAH) based on the number of aromatic carbons, followed by a

116
separation of the various PAH isomers and/or al kyl -substituted PAH in a given

fraction by reversed-phase HPLC. This sequential HPLC method has been employed

to quantify selected PAH in several virgin and used lubricating oils, a shale

oil, a coal liquid, and a petroleum crude. We are currently extending this

method to include nitrogen and sulfur heterocyclic compounds as well as amino- and nitro-substituted PAH.

The off-line multidimensional HPLC analytical procedure [1] previously

developed by our group involves the collection of the desired fraction from

the normal-phase column, evaporation of the solvent to near dryness, and

redissolution of the fraction in an appropriate solvent for the final reversedphase determination. Disadvantages of this method include: (1) the manipulation

of small (20-1000 yL) volumes of eluent which can lead to possible sample

contamination and/or losses due to either volatilization or adsorption on container walls; (2) the variability of the volume from which aliquots are taken requires the use of volume correction factors; (3) degradation of the

system detection limits is observed since only a fraction of the eluent can

be injected onto the reversed-phase analytical column; (4) the high demand on operator time increases the cost of the analysis since the approach is not

easily automated.

To eliminate some of these disadvantages, an on-line system coupling a normal-phase chromatographic system to an analytical reversed-phase system

has been designed (see figure 18). This system allows for the concentration

of a selected fraction from the normal -phase HPLC column on a concentrator

column. The solvent is then purged with nitrogen and the concentrator column

coupled to a reversed-phase system where the fraction can be further separated.

To demonstrate the applicability of this on-line system for the analysis

of PAH in complex matrices, samples of NBS SRM 1580 (Organics in Shale Oil),

a solvent refined coal liquid, and a Wilmington crude oil were analyzed for

several individual PAH. The results of the multidimensional on-line analysis

are listed in Table 13 along with the certified values for SRM 1580 and the

earlier off-line sequential HPLC values. No statistical bias is noted

between the values, and the precisions of the on-line and off-line methods

are comparable.

We are currently extending this system to include other groups of

compounds.

Reference

[1] Wise, S. A.; Chesler, S. N.; Hertz, H. S.; Hilpert, L. R.;

May, W. E. Anal. Chem. 49: 2306; 1977.

W. E. May, W. J. Sonnefeld, S. A. Wise

117
Solvent

Delivery

System

Waste

Reversed

Phase

Normal

Phase

(Isocratic)

.

Solvent

Delivery

System

118

Figure

18.

On-line

multidimensional

system.
Table 13. Comparison of On-Line Multidimensional Results with Off-Line Results.

Multidimensional HPLC Multidimensional HPLC

3 3 Compound (on-line) (off-1 ine)

SRM 1580 (Shale Oil)

(Concentration in yg/g)

Fluoranthene 53.8 + 3.5 (3)

b

53 ± 2 (9)

Pyrene 109.7 + 7.1 (3) 107 ± 8 (10)

Perylene 2.32 + .15 (5) 3.9 ± .6 (11)

Benzo[a]pyrene 20.7 + 2.2 (8) 23 ± 1 (8)

SRC II Coal Liquid

(Concentration in mg/g)

Fluoranthene 3.15 ± .04 (3) 3.3 ± .16 (3)

Pyrene 6.65 ± .05 (3) 6.0 ± .2 (3)

Perylene 0.024 ± .002 (3)

Benzo[a]pyrene 0.133 ± .008 (5) 0.134 ± .007 (3)

Benzo[e]pyrene 0.153 ± .006 (3) 0.143 ± .005 (3)

Benzo[k]fluoranthene 0.062 ± .001 (5)

Wilmington Crude Oil

(Concentration in yg/g)

FI uoranthene 2.4 ± .3 (3) 3 ± 1 (3)

Pyrene 14.8 ± 2.2 (3) 14 ± 2 (3)

Uncertainty is 1 standard deviation.

b(n) indicates the number of replicate measurements.

Certified

54 ± 10

104 ± 18

3.4 ± 2.2

21 ±6

119
3. Methods for the Determination of Selected Polycyclic Aromatic Hydrocarbons and Aza-arenes on an Urban Air Particulate Sample and SRM

Certification of the Sample

Many regulatory programs of the U.S. Government emphasize the need to

collect data on the concentration, distribution, and personal exposure to

organic pollutants in air. Organic air pollutants of particular interest,

because of their ubiquitous nature and carcinogenic properties, are the

polycyclic aromatic hydrocarbons (PAH). At NBS, two large samples of urban

air particulate material [Standard Reference Material (SRM) 1648 "Urban Air

Particulate Matter" (from St. Louis, MO) and urban particulate matter (from

Washington, DC)] have been used for the development of analytical methods

for the characterization and quantitation of PAH extracted from them.

SRM 1648, which is issued in 2-g quantities, is not certified for organic

constituents. However, a number of analysts have expressed interest in the

organic constituents in this SRM for use in analytical methods evaluation,

intercal ibration, and biological testing studies. As a result, NBS will

issue 10-g quantities of the Washington urban particulate matter as SRM 1649

certified for the concentrations of ten major PAH. During the past year,

the analytical methods [i.e., extraction, isolation, and gas chromatographic

(GC) and high-performance liquid chromatographic (HPLC) methods for analysis]

have been developed for the certification of SRM 1649.

The extraction of air particulate matter with an organic solvent system

(e.g., methylene chloride or benzene/methanol), using a Soxhlet extractor,

results in a complex mixture of organic constituents from which the PAH

must be isolated prior to identification and quantitation by GC and HPLC.

Prior to analysis by high resolution capillary gas chromatography , the PAH were isolated from the complex organic extract (obtained with 1:1 benzene/

methanol) using a solvent-solvent partition of N,N-dimethylformamide (DMF)

and water to remove aliphatic hydrocarbons, followed by a normal -phase HPLC

separation to remove the more polar aromatic constituents such as aza-arenes. Quantitation of the selected PAH was relative to an internal standard,

1 -methyl pyrene, added to the sample prior to extraction.

In the HPLC analyses, quantitation was accomplished using fluorescence

detection to achieve the selectivity necessary to quantitate individual

compounds in the complex mixture. The sample was extracted with methylene

chloride; then the extract was partitioned between cyclohexane and nitromethane to remove some interfering constituents prior to analysis. Because

of the selectivity of the HPLC fluorescence detection for PAH compared to

the universal flame ionization detection for GC, a less rigorous PAH isolation

procedure was used for the HPLC analysis than for the GC (i.e., cyclohexane/

nitromethane partition vs. cyclohexane/DMF/water partition and HPLC). This

selectivity is illustrated in figure 19 for the HPLC analysis of the air

particulate extract. In the upper chromatogram, a UV absorption detector is

used for detection, whereas in the middle and lower chromatograms six

different fluorescence excitation and emission wavelength combinations are employed to optimize the selectivity/sensitivity for various PAH. HPLC

quantitation is based on an internal standard of 7-methyl fluoranthene.

Preliminary HPLC and GC analyses indicate the following concentration ranges

for several major PAH; pyrene, fluoranthene, benzo[b]fluoranthene.

120
uv

254nm

Fluorescence

>-

0 10 20 30 40 50

Time (min)

Figure 19. Liquid chromatographic separation of PAH isolated from air

particulate matter with UV detection (upper chromatogram)

and fluorescence detection at various excitation and

emission wavelengths (middle and lower chromatograms).

121
benzo[ghi]perylene, 5-6 yg/g; phenanthrene , benz[a]anthracene , chrysene,

benzo[k]fluoranthene, 3-5 yg/g; and perylene and dibenz[a,h]anthracene,

%0.5 yg/g.

The Washington urban particulate material is also being used to develop

analytical methods for the isolation and characterization of other classes of

polycyclic aromatic compounds in air particulate material in addition to the

major PAH, i.e., nitrogen, sulfur, and oxygen heteroaromatic compounds.

Currently, research is focused on the determination of aza-arenes using an acidic extraction, HPLC clean-up, and GC analysis with a nitrogen specific

detector. Preliminary analyses indicate that the major aza-arenes are quinoline, isoquinoline, and alkyl homologs of these compounds.

S. L. Bowie, R. M. Campbell, S. N. Chesler, W. F. Cuthrell, F. R. Guenther,

L. R. Hilpert, W. E. May, S. A. Wise

4. Methods for the Analysis of Polynuclear Aromatic Hydrocarbons (PAH),

Amino-PAH, and Phenols in Alternate Fuels and Effluents

Energy demand in the U. S. has intensified efforts to develop alternate

energy sources such as coal, oil shale, and tar sands. Contamination of the

large amounts of water used in the mining and refining operations for some of

these processes results in a significant environmental threat. It is, therefore, important that the aqueous effluents be monitored for their toxic

organic compound content. Research sponsored by the Department of Energy has

continued during FY 1981 on the development of accurate gas chromatographic/

mass spectrometric (GC/MS) and high-performance liquid chromatographic (HPLC)

methods for the quantitative determination of toxic organic compounds in

alternate fuels and effluents. The complexity of these sample matrices

requires that the methods be highly specific, and the relatively low concen- trations (ppm to ppb) of the analytes demand high sensitivity for accurate

quantitation.

Coal gasification, oil shale retorting, and petroleum refinery aqueous

effluents were analyzed for phenolic and PAH species. A simple organic

extraction was developed to isolate the analytes prior to quantitative determinations by selected ion monitoring GC/MS. Pyrene-d 10 was used as the

internal standard for the PAH determinations and 2-chlorophenol was used for

the phenols. Two aliquots of the effluents were extracted with methylene

chloride, one at a neutral pH for the PAH and one after acidifying with

sulfuric acid to pH 1-2 for the phenols. Aliquots of the concentrated

extracts were chromatographed on high-resolution wall-coated open tubular

capillary columns. The PAH were separated on a nonpolar 30 m x 0.25 mm SE-30

coated column, the phenols on a polar 20 m x 0.25 mm Pluronics PL-64 column.

Selected ion monitoring of characteristic, intense ion(s) in the mass spectrum

of each analyte was used to enhance the selectivity and sensitivity of

detection. Since no time is wasted scanning portions of the spectrum in

which there are either (a) no ions, or (b) ions of low intensity, sensitivity

is increased by recording intense ions at characteristic masses and integrating the ion currents. To ensure that the mass spectrometer is measuring the

signal at the top of the mass peaks, the ions are monitored in 0.1 amu increments (e.g., for the benzopyrenes, with a nominal molecular weight of

122
252, ions at m/z 252.0, 252.1, 252.2, and 252.3 are monitored with a dwell

time of 100 ms for each ion). The integrated ion currents are plotted versus chromatographic retention time (see figure 20). The single ion records show

chromatographic resolution of the analytes from non-analyte components in the

sample extract which also yield ions at m/z 252. The individual analyte

concentrations are then determined from the analyte and internal standard

peak areas and experimentally determined relative response factors. Five PAH

and six phenols were determined in aqueous effluents from coal gasification,

oil refinery, and oil shale processes. The results of these determinations

are shown in Tables 14 and 15. Values represent an average of two determinations. The individual determinations differed by 10 percent or less.

Table 14. Polynuclear Aromatic Hydrocarbons in Effluents.

Analyte Concentration (ppb)

Sample Fluoranthene Pyrene Benzo[e]pyrene Benzo[a]pyrene Perylene

CG-04 11.6 11.0 0.92 1.6 0.5

CG-06 303 281 30 58 18

OR-21 <1.0 <1.0 <1.0 <1.0 <1.0

OS-43 <1.0 <1.0 <1.0 <1.0 <1.0

Notes: CG = coal gasification effluent

OR = oil refinery effluent

OS = oil shale effluent

Table 15. Phenols in Effluents.

Analyte Concentration (ppb)

Sample Phenol 2,6-DMP ;>,4- and 2,5-DMP o-Cresol m-Cresol p-Cresol

CG-04 1040 27 190 300 16 27

CG-06 730 290 890 490 330 250

OS-42 <10 <10 <10 <10 <10 <10

OS-43 <10 <10 ND <10 ND ND

0R-21 <10 <10 <10 <10 <10 <10

OR-23 <10 <10 ND <10 ND ND

0R-25 <10 <10 <10 <10 ND ND

Notes: DMP = dimethyl phenol

CG = coal gasification effluent

OR = oil refinery effluent

OS = oil shale effluent

ND = not detected

Several amino-PAH have been determined in an SRC II coal liquid and a Wilmington crude oil sample. 1 -Aminonaphthalene and 2-ami noanthracene were

determined in the samples using a sequential HPLC procedure. The analytes

were isolated from the oil matrices by chromatography on an aminosilane

column using ^45-60 percent methylene chloride-in-hexane as the mobile phase.

The analytes were then further separated from other interferences by

123
Figure 20. Selected ion chromatogram GC/MS analysis of PAH in coal

gasification effluent.

124
chromatography on a C-18 column with 40 percent acetonitrile in water as the

mobile phase. Detection was done spectrofluorimetrically with the excitation

and emission wavelengths optimized for each compound. The results of initial

analyses are shown in Table 16.

Table 16. Amino-PAH in Fuel Samples (ppm).

Analyte Wilmington Crude SRC II Coal Liquid

' i nonaphthalene 8 140

2-A loanthracene 0.3 13

K. Hilpert, W. E. May, K. L. Richie, W. J. Sonnefeld

5. Methodology for Certification of a Polychlorinated Biphenyl (PCB) in

oil SR"

Polychlorinated biphenyl (PCB) mixtures have been used extensively in

th'. country in high-voltage electrical components. These toxic compounds

ma> be introduced into the environment when the electrical components in

which they are contained are repaired or discarded. PCB-containing fluids

physically resemble lubricating oil, and there have been instances in

which toxic PCB's have been mistakenly added to oils being collected for

recycling purposes. Thus, a PCB SRM will find use in the electrical

industry where PCB contamination of transformer cooling fluid is of current

concern, and in the motor oil recycling (re-refining) industry where

inadvertent contamination by PCB-containing fluids is a potential problem.

A Standard Reference Material entitled "Polychlorinated Biphenyls in

Oil" (SRM 1581) has been prepared consisting of separate solutions of

Aroclor 1242 and Aroclor 1260 (commercial polychlorinated biphenyl mixtures)

in a transformer oil and a motor oil base at the 100 ppm (wt./wt.) level.

Two independent analytical methods are being used for the certification

measurements. First, quantitative data were obtained from the gravimetric

preparation of these solutions. Secondly, a hybrid chromatographic technique developed in our laboratory is utilized that involves both gas

chromatography and high-performance liquid chromatography (HPLC). HPLC is

used first to remove the major interfering components in the oil sample

(see figure 21). The "clean" sample is then separated into its component

parts using a nonpolar wall -coated open-tubular gas chromatographic column

and selective electron capture detection (see figure 22). Quantitative

data are obtained by relating peak areas of three internal standards (PCB

isomers are used which are not detected in the Aroclor of interest) to the areas of the PCB peaks of samples and of calibration standards.

In addition to the certification of total PCB content, concentrations

of selected PCB isomers in each of the Aroclor solutions will be measured,

as well as total chlorine content by neutron activation analysis

(R. Fleming, Division 551).

S. N. Chesler, F. R. Guenther, W. E. May, R. M. Parris

125
uv

Absorption

i i rracuon

Collected

LC

FRACTIONATION

Oil Sample

Aroclor 1254

Standard

i

0 5 10 15

Time, minutes

Figure 21. Preparative scale HPLC fractionation of a motor oil sample.

126
spuepueis LBUJiaiui

Figure

22.

High

resolution

gas

chromatogram

(electron

capture

detection)

of

the

PCB-containing

fraction

of

"Motor

Oil

Base

and

Aroclor

1260".
6. Identification of Polychlorinated Biphenyl (PCB) Isomers Using Combined

Gas Chromatography/Fourier Transform Infrared (GC/FT-IR) Spectroscopy

During the past year, 42 pure PCB isomers were procured and their gasphase IR spectra obtained and assembled into a computer data base. Table 17

lists the available spectra by isomer groups. Emphasis has been placed on the tetra- and penta-i somers , due to their abundance in Aroclors 1242 and

1248, some of the most common PCB mixtures encountered in environmental

analyses.

All work to date has been on Aroclors 1242, 1248, and 1260. Concentrated solutions of these Aroclors (0.1 percent in methylene chloride) were

run on a 30-meter fused silica capillary column, coated with a nonpolar

bounded liquid phase (DB-5) to a thickness of 1 ym. The effluent from this

column was then run directly into a special low-volume 2 mm x 42 cm goldplated light pipe (approximately 1.5 cm 3 volume). Injections were made

splitless utilizing the solvent effect reported by Grob [1].

A Gran-Schmidt [2] reconstructed chromatogram is shown in figure 23.

This represents a "total wavelength" response of the FT-IR to the GC

effluent. Examination of the spectra indicated that very few of the peaks were single isomers. However, the peak at data point 153 was identified

as 2,4' ,5-trichlorobiphenyl

.

Work is continuing with regard to (1) increasing GC resolution to

simplify the IR spectra, (2) obtaining more pure-isomer spectra, (3) deconvoluting multicomponent peaks utilizing library spectra of known components

in the peak, and (4) using HPLC fractionation of the Aroclors to reduce

chromatographic complexity. Developing these procedures on the complex

Aroclor isomer mixtures will provide an excellent model for generic development of GC/FT-IR spectroscopy in analytical chemistry.

Table 17. Available PCB Isomers.

Chlorines Possible Isomers In Library

1 3 1

2 12

3 24 7

4 42 16

5 46 12

6 42 4

7 24 2

8 12

9 3

10 1 209 42

128
IR

SPECTRUM

153

NU3S/S11DA '1UN3IS yDlOdidO

129

50

100

150

200

250

300

350

ATA

POINTS

Figure

23.

Gran-Schmidt

reconstruction

of

Aroclor

1242

from

a

30

meter,

DB-5

capillary

column.

IR

spectrum

153

was

found

to

match

the

library

spectrum

of

2

,4

'

5-trichl

orobiophenyl

.
References

[1] Grob, K. ; Grob, K. , Jr. J. Chrom. Sci. 8: 53; 1974.

[2] Hanna, D. A.; Hangac, G. ; Hohne, B. A.; Small, G. W. ; Wieboldt,

R. C.; Isenhow, T. L. J. Chrom. Sci. 17: 423; 1979.

F. R. Guenther, R. M. Parris

7. Chemically Modified Electrode Detector for Halogenated Hydrocarbons

Halogenated hydrocarbons, such as polychlorinated biphenyls, organochlorine pesticides, and organohalogenated industrial solvents, constitute

one of the major classes of hazardous wastes contaminating the environment

and comprise a fair portion of the EPA Priority Pollutant List. Most of

these types of compounds are presently determined by gas chromatography

following solvent extraction to separate and concentrate the analyte. An

analytical method is needed which can be applied directly to the sample

matrix without the necessity of a pre-separation/concentration step and which

also is amenable to field use for on-site analysis.

We are interested in the development of chemically modified electrodes,

which will electrocatalytical ly detect organohalide compounds. These chemically modified electrode sensors could allow the selective and sensitive

detection of organohalide compounds in the presence of complex matrix interferences. Chemically modified electrodes were fabricated by electrodeposition

of a polyphenylene oxide polymer film on Pt or Au substrates. The polymer

molecules contain functional groups which are derivatized chemically [see

Schemes 1(A) and 1(B)].

In Scheme I, the solution Ni (II) L/Ni ( I ) L redox couple has been shown to

be electrochemical ly and chemically reversible. The Ni ( I ) complex forms an adduct with the R-X species, if present, and subsequent transfer of an electron to the R-X moiety regenerates the Ni (II) complex. The reduction of

R-X to X" and R* proceeds rapidly and catalytical ly , at -1 to -1.5 volts vs. S.C.E. as opposed to -2.3 volts for the direct reduction of R-X.

130
Scheme I:

(d) R-X + Ni'l a

» m

ml + r- + x~

The synthesis of unsymmetrical Schiff-base ligands starts with the

synthesis of 1.

ch2 - ch2 -ch2

1

ligand

polymer

131
This molecule is formed by the 1:1 molar condensation of sal icyl aldehyde

with 1 ,3-diaminopropane. The final synthetic step involves condensation

of meta-substituted sal icyl aldehyde with a nickel complex:

Future work involves (1) further film characterization via surface

analysis (ESCA, Raman), (2) electrochemical evaluation of these derivatized

polymer films, (3) evaluation of the stability associated with these

polymer films, and (4) the electrocatalytic efficiency as a function of

film thickness and chemical composition.

A potential spin-off of this research is the use of these chemically

modified electrodes for the electrosynthesis of useful products from waste

materials. Such a recycling process would follow the scheme:

r-C 1 + e

" —CME

- Cl" + R. —— R-R.

In other words, dimerization of the hydrocarbon radicals would result in

dehalogenated organic compounds possibly of lower toxicity or perhaps

commercial value.

E. A. Blubaugh

132
8. Electrochemical Oxidation of Croconate Salts and Their Implication in

Semiconductor Behavior and Electrochromic Displays

As part of the competence building program in electrochemistry, we have

been investigating several aromatic compounds based on dicyanomethylene

derivatives of croconates (pseudo-oxocarbons r of general 3 formula C 0 [C ( CN ) p ] ). n m

/ZJ n-m These compounds are intense chromophores and exhibit appreciable electrical

conductivity, hence they are ideally suited as models for research in spectroelectrochemistry. From the results of the nonaqueous solution electrochemistry

and crystallographic analysis, a mechanism for the electrical conductivity of

crystalline potassium croconate violet has been proposed. In addition, it was shown that the intense coloration of croconate solutions can be reversibly

altered by electrochemical means.

The solution electrochemistry in N,N-dimethylformamide ( DMF ) of four

croconate dianions indicates that two reversible one-electron transfers occur

(figure 24). The first oxidation process is a one-electron abstraction from

the dianion to form a stable radical anion followed by a second one-electron

oxidation of the radical anion to the neutral molecule. The first oxidation

process causes nearly complete extinction of the croconate coloration (see

figure 25). The color is completely restored upon reversal of the electrode

potential to its rest potential. Although the reaction is relatively slow

(compared to a liquid crystal display), the fact that the color is at its

full intensity at rest potential means that no power is consumed to produce

the color. This result would be of great value for displays that are ordinarily "lit" and only have to be extinguished momentarily.

In considering electron conduction in crystalline organic materials, it

is clear that chemical changes during electron conduction could severely

alter the conduction process. Although the solution electrochemistry of

potassium croconate violet indicates the dicyanomethylene groups are electrochemically active, it is apparent that electron transfer must be initiated

and terminated at the alkene bond, since this is the only redox process that

leaves the molecule structurally unaltered. However, because of the stacking

arrangement, electron migration, illustrated in figure 26, most likely occurs between a dicyanomethylene group and the alkene bond of adjacent unit cells

and between dicyanomethylene groups within the unit cell. Electron conduction

can be rationalized in the dicyanomethylene group by invoking either a concerted electron transfer or delocalization of the unpaired electron by

resonance (resonance forms are depicted in figure 26), each process leaving

the dicyanomethylene group intact. The result is the dicyanomethylene group

becomes the conduction arm of the molecule while the alkene bond undergoes

oxidation/reduction.

L. M. Doane, A. J. Fatiadi

133
2 -

Figure 24. Cyclic voltammetry in 0.5 mol/L TEAP - DMF at

0.05 V/s of croconate (1), croconate orange (2),

croconate violet (3), and croconate blue (4).

134
135

400

500

600

700

Wavelength

(nm)

Figure

25.

Absorption

spectra

of

croconate

violet

for

potentials

of

the

first

oxidation

process

ranging

from

(1)

fully

oxidized

to

(12)

fully

reduced.
b) c)

Figure 26. Views of three stacked croconate violet dianions showing proposed:

(a) initial electron abstraction and intermolecular electron

conduction between dicyanomethylene groups, (b) intermolecular

electron conduction between the alkene carbon atom and the

dicyanomethylene group (shown as resonance form here), and

(c) intramolecular electron conduction between the alkene carbon

atom and dicyanomethylene group.

9. A Multipurpose Cell for Nonaqueous Electrochemistry

Because the electrochemistry of many compounds involves radicals or water-sensitive moieties, the use of nonaqueous solvents is becoming

increasingly popular. However, a not-so-trivial problem is obtaining

solvents that are free of oxygen and water. Vacuum distillation and/or

application of molecular sieves is generally sufficient to rid the solvent

of water and organic impurities. Commonly, several vacuum freeze-pumpthaw cycles are employed to purge the solvent of oxygen. However, if the

electrochemical experiment is not maintained under an inert atmosphere,

such rigorous purification procedures are easily defeated.

We have designed and constructed a vacuum electrochemical system that

easily maintains an oxygen- and water-free environment. The system

employs an electrochemical cell usable in all types of electrochemical

experiments (except polarography) and in some new applications, e.g.,

thin-layer electrochemistry and spectroelectrochemistry. The vacuum cell

functions equally well in either of two configurations, i.e., as a spectroscopic cell in experiments employing an optically transparent thin-layer

electrode (OTTLE) (figure 27A) and as an electrochemical cell in voltammetric experiments (figure 27B). The cell (in either configuration)

136
Figure 27A. Vacuum electrochemical cell: spectroelectrochemical

apparatus. The asterisk indicates an 0-ring.
Figure 27B. Vacuum electrochemical cell: bulk electrochemical

apparatus. The asterisk indicates an 0-ring.
consists of two parts: (1) the main U-shaped cell, which contains the

solution and provides support for the electrodes and optical windows, and

(2) the inlet adapter, which in part forms an isolated auxiliary electrode

compartment and a port for solution introduction. Approximately 2 mL of

solution are required to adequately fill the cell for an experiment.

Since the system is closed and under an inert atmosphere, the need

for continuous purging is eliminated and cell transportation is facile,

especially for laboratories where the solution preparation facilities are remote from the instruments. In addition, the lack of continuous purging

removes the possibility of trace impurities in the purging gas accumulating in the solution.

Although the joints are standard taper, 0-rings are utilized between

several joints to effect greaseless vacuum seals which will not seize.

With some joints, a groove is ground in the inner joint to accomodate the

0-ring; with other joints, a joint gasket assembly is employed as depicted

in figure 27.

The many uses of the cell are accomplished with a versatile cell cap.

The cell cap provides support for the working and reference electrodes and

is rapidly and easily converted to the appropriate configuration of the

experiment. A variety of working electrodes utilizing gold, platinum,

silver, and pyrolytic carbon have been constructed to easily mount in the

cell cap (see figure 27B).

This cell has been used successfully in both configurations in the

electrochemistry of several organic and inorganic compounds dissolved in

N,N-dimethylformamide and propylene carbonate; we have characterized the

electrochemistry of several oxocarbon salts and demonstrated their reversible

electrochromic behavior.

E. A. Blubaugh, L. M. Doane

139
10. Chronoamperometry at Unshielded and Collarless Disk Electrodes

In order to better understand the redox processes occurring at solid

electrodes and apply them in electrochemical investigations, theories and

models have been developed to describe the chronoamperometric diffusion

processes. The diffusion coefficient D of electroactive compounds can be

accurately determined from chronoamperometry using shielded disk electrodes

to conform to the conditions of one-dimensional diffusion. For unshielded

electrodes, the simple Cottrell equation no longer applies, and suggestions

have been made to correct this by taking into consideration the edge effect,

i.e., lateral diffusion. Recently, two groups have published results of

numerical simulation for unshielded electrodes [1,2]. We have tried to apply

these to the chronoamperometric data we obtained for K 3 Fe(CN) 6

.

The conventional procedure is to plot i/t versus /t, where i denotes

current and t denotes time. Our data and the two least squares regression

calculations suggested by Heinze [1] and Lingane [3] are illustrated in

figure 28: (a) the dashed line results from use of a linear equation suggested

by Lingane [3], and (b) the solid line results from the use of the simulation

results of Heinze [1]. In (a), D was determined from the intercept of the

straight line on the ordinate axis at t = 0, while in (b) D was determined

from a nonlinear regression analysis.

Alternatively, i is shown as a function of l//t in figure 29. The

dashed curve is a least square polynomial fit to the experimental points. D can be estimated from the extrapolated value of i as time approaches infinity,

i.e., l//t = 0. The solid straight line is drawn through the points (x l5 i

3 ) and (x 2 , i 2 ), as suggested by Sato et al. [2], where Xx = (3//t 2 + l/v^i)/4

and x 2 = (3/Ztx + l//t 2 )/4; and the range of time where data are used is

ti < t < t 2 . Then from the slope and the intercept of this line at l//t = 0,

D is determined by an iterative procedure based on the numerical simulation

results of Sato et al. [2].

The values of D as determined by the various procedures are summarized

in Table 18.

Table 18. Diffusion Coefficient Determined by Various Procedures.

Procedure D x 10 6 cm2 /s

a) i/t vs /t, 1 inear

b) i/t vs /t, using Heinze's results

c) i vs l//t, extrapolate to l//t = 0

d) i vs l//t, using Sato's results

7.68

7.88

7.8

7.54

140
50

+ /

+

+ /

+ /

/

/

/

/

/

/

i l J I I L J L

t

1/2

, (sec)

1/2

Figure 28. Plot of i/t vs. /t.

The estimated percent deviation of each value is about ±5 percent and

the values determined by the various procedures agree with each other

within this limit of estimated deviation. The accepted value, reported by von Stackelberg et al. [4] is D = 7.79 x 10' 6 cm2 /s. Procedures (a), (b),

and (d) allow one to use the data at the middle range of current-time

curves, thus avoiding the artifacts at an early time due to the electronics

but also introducing some degree of arbitrariness in choosing the range.

141
T
Procedure (d) has appeal in that the two variables, i and t, are separate

and their errors are not mixed as in the case of i/t, but this plot seems

to be less sensitive as a diagnostic in our series of experiments as compared to the i/t vs /t plot.

