<***' °' ^o,

4^^^ V)

National Bureau of Standards

library, .^E-01 Admin. BIdg,

OCT 6 1981

131133

NBS TECHNICAL NOTE 963

^^fAU of ioQ Air and Water Pollution

' ^^"^^^ Annual Report FY 74-76

U.S. DEPARTMENT OF COMMERCE/ National Bureau of Standards
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' was established by an act of Congress March 3, 1901. The

Bureau's overall goal is to strengthen and advance the Nation's science and technology and

facilitate their effective application for public benefit. To this end, the Bureau conducts

research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is performed by the National Measurement Laboratory, the National Engineering Laboratory,

and the Institute for Computer Sciences and Technology.

THE NATIONAL MEASUREMENT LABORATORY provides the national system of

physical and chemical and materials measurement; coordinates the system with measurement

systems of other nations and furnishes essential services leading to accurate and uniform

physical and chemical measurement throughout the Nation's scientific community, industry,

and commerce; conducts materials research leading to improved methods of measurement,

standards, and data on the properties of materials needed by industry, commerce, educational

institutions, and Government; provides advisory and research services to other Government

Agencies; develops, produces, and distributes Standard Reference Materials; and provides

calibration services. The Laboratory consists of the following centers:

Absolute Physical Quantities^ — Radiation Research — Thermodynamics and

Molecular Science — Analytical Chemistry — Materials Science. THE NATIONAL ENGINEERING LABORATORY provides technology and technical

services to users in the public and private sectors to address national needs and to solve national problems in the public interest; conducts research in engineering and appHed science

in support of objectives in these efforts; builds and maintains competence in the necessary

disciplines required to carry out this research and technical service; develops engineering data and measurement capabihties; provides engineering measurement traceability services; develops test methods and proposes engineering standards and code changes; develops and

proposes new engineering practices; and develops and improves mechanisms to transfer

results of its research to the utlimate user. The Laboratory consists of the following centers:

Applied Mathematics — Electronics and Electrical Engineering^ — Mechanical

Engineering and Process Technology^ — Building Technology — Fire Research —

Consumer Product Technology — Field Methods.

THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts

research and provides scientific and technical services to aid Federal Agencies in the selection, acquisition, application, and use of computer technology to improve effectiveness and

economy in Government operations in accordance with Public Law 89-306 (40 U.S.C. 759), relevant Executive Orders, and other directives; carries out this mission by managing the Federal Information Processing Standards Program, developing Federal ADP standards

guidelines, and managing Federal participation in ADP voluntary standardization activities; provides scientific and technological advisory services and assistance to Federal Agencies; and

provides the technical foundation for computer-related policies of the Federal Government.

The Institute consists of the following divisions:

Systems and Software — Computer Systems Engineering — Information Technology.

'Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted; mailing address Washington, D.C. 20234. ^Some divisions within the center are located at Boulder, Colorado, 80303.

The National Bureau of Standards was reorganized, effective April 9, 1978.
ixcioo Air and Water Pollution

^'^^

Annual Report, FY 74-76

AD ^(^3

William H. Kirchhoff

Eileen Myers

National Measurement Laboratory

National Bureau of Standards

Washington, D.C. 20234

^^^^^ '"' Co.

*<'«f4u of *

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Dr. Sidney Harman, Under Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

U S NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Issued October 1978
National Bureau of Standards Technical Note 963

Nat. Bur. Stand. (U.S.), Tech. Note 963, 387 pages (Oct. 1978) CODEN: NBTNAE

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1978

F<x sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

(Order by SD Catalog No. C13.46:963). Stock No. 003-003-01983-6 Price $6
TABLE OF CONTENTS

Page

List of Figures ' * '^H

List of Tables ^H

Abstract 1

Introduction. 3

Air Pollution Projects

1. Automotive Exhaust Flowmeter

B. Robertson 10

2. Building and Evaluation of a Polluted Air

Delivery System

G. P. Bavmgarten and F. W. Ruegg 19

3. Applications of Infrared Measurements to Air

Pollution Problems

R. Deslattes and C. J. Howard. 22

4. Electron Energy Loss Spectroscopy

R. J". Celotta 42

5. Freon Photochemistry

P. Ausloos. 44

6. Chlorine-Atom Kinetics

Michael J, Kuryto 45

7. The Fluorescence Detection of Nitric Oxide

Hideo Okahe 48

8. Effect of Polymeric Structure on Permeation

Tube Uniformity

D. H. Reneker 54

9. Analysis of Mathematical Models of Integrating

Monitoring Devices

R. J. Rubin. 63

10. Atmospheric Chemical Kinetics

John T. Herron 57

11. Climatic Assessment Program

David Garvin and Robert F. Hampson 73

III
12. A Computer Program for Solving Systems Page

of Chemical Rate Equations

R. L. Brown 77

13. Ultraviolet Ozone Photometry

Arnold Bass 78

14. Gas Standards for Air Pollution Analysis

J. K. Taylor and E. E. Hughes 80

15. Calibration Standards by Thermal Decomposition

Wing Tsang 1 05

16. Gas Dilution Calibration Techniques

J. J. Ritter 1 07

17. Piezoelectric Air Pollution Sensors

Eugene P. Soheide ' ' ^ 37

18. Measurement of Atmospheric Ar by Isotopic

Enrichment and Pulse Shape Discrimination

Spectroscopy

L. A. Cwcrie 1^'

19. Origin of Atmospheric Hydrocarbons

L. A. Currie '^^

20. Lead in Gasoline

J. L. Barnes ^^'

21. Degradation of Polymers

R. E. Florin "^ ^^

22. Fossil Fuel Standards

P. D. LaFleur and D. A. Becker ' ^'

23. Determination of Platinum and Palladium

by Activation Analysis

D. A. Becker ' ^^

24. Urban Dust Project

J. K. Taylor and f/. Cassatt ^ ^^

25. SEM and ESCA as Techniques for Characterization

of the St. Louis Air Particulate

A. W. Ruff ' ^^

26. Development of a Particulate Reference Sample

on Membrane Filters for the Standardization

of X-Ray Fluorescence Spectrometers . P. A. Pella '°^ IV
27. Analysis o£ EPA X-Ray Calibration Standards Page

by Isotope Dilution Mass Spectrometry

I. L. Barnes 1 72

28. An Evaluation of Equipment and Procedures

Used in the Department of Interior Respirable

Coal Mine Dust Sampling Program

IfJayne A. Cassatt and Edgar S. Etz 194

29. X-Ray Fluorescence Analysis of Air Particulates

K. F. J. Eeinrich 1 98

30. Instrumentation For Particle Sizing

M. L. Greenough 203

31. X-Ray Analysis of Limestone Scrubber Slurry

A. Perloff 206

32. Particle Size by Light Scattering

Ilan Chabay 219

33. Development of Sulfur Particle Analyzer

R. L. MoKenzie 223

Water Pollution Projects

34. Flow Measurements for Water Pollution Abatement

G. Kulin 236

35. Water Sampling and Sample Handling for Trace

Element Analysis

D. A. Beaker and S. H. Harrison 242

36. Development of a Deep Sea Ocean Sampler

Meyer Waxman 24o

37. An Electrochemical Chlorine Flux-Monitor

G. Marinenko and J. Devoe 250

38. Priority Standard Reference Materials in

Water Pollution

R. Alvarez 259

39. Mercury in Water Standard Reference Material

H. L. Rook and I. L. Barnes ^"^

40. Mercury in Water Collaborative Study

D. A. Becker 26/

V
41. Transformations of Heavy Metals in Aquatic Page

Environments

F. E. Brinakman and VI. P. Iverson 269

42. Heavy Metal Speciation

Richard A. Durst 3q-|

43. Development of Reference Materials for

Sediment Analysis

John K. Taylor 397

44. Development of Precipitation Standards 309

J. K. Taylor

45. Mixed Heavy Metals in Water SRM

I. L. Barnes 31 )

46. Trace Hydrocarbon Analysis

E. S. Hertz and S. N. Chesler 31

5

47. Organochlorine Analyses

S. N. Chesler and H. S. Hertz 326

48. Fate and Effects of Oil Discharged on the

Marine Environment

S. Wasik 328

49. DDT Propagation Models

A. J. Goldman and L. S. Joel 332

50. Reactor Effluent and Environmental Radioactivity Standards

J. M. R. Hutchinson 335

51. Radioactivity Decay Schemes

D. Hoppes 345

List of Publications 347

VI
List of Figures

Figure 1.1 Long Wavelength Acoustic Page

Flowmeter 17

Figure 2.1 Polluted air delivery system 21

Figure 3.1.1 Zeeman Energy Levels o£ HO7 and

Magnetic Resonance Transitions 27

Figure 3.5.1 X-Y Plotter traces from the digital

oscilloscope used for signal averaging. . . 31

Figure 3.5.2 Analytical curve and results of three

runs of vinyl chloride in air 32

Figure 7.1 The apparatus for the measurement of

quenching of NO fluorescence of various

gases 52

Figure 8.1 A Schematic diagram of the structure

in a longitudinal section of the wall of

a fluorocarbon copolymer tube 58

Figure 8.2 Geometry of the low Angle X-Ray

equipment 59

Figure 8.3 Relationship between permeation rate

and lamellar thickness at various

positions in the tube wall 60

Figure 8.4 Relationship between permeation rate and

orientation index at various positions in

the tube wall 51

Figure 14.1.1 Nitrogen dioxide Permeation Tube g^

Figure 14.2.1 Solid Waste Flow Diagram 100

Figure 14.2.2 Water Sewage Flow diagram 101

Figure 14.2.3 Map showing sampling sites '02

Figure 17.1 Piezoelectric crystal and glass holder

into which it is sealed 117

Figure 17.2 Response from sampling mercury vapor

of 50 ng/£ concentration 118

Figure 17.3 Sensor response versus flowrate 119

VII
Figure 25.1 St. Louis Urban Air Page

Particulate Dust 157

Figure 25.2 Disked Shaped particle is

pollen grain 157

Figure 25.3 Tentacle-Shaped object

"A" related to a plant seed. Object

"B" residue from an incinerated

hydrocarbon material 1^°

Figure 25.4 Large particle has fracture surfaces

similar to glass '5°

Figure 25.5 Similar to that seen in Cross-section

of spruce wood '^^

Figure 25.6 Polycarbonate nucleopore filter located

in final stage Delvon Sampler 11/29/74.. '^^

Figure 25.7 Amphibole from Bozeman, Montana 150

Figure 25.8 Crocidolite from Grignaland, South Africa isi

Figure 25.9 Crysotile from Globe, Arizona *°'

Figure 26.1 Particle size distribution of reground

material '^'

Figure 27.1 Sample Chamber of EDXRF Spectrometer '''

Figure 27.2 (a) Sample Mounting frame 178

(b) X-Ray Beam Profile in sample (x-y)plane. 178

(c) X-ray Beam Profile along z-axis 178

Figure 27.3 PIXEA Uniformity measurement of Typical

Iron Dust 181

Figure 27.4 PIXEA uniformity Results for Deposits.

A, B and C for 12 elements 182

Figure 2,7.5 EDXRF Calibration constants for Ti,Mo

and Sm secondary targets 187

Figure 27.6 XRF Comparison of CSI and yM Calibration

Standards 191

Figure 29.1 NBS energy-dispersive (non-diffractive)

x-ray fluorescence apparatus 200

VIII
Figure 29.2 Iron intensity from filter paper Page

standards versus iron concentration. . . . 201

Figure 29.3 Iron intensity from filter paper

standards versus iron concentration,

curve extended 202

Figure 31.1 Sample holder 211

Figure 31.2 Calcite and Sulfite peaks vs.

composition 213

Figure 31.3 Sulfate peak heights vs. composition... 214

Figure 31.4 Ratio of sulfite to carbonate peak

heights vs.% sulfite. 216

Figure 31.5 Ratio of sulfate to carbonate peak

heights vs. % sulfate 217

Figure 33.1 Pulsed Electrostatic Precipitator

Total Particulate Sulfur Monitor ^^^

Figure 33.2 Calibration Curve for Sulfuric Acid

Using Meloy 285 as a detector 229

Figure 33.3 Thermogram of various Sulfates in CH . . . 230

Figure 33.4 Schematic Diagram of Thermal Speciation

System 231

Figure 33.5 Strip Chart Record of L.A. Freeway

Study 232

Figure 33.6 Schematic of Aerosol Mobility

Chromatograph Speciation Technique 233

Figure 33.7 Equilibrium vapor pressure Data for

Sulfuric Acid 234

Figure 33.8 Separation of Potassium Sulfate and

Sulfuric Acid Aerosols 235

Figure 35.1 Plot of Heavy metal concentrations and

scandium normalized concentrations of

suspended particulates versus Sampling

Station in Woods Creek 247

Figure 37.1 Chlorine Flux monitor 255

IX
Figure 39.1 Graph of Mercury Loss Page

in Water 266

Figure 41.1.1 GC-AA spectra of Pseudomonas

grown on metal-doped slants under

either air or nitrogen atmosphere after

eight days " 271

Figure 41.1.2 Cross section diagram of graphite furnace detector 272

Figure 41.1.3 Gas chromatograph coupled to an atomic

absorption unit via thermostatically

controlled tube and electronic pulse

programmer 273

Figure 41.1.4 Pulsed AA-chromatograms of gaseous

samples of tetramethyltin and trimethyltin 274

Figure 41.1.5 Major reactions and equilibria presumed

to be involved in theGC-GF-AA

System 278

Figure 41.1.6 Atomization efficiency curves for trimethylarsine in a silica-lined graphite

furnace with and without hydrogen added

to carrier gas

Figure 41.1.7 Calibration curves compared for trimethylarsine, dimethylselenium and

tetramethyltin in a graphite furnace. . 280

Figure 41.2.1 Chromatograms obtained by a flame

ionization detector and a mercury flameless atomic absorption detector 281

Figure 41.3.1 Cadmium volatilization by Pseudomonas

sp. grown on Nelson's Medium doped

with 5 ppm CdC12 is demonstrated by

accumulation of transported Cd material

in a separate water absorbing solution

as a function of time 285

Figure 41.4.1 Rate of methylation of mercuric

ion by trimethyltin ion in water

is compared at various total ionic

strengths and with specific gegenions.. 288
Figure 41.4.2 Mercury species are expected Page

to occur at chloride ion concentrations shown 289

Figure 41.4.3 Competetive oxidation of trimethylstibine and trimethylarsine are examined by proton nuclear magnetic

resonance spectrometry 291

Figure 41.4.4 AA calibration curves of five tin

compounds 293

Figure 41.5.1 Example of potential transport chemistry

available for toxic organoarsenials 295

Figure 42.1 Anodic Stripping Voltammetry of Cadmium,

lead and copper from a thin mercury film

glassy carbon electrode plated in -situ.. ^^^

Figure 42.2 Cyclic Voltammetry of methyl mercury

chloride 306

Figure 46.1 GC-MS Analysis of Katalla River

Sediment 319

Figure 46.2 Gas chromatograms of headspace sampled

Mytilus tissue 32i

Figure 46.3 Grand Bahamas sediment 323

Figure 46 . 4 Santa Barbara Sediment 324

Figure 46.5 Liquid Chromatograms of an extract

of Elizabeth River oysters 325

XI
List of Tables

Table 3.1.1

Table 3.1.2

Table 3.10.1

Table 7.1

Table 7.2

Table 14.2.1

Table 14.2.2

Table 16.1

Table 16.2

Table 16.3

Table 20.1

Table 20.2

Table 20.3

Table 20.4

Table 20.5

Zero-field asymmetric rotor- Page

energy levels (E) for HO2 25

HO2 Rotational Constants

[cm-1] 26

Rotational Constants for the

Ground and First Vibrational

State of Chlorine Nitrate (MHz) 41

Concentrations, signals, and calculated

concentrations of standards of NO in

N2 50

Quenching Constants of NO fluorescence

by some Automotive Exhaust Gases 51

Analysis of Sulfate in Rainwater 96

Sulfate in Seawater Analysis 97

Comparison of FID Calibrations by

SRM and EDF 108

Comparison of FID Calibrations by

SRM and by EDF, Initial Results 110

Comparison of FID Calibrations by

SRM and EDF Ill

Lead in Gasoline Fossil Fuel

Standard 129

Lead in Reference Fuel 2.0g

Lead/Gallon Standard 1 30

Lead in Reference Fuel .07g

Lead/Gallon Standard 131

Lead in Reference Fuel .05g

Lead/Gallon Standard 132

Lead in Reference Fuel .03g

Lead/Gallon Standard 133

XII
Table 20.6

Table 20.7

Table 23.1

Table 25.1

Table 25.2

Table 26.1

Table 26.2

Table 27.1

Table 27.2

Table 27.3

Table 27.4

Table 31.1

Table 31.2

Table 31.3

Table 35.1

Table 37.1

Table 37.2

Table 38.1

Effect of Nitric Acid Concen- Page

tration on Recovery of Lead

in Gasoline 134

Effect of Hydrochloric Acid Concentration on Recovery of Lead in

Gasoline 135

Radioisotopes Used for the Analyses

of Neutron Activation 148

Relative Intensities of Elements

in Uncleaned Sample 162

Average of Table 25.1 data and

line intensities 163

Average Attenuation Values of

Parylene Coatings 169

Attenuation Values of Polypropylene and Parafilm Coatings 170

X-Ray Calibration Foils 174

Attenuation Corrections 185

Error Analysis 188

Attenuation Corrections for CSI and

yM Standards 1 90

Sample Compositions 207

Observed net Peak Heights 208

Data for Constant Carbonate

Composition Curves 210

Blank Analysis Due to Sampling

and Filtering Procedure 246

Serial Dilution of Tap Water 252

Serial Dilution of Chlorox 253

Relative Importance of Inorganic

Pollutants and Desired Concentrations

Based on Questionnaire Responses 260

XIII
Table 38.2

Table 41.1.1

Table 41.1.2

Table 45.1

Table 45.2

Table 46.1

Table 46.2

Table 50.1

Table 50.2

Table 50.3

Table 50.4

Relative Importance o£ Organic Page

Pollutants and Desired Concentrations Based on Questionnaire Responses. 261

Calibration Curves for GC-AA Analyses

of Trace Organometal Gases in

Nitrogen 276

Thermodynamic and Kinetic Data Relevant

to AA Detection of Selected Organometals 277

Multielement Water Standard Stored in

Teflon FEP 31

Storage of Multielement Water Standard

in Various Containers 314

Hydrocarbon Content of Sediment

Samples as Expressed in Percentages

by Molecular Weight Region 317

Water Analyses -Fall 1974 Sampling 318

Radiological Pollutant Assurance 336

Traceability tests with health services

Laboratory , USNRC 338

Traceability Tests with EPA Reference

Laboratory Quality Assurance Branch,

EPA-NERC-LV 340

NBS Standards Distributed to State

Laboratories 343

XIV
The NBS Air and Water Measurement Programs

(1974 - 1976)

William H. Kirchhoff

Eileen Myers

Abstract

This report contains a project by project description of progress

and accomplishments in the National Bureau of Standards programs in air

and water measurement covering fiscal years 1974 to 1976. These

accomplishments include the development of new and improved methods

for the measurement of substances in air and water, the development

of standards for the testing and calibration of measurement methods

and the provision of data for relating ambient air or water quality

to emission or effluent levels.

The projects covered in this report deal specifically

with:

Air- -Research leading to development of SRM's (Standard Reference Materials) or other means for ensuring the accuracy

of air measurement methods.

Development of laboratory methods with improved accuracy,

sensitivity and specificity for air pollution measurements.

Generation, evaluation, compilation and dissemination

of data and technical information needed to relate the substances emitted from sources of pollution to those found' in

the atmosphere after chemical reactions have occured.

I
Water-

Evaluation of the accuracy of methods for measuring water

velocity and flow in open and closed channels.

Development of radioactivity standards.

Development of Standard Reference Materials for evaluating the accuracy of instruments and methods for measuring

the concentration of pollutants in water and sediments.

Measurement evaluation and compilation of physical and

chemical properties of known pollutants.

Key Words: Air pollution; Measurement; SRM;

Water pollution
Introduction

Measurement of the concentration and the chemical and physical

properties of substances in air and water provides an understanding

of the extent and effects of pollution. Without accurate measurement

scientists cannot correctly relate health effects to levels of pollution,

engineers cannot correctly assess the effectiveness of control techniques,

regulatory agencies cannot correctly relate levels of pollution emissions

with ambient air and water quality, and the government cannot correctly

make policy decisions concerning compromises among the conflicting

demands of environmental protection, energy conservation and economic

health.

Although an element of uncertainty will always be present in

understanding the environment, the purpose of the NBS programs in

air and water measurement is to provide the means for quantifying and,

where necessary, minimizing the uncertainty associated with assessing

the extent and effects of pollution. It is important to emphasize the

aspect of quantifying uncertainty. It is obvious that minimization of

uncertainty cannot be demonstrated without quantification of uncertainty.

Often, however, the environmental scientist has only vague estimates

of the reliability of the numbers he obtains and it is rare to see reported environmental data accompanied by an estimate of accuracy.

Without such an estimate, data has little significance for those who

would later want to use it. High accuracy may not even be necessary

so long as the limits of reliability of the data are known.

The objective of the NBS programs in air and water measurement is

to provide the basis for determining the accuracy of air and water

measurements and for achieving greater accuracy. This is accomplished

through the development of improved measurement methods, the development

of measurement standards and the provision of accurate technical information.

The NBS role in environmental measurement is derived from the

Bureau's basic statutory responsibility for the accuracy and compatibility

of measurements made throughout the Nation. The Clean Air Act of 1970

and the Water Pollution Control Act of 1972 direct the Administrator

of the Environmental Protection Agency to cooperate with and encourage

3
cooperative activities by all Federal departments and agencies having

functions relating to the prevention and control of air and water

pollution. This is to assure the utilization in the Federal pollution

control program of all appropriate and available facilities and resources within the Federal Government.

Responsibility for management of the NBS air and water measurement

programs rests with the Office of Environmental Measurement in the

National Measurement Laboratory of NBS. Nearly 70 scientists from 12

technical divisions throughout NBS participate in the programs. The

technical results of this effort are directed to a broad cross section

of scientists and engineers in industry. Federal, State and local

governments and private research institutions with responsibilities

for and interests in environmental measurement. However NBS devotes

nearly 1/3 of this effort to assisting other Federal agencies with

special environmental measurement problems related to each agency's

mission.

This report is a project-by-project description of the NBS Air and

Water Measurement Program covering the fiscal years 1974-1976. In order

to give a sunmary description of the program, the projects can be grouped

into the following 10 categories:

Air Program

Measurement Techniques for Trace Gases

Standard Reference Material Development for Trace gases

Measurement methods for Airborne Particulates

Standard Reference Material Development for the Analysis of

Particulates

Atmospheric Chemistry Processes and Data

Water Program

Standards and Guidelines for the Measurement of Water Flow

Standards for the Measurement of Environmental Radioactivity

Methods and Standards for the Measurement of Trace Levels of

Inorganic substances in Water

Chemical Processes and Properties Data
The following list is a sumnary of the major accomplishments of the

air and water measurement programs during the fiscal years 1974-1976:

AIR PROGRAM

Provision of reference materials to ASTM Project Threshold

for collaborative tests of methods for SO^, NO^, sulfation,

dustfall, airborne particles, lead and NO.

Development of a high reliability exponential diluter as a dynamic gas calibration device.

Development of Standard Reference Materials for quartz, toxic

metals and 6 gases for the National Institute of Occupational

Safety and Health for the analysis of hazardous materials

in the work place.

Provision of reference materials for a Collaborative test

performed by the Environmental Protection Agency of a method

for measuring CO in stack emissions.

Development of an absolute coulometric method for measuring NO

in NO2.

Development of gas blend Standard Reference Materials of

CO in N2 and NO in N^. This completed the set of SRM's

developed for automobile emission measurements.

Demonstration of a piezoelectric technique suitable as a personal dosimeter for measuring mercury in air.

Demonstration of a laser-Zeeman detector for NO.

Demonstration of a fluorescence detector for NO.

Demonstration of an acoustic delay technique for the

measurement of automotive exhaust flow with a time resolution

of less than 0.1 sec. Development of a prototype laboratory instrument for the

Environmental Protection Agency for the determination of

particle sizes by the measurement of the ratio of light

scattering at two different forward angles.

Issuance of an NO2 permeation tube Standard Reference Material »»
Development of a thermal generator for trace concentrations

of formaldehyde.

Development for EPA of a "suitcase" blender for preparing

known concentrations of SO2 and CO for field calibrations

of monitoring instruments,

Development of reference materials for EPA for a national

survey of vinyl chloride levels.

Issuance of a lead-in-gasoline Standard Reference Material,

Development of an infrared laser-Stark modulated detector

for the measurement of specific gas phase pollutants and

demonstration of the method for vinyl chloride.

Measurement and characterization of the infrared spectrum of NO^.

Issuance of a report to Senate Labor and Public Welfare

Committee on the adequacy of methods used to determine the

exposure of coal miners to coal dust.

Publication of evaluated chemical rate constants for reactions

of importance in assessing the probable effects of atmospheric

injection of oxides of nitrogen on the stratospheric ozone

layer.

Development and field-test of a prototype atmospheric sulfate

monitor.

Determination of the photochemistry and absorption cross- sections of Freon 11, Freon 12, and CCI4,

Measurement of the reaction kinetics of Freons and Freon

substitutes with hydroxyl radicals using an NBS developed

laser magnetic resonance detector.

Workshop on Halocarbon measurements.

Construction of a compact and stable CO^ laser suitable for

field instrument use in a spectroscopic detector for specific

atmospheric constituents.

Construction and evaluation of a laser Doppler spectrometer

for characterizing the particle size distribution of aerosol

generators and for calibrating particle sizing devices.
Issuance of a stationary source SRM for SO^.

Workshop on Traceability of Calibration Standards,

Development of a tomogeneous urban particulate sample as

a candidate SRM. The material was collected in a bag house

located in St. Louis, Mo.

Construction of a double-beam ultraviolet Dhotoineter as a primary

standard for the accurate measurement of 0^ at concentrations

typical of ambient levels.

WATER PROGRAM

Publication of "A Guide to Methods and Standards for the

Measurement of Water Flow".

Conference on "Flow Measurements as Related to National Needs".

Discovery of a technique for stabilizing ng/g concentrations

of Hg in water and issuance of a trace mercury in water

Standard Reference Materials.

Construction o£ a water samipler with accompanying water sampling

protocol for the analysis of ng/g concentrations of heavy

metals in water.

Preparation of an industrial river sediment Standard Reference

Material certified for its trace metal composition.

Characterization of transalkylation processes between tin

and mercury.

Develooment and test of a deep ocean sampler capable of

retrieving water sample from a depth of 7 miles and maintaining the sample at its ambient pressure.

Determination of the partition coefficients of 22 polycyclic

hydrocarbons between air and water as a function of temperature

and salinity.

Development and verification of a theory for predicting the

values of partition coefficients of aromatic compounds in

water as a function of salinity from related Thermodynamic

properties of these compounds.
Development of a prototype monitor for the measurement of part

per billion concentrations of chlorine in fresh and salt water,

Workshop series on Standard Reference Materials needs for the

analysis of pollution resulting from new sources and uses of

energy.

Development of a trace level multielement in water SRM,

Development of a Standard Reference Material consisting of

freeze-dried homogenized oyster tissue.

'Preparation of a report for the Federal Working Group on Pest

Management on the testing and Evaluation of the Randers Meadows

Model for the distribution of DDT in the Environment.

Verification of a mathematical model for estimation of the

effects of geometry and slope variations on the accuracy of

Parshall Flumes for the measurement of water flow.

Issuance of Environmental Radioactivity Standards fncluding:

Plutonium-239,242 Krypton-85, Xenon-133, Americium-243, Iron-55,

Fresh Water Sediment and several mixed y-ray solution standards.

Publication for EPA of a Bibliography and summary of current

literature on sampling, sample handling and long term storage

for environmental materials.

Development for The National Oceanic and Atmospheric Administration of techniques for the sampling and analysis of trace

quantities of hydrocarbons in natural waters, sediments and

tissues and publication of "Methods for Trace Hydrocarbon

Analysis in the Marine Environment".

Demonstration of a measurement method for organic derivatives

of tin, arsenic, and selenium at nanogram levels.

The period covered by this report, fiscal year 1974-1976, culminated

with the 8th Materials Research Symposium on Methods and Standards for

Environmental Measurement. The five day symposium included over 100

contributed and invited presentations and attracted over 350 participants

from government, industry and imiversities. The proceedings of this
symposium have been published under the title "Methods and Standards

for Environmental Measurements" and is available from the U.S. Government

Printing Office, Washington, D.C, 20402. The stock number is 003-003-01704-03.

This introduction would be incomplete without mentioning that the Air

and Water measurement programs during the 1974-1976 period covered by this

report were under the leadership of James R. McNesby. Dr. McNesby led

the programs since their inception as the "Measures for Air Quality"

program in 1970. The outstanding accomplishments of the program are a direct consequence of his outstanding leadership. Also, during this

period. Dr. Radford Byerly and Dr. Jimmie Hodgeson successively were responsible for the management of the air program and they must therefore

also share in the responsibility for its success. Finally, it should be noted that the entire report was typed by

Ms. Carol Grabnegger, which may be responsible for her decision to begin

a new career as a laboratory technician. Her patience and care are greatly appreciated.

William H. Kirchhoff

Eileen Myers
1 . Automotive Exhaust Flowmeter

Project Leader: B. Robertson, Mechanics Division

Other Personnel: J. E. Potzick

Objective

The eventual, nearly instantaneous measurement of automobile

exhaust pollutant concentration will require equally rapid

measurement of total flow rate so that the mass rate of

pollutant emission can be determined. The aim of this project is to develop and evaluate an essentially non-intrusive

flowmeter for use along with pollutant detectors for measuring

automotive pollutant emissions from the tailpipe. Rapidly

varying flowrates averaging from about 13.6 to 204 g/s (11.3

to 350 i/s)y rapidly varying temperatures up to about 260°C,^

broadband noise levels up to more than 145 dB (re 2 x lO-Spa/,

moisture, particulates, and corrosive contaminants are

expected in the exhaust of a large automobile. For a small

automobile, the average flowrate is expected to range from

about 2.3 to 34 g/s (1.89 to 58 l/s). Maximum permissible

pressure drop is 200 Pa in order not to. interfere with pollution control devices on the vehicle. One millisecond

response time and one percent uncertainty are desired.

Approach

A number of closely related ultrasonic techniques have been

evaluated. In all of them the meter consists of an approximately 5 cm diameter pipe connected to the end of the automobile tailpipe with acoustic waves beamed both upstream and

downstream 5 cm or more through the flowing gas. The gas

drags the sound in the direction of flow so that waves

traveling upstream go slower, and waves traveling downstream

go faster than when the gas is still. The resulting difference

in transit times of the upstream and downstream traveling waves

is obtained using microphones to detect the sound waves and an

electronic circuit for processing. The time difference is

directly proportional to the mass flowrate to be measured.

A new long wavelength version of this technique shows the

greatest promise. In addition to the total mass flowrate,

it provides a direct measurement of the average gas density

so that the volume flowrate can be obtained.

Pa= Pascals= pressure drop

10
Progress

Six earlier ultrasonic techniques are described along with the

reasons for their being discontinued. Finally the present

long wavelength design is discussed in detail, and progress

to date is reported.

The first technique involved placing two microphones equal

distances upstream and downstream from a spark plug, which

was on the opposite side of the pipe from the two microphones. The spark is fired, and the time interval between

detection of the sound pulses is measured. Unfortunately,

the spark jitters in space from one firing to another by an

amount that leads to an uncertainty in the flowrate comparable

to the flowrate to be measured.

The second technique involved replacing the spark by a specially made 1.5 cm diameter electrostatic tweeter. Unfortunately, the tweeter could not be made as loud as a spark,

and hence had no hope of being heard over the exhaust noise.

The third technique involved replacing the spark by a 1.3 cm

diameter 40 kHz piezoelectric transducer and measuring the

phase difference between the ultrasound waves detected by the

microphones. The pipe had to be made of the fibrous part of

acoustic tile in order to minimize reflections, which confuse

the measurement. This meter worked as long as the temperature

was held constant.

The fourth technique involved setting the spark back from the

pipe, and at the end of a 15 cm long, 4 mm diameter 'set back'

tube connected to the pipe. This 'spark tube' method eliminated the spatial jitter of the sound source as did the second

and third techniques above.

A subsequent theoretical analysis showed that all of the above

'divergent path' techniques would be sensitive to temperature

gradients because different temperatures along the two paths

would lead to an uncertainty in the flowrate which could be

an unacceptably large fraction of the flowrate to be measured.

Hence all later designs involved using a coincident path for

the upstream and downstream traveling waves.

The fifth design involved two spark tubes and two microphones,

one pair close together on one side of the pipe and the other

pair on the other side and downstream of the first pair. The

microphone adjacent to the end of a spark tube detects when

the sound pulse is emitted from the tube, and the microphone

across the pipe detects when the sound pulse arrives. For

the other spark tube the roles of the microphones are

n
reversed. The difference in transit times can be computed by

using an up-down counter. This design was not constructed

because of its complexity and because of the difficulty of

producing a loud enough spark while also using sound absorbing walls in the tube in order to minimize reverberations and

increase measurement repetition rate.

The sixth technique involved a 20 kHz and a 40 kHz piezoelectric transducers, each at the end of a set back tube in place

of the two spark sources. The upstream and downstream waves

could be distinguished because their frequencies were different. The phase shift of each of the upstream and downstream

waves due to the dragging by the flowing gas was measured

using the two microphones, and the difference in the phase

shifts was computed using an up-down counter. This method

worked substantially better than all previous ones. However,

there were some unwanted reflections of the ultrasonic waves

perhaps by the metal sound source tubes or by the imperfect

sound absorbing walls of the pipe. The phase of these

reflected waves changed with temperature, and hence their

effect could not be cancelled electronically.

Long Wavelength Acoustic Flowmeter

The experience with the previous acoustic flowmeters has led

to a new design which eliminates their undesirable features.

In this design a loudspeaker driver at one end of the metering

pipe generates a pure tone whose wavelength is longer than

the diameter of the pipe. As a result only the fundamental

sound mode can propagate, and higher modes generated at the

driver and by irregularities in the pipe wall will be quickly

damped. Hence, the entire sound field inside the meter can

be known at all temperatures even though no sound absorbing

material is used.

Another important advantage of using long wavelength sound is

that the flow measurement will be independent of the details

of the spatial dependence of the local gas flow velocity and

density, and depend only on the total mass flowrate and the

average of the density over the cross section of the pipe.

This has been proved using the equations of mass, momentum,

and entropy conservation of an ideal fluid by using pertur- r2i

bation technique , [1] and correction terms have been obtained^ ^ which are small for the present flowmeter design. This

profile-independent flowmeter is highly desirable since its

indication for a given actual flowrate will not vary from

car to car because of differences in muffler and tail pipe

configuration.

12
The sound is detected by three 3.2 mm diameter condenser micro

phones mounted 15 cm apart on one side of the pipe with their

diaphrams nearly flush with the inside surface of the pipe.

The only part of the signal from the microphones that is

needed is the zero or null of the sound wave, since null time

differentials determine the gas velocity (see below).

As a result, the flow measurement does not depend on the microphone gain, which changes somewhat at higher temperatures.

As the temperature and hence the speed of sound in the exhaust

gas changes, the frequency of the sound is changed automatically to maintain the wavelength equal to the spacing between

the first and third microphone. This simplifies the determination of the flowrate so that it is obtained by measuring

a time interval as before. Now, however, the gas density

also can be obtained by measuring the sound frequency.

Theory of Operation

The sound field consists of two oppositely traveling waves

because of reflection of the sound at the end of the pipe.

This field is a function only of longitudinal positional x and time t of the form

p(x,t) = A+ cos(a)t + ^_ + ^J + A.

c-v

cos (cot - — + c+V

*_), (1)

where p is the acoustic pressure, w/Zir is the frequency, c is the effective speed of sound, V is the mean exhaust velocity to be measured, and A+ and (()+ are consrtants . The quantities C and V are given, for v/c <" 1/10, by^>^^

c2 YP

<pv> (2)

where y is the ratio of specific heats, P is the barometric

pressure, p is the local gas density, v is the local gas flow

velocity, and the angular brackets denote an average over the

cross section of the pipe. The averages <p> and <pv> are

related to the total mass flowrate G and volume flowrate Q by

G = <pv>A, Q = <pv>A/< p> where A is cross-sectional

area of pipe.

13
Hence, c and v that appear in the expression for the sound

field depend only on known quantities, like y and P etc.,

and on the G and Q to be measured.

Let ti and tj be the zero-crossing times of the microphones

at longitudinal positions xi and xj , where i, j = 1,2, or 3

Application of trigonometric identities to Eq (1) gives, to

first order in v/c.

V ^ niT/co + ti - tj _

- tan'^ Ji (4)

c^ ^3 "1 oj Xj - s^ '

= rA+2-A.^)sin[oo(xj-Xi)/5] (5)

ji

(A_^'^+A_2)cos[a3 (x • -x^)/c]+2A^A_cos [(jo(x. +x .) /c + (})^ -())_]

and n is an integer, which we can choose to be zero. The frequency (o/Ztt is chosen so that the spacing £ between microphones

satisfies.

^- -i-j. (6)

where iJ- = x? - xi = X3 - X2 and X is the wavelength. Then

0ji = >. and Eq Xa) is substantially simplified. Since I = 15 cm, c - 332 m/s at 0°C, and c"^ is proportional to the

absolute temperature, the frequency 03/211 satisfying Eq (6)

ranges between 1090 and 1520 Hz.

The expressions for the total mass and volume flowrates obtained by combining Eqs (3), (2), (4), and (6) are

G = yPA At/£, (7)

Q + Hi^ £ At, (8)

7T

where At = ti - t2 = t2 - t3 . Now the area A and length I

are kno\m , the barometric pressure P can be measured, and

the specific heat ratio varies slowly with temperature and

equals 1.37 for dirty exhaust, 1.38 for clean exhaust, and

1.39 for humid or dry air. Hence, the total mass flowrate

G can be obtained from a measurement of the time interval

14
At. Also, the volume flowrate Q can be obtained from At

and the frequency oo/Ztt and does not depend upon yP

.

In order for the flowmeter to be able to determine the frequency that satisfies Eq (6) , it must obtain the difference

in time differences: A^t = (t2 - t3) - (tj - t2) . For

frequencies that nearly satisfy Eq (6) , we find from Eqs

(4) and (5) that

A+2-A_2 4A+A- sin ((})+-({).) ,oo£ .2

A2t = ^T ' '"^ (9)

[A_^2+A/ + 2A^A_cos ((j)_^ -(})_)] 2

CO

where we have chosen the origin so that X2 =0. The correct

frequency is obtained when A'^t is zero. Since A2t is a function of t-he frequency deviation squared, the frequency

must be dithered

00 = co„ + CO- sin cOjt (10)

with Wj << coq to determine whether to increase or decrease

the frequency in order to set A2t equal to zero.

Since the response time of the frequency adjusting circuit

must be slower than Ztt/co^^, the above inequality states that

the response time of the flowmeter must be much slower than

1 ms . However, this response time refers only to flow transients, e.g. due to engine acceleration, the effect of flow

pulsations due to individual cylinder firing is not presently

known

.

Construction and Testing

A long wavelength flowmeter consisting of the three microphones, a loudspeaker driver, and a simplified, bread boarded

electronic circuit has been constructed. In this version the

frequency was adjusted manually to get the right wavelength.

Preliminary tests with heated air flowing through the meter

pipe show that the basic physical principles described above

are qualitatively confirmed.

[3 ] A block diagram of the proposed complete flowmeter circuit

is in Fig 1.1 The upper half consists of three channels, one

for each microphone, and circuits for obtaining the time

diferences t]^ - t2, t2 - t3, and tj^ - t3. The last of these

15

I
is used for the flowmeter output, which is proportional to

the total mass flowrate. The lower half of the circuit

adjusts the frequency of the sound so that the wavelength

is held equal to 2Z.

One of the most important parts of the flowmeter circuit is

the synchronous zero-crossing marker. This is a specially

designed^! narrow-banding circuit, which uses a phase sensitive

detector, an integrator, and a voltage controlled phase

shifter, all in a feedback loop. The circuit converts a voltage consisting of a sinusoidal signal plus noise into a clean square wave whose zero crossing accurately marks the

instant when the sinusoidal signal (without noise) crosses

zero. This circuit substantially reduces the jitter in the

measurement of the zero crossing time. The resulting jitter

is given by

^•^^i^rms = V^/C'^Vg/JH), (11)

where Vj^ is the rms noise voltage of bandwidth ^/Ztt, Vg is the

rms signal amplitude, and t is the response time of the circuit. Hence the time jitter can be made arbitrarily small by

slowing the response time.

This circuit has been constructed. Tests on it indicate that

it performs as described. If we assume Vg/Vj^ = 10, 9,/2-n = 150 kHz, and x = 1 ms , the time uncertainty (<5ti);j.j^5 will be

500 ns . The same uncertainty results from a less piercing

signal-to-noise voltage ratio of 1 provided the response

time is slowed to 100 ms

The 500 ns zero-crossing-time uncertainty causes an uncertainty in the flow measurement. Since Vj^^g^ /c = 1/10, Eqs (4)

- (6) give a velocity uncertainty of 1 percent of full scale.

Because of Eq (3) , this gives a flowrate uncertainty also 1

percent of full scale. Since the noise will decrease with

decreasing flowrate, the uncertainty may be expected to

decrease also and remain approximately a constant 1 percent

of reading.

16
3

"5>

ro

i i

o

c

'i

i/> c

o w

o o »_ ^ d «

u o ^

C *- o

(A N C

-

o

c

o

c:w rg

c

"Jrt (AO k. o ^

^ o

0) c

^ -E O <A c tf) E 2

^ s

Figure 1.1 Long Wavelength Acoustic Flowmeter

17

I
References

[1]. Robertson, B. "Expression For The Effect of Arbitrary

Temperature and Mean Flow Profiles On the Speed of

Sound in a Duct." rA)^ J.Aaoust. Soq. Am. _59 S78 ri976')

[2]. Robertson, B. Effect of Arbitrary Temperature and Flow Profiles

on the Speed of Sound In a Pipe, submitted to J. Aaoust. Soq. Am.

[3]. Potzick, J. and Robertson, E. Acoustic Mass Flowmeter for Automotive Exhaust Measurements (A) , . J. Aaoust. Soa. Am. 59_S78 (19761

[4]. Potzick, J. and Robertson, B. A Synchronous Zero Crossing Marker

for Measuring Phase in the Presence of Noise, submitted to MBS

review for publication in Rev. Soi. Instr.

18
2 . Building and Evaluation of a Polluted Air Delivery System

Project Leader: G. P. Baumgarten and F. W. Ruegg, Mechanics

Division

Obj ective

This report describes the building and evaluation of a prototype SOo polluted air delivery system (PADS) . This system is

intended for field use with performance specifications

prescribed by the Environmental Protection Agency.

Approach

The delivery system was built to deliver sulfur dioxide (SO2)

in air at a rate of 5 liters per minute with design

concentrations by volume of 1.0, 0.1 and 0.01 parts per

million. It consists of a diluent air delivery system

utilizing a critical flow sonic nozzle and three separate

concentrated SO2 in air flow systems utilizing laminar flow

porous plugs, one plug for each desired output concentration

(Figure 2.1).

Progress

As seen in the sketch the delivery system is contained in a dispatch case and the two gases are delivered to it from

pressurized containers through detachable supply lines.

Prospective use by unskilled technicians dictated simplicity,

durability and compactness. By maintaining specific upstream

pressures on the critical flow nozzle and the laminar flow

porous plugs of 45 and 12 psig respectively, the prototype

19
PADS produced average output concentrations of 0.76, 0.100

and 0.003 parts per million of SO2 in air based on concentration measurements with an NBS calibrated analyzer. The

expected output concentrations were 0.98, 0.105, and 0.010,

respectively, based on flow calibrations of the individual

components. The uncertainty of the output concentration is

estimated to be about * 10 percent. A detailed description

of the system is to be found in NBSIR 73-414, April 1974.

This work was supported by the Environmental Protection

Agency.

20
PRESSURE GAUGE

PURE AIR —>

P 1 CRITICAL NOZZLE

vT 5 Ipm

.25x10"^ Ipm

^xr\ 2.5x10"'^ Ipm

\

25x10 ^ Ipm

POROUS PLUGS

PRESSURE GAUGE

2000 ppm SO2

Figure 2.1 Polluted Air Delivery System.

01 ppm SO2

1 ppm SO2

1 ppm SO2

21
3. Applications of Infrared Measurements to Air Pollution

Problems

Project Leaders R. Deslattes, Optical Physics Division,

C. J. Howard, NOAA

Other Personnel H. E. Radford, W. J. Lafferty, S. Freund,

H. Layer, P. Schenck, J. Hougen, A. Maki,

Optical Physics Division; Y. Beers,

K. Evenson, J. S. Wells, Time and Frequency

Division; J. Devoe, D. Sweger, E. Hughes,

Analytical Chemistry Division; H. Okabe,

Physical Chemistry Division, and G. E. Streit,

NOAA

Objective

To develop techniques and supporting information for measuring

spectroscopically the concentrations of various molecules

which play a role in air pollution. Currently emphasis is

being placed on measuring and analyzing the spectra of NO2

O3, OH and HO2. The latter two molecules are critical species

in the chemistry of both smog formation and stratospheric

ozone destruction by anthropogenic pollutants. The vital

necessity of understanding its chemical kinetics requires

the development of a quantitative method for its measurement.

This broad project has brought together in concert resources

of 4 NBS Divisions and one sister agency (NOAA)

22
Approach

Techniques and instrumentation are developed to utilize ultraviolet and infrared laser devices in measuring air pollutants.

In order to expand the versatility and specificity of fixed

frequency molecular lasers, absorption modulation techniques

such as the Zeeman and Stark effects are being investigated.

As additional back-up data the high resolution absorption

characteristics of NO2, 0?, and HO2 are being studied. These

techniques exploit the near coincidence of a particular transition in a molecular laser such as CO with an absorption

feature in the spectrum of a pollutant molecule. If the

latter is paramagnetic, its absorption can be brought into

coincidence with the laser emission by the application of a magnetic field (Zeeman effect). If the pollutant is polar, an

electric field can be used for the same purpose (Stark effect)

Continuously tunable IR lasers such as the spin-flip Raman

laser are also used to measure specific pollutant species.

23
3. 1 Laser- Zeeman Spectrum of HQ2

Using a Zeeman-modulated cavity spectrometer with a 10 s time constant and a phase locked klystron, HO2 Zeeman components of the six allowed zero-field lines at 65,070 +_ 2,65,082±2,

65,098 + 2, 65,373 + 2, 65,397 + 2, and 65,401 + 2 MHz, and

of one Forbidden zero-field line at 65,369 +_ 4 MHz, have been

observed in the products of a discharge-flow system[l] The Q

of the Fabry-Perot cavity is about 10,000, and the magnetic

field was swept from to 30 gauss. Chemical tests indicate

that the observed lines are due to HO2 . They have been

assigned and least-squares fitted using a simple theoretical

model, to yield a value of 65,185 +_ 2 MHz for the -^01-^90

asymmetric rotor transition frequency of HO2 , a value of

-208 +_ 2 MHz for the linear combination 1/2 (ebb "^ ^cc) °^ elements of the electron spin-molecular rotation interaction

tensor, a value of -28 +_ 2 MHz for the nuclear spin - electron

spin Fermi contact interaction parameter, a, and a value of

+4 +^ 2 MHz for the spin-spin tensor interaction parameter, X.

The analysis of the laser magnetic resonance spectrum of HO2

has been publishedL ^

» 3] Experiences gained while working on

the details of the HO2 spectrum have been generalized and

have led to the publication of a paperH containing a straightforward and logical, though somewhat lengthy, prescription for

analyzing any future data from laser magnetic resonance spectrometers (e.g. that measured for NO2)

Figure 3.1.1 shows a plot of Zeeman energy levels for HO;

versus applied magnetic field. The circles, squares, an(

triangles indicate allowed laser magnetic resonance transitions of the three types M=0, 1. Diagrams of this nature,

though complicated, have proven to be of great help in

visualizing the relationship between observed spectra and

theoretical molecular energy level patterns.

Table 3.1.1 gives the zero-field asymmetric rotor energy

levels (E) obtained to date for HO2 from the magnetically

•shifted Zeeman spectra, and gives a good indication of the

significant extent of our present knowledge. The column of

observed-calculated values (0-C) indicates the quality of

our theoretical understanding of the data.

Table 3.1.2 gives a set of rotational constants for the HO2

molecule obtained from the asymmetric rotor energy levels in

table 3.1.1 as well as a comparison with rotational constants

obtained from ab^ initio calculations (SCF and CI). Discussions with the ab initio people indicate that they do not

expect any better agreement with experiment than that shown

in the table.

24
Table 3.1.1

Zero-Field Asymmetric Rotor Energy Levels (E) for HO7

HO2 ASYM^TRIC ROTOR FIT (A, B, C, Dj^, Dj^, D^^)

N'(K'^,r) - N"(K"^,K"^) E[cm'^] 0-C[cm"^]

7(2,6)

8(2,7)

11(2,9)

12(2,10)

13(2,12)

14(2,13)

15(2,13)

4(3, 1)

4(3,

10(3,

10(3,

11(3,

11(3,

14(3,12)

14(3,11)

15(3,13)

15(3,12)

18(4,14)

18(4,15)

2)

8)

7)

9)

8)

7(1,7) 58.587 +0.000

8(1,8) 58.833 +0.006

10(1,10) 83.380 -0.002

11(1,11) 85.923 +0.002

12(1,11) 83.531 -0.002

13(1,12) 85.291 -0.004

14(1,14) 93.782 -0.006

5(2, 4) 85.207 -0.001

5(2, 3) 85.201 -0.002

9(2, 7) 117.696 -0.007

9(2, 8) 117.750 -0.002

10(2, 8) 119.852 +0.009

10(2, 9) 119.926 +0.011

13(2,11) 126.198 -0.012

13(2,12) 126.404 -0.007

14(2,12) 128.320 +0.009

14(2,13) 128.588 +0.008

19(3,17) 92.664 -0.000

19(3,16) 92.647 -0.001

25

I
Table 3.1.2

HO2 ROTATIONAL CONSTANTS [cm'-*-]

This Work SCF^ CI^

A 20.357 21.368 20.576

B 1.117 6 1.035 0.938

C 1.056 4 0.987 0.897

^K 0.004 1

^NK 0.000 117

^N 0.000 000 5

a 0.007 4

^Liskow, Schaefer and Bender, JACS 93, 6734

(1971)

26

I
1 10

H in kGauss

20

-0.5

Figure 3.1.1. Zeeman Energy Levels of HO2 and

Magnetic Resonance Transitions

27
The work described above is quite significant, both for the

information which it has produced on the important free

radical HO2 , and because it systematizes and simplifies data

interpretation from the new and sensitive technique of laser

magnetic resonance spectroscopy.

3. 2 Rate Constants for the Reactions of OH with CH4 and

Fluorine, Chlorine, and Bromine Substituted Methanes

at 296 K

The absolute rate constants for the reactions of OH radicals

with CH4 and fifteen fluorine, chlorine, and bromine substituted methane molecules have been measured using a discharge

flow system and laser magnetic resonance detection of OH.

Measurements were made at 296 K and at pressures between 0.8

and 1333 Pa.

The results indicate that the reaction mechanism involves the

abstraction of a hydrogen atom and formation of H2O and a methyl type radical product. Completely halogenated methane

molecules are found to be relatively unreactive. Hydrogen

containing molecules react with rate constants ranging from

about 0.2 to 160 x 10"^^ cm^/molecule'sec . The reactivity

increases with decreasing carbon-hydrogen bond energies.

Rough estimates are made of the Arrhenius parameters for the

reactions

3 . 3 Spectral Measurements on NO2

We have nearly completed high resolution measurements of the

entire infrared spectrum of N02.P~^ 1 The main thrust of the

measurements was to present a complete set of measurements on

the strongest absorption bands, but work was necessary on all

the bands in order to aid in the analysis of the most important

bands. The first analysis of the most important band (V3 at

1617 cm'l) was the subject of a joint publication with Prof.

K. N. Rao and Dr. S. C. Hurlock of Ohio State University .[^

In order to improve on those measurements we have collaborated

with Prof. A. Cabana of the University of Sherbrooke to publish measurements with a four-fold improvement in resolution.t^

This work on the V3 band has been used elsewhere to produce a computer synthesized spectrum to simulate the spectrum of NO2

expected in upper atmosphere measurements. Such synthesized

spectra are vital to the interpretation of spectra obtained

from instrumented balloon flights.

28
Some laser Zeeman spectra of the V3 band of NO2 were also

measureci-'-^ and it was found that several absorption lines

are easily Zeeman shifted into resonance with CO laser transitions. Two laser magnetic resonance patterns for 14n02

and six patterns for 1^N02, observed using six CO laser transitions, have been analyzed to yield spin-corrected Zero-field

vibration-rotation transition wavenumbers and zero-field spinrotation splittings. The planning and analysis of the laser

Zeeman measurements was aided by the earlier analysis of the

V3 band obtained from the conventional infrared grating studies

made in this laboratory. The results from both the laser and

the grating techniques are in good agreement. The 15no2 results allow new values of vq = 1582.107 + 0.008, A'-A'' = 0.2116 + 0.0011, and Dj^ - Dp = 1.39 + 0.20 x 10-4 cm"! to

be determined for the V3 fundamental of that molecule (errors

are 3 standard deviations).

3.

4

Measurement and Analysis of the IR Spectrum of Ozone (Ot;)

The second strongest absorption band of ozone (v]^+V3) has been

measured and a complete analysis of all the strongest transitions is finished. An atlas giving line wavenumber measurements and quantum number assignments has been published .P--^] The line atlas includes a reproduction of the spectrum to

indicate the relative intensities of the different lines.

An expanded version of the spectrum has already been used to

identify ozone absorption lines in spectra of the earth's

atmosphere recently taken at Kitt Peak Observatory.

3.

5

Laser-Stark Spectroscopy

A Stark cell was constructed for use in conjunction with various fixed frequency molecular lasers for measuring the concentrations of pollutants such as formaldehyde, ozone, and

vinyl chloride. Analytical measurements of vinyl chloride

in air have been performed on samples ranging from 0.1 ppm

to 1000 ppm. The sensitivity and linearity over the entire

range produced good results which have been published, t^^]

The results of this early work showed that concentrations as

low as 2 ppm could be measured. Preliminary checks for

accuracy were made using gas mixtures of VCM (vinyl chloride

monomer) in air provided by E. Hughes of the Air and Water

Pollution Analysis Section. Linearity of signal vs concentration was established from 2 ppm to over 1000 ppm.

Subsequent improvements in measurement techniques have

extended the sensitivity to approximately 0.1 ppm. These

29
results were presented at the Pittsburgh Conference in April

1975 and are shown in Figures 3.5.1 and 3.5.2 . Figure 3.5.1

is a reproduction of actual X-Y plotter trace's taken from the

digital oscilloscope used for signal averaging and are

included to demonstrate the S/N ratios. The approximate

averaging times range from 20 s at 95 ppm to 20 min at 0.1

ppm. Figure 3.5.2 shows the analytical curve obtained and

contains the results of three runs taken over a period of

several days. Note that the scale is folded and that the

data are normalized to the 9 ppm sample. Much of the earlier

work was normalized to the 2 7 ppm sample and is not shown here.

Some progress has been made in looking for interferences. A

list of chemicals most likely to be found in an industrial

atmosphere containing VCM was compiled and most of these

chemicals have been obtained. Of the dozen or so chemicals

that have been scanned with the CO2 laser to date there are

no serious interferences with the exception of acrylonitrile

which exhibits a very strong absorption on the same CO2 laser

line as does VCM. It should be noted, however, that acrylonitrile also strongly absorbs laser lines that VCM does not,

and further that there should be no interference between

these two in the CO laser region. Some interference experiments show that several chemicals are strong absorbers of

CO2 laser emissions other than that used for VCM. These

experiments show promise of the extension of this detection

scheme to other important chemicals.

3. 6 Ozone Kinetics Studies

Some kinetics studies have been completed on the reaction of

vibrationally excited ozone with NO, a reaction which may be

of significance to upper atmosphere chemistry [13, 14] .Results

include measurements of the rate coefficients tor the reactions of vibrationally excited ozone with NO, SO, and 02(-'-A).

Rate enhancements have also been observed in the reaction

with atoms. The laser enhanced chemiluminescent reaction

with NO has been used to monitor the rate of deactivation of

vibrationally excited O3 with He, Ar, H2 , N2 , O2 , H2O, CO2,

SO2, CH4, and SF6. From this study it was possible to

separate reactive from deactive processes. Further,

it was shown that the activation energy for O3* + NO reaction

was identical to that of ground state ozone + NO reaction

indicating that vibrational energy requires a given translational energy in order to couple to the reaction coordinate

leading to activated complexes. Further work completed

during FY 1975 includes the effect of vibrational energy on

the + OCS and + C2H4 systems. While these two systems are

not of

30
II

10-

8

' 7

|6

<

a>>

5 -

o 4 -

0)

2 -

I -

t(

t

1 1

t

o Expanded scale

1

20

2

40

4

60

6

80

8

Concentration, pom

Figure 3.5.1 X-ray plotter traces from the digital

oscilloscope used for signal averaging

100

10

31
Vinyl Chloride in Air i

xl60

95 ppm

^M^^^^^VMB

xl6

9.0 ppm

x4 1.2 ppm

xl

0.1 ppm

Figure 3.5.2 Analytical curve and results o£ three

runs of vinyl chloride in air.

32
atmospheric interest they do help in testing models for predicting the effect of vibrational energy on chemical dynamics.

Current studies are underway to measure the rate constant for

the + CIO reaction because of its involvement in stratospheric

chemistry, and to investigate the rates of reactions of CI

atoms with ground state, vibrationally excited molecules,

specifically of atmospheric interest.

Also, a CO laser was used to pump optically the first vibrational level of nitric oxide, NO C v=l) . In a fast flow,

chemical reaction cell the rate constant for the reaction

NO(v=l) + O3 \\ NO9 (^62) + O2 was measured. This constant was com-

, pared to the 'corresponding rate constant for vibrationally unexcited

,reactants NO(v=0) + O3 }C>i NO2 (^Bo) + O2 with the result that K^Kt =2.7,

Since the N-0 bond does not break during the collision leading to'cRemical

(reaction between NO and O3, it was somewhat surprising that the rate

constant was so increased. This is the first direct demonstration that

vibrational excitation in a non-reactive bond enhances chemical reactivity.

3. 7 Sulfur Dioxide Fluorescence

Work on fluorescence of SO2 using a doubled nitrogen laser

pumped dye laser in order to determine the optimum laser

wavelength for use in SO2 monitoring has been completed.

The combination of doubling efficiency with available doubling

'crystals and the fluorescence quantum yield indicated that 220.5 nm is

the optimum wavelength for SO2 monitors using laser induced fluorescence.

Fluorescence from the 220.5 nm band could easily be observed at 2 ppm

(S/N > 20) in air in an apparatus designed primarily for spectroscopic

investigations. The indications are that laser induced fluorescence should

enable monitoring of SO2 at ppb level in a suitable apparatus.

3. 8 Wave Guide Lasers

The performance of several high pressure CO2 wave guide lasers,

which had been constructed during the previous reporting period, have been extensively studied. In addition to their primary asset of being widely tunable (over an order of magnitude

greater than conventional CO2 lasers) they exhibit unexpectedly

high amplitude and frequency stability. While this inherent

stability is not completely understood, it does result in part

from the short sturdy construction of the laser cavity. These

lasers are being used in a study of the saturated absorption

spectroscopy of SiF^ which will help define the limits of

concentration and specificity over which such a system will be useful.

33
3.9 Tunable Semiconductor Laser Applications

A second generation spin flip Raman laser has been completed.

The new system consists of an electromagnet whose field and

sweep parameters are selected by a commercial field dial

controller. The magnetic field range is 0-1 tesla (0-10 k

gauss). A liquid helium dewar with provisions for either

cooling by a cold finger or immersion in liquid helium is in

use. A new CO pump laser of improved design was constructed.

This new laser operates between 1900 and 1700 cm'^. This

laser may be frequency stabilized by locking it to a reference synthesized from a CO2 laser and a kystron. We now

have three different concentrations to choose from for the

InSb resonator. With the second generation system, the

operating range has been extended to between 1900 and 1800

cm"l. The spectroscopic capabilities of the 2nd generation

SFRL and the opto acoustic detector are indicated in an NBS

Tech Note . nsjiMore recently,, infrared frequency synthesis

techniques witn metal-insulator-metal diodes have led to

absolute frequency measurements with our SFRL system.

The molecule of greatest interest at present is HONO, and

the SFRL frequency coverage has not been extended to the

band of interest at 1696 cm-1, thence a brief investigation

as to the suitability of the SFRL for kinetics studies of

other molecules was conducted. This study included monitoring the R^(^) transition in NO in a flow system and using a ratio detection scheme with a polarization dependent beam

splitter. The conclusion we have reached is that the SFRL

is not sufficiently stable in amplitude to conduct kinetics

studies (also reached independently by the SFRL group at

Heriot-Watt) and that its major roles lie in its absolute

frequency measurement capabilities and pollutant identification potential. Further development of the SFRL has been

set aside and the SFRL dewar has been modified to accommodate

a semi-conducting diode laser. A diode laser (whose frequency

will span the 1696 cm"^ band of HONO) and a control unit have

been purchased, and we expect to take the first high resolution

spectra at HONO in the near future. The CO laser operating at

1696.512 cm"l should provide a reference point for the calibration of the spectra.

The production and identification of gaseous nitrous acid

(HONO) is of interest due to the expected participation of

HONO in the chemistry of both the stratosphere and troposphere. A high quality source of nitrous acid, free of

nitric oxide and nitrogen dioxide, is highly desirable both

for spectroscopic and kinetic measurements. To this end the

reaction of gaseous hydrogen chloride with solid sodium

34
nitrite has been suggested. We have investigated the reaction

of HCl with a heated column o£ potassium nitrite (I) on the

NOAA flowing afterglow and are presently trying to make

quantitative measurements of HONO production by iodometric

procedures

.

A HClCg) + KN02(s) ^ HONOCg) + HClCs) (I)

On the flowing afterglow H3O was used as a proton donor and

an attempt was made to monitor the production of H2^^*^ • The

latter, protonated nitrous acid, was observed, but in very

low ratio to NO"*". We ascribe that to the weakness of the

HO. .NO bond which is broken during the proton transfer reaction. The results do indicate production of HONO, but various

tests made on the flowing afterglow with NO and NO2 could not

rule out the possibility that reaction (I) goes partially as:

2HCl(g) + 2KN02(s) H NO(g) + N02(g) + H^OCg)

+2KCl(s).

The iodometric technique being used to attempt to measure the

quantitative production of HONO is to trap the HONO as nitrite

ion in neutral or basic solution. The nitrite ion oxidizes

I to I3 which is then titrated back to I with standardized

thiosulfate solution. Preliminary measurements indicate a yield of 60% or better of oxidant from reaction (I) , but

unfortunately once again HONO cannot yet be distinguished

from a mixture of NO and NO2 (N2OT) which is in fact the

anhydrous form of HONO. This problem is being pursued

further.

35
References

[1

[2

[3

[4

[5

[6

[7

[8

[9

[10

[11

[12

[13

[14

[15

Beers, Y. and Howard, C. J. J. Chem. Phys. 63^, 4212 (1975)

Radford, H. E., Evenson, K. M. and Howard, C. J.,

J. Chem. Phys. 60, 3178 (1974).

Hougen, J. T. Radford, H. E., Evenson, K. M. , and Howard,

C. J., J. Mot. SpeotrosQopy 56^, 210 (1975).

Hougen, J. T. , J. Mot. Speatrosa. 54, 447 (1975).

Lafferty ,W. J. and Sams,R.L. High Resolution Infrared

Spectrum of the 2\)^ Band of m^yMol. Phys . 28_, 861 (1974).

Hurlock,S. C,. Lafferty, W.J. and Rao, K.N. Analysis of the

O3 Band of N O2 J. Mot. Specti-osa. 50^, 2.46 (1974).

Sams, R.L. and Lafferty, W.J. HighResolution Infrared

Soectrum of thp v^ + \j^ Band of 14n1^0^ J. Mot. Speatvoso.

56, 399 _U975) . ^

Cabana, A. Laurin,M. Lafferty , W.J. and Sams, R.L. High

Resolution Infrared Spectra of the u« „„j -, , -a^^A^ r^-c XA 1 <; n T -ni c7 1.1 no cin^?^^^^ 2 U-, Bands ot

14xT Itf. Can. J. Phys. 53, 19U2 (1975). i n U2, —

Cabana, A. ,Laurin,M. , Pepin, C, and Lafferty , W.J. , High

Resolution Infrared Spectra of the u, and u^+Ut-uo Bands

of l^N Oo, J.Mol.SpeatrosQ. 5'9 , 13 U9760 .

" ' 2

Ereund, S.M.., Hougen, J. T. ,andLafferty , W.J. , Laser Magnetic

Resonance Spectra of 14N07and ^^NO^, Near 1600 cm"l.

Can. J. Phys. 5_3,l'3 (1976J.

Maki,. A. G., High Resolution Infrared Spectrum of the 0-,+

Uj Band of O,zone, J^.Mol . Speatrosa. Sl^, 416 (1975).

Freund, S. M. and Sweger, D. M. , Anal. Chem. 4_7, 930 (1975)

Kurylo, M. J., Braun, W. Kaldor, A., Freund, S. M. and

Wayne, R. P., J. Photoahem. 3, No. 2 (1974).

Braun, W. , Kurylo, M. J., Kaldor, A. and Wayne, R. P.,

J. Chem'. Phys., July 1974.

Wells, J. S., Peterson, F. R. , Striet, G.^ E. Goldan, P. D.

and Sadowski, C. M. , NBS Tech Note 670, Jan. 1976.

36

1
5.10 Microwave Spectroscopy of Atmospheric Contaminants

Project Leader: D. R. Johnson, Optical Physics Division

Other Personnel: R. D. Suenram, NBS-NRC Postdoctoral Fellow

1975-1977.

Objective

Over the course of the past decade, there has been a growing

concern about atmospheric contamination. Automobiles and

various industrial processes were recognized early in the

course of analysis as being major contributors to atmospheric

contamination. More recently, the commonly used fluorocarbon

refrigerants and aerosol propellants have presented yet another

type of atmospheric contamination problem. Direct measurements of the concentrations of these contaminating molecules

or their reaction products in the atmosphere have proved to

be extremely difficult. However, the importance of these

measurements to provide bench marks for theoretical calculations cannot be overstated. For many molecules, ground-based

radio astronomical techniques offer a convenient and unambiguous

way of getting information on the vertical profile as well as the column abundance. However, before measurements of this

type can be made it is essential that the microwave spectrum

of the molecule in question be thoroughly studied in the

laboratory. It is the objective of this research effort to

provide detailed laboratory analysis for atmospheric pollutants

that can potentially be observed by astronomical techniques.

Approach

We currently have in operation three independent microwave

spectrometers with special facilities for handling shortlived and reactive molecules. Our spectral coverage parallels

that of the existing radio telescopes and we have had extensive field experience with a variety of radio telescope

systems. Past experience has shown that the molecular transitions that offer the best possibilities for telescope

studies are not necessarily the same transitions that are

easily studied in the laboratory. Our approach is to analyze

the microwave spectrum of the molecule in detail in order to

produce a set of molecular parameters of known accuracy. The

resultant molecular parameters are then used to make a reliable prediction of the entire microwave spectrum of the

molecule. Relative intensities for the various spectral lines

can be calculated with reasonable accuracy once the permanent

electric dipole moment has been measured.

37
Progress

Recently it has been suggested that chlorine nitrate could be

formed under stratospheric conditions by the 3-body reaction

of CIO and NO2.

CIO + NO2 + M -> CIONO2 + M (1)

analogous to the OH reaction

OH + NO2 + M ^ HONO2 + M (2)

Model stratosphere calculations based on these reactions imply

that substantial amounts of CIO may be converted to CIONO2.

CIONO2 could therefore act as an additional "holding tank" for

chlorine and would be expected to decrease the efficiency of

chlorine in destroying stratospheric ozone. Since the laboratory microwave spectrum of CiON02 had not been previously

studied, we undertook its investigation.

An existing microwave spectrometer with a new stainless steel

and Teflon absorption cell was used for the investigation.

The sample was completely contained in stainless steel, Teflon

and Pyrex with the exception of one ground glass joint in the

inlet system which was lubricated with Kel-F grease. Samples

were injected into the absorption cell by allowing CIONO2 to

warm up enough to bring the pressure in the system to over

100 y/Hg. The pressure was then reduced to 20-50 y/Hg before

running by opening the system to the vacuum pump for a few

seconds. It should be emphasized that only when the absorption

cell was cooled with dry ice and the system free of any small

leaks were we able to observe detectable signals from CIONO2

in the gas phase. If the vacuum system was exposed to the

atmosphere several injections of CIONO2 were necessary to

season the cell before the microwave spectrum could be

reproduced.

The microwave spectrum of chlorine nitrate has been observed

and analyzed. The molecule was found to be quite prolate

(k = -0.895) with the dominant electric dipole moment component along the a-principal axis. Hence, the molecule has a "band spectrum" where the most intense transitions follow the

selection rule AJ = +1. The assignment of this particular

spectrum to chlorine nitrate was based on several unique

spectral characteristics. The observed spectrum is that of

a planar molecule with a geometry similar to nitric acid

38
(i.e., A = Ic-Ia-Ib is small and positive). The 37^1 form of

the molecule was readily identified (1/3 the intensity of

^^Cl) and the rotational constants agree well with the expected

mass shift (see Table 3.10.1) Many of the observed transitions

show splittings characteristic of effects from the nuclear

quadrapole moments of a chlorine atom attached to the end of

the molecule. All of this information considered together

offers strong proof that the molecule under investigation is

indeed CIONO2. Stark effect measurements have been carried

out on several transitions of CIONO2 leading to p^ " O-^l ;^ .10 Debye, y^ = 0.22 + 0.02 Debye and y^ = ^

•

During the early stages of these experiments, a new molecular

species was observed in the sample cell. At the time the

sample appeared to have a slightly higher vapor pressure than

it did during the later stages of the experiment. It appears,

therefore, that the sample, as it was originally synthesized,

contained this second molecular species as a slightly more

volatile constituent. Since the new molecule was not anticipated and its microwave spectrum had not been previously

studied, it had to be identified from the spectral characteristics alone. The microwave spectrum of the new molecule was

characterized by intense, a-type, R-branch bands, which were

in many ways similar to those of CIONO2 but shifted somewhat

in frequency.

Spectral assignment has now been completed on the main

isotopic form with the resulting rotational constants:

A = 31578.7 + 1.1 MHz

B = 2691.03 + 0.03 MHz

C = 2560.89 + 0.03 MHz

The B and C rotational constants are not very different from

those of CIONO2 itself but the inertial defect (A = I^,-Ia-I|5)

is quite large, clearly indicating that the new molecule is

non-planar. Thus far, transitions active through dipole

moment components along both the a- and b-principal axes have

been observed. The moment in the c direction has been shown

to be small and may well be negligible. Quantitative measurements of y^ and y]-, have not yet been made but qualitative

comparisons indicate that the moments are about 3 times

larger than their respective counterparts in CIONO2. A

second spectrum essentially identical in character to the

spectrum of the new molecule but with 1/3 the intensity has

also been located. Both the intensity and frequencies of

the individual lines of the new spectrum are consistent with

a molecule containing an isotopic substitution on a single

chlorine atom. Splittings of individual lines much like

those of CIONO2 have also been found in the spectrum of the

39
new molecule implying that the chlorine atom is in an end

position. From the observed set of rotational constants the

molecule must contain at least 3 but no more than 4 atoms in

addition to the CI atom. Considering the starting compounds

used for the preparation of the initial sample it is clear

that these 3 or 4 additional atoms must be formed from some

combination of and N. With all of the evidence in hand we

were forced to conclude that the new molecule is ClONO in a non-planar zig-zag structure. ClONO could well have been

formed during our initial sample preparation through the

reaction,

CI2O + NO + NO2 t

2C10NO (3)

which is analogous to the well known reaction

H2O + NO + NO2 X

2H0N0 (4)

ClONO may be formed under stratospheric conditions by a 3-body

reaction analogous to reaction (1)

CIO + NO + M -»- ClONO + M (5)

The importance of ClONO in stratospheric models can only be

determined when reaction rate and absorption cross section

information become available.

40
Table 3.10.1

Rotational Constants for the Ground and

First Vibrational State of Chlorine Nitrate (MHz)

I

35

CI

V~^~0 A 12108. ± 5.0^

B 2776.96 ± 0.05

C 2258.07 + 0.04

37

CI

12108.2 ± 4.2

2700.91 * 0.04

2207.55 i 0.04

V = 1 A 12008. ± 6.0 12003.5 * 6.0

B 2776.75 ± 0.06 2700.81 + 0.05

C 2262.06 ± 0.05 2211.42 + 0.04

^!he error limits represent two standard deviations

of the fit.

41
4. Electron Energy Loss Spectroscopy

Project Leader: R. J. Celotta, Optical Physics Division

Obj ective

To develop electron energy loss spectroscopy as a gas analysis technique and to determine its sensitivity and advantages

as applied to particular measurement problems.

Approach

The magnitude of the unique electron energy loss spectrum of

a gas or vapor is used to determine its identity and relative

concentration within a gas sample. Data is accumulated on a mini-computer, which can, for simple problems, calculate the

concentrations, or in complex cases, will prepare the data for

analysis on a larger computer.

Progress

The sensitivities for detection of methane, ethane, acetylene,

nitrous oxide, trichloroethylene , trichloroethane , freon 12

and freon 22, in oxygen, were determined by fitting low concentration spectra with pure spectra of the constituents . [Ij

Duplicate measurements and fits were made to estimate the overall reproducibility. The apparatus was improved by a reworking

of its detection electronics and changes in the electron beam

handling powei supplies.

Additional work was performed on determination of oscillator

strengths or photo absorbtion cross -sections , for various

atmosphere gases and pollutants. Determinations were made for

freons 11 and 12 1--', oxygenL^J, acetone [4], methane t^], n-Hexaneland nitrous oxide [6] . The freon results helped resolve a controversy between conflicting optical data.

! References

[1]. Kuyatt, C. E., Celotta, R. J., and Mielczarek, S. R.

The Physios of Eleatronio and Atomic Collisions ^ invited

Lectures and Progress reports of the VIII^^ International

Conference, Belgrade, Yugoslavia, 1973, B. C. Cobic and M. V. I Kurepa, editors, published by the Institute of Physics, Belgrade, Yugoslavia, pp. 681-701.

[2]. Huebner, R. H. , Bushnell, D. C, Celotta, R. J., Mielczarek, S. R. and Kuyatt, C. E., Nature 257 , 376 (1975).

[3]. Huebner, R. H. , Celotta, R. J., Mielczarek, S. R. and

Kuyatt, C. E. , J. Chem. Phys. 63, 241 (1975).

42
[4]. Huebner, R. H. , Celotta, R. J., Mielczarek, S. R. and

Kuyatt, C. E. , J. Chem. Phys. 59^, 5454.

[5]. Huebner, R. H. , Fergurson, C. H. , Celotta, R. J., and

Mielczarek, S. R. Extended Abstracts ^ IN^^ International Conference on Vacuum Radiation Physics. Homberg, July 22-26, 1974,

pp 111-114.

[6]. Huebner, R. H. , Celotta, R. J., Mielczarek, S. R. , and

Kuyatt, C. E., J. Chem. Phys. 6_3, 4490 (1975).

43
5 . Freon Photochemistry

Project Leaders:

Other Personnel

P. Ausloos, A. M. Bass, Physical

Chemistry Division

A. Ledford, R. E. Rebbert

Objective

To determine absorption cross sections and the quantum yields

of photolysis of Freon 11 and Freon 12 in the stratospheric

window region (195-210 nm) , and the photodecomposition of

CCI4, CHjCl, CHFCI2 (Freon 21) and CHF2CI (Freon 22).

Progress

Since chlorine atoms catalyze the chain decomposition of

stratospheric ozone, this project sought to measure quantum

yields of the photolyses of the Freons , the major suspected

source of stratospheric chlorine atoms, and to determine the

modes of decomposition of chlorofluormethanes . An

investigation of the photodissociation of CFCl, (Freon 11)

and CF2CI2 (Freon 12) in the presence of a chlorine atom

interceptor has been carried out in the important

stratospheric window region (195-210 nm) . It was found that

one Freon molecule dissociates per photon. Depending on the

wavelength, decomposition of the Freon molecule may result

in the release of one or two chlorine atoms. The shorter

the wavelength the greater the probability that two chlorine

atoms detach themselves from the photoexcited Freon molecule.

It has furthermore been demonstrated that detachment of a CI2 molecule or an F atom from Freon 11 and Freon 12 occurs

with a very low probability (<0.001).

44
In order to obtain accurate photodecomposition quantum yields

at stratospheric temperatures (200-275K), it will be necessary

to measure the absorption cross section of the Freons at the

temperature and pressure at which the photolysis experiments

are to be carried out. Preliminary measurements carried

out by us at 213.9 nm have shown that the absorption cross

section of Freon 12 decreases sharply at temperatures below

300 K. It follows that values reported in the literature,

which are invariably measured at room temperature (unspecified)

,

cannot be used to determine photodissociation quantum yields

with a high degree of accuracy.

As a follow-up of the investigation of the photodissociation

of CFCl^ and CF2CI2, the CCl. photolysis has been elucidated.

Contrary to recent reports in the literature, absorption of a photon by CCl. does not lead to the elimination of a chlorine

molecule. Instead, at the long wavelength end of the solar

spectrum a chlorine atom is detached with a quantum yield

equal to unity. As was observed in the case of CFCl^ and

CF2CI2, the shorter the wavelength the greater the probability

that two chlorine atoms detach themselves from photoexcited

CCI4.

These photochemical investigations will be extended to establish

the photodissociative channel (S) of CH,C1, which has been

shown to be a major natural source of chlorine in the

stratosphere. In addition, the photodecomposition of possible

chlorofluorocarbon substitutes HCF2CI and HCFCI2 will be

investigated. Preliminary experiments carried m this

laboratory have shown that photoexcited HCF2CI splits out

HCl rather than a chlorine atom. If this judging is

corroborated by further experimentation, it would indicate

that photodissociation of HCF2CI would have relatively little

effect on the ozone layer.

45
6 . Chlorine-Atom Kinetics

Project Leader: Michael J. Kurylo, Physical Chemistry Div.

Other Personnel: Ronald G. Manning and Walter Braun

Objective

The recent inquiry into the possible role that naturally

occurring or man-made chlorine containing compounds might

play in determining the chemistry of the earth's stratosphere

has resulted in an upsurge of interest in chlorine atom

gas phase reactions. Interruption of the Cl-ClO chain can

occur via the reaction

CI + RH ^ HCl + R

whereby CI is converted into less reactive HCl. The most

logical candidates for reactants (RH) are CH^ (abundant

at midstratospheric levels with a mixing ratio (v/v) of

10"^) and CH3CI (10"19 mixing ratio).

Until recently, however, the only direct reaction rate data

for CI atoms with either of these species were obtained for

temperatures at or above 288K. Unlike the reactions of

atoms with CH4 and CH3CI, the CI reactions were observed

to have vastly different Arrhenius A factors and equal

activation energies. A very recent study of CI + CH4

from 218-401 K is in reasonable agreement with the two

earlier studies at 288 Kbut differs significantly from the

values predicted by the only other temperature dependent

study. [1-4]

Approach

For these reasons we have undertaken a systematic study of H

atom metathesis by CI atoms for the following reactions:

CI + CH4 H.-^ HCl + CHj

k

CI + CH3CI ->-^ HCl + CH2CI

CI + CH3F -^^ HCl + CH2F

CI + C2H5 -J-^ HCl + C2H5

46
(

I

Standard flash photolysis resonance fluorescence techniques

were used to obtain rate expressions in units of cm3

molecule" ^s"l.

ki(218-322K) = (7.83 + 1.53) x lO'^^^^^p [_ (2528 + 101)/RT]

k2(233-322K) = (3.36 + 0.71) x lO-^^exp [- (2484 + 113)/RT]

k3(216-286K) = (4.79 + 1.05) x lO'l^exp [- (1595 + 107)/RT]

k4(222-322K) = (7.29 + 1.23) x lO'^^exp [- (121 + 87)/RT]

The results are in good agreement with subsequent resonance

fluorescence studies but conflict with high temperature (>300K)

discharge flow mass spectrometric values obtained for CH4

and CH3CI reactants. The discrepancies are due to either

systematic errors in one or both of the techniques or to

curvature in the Arrhenius type temperature plots. A full

range (200-lOOOK) temperature study is needed to resolve

this difference.

References

[1] J. Chem. SoQ. F.T. (I) 69, 1547 (1973).

[2]. J. Chem Phys. 65, 2126 (1976).

t [3]. J. Phys. Chem. 81, 291 (1977).

[4]. J. Chem. Phys. 66, 2690 (1977).

47
7, The Fluorescence Detection of Nitric Oxide

Project Leader: Hideo Okabe, Physical Chemistry Division

Other Personnel: Frederick P. Schwarz

Objective

Development of a simple, rapid and highly accurate fluorescence

technique to measure the NO concentration in standard reference

mixtures of NO in N2. Investigate the potential application

of this method for measuring NO in automotive exhaust gas and

in air.

Approach

An approach has been adopted based on experience with the

development of the ambient (ppb) SO2 in air fluorescence

monitorP-J The NO absorption begins around 230 nm and proceeds

down into the vacuum ultraviolet. The emission from the

A^z* state of NO excited by the zinc resonance line at 213.86 nm

extends from the resojiance line to 310.0 nm and has a maximum around 260 nm^J. At concentrations in the ppm range,

the fluorescence should be linearly proportional to the

concentration if the 213.86 nm line intensity is constant

and if no self quenching takes place. However, the quenching

of the NOCA^Z*) by NO and gases other than N2 is fairly

efficient.- In the case of NO in N2 , the fluorescence intensity

would become sublinear with respect to the concentration at

high NO concentrations.

Progress

The quenching of the NO fluorescence in N2 by the presence of

third gases was investigated. The gases chosen were H2O

vapor, CO, CO2, C2H4, CsHg, and O2, all of which are present

in automobile gas emissions . "^^

Four runs consisting of 57 measurements of NO in N2 at

concentrations from 250 ppm to 0.0153 ppm were performed in

a static sampling system. The static sampling system consisted

of the fluorescence cell connected to a vacuum system and

a large mixing vessel. An initial mixture of 250 ppm NO in

N2 was diluted successively by N2 in the mixing vessel and a sample of each mixture was introduced into the evacuated cell

and its fluorescence measured. Least squares fits of the

signal, F, to the following equation were calculated.

48
F = A [NO] - BF [NO] + F^

Fq is due to the scattered light from the 213.86 nm radiation

and the fluorescence of NO impurity present in the N2 diluent

gas. B is a constant mainly due to the fluorescence self

quenching of NO. From the values of A, B, and F, determined

in each run, the NO concentrations were recalculated from

the signal measurements. Over 50% of the 57 calculated

concentrations were within 31 of the actual concentrations.

Five different primary standards of NO in N2 were diluted by

a calibrated mass flowmeter and the NO fluorescence measured.

The sampling was done in a flow system where the samples at

flow rates of -lOil/min were continually

passed through the fluorescence cell which was open to the

atmosphere. The concentrations, signals, and calculated

concentrations are presented in Table 7.1. An error of 1.01

in the concentrations yielded a residual standard deviation

of 0.468. The deviation between the actual and calculated

values is less than 1.21. The technique can be applied to

concentrations as high as 932 ppm.

The quenching constants of NO fluorescence by various automotive exhaust

gases are given in Table 7-2.

49
Concentrations, signals, and calculated

Concentrations of standards of NO in N2

Table 7.1.

Initial Mixture Prepared Photon

of NO in N, Cone,

(ppm)

Counts

Cal . Cone

(ppm)

5136 ppm

1067 ppm

1.9171

0.9913

1.515:

20.4 93,424 + 446 20.3

18.6 87,063 + 743 18.6

118 428,307 + 1323 117

122 441,267 + 447 121

123 448,737 + 1429 123

261 823,400 + 3872 258

239 778,520 + 2571 240

932 1,896,227 +10,761 924

316 961,990 + 2362 317

193 652,854 + 2093 193

Parameters

A = 1.03 X

10"-^ ppm"-^

B = 3964

F^= 14,722

Standard Dev.

1.13!

0.4311

6.73!

50
Table 7.2

Quenching Constants of NO fluorescence by some Automotive Exhaust Gases

NO Flucrescence- Quenching Gas

Approximate

Composition

Range in % Vol. of Auto.

Exhaust Gas

Quenching

Constant B

in Torr"^

after Dilution of Sample by 100

to 1 with N2

% Fluctuation

of CjyjQ after

Dilution by

100 to 1 with

N2 at 760 Torr

and at 24°C

13.0 to 13.2 O.90 47 to 47

0.8 to 5.2 0.07 ± .01 to 3

9.5 to 10.2 0.90 39 to 41

-0 0.50

to 0.2 0.10 to .15

to 0.2 0.01 ~0

0.2 to 1.7 0.005 ~0

Total Variation

of the C^o

to 5

Total Variation

without COo

to 3

H20

CO

COo

C2H4

51
52
References

[1], Schwarz, Frederick P., Okabe, Hideo, and Whittaker, Julian

K. , Analytioal Chemistry 46^ 1024 (1974).

[2]. Pearse,R.W.B. , and Gaydon A.G,, The Identifioation of

Moleoular Speatra, 3rd ed. (John Wiley ^Sons , Inc., New York,

1963) pp.269 and 226.

53
8 . Effect of Polymeric Structure on Permeation Tube

Uniformity

Project Leader: D. H. Reneker, Polymers Division

Other Personnel: G. M. Martin, J. D. Barnes

Objective

To identify the sources of variability in the permeation rate

of permeation tubes so that appropriate measures can be

taken to obtain uniform tubing and minimize the cost of SRM

permeation tubes. Presently, each permeation tube is individually calibrated although ideally, only randomly selected

tubes should be calibrated in certifying a lot».

Approach

Observe and describe the morphology of the polymer in the

tube. Identify the morphological variables that have the

greatest effect on permeation rate. Communicate results to

manufacturers of the tubing used in permeation tubes so that

highly uniform batches of tubing can be obtained.

Progress

In work reported previously-^^ an excellent negative correlation of permeation rate with the density of the tube walls

was established for SO2 permeation tubes made from a fluorocarbon copolymer. The least squares line fitted to the data

had the equation P = 102.95 - 46.90p with a residual deviation of 0.02/yg/min where P is permeation rate in yg/min

and p is density in g/cm^. The factors that make the density

vary include essentially all the geometrical features that

cause the polymer molecules to depart from a perfect crystal

structure, such as crystallographic defects, disorder

around chain ends or side branches, disorder in the interlamellar regions and microvoids. The measured density is an

average of the effects of all such defects that are present

in the sample.

The permeation rate also depends on these same geometrical

features, but in an independent way. For example, suitably

connected defect arrays can provide effectively shorter

pathways for the permeation molecule. Unfavorably oriented,

54
defect free lamellae can act as barriers that greatly reduce

the permeation rate since permeation through lamellae is

slower than between them. Neither the way the defects are

connected nor the orientation of the lamellae would necessarily affect the density. Therefore we looked beyond the

density into the morphological details of the sample in order

to identify more fundamental factors which can cause variations in the permeation rate. The dominant morphological

feature of this fluorocarbon copolymer is its tendency to

form stacks of folded chain lamellar crystals a few tens of

nanometers thick. Most of our effort was concentrated upon

the characterization of this lamellar morphology using

techniques such as X-ray diffraction, optical microscopy, and

electron microscopy.

The morphological features that were actually observed in the

walls of these permeation tubes are summarized in Fig. 8,1

which is a schematic diagram of a longitudinal section of the

tube wall. The size (S) of the polyhedral stacks of lamellae

is roughly to scale although the stacks are not as perfect

as indicated. The stacks may be thought of as parts of

spherulites, although the spherical morphology is not well

developed in these extruded tubes. The dark lines represent

the nearly planar boundary regions between the stacks of

lamellae. The thickness of the lamellae (L) is greatly

exaggerated in the diagram. The angle (\> is the angle between

the normal to a stack of lamellae (n) and the radial direction (r) . The parameters S, L, and ^ which characterize_^each

stack of lamellae are all functions of radial position (r)

.

An X-ray beam with a diameter of 200 ym permitted diffraction

patterns to be obtained from regions at radial positions near

the outer surface, the middle, and the inner surface of the

tube wall, as indicated in Fig. 8.2.

The relation between the lamellar thickness (L) values at

different radial positions and the permeation rate are shown

in Fig. 8.3. The lamellar thickness increased from about 26

nm near the outer surface to about 33 nm near the inner

surface. There was also a definite tendency for tubes with

higher permeation rates to have thicker lamellae at all

three radial positions.

An experimental orientation index (n) related to the local

average value of (J) was derived from optical density scans of

the small angle X-ray patterns as shown in Figure o.2. The

value of n was taken as the intensity (E) of X-rays from the

lamellae that diffracted in the axial direction divided by

the intensity (D) from the lamellae that diffracted in the

radial direction. Thus a high value of n means that the

stacks of lamellae had their normals more nearly parallel to

55
the tube axis, that is 4) near 90 . The relation between the

orientation index (n) values at different radial positions

and the permeation rate is shown in Fig. 8.4.

A theoretical model [2] was developed for permeation through

tube walls with the morphological features shown in figure 8.1

Permeation was assumed to occur by different mechanisms in

the regions between lamellae and in the regions between stacks

of lamellae. This model provides a basis for identification

of the parameters which affect the permeation rate and for

estimation of the effect of variation of each parameter on

the permeation rate.

Our efforts on the characterization of the morphological

structure of permeation tubes were described in an invited

talk attended by technical representatives or resin producers

and extruders at a meeting of the Society of Plastics

Engineers in May 1974. An article [2] based on that talk was

submitted for publication. Visits were made to Metronics

Associates who manufacture the SRM SO2 permeation tubes and

to Dohrmann Associates who manufacture an instrument for

measurement of permeation. Contacts were made through lAT

with people at NIOSH and OSHA who are concerned with the use

of permeation tubes as calibrated dispensers of other gases

such as vinyl chloride.

During FY 75 our efforts have been directed toward obtaining

or preparing samples with wider ranges of morphological

parameters and establishing a facility for measuring permeation rates of such samples.

We designed and purchased components for a permeation measuring

facility based on a sensitive gas chromatograph. The gas

chromatograph serves as a means of monitoring the concentration

of permeant gas in a stream of helium carrier which continuously

sweeps the outlet side of a membrane or tube made from the

polymer under test. A valving manifold admits pure carrier

gas, pure permeant gas, or a controlled mixture of carrier

and permeant gas to the inlet side of the polymer sample.

The cell containing the sample is thermostatted in a

controlled temperature bath. This equipment is designed to

permit time-lag-measurements [3], sorption and desorption

measurements, and steady state permeation rate measurements.

Experiments were undertaken in which the density of

commercially available fluorocarbon tubing was modified by

thermal treatment. The density of the fluorocarbon was

found to increase to a value higher than any found

previously in our studies when a length of tubing was

annealed at a temperature just below its melting point.

56
Melting a length of tubing and then quenching it in ice water

yielded no significant change in density. This result

agrees with our assessment that the tubing used in

manufacturing permeation tubes is a highly quenched material.

Procedures were investigated for fabricating samples from

the melt for permeation measurements but more reproducible

methods are needed.

Contacts with the supplier of SRM SO2 permeation tubes to NBS

revealed that this manufacturer had been unable to get his

suppliers to agree to provide fluorocarbon tubing which fell

within certain dimensional tolerances. He therefore offered

no hope of being able to obtain tubing with a specified

density. At the present time, the permeation tube manufacturer makes quality control measurements (length, mass,

diameter, etc.) on as-received tubing and is able to estimate

whether permeation tubes produced from such tubing will be

uniform enough for his purposes. This produces tubes of the

right general rate, but it does necessitate individual

calibration of SRM tubes and might mask other perturbing

effects

.

Given that SO2 permeation tubes must be manufactured at

fairly frequent intervals because they cannot be stored for

a long time period, it might be desirable for NBS to

sequester a supply of fluorocarbon tubing to be furnished

to manufacturers of permeation tubes as they need it to make

SO2 and other permeation tubes for NBS. This would be

expected to reduce the batch-to-batch variations in permeation

rate to the much lower level of the variation observed within

a good batch, thereby permitting NBS to supply the measurement system with a less variable product.

57
\00fjLm

I 1

UJo

QC

(O

(T. UJ

t-O

UJo

s

q:UJ

LONGITUDINAL SECTION I^S(r)—

H

Figure 8.1 - A schematic diagram o£ the structure in a longitudinal section o£ the wall of a fluorocarbon copolymer

tube.

58
-

Figure 8.2 Geometry of the low angle

x-ray equipment . The 200ym diameter

X-ray beam, propagating in the

direction of the arrow passed

through

a longitudinal sectionA. The

X-ray shadow image of an actual

sample is shown at B. The bright

spots show the diameter of the beam

and the outer, middle and inner

positions. The resulting low angle

diffraction pattern is shown at C.

The separation of the arcs

indicatesa lamellar thickness

of 30nm. The orientation

index nv;as defined as the ratio

of the distance E shown on the

axial optical density trace of the

diffraction pattern to the distance D shown on the radial trace.

59
O <1

UJ

O

O UJ

-^-H

t—B—

I

\-%-i

CO

00

c4

Hoi i

i

CM

Ul

I- « <

CM flC O

CM <

±

oi

(M

CM

CM

CM

Ul

CO

CO

CM

CO CM

00

CO CO C4

(uju) SS3N>I3IH1 MVn3l/VV1

CM CM CM

Figure 8.3- Relationship between permeation rate and

lamellar thickness at various positions in the tube wall.

60
00

oi

O

O

DO

<D

(O

c

O <3 D 8 <^

UJ

OC -I UJ Q

O S ^

OC

UJ

UJ

CM 2

D

QC

UJ

Q.

O

o ^n°

CO

oi

CO ca XaONI NOIIVINBIUO

Figure 8.4 - Relationship between permeation rate and

orientation index at various positions in the tube wall.

61
References

[1]. NBS Technical Note 828, Measures for Air Quality (1972-

1973) Annual Report j,psiges 7-10.

[2]. Reneker, D.H., Margin G.M.,Rubing R.J. and Colson,J.P.,

Polymer Engineering and Science 15 No. 1, January 1975.

[3]. Crank J., and Park, G.S.,in Diffusion in Polymers ^'^'p

.

1-37, Crank, J., and Park G.S., Eds., Academic Press, New

York, 1968.

62
9 . Analysis of Mathematical Models of Integrating Monitoring

Devices

Project Leader: R. J. Rubin, Polymers Division

Objective

To provide an analysis of mathematical models for the

diffusion of criteria air pollutants (e.g., 0,, SO2, NO2 , CO)

from a turbulent atmosphere to and through a permeable

membrane to a reactive substrate. Such analyses show how

the barrier- -reactive substrate system acts as a device for

averaging pollutant concentrations during a period of 24 hours,

1 week, or longer. The analyses also show how material

properties, such as gas solubilities and diffusion coefficients,

affect the operation of the device.

Approach

Two models of an integrating monitoring device are considered.

In the first model (Model I) , a permeable membrane backed by

a reactive substrate, the transport of gas through the

membrane is assumed to be governed by the simple one-dimensional

diffusion equation. In a second model (Model II), also

analyzed in terms of a one-dimensional diffusion equation,

reactive sites which act as traps for diffusing gas molecules

are assumed to be uniformly distributed throughout the

membrane. In contrast to the case of Model I for which the

diffusion equation is linear, the diffusion equation describing

Model II is in general nonlinear.

Progress

The simplest version of each of the two model monitoring devices

has been analyzed thoroughly. In the case of Model I, a permeable membrane of thickness £ which is exposed to the

atmosphere is backed by a reactive substrate. The quantity of

diffusing pollutant gas immobilized per unit area by reacting

with the substrate backing in the time interval T is given by

the expression

$ (t~) = D5r'Jftti<^t, T'>r^

or

\(.-r)^ Qt}-^

,

T»^^ (1)

63
where Q = DS is the permeability of the membrane,

D is the diffusion coefficient of the gas in the

membrane,

S is the solubility coefficient (Henry's Law constant)

of the gas in the membrane,

i is the polymer membrane thickness,

p(t) is the ambient partial pressure of the pollutant

gas as a function of the time, t

p is the average ambient partial pressure of the

pollutant gas in the time interval T

t'^ =i 1 /Ott*" i s the relaxation time to establish a steady-state

gradient of gas in the membrane.

For operating times T which are large compared to the

relaxation time, tj^, Model I is a perfect integrator in

the sense that the total amount of gas which is immobilized

per unit area in the operating time interval T is proportional

to the time integral of the partial pressure of the pollutant

gas in that time interval.

In the case of Model II, a permeable membrane which is

exposed to the atmosphere contains a uniform distribution of

trapping sites. The quantity of diffusing gas immobilized in

trapping sites per unit area in the time interval T is given

by the expression

I

* (T) .[jDSn. 5.VlltJ

or

\i-r) ^[2Qn.fl-y- (2)

where n is the initial concentration of trapping sites in

the memorane and where the other quantities have been defined

following Eq . (1). In the case of Model II, the amount of

pollutant gas trapped per unit area of the membrane in the

time interval T is proportional to the square root of the time

integral of the partial pressure of the pollutant in that

interval

.

64
Results and Discussion

The units of ^i^T) and $b:(t) for Models I and II can be

expressed in moles of pollutant gas collected, or immobilized,

per square centimeter of membrane area in the operating time

interval T. In order to compare the collecting

characteristics of monitor Models I and II, we suppose that

each monitor is exposed for 24 hours to an average partial

pressure of a pollutant equal to 5 x 10"^ atmospheres. This

partial pressure corresponds to the maximum allowable

exposure to several criteria air pollutants, namely, 50 ppb.

The quantities of gas collected by the two models under

the^foregoing identical exposure conditions^are denoted by

y^ and ^ . The expressions for ^ and ?

are : ^ ^s.

and

A X .

. -3

§^ = ^M\ iQY\o)^/.\0 rDoles crr,-^

when Q, the permeability, is expressed in the units cm of

diffusing gas at S.T.P., cm (membrane thickness) per second

per cm (membrane area) per cm of Hg pressure difference

across the membrane, where l is the membrane thickness in cm,

and nQ is the concentration of trapping sites in moles cm'3.