Several articles have appeared recently, aimed at describing the currenttime behavior in chronoamperometry employing unshielded disk electrodes,

using both numerical simulation and analytical approximation. We have been

developing a theory for chronoamperometry that is applicable to cylindrical

rod electrodes insulated with a thin coating on the side, disk electrodes

with a tapered collar, and several other electrode constructions which are easily fabricated. Solving the diffusion equation with the condition that

the potential step is such that the concentration, C, of one of the species

is zero on the disk, the current, i , as a function of time, t, is given by:

x(t) = /rtf o fJ

-tz 2 sin z Jt (z) dz +

r°° erf(/tz") sin z Ji (z)

_ 9 O'* dz

where

*i tt A X

= is the dimensionless current, and

x = is the dimensionless time;

a

a is the radius of the disk and D the diffusion coefficient.

__ As t -> o (small t or large a), the first integral dominates and x("0

5—, which is the Cottrell equation. On the other hand, as t -> °°, the

4

/t

second integral dominates and x(^) + which is the behavior of the spherical electrode, as one would expect. The two integrals were evaluated by a series expansion of the Bessel function J i

( z ) . The asymptotic expansion

in fractional power of t at small t are still being investigated.

References

[1] Heinze, J. Ber. Bunsenses Phys. Chem. 77: 1051-1055; 1973.

[2] Kakihana, M. ; Ikenchi, H.; Sato, 0. P.; Tokuda, K. J. Electroanal.

Chem. 117: 201-211; 1981.

[3] Lingane, P. J. Anal. Chem. 36: 1723-1726; 1964.

[4] von Stackelberg, M.; Pilgram, M. ; Toome, V. Z. Electrochem. 57:

342-350; 1953.

L. M. Doane, W. T. Yap

143
1 1 . Spectroelectrochemical Research: Surface-Enhanced Raman Spectroscopy of

Pyridine Derivatives

Surface-enhanced Raman spectroscopy (SERS) is a recently discovered

phenomenon which gives highly resolved spectral data of some molecular

adsorbates. SERS is a currently unexplained phenomenon which produces a 10 6 enhancement of the Raman spectra of molecules adsorbed on metals such as silver and gold. Some of the theories which have been proposed involve

coupling into surface plasmons via atomic, molecular, or large-scale surface

roughness as well as field and image enhancement due to surface roughness.

The experimental apparatus can range from simple to elaborate. A simple

system consists of general purpose Raman equipment--an argon ion laser, a double grating monochromator with a photomultiplier and photon-counting

electronics with microcomputer-controlled data acquisition, storage, and

display. A more elaborate system which could be used to monitor a broader

range of compounds and surface reactions would consist of a tunable dye laser

and multichannel detection. Several electrochemical cells have been designed

consisting of a working electrode, counter electrode, reference electrode,

and a port for deaerating the solution. A thin-layer cell has been designed

to minimize the interference of solution spectra and to facilitate equilibrium

of the redox reactions.

The enhancement of the spectra of surface species makes SERS an ideally

suited technique for studying molecule-electrode interactions in situ.

This technique has been successfully applied to studies of a number of pyridine

derivatives (carboxaldehydes , methyl ketones , and carbinols) and the effects of

adsorbate-substrate interactions have been identified. The 4-substituted

carboxaldehydes and methyl ketones exhibit weaker carbonyl stretching bands

when adsorbed on silver than in solution, while no such effect is found for

the corresponding 3-substituted compounds. This is consistent with an interaction of the nitrogen lone-pair electrons with the silver, leading to electron

withdrawal from 4-substituents and increased hydration of carbonyl groups at

that position. Examination of several N-methylpyridinium salts shows a similar trend, with N-methylation increasing the degree of hydration and

reducing the carbonyl band intensity in 4-pyridinecarboxaldehyde but not in

3-pyridinecarboxaldehyde. The effect of adsorption is more dramatic, however,

since the SERS spectrum of 4-pyridinecarboxaldehyde is identical to that of

the corresponding carbinol, indicating that the aldehyde is completely

hydrated on the electrode. Thus, SERS allows us to identify the surface

species and to show that it is quite different from that found in bulk solution.

This result could not have been anticipated on the basis of cyclic voltammetry

since no electrochemical reaction is required to produce the surface species.

Another study which has important implications on the surface metal

interface uses N-methylpyridinium ions which only show surface enhancement

when iodide is in the solution. No enchancement is observed with only

chloride in solution and the effect of perchlorate is currently being

investigated. These studies are important because the N-methylpyridinium

ion has no nitrogen lone-pair electrons for bonding and is, in fact, an organic cation. These types of molecules have received little attention in

SERS studies.

144
Many biomolecules undergo very slow heterogeneous electron transfer.

This behavior is attributable to adsorption of the biocomponent on the electrode surface and/or isolation of the electroactive center by the protein

matrix. This problem can be circumvented by addition of another species to

the solution, a mediator-titrant , which transports electrons between the

electrode and biocomponent. 4,4' -Bipyridine has been found to mediate

electron transfer between cytochrome C and gold electrodes. Some workers have

proposed that it mediates only when it is in a particular orientation with

respect to the electrode surface. Preliminary results have indicated that

this is not true on silver. SERS should be able to provide other valuable

information on the interaction not only between the electrode surface and the

mediator, but also the mediator and the protein.

It is anticipated that SERS will prove to be extremely useful in studying

the surface characteristics of electrodes modified by the attachment of

polymers and other electrocatalytic moieties. These polymer-modified electrodes are currently being investigated in our group to determine their

properties and analytical potential.

K. A. Bunding, R. A. Durst

12. Measurements of the Optical Rotatory Dispersion of Internationally

Exchanged Quartz Control Plates and Long Quartz Rotators Between 400

and 650 nm

Quartz control plates and rotators are used by national laboratories to

assure comparability of measurements on their reference polarimeters . Several

plates and rotators were exchanged between NBS and the Physikal isch-Technische

Bundesanstal t (PTB) prior to determining a revised international value for the

100 °S point of sugar, a value that determines the market value of sugar. The

developing use of lasers as light sources in polarimetric measurements also

necessitated a study of the dependence of the optical rotation of these

rotators at laser wavelengths before they be adopted as new polarimetric

standard wavelengths.

Therefore, the optical rotatory dispersion of two long quartz rotators

(^15 mm long, supplied by PTB) and an NBS quartz control plate (M.5 mm in

length) have been measured in the NBS high precision polarimeter at nine

wavelengths between 400 and 650 nm using a Hg lamp and stabilized He-Cd, Ar,

and He-Ne gas lasers. The rotation values along with their corresponding

wavelengths were fitted to a four-parameter equation to calculate the

following constants: —— = -0.03955458 + 0.3673044985 (A-0. 07359803)

a6 3 3

where a

^ = optical rotation at wavelength A

ag 3

3

= optical rotation at 632.9914 nm (He-Ne laser source)

A = wavelength in pm

145
Comparison of these data with Blinnagel's earlier measurements (1966) using

lamp sources at the PTB on a 50 mm quartz rotator indicate that all four

rotators, though of different origin, have a common rotatory dispersion (see

Table 19). The fit of all four data sets to the Mandel four-parameter equation

is excellent with reproduction of a^/a633 to within 0.00002. This equation

replaces the currently used seven-parameter equation derived from the fit of

the single data set of Bunnagel. Hence, we have a firm corroborated formula

by which optical rotation measurements at 633 nm performed with a stable,

reproducible, inexpensive He-Ne laser source can be converted to corresponding

optical rotator values at the 546 and 589 nm reference wavelengths for

saccharimeters. Since certification at these wavelengths is a necessary part

of our calibration service, measurement at this single wavelength has

significantly shortened the time required for quartz plate calibrations by

25 percent. With user-submitted quartz control plates numbering over 70

during the last four years, the time savings is significant. The formula also

provides a means by which the center of gravity wavelength of a spectral line can be determined to within a few ppm by measurement of its rotation by quartz

rotators.

Table 19. Relative Optical Rotations of Internationally Exchanged Rotators

Measured with Laser Sources.

15 mm Rotator

PTB #2

15 mm Rotator

PTB #3

1 . 5 mm

Rotator

NBS #1724

50 mm Rotator

Bunnagel Data

Interpolated

to our A a

A a

A aA a

A Source X, nm a

632. 9914

a

632. 9914 a632.9914 * a

632.9914

He-Cd 441.689 2.16015 2.16014 2.16023 2.16018

Ar 458.0630 1.99527 1.99525 1.99521 1.99523

Ar 476.6194 1.83055 1.83055 1.83050 1.83050

Ar 488.1225 1 . 73860 1.73861 1.73862 1.73858

Ar 496.6462 1.67495 1.67497 1.67494 1.67493

Ar 501.8559 1.63778 1.63777 1.63773 1.63775

Ar 514.6742 1.55148 1.55147 1.55143 1.55146

Hg Lamp 546.2271 1.36627 1.36629 1.36626 1.36628

He-Ne 632.9914 1.00000 1.00000 1.00000 1.00001

A. C. Cummings, D. K. Hancock, J. Mandel

146
13. Nitrogen-15 NMR Spectroscopy of Neomycin B at High Field

The aminoglycoside class of antibiotics form a group of drugs that are of

interest as possible future SRM's. Natural -abundance nitrogen-15 and 400 MHz

proton NMR studies performed recently at the high-field NMR facility of the

National Measurement Laboratory have demonstrated the usefulness of nitrogen

and proton NMR parameters for the structural, conformational, and quantitative

analysis of complex aminoglycoside molecules.

More than thirty years of considerable effort devoted to the isolation

and characterization of components of the commonly prescribed "neomycin

complex" has led to the elucidation of the structures of isomeric neomycins B and C in total stereochemical detail [1]. Despite this effort, however, the

complete solution conformation of neomycin B (Structure 1) has not been

defined with certainty. Results have been obtained, which, for the first

time, describe conclusively conformational forms of individual sugar residues

in Structure 1, and also illustrate the use of 15N NMR for detection of

impurities in commercial samples of antibiotics.

Nitrogen-15 chemical shifts of four derivatives of neomycin B are presented in Table 20 for comparison with the 15 N shift data of structurally

related pseudo- and mono-saccharides shown in Table 21. Assignments of the

resonances in the spectrum of the hexahydrochloride lg are based on the

15 N shifts of hydrochloride salts of the components £-Z, except for the

specific assignments of N-l and N-3 which have been made on the basis of spinlabeling experiments. Similar chemical shift comparisons were used to classify

nitrogens in the sulfate derivative 1§, the free base lb, and the hexa-Nacetyl derivative Id according to their structural type. Specific assignments

of individual nitrogens in la and lb were based on data obtained from 15 N chemical shift titration curves.

Complete 15 N chemical shift titration data for neomycin B are shown in

figure 30. The complex behavior of the 15 N shifts with changes in pH is

apparent, especially at intermediate .pH values, where problems with peak over- lapping and relative order of resonances are most severe. Once resonance

assignments have been confirmed at the low pH extremes by comparing 15 N shifts of a sample of neomycin B hexahydrochloride (lg), the construction of

smooth sigmoid curves through the points for individual nitrogens facilitates

their assignment over the entire pH range. Chemical shift values extracted

from the curves at pH 6.7 (indicated by the arrow) are within ±0.1 ppm of

those determined for a solution of the sulfate 1§ at the same pH. It is seen that protonation of the free base lb leads to downfield shifts ranging from

6.8 to 14.2 ppm. It is also apparent from the titration curves that all of

the amino groups in the antibiotic are essentially fully protonated at pH <4.5,

and fully unprotonated at pH >10.5. The pK_ values for individual nitrogens

a shown in Table 22 were calculated from the titration curves.

147
o

1

In general, the 15 N shifts of the N-acetyl ated compounds studied are 99.0-103.4 ppm downfield of the corresponding shifts of their free bases.

The close correspondence of 15 N shifts for nitrogens of a specific structural type in compounds which differ widely in their complexity, i.e., number

of sugar units, indicates that substituents removed from the local environment

(more remote than the y-position) of the nitrogens have little influence on their chemical shifts. The small variations observed, however, may result

from changes in solvation at the nitrogen sites with increasing complexity of

the aminoglycoside. The substituent effect parameters derived for the aminoglycosides studied have been found to be in excellent agreement with those

derived for simple aliphatic amino compounds [2]. Empirical methods have been

developed to calculate nitrogen chemical shifts for aminoglycosides by using

the substituent parameters.

148
Table 20. Nitrogen-15 Chemical Shifts of Neomycin B Derivatives in H2 0.

Chemical Shift9

Derivative N-l N-3 N-2' N-6

N-2' 'N-6"

Sulfate*

3 (la) -340.4 -338.6 -343.4 -350.0 -347.8 -349.6

Free Base QbJ -343.5 -345.8 -353.9 -361.8 -360.7 -359.8

Hexahydrochloride (lg) -336.3 -337.9 -342.1 -349.3 -346.5 -348.9

Hexa-N^-acetyl (Id) -244.5 -246.3 -253.4 -259.8 -257.3 -257.7

a

In ppm upfield from an values denote upfield

external

shifts.

capillary of 1M NH 4 15 N0 3 in H 2 0; negative

bpH = 6.7 of commercial preparation purchased from Sigma Chemical Co.

Based on the substituent effect parameters, N-2 1 " shifts calculated for

L-idopyranosides in the 4

C_! conformation (Structure 2a) should be similar to

those for 2-amino groups in D-glucopyranosides , but, in fact, the experimental

values are consistently 4-6 ppm to higher field. Furthermore, earlier studies

[3] have shown that the 15 N shifts of a-Q-mannosamine derivatives, the

structures of which are analogous to Structure 2b > are upfield of their

respective a-D- gluco derivatives by similar increments to those found here.

The data suggest that L-idopyranosyl residues in l§-d adopt the 4

C_

X conformation (2b) in solution. Proton NMR studies confirm this conclusion.

The 15 N chemical shift titration curves afford a method for the simultaneous measurement of the pK

g values of all nitrogens in the molecule that is

far superior to conventional acid-base titrations. This is of general interest

for the analytical characterization of other classes of nitrogen-containing

materials.

149
Table 21. Nitrogen-15 Chemical Shifts of the Neomycin B Family of Ami nosaccharides.

Compound Chemical Shift9

Derivative N-l N-3 N-2 ' N-6 1 N-2'" N-6 '

1

Neamine

Free Base (2a) -343.7 -345.2 -353.8 -361.1

TetrahydrochToride (2b) -336.9 -338.0 -342.2 -349.8

Tetra-N-acetyl (2g) -244.3 -246.1 -253.1 -260.2

Methylneobiosiminide

Free Base (3a)

Di hydrochloride (3b)

Di-N-acetyl (30

2-Deoxystreptami ne Free Base (4a) -344.9 -344.9

Dihydrochlonde (4b) -337.7 -337.7

Di hydrobromide (4 q] -337.6 -337.6

Di-N-acetyl (4d) -245.7 -245.7

2 , 6-Di ami no-2, 6-di deox.ygl ucose

Di hydrochloride (5a) a -342.2 -349.3

(a: 8 = 71:29) 8 -343.9 -349.1

Free Base (5b) a -352.6 -361.2

(a: 8

= 75:25] 8 -353.3 -361.5

2-Ami no-2-deoxygl ucose Hydrochloride (£a) a -341.7

8 -343.2

N-Acetyl (§b) a -253.6

8 -254.4

6-Ami no-6-deoxygl ucose Hydrochloride (Za) a:

8:a:

8:

-349.6

N-Acetyl (Zb) -258.6

-359.8 -359.6

-346.4 -349.3

-256.7 -257.6

i

a In ppm upfield from an external capillary of 1M NH4 15 N0 3 in H 2 0; negative values

denote upfield shifts.

Table 22. pK Values of Individual Nitrogens in Neomycin B. a

N-l

a N-3

a N-2' N-6' N-2"' N-6"'

8.08 ± 0.01 5.58 ± 0.05 7.49 ± 0.01 8.61 ± 0.04 7.58 ± 0.01 8.83 ± 0.01

a Assignments based on spin-labeling experiments.

150
360 H

151

Figure

30.

Nitrogen-15

chemical

-shift

titration

curves

for

Neomycin
References

[1] For a general review, see: Rinehart, K. L. The Neomycin and

Related Antibiotics. New York, NY: John Wiley and Sons, Inc.; 1964.

[2] Duthaler, R. 0.; Roberts, J. D. J. Am. Chem. Soc. 100: 3889; 1978.

[3] Botto, R. E.; Roberts, J. D. J. Org. Chem. 42: 2247; 1977.

Coxon, B. Pure and Applied Chem. 49: 1151; 1977.

R. E. Botto, B. Coxon

14. Nitrogen-15 NMR and Mass Spectral Characterization of Doubly 15 N-Labeled

2-Amino Oxazoline Derivatives of the Pentoses and Hexoses

The synthesis, characterization, analysis, and testing of anti-tumor

nucleosides is an important facet of present-day cancer research. Because

2-amino oxazoline derivatives of carbohydrates can be used to prepare potential

anti-tumor nucleosides (and nucleotides) in a single step, via three-carbon

annul at ion reactions with various electrophiles, they would be very suitable

for use in the preparation of radiolabeled anti-tumor nucleosides, especially

those with isotopes possessing short half-lives. Such a class of radiopharmaceuticals based on pyrimidine cyclonucleosides is virtually unknown today

and would have great clinical utility as nondestructive in vivo diagnostic

imaging agents for use in nuclear medicine and clinical oncology. These

short-lived radionuclides ( 18 F, nC, 13 N, 15 0) all decay by positron emission,

and hence positron emission tomographic techniques (P.E.T.T. scanning) could

be applied to them. Thus, a long-term goal of this work would be to provide a useful adjunct to the already well-established technique of isotope dilution

mass spectrometry using stable isotope-labeled nucleoside anti-tumor agents in

clinical settings. Carbohydrate derivatives of the 2-amino oxazoline type

have previously been used in stereospecific syntheses of such anti -tumor

nucleosides as 1-8-D-arabinofuranosyl cytosine (Ara C).

As part of a postdoctoral research associate project, a new efficient

synthesis of doubly 15 N-labeled 2-amino oxazoline derivatives of carbohydrates

has been developed which involves treatment of either unprotected or O-isopropylidene protected glycosyl amines with cyanamide- 15

]^ in methanol to

give glycofuranosyl 2-amino oxazol ines- 15 !^. The structures and purity of

many of these derivatives in the pentose and hexose series have been analyzed

by proton, carbon-13, and nitrogen-15 NMR and by mass spectrometry. Reversedphase HPLC proved to be a valuable means for purification of these compounds.

In figure 31, a probable mechanism for the formation of 2-amino oxazolines

from glycosyl amines and cyanamide in methanol at room temperature is presented.

We postulate that the key intermediate for these labeled syntheses is an imonium ion which undergoes a transimination reaction with labeled cyanamide

and then subsequent ring closures to give either furano or pyrano 2-amino

oxazol ines- 15 !^. Precedent for the invoking of an imonium ion was provided by

the work of Frush and Isbell at NBS in 1951 [1]. These workers postulated an imonium ion intermediate in the mutarotation and hydrolysis of glycosyl amines.

152
Figure

31.

Probable

mechanism

for

formation

of

2-amino

oxazolines

from

glycosyl

amines.
The inverted catenary (bel 1 -shaped) pH versus log rate profile which they

observed for glycosylamine hydrolysis explains in part how the glycosylamines

are able to act as useful precursors of the 2-amino oxazolines. In the case

of the ribose, arabinose, and xylose 2-amino oxazoline derivatives, only

furano oxazolines were observed. However, in the case of the lyxose

derivative, a 4 to 1 mixture of pyrano and furano 2-amino oxazolines is

apparently formed, as detected by both TLC and C-18 reversed-phase HPLC.

In an attempt to prepare analytically pure samples of both lyxopyrano and

lyxofurano 2-amino oxazolines and eventually also prepare them doubly ^relabeled, stereospecific syntheses of each form were undertaken. Figures 32

and 33 depict the stereospecific syntheses which have been worked out. In figure 32, the entire scheme has been successfully applied to arabinose and

almost entirely to lyxose itself. In figure 33, the 5'-0-trityl lyxofurano

2-amino oxazoline has been isolated at about 75 percent purity.

D-arabinose

Figure 32. Stereospecific synthesis of arabinose furano

2-amino oxazoline.

In analyzing the structure and purity of one of the doubly 15 N-labeled

2-amino oxazolines, an interesting result was observed. The proton NMR

spectrum of 15 N 2 -4, 6-0-isopropyl idene-2-amino-3-L-sorbofurano[2' ,3' :4,5]2-

oxazoline at 400 MHz in three different solvents displayed variations of

vicinal 15 N coupling to H-l and H-l ' , suggesting a dependence of proton dihedral

angle on solvent.

154
D- I yxose

Figure 33. Stereospecific synthesis of lyxofurano 2-amino

oxazol ine.

These results suggest several experiments which are now being pursued.

For example, since this 15 N-labeled sorbose derivative is apparently an ideal

model system for distinguishing between intermolecular versus intramolecular

H-bonding by use of 15 N NMR, it would be of theoretical value to correlate the

temperature-dependent changes in the FT-IR of this compound in CDC1 3 or

CD2 C1 2 with the temperature-dependent changes in proton and 15 N NMR spectra at

400 MHz. Thus, an enthalpy value for an intramolecular H-bond in an aprotic

solvent could be calculated from an Arrhenius plot.

Reference

[1] Isbell, H. S.; Frush, H. L. J. Res. NBS 46: 132; 1951.

B. Coxon, R. M. Davidson, S. A. Margo! is, E. White V

15. Two-Dimensional Proton NMR Spectroscopy of Hydroxyl Proton Coupled

a- and g-D-Gl ucopyranose

Solutions of a- and B-D-glucose in dimethyl sulfoxide-d^ (DMSO-d^) are of

interest as stable systems for the quantitative analysis of Q-glucose (dextrose)

SRM's by proton and carbon-13 NMR. However, inhibition of hydroxyl proton

exchange in these solutions results in complex 12-proton spin systems that are difficult to interpret by conventional techniques. The proton NMR spectra of

155
the major and minor components of SRM Q-glucose (a-D-gl ucopyranose and

3-D-glucopyranose, respectively) in DMS0-c[6 solutions have now been analyzed

completely by application of the two-dimensional

,

1 J

' -resolved technique at

400 MHz. One great advantage of this technique is the separation of chemical

shift and coupling constant information into different dimensions, which

allows complex, overlapping proton signals to be disentangled by cross-sectioning methods, as long as there are at least slight differences in chemical

shift between these signals.

The complete, two-dimensional proton NMR spectrum of 3-Q-glucose in

DMS0-d 6 solution is shown in figure 34. Display of the 'J'-spectra cross- sections of the 3 anomer (see figure 35) permits the separation of all spin

multiplets except the doublets due to HO-2 and HO-3, the chemical shifts of

which are accidentally coincident under these conditions. Complete coupling

constant data obtained by measurement of the 'J'-spectra cross-sections for

both a and 3 anomers are shown in Table 23.

Table 23. Proton Coupling Constants (Hz) of a- agd 3-Q-Glucopyranoses in

DMS0-d^6 Solutions , Measured by 2-D NMR at 400 MHz

.

Anomer J

1 ,2

J 2,3J 3,4

J 4,5

J 5,6

J 5,6' J

6 ,6

'

a 3.6 9.7 8.7 9.7 2.3 5.0 11.2

3 7.7 8.9 8.5 9.4 2.2 5.9 11.8

Anomer J

1 , HO1

J 2,H0-1 ^2, HO-2 ^3, HO-3J 4,H0-4

J 6,H0-4 J 6' ,H0-6

a 4.8 1.2 6.6 4.8 5.4 5.2 6.4

3 6.6 0 4.7 4.8 4.9 5.5 6.3

a Data size: 8K x 128; Digital resolution in 'J' domain: 0.24 Hz/point.

These spectral analyses have been confirmed by other experiments in which

simplified spectra were obtained for a- and 3-Q-gl ucopyranose by addition of one drop of trifluoroacetic acid to the DMS0-d 6 solutions. This procedure

greatly increased the rate of hydroxyl proton exchange, and thereby removed

the hydroxyl proton coupling constants from the CH proton spin multiplets.

The addition of a catalytic quantity of trifluoroacetic acid also speeded

anomerization, so that for additional confirmation of the spectral assignments

of individual anomers by homonuclear spin decoupling, automated sequences of seven double-resonance experiments were performed, within 7-9 min after the

addition of the acid, before significant anomerization had occurred.

The vicinal CH proton coupling constants (Table 23) indicate that a- and

3-D-gl ucopyranose both adopt the 4 Cj chair conformation in DMS0-d 6 solution.

Specific evidence for existence of the a-anomer in conformation TA), in which

H-2, C-2, C-l , 0-1, and H0-1 adopt a planar 'W -arrangement, is afforded by

observation of the unusual long-range coupling constant, J

2 ^q_-j 1-2 Hz.

156

158

Figure

35.

2D

NMR

J-spectra

at

400

MHz,

$-D-glucose

in

DMSO-d,,

hydroxyl

protons

coupled.
a-D-GLUCOSE, ‘W’-COUPLING

CH2 OH ^0

HO

J2 , HO-1 1-2 Hz

cw r ^H

This coupling constant is not observed for the 3-anomer, and, in fact, the

planar 'W -arrangement is sterically impossible in this anomer. The favored

orientation of HO-1 in the a-anomer may be attributed to steric crowding of

HO-1 by DMS0-d 6 molecules hydrogen bonded to HO-2 and HO-3.

The efficiency of data acquisition for both one- and two-dimensional NMR

depends on the proton spin-lattice relaxation times (Tx) of the sample, since

the pulse sequence cannot normally be repeated at intervals of less than 5T X

. Therefore, the proton T x values of a- and 8-Q-glucopyranose have been measured

under the conditions used for the two-dimensional spectroscopy. The inversionrecovery method was used together with analysis of the data by means of an iterative, three-parameter exponential fit. The Tx results are shown in

Table 24. For solutions of the anomers in DMSO-d^, the pyranoid ring protons

show Tx values in the range 0.5-0. 7 s, the methylene protons values of 0.3 s,

and the hydroxyl protons, 0. 9-1.1 s. This interesting difference between ring

(CH) protons and hydroxyl protons may be due to either greater mobility of the

hydroxyl protons (shorter correlation time), or to association (by hydrogen

bonding) of the hydroxyl protons with solvent molecules containing deuterium

nuclei that are relatively poor relaxers of protons. Measurements of solutions

of a- and 8-Q-glucose in non-deuterated dimethyl sulfoxide are in progress, to

test these hypotheses. However, the results indicate that the pulse sequence

for two-dimensional NMR should not be repeated more often than once every

5.5 s

.

159
Table 24. Proton Spin Lattice Relaxation Times (Ti, Sec) of a- and

3-D-Glucopyranoses a at 400 MHz.

Anomer H-l H-2 H-3 H-4 H-5 H-6 H-6' HO1

H0-2 H0-3 HO-4 HO-6

a 0.7 0.6 0.6 0.6 0.5 0.3 0.3 0.9 1.1 1.0 0.9 1.0

3 0.6 0.7 0.6 0.6 0.6 0.3 0.3 1.1 1.0 1.0 0.9 1.1

Concentration: 100 mg of a- or 3-Q-glucose in DMSO-cU (1.0 mL).

B. Coxon

16. Comparison of Two Isotope Dilution Definitive Methods for the Determination of Glucose in Serum and Evaluation of the American Association

for Clinical Chemistry Candidate Reference Method for Glucose

The measurement of serum glucose levels is one of the most important and

most commonly performed analyses in the clinical laboratory. Clinical chemists

employ many different methods to determine serum glucose levels. When these

methods are compared on serum pools, serious discrepancies are found in the

results. Methods of demonstrated high accuracy and precision are needed to

provide an accuracy base to which the clinical methods can be compared. The

Centers for Disease Control undertook the development of a reference method

with which clinical laboratories could evaluate their procedures. To establish the accuracy of the proposed reference method [a modified hexokinase/

glucose-6-phosphate dehydrogenase (HK/G6PDH) procedure], the Standards

Committee of the American Association for Clinical Chemistry asked NBS to

develop an isotope dilution mass spectrometric (ID/MS) definitive method for serum glucose.

A brief description of the first ID/MS method for serum glucose develooed

at NBS is as follows: A known weight of uniformly labeled 13 C-glucose is

added to a known weight of serum. After the serum is allowed to equilibrate,

it is freeze-dried. The serum is then treated with acetone under anhydrous

conditions to convert glucose into 1 ,2:5,6-di-0-isopropylidine-a-D-glucofuranose (DAG). Three thin-layer chromatography steps are employed to

separate DAG from other reaction products including the acetone-condensation

products with other hexoses. For the initial comparison of this method with

the reference method, samples were introduced to the mass spectrometer via the

direct insertion probe. All later work involved sample introduction via

packed column gas chromatography. Measurements are made on a low resolution

magnetic sector instrument operated in the electron impact (El) mode.

+ Magnetic switching is employed in the sequential monitoring of the (M-15)

ions for the labeled and unlabeled DAG. The measured unlabeled/labeled ratio

from serum samples is compared with the measured ratios of calibration standards, which consist of known weights of SRM glucose and uniformly labeled

13 C-glucose, converted to DAG. For quantitation, each sample measurement is

bracketed by measurements of the two calibration standards whose ratios most

closely bracket that of the sample. Linear interpolation is then used to

calculate the amount of glucose in the sample.

160
The results of the initial comparison of our ID/MS method with the

HK/G6PDH reference method is summarized in Table 25. The reference method

results are a composite of the results obtained from twelve laboratories

,

including NBS, on five serum pools analyzed in quadruplicate over a five-day

period. The results demonstrate that the methods agree well for all pools

tested. A full report of this study is undergoing review for publication as an NBS 260 report.

Table 25. Comparison of Candidate Reference Method Results with ID/MS

Target Values. Differences and Standard Deviations in mg/L.