Typical values of Q lie in the range [1] lO"!^ to 10"8 so

values of ^ and ^ lie in the range

and

65
_3

The largest value of n^ which might be achieved is no = 10

moles cm" 3 and the smallest value of A which might be used is

10 '2 cm. The optimum estimated ranges for ^ and ^

are then ^ IT

1-^7 KIO'' < ij. < mixio'" moles cm^

and

1.71 X lo""^ < Iff < I'li ^ to^ "«^ ^'""''•

Thus Model II appears to be a better collector than Model I.

At the same time, it should be pointed out that the most

optimistic estimate of the quantity of gas collected in a 24-hour period for the maximum allowable exposure is nevertheless very small.

REFERENCES

[1] Hwang, S. T. , Choi, C. K. , and Kammermeyer, K.

,

Separation Soienae 9, 461-478 (1974).

66
2Q^ Atmospheric Chemical Kinetics

Project Leader: John T. Herron, Physical Chemistry Division

Other Personnel: Robert Huie

Obj ective

The general objectives of this program are the quantitative

understanding of the chemical processes whereby primary pollutants are formed and subsequently transformed into the

noxious compounds typical of polluted urban atmospheres.

Specific goals over the next 2 to 3 years are:

a) Understanding the atmospheric reactions of ozone with

the olefins

b) Understanding the atmospheric oxidation of SO^

c) Understanding the atmospheric oxidation of organic sulfides

Approach

These goals encompass a wide range of chemical species and a large number of chemical reactions, some of which are probably

yet to be identified.

Ideally, the experimental approach should involve both the

study of elementary reactions, and phenomenological studies

of complex systems. An essential component of this type of

approach is a capability for the mathematical modelling of

these systems.

Mathematical and computer capabilities have reached a stage

of development such that real processes and real systems are

now beginning to be quantitatively described in terms of real

chemical (and physical) processes. The model is increasingly

the central element in understanding air pollution chemistry,

and is a major driving force in planning experimental programs.

To contribute towards the goals outlined in the first section,

the following approach is proposed:

A. Phenomenological Studies

1. Stopped-flow Mass Spectrometry. This technique permits the measurement at low pressure (2 to 15 torr) , in

real time, of the rates of change of reactants and products of chemical reactions. Reaction rate constants

67
and mechanisms may be deduced from these kinds o£ experiments. Particular systems to be studied include:

a) Ozone-olefin reactions

b) Oxidation of SO^ in ozone-olefin mixtures

c) Ozone-sulf ide reactions

2. Atmospheric Chemistry Simulation. This involves

studies under real atmospheric conditions of subunits of

air pollution chemistry. For example, the system O3

,

C3H5, SO2; or the system NO, NO2 , C3H5, SO2, hv (u.v.).

The analytical approach to this type of work has not been

chosen. The possibilities include long path infrared,

laser Raman, mass spectrometry, gas chromatography, or

combinations of these and other approaches. Modelling

is an essential element.

B. Elementary Reaction Studies

1. Flow-tube Mass Spectrometry. This involves the formation and reaction of free radicals under steady-state

conditions. Amongst the great many reactions of interest

the following are given as examples:

CH^O

a) HCO + 0^ ^ HCO2 -^ HCO

b) RO2 + SO2 ^ RO + SO3

c) CH3 . O3 ^ CH^O + H + O2

d) S * ^A ^ radicals, st

2. Crossed Beam Mass Spectrometry. This involves crossing two intense beams of reacting gases with detection

of reaction products by means of mass spectrometry. Some

possible reactions to be studied are:

a) SO2 + CH3

b) O3 . CH3

This approach is limited to fast reactions for which

k > 10"^ collision rate.

68
3. Flash Photolysis -Resonance Fluorescence. This is

an approach which hopefully can be made available when

highly accurate rate measurements on simple species such

as H, 0, and OH are required.

C. Modelling

The modelling component o£ this program will be restricted to

the modelling of small scale simulation experiments. Existing

NBS modelling capabilities developed for the NBS fire program,

will be modified and expanded for use in atmospheric chemistry

simulation. Ideally, this capability will be made available

through time-share computer facilities using laboratory sited

computer terminals.

A comprehensive study of significant reactions in the atmospheric chemistry of ozone has been initiated. The initial

part of this work has been concerned with the rates of reaction of ozone with atmospheric pollutants. The reaction O3 + NO2 -^ NO3 + O2 has been studied[l]from 259 to 362K, and the

rate constant found to be k = 9.44 + 2.46 x 10^0 exp (-2509

+ 16/1) cm mol"ls-l.

The major experimental effort has been devoted to studies of

ozone-olefin reactions using a stopped-flow reactor with

photoionization mass spectrometer detection. [2 , 3] product

yields have been measured in real time for O3 + C2H4, C3H5,

iso-C4H8, and cis-2-C4H8.

It was found that rate constants for the reactions of ozone

with olefins in the presence of a large excess of molecular

oxygen were considerably smaller than those measured in the

absence of molecular oxygen. This effect was attributed to

the scavenging of free radicals by oxygen, resulting in

elimination of chain decomposition of ozone.

Rate constants , measured in the presence of molecular oxygen

are as follows (in units of cm^ mol'^s"!):

log k (1-butene) = (9.247 + 0.033)-(1686 + 20)/2.303T

log k (2-methylpropene) = (9.281 + . 026) - (1671 + 23)/2.303T

log k (cis-2-butene) = (9.272 + 0.087)-(956 + 54)/2.303T

.J log k (trans-2-butene) = (9.555 + 0.069)-(1051 + 43)/2.303T

log k (2-methyl-2-butene) = (9. 582+ . 119) - (826+78)/2 . 303T

log k (2,3-dimethyl-2-butene) = (9.230 + 0.237) - (294 + 196)/2.303T

69
A good linear correlation was found between the activation

energy for the reaction and the ionization potential of the

olefin. The mechanisms of the ozone-olefin reactions were

studied using a stopped flow reactor with photoionization

mass spectrometer detection. Product yields have been measured in real time for O3 + C2H4 + C3H5, I8O-C4H8 and cis ||l

2 -C4H8

.

The reactions are complicated by free radical chains involving

OH, HO2, CHO, RO, and RO2 . The primary products are probably

an aldehyde (or ketone) and a biradical intermediate (the

Criegee intermediate or zwitterion)

.

0^ + olefin ^ RCHO + RHCOO

The decomposition or reaction of the biradical leads to the

formation of free radicals. For the ethylene reaction the

postulated mechanism under conditions 0> > C^H. is:

O3 . C^H^ .

HjCOO -I

CH^O + H^COO

"2 ^ C°2

2H + CO2

H + HCO

OH + O2

Products

H^O-^ HCO

HO2 + CO

OH + 202

HCO2 *°2 H

H . O3 . OH + C2H^ H

OH + CH^O -)

HCO + O2 ->

HO2 ^ O3 ^

HCO + 03-^ HCO +0 H + CO2 + O2

Computer modelling of this system using a more complete reac

tion scheme has been carried out using the computer program

of R. L, Brown. The existing photoionization mass spectrometer uses an argon resonance lamp with photon energies no

greater than 11.8 eV. This is not enough to ionize and

detect CO, CO2 , O3, or H2O. It is hoped that use of a neon

resonance lamp (energy, no greater than 16.8 eV) will allow

these products to be detected.

70
A critical question which needs to be answered in these

studies, in whether or not species such as the biradical

intermediate have long lifetimes and hence can qualify as

SO2 oxidizers.

In addition to studying the ozone-olefin system, rate constants were measured for a set of halo-olefins as a contribu'

tion to the stratospheric chemistry program. The rate

constants, at room temperature are:

k(C^H,Cl) = 2.2 X 10^ cm^ mol'^s"-^

2 3

k(C,H_F) '2^3^ = 2.4 X 10^ cm^ mol'-'-s"-^

k(l,2-C2H2Cl2) = 1.4 x 10^ cm^ mol'-^s""^

k(l,2-C2H2F2) = 2-9 ^ 10^ c"^"^ mol"-^s'^

For comparison,

k(C^HJ '2^4 = 1.0 X 10^ cm^ mol'-^s""^

The rate constants reported here are about a factor of 5

greater than had been previously reported on the basis of

relative rate measurements carried out in solution.

Studies of the reaction of ozone with organic sulfides have

also been initiated. These reactions appear to be very fast

but the dependece of rate on concentrations suggests that the

reaction is predominately a free radical chain process in

which the OH radical may play a dominant role.

Some preliminary studies have been made on the reactions of

ozone with organic sulfides. The reactions are surprisingly

fast (comparable to 0_ + C^H ) and indicate a possible

mechanism:

0^ + R-S-R H- (R)2S0* + O2

(R)2S0* -> RSO + R

R + 0_ ^ aldehydes, etc.

71
References

[1] . Huie, Robert E. , and Herron,JohnT. , The Rate Constant for

the Reaction 0,+NO -^ 0^ + NO, Over the temperature Range 259-

362° K. Chem. Fhys. Letters Z_7 ,411 (1974).^

[2]. Herron, John T. and Huie, Robert E. , Application of Beam

Sampling Mass Spectrometry to the Kinetics of Ozone Reactions.

J. Mass Spectrometry Ion Phys. 16_ ,125 (1975).

[3]. Huie, Robert E. , and Herron, John T. , Temperature

Dependence of the Rate Constant for Reactions of Ozone with

some Olefins. J. Chem. Kinetics^ Symp . No

.

1^1975 ^ p. 165.

Publications

Huie, Robert E.,and Herron, John T. , Reactions of Atomic Oxygen

0-^P) w

(1975).

3

(0 P) with Organic Compounds. Progr, Reaction Kinetics 8^,1

Supported in part by the Office of Air and Water Measurement

72
I

11^ Climatic Assessment Program

Project Leaders: David Garvin and Robert F. Hampson

Other Personnel: J. T. Herron, R. L. Brown, R. E. Huie

,

J. D. McKinley, W. Tsang, W. Braun,

M. J. Kurylo, A. H. Laufer, H. Okabe,

L. H. Gevantman, M. D. Scheer

Objective

To evaluate chemical kinetic data on stratospheric reactions

including especially those involving molecules emitted by

supersonic transports cruising in the stratosphere.

Approach

The Climatic Impact Assessment Program of the Department of

Transportation was charged with determining the potential

ecological impact of propulsion effluents from fleets of

supersonic transports flying the stratosphere. For its work

the program drew on ten U. S. Federal departments and agencies

and seven in other countries. Some one thousand scientists

and engineers contributed to the technical outputs.

Stratospheric chemistry involves fifty or so molecules and

free radicals, present at the part per million concentrations

level or less, that can interact in 150 to 200 chemical reactions and photodissociation processes. The principal

interest has been in how these reactions control the amount

of ozone in the stratosphere, thereby determining the intensity of ultraviolet light that reaches the earth's surface.

For simple chemical models (minimal meteorology) the following

types of data are needed:

1) The chemical mechanism, i.e., the specific chemical and

photochemical processes that should be included to make

the outputs meaningful.

2) The rate constant (as a function of temperature) for each

elementary chemical reaction in the mechanism.

3) The optical absorption cross section for each molecule

that can be decomposed by ultraviolet light.

4) The efficiency of photodissociation (quantum yield) for

each molecule that absorbs u.v. light.

73
General questions asked by the CIAP managers are:

a) ViTiat chemistry is important and what can be ignored?

b) What is known about these chemical reactions; for which

are there usable data and for which are measurements

needed?

c) Which laboratories have the capability for making the

measurements?

These questions were answered by kineticists and photochemists

in the NBS Physical Chemistry Division.

The needs of CIAP for chemical data were extensive and varied.

They were met in several ways. First a survey was made of

papers on stratospheric chemistry to determine which reactions

were important and what new measurements were needed either to

improve the accuracy or to fill gaps in the data base. Second,

a workshop for chemical kineticists and atmospheric modelers

was held at NBS in the fall of 1972. This provided a forum

for modelers to describe their needs and experimentalists to

outline measurements that could be made in the near future.

Third, as indicated in the previous section, an initial table

of rate data was developed by the CIAP Chemistry Panel.

Fourth, a data evaluation program was mounted at NBS to

extend these tables and keep them up to date. Four editions

of the tables were issued. The work involved scientists both

at NBS and in other laboratories ^ the results being compiled

and distributed by the Center. Fifth, this evaluation activity was supplemented by compilations of new data, not yet

evaluated.

All of this material was distributed by the Center in a series of reportsLl"!-^ and was made available to the

general public as NBS Technical Note 866.

1

R. J. Cvetanovic, T. Slanger, K. H. Welge, W. H. Breckenridge

,

J. Troe, D. Drysdale, J. Heicklen, D. L. Baulch, D. G. Home,

D. Stedman, R. T. Watson.

74
References

[1]. Hampson, R.F., Ed., Brown, R.L., Garvin, D. , Herron, J.T.,

Huie, R.E., McKinley, J.D., Tsang, W. , Chemical Kinetics

Data Survey I, Rate Data for Twelve Reactions of Interest

for Stratospheric Chemistry ^ NBS Report 10 692 (Jan

1972).

2

[2], Hampson, R.F., Ed., Braun, W. , Garvin, D. , Herron, J.T.,

Huie, R.E., Kurylo, M. J. , Laufer, A.H. , Okabe, H. , Tsang,

W. , Chemical Kinetics Data Survey II. Photochemical

and Rate Data for Fifteen Gas Phase Reactions of Interest

for Stratospheric Chemistry ^ NBS Report lo 828 (April

1972).

[3]. Garvin, D. , and Gevantman, L.H. , Chemical Kinetics

Data Survey III. Selected Rate Constants for Chemical

Reactions of Interest in Atmospheric Chemistry , NBS

Report 10_ 867 (June 1972).

[4]. Johnston, H., and Garvin D., Working Papers for a Survey

of Rate Data for Chemical Reactions in the Stratosphere

,

NBS Report 10_ 931 (Oct. 1972).

[5]. Hampson, R.F., Ed., Braun, W. , Brown, R.L., Garvin, D.

,

Herron, J.T., Huie, R.E., Kurylo, M.J. , Laufer, A.H.

,

McKinley, J.D., Okabe, H. , Scheer, M.D., Tsang, W.

,

and Stedman, D.H. , Survey of Photochemical and Rate Data

for Twenty-Eight Reactions of Interest in Atmospheric

Chemistry , J. Phys. and Chem. Ref. Data^ 2, 2, 267-312

(1973).

[6]. Garvin, D. , Ed., Chemical Kinetics Data Survey IV.

Preliminary Tables of Chemical Data for Modelling of the

Stratosphere^ NBSIR 73-203 (May 1973).

[7]. Garvin, D. , Ed., Chemical Kinetics Data Survey V. SixtySix Contributed Rate and Photochemical Data Evaluations

on Ninety-Four Reactions, NBSIR 73-206 (May 1973).

[8]. Hampson, R.F., Ed., Garvin, D. , Herron, J.T., Huie, R.E.,

Kurylo, M.J., Laufer, A.H., Okabe, H. , Scheer, M.D.,

and Tsang, W. , Chemical Kinetics Data Survey VI. Photochemical and Rate Data for Twelve Gas Phase Reactions of

Interest for Atmospheric Chemistry y NBSIR 73-207 (Aug. 1973)

[9]. Garvin, D. , and Hampson, R.F., Eds., Chemical Kinetics

Data Survey VII. Tables of Rate and Photochemical Data

for Modelling of the Stratosphere y NBSIR 74-430 (Jan.

1974).

75
[10]. Watson, R.T. , Chemical Kinetics Data Survey VIII.

Constants of

(June 1974)

.

ClOj. of Atmospheric Interest , NBSIR

Rate

74-.^16

[11] Hampson, R.F., and Garvin, D., Eds., Chemical Kinetics

and Photochemical Data for Modelling Atmospheric Chemistry, NBS Tech. Note 866 (1975).

NBS Reprots and publications in the NBSIR series that are

still in print may be obtained from the Chemical Kinetics

Information Center, NBS, Washington, DC, 20234.

76
12. A Computer Program for Solving Systems of Chemical Rate

Equations

Project Leader: R. L. Brown, Physical Chemistry Division

A chemical language processor has been developed which

simulates the generation of a computer code for a particular

set of chemical rate equations. This code is then used by

an efficient integrating algorithm to solve the resulting

set of coupled ordinary differential equations. The program

is applicable to spatially homogeneous, isothermal chemical

systems. Reactions are entered in the general form A + B ^

C + D, where any chemical name having up to 10 characters

can be used. Three-body reactions, like A^ +M^A+A+

M can always be written in the general form provided the

concentration of the third body can be considered to remain

constant during the course of the reaction. Three-body

reactions of the form A+B^C+D+E must be written as

two separate two-body reactions. For mechanisms entered in

this form only a simple program is required to calculate the

time derivatives of all the chemical species and the Jacobian

matrix for the set of differential equations. In its

present form, systems can have a maximum of 50 species and

200 reactions. This is not a fundamental limitation. It

can be used for larger systems if several array dimensions

specifications are changed.

77
13. Ultraviolet Ozone Photometry

Project Leader:

Other Personnel

Objectives

Arnold Bass, Physical Chemistry Division

Al Ledford

The objective of this work is to provide a facility for calibration of atmospheric ozone monitoring instruments by use of

ultraviolet absorption photometry. Measurements are required

in the concentration range of 50-500 ppb with an accuracy of

95% or better.

Approach

Recent controversies over the accuracy and reproducibility

of iodometric calibration procedures for atmospheric ozone

monitoring instruments have led to the proposal of ultraviolet

absorption photometry as an alternative calibration method.

In order to examine the nature of these discrepancies it is

planned to intercompare the various methods in use for ozone

concentration- -iodometry, gas phase titration, and ultraviolet absorption photometry. The photometric measurement

will be made by using a double-beam photometer based on the

application of Beer's Law to the absorption by ozone of

253.7 nm radiation. The intercomparison with the other

measurement methods will be done by using a commercial ozone

monitor as a transfer instrument.

Progress

A double- beam photometer has been designed and constructed.

The sample path length in this instrument is approximately

300 cm. The instrument measures changes in ozonized-air

sample transmissions of mercury radiation at 253.7 nm where

78
the photoabsorption cross -section o£ ozone has been well

determined. The background mercury radiation is filtered bytwo narrow-band interference filters. The light is collimated

and passed through a beam splitter which passes approximately

equal intensity beams through the two absorption cells. Clean

air flows through one cell into the ozone generator and then

the ozonized air flows through the second cell. The light

beams emerge from the cells and are recombined in the face of

a photomultiplier tube used in the photon counting mode. A

rotating chopper allows the two beams to be detected sequen- tially so that the transmission of the two cells may be

directly observed.

The entire system has been assembled and preliminary measure

ments have been made. At the 100 ppb level the standard

deviation of the mean of several measurements is approximately 5 ppb.

Future Plans

Future work will proceed as follows:

1) After completing some modification of the mercury lamp,

the photometer measurements will be compared with the

measurements of ozone concentration by iodometry and by

gas phase titration. The photometer will then be

available for intercomparison with ultraviolet photometers in other calibration laboratories;

2) The gas-handling system of the photometer will be modified so that it will be possible to perform gas phase

titration measurements in the photometer. The titration

reaction of ozone with nitric oxide (NO) produces NO7

.

We will measure the concentration of the NO2 produced by

absorption photometry at 435.8 nm. If this measurement

is made with sufficient accuracy, it can provide an

independent method for the calibration of SRM samples

of NO.

79
14 . Gas Standards for Air Pollution Analysis

Project Leaders

Other Personnel

J. K. Taylor and E. E. Hughes, Analytical

Chemistry Division

W. D. Dorko, B. C. Cadoff, W. P. Schmidt,

R. J. Marinenko, D. G. Friend, S. Meeks,

E. Scheide, R. H. Johns (ASTM) , E. R.

Deardorff, D. G. Friend, B. Greifer,

K. Heinrich, R. Myklebust

Objective

This project is concerned with the development of Standard

Reference Materials for air pollution analysis and the provision of traceability of all air pollution measurements,

including those relating to the occupational environment,

to a common set of analytical standards.

Approach

Research is conducted to develop or to improve techniques for

preparation of primary gas standards by gravimetric, volumetric and manometric techniques. Instrumental methods will

be developed for intercomparison of primary standards and with

SRM's to establish the certification levels of the latter.

Absolute methods for the analysis of gaseous mixtures will

also be developed where possible. Studies will be made of

the stability of gas mixtures, as this affects their usefulness as reference standards. The scope of the program

includes measurements in the ambient air, of source emissions,

and of the workplace atmosphere.

80
Progress

14.1 Ozone, Sulfur Dioxide and Nitrogen Oxides

Ozone Reference Standards

An investigation has been in progress to evaluate ozone generators as potential Standard Reference Materials. This

includes a study of factors affecting their performance, and

methods of calibration. The gas phase titration technique,

using SRM nitric oxide-nitrogen as a reagent has been studied

as an independent method of calibration of generators. Coincidentally, the stoichiometry of the neutral buffered potassium

iodide (NBKI) reference method has been investigated.

The effects of temperature, oxygen content of the air, flow

rate, and voltage fluctuations of the UV lamp have been studied

and found to be consistent with predictions from the physical

processes involved. The effect of humidity in the air to be

ozonized was studied in detail and found to be significant.

Reductions in ozone production in moist air as compared with

dry air amounted to 6 percent and 13 percent when the relative humidity was 50 percent and 95 percent, respectively.

However, no significant change in concentration was found

when moisture was introduced into air already containing

ozone.

Studies to evaluate the effect of atmospheric pressure on the

production of ozone by the generator have not yet been undertaken and need to be done.

The gas phase titration (GPT) technique has been developed so

that it can be used as an independent method for calibration

of a laboratory standard ozone generator. This involves the

reaction of ozone with nitric oxide of known concentration

and measurement of the reduction in NO concentration due to

this reaction. A precision gas dilution system utilizes SRM

nitric oxide-nitrogen mixtures as the reagent so that calibration of a generator with reference to this SRM is possible.

Extensiveintercomparisons have been made between the NBKI,

the GPT, and ultraviolet absorption techniques. The UV measurements have been made with a commercial instrument. It

was found that the NBKI method yielded results that were in

general equal to or higher than the GPT. The UV method using

the unmodified commercial instruments gave results that were

20-301 higher than the GPT.

81
The NBKI method was investigated in some detail in terms of

the effects of sample flow rate, the time between completion

of sampling and measurement of the iodine produced, the

strength of the solution relative to KI , and to minor difference in operator technique. It was found that: (a) Variations in sampling time had little effect (less than 3%) as

long as total sampling time was held to 10 minutes or less;

(b) Variations in sampling rate had no effect between the

limits 0.5-1.5 1 min"^; (c) The concentration of KI in the

reagent had a great effect on the absorbance of the solutions

after ozone collection. Under identical analytical conditions, 10% KI reagent yielded a 12% higher absorbance reading

than 1% KI reagent; (d) Minor operator variables, such as

different techniques for rinsing and drying impingers, length

of time between sampling and reading the absorbance, and even

differences in impingers yielded differences in results as

10% or greater.

Neither the chemical method nor the gas phase titration is a simple technique in execution and neither is particularly

satisfactory for routine calibrations unless the laboratory

has had considerable experience in its use. Accordingly the

need for an ozone generator to serve as a calibration source

is emphasized.

An important practical matter undergoing investigation is the

long-time stability of the NBS ozone generator. The information being obtained will answer questions on the frequency of

recalibration and the expected service life of a generator.

The UV lamps in use at present appear to produce decreasing

amounts of ozone as a function of the number of hours the

lamp has been in operation. The decrease is about 1% per

100 hours of operation.

Electrolytic Generation of Ozone

A novel technique for the generation of ozone by electrolysis

of water has been investigated in a preliminary manner. Large

amounts of ozone can be generated by electrolysis of perchloric or sulfuric acid solution at reduced temperatures. The

amount of ozone produced is dependent on the current density

and the temperature of the electrolyte. Several cells were

designed and built which produced ozone in small quantities

and by sweeping air through the cell it was possible to produce concentrations in the range of to 1 ppm.

82

I
Preliminary results indicate that it may be possible to construct a cell capable of producing reproducible quantities of

ozone in this range. Currently it appears that the concentration on a day to day basis, can be reproduced to about +_ 5%

of the amount. It is necessary to operate the cell at 0°C

and to control the current to rather close limits to achieve

the stated degree of reproducibility.

Further work is anticipated, which may improve the reproducibility. Such factors as current control, internal cell

temperature control, dissolution of ozone in the electrolyte

and modification to the electrode to eliminate large bubble

formation will be investigated.

Sulfur Dioxide Reference Materials

The stability of sulfur dioxide-air mixtures at stationary

source concentration levels has been under investigation for

several years. Samples contained in mild steel cylinders

exhibit reasonable stability after an initial conditioning

period. Initially, rapid and unpredictable changes in concentration occur, followed by a gradual attainment of equilibrium. While standards of this kind would be usable they

would require individual calibration and periodic reevaluation

to insure that stability has been reached.

The recent availability of specially treated aluminum cylinders, which have been found satisfactory for several reactive

gas mixtures, suggested a possible alternative to mild steel.

Consequently, five cylinders at each of the concentration

levels of 500, 1000, and 1500 ppm were purchased. Analyses

over a period of six months indicated excellent stability.

Variation in concentration observed during the six month

period lie within the error limits of the method of analysis.

The stability of the samples and the accuracy with which the

concentration can be measured are such that no problems are

anticipated in the production of SRM's of these materials.

Consequently, a set of commercially prepared samples of sulfur

dioxide in nitrogen consisting of twenty-eight samples each

at concentration of 500, 1000, 1500 and 2500 ppm were analyzed.

The analysis was performed using a modification of the peroxide method in which the sulfur dioxide is collected in a dilute solution of hydrogen peroxide in which it is oxidized

to sulfuric acid and is subsequently titrated with standardized

base.

83
The technique was independently validated using a technique in

which the sulfur dioxide is oxidized to sulfate in peroxide

and is then reacted with barium chloride to form the insoluable

barium sulfate. The barium sulfate is then determined gravimetrically. The results of the two methods agreed well within

limits of one percent.

The precision with which the sulfur dioxide could be determined in a sample, the agreement of the two methods, the

uncertainty in standardization of the base and the uncertainties in the measurement of the volume of the gas sample

resulted in a total uncertainty in the concentration of any

sample of about one percent.

These samples are now available as Standard Reference Materials

1661, 1662, 1663 and 1664 which have nominal concentration of

sulfur dioxide of 500, 1000, 1500 and 2500 ppm respectively.

Nitrogen Dioxide Permeation Tubes

Over one hundred nitrogen dioxide permeation devices (see

figure 14.1.1) have been sold by the Office of Standard

Reference Materials. These devices, SRM #1629, were fabricated

and calibrated at the National Bureau of Standards. The

sales records indicate a continuing need for these devices

at a rate of about 50 per year.

Investigation is continuing concerning the life expectancy

of these devices to increase the period of certification to

a period greater than 6 months.

Automotive Standard Reference Materials

This project was concerned with the development of a series

of Standard Reference Materials useful in the measurement of

emissions from mobile sources. The experimental work

included investigation of techniques for stabilizing the

composition of the gas mixtures in high pressure cylinders,

the preparation of specifications by which the mixtures can

be produced by commercial suppliers, and the development of

measurement techniques by which the SRMs can be intercompared

with primary Standards produced in the NBS laboratory. A

further outcome was the design and construction of a semiautomated analytical system for intercomparison of the composition of gas mixtures.

84
TEFLON PERMEATING AREA

Vf)}\

GLASS

. .* • • ;

•

. ; • • .* • • .* v_!>r^ .* • • .* • • .* • •V • •V • •V • • .* • • .* • • .

• • ; • • .• •

.* V^LIQUID '•. *•. *•- -•« -•. -•. '•.NITROGEN '•• -•. '•. DIOXIDES^/* •. •. •. '** '** *• ***•* I '• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• • • ••- ••- ••- ••» • •^^^ ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• •••

• • •• •• •• •• Jr / '^^ •• •• •• •• •• •• •• •• •• •• •• ••

M fifl inzzT

STAINLESS STEEL BANDS

Figure- 14.1.1 Nitrogen Dioxide Permeation Tube

85
The SRMs consist of a series of four binary gas mixtures,

namely: propane-air; carbon monoxide-nitrogen; nitric oxide

nitrogen; carbon dioxide nitrogen. The propane and the carbon dioxide mixtures were found to be stable in mild-steel

cylinders. Coating the inside of steel cylinders with a thin layer of ceresine wax was found to provide long-term

stability of carbon monoxide-nitrogen mixtures.

A pre-treatment process was specified for the nitric oxide

mixtures. This consists of an initial conditioning (soak)

of the mild steel cylinder with a mixture of approximately

twice the concentration of the gas that it will finally contain. After standing for one week, the conditioning mixture

is pumped out and the final mixture is introduced. This

process results in adsorbtion of some nitric oxide on the

walls of the cylinder as evidenced by the fact that some of

this disorbs during blowdown as the pressure in the cylinder

approaches atmospheric. However, no changes in concentration

were observed as long as the pressure in the cylinder is

greater than 400 psi.

The laboratory primary standards are made in stainless steel

cylinders by a gravimetric procedure to a relative accuracy

of 0.1 percent. Intercomparisons of these with the SRMs is

accomplished as follows: For propane - gas chromatography

using the flame ionization detector; for nitric oxide - chemiluminescent measurement; for carbon monoxide and carbon

dioxide - gas chromatography using the flame ionization detector, after reduction of methane.

Techniques were also developed for preparation of the primary

standards and for the determination of impurities in both the

SRMs and the pure gases from which the primary standards are

produced.

A novel semi -automated analytical system was designed and

constructed for intercomparisons of each of these following

gas mixtures with corresponding primary standards: Propaneair; carbon monoxide-nitrogen; carbon dioxide-nitrogen. The

system uses the flame ionization detector as the sensor and

includes a catalytic reduction system for conversion of the

oxides of carbon to methane, prior to measurement.

86
The final outcome of this project has been the certification

and issue of the following Standard Reference Materials:

1665 Propane in air, 2.8 ppm

1666 Propane in air, 9.5 ppm

1667 Propane in air, 48 ppm

1668 Propane in air, 95 ppm

1669 Propane in air, 475 ppm

1673 Carbon dioxide in N2 , 0.951

1674 Carbon dioxide in N2 , 7.21

1675 Carbon dioxide in N2 , 14.2%

1677 Carbon monoxide in N2

,

9.74 ppm

1678 Carbon monoxide in N2

,

47.1 ppm

1679 Carbon monoxide in N2

,

94.7 ppm

1680 Carbon monoxide in N2

,

484 ppm

1681 Carbon monoxide in N2

,

947 ppm

1683 Nitric oxide in N2 , 50 ppm

1684 Nitric oxide in N2 , 100 ppm

1685 Nitric oxide in N2 , 250 ppm

1686 Nitric oxide in N2 , 500 ppm

1687 Nitric oxide in N2,1000 ppm

The gas mixtures are prepared by commercial suppliers, according to NBS specifications. Each SRM cylinder is individually

calibrated at the National Bureau of Standards with respect to

NBS primary standards. The certified accuracy of the composition is generally one percent, relative. The SRM certificate

contains the composition of the specific cylinder and describes

the conditions of preparation and use.

Reference Materials for Collaborative Tests of ASTM Air

Quality Methods" [T]

A three year program for the development of test materials

for the collaboration tests of certain ASTM standard methods

was completed. The work was done by Dr. Richard H. Johns,

Research Associate, sponsored by the American Society for

Testing and Materials. Personnel of the NBS Air and Water

Pollution Analysis Section cooperated. The collaborative

tests were conducted by ASTM in an activity known as Project

Threshold. Both ambient levels and stationary source measurement methods were tested.

Reference materials developed or adapted to these collaborative tests included: SO2 and Nn2 permeation tubes; ozone

generators; potassium sulfate (sulfate measurements); neutral

density filters; dust-fall composition standards; materials

for particulate and vaporous lead in the atmosphere. The

materials were used as quality control samples to check

analytical accuracy or were injected into stacks or ducts

as spikes to check both sampling and analytical measurements.

Techniques for spiking were developed as part of the project.

87
14 . 2 Industrial Hygiene Reference Standards

The Occupational Safety and Health Act requires that national

standards be established for toxic or hazardous substances in

the industrial environment. OSHA must set the standards,

provide regulatory surveillance, and certify instrumentation

used by industry for compliance testing. NIOSH which is

responsible for research in support of the OSHA mission has

requested the assistance of NBS in developing analytical procedures and calibration techniques to be used by that agency

in discharging its responsibilities. Traceability to NBS is

a key consideration, and the techniques are also expected to

be used by industry and equipment suppliers in verifying the

performance of their instruments and quality control measures.

The methods will be relatable to SRM's as far as possible.

The development of new SRM's where no other avenue of establishing traceability is available is a further aim of this

project. The development of analytical techniques and

sampling procedures in specific cases is a logical extension

of this program.

Toxic Materials [2]

A number of materials were prepared as collaborative test

samples and some of them have been precursors of Standard

Reference Materials. Those that have appeared to date are

described below.

SRM 2671 Freeze-Dried Urine Certified for Fluorine

SRM 2672 Freeze-Dried Urine Certified for Mercury

SRM 2675 Beryllium on Filter Media

SRM 2676 Metals on Filter Media (Pb , Cd, Zn, Mn)

SRM 2671 consists of two freeze-dried samples of human urine

containing low (0.8 mg V / I) and elevated (7.1 mg F /I) levels

of fluoride, respectively, when reconstituted with pure water.

SRM 2672 is a similar set of samples containing low (0.05 mg

Hg/il) and elevated (0.29 mg Hg/il) respectively, when reconstituted. The samples were developed primarily for the

industrial hygiene analyst in connection with measurements

of workers to these particular toxic substances.

88
SRM's 2675 and 2676 consist of membrane filters upon which

have been deposited known and carefully reproduced quantities

of salts of the respective metals. Three levels of metal

content have been deposited in each case to simulate the

amounts collected under typical conditions when the workplace

atmospheric concentrations are near the detection level of

commonly used industrial hygiene measurements, at the threshold, and well above the threshold level.

When the samples are used as a series, the analyst may discover whether the techniques he is using give reliable results

or are biased by a constant factor or by a constant amount.

Work is in progress to produce a similar set of filters on

which are deposited mixtures of quartz and clay. The target

values are as follows (yg/filter) : Blank No. 1 No. 2 No. 3

Quartz 30 80 200

Clay 400 370 320 200

The filters were prepared in two steps in which the quartz

was deposited, followed by deposition of the clay. This

permitted measurement of the quartz or randomly selected

filters by x-ray fluorescence (non-destructive) , followed

by chemical analysis of the same filters. As a result, homogeneity could be checked by true techniques, while the method

of preparation and the chemical analysis provided independent

estimates of the quartz content of the filters.

The filters are expected to be available for distribution on

or about October 1, 1976, as SRM 2679, Quartz on Filter Media.

Adsorption Tubes [3]

Previous work at NBS has developed procedures for deposition

of known amounts of organic solvents in charcoal tubes, such

as are used for personal sampling in the work-place atmosphere

The technique makes possible the production of tubes with

levels precise and accurate to + 2 percent of the amount

present. The availability of tEese tubes should greatly

increase the measurement accuracy. Standard Reference Materials are now in the process of preparation and certification

with the following target values (yg/tube)

:

89
Solvent/Tube

Benzene 16 64 256 960

Xylene 43 303 2170 13020

p-Dioxane 18 144 1080 7200

Ethylene 101 404 1616 6060

Chloroform 122 488 1952 7320

Trichloroethylene 268 1074 4296 16110

Carbon Tetrachloride 31 126 504 1890

Gas Blending System

In an Interagency Agreement with NIOSH, a system has been constructed to prepare mixtures of gases in which one component

may be present at concentrations variable from several percent

to a part per million. The starting materials may be either

a pure gas, an organic liquid, or a gas mixture of an intermediate concentration. The system is intended to produce

large volumes, 5 1/m, at a constant concentration for a period of 24 hours. The system will be used to calibrate

gas detecting instruments and devices by the National Institute for Occupational Safety and Health.

The system consists essentially of flow control devices which

allow the mixing of two gas streams in a predetermined and

reproducible ratio. Two or more stages of dilution may be

employed by transferring the gas mixture from one stage to

the next with small non-contaminating pumps. The starting

materials may be a liquid with which a gas stream is saturated

or a pure gas obtained from a cylinder under pressure.

The system is quite flexible in that the components can be

arranged in different configuration to produce a wide range

of concentration of a substance in air from 101 to 1 ppm

starting with the pure substance and a diluent gas.

I!

Reproducibility is excellent and is assured by using calibrated

mass flow meters. In practice this accuracy is assured by periodic calibration of each flow measuring device with a wet-test

meter which in turn has been calibrated by passing a measured

weight of gas through the meter. Mixtures can be prepared

with an accuracy of between 0.2 and 1%, depending on the

extent of dilution and on the peculiarities of the particular

gas mixture being prepared. The accuracy of mixing was confirmed by comparing the concentration of propane produced at

various dilutions with Standard Reference Materials and other

gas standards of known accuracy.

90
Several versions of the system are currently in use in the

laboratories of the National Institutes of Occupational

Safety of Health for use in calibrating gas detecting devices.

Gravimetric Analysis of Gas Mixtures [3]

A method has been developed for measurement of the concentration of gas mixtures by gravimetric measurement of the weight

of a component collected on activated charcoal. The technique

is potentially adaptable to any binary mixture containing a component adsorbable on charcoal and has been found useful

for analysis of those containing the vapors of organic solvents

A measured volume of the gas to be analyzed is drawn through

a tube containing activated charcoal, which has previously

been equilibrated to constant weight. A system, utilizing a critical orifice, has been developed to maintain a steady

rate of flow. Sufficient sample is taken to produce a weight

change of several milligrams for the charcoal adsorber. Measurements of styrene, toluene, benzene, ethylene dichloride,

chloroform, and methylene chloride have shown that a precision

of 1 percent can be obtained at the 50 ppm level.

Solid Sorbent Collection Systems [4]

Another NIOSH sponsored project was concerned with development

of sampling systems based on the collection of the component

of interest on a solid sorber. The sorption can be either

physical or chemical in nature.

Furthermore, the sampling systems need to be applicable as

personal samplers to measure a time-weighted-average exposure,

and compatible with commonly available analytical measurement

methodologies

.

A very effective sorbtion system' was developed for collection

of hydrogen fluoride. The collector is packed with crystals

of sodium acetate which trap the stronger acid as sodium

fluoride, while liberating the weaker acetic acid. By rise

of the fluoride ion selective electrode for measurement, the

combination of collector-analyzer is very specific.

A similar system was developed for measurement of hydrogen

cyanide exposure of industrial workers. The collector consists of flakes of sodium hydroxide contained in a plastic

adsorbtion tube. Again selectivity is achieved by using the

cyanide ion selective electrode for the analytical measurement.

91
Quality Control Analyses

NBS has assisted NIOSH during both FY 1975 and FY 1976 in

connection with the latter 's quality control program. The

Chemical Reference Laboratory of NIOSH periodically issues

samples in its Proficiency Analytical Testing Program (PAT)

.

NBS has been analyzing selected samples from these series for

lead, cadmium, and zinc; for quartz; and for organic solvents

adsorbed on charcoal. These values are used by NIOSH to

evaluate the PAT samples and particularly to assist them in

setting control limits for certification of laboratory

efficiency.

It is expected that the availability of NBS SRM's for many of

these materials will minimize the frequency of test samples

required to establish laboratory proficiency.

Vinyl Chloride Reference Materials [5]

The objective of this work was to provide reference materials

for use in an EPA program to monitor the vinyl chloride concentration in the ambient air. Compressed gas mixtures of

vinyl chloride were needed for calibration of instrumentation.

Quality control samples were also desired consisting of

charcoal tubes with known amounts of vinyl chloride deposited

upon them, corresponding to that obtained by sampling the

atmosphere at three different concentration levels.

Fifteen cylinders containing mixtures of vinyl chloride in

nitrogen were analyzed. These cylinders had been ordered

by EPA from a commercial supplier who shipped them to NBS

enroute to final delivery to EPA. The nominal concentration

levels were as follows: 2 cylinders at '900 ppm; 6 cylinders

at 40 ppm; 7 cylinders at 1 ppm.

The vinyl chloride content was determined by gas chromatographic

analysis by comparison with primary standards prepared at NBS.

The chromatograph used was a commercial model with dual columns

and dual flame ionization detectors. The column used was

3.12 mm (1/8") OD, 1.8 m (6') long packed with Poropak Q and

operated at 100°C. A gas sampling valve with 5 cm^ sample

loops was used for sample injection. The samples and standards were compared by measuring the respective peak areas

using an electronic digital integrater.

The mixtures of vinyl chloride used as calibrants were compounded in our laboratory by partial pressure measurements

to nominal concentrations of 2, 10, 50, 100, and 1000 ppm by

92
volume. The lower concentrations were made by successive

dilutions of the higher concentration mixtures. The calibrant mixtures were compared with existing Standard Reference

Material propane mixtures using the gas chromatograph and the

relative FID response factors for vinyl chloride and propane.

These mixtures had been prepared previous to this project as

part of a study to evaluate the stability of vinyl chloride

mixtures when stored in cylinders.

The samples at the 900 and 40 ppm levels were compared with

the vinyl chloride calibrants at these levels. The relative

uncertainties in the calibrant mixtures were 1.5 percent and

2.0 percent, respectively. The samples at the 0.9 ppm level

were analyzed using the calibrants at 2 and 10 ppm with

relative uncertainty in the calibrants of 2.5 percent.

Charcoal tubes were prepared upon which known amounts of vinyl

chloride were deposited to serve as analytical quality control

standards. The amount deposited corresponded to that which

would have been collected during 24 hours at a sampling rate

of 0.2 1/min, for several concentration levels of vinyl

chloride. The concentration levels were first set at 0.1,

1.0, and 5 ppm respectively and a few pilot tubes were prepared on this basis. The levels were later modified to 0.014,

0.10, 1.0 ppm respectively, and most of the tubes were

prepared accordingly.

The charcoal tubes were supplied by EPA. They consisted of

glass tubes approximately 1 cm in diameter and 16 cm in

length which contained approximately 13 cm of charcoal of

8-16 mesh size. Glass wool plugs had been inserted in each

of the tubes, which had been constricted, to hold the contents in place. Rubber septum plugs were inserted in each

end of the tubes to prevent circulation of air. The tubes

were covered with aluminum foil to exclude light during

storage

.

Each tube, when received, had been given a code number which

was used to identify it.

The tubes were randomly selected from the lot used for atmospheric monitoring and more indistinguishable from others

except by reference to the code number. They could therefore

serve as blind samples for quality control purposes.

The analytical standards were prepared by a method developed

at NBS under an Interagency Agreement with NIOSH l^] . it

consists essentially of drawing a measured volume of gas

through the tubes which are totally immersed in an atmosphere

of gas of known composition. The tubes are attached to

93
matched critical orifices mounted on a circular manifold. Byapplication of a vacuum to manifold the same volume of gas is

drawn through each orifice. The average flow rate for the

critical orifices used was 0.9139 liter/min and no orifice

deviated by more than 0.8 percent of this value.

The manifold is covered with a bell-jar with a gas inlet and

outlet to provide an ambient atmosphere of known gas composition. Twenty tubes can be prepared simultaneously . [3J

.

The amount of vinyl chloride deposited on a given tube can be

calculated from the concentration of the gas mixture and the

volume of gas which was drawn through it. The latter can be

obtained from the length of time of the flow, the calibration

data of the critical orifice, and application of the appropriate correction factor for the pressure drop of the particular

tube.

Selected tubes from the lot were also analyzed, by gas chromatography, to verify the amount of vinyl chloride predicted to

have been deposited. The method consists in desorbtion of the

vinyl chloride from the charcoal, using a known amount of carbon disulfide and gas chromatographic analysis of the resulting

solution. The chromatograph is calibrated with solutions of

known concentration of vinyl chloride in carbon disulfide.

Altogether, 900 charcoal tubes were prepared with the amounts

of vinyl chloride ranging from 12 yg per tube to 3600 yg/tube.

The uncertainty of reported levels was estimated to be 2.5

percent.

Indirect Determination of Sulfate in Natural Waters by Ion

Selective Electrode

The indirect determination of sulfate in natural waters (seawater and simulated rainwater) was accomplished by titration

with lead nitrate solution using the lead ion-selective electrode as the titration sensor. The indirect determination of

sulfate is based on the formation of PbS04 which is quantified by measurements with a lead electrode. The measurements

were carried out in 80 percent isopropanol using a doublejunction reference electrode. The data evaluation was

performed by a Gran plot of the titration of sulfate samples

with standard lead nitrate. Samples containing between 2 and

100 ppm sulfate concentration were analyzed directly, while

94
I

samples of higher sulfate concentration were diluted prior to

analysis. The seawater samples were diluted 100-fold prior

to analysis. A summary of the results are presented in

Tables 14.2.1 and 14.2.2.

Conclusions

Sulfate concentrations in natural waters as low as 3 ppm may

be determined indirectly by using a lead ion-selective

electrode. The accuracy, precision and length of time

required to run the analysis compare very favorably with

other techniques that are generally used for this determination and the range of samples that can be analyzed is

broadened to include rainwater, brackish water and seawater.

By repolishing the electrode frequently, rainwater and seawater samples may be analyzed directly with no sample pretreatment

.

Survey of Analytical Methods t '^l A comprehensive report has been prepared which evaluates the

capabilities of the presently available instrumental methods

for determining traces of 27 important elements in a wide

variety of industrial process fields and waste materials.

The report was prepared by measurement experts in the NBS

Analytical Chemistry Division and the evaluations are based

upon literature surveys and their experience in environmental

materials analysis. Extensive use is made of tabular format

and the evaluations reflect cost-benefit considerations.

Many references to the original literature are given.

Quality Control of Ambient SO2 Measurements [8]

A set of reference materials was developed to serve for quality control and performance evaluation of measurements of

ambient levels of sulfur dioxide by the pararosaniline (PRA)

method. The materials consist of small quantities of sodium

sulfite homogeneously mixed in pure mannitol which serves as

an inert diluent. Such samples can be weighed out and dispensed in vials to simulate the amount of SO2 collected

during a 24-hour sampling period, for various levels present

in the atmosphere.

Two batches, each containing 400 sets, of these materials

were prepared for EPA for use in quality control assessments

95
tNJ

gO

Qi •H ^—

UP

IIU ^O oupo o

(U J-i i-l <D O g

ex

d^C 3 o o

t-H tL, i

(U oo

00

to?l

to o

-^roo

vO vO to o

+1 +1 +1 +1

(SI (SJ LO

O oo

00

CM 00 to ^ 00 o o iH O o

o, o, O, o, o + + + + +

r- to <vj' vO "St LO en• i-H• O• OJ

to 00

LO (MO o oo

to

to

to LO o1-1 ^ 00

PQu

Q

03oo03o Soum

<D T^

to

e:oHP • 3 TJ

rH•HT5

go

a)

m ?H M o (1) :s p. o w o rt LO is * CO '3 •H g

I-H o 03u

*=

?i

Crt tf

0)

O

rH >x

P' rH ^ 8 ctf X5

96
TABLE 14.2.2

SULFATE IN SEAWATER ANALYSIS^

Sample SO. (mg/1)

1 2735

2 2683

3 2760

4 2785

Ave 2741 + 44

aThis analysis agrees very well with the value

of 2717 + 19 mg/jl (n = 10) reported by Luther

and Meyerson [6] which was done by indirect

polarography

.

97
of laboratory performance. A set of 5 samples spanning the

entire range of conceivable SO2 levels. By the use of 5 samples covering the range both addition and multiplication

errors can be identified. The chance for confusion of interpretation, resulting from an outlying sample is also minimized.

While the samples prepared in the above manner were of sufficient homogeneity for the intended purpose, it is recognized

that the mixing of microgram amounts of a solid in gram

amounts of a solid diluent is a difficult process. Accordingly,

alternate approaches were tried. It was found that small

volumes of the tetrachlormercurate (TCM) solution, the absorbtion solution for the PRA method, containing sodium sulfite

can be freeze dried to provide test samples. Such solutions

are quantitatively dispensed into ampoules, freeze-dried, and

sealed under vacuum, preferably. The advantage of this

technique is that the samples are more uniform which may offset the disadvantage of greater cost of preparation.

Samples made by either method are dissolved in a specific

volume of TCM solution and analyzed in the same manner as a sample collected in an atmospheric impinger sampler. The

samples may then be used to evaluate all aspects of the SO2

measurement, except the actual sampling.

Source and Environmental Fate of Toxic Heavy Metals in a Defined Region "

Objective

The purpose of this investigation is to develop and demon- strate an analytical methodology for ascertaining the mass balance of toxic heavy metals in Washington, DC, in order

to identify the information base necessary to effectively limit and control population exposures in urban areas. The

sources, sinks, and the movement into, within, and out of the DC metropolitan area will be considered. The analytical measurements necessary to obtain a mass balance will be established and tested using analytical data obtained by

the DC Environmental Services laboratory. The project was initiated with funding for studies of mercury and was extended to include cadmium and lead.

98
Approach

This project will go through six phases before completion.

These are listed below;

1. Literature Search

2. Sampling Site Determination and Evaluation

3. Sampling and Analysis Procedures

4. Data Collection

5. Data Evaluation

6. Final Report

Phases 1, 2 and 3 have been essentially completed. The data

collection (phase 4) will begin during the next month.

Progress

A literature search has been conducted in order to determine

the state-o£-art in heavy metals analysis, especially the

analysis of environmental samples for mercury, cadmium and

lead. Reports have also been obtained concerning environmental studies of similar scope and objectives as this one

done in other parts of the country. The literature has also

been scanned for information concerning sampling and storage

of environmental samples.

Solid waste, sewage and drinking water flow charts for

Washington, DC have been drawn, and copies of these are

included with this report (Figures 14.2.1 and 14.2.21. A sampling

schedule has been devised and a map showing the sampling

sites is also included with this report (Figure 14.2.3).

The air samplers are being constructed and the analytical

and calibration techniques are being worked up for these

s amp 1 e s . NBS standard reference materials have been sent to the Blue

Plains laboratory for analysis and the results have been

obtained and discussed. Several changes have been recommended

and the Blue Plains analyst (s) will spend some time at NBS

going over these procedures and obtaining additional specialized atomic absorption training.

Voluntary Standards Participation

A number of NBS scientists and particularly members of the

staff of the Analytical Chemistry Division, participate

actively in the program of work of ASTM committee D-19 on

Water. Accordingly, a cost center was established during

Fiscal Year 1976 to support this activity and to provide for

more active participation where it is desirable to do so.

99
1000

u w

1-95 (2000)

Landfill

400 I

00

Va.

DC Govt, Federal

480

Oxon Cove

Landfill

Cherry Hi

Landfill

350

Mt Olivet

(400)

Transfer Sta

Incinerator

#5 (950)

Service

Areas

I

42

NJ & K

(480)

Transfer Sta

d'(h<h(§^S^iD&(h (h

Private Haulers

Total DC Solid Waste = 950 + 400 + 480 + 100 + 42 = 2000 tons/day

1-95

351TM tlOOG

Oxon

Cove

. -DC2000 —42

¥

Cherry

Hill ,,600

Incinerate

600

Air

1

Incinerator

T

Sewer

Ash

I

Landfill

Figure 14.2.1 Solid Waste Flow Diagram

100
Rainfall

POTOMAC RIVER

WSSC

£

MO.

09

BLUE

Dalecarlia

ttt:

D.C.

Primary

Secondary

sludge

li

VA.

PLAINS

POTOMAC RIVER

Figure 14.2.2 Water and Sewage Flow Diagram

101
Figure 14.2.3 Map showing sampling sites.

102
A total effort of approximately 0.4 man years was devoted to

this activity, consisting of attendance at meetings, review of

manuscripts, drafting of proposed standards, and participation

in collaborative tests of proposed standard methods.

REFERENCES

[1] Johns, R. H. , Taylor, J. K. , Reference Materials for

Collaborative Tests of Air Quality Methods, TN 840 (1974)

[2] Mavrodineanu, R. , Baldwin, J. R. , and Taylor, J. K.

,

Development of Reference Materials for Atmospheric

Analysis of the Occupational Environment: Filter

Samples Containing Toxic Metals, NBSIR 73-256. October

1973; Taylor, J. K. , Deardorff, E. R. , Olson, C. D., and

Burke, R. W. , Preparation of Simulated Environmental

Filters Containing Quartz and Clay, NBSIR 73-400^.

October 1973; Rains, T. C, Olson, C. D. , Velapoidi,

R. A., Wicks, S. A., Menis, 0., and Taylor, J. K.

,

Preparation of Reference Materials for Stationary

Source Emission Analysis: Beryllium, NBSIR 74-439

(1974) .

[3] Cadoff, B. C, Hughes, E. E., Alvarez, R. , Taylor, J. K.,

Preparation of Charcoal Sampling Tubes Containing

Known Quantities of Adsorbed Solvents, NBSIR 74-630.

(1974) .

[4]. Greifer, B., Cadoff, B. C:, Wing, J., and Taylor, J. K.

,

Development of Solid State Samplers for Work Atmospheres,

NBSIR 74-527, 54 p. (1974); Greifer, B. and Taylor, J. K.

Development of Solid State Samplers for Work Atmospheres:

Phosphine, NBSIR 75-977^ 31 p (1976); Cadoff, B. C. and

Taylor, J. K. , Development of a Solid Sorption Tube and

Analytical Procedure for Hydrogen Cyanide in the Workplace Atmosphere, NBSIR 76-998> 25 p (1976); Wing, J.

and Taylor, J. K. , Development of a Solid Sorption Tube

for Sampling Hydrogen Fluoride in the Work Atmosphere,

NBSIR 74-581 SS p (1974).

[5]. Cadoff, B. C, Dorko, W. D., Taylor, J. K. , Vinyl

Chloride Reference Material, EPA (1975); Hughes, E. E.,

Dorko, W. D. , Freund, D. , Sweger, D. M. , Preparation and

Evaluation of Vinyl Chloride Standards, Proc. for International Symp. on Environ. Monitoring, Las Vegas (1975).

103
[6]. Luther, G. W. Ill and Meyerson, A. R. , Anal. Chem. 47

(12) 2058 (1975).

[7].Greifer, B. and Taylor, J. K. , Pollutant Analysis Cost

Survey, EPA-640/2-74-125, 208 p (1974).

[8]. Taylor, J. K. and Deardorff, E. R. , Sulfur Dioxide

Reference Materials, NBSIR 75-662^ le p (1975).

104
15. Calibration Standards by Thermal Decomposition

Project Leader:

Other Personnel:

Objective

Wing Tsang, Physical Chemistry Division

James Walker, Physical Chemistry Division

and Douglas Cornell, Fairleigh-Dickensen

University

a) To demonstrate the feasibility of generating dilute,

known quantities of pollutant gases which are not readily

contained in steel cylinders.

b) To construct an apparatus which will permit the continuous

generation of dilute concentrations of pollutant gases.

Approach

Thermal decomposition of appropriate "parent" compounds

Construct a demonstration prototype.

Progress

Three reactive gas generators have been constructed and

tested. One has been delivered to the Center for Fire

Research and another to the Office of Air and Water Measure

ment . The reactive gases that can be generated by this

instrument are HCHO, CH.CHO, CH2CHCHO, SO2, HCN, and HCl.

The specific reactions are

105
CH2 = C(CH3)CH2CH20H -> iC^Hg + HCHO

CH2 = CHCH2CHOHCH3 -> CjHg + CH3CHO

CH2 = CCCHJKH2CHOHCH = CH2 ^ iC^Hg + CH2CHCHO

(CH2)3S02 - ^-^3^61^ ^

* SO2

CN C00C2Hg - HCN + CO2 + €2^^^

A large variety of other thermally stable pollutants can be

generated in this manner. These include CO from the reaction

orl-dicyclopentadienol -> cyclopentadiene + butadiene + CO

and NO from the reaction

CH3CHONOCHONOCH3 -» 2CH3CHO + NO

An unexpected application of the generator occurred in recent

successful efforts in Herron's laboratory to calibrate mass

spectral analyses of formaldehyde, a product of combustion

and smog reactions.

Several papers have been published [1-4] .others are being

^prepared' [5,6] and a patent is being sought.

References

[1]. Tsang, Ylingy Journal of Research of the National Bureau

of Standards, 7_8,157 (1974).

[2]. Cornell, Douglas and Iss.Tig^'^i.TigyAnalyt-ioal Chemistry

,

45,933 (1974).

[3]. Cornell, Douglas and Tsang, Wing, International Journal

of Chemiaal Kinetias , 7 AA , (^197 S) . [4]. Walker, J. A. and Tsang, W. ,/l755Ji? 7^- Z^C)^^ January 1976.

[5]. Tsang, W. and Walker, J. A., An instrument for the Generation

of Reactive Gases ysubmitted to Analytical Chemistry

.

[6]. Cornell, D. and Tsang, W. , Pyrolysis Generation of Dilute

Concentrations of Carbon Monoxide , submitted to Analytical Chem.

106
16, Gas Dilution Calibration Techniques

Project Leader:

Other Personnel:

J. J. Ritter, Inorganic Materials Division

N . K . Adams

Objective

To examine experimentally the capabilities and limitations of

the NBS exponential dilution flask as a certifiable device

for the rapid calibration of fast-response air monitoring

equipment.

Approach

The performance of the NBS-developed exponential dilution

flask (EDF) was evaluated by comparison to currently available

propane-air Standard Reference Material (SRM) mixtures.

Several operational procedures involving the NBS dilution

flask were examined in an attempt to establish a realistic

method for the use of the EDF in the calibration of a flame

ionization detector (FID). The performance of the NBS-EDF

was compared to that of a conventional EDF.

107
Progress

Several approaches were studied in the application of the

NBS-EDF to the calibration of a FID. Two practical procedures

were developed. The first involves the introduction of an

approximately known quantity of pure calibrant gas into the

operational dilution flask and utilizing the resultant data

to compute the detector linearity factor, n. [The factor, n,

is simply the ratio of the slope of a plot of the logarithm

of the observed signal vs. time to the theoretical slope

computed from the volume of gas involved in mixing and gas

flow rate.] A single high-level response-concentration

relationship (^o^ (within the concentration region covered

by the dilution® curve) for the FID is established with a

propane-air SRM. All responses (S) above or below the SRM

gas level can now be expressed in terms of calibrant concentration (c) by the use of the equation S = £0 c^.

Typical results obtained by this procedure are given in Table

16.1.

Table 16.1 Comparison of FID Calibrations by SRM and EDF*

^SRM ^EDF *^EDF

93.9 92.0 0.7

46.3 Calibration mixture

9.51 9.62 0.05

2.96 2.97 0.05

*46 ppm SRM used to establish a reference point on the

exponential curve.

108
The second method requires the introduction o£ a precisely known

quantity (Nq) of pure calibrant gas into the dilution flask

and an integration of the area (A) under the resultant curve.

The linearity factor (n) for the detector is obtained as before,

the carrier gas flow rate (r) measured and the volume of

carrier gas in the flask under actual operating conditions

(Vjn) must be determined. The response (S) is related to

sample concentration through the following equation:

The latter technique does not require the use of a precalibrated

SRM gas mixture, but necessitated the development of a precision sample introduction device to be used in conjunction

with the EDF.

Comparative FID calibrations were conducted utilizing four

propane-air SRMs and the NBS EDF operating with air as a carrier gas and measured amounts of pure propane calibrant.

The results are given in Table 16.2.

From Table 16.2 it will be noted that all of the c values

obtained from the EDF are consistently low compared to the

certified SRM values. Investigations into probable causes for

this, disclosed that the carrier air contained about 6% more

oxygen than the SRM diluent air. Carrier air of comparable

O2 content was obtained and the calibrations were repeated.

The results are shown in Table 16.3.

The data in Table 16.3 show that the agreement between the

certified SRM values and the EDF values is now improved except

at the high level where a bias still persists. The contents of

the SRM cylinders were reanalyzed using gas chromatographic

methods, and by comparison to standard gravimetric C3-Hg-air

mixtures, shown to be essentially unchanged. During the reanalysis it was also demonstrated that the use of the SRM

delivery system did not affect the delivered propane concentrations . The results of calibrations using the alternative method based

upon an exponential curve and a single SRM calibration point

on that curve are given in Table 16.2.

109
I

Table 16.2. Comparison of FID Calibrations by SRM and by

EDF, Initial Results

^SRM

ppm „ UjHg

in air v/v ^EDF ^EDF

93.9 89.8 0.1

46.3 43.8 0.3

9.51 9.41 0.04

2.96 2.86 0.02

110
Table 16.3 Comparison of FID Calibrations by SRM and EDF^

a ^SRM ^EDF ^EDF

93.9 90.4 0.8

46.3 45.4 0.3

9.51 9.48 ' 0.11

2.96 3.01 0.05

^SRM diluent air and EDF carrier gas of comparable Oj content

I

111
A bias at the high propane concentration is again indicated.

I£ the EDF were a significant contributor to this bias, one

might logically expect the effect to be reflected in all

C£Dp values. The results more directly suggest a possible

alteration in FID linearity at relatively high propane concentrations. If this were the case, then one could expect the

change in linearity to manifest itself in the slopes (k's) of

the exponential curves in the 50-120 ppm region. However, a detailed examination of the slopes of the decay curves showed

the k values to be identical (within the standard deviation)

in the 100, 50, 10, and 3 ppm regions. We suspect that the

difficulty may be related to differences in FID behavior

whether subjected to a constant high propane level as in the

SRM determinations or to transient propane levels as in the

EDF experiments. Thus, the source of this bias becomes a problem for further investigations.

A conventional EDF of relatively advanced design was evaluated.

Carrier gas flow rate, EDF gas temperature, EDF volume, EDF

operating pressure, etc., were measured with the instrumentation

normally used to monitor the NBS dilutor. The EDF was coupled

to the same FID used in all previous work. The device was

found to be exponential, ( i.e. , a least-squares fit of log

signal vs^. time gave a reasonable straight line) and showed

good slope reproducibility (a ~ 0.005 k) . However, the

experimental slopes differed from those expected from L

by as much as 141. This EDF, when used as recommended, "^is

thus incapable of being used to assess detector linearity as

described previously in this report. A realistic detector

calibration must not only give a response-concentration

relationship but also a measure of detector linearity.

Detector Linearity. The linearity (n) of the FID used in this

work was determined from both the EDF experiments and from

SRM data. For nsRM» this involved least-squares fitting of

six sets of data, each containing four points while ngj^p was

obtained directly from the k and a values as described

previously. The mean values and their standard deviations

(a, for a single measurement) are given below:

ngDp = 1.020, OEDF = 0.005, 34 measurements (tieDF)

^SrM ~ 1'006, asRM = 0.013, 6 measurements (hsrm)

Student's t-test was employed to determine whether or not the

mean values above are significantly different. For the present

case

112
t

= ^EDF " ^SRM

^ EDF ^^ SRM ^

-'-/^ ^EDF ^SRM

The above data gave t = 2.60, indicating that np^p and ^^^(M

are significantly different. It can be shown that when

t > 1.96, the mean values are significantly different (95%

probability), whereas when t <^ 1.96, the mean values are not

significantly different.

The data associated with the 94 ppm SRM were eliminated from

each of the six sets of data and the remaining three SRM

points in each set were refitted by the least-squares method.

The FID linearity (hsrm) obtained from this procedure was

1.012 with asRM = 0.016. The ngoF and nsR^i values were subject

to the "t" test with the result that t = 1.21, which indicates

that the values for n-^-Q-p and nsRM a-^e not significantly

different.

The statistical testing suggests the presence of a systematic error in nsRM* This error arises from the signal (S)

obtained from the 94 ppm SRM under our experimental conditions.

Since the propane concentration of the 94 ppm SRM has been

duly verified, we believe the error to originate in the FID.

The presence of a systematic error has been previously noted

in the calculation of C£j)p for the 94 ppm SRM.

Flame ionization detector calibrations performed with the type

IV EDF have been shown to be repeatable to +1%. It has been

further shown that the FID can be calibrate3^ in the 50- to

3-ppm region with acceptable accuracy without reference to

any precalibrated gas mixture by charging the EDF with a minute quantity of pure calibrant gas. Although the potential

of the EDF as a calibration device has been demonstrated, an

extension of the verifiable calibration range would be highly

desirable. Further work with the FID and with other detectors

will assist towards the achievement of this goal.

The NBS exponential dilution flask design is protected by a

U. S. patent (3,911,723). [1].

References

[1]. Anat.Chem. ,AS, 612 (1976).

113
17. Piezoelectric Air Pollution Sensors [4-5]

Project Leader Eugene P. Scheide, Analytical Chemistry

Division

Objective

The objective of current research is to study the feasibility

of using coated piezoelectric crystals as selective and

sensitive environmental sensors.

Approach

The frequency of vibration of a piezoelectric sensor is

dependent on the weight of the coating and the weight of the

vapor adsorbed onto the coating. The concentration and/or

total exposure of the pollutant is therefore measured by

monitoring changes in frequency of the coated piezoelectric

crystal detector. The sensor is quantitative and can be

made selective by using selective substrates.

Progress

A film badge (dosimeter) has been developed and evaluated for

the measurement of mercury vapor in industrial atmospheres.

In the employment of personal environmental monitors in

industrial hygiene analysis, a collection device is needed

that is small enough to be worn on a worker's clothing and

compatible with existing miniature air pumps. An alternative

to the commonly-used solid state sorption tube is the

piezoelectric crystal sensor. This is a gravimetric device

114
in which the mass of material deposited or absorbed onto it

is determined by measuring its change in frequency. By

applying a substrate to the crystal that allows selective

adsorption of the contaminant of interest the total exposure

to this contaminant is determined from a calibration chart by

measuring the frequency change of the crystal and the time of

the sampling period. The sensor is very sensitive (lower

limit ~10"1^ g) and can be made selective for many

substances by applying various selective substrates.

The piezoelectric sensor using gold as the selective substrate

has already proven capable as an analytical tool for mercury

analysis [1,2]. In the present application, however, the

sensor is used as an integrating device to measure total

exposure for a given time period. The sensor is small enough

(1" X 1" X 2", and weighs less than lOg) to be worn in the

breathing zone of an individual and used in conjunction with

a miniature personal pump.

Figure 17.1 shows a picture of a piezoelectric crystal and

the elass holder into which it is sealed, while the above sketch

shows the sensor and pump in operation.

Air samples containing mercury vapor of known mercury concentration from a mercury vapor generation system [3] were

drawn past the sensor using a miniature pump. The flow rate

was varied between 20 and 2 50 cm^/min and the sampling time

was varied between 2 min and 8 hours. After sampling and

frequency measurement, the mercury was desorbed from the

sensor by placing the sensor in an oven at ISO^C and passing

clean, hot air over the sensor. The mercury is thereby

desorbed from the gold surface and the sensor is ready to use

again.

Figure 17.2 shows the response from sampling mercury vapor of

50 ng/1 concentration. Three different sensors of different

fundamental frequency were used. As can be seen, the

higher the frequency the greater the sensitivity, but the

range or adsorption capacity is less. Thus, higher frequency

crystals can be used for grab samples, while lower frequency

crystals can be used for 8 h exposures.

The reproducibility of replicate samples was +^5 percent.

The collection efficiency was studied as a function of flow

rate. Even at the lowest flow rate studied (20 cmV min) the

collection efficiency was not 100 percent. This was proven

by placing two sensors in series. The second sensor adsorbed

mercury vapor in all cases indiciating low collection

efficiency by the first sensor. Studies are still in progress

115
in optimizing this parameter. However, the sensor can be i used as is because the collection efficiency is constant,

| providing the flow rate is kept constant. Figure 17.3 shows

the sensor response versus flow rate. |

The cost of piezoelectric sensors, when produced in quantity,

should approach that of the solid adsorbent collectors since

the former can be re-used many times. The analysis time

using piezoelectric sensors is much shorter and the analysis

can be carried out by untrained personnel. The analytical

instrumentation is also less expensive and can be used for

the analysis of other gases once other selective substrates

are found. The piezoelectric sensor is much more sensitive

than most other techniques and can be used without timeconsuming pre-concentrating steps before analysis.

116
Figure 17.1 Piezoelectric crystal and glass holder into

which it is sealed

117
Figure 17.2 Response from sampling mercury vapor of 50 ng/1 concentration

.

118
V)

< -fm

o o o o

o o o o

m ^ CO <s (ZH) dV

Figure 17.3 Sensor response vs. flowrate,

119
REFERENCES

1. Scheide, E. P. and Taylor, J. K. , Environ. Sci.and Teo'h. ^ 8 , (13), 1097 (1974).

2. Bristow, Q. , J.Y?eoc/2SOT. Explor., 1, 55 (1972).

3. Scheide, E. P., et. al., nbsIR 7 ^-254 (Oct. 1973).

4. Scheide, E. P., and Taylor, J. K. , Amev. Ind. Hya. Assoc.

J. 36 (12), 897 (1975)

.

5. Scheide, E. P., "A Piezoelectric Crystal "Film Badge" for

Monitoring Mercury in Air," presented at the 170th Annual

ACS Meeting, Chicago, XL, August 1975.

120
37

18 . Measurement of Atmospheric Ar by Isotopic Enrichment

and Pulse Shape Discrimination Spectroscopy

Project Leader: L. A. Currie, Analytical Chemistry Division

Other Personnel: R. M. Lindstom (Anal. Chem. Div.)> in

collaboration with H. H. Loosli (Univ.

Bern), L. Machta (NOAA) , W. Roos (Mound

Laboratories), J. Barkley (NBS) and

P. Shoenfeld (NBS)

Objective

Argon-37 is produced naturally through the interaction of

cosmic rays with atmospheric argon, with a pronounced vertical profile. As its half-life (35.1 days) is relatively

short and because it is chemically so unreactive it represents an ideal tracer for the measurement of atmospheric

mixing. Complications arising from processes such as

rainout, fallout, chemical reaction, and exchange among

reservoirs are completely avoided.

The quantitative connection between cosmic ray production and

atmospheric concentrations of ^'^Ar, and stratospheric and

tropospheric mixing processes, has been clearly set forth in

the steady-state model of Machta t-^J. A principal result of

the model is that, given the absolute production profile

of 37y\^p in the atmosphere, one can derive important information about tropospheric mixing from the determination of

the ground-level concentration of the nuclide.

The temporary contamination of the Northern Hemisphere with

substantial amounts of noncosmic ^ Ar necessitated concen121
tration on efforts at measurement of samples from the Southern

Hemisphere, with which there would be insignificant mixing

within the mean lifetime of the isotope.

Progress

The system for reliable sampling and sensitive measurement

of atmospheric -^^Ar has been set up at NBS. Isotopic separation prior to counting was carried out at the Mound

Laboratories L^ -I in an 11 column thermal diffusion cascade,

with an effective length of over 37 meters. An enrichment

factor of 70 or greater could be readily obtained. Feedstock gas could be either argon from air reduction plants,

or a concentrated atmospheric sample purified over CaC^ to

remove the balance of non-noble gases.

Low level counting was carried out using the unique NBS system[5] which enables a great reduction in background via pulse risetime discrimination. This allowed the measurement of

trace concentrations of -^^Ar in reasonable counting time

periods, which would not otherwise have been possible. Delrin

and brass counters of conventional design were utilized for

the bulk of the present work.

Results were obtained for several samples from the Southern

Hemisphere, along with preliminary data on a number of samples from various localities, including stratospheric gases.

Interlaboratory comparisons with the Universitat Bern demonstrated the precision of the measurements. These results

demonstrated the utility of the technique for the determination

of tropospheric mixing. It was also found that significant

^^Ar contamination persisted even in these measurements, presumably due to nuclear testing in the South Pacific region.

Later samples from Brazil, Argentina and Australia (Spring

1974) were free of contamination, and provided valuable data

on mixing processes [4]

.

37 In order to define the vertical production gradient for Ar,

samples of dead material were exposed to high altitude conditions for extended periods. This was carried out at the

Jungfraujoch and the Signalkuppe, two tall Swiss mountain

peaks with relative atmospheric depths, at the point of

exposure, of 560 and 670 gm/cm^, respectively. Combined with

the model of Lai and Peters t^J, these data allowed precise

determination of the altitude gradient.

122

I
To complete the study cross sections for the reaction Arfp.xl Ar were determined. This is the primary mode of production of natural -^/Ar. The values are, in millibarns, (at 50 MeV)

4.4, (at 92 MeV) 8.6, and (at 200 MeV) 13.2. In addition

nlmf?v^!§rt°''38r?'" 34?/'"3|P'^^ reaction to yield other nuclides, namely -^^01, -^aci, 34ci, SSg and 31s, were measuredl^].

Further data and interpretation are forthcoming in the final report for this project.

References

[1] . Machta, L. , "Argon' 37 as a Measure of Atmospheric Vertical Mixing", Noble Gas Symposium (ERDA CONF- 730915 )

y

1974, pp. 58-68.

[2]. Rutherford, W. M. , Evans, J., and Currie, L. A., Anal.

Chem. 48, 607-612 (1976). "Isotopic Enrichment and

Pulse SHape Discrimination for Measurement of Atmospheric Argon- 37".

[3]. Currie, L. A., and Lindstrom, R. M. , "The NBS Measurement System for Natural Argon- 37", Noble Gas Symposium

(ERDA CONF-730915), 1974, pp. 40-57.

[4], Currie, L. A., Results (To be published).

[5]. Lai, D. , and Peters, B., "Cosmic Ray Produced Radioactivity on the Earth", Handbuoh. Phys, 46, 551-612

(1967).

123
la Origin of Atmospheric Hydrocarbons

Project Leader: L. A. Currie, Analytical Chemistry Division

Other Personnel: D. Breiter, E. Wolle, B. Andrews

Approach

Atmospheric hydrocarbons in urban areas have frequently been

assumed to arise as a consequence of automobile or industrial

pollution. However a major question has been raised recently

as to the relative contributions of Nature versus Man. Various

allegations (and measurements) have been made, suggesting that

the major contribution at least in the eastern cities may

arise from natural sources, such as forests[i] . On a global

scale this addition to the hydrocarbon reservoir is over seven

times that of man.

The elucidation of these relative effects has an obvious impact upon pollution control and energy resource utilization.

We are preparing to measure the origin of individual species

present in atmospheric samples by examining their radiocarbon

content. All man made contributions of significance to atmospheric hydrocarbons above methane are derived from petroleum,

which is devoid of radiocarbon as a result of its geological

age. It is therefore possible to determine the various

sources of tropospheric pollutants by analyzing air samples

by gas chromatography and, after combustion and conversion

of the desired compound, counting the resultant gas in a properly designed proportional counter.

Progress

We have adapted our existing low level counting system for the

measurement of small samples (less than 100 milliliters) of

carbon dioxide and/or methane. This corresponds to 10-20

milligrams of carbon per counter fill. Several new quartz and

copper microcounters of very low background and high efficiency

have been fabricated toward this goal. We have, in addition,

more conventional 1 and 1.5 liter counters which may prove

useful for calibration studies. Background rates for the

entire system are generally in the range of 0.17 cpm. A

filling system particularly adapted to the small counters

has also been constructed.

The relative merits of methane and carbon dioxide as counting

gases have been evaluated, and the results compared with gases

of known efficiency. We find methane to be preferable from

124
the standpoint of signal/noise and resolution o£ the pulse

energy-pulse risetime profile. Carbon dioxide will perform

satisfactorily but at a slightly increased noise level [2] . The problem of sample purity is especially acute in the present system due to the fast pulse risetime which is required

from the counter in order to collect meaningful data. We

have therefore undertaken a study of the effect of trace

impurities upon the counting process. It has been found that

conventionally purified carbon dioxide such as is used in most

radiocarbon laboratories is of insufficient purity for our

purposes. In addition to devising a further purification

scheme we have to some extent improved this difficulty by

increasing the time constant of the counter guard circuit

so as to provide coincident pulse blanking throughout the

irregular risetime of the data pulse.

A number of preliminary studies have been carried out upon

radiocarbon calibration standards and other materials of

interest. Working standard carbon dioxide from F. J. Pearson

(USGS-Reston) and E. Ralph (Univ. of Pennsylvania) have been

measured in both the small and large counters. Standard

deviations and non-Poisson random error have been computed

in each case. Preliminary data on a sample of urban particulate containing 12% carbon indicate an upper limit of 201

of contemporary levels, demonstrating the utility of the

approach to such samples. These data compare favorable with

that of Clayton, Arnold, and Patt)E5]on similar samples.

Further refinement of the sample is continuing.

We have considered various atmospheric sampling techniques,

and have decided, in addition to particulates, to confine

most of our efforts toward selective adsorption of the hydrocarbons upon cryopumped molecular sieves. Currently we are

constructing a high purity microcombustion line and conversion apparatus which can be interfaced directly with a flame

ionization analytical gas chromatograph. This arrangement

will allow the rapid processing of trace compounds in large

volume air samples.

125
References

[IJ.Maugh, T. U,,Soienae 18£, 277-8 (1975).

[2]. Currie, L. A., 9th International Radiocarbon Conference,

Proceedings, Los Angeles, California (June 1976).

L-^J • Clayton, G. D. , Arnold, J. R. , and Patty, F. A., Saienoe

122, 751-3 (1955).

126
20. Lead in Gasoline

Project Leader: I. L. Barnes, Analytical Chemistry Division

Other Personnel: N. M. Caliman, J. W. Gramlich, E. F. Heald,

and T. J. Murphy

Objective

To develop a method for the accurate determination o£ lead in

gasoline and reference fuels by isotope dilution mass spectrometry.

Approach

The conditions for the quantitative conversion of the organically bound lead in gasoline and reference fuels to inorganic

lead were to be established. Lead could then be accurately

determined by spiking with 206 separated isotope of lead and

mass spectrometric analysis.

Progress

A method has been developed for the accurate determination of

lead in gasoline. It has been used to certify the lead concentration in Standard Reference Materials, SRM's 1636, 1637,

and 1638, Lead in Reference Fuels. These SRM's consist of

four separate blends of leaded fuel which vary in concentration from 12 to 773 yg Pb/g. The method has also been used

to determine the lead concentration in the Gasoline Fossil

Fuel Standard.

The success of the method depends on the quantitative conversion of the organically bound lead of the fuel to inorganic

lead. After experimenting with several methods, the following

method was found to give quantitative conversion without loss

of volatile lead compounds.

A sample of the fuel (about Ig) is transferred to a Pyrex

Erlenmeyer flask containing 5 ml of concentrated nitric acid

and ^°^Pb spike. The flask is stoppered with a polyethylene

stopper and the contents are rapidly stirred using magnetic

stirring for one hour. The flask and contents are then

shaken for five minutes to ensure reaction with any volatile

lead. For hydrocarbon reference fuels, the mixture is simply

evaporated to dryness. For gasoline, 1 ml of perchloric acid

is added and the solution is evaporated to fumes of perchloric

acid.

•^The abbreviation ml, for milliliter is used in this publication. The new

abbreviation for milliliter is mL.

127
At this point, the lead is available for separation and determination by mass spectrometry (or other techniques)

.

The results of the determination of lead in the Gasoline

Fossil Fuel Standard and the SRM Reference Fuels are shown

in tables 20.1 through 20.5.

The analysis of the Gasoline Standard, Table 20. 1| shows that

one bottle. 564, had a lead concentration two percent higher

than the other four bottles. This could be due to loss of

gasoline and concentration of tetra-ethyl lead. The results

for the other bottles show that the material contained 375.0

+ 2.2 yg Pb/g. The results for bottle 141 show that no lead

Ts lost during the equilibration-oxidation steps since there

is no significant difference between the results for subsamples 1 and 2 which were spiked before the analysis and

sub -samples 3 and 4 which were spiked after the evaporation

of HNO_.

The SRM Reference Fuels have been certified on the basis of

the results reported in table 20.2 through 20.5 as follows:

Nominal Lead Concentration Certified Lead Concentration

g/gal yg/g

0.03 12.31 + 0.06

0.05 19.68 + 0.05

0.07 27.70 + 0.06

2.00 772.70 + 1.50

The uncertainties cited represent the pooled 95% confidence

interval for a single determination with allowance for known

sources of possible error.

An investigation of the concentration and type of acid used

for the conversion of the organically bound lead was also

completed. The results are shown in Tables 20.6 and 20.7.

They show that quantitative results were obtained only when

concentrated nitric acid was used. Low recoveries were found

for hydrochloric acid and more dilute nitric acid concentrations

128
Table 20.1 Lead in Gasoline Fossil Fuel Standard.

Bottle Sample Lead

No. No. ug/g

141 1 375.1

2 375.0

3^ 376.6

4* 376.8

Average 375.9

226 1 374.9

2 375.2

Average 375.0

323 1 373.4

2 375.1

Average 374.3

564 1 380.5

2 384.5

Average 382.5

707 1 374.3

2 374.8

Average 374.6

Grand Average 375.0 . (Bottle 564 omitted) *2.2

Grand Average 376.5 u (Bottle 564 included) *6.9

Spiked after evaporation of HNO3

95% L.E. for Single Analysis.

129
Table 20.2 Lead in Reference Fuel 2.0 g

Lead/Gallon Standard.

Lead

yg/g

Can A

Vial 5 772.4

319' 772.1

735 773.6

Average 772.7 ± 1.5^

Can B

Vial 995 745.8^

1078 742.1

Bulk 1 742.5

2 740.8

3 741.6

4 741.4

Average 741.6 +1.5'

a

b

Pooled 95% confidence limit for an

individual determination.

Excluded from average (sample taken one

hour after opening vial.)

130
' '^ —fc*-

Table 20.3 Lead in Reference Fuel 0.07 g

Lead/Gallon Standard.

/ial Lead

yg/g

95 27.70

212 27.71

444 27.70

494 27.69

645 27.75

823 27.68

825 28.23^

828 27.70

828 27.69

1019 27.69

1155 27.73

Average 27.70 +

EPA (first series)

8 27.64

51 27.65

128 27.78

Average 27.69

EPA (second series)

Front 27.78

Middle 27.77

Rear 27.82

Average 27.79

, Excluded from average

95% confidence limit for an

individual determination.

131
Table 20.4 Lead in Reference Fuel 0.05 g

Lead/Gallon Standard.

Lead

yg/g

Can A

Vial 31 19.67

71 19.70

637 19.68

Average 19.68 ± 0.05^

Can B

Vial 970 19.81

1140 19.86

Bulk 1 19.85

2 19.87

3 19.87

4 19.83

Average 19.85

EPA (first series)

Vial 35 19.61

85 19.76

120 19.88

Average 19.75

EPA (second series)

Dial Front 19.83

Middle 19.82

Rear 19.80

Average 19.82

± 0.05'

^ Pooled 951 confidence limit for an

individual determination.

132
Table 20.5 Lead in Reference Fuel 0.03 g

Lead/Gallon Standard.

Vial Lead

138 12.32

285 12.30

352 12.29

506 12.33

633 12.36

812 12.30

911 12.30

1061 12.28

Average 12.31 ± 0.06^

EPA (first series)

2 12.40

54 12.37

1301 12.34

Average 12.37

EPA (second series)

Front 12.33

Middle 12.32

Rear 12.32

Average 12.32

a 95% confidence limit for an

individual determination.

133
Table 20.6 Effect of Nitric Acid Concentration on

Recovery of Lead in Gasoline.

Sample

No.

HNQ3 Lead Found

ppm

Recovery

1

1 16 376.6 100.4

2 16 372.9 99.4

3 16 376.3 100.3

4 16 378.1 100.8

5 8 376.5 98.0

6 8 369.7 98.6

7 4 346.8 92.5

8 4 352.3 93.9

9 2 141.3 37.7

a

b Concentration of the 5 ml of added acid.

Based on previous analysis of 375.0 + 2.2 ppm Pb.

134
Table 20.7 Effect of Hydrochloric Acid Concentration on

Recovery of Lead in Gasoline.

Lead Found (ppm) Recovery

98.0%

93.31

94.11

71.3%

98.8%

6 5.7%

100.2%

Sample No. HCl N^ Lead F

1 10 367.5

2 10 349.8

3 10 352.9

4 10 267.7

5^ 10 370.6

6^ 10 246.5

7^ 10 - 375.7

8^ 10 198.1

9 5 319.0

10 5 249.2

11 1 16.1

12 1 48.5

13 0.2 11.8

14 0.2 16.8

Concentration of the 5 ml of added acid.

L. Based on previous analysis of 375.0 ±2.2 ppm.

Spiked after evaporation.

52.8

85.1%

66.5%

4.3%

12.9%

3.1%

5.0%

135
21. Degradation of Polymers

Project Leader: R. E. Florin, Polymers Division

Other Personnel: J. H. Flynn, S. Straus, L. Dunlap, W. J.

Pummer

Objective

To gain an understanding of the mechanisms of polymer

degradation, primarily thermal decomposition to volatiles.

Applications are to limits on service, fire hazard, incineration, and toxic hazard.

Approach

Data for the deduction of mechanism are pyrolysis rates and

molecular weights as a function of conversion. Products are

characterized also for newly studied polymers. Interpretation

is in terms of the free radical chain theory. Burning of

aged polymers is also studied.

Progress

Experimental work was completed upon the pyrolysis of polyoctafluorostyrene fractions of various molecular weights.

Monomer is not an important product, a fact which raises

difficulties as to the type of reaction that can produce

oligomer fractions in an all-fluorocarbon polymer. Data

from the pyrolysis of azobis-isobutyronitrile prepared

polystyrene showed very high initial rates for some lowmolecular-weight fractions, which are not yet satisfactorily

explained, although they correlated with several anomalous

pyrolysis gas chromatography peaks. The pyrolysis of

polystyrene in nitrogen showed rate versus conversion curves

similar to vacuum experiments but apparently about 301

higher not lower. Before drawing conclusions, a careful

check is being made of temperature distributions under the

two conditions. Burning behavior and extent of oxidation

were studied for four polymers aged in air by the action of

heat and also by gamma rays. Appreciable effects were:

for polypropylene oxidized under gamma rays, an appreciable

increase in ignition time; and, for flexible polyurethane

aged in an oven, an increase in burning rate.

136
22. Fossil Fuel Standards

Project Leader: P. D. LaFleur and D. A. Becker, Analytical

Chemistry Division

Other Personnel: Many scientists throughout the Analytical

Chemistry Division

Objective

To develop environmental trace element standards for fossil

fuel energy requirements.

Approach

The approach that has been used was to obtain samples of

the required materials for processing and issuance as

Standard Reference Materials. This processing included

insuring the material had a limited particle size range,

proving homogeneity on the final bottled sample, and finally

analyzing and certifying these materials for trace element

content. A much more detailed description of the materials

and the processing required for each of them is contained

in last year's Measures for Air Quality Annual Report, NBS

Technical Note 828.

Progress

The Trace Elements in Fly Ash (SRM 1633), Trace Elements in

Coal (SRM 1632), and Trace Elements in Residual Fuel Oil

(SRM 1634) have been issued--see certificates for details.

The Trace Elements in Gasoline SRM has presented a number of

significant technical problems and because of this has been

dropped as a candidate SRM.

The gasoline was analyzed for its lead content by isotope

dilution mass spectrometry, which revealed that with leaded

gasoline, the problem of volatility is extremely significant.

This is compounded by the fact that the tetra-ethyl lead

apparently has a different volatility than the gasoline

hydrocarbon component. In addition to the above problem,

there has been great difficulty in the attempts to process the

gasoline into a form suitable for analysis by conventional

analytical techniques. In this case the problems include

both volatility, and the potential for rapid, uncontrolled

137
oxidation. The volatility problem is especially difficult

to evaluate because it is not known which of the trace

element components are in metallo-organic form and what

their individual vapor pressures are in relation to the

hydrocarbon component of the gasoline. These problems have

resulted in the decision that gasoline is an inappropriate

material for a trace element standard.

138
U. S. Department of Commerce

Frederick B. Dent

Secretary

National Burtsn of Standards

Ridiard W. Roberta, Director Rational ^ureau of ^inndntdsk

C^rttfttat^ of ^nnl^Bxs

Standard Reference Material 1632

Trace Elements in Coal

This Standard Reference Material is intended for use in the calibration of apparatus and methods

used in analyses of coals and other materials with similar matrices for trace elements. This material should be dried without heat to a constant weight before using. Recommended procedures for drying are: (1) drying for 24 hours using a cold trap at or below —50 °C and a pressure not greater than 30 Pa (0.2 mm Hg); (2) drying in a desiccator over P2O5 or Mg (0104)2- When not in use, the

material should be kept in a tightly sealed bottle and stored in a cool, dark place. Long term (> 1 year) stability of this SRM has not been rigorously established. NBS will continue to monitor this material and any substantive change will be reported to purchasers.

The certified values given below are based on at least a 250-mg sample of the dried material, the minimum amount that should be used for analysis.

Element* Content^ Mg/g Element' Content^ Mg/g

Iron8'' Manganese*'*

Zinc^'*

8700 ± 40 ± 37 ±

300

34

Selenium"*'* Uranium*'^

Thallium*'

d

2.9 ± 0.3

1.4 ± 0.1 0.59 ± 0.03

Vanadium'»'*'8

Lead«'*'''<* Chromium*'*'*

35 ± 30 ± 20.2 ±

39

0.5

Cadmium"*'*''

Mercury*'*'

0.19 ± 0.03

0.12 ± 0.02

Copper* '"J '8 Nickel*'8'i Arsenic* '*•

18 ± 15 ±

5.9 ±

2

10.6

1. Methods of Analyses:

a. Atomic Absorption Spectrophotometry

b. Flame Emission Spectrometry

c. Isotope Dilution Mass Spectrometry

d. Isotope Dilution Spark Source Mass Spectrometry

e. Neutron Activation

f

.

N uclear Track Technique

g. Photometric

h. Photon Activation

i. Polarography

2. The values are based on the results of 4 to 17 determinations by each of at least two analytical

techniques. The estimated uncertainties include sample variations, possible method dif- ferences, and errors of measurement (but in no case less than the 95% confidence limits computed for the analyses).

The overall direction and coordination of the analytical measurements leading to this certificate were performed in the Analytical Chemistry Division under the chairmanship of P. D. LaFleur.

The technical and support aspects involved in the preparation, certification, and issuance of this Standard Reference Material were coordinated through the Office of Standard Reference Materials by C. L. Stanley.

Washington, D.C. 20234

March 7, 1975

(over)

J. Paul Cali, Chief

Office of Standard Reference Materials

139
PREPARATION, TESTING, and ANALYSIS

This material is a blend of commercially available coals supplied by five electric power plants: Tennessee Valley Authority, Stevenson, Alabama; Commonwealth Edison, Chicago, Illinois; Balti- more Gas and Electric Co., Baltimore, Maryland; Carolina Light and Power Co., Roxboro, North

Carolina; and Potomac Electric Power Co., Washington, D. C. These plants were specially selected to provide coals that covered a broad spectrum of the coal mining industry. Some of the coals required

regrinding to obtain a fine particle size. This was done under the auspices of Mr. Forrest Walker of

the U. S. Bureau of Mines, Pittsburgh, Pennsylvania. The coals were then sieved and the portion

passing through a 120 mesh sieve and retained on a 325 mesh sieve was taken (125 to 44 micrometers diameter). After sieving, the five coals were blended in a double-coned blender. After 1 hour

the material was immediately removed and bottled. A random scheme for sample selection was designed and a statistical analysis of the homogeneity

data was performed by J. Mandel of the NBS Institute for Materials Research. Thirteen of 500

bottles were selected for homogeneity tests. These samples were analyzed for aluminum and manganese by nondestructive neutron activation analysis. Replicate analyses on 250-mg samples indicated homogeneity within ±5 (relative) based on these two elements. The homogeneity analyses were performed in the NBS Analytical Chemistry Division by T. E. Gills and S. H. Harrison. Analyses for the various elements were made in the NBS Analytical Chemistry Division by the following

analysts: R. K. Bell, R. W. Burke, B. S. Carpenter, B. I. Diamondstone, L. P. Dunstan, M. S. Epstein,

E. L. Garner, T. E. Gills, E. S. Gladney, J. W. Gramlich, G. J. Lutz, L. A. Machlan, E. J. Maienthal,

L. T. McClendon, T. J. Murphy, E. Orvini, P. J. Paulsen, T. C. Rains, K. M. Sappenfield, S. A. Wicks.

The following values are not certified because they are based on a non-reference method, or were

not determined by two or more independent methods. They are included for information only.

Element Content (us/z)

Titanium (800)

Cobalt (6) Silicon (3.2%)

Thorium (3.0)

Beryllium (1.5) Silver (<0.1)

Tellurium (<0.I)

140
U. S. Depart^n|^of CommeFce

Rogers Q£. Morton

National ^arUiTol Standard!

Richard W. Itiert*, Director Rational ^urcau of ^tanrfards

Certificate of ^nalgsis

Standard Reference Material 1634

Trace Elements in Fuel Oil

This Standard Reference Material is intended for use in the

calibration of apparatus and evaluation of methods used in

analyses of fuel oil and other materials with similar matrices

for trace elements. When not in use, the material should be kept

in a tightly sealed bottle. Long term (>1 year) stability of

this SRM has not been rigorously established. MBS will continue to monitor this material and any substantive change

will be reported to purchasers.

The certified values given below are based on at least a 250-mg sample of the material, the minimum amount that should

be used for analysis

.

2 y pg/g except S in

Element Content - % by weight

Sulfur^/^, 2.14 ± 0.02%

HickBl^r'^' 36 ±4

Lead^-^' ,, 0.041 ± 0.005

Vanadium^J^' 320 * 15

Zinc|-i^/^, 0.23 ± 0.05

iron^ iy'^' 13.5 ± 1.0

1. Methods of Analyses:

a. Atomic Absorption Spectrophotometry

b. Isotope Dilution Mass Spectrometry

c. Isotope Dilution Spark Source Mass Spectrometry

d. Neutron Activation

e. Combustion with Titrimetry

f. Spectrophotometry

g. Polarography

2. The values are based on the results of 4 to 15 determinations by each of at least two analytical techniques.

The estimated uncertainties include sample variations,

possible method differences, and errors of measurement

(but in no case less than the 95% confidence limits computed for the analyses)

.

The overall direction and coordination of the analytical measurements leading to certification were performed in the Analytical

Chemistry Division under the chairmanship of P. D. LaFleur and

D. A. Becker.

(over)

141
The technical and support aspects involved in the preparation,

certification, and issuance of this Standard Reference

Material were coordinated through the Office of Standard

Reference Materials by C. L. Stanley.

Washington, D. C. 20234 J. Paul Cali, Chief

May 14, 19 75 Office of Standard Reference Materials

PREPARATION, TESTING, and ANALYSIS

The material was obtained through a commercial supplier from a refinery on the island of Aruba in the West Indies, and is

essentially a "No. 6 Fuel Oil" as defined by the American

Society for Testing and Materials

.

A random scheme for sample selection was designed and a statistical analysis of the homogeneity data was performed by J.

Mandel of the NBS Institute for Materials Research. Fifteen

of 500 bottles were selected for homogeneity tests. These

samples were analyzed for vanadium by nondestructive neutron

activation analysis. Replicate analyses on 250 mg samples

indicated homogeneity within ±2% (relative) based upon this

element. X-ray fluorescence analyses for sulfur on bulk

samples before bottling supports the conclusion of acceptable

material homogeneity. The homogeneity analyses were performed

in the NBS Analytical Chemistry Division by T. E. Gills,

M. Darr, and R. Myklebust. Analyses for the various elements

were made in the NBS Analytical Chemistry Division by the

following analysts: R. W. Burke, B. S. Carpenter, M. S.

Epstein, E. L. Garner, T. E. Gills, J. W. Gramlich,

L. A. Machlan, E. J. Maienthal, T. J. Murphy, E. Orvini,

T. C. Rains, H. L. Rook, T. A. Rush, and S. A. Wicks.

The following values are not certified because they are based

on a non-reference method, or were not determined by two or more independent methods. They are included for information

only.

Element- Content pg/g

Arsenic-/,, (0.095)

Beryllium-^

Cadmium-vy

(<0.01)

(<0.01)

Chromiumy (0.09)

Mercury-/ (0.002

Manganese^i-^ (0.12)

142
U. S. Department of Commerce

Frederick B. Dent

Secretary

Nation*! Bureau of Standards

Kichard W. Roberta, Director (Uttixixtnit of ^nnlysh

Standard Reference Material 1633

Trace Elements in Coal Fly Ash

This Standard Reference Material is intended for use in the calibration of apparatus and methods

used in analyses of coal fly ash and other materials with similar matrices for trace elements. This

material should be dried to a constant weight before using. Recommended procedures for drying

are: (1) drying for 24 hours using a cold trap at or below —50 °C and a pressure not greater than 30

Pa (0.2 mm Hg); (2) drying in a desiccator over P2O5 or Mg (€104)2. When not in use, the material should be kept in a tightly sealed bottle. Long term (>1 year) stability of this SRM has not been

rigorously established. NBS will continue to monitor this material and any substantive change will be reported to purchasers.

The certified values given below are based on at least a 250-mg sample of the dried material, the minimum amount that should be used for analysis.

Element

Content^ /ig/g Element' Content^ U^g

Manganese"'* '8 Zinc*'* Vanadium**'*'?

Lead*'' Chromium"'*'*''

Copper" '••'J

493 ± 7 210 ± 20

214 ± 8

70 ± 4

131 ± 2 128 ± 5

Nickel"'*-'

Arsenic*''' Uranium*'*

Selenium^'*

Cadmium" ^ ''* Mercury" *

98 ± 3

61 ± 6

11.6 ± 0.2

9,4 ± 0.5 1.45 ± 0.06

0.14 ± 0.01

1. Methods of Analyses:

a. Atomic Absorption Spectrophotometry

b. Flame Emission Spectrometry

c. Isotope Dilution Mass Spectrometry

d. Isotope Dilution Spark Source Mass Spectrometry

e. Neutron Activation JNuclear Track Technique

Photometric

Photon Activation

Polarography

Colorimetry

2. The values are based on the results of 4 to 28 determinations by each of at least two analytical

techniques. The estimated uncertainties include sample variations, possible method dif- ferences, and errors of measurement (but in no case less than the 95% confidence limits computed for the analyses).

The overall direction and coordination of the analytical measurements leading to certification were

performed in the Analytical Chemistry Division under the chairmanship of P. D. LaFleur.

The technical and support aspects involved in the preparation, certification, and issuance of this Standard Reference Material were coordinated through the Office of Standard Reference Materials by C. L. Stanley.