Manual

9

- ID/MS Semi -Automated*

3 - ID/MS

Pool Mean Difference S.E.D.

C Difference S.E.D.C

409.0 4.4 4.5 8.9 2.9

785.8 7.6 5.5 4.1 4.0

1344.4 - 1.1 7.3 - 3.0 6.3

1969.7 -19.2 9.8 -32.2 9.0

2978.7 -36.9 13.9 -48.6 13.6

Candidate reference method with manual pipetting.

^Candidate reference method with semi -automated pipetting.

c Standard error of the difference.

A second ID/MS method was devised to provide a much simpler wet chemical

procedure as well as to verify the accuracy of the DAG method. This approach

utilizes the same labeled glucose, but differs markedly otherwise. After

equilibration, the serum is treated with ethanol to precipitate protein and

the deproteinized serum is freeze-dried, treated with 1 -butyl boronic acid in

anhydrous pyridine followed by acetic anhydride to form the derivative, a-Dglucofuranose cyclic 1 ,2:3,5-bis-(butylboronate)-6-acetate (glucose BBA).

Separation of glucose BBA from the BBA derivatives of other monosaccharides is

accomplished by gas chromatography using a 100 m SCOT capillary column.

Measurements are made in the electron impact mode, using the ( M - 5 7 ) ion,

which is a prominent fragment ion for glucose BBA but only a minor fragment

ion in the mass spectra of other hexose BBA's. Bracketing of the samples

with similarly derivatized calibration standards is again used for quantitation. Table 26 shows the results for the comparison of the two ID/MS methods,

performed at NBS, with the reference method, performed simultaneously at CDC,

on three human serum pools.

Table 26. Comparison of the Two ID/MS Derivative Methods and the CDC

Reference Method on Three Human Serum Pools Sampled

Simultaneously. Mean Results are in mg Glucose/g Serum.

DAG Glucose BBA HK/G6DH

Pool Mean CV {%) Mean CV (%) Mean CV (%)

A 0.6843 0.29 0.6779 0.19 0.6845 0.51

B 1.803 0.15 1.790 O.

1 ? 1.794 0.29

C 2.919 0.24 2.901 0.18 2.912 0.22

161
The agreement of all three methods is excellent (<1 percent range for

each pool). To check for interferences, samples from each pool were remeasured under

+ isobutane chemical ionization (Cl) conditions, with monitoring of the (M+l) ions for both DAG and glucose BBA samples. The Cl results

agreed with the El results within the uncertainties of the measurements.

Our results have shown that both ID/MS methods are very precise, and

after exhaustive testing, we have found no bias sufficient to interfere with

the intended uses of either method. Therefore, each method satisfies the

requirements for a definitive method. However, when the two are compared on identical serum samples, the DAG results are consistently higher than the

glucose BBA results by a small but statistically significant amount (<1 percent for all pools tested). When compared on an aqueous glucose solution,

the two methods agree within the uncertainties of the measurements. Therefore, the small systematic difference observed is related to the presence of

the serum matrix. The two ID/MS methods have been described in a manuscript

to be submitted to Biomedical Mass Spectrometry . The excellent agreement of

the KH/G6PDH results with the ID/MS definitive method values proves that the

CDC method fulfills the requirements of a reference method.

A. Cohen, H. S. Hertz, J. Mandel , R. Schaffer, L. T. Sniegoski, T. Sun,

M. J. Welch, E. White V

17. Comparison of Two Isotope Dilution/Mass Spectrometry (ID/MS) Methods

for the Determination of Total Serum Cholesterol

Both U.S. and international societies for clinical chemistry recognize

the need for definitive (i.e., essentially bias-/ree and highly precise)

methods that can serve, along with high-purity SRM's, as the accuracy base for

clinical chemistry. NBS has developed a candidate definitive method for total

serum cholesterol involving ID/MS. Our publication [ Cl in . Chem . 26 , 854-860

(1980)] provides data that show the absence of interferences in the ID/MS

measurements involved in the method and the high reproducibility of the

results, thus demonstrating the method's accuracy and precision. To ensure scientific validity, we sought external confirmation by comparison with

another laboratory.

Researchers at the Karol inska Institute (KI), Stockholm, Sweden, who were

the first to report an ID/MS method for total cholesterol [1], used their

method to analyze samples of the same serum pools as were run at NBS. Their

analyses gave results with mean values consistently lower than the NBS values

for those pools. NBS study of the cholesterol used at the KI as primary

standard revealed that it contained lathosterol, an isomer of cholesterol that

interfered with the KI measurement method. When the KI reanalyzed the serum

pools with SRM cholesterol used as the primary standard, the bias was no longer evident, with mean values for the pools ranging from 1.5 percent below

to 1.5 percent above the NBS mean values (Table 27). The imprecision of the

results obtained at the KI was about the same for the two series of analyses

and were from three to ten times larger than the NBS values. Several aspects

of the KI method have been identified as contributing to the imprecision.

Although no systematic bias is now apparent between the two methods, the

imprecision of the KI method limits its usefulness for confirming the accuracy

162
Table 27. Total Cholesterol Concentrations as the Mean ± One Standard Deviation of the Mean in mmol/L, for Five Serum Pools, as Determined by

ID/MS in Two Series of Analyses at the Karol inska Institute (KI)

and One at the National Bureau of Standards (NBS).

Laboratory Pool

N

a A B C D E

KI/firstc series 8 3.39 ± . 058

b

4.68 ± .036 6.11 ± .046 7.35 ± .054 8.59 ± .088

KI/secondd

series

8 3.39 ± .019 4.73 ± .059 6.15 ± .046 7.57 ± .112 8.85 ± .064

NBS 16 3.43 ± .006 4.72 ± .008 6.15 ± .011 7.47 ± .011 8.79 ± .015

a N is the number of measurements per pool.

^Calculated from an analysis of variances [2].

c Analyses performed without SRM Cholesterol as the primary standard.

^Analyses performed with SRM Cholesterol as the primary standard.

Of the NBS method as a definitive method. (The KI method was not designed to serve as a definitive method.) Conversely, the NBS method, which has been

rigorously tested for accuracy in-house, does prove that the KI method fulfills

the accuracy requirements of a reference method. The comparison of these

ID/MS methods has been described in a manuscript submitted to Cl inical

Chemistry .

References

[1] I. Bjorkhem, R. Blomstrand, and L. Svensson, Clin. Chim. Acta

54, 185 (1974).

[2] J. Mandel and R. Paule, Anal . Chem . 42 , 1194 (1970).

A. Cohen, H. S. Hertz, J. Mandel, R. Paule, R. Schaffer, L. T. Sniegoski,

M. J. Welch, E. White V

18. Identification of Components Leached from Implants Made of Siloxane

Polymers and Influence on Prolyl Hydroxylase Activity

Use of a mammary prosthesis following radical mastectomy or for cosmetic

purposes has become a common medical practice. However, after implantation

these prostheses are frequently encapsulated with collagenous tissue to such

an extent that the patient finds it necessary to have them removed. In

current practice, mammary augmentation devices usually consist of an outer

siloxane envelope filled with either a siloxane gel or siloxane gel-saline

mixture. Our research for the Food and Drug Administration (FDA) was designed

to determine whether there is a substance leaching from the implanted device

which activates the enzyme system for collagen production. Researchers at FDA

had evidence that gel may be diffused through the envelope.

163
Test samples of prosthesis envelope and gel were obtained from Dow

Corning Corp. To ten-gram quantites of prosthesis gel in rigorously cleaned

glass containers was added 20 mL of purified water. The mixture was stirred

slowly for four hours, then the leachate-containing water was decanted into a 500 mL acid-cleaned flask, after which water was removed in a rotary evaporator. Water from ten leachings was pooled. Leachate residue was dissolved

in 25 mL of 0.04 M TRIS-HC1 (pH 7.6) buffer solution which was centrifuged to

remove particulate matter. This leachate was used to study influence on enzyme activity. Alternatively, leachate-containing water was extracted with

methylene chloride. The composition of the extract was determined by gas

chromatography/mass spectrometry, and was found to consist largely of dimethyl

siloxane fragments.

for which n had values of 0-3.

Prolyl hydroxylase was chosen for the study of leachate influence on the

collagen-forming enzyme system, because its activity is considered to be rate

limiting. This enzyme was extracted from the leg bones of 15-day chick

embryoes. Its substrate, protocollagen, was obtained from the calvaria of

these embryoes incubated with gentle shaking for 24 hours in tissue culture

with tritium-labeled proline at 37 °C. Enzymatic activity assay was performed

by mixing enzyme, substrate, and cofactor solution, incubating at 37 °C for 15

min, then stopping the reaction with trichloroacetic acid. The mixture was centrifuged and tritiated water separated from other soluble tritiated com- pounds with a cation exchange resin. Enzyme activity is proportional to the

amount of tritiated water found in this procedure. No rate influence on the

prolyl hydroxylase by the silicone leachate was observed. Rate studies

employing leachate from silicone envelopes similarly did not show measurable

effects. Small quantities of ethyl alcohol, a,

a' -dipyridyl , or dimethylsulfoxide, however, were shown to be inhibitory.

A. E. Davidson, S. N. Chesler, L. R. Hilpert, B. F. Howell, D. J. Reeder,

E. White V

19. Combined LC/MS Techniques: Development of an Interface System Compatible

with Reversed-Phase LC

High-performance liquid chromatography (HPLC) can be used for the separation of many nonvolatile and polar molecules that are not amenable to gas

chromatography and can handle many samples in matrices that are difficult to

analyze directly by gas chromatography, such as water or heavy oil. Therefore,

the coupling of a mass spectrometer, a universal and/or selective detector, to

a liquid chromatograph has generated a great deal of interest. Numerous

publications have appeared and two methods have been used in commercial

instrumentation.

164
Due to the limitations of existing interfaces, we have constructed a unique LC/MS interface that operates by removing most of the excess solvent

from the effluent stream as it flows down a heated wire. The residual con- centrated solution- is drawn into the vacuum of the mass spectrometer and

volatilized into the ion source. It has been found to perform satisfactorily

with several normal -phase chromatographic separations. The interface and some applications are described in the previous annual report and in Christensen

et dl. 9 Anal . Chem. , 53 , 171 (1981).

A large portion of analytical LC is now performed using reversed-phase

chromatography and it is, therefore, desirable to accomodate the aqueous

solutions used in that chromatographic mode. The only part of our system

which did not operate well with water was the probe which introduced the

concentrated stream into the ion source. The difficulty arose because of the

high surface tension and heat of vaporization of water. Attempts to overcome

the problem by heating the tip of the probe were unsuccessful. A sonic

spraying device was developed, using a solenoid coil around the exterior part

of the solvent introduction capillary (see figure 36). The capillary, being

made of nickel, is magnetostrictive, so that an alternating field causes it to

vibrate. When tuned to resonance, the vibration is strong enough to cause

25 ym diameter water droplets to be sprayed from the surface at the tip of the

probe. Concentrated buffer solutions can be sprayed without evaporative

deposition clogging the 8-10 ym orifice; adenosine, a test compound of low

volatility, can be dispersed well enough to observe a molecular ion.

concentrator wire

droplets

coi,

phosphor-bronze diaphragm

vacuum seal

-s-l

stepped down for amplitude gain

( not to scale )

flow control wire

Figure 36. Magnetostrictive sonic atomizing probe for LC/MS.

165
The first reversed-phase application was that of measuring the polar

molecule, valproic acid, in a complex matrix (serum), by direct injection of

serum onto the chromatographic column. Other analyses for this compound

require extraction from the serum and preparation of a derivative. Preliminary trials of the direct LC/MS method showed precision of about 10 percent

relative standard deviation, e.g., 100 ppm ± 10 ppm. If refinements can improve the precision, the method will be used for certifying trace level

constituents in forthcoming Standard Reference Materials. Other applications

of the LC/MS technique to reversed-phase liquid chromatography are now being

pursued.

R. G. Christensen, H. S. Hertz, E. White V

20. Laser Induced Photodissociation of Ions

As part of a five-year mass spectrometry competence building program in

"Analysis of Ionization Mechanisms and Ion Structures," we have begun to

explore the laser induced photodissociation of ions, particularly the potential for organic structure determination and for analytical specificity.

The photodissociation of ions has been used for some years in conjunction

with time-of-fl ight and ion cyclotron resonance spectrometers, as well as more

recently with mass filter spectromet' : to investigate absorption cross sections, dissociation pathways, ar kinetic energy release. These studies,

for the most part, can be classifi_d as physical chemistry and have been

limited to low molecular weight compounds. A group under J. H. Beynon [1]

has reported in the last year, the laser induced photodissociation of ions

using an argon ion laser and conventional double focusing magnetic mass spectrometers of both normal and reversed geometry. The molecules examined

have been simple mono- and di-substituted benzenes and interest has centered

on kinetic energy release and dissociation as probes of the mechanisms of ion

dissociations.

The experimental set-up which we are presently using is shown schematically in figure 37. The mass spectrometer is an existing high resolution

instrument of Mattauch-Herzog geometry equipped to allow detection of ions

decomposing in the first field-free region (metastable ions) by accelerating

voltage scans and by two linked scan methods in which the electrostatic

analyzer and magnet are scanned simultaneously. The laser, optical components, and lock-in amplifier, borrowed to test feasibility, are being replaced

with more suitable components. An argon ion laser with an output of at least one watt at each of ten wavelengths between 350 and 529 nm (3.47-2.34 eV), is

being installed.

166
CHOPPER

MIRROR

Figure 37. Schematic of the experimental arrangement used for the

laser induced photodissociation of ions.

The photodissociation behavior of ions from about a dozen compounds has

been examined at 514.5 nm (2.41 eV) using either accelerating voltage or linked

electrostatic/magnetic field scans. The pronounced and selective effect of

irradiation on the intensities of metastable ions, which leads to the formation

of m/z 77 in nitrobenzene, is shown in the accelerating voltage scans in figure

38. Fragmentation pathways not observed in spontaneous metastable ion decompositions also occur. Thus, as may be seen in figure 39, irradiation causes 2,4-hexadiyne molecular ion to lose a methyl radical, a fragmentation also

observed by collisional activation. Among other compounds showing laser

induced photodissociation were benzene, naphthalene, anthracene, cinnamic

acid, N-trifluoroacetylphenylalanine cyclohexyl ester (which was examined as a model for planned studies of peptides), and silver acetate. Compounds not

showing any activity at the 514.5 nm wavelength included aliphatic esters, an aliphatic amide, and, unexpectedly, an aromatic compound, phenol.

Planned activities for the near future include installation of the more

powerful laser and new optics, automation of data collection which is cur- rently entirely manual, some survey work to find out what kinds of compounds

(ions) will show activity and at which wavelengths, and major modification of

the mass spectrometer flight tube to permit small -angle crossed-beam experiments. This latter modification will allow photodissociation of ions created

by field desorption. The combined techniques should be a powerful method for

the determination of the structure of organic molecules.

Reference

[1] Harris, F. M., Mukhtar, E. S., Griffiths, I. W., and Beynon, J. H.,

Proc. R. Soc . Lond . A374, 461-473 (1 981 ).

H. S. Hertz, D. J. Pereles, J. C. Travis (550), E. White V

167
2.0 3.0 4.0

Laser Off

Figure 38. Accelerating voltage metastable ion scans showing the effect of

irradiation at 514.5 nm on the loss of N02 from nitrobenzene

molecular ion.

168
C-C-C-CH

IK

169

Figure

39.

Linked

electrostatic

analyzer/magnetic

field

metastable

ion

scans

showing

the

loss

of

of

methyl

from

2,4-hexadiyne.

Upper

trace:

laser

on.

Lower

trace:

laser

off.
21 . A Method for the Mass Calibration of Photoplates in Field Desorption

Mass Spectrometry and Its Application to Some Peptides

Exact mass determination by high resolution mass spectrometry has been a valuable tool for structure elucidation and has been widely used for compounds

which give electron impact spectra. However, for high mass, nonvolatile

molecules, ionization by field desorption is often necessary to obtain a spectrum, and for this method exact mass determination has proved difficult.

The common mass calibration material for electron impact, high resolution mass spectrometry, perfl uorokerosene (PKF), cannot be used for field desorption

since it deactivates the emitters on which the desorption is accomplished.

Other procedures such as mass calibration in electron impact, then switching

to field desorption, and the use of complex mixtures as calibrants have been

used, but are unreliable or very inconvenient. A straightforward way to

establish a mass calibration is essential if high resolution, field desorption

mass spectrometry is to be routinely useful.

We have developed a method, applicable to field desorption, for establishing a high resolution mass scale on a photoplate by a double exposure in

which sample and calibrating material are separately field desorbed onto the same line of the photoplate. Mass calibration is achieved by field desorption

of a mixture of silver methanesul fonate and trifluoromethanesulfonate

+which

gives cluster ions of the general formula [Agm+n+-| (0 3 SCH 3 ) m

(0 3 SCF 3 ) p

] [1].

These ions provide calibration masses at about every 50 mass units to above

1400 as shown in figure 40.

The precision of the calibration method was evaluated using two pentapeptides, methionine enkephalin, and leucine enkephalin, known to give good

low resolution spectra. For 11 spectra of methionine enkephalin with an expected [M+H]

+ ion at 574.2335, the measured [M+H]

+ was 574.2310 with a standard deviation of 0.Q063 (range: 574.2437 - 574.2233); and for 8 spectra

of leucine enkephalin with an expected [M+H]

+ ion at 556.2771, the measured

[M+H]

+ was 556.2773 with a standard deviation of 0.0051 (range: 556.2835 - 556.2679).

The accuracy of the method was evaluated by using five polypeptides of

known mass. The masses obtained for [M+H]

+ and for other ions are compared to

the theoretical masses in Table 28.

From the above, we conclude that a mixture of silver methanesul fonate and

silver trifl uoromethanesul fonate is a good calibrating material and provides

satisfactory precision and accuracy for high resolution, field desorption mass spectra using photoplate detection.

170
001

Figure

40.

Field

desorption

mass

spectrum

ofa

1:1

mixture

of

silver

methanesul

fonate

and

silver

trifluoromethanesulfonate.

Average

of

40

exposures

on

which

overexposed

lines

have

been

omitted

from

averaging,

thus

enhancing

the

higher

mass

end

of

the

spectrum.
Table 28. Results of Exact Mass Measurements on Peptides.

MeasuredPeptide

Theoretical Mass

(Mass Units)

Measured Mass

(Mass Units)

Theoret

(Mill imass

Trp-Met-Asp-Phe-Amide

Gastrin Related

Tetrapeptide

[M+H]

+

: 597.2495 597.2501 0.6

Tyr-Il e-His-Pro-Phe

Angiotensin II Pentapeptide

[M+H]

+

: 676.3459 676.3471 1.2

Lys-Phe-Il e-Gly-LeuMet-Amide

Eledoisin Related

Peptide

[M+H]

+

: 707.4278 707.4187 -9.1

Tyr-Gly-Gly-Phe-Met [M+H]

+

: 574.2335 574.2311 -2.4

Met-Enkephal in [M+Na]

+

: 596.2155 596.2247 9.2

[M+ 107Ag]

+

: 680.1308 680.1287 -2.1

[M+ 109Ag]

+

: 682.1304 682.1301 -0.3

Gly-Phe-Met : 354.1487 354.1483 -0.4

Tyr-Gly-Gly-Phe-Leu [M+H]

+

: 556.2771 556.2778 0.7

Leu-Enkephal in [M+Na]

+

: 578.2591 578.2559 -3.2

Gly-Phe-Leu : 336.1922 336.2070 4.8

Some advantages of the method are: calibration is accomplished in

mode with no switching between El and FD required; the calibration material

leaves the activated emitter wire undamaged so that sample and calibration

material can be desorbed one at a time in either order from an emitter; the

components of the calibration material are commercially available; the calibration masses are spaced at reasonable intervals over a large mass range; the mass defect of the calibration material makes sample ions easily distinguishable from calibration ions; and the existence of two silver isotopes at a ratio close to 1 leads to clusters from which lines of appropriate intensity

can be chosen.

Reference

[1] Robert, G. D. ; White V, E. Unpublished results.

R. Espinosa-Leniz, E. White V

172
22 . Design of a Toxic Chemicals and Carcinogens Handling Laboratory

This year the Organic Analytical Research Division finished the design

phase for the construction of a toxic and/or carcinogenic chemicals handling

laboratory. This facility will be used for the storage, weighing, solution,

and chromatographic analyses of these chemicals and will markedly reduce the

potential danger for exposure to our staff. The facility is being implemented

because (1) an Increasing number of toxic and carcinogenic compounds are used

in our laboratories, (2) existing laboratory storage and weighing areas for

such chemicals are very congested, and (3) a greater number of staff members

are required to work with these compounds.

In FY 1981, the services of an architectural and engineering firm (A&E) were procured to design the facility to meet our use plan. During the design

phase, numerous meetings of the A&E, NBS scientists, and NBS Plant personnel were held.

The floor plan for the proposed facility is shown in figure 41. The

facility is entered through an anteroom in which the user can dress in protective clothing before passing into the inner laboratory. The air flow in the

inner laboratory is designed to minimize any contamination of the users from

chemicals in the facility. Two Class II, Type II hoods are positioned back

to back in the center of the lab and are flanked by custom-built storage

cabinets. All air in the laboratory is subjected to both HEPA (particulate

removal) and charcoal (vapor removal) filters. The work areas on either side

of the facility will hold gas and liquid chromatographic instrumentation

(specially vented) for analysis work. The facility will be exited either

through a second change room and then through a shower (for shower-out

protocols) or through the first change room, thus bypassing the shower. The

facility is provided with operation monitoring alarms and a provision for

emergency power in the event of a power failure.

During FY 1982, the contract for construction will be sent out for bid

and the facility constructed.

S. N. Chesler, H. S. Hertz

i

I

173
MEW C l_ O O R P L A M TSC.ALC \'-t

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JA)£KAT1C>N INTO OROuT OF LAB MODULE. 1 0 PERIMETER. CP EXIST N 6 METAL PARTITIONS ® FLOoe., CEIUMfi fABuTnNft WAU3

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5)ALLPIPE CONDUIT $ DUCT PENETRATIONS THRU LAB FLEORS, WALLS f CCNC CEIUMC. 4INSIDE, (bp ALA. ELECTRICAL CONDUITS PENETEATIMC THE LAB EXTERIOR. ENVELOPE

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too lb. AIR

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.

Floor plan for the proposed NBS toxic chemicals handling

laboratory. 174
C. Outputs and Interactions

(Organic Analytical Research Division)

1 . Publ i cations

Brown, J. M. , Wise, S. A., and May, W. E. , Determination of Benzo(a)pyrene in

Recycled Oils by a Sequential HPLC Method, J. Environ. Sci. Health A15

(6), 613-623 (1980).

Chesler, S. N. , May, W. E., White, P. A., Parris, R. M. , and Guenther, F. R.

,

Determination of Polychlorinated Biphenyls in Waste and Lubricating Oils,

Proc. of Joint Conf. on Meas. and Stds. for Recycled Oil /Systems Perfor.

and Durability , NBS SP 584, 295-297TT980TT

Eng, G. E. and Richie, K. L. , Reinvestigation of the Structure of the Trimethyltin Chloride 2,2' -Bipyridine Adduct, Inorganica Chimica Acta 43,

233-235 (1980).

Hertz, H. S. , Certification of Clinical and Environmental Trace Organic

Reference Materials, Proc. Intern. Sym. on the Prod, and Use of Res.

Matls. , West Berlin, Germany, 393-398 (1980).

Hertz, H. S. , Standard Reference Materials for Trace Organic Environmental

Analysis, Abstracts from the 1980 Pittsburgh Conference, Atlantic City,

NJ, Paper No. 567 (1980).

Hertz, H. S. , Brown, J. M. , Chesler, S. N. , Guenther, F. R. , Hilpert, L. R.

,

May, W. E. , Parris, R. M. , and Wise, S. A., Determination of Individual

Organic Compounds in Shale Oil, Anal. Chem. 52 (11), 1650-1657 (1980).

Margolis, S. A. and Longenbach, P. J., Analysis of Purity of Commercial

Peptides by High-Resolution Liquid Chromatography, The Role of Peptides

in Neuronal Function, J. Barker and T. Smith, eds. , Marcel Dekker, Mew

York, NY (1980J7

Reeder, D. J. , Place of Reference Materials and Reference Methods in the

Evaluation of Drug Effects, Drug Effects on Lab. Test Results, 49-57

(1980).

Siggaard-Andersen, 0., Durst, R. A., and Maas, A. H. J., Physico-Chemical

Quantities and Units in Clinical Chemistry, J, Clin. Chem. Clin. Biochem.

18, 829-854 (1980).

Bartle, K. D. , Lee, M. L. , and Wise, S. A., Factors Affecting the Retention of

Polycyclic Aromatic Hydrocarbons in Gas Chromatography, Chromatographia

1_4 (2), 69-72 (1981 ).

Bartle, K. D. , Lee, M. L. , and Wise, S. A., Modern Analytical Methods for

Environmental Polycyclic Aromatic Compounds, Chem. Soc. Rev. 10 (1), 113-

158 (1981).

Brown-Thomas, J. M. and May, W. E. , The Analysis of Phenols in Water by HighPerformance Liquid Chromatography, Abstracts of the 1981 Pittsburgh

Conference, held March 9-13, 1981, Atlantic City, NJ (1981).

175
Chesler, S. N. , Guenther, F. R. , and Christensen, R. G. , An Electrically

Heated Sample/Injector for Use with High-Efficiency Gas Chromatographic

Columns, Recent Adv. in Capillary Gas Chromatog. , W. Bertsch, ed. , 395

(1981).

Chesler, S. N. , White, P. A., May, W. E., and Parris, R. M. , Analysis of

Polychlorinated Biphenyls in Waste and Lubricating Oils, Abstracts of the

1981 Pittsburgh Conference, held March 9-13, 1981, Atlantic City, NJ,

Paper No. 227 (1981 )

.

Christensen, R. G., Hertz, H. S., Meiselman, S. , and White V, E., A Liquid

Chromatograph/Mass Spectrometer Interface Incorporating Continuous

Sample Preconcentration, Anal. Chem. 53 (2), 171-174 (1981).

Durst, R. A. and Bates, R. G. , Hydrogen Ion Activity, Encyc. of Chem. Tech.,

3rd ed. , 13., 1-12 (1981).

El Khadem, H. S. and Coxon, B., A Nitrogen-15 N.M.R. Study of Some Dihydro-LAscorbic Bis(phenylhydrazone) Derivatives, Carbohyd. Res. 89, 321-325

(1981).

Guenther, F. R. , Chesler, S. N., and Parris, R. M. , The Quantitative Analysis

of Some N-Heterocycl ics in Shale Oil by Two-Dimensional ( GC

)

2

, Abstracts

of the 1981 Pittsburgh Conference, held March 9-13, 1981, Atlantic City,

NJ, Paper No. 45 (1981 )

.

Guenther, F. R. , Parris, R. M. , Chesler, S. N., and Hilpert, L. R., The

Determination of Phenolic Compounds in Alternate Fuel Matrices, J. Chromatog. 207 , 256-261 (1981).

Hancock, D. K. , Literature Survey Characterization of Petroleum Derived Oils

by Luminescence Spectroscopy, Internal Report for the NBS Recycled Oil

Program (1981).

Harrison, S. H. , Zeisler, R. , and Wise, S. A., Project Summary: Pilot Program

for the National Environmental Specimen Bank - Phase I, EPA Res. Report

(1981).

Howell, B. F. and Velapoldi, R. A., Fluorescent Penetrant Testing: A Review,

and Research That Can Be Done to Improve Quantitation, to be published as an NBS Special Publication (1981).

Kaplan, A. E. , Weiss, E. R. , Byrne, S. T. , El-Torkey, N. M., and Margolis,

S. A., Purified Reduced Nicotinamide Adenine Dinucleotide Responses to

Lactate Dehydrogenase Isozymes from Three Cell Sources, Science 212 , 553-

555 (1981).

MacCrehan, W. A., Differential Pulse Detection in Liquid Chromatography and

the Application to the Measurement of Organometal Cations, Anal. Chem. 53

(1 ), 74-77 (1981 ).

176
May, W. E., Brown-Thomas, J. M. , Hilpert, L. R. , and Wise, S. A., Certification of Selected Polynuclear Aromatic Hydrocarbons in SRM 1580,

"Organics in Shale Oil," Anal. Methods and Biol. Fate of Polynuclear

Aromatic Hydrocarbons, M. Cooke and A. J. Dennis, eds., Battelle Press,

Columbus , OH, 1-16 (1981 )

.

Reeder, D. J., Coxon, B., Enagonio, D. P., Christensen, R. G., Howell, B. F.,

Paule, R. C. , Mandel , J., and Schaffer, R., Standard Reference Materials:

SRM 900, Anti epilepsy Drug Level Assay Standard, NBS SP 260-72, 67 pages

(1981).

Schaffer, R. , Mandel, J., Sun, T. , Cohen, A., and Hertz, H. S., Evaluation of

the AACC Candidate Reference Method for Serum Glucose vs an ID/MS Method,

to be published as an NBS Special Publication.

i Blubaugh, E. A., and Doane, L. M., A Vacuum Thin Layer Electrochemical Cell

for Nonaqueous Spectroelectrochemistry , Anal. Chem. , in press.

I Christensen, R. G., Hertz, H. S., Reeder, D. J., and White V, E., Developments

in the Analysis of Priority Pollutants by Liquid Chromatography/Mass

Spectrometry and Immunoassay Procedures, Adv. in the Identification and

Anal, of Org. Poll, in Water 1, Lawrence H. Keith, ed., Ann Arbor Science

Publishers, Ann Arbor, MI, in press.

Doane, L. M. and Fatiadi, A. J., Electrochemical Oxidation of Several Oxocarbon Salts in N,N-Dimethylformamide, J. Electroanal. Chem. and Interfacial Electrochem. , in press.

Doumas, B. T. , Bayse, D. D. , Carter, R. J., Peters, T., Jr., and Schaffer, R.

,

A Reference Method for the Determination of Total Serum Protein. I. Development and Validation, Clin. Chem. 27 , in press.

Doumas, B. T. , Bayse, D. D., Bauer, K. , Carter, R. J., Elevitch, F. , Garber,

C. C., Graby, R. A., Hause, L. L., Mathes, A., Peters, T., Jr., Rand,

R. N. , Reeder, D. J., Russell, S. M., Schaffer, R. , and Westgard, J. 0.,

A Reference Method for the Determination of Total Protein. II. Test for

Transferability, Clin. Chem. 27 , in press.

Durst, R. A., Views on the Current Status of the pH Scale, Blood pH, Carbon

Dioxide, Oxygen, and Calcium-Ion , 0. Siggaard-Andersen , ed. , Copenhagen,

in press.

Durst, R. A. and Maienthal, E. J., Sampling Operations for the Pilot Environmental Specimen Bank, IAEA Report, in press.

Durst, R. A., Siggaard-Andersen, 0., and Maas, A. H. J., Reference and Quality

Control Materials for pH and Blood Gases, Blood pH, Carbon Dioxide,

Oxygen, and Calcium-Ion , 0. Siggaard-Andersen, ed., Copenhagen, in press.

Harrison, S. H. , Zeisler, R. , and Wise, S. A., Pilot Program for the National

Environmental Speciman Bank - Phase I, EPA Res. Report , in press.

177
Konash, P. L. , Wise, S. A., and May, W. E. , Selective Quenchofluorometric

Detection of Fluoranthenic Polycyclic Aromatic Hydrocarbons in HighPerformance Liquid Chromatography , J. Li q . Chromatog. , in press.

MacCrehan, W. A. and Durst, R. A., Dual -Electrode Liquid Chromatographic/

Electrochemical Detector for the Determination of Analytes with High

Redox Potentials, Anal. Chem. , in press.

Schaffer, R. , Velapoldi, R. A., Paule, R. C., Mandel , J., Bowers, G. N., Jr.,

Copeland, B. E. , Rodgerson, D. 0., and White, J. C. , Reference Method for

Determination of Serum Sodium, Clin. Chem. , in press.

Sonnefeld, W. J. , Zoller, W. H. , May, W. E., and Wise, S. A., On-Line Multidimensional Liquid Chromatographic Determination of Polycyclic Aromatic

Hydrocarbons, Anal . Chem. , in press.

Wise, S. A., High-Performance Liquid Chromatography for the Determination of

Polycyclic Aromatic Hydrocarbons, Chapter 5 in Handbook for Polycyclic

Aromatic Hydrocarbons , A. Bj0rseth, ed., Marcel Dekker, New York, NY,

in press.

Wise, S. A., Bonnett, W. J., Guenther, F. R. , and May, W. E., A Relationship

Between Reversed-Phase C 18 Liquid Chromatographic Retention and the Shape

of Polycyclic Aromatic Hydrocarbons, J. Chromatog. Sci. , in press.

Yap, W. T. and Durst, R. A., Electron Transfer in Molecules with Interacting

Multiple Redox Centers, J. Electroanal. Chem. , in press.

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

H. S., Mandel, J. , Paule, R. C., Svensson, L. , Bj0rkhem, I., and Blomstrand,

R. , Comparison of Two Isotope Dilution/Mass Spectrometry Methods for the

Comparison of Total Cholesterol, Clin. Chem. , submitted for publication.

2. Talks

S. A. Margolis, "Nutrient Analysis Standards," Interagency Technical Committee

(IATC) Working Group on Nutrient Composition of Foods, National Institutes

of Health (NIH), Bethesda, MD, Sept. 10, 1980.

W. E. May, "Quality Assurance in Environmental Trace Organic Analysis,"

Chemistry Department, University of Maryland, College Park, MD, Sept. 12,

1980. Invited

E. White V, "High Resolution and Field Desorption Mass Spectrometry," Department of Chemistry, University of Maryland, College Park, MD, Sept. 12,

1980.

S. A. Wise, "The Environmental Specimen Bank Program," EPA/Narragansett

Seminar, Narragansett , RI , Sept. 15, 1980. Invited

178
S. A. Wise, "The Relationship of Liquid and Gas Chromatographic Retention and

the Shape of Polycyclic Aromatic Hydrocarbons," Washington Chromatography

Discussion Group, Hewlett-Packard Company, Rockville, MD, Sept. 18, 1980.

Invited

M. L. Fultz, "A Study of the Spectroelectrochemistry of o-Tolidine Using a Vidicon Detector," 1980 Federation of Analytical Chemistry and Spectroscopy Societies (FACSS), Philadelphia, PA, Oct. 1, 1980.

W. A. MacCrehan, "A Dual Electrode Reductive Electrochemical Detector for

Liquid Chromatography," 1980 Federation of Analytical Chemistry and

Spectroscopy Societies (FACSS), Philadelphia, PA, Oct. 1, 1980.

P. A. White, "The Certification of Generator Columns for the Production of

Aqueous Polynuclear Aromatic Hydrocarbon Standards - SRM 1644," 1980

Federation of Analytical Chemistry and Spectroscopy Societies (FACSS),

Philadelphia, PA, Oct. 2, 1980.

H. S. Hertz, "Determination of Individual Organic Compounds in Shale Oil,"

University of Maryland, College Park, MD, Oct. 3, 1980. Invited

E. A. Blubaugh, "Asymmetric Schiff Base Complexes of Nickel (II) and Copper

(II)," Electrochemical Society Meeting, Washington, DC, Oct. 4, 1980.

S. A. Wise, "A Relationship Between Reversed-Phase C 18 Liquid Chromatographic

Retention and the Shape of Polycyclic Aromatic Hydrocarbons," International Symposium on Advances in Chromatography, Houston, TX, Oct. 7,

1980.

H. S. Hertz, "Quantitative Trace Organic Analysis," Chemistry Department,

Northeastern University, Boston, MA, Oct. 27, 1980. Invited

W. A. MacCrehan, "Detection of Reducible Analytes Separated by Liquid Chromatography Without Rigorous Oxygen Exclusion," Eastern Analytical Symposium,

New York, NY, Nov. 21 , 1980.

L. T. Sniegoski, "The Use of Isotope Dilution/Mass Spectrometry for the

Accurate Determination of Organic Constituents in Serum," 15th American

Chemical Society Middle Atlantic Regional Meeting, Washington, DC,

Jan., 1981, with A. Cohen, H. S. Hertz, R. Schaffer, M. J. Welch, and

E. White V.

W. E. May, "High-Performance Liquid Chromatographic Methods for Trace Organic

Analysis," Chemistry Department, Howard University, Washington, DC,

Jan. 23, 1981. Invited

H. S. Hertz, "Quantitative Analysis of Individual Trace Organic Compounds in

Shale Oil," Hewlett-Packard GC/MS User's Meeting, Baltimore, MD, March 6,

1981. Invited

F. R. Guenther, "The Quantitative Analysis of Some N-Heterocycl ics in Shale

Oil by Two-Dimensional (GC) 2 ," 1981 Pittsburgh Conference on Analytical

Chemistry and Applied Spectroscopy, Atlantic City, NJ, March 9, 1981.

179
D. J. Reeder, "FI uoroimmunoassay for Detection of Dinitrophenols in Water,"

1981 Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Atlantic City, NJ, March 9, 1981.

J. M. Brown-Thomas, "The Analysis of Phenols in Water by High-Performance

Liquid Chromatography," 1981 Pittsburgh Conference on Analytical Chemistry

and Applied Spectroscopy, Atlantic City, NJ, March 10, 1981.

R. M. Parris, "Analysis of Polychlorinated Biphenyls in Waste and Lubricating

Oils," 1981 Pittsburgh Conference on Analytical Chemistry and Applied

Spectroscopy, Atlantic City, NJ, March 10, 1981.

W. E. May, "Analysis of Polycyclic Aromatic Hydrocarbons in Water: Standards

Methods or Standard Reference Materials," 1981 Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Atlantic City, NJ, March 12,

1981. Invited

D. J. Reeder, "An Overview of Analytical Chemistry and Immunoassay at the

National Bureau of Standards," Chemistry Department, North Texas State

University, Denton, TX, March 16, 1981. Invited

W. E. May, "Analysis of Selected Organics in Alternate Fuels Using Multidimensional HPLC Techniques," Perkin-Elmer Corporation, Norwalk, CT,

April 21, 1981. Invited

S. A. Wise, "Analytical Methods for Polycyclic Aromatic Hydrocarbons in Air

Particulates," EPA National Symposium on Monitoring Hazardous Organic

Pollutants in Air, Raleigh, NC, April 30, 1981. Invited

S. A. Wise, "The Determination of Polycyclic Aromatic Hydrocarbons by HighPerformance Liquid Chromatography," Department of Chemistry, University

of Oslo, Oslo, Norway, May 14, 1981. Invited

S. A. Wise, "Trace Organic Analysis at the National Bureau of Standards,"

Department of Chemistry, University of Oslo, Oslo, Norway, May 14, 1981.

Invited

S. A. Wise, "The Determination of Polycyclic Aromatic Hydrocarbons by HighPerformance Liquid Chromatography," Central Institute for Industrial

Research, Oslo, Norway, May 15, 1981. Invited

S. A. Wise, "Certification Analysis of Environmental Standard Reference

Materials," Colloquium for Chemie and Okologische Chemie, Technische

Universitat Weinhenstephan, Weinhenstephan, Germany, May 18, 1981.

Invited

S. A. Wise, "Organic Analysis in the NBS Pilot Environmental Specimen Bank

Program," Annual Environmental Specimen Banking Meeting sponsored by U.S.

EPA and Umwel tbundesamt of Federal Republic of Germany, Kernforschungsanlage (Nuclear Research Center)KFA, Julich, Germany, May 20, 1981. f Invited
S. A. Wise, "Mussel Sampling, Storage, and Analysis for the Pilot Environmental Specimen Bank - Current Status," Annual Environmental Specimen

Banking Meeting sponsored by U.S. EPA and Umweltbundesamt of Federal

Republic of Germany, Kernforschungsanlage (Nuclear Research Center)KFA,

Jiilich, Germany, May 20, 1981. Invited

M. J. Welch, "The Certification of Organic Analytes in a Human Serum Standard

Reference Material by ID/MS," American Society for Mass Spectrometry 29th

Annual Conference on Mass Spectrometry and Allied Topics, Minneapolis,

MN, May 26, 1981.

L. R. Hilpert, "Analysis of Phenolic and Polynuclear Aromatic Hydrocarbon

Species in Alternate Fuels and Effluents," American Society for Mass

Spectrometry 29th Annual Conference on Mass Spectrometry and Allied

Topics, Minneapolis, MN, May 28, 1981.

R. Espinosa-Leniz, "A Method for the Mass Calibration of Photoplates in Field

Desorption and Its Application to Some Peptides," American Society for

Mass Spectrometry 29th Annual Conference on Mass Spectrometry and Allied

Topics, Minneapolis, MN, May 28, 1981.

E. A. Blubaugh, "Technetium Electrochemistry: Electrochemical Studies of

Arphos Complexes of Technetium in Nonaqueous Media," Naval Research

Laboratories, Washington, DC, July 6, 1981. Invited

E. A. Blubaugh, "Technetium Electrochemistry : Electrochemical Studies of

Arphos Complexes of Technetium in Nonaqueous Media," E. R. Squibb and

Sons, Inc., The Squibb Institute for Medical Research, New Brunswick, NJ,

Aug. 6, 1981. Invited

R. E. Botto, "High-Field Proton and Nitrogen-15 NMR Spectroscopy of Neomycin B,

New York, NY, Aug., 1981, with B. Coxon.

B. Coxon, "Two-Dimensional Proton NMR Spectroscopy of Hydroxyl Proton Coupled

a- and 8-G1 ucopyranoses at 400 MHz, New York, NY, Aug., 1981.

B. Coxon, "Structural Analysis of Fortimicin Antibiotics by Means of Proton

Coupled Nitrogen-15 NMR Spectra, New York, NY, Aug., 1981, with J. B. McAlpine.

R. M. Davidson, "Nitrogen-15 NMR and Mass Spectral Characterization of Some

Doubly 15N-Labeled ( 15 N 2 -) 2-Amino Oxazoline Derivatives of the Pentoses

and Hexoses," American Chemical Society Meeting, New York, NY, Aug. 26,

1981.

R. A. Durst, "Assessment of the Status of Spectroelectrochemistry," 31st

General Assembly of the International Union of Pure and Applied Chemistry

(IUPAC), Catholic University, Leuven, Belgium, Aug. 27, 1981. Invited

R. A. Durst, "The International Practical pH Scale," 31st General Assembly of

the International Union of Pure and Applied Chemistry (IUPAC), Catholic

University, Leuven, Belgium, Aug. 28, 1981. Invited

181
3. Committee Assignments

Harry S. Hertz

Chairman, ASMS, Committee on Education

Member, ASTM, Committee D19 on Water

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

Air Pollution Data and Monitoring Working Group, Task Group in

Anticipatory Monitoring

Board of Directors, NCCLS

Technical Advisor, OIML, SP26, Subcommittee Sr5 on Reference Materials

for Calibration of Instruments Meant for Checking Substances During

Medico-Biological and Research Analyses

Member, Program Advisory Committee, ACS, Division of Analytical Chemistry

Bruce Coxon

Secretary, ASTM, Subcommittee E13.07 on Nuclear Magnetic Resonance,

Committee El 3 on Molecular Spectroscopy

Associate Referee, International Commission for Uniform Methods of Sugar

Analysis, Subcommittee 5 on 100 °S Point of Sugar Scale

Referee, U.S. National Committee on Sugar Analysis, Subcommittee 5 on 100 °S Point of Sugar Scale

Richard A. Durst

Member, ASTM, Committee D19 on Water

Member, Department of the Interior, Office of Water Data Coordination,

Task Group 5 on Chemical and Physical Quality of Water and Sediments

Secretary, IFCC, Scientific Committee, Analytical Section, Expert Panel

on pH and Blood Gases

Member, Instrument Society of America, Subcommittee SP76.02 on Electrochemical Analyzers

Member, IUPAC, Committee V on Analytical Chemistry, Subcommittee 5 on Electroanalytical Chemistry

Member, NCCLS, Subcommittee on Electroanalytical Methods

Member, NCCLS, Subcommittee on pH and Blood Gases

Consultant on Electrochemistry , U.S. Army, Task Group on Medical Bioengineering R&D Laboratory

Barbara F. Howell

Alternate Councilor, ACS

Treasurer, ACS of Washington, DC

Member, ASTM, Committee E7 on Nondestructive Testing

Subcommittee E7.03 on Liquid Penetrant and Magnetic Particle

Task Group E07.03.02 on Magnetic Particle and Penetrant TestingPenetrant Method

Task Group E07.03.05 on Magnetic Particle and Penetrant Testing

Task Group E07.03.06 on Magnetic Particle Methods

Task Group E07.03.07 on Magnetic Particle and Penetrant TestingMagnetic Glossary

Willie E. May

Member, ASTM, Committee D19 on Water

President, Washington Chromatography Discussion Group

182
Dennis J. Reeder

Member, AACC

Study Group on Cortisol

Study Group on Total Serum Protein

Associate Member, IFCC, Expert Panel on Drug Effects in Clinical Chemistry

Chairman, NCCLS, Subcommittee on Specific Plasma Proteins

Member, NCCLS, Subcommittee on Total Protein

Robert Schaffer

Member, AACC, Committee on Standards

Subcommittee on Cholesterol

Subcommittee on Creatinine

Subcommittee on Electrolytes

Subcommittee on Glucose

Subcommittee on Iron

Subcommittee on Theophylline

Subcommittee on Urea

Subcommittee on Uric Acid

Member, NCCLS, Area Committee for Clinical Chemistry

Subcommittee on Calibration Reference and Control Materials

Subcommittee on Quantities and Units

Subcommittee on Reference Methods and Materials

Member, Council for National Reference System in Clinical Chemistry

4. Other

a. Seminars

October 9, 1980

October 23, 1980

October 28, 1980

December 17, 1980

February 12, 1981

February 19, 1981

Bruce Coxon and Robert E. Botto, National Bureau of

Standards, "NMR Experiments on the 400 MHz Instrument".

Alexander J. Fatiadi, National Bureau of Standards,

"Croconate Semiconductors".

Ronald L. Birke, City College of New York, "Surface

Enhanced Raman Spectroscopy".

Ronald L. Birke, City College of New York, "Diagnosis

of Electrode Kinetic Parameters by Differential Pulse

Polarography".

Mark Wrighton, Massachusetts Institute of Technology,

"Chemically Modified n-Type Semiconducting Silicon

Photoelectrodes".

Robert McKinney, National Institutes of Health,

"Containment and Safe Handling of Carcinogens and

Biological Hazards".

February 24, 1981 - George M. Frame, U.S. Coast Guard Research Development Center, "A Mobile Laboratory for Fast Response

to Spills".

183
March 5, 1981 Dennis J. Reeder, National Bureau of Standards,

"Immunoassay Procedures: FIA, EIA, ELISA, Etc".

March 13, 1981 - Milton L. Lee, Brigham Young University, "Recent

Advances in Capillary Chromatography".

April 15, 1981 William J. Sonnefeld and Franklin R. Guenther,

National Bureau of Standards, "Multidimensional

Chromatography".

May 14, 1981 - Stephen N. Chesler, National Bureau of Standards,

"Capabilities of the FTIR".

May 21, 1981 - Norbert Blanckaert, Katholieke Universiteit , Belgium,

"The Glucuronic Acid Conjugates of Bilirubin".

June 5, 1981 C. J. Porter, University College of Swansea, Great

Britain, "Consecutive and Charge Stripping Reactions

in Mass Spectrometry".

August 5, 1981 — Josef K. F. Huber, University of Vienna, Austria,

"Quantitative Analysis Using Multidimensional Chromatography" .

August 5, 1981 “ P. Ramachandra Naidu, Sri Venkatesware University,

India, "Chlorosulphonic Acid as a Titrant in Nonaqueous Media".

August 20, 1981 Robert M. Davidson, National Bureau of Standards,

"Nitrogen-15 NMR and Mass Spectral Characterization

of Some Doubly 15 N-Labeled ( 15 N 2 -) 2-Amino Oxazoline

Derivatives of the Pentoses and Hexoses".

September 17, 1981 - Marianne Grassl , Boehringer Mannheim Biochemicals,

Germany, "Quality Control of Biochemicals".

b. Conferences Sponsored

October 23-24, 1980 - S. A. Margolis, Workshop on Reference Materials for

Organic Nutrient Measurement, National Bureau of

Standards, Washington, DC.

c. Seminars Organized

H. S. Hertz, The Search for Zero, FDA Mass Spectrometry Symposium, Food and

Drug Administration, Washington, DC, October 15-17, 1980.

H. S. Hertz, Analytical Chemistry Sessions, 15th American Chemical Society

Middle Atlantic Regional Meeting, Washington, DC, January 7-9, 1981.

184
H. S. Hertz, EPA National Symposium on Monitoring Hazardous Organic Pollutants

in Air, Session IV -- Sampling and Analytical Techniques for Organic

Aerosols, Raleigh, NC, April 28 - May 1, 1981.

H. S. Hertz, and E. White V, Interpretation of Mass Spectra and Quantitative

Mass Spectrometry, sponsored by the American Society for Mass Spectrometry,

Minneapolis, MN, May 23-24, 1981.

d. SRM Certification

1) SRM 909, Human Serum

2) SRM 910, Sodium Pyruvate

3) SRM 938, 4-Nitrophenol

4) SRM 998, Angiotensin I (In Process)

5) SRM 1564, Indeno(l , 2, 3-cd) pyrene Generator Columns (In Process)

6) SRM 1581, Polychlorinated Biphenyls in Oil (In Process)

7) SRM 1590, Stabilized Wine

8) SRM 1595, Tripalmitin (In Process)

9) SRM 1599, Valproic Acid and Carbamazepine in Human Serum (In Process)

10) SRM 1644, Generator Columns for PAH in Water

11) SRM 1647, Polynuclear Aromatic Hydrocarbons in Acetonitrile

12) SRM 1649, Polynuclear Aromatic Hydrocarbons in Air Particulate

Matter (In Process)

13) SRM 1815a, n-Heptane (Engine Octane Number Standard)

185

IV. Gas and Particulate Science Division

Harry L. Rook, Chief

Raymond L. McKenzie, Deputy Chief

A. Division Overview

The Gas and Particulate Science Division develops new and improved

techniques for the measurement of chemical composition on a microscopic

scale and conducts research on measurement methods for gaseous molecules in

controlled mixtures and at trace atmospheric levels. The results of this

research are applied to NBS and other international standards programs and,

in selected areas, applied to high priority national problems as addressed

by other federal agencies and private industry. The Division's programs are carried out by five groups with scientific effort divided approximately

equally, .between gas analytical research and microanalytical research. The

group structure and personnel alignment are given in the Division organization chart.

During the past year, a number of major achievements have been realized.

The Microanalysis Research Group has made excellent progress in quantitative

compositional mapping. Using the electron microprobe, accurate twodimensional mapping has been demonstrated and applied to grain boundry migration studies. Changes in zinc-copper concentrations at boundry sites are clearly evident with micrometer resolution. Also a substantial improvement

has been made in the elemental ratio technique using the ion microprobe.

Accurate depth distributions of arsenic in silicon have been demonstrated.

Other significant outputs include: the development of the first set of

test thin film standards for analytical electron microscopy and laser microprobe mass analyzer (LAMMA) studies; the determination of scaling factors

leading to quantitative laser Raman microanalysis on selected samples; the

development of accurate expressions for atomic number and energy dependence

of x-ray bremsstrahlung; investigations into the effects of crystal orientation in quantitative secondary ion microscopy; and investigations into ion

yield mechanisms in the laser excitation process of LAMMA.

In x-ray fluorescence the group has completed the development of a comprehensive set of interelement corrections to improve the accuracy of

energy-dispersive x-ray spectrometric analysis. These, coupled with an improved line overlap correction procedure, have significantly improved the

accuracy of self-consistent compositional calculations of XRF data.

In the area of gas measurement and analytical research, a major achievement during the past year was the completion of the infrared diode laser

photometer. A procedure has been developed for the direct analysis of trace

levels of N 2 0 using the new system. The diode laser results have been

compared to results obtained by electron capture gas chromatography with

good agreement. This successful utilization of two independent analytical

methods to obtain accurate gas mixture concentrations represents a significant

advance from the current practice of basing gas mixture composition on gravimetric formulation data. This measurement achievement will have significant

impact on the measurement of reactive gaseous species in contained mixtures

187
and in the atmosphere. A second laser photometric technique using optoacoustic signal detection has also been used successfully to determine low

concentrations of N02 in the presence of high concentrations of NO and

nitrogen. This work was vital to the analytical certification process of

N02 gas SRM's. Finally, the first comprehensive determination of the ozone cross sections from 240 to 340 nm at low temperature has been completed.

These data are being used to revise model calculations of ozone cross sections at stratospheric temperatures for use with SBUV satellite ozone monitoring of the earth's atmosphere.

As in past years, the Division has been a major contributor to the NBS

SRM program both in research leading to new standards and in the analytical

certification process of current SRM's. Over 4000 individual samples of more

than 100 different SRM's have been analyzed for SRM certification this year.

The future research directions of the Division may be classified into

two general areas. The first is research to improve quantitative microanalytical techniques and methods and to apply those improvements to

compositional mapping and particle analysis. The second is research to

improve techniques for the accurate analysis of gaseous species in contained

mixtures or under atmospheric conditions.

The research directions in microanalysis have been strongly influenced

by the equipment-intensive nature of the field. Durinq the past few years,

the Division has acquired an assemblage of state-of-the-art microanalytical

instrumentation not available at any other single research establishment in

the world. At the same time, a small but highly motivated group of research

analytical chemists with experience in complementary areas of microanal vsis are establishing the foundation for exciting research in new analytical areas that include: three dimensional compositional mapping; automated imaging of

particles by elemental or isotopic composition; multi parameter analysis of

individual particles using two or more microanalytical techniques with data

correlation done under computer control; and the accumulation and reduction

of very large multielement data sets derived from arrays of particulate

material or from predetermined arrays in two or three dimensional space. In

order to build on the research in the above areas, efforts will be made to

reassign some Division personnel and to selectively add staff in key areas.

The future directions in gas analytical research have been influenced by numerous personnel changes during the past year. Key research scientists in

both the Gas Metrology Group and the Atmospheric Chemistry Group have left

the Division as a result of the NBS reduction in force or attrition. However, a firm committment to improve qas measurement techniques remains as the

basis of research planning. It is important to note that contained gas

mixture standards can still be compounded by gravimetry far more accurately

than present analytical techniques can measure them. Research on gas analytical techniques which have the potential of definitive accuracy and high

precision has been initiated and will be continued. Optical photometric

techniques using ultraviolet, visible, and infrared radiation are showing

great promise. Research on gas chromatographic detection theory and response

characteristics will also be pursued.

188
A new research program will be started next year in interfacial stability

and surface reactions as they affect gas mixture stability. Initial research

will be conducted on oxides of nitrogen. Surface studies will include model

as well as real materials. A complete material balance will be attempted to

account for losses of gas species of interest.

In summary, the potential for excellent research in gas analysis and in

microanalysis must be exploited by present research personnel in the near

term and a dedicated management effort must be made to identify key positions

which must be filled in the longer term.

1 . Microanalysis Research Group: Overview

The Microanalysis Research Group conducts research to advance the

development and application of microanalysis techniques for the chemical,

crystallographic , and morphological characterization of matter on a micrometer scale of spatial resolution. The techniques utilized include electron

probe x-ray analysis, scanning electron microscopy, electron diffraction,

electron energy loss spectrometry, secondary ion mass spectrometry, microRaman spectroscopy, and laser microprobe mass analysis. Research is conducted

on several aspects of each technique including: (1) advancing understanding

of the basic physics of the primary excitation and secondary radiation

attenuation; (2) developing methods of quantitation; (3) developing standards;

and (4) applying results of the research to developing improved compositional

mapping techniques and to interface with other selected problems.

A major highlight of the past year has been the expansion of the

instrumentation and support facilities of the Microanalysis Research Group.

This expansion has been achieved through a combination of initiation of

activities in the NBS competence building program on Compositional Mapping

and other agency support. The Group now has available a wide range of

state-of-the-art microprobe instrumentation, employing primary beams of

electrons, ions, or photons and detecting as analytical signals the x-rays,

ions, or scattered photons produced during interaction with the sample.

During FY81 , the Group received the first laser microprobe mass analyzer

(LAMMA) in North America (described below) and has arranged for the procurement of a Cameca IMS-3F ion microscope, an advanced secondary ion mass spectrometer. To aid in the development of compositional mapping techniques,

a powerful DEC VAX super-mini computer has been obtained and will be augmented

with an image processing peripheral which is currently being procured. To

ensure that the central processing computer is not overburdened by instrument

control functions, the major microprobe instruments (ion microprobe, electron

probe microanalyzer, laser microprobe mass analyzer, laser Raman microprobe,

and analytical electron microscope) have been individually automated through

the use of small minicomputers, which together with the central computer will

comprise the Microanalysis Data Collection and Processing System (MADCAPS).

The eventual goal of this system is to provide the capability for the

preparation of analytical compositional maps in two and possibly three

dimensions, with the further possibility of merging information from two or more techniques to improve the overall characterization of the sample.

189
The development of lateral and depth compositional mapping depends, of

course, on the development of reliable methods of quantitative analysis at

point locations. Consequently, Group activities have included: (1) the

development of trial materials to serve as thin film standards for analytical

electron microscopy and laser microprobe mass analysis; (2) the investigation

of working curves for the quantitative analysis of inorganic compounds by

laser Raman microanalysis; (3) the continuing investigation of accurate

expressions for the atomic number and beam energy dependence of the x-ray

bremsstrahlung ; (4) investigation of crystallographic effects on secondary

ion yield in the ion microprobe; and (5) investigation of the parameters

which control the ion yield in laser microprobe mass analysis.

The development of candidate materials to serve as thin film standards

for analytical electron microscopy and laser microprobe mass analysis

represents another step in the Group's efforts to produce "high technology

standards" in response to the new analytical techniques which have recently

evolved. Previous developments in this series include the Research Material

Microanalysis Glasses, Fine Glass Fibers, and Spherical Glass Particles. The new thin films mark the first time we have attempted to develop a material

which can be characterized both with regard to composition and dimensions; we

seek to provide a known quantity of atoms in a defined volume. We expect

that these thin film standards may find uses in techniques other than AEM and

LAMMA, especially when combined with the bulk glasses, fibers, and microspheres to provide a wide range of geometrical shapes with which to test and

develop instrumentation and analytical techniques.

Finally, a component of the Group's research has been devoted to applications of analysis in support of research activities of other Centers at NBS

and other federal agencies including: (1) investigation of rapidly solidified

alloys (CNIR); (2) analysis of stratospheric aerosols (NASA); (3) analysis

of foreign debris in human tissue (FDA); (4) study of dopant redistribution

during laser annealing of semiconductors (CEE); (5) preparation of trial

standards for asbestos mineral analyses (EPA); and (6) studies of the

mechanisms of grain boundary migration (CMR).

Future research plans of the group are strongly influenced by the

competence program in compositional mapping and plans for new high technology

standards. Plans for the coming year include continued research on three

dimensional compositional mapping, mul ti parameter analysis of arrays of

individual particles, research on automated immage analysis, and continued

research on their film standards.