Washington, D. C. March 7, 1975

20234 J. Paul Cali, Chief

Office of Standard Reference Materials

(over)

143
PREPARATION. TESTING, and ANALYSIS

This material is a blend of coal fly ashes supplied by five electric power plants: Tennessee Valley

Authority, Stevenson, Alabama; Commonwealth Edison, Chicago, Illinois; Baltimore Gas and Electric Co., Baltimore, Maryland; Carolina Light and Power Co., Roxboro, North Carolina; and

Potomac Electric Power Co., Washington, D. C. These plants were specially selected to provide fly ashes that covered a broad spectrum of the fly ashes from the coal mining industry. Five of the fly ashes were collected by electrostactic precipitators and one by a mechanical collector. The fly ashes were sieved and the portion passing through a 170 mesh sieve was taken (88 micrometers diameter

or less). After sieving, the fly ashes were blended in a double-coned blender. After 1 hour the

material was immediately removed and bottled. A random scheme for sample selection was designed and a statistical analysis of the homogeneity

data was performed by J. Mandel of the NBS Institute for Materials Research. Fifteen of 500

bottles were selected for homogeneity tests. These samples were analyzed for manganese by nondestructive neutron activation analysis. Replicate analyses on 250 mg samples indicated homogeneity within ±5% (relative) based upon this element. X-ray fluorescence analyses on bulk samples

before bottling supports this conclusion with values for cadcium, titanium, iron, nickel, zinc, stron- tium, and barium. The homogeneity analyses were performed in the NBS Analytical Chemistry

Division by T. E. Gills and S."D. Rasberry. Analyses for the various elements were made in the NBS

Analytical Chemistry Division by the following analyst: R. K. Bell, B. S. Carpenter, L. P. Dunstan, M. S. Epstein, E. L. Garner, T. E. Gills, E. S. Gladney, J. W. Gramlich, G. J. Lutz, L. A. Machlan, E.

J. Maienthal, L. T. McClendon, T. J. Murphy, E. Orvini, P. J. Paulsen, T. C. Rains, T. A. Rush, and

K. M. Sappenfield.

The following values are not certified because they are based on a non-reference method, or were

not determined by two or. more independent methods. They are included for information only.

E;iement . Content (A'g/g)

Potassium (1.72%)

Strontium (1380)

Rubidium (112)

Cobalt (38)

Thorium (24)

Beryllium (12)

Thallium (4)

144
23. Determination of Platinum and Palladium by Activation

AnalysiT

Project Leader: D. A. Becker, Analytical Chemistry Division

Objective

The objective o£ this project is to develop an accurate and

precise trace element analytical technique for the determination

of platinum and palladium in biological and environmental

materials.

Approach

The utilization of vehicular exhaust catalytic converters

containing these noble metals underscores the need for accurate

and sensitive analytical techniques for the noble metals in

the environment, especially for platinum and palladium [1-3].

Neutron activation analysis is able to analyze both of these

elements at the yg/g concentration level or below. Earlier

work in this laboratory has established that platinum can be

determined at the .01 yg/g concentration level in glasses.

However, in order to determine these elements at the trace

level they must be chemically separated from the matrix

material after irradiation. This is necessary due to their

low energy gamma rays which are used for analysis. This

effort has therefore been towards development of a radiochemical separation technique that will allow the determination

of platinum and palladium accurately and reliably at the

yg/g to ng/g concentration levels in a wide variety of

environmental materials.

Progress

The neutron activation analysis method developed and described

here is capable of quantitatively determining gold, platinum

and palladium in a wide variety of biological and environmental

matrices. The nuclear characteristics of the radioisotopes

used in this procedure are found in Table 23.1. As shown, the

isotope used for the determination of platinum is the gold-199

daughter from platinum-199.

145
In addition to the matrices described here, this method is

currently being applied also to the analysis of several new

biological standard materials currently undergoing certification, a fresh water sediment being evaluated as a potential

reference material, and an urban air particulate material.

All samples were prepared for analysis by lyophilization.

Dry samples weighing from twenty to two-hundred milligrams

each were placed into precleaned, polyethylene snap cap

vials for neutron irradiation. The facility used was the

NBS nuclear reactor, with irradiation periods of up to four

hours at a thermal neutron flux of 5.6 x 10^^ n^cm"^ s" .

The chemical separation technique employed involved wet-ashing

the irradiated biological or environmental sample with approximately ten milliliters of a three to one mixture of concentrated nitric and perchloric acids. This sample dissolution

took place in the presence of about one milligram each of

platinum, gold and palladium carriers, and about five milligrams of copper holdback carrier. The samples were slowly

wet-ashed on a hot plate to fumes of perchloric acid, then

taken almost to dryness. After cooling, they were taken up

in about three milliliters of a three to one mixture of

concentrated hydrochloric and nitric acids until complete

dissolution occurs. An additional five milligrams of copper

holdback carrier was added at this time, along with several

milligrams of scandium and phosphate holdback carriers.

Samples were then diluted to approximately twenty milliliters,

and quantitatively transferred into appropriately sized

disposable plastic containters (e.g., centrifuge tubes,

bottles, etc.). At this point, 200 milligrams of finely

divided silver metal powder was added, and the solution-powder

mixture stirred for approximately five minutes using a magnetic

stirring bar with high agitation. The silver powder should

swirl throughout the entire solution during this period.

After spontaneous deposition onto the silver powder is concluded, the solution with silver powder is quantitatively

transferred to a standard radiochemical filter chimney with

a filter capable of retaining fine particle size material. In

this work, glass fiber filter pads were used. The silver

powder is washed several times with distilled water, and great

effort is taken to ensure that all of the silver particles

have been transferred to the filter. At this point, the silver

powder on the filter paper is removed from the filter chimney

and carefully transferred to a plastic disposable petri dish

and mounted for subsequent counting. Separation of the silver

by centrifugation was also investigated, but filtration was

found to be more effective in removing the silver powder fines

from the solution.

146
Aliquots o£ the dissolved standards are processed in exactly

the same way in order to check radiochemical recovery. In

addition, duplicate aliquots are added directly to filter

paper in the disposable petri dishes producing a geometry

similar to that of the processed sample.

Tracer studies made using this radiochemical separation

procedure showed quantitative recovery (greater than 99.5%)

for the gold-198, gold-199, and palladium-109

.

This analytical system has been evaluated through application

to the determination of gold, platinum, and palladium in

several available biological and environmental materials.

Results on the analysis of a bovine animal tissue (liver)

gave values of 1.8 ng/g for gold, less than 1.6 ng/g for

platinum, and less than 1 ng/g for palladium. Results for the

analysis of a powdered botanical material (leaves) gave

results of 0.2 ng/g for gold, less than 9 ng/g for platinum,

and less than 1 ng/g for palladium. These analyses were

made using a neutron flux of 5.6 x 10^^ n*cm"2 s"^ for four

hours, and counting both on a 6% efficient Ge(Li) detector

(gold-198, gold-199) or LEPS System (109-palladium) . For

the botanical material, the less sensitive 208 keV gamma ray

peak was used due to an interference with the 158 keV gamma

ray. This interference was apparently due to the scandium-47

daughter from neutron irradiation of naturally stable

calcium-47. Later determinations using scandium holdback

carrier eliminated this interference problem.

In conclusion, the spontaneous deposition technique has been

demonstrated for the first time to be an effective radiochemical separation method for biological and environmental

samples, and neutron activation combined with this separation

technique appears to be a very useful method for the

determination of platinum, palladium, gold, and possibly other

noble metals in biological and environmental materials.

147
Table 23.1 Radioisotopes Used for the Analyses

of Neutron Activation

Element

Determined

Radioisotope

Used

Photon Energy Half-Life

Gold

Platinum

Palladium

198Au

199Au (daughter)

109 Pd

412 keV

158 keV

(208 kev)

88 keV

2.69 d

3.14 d

13.5 h

ll

148
References

[1]. Kinard,W.D. , Becker, D. A. , and LaFleur, P.D., NBS Teoh.

Note 548 (1970) pp. 66-69.

[2]. Becker, H .k. y Anal. Chem. Acta 6j^, 1 (1972).

[3]. Park ,K.S., Gijbels,R., and Hoste, J., Radioanal. Chem,

5, 31 (1970).

149
24. Urban Dust Project

Project Leader: J. K. Taylor and W. Cassatt, Analytical

Chemistry Division

Objective

To collect a large sample (25 kilograms) o£ urban air

particulate from each of two metropolitan areas. One site

is to be representative of highly industrialized communities

while the other is to be typical of cities devoted to light

commerce and residential developments. The samples will be

characterized with respect to trace element composition,

organic components, and particle size distribution.

Approach

Each of these samples will be homogenized separately and

subdivided into several hundred samples for use as a Standard

Reference Material. These SRMs will be issued by NBS to

provide calibration and test materials for those involved in

air particulate studies or air pollution monitoring. The

reference materials will constitute known samples which have

compositional and physical characteristics that are very

similar to the material that the users are attempting to

detect or analyze. Secondly, they will enable investigators

to measure the sensitivities, matrix interferences and

particle size effects that are associated with the particular

instrument or analytical procedure that is being tested.

150
Progress

Five baghouses, each with an air sarapli^ig rate o£ approximately

6000 cubic feet of air per minute (163um /min) were installed

in December 1973 in the eastern section of the St. Louis

metropolitan area (Granite City, IL). At the end of FY 74

(July 1974), the total dust mass collected in all the baghouses

was about two kiligrams. This yield was particularly disappointing since it was estimated the total air particulates

entering the bags was in the neighborhood of 27 kilograms.

During FY 75, the collection efficiency was observed to rise

slowly as the mass of dust particles built up on the filter

cloth. It was estimated from a few bats that had been

weighed early in 1975 that approximately six kilograms had

been collected by the end of January of that year. However,

the average particulate collection efficiency for the entire

period was still only nine percent.

In January 1975, a set of experiments was conducted in

Washington, D. C., to determine whether the air velocity had

any effect upon the collection efficiency of the cotton

filter material. When a segment of a filter bag (which had

been removed from baghouse No. 2) was placed in a Hi-Vol

sampler with a fiberglass filter behind the cloth, it yielded

a measured collection efficiency of 93 percent. The linear

velocity through the cloth was -20 times the velocity through

the bags in the baghouses. The results indicate that the

effect of flow rate on the baghouse efficiency warranted

investigation.

Toward the end of January 1975 a Hi-Vol system was operated

for 16 hours inside baghouse No. 5 in St. Louis and then was

run outside the baghouse for an equal period of time. The

Hi-Vol sampler collected 39 mg of dust inside unit 5 as

compared to 145 mg outside. This gave an estimate of 70

percent for the baghouse collection efficiency. A repeat of

this experiment in April yielded an efficiency reading of 90

percent.

Early in April 1975, ••90 percent of the bags from unit 5 and

one bag from unit 4 were brought back to NBS. Weighing data

on the dust that was vacuumed from four bags from unit 5 and

one bag from unit 4 indicated that a total of about nine

kilograms of material had been collected by all five baghouses

up to that time (April 1975). Another sample taken from

unit 4 at the end of May indicated that roughly 10 kilograms

were contained in all units as of June 1975.

151
Seven weeks after the 90 percent reduction in the number of

bags in unit 5, it was observed that the dust loading in the

bags reduced the air flow rate through this unit by 20 percent. Upon analysis, it was observed that the dust mass per

bag (after seven weeks) was about twice that in each bag in

unit 4.

The total collection rate for all five baghouses was computed

to be about 0.5 kilogram of dust per week. It should be

noted, however, that the collection rate during the January

to June period should have risen to one kilogram per week as judged from the measured collection efficiencies. One cause

for this factor-of-two discrepancy may be the loss of mass

due to volatilization of the material as it is "dried" by the

air flowing through the filter bag.

A small sample of urban dust, subjected to a preliminary

analysis by x-ray fluorescence spectrometry shows that the

following elements can be observed by instrumental analysis:

Ca, Mn, Fe, Co, Cu, Zn, As, Br, and Pb. It would appear,

therefore, that this method deserves consideration as a candidate for a relatively inexpensive analytical technique

for checking homogeneity of the bulk material at various

stages of the SRM production.

On the basis of the observations noted above, it was predicted

that the desired quantity of dust would be collected by late

winter. Accordingly, the collection operation was discontinued April 6, 1976.

A special vacuum cleaner, provided with a probe of approximately

the internal diameter of the bags, was constructed and used

at NBS to recover the collected material. The dust so obtained

contains a small amount of extraneous material, including

bag filters, but this can be removed by sieving. It has been

found that more than 90 percent of the recovered material

will pass a 325 mesh screen and this appears to be essentially

free of bag fiber and sufficiently homogeneous for use as a reference material.

The certification analyses will be conducted during Fiscal

Year 1977. It is expected that the SRM will be ready for

issue on or about July 1, 1977.

152
25 SEM and ESCA as Techniques for Characterization of the

St. Louis Air Particulate

Project Leader: A. W. Ruff, Metallurgy Division

Other Personnel: D. B. Ballard, A. J. McAlister

Objective

To characterize St. Louis air particulate samples and

certain asbestos fibers.

Approach

Scanning electron microscope (SEM) and ESCA examinations have

been conducted of the St. Louis, Missouri air sampling station.

Asbestos fibers were also studied.

Progress

SEM - A specimen of the proposed SRM Urban Air Particulate,

collected at a baghouse station in St. Louis, Missouri, was

prepared for examination in the SEM. The technique consisted

of sprinkling part of the homogenized sample onto a specimen

stub that had previously been covered with a piece of doublestick tape and then coated with a thin layer of carbon. The

stub was inverted and tapped lightly to remove excess and

nonadherent particles. This prepared specimen was then

coated with a 500A layer of Au-Pd alloy by DC sputtering.

The specimen was viewed in the SEM with gun potential at

lOKV. 23° tilt angle on stub and a target current of 340 x

10 "12 amp.

The photomicrograph. Figure 25.1 shows particulates typical

of the great variety of sizes, shapes and structures observed.

Stereomicroscopy was used to ascertain geometrical shapes of

some particles. The 3-D technique may allow identification

by reference to other SEM publications on particulates and

to the McCrone Particle Atlas. The disk shaped particle in

Figure 25.2 is probably a pollen grain. Figure 25.3 shows a

tentacle-shaped object "A" probably related to a plant seed.

The object "B" may be the residue from an incinerated hydrocarbon material. The large particle in Figure 25.4 has

fracture surfaces similar to glass. The substructure shown

in Figure 25.5 is similar to that seen in a cross section of

153
spruce wood. Many smaller and agglomerated unidentified

particles can be seen embedded in or attached to the larger

particles described above.

Two materials other than glass were examined in the SEM as

substrates for collected air particulates. The first was a paper made from compressed spun-glass fibers and the second

was a polycarbonate nuclepore filter paper. Both of these

filters were located in the exit stage area of the Delvon

Sampler discussed earlier, therefore, the total number of

particulates trapped was small. The surface structure of

the nuclepore filter is shown in Figure 25.6. Very few

particles smaller than the pore size were observed on the

surface. A significant number of paired holes can be

observed in this filter material. The latter substrate

offers the considerable advantage of retaining the particles

on one surface rather than permitting them to become

embedded within the filter.

Study of Asbestos Materials - A preliminary SEM examination

was made on six different bulk samples of asbestos minerals

mined at different localities. The specimens were freshly

fractured and then mounted on SEM stubs and coated by

sputtering with the Au-Pd alloy.

The typical fibrous structure of asbestos is shown in photomicrographs of three of the samples. Figure 2S. 7 is an

amphibole from Bozeman, Montana; Figure 25.8 is a crocidolite

from Grigualand, South Africa; and Figure 25. 9 is a crysotile from Globe, Arizona. A decrease m fiber

flexibility from amphibole to crysotile can be inferred. Also

observed were the random occurrence of small irregular

particles, probably inclusions of other mineral species, of

a nonfibrous nature. Mechanical shredding of this bulk

material could radically alter the observed appearance and

thus make identification of air collected asbestos particulates

by shape and size alone unreliable.

ESCA - Presented here are the results of our effort to evaluate

the utility of the ESCA technique for characterization of

the St. Louis particulate matter. Withdrawals from our

aliquot of the material have been examined in three different

ESCA machines

.

The major practical problem encountered in these measurements

is that of suitably mounting the material which consists of

all collected matter which passed a 50 mesh sieve. The

particles vary widely in physical characteristics and size[l]

are both organic and inorganic in nature f 11 .Mounting without

cements (using fine screens, heavily etch-pitted metals, and

154
soft metal substrates) was attempted and found wanting,

even in the DuPont machine where a favorable horizontal sample

mount is used. We therefore followed the practices of the

machine operators and employed cemented mounts: double sided

scotch tape for the Varian and DuPont machines, and a layer

of quick drying silver printed circuit paint for the MacPherson

instrument. In all cases, thick, apparently uniform layers

of the particulate matter were obtained, and effects of the

cement were estimated to be minimal.

In Table 25.1 are summarized the results of ESCA scans of 4

withdrawals studied as mounted, without cleaning. We give

here the intensities, relative to the C Is line intensity,

of the strongest observed line of each of the 14 elements

identified. The scans (labelled 1, 2, 3, and 4, and

identified in the Table 25,1 legend) covered a binding

energy range of to 1000 eV; some elements could have gone

undetected on account of this limitation. The cited errors

of Table 25.1 and later are the estimated counting errors in

the data. Results of 3 preliminary runs of the Varian

instrument are omitted here because of their high noise level.

In Table 25.2 we present the average of the Table 25.1 data,

and convert it to relative atomic concentration in the

radiating volume by means of measured relative core level

photoexcitation cross-sections [2] .Also shown in Table 25.2

are line intensities obtained from withdrawal No. 1 after

10 minutes of argon bombardment (at a current density

sufficient to erode away ISA of Si02 per minute, according

to the machine operator) , and the corresponding atomic

concentrations in the radiating volume.

The data for four separate scans on uncleaned, as mounted

particulate matter presented in Table 25.1 agree within the

noise. Scan 1 took ^ one hour, and scan 2 eight, on the

MacPherson machine; scan 4 12 hours on the Varian instrument;

and scan 3, comparable to the 2-hour scan 1 in signal to

noise ratio, was obtained in a 20 -minute run on the DuPont

machine which is designed for fast, low resolution scans.

Despite the time investment, only the C and Is intensities

are established with any real accuracy; the presence of the

other lines is established beyond question, but their

amplitudes are not accurately established.

The results for the sputter cleaned sample in Table 25.2

should more closely resemble the bulk composition of the

material, and it would be of interest to compare them with

the results of other analytic procedures.

155
Chemical speciation [3] is the real power o£ the ESCA technicjue.

We have made no attempt to identify the chemical species

present in the present sample, but the potential for such

identification is present and may prove of interest.

References

[1] . See the scanning Electron Microscope studies of this

material performed by the Microstructure Characterization

Section, 312.03. Amorphous, filamentary, and clearly crystalline

structures were observed. Pollen particles were frequently

seen and readily identified.

[2]. Jorgensen, C.K. ,and Berthou, H.j Faraday Pisa. , 54 ,1973.

[3]. Siegbahn, K. , Nordling, C, Fahlamn, A., Nordberg ,R. , Hamrin, K. , Johansson, G., Bergmark, T. , Karlsson, S.E.,

Lindgren, I., and Lindberg, B., ESCAjAtomioj Moleoular, and

Solid State Structure Studied by Means of Electron Spectroscopy

.

(Almqvist and Wiksells AB, Stockholm, Sweden, 1967).

156
Figure ' 25,1 St. Louis Urban Air Particulate Dust 1 mm

Figure 25.2 Disk shaped p.article is

pollen grain I

1 10 um

157
I ^fiA v,1^

Figure 25.3 Tentacle shaped object "A" related ^ ^ to a plant seed. Object "B" residue from an incinerated

hydrocarbon matexiaL

Figure 25.4 Large particle has fracture surfaced i -jq ^^ similar to glass

158
Figure 25.5 Similar to that seen in a cross

section of spruce wood 10 ym

I

: ~~1 10 \m

Figure 25.6 Polycarbonate nuclepore filter located in

final stage Delvon sampler 11/29/74

159
I 1 10 um Figure 25% 7 An amphibole from Bozeman

Montana

160
Figure

25.8

Crocidolite from Grigualand, South Africa,

10 ym

Figure 25.9

Crysotile from Globe, Arizona.

-| 10 um

161
i-H tSI O O• • ^ l/> LOvOiHKJfVIiHtOr-ICMOfMO l+loooooooooooo

d)P.s

ed W

•XJ<UC

rt

<D iH (/) O ^ C <D D -e€

1^ 3

•H 2

1/3 tH < •P «J

f: 15 o a £ u

a> Ti

i-H ^ w ^-j •H

M-i ^ O

Uio

•H

4J •H

to

p:

a> •p

Hi

I-H

0)>

•H

•P

cd iH

a> oi

r o eg o \o

IT)

(NJ

I-H o o

to

in r^ iH ro

1+ |o o o o o I o »o I O I O O I o o o t>-

(N)

rg ra o o• • t^00rOK>r>Ji-<r-li-IK)tHrH I + I+I0OOOOOOOOOO • o to O vO

00 LO o o

vOOtO^CSIrH<Mr-|tOiH + I+IO1-IOOOOOOOO O t-> O vO

0)>

1-3

(/) V) Q^V) d, pL, fX pL, Qt P^hJ H-I P< tf) i-liHtMiHCM<NltMrgf>J(M^^rsIiH

•p

iH

uou2cocos<cjaH2:cu(L,(t,

V)Co

•H

4J

C0O

•HMH

•H

R) P

•H 3

00 \o o o

iH iH X Xio

LO LO iH ( I >

9)U

O

O 3 ^1 (O 3

V) (/> en

0) (0 v>

V4 0) a>

fl 4J <-> 3 C C 033 goog g

<pCOO)

•H ftiO.

((} C0 ctf &<P 4J bO 0> 4) < iH iH

.0.0 •3 3 COO

OtJ-d

0) <p c:

CI4 O'H u avi

(0 3 0)

rg to ^

162
If) o

•H

+J •H

(/)

-p

• H

0)C

•H

t3

Ln«MO

E-o

O

>

<U

o

•H

+-> u

u < M-i

•H

V)

•P

p:

o

•H 4-» e o

o rt •M ^<

•H

V)

d) p

(U>

•H o

•H

nj toO P

r-l »H O

OS w

(U

p

1—1

r^fMt>>.tooocnvovovocnvO'^oo t^votOiHOLorgtoooooLO'^ '^(NJOOOOOOOOOOOO

OCMfSlOOi-HOOOOOOOO

o^tO(sioi-iLnoo^LOO"^'!i-iH LOOOrHrOrHCNJtOiHOOrHOrHO vOrHOOOOOOOOOOOO

LO t-^ LO LO OtOvOt^CMtOCsItHrgiHrsIOrHO OvOOOOOOOOOOOOO

r^ooouivoooorjoo^rjooo

CgvOOO^tOCsli-lrH^tOtOtOiHO

I—i«HCN)i-Hr«jtvitNi(sjrgrM!s^^rMrH

Cj -H bOiH t-i rt ^ (U rH uouzc/Dc/32<uai2CuUH(i,

to

d>

o

Jh

c

163
26. Development of a Particulate Reference Sample on Membrane

Filters for the Standardization of X-Ray Fluorescence

Spectrometers

Project Leader:

Other Personnel

P. A. Pella, Analytical Chemistry Division

E. C. Kuehner and W. A. Cassatt

Obj ective

In the analysis of ambient air particulates, the sample

analyzed is often in the form of thin deposits on either

membrane or Whatman type filters. Therefore, it is desirable

to have a calibration sample in thie same form. The preparation of orchard leaf deposits on membrane filters to be

used for this purpose is described in this report. The work

was supported by the Environmental Protection Agency.

Approach

The NBS Orchard Leaves (SRM 1571) as certified requires that

at least 250 mg samples be taken to insure that the trace

element distribution is representative of the bulk material.

To permit smaller samples to be used and to minimize the

attenuation of x-rays in the individual particles, the

material was reground. A number of different coatings were

investigated to provide good sample protection, and at

the same time obtain low attenuation of the x-rays from

elements such as phosphorus and sulfur. Different coating

164
materials that were investigated consisted of polyisobutylene,

heat-sealed overlays of polypropylene and Parafilm, and vapordeposited Parylene films.

Progress

Sample deposits were prepared by filtration of a suspension

of the reground material in cyclohexane. Attempts were

made to prepare deposits from an aerosol suspension, but

were not successful.

A. Grinding of the Orchard Leaves SRM 1571

A high velocity air impact grinder was used to reduce the

particle sizes. The impactor produces two size fractions

having relatively broad size distributions. The "fines"

fraction was collected after each pass through the grinder

and was reground four times. The particle size distribution

of the collected material was characterized by automated

image analysis. Data were taken by examining nine regions

of four different sample preparations. These samples were

prepared by dispersing a few milligrams of material in

cyclohexane with ultrasonic stirring. About three drops of

this suspension were placed on a microscope slide, covered

with a cover glass and allowed to dry.

B. Preparation of Deposits on Membrane Filters

From 2 to 15 mg of dried reground orchard leaves were weighed

and transferred to a 50 ml beaker containing about 40 ml of

spectrograde cyclohexane. The beaker containing the orchard

leaves was placed in an ultrasonic bath for about one minute

to disperse the particles. The suspension was transferred

to a vacuum filtering unit and the sides of the beaker were

washed down with cyclohexane. The material was filtered

rapidly through a 37 mm preweighed membrane filter (0.8 ym

pore size). The glass filtering funnel was constructed so

that deposits on the 37 mm membrane filters were 29 mm in

diameter. The net weight of the air-dried deposit was used

to calculate the areal density of the deposit in mg/cm^. All

weighings were performed in a room in which the relative

humidity was maintained at 50 +^ 4 percent.

165
C. Preparation o£ Parylene-Coated Samples

The samples were coated at the Union Carbide Corporation with

a thin film o£ Parylene N--a polymeric material developed

by Union Carbide Corporation (U. S. Patent No. 3342754). The

procedure consists of first vaporizing the di-para-xylylene

dimer by heating it at lyS^C at 760 mm Hg (1.01 x lO^N/m^)

.

This vaporized material passes through a deposition chamber

maintained at room temperature, and 0.1 mm Hg (13.3 N/m^)

which contains the samples to be coated. The samples are

rotated in the chamber to insure a uniform coating of Parylene

The exit of the deposition chamber is connected to a cold

trap (-70°C) and pumped with a mechanical pump to a pressure

of 0.001 mm Hg (0.133 N/m^) . The film thickness is monitored

in the deposition chamber using a piezoelectric frequency

sensor. More accurate thickness measurements were made at

Union Carbide after removal of the samples using a UV

spectrometer. The thickness is calculated from a calibration

curve by comparing the absorbance of the film with that of a film of known thickness measured interferometrically

.

D. Preparation of Thin-Film Overlays of Parafilm and

Polypropylene

A sheet of Parafilm (American Can Co.) was stretched by hand

as thinly as possible without causing the sheet to tear,

and was placed directly on the sample which was held by

suction to a filtering funnel. A polypropylene sheet (0.08

mm thick) was next placed on top of the Parafilm and was

heat-sealed to the sample using a hot air gun.

E. Mounting the Parylene-Coated Filter Deposit

Filter holders for mounting the deposits were supplied by EPA,

and are described in an EPA repori^ ] These holders,

designed to accommodate 37 mm diameter membrane filters, were

modified by increasing the platform diameter by 2 mm. This

permitted the filter deposit to be centered in the holder

more easily and also allowed for some expansion of the

membrane filter before cementing in the holder. The filter

deposit was held on a filtering funnel by applying suction.

A thinned mixture of cement prepared by mixing equal parts

of Barge all-purpose cement, ethyl acetate and cyclohexane

was brushed on the platform of the holder. The filter was

cemented to the holder platform by pressing the holder flat

against the outer edge of the filter deposit and then allowed

to dry.

166
Neutron activation analysis (NAA) of the reground orchard

leaves showed that the concentrations of iron, nickel, cobalt

and chromium were much higher than in the certified SRM 1571.

Therefore, it was important to determine if these introduced

elements were homogeneously distributed throughout the material.

For this reason, sixteen samples of reground material (200 mg

each) were taken and six elements, including iron and

chromium, were analyzed by NAA. An analysis of variance

of these concentrations in the material indicated that there

were no gross inhomogeneities (not greater than five percent)

.

These results indicated that the reground SRM 1571 was

satisfactory for use provided that recertification of the

introduced elements could be accomplished.

The particle size distribution of the reground material is

shown in Figure 26.1. The area of about 80 percent of the

3000 particles examined was between zero and 7.5 ym^ (3.1 ym

equivalent diameter). Less than 0.5 percent of the particles

were within 82.5 and 105 ym^, with no particles observed

above 105 ym^.

To determine if the cyclohexane treatment altered the trace

element composition of the orchard leaves, NAA was performed

on cyclohexane extracts and on the material after treating with

cyclohexane. A number of elements, including Br, Mn, Fe, K,

and Na were analyzed. The results showed that only sodium

was affected by this treatment, and about 50 percent was

extracted.

A simple technique was developed for measuring the uniformity

of the deposits. This consisted of directing a laser beam

about 2 mm in diameter normal to the sample, and measuring the

intensity of the light transmitted [2] .Using A Beer's law

calibration of absorbance vs. areal density, the uniformity

of the deposit was measured. Of the several samples examined

having areal densities of 1.0 to 2.0 mg/cm^, variations in

uniformity did not exceed 0.02 mg/cm^.

167
A number of coating materials were investigated and compared

with regard to their ability to adhere to the sample and to

provide protection from abrasion and humidity. These consisted

of vapor-deposited Parylene films and heat-sealed overlays of

polypropylene using Parafilm as a binder. Also, orchard

leaf deposits were prepared from suspensions in cyclohexane

containing from 0.1 to 10 percent by weight of polyisobutylene.

Another important factor considered was the x-ray attenuation

of these coatings, especially from elements of low atomic

number such as phosphorus and sulfur. The attenuation of P,

S, K, and CaKa lines was measured by comparing the background

corrected peak intensities of coated and uncoated samples

having the same areal densities using a wavelength-dispersive

x-ray spectrometer.

The values obtained for various thicknesses of Parylene and of

thin polypropylene and Parafilm coatings are summarized in

Tables 26.1 and 26.2, respectively. For Parylene coatings

75 to 193 nm thick, little change in attenuation was noted.

Also, the x-ray background intensities from these samples were

essentially the same as the uncoated samples except that the

background of the 2500 nm thick sample was increased

significantly. The attenuation values of the polypropyleneParafilm coatings could not be reduced any further because

thinner films were not available. In order to produce

adherent deposits using polyisobutylene, as much as one

percent or greater by weight of the polymer in cyclohexane

was used. However, the amount of polyisobutylene retained

on the samples varied considerably making it difficult to

obtain reproducible attenuation data. For this reason, this

coating material was considered unsatisfactory.

168
Table 26.1. Average Attenuation Values o£

Parylene Coatings^

2 sample areal density = 2.0 mg/cm

No. of Parylene Percent Attenuation

Samples Thickness, nm Element Average S"

5 75 P 3 1.7

3 75 S 2 1.3

2 75 K 1.4

5 117.5 P 3.1 0.50

5 117.5 K 1.7 0.44

5 158.0 P 5.4 0.90

2 158.0 S 5.2

4 158.0 K 2.9 0.35

7 166.5 P 5.0 0.81

5 166.5 S 4.3 0.92

7 166.5 K 2.6 0.69

5 193.0 P 7.3 0.88

3 193.0 K 3.7 0.20

3 2500 P 33 1.5

3 2500 S 28.9 0.71

2 2500 K 11.4

Calculated from the expression I -I^/I x 100; where I peak intensity of uncoated sample, and I = peak intensity

of coated sample.

S = standard deviation of a single measurement.

169
Table 26 2 Attenuation Values of Polypropylene

and Parafilm Coatings

Total Coating Percent Attenuation

2 Sample # Thickness, mg/cm P S CI K Ca

1 1.2 28.1 23.2 14.1 10.9 8.5

2 1.1 24.4 23.6 16.2 11.4 7.9

3 1.2 26.3 24.4 13.6 10.1 8.3

Average 26.3 23.7 14.6 10.8 8.2

The ruggedness of samples coated with Parylene films (75 to

200 nm thick) were tested by an air jet which impinged on

the sample surface. Effects of humidity were observed when

the samples were placed in a chamber maintained at 100 percent relative humidity.

The trace element composition of the starting material (dipara-xylylene dimer) was analyzed at Union Carbide Corporation.

Of the 27 elements analyzed, sodium, magnesium, iron and

aluminum were present in concentrations from 2 to 9 ppm.

Silicon was 31 ppm, and the remaining elements were either

below 1 ppm or were not detected. These results indicate

that the Parylene material should be of sufficient purity

for application in this work. Since the Parylene films

appeared to furnish good sample protection, including high

resistance to humidity, high purity, good adherence, and

acceptable x-ray attenuation for the low atomic number

elements, 60 samples were prepared and delivered to EPA

containing from 0.1 to 5.0 mg/cm^ of orchard leaves coated

with 117.5 nm of Parylene.

References

[1]. Goulding, F.S.,and Jaklevic, J.M., EPA Report No.

EPA-R2-7S-182, April 1973.

[2]. Kuehner ,E.C. , and Cassatt, W.A. , A Laser Miarophotometer

for Determining Uniformity of Particulate Deposits on

Membrane Filters ^ in press.

170
in

ur>

in

OS

O)

m

CO

d

CM

CM

OO

^" o

O OO E

^1

IT) Oi

LU

IT) CO

CO m cc

C_3 ^

p^ 1—

CO

CJE " od LU

Lfl :l CM

<

>

in <1 i OO

a

r~> cc

LU

LO < ^ CO LL. o

oc

LA Oi LU

CO CO LU

IE

o <

o

CM Cl

CO CO

Ln ^ csi CM LO

p '^

in *^ ^

LO

CO

lVAU31Ni 3ZIS NiHilM S313liUVd dO INBOUBd

Figure 26.1 Particle size distribution of reground material

171
27. Analysis of EPA X-Ray Calibration Standards by Isotope

Dilution Mass Spectrometry

Project Leader: I. L. Barnes, Analytical Chemistry Division

Other Personnel: L. J. Moore, L. A. Machlan, J. W. Gramlich

Objective

As part of a study by the x-ray analysis laboratory (ERC) at

the Environmental Protection Agency to develop accurate calibration standards for their energy dispersive x-ray fluorescence spectrometer, a set of vacuum deposited mylar foils was

analyzed destructively by isotope dilution thermal ionization

mass spectrometry (IDMS) at NBS.

A set of foils, with each foil containing a single deposit of

CuS, KCl, CaF2, Cr, Fe , Cu, RbNOs, SrF2, M0O3, or Pb was

analyzed for cation content by IDMS. The deposits were also

carefully characterized by EPA for uniformity using protoninduced x-ray emission analysis. The results of these calibrations indicate that disagreements as large as 15 percent

were observed between standards from the two commercial

suppliers

.

Follow-up analyses for Ca, Ba, Sr, and Pb by IDMS for a second set of filters have not yet been evaluated in an

effort to elucidate problems in the characterization of

these deposits for use as EDXRF calibration standards.

Summaries of the IDMS work at NBS and the goals of the EPA

project are presented in the attached report and publication.

172
July 14, 1976

Report of Analysis

A set o£ x-ray calibration foils (Set #2) was analyzed by

thermal ionization isotope dilution mass spectrometry for

Ba, Ca, Sr, and Pb . Four foils, each containing a single

element in the form of a salt or metallic deposit, were

each carefully removed from the supporting frames and spiked

with the appropriate separated isotope (° Sr, "^^Ca, ^^^Ba,

^°^Pb). After acid dissolution and isotopic equilibration,

each sample was purified by ion exchange and analyzed isotopically by well established mass spectrometric procedures.

A set of foils previously analyzed (1975) in a similar fashion

and reported in a publication [1] are also listed in table 27.1

for convenient reference.

The errors indicated are estimated overall limits of error

for a single analysis, which are based on a large number of

similar analyses previously performed for a particular element.

[1] Stiles , A. R. ,et al . ,Calibr.ation of an EDXRF Spectrometer,

Advanaes in X-ran Analysis, 19, (1975).

173
Table 27.1

X-RAY CALIBRATION FOILS

Total analyte, ymols -------

Estimated Limit of

Error for a Single

Set #1 Set #2 Analysis, Relative

Ba 1.154 1.067 0.20%

Ca 1.817 1.585 0.10

Sr 1.219 1.239 0.10%

Pb 1.142 1.007 0.10%

Mo 1.395 --- 0.20%

K 2.833 --- 0.15%

Cu 3.326 --- 0.25%

Fe 1.350 --- 0.70%

Cr 1.666 --- 0.25%

Rb 1.512 --- 0.15%

174
CALIBRATION OF AN ENERGY DISPERSIVE X-RAY FLUORESCENCE

SPECTROMETER

A. R. Stiles*, T. G. Dzubay**

*Northrop Services, Inc. and ^^Environmental Protection

Agency, ERC, Research Triangle Park, N.C. 27711

R. M. Baum*, R. L. Walter, R. D. Willis

Chemistry* and Physics Dept., Duke University

Durham, N.C. 27705

L. J. Moore, E. L. Garner, J. W. Gramlich, L. A. Machlan

U.S. Dept. of Commerce, National Bureau o£ Standards,

Washington, D.C. 20234

Abstract

The purpose of this work was to develop accurate calibration

standards which were fully characterized in terms of uniformity and concentration using fundamental measuring methods.

Three similar sets of vacuum deposits were commercially made,

each set containing the single deposits CuS, KCl , CaF2, Cr,

Fe , Cu, RbN03, SrF2 , M0O3, BaF2 , and Pb . Thickness variations

in each deposit were measured with PIXEA (proton induced x-ray

excitation analysis) measurements taken at 6 to 8 positions

along the deposit diameters. Relative elemental concentrations on corresponding deposits from each set were measured

using multiple XRF intercomparisons . One set of deposits was

destructively analyzed at the National Bureau of Standards

with isotope dilution thermal ionization mass spectrometry

(IDMS) in order to calibrate the remaining sets of vacuum

deposits. The calibrated deposits were compared with standards from two commercial sources. For seven elements

heavier than chlorine there was an average deviation of

13.51 between the calibrated deposits and the commercial

standards. Disagreements as large as 151 were observed

between standards from the two commercial suppliers.

Introduction

Calibration standards for thin sample analysis are available

commercially as solution deposits on membrane filters and as vacuum deposits on thin Mylar. Significant disagreements

between standards from different commercial sources have been

observed in our laboratory using an energy dispersive x-ray

fluorescence (EDXRF) spectrometer. Alternatives to the use

of commercial standards are the preparation of laboratory

calibration standards, using solution deposition, pressed

175
pellets, vacuum deposition or other techniques. The approach

adopted in this work was the accurate characterization o£

vacuum deposits on thin Mylar for 12 elements and preparation

of solution deposited two-element ratio standards for the

other elements of interest. The calibration program consisted of the following steps: 1. Characterization of the EDXRF

spectrometer. 2. Characterization of three similar sets, A,

B and C, of vacuum deposits for 12 elements using PIXEA to

measure uniformity and XRF spectrometry to establish interset

ratios for each element. 3. Destructive analysis at the NBS

of set A of vacuum deposits using IDMS (isotope dilution

thermal ionization mass spectrometry). 4. Calculation of

true concentrations and soft x-ray attenuation corrections

for foil sets B and C based on the IDMS results. 5. Preparation of two-element solution deposited ratio standards to

link the 12 calibrated elements with other elements of

interest

.

System Parameters

The EDXRF spectrometer calibrated in this study uses a 30 watt

tungsten anode x-ray source to excite three secondary targets,

Ti , Mo and Sm [1,2]. The Si (Li) detector has a guard- ring

reject feature [3] to reduce errors due to partial charge

collection. Spectral analysis is accomplished with a minicomputer using stored shape standards. The system is dedicated to the analysis of atmospheric aerosols collected on

membrane filters. A diagram of the sample chamber is shown

in Figure 27 . l^tandards and samples analyzed in this system

are mounted in plastic frames Figure27. 2awhich can accommodate

37 mm diameter specimens. Figures 27.2b and 27.2c are the result

of measurements to determine the sensitivity of the spectrometer to sample displacements and non-uniformities. The

sample plane, x-y, was mapped by positioning Pb-Sn solder

squares on graph paper substrates using a thin layer of

grease for adhesion. The importance of uniform thickness

for standards and samples is evident with this highly nonuniform beam configuration. The effect of displacements

along the z-axis due to warped or out-of-plane samples was

investigated using shims with both solder squares and

solution deposits on filter paper.

Most imprecision, exclusive of counting statistics, can be

ascribed to variations in the output of the x-ray tube. With

+^0.5% line voltage regulation, the count rate of this spectrometer can vary within +_ 1-51, depending upon the secondary

target and anode voltage. An additional + 2% (2a) uncertainty,

inferred from the residual errors in the XRF ratio measurements

described in the next section, is attributed to instability

176
CD

CC

^///'/77ZZZ//////A'

u

(D M

<Ueo

uo

p.

X

Q

O

e

x;u

rHP< W

4)

D

•H
V

E

E X

S

rt ^ Jk (U m £ PQ E ,bO

s rt o

+

1 rt X

75 •H

L <D X

^s. /—v^ Cti ^s. O 'H •V f^ '4H M X "-^ o - s.

^ < 1 1^^

z/^ 1

1 -

1

I -

__

CM

•-

1 ^

NK

//

/

-

CM

1 ~ ! CM

Co

n Cm (n Cm

t n

[\k

/

/ "

U— -

- CM

1

in

!

r-) .g^ CO

to

i (O

I

1 Co j rsi

t

1 c\ : —

! -

\

- \

K

i(

- CO fN Lf) lO to «D . iT)

1

1 ^ ro

1 -

"! \

\

(>4

f

1

^- CO Co CD

1

tf) i 00 IS oc ^X CO 00 1 r^ to tn

1

1 ^

!

i

1 i CN *** '»• > 00 (N <yi O) o O) O) O) ! 00 00 un lO 1 <% Cm 1

.

- -\

1

t

i _ _ 1 -- --1 1 3, i

1 i / .^\l 1 ^_ *- n o-j r- "^ 2 s 1° o , 2 <?) CT) CO 1 iD '^ — Cm /

Hh \

1

1 v-^

1 /

\

' !

i ! ' '\

— •- ro t^ (^ to 1 O) Oi o o o

i Si» 00 ^ Co

1 -

J 7

N

\

- - CN

1

If) U3 f> ir> lO 1 CO

i

Co - /

i

N

\ls.

i

""

1

- - f\l Cm *" - J/

/

^"3

N\\ y

^

y

^K ^»J o^^^ E

a. eCO "-J

^ ^ oc Em<>>4

II II CJ o

oi en 5S o

CO 2 ««

<1>

t-i

D.,

X

E

E a>&

tf) C

•H

(D tH•H

M-lO

u

P.I S

03

<U ,0

I

CMs? E35

178
within the high voltage supply; it is regarded as a short term

error, since its effects were observed in successive measurements of the same sample.

The effect of gain and baseline drifts in the pulse amplifier

and ADC was calculated assuming a Gaussian peak shape and a fit region equal to one FWHM (full width at half maximum)

.

A small peak shift in either direction causes an apparent

increase in elemental concentration when the spectrum is

analyzed with stored shape standards. Peak centroid shifts

in excess of 0.1 FWHM are rare, and the corresponding error

range is +2 -01. In routine sample analysis these errors can

be minimized with periodic adjustment of pulse electronics

and can be virtually eliminated with software that includes

mathematical spectrum shifting or functional peak representations .

Characterization of Vacuum Deposited Films

Essential properties for the elemental deposits characterized

in this study were 1) ability to withstand the beam-heating

of PIXEA with a 3 MeV proton beam of 5-20 nA, 2) uniformity

of the deposit thickness, 3) high XRF peak/background,

4) known area of deposit, 5) amenability to accurate attenuation correction, and 6) flatness. Properties 1, 3, 4 and

5 argued effectively for vacuum deposits on thin (4 ym) Mylar.

Accordingly, three similar sets of vacuum deposits on Mylar

were obtained, each set A, B and C consisting of the separate

deposits CuS, KCl, CaF2, Cr, Fe, Cu, RbNOs, SrF2, M0O3, BaF2

and Pb . A well defined area of 7.92 cm^ was obtained using

a circular, 31.75 mm diameter knife-edge aperture to mask the

Mylar during deposition. The deposits were centered and

mounted by the manufacturer (MicroMatter Co., Seattle, WA)

in the sample frames provided. The vacuum deposits calibrated

in this work were prepared by vacuum deposition at a distance

of 20 cm from the evaporator in order to obtain a uniformity

of +^ 21 or better. The deposits were not weighed by the manufacturer because the range of concentrations, 10-20 yg/cm^

,

was too low for a + 5% determination.

179
The uniformity of each vacuum deposit was measured using PIXEA

(6 mm dia.) spot measurements at 6 to 8 positions along the

deposit diameters. To minimize damage to the target films,

the scans were preceded by evaporation tests with zinc and

other volatile deposits; it was found that 3.0 MeV proton

currents between 10 and 20 nA were safe for all deposits for

periods of several minutes. Duplicate measurements were made

at each location on the films, each measurement an accumulation of more than 10k counts, to obtain better than II statistical precision. For all elements except S, K and Ba the

peak-to-background ratios were greater than 100, and it was

possible to make relative thickness determinations using a single channel analyzer and scaler to select and count the

characteristic x-rays. For the three exceptional elements,

an on-line computer code permitting background subtractions

and peak area calculations was used in conjunction with a CRT display to measure x-ray yields. Figure 27.3 shows the

PIXEA results for an iron deposit. While a standard deviation of thickness for this deposit was found to be 1.8%,

the center of the deposit where the EDXRF system is most

sensitive was not far, only 0.271, from the average deposit

thickness. This was true for most deposits, as indicated in

Figure2 7.4 a summary of the PIXEA results. Thus, non-uniformity

was estimated to have less than +_ 2% effect upon the accuracy

of these deposits as calibration standards.

Intraelemental ratios, A/B, C/B and A/C, among the three sets

A, B and C of vacuum deposits were measured using ten XRF

measurements of each deposit. For each element, the anode

current was adjusted in order to obtain no more than 2000

counts per second with the thickest deposit. The analysis

time for each element was selected to yield more than lOK

counts in the principal characteristic peaks and ranged

between 30 and 150 seconds, depending upon the excitation

efficiency and peak-to-background ratio. Peak-to-background

ratios ranged from only 2 for Ba to more than 100 for Pb.

Background subtraction was accomplished using a stored Mylar

blank spectrum and normalization to a background fit region

located above the characteristic peaks. Elemental ratios

among sets A, B and C were calculated using the integrated

peak counts over a region containing the characteristic peak

that was estimated to be large enough to minimize errors due

to centroid shifts while not seriously degrading the peak-tobackground ratio. The intraelemental ratios ranged between

0.4 and 1.6 with calculated uncertainties averaging about II

at the 95% confidence level. The error calculations indicated

that the XRF ratioing measurements contributed less than +1.5%

uncertainty to the eventual calibration of these deposits

following the NBS analyses. The residual imprecision, after

exclusion of counting statistics, was attributed to short-term

instabilities in the high-voltage anode supply.

180
— t * -^

to

CO ao O ,_

a.

cc

c/) 1- o

u C/3 H- ao O

^B ^3

ao «M

<F- cn

II II 2» D

i

CM

" i

QC

UJ

<

O

<D

O

.J<

m

CO

oa.

pg

O)

ID

NVBIAIOlOliVU

Figure 27.3 PIXEA uniformity measurement of Typical Iron Dust

181
1 T 1 1

1 o D — o a

.a

a. — o o

D — <^

o

o

D —

o -

sa — o O- — o D — oS — o Ia — DO — o D — A — o —

O D — s O D — .a

OC — a

oc OD

u.

DEVIATION

AS

OF

MEAN.

k2 CO

5s

H-Z

Ui

u. U O OC o

o

o

o

Dl

D-

-C

O3U

3

z

UJsUi

—J

Ui — 5»-

< oc t- Ui

(/>a.

Sv,

t-<

SEz ><Ui Ui as

II a D o

o

o

D —

OD—

D — U

—

o

o

o

D

a

D— la U — o a — O D i£ — D- — o D — o o u — D- — o D — o - Qcrt

1

1 1 1 1

O

I D —

1 «»• r> Cii e> iN33U3d

(/) M

t—

1

D

t/5 <D a:

<NJ X-H

+-> •H ?H e o

5-( M-i O

"4H U H

C XI D c

03 <

W •> X m

1—1 •> Ph <

trt •^ +j

. -H

I>- t/l <NI O t/i a,-M

(U 0) c

^ -o p e

bO ^-1 0) •H O .—

1

PL, m <u

182
IDMS ANALYSES

Modern isotope dilution trace determinations by thermal ionization mass spectrometry, in conjunction with chemical matrix

purification techniques, have resulted in optimal precisions

and accuracies (L 0.1%) that have been equaled by no other

analytical technique. The efficacy of IDMS, when rigorously

and properly applied, accrues primarily from four sources:

1) The use of an internal standard (the separated isotope)

which is atoms of the analyte itself. The accuracy of IDMS

is therefore not measurably affected by non-quantitative

recovery, as long as a reasonable percentage of the original

sample is recovered. 2) The purification of the analyte by

ion exchange and other separation techniques, so that a pure

sample is derived for isotopic analysis. 3) The present

capacity to measure, very precisely and accurately and with

a minimum of spectral interferences, stable isotopic ratios

of small samples via thermal ionization mass spectrometry.

4) The use of well characterized isotopic and stoichiometric

standards and related materials. These four components result

in the control or elimination of interferences which often

occur with techniques that rely on the observation of some

secondary property of the analyte and not the atoms themselves.