Dale E. Newbury, Group Leader; Adville A. Bell, Edgar S. Etz, Inga I. Holl,

Ryna B. Marinenko, Robert L. Myklebust, Patrick J. Sheridan, David S. Simons,

John A. Small, Eric B. Steel, Barbara B. Thorne

190
2. X-Ray Fluorescence Spectrometry Group: Overview

The X-Ray Fluorescence Spectrometry Group conducts research in sample

preparation including preconcentration methodology applied to a wide range

of sample types, develops new techniques for instrument calibration and

standardization, develops data reduction procedures for quantitative x-ray

analysis, and conducts certification analyses on a wide variety of NBS

Standard Reference Materials.

In 1981, the X-Ray Fluorescence Spectrometry Group devoted a major

effort to completing EXFNBS — a comprehensive interelement correction and

x-ray line overlap computer program for energy-dispersive x-ray spectrometric

analysis. We have performed alloy analyses using EXFNBS and compared the

results obtained with another fundamental parameter program and the RasberryHeinrich method. A technical paper describing this intercomparison has been

submitted for publication. In addition, an overview of EXFNBS will also be

published. A major portion of our work consists of the quantitative analysis

and homogeneity testing of renewal SRM's. During this year we have characterized a number of alloy SRM's with our automated wavelength-dispersive

spectrometer.

Next year we plan to investigate the use of toroidal monochromators in

energy-dispersive spectrometry to improve detection limits for ultratrace

analytical applications, and to install our recently purchased data acquisition system for processing x-ray spectral data.

Peter A. Pella, Group Leader; Feng Ling-Yuan, Anthony A. Marlow,

John S. Sieber

3. Atmospheric Chemistry Group: Overview

The Atmospheric Chemistry Group conducts research on measurement techniques for molecular species at ambient concentrations. This research

includes the determination of fundamental constants required for spectroscopic measurements, molecular cross sections, line intensities, and improved

trace radioactive gas measurements. The results of this research are applied

to the development of improved techniques for trace and ultratrace gas

measurement.

Major accomplishments this year in the area of spectroscopy include:

(1) the determination of the temperature dependence of the ozone absorption

cross-section in the Hartley and Huggin Bands (240 to 340 nm) at 298 K and

243 K; (2) the calibration of the Fourier transform infrared spectrometer

(FT-IR) and its application to the first reported determinations of the band

intensities of HN02 and N 2 0 3 ; (3) continued detailed intercomparison of 0 3 , NO, and N02 measurement standards by gas phase titration; and (4) use of

optoacoustic spectroscopy to provide a primary calibration of an N02 -to-N0

converter used for SRM calibration measurements in a cooperative study with

the Gas Metrology Group.

191
A major computer modeling study has been completed this year to evaluate

47 potential chemical reactions occuring in ozone generation systems as a result of impurities in "clean air" sources. The relative levels of

interfering products and competing reactions with respect to gas phase

titration measurements of 0 3 , NO, and N02 have been evaluated.

In the area of nuclear environmental chemistry, significant activities

during the past year have included: (1) analysis of environmental samples

obtained from Russia, the Shenandoah Valley, and Houston to determine the

relative proportions of contemporary and fossil carbon in order to establish

the sources of the samples; (2) research to develop microchemical techniques

of sample preparation for Accelerator Mass Spectrometry measurements of

microgram size samples; and (3) the organization of a Symposium (ACS, Houston,

1980) on Nuclear and Chemical Dating Techniques (by Dr. Lloyd Currie).

The major emphases next year will be (1) the continued application of

optoacoustic and related spectroscopic techniques and of the FT-IR with a long-path cell for the measurement of trace-level atmospheric molecular

species, (2) the application of Accelerator Mass Spectrometry for the

determination of carbon isotopic ratios in microgram-size samples, and

(3) the development of mathematical methods for accurate low-level signal

extraction from high backgrounds and for modeling of complex chemical

composition matrices from environmental -study data bases.

Raymond L. McKenzie, Acting Group Leader; Arnold M. Bass, Ilan S. Chabay,

Lloyd A. Currie, Alan Fried, Robert Gerlach, George A. Klouda, James E. Norris,

Gerald B. Tompkins, Robert Continetti

4. Gas Metrology Group: Overview

The primary responsibility of the Gas Metrology Group continues to be

the development and production of standard reference gases for all areas of

science and technology where accuracy in gas measurement is required either

by legislative mandate or necessity. Thus the group performs two major

functions — the development of Standard Reference Materials (SRM's) and the

performance of the research essential for the characterization of gas standards. In addition, a limited gas analysis service, utilizing the unique

capabilities of the group, is provided to other groups at NBS and to other

government agencies.

Research in the group has resulted in the development of high accuracy

standards for the measurement of atmospheric concentration of nitrous oxide

(^300 ppb). Development of standards for measurement of atmospheric con- centrations of several halocarbons is progressing and work has begun on development of measurement techniques and standards for carbonyl sulfide, an important trace sulfur compound in the atmosphere.

A laser-diode spectroscopic technique has been developed to the point

where comparative measurements of nitrous oxide can be made by this technique

and gas chromatography using electron capture detection. The successful

utilization of the two techniques is essential for the assessment of the

accuracy of the nitrous oxide measurements. Standards for benzene and

192
perch! oroethylene at environmentally significant concentrations have been

developed and their accuracy and stability have been studied. Standards

consisting of both gas mixtures in cylinders and in permeation tubes have

been evaluated.

Additional work has been done on high accuracy standards for measurement

of atmospheric carbon dioxide. Final analysis of the potential SRM's will

begin after delivery and evaluation of a state-of-the-art non-dispersive

infrared analyzer.

As in the past, a major output of the group has been the analysis and

certification of gaseous SRM's. Over 3,000 individual samples have been

analyzed during the past year. In addition, 95 gaseous SRM's sold by the

Office of Standard Reference Materials have been returned by users for

reanalysis as part of a continuing study of stability. Four new SRM's have

been issued during FY 81.

The development of the Certified Reference Material Program has been

completed and CRM's are available from at least two commercial gas suppliers.

The document outlining the program has been published in a joint NBS/EPA

Special Publication. The current protocol describes the preparation of

carbon monoxide in air or nitrogen, and nitric oxide in nitrogen CRM's.

Documents concerning other gases are in preparation.

Service analyses performed by the group include an attempt to prepare

and analyze samples containing 36 Ar and 40 Ar in an atmospheric matrix

approximating that of the planet Venus. The mixture is needed to resolve a discrepancy between results of analyses made by investigations in the

United States and Russia. The group continues to be involved in international

evaluations of gas standards both through participation in international

standards organizations and through cooperative analyses between various

countries.

Future research plans of the Gas Metrology Group include: (1) continued

research in laser infrared photometry as an accurate, sensitive analytical

technique for gaseous molecules with large IR cross sections; (2) research on the theory and response characteristics of electron capture detectors used in

gas chromatography; and (3) initiation of a new research effort in interfacial stability and surface enhanced reactions as they relate to gas mixture

stability.

Ernest G. Hughes, Group Leader; William F. Cuthrell, William D. Dorko,

James W. Elkins, Rudolph V. Kelly, Gerald D. Mitchell, Richard C. Myers,

George C. Rhoderick, William P. Schmidt, Gerald A. Sleater, James E. Suddueth

193
5. Particle Research Group: Overview

The main objectives of the Particle Research Group are the development

of particle generation techniques, and the characterization and improvement

of particle measurement and collection techniques. Our research closely

parallels some aspects of the Microanalytical Research Group efforts although

our major emphases this year have been in the areas of particle sampling and

in-situ measurement techniques.

A major accomplishment this year has been the completion of the design,

construction, and complete wind tunnel testing and evaluation of the Personal

Ambient Aerosol Sampler (PAAS). Two units of the PAAS have been sent to

groups interested in evaluating it in field studies (the EPA and Harvard

University School of Public Health). The work has been presented in whole or

in part at three meetings during the year and we have already received

requests for the papers describing the PAAS from both national and foreign

environmental and occupational health scientists. The PAAS was designed and

has been demonstrated to collect both the inhalable and the respirable

fractions of particles from an air sample and to have a sampling cut-point

(particle size discrimination) that follows that recommended by the AEC.

It is wind-velocity and direction insensitive for indoor and mild outdoor

conditions. The high sampling rate that has been achieved (6 L/min) has

resulted in high interest by many researchers.

The group participated in an intercomparison study of several Aitken

nuclei and cloud condensation nuclei counters during the International Cloud

Condensation Nuclei Workshop (October 6-17, 1980, Reno, Nevada). A result of

this work was the characterization and critical intercomparison and evaluation

of the performance parameters of several Aitken counters which have been informally used as "standard" counters. This intercomparison has provided a clearer

understanding of the conditions under which one may expect the particular

instruments to measure Aitken nuclei concentrations accurately and of the

subtle pitfalls that may be encountered in using these instruments naively.

A third effort this year has been the preparation and initial characterization of Mi n-U-Si 1 5 as a candidate material for the production of a Respirable a-Quartz SRM. We have made particle size distribution studies of

the material to verify that it is in the respirable range and are coordinating

the other aspects of the certification measurements (including x-ray diffraction, infrared absorption, and thermogravimetry).

Finally, in collaboration with the Atmospheric Chemistry Research Group,

we have made wind tunnel tests of air velocity and relative directional

effects on the sampling efficiency and properties of gaseous pollutant

personal samplers. We have developed gas generation and dispersion techniques

for introducing sample gases into the tunnel and have characterized the

resulting gas concentration profiles in the tunnel. We subsequently initiated

a study of the sampling efficiency of the Palmes-tube NO 2 sampler as a function of wind speed and direction.

194
The Particle Research Group plans to initiate several new research areas

next year in collaboration with other groups in the Division, the CAC, and

the Center for Fire Research. These include: (1) development of particulates

and thin films (of deposited particles) of known chemical composition as standards for microanalytical techniques; (2) characterization of the size

and chemical distribution of particles resulting from spark discharge

techniques for transport of materials from bulk samples to various plasma

and flame spectroscopic analytical instruments; and (3) measurement of the

formation and growth of gas or vapor/aerosol systems to test modeling

experiments of smoke and related aerosol systems (i.e., the homogeneous and

heterogeneous nucleation and subsequent growth of particles by condensation

from the vapor phase).

Raymond L. McKenzie, Group Leader; David S. Bright, Robert A. Fletcher

195
B. Selected Technical Accomplishments

(Gas and Particulate Science Division)

1 . Development of a Monte Carlo Electron Trajectory Simulation

Monte Carlo electron trajectory simulation techniques have proven to be

powerful tools for the study of electron interactions in solids [1]. Monte

Carlo techniques have been applied to problems in scanning electron microscopy

and electron x-ray microanalysis and, more recently, to the newly developed

microanalytical method of analytical electron microscopy [1-3]. The Microanalysis Research Group has worked on the development and implementation of

Monte Carlo techniques for microanalysis studies for several years [1,2, 4, 5].

During this time, frequent requests have been received from the microanalysis

community for a Monte Carlo simulation which can be implemented by users on

small laboratory computers. This year we have developed such a Monte Carlo

simulation for distribution which incorporates a number of calculations of

interest in microanalysis and we are making this computer program available

to the community [6].

The simulation is of the single scattering type and is based upon the

relativistic screened Rutherford elastic scattering cross section for the

calculation of the mean free path between scattering sites and the elastic

scattering angles. The Bethe continuous energy loss relation is used to

account for inelastic scattering. The Bethe cross section for inner shell

ionization is employed for x-ray calculations, with the constants in the cross section selectable among those due to Powell, Mott and Massey, Green

and Cosslett, and others. The parameters calculated include the electron

backscatter and transmission coefficients, the depth and lateral x-ray

generation distributions, and the x-ray depth distribution corrected for

absorption within the sample.

Two examples of x-ray distribution functions obtained by the Monte Carlo

simulation technique are shown in figures 42 and 43. The variation of the

shape of the depth-distribution curves can be interpreted in terms of the

increased scattering power of the high atomic number targets. The simulation

can be applied to the problem of examining interelement effects, particularly

absorption, in thin foils. This scattering and absorption information is

needed for the development of advanced quantitation methods for analytical

electron microscopy.

References

[1] Heinrich, K. S. J.; Newbury, D. E.; Yakowitz, H. , Eds., Use of

Monte Carlo Calculations in Electron Probe Microanalysis and

Scanning Electron Microscopy. NBS Special Publication 460; 1975.

[2] Newbury, D. E. ; Myklebust, R. L. Monte Carlo Electron

Trajectory Simulation of Beam Spreading in Thin Foil Targets.

Ultramicroscopy. 3: 391-395; 1979.

196
[3] Kyser, D. F. "Monte Carlo Simulation in Analytical Electron

Microscopy" in Introduction to Analytical Electron Microscopy,

ed. J. J. Hren, J. I. Goldstein, and D. C. Joy (Plenum, 1979)

199-221.

[4] Yakowitz, H. ; Newbury, D. E.; Myklebust, R. L. "Approaches to

Particulate Analysis in the SEM with the Aid of a Monte Carlo

Program". Scanning Electron Microscopy (1975), 93-102.

[5] Newbury, D. E.; Myklebust, R. L.; Heinrich, K. F. J. "A Hybrid

Monte Carlo Procedure Employing Single and Multiple Scattering"

in Eighth Int'l. cong. X-Ray Optics and Microanalysis , ed.

D. Beaman, R. Oglivie, and D. Wittry, (Pendell, Ann Arbor, Mich.

1980), 57-62.

[6] Newbury, D. E.; Myklebust, R. L. "A Monte Carlo Electron Trajec

tory Simulation for Analytical Electron Microscopy", Analytical

Electron Microscopy III, (in press).

D. E. Newbury, R. L. Myklebust

Figure 42. X-ray depth distribution functions

for targets of various thicknesses.

197
Figure 43. X-ray depth distribution functions for

copper at various beam energies.

2. Empirical Quantitation in Raman Microprobe Analysis

Research has been initiated to quantitate micro-Raman scattering data

from solid phase microsamples. The quantitative interpretation of the Raman

spectra of microparticles is a difficult problem owing to the complexities of

the underlying scattering phenomena and the difficulties of the experiment

itself [1 ,2]

.

Theoretical treatments of inelastic scattering (Raman and fluorescence)

theory [3] predict that the scattered intensities from microparticles are affected by (i) the geometrical (e.g., size and shape) and optical (e.g.,

refractive index) properties, (ii) the distribution of active molecules

within the particle, (iii) the angular distribution of scattered light and

polarization effects, and (iv) a number of instrumental factors. These same theories point out that the processes of inelastic scattering and optical

absorption are closely related and postulate resonances in the Raman spectra

of particles with perfect geometries (e.g., dielectric spheres and cylinders).

Thus, while present theoretical understanding rests entirely on model calculations for isolated particles of perfect size and shape and ideal optical

properties, an extension of these principles to particles that do not fit

these models is not easily made and accounts for the lack of progress in

quanti tation

.

We have evaluated the results of empirical approaches to quantitation

and have assumed that, in a first approximation, the relationships for

quantitation in macro-Raman spectroscopy [4] can be extended to micro-Raman

198
5

l|

scattering. That is, the scattered intensity from microscopic particles will

be found to be proportional to the concentration of the species which generates

the Raman band. Based on this premise, we have examined empirical quantitation by means of working curves, establishing detection sensitivities for

inorganic species (and organic compounds) in simple solid matrices. The

scattering systems investigated have ranged in optical /spectral complexity

from samples transparent to the exciting radiation to solid phases nearly

opaque to the incident laser beam. Observations to date suggest that the

quantitative aspects of micro-Raman scattering may be tractable for a broad

range of microsamples.

The solid phase matrix presently under intensive study is the carbonateapatite system, of great relevance to biological mineralization [5,6]. In

this area, our studies are directed at the determination of carbonate contents

in vertebrate tissues of bone and tooth, work performed in collaboration with

the American Dental Association Health Foundation, Research Unit at the NBS,

and workers at the Children's Hospital Medical Center of Harvard Medical

School

.

The organic matrices of bone and dentin constitute approximately 30

percent of their respective dry weights. A solid inorganic mineral phase of

which hydroxyapatite, Ca 10 (P04 ) 6 (0H) 2 , in the final form contributes the

remaining 70 percent dry weight. Bulk chemical analysis of mineralized

tissue shows a carbonate (C0 3 2 ") content varying with age from 1.4 percent to

6.2 percent in mature chick bone. The principal tissues examined are samples

of bone and tooth, studied as powders and thin sections. To quantify the

carbonate contents in these matrices, a series of synthetically prepared

carbonate apatites have been obtained as standards, with C0 3 2 ” contents

varying from ^1.5 to ^20 weight percent. The molecular groupings in these

solids give rise to characteristic Raman bands. The bands with Raman shifts of

M)61 cm" 1 (v x mode, P04

3 ”) and ^1074 cm" 1 (v l9 C0 3 2 ’) were selected as the

analytical bands. Carbonate-to-phosphate intensity ratios were obtained from

the spectra of these standards taking into account the spectral "background"

at each analytical frequency. This procedure yields a calibration curve from

which the composition of the mineral phase can be determined. Typical

spectra from these studies are shown in figure 44. Comparison of the two

spectra from mature chick bone and a 4.3 weight percent carbonate apatite

standard indicates that the method of relative intensity measurements yields_

quantifiable data for this system. The calculated values for the C0 3 2 /P04

3 " intensity ratio are 0.19 for both the bone sample and the carbonate apatite

standard, after background corrections. The exact trend over the composition

range of interest has not been fully established, although a linear relationship with concentration is indicated.

Future research efforts will have the objective of experimental

verification of the predications made by the scattering theories for small

particles. Also of importance will be the development and characterization

of micro-Raman "standards" that have well-defined geometry, known composition, homogeneity, and are stable under laser irradiation. These data will

then result in the development of the required empirical correction procedures.

199
1000

2000

Figure 44. Raman microprobe spectra of single particles of (a) fully

matured chick bone (powder) and (b) synthetic carbonate

apatite.

References

[1] Rosasco, G. J. Raman Microprobe Spectroscopy, in Advances in

Infrared and Raman Spectroscopy, R. J. H. Clark and R. E. Hester,

eds. Heyden & Son, Ltd., London, Vol. 7 (1980) 223-282.

[2] Etz, E. S.; Blaha, J. J. Scope and Limitations of Single Particle

Analysis by Raman Microprobe Spectroscopy, in Characterization of

Particles. NBS Spec. Pub! . 533, 1980, 153-197.

[3] Kerker, M.; Druger, S. D. Raman and Fluorescent Scattering by

Molecules Embedded in Spheres. Appl . Opt. 18: 1192; 1979.

[4] Irish, D. E.; Chen, H. The Application of Raman Spectroscopy to

Chemical Analysis. Appl. Spectrosc. 25: 1; 1971.

200

INTENSITY

(counts)
[5] Casciani, F. S.; Etz, E. S.; Newbury, D. E.; Doty, S. B. Raman

Microprobe Studies of Two Mineralizing Tissues: Enamel of the Rat

Incisor and the Embryonic Chick Tibia, SEM/1 979/11, SEM, Inc., AMF

O'Hare, IL 60666, (1979), 383.

[6] Nishino, M.; Yamashita, S.; Aoba, T. ; Okazaki, M.; Moriwaki, Y. Laser-Raman Spectroscopic Studies on Human Enamel and CarbonateContaining Apatites. 0. Dent. Res. 60: 751; 1981.

E. S. Etz

3. Automation of the NBS Laser-Raman Microprobe

The NBS laser-Raman microprobe has been automated to increase its

research and analytical utility. A Digital Equipment Corporation MNC

DecLab-11 system has been interfaced to the laser-Raman microprobe and now controls many of the instrument functions as well as data acquisition. The

computer is a PDP-11/03 with 64 kilobytes of memory, dual 5 megabyte firm

disks, and a CRT console. The console serves both as the computer terminal

and as the display device for the spectral data. The computer is interfaced

through a series of plug-in modules as is shown in figure 45. Two 16-bit

digital input modules and three 16-bit digital output modules are used in

this system. One output module controls the stepping motors on the spectrometer and the strip-chart drive motor as well as the Burleigh dual PZT

translator stage to position the specimen. The output of the encoders on the

spectrometer is read by the computer through an input module. The second

input module reads the output from the SSR photon counter which is controlled

by the second output module. The third output module controls the Houston

Instruments Complot digital recorder. All signals in the system are digital

and no amplification outside the SSR photon counter is required.

The software consists of two parts: the first part initializes all of

the spectrometer functions, controls the system for data collection, and does

the data acquisition. The second part controls all of the data display,

consisting of the CRT graphics display and the digital plotter. Spectra may

be displayed and compared on the CRT terminal. Hard copies of the spectra

may be plotted on the digital plotter.

An important consequence of the automation of the system is the direct

spectral digitization for our micro-Raman spectral library. Plans are for

the future development of a file searching technique using peak location and

band intensity data for matching reference spectra with the spectra of

unknowns

.

J. J. Blaha, E. S. Etz, R. L. Myklebust

201
Disk

Storage

Figure 45. Schematic diagram of Laser-Raman microprobe data acquisition,

processing, and output computer interface.

4. Development of Standards for Single Particle Analysis of Fly Ash

Fly ash from coal-fired power plants is one of the major sources of

airborne particulate materials in the United States, accounting for approximately 25 percent of all anthropogenic particle emissions. The study of

the environmental impact of fly ash is essential, as well as the study of

its role as an industrial raw material.

Since the elemental composition of fly ash material varies from particle

to particle, it is necessary to quantitatively analyze individual fly ash

particles by microanalytical techniques as part of the total characterization

of the material. These individual analyses are then statistically grouped

and compared to bulk composition. The development of methods for and the

analyses of individual particles is dependent on developing well characterized

particle standards.

During the past several years the Microanalysis Group has been involved

in a cooperative program with the Inorganic Glass Group (Center for Materials

Research) to develop microanalytical measurement standards.

202
As part of this program, we have developed a surrogate fly ash consisting

of glass microspheres ranging from 0.5 pm to 250 pm in diameter. The microspheres are prepared by pumping an air suspension of finely ground glass

through a vertically mounted alumina tube. The tube is heated to the melting

point of the glass and the irregular particles are drawn into a special

shape by surface tension. After formation, the microspheres are air cooled

and collected on polycarbonate filters (figure 46).

Figure 46. Glass microspheres synthesized in forced draft furnace.

The composition of the parent glass used in the manufacture of the

synthetic fly ash is given in Table 29. This composition was selected to

simulate the elemental concentrations found in many types of fly ash

particles

.

In order to determine if there were any alterations in composition of

the microspheres as a result of the preparative (production) process, the

composition of the microspheres was compared to the bulk glass. For this

comparison the microspheres were cross-sectioned to minimize particle absorption, and polished to an optically flat surface. Table 30 lists the elemental

ratios for microspheres compared to bulk glass for 60 analyses on 15 crosssections. The ratios for all the elements are close to, but slightly less

than unity. This discrepancy can be attributed to a particle mass effect

which is the loss of x-ray intensity from the microspheres as a result of

electrons penetrating through the microspheres into the epoxy.

203
Table 29. Partial Compositions of Bulk Glass K-961

.

Weight Fraction

Element K-961

a

0 0.470

Na 0.030

Mg 0.030

A1 0.058

Si 0.299

p

b 0.002

K 0.025

Ti 0.012

Ca 0.036

Mn

b 0.003

Fe 0.035

a Composition based on constituents used to make the

bulk glass.

b

For K-961 the elements phosphorus and manganese

were not analyzed because of the low amounts of

these elements in the glass.

Table 30. Average Intensity Ratios to Bulk Glass for K--961 Microspheres.

Element Average

Standard

Deviation

Standard Deviation

of a Single

Determination

Poissonian

Standard Deviation

of a Single

Determination

Na 0.97 0.004 0.18 0.049

Mg 0.96 0.001 0.050 0.025

A1 0.96 Q. 0009 0.041 0.014

Si 0.98 0.0005 0.025 0.006

K 0.97 0.0009 0.039 0.019

Ca

a 0.98 0.0009 0.033 0.017

Ti 0.98 0.0009 0.042 0.026

Fe 0. 93 0.0009 0.042 0.026

a The potassium peak has been subtracted.

B
The results from the analyses of the microspheres indicate that, within

the uncertainties of the techniques used for sample preparation and analysis,

there is no alteration in composition due to the preparative process. These

microspheres are serving two important functions. First they are being used

as direct standards for semi-quantitative electron probe analysis of fly ash

particles. Secondly the spheres are being used to develop a general analytical correction procedure for the quantitative electron microprobe analyses

of individual particles.

J. A. Small

5. Development of a Candidate Thin Film Standard Reference Material

The development of advanced high spatial resolution analytical techniques

such as analytical electron microscopy (AEM) and laser microprobe mass analysis (LAMMA) which require samples in the form of thin films has placed

new demands on standards development. Standards of known composition are now required which are laterally homogeneous on a scale of nanometers and which

have a known and constant thickness on the order of 100 nm. To supply these

standards, we have investigated ion beam sputtering of glass targets to

produce films with suitable, constant properties [1]. Ion beam sputtering

has been previously utilized by the X-Ray Fluorescence Group to produce thin

film standards on filter material. For the new work, it has been necessary

to extend the procedure to produce standards which can be demonstrated to be

stable and homogeneous on a submicrometer spatial scale. A schematic of the

apparatus for the production of the films is shown in figure 47. The glass

target is sputtered with a beam of 1 keV Ar+ ions, and the sputtered material

is deposited on thin (20 nm) carbon films carried on copper or beryllium

grids. To improve the homogeneity, the substrates are mechanically rotated

relative to the source during glass deposition.

The initial test film which was produced had the nominal composition of

NBS SRM K-411 glass [MgO (15 wt. %); Si0 2 (55 wt. %); CaO (15 wt. %); FeO

(15 wt. %)]. Contaminants in the commercial sputtering apparatus used introduced aluminum and chlorine into the films, although this problem has been

eliminated in subsequent runs. Homogeneity was determined by electron probe

analysis with energy dispersive x-ray spectrometry. Figure 48 shows the

results for the ratio of iron to calcium. In this figure, the box represents

the range for 50 percent of the analyses, and the bars show the maximum

excursions. The standard deviations for the ratios of the various elements

to calcium were in the range ±3 percent relative. Moreover, this includes

even the chlorine contaminant, indicating the strong bonding formed during

the sputtering process. Thickness measurements by double-beam interferometry

and stylus profilometry revealed a constant thickness within ±20 percent

relative.

205
'www I Source Filament

Anode 1 1st Stage Accelerator

2nd

Flow Neutralizer

Collimator

Figure 47. Schematic of the ion sputtering apparatus.

GLASS FILM K411+

0.0 0.1 0.3 0.3 0.4 0.5 0.6 0.7

Figure 48. Diagram showing the variability in ratio of

Fe to Ca x-ray intensities for six samples

analyzed on the electron microprobe.

The results obtained so far on the homogeneity and stability of the

candidate materials suggests an excellent basis exists for the development

of a thin film standard reference material. Because sputtering does not

necessarily transfer the target composition faithfully to the film, it will

206
be necessary to analyze the sputtered films by independent techniques such as neutron activation and atomic absorption.

Reference

[1] Steel, E. B. ; Newbury, D. E. ; Pella, P. A. "Preparation of Thin

Film Glass Standards for Analytical Electron Microscopy" to be

published in Proc. 3rd Workshop on Analytical Electron Microscopy.

E. B. Steel, D. E. Newbury, P. A. Pella

6. Intercomparison of NRLXRF Semi-Empirical and NBS Interelement

Correction Methods

Proper corrections for interelement effects in quantitative x-ray

fluorescence spectrometry are a major factor in obtaining accurate compositional data. Various semi-empirical approaches to obtaining correction

factors have been published. A widely used approach which combines the use of

influence coefficients and fundamental parameters was developed by the Naval

Research Laboratory. This program, called NRLXRF [1], allows the user to

select from three analysis schemes. These are called "Empirical", "Full",

and "Theoretical" and their selection will depend upon which standards are available. The purpose of the NBS work was to compare the results obtained

with each of the three options in NRLXRF and to check for consistency in the

results by intercomparison with another semi -empirical model such as RasberryHeinrich [2] and an NBS fundamental parameter method EXFNBS [3]. The samples

chosen for the intercomparison consisted of a series of wel 1 -characterized

alloys analyzed for Fe, Ni , and Cr.

The results obtained with the Rasberry-Heinrich method and the Empirical

option of NRLXRF are summarized in Table 31. The Empirical option of NRLXRF

uses a form of the Lachance-Traill equation and a weighted least-squares

procedure which emphasizes the standards whose composition are most like the

unknown specimens. Comparison of the results in Table 31 indicate that these

procedures are comparable for samples 5054, 5364, and 5202 where the relative

error is 1.1 to 1.5 percent. These procedures give optimum results when the

total composition of the analyte is determined or accounted for as in the case

of the ternaries where the sum of the constituents equal 98 percent or better.

For alloys like NBS-SRM 1188, however, 5 percent of the total elemental

composition consists of the elements Ti, A1 , Si, and Nb. If this sample is

treated as a ternary only, the relative error increases to 3-3.5 percent, as shown in the table. The Empirical option in NRLXRF contains a provision for

adjusting the weight fractions of the analytes for the presence of known

concentrations of elements in the unknown specimen. Entering the known weight

fractions of Ti, A1 , Si, and Nb for 1188 and then treating the sample as a ternary reduces the relative error to 1.2 percent. Similar improvements in

the results could be made with the Rasberry-Heinrich method if influence

coefficients are included in the analysis scheme for Ti, A1 , Si, and Nb.

207
Table 31. Comparison of Rasberry-Heinrich and NRLXRF (Empirical Option).

Call concentrations are in weight percent)

Specimen

I.D. Chem. R-H

a

R. E. dR-H

b

R.E.

d

Emp.

c R.E.d

Iron

5054 72.50 72.29 -0.29 72.71 0.29 73.07 0.79

5364 47.21 47.50 0.61 47.56 0.74 47.32 0.23

5202 63.03 62.77 -0.41 62.84 -0.30 62.96 -0.11

1 188

e 6.60 6.55 -0.76 6.05 -8.3 6.21 -5.9

1 188

f 6.60 - - - - 6.74 2.1

Nickel

5054 0.150 0.15 0.0 0.16 6.7 0.16 6.7

5364 23.57 24.09 2.2 23.71 0.59 23.68 0.47

5202 14.80 15.07 1.8 14.73 -0.47 14.78 -0.14

1 188

e 72.65 72.36 -0.4 72.11 -0.74 73.98 1.8

1 1 88

f 72.65 - - - - 72.88 0.3

Chromium

5054 25.77 25.22 2.13 26.00 0.89 25.38 -1.5

5364 27.84 26.75 3.9 27.49 -1.3 27.78 -0.22

5202 21 .30 20.90 1.9 21.17 -0.61 21 .27 -0.14

<d 00 CO 1 15.40 14.21 -7.7 15.36 -0.26 14.95 -2.9

1188f 15.40 - - - - 15.21 -1.2

Specimens

Data Summary, Average Relative Error in Percent

5054, 5364, 52Q2 1.5 1.3 1.1

CD COCO i

3.0 3.1 3.5

1188' — 1.2

l R-H = data from Rasberry and Heinrich £3].

} R-H = this work (Cr target 50 kV, 10 mA, and g

NRLXRF (empirical option).

FeNi

= -0.70).

'Emp.

*R.E. = Relative error, percent = 0BS ~ x 100.

e

l 1 88 = Treated as a ternary and analyzed for Fe, Cr, and Ni only.

f

1188 = Analyzed for Fe, Ni , and Cr, however, the known concentrations

of the unanalyzed elements were included.

208
The results of analyses on the same set of standards for the NRLXRF

Full and Theoretical options and EXFNBS are presented in Table 32. These

results are also consistent with those presented in Table 31 where the

average relative error was 1.3-1. 5 percent. Using only pure element standards for calibration (i.e., Theoretical option in NRLXRF), the relative

errors were 3.6 percent for NRLXRF and 2.2 percent for EXFNBS. The slightly

better values obtained with EXFNBS are probably due to the use of a very

efficient exciter (e.g., Zn) for Fe, Ni, and Cr in which case the effect of

secondary and tertiary fluorescence effects are minimized.

References

[1] Birks, L. S. ; Gilfrich, J. V.; Criss, J. W. "NRLXRF, a FORTRAN

Program for X-Ray Fluorescence Analysis," X-Ray Optics Branch,

Material Sciences Division, Naval Research Lab., Washington,

D. C. 1977. (COSMIC) Suite 112, Barrow Hall, Athens, Georgia

30602, Prog. No. D0D-Q0065, (July 1977 version).

[2] Rasberry, S. D.; Heinrich, K. F. J. Anal. Chem. 46: 81; 1974.

[3] Myklebust, R. L.; Pella, P. A.; Thorne, B. (to be published in

X-Ray Spectrom).

P. A. Pella, J. R. Sieber

209
Table

32.

Analysis

with

NRLXRF

and

EXFNBS

(all

concentrations

are

in

weight

percent)

• CD CM J—

LlJ O O CM

• • • • • • Cd o o o i— CM

I I II

00

"CT o CO CO

-M LO o o CO

CO • • • . CM CO CO o • r^- CO

</ ; J •Xj

r— CT) 00 00 LO CO CO

CO 00 CO o CO •— CM

r- r- CO <3* LO *

t

iii CMi i i i

LO s

LO CO Is'- *3- cn CO LO r— o • • • • • . • CO LO CO CO cn CM LO CM n— CM CM CM i

i— i— co

i— r^. co o o o i—

i i i i

co o CT) co co <3- co <—

00 T T T

CO CO CO O O CO CO r- CO

u

LO TO CO CO CT) LO

*3- o LO CT) p^ CM O p-

+-> o CM •sj- co r— CT) O LO CM LO

OO • • • • . • • • • « • • CO co CO o co LO co LO 00 i— LO <

<=3" co CM 1 CM CM CM r—

. LO o CM i

1 UJ 1^ *3- O CO 1CO

• c • . m • CL) •

1' oz o 1

o 1 LO CO

s~ 1 1 o 1—

1 1—

1

•r- 1

1 z

1 -O o • p^ CM CT) p»

1 o p^ O CO CT) i

CL) . . • • .

1 JZ. CO p^ CM CO o

1 1— p*. CO

1

ti_. co CT) 00

QC LlJ co o i

1

p«. X » » . . •

1 cc o O CO CO

cc i + 1 + +

fO CO CO , , LO

1

CO CO CT) 00 r—

(

’ • • • • • o r— CM CO o U- CO

m o CO o

oLO E LO CM o CO 1

<u • • • « i sz CM r^ CO CO o o r- CO

c

a)E • •Cp ^P CM 00 3-

<- Q LO CO O 00 LO U • O CO CM o CL) »—

t

Q.

LO LO LO LO

oo

co E CT) , co LO p- o 00 =3 O CM co LO

• • • •f— • • • • CO p-» o E

O

S- E<_>

1 O CM1 CM CO

^3" LO LO *3" p» r—

1

CO O O 00 00

• • • • • t 0 LO LO CM CO p-» P— LO

CM r— P-. CM CM CM r—

CM r— CT) CO CM LO CO

CO LO CM CO 00 CO LO d d d O O d CM , + i 1 1 + + +

P-. r— CM r— CO 00 p-— CO p^ CM IX CT) CO

0 . 0 * 0 • 0 CO >3- CM LO p. r— LO CM i

P-* CM CM CM

s-o

ssp>. o LO p. O o aj LO 00 CO r^. 00 CO

• • • • * • • a> CO CM LO ip 1

LO >

CM r^. CM CM CM •r—

+-> fO

aj

scu CM 00 «?P *=3" CM 00 CT) CO O CO LO CO O 00 fT3 CO CM r— o CO CM r— s- LO LO r~ LO LO LO r— oj>< (O O -O

210

Full

option

using

all

ternary

standards

plus

SRM

1189.

'Theoretical

option

using

pure

elements

only

for

calibration.

All

ternary

standards

plus

SRM

1189

used.

'pure

elements

only

used

for

calibration.
7. Measurement of the Temperature Dependence of the Ozone Absorption

Cross-Sections in the Ultraviolet

Work has continued on the determination of temperature dependence of the

ozone ultraviolet absorption cross-sections. The ultraviolet photometer was described in last years report to the panel and is functioning as planned.

The goal of this project is to determine the ozone cross-sections over a range of wavelengths and temperatures that are of particular concern in

stratospheric measurements and modeling. Thus we propose to record the

spectrum over the wavelength range 200 to 700 nm and over the range of temperatures 200 to 300 K. We have now completed measurements over the region of

the Hartley and Huggins Bands (240 to 340 nm) at two temperatures (298 K and

243 K). These measurements have been made in steps of 0.05 nm with a spectral

resolution of approximately 0.02 nm. Several scans were made of this region

of the spectrum. The consistency of the determinations between repeated

scans was very good. The uncertainty of the measured cross-sections, relative

to the cross-section at 254 nm, is estimated to be less than 2 percent.

Figure 49 displays the absorption spectrum between 345 and 260 nm. The

upper curve is for 295 K; the lower curve is for 243 K. Figure 50 shows the

region between 345 and 325 nm in greater detail. In both cases the plotted

curves represent the average of at least three individual scans through the

spectral range quoted.

The ratio of the cross-section at 243 K to that at 298 K is plotted as a function of wavelength in figure 51. The ratio values published previously

by Vigroux are indicated by the x's. The real and detailed structure of the

temperature coefficient as a function of wavelength is clealy displayed in

contrast to the very limited information previously available in the published

literature.

The value of these improved measurements has been demonstrated by two

research groups involved in the analysis of satellite observations of ozone

concentrations in the Earth's atmosphere. In one case, discrepancies of about

3.5 percent which were previously observed in comparisons between satellite

and ground-based measurements of ozone total column densities and of vertical

profiles were reduced to less than 1.5 percent by using the new cross-section

values.

In the second case, observation of backscattered radiation made from

Nimbus 7 displayed unidentified structure in the spectrum between 280 and

310 nm. This structure was initially attributed to sulfur dioxide (S0 2 ) and

implied a concentration of S02 of 200 ppb at 10 to 30 km, strongly in

conflict by four orders of magnitude with in situ measurements. By using our new ozone cross-section measurements it was shown that essentially all

of the spectral structure can now be accounted for by ozone.

We expect to complete the remainder of the measurements during FY 82.

A. M. Bass

211
T T ~r ~r ~r ~r

r | z

x

h 8 o

2

LU

_lLU>X

- 8

-8

0’81- S • 0

1 - 0-61- S • 6 1 - 0'02- S‘02- O' 12-

( WD ‘ OS ) N0I !O3S-SS0yO (01 1000

8

0* 23-

00

ISJ

CL) s-X

+J

03

s-CDQ.

E

<U +J4-O

+-> u

c

o 03 LU CO

i/) CO fO c\l CO o CO O)c cu o > CO CO eg Nl S- O 3

4-O

U

o s 2 c 2

o o Z QC QC

1— 1 +Jo o h*o

HO

CD

(/)

1 hQ.

DC

LU

a.CO

LU

Q.

CO

{/) too

s-u CD QC QC

III c CO

CQ

LU

CL

Q_

LU

|

ptio 298 < —

J

s-O Cl) t/i > LU XI S_ 03 3

z o

+J

a)o

s-<Da

a

> X)

nsi- +J

03

=x

a)

s~3

CX>

212
CR0SS-SECTI0N

(SQ.CM.

I

1

I

I

I

I

;

213
l^6Z/M£VZ) SNDI133S- S S D id 3 JO OUbd

o

s-cd

CO

CO

I CO

CO

CD

s

to 4-> C

<uE

a>

ito

03<D

s-CD

s.fC

ISI m

CO

00

cr>

C\J 4-> 03

aj

too

CO

Tf

<N co

S 5

o

4->

CO

•d" CvJ

fO

(Oco

•r—

-t-> 0

aito

1 to

toO X

s-U -O

CD 4— -X O S-03 O E

+-> CD

fO S- q; 03

LO

a)

s-13CD

214
8. Measurement of Infrared Intensities of Atmospheric Species

Over the last seyeral years there have been increased efforts in the

atmospheric science community to model the atmosphere. The goal is to obtain

accurate measurements of both concentration profiles of most atmospheric

constituents, and the temperature profile of the atmosphere. The purpose of

these measurements is to predict the response of the ozone layer to changes

in concentrations of other constituents, to understand the role of the

atmosphere's composition as it effects climate, and to monitor pollution.

Many of these studies employ infrared techniques to make atmospheric measurements, and therefore must rely on laboratory measurements of band intensities

and line parameters to interpret the data. We have a program, in collaboration with personnel of the NBS Molecular Spectroscopy Division (CCP) to

provide accurate infrared band intensity and line parameter measurements to

fulfill the needs of the atmospheric science community and also to provide

data for the preparation of gas standards.

For these measurements we employed a Fourier transform infrared spectrometer (FT-IR) with 0.01 cm" 1 resolution for band strength measurements and a diode laser spectrometer (DLS) with M3.003 cm” 1 resolution for line parameter

measurements. We made three series Of measurements with the FT-IR specifically

to calibrate it for intensity measurements. These are the NO fundamental band,

the N 2 0 V! band and the 0CS band. In Table 33, our values are compared to

values obtained by DSL and by a conventional grating spectrometer in the case

of NO. The agreement in all three cases is to within a few percent and well

within the estimated uncertainties of the comparison values. From this

comparison we estimate the systematic error to be less than 5 percent.

215
Table 33. Comparison of FT-IR Band Strength Measurements with

Literature Values.

NBS FT-IR Value

for

Band Strength, S Comparison Value, S

Band System of 296 °K of 296 °K

-2 -1 -2 1 (cm atm~ ) (cm atm~ )

References for

Comparison Values

N2O v-j 224.9 ± 1.6

a 219 ± 11^ (DSL) A. G. Maki and R. H. Kagann

to be published

OCS v-j 35.49 ± 0.80 35.4 ± 1.6 (DSL) V. M. Devi, P. P. Das,

A. Bano, and K. M. Rao

J. Mol. Spec. 87, 578

(1981).

NO v = l«-0 113.6 ± 1.2 112 ±6 (Grating) L. L. Abels and J. H. Shaw

J. Mol. Spec. 20t, 11 (1966).

The uncertainties listed in this column are 95% confidence limits (using

student ± distribution) on the random error (the scatter in the Beer's law

plot). The systematic error is not included here but is estimated not to

exceed ^5%.

bThe uncertainties listed in this column include a contribution from the

estimated systematic error.

After calibrating our FT-IR, we measured selected band strengths of the

following atmospheric species: N 2 0, N02 , OCS, HN02 , and N 2 0 3

. The results

of these measurements are shown in Table 34. The uncertainties include

contributions from the estimated systematic error of 5 percent and from

random error in the data. The measurements of HN02 and N2 0 3 were made in

equilibrium systems where both species were minor components. No direct

measurements of the partial pressures were possible, so the pressures were calculated using literature values for the appropriate equilibrium constants.

This and the fact that the two species were present in the equilibrium

mixtures in small concentrations (^0.5 torr for HN0 2 and 0.1 torr for N 2 03 ) account for the high uncertainties in the measurement of these two species.

These are the first known measurements of infrared absorption intensities of

HN02 and N 2 0 3.

The data from the N02 measurements are presently being analyzed and we have just begun measurements of Freon 11 and plan to make measurements of

Freon 12.

R. H. Kagann

216
Table 34. FT-IR Measurements of Band Strengths and Band Positions.

Band Strength, S

Band System Band Center at 296 K

-1 -2 -1

(cm ) (cm atm )

NO 1+0 1876 113.6 + 5.8

n

2 o 589 28.9 + 1.5

2v° 1168 8.28 + 0.46

V

1 1285 225 + 11

3v’, Q 1749 0.0235 + 0.0088

v -| +v

2

»

Q

1880 0.254 + 0.015

v

l +v 2’ sys1- em 1880 0.583 + 0.085

? v-|+2v

2 -v2

, Q 1886 0.0348 + 0.0059

v

3

2224 1421 + 92

V2v0

2462 7.32 + 0.39

2v, 2563 32.1 + 1 .7

v

2 +v3

2798 2.25 + 0.21

2v

2 +v3

3364 2.21 + 0.19

Vv

3

3481 46.8 + 2.5

2v^ +2v> 23749 0.702 + 0.093

3v

i 3836 1.86 + 0.67

2v

3

4417 1.53 + 0.37

217
Table 34 continued.

Band Strength, S

Band System Band Center

(cm

-1

)

at

(cm

-2

296 K atnT^

)

OCS \) i 858 35.5 + 1 .9

1044 13.35 + 0.78

2vi 1711 6.71 + 0.44

v++2

2 1893 10.91 + 0.69

v 3

2062 2984 + 177

V2+V3 2575 0.0596 + 0.0064

vi +V3 2918 33.6 + 1.9

^? + V 2 V 3

3095 2.26 + 0.14

2V3 4102 17.9 + 1.7

cis-hno

2 V4 852 960 + 140

v 2 1640 1250 + 240

2V2 3257 30 + 5

^1 3427 69 + 20

Trans-HN0

2 V 4

790 563 + 82

v 3

1263 699 + 86

VZ 1699 704 + 81

( 2v 3 or v2+

\>4 2 ) 2493 25 + 6

2v2 3372 37 + 6

V 1 3590 246 + 29

N 2°3 V

1 1302 1180 + 180

V

1 1829 1302 + 180

218
9. Continuation of the Intercomparison of 0 3 , NO, and N0 2 Measurement Standards by Gas Phase Titration

In our research summary presented last year, intercomparison of ozone

(0 3 ), nitric oxide (NO), and nitrogen dioxide (N02 ) measurement standards

using the rapid bimolecular reaction

NO(excess) + 0^ = N0

2 + 02

,

was discussed in detail. In these studies, NO was titrated by incremental

additions of 0 3. The concentration of NO reacted, A (NO) as measured by

chemiluminescence and calibrated by NO Standard Reference Material (SRM)

cylinders, was compared with UV photometric measurements of the 0 3 concentration added, a( 0 3 ). Preliminary measurements of the N0 2 concentration

generated during the course of this reaction, A(N02 ), were also made. This was accomplished utilizing an N02 optoacoustic detection system calibrated

by permeation tube standards. In this method of detection, N0 2 is measured

directly without an interfering response from NO, thus eliminating con- siderable measurement uncertainty inherent in the more traditional chemiluminescent measurements of N02

. The data obtained from the three independent

measurements revealed excellent agreement between the A ( NO ) and the A(N02 ) concentrations determinations, while the A(0 3 ) concentration values averaged

3 to 4 percent lower.

During the past year we have continued the study of these intercomparisons. A more extensive set of A(N0), A(N02 ), and A(0 3 ) measurements confirm

our previously reported results. These data were fitted using a linear

regression. However, since the uncertainties in all three determinations are comparable in magnitude, a weighted regression was employed using an iterative

technique described by Derek York; the residuals in both the ordinate and

abscissa were simultaneously minimized, in contrast to ordinary least-squares

data treatment. The following relations were thus generated:

A(0

3 )u V ppm = ± 0-005] A ( N°)g rav -[0.003 ± 0.004], (56 data pairs)

A(N0

2

) perm. tube ppm = 11 - 006 1 °* 007] A ^ N0)

grav.

- [0 ' 004 1 °- 005] ’

(22 data pairs.

The agreement between A(N0) and a(N02 ) verifies the reaction stoichiometry

.

In an attempt to identify the source of the 3.6 percent bias found in the

(0 3 ) measurements, other reactions have been considered which cause the

° uv oxidation of NO to N02 without consuming 0 3

. The most obvious,

2 NO + 0

2 + 2 N02

,

accounts for only approximately 0.2 percent, as both measured and calculated

in this study. An alternative set of reactions also considered involves the

chemistry of impurities in the "clean air" source used in the generation of

219
O 3

. Impurities such as N 2 0, CH4 , CO, and C0 2 have been measured at ambient

concentrations. In addition, water vapor concentrations ranging from approximately 10 ppm to a few hundred ppm have also been measured. The chemistry

of these impurities centers around the production of the OH radical in the

03 generator which subsequently generates CH 3 0 2 and H0 2 radicals, both of

which are known to react very rapidly with NO to produce N02

. Fourty-seven

reactions involving these impurities were studied by computer modeling our

gas phase titration (GPT) experiments using typical flow and concentration

conditions. Details of this model will be described in the following

research summary. The computer routine used in this analysis was developed

by Robert Brown of the Center for Chemical Physics. At the relative

humidities measured in these experiments, the results from the modeling

indicate a maximum increase in ANO relative to A0 3 on the order of a few

tenths of one percent, much too low to account for the observed discrepancy

of 3.6 percent. Relative humidities as high as 50 percent would be required

to generate a 2 percent discrepancy in these species. We are, however,

continuing to study the air stream source for, as of yet, undetected

impurities which may effect the oxidation of NO to N02

. We have also found

that those species known to be present in the air source, as well as those

reactive and stable end products predicted by the model, are not major

interferences in the UV absorption measurements of 0 3 at 253.7 nm.

In addition to the chemistry of impurities just described, we were also

concerned about trace impurities in the air stream reacting directly with 0 3 , which because of the split flow stream arrangement could potentially yield

lower 0 3 concentrations during measurement. A series of GPT experiments were therefore carried out using a different flow scheme. The 0 3 source, reaction,

and mixing chambers were replaced by two larger glass vessels, a 1-1 iter

reactor followed by a 2-liter mixing chamber. Ozone was introduced into the

system by passing the ozonized air stream from the NBS 3-meter UV photometer

directly into the reaction chamber. Not only did we eliminate the split flow

stream in this manner, but it also enabled us to make simultaneous 0 3 and NO

measurements, thus eliminating a possible source of error due to lamp fluctuations in the 03 source during the time between titration and 0 3 measurement.

This arrangement also enabled us to eliminate the necessity of the Das i bi

transfer standard along with questions concerning the use of a different air source in the calibration and GPT phases. The results of these experiments

using high purity air with water vapor concentrations less than 3 ppm and

total hydrocarbon concentrations as CH4 less than 0.1 ppm are very similar to

previous GPT runs; the ANO concentrations as measured by chemiluminescence

and calibrated by gravimetrical ly prepared standards ranged from 3 to 5 percent

higher than the corresponding A0 3 concentrations as measured by UV photometry.

In future studies, we will continue to investigate air stream impurities

by computer modeling, gas chromatography , and long path Fourier Transform

Infrared Spectroscopy. This last technique will also be used in conjunction

with a new and improved UV photometer to measure 0 3 concentrations in gas

phase titrations.

A. Fried, J. A. Hodgeson

220
10. Studies of the Photochemistry of Trace Airstream Impurities in

Ozone Generators

In our studies intercomparing measurement standards by gas phase titration(GPT), we became concerned with chemical reactions that potentially

could effect the oxidation of NO to N02 without consuming 0 3 and hence

account for the observed stoichiometry:

ANO = AN0

2 > A0

3

In these studies, 0 3 was produced by a conventional photolytic generator in

which 02 flowing through a quartz tube was photolyzed by UV radiation from a low pressure mercury lamp in accordance with the following reactions:

0

2 + hv (a < 2424 A) = 2 0 ( 3

p) (

1

)

0 ( 3

p) + 0

2 + M = 0

3 + M, M = N

2

, 0

2

( 2 )

0

3 + hv (A < 4000 A) = 0 (

] D) + 0

2 (3)

In the absence of impurities in the 0 3 generator airstream, reaction (3), the

photolysis of 0 3 in the generator, will simply regenerate 0 3

. However,

impurities such as N 2 0, CH 4 , CO, C02 at ambient concentrations and H 2 0 vapor

ranging from 10 ppm to a few hundred ppm have been measured in cylinder air

used in the generation of 0 3

.

Such findings prompted us to initiate an investigation into the photochemistry of these impurities. A set of 47 reactions involving these

impurities was simultaneously introduced, along with appropriate rate

constants, into a computer routine for solving systems of chemical rate

equations (developed by Robert Brown of the Center for Chemical Physics).

In addition to reactions (1-3) detailed above, some of the other important

reactions in the 0 3 generator considered in this model were:

0(7 D) + H

2 0

= 2 OH (4)

o(’d) + N

2

0

= 2 NO (5)

0 (

1 D) + CH

4

= CH

3 + OH ( 6 )

o(’d) + 0

3

= 2 0

2 (7)

0(

1 D) + H

2 = OH + H (8)

OH + 0

3

= ho

2 + o2 (S)

OH + ch

4

= CH

3 + h

2 0 ( 10 )

OH + H

2 = H + H2 0 (ID

OH + CO = H + C0

2

( 12 )

H + 0

2 + Pi = H0

2 + M (13)

221
CH

3 + 0

2 + M - CH

3

0

2 + M (14)

ho

2 + °3 = OH + 20

2 (15)

Terminating Reactions

OH + OH = h

2 o2 (16)

OH + ho

2 = h

2 o + o

2 (17)

ho

2 + H0

2 = h

2 0

2 + 0

2 (18)

The generation of the reactive radical, 0( 1 D), via the photolysis of 0 3 in reaction (3) is a critical step in this reaction sequence. Unfortunately,

the rate constant for this reaction, k 3 , is dependent on the radiation flux

of the 1849 A and 2537 h mercury lines reaching the quartz photolysis tube,

and is unique to every lamp and 03 generator. Factors such as the separation

between the lamp and the photolysis tube, the lamp temperature and voltage,

the build-up of 03 concentrations surrounding the lamp and the reflectivity of

the 0 3 generator housing will all affect the 0 3 photolysis rate constant. In an effort to obtain an accurate value for this parameter, we measured the

percentage loss of 0 3 , (A[0 3 ]/[0 3 ] )xl00, as measured by a Dasibi UV photometer,

by the addition of 775 ppm H 2 0 upstream of the 0 3 generator. Water added

downstream of the 0 3 generator had no affect on the Dasibi readings, thus

insuring that any observed changes were in fact due to photochemistry. The

photolysis rate constant, k 3 , was determined by fitting the observed 0 3 loss,

4.3 percent, to the model in an iterative fashion. The resulting value of

k 3 , 0.125 s

1

, is within a factor of three of the value obtained by lamp

flux estimates, 0.049 s" 1

.

Additional experiments were performed in which the loss of 0 3 was measured by the addition of other concentrations of H 2 0 vapor. These data are shown in figure 52 for two different initial 0 3 concentrations — 1.27 ppm

and 1.02 ppm. The computed profiles using the value of k 3 determined above

are shown by the solid and dashed lines for the two different 0 3 concentrations, respectively, and are in excellent agreement with the observed profiles.

Such agreement strongly suggests that our model accurately describes the

photochemi stry occuring in our 0 3 generator. Because of significantly larger

uncertainties in the other experimentally determined 0 3 losses, a refined

determination of k 3 from a fit of all the data points was not justified.

In order to incorporate the previous results in a complete computer

simulation of our GPT experiments, two additional computer runs were necessary.*

First, the concentrations of the various species at the output of the .0$

generator were put back into the computer model with all photolysis rates set

to zero. This step represents the decay of the photolysis products during the

transit time between the 0 3 generator and the nitric oxide (NO) reaction

chamber. Second, the concentrations generated in the previous step were put

back into the model along with the addition of pertinent reactions involving

NO. This step simulates the reaction sequence occurring during gas phase

ti tration.

222
Figure 52. Predicted vs. observed 0 3 losses for two initial 0 3 concentrations.

Points are the observed values, lines are predicted values.

223
While this analysis is not quite complete at this time, preliminary

analysis using a limited set of reactions indicates that relative humidities

as high as 50 percent would be required to generate a 2 percent increase in

ANO relative to A0 3 , as measured by UV photometry. The preliminary results

also reveal a second important point, namely the existence of stable reaction

products such as CH3 00H, CH 2 0, HN0 3 , HN0 2 , and H 2 0 2 in the GPT sampling

manifold. The presence of this last species is especially significant, since

its existence has been speculated in GPT experiments employing KI determinations of 0 3 in the presence of humidified air. In such cases, the generated

H 2 02 would be a positive interference in the 0 3 determinations, and could

possibly account for rather large positive biases found in previous KI determinations of 0 3

.

A. Fried, J. Hodgeson

1 1 . Determination of Trace Gas Concentration by Infrared Tunable Diode

Laser and Fourier Transform Infrared Spectroscopic Techniques

The demand for extremely sensitive analytical methods of measuring trace

gas concentrations has resulted in the use of gas chromatography (GC) coupled

with specific detectors, like the electron capture (ECD) and the flame photometric (FPD) detectors. These detectors are convenient and reliable at the

high parts-per-mil lion (ppm) level, however both detectors are generally

unpredictable and non-linear at the ultra-trace levels (ppb, parts-perbillion, and ppt, parts-per-trillion). Alternative methods for measuring

nitrous oxide (N2 0) and halocarbon F-ll (CC1 3 F) at ambient levels have been

surveyed, and two equally promising methods of infrared absorption spectroscopy have been investigated. One method uses a small tunable diode laser

(TDL) as a source and provides resolution (0.0004 cm' 1

) many times greater

than the Doppler width of an absorption line, low analysis time (milliseconds), and excellent reproduciabi 1 ity of sample analysis (±0.3 percent,

relative standard deviation, RSD). The second method uses a Fourier Infrared

Spectrometer (FT-IR) and provides wide coverage of the infrared spectrum

with lower resolution (0.06 cm' 1

) of absorption lines, accurate frequency

determination of absorption lines, and reproducibility of a few percent.

Many more infrared absorbing gases can be measured within the same analysis

with the FT-IR than with the TDL.

The greatest potential advantage of infrared techniques over conventional

methods is that the spectroscopic technique allows both direct and comparative

measurement of concentration in gas standards. Radiation at frequency v passing through an absorbing gas at partial pressure, p in a sample cell of

length, z, is absorbed according to the Beer-Lambert Law,

I(v) = I exp {-k(v)p£},

where k(v) is the absorption coefficient and I is the baseline intensity.

Therefore, one can determine gas concentrationairectly from prior knowledge

of the absorption coefficient. Comparative measurements are possible by

placing the gas sample in a cell and comparing its absorption to those

generated by standards. Relative concentrations measurements at the ppm

(by mole fraction) and the ppb levels have been made in this laboratory.

224
The determination of the absorption coefficient is crucial for the direct

measurement of gas concentration by either the FI-IR or the TDL spectrometer.

We have recently completed work on the measurement of the band strength by

FT-IR of the major vibrational bands for halocarbon F- 11 ( CC1 3 F) . The

strongest band, v4 (centered at 846 cm" 1 ), was investigated because it is

situated in the "atmospheric window". Constituents of the earth's atmosphere

do not absorb reradiated infrared radiation from the surface in this region

of the electromagnetic spectrum whereas F-ll and other trace gases do absorb

in this window and thus may be important to the radiation budget of the

earth. Nine measurements were made of the integrated absorbance using the

FT-IR for samples of F-ll at partial pressures between 64 and 400 pascals

(0.4 and 400 torr respectively) in one and two cm long cells. A plot of the

integrated absorbance (base 10, /A 10 dv) versus the pressure-pathlength

product graphically displays agreement with Beer's law (figure 53). The

slope of the line in figure_53 is equal to the band intensity, S, and this

line yields 18.04 ± 0.10 cm

2 K Pa” 1 (1828 ± 10 cm" 2 atm" 1

) for the v4 -band.

Therefore, gas concentrations can be calculated from knowledge of S, the

integrated absorbance, and the length of the cell.