The demonstrable accuracy of IDMS uniquely qualifies it as a tool for the evaluation of other analytical methods that are

less fully developed. IDMS is currently being applied at NBS

in such a role to develop reference methods of clinical

analysis for the determination of electrolytes in blood serum

by atomic absorption/emission techniques.

The pre-characterized vacuum deposited films were carefully

removed from their mounting frames while held over a beaker.

To each beaker containing a sample was added an accurately

weighed (+ 0.011) isotopic spike solution of the corresponding

element tPTat had been highly enriched in one of its stable

isotopes (^°°Mo, «'*Sr, '^Ca, ^oep^^^ evj^^^^ syp^^ m^^ 65^^^ or

^°Cr). The concentration of each spike solution was calibrated

to within 0.1 - 0.2% by comparing it to a natural solution of

the particular element which was gravimetrically prepared from

well characterized isotopic and stoichiometric standards. After

acid dissolution and isotopic equilibration, each spiked sample

was purified by ion exchange or extraction.

Isotopic measurements were made using well established procedures [4,5,6] on NBS designed and built single focusing magnetic sector mass spectrometers, capable of providing stable

isotopic ratio measurements to less than +_ 0.05% [ 7]. The

fractionation error induced by thermal ionization was corrected

either empirically by analyzing samples in a manner identical

183
to that o£ a standard o£ known isotopic composition or, for

elements of three or more isotopes and adequate signal intensity, by internal normalization to a constant natural isotopic

ratio.

A separate Pb deposit was isotopically analyzed in order to

minimize the effect of radiogenic isotopic components on IDMS

accuracy. For Sr, a similar in situ correction was made for

the radiogenic ®^Sr.

The measured chemical contamination from the chemical processing was very small. Except for Fe , the analytical uncertainty

for all elements was less than or equal to 0.25% (relative to)

[5] the Fe uncertainty was less than 0.7% due to a higher contamination level.

Calibration of Deposits

The two remaining sets of vacuum deposits B and C were calibrated using the IDMS results for set A, the XRF ratios, and

the known deposit area of 7.92 cm^ . The element chlorine was

calibrated by assuming stoichiometry for the KCl deposits + 21.

S and Ba were not analyzed with IDMS and will be calibrateH"

using an accurate alternative method at the NBS. Attenuation

corrections for representative concentrations of S, K and Ca

using Ti excitation are shown in Table 27. 2. These values were

calculated with the expression [3] .

A =(l-exp(- (y^ sece^ + y^ secS^) pd) )/ (y^ secB^ + y^ seceQ)pd,

where \i± and yo are the total mass absorption coefficients

(cm2/g) for the incident and observed radiation respectively,

Q^ and Bq are the angles of incident and observed radiation

with the normal to the^ sample plane resr)ectively and od is the

concentration of the deposit (g/crn^) . Two cases were considered for each attenuation correction. The CuS deposit

was prepared by sulfiding a copper vacuum deposit with sulfur

vapor; precipitation of the sulfur onto the copper might also

have occured, but the sulfur attenuation correction was

estimated by assuming that the formation of copper sulfide

was more likely. All deposits with soft characteristic x-rays

were examined under a microscope, and the KCl deposits were

found to be granular with particle thicknesses estimated to

be 2.5 times the average deposit thicknesses; the attenuation

correction for potassium was estimated to be somewhat closer

to the value obtained for the granular case. Since none of

the x-ray attenuations exceeded 4%, the estimated uncertainty

in these is no more than 1%.

184
Table 27.2

ATTENUATION CORRECTIONS

Case yg/cm2a

S(Ka), Sulfide 10.0

Precipitate

A(Calculated)

0.974

0.996

ACEstimated)

0.98

K(Ka) , Layer

Granular (2 . 5)

10.5 0.985

0.963

0.97

Ca(Ka) , Layer

Granular (2 . 5)

13.6 0.993

0.982

0.99

Concentrations of S, K and Ca in CuS, KCl and CaF2

respectively.

185
Solution Deposited Ratio Standards

Solution deposited ratio standards were prepared in order to

link the twelve elements calibrated via NBS analyses with

other elements of interest heavier than chromium. The solutions, each containing two elements, one of which was a calibrated element, were deposited onto filter paper with

a depositor consisting of a precision capillary matrix.

Freeze drying was employed to minimize chromatographic effects.

Principle advantages of this technique are repeatability and

overall uniformity, both near 3% [8,9]. A disadvantage is

that the capillary deposits, like all solution deposits, are

not easily corrected for soft x-ray attenuation. A more

complete description of this new technique for solution

deposition is given in the literature [8,9].

Results and Discussion

Elemental concentrations in routine XRF analyses of samples

are calculated using the expression,

C^Cng/cm^) = I2N/F2,

where C^ is the concentration of element Z, I7 is the total

number of counts contained in the principal characteristic

peak for element Z after background subtraction, N is a normalization constant near unity, and F2 is a calibration

constant or F-number for the element Z. Figure 27.5 shows

F-numbers that were obtained previously using commercial

calibration standards. Because of the unexpected outcome

of XRF intercomparisons between the IDMS calibrated deposits

and commercial standards discussed in later paragraphs, new

F-numbers have not yet been obtained. F-numbers for the

twelve elements studied here will be obtained experimentally,

while those for intermediate elements will be calculated

using XRF data from the solution deposited ratio standards

and a weighted nonlinear least squares fit to a smooth calibration curve [3]. Elements lighter than sulfur will be

calibrated with vacuum deposited standards instead of

solution standards.

Table 27.3 lists the uncertainties associated with data acquisition with samples using the calibrated XRF spectrometer.

Entries 1 through 5 in table 27.3 have been discussed earlier.

The last entry includes, for the twelve elements calibrated with

NBS analyses ,, the .combined uncertainties (rounded upward).

186
(K.i)

(L, I'l L.l

Pb

CONCENTRATION (Z) f^^'^^-N m ng/cm2

WHERE N NORMALIZER 1

SO

20

10

10 20 30 1

40 SO ATOMIC NUMBER IZI

60 70 8C

Figure 27.5 EDXRF calibration constants for Ti(^) Mo (<>•)

and Sm (a) secondary targets

187
Table 27.3

Error Analysis

1. Sample X-Y-Z Displacement

2. Anode KV- I Drift

3. Peak Centroid Shift

4. Counting Statistics

5. Attenuation Corrections

6. Calibration

±2I,X-Y

±2%,Z

±2%, Short T(2a)

±1-51, Long T ±2-01,0.1 FWHM Shift

±21 ,10k Counts (2a)

±1% , Calibration

Standards

±4I,NBS-Calibrated

Elements

±6-10%, Other

Elements

188
in uniformity, intraelemental ratios, NBS results, attenuation

corrections, and 21 for the F-number determinations. The

ranges of uncertainty for other elements, +_ 6-101, are estimated, and will be reviewed upon completion of the calibration

study.

XRF intercomparisons were made between solution deposited

standards from Columbia Scientific Industries 2 (CSI) and

vacuum deposited standards from MicroMatter Company ^ (yM)

for the elements S, K, Ca, Cr, Fe , Cu, Mo, Ba and Pb . Each

calibration standard was analyzed three times, and a relative

standard deviation for the averaged results was less than

3.5% in each case. Background subtractions were accomplished

by normalizing stored blank spectra to fit regions located

above the characteristic peaks. Attenuation corrections were

applied to elements lighter than Fe; these are listed in

Table 27.4. Figure 27.6 shows the results obtained with the

expression [ I/AC] csi/ [I/AC] yM» where I is the average number

of counts in the principal characteristic peak, A is the

attenuation correction, and C is the elemental concentration

specified by the manufacturer.

A second XRF intercomparison was made, ratioing the same

standards from CSI and yM to the vacuum deposits which had

been calibrated with IDMS analyses. The procedure was

identical to that used in the above intercomparison. The

average ratio was 0.85 with CSI standards for the elements

K, Ca, Cr, Fe , Cu, Mo and Pb . The yM standards averaged 0.88

for the same elements. A comparison between the capillary

deposits and the calibrated vacuum deposits produced an

average ratio of 0.97 for the elements. Cr, Cu, Sr, Mo and Pb.

The systematic disagreement with both CSI and yM standards was

unexpected, especially in view of a general agreement with CSI

solution deposited standards reported by many laboratories in

a recent round-robin study [10]. A review of the methods used

in our work failed to explain a systematic error of appreciable

magnitude. Indeed, the review served to increase confidence

2 Columbia Scientific Industries, Austin, Texas. The CSI

sulfur standard had an "ultrathin" Millipore TAWP substrate.

Other CSI standards used Millipore SMWP media.

3

The MicroMatter standards intercompared with CSI and IDMScalibrated standards were commercially prepared and were

gravimetrically determined by MicroMatter Company.

189
Table 27.4

ATTENUATION CORRECTIONS FOR CSI AND yM STANDARDS

McmJ MZ^iiiicsii AMI HiZ^miML |

S 0.77 41.10 0.91 28.0

K 0.67 5.41 0.94 43.0

Ca 0.72 35.14 0.96 56.4

Cr 0.93 33.64 0.99 74.0

Columbia Scientific Industries, Austin, Texas. The CSI

sulfur standard had an "ultrathin" Millipore substrate

Other CSI standards used Millipore SMWP media.

The MicroMatter standards intercompared with CSI and IDMScalibrated standards were commercially prepared and were

gravimetrically determined by MicroMatter Company.

190
] 1' ! T'

?

CME

u

c/a O

T)

^^

cd T»

CJ

R) <P

c

o

P

i o

3. •d

r-o

u

o

o

v> •H

CO&

O

o

X

J L_J L-_i

(Uu

3

•H

PL,

191
in most aspects of the program. The good agreement with the

capillary deposits was equally surprising, considering the

relatively brief experience with that technique.

Results of preliminary vibrational tests suggest that material

losses from vacuum deposits sent to the NBS might have occurred;

nearly 5% of one deposit, CaF2, and less than 1% of three other

deposits were dislodged in these five-minute tests. Such

losses in greater quantity could account for the kind of

disparities with CSX and yM reported above. More tests are

planned in order to check actual losses that occur in mailing

calibration standards, particularly vacuum deposits on thin

Mylar. Meanwhile, a second set of pre-ratioed and -characterized deposits will be hand carried to the NBS for analysis.

Conclusion

The comparison shown in Figure 27.6 is sufficient provocation for

a concerned user of XRF spectrometry to initiate an independent calibration study. The results of this carefully planned

and executed study suggest that too little attention has been

paid the possibility of degradations in the accuracy of calibration standards while in shipment use and storage. The

possibility that vacuum deposits undergo material losses in

transit is being investigated: if losses occur, then frequent

use and handling might also affect accuracy. Experience in

this laboratory has shown that solution deposits, though free

from mechanical losses, can be expected to lose accuracy

through warping and, in some cases, to crack and tear. Thus,

while obtaining an accurate calibration for an XRF spectrometer is the principal objective of this continuing effort,

additional information will be sought regarding the stability

of calibration standards and the validity of the intercomparisons discussed in this report.

192
References

[1]. Goulding,F . S . , and Jaklevic,J. , "X-ray Fluorescence

Spectrometer for Airborne Particulate Monitoring" ,£'P4 Report

No. EPA-R2-73-182 (1973).

[2]. Dzubay,T.G., and Stevens, R.K., "Ambient Air Analysis

with Dichotomous Sampler and X-ray Fluorescence Spectrometer",

Envir. Soi. and Teoh. ^9, 663-668 (1975).

[3]. Giaque, R. D. ,Goulding ,F.S., Jaklevic, J.M., and Pehl,R.H.,

"Trace Element Determinations with Semiconductor Detector

X-ray S^ectr omet ex s'\ Anal. Chem. , \S_, 671-681 (1973).

[4]. Barnes, I.L., "Determination of Lead, Uranium, Thorium

and Thallium in Silicate Glass Standard Materials by Isotope

Dilution Mass Spectrometry", Anal. Chem. ^ ^S_y 880-885 (1973).

[5]. Moore, L.J., Machlan, L.A., "High Accuracy Determination

of Calcium in Blood Serum by Isotope Dilution Mass Spectrometry",

Anal.Chem. ,^^_, 2291-2296 (1972).

[6]. Moore, L.J., Machlan, L. A. , Shields, W.R.and Garner, E.L.,

"Internal Normalization Techniques for High Accuracy Isotope

Dilution Analyses- -Application to Molybdenum and Nickel in

Standard Reference Materials", Anal. Chem. , A6_y 1082-1089 (1974).

[7]. NBS Teohniaal Note #277 ^ "Analytical Mass Speatrometry

Section: Instrumentation and Procedures for Isotopic Analysis,"

edited by W.R. Shields (1966). Available from Supt. of Documents

U.S. Govt. Printing Office, Washington, D.C. 20402.

[8]. Baum, R.M. , Gutknecht, W.F., Willis, R.D. and Walter, R.L.,

"Preparation of Standard Targets for X-ray Analysis", Anal.

Chem. 47_, 1727-1728 (1975).; see also^na^. Chem.,A6y 843-855

(1974).

[9]. Baum, R.M. , Gutknecht, W.F., Stiles, A.R. and Walter, R.L.,

"Standard Solution Deposits using a Capillary Matrix and

Lyophilization" , to be presented at Symposium and Workshop on

X-ray Fluorescence Analysis of Environmental Samples

,

Environmental Sciences Research Laboratory, EPA, Research

Triangle Park, N.C., January 26-28, 1976.

[10]. Camp, D.C, VanLehn, A.L., Rhodes, J.R., and Pradzynski,

A.H. , "Intercomparison of Trace Element Determinations in

Simulated and Real Air Particulate Samples", X-ray Spectrometry

,

4, 123-137 (1975).

193
28. An Evaluation of Equipment and Procedures Used in the Department of Interior Respirable Coal Mine Dust Sampling Program^ [1-2]

Project Leaders: Wayne A. Cassatt and Edgar S. Etz,

Analytical Chemistry Division

Objective

This work was done in response to a request from the Senate

Committee on Labor and Public Welfare to "evaluate and report

on the adequacy of:

(1) the approved personal dust sampling equipment used in

the assessment of respirable coal mine dust concentrations in

underground mines,

(2) the procedures used by the Department of the Interior

(DOI) in the evaluation of the dust samples obtained under the

coal mine operator's dust sampling programs, and

(3) any recent studies made by the Department or private

industry concerning the coal mine dust sampling equipment."

In particular, the Bureau was requested to determine the overall accuracy of the measurement results produced under the

coal mine dust sampling program as it is implemented and

administered by the Mining Enforcement and Safety Administration (MESA) of the Department of the Interior. During

subsequent discussions with the Senate Committee staff, the

Bureau was asked to comment on the advantages and disadvantages of the area sampler concept, i.e., the use of a stationary sampling device to sample the atmospheric dust

concentration in the surrounding area.

Approach

The Chairman of the Senate Committee requested that the Bureau

coordinate its technical evaluation with a larger, overall

study of the respirable mine dust sampling program being conducted by the General Accounting Office (GAO)

.

To produce the information and data needed for the technical

evaluation, the NBS staff, in conjunction with members of the

GAO, planned and carried out the following activities: (1) a literature survey of relevant studies conducted by other

organizations, (2) personal interviews with officials,

scientists and mine personnel who are participating in the

mine dust program, (3) visits to coal mines, (4) examination

194
of approved dust sampling equipment, (5) a series of sample

weighing experiments performed at NBS and at program laboratories, and (6) the submission of a group of preweighed dust

cassettes which were introduced as test samples into MESA's

sample processing system.

The federal dust standard, enforced by MESA, calls for the

dust loading in the mine atmosphere to be controlled by the

mine operator such that the average concentration of the

respirable fraction of this dust does not exceed 2.0 mg/m^

.

This average is determined from 10 eight-hour samples collected

with a personal sampler worn by a miner performing a "high

risk" task in each coal mine section. The sampler consists

of an air pump preceded by a fine dust filter which is in

turn preceded by a cyclone separator which removes the large

dust particles that ordinarily do not enter the miner's

respiratory tract. The dust filter is weighed before and

after sampling to yield a gravimetric measurement of the

respirable dust mass. The dust concentration is calculated

from this mass and the total air volume that has flowed

through the filter during the collection period.

Progress

The mine visits, the weighing experiments and the submission

of the test samples were undertaken by NBS scientists in

cooperation with members of the GAO and the Department of the

Interior.

Major Conclusions

Examinations of the personal sampler by NBS and other organizations reveal that this is a "state-of-the-art" instrument

that has no proven peer in this application, but the sampler

has exhibited certain important limitations during the five

years that it has been utilized in the enforcement program.

As of February 1975, at the end of the experimental portion

of this study, one or more of the approved sampler models

exhibited the following shortcomings: (1) the filter capsule

lost weight while in use, (2) the air flow was difficult to

adjust and maintain during use (3) the sampling head was

difficult to assemble correctly and could be knocked out of

alignment by physical impact (4) the actual volume of air

sampled was not indicated by the instrument (5) simultaneous

inversion and impact of the sampling head could contaminate

the dust sample with non-respirable particles and (6) the

sample could be altered without being detected. Since

February 1975, the National Institute for Occupational

195
Safety and Health (NIOSH) , who is responsible for the approval

of these samplers, has taken remedial action which NIOSH

officials believe will correct difficulties (1) and (3) in

this list. Since that time MESA has awarded R^D contracts

to various organizations to develop sample air volume indicators and to design filter cassettes which are tamper proof.

The sample weighing process, as administered today by MESA,

yields an uncertainty in a particular dust mass determination

that is represented by a standard deviation of 0.14 mg/m^

which is equivalent to 7 percent at a dust concentration of

2.0 mg/m^. The air flow rate in the sampler can be adjusted

with a 5 percent precision when care is exercised. When

operated in the laboratory the sampler has yielded a precision on the order of 7 percent as evidenced by a standard

deviation of 0.14 mg/m^ at the compliance level. The in-mine

studies conducted by other organizations show that trained

scientists, experienced in analytical measurement work, can

achieve dust concentration measurement results with uncertainties ranging from 7 to 50 percent which are equivalent

to standard deviations of 0.14 to 1.0 mg/m3 at 2.0 mg/m-^.

The smaller uncertainties were achieved when these scientists

exercised the most meticulous care and supervision of the

instruments during measurement. An analysis of these uncertainties has provided a basis to estimate that when trained

analysts conduct the sampling and report the result as the

mean of the measurements obtained from 10 samples, this mean

will lie within 20 percent (0.39 mg/m^ at the compliance

level of 2.0 mg/m^) of the "true" mean with 95 percent

probability. The uncertainty to be expected in the normal

program operations, i.e.,when the miners and mine operators

perform and supervise the sampling and when the weighings are

made in the normal manner, is estimated to be as large as 31

percent or 0.63 mg/m^.

The personal dust sampling equipment currently used in the

MESA program appears amenable to a number of improvements

which would be expected to reduce each of the errors identified above to a significant degree, but this remains to be

demonstrated. The more important improvements should come

from redesign of the filter cassettes, one of the filter

capsules and the air flow meters.

The total reported experience with area samplers is insufficient to provide NBS scientists with a sound basis for a final assessment of this device. The area sampler does appear

to offer several advantages which suggest that it may be a desirable complement to the personal dust sampler, but again

this remains to be demonstrated.

196
References

[1]. "An Evaluation of the Aaauraoy of the Coal Mine Dust

Sampling Program Administered by the Department of the

Interior"3 a. Final Report to the Senate Committee on Labor

and Public Welfare. Prepared by the staff of the Analytical

Chemistry Division, NBS. P.D.LaFleur, Chief, Institute for

Materials Research, NBS. Issued and submitted to the Congress

December 1975.

[2]. "Improvements Still Needed in Coal Mine Dust Sampling

Program and Penalty Assessments and Colleotions"jRepovt to

the Congress by the Comptroller General of the United States,

Elmer B. Staats. Prepared by the staff of the U.S. General

Accounting Office. Released December 31, 1975.

197
29. X-Ray Fluorescence Analysis of Air Particulates

Project Leader: K. F. J. Heinrich, Analytical Chemistry

Division

Other Personnel: R. L. Myklebust, M. M. Darr, P. A. Pella

Obj ective

This work was undertaken in order to evaluate the relative

merits of several configurations of both dispersive and nondispersive x-ray fluorescence analyzers with respect to their

applicability to the analysis of airborne particulates collected on filter paper.

Approach

Recent advances in Si (Li) solid-state detectors used in energy

dispersive x-ray analysis have improved their resolution and

sensitivity to an extent that the analysis of air particulates

on filter paper is now possible. These advances have provided

competition for the previously existing technology of x-ray

spectrometry using wavelength dispersion by crystal monochromators . However, developments in each of these areas have

made uncertain the relative merits of each arrangement in

terms of sensitivity, accuracy, economy and ease of use. The

results of this project will provide data that will allow

rational decisions to be made regarding the choice of a most

suitable configuration.

Progress

We have selected two instrumental arrangements for experimental testing. The data thus far produced should serve as a guide to the choice of configuration of apparatus most appropriate for the analysis of airborne particulates.

In the energy dispersive arrangement, we have been able to

produce effective excitation of the x-ray lines of interest

while minimizing background radiation. An apparatus was

constructed which uses an x-ray tube to generate characteristic x-rays from a secondary target which excite the

specimen (See Figure 29.1.). This secondary target reduces

the scattering of polychromatic bremsstrahlung radiation

generated in the x-ray tube, thus reducing the background

level. Detection is accomplished by means of a Si (Li)

solid-state detector and multichannel pulse height analyzer.

198
The wavelength dispersive apparatus is a commercial, singlechannel x-ray spectrometer which uses crystal monochromators

.

The x-ray tube, crystal, and detector can be selected to produce the most efficient excitation and the optimum x-ray

signal to background ratio for the element being measured.

A preliminary comparison of the two methods was made using NBS

Standard Reference Material (SRM) 1571 Orchard Leaves. This

powdered material is well characterized for some of the elements of interest to air pollution studies, such as copper,

zinc, and lead. The initial tests indicated that the elements

lying between manganese and lead in the periodic table can be

detected at levels of 1 to 3 ppm when using the wavelength

dispersive method. For energy dispersive x-ray analysis,

similar detection levels have been reached when the appropriate conditions are properly selected.

In order to perform quantitiative analyses of air particulates

on filter paper, standards must be available which consist of

known amounts of a well-characterized particulate material

distributed on filter paper. Such standards have been prepared

for obtaining calibration curves for iron and manganese by

filtering from liquid suspension Standard Reference Material

cements, glasses, iron oxide and manganese oxide and depositing

th.ese materials on membrane filters. About 900 yg of material

per cm2 of filter paper was deposited in each case. The iron

calibration curve obtained with the wavelength dispersive

system is shown in Figure 29.2 (up to 30 yg/cm^ of Fe) and in

Figure 29.3 (same curve extended to 300yg/cm^of Fe).The data all

fall on the same straight line ; therefore , for these specimens,

^?ith?T the particle^size nor^the matrix material have any significant effect. The dara for manganese are also m agreement with these results.

Some real air particulates collected on filter papers have been

analyzed for iron and manganese. These samples were obtained

from Columbia Scientific Industries and are being used for

inter-laboratory comparisons. Our iron and manganese determinations will be sent to Columbia Scientific; however, their

results are not yet available.

Preliminary work with the energy dispersive system indicated

several possible changes that might be made for improving the

sensitivity and stability of the system. These changes have

recently been made and the quantitative tests using the iron

and manganese standards will be repeated with the improved

energy dispersive instrument.

199
o

d=h

a>

Figure 29.1 NBS Energy-dispersive (non-diffractive) x-ray

fluorescence apparatus

200
1 1 1 1 1 1

150 — /

<' —

•£ 100 /

/

e

u

M //

M

e /

50

1 1 1 1

1 1 10

/xg Fe/cm

20

2

30

Figure 29.2 Iron intensity from filter paper standards

versus iron concentration

201
300

fig Fe/cm'

Figure 29.3 Iron intensity from filter paper standards versus

iron concentration (curve extended to 300 yg/cm^ of Fe

202
30. Instrumentation for Particle Sizing

Project Leader: M. L. Greenough, Measurement Engineering

Division

Other Personnel: J. Cohen, R. Frisch, E. C. Palasky

Objective

Instrumentation is being developed for determining the size

of particles in the 0.1 to 5 micrometer diameter range, based

upon the selective forward scattering of a light beam across

which the particles are caused to flow. The instrument development was funded by the Environmental Protection Agency.

Approach

The general approach follows that was proposed and experimentally

verified by Dr . C. C. Gravatt of NBS, Polymer Division. Specifically the goal is to detect the light scattered in narrow

conical bands located at 5 degrees and at 10 degrees from the

beam axis. The ratio of the light levels in the two bands is

extracted for individual particles during transit. These ratio

indications are summed in a small computer for periodic printout of numeric distribution according to particle size.

The system is built around an argon ion laser whose beam is

focused as it enters the sample cell. The air sample being

measured is passed through the cell, after being extracted

from an overall intake manifold. When particles contained

in the air pass through the narrow laser beam, the small

amount of scattered light is transmitted through a conical

mask assembly called the director, to two photomultiplier

tubes. These tubes are the sources of analog signal pulses

whose relative amplitudes during coincidence are predicted

to be dependent upon size of the particle initiating the

scattering. Detection is in two conical bands each one

degree wide, at 5 and 10 degrees from the beam axis.

The pulse signals are fed to an interface unit providing the

interconnection between the optical signals and the computer.

In the interface the 5-degree signal is applied to 32 threshold

comparison circuits which have appropriate voltage dividers.

To the other side of the comparison circuits is applied the

10-degree signal. Whenever the 10-degree signal exceeds the

threshold fraction of the 5-degree signal, a digital output

is created. The output of the 32 comparison circuits is to

be recoded in a computer word developed on the basis of one

203
eight-bit byte for each discrete particle which is detected.

Thus eight bits in the word convey the information regarding

particle size. At the end of the pulse time this work is

transmitted out of the interface buffer to be accumulated in

the computer's memory according to bit contents.

At periodic intervals, perhaps five minutes or as desired,

the computer will print out a report giving the distribution

of accumulated particle sizes, using the teletype unit which

is to be a part of the computer system.

Progress

The instrument was completed and made ready for delivery to

its sponsor, the Environmental Protection Agency. The major

phases of activity were:

1) Mechanical Design and Construction

The various components were mounted into the 115-centimeter (45-inch) high rack cabinet. This included the

computer, electronic signal-processing circuits, computer

interface, laser power supply, other power supplies and

the vacuum pump. The optical assembly at the top of the

cabinet comprises the laser, sensing head photomultiplier

tubes and flowmeter. With an additional teletype unit

associated with the computer, the complete system weighs

approximately 125 kilograms (275 pounds)

.

2) Computer Program Preparation

Documentation supplied by the manufacturer of the computer

was found to be limited for a machine of this small (4k

words) size. Consequently it was necessary to prepare

several utility programs in the beginning. The operating

program was written with the aid of a remote -terminal

editor system, followed by steps of manual and machine

translation to produce the working paper tape program.

In operation, printouts of the distribution of detected

particulates are made at intervals under the control of

the operator. The printout shows the accumulated contents

of each ratio category, for example 10 to 13 percent, 13

to 16, and so on. These output data may then be plotted

to furnish graphic indication. Approximately 20 percent

of the machine memory capacity is used by the operating

program, leaving considerable room for later expansion

if desired.

204
3) Testing, Operational Experience

In trial operation a few modifications were found necessary

One of these was the optical calibrator which enables setting of the gains for the two phototubes. The fine -wire

arrangement originally planned proved to be too critical

in positioning. It was replaced with new yoke carrying

an optical diffuser and a neutral density filter. When

the yoke is extended into position, the laser beam is

attenuated and scattered approximately uniformly, reaching

both the phototubes. Gain adjustment is then accomplished

by varying the supply voltage on each phototube until its

output signal reaches a designated value. Retraction of

the yoke then permits normal action.

Additional provisions for operational verification allow the

electrical insertion of dummy signal ratios obtained from a test panel control. With this technique the ratio-determining

circuits we found capable of a dynamic signal range of 100 to

1 with no more than one step (3%) error. Although this is a wide range, there is a possibility than an even larger one

may be needed to cope with the desired span of particle size.

More operational experience should show whether recalibration

will be necessary to cover the extremes of particle size, or

whether the present lOOX dynamic range is sufficient.

One of the extrapolations from the original experiments was

a prediction that a low-power laser should be adequate for

the system, in view of certain optical changes introduced in

the design. This assumption proved justified; the signal

levels were such that the laser could be operated at half

power or less, increasing its useful life.

Polylatex spheres of several sizes in the range of 0.3 to 3

micrometers were introduced into the inlet port and the resultant distribution of ratios noted. Although it is too

early to say what the ultimate discriminatory ability of the

system will be, the preliminary results are quite promising.

In order to quantify the particles used so far, electron

microscope images have been produced and examined. The

particles have been noticeably egg-shaped, which is entirely

in keeping with the asymmetrical characteristic noted in the

indicated distribution.

The instrument was delivered along with requisite documentation

to the Environmental Protection Agency.

205
31 . X-Ray Analysis of Limestone Scrubber Slurry

Project Leader: A. Perloff, Inorganic Materials Division

Qbj ective

I£ good quantitative analyses of the material is desired the

x-ray technique is not the answer. Without adding known

amounts of an internal standard an estimate of each of the

major components can be crudely obtained if that component

represents less than approximately 50% of the mixture. Such

an estimate would have a large associated error, i.e., an

estimate of 301 should be taken as meaning the amount of that

component probably lies between 20%-40% of the mixture. The

use of an internal standard would probably reduce this error

range by a factor of 2. Recourse to orthodox wet chemical

procedures would be necessary if greater accuracy is required.

Approach

It was hoped that peak intensities or relative peak intensities

of the major components of the mixture might provide an

adequate measure of the composition provided constant conditions

of the diffractometer , sample holder and sample packing could

be maintained. This would eliminate the necessity for sample

weighings and the possibility of errors from inadequate or uneven mixing which could arise from the use of an internal

standard.

If this procedure was not satisfactory the use of an internal

standard could be estimated from mixtures containing a constant

amount of one component.

Progress

The diffraction pattern of limestone scrubber solids was

analyzed. It was established that all of the distinct peaks

could be accounted for on the assumption of a mixture of

three components: CaCO, (calcite form), CaSO^' ^H20, and

CaSO .• 2H2O. Pure samples of these compounds were purchased

or made for x-ray examination and as stock material for

making up mixtures of known composition. The mixture

compositions are listed in Table 31.1 and the observed net

peak heights (total peak height minus background) are given

in Table 31.2. Intensity measurements were made on samples

which had been mixed and ground for 5-10 minutes in a mullite

mortar and pestle, loaded loosely into the holder (Figure 31.1)

and compacted by tapping the holder until the top surface

appears smooth and uniform.

206
TABLE 31.1

SAMPLE COMPOSITIONS

CaSO3-%H20 CaCO^ CaSO •2H

Mixture mg %^ mg %_ mg %^ 1 198..25 50.,40 164..64 41..85 30..49 7..75

2 100.,64 25.,80 202..96 52..03 86..45 22..16

3 182..13 43..84 87..30 21..01 146..00 35..14

4 148..52 33..62 148..03 33..51 145,.21 32..87

5 144..44 36.,47 164..50 41..54 87,.08 21..99

6 187..18 46.,39 142..07 35..21 74,.20 18.,39

7 247..92 56.,86 144..59 33..16 43,.47 9.,97

8 96..87 20.,08 159..71 33..11 225..72 46.,80

9 44..35 10.,15 144..87 33..15 247,.78 56..70

10 314..98 69.,98 90.,05 20.,01 45..05 10.,01

11 270.,06 60.,01 90.,06 20.,01 89..89 19.,98

12 157..59 34..99 90.,31 20.,05 202..52 44.,96

13 89.,96 19.,96 90.,53 20.,08 270..26 59.,96

14 44..93 9.,99 89.,87 19.,98 315..01 70.,03

15 90..11 20.,02 188..94 41..99 170..95 37..99

16 44..98 10.,00 188..99 42..00 216..01 48..00

17 360.,03 79.,99 45.,03 10.,00 45..04 10,,01

18 292..50 64.,99 45.,04 10.,01 112..50 25.,00

19 225.,00 49.,99 45..05 10.,01 180..04 40.,00

20 157..52 35.,01 44..97 9.,99 247,.48 55..00

21 90,.05 20.,01 45..02 10.,00 315..04 69.,99

22 44,.98 10..00 45..01 10.,00 359..99 80..00

207
TABLE 31.2

Observed Net Peak Heights

Peak #

Sample # 1 2 3_ 4 5_ 6

2_

1 0.90 1.62 0.96 0.78 2.97 8.45

1* 1.10 1.77 0.82 0.61 2.55 8.05

2 1.96 0.77 0.39 1.45 1.44 0.8 10.8

3 3.30 1.25 0.75 2.41 2.55 1.85 4.63

3a 3.28 1.31 0.66 2.33 2.62 1.70 4.45

4 2.60 1.12 0.74 1.85 1.80 0.7 7.00

4a 2.46 1.09 0.80 2.07 1.88 1.0 7.21

4* 1.55 1.40 0.50 1.48 1.60 0.70 6.33

4a* 1.67 1.26 0.46 1.52 1.70 0.75 6.26

5 1.83 1.36 0.85 1.32 2.10 0.73 8.02

6 1.50 1.73 0.68 1.18 3.17 0.50 7.15

6a 1.52 1.58 0.69 1.13 3.07 0.60 7.31

7 1.13 1.70 0.97 0.86 2.81 7.00

8 4.70 0.80 0.42 3.32 1.02 1.90 7.40

9 5.84 0.36 0.31 4.14 0.88 2.65 7.18

10 0.6 2.28 1.50 0.53 3.37 4.00

11 1.40 1.83 0.85 1.02 3.41 0.75 3.86

12 5.30 1.50 0.74 3.34 1.90 2.17 5.17

13 5.57 0.62 0.32 4.49 1.20 3.07 4.43

14 8.90 0.55 0.25 5.54 0.63 4.13 4.85

15 2.50 0.80 0.30 1.70 1.00 0.8 9.05

15a 2.15 0.80 0.27 1.72 1.08 0.9 9.18

15* 2.55 0.62 0.33 1.72 1.15 1.0 8.35

16 3.83 0.4 0.2 2.70 0.68 1.75 9.18

17 0.43 2.42 0.95 0.35 3.49 1.70

18 1.92 2.02 1.22 1.25 3.42 1.10 2.30

19 2.81 1.72 0.95 2.27 2.77 1.60 2.48

20 4.53 1.00 0.62 4.02 2.10 2.50 2.25

20* 2.37 1.87 0.55 2.45 1.85 1.67 2.32

21 5.00 0.82 0.40 4.94 1.24 3.03 2.43

22 6.02 0.30 0.20 5.50 0.73 3.57 2.31

208
TABLE 31.2 (continued)

a = Pattern rerun with same sample and same packing.

* = Pattern run after regrinding and repacking

Peak 1 is CaSO •2H O line at d = 7.56

Peak 2 is CaSO '^H O line at d = 5.55

Peak 3 is CaSO '^^H line at d = 5.33

Peak 4 is CaS0.'2H-0 line at d = 4.27

4 2

Peak 5 is CaSO '^^H line at d = 3.14

Peak 6 is CaSO *2H line at d = 3.06

Peak 7 is CaCO (calcite) line at d = 3.04

209
TABLE 31.3

Data for Constant Carbonate Composition Curves

10% calcite

sulfite ( Pk 4

j

sulfate ( Pk 4]

Sample # % sulfite carbonate \Pk 7/ % sulfate carbonate \Pk 7/

22 10 0.316 80 2.381

21 20 0.510 70 2.033

20 35 0.934 55 1.786, 1.056

19 50 1.117 40 0.915

18 65 1.486 25 0.543

17 80 2.053 10 0.206

20% calcite

14 10 0.130 70 1.143

13 20 0.271 60 1.013

12 35 0.368 45 0.646

3 44 0.571 35 0.522

11 60 0.883 20 0.264

10 70 0.842 10 0.132

33-35% calcite

9 10 0.123 57 0.577

8 20 0.138 47 0.449

4 33 0.260 33 0.264-0.287,

0.234-0.243

6 46 0.431 18 0.155-0.165

7 57 0.401 10 0.123

42% calcite

16 10 .074 48 0.294

15 20 0.110-0.118,

0.138

38 0.188, 0.206

5 36.5 0.262 22 0.165

1 50 0.351 8 0.092-0.076

210
Ic

, CM CO

k

3"

9."

32 \^

-<M

H

Figure 31.1

Seunple holder is cut from 1/16" hi plate. The dashed lines represent

a glass slide cemented to the bottom. When loading a sample, a

second glass slide is clamped on the top surface. The sample

is introduced from the open end. While holding the open end upright

the holder is tapped with a metal rod to compact the seunple. The

second slide is removed before placing the holder on the

diffractometer.

211
The samples cannot be pressed to give a good surface because

this results in highly oriented diffraction patterns. The

relative intensity of the CaSO_ • h H2O peaks at d=5.55 and

d=5.33 was used as a guide to decide whether the samples were

free of marked orientation effects. In an oriented sample

the 5.33A peak becomes the strongest lin§ and may be an

order of magnitude greater than the 5.55A peak. With a calcium

sulfite sample free from preferred orientation the peak at

d=3.14A is the strongest and the 5.55A peak is roughly twice

the intensity of the 5.33A peak.

All patterns were made with the same holder, diffraction unit

and experimental conditions. This is absolutely necessary as

an x-ray diffraction calibration curve is only valid when all

experimental conditions and equipment are held constant. The

patterns were made on a Philips dif f ractometer with Ni-filtered

Cu radiation. A scintillation detector, pulse height analyzer

and strip charter recorder were used. The slit system

consisted of 1° divergent and receiving slits coupled with

0.006" limiting slit. Peak heights and backgrounds were

measured on the strip chart record. A scanning sj)eed of 1/2

degrees 28 per minute and a time constant of 1/2 seconds were

used.

For each pattern the relative peak heigh-^s of seven peaks

were measured; one ^alcite pe§k (d=3.04A), three sulfite

peaks (d=5.55Aj 5.33A an^ 3.14A) and three sulfate peaks

(d=7.564, 4.27A and 3.06A). The strongest<,peaks for calcite

(d=3.04A) and the sulfite compound (d=3.14A) were used as a measure of their proportions. It was felt that the second

strongest line (d=4.27A) for the sulfate salt would be a ^ better criterion than the low angle strongest peak (d=7.56A).

At the lower angle the area intercepting the x-ray beam is

larger than the sample area and it becomes harder to maintain

a reproducible amount of sample in the beam.

Results and Conclusions

The graphs of Figures 31.2 and 31.3 indicate that, within

crude limits of accuracy, the peak heights of the major peak

of each component can give an estimate of the percentage of

that component as long as it is less than approximately

50% of the total mixture. The confidence that could be

placed in such an estimate varies with each compound. The

carbonate is best in this respect. This is due to the much

steeper slope of the curve and to the fact that it is not

very prone to preferred orientation because the starting

material was already in a finely powdered form.

212
CALCITE

20 60

SULFITE

30 40 50 70

X COMPOSITION

Figure 31.2 Calcite and sulfite peaks vs. composition

213

io
® o

eo

o

®

®

®

iH0l3H >IV3d

Figure 31.3 Sulfate peak heights vs. composition.

o

214
The sulfite curve appears to be next in terms of accuracy and

reproducibility. It is much less accurate than the carbonate

curve because of the lower slope. The influence of preferred

orientation is probably less in the sulfite pattern compared

to the sulfate pattern because the sulfite lines were used to

decide if orientation effects were present. It is highly

possible, especially in mixtures high in sulfate and low in

sulfite, that a pattern could be obtained in which the sulfite

was essentially unoriented and the sulfate was still

preferentially oriented.

The sulfate curve is the worst in terms of reproducibility and

accuracy. This is probably due to orientation effects not

being controlled as well as for the sulfite compound.

The use of an internal standard would improve matters

slightly as illustrated by the constant carbonate composition

curves of Figures 31.4 and 31.5. The results could be

improved further by the choice of a more appropriate internal

standard which could give a steeper, more sensitive curve.

Averaging several measurements for each composition would

improve the accuracy.

The use of an internal standard would require two weighings

and thorough mixing for each sample you wish to analyze.

Weighing, mixing, grinding and a single scan would take from

30-60 minutes per sample. Additional grinding, mixing and

scans, which would be necessary if more confidence is required

in the results, could take about 30 minutes each. The end

result would be semiquantitative at best. I do not know

what present wet chemical techniques are available for this

specific problem, but I would be surprised if there were not

some relatively rapid titrimetric techniques which could give

better results in a shorter time.

Whether the x-ray technique can be used depends on your ultimate

objective. If monitoring the quantity of calcite is the

primary objective then it can be used effectively with an

appropriate internal standard with the time requirements

reduced by scanning only the area of interest. If it is

important to know the relative amounts of sulfite and sulfate

salts with good accuracy, I would not recommend the technique.

Materials Preparation

CaCO- - B and A reagent grade powder. X-ray pattern

shows only the calcite phase.

215
J3M

5

H

n

n

>nt

0)

I

•

' % p 0) « P 4J

0) Id (0 4i c c ^ ^ iH M u

3 10 <0 CO u u

<H «> 4P o o

M

V

«I

(0O

in

I <*»

P

10C

<0o

<N

•P • <i) 5J <^

I,

!

/Z >lV3d\

\S )IV3d/

3iVN08aV3

3iiJins

to

u3

•H

216
CO

0) +J

n) <^

r-\3

u

dpw

>

(0 +J

4:3en •H

0) x:^

(0

0)a

0) 4J

nJ

c: ^

M

(0 ».

+J

•1. ^ n) • •p 0) <U C 0) +J +J 4J

(U to (0 ^ n) p fi c ^ C

<4-l ^ ^

(0 ^ iH M ^ u 3 <fl (0 dP n] (0 ID <M *> «> 1 dP n CN iH tN n ^

•H ^^ky 4J • (5) ill ^rt

f-l

•H

(in

3iVN09aV3

3ivdins

217
CaSO^ • 2H2O - Precipitated by combining solutions

of reagent grade CaCOH)- and Na2S0. . A well

crystallized single-phase product is obtained

by digesting overnight.

CaSO, • h^2^ ' ^ well crystallized product is obtained

by slow diffusion of solutions of CaCl- '21120

and Na2S0.. A substantial yield of the

product requires about three weeks to form.

Rapid precipitation produces a poorly

crystallized product which is low in calcium.

This suggests that there may be an

amorphous form of a higher hydrate which is

metastable.

218
32. Particle Size by Light Scattering

Project Leader: Ilan Chabay

Objective

The primary goal of this project has been to design, fabricate,

and assemble the components of a laser scattering system for

the measurement of particle size distributions.

Approach

Light scattered by a particle falling in a gravitational field

exhibits a Doppler shift, the magnitude of which is determined

by the velocity of the particle which, in turn, depends upon

its size, density and the medium through which it falls. This

Doppler shift is to be measured to assess the particle size.

Progress

The equipment includes an argon ion laser, an etalon, an air

supported optical table (which provides vibrational isolation)

,

a set of optical components with adjustable mounts, a photoimultiplier tube, PMT housing and PMT power supply, a signal

icorrelator and a digital voltmeter.

219
In order to introduce the particles into the scattering region

under well-defined conditions, a wind tunnel was designed and

constructed. It is designed to create a uniform velocity, slow

air flow in the scattering region through which the particles

fall. The velocity due to the settling motion of the particles

can then be unequivocally separated from the mass flow velocity

of the surrounding air.

An optical bench, on which the detection apparatus is mounted,

was built. It allows the angle of scattering to be chosen and

changed readily and with high precision.

Preliminary tests done with water droplets from a simple atomizer served to indicate that the optics and correlator were

set up and operating correctly.

The interfacing and software for direct computer processing of

the data gathered by the correlator is being designed. This

will involve talcing data from the correlator as an autocorrelation function, performing a fast Fourier transform, determining the sizes of particles present from Stokes' Law, then

using a calculated Mie scattering curve for the scattering

angle to determine the distribution of particle sizes.

A summer student is currently just beginning to set up and

test a vibration orifice aerosol generator based upon the

Berglund-Liu design. The generator is claimed to be capable

of producing monodispersed particles of liquid or solid

materials if operated under carefully controlled conditions.

Scientists at the Environmental Protection- Agency and other

laboratories have experienced difficulties in obtaining the

desired size and reproducibility claimed by the designers.

The laser Doppler spectrometer will be used to investigate

the operating parameters of the vibrating orifice and to

assign accuracy limits to its performance. Once calibrated,

the particle generator will be used in conjunction with the

light scattering instrument to carry out particle reaction

studies

.

220
An evaluation of the potential of coherent anti-Stokes Raman

spectroscopy (CARS) for the use as a general analytical tool,

for particulate analysis, and for gas analysis was undertaken

at Molectron Corporation in Sunnyvale, California. Since that

trip, one paper has been written. [1].

In the last year, the particle doppler shift spectrometer

(PDSS) has been assembled and successfully tested. Preliminary studies have been made with the Berglund-Liu vibrating

orifice aerosol generator (VOAG) as a particle source.

The PDSS is capable of resolving . 1 ym size increments with

similar accuracy in the 10 ym radius size range. In the form

described previously, in the FY 1975 report, the PDSS was

used to check the performance of a Royco model 225/508 and a Particle Measurement Systems ASSP. Both of the latter instruments were within their specifications, but neither showed the

resolution or detail in the size distribution, nor had any

means of internal accuracy check which the PDSS has.

The limitations on the PDSS at present are the following:

1) poor reliability of the EMR computer system for data

storage and processing.

2) considerably less resolution available than is theoretically possible (this is due to the 100 channel capacity

of the correlator and the slow transfer rate of data to

the computer)

.

3) Convection currents in the scattering volume.

A new particle handling system to introduce particles into

the scattering volume has been designed (in large part by_

David Bright). This system with a long vertical column with

postions to control flow at top and bottom is being tested

now. This system is meant to replace the wind tunnel

arrangement

.

221
We are also considering a fast Fourier transform instrument

with 400 channels and frequency range translation as a replacement for the 100 point correlation. The FFT instrument would allow greater resolution and accuracy, faster

data collection, and less dependence upon the state of health

of the EMR computer.

A paper on the preliminary design and testing of the PDSS is

being prepared for submission to Environmental Science and

Technology. Included in the paper will be comments on the

vibrating orifice generator. The data, even in preliminary

form, show that the aerosol produced has considerably more

"structure" in its size distribution than has been detected

or assumed previously.

The three week trip to Molectron Corporation in spring of

1975 has resulted in the paper cited in the previous report,

a second paper to be published shortly in Proc. Natl'l Acad.

Sci. (US), and the establishment of a facility at NBS for

study of non-linear optical spectroscopy. One aspect which

will be considered is any application of techniques (other

than CARS itself) such as inverse Raman, to particulate

samples, and to gaseous samples.

References

[1]. Klauminzer, Gary, Hudson, Bruce and Chabay, Ilan,

Coherent Anti-Stokes Raman Spectroscopy (CARS) : Improved

Experimental Design and Observation of New Higher Order

Processes. Submitted to Applied Physios Letters.

222
33 . Development of Sulfur Particle Analyzer

Project Leader: R. L. McKenzie, Analytical Chemistry

Division

Other Personnel: D. B. Kittelson, M. Vermeersch, K. Kwok,

D. Y. H. Pui, B. Y. H. Liu, K. T.

Whitby, University of Minnesota, and

Y. Kousaka, University of Osaka

Obj ective

The design goal of this project was to measure, in real time

under field conditions, particulate sulfur levels ranging

from ambient levels (about 1 microgram per cubic meter

sulfate) up to source emission levels which may range up to

as high as 50 micrograms per cubic meter.

Approach

The present configuration of the system which has been

developed is shown in the schematic diagram in Figure 33.1,

which indicates the principle that is being used. Aerosol

samples enter the system through an electrostatic precipitator

chopper which is turned on and off by a high voltage square

wave. When the precipitator is on, it charges and precipitates

the particles, removing them from the sample stream. When

the precipitator is off, the particles flow through the

precipitator into the flame photometric detector. This

results in modulation of the aerosol concentration entering

the flame photometric detector, which in turn results in a modulated output from the flame photometric detector. The

modulated portion of the signal is proportional to the

aerosol concentration in the sample. The flame photometric

detector output is measured with the lock-in amplifier, which

selectively amplifies the modulated or a.c. component of

the signal, which has the frequency of the square wave highvoltage source on the chopper. Because the chopper does not

modulate any gas phase materials, the system should not

respond to gas phase sulfur species, for example, SO^.

In the last Progress Report, work was reported that we did

with a Meloy Model 180 flame photometric detector. A high

sensitivity instrument, the Model SA-285, has been obtained

and preliminary calibrations with sulfuric acid, using this

detector have been made. Just two weeks after that

instrument was received it was taken to Los Angeles for a two-week field study.

223
Progress

Figure 33.2 shows the calibration curve obtained for sulfuric

acid using the Meloy 285 as a detector. Three calibration

curves have been obtained, one with ppb SO^ as a background

gas phase constituent, and two curves with, respectively,

30 ppb and 60 ppb SO-. These calibration curves, shown in

Figure33. 2indicate that there is an SO^ interference: the

calibration curve is a function of the level of SO^ in the

sample. Some calculations have just been completed to

characterize response of the whole system, which indicates

that this type of behavior would occur if there is an error

in setting the off-set voltage for the system, or in setting

the span. An error analysis is now being done to see_how areat

an error is caused by small misadjustments . In any case,

the SO^ interference is not a major problem, because the

SO2 can be removed from the sample by simply putting a scrubber in the sample line before the inlet.