We have recently conducted a test of our diode laser absorption spectrometer system to determine the imprecision values for comparative measurements

of samples from a set of gravimetric standards of nitrous oxide in air at the

ppm level. The results of this test are shown in Table 35. The gravimetric

concentration represents the value of N 2 0 in a cylinder based on gravimetry

where the theoretical inaccuracy in weighing is less than 1 part in 10,000.

The measured values refer to the average of several determinations based on the amount predicted from a linear function derived by a least squares fit of

a calibration curve of the expected concentration versus the measured peak

area. The relative difference, A percent, is the difference between the

diode laser value and the gravimetric value divided by the gravimetric value,

expressed in percent. The current imprecision for replicate samples is

between ±0.1 and 0.3 percent (RSD).

Table 35. Diode Laser Measurement for PPM N

2

O Standards

Sample No.

Measured

Concentration

Gravimetric

Concentration A °l

1 241.4 241 .3 +0.04

2 319.6 319.4 +0.05

3 337.0 337.5 -0.14

4 376.8 376.5 +0.07

5 488.4 488.4 0.00

6 523.6 524.8 -0.23

7 550.0 548.1 +0.34

8 591.9 592.6 -0.11

225
PRESSURE PATHLENGTH PRODUCT

Figure 53. Band strength determination of v4 band of CC1 3 F.

Our experimental goal is to measure concentrations of infrared absorbing

gases at the ppb level with imprecisions of ±0.1 percent, the current limit

of the best chromatographic results. The diode laser measurements in Table 35 were made in a 15.5 cm absorption cell at a pressure of 1.2 k pascals (9 torr).

For N 2 0, these measurements were not as accurate as those of electron capture — gas chromatography (EC-GC) at the ppm concentration level. However, we believe that if we use a 40 m total path white cell and if we can maintain

the same signal to noise ratios as with the 15.5 cm long cell, then the diode

laser may be useful for the determinations of ppb-levels of N 2 0, comparable

to those by EC-GC.

226
The FT-IR spectrometer will be used to complement the high resolution

capability of the tunable diode laser. We plan to add a white cell to the

present FT-IR spectrometer for trace measurement of infrared absorbing gases.

The FT-IR system will allow identification of species and lines of interest.

Once absorbing species are identified, the tunable diode laser spectrometer

will permit discrimination from possible interfering lines and measurement of

gas concentrations with inaccuracies of less than ±0.3 percent.

J. W. Elkins, R. H. Kagann, R. L. Sams

12 . Development of Ambient Nitrous Oxide and Halocarbon Standards

Concern has arisen during the past decade that possible increases of

nitrous oxide (N 2 0) and certain halocarbons may influence the equilibrium

concentration of stratospheric ozone and consequently the radiative budget

of the earth. Theoretical models which may be used to predict ozone concentration changes and radiative losses and/or gains require accurate measurement

of the spatial and temporal concentrations of N 2 0 and certain halocarbons at

low altitude to set boundary conditions for equations describing mass transport

of these gases into the stratosphere. A number of recent laboratory intercomparisons have shown that variations in concentration values of greater than

10 percent were found for identical standards of ambient air with N 2 0,

halocarbon-1 1

( CC1 3 F ) , and halocarbon-12 (CC1 2 F 2 ) when analyzed by a number

of different laboratories.

This report describes work in progress under a three year study jointly

sponsored by the National Aeronautics and Space Administration (NASA) and NBS.

The primary products of this investigation are the development of Standard

Reference Materials (SRM's) of ambient N 2 0 (250-350 ppb) , and halocarbons

F-ll (50-250 ppt) and F-12 (100-400 ppt). The concentration ranges represent

the lowest levels at which any gas standards will have been certified as SRM's. Preparation of nitrous oxide standards is nearing completion and work

is progressing on the preparation of the halocarbon standards. An important

milestone was accomplished in the verification of our nitrous oxide standards

using two independent analytical methods.

A series of primary laboratory standards for N2 0 have been prepared.

These standards were used as the basis for a series of measurements made to

answer questions concerning the current controversy on the value for the

absolute concentration of N 2 0 in the earth's lower atmosphere. Our original

intercomparison work [1], led us to conclude that a bimodal distribution

existed in the assumed concentration of N 2 0 standards used by various laboratories which participated in the study. Indeed, the scientific literature

currently contains values for atmospheric N 2 0 which may be divided into two

distinct groups; one at approximately 300 and one at approximately 330 ppb.

In the present work, gas standards were prepared by a gravimetric technique and were measured to establish the absolute concentration of N 2 0 in the

atmosphere. This measurement is important to our effort, because the value

will determine the concentration range of the N 2 0 Standard Reference Materials

(SRM's) which will be prepared and analyzed in the near future. In the

gravimetric technique, the component and balance gases are weighed separately

227
before and after addition to a cylinder. We prepare standards routinely by

this method with accuracies of better than ±0.1 percent for dilution ratios

of component gas to balance gas of 1:5000. Two dilution steps are required

to prepare N 2 0 gas standards near atmospheric concentrations, first to ppm

(parts-per-mil 1 ion) , and then to ppb levels.

A set of "parent-standards" of parts-per-mi 1 1 ion of N 2 0 in air were prepared and subsequently analyzed by intercomparison with each other by

gas chromatography (GC) using both electron-capture (EC) and ultrasonic (US)

detectors. The parent-standard concentration values were chosen to be

approximately the square root of the expected concentration value for

atmospheric N 2 0, so that identical pressures could be used in the two stages

of dilution. The parent-standards were verified by comparing the amount

predicted from a linear least squares fit of the expected concentration

versus the measured peak area. The relationship indicated both by EC-GC and

US-GC was essentially linear over the concentration range between 480 and

600 ppm, with typical values of the squared linear correlation coefficient

(r 2

) between 0.9995 and 1.0000. The relative difference between the gravimetric and the average measured concentration of each standard was less than

±0.1 percent.

The degree of linearity of the response versus the gravimetric concentration values from EC-GC and US-GC and the low uncertainty values for replicate

samples of the parent standards were supporting evidence that the gas

standards were prepared correctly. This evidence gave increased confidence

for preparing subsequent standards in the following dilution step.

The second stage of dilution to ppb levels required the construction of

a welded stainless-steel manifold with metal bellows valves for the transfer

of the individual gases into the cylinder. The high sensitivity of the EC-GC

allowed ultra-trace analysis of these standards. The gravimetric determinations were again verified by comparing the amount predicted from a linear

least squares fit of the expected concentration versus the measured peak

areas.

Samples of atmospheric air were collected by first evacuating a 2.3 liter

electropolished stainless steel cannister fitted with a metal bellows vacuum

valve to a pressure less than 0.13 Pascal (1 micrometer of Hg) in the laboratory, and then drawing the air sample by condensation into the cannister by

opening the valve while the cannister was surrounded by liquid nitrogen.

This procedure reduced contamination and provided an adequate sample for

replicate analysis. The cannisters were analyzed by EC-GC after the water

vapor had been eliminated by passing the sample through a P 2 0 5 filter. The

average concentration of N 2 0 in samples taken during the Spring of 1981 was found to be 299.8 ± 1.4 ppb (Is) for 21 samples measured. Therefore, the

NBS certified standards for l\| 2 0 will be centered around 300 ppb.

Our N 2 0 standards at the ppb level were intercompared with three

cylinders analyzed by R. F. Weiss at Scripp's Institution of Oceanography

(SI0). Weiss measures atmospheric N 2 0 by comparing the ratio of the observed

peaks in air due to C02 and N 2 0 using a modified US-GC procedure. The

absolute value of C02 is based on both the measurement of the C0 2 concentration made by C. D. Keeling (SI0) and on standards made by Weiss with fixed

228
N 2 0:C02 concentration ratios. The agreement between our method and SIO

indicates no difference greater than ±0.2 percent (see Table 36).

Table 36. Intercomparison of N2 0 Samples,

(ppb = parts-per-bi 1 lion by mole fraction)

Sample NBS Value

1 306.1 ± 1.0 ppb

2 302.9

3 294.1

Value Determined at SIO

305.8 ±1.0 ppb

303.0

293.4

The preparation of gas standards of halocarbon F-ll (CFC1 3 ) presents

problems somewhat different from those involved in the preparation of N 2 0

standards because F-ll exists as a liquid at room temperature. We have

recently developed a microgravimetric technique for preparing standards of

volatile liquids by weighing small quantities of the liquid contained in a capillary tube prior to its introduction into a gas cylinder. This method

allows the preparation of low-ppm concentration standards in a step dilution

with estimated inaccuracies of less than ±0.1 percent. Once the liquid is in

the gas phase, subsequent dilution to ppt-levels is possible by a technique

similar to that used for N 2 0.

We propose to intercompare our gas chromatographic measurements with

both diode and laser absorption and Fourier Transform Infrared measurements

of N 2 0, and halocarbons F-ll and F-12. These instruments will provide

independent methods to verify the concentration of the various constituents

in the gas standards.

Reference

[1] "Evaluation of Methodology for the Analysis of Halocarbons in

the Upper Atmosphere", NBSIR-78-1 480

.

J. W. Elkins, E. E. Hughes

13. Standards for Measuring Toxic Organic Vapors in the Workplace Atmosphere

The major effort in the toxic organic standards project in FY81 was the

preparation of primary gas cyclinder mixtures of a wide range of medium

molecular weight organic solvents, the determination of the stability with

time of these mixtures, the preparation and analysis of multi-component gas

mixtures, and the certification of both gas mixtures in cylinders and permeation tubes containing benzene and perchloroethylene as Standard Reference

Materials (SRM's). Major accomplishments were the development of a procedure

to prepare gravimetric gas mixtures containing organic solvents with high

vapor pressures, e.g., vinyl chloride monomer ( V CM ) and the completion of the

long-term stability studies of benzene and perchloroethylene gas mixtures.

229
Gas mixtures containing high vapor pressure organic solvents in a matrix

gas have been prepared gravimetrical ly using a modified capillary tube

technique. Instead of filling the weighing tube with liquid organic by differential pressure, the tube is cooled with dry ice to create a temperature

differential that draws the liquid into the tube. Gravimetric gas mixtures

containing vinyl chloride monomer in a nitrogen matrix have been produced at

concentration levels as low as 0.2 parts per million by mole (ppm) in a single

step dilution. A set of mixtures prepared by this procedure in the concentration range of 0.5 to 10 ppm was compared with a set of mixtures prepared by

the more laborious successive dilution method in the same concentration range.

The results of this comparison showed that both sets yielded the same average

FID response/concentration ratios but samples produced by the successive

dilution technique showed greater imprecision.

Accurate multi-component qas standards for analytical techniques other

than FID and electron capture (EC) have become more necessary as the quantitative ability of these techniques (e.g., GC/mass spectrometry) have been

developed. Preliminary studies of gravimetrical ly-prepared mixtures of up to

four organic solvents in a matrix gas demonstrated inaccuracies in predicted

concentrations of less than 1 percent (relative) for each organic component

at the one ppm concentration level.

Stability studies for several organic vapor/matrix gas mixtures in gas

cylinders have been in progress for nearly two years. Periodically, all of

the cyclinder standards are intercompared to detect any change in the relative

response/concentration ratios of freshly-processed mixtures to mixtures that

have been stored for longer time periods. If no difference in this ratio

is noted between these mixtures, the concentrations of the cylinders are considered to be stable with time.

Benzene/air, benzene/nitrogen, and perchloroethylene/nitrogen mixtures

have been studied for the past several years and no change in concentration

has been observed. Vinyl chloride monomer, chloroform, toluene, and

chlorobenzene, all in a nitrogen matrix have been observed for a one year

period with no evident change in concentration.

Both gas cylinder mixtures and permeation tubes containing benzene and

perchl oroethylene prepared to our specifications have been obtained commer- cially and are in the process of certification for their issuance as SRM's.

The results of the calibration of 17 benzene permeation tubes chosen randomly

from a batch of 100 tubes in the certification process are shown in Table 37.

The difference between the rates determined gravimetrically and the predicted

rates based on their comparison with primary gas cylinder standards is less

than ±1 percent (relative) in most cases. Since each tube in a batch will be

individually calibrated, the uncertainty in the certified permeation rate of

any SRM benzene permeation tube should be about ±1 percent (relative).

W. P. Schmidt

230
Table 37. Calibration of Benzene Permeation Tubes at 25.0 °C. Rates

Determined by Gravimetry and by Comparison with Primary

Gas Cylinder Standards.

Permeation

Tube

No.

Permeation

Rate, 25.0 °C

(Gravimetric)

F I

D

a Response

Dilution Flow = 100 cc/min.

Permeation

Rate, 25.0 °C

FID

(vs. Grav. Stds.)

A Permeation

Rate

(FID - Grav.

3 0.338 yg/min. 2504 0.343 yg/min. 1.5 % Rel

.

5 0.369 2710 0.371 0.5

12 0.355 2600 0.356 0.3

13 0.355 2610 0.357 0.6

20 0.343 2512 0.344 0.2

22 0.372 2711 0.371 -0.2

26 0.358 2618 0.358 0.0

31 0.341 2492 0.341 0.0

53 0.341 2494 0.341 0.0

54 0.356 2595 0.355 -0.2

58 0.371 2713 0.372 0.2

66 0.377 2756 0.377 0.0

70 0.360 2638 0.361 0.3

76 0.339 2494 0.341 0.7

82 0.347 2527 0.346 -0.3

85 0.365 2658 0.364 -0.4

86 0.368 2696 0.369 0.3

a Flame ionization detector.

14. Nitrogen Dioxide Standard for Stationary Source Emission Measurements

A series of four new SRM's consisting of nitrogen dioxide in air at

concentrations of 250, 500, 10QQ, and 2500 parts per million (ppm) will soon

be issued by NBS. The certification of these SRM's was particularly difficult

because of the highly reactive nature of the N02 molecule and because of the

absence of accurate analytical methods for N02

. The reactivity of N0 2 precludes the use of gravimetrical ly prepared standards and the uncertainty of

the reaction of NO2 has thus far excluded the use of chemical or physical

reaction for analysis on an absolute basis. Consequently, these mixtures

were analyzed by conversion of the N02 to NO followed by analysis with instruments that respond only to NO and which have been calibrated with accurate

NO standards. The results yielded a precise relationship between samples at

231
the same concentration and a precise relationship between the various concentrate levels. The precise relationship between the various concentrate

levels was further confirmed directly by UV photometric measurements of

the N02

.

Two major problems that had to be resolved before the program could suc- cessfully proceed were the determination of the efficiency of the conversion

of N02 to NO and the difference in response of the NO analyzer to a nitrogen

versus air balance gas. The solution to these problems and further confirmation of the accuracy resulting from the solution are described below.

The response of the chemiluminescent NO analyzer is dependent upon many

things but the three that must be consideredin this application are:

the NO content of the sample entering the cell, C^;

the flow rate of the sample into cell, f^;

and,

the quenching effect of the balance gas, Q.

When N0-in-N 2 standards are used to analyze N0 2 -in-air samples, all three of

these factors must be determined. The NO content of the N0-in-N 2 standard is

known but when the N0 2 -in-air is analyzed the amount of NO is dependent on the efficiency of conversion of the N02 to NO.

The converter efficiency was independently measured using an N02 optoacoustic detection system. The utility of this system has been demonstrated

in the direct measurement of N02 in the intercomparison of NO, 0 3 , and N0 2 analytical techniques. The converter efficiency was determined by alternately

directing the flow from a permeation tube calibration system through and

around the catalytic converters into a stainless steel optoacoustic cell. The

detection response obtained by flow through the converter, Rconv

5 and bypassing the converter, R[

3ypass

> were used in the calculation of converter

efficiency, CE, by the following relationship: DR R R rr _ ( bypass - bypass, baseline) — ( conv - conv, baseline) (1) tt 7~5 n S v bypass - bypass, baseline'

Using this procedure, a converter efficiency of 96.6 ± 0.6 percent was obtained over the N02 concentration range of 10 ppm to 120 ppm. Within the

stated uncertainty, the converter efficiency did not show any N02 concentration

dependence.

The effects of sample flow rate into the chemilumenescent cell and the

background gas quenching were determined using the chemiluminescent nitric

oxide analyzer and a high-rate N02 permeation tube system. The flow rate

into the cell is regulated by a capillary tube and is dependent on the molecular weight of the gas (i.e., nitrogen versus air). The chemiluminescent

quenching may also be dependent on the balance gas, again nitrogen versus

air. Nitrogen and air were alternately used as balance gases through the N02 permeation tube system. The difference in the signals observed on the nitric

232
oxide analyzer was a direct measure of the combination of these two effects

since everything else was identical. The difference in the signals was determined to be 1.5 percent which is consistent with the difference in

sample flows through the capillary.

Using air as a balance gas, the permeation tube system produced cal i brant

mixtures with sufficient flow to directly calibrate the N0 2 analyzer to

analyze the N02 /air mixtures at 250 and 500 ppm. The values determined by

this method agree within 0.5 percent relative with the values calculated by

using NO standards and applying the appropriate factors.

E. E. Hughes, W. D. Dorko, A. Fried

15. Intercomparison of Aitken and Cloud Condensation Nuclei Counters

An important measurement problem in the areas of cloud physics, air

quality, and atmospheric modeling and characterization is that of detecting

and quantitating the concentration of Aitken and Cloud Condensation Nuclei

(CCN). (Aitken nuclei are those particles capable of being activated as condensation nuclei at supersaturations of the order of 200 percent, whereas

CCN are particles or aerosols capable of being activated as condensation

nuclei under atmospherically realistic supersaturations of between 0 percent

and 1-2 percent.) A variety of Aitken counters and CCN counters have been

developed but their performance has never been rigorously intercompared nor

has a "standard" counter been agreed upon as a reference for calibration or comparison. During the past year we have intercompared two Aitken counters — a Poliak counter and a Thermal Systems Incorporated (TSI) Condensation

Nucleus Counter (CNC) - and have also, as participants in the 1980 International CCN Workshop, i ntercompared these instruments with CCN counters of

other participants.

The Poliak counter, which has been in wide use for over 20 years,

measures Aitken nuclei concentrations by overpressuring an air sample during

which time it is saturated with water vapor, and then quickly expanding the

volume to achieve supersaturation and subsequent nuclei activation and growth

by condensation of the vapor. The concentration of droplets formed is measured by determining the decrease in transmittance of a light beam through

the sample. The transmittance must be calibrated against concentration of

the aerosol

.

The TSI CNC is a continuous flow instrument and works on a completely

different principle. The sample stream is first saturated with alcohol vapor

(n-butyl alcohol) and then passed through a chilled condenser tube (kept at

25 °C below the saturator) where supersaturation occurs, the nuclei are activated, and the resulting droplets grow to 5 to 10 ym in diameter. The

sample containing droplets then passes into a viewing/detection region. For

sample concentrations below 1000 cm” 3

, the droplets are counted individually

by detecting the pulses of scattered light resulting when a droplet passes

through a light beam in the detection region. The instrument operates in an absolute or self -cal ibrating mode in this case and one needs know only the

flow rate and the count rate to determine the concentration. (At higher

count rates it is necessary to apply a correction for coincidence losses, but

this is easily accomplished.) At concentrations above 1000 cm 3

, the TSI CNC

233
operates in a photometric mode in which the photodetector circuit measures

the intensity of light scattered from all the droplets present in the detection volume. The photodetector output then must be calibrated as a function

of concentration of the aerosol, and the resulting calibration incorporated

into the electronics of the instrument. In addition to flow rate, parameters

such as residence time in the condenser tube, vapor and heat diffusivity,

photodetector linearity, and optics cleanliness all affect the calibration

of the instrument.

We have found, in a comparison of the Poliak and TSI CNCs, that the

instruments are in agreement to within 10 percent when the TSI is in the

single or absolute count mode (see figure 54). (This result confirms an earlier study [1] which indicated that the Poliak calibration curve tends to

underestimate the concentration by some 10 to 20 percent at low values (below

1000 cm

-3

) when compared to an "absolute" Aitken counter which used photographic detection of the droplets and subsequent visual counting.) The upper curve of figure 54 calls attention to several precautions that must be taken

in using the TSI in the photometric measurement mode. The non-linear portion

of the log-log plot of the TSI-vs-Pollak results was due to dirty optics in

the instrument. Light scattered from dirt or a film on the optics contributes

a small background signal that is integrated into the signal resulting from

light scattered by the droplets. The relative contribution of this background

decreases as concentration increases and, in this case, becomes negligible

above 2000 cm” 3

. The linear portion of the upper curve is parallel to an extrapolation of the lower curve (absolute counting mode) which suggested a miscal ibration was likely. A check of one calibration parameter (the photodetector pulse height) showed that the instrument was indeed out of

calibration. This was due at least partly to the fact that we were operating

the instrument at an appreciably higher altitude (Reno, Nevada, 1371 M) than

that at which it was calibrated (St. Paul, Minnesota, 266 M). There is no direct way to adjust the calibration and our conclusion is that one must

exercise great caution in using the instrument in the photometric mode for

absolute concentration determinations. We also note, however, that it still

provides reliable relative measurements in this concentration range and has

the advantage of providing a continuous, real-time measurement.

We have also compared the performance of the Poliak and the TSI CNCs with

that of cloud condensation nucleus counters. Under most conditions the CCN

counters will give lower values because they detect and measure only those

nuclei which are activated at a few percent supersaturation. However, when

the test aerosol is a monodi sperse, submicrometer aerosol, it will all be

activated by these devices and the two different types of instruments should

give the same results. Our results of an intercompari son of a representative

CCN counter (the University of Missouri at Rolla continuous-flow diffusion

chamber) with the Poliak and the TSI indicated that this particular instrument

read about 20 percent and 10 percent higher than the Poliak and TSI counters,

respectively. This is considered quite good agreement.

The results of the intercomparison have served to validate a large body

of data that has been taken with the Poliak over the last twenty-some years.

The study also identifies the conditions under which the TSI CNC can be used

as a self-calibrated, absolute counter and the conditions under which one must exercise caution (i.e., the photometric mode) in interpreting the accuracy

i .fni

I 234
CN/cm

3

(TSI)

20 10 2 10 3 10

4

CN/cm3 (POLLACK)

Figure 54. Intercomparison of TSI and Pollack Condensation Nuclei concentration measurements (CN/cm 3 ). The TSI counter was operating in the

single count mode in the lower curve and in the photometric mode

in the upper curve.

235
of the results. On the basis of our results, we recommend that the TSI be

used in the single-count mode exclusively and we plan to evaluate the

feasibility of developing an automated dilution system that will allow one to

always present the instrument with sample concentrations below 1000 cm" 3

.

Reference

[1] Emmanuel, M. B.; Squires, P. Absolute calibration of a photoelectric condensation nucleus counter at low values of

nucleus concentration, PAGEOPH, 72^:268-283 (1969.

R. L. McKenzie

16. Nuclear Environmental Analytical Chemistry

During the past few years our research in this area has been directed

toward the development of radiocarbon dating techniques for the identification

of sources of carbonaceous gases and particles in the atmosphere. These

efforts remain our primary focus, but the scope of the program has expanded

somewhat to encompass the combined use of nuclear, (stable) isotopic and

chemical data together with environmental models to increase our basic understanding of the environmental system.

A. Environmental radiocarbon results . A continued effort has been made

this past year to apply radiocarbon ( I4 C) measurements to atmospheric carbonaceous particles and gases for source identification. The basic model for

use of 14 C as an environmental tracer is isotopic dilution; that is, radiocarbon is present in all living ("biogenic") matter, and, since it decays

with a half-life of 5730 years, it is essentially absent from fossil fuel.

The relative proportions of bioqenic and fossil source components is thus

deduced from the observed 14 C/ 12 C ratio compared to that in the biosphere

( 14 C/ 12 C £ 1.5 x 10~ 12

). Because the two-source assumption (fossil, biogenic)

is quite good, and because isotopic composition is quite robust with respect

to changes due to reaction or transport, the 1C/ 1

C ratio is intrinsically

reliable for (carbonaceous) source apportionment. For most studies involving

measurement of 14 C oh particulate samples containing milligrams carbon our low-level counting (11c) facility utilizing miniature gas proportional

counters is ideal, but for individual species the tandom Accelerator Mass

Spectrometer (AMS) approach of counting single 14 C atoms on microgram

quantities is necessary. Activities this year have included 14 C measurements by 11c on particulate samples collected in Houston, Texas and Elverum,

Norway for urban source identification, Shenandoah Mountains for local

natural pollution affects, and Pt. Barrow, Alaska for long range transport

of elemental carbon.

B. Low-level counting measurement techniques . Our work on extending

the state-of-the-art of small sample decay counting [low level counting (11c)],

mi nature proportional counters), and direct atom counting [accelerator mass spectroscopy [AMS)] [tandem accelerator) has continued. One emphasis has

been the further investigation of sample preparation techniques for AMS and

improved sample prepararion, radiocarbon (j5~) measurement and data reductionquality control methods for 11c . We have instituted an improved means of

236
quality control involving "segmented counting" with the automatic output of

six control charts for each measurement. In this process, each major counting

period (typically 8-24 hours) is subdivided into approximately 10 counting

intervals, and important parameters — such as barometric pressure, guard

count rate, meson rate, anticoincidence rate, etc. — are separately monitored.

Occasional localized problems (as from a passing thunderstorm) can be quickly

deduced from the mul ti parameter control chart.

C. Sample preparation research . For each carbonaceous sample type

being investigated, chemical methodology for quantitative conversion of

sample to carbon dioxide is extremely important. To analyze atmospheric CH 4 samples, (18 samples were collected at NBS), a means of converting CH4 to

C02 was developed which uses a catalyst (Hopcalite) at ^400 °C in the

presence of oxygen.

In addition, each particulate sample is unique to the collection site,

and contains varying nitrogen and sulfur compounds that upon combustion are transformed into impurities which affect lie counting efficiencies. It has

therefore been necessary to refine our purification procedure for nitrogen

and sulfur oxides and we are currently developing purification techniques to remove Rn-222 from C02 samples. Rn-222 may be either inherent in sample or occur as a result of combustion. We have found gas chromatographic

techniques to be most useful here.

If sample sizes are in the microgram range, an AMS approach to 14 C assay

will be required. For this reason some research has been devoted to the

combustion of microgram quantities of carbonaceous samples to carbon dioxide

and subsequent chemical conversion to carbon (amorphous form) to be used as

a solid source for AMS. The technique utilizes a closed vycor break-seal

tube for quantitative combustion to C0 2 and subsequent transfer of C02 to a second vycor break-seal tube for reduction to carbon in the presence of Mg

metal

.

D. Radiocarbon and receptor modeling . The information content from

radiocarbon measurements can be enormously enhanced by combining it with

"serial" or "parallel" chemical or physical information. By serial information, we refer to 14 C data which results from a serial selection process

according to time, location, particle size, or chemical species. Parallel

information refers to multidimensional data, that is data arising from the

simultaneous evaluation of a single sample according to such characteristics

as isotopic composition ( 13 C, 14 C), inorganic composition, organic composition, and morphology. In a sense serial data, collected for a series of

samples, provides the necessary input for multivariate analysis (including

time series and principal component analysis); parallel data from a single

sample yields the input for least squares analysis (chemical mass balance).

Such a combination of 14 C measurements, which yield a robust indication of

the biogenic fraction, with complementary physicochemical data is clearly a most powerful approach for receptor model validation and precise estimation

of individual carbonaceous source components. (Radiocarbon alone, of

course, will not resolve individual biogenic or individual fossil carbon

sources .

)

237
An initial step taken towards the modeling problem has been incorporation

of a multi -facet routine called "Arthur" for pattern recognition on large

data sets and the addition of multi-dimensional scaling routines and

parametric mapping.

L. A. Currie, R. W. Gerlach, G. A. Klouda, G. B. Tompkins

17. Development and Evaluation of Personal Particulate Dosimeters

The development and testing of the NBS portable particle sampler has been

completed. Much of this work involved the use of the wind tunnel which was built and tested last year. Several prototype samplers were made and have

been sent to the project sponsors, the Environmental Protection Agency, and

to Dr. John Spengler of the Harvard Medical School, Boston for evaluation.

The NBS sampler differs from existing portable samplers in that it collects

both the inhalable (5-15 ym) and respirable (<3 ym) size fractions and has a higher flow rate for longer sampling periods. Besides developing the NBS

sampler, we have tested the particle size collection characteristics of the

10 mm nylon cyclone used in the Harvard Medical School sampler and the H & H (of Toronto) aluminum cyclone.

NBS Sampler

The NBS sampler consists of three particle collection elements — an inlet, a coarse filter, and a fine filter - in which each element collects

successively smaller sized particles.

The inlet was designed by Drs. Walter John and Steve Wall of the University of California, Berkley and was rescaled by us to adapt to the NBS sampler.

The inlet is cyl indrical ly symmetrical to minimize the effects of wind

direction. It removes the very large particles from the sample by impaction

and passes the smaller particles on to the filters. A cross section of the

inlet is shown in figure 55. Representative data showing the collection

efficiency vs. wind velocity with the 15 ym conical insert in place is shown

in figure 56. Here, the diameters range from 4 to 7 ym. The collector

efficiency for particles below 7 ym decrease slightly with wind speed.

We tested the coarse filter collection efficiency in more detail than

reported last year, since this element of the sampler separates the respirable

size fraction from the larger or inhalable size fraction. Figure 57 shows the

filter collection efficiency and Table 37 gives the corresponding 50 percent

cut point characteristics. The effects of particle bounce, particle density,

and filter loading are of particular interest. For total filter loadings

under 400 yg the cut characteristics did not change, as shown in figure 57.

The coarse filter suffers some particle bounce, and liquid particles, which

do not bounce, are collected more efficiently than solid ones. However,

liquid particles are atypical for ambient aerosols in this size range.

Particle density affects the cut characteristics only slightly.

238
Inlet

239
4

to

7jum

diameter

i i i

i i i i i i i o 10

T- O

Aouepwg

j— o

o

o

240

Figure

56.

Collection

efficiency

of

the

inlet

asa

function

of

wind

speed

for

4

to7

ym

diameter

particles

at

0,

45,

and

75

degrees

relative

to

the

wind

direction.
Filter

Collection

Efficiency

1.0 rParticle Aerodynamic Diameter—/urn

Figure 57. The filter collection efficiency is the mass fraction of

particles reaching the filter that stick on the filter.

The efficiencies of the filter before (Clean) and after

collecting (Loaded) a 150 to 400 yg sample are shown

along with the AEC recommended respirable cut curve.

Table 37. Cut Point Characteristics.

Device

AEC respirable

recommendation

50% Cut Point

Diameter - ym

a = Geometric

9

Standard Deviation

3.4 2.7

3.2 2.8

2.6 1.7

5.7

NBS coarse filter

10 mm cyclone

H & H cyclone

241

1.9
The fine filter is intended to catch all of the remaining particles.

Since this filter is the sampler element that requires the most work of the

pump, we selected a Teflon fiber filter, gaining a three-fold reduction in

pump work over that of similar filters at the cost of a 1 to 2 percent loss

of 0.1 ym particles. Loadings heavier than anticipated with normal use did

not plug the fine filter or change the sampler flow rate.

The sampler draws air at 6 L/min for over 24 hours, sampling a larger

volume of air than other similar devices. This is important because for

ambient air, obtaining sufficient sample for weighing is often a problem.

The sampler, enclosed in a case lined with foam, operates quitely. The

interior of the case serves as a pulse damper so that the air flow through

the size discriminating elements is much smoother than in other similar

samplers. Tools are not required to change filters or sampler parts. All

parts are commercially available except the inlet.

Cyclones

The cut or cyclone efficiency curves which show the fraction of particles

caught by the cyclones vs. particle diameter were determined for both

cyclones. We characterized the 10 mm cyclone with the 1.7 L/min pulsation

air flow of the Harvard sampler iand the H & H cyclone with a steady 1.7 L/min

air flow. The cut characteristics are given in Table 37, along with the

characteristics for the AEC recommended respirable cut point and the NBS

sampler coarse filter cut.

D. S. Bright, R. A. Fletcher

242
C. Outputs and Interactions

(Gas and Particulate Science Division)

1 . Publications

Blaha, J. J. , Myklebust, R. L. , and Etz, E. S. , "Automation of the NBS

Laser-Raman Microprobe," Microbeam Analysis--1981 , Geiss, R. H.,

Ed., San Francisco Press, pp. 61-64 (1981).

Blaha, J. J., Etz, E. S. , and Heinrich, K. F. J., "Raman Microprobe Analysis

of Stationary Source Particulate Pollutants," EPA Report, EPA-6001-,

issued by the Office of Research and Development, U. S. Environmental

Protection Agency, Research Triangle Park, N. C. 27711, 30 pages

(July 1981).

Currie, L. A., "The Origin of Carbonaceqous Species in the Atmosphere

Deduced by Radiocarbon," ASTM Symposium on Sampling and Analysis of

Toxic Organics in the Atmosphere, ASTM STP 721 p. 120 (1980).

Currie, L. A., Klouda, G. A., and Cooper, J. A., "Mini-radiocarbon Measurements, Chemical Selectivity, and the Impact of Man on Environmental

Pollution and Climate," Radiocarbon 22^, 349 (1980).

Currie, L. A., and Polach, H. A., "Exploratory Analysis of the International

Radiocarbon Across-Cal ibration Data: Consensus Values and Interlaboratory Error," Proceedings of the 10th International Radiocarbon

Conference, Radiocarbon 22^, 933 (1980).

Voorhees, K. J., Kunen, S. M. , Durfee, S. L., Currie, L. A., and Klouda, G. A.,

"Characterization of Airborne Particulates by Pyrolysis/Mass Spectroscopy and 14 C Analysis," Anal. Chem. , S3, 1463 (1981).

Elkins, J. W. , Wofsy, S. C. , McElroy, M. B. , and Kaplan, W. A., "Nitrification

and Production of N 2 0 in the Potomac: Evidence for Variability,"

Nutrient Enrichment in Estuarios , ed. by B. Neil son and L. E. Cronin,

Humana Press Inc., N. J. , p. 25-35 (1981).

Wofsy, S. C., McElroy, M. B., Elkins, J. W., "Transformations of Nitrogen

in a Polluted Estuary: Nonlinearities in the Demand for Oxygen at

Low Flow," Science 2W, 754-756 (1981 ).

Etz, E. S. , "Empirical Quantitation in Raman Microprobe Analysis," in

Microbeam Anal ys i s —1981 , Geiss, R. H., Ed., San Francisco Press,

pp. 73-78 (1981).

Fletcher, R. A., Bright, D. S., "The NBS Personal Ambient Aerosol Sampler.

Capabilities and Testing," Proc. 1981 and Bulk Solids Conference

(1981).

Hughes, E. E. and Mandel , J., "A Procedure for Establishing Traceability

of Gas Mixtures to Certain National Bureau of Standards SRM's", NBSEPA Joint Report EPA-600/7-81 -010, May 1981.

243
Langway, C. C., Jr., Klouda, G. A., Herror, M. M., Cragin, J. H. , "Seasonal

variations of chemical constituents in annual layers of Greenland

Deep Ice Deposits," [Union Geodrsiqur et Geophysique Internationale,

Association Internationale des Sciences Hydrologiques. Commission

des Neiges et Glacks.] Symposium. Isotopes et Impureties dans les

Naiges et Glacks. Actes du Colloque da Grenoble, Acut/Septembre

1975, p. 302-06. (IAHS-AISH Publication No. 1181).

Fiori, C. E., Myklebust, R. L., and Gorlen, K. , "Sequential Simplex: "A

Procedure for Resolving Spectral Interference in Energy-Dispersive

X-ray Spectrometry", Energy-Dispersive X-ray Spectrometry, NBS Spec.

604, 233-272 (1981).

Myklebust, R. L. , Fiori, C. E. , and Heinrich, K. F. J., "Spectral Processing

Techniques in a Quantitative Energy-Dispersive X-ray Microanalysis

Procedure (FRAME C)", Energy-Dispersive X-ray Spectrometry, NBS Spec.

Publ . 604, 365-379 (1981).

Newbury, D. E. , "Characteristics of Backscattered Electron Detectors for

Scanning Electron Microscopy" Microbeam Ana1ysis-(1981

)

, ed. R. H. Geiss

(San Francisco Press, 1981) pps. 1-8.

Newbury, D. E., "Microanalysis of Individual Layered Particles by Secondary

Ion Mass Spectrometry" NBS-EPA Interagency Energy/Environment R and

D Program Report (1981).

Kingston, H. M. , Pella, P. A., "Preconcentration of Trace Metals in Environmental and Biological Samples by Cation Exchange Resin Filters for

X-ray Spectrometry," Anal. Chem. 53^, 223-227 (1981 ).

Stone, R. E. , Walter, F. J., Blackburn, D. H. , Pella, P. A., and Kramer,

H. W. , "A Standard Technique for Measuring Window Absorption and Other

Efficiency Losses in Semiconductor Energy-dispersive X-ray Spectrometry,"

X-ray Spectrom., 10_ (1981).

Sleater, G. A., P. G. Campbell,, M. A. Post., J. F. Seiler., "Protective

Coatings for Steel Structures: Laboratory & Development of a Model

Coating Guide Specification," ESL-TR-80-20 (Air Force Engineering & Services Center) Jan. 1980.

Small, J. A., Steel, E. B., "An Overview of NBS-EPA Program for Development

of Standards for use in the Analysis of Environmental Samples for

Asbestos by Electron Microscopy," in Proc. Third International

Colloquium on Dust Measuring Technique and Strategy, Held in Cannes

Friday, June 10-12, 1980, published 10/81.

Rehm, Ronald B., Bright, D. S., "A First Order Kinetic Titrimetry Solution"

(submitted to Analytical Chemistry 7/2/81).

Currie, L. A., "Quality of Analytical Results, with Special Reference to

Trace Analytical and Sociochemical Problems," Pure and Applied Chemistry,

in press.

244
Currie, L. A., "Interpreting the Environmental Record," Nuclear and Chemical

Dating, Symposium Series, 1981, in press.

Currie, L. A., "Contemporary Particulate Carbon," in: Particulate Carbon:

Atmospheric Life Cycle, G. T. Wolff and R. L. Klimisch, eds.. General

Motor Research Laboratories, (1981) in press.

Cooper, J. A., Currie, L. A., and Klouda, G. A., "Application of Carbon-14

Measurements To Impact Assessment of Contemporary Carbon Sources on Urban Air Quality." (submitted to Environmental Science and Technology,

1981 ) to be publ ished.

Cooper, J. A., Currie, L. A., and Klouda, G. A., "Assessment of Contemporary

Carbon Combustion Source Contributions to Urban Air Particulate Levels

Using C-14 Measurements," Env. Sci. & Tech., 1981 in press.

Currie, L. A., Klouda, G. A., and Gerlach, R. W. , "Radiocarbon: Nature's

Tracer for Carbonaceous Pollutants," Proc. International Conference on Residential Solid Fuels, J. A. Cooper, Ed., (1981) in press.

Currie, L. A., Klouda, G. A., "Counters, accelerators, and Chemistry," Nuclear

and Chemical Dating Techniques, in press.

Fried, A., "Laser Optoacoustic Detection of N02 in the Gas Phase Titration

of Nitric Oxide with Ozone," submitted to Anal. Chem.

Wofsy, M. B., McElroy, M. B. , Elkins, J. W. , "Transformations of Nitrogen in

a Polluted Esturary: Nonlinearities in the Demand for Oxygen at Low

Flow," Science, 213 (1981) in press.

Cragin, J. H., Herron, M. M., Langway, C. C. Jr., and Klouda, G. A.,

"Interhemi spheric comparison of the composition of atmospheric precipitation during the Late Cenozoic Era". Proceedings of the SCOR/SCAR Polar

Oceans Conference, Montreal, P. Q. Canada, 5-11 May 1974. To be published.

Rogers, C. F. , and McKenzie, R. L., "Comparisons Between Two Aitken Counters

and with Cloud Condensation Nuclei Counters at the 1981 International

CCN Workshop. Submitted to Journal de Recherches Atmospheriques

.

Myklebust, R. L. , Pella, P. A., and Thorne, B., "An Overview of EXFNBS-A

Data Reduction Procedure for Energy-Dispersive XRF with Secondary Target

Excitation," Submitted to X-ray Spectrometry.

Myklebust, R. L., Small, J. A., and Newbury, D. E., "Errors Observed in the

Analysis of Particle Mixtures by Overscanning" Int'l Rev. of

Scanning Electron Microscopy-1981 (in press).

Fiori, C. E., Newbury, D. E., and Myklebust., "Artifacts Observed in Energy

Dispersive X-ray Spectrometry in Electron Beam Instruments-A Cautionary

Guide", Energy-Dispersive X-ray Spectrometry , ed. K. R. J. Heinrich.,

D. E. Newbury, R. L. Myklebust., and C. E. Fiori NBS spec. publ. 604

(in press).

245
Newbury, D. E., "Imaging Strategy in the Scanning Electron Microscope-A Tutorial

Int'l Rev. of Scanning Electron Microscopy 1981 (in press).

Newbury, D. E., "Characteristics of Backscattered Electron Detectors for

Scanning Electron Microscopy" in Microbeam Analysis-1981 (in press).

Newbury, D. E. , and Myklebust, R. L., "Monte Carlo Electron Trajectory Calculations of X-ray Generation in Tilted Solid Specimens" in Microbeam Analysis1 981 (in press).

Pella, P. A., "Standard Practice for Testing Homogenity of Materials for the

Development of Reference Materials, Part 42", ASTM publication, (in press).

Pella, P. A., Sieber, J. R. , "Intercomparison of NRLXRF, Semi -Empiri cal , and

NBS Interelement Correction Methods," submitted to X-ray Spectrometry.

Small, J. A., "Quantitative Particle Analysis in Electron Beam Instruments

A Tutorial," International Review of Scanning Electron Microscopy,

1981 (in press).

Small, J. A., Steel, E. B., "Analysis of NBS SRM #1648 for Use as a Matrix

Material in the Development of Asbestos Filter Standards," NBS Special

Publication, 619 (in press).

Steel, E. B., Newbury, D. E. , Pella, P. A., "Preparation of Thin Film Glass

Standards for Analytical Electron Microscopy," in Proc. of 3rd International Workshop on Analytical Electron Microscopy, San Francisco Press,

CA. , 1981 (in press)

Steel, E. B.,. Small, J. A., "Minimization of Operator Error in AEM Analysis of

Asbestos NBS," Special Publication 619, (in press).

Steel, E. B. , Small, J. A., Leigh, S., Sheridan, P., Fill iben , J., "Error

in Asbestos Analysis: Operator Error and Filter Homogeneity," Scanning

Electron Microscopy, 1981 (in press).

Steel, E. B., Wylis, A. G., "Mineralogical Character of Asbestos," in

Geology of Asbestos Deposits , AIME, (in press).

2. Tal ks

Bass, A. M. , "Ultraviolet Absorption Cross Sections of Ozone: The Temperature

Dependence," Photo Chemistry Conference, University of Crete, Greece

Sept. 7-12 1981, Spectrosc'opy in Support of Atmospheric Measurement., OSA * Topical Meeting Sarasota, FI. Nov. 10-12, 1980.

Bright, D. S., "New Personal Ambient Aerosol Sampler," American Industrial

Hygiene Conf . , Portland, OR (3/28/81).

Bright, D.S., "Performance of NBS Personal Ambient Aerosol Sampler," ASTM

Conference on Sampling and Analysis of Toxic Materials in the Atmosphere,

Boulder, CO (8/3/81).

246
Currie, L.A., W.F. Libby Memorial Symposium on Nuclear and Radiochemistry,

NYC (8/25/81).

Currie, L.A., "Radiocarbon: Nature's Tracer for Carbonaceous Pollutants,"

1981 International Symposium on Residential Solid Fuels, Portland, OR,

(6/2/81).

Currie, L.A., "Carbon Pollutants: Where From?", Radio Program (ACS)-Men and

Molecules (3/23/81)

Currie, L.A., "Contemporary Elemental Carbon," 1980 GMR Symposium, Warren, MI

(10/14/80).

Currie, L.A., "Measurement of Natural Radiocarbon: New Applications and

Methodology," NIH, Bethesda, MD (12/29-80).

Currie, L.A., " The Isotopic Dimension: Exploring Man's Contribution to

Carbonaceous Pollution," 15th Middle Atlantic Regional Meeting, ACS,

Washington, DC (1/8/81).

Currie, L.A., "Quality of Analytical Results, With Special Reference to Trace

Analysis," International Symposium on Trace Analysis and Technological

Development, Bombay, India (2/17/81).

Currie, L.A., "The Radiocarbon Renaissance," Physical Research Laboratory

Ahmedabad, India (2/23/81).

Currie, L.A., "Trace Analysis and Cosmogenic Nuclides: Tools for Studying

the Environment," Indian Institute of Technology, Kanour, India

(2/24/81).

Currie, L.A., "Noisy Signals: The Analytical Frontier," 11th Annual Symp.

on the Analytical Chemistry of Pollutants, Jekyll Island, GA (5/18/81).

Etz, E.S., "Strategy and Tactics on the Raman Microprobe Analysis of Environmental Particles," 15th ACS Middle Atlantic Regional Meeting (MARM),

Washington, DC (1/8/81).

Etz, E.S. , "Raman Microprobe Analysis: Status and Prospects," Colorado

State University, Fort Collins, CO (9/14/81).

Etz, E.S., "Materials Characterization by Raman Microprobe Spectroscopy,"

University of Wyoming and the DOE/Laramie Energy Technology Center,

Laramie, WY (9/15/81).

Etz, E.S., "Demonstrating the Multiplex Advantage in Raman Microprobe

Spectroscopy," 8th Annual Meeting of the Federation of Analytical

Chemistry and Spectroscopy Societies (FACSS), Philadelphia, PA (9/23/81).

Fletcher, R. A., "The NBS Personal Ambient Aerosol Samples: Capabilities

and Testing," 1981 Powder and Bulk Solids Conference. Chicago, ILL.

(5/81).

247
Fletcher, R. A., "Inlet Collection Efficienty of Portable Aerosol Samplers,"

Fourteenth Aerosol Technology Meeting. Johns Hopkins University

School of Hygiene and Public Health Baltimore, MD. (8/81).

Hughes, E. E. , "Primary Standards for Gas Analysis," Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Atlantic City, NJ

(3/12/81).

Kagann, R. H., "FTS Band Intensity Measurements of Nitrous Acid," Thirty-Sixth

Symposium on Molecular Spectroscopy, Columbus, OH (6/15-19/81).

Kagann, R. G. , "FTIR Intensity Measurements in Atmospheric Species," 1981

Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy,

Atlantic City, NJ (3/9-12/81).

Myklebust, R. L., "Quantitative Electron Probe Microanalysis of Fly Ash

Particles," Topical Conference on Atomic and Nuclear Methods in Fossil

Energy Research, Mayaguez, Puerto Rica (12/3/81).

Myklebust, R. L. , "Progress in Quantitative Analysis of Particles at NBS",

Metropolitan Probe Users Group, Paramus, NJ (4/1/81).

Myklebust, R. L. , "Monte Carlo Electron Trajectory Calculations of x-ray

Generation in Tilted, Solid Specimens," 16th Annual Conference of the

Microbeam Analysis Society, Vail, Colorado (7/16/81).

Newbury, D. E. , "Strategy for Imaging with the Scanning Electron Microscope,"

International Conference on Scanning Electron Microscopy, Dallas, TX

(4/13-17/81).

Newbury, D. E. , "Characteristics of Backscattered Electron Detectors for

Scanning Electron Microscopy," Microbeam Analysis Society Conference,

Vail, CO. (7/13-16/81).

Newbury, D. E. , "A Monte Carlo Electron Trajectory Simulation for Analytical

Electron Microscopy," 3rd International Workshop on Analytical Electron

Microscopy, Vail, CO. (7/13-16/81).

Newbury, D. E. , "Application of Microprobe and Surface Analysis Techniques to

Technological and Biological Problems," Labcon 81, Chicago, ILL.,

(9/15/81).

Newbury, D. E. , "Observations on the Mechanisms of High Resistance Junction

Formation in Aluminum Wire Connections," American Society for Metals

Local Society, Albuquerque, NM (9/23/81).

Newbury, D. E. , "Recent Developments in Microbeam Analysis Techniques,"

Northern California MAS Local Group, San Francisco, CA (4/29/81).

Newbury, D. E. , "Backscattered Electron Detectors for Scanning Electron

Microscopy," Metropolitan MAS Local Group, Brunswick, NJ (5/21/81).

248
Newbury, D. E., "Recent Developments in Microbeam Analysis Techniques,"

Southwest MAS Local Group, Albuquerque, NM (9/24/81).

Pella, P. A., "XRF Analysis of NBS Ternary Alloys and Fused Samples Using

Empirical and Fundamental Parameter Data Reduction Techniques,"

7th Annual Meeting of the Federation of Analytical Chemistry and

Spectroscopy Societies (FACSS), Philadelphia, PA (10/1/80).

Small, J. A., "Error in Asbestos Analysis: Operator Error and Filter Homogeneity", Scanning Electron Microscopy, Dallas, TX (4/81).

Small, J. A., "Errors Observed in the Analysis of Particle Mixtures by

Overscanning," Scanning Electron Microscopy, Dallas, TX (4/81).

Small, J. A., "Quantitative Particle Analysis in Electron Beam Instruments,"

SEM, Dallas, TX (4/81).

Small, J. A., "Analysis of NBS SRM #1648 For Use as a Matrix Material in the

Development of Asbestos Filter Standards," NBS/EPA Workshop on Asbestos

Standards, Washington, D.C. (10/80).

Simons, D. S., "The Study of Crystallographic Contrast in Ion Microprobe

Analysis of Incone," 3rd International Secondary Ion Mass Spectrometry

Symposium, Budapest, Hungary (8/31/81).

Steel, E., "Minimization of Operator Error in Analytical Electron Microscopic

Analysis of Asbestos Samples," Asbestos Standards Workshop, Washington,

D.C. (10/80).

Steel, E., "Preparation of Thin Film Glass Standards for Analytical Electron

Microscopy," Microbeam Analysis Society Annual Meeting, (7/81).

3. Committee Assignments

Harry Rook

Member, ASTM D-22.05 Calibration

Member, ASTM D-22.07 Precision and Accuracy of Methods

Member, Office of Water Data Coordination, Committee 5F

Raymond McKenzie

Member, ASTM D-22 Sampling and Atmospheric Analysis

Member, ASTM D-22. 03 Monitoring Instrumentation

Member, ASTM E-29 Particle Size Measurement

Member, ASTM E-29. 04 Characterization of Liquid Particles

Arnold Bass

Member, ASTM D-22. 02 Methods of Sampling and Analysis

Member, ASTM D-22. 03 Monitoring Instrumentation

Member, ASTM D-22.05 Calibration

Member, ASTM D-22.07 Precision and Accuracy of Methods

David Bright

Member, NBS Postdoctoral Selection Committee

249
Lloyd Currie

Member, Intersociety Committee - Methods of Air Sampling and Analysis

Member, Analytical Letters - Editorial Board

Member, International Committee for the Calibration of the Radiocarbon

Time Scale

Member, Model Validation Subcommittee - Receptor Modeling Workshop

Member, CAC Computer Utilization Committee

Member, Organizing Committee - 1981 International Conference on Residential

Solid Fuels

William Dorko

Member, American Chemical Society, Washington Section, Board of Managers

Edgar Etz

Member, ASTM D-22 Methods of Sampling and Analysis of Atmospheres

Jimmie Hodgeson

Member, ASTM D-22 Atmospheric Analysis

Member, ASTM D-22. 02 Manual Methods

Member, ASTM D-22. 03 Instrumental Methods

Member, ISO/TC 146/SC3 Air Oual ity/Ambient Atmospheres

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 158/WG-4 Analysis of Natural Gas

Member, ISO/TC 158/WG-l Terminology

Robert Myklebust

Member, Microbeam Analysis Society (National Council)

Member, ASTM E-2 Emission Spectroscopy

Member, ASTM E-2. 04 Standard Reference Materials

Dale Newbury

Chairman, Microbeam Analysis Society

Chairman, Technical Program Committee

Chairman, National Council for the MAS

Member, ASTM E-42 Surface Analysis

Member, Journal of Microscopy, Editorial Review Board

Member, Scanning, Editorial Review Board

Peter Pella

Member, ASTM E-2 Emission Spectroscopy

Member, ASTM E-2. 02 Statistics, Calibration and Standardization

Gerald SI eater

Member, ASTM D-22 Sampling and Analysis of Atmospheres

Member, ASTM D-22. 06 Source Sampling

Member, ASTM D-22. 07 Precision and Accuracy of Methods

250
4. Other

a. Seminars

October 16, 1981 Dr. William Fairbanks, Colorado State University,

Measurement of Low Iodine 129 Isotopic

Concentration by Laser Fluorescence"

(NBS sponsor: H. Rook)

November 14, 1980 Dr. Bernhard Lehman, Oak Ridge National

Laboratory, "Counting Noble Gas Atoms with

Lasers--a New Approach to 39Ar and 81 Kr Dating"

(NBS sponsor: L. Currie)

January 28, 1981* Dr. Hal Rosen, University of California,

Joint Colloquium with OEM "Soot in the Arctic"

(NBS sponsor: L. Currie)

February 10, 1981* Prof. Jane Fox, University of Illinois

Joint Colloquium with Chemical Kinetics

Division, "A Chemical Instability in the

Stratosphere" (NBS sponsor: J. Elkins)

February 25, 1981 Dr. R. D. Leapman, National Institutes of

Health, "Materials Characterization Using

Electron Energy Loss Spectroscopy"

(NBS sponsor: Dale Newbury)

March 25, 1981* Dr. Louis Codispoti, Bigelow Laboratory for Ocean

Science, Joint Colloquium with Office of Standard

Reference Materials," Temporal Changes in Carbon

Dioxide (pC0 2 ) in the Surface Waters of the

Bering Sea" (NBS sponsor J. Elkins)

April 1, 1981* Mr. Joseph Krasnec, Univeristy of Idaho,

Joint Colloquium with Office of Environmental

Measurements, "Spatial and Temporal Distribution

of Methyl Chloroform in the Earth's Atmosphere"

(NBS sponsor: J. Elkins)

April 22, 1981* Dr. Walter W. Berg, National Center for

Atmospheric Research, Joint Colloquium with

Office of Environmental Measurements, "A

New Look at the Chlorine-Bromine Synergism"

(NBS sponsor: A. Fried)

May 20, 1981* Dr. Michael J. Kurylo, NBS Joint Colloquium

with Chemical Kinetics Division, "HO Reactions

of Stratospheric Importance".

(NBS sponsor: D. Newbury)

251
May 26, 1981

May 27, 1981

June 22, 1981*

June 24, 1981

July 9, 1981

July 27, 1981

Dr. R. G. Downing, Texas A&M University,

"Isotopic and Elemental Heterogeneities

of the Noble Gases in the Solar System"

(NBS sponsor: D. Newbury)

Prof. Nai-Teng Yu, Georgia Institute of

Technology, "Raman Spectroscopy with

Intensified VIDICON & RETICON Detectors"

(NBS sponsor: E. Etz)

Dr. Lado Kosta, Institute Jozef Stefan,

Yugoslavia Joint Colloquium with Office of

Standard Reference Materials

"Reference Analytical Methods for Trace

Analysis of Standard Materials"

(NBS sponsor: H. Rook)

Professor Edward S. Macias, Washington

University, "Urban Haze: The Importance

of Carbonaceous Particles".

(NBS sponsor: R. Fletcher)

Dr. John Titchmarsh, AERE Harwell, England

"Use of Particle Analysis of STEM in Studies

of (1) Reveisible Temper Embrittlement and

(2) Irradiation Induced."

(NBS sponsor: D. Newbury)

Dr. Arnold P. Von Rosenstiel, Applied Research

Organization (TNO), Apeldoorn, The Netherlands,

"Analysis of Fly Ash by High Voltage Electron

Microscopy and Secondary Ion for Mass

Spectrometry.

(NBS sponsor: J. Small

)

*Denotes Jointly Sponsored Colloquia

b. Workshops

"Workshop on Certified Reference Materials" held at NBS May 28, 1981

(E. E. Hughes).

"3rd International Workshop on Analytical Electron Microscopy," July 13-16,

1981. Vail, Colorado (D. E. Newbury session organizer and chairman).

Asbestos Standard Workshop. NBS 10/80. (J. A. Small, organizer and chairman).

"Willard F. Libby Memorial Symposium on Nuclear and Radiochemistry," New York,

NY (August 25, 1981. L. A. Currie, organizer and chairman).

252
c. Standard Reference Materials

X-Ray Fluorescence

1620a, 1621b, 1622b Sulfur in .Residue Fuel Oil

Austenite in Ferrite

1226 Alloy

1155, 1155A Alloy

1173 Alloy

1270, 1270A Alloy

Gas Metrology Group

1625 S0 2 Permeation Tube, 10 cm 1626 S0 2 Permeation Tube, 5 cm

1627 S0 2 Permeation Tube, 2 cm

1629 N0 2 Permeation Tube

1661 S0 2 /N 2 500 ppm

1664 S0 2 /N 2 2500 ppm

1665 CoHo/Ai r 3 ppm

1666 CoH ft /Air 1 0 ppm

1667 C

3 H8 /Air 50 ppm

1668 C

3 H

8 /Air 100 ppm

1669 C

3 H8 /Air 500 ppm

1674 C0 2 /N 2 7%

1675 C0 2 /N 2 14

%

1677 C0/N 2 10 ppm

1678 C0/N 2 50 ppm

1679 C0/N 2 100 ppm

1680 C0/N 2 500 ppm

1681 C0/N 2 1000 ppm

1683 N0/N 2 50 ppm

1684 N0/N 2 100 ppm

1685 N0/N 2 250 ppm

* 1686 N0/N 2 500 ppm

1687 N0/N 2 1000 ppm

2619 C0 2 /N 2 0.5%

2620 co2 /n 2 1%

2621 C0 2 /N 2 1.5%

2622 C0 2 /N 2 2%

2623 C02 /N 2 2.5%

2624 C0 2 /N 2 3%

2625 C02 /N 2 3.5%

2626 C0 2 /N 2 4%

253
t
KIBS-1 14A 1REV- 2-8 c)

U.s. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 81-2425

2. Performing Organ. Report No. 3. Publication Date

December 1981

4. TITLE AND SUBTITLE

Annual Report 1981, Center for Analytical Chemistry

5. AUTHOR(S)

C. W. Reimann, R. A. Velapoldi, J. K. Taylor

6. PERFORMING ORGANIZATION (If joint or other than N BS, see in struction s)

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8. Type of Report & Period Covered

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City, State, ZIP)

10.

SUPPLEMENTARY NOTES

Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

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, 1981 in the Instrumentation Development Group, the Inorganic

Analytical Research Division, the Organic Analytical Research Division, and

the Gas and Particulate Science Division. In addition, it describes certain

special activities in the Center including quality assurance and voluntary

standardization coordination, the National Environmental Specimen Bank, and

service analysis coordination.

12- KEY WORDS (Six to twelve entries ; alphabetical order; capitalize only proper names; and separate key wo rds.by semicojon s) Analytical chemistry; analytical services; gas and particulate science; inorganic

analytical chemistry; National Environmental Specimen Bank; organic analytical

chemistry; quality assurance; voluntary standardization.

13. availability

Q Unlimited

IXl For Official Distribution. Do Not Release to NTIS

Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

15. Price

J>U.S. GOVERNMENT PRINTING OFFICE! 1 98 2-3 6 0 “9 97 / 1 9 0

1

USCOMM-DC 6043-P80