The instrument as described above gives only a measure of the

total sulfur in particles, and gives no information about the

chemical form of the sulfur.

The second objective of this study was to be able to perform

some speciation of the sulfur in the particles.

The first technique to be described is a thermal speciation

system which can be coupled directly to the inlet of the

particulate sulfur monitor just described. When the

volatilization temperature of an aerosol that contains

volatile compounds is reached for a particular compound, that

particle will evaporate. Much of the vapor will be lost to

the walls by diffusion. If the sample is subsequently cooled,

the remaining vapors will recondense and reform particles,

but these particles will be lost to surfaces in the system

as they reform due to the high diffusional mobility of these

small particles.

Figure 33.3 shows thermograms obtained for sulfuric acid,

ammonium sulfate, and ammonium bisulfate. These thermograms

were obtained by passing the aerosol through a heater and a condensor section, and then to a detector. The loss of

particles is as one would anticipate for the volatilization

properties of the compounds in these particles. Sulfuric

acid aerosol losses begin to occur at about 30°C, and are

essentially complete by 100°C. The 50% temperature transition

for this particular material is 71°C. The ammonium salts of

sulfuric acid do not begin to be lost from the sample until

about 100°C, and the loss is essentially complete at 200°C.

The midpoint of this transition is about 142°C. For these

224
two particular cases, it is possible to distinguish clearly

between sulfuric acid and its ammonium salts by this

technique

.

Two other temperatures that help to characterize this system

are the ambient temperature, where all of the material is still

present, and 200°C, where all of the material has essentially

been lost from the sample. Any material left in the sample

at 200°C would be what we will term refractory sulfur compounds

One disadvantage in making thermograms as Just described in the

field is that it requires long equilibration times to reach

the various temperatures, and there are also many transient

values introduced between equilibrium values. One has been

able to take advantage of the four characterizing temperatures

indicated above to eliminate these transients and to operate

under continuous equilibrium temperature conditions.

Figure 33.4 is a schematic diagram of the thermal speciation

system. The sample is drawn in simultaneously through four

identical pathways which are respectively at ambient

temperature, 71°C, 142°C, and 190°C. The second half of

this system just provides a means of selecting the sample

from a particular heater condenser pathway while simultaneously

maintaining constant equal flows through all four pathways.

Figure 33.5 is a strip chart recorder made during the Los

Angeles Freeway Study several weeks ago. The signal changes

as one switches from one thermal pathway to another. The

response time of the whole system is indicated on this curve

to be about 1 minute. When the signals are converted from

millivolt readings to sulfur concentrations, one finds the

following values:

Temperature

ambient

71°C

142°C

190°C

This data indicates that the sensitivity of our system is

about .1 yg of sulfur/m . The above sample was taken on the upwind side of the San

Diego Freeway when the wind was coming in off the ocean. The

data indicates that only 10% of this sample was lost in the

region where sulfuric acid would be lost, 20% of the sample

was lost in the region where ammonium sulfate and bisulfate

225

7 ygm/S/m 0. of Total Signal

.75 - .80 (100)

.70 - .75 10

.55 20

.50 70
materials are lost, and 70% of the sample is in the refractory

sulfur compound region. Part of the signal in the 190°C

thermal pathway may be due to potassium or sodium metals,

which have been shown earlier to cause a positive interference.

(These salts would be expected to be in the refractory

fraction of the sample.) However, the levels that would be

required of these two metal ions, based on earlier studies,

indicate that they would contribute only a minor part of the

signal that is being seen in this sample region.

The second speciation technique that is being developed is

termed an aerosol mobility chromatograph. The system, which

is shown schematically in Figure 33.6, detects the change

in the size of the aerosol upon exposure to different

relative humidity conditions by use of a high resolution

differential mobility analyzer. The sample is introduced

and passed through a diffusion dryer and then through a Krypton 85 neutralizer which dries the sample and gives it

an equilibrium Boltzmann charge. The sample goes through a differential mobility analyzer which selects a monodisperse

fraction of that sample to be used for the rest of the

evaluation. The monodisperse sample is equilibrated to new

humidity conditions in the humidifier section, and the sample

is subsequently analyzed with the second differential

mobility analyzer. If the material contains hydroscopic

species, the water content, and thus the particle size of

the aerosol, will change under the new humidity conditions.

This change may be detected in the second differential mobility

analyzer. Calculations have been made based on the equilibrium

vapor pressure data for sulfuric acid, and using Kelvin's

equation to predict theoretically the change in water content

of sulfuric acid droplets under varying humidity conditions.

These calculations are shown in Figure 33.7 as the solid lines.

One sees that as the relative humidity goes up, the particle

diameter increases. The data points are for sulfuric acid

aerosols measured in the aerosol mobility chromatograph. The

agreement between theory and the experiment is very, very

good.

Figure 33.8 provides a demonstration of an actual separation

of two different sulfur species. Potassium sulfate and

sulfuric acid aerosols were generated and mixed, and then

fed into the system. The solid curve shows that with no

humidif ication between the first and second aerosol mobility

analyzers, both materials come out together in the same peak.

However, when the relative humidity is raised to 531,

separation occurs. Under these conditions, sulfuric acid

aerosol will grow as it picks up water; potassium sulfate,

however, will not grow, as 531 relative humidity is still

below the deliquescent point for potassium sulfate. The

different responses of the aerosols to the change in relative

226
humidity results in different aerosol equilibrium sizes, and

consequently, in different electrical mobilities. This

provides the basis for the separation that is shown in Figure

33.8.

Conclusion

In summary, one now has a prototype system that meets the

design objectives for the project, and begins to think in

terms of possible production configurations for the system.

Future work includes the following items:

o

o

Evaluation of the SO^ interference.

Complete calibration curves for sulfuric acid

and for sulfate salts.

Evaluation of the system with respect to metal

ion interferences

.

Evaluation of burner block configuration.

The response time of the slowest component in

this system will determine the maximum chopping

rate. The maximum chopping rate in turn

determines the overall response time of the

instrument. Calculations of the time scale of

the events that occur in the flame indicate that

these processes should all occur within tenths

of a second or less. However, data indicates

for the burner block in the Meloy, that events

occur that take as long as several seconds.

This is due to absorption-desorption from the

walls and other surfaces in the burner block.

A burner block to minimize this, and decrease

the response time of the system is being designed.

Characterization of the aerosol mobility

chromatograph with respect to ammonium salts

of sulfuric acid, and also with respect to other

compounds such as nitrates which may possibly

act as interferences in this particular application,

227
q:

-J <

S23DO

UJ -J<

>-u z

e> z CO

UJ3O

UJ

cru.

r

UJ UJ > o < < ^ H UJ

UJ

O CE

tr > 3 < xo gScn

<n

X

«jo UJ

(O -J o 0.

cr Zt

UJ < < <n opHom

rH

<U

•(->

iHU

•HPpoH

JhO

+J

+J •H

Dh •HO

(D

JHo

•HPpoPoQ

rHm

(/) iH

top

(30 •H

228
0.1

1

Q.

3

OjOCH

HgSO,

o H2SO4 , 30ppb SO2

A H2SO4 , 60 ppb SO2

J \ I I I I I

1.0 10 20

/xg /mFigure 33.2 Calibration curve obtained for Sulfuric Acid

using the Meloy 285 as a detector,

229 .
lN3ddnO nvlOl dO lN3Dd3d

230

H

tA

(D

+-> ^^

1—1

O

•H>

o

S

ojbO

O

E-H

tototo

<u

f-l p

bO •H
o

COo

uj T

rm

crUJ

X

UJ

I-

>-

< o

Q. 0(0

Ul

X

o

CO

(O

a:Ul

1 J1 <

Ul

X

UJ

q:3 in

1- cr < o

CE if) l^ p"

1 Q. UJ S en

Oh

ir V L

0^ O^

>- -r\

O 32

I- O 3

5^

</) I-Z

UJ3

crV)

z

C/3

to

to

<u

•H

231
AUU

in>^^oou

en0) iH

(U

txO <Omo

Tiuou

<uu

+-> O

p4

•H

+J• to

to

<0u3

bO

•H

232
CM

a:

hi

UJ

Li. Q —

X

qr

Q-c/)

^

<

QJ l_ UJ

q5<

::\\\\\v\\\-^^ss

^

—

QCUJH

UJ is

-JU.

c

•H

P!O

p

o

•H

+->

•HO

V)

Ph^

O

t-J cdS

o

u

o

4-> •H

iH•HX)

O

O

o

<D m

o

o

•H

->S

x:o

to

to

(U^13

•H

CI* 233
0.02 0.05 0.1 0.2

PARTICLE DIAMETER , fim

Figure 33.7 Equilibrium Vapor Pressure Data for Sulfuric

Acid.

234
Vd • ±N3y«nD ^313W0«i0ai3

iHo

mo

u

I

-J

o

m

tH3

COe

•H

V)

tfl nj M

O

m

o

PIo

•H

4-> OJ

OJft

(D CO

OO

to

tno

t)0 •H

235
34. Flow Measurements for Water Pollution Abatement

Project Leader:

Other Personnel:

G. Kulin, Mechanics Division

R. W. Davis, K. E. Lofquist (part-time),

A. L. Lembeck, T. Robusto, Jr.

Objective

The objectives of the project are (1) to improve the measurement of water velocities as practiced in the field, with

emphasis on low velocities (less than 1 ft/s) and on the use

of current meters for velocity sampling in open channels; and

(2) to improve field measurements of the volumetric flowrate

of water and wastewater. There is a strong connection between

the two objectives in that the velocity-area traverse is one

of the most basic and frequently used methods for determining

flowrate and for field calibrating flowrate measuring instruments. Attainment of these objectives is motivated by needs

for: better measurement of the very low velocities which

play major roles in lake and estuary dynamics and which have

become increasingly important in view of the intense interest

in water quality control and marine disposal of thermal discharges and other wastes; the establishment of guidelines for

accurate and consistent wastewater-discharge compliance and

enforcement monitoring, and for other flow measurements

needed to satisfy regulatory requirements; and promulgation

of such guidelines among users by publications, workshops,

conferences, short courses, etc.

236

I
Approach

The approach emphasizes analytical , computational and experimental flow measurement investigations in-house, complemented

by the maintenance of extensive contacts with users who actually make flow measurements in the field. The purpose of the

field contacts is to observe flow measurement problems and

error sources as they occur in the field in order to continuously assess measurement needs versus existing capability

and to provide meaningful input for the laboratory program.

The field contact work also fosters the transfer of measurement capability and information from NBS to field users.

The laboratory program includes: experimental studies of

water velocity and flowrate measuring devices and methods

to determine performance limits and error sources; development of analytical and computational models to support,

complement and extend this experimental work; and application

of these results to provide guidelines and recommended practices for flow measurements. The future high performance

water tunnel and the almost completed open channel will be

the major laboratory facilities for the velocity and open

channel flow measurement efforts respectively.

Progress

Flow measurement guidebook . "A Guide to Methods and Standards

for the Measurement of Water Flow," G. Kulin and P. R. Compton,

was published in May, 1975 as NBS Special Publication 421 and

is available for purchase from the G.P.O. ($1.65, Cat. No.

C13. 10:421). It has also been distributed directly to appropriate EPA personnel and to selected users whose measurement

problems were discussed as part of the field contacts effort

of the project. The total distribution to date has been

approximately 1,000 copies, with about half of that number

accounted for by G.P.O. sales or direct requests to NBS.

The guidebook was prepared for the following purposes:

1. To collect in one document and briefly describe the best

sources of information on good flow measurement practices.

Although several good flow measurement manuals have been

available, in our opinion no single publication existed

which directed field users to all of the information

needed for good measurements. Accessibility of these

sources was emphasized.

237
2. To caution users concerning error sources and pitfalls

in the use of instruments and procedures. These errors

were quantified wherever possible using our own experience

and information gathered from available literature. Our

field contacts had indicated that one of the shortcomings

in other flow measurement publications (in the eyes of

the users) was their failure to indicate the errors introduced by departures from "standard" practice.

Additions and comments from readers will be incorporated in

a projected future revision of this guidebook.

Ad hoc committee on wastewater flow measurement . The Environmental Protection Agency has an immediate need to establish

flow measurement guidelines for the large number of industries

and municipalities which are being issued effluent permits.

Because these permits are issued in terms of a total daily

pollutant loading, all dischargers must monitor the flowrate

as well as the pollutant concentrations of their effluents.

Legally and technically acceptable criteria for selfmonitoring flow measurements (by industries) and for calibration checks (by regulatory agencies) must be established.

EPA requested the Mechanics Division to organize an ad hoc

group of Federal flow measurement experts to address this

problem, and a meeting of this interagency panel was held at

NBS on June 24, 1974. The foregoing flow measurement guidebook responded to many of the issues raised during that

meeting, and future activities by this panel depend in part

on response and follow-up to that initial guidebook effort.

Open channel flow measurement - flumes . The Parshall flume is

probably the most widely used flow measuring flume. It is an

empirical device which resists purely theoretical analysis.

Experiments were made in the NBS hydraulic laboratory on a three-inch Parshall flume to determine flowrate errors caused

by bottom slopes (the flume should be level) and by incorrect

sidewall convergence angles. These two error sources stem

from common installation and fabrication errors, and no guidelines exist for adjusting the publishe4 flow tables for these

effects. The experiments were supported and guided by prior

error estimates which had been made using semi -analytical

approaches based on reasonable assumptions. This analytical

work also provided a rational basis for extrapolating the

experimental results to larger flumes. The results indicated,

for example, that for flume bottom slopes of one-half percent

and more, errors of more than 10 percent can be introduced by

using uncorrected published data for the lowest flowrates . [1]

238
The Palmer -Bowlus flume is another popular type of wastewater

flow meter and a discussion by G.Kulin [2] calls users'

attention to possible errors of up to 8 percent at the low

and high extremes of flow if certain precautions are not

observed.

Open channel flow measurement- -computer models . The work on

the applicability of computer simulation models to solutions

of flows over certain types of flumes (two-dimensional PalmerBowlus) or broad-crested weirs resulted in a paper. [3]. In this

study, the operational range of the . two-dimensional flume was

extended to head- length ratios for which the one-dimensional

theory (the only previously available analytical approach) lost its

validity. Effects of changes in flume bottom geometry,

channel slope and upstream velocity profile were investigated

numerically. Experimental verifications were obtained in a laboratory flume of six-inch width and crest length. The

results also will provide guidance for the effective conduct

of the flume performance experiments in the new open channel

which is described in the following section.

Open channel . Construction of an open channel facility will

be completed in August 1976. This open channel is necessary

for (1) evaluations of upstream effects on flowrate measuring

flumes, veirs and other devices, (2) development of guidelines

for traversing small conduits and sewers with current meters

and ultrasonic flowmeters, (3) determination of the hydraulics

of flow in partly full pipes, i.e., sewers, this information

being needed for improvements in certain methods of sewage

flow measurement, and (4) investigations of the feasibility

of using laser-based devices for flowrate determinations in

sewers and other open channels.

The open channel is an open circuit system employing the existing reservoir and pumping system of the laboratory. It also

uses the constant-head inlet tank which is part of an existing

gravity-flow water tunnel. The basic working section is 40

Ifeet long and is a 3 x 1-1/2 ft. rectangle in section. This

section can be replaced in the future with a circular section

for sewer-related flow investigations. The channel slope is

adjustable and the flow capacity is 10 cubic ft. per second.

The basic flowrate measurement is a rectangular weir in the

outlet tank, which will be calibrated in place.

239
Flow in rectangular open channels . There is surprisingly

little published information on the detailed characteristics,

specifically velocity distributions, of open channel flow in

artificial conduits of various shapes and roughness. Some

of these gaps will be filled by the work to be done in the

NBS open channel. However, enough information has been

gleaned from the literature to permit at least the determination of the useful limits of the one-point (six-tenths depth)

method of velocity traversing in rectangular conduits of

appreciable depth-width ratio. Because this is considered

worthwhile information for the user community, a technical

note on the subject is being prepared without awaiting future

NBS work on guidelines for traversing small conduits.

Current meters . The experimental investigation of the low

velocity performance of Price and Pygmy current meters in a small towing tank has been completed. The velocity range was

generally from 0.1 ft/s to 0.5 ft/s , although in some cases

the Price meter was used at velocities as low as 0.06 feet

per second. This work includes: investigation of the repeatibility of meter performance at low velocities; experiments on

the effect of internal friction (as grossly evidenced by spin

tests) on the threshold velocity and low velocity behavior of

Price meters; sidewall and bottom proximity effects on buckettype current meters; effect of a small angle of tilt on Price

meters at low velocities; and estimates of the errors involved

in extrapolating routine calibration curves (with velocities

to 0.25 ft/s) to 0.1 feet per second.

Additionally, an analytical model of bucket -wheel, vertical

axis current meters was developed which permits evaluation of

the errors introduced by lateral velocity gradients in the

flow. Errors caused by the presence of the observer's body

in the stream during rod-supported "wading" measurements were

evaluated theoretically. The results suggest that the presently recommended wading position can introduce significant

systematic error, but field data on this subject are meager.

Also evaluated theoretically were the effects on meter rotation of the proximity of the torpedo-shaped weights used

during cable suspension of current meters. These results

were compared with prior data obtained in the large towing

basin on the old NBS grounds.

All of the foregoing results are now being prepared for

publication.

240
Water tunnel . Completion o£ the high performance, 24-inch

test section water tunnel has been hampered by continual

delays owing mainly to the contractor's difficulties with

certain subcontracts. Contract monitoring and other activities in support of the tunnel contract continued throughout

the reporting period. The earliest commitments of the

completed water tunnel to the water pollution flow measurements program will be for establishment of high quality, low

velocity reference flows in the test section and for the

evaluation of turbulence effects on vertical-axis current

meters

.

Flow measurem.ent conferences . A three-day conference on Flow

Measurements as related to National Needs was arranged and

hosted by NBS on February 26-28, 1974, to provide a forum at

which regulatory authorities, instrument users and manufacturers could address problems of flow measurements in the

field. One day of this conference was devoted to water and

wastewater flow measurements, and the program arranged for

that day was a direct follow-up of the field contacts activity

which had preceded it.

A follow-up symposium on Errors in Open Channel and Closed

Conduit Flow Measurement: Their Sources, Assessment and

Resolution is now being planned for February 23-24, 1977 at

NBS. This meeting proposes to provide a forum for identifying

additional error sources in flow measurement, formulating error

analysis techniques and recommending techniques for resolving

uncertainties . Additionally , it will provide the stimulus for

cooperative industry-government activities for reducing

uncertainites in all phases of open channel and closed

conduit flow measurement. Approximately one half of the

sessions will be devoted to open channel flows of water and

wastewater.

References

[1]. Kulin, G. and Davis, R.W. , Effect on Parshall' Flumes

of Slope and Geometry Changes, in press.

[2]. Ludwig, R.G. and Parkhurst, J.D., Simplified Application

of Palmer-Bowlus Flow Meters , discussion by G .Kulin, Journal

of the Water Pollution Control Federation ^ ^^^ January 1976.

[3]. Davis, R.W. , Numerical Modeling of Two-Dimensional

Vlumes , submitted to the Journal of the Hydraulics Division^

American Society of Civil Engineers

.

241
35. Water Sampling and Sample Handling for Trace Element

Analysis

Project Leaders: D. A. Becker, S. H. Harrison, Analytical

Chemistry Division

Objective

The validity of trace

to the validity of the

aims to study and deve

dling procedures for t

The objective of this

(1) development of the

of a water sampler, (3

sampler, and (4) appli

element measurements is directly related

sampling procedures used. This project

lop water sampling and preanalysis hanrace element profile determinations,

work was separated into four phases:

analytical technique, (2) development

) use and evaluation of the water

cations to environmental problems.

Approach

In order to investigate sampling protocols, an analysis technique capable of multielement determinations on a single

sample was needed. Non-destructive neutron activation analysis

of freeze dried water was chosen for this purpose. This

technique was used to evaluate a Teflon water sampler developed in our Division. This evaluation consists of replicate

sampling studies and a comparison of results with those from

a popular commercial water sampler. To demonstrate that the

sampling, treatment and analysis procedure developed is

applicable to environmental problems, a study of two waterways, suspected of abnormal trace element content, was

initiated.

242
During this evaluation, the sampling, storage and handling

techniques used are reevaluated, and changed i£ necessary in

order to provide a convenient, workable and scientifically

valid water sampling protocal.

Progress

Radioactive tracer studies for determining the trace element

retention of 21 elements during the freeze drying process

have been completed. The results show that all but the most

volatile elements (Hg, I, and perhaps Au) are quantitatively

retained in a residue resulting from the freeze drying of

100 g of filtered river water.

After establishing a technique for preconcentration of water,

the development and study of sampling techniques was initiated

A Teflon water sampler, which was designed and constructed at

NBS is under evaluation. To date, most of the evaluation has

consisted of determining the sampling error for different

kinds of water systems. The method chosen was replicate

sampling of a location over a moderately long time interval

about two hours. Sampling error was defined as

SE = \J(SB)^ - (AE)^ - (FDL)^

where SD = the relative standard deviation of the determinations in the replicate samples, AE = the analytical error

and FDL = the freeze dry loss. For suspended particulates

the last term is not applicable.

The kinds of water systems investigated were a fresh water

stream, a mixing zone in a river and a large estuary, at the

mouth of its main tributary. The results for both the

dissolved species (determined as freeze dried filtrate) and

the suspended particulates are complete. As one might

expect the fresh water stream is a well mixed system and the

standard deviation of values for a single element in the

replicate samples was generally determined to be less than

20% and for many elements, less than 101. On the other hand,

the estuarine locations are not as well mixed and the data

show some indication that tidal changes cause dissolution of

trace elements from the sediments into the aqueous phase.

k

243
Adopting a technique used byde Groot[l] and others .suspended particulate data were normalized to the element scandium.

For the replicate sampling studies, normalizing suspended particulate values serves to smooth the data, particularly

in the case of the estuarine samples.

Another part of the evaluation was to determine if the sampler construction materials would contaminate the water samples.

This was assessed by running highly purified water through

the sampler and filtering unit and then analyzing the water

to determine if there was any increase in trace element content over the normal analytical blank. The results of this

experiment appear in Table 35.1. (The polyethylene bag is

the predominate analytical blank.) It can be seen from

Table35.1 that Na is the only element which is abnormally

high in the "Sampling Blank" sample. Although the Co value

of 21 nanograms is about twice as high as the largest value

determined in the polyethylene bags, the range of Co values

in these bags was so great that this value could be accounted

for by inhomogeneity in the polyethylene.

To demonstrate the applicability of the described sampling

and preconcentration scheme to aquatic environmental problems, a study of two estuarine systems was undertaken.

In cooperation with Robert Huggett of VIMS (who provided a boat and crew for sampling) a heavy metal characterization

of Woods Creek was begun. Woods Creek is a small marshy

waterway which flows into Skiffes Creek, and subsequently

the James River near Fort Eustis, Virginia. A Dow Chemical

plant dumps liquid effluent that is reportedly high in Zn

into this creek. The problem is to determine the fate of

the Zn in this waterway. Nine stations were sampled over

a two-mile stretch of Woods Creek yielding filtered liquid,

suspended particulates, and sediment (top cm) samples for

each station. The liquid and suspended particulate samples

have been analyzed for Zn and 10 to 20 other elements.

The normalization technique described above enhances the

information obtained from the suspended particulates, that

is, enrichments of elements relative to crystal material

(as indicated by scandium) can be followed down the stream.

Figure 35.1 shows the effect of normalization on two groups of

elements. Completion of this project will require combining

our data on filtered liquid and suspended particulates with

sediment data from Mr. Huggett.

244
Phases 1 and 2 of the project (development o£ analytical

technique and development of water sampler) are essentially

complete. The primary objective of phase 1 was to determine

if freeze drying (or lyophilization) of water was a viable

technique for trace element preconcentration. The results

of this work were published by S. H. Harrison, et al . in the

August 1975 issue of Analytical Chemistry . Phase 2 involved

the development of a Teflon water sampler with special features not presently available in commercial water samplers.

The design and operating characteristics were described in

a talk presented at the 7th Materials Research Symposium,

October 1974, in Gaithersburg, Maryland. The manuscript of

this talk appears in the Proceedings of the Symposium.

Phases 3 and 4 of the project (the use and evaluation of the

water sampler and its application to sampling studies) are

essentially complete. Because of the nature of phase 3, the

sampler evaluation is an open ended project, but that part

supported by the Office of Air and Water Measurement is

complete

.

For the most part, phase 3 consisted of replicate sampling

studies (to determine natural variations of trace element

concentrations at a single location) and data treatment

studies. Much of this work is reported in the Proceedings

of the 7th Materials Research Symposium referenced above,

and some of it was presented at the 1975 Annual Meeting of

the American Nuclear Society, June 9, New Orleans.

Changes and improvements in the techniques developed in all

four phases are continuing, as experience dictates. An

example of this is recent work on improving cleaning procedures of the polyethylene film used for making the water

sample bags. Using a 24-hour washing period in 5 N HCl prior

to the customary HNO3 washing, the average Fe concentration

in the film has been reduced by 501 (compared to the previously reported value in the Analytical Chemistry paper)

,

the average Co concentration by an order of magnitude, and

the average Mn concentration by almost an order of magnitude.

References

[1]. deGroot,A.J. and Allersma, E. , Conference on Heavy

Metals in the Aquatic Environment ., Nashville , Tenn.

(December 1973)

.

245
oo I o

too

00o oI oo

CM

ro

IX] S

a,

K-3 CO

PQ

CO

Ou

p-(o

CO

pq^

(SI o

(NJ ooO I bOOoooovOI oooooo<S1 tooovO

csiI oto

\0o00

00o

u->

m

1-1 ooooo Iu

•HP>

tg<DH

m E? o >

•S

bO

I-- ^

LO• • e rt 00 nJ § PQ rH ^H •%

5-1 iH 0) 5h bO CD 4-> Si O C .31 5^ 2 >^ CQ'^ 3

<oV

g <D

CO -H /—>

bO <D ?H <+-l • rsj rt >s bO-H cj r-- U rH o u (Tt (D O ua • 1—1 < 2 CI)

M

(D Q

•MO

246
t>u

CONCENTRATION IN Ng/g A CONCENTRATION IN Ng/g

50 A \

40 _ \ Zn X 10"^

\\ yApe X 10"^ —

30 - \ ^k^'^^^Ov ~ /\cr /N. \

^^^ >\^ y

20 " \/ \\ ^\^

10 - ^\ ^^_

u <a)

^^

(c) _

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 23456789 1 23456789

1.2

1.0

0.8

— 0.6

*^0.4

60

50 ~

40 -

30 -

20

-

NORMALIZED TO SCANDIUM NORMALIZED TO SCANDIUM _

"" / \^n X 10"^

/ X. v/^V Ce X 10'^

"

~y h \

^-^ =

^ \^ Th "-^

lV\\

(b)

^

(d) __

1 1 1 1 1 1 1 1

1.2

— 1.0

— 0.8

0.6

0.4

0.2

123456789 12345678 9

Figure 35.1 Plot of heavy metal concentrations and scandium

normalized concentrations (x/Sc) of suspended particulates vs.

sampling station in Woods Creek where station 1 is the headwaters

of the creek, and station 9 is just below the confluence of Woods

and Skiffes Creeks . Distance between sampling locations is '^equal*

247
56. Development of a Deep Sea Ocean Sampler

Project Leader: Meyer Waxman, Heat Division

Other Personnel: Harry Davis

Objective

Design, build, and test a deep-ocean biological water sampler,

simple enough to be used by oceanographic researchers having

access to only simple and unsophisticated vessels.

Approach

Initial design considerations included the utilization of the

potential energy of the ocean with depth, of a free-falling

piston within a cylinder and of an evacuated vessel to be

opened at an appropriate time. The apparatus was to be a self-contained unit with provisions for a sequence of programmable events to take place on the ocean bottom. These

were to include allowing time after bottom impact for

adequate settlement of ocean-bottom sedimentation, allowing

for equilibrium of the vessel's internal and external pressures, flushing of the vessel prior to its filling and

releasing the sampler, after filling, for return to the

ocean surface. All necessary energy for the operation of

the different events were to be derived from compressed gas,

batteries , or wound springs . We chose to select the latter

concept because of its proven dependability in numerous technological applications. Industrial engineers, experts with

both electro-mechanical and mechanical spring devices,

strongly advised the sole use of the latter, again because

of proven reliability.

Progress

A deep-ocean environmental sampler has been constructed to

tolerate an internal pressure 15,000-20,000 psi with a marked

safety factor. The sampler has been tested in a high pressure

testing facility made available by the U. S. Navy. It is

autoclavable and capable of maintaining sterility, as shown

by studies carried out at the University of Maryland. The

sampler permits recovery of samples without decompression.

It can be used as an incubation chamber, with nutrients added

to the sample and for the withdrawal of aliquots of the sample

for analysis or transfer to other incubation units without depressurization of the sample. The sampler has been designed

248
so that it is deployed closed, sterile and internally pressurized, and at the site of sample collection, opens,

collects a sample, closes, and is retrieved with the samples

maintained under in situ pressure.

A cruise was accomplished February 11-14, 1976, aboard the

R. V. Eastward to the Puerto Rican trench. Two successful

casts were obtained. The first successful cast was at a depth of 6,800 meters. The depth was calculated from

reversing thermometers and from the internal pressure of the

sampler upon retrieval and, in addition, readings made with

a pinger. The water sample was subsampled using 4 (3 ml)

syringes, filled by release of the in situ pressure (approximately 680 atmospheres. The syringes were immediately

repressurized to 10,000 psi at 3°C. In addition, 2.5 ml

subsamples were collected and added to MSWYE broth (9.0 ml).

The nutrient broth was incubated at 3°C and good growth has

been obtained. Cultures are presently being isolated. In

addition to the successful retrieval of the first pressurized

sample, the second cast provided a sample brought back under

pressure from 3,430 m. On testing the internal pressure of

the sampler on retrieval, the depth of the cast was confirmed

and the reversing thermometer calculations also provided

evidence of the cast at the depth indicated. We have maintained the water sample, under pressure, at approximately

343 atmospheres and have been able to introduce nutrient

without decompression. These samples are still under pressure

at 3°C. We anticipate being able to determine evidence of

microbial growth and uptake since a radioactively labled substrate was introduced into the pressure chamber.

Work is progressing well on perfecting the sampler, that is,

to provide transfer under pressure to fresh culture chambers

and to improve the mechanism for introduction of nutrients

under pressure. The sampling devices are also being improved

to withstand repeated heavy duty use in the field.

249
37. An Electrochemical Chlorine Flux-Monitor

Project Leaders

Other Personnel

G. Marinenko and J. Devoe, Analytical

Chemistry Division

D. Friend, J. L. Andrews, A. A. Bell, D. F.

Braun, F. C. Ruegg, J. K. Taylor, R. Shideler

and R. Huggett, Virginia Institute o£ Marine

Science

Objective

The work described here deals with research leading to the

development of an absolute, coulometrically calibrated

chlorine flux-monitor capable of measuring chlorine in

water down to 10 ppb

.

Approach

Chlorine, chloramines, hypochlorite and other higher states

of oxidation of chlorine will oxidize iodide to iodine at

proper pH. Under select conditions one can separate some of

the individual chlorine species and chloramines, taking advantage of different rates of oxidation of iodide. The initial

effort, however, was directed at the determination of total

residual chlorine. In the reaction with iodide one mole of

chlorine produces one mole of iodine. Thus, monitoring the

molar concentration of iodine is equivalent to monitoring the

molar concentration of chlorine.

250
An electronic measurement package was designed and constructed

to complement the electrochemical flux-monitor cell. Such an

instrument fulfills the requirements for a field instrument.

It requires no external power source (battery-operated) , is

portable and features digital display of the signal either in

microamperes or in ppm of chlorine after calibration.

Laboratory Performance of the Chlorine Flux-Monitor

Two series of experiments were conducted with the chlorine fluxmonitor: (1) to assess its reliability in measurement of

low levels of chlorine (2) to assess its accuracy.

(1) To study the performance of the chlorine flux-monitor in a laboratory assessible "natural" system, cold tap water was

selected as the system to be investigated. A chlorine concentration was measured in undiluted tap water (after clearing

the lines of stagnant water by running it for 1 hour before

sampling). Subsequently, a factor of two dilutions of tap

water with distilled water series was performed, and the concentration of chlorine was measured after each dilution. The

results of this series of experiments are shown in Table 37.1,

(2) To test the accuracy of our measurement a fresh bottle of

"Chlorox" was used to prepare 52 ppm stock solution. Subsequently this solution was diluted 1:1000 just before measurement and further diluted according to factor of 2 dilution

scheme used in the tap water experiment. The results of this

series of measurements are shown in Table 37.2.

Field Tests of Chlorine Flux-Monitor

Two separate field tests of the chlorine flux-monitor were performed. The first test was executed in an actual emergency

situation at the peak of a massive fish kill near Newport

News, Virginia. On May 30, 1974, during a fish kill our

equipment was taken to Gloucester Point and used for monitoring chlorine in the James River. Our measurements were

conducted aboard a boat furnished by the Water Quality Control

Board (WCB) over several square mile areas of the river near

the outfall of a sewage treatment plant. Initially our boat

was the only one from which measurements were performed.

Subsequently we were joined by another boat with a commercial

amperometric titrator on board. The results of this river

survey are as follows:

251
TABLE 37.1 Serial Dilution o£ Tap Water

Expt.

No.

Dilution

Factor

C

Co

alculated

nc. of CI2

ppm^

Measured

Cone, of CI2

ppm

d

1 Undiluted - 1.237 +0.002

2 2 0.618 0.620 -0.011

3 4 0.309 0.298 +0.006

4 8 0.154 0.148 +0.006

5 16 0.077 0.072 -0.005

6 32 0.038 0.038 0.000

7 64 0.019 0.020 +0.001

8 128 0.010 0.010 0.000

9 256 0.005 0.005 0.000

10 512 0.002 0.003 +0.001

11 1024 0.001 0.001 0.000

d= +0.003

Based on the measured CI2 concentration in undiluted tap

water in Experiment No. 1.

252
TABLE 37.2 Serial Dilution of Chlorox

Dilution of 52 ppm

Chlorox Solution

Calculated

Cone, of CI2

ppm

Measured

Cone, of Cl^

ppm

d

0.052 0.051 -0.001

0.026 0.025 -0.001

0.013 0.011 -0.002

0.006 0.005 -0.001

0.104 0.104 0.000

0.052 0.053 +0.001

0.026 0.026 0.000

0.013 0.013 0.000

1:1000

1:2000

1:4000

1:8000

1:500

1:1000

1:2000

1:4000

d = 0.001

253
An electrochemical system for monitoring iodine concentration

consists of a platinum microelectrode and a saturated calomel

electrode. With volt applied to such a cell one obtains a current proportional to the concentration of iodine (and thus

chlorine)

.

For calibration purposes an accurately known amount of iodine

can be generated coulometrically at a known rate. Consequently,

the amount of electrochemically generated iodine, or known

iodine flux, needed to produce an amperometric signal identical to the signal obtained from unknown water, corresponds to

the unknown chlorine concentration.

Progress

Experimental Research

An analysis and calibration system was constructed taking

advantage of the described electrochemical principles.

The electrochemical chlorine flux-monitoring system shown in

Figure. 37.1 was designed and constructed. It consists of

two distinct and separate electrochemical cells, which function independently. Although the two cells are incorporated

into a single system, each cell performs a unique function

for which it was designed. The two cells are designated as

follows: Calibrating generator (1); detector (2). In the

system 0.1 M KI, pH 4 buffer in saturated NaCl solution is

slowly injected into the stream (3).

Cell (1) operates only during calibration of the instrument,

which can be performed as frequently as desired. The function of cell (1) is to generate a known, preselected, flux

of iodine for signal calibration.

•The chlorine monitor requires the aqueous solution (sample

water) to flow at a uniform rate through the monitor (4)

.

The output of the detector cell (2) is electrical current, the

magnitude of which depends on the concentration of chlorine.

Typically for our system the current is 20 yA when the concentration of chlorine in the sample is 1 ppm.

254
Figure 37.1 Chlorine Flux-Monitor

(1) Calibrating Generator Cell

(2) Amperometric Detector Cell

(3) Reagent Inlet

(4) Sanple Inlet

255
June 30, 1974

NBS-VIMS WCB

TT^n^ h T *• Chlorine via Chlorine

^^"^^* ^ Location Flux-Monitor .ppm ppm

11:00 Outfall 0.160

11:20 Mid-River channel

at Blunt Point 0.022

11:35 Bouy off N12 0.029

12:00 Outfall 0.223 0.20

12:20 Outfall 0.245 0.24

12:30 Outfall 0.252 0.23

12:55 200 m east of outfall 0.035

13:20 1000 m east of outfall 0.029

13:35 Outfall 0.181 0.21

At the request of the State of Maryland Water Resources Administration, the second expedition was made on June 19, 1974,

to monitor chlorine in streams of Northern Maryland. A

second instrument was also used in addition to the chlorine fluxmonitor to determine the chlorine in the same water.

The fact that the chlorine flux-monitor has a small residual cur- rent due to the presence of iodine in KI -buffer mixture, for

which compensation is made electrically and zero in the

instrument, appears to be an asset. While the other titrator

showed "zero" chlorine level in waters of most of the surveyed

streams, our instrument showed a reversal in the polarity of

the signal (negative sign) corresponding to 0.015 to 0.032 ppm

chlorine equivalents of reducing agents in the water. This is

additional significant data which is obtained using the fluxmonitor. At one point we sampled the treated, undiluted

sewage outfall from a small sewage treatment plant, which

services a development in Northern Maryland. It was again

an interesting test of the NBS chlorine flux-monitor. The

amount of chlorine was too great to arrive at a confident

value via the commercial instrument. Several burette fillings

were required thus the estimate of chlorine level obtained via

the other titrator was about 4.5 ppm. The virtually instantaneously responding NBS chlorine flux-monitor displayed 5.57

ppm as the concentration of chlorine.

256
A sample of stream water taken a few yards away from the outfall (consequently resulting in the dilution and reduction of

chlorine by the stream water and the reducing agents present

in the stream respectively) was also analyzed using tne flux-balance

monitor and the other titrator. The flux-monitor value was 0.02&

ppm and that obtained using the titrator was 0.03 ppm.

The chlorine flux-monitor is an instrument which meets today's

requirements of low level chlorine monitoring in natural waters.

Experimental data show that chlorine levels of a few parts per

billion can be measured with the uncertainty of 0.1 ppb

.

Design and Construction of a Prototype Chlorine Flux Monitor

The aim of this part of the project was to design a self contained, portable chlorine monitor capable of field survey

measurements utilizing the electrochemical cell devised by

Dr. George Marinenko, and to produce eight of these instruments

for field use and further evaluation.

A modular instrument was designed consisting of three assemblies: an electronic measurement and calibration unit, a rechargeable battery pack, and a water sampling unit containing the electrochemical cell. The design was based on

information gained while using an earlier prototype electronic

unit and from field and laboratory data. Special attention was

given to providing increased sensitivity, stability and ease of

operation.

Upon completion of the instrument design, two units were constructed and made available for operational tests. Subsequent

evaluation including field tests conducted on the James River

in Virginia in cooperation with the Virginia Institute of

Marine Science revealed deficiencies in two areas of operation.

The electronics malfunctioned when subjected to the extreme

humidity of ocean air, the introduction of reagent was found

to be inadequate and unreliable, and the reagent buffer mixture

was unstable.

The electronics system has been modified to reduce or eliminate

susceptibility to moisture. Stable operation under prolonged

exposure to conditions of high humidity and temperature has

been demonstrated. Operation in a salt air environment has

yet to be shown. Acceptable operation of the reagent induction

system has been achieved using separate ports for reagent and

buffer with external capillary limiting flow.

257
In accordance with the production goal of eight units, all

components have been acquired and assembled. The electronics

systems for six units are complete and tested. Two water

sampling units are complete and are undergoing tests with the

remaining six units awaiting final design of the reagent

introduction system.

A package of in-house drawings and documentation has been

assembled and is being made available .to all interested

parties

.

258
38. Priority Standard Reference Materials in Water Pollution

Project Leader: R. Alvarez, Office of Standard Reference

Materials

Other Personnel: R. H. Meyer

Objective

To determine the most urgent Standard Reference Materials

needs in water pollution.

Approach

A questionnaire was devised to determine the need for

primary SRMs in water analysis, to provide guidance for their

composition and production.

Progress

In all, 300 questionnaires were mailed to interested parties

in industry. Federal, state, and local agencies, universities,

private water testing laboratories, and centers for oceanographic studies. The mailing was directed primarily to

members of the ASTM Technical Committee D-19 on Water.

Information was requested under these headings:

I. inorganic pollutants

II. organic pollutants

III. turbidity or particulate

IV. anticipated use for all SRMs

V. information on low-blank reagents

A total of 165 responses have been received. The results of

the responses are summarized in Tables 38.1 and 38.2.

259
TABLE 38.1 Relative Importance of Inorganic Pollutants

and Desired Concentrations Based on Questionnaire Responses

Concentrations in mg/liter (ppm)

Mercury 0. 001 1 0.005 0.05 0.01 5 10

Cadmium 0. 01 0.001 1 0.1 0.05 5 10

Lead 1 0.05 0.01 0.1 0.001 5 10

Arsenic 1 0.01 0.001 0.05 0.1 5 10

Chromium 1 0.05 5 0.01 0.1 10 0.001

Copper 1 0.01 0.05 0.1 10 0. 001 5

Cyanide 1 0.01 0.1 0.05 5 10 -

Selenium 0. 01 1 0.001 0.05 0.1 5 10

Fluoride 1 10 0.1 0.5

Zinc 1 s 0.1 0.01 10 0. 001 0.05

Barium 1 0.1 5 10 0.01 0. 5

-

Iron 1 10 0.01 0.1 0.05 - -

Nickel 1 0.05 0.1 5 10 - -

Silver 1 0.05 0.01 0.1 10 _ _

260
TABLE 38.2 Relative Importance of Organic Pollutants

and Desired Concentrations Based on Questionnaire Responses

Concentration in mg/liter (ppm)

Polychlorinated

Biphenyl

0.001 0.01 0. 1 1

Aliphatic

Hydrocarbons

1 10 0. 1

Aromatic

Hydrocarbons

1 10 0. 1 0.001

DDT 0.001 0.01 0.1

Aldrin 0.001 0.01 0.1

Dieldrin 0.001 0.01 0.1

Benzidine 0.001 0.01 0.1

Chlordane 0.001 0.01 0.1

Endrin 0.001 0.01 0.1

DDD 0.01 0.001 0.1

DDE 0.01 0.001 0.1

Toxaphene 0.001 0.01 0.1

261
59. Mercury in Water Standard Reference Material

Project Leader: H. L. Rook, I. L. Barnes, Analytical

Chemistry Division

Other Personnel: J. Moody, P. Paulsen, and T. Rains

Objective

The objective of this project was to investigate stability,

prepare and analyze trace ionic mercury in water solutions for

ultimate SRM certification. Two mercury concentrations were

chosen, one at -1.5 yg/g for "spike" standardization of

natural waters, and one at ~1 ng/g for benchmark standardization.

Approach

Tracer studies, using carrier free mercury- 203 can reveal

mercury losses from solution. Loss of mercury would be

reflected in a diminishing gamma-ray count rate. Conditions

would be sought under which no loss of mercury from solution

would be experienced.

Progress

Solutions were prepared to a mercury concentration of 1.00

ng/ml, as the nitrate, and stored in 1 liter, precleaned.

Teflon bottles. Carrier free mercury-203 was added to give

a gamma-ray count rate of -30,000 cm/min per ml of solution.

One ml aliquots of each solution were withdrawn at successive

time intervals and counted at a fixed geometry to determine

the mercury concentrations.

262
Solutions were initially stabilized with acid or EDTA and

studied for mercury loss as a function of time. The individual

solutions were as follows:

1. 0.5 N HNO3 + 1.0 ng/ml Hg"*""^

2. 0.5 N HNO2 + 0.2 N H2SO4 + 1.0 ng/ml Hg"^"*"

3. 0.001 M EDTA + 0.1 N NH^OH +1.0 ng/ml Hg"*""^

Loss of mercury from solution was found in all cases. The

acid stabilized solutions lost about 201 per month (Figure

39.1 and the EDTA stabilized solution lost about 901 per

month. After 16 days, 1 yg/ml gold, as the tetrachloride,

was added to the solutions. The acid stabilized solutions

recovered to the original mercury concentration and remained

constant for the duration of the two-month study. The EDTA

solution recovered to -851 of its original concentration.

Following this study, two solutions were made, stabilized

with 0.5 N HNOj and with AuCl, at the 0.01 and the 1.0 yg/ml

levels, respectively. These solutions were stored in

containers of Teflon, borosilicate glass, and polyethylene.

To the present time, all solutions have maintained constant

mercury concentrations within the error limits of the mercury20 3 count rate.

I. Analysis

Analyses of the solutions were carried out by three independent

analytical techniques: Atomic absorption, neutron activation,

and isotope dilution spark source mass spectrometry. The

major problem in the analyses was variation in the blanks of

reagents and water used to make up the test solutions. Finally

by using the NBS Analytical Chemistry Division-produced ultrapure water and reagents, and isolating all work to one clean

area, the blank was reduced to about 0.05 ng/ml +_ 100% relative,

All analytical techniques improved their ability to determine

trace mercury to the point where errors were less than +^5%

total.

II. Production

1. Cleaning of Bottles and Ampoules- -The glass ampoules

used for the 0.5 ppm SRM were first cleaned by multiple rinses

with distilled water followed by immersion in a bath of

boiling 1+5 HNO^ for 24 hours. After draining out all of the

acid and rinsing with distilled water, all of the ampoules were

filled with a special ultrahigh purity distilled water prepared

at NBS.

263
A period of two weeks storage was allowed for the water to

leach the ampoules. Afterwards they were drained, rinsed with

ultra-high purity water and then dried in a class 100 forced

clean air oven. The Teflon bottles were cleaned in a similar

manner with 1+5 HNO^ followed by 2 or more weeks storage with

ultra-high purity water in them. The Teflon bottles were air

dried in a clean room, numbered, and then weighed dry.

All other plastic containers, volumetric flasks, pipets, and

other apparatus received a similarly thorough cleaning. All

apparatus and containers were new, having never been used for

mercury before. All water and acids used in the preparation

of the solutions were ultra-pure reagents made by a subboiling distillation process at NBS.

2, Preparation of Solutions --Weighed amounts of pure gold

and pure mercury were dissolved and made to volume in

volumetric flasks using -6 N HNO-. A master solution for the

1.5 ppm standards was prepared by weighing out the appropriate

amounts of HNO- and H-O to give 20 liters of 0.5 N HNO- in a clean polyethylene carboy.

On the day before the ampouling operation for the 1.5 ppm

standard, aliquots of the gold and then mercury solutions were

added to the carboy. A magnetic stirrer was used to keep the

solution well mixed.

The dilute master solution for the 1.2 ng/g standards was

prepared by diluting the primary mercury standard. This was

done by weight in a clean two- liter Teflon bottle.

All of the one liter Teflon bottles for the 1.2 ng/g standard

were individually filled with 940 ml of water with sufficient

nitric acid added to make the solution -0.5 N in HNO-.

Approximately 10 yg of gold was added to eacF bottle. This

operation was also done on a weight basis.

3. Production- -An ampouling machine with Teflon tubing

and valves and a glass piston pump was used to fill the glass

ampoules with the 1.5 yg/g master solution. All liquid contact

parts were thoroughly cleaned in HNO^ and after assembly the

entire system was purged by pumping several hundred ml of the

master mercury solution. During the automatic ampouling

operation, a class 100 clean air environment was maintained

around the apparatus. All ampoules were sequentially numbered

for sampling purposes.

264
For the 1.2 ng/g SRMs , a 10 ml aliquot of the dilute master

solution was added to each of the one liter Teflon bottles

which had been previously filled with 940 ml H2O + HNO,, and

the gold stabilizing agent. Since this solution was also

prepared by weight, several determinations were made of the

final solution density in order to convert weight

concentration values to volume concentration values. The

theoretical concentration of mercury in these two SRMs was

calculated to be 1.495 yg/g and 1.23 ng/g, respectively in a nominally 0.5 N HNO^ solution. The nominal gold concentrations

were 1 yg/g an^ 10 ng/g, respectively.

All work on SRM #1641 and 1642, Mercury in Water Standard, is

complete. A successful method for stabilizing ng/g levels

ionic mercury in water was developed. Analytical methods for

the determination of mercury at that level were studied and

improved. Final certification analyses were completed within

the +51 error limit originally desired. The certified mercury

contents are:

SRM #1641 - 1.49 + 0.02 yg/g

SRM #1642 - 1.18 + 0.04 ng/g

265
oO

a.

03 CO

266
40. Mercury in Water Collaborative Study

Project Leader: D. A. Becker, Analytical Chemistry Division

Other Personnel: I. L. Barnes, J. R. Moody, H. L. Rook,

P. J. Paulson, T. C. Rains

Objective

To determine the present state-of-the-art for the determination

of mercury in water at ambient concentrations, and to evaluate

the effect of a Mercury in Water Standard Reference Material

(SRM) on the analytical results obtained by a variety of laboratories.

Approach

Two Mercury in Water SRM's have recently become available from

NBS, a low level SRM (1642) certified at 1.18+0.05 ng/g, and

a higher level SRM (1641) intended for laboratory spiking or

dilution wich is certified at 1.49+0.05 yg/g. These solutions

were stabilized with gold ions as d^escribed. [1]. In an

attempt to evaluate the effect of these new SRM's on the

measurement system as it presently exists for mercury in natural water, a set of four stabilized mercury solutions were

made at varying concentrations, ranging from less than one-half

to almost five ng/g. Seventeen laboratories were statistically

randomly selected from a group of over thirty which expressed

an interest in participating in this study. The laboratories

selected included four federal government laboratories, seven

city and state government laboratories, and six industrial,

non-profit, or private testing laboratories.

Progress

The study was completed in two steps. The first step, undertaken prior to the general announcement to the availability

of the SRM's, entailed sending 2 50 ml samples of the four

test solutions to the laboratories for analyses. They were

to apply their standard analytical technique for natural

waters (including digestion) , using not more than one-half

of each sample. The second step included reanalysis of the

remaining portion of the samples, but was to be completed

only after each of their analytical systems had been evaluated

and optimized using SRM 1642, Mercury in Water-Trace. The

267
study has now been completed, and twelve of the laboratories

have submitted their final results. These results have been

statistically evaluated as to general mercury analysis capabilities and the effect of SRM use on the final values.

Results and Discussion

The date received showed a great deal of scatter, with several

of the laboratories submitting individual values in error by a factor of 10 or more. Of the twelve laboratories reporting

results, only eight provided unambiguous information on all

concentration levels. The results from these eight laboratories

were then evaluated statistically for each of the four concentration levels. The analytical precision (relative standard

deviation, expressed as the percent of the average) ranged

from 60% at approximately . 2 ng mercury/g solution, down to

almost 71 at the 5 ng/g concentration level. The analytical

accuracy without the SRM (expressed as percent deviation from

the "known" target value) ran from +33% at the 0.2 ng/g level,

down to +41 at the 5 ng/g level. The accuracy of the results

by the laboratories after using the SRM to calibrate their instruments was only slightly improved, ranging from +28% down to

+ 3%.

The conclusions which must be drawn from the above results are

that the present state-of-the-art for the determination of mercury in water at the ng/g concentration level is so imprecise

that it was difficult to evaluate the effect of the Mercury in

Water SRM at these levels. This is illustrated by the fact

that for the eight of seventeen laboratories which were able

to complete the analyses satisfactorily, the imprecision of

all determinations below 1.0 ng/g averaged ±57%.

References

[1]. Rook, H.L., and Moody, J., Stabilization and Determination

of Nano-gram Quantities of Mercury in Water, Proceedings of

Nuclear Methods in Environmental Researahy University of Missouri-Columbia

(July 1974) pp. 44-53.

coa

k

268
41 . Transformations of Heavy Metals in Aquatic Environments

Project Leaders:

Other Personnel:

Guest Workers:

Objective

F. E. Brinckman, Inorganic Materials Div.

and W. P. Iverson, Metallurgy Div.

G. E. Parris, K. L. Jewett, W. Blair

C. W. Huey, J. M. Bellama, T. Watters,

and D. Nies, University of Maryland;

Br. J. E. Doody (Christian Univ., Tenn.)

The principal objectives of this continuing project are to

characterize the sources and fate of toxic heavy metals in

the environment through: (1) determination of key

biological, chemical and physical mechanisms in natural

water systems for mobilization and transport of heavy metals,

and (2) development of measurement capabilities for this

characterization. Information derived from new instrumental

approaches to these studies can provide keys for the

prevention or control of release of toxic, methylated forms

of such heavy metals from new sources such as antifouling

^coatings or pesticides or already established reservoirs m

natural bodies of water (rivers, estuaries, etc.).

Approach

An understanding of the chemical and biological nature and

dynamics of metals transport in natural waters requires

a balanced interdisciplinary approach to characterizing key

pathways. The NBS interdivisional team comprises organometallic and microbiological expertise.

The effort has involved some outside sponsorship from the

Environmental Protection Agency, the Naval Ship Research and

269
Development Center, and the National Science Foundation.

Support in the form of available shiptime from NSF and the

Chesapeake Bay Institute has permitted continuance of an

active field sampling program in the Chesapeake Bay. Academic

collaborations also form an integral component of this interdisciplinary project. Thus, joint research continues with

Dr. Colwell of the Marine Microbiology Group and Guest

Workers and staff from the Chemistry Department at the

University of Maryland. Collaboration with the Virginia

Institute of Marine Science (VIMS) has also been ongoing

during the period. Such involvement ensures a realistic

and balanced approach to relevant metal transport questions

involving both chemical and biological processes.

Progress

41.1 Instrumental Development

An instrumental method for the determination of metallic

mercury, dimethylmercury and methylmercury in the nanogram

range has been developed and placed into routine laboratory

use [3] . This method employs a gas chromatograph coupled

with a mercury-specific flameless atomic absorption spectrophotometer (GC-AA) which serves as the detector for

elemental mercury or organomercurial species eluting from

the chromatographic column. The method has been used for

qualitative surveys of trace organomercurial compounds

produced from biological and abiotic processes as well as for

the indirect detection of methylated forms of other metals

which can exchange methyl groups with mercury(II) (Fig. 41.1.1)

For the specific detection at trace levels of volatile forms

of metals other than mercury, the GC was coupled to an atomic

absorption spectrophotometer employing a graphite furnace

(GC-GF-AA) . The effluent from the GC was passed via a thermostatically controlled stainless steel transfer tube to

the graphite furnace (Fig. 41.1.2). Since the maximum time

to which the graphite tube could be heated at the atomizing

temperature is limited, a solid state electronic logic

circuit was built and incorporated into the NBS GC-GF-AA unit

to permit pulsing the furnace (viz.; 30 seconds on 15 seconds

off) as the GC effluent passed through it (Fig. 41.1.3).

Pulsed gas chromatograms of tetramethyltin and tetraethyltin

are indicated in Fig. 41.1.4).

More recently, the GC-GF-AA system has been evaluated for

the quantitative element-specific analysis of gaseous

Me_As, Me2Se, and Me.Sn, (Me=CH^) , as well as for their

detection in aqueous media. The atomization temperatures

were found to be reasonably predictable from available

thermochemical properties of the elements and compounds

270
AIR

8 DAYS

pH = 7.2

^wMiW»^^vi/yw>^^^ ^%*,rt*nK Ps* Hg*Sn

^'T'^^"^*^^****''*'^"*^^ Ps Hg >V^VAy«w«V^wNt.vws,«w^

A^»\S^^^y»>»,|i,Avy|,i^,>)^ Ps Sn »^N^*^'r»N»*»H^<^'*^>lVVMW>^^

t^^ttf^fiiff^llfnt^ffr^t^^fff'tll^^i^/t^ttlff^^lf'^ffff^^^^ff^ Hg Sn

-Hg°

v\fi>vV»yvV'AM*V*>iM*«*«y'' i*»^n»»hi»i#.iii'

MeHgCI

>V^»»W/*7[VM^»*v^/«*<^yvv*V**^»*'«vv«^ BLANK

10

CALIBR

mm

Figure 41.1.1 Pseudomonas grown on metal-doped slants under either

air or nitrogen atmospheres after eight davs.GC-AA soectra show

substantial reduction in free mercury content of air-grown series, but a large concentration of methylmercury has formed in those vessels where

Pseudomonas is exposed to both Hg(II) and Sn(IV). In the corresponding

anaerobic series under N„ , substantive amounts of both gaseous mercury and

methylmercury form, although the calibration spectrum at bottom confirms

the absence of dimethylmercury.

271
o<

UJ o

iH

.4-1

CO

cd00 uc

(U3

00c

•Ho

0}I OI oooo

(U p

(U -d

(Uo

tdc

0) p

•H

bOO /-^

(0 S 0)

Cd

a

U -H

60 rH

«d •H T) G CO O cd •H 73

4J ^-^ O

0)

U

CO

O

CO S

CO o o u U M-i CJ CM3

00 I

272

pl^
Figure 41.1.3 Gas-chromatograph (left) coupled to an atomic absorption

unit (right) via thermostatically controlled tube (above both units)

and electronic pulse programmer (lower center)

.

273
—

c

0)

2

II <

in

i

-CM

-'^

->o

-00

1^

II

O

-CNJ

z

2

Figure 41.1.4 Pulsed AA- chromato grams of gaseous samples of tetramethyltin

and trimethyltin are compared, showing Sn-specific detection at A = 224.6

nm. A represents interval between atomization pulses at 2700 .

274

i
(Table 41.1.1). Thus, a consideration of the critical

reactions occurring during atomization in the graphite furnace

(Fig. 41.1.5) suggested improved AA techniques. It was found

that the sensitivity could be greatly increased by the

addition of H2 to the GC carrier gas, thereby using

considerably reduced atomization temperatures (1500-1800 C°)

allowing the elimination of the pulse mode of operation, just

described, for such less refractory organometallic compounds.

This dramatic improvement is illustrated in Figure 41.1.6.

Typical calibration curves for Me2Se, Me^As, and Me.Sn are

shown in Figure 41.1.7. Specific analytical details are

presented in Table 41.1.2. along with evaluation of detection

limits at 951 confidence limits. Details of this work are

in the process of being prepared for publication [13] . The GC-GF-AA facility currently permits serial metal-specific

detection of such organometals at nanogram concentrations in

head gases above water containing a variety of organic compounds associated with bacterial metabolites. The system is

clearly applicable to other volatile organometals at trace

concentrations. Preliminary results for organosilanes appear

promising, although so far column decomposition has limited

effectiveness for speciation and quantification of very

highly reactive organometallic gases, such as dimethylcadmium.

A Perkin-Elmer Model AD-2 electronic microbalance has been

acquired which facilitates the weighing of small solid samples

for direct solids analysis with the AA unit.

41.2. Field Studies and Sampling

During the pas.t three years, an active field schedule of

sediment, water and plankton sampling of the Chesapeake Bay

has been pursued. Materials so acquired have formed the basis

of most of the specific laboratory experimental parts of the

project, e.g . , isolation of bacteria and analysis for sulfur,

metals, and oil

.

Investigation of elemental sulfur found in the Chesapeake Bay

sediments revealed an enrichment of S over S-^^in all except

one of five sulfur samples, indicating bacterial sulfur

cycling. In these sediments, as much as 501 of the total

mercury loading was found to be available in a soluble

(organic solvents) form, bound to complex organic groups.

The Hg in petroleum fractions from the sediment was detected

by Hg-specific GC-AA in oil fractions eluting at retention

times characteristic for either C2Q petroleum components or

organomercurials of high molecular weight (Figure 41.2.1) [8].

Availability of the new GC-GF-AA facility will now permit

extension of this Hg-speciation work to evaluation of other

metal species in marine sediments. Of particular interest

275
n

CM CM

O o CM CM CM

C ee CM X X O o X X X X

0)

X rs. p^

B m> •t C<J p^ •> #t •> •1 * A. (/] CO (/} CO o <J OT •H u M tt 4J * « •t M •o •a M ai •t «k •H o «) V

•n

O o O o a « O

O o O

B

Q o o O

O rH fH o o o o

00 00

m t^ r^ 3 3 in CO 00 in o H ^ iH fH iH Cli CL, tH iH fH rH ^ eo -

•H I C3U<<oOCuwHe

CO

CO

60

<n

fH

-it

•»

-aCT> i-(

•»'

m vO vO

ON fH CM P-l

o\ >e 1^ iri vO r^ cn 00

vC i~~

m •ff + r*

<u e< « To u cn CO

m o vC o -a- r^ S 00 •« o r-( «» 00 iTl 0^ 00 CM \r\ o o u • • CM • • • • • • 1^ m •» 1-1 iH 00 vO p^ CO fH CO r*

oT-o 00 o <-i yo \0 00 r-. NO ON o ON a u 00 o <N ir, CM iri r^ irl o ON CM a CO 00 O <t r^ ON r^ p^ r-t ON 00 * * • •t «, ft m CO )>( vO r^ 00 00 o nA NO <n 1/^ CO U-l o m ON M ON r** ON CO o CM + vO r^ 1^ O) rH CM fH p^ CM UO -*

>-* #• 8 -H O ON

CO P~ 0> ON o pe u ^ <J> *n rH r-t .-I

•H

B

XO

a .a

eg

b

m (« oc U

II (J H

t5

U

>N fH

T5 kl

OJ ^ 4^ a c j: X V - 3 e

•H « B u

•H

iH JS B a.a I o B -H

u

CO 00 ^ . . CJ « 3. f—f

(—

CJ

00 • • .H 00 o

0) CO iH CM e B o b^ i_i o. > > hi a. 3. n U

CJ tM o U-l U-l B B > o o o 01 01 o

•* IV

h ^ -H 1 0) 10 4J •a, u IH o w u « <M IH o H •H fH w 01 CO CM 3 B3 3U

fH 01

CO00

«'

CB 18

u 01h

(->

MM

O CO CO <:

B XI

U •o 01 NH 00

276
iHo

B

e ij) Q c e

fl •H M iJ

1^ rt O H

co

•H U

4J G

o (V « B

4J 0)

01 i-H o u

<u

to

e c

t«> •H

OJ U

.-1 •H

01 0) a Oa

n s

•o 00 <n u 9B < CN CM r m m p

as X X

<-) U u

n •H M O 4-1 ^-^ O <« m j:

1 m o +

*H •H

<: o j: 0^ 3 u-1

-^ s 3 ^

1

4-t X l-l O 0) iH o.

CO a

<a 0) J " , H

t +

tsl <

(U 0) 01 01 u i-i u )<

<u OJ 01 01

u-l UH M-l 14-4 0) 01 0) 01 a: b: Bi OS

J) rs; •rJ '-a

277
<O <rM

I—<ISI o aXo

>-<< o o

I—

a.

oco Xo

278 I oI ooc

•H

na

0)>O>GO

4J

0)S3

CO0)ua

•rl

•rl rH

•H

cr

(1)

•T3G

(fl

CO

(3O

•HUO

CO

cuuu ^ O -H

•r-) . to rH ^ <r

4-1

QJ CO

C/i

4J

0) to 3 CO 00 •H
1^

CO

G)

II X

<

>

E

o

c\J

CNJ O

O)

o

00

CM

o

D) O

=3. O

o ^

(/I

i_

<

CD

o

II

II

CO

C\J

Figure ^ i . i . <5 Comparison of atomization efficiency curves for trimethylarsine

in a silica-lined graphite furnace with and without hydrogen added to the

carrier gas. Relative GC peak areas are indicated below the curves. Similar results are observed using other furnace surfaces. Above '^1800 on bare graphite, the effect of hydrogen is relatively small since arsenic

is efficiently atomized without Hj.

279
GRAPHITE

in

o

X

en >

:3,

METAL, jjg Figure 41 . 1 . 7calibration curves are compared for trimethylarsine, dimethylselenium and tetramethyltin in a graphite furnace at 1800° with 10% H2

added to carrier gas. Each rectangle shows the results of five consecutive

injections; these data were used to determine detection limits and sensitivity

of the measurement{cf . Table41 . l.^he organometallic gases were introduced

into the GC-GF-AA system as various size injections of a standard gas

mixture in ultrapure N^.

280
FID n

0,4^5

16

" ^^ ^^-Tw^iTi) nx'j*.

0-4 CM

Parameter jump seen at "B"

is' tlie lowest set of spectra

results from a Hg baseline

check made by replacing the

GC effluent stream with a reference air stream in one

of the AA dualbe^ ilS.

r

n

T T T —1

1 1 Figure4l. 2. 1 Simultaneous Simiill chromatograms obtained by a flame ionization

detector (?ID ) and a mercury-specific flameless atomic absorption detector

(AA) are compared for a known, Hg-free calibration mixture of C^,-C^,

paraffins (top) and oil extracts from two sections of a Colgate Creek core. The 0-4 cm sample contained total Hg=0.7yg/g with 45% as extractable Hg,

plus .8% free S": the 10-14 cm sample contained total Hg=0.7vig/g with 26%

as extractable Hg, plus 1.1% free S°. Significantly different retention

times of ca.22 and 36 min. were noted for the ligated mercury effluents.

281
will be the speciation of petroleum (or lipid) bound metals

such as lead, tin, arsenic, and cadmium.

In a trial experiment to determine the presence of methylmercury volatilized from the Chesapeake Bay sediments, the GC

and mercury specific atomic absorption units were installed

aboard the Johns Hopkins Research Vessel Ridgley Warfield.

Evidence for the formation of at least two unidentified

volatile species of mercury (other than Hg°, methyl- and

dimethylmercury) from fresh sediment alone and sediment mixed

with a strain of Pseudomonas, was obtained directly in the

field.

Samples of frozen, unidentified plankton from the Chesapeake

Bay were sent to us for speciation of the incorporated mercury.

Unfortunately, the sample size was too small to permit valid

characterization of the Hg species. In future studies, on

the identification of mercury species in samples of biota, a programmable micropyrolyser , received during this report period,

will be used to pyrolize biological samples on-stream

preliminary to GC-AA analysis, hopefully liberating the

volatile mercurials (or other organometals) from the complex

matrix.

Oyster slime from fresh specimens provided from VIMS, was

found to produce only Hg° from Hg(II). No methylmercury was

detected as had been by Jernelov (Swedish-Finnish Mercury

Symposium, Helsinki, 1967).

A field study was conducted to investigate the effects of

Sn(IV) on the uptake and transport of Hg(II) by water,

sediment, and biota near an underwater habitat (ca 1 mile

from Grand Bahama Island) . This occurred as a result of our

collaboration with VIMS and their working relationship with

NOAA which operates the habitat. Collected samples have

been kept frozen at -80 C° and will be analyzed for tin and

mercury employing the GC-GF-AA facility.

A box- type sediment sampler which permits taking top sections

of undisturbed sediment was purchased. Plans were obtained

for the construction of an underwater sediment gas sampler

and this unit is now under construction in NBS shops. This • combination of refined field samplers will bring a more

sophisticated and reliable approach to the NBS field sampling

program. In particular, it is planned to apply NBS

laboratory GC-GF-AA capability to both determination and

speciation of selected toxic heavy metals transported across

sediment-water interfaces.

282
41.3 Biological Metal Transformations

It has been well established that a number of transformations

of heavy metals can be carried out by microorganisms, chiefly

bacteria and fungi [1,2,3,4,6]. Since these microorganisms

form a major part of the biota in natural environments, an

evaluation of their metal transforming abilities is necessary

to evaluate the potential importance of these activities in

bringing about metal transformations.

41 . 3a Mercury

Employing the GC-AA method, a number of bacterial isolates

from the Chesapeake Bay were found to produce primarily

volatile metallic mercury from Hg(II), but a few demonstrated

a capacity to methylate the metal as well. Utilizing hermetically sealed bioreactors with the GC-AA detection system

[1,3] the effects of aerobic versus anaerobic conditions on

several of the facultative isolates was demonstrated for the

first time to influence the form of mercury transported. Thus

the methylating capacity of these isolates was found to be

associated with anaerobic conditions, whereas the same

organisms could produce only metallic mercury in air.

Bacterial methylation and Hg° formation from Hg(II) by two

strains of the common intestinal bacterium, Esoheriohia aoli^

were demonstrated. These strains have been extensively used

in molecular biological and genetic studies.

41.3b Tin

A mercury- tolerant strain of Pseudomonas , isolated from the

Chesapeake Bay, was demonstrated to also tolerate inorganic

Sn(IV), Sn(II), and Cd(II) salts, as well as a number of

other heavy metal ions [10]. In the presence of Hg(II) salts,

incorporated into Nelson's agar medium (an artificial

estuarine salts solution containing glucose yeast extract,

and hydrolyzed casein) , elemental mercury was produced by

the organism. On this medium containing Sn(IV), the

organism generated a volatile methylated tin species.

Evidence for the formation of the volatile tin species was

based on a spectrofluorimetric technique employing flavinol

as the ligand and on mass spectrometric and atomic

absorption evidence [6,7]. Growth of this mercury-tolerant

strain of Pseudomonas in the presence of both Hg(II) and

Sn(IV) resulted in the formation of methylmercury (Fig. 41.1.1)

A postulated mechanism to account for this novel formation

of methylmercury is

:

283
Sn -> Methyltin species (Biological pathway)

Methyltin species + Hg -^ MeHg (Abiotic reaction)

.

In view of recent data [8,16] indicating a strong correlation

between tin and mercury in river sediments and aquatic

plants, the availability of this information will affect

future models for bimetallic environmental interactions and

urgently suggests new lines for environmental chemistry in the

future.

41.5c Cadmium

A joint NBS-EPA project was initiated in order to assess the

environmental mobility of cadmium in aquatic systems and to

develop means for speciation of important transport species.

The involvement of a natural product, Vitamin B,2, in its

common form as cyanocobalamin, has been shown to provide

specific stimulation to the same metal-resistant marine

bacterial isolate resulting in volatilization of cadmium

from its inorganic salts [14]. The experiments have been

controlled in a number of ways which verify the need for the

microorganism, Pseudomonas sp^ plus Cd and the cobalamin in

a well-established laboratory estuarine salts nutrient

medium (Figure 41. 3.1). No cadmium is detectable (-0.01 ng

level) in a sterile water absorbing solution separated from

the growth medium, if either the bacteria or cobalamin are

deleted from the experiment. The form of the volatilized

cadmium species is presently unknown. In model abiotic

experiments, it was shown that although highly reactive

gaseous Me^Cd is mainly decomposed by water to methane and

hydrated CaO, sufficient Me-Cd bonds persist which can

methylate HgCl2 contained in the water absorption solution

at ppm levels. In the bacterial Cd volatilization experiment,

use of Hg in the absorbing solution does yield Me-Hg products,

While a Me-Cd metabolite might be inferred from present

evidence, detailed examination of the relative amounts of

cadmium and "methylator" volatilized into the absorption

solution compartment suggests that these are more likely

coincident processes, and that there may be a significant

abiotic reaction also responsible for the substantial excess

of methylator over Cd produced. The work specifically concerned with the bacterial volatilization of cadmium is near

completion and a preliminary manuscript has been written [14J

.

The work concerned with the production of "methylator", by

either bacterial and/or abiotic pathways, is continuing with

special emphasis on the general methylating capability of the

volatile species towards a number of heavy metal ions [2,7]

284
Hr. „. . Figure 41. J. 1 Cadmium volatilization by Pseudomonas sp(Ps)grown on

Nelson's medium(N) doped with SppmCdCl, (Cd) is demonstrated by accumulation of transported Cd material in a separate water absorbing

solution as a function of time. Compared against positive controls,

the process is stimulated by presence of 2.5ppm cyanocobalamin (B. . ) curv

0| whereas the system Ps+N+Cd (curved) alone shows little Cd transport.

Additional controls testing for abiotic Cd volatilization in N+Cd+B. „ only

(0),or for adventitious Cd contamination with Ps+N+B.^ (0)» indicate

that only the B -stimulated process is significant. TRe error bars depicted

in the top curve apply to all four curves shown, and indicate the average

deviation (± 4%) between two completely independent runs for the foursystem sets described. The fall-off of Cd concentration in the absorbing

solution after one day reflects a maximum growth/volatilization by the

microorganism, combined with the known "plating out" of trace aqueous

Cd species on glass container walls.

285
commonly found in sediment or sewage sludge sites. Since

cobalamins are common biproducts in such sludge matrices,

expected results from this line of work can yield important

information regarding the potential volatilization of a number

of metals well known to accumulate in such environments [5,8].

41.4 Abiotic Metal Transformations

Two other important factors responsible for the conversion of

heavy metals into organometals are ligand interactions and

photochemical processes. An initial effort has been made to

evaluate the potential importance of these factors in bringing

about metal transformations.

Examples have now appeared in the literature which show the

occurrence of metal transformations in aqueous solution [8]

including a wide range of transmethylation reactions between

heavy metal ions [7]. On the one hand, the known cellular

metabolite, methylcobalamin, has been shown to transfer with

ease its methyl group to mercuric ion in aqueous solution to

form the highly neurotoxic methylmercury ion [171. In

another study [18]. Jernelov, et al. ^ have implicated

anthropogenic alkyllead discharges in the formation of high

methylmercury concentrations in St. Clair River sediments.

Hence we have an example of methylation also occurring

environmentally in apparently a straightforward metathetical

reaction.

41.4a Photochemical Reactions

Work has also been advanced in the area of photochemistry.

For example, a methylchromium bond has been formed in the

photolysis of tertiary-butoxy radicals and chromium(II) in

aqueous solution [19]. It was also found that in the

presence of acetate ion or acetic acid in aqueous solution,

Hg was photolyzed in sunlight to form a methylmercury bond

[20]. We have examined this latter reaction and similar

ones [7]. These last reactions are consistent with early

findings [21] that (RC02)2Hg compounds decompose in protic

organic solvents under ultraviolet irradiation to yield

alkyl-mercurials, RHg(OCOR).

A survey of the photolysis of acetate ion in the presence of

other metal ions has also been initiated. Among other

metals, thallium was selected for initial study because of

the recent demonstration of its bacterial utilization and

transport [22]. Thallium(I) shows evidence of involvement

in a photolytic process similar to that seen for Hg(II).

Thus, when thallium(I) acetate is irradiated a decrease in

acetate concentration occurs; however, if a solution of

sodium acetate is similarly irradiated, no diminution of

286
acetate concentration is observed over the same period of

time. Also, as with the case for Hg, continued irradiation

of T1(I) acetate finally produces free metal, along with

gaseous products, including methane which might result from

intermediate methylthallium(I) formation.

Two important factors emerge from these results: (1) presence

of a metal cation capable of appropriate (possibly bidentate)

coordination of the acetate moiety may be necessary for

effective photoalkylation to occur; and (2) possible formation

of a transient methylthallium(I) species, similar to those

reaction intermediates reported for Pd(II) and Pt(II) forms

but rapidly decomposes to observed products [7].

41.4b Mercury

2 + In order to investigate the abiotic methylation of Hg in

water, the effect of ligands on reaction rate was studied.

It had been previously determined that Me^Sn"*" undergoes loss

of one methyl group to quantitatively form MeHg+ from aquoHg as shown by equation (1) [2,7].

A major portion of the basic kinetic data required for assessing the influence of key environmental parameters of rates

of transmethylation between organotin species and Hg(II)

species has been completed [15] . Present_results show that,

both specific ligand (e.g-.jCl but not NO^ or CIO.) and total

ionic strength effects dominate the bimolecular rate law

describing the reaction

Me^Sn"*" + Hg^"^ - -^? ^

Me2Sn^"^ + MeHg"" (1)

and that the earlier demonstrated [7] low activation energy

for the transmethylation (14 Kcal) results from reaction of

dissimilarly charged metal species in the transition state

(Figure 41.4.1). These results are also consistent with the

maximum rate for Me transfer observed at chloride_ion

concentrations yielding maximum formation of HgCl,, as

calculated from available formation constant data (Figure

41.4.2), The importance of other solvents on this model

reaction was also evaluated. Inasmuch as available

literature does not usually consider pure water as reaction

medium, an understanding of relative contributions of various

solvent parameters is necessary for developing a mechanistic

picture for the aqueous model reaction and its extension

to other metal cases.

Basically, the rate of the bimolecular process above (k2)

depends mainly on the mole fraction of water available m

any miscible organic solvent. Indeed, without water present,

no reaction is observed, suggesting a critical involvement of

287
-1.9-1

-2.1-

CIO4

-2.3-

01

O

^^Q

Sw a

N

'XX

\

2.57/-

4.1-

\

-4.3-

^

0.2 0.4

nHT

0.6 0.8 1.0

Figure41.4.1 The rate of methylation of mercuric ion by trimethyltin ion

in water (expressed as log k.) is comgared at_various total ionic strengths

(u) and with specific gegenions (0"C1 ;S=CloT).At nearly constant low y

(i/^M).3) the methylation rate is dominated" by salinity (eg.^=Cl ) and

substitution of supporting gegenions such asNOl ,C10~ show no significant

effect on this rate. Increasing ionic strength with an "inert" gegenion

such as CIO.TS) reduces the rate of transmethylation, but not as severely as with increasing CI (0). The negative slopes seen for >^>0.4

indicate that molecular species of dissimilar charge are involved in the

transition state.

288
100-

80-

60-1 a o

»

20

I I I » I 1.6 1.4 l.a 1.0 .8 —I— .4 .a pCl

Figure 41.4.2 /\t the chloride ion concentrations (pCl) shown^ the above MERCURY species ARE EXPECTED TO OCCUR. ALTHOUGH FOURTEEN CHLORO" OR HYDROXYCHLORO-MERCURY COMPLEXES CAN EXIST AND THEIR RELATIVE ABUNDANCES

ARE DETERMINED BY THE MODIFIED COMPUTER PROGRAM, THE THREE CHLORO-Hg

SPECIES SHOWN REPRESENT OVER 99Z OF TOTAL MERCURY PRESENT. No CHLOROHYDROXY- OR HYDROXY-MERCURY SPECIES AT ANY SIGNIFICANT CONCENTRATION

ARE INDICATED IN THE CONDITIONS EMPLOYED BY THE PRESENT STUDY.

289
water in the ionic transition state. This aspect is now under

study by use of the kinetic isotope effect of trace amounts

of D2O versus H^O in an "inert diluent" organic solvent. The

ultimate goal of the present work relates to providing a model case for understanding the factors influencing transformations of known organometallic metabolites as these are

transported and are transformed by passage across lipid-water

interfaces

.

41.4c Arsenic and Antimony

The chemical changes which facilitate the movement of

arsenic and antimony from one subsystem of the biosphere to

another were investigated. One of the more important

processes in arsenic mobilization has been shown to be the

reduction and methylation of inorganic arsenic compounds by

microorganisms to produce trimethyl- and dimethylarsine

[23,24,25]. At this time, it has not been demonstrated that

methylstibines are metabolites of microorganisms acting on

inorganic antimony compounds, but the extensive similarity of

the chemistry of arsenic and antimony gives reason to believe

the antimony can be biologically methylated.

Methyl-arsines and stibines are subject to a number of

reactions such as oxidation, quaternization and complex

formation which could facilitate or inhibit their dispersal

in the environment as well as mobility within organisms.

Limited quantitative information, however, has been available

to aid in assessing such redistribution possibilities. Our

current efforts were devoted to establishing such a chemical

data base.

Two studies on this topic have now been completed: Part I,

"Quaternization of trimethylarsine and trimethylstibine" [9

J

and Part II, "Oxidation of Trimethylarsine and Trimethylstibine"

[11]. In Part I, it was shown that the reactions of Me^As

and Me,Sb with a variety of alkyl halides in methanol and

in acetonitrile followed second-order kinetics and for that

and other evidence, appeared to be a S^ type reaction. Twelve » reactions were studied quantitatively and their reaction ' rates allowed the following order of nucleophilic reactivity

to be established:

Me^As > pyridine > Me^Sb.

In Part II, this difficult problem of obtaining qualitative

and semi-quantitative data on the reaction of Me^As and

Me-,Sb with molecular (atmospheric) oxygen in methanol

solution and in the gas phase was examined. Figure 41.4.3]

shows the qualitative observations made, using proton

nuclear magnetic resonance spectroscopy (PMR) , when

290
'igure 41.4.3 Competitive oxidation of trimethylstibine and trimethvlarsinp

<iXe esiauiined by proton nuclear magnetic resonance spectrometry. Snectnim

A, unexposed samples with AstSb, 1.0:0.8. Spectrum B

and B' , after 50 min. exposure ,show that even though

the initial amount of (CH-) Sb was less than the initia]

amount of (CH-)-As, the total (CH^) Sb oxidation

products are at least three times more abundant than

the total (CH_)-As oxidation products. Spectrum C, after

250 min. shows that more than half the (CH-)„Sb has beer

oxidizied while only a few percent of the fcH_)„As has

been oxidized. The methyl-proton signals in Spectrum C are labeled according to our tentative identification

of products which, except for (CH^) SbO and (CH ) AsO

(R =CH^) , are not unequivocally established.

mSfmJ\MMiJ V*,,,ywH.wt»rt(iMM^v^

LAAs

zo LO

291
Me_Sb in methanol solution was allowed to react with infusing

atmospheric oxygen. The principle product was trimethylstibine

oxide (-801 yield) with about 20% of the antimony being

accounted for as insoluble (unobserved by PMR) dimethylstibinic

acid. A transient signal in the PMR spectra was due to an

intermediate in the formation of the stibinic acid.

Qualitatively, the reaction of Me-As is very similar except

that dimethylarsine analog (cacodylic acid) is stable. Semiquantitative rate constants for these oxidations were deduced

assuming that the reactions are first order in O2 and

Me^As or Me,Sb.

In general, Me^As reacts quite slowly and can move long

distances in air or oxygenated water without change, whereas

Me,Sb reacts very rapidly with O2 in both the gas and liquid

phases. We generally conclude tnat while volatile metabolic

trimethylarsine can be expected to survive atmospheric

oxidation for substantial periods of time, similar transport

potential for Me^Sb is not likely, and it is presumed that any

microbial process involving methylation of Sb will not result

in its volatilization as with As and some other toxic heavy

metals

.

41. 4d Qrganotin Compounds

The study of specific organotin molecules released from antifouling formulations (joint NBS-NSRDL Project) has focused on

two primary approaches: (1) molecular characterization of

organotin species leached into aquatic environments and (2) a study of their subsequent modification at trace (micro- or

nanogram) levels in natural environments.

In preliminary studies employing usual AA graphite furnace

and GC parameters [12jl3] no significant curvature or nonlinearity was evident for calibration of volatile methyltin

species from water solutions in the 1-5 ng range. A

significantly different sensitivity or response was obtained

for various inorganic tin solutions in the 1-5 ng range which

appeared to follow expected ease of atomization based on

the oxidation state or facile thermal cleavage of organotin

bonds [13] (Figure 41.4.4).

Extension of this approach to speciation of several other

trace organotins in aqueous samples is partially attained,

but highly dependent on partition coefficients of the

original analyte or a modified volatile derivative. A

number of unresolved factors are also involved, including

variable atomization efficiencies of aquated tin species and

influence of container materials on the stability of

calibration solutions containing trace quantities of organotins . 292
0.8

0.6-

*2 0-4

S 0.2-

MesSnCI

Sn (ng)

Figure 41. 4. AAA calibration curves of five tin compounds. Greater atomization

efficiency (response) is indicated for Sn (IV) species as opposed to

Sn (II) ions.

293
41.5 Electrochemistry of Trace Organometals in Aqueous Media

A collaborative effort in this topic area was recently begun

for the following reasons:

a) Basic mechanism and rate data are required

for elucidation of many chemical or biological

steps which involve redox of metal sites bound

to organic liquids; toxic methylarsenicals

provide an important example as is illustrated

in Figure 41.5.1.

b) Potential for developing an independent

electroanalytic chemistry for certain

organometallic species of environmental

concern, e.g., methylmercury ion.

c) Evaluation of additional certification

methods required for development of an

SRM for trace (ppb) methylmercury in

water.

41.5a Progress to Date: Methylmercury

In collaboration with Dr. Richard M. Durst (310.05), a preliminary survey of the electrochemistry of methylmercury

ion with a member of gegenions has been initiated employing

principally cyclic voltammetry. Prof. John E. Doody {of.

Section 41.7 is also actively collaborating in the program

during the summer of 1976.

41.5b Other Organometals

Electrochemistry of several methylarsenicals and organotin

compounds will be surveyed utilizing cyclic voltammetry,

the model compounds have now been synthesized and purified.

41 .6 Workshop on Microbial Transformations of Heavy Metals

A workshop on Microbial Transformations of Heavy Metals was

organized and conducted at NBS on May 10-11, 1976. The

objective of this Workshop was primarily to provide a better"

means of communication among workers in this area than had

hitherto been possible at the International Conference held

over the past several years. Other objectives would be to

permit a better understanding of the progress made in these

areas, and to envision areas when significant gaps were

missing in understanding the overall significance of heavy

metals transformations by microorganisms in the environment.

294
(/)

LJH

COzOQOOU

O

CO

•HG

(U

CQM

COO

CiCO&0

VIoo

•HO

4J

}-) o

H-f

cd

u

4J CO CO (U

d),

u o

•u ca O bO

&, cu

CO -u

cd CO •H cd

4-1 C

(U 4Jo

V< 4J

CO

295

B

4-1 0) O rCo

(UX

.H

O 6 <U

CO ^^o

in

g

rH >> U -H 3

C50 •H
There were about 32 people in attendance including 18 invited

participants. The three main areas of discussion were: (1)

techniques for detection and speciation of volatile heavy

metals, (2) bacterial transformation of heavy metals and (3)

extrachromosome elements as determination in metal tolerance

and metal transformations of bacteria.

41.7 NBS-NSF Faculty Participation Research Program

The NBS was awarded funds by NSF sufficient to support two

senior academicians for the summer of 1976.

41.7a Objective and Mechanism '

The NSF program of Faculty Research Participation provides

opportunities for academic faculty to participate in

industrial research activities. The purpose of providing

this experience in research on problems on national interest

and concern is to encourage and assist teachers in reevaluating the relevance of their course materials to the

needs of students being prepared for applying the results

of their education in the national society.

In the program, a research facility proposes to the National

Science Foundation to offer selected academic faculty

opportunities to participate for ten weeks during the summer

in the ongoing research activities of the facility. The

projects available during the summer are announced to the

academic community in the preceding spring. Interested

faculty then apply for participation directly to the facility.

The participants in a project are selected by the research

facility from the applications submitted to it.

The research opportunities or problems are specified by the

facility. They are to be immediately relevant to the

interests and concerns for which the facility is maintained,

amenable to a valid and effective application of scientific

method, and appropriate to the conditions of support provided

by the Faculty Research Participation Program, and to its

goals. The project plan provides for the faculty to work

as resident participants in ongoing research activities of the

facility.

41.7b NBS Summer Participation Projects

Three separate but parallel topic areas were made available

for study by senior workers under the auspices of the NSF

Faculty Research Participation Program. These represented

the main disciplinary concerns which provide impetus to the

overall NBS project, and which from appropriate new academic

experience can play an immediate role in advancing our work.

296
Conventional laboratory facilities and instrumentation were

already available for successful faculty participants, and a

number of special manipulative and detection systems for the

biotransformation studies are also available.

The topic areas listed reflect distinct academic experience

and interest. They overlap to a substantial degree, depending

on individual persuasion and availability, but are set out

separately in order to better define the range of interest

within the NBS project on Environmental Metals Transformations:

Abiotic Transmethylation Reactions of Heavy Metals in

Aquatic Systems - represents our continuing interest in

extending the descriptive organometallic chemistry of aquated

heavy metal ions in water and related protic media.

Biotransformations of Heavy Metals in the Environment - involves the ongoing interdivision program which combines NBS

expertise in microbial corrosion and inorganic chemistry. The

work is directed to active field studies providing bacterial

isolates and representative biological matrices for

laboratory investigation of metal transport and speciation.

Speciation of Trace Organometallics in the Environment - draws on NBS interests and expertise in advancing analytical

and characterization methodology. While not viewed principally

as an analytical effort, academic interest in those areas

concerned with trace determinations of metal-containing

molecules derived from, or within, biological matrices will

offer considerable support to the overall project.

41.7c Selection NBS-NSF Faculty Participants

Following announcement of the joint NBS-NSF project, a substantial number of applications were received. Among 14

eligible applicants, two were selected: Professor John E.

Doody, F.S.C. Christian Brothers College, Memphis, Tenn.--

to conduct research on speciation and electroanalytical

investigation on toxic organometallic compounds in aqueous

media. Professor J. M. Bellama, University of Maryland,

College Park, MD--to study the possible transfer of alkyl

(methyl) groups from methyl silicones, and model trimethylsilyl compounds similar to such industrial materials, to

other metal species in order to establish potential for

environmental hazards.

Both recipients of the NBS-NSF award have been appointed as

NBS Guest Workers in order to provide continuity for

completing publication of their research following the 10-

week contact period.

297
REFERENCES

[1] Nelson, J. D. ,- Blair, W. , Brinckman, F. E., Colwell,

R. R. , Iverson, W. P., Biodegradation o£ Phenylmercuric

Acetate by Mercury-Resistant Bacteria, Applied

MioTobiology 3 26^, #3, 321-326, 1973.

[2] Jewett, _K. L., Brinckman, F. W. , Transmethylation of

Heavy Metal Ions in Water, Div. o£ Environmental

Chemistry, ACS, 167th National Meeting, CA, 1974.

Preprints of Papers, 1£, 218-225.

[3] Blair, W. R. , Iverson, W. P., Brinckman, F. E.,

Application of a Gas Chromatograph- -Atomic Absorption

Detection System to a Survey of Mercury Transformations

by Chesapeake Bay, Miaroorganisms Chemo sphere^ 3_, #4,

167-174, 1974.

[4] Iverson, W. P., Blair, W. , Huey, C, Brinckman, F. E.,

Jewett, K. L., Biological and Non-biological Transformations of Mercury in Aquatic Systems, ed. , Krenkel:

Progress in ]flatev Teohnology ^ 7_, 193-195 (Supplement),

1974.

[5] Brinckman, F. E., Jewett, K. L. , Blair, W. R. , Iverson,

W. P., and Huey, C, Mercury Distribution in the

Chesapeake Bay, ed. Krenkel: Progress in Water

Technology y 7_, 251-252, (Supplement), 1974.

[6] Huey, C, Brinckman, F. E., Grim, S., Iverson, W. P.,

The Role of Tin in Bacterial Methylation of Mercury,

Proa, of the Inter. Conf. on Transport of Persistent

Chemicals in Aquatic Ecosystems ^ Canada, pp. 11-73-78,

1974.

[7] Jewett, K. L., Brinckman, F. E., Bellama, J. M.

,

Chemical Factors Influencing Metal Alkylation in Water,

ed. T. Church, ACS Symposium Series^ No. 18 pp.

304-318, 1975.

[8] Brinckman, F. E., Iverson, W. P., Chemical and Bacterial

Cycling of Heavy Metals in the Estuarine System, ed.

T. Church, ACS Symposium Series^ No. 18 pp. 319-342,

1975.

[9] Parris, G. E. , Brinckman, F. E., Reactions which Relate

to the Environmental Mobility of Arsenic and Antimony

I Quaternization of Trimethylarsine and Trimethylstibine,

J. Org. Chem., 40, 3801, 1975.

298 I
[10] Huey, C. W. , Biotransformations of Metals^ Ph.D.

Dissertation, University of Maryland, 1975.

[11] Parris, G. E. and Brinckman, F. E., Reactions which

Relate to the Environmental Mobility of Arsenic and

Antimony: II. Oxidation of Trimethylarsine and

Trimethylstibine, Environ. Soi. Teahnol^ (1976) in

press.

[12] Brinckman, F. E. , Iverson, W. P., and Blair, W. R.

,

Approaches to the Study of Microbial Transformations

of Metals, (Proc. 3rd Internat. Biodegradation Sympos .

,

eds : Sharpley and Kaplan, Biodeterioration of

Matl's, 3, (1976), 919-936.

[13] Parris, G. E., Blair, W. R. , and Brinckman, F. E.,

Chemical and Physical Considerations in the Use of

Atomic Absorption Detectors Coupled with a Gas

Chromatograph for Determination of Trace Organometallic Compounds, in preparation.

[14] Huey, C. W. , Brinckman, F. E., Iverson, W. P., and

Grim, S. 0., Bacterial Volatilization of Cadmium,

in preparation.

[15] Jewett, K. L., Brinckman, F. E. , and Bellama, J. M.

,

Factors Influencing Metal Alkylation in Water, in

preparation.

[16] Schromel, P., Samsake, K. , and Parker, J., Soa. J.

Envir. Sai., 5, 37-40 (1933).

[17] Agnes, G., Bendle, S., Hill, H. 0. A., Williams, F. R.

and Williams, R. J. P., Chem. Comm. (171), 850-851.

[18] Jernelov, A., Lann, H. , Wennergren, G., Fagerstrom, T.,

Asell, B., and Andersson, R. , "Analyses of Methylmercury Concentration in Sediment from the St. Clair

System," unpublished report of the Swedish Water and

Air Pollution Research Laboratory (in English)

,

(1972), 17 pp.

[19] Ardon, M., Woolmington, K. , and Pernick, A., Inorg.

Chem, (1971) 10_, 2812.

[20] Agaki, H. and Takabatake, E., Chemosphere (1973),

3, 131-133.

[21] Razuvaev, G. A. and Ol'deleop, Y. A., Doklady Akad.

Nauk USSR (1955), 10_5, 738-740.

299
[22] Schneiderman, G. S., Garland, T. R. , Wilding, R. E.,

and Prucker, H. , Abstv. Ann. netting Amer. Soo.

Microbiol. (1974).

[23] Challenger, F., Chem. Rev., 36, 315 (1945).

[24] Perlman, D., Microbial Production of Metal-Organic

Compounds and Complexes in Advances in Applied

Microbiology 3 edited by W. W.Umbreit, Academic

Press, New York (1965), pp. 103-109.

[25] Wood, J. M., Science, 183, 1049 (1974).

300
42. Heavy Mftt^^JLSpecjLaJiiim

Project Leader: Richard A. Durst, Analytical Chemistry

Division

Approach

Heavy metal elements such as cadmium, lead and copper undergo

extensive chemical and biochemical modifications when released

into the environment. In natural waters, the metals may

exist simultaneously in a variety of forms including free ions,

complexes, particulates, and organometallic compounds. Since

it has been demonstrated that there is a close relationship

between toxicity and speciation, the determination of the

forms of the metals is at least as important as the total

concentration. Because the analytical techniques

conventionally used for the measurement of trace heavy metals

require sample pretreatment operations which destroy the

various forms present, few data are available on the very

important question of heavy metal speciation in natural waters.

Electroanalytica

convenient means

without the need

by virtue of the

and sensitivity

the metal ions,

anodic stripping

potentiometry wi

cadmium, and lea

work will progre

I techniques can provide a unique and

for performing speciation analyses in situ

for preconcentration or chemical pretreatment,

ir high analytical sensitivity, selectivity,

to complex formation and oxidation states of

Accordingly, the techniques of polarography

,

voltammetry, and ion-selective electrode

II be applied to the elucidation of copper,

d speciation in various natural waters. This

ss along several lines of research including:

301
sampling and sample storage, evaluation of techniques, gross

sample characterization, speciation by chemical and

instrumental differentiation, equilibria and kinetics studies,

effects of ambient environmental conditions, intercomparison

of natural waters, and bioreactor studies of the distribution

of heavy metals between the solution, sediment, and biota.

The development of the techniques and studies of the type

noted above will help provide the data necessary to set

realistic toxicity standards and the means to monitor the

natural waters for specified toxic species.

Progress

The evaluation of voltammetric techniques has been initiated

using the P.A.R. Model 170 Electrochemistry System to provide

the various functional modes required for this study. This

system, which is new, has been set up to perform experiments

in polarography and stripping voltammetry, using a classical

dropping mercury electrode (DME) , a rotating glassy carbon

electrode (RGCE) , or a hanging mercury drop electrode (HMDE)

.

As part of the overall system, a special gas mixing manifold

has been constructed in this laboratory to provide precisely

blended carbon dioxide-nitrogen mixtures for the dual purpose

of deaeration and pH control of the sample. By means of flow

meters and differential flow regulators, it is possible to

accurately control the amount of CO2 in N2 at any value between

and 100 percent and the flow rate up to 200 cm /min.

Although some of the initial testing was performed using the

DME, and this electrode may be used in future work with the \

differential pulse mode of operation, this mode is not

functioning properly on the present instrument and further

work with differential pulse polarography must await repairs

to the instrument. The most recent work has involved

optimizing the operational parameters for performing anodic

stripping voltammetry (ASV) with the RGCE and in situ

plating of a thin film of mercury on the glassy carbon.

Although ASV can be performed using differential pulse

stripping for maximum sensitivity, the present evaluation

work has concentrated on conventional linear d.c. scan stripping

302
Using millimolar sodium carbonate and millimolar sodium

acetate supporting electrolytes (which were purified by

continuous controlled-potential electrolysis), it has been

possible to determine 0.5 ppb of copper, cadmium, and lead

in synthetic solutions. These levels are consistent with those

anticipated in the natural samples to be studied in the future.

The peaks obtained for these three elements are completely resolved by this technique (see Figure 42.1). Although there is

no problem in terms of sensitivity and selectivity with the

synthetic solutions under study, matrix effects in the natural

samples may pose problems in terms of interferences and longterm stability of the samples.

Most of the recent work has involved evaluation of the

precision of the ASV method when using two different types of

working electrode: the thin mercury film glassy carbon

electrode (TMFGCE) plated in situ and the hanging mercury

drop electrode (HMDE) . Although the TMFGCE has the advantages

of higher sensitivity and resolution, it suffers from two

serious disadvantages. First, plating in situ requires

spiking the sample solution to about 10"5 M in mercuric ion

which would upset trace metal equilibria in an actual environmental sample, and also poison heavy metal ion-selective

electrodes used in simultaneous measurements. Second, the

presence of the glassy carbon substrate requires multiple

plate/strip cycles in order to obtain reproducible results.

This is a reflection of variations in the thin film caused

by incomplete stripping of the mercury film between scans.

Por the work planned, it appears that the TMFGCE is not

suitable and, in the absence of the differential pulse mode,

only d.c. ASV with the HMDE will be applicable, although

its limited sensitivity may not be sufficient for the lowest

heavy metal concentrations encountered.

During this period, attention has been focussed on two

heavy metals: cadmium and mercury. Calibration curves

developed for the cadmium ion-selective electrode have

demonstrated its utility to less than 100 ppb of cadmium. In

the 10-100 ppb range, the electrode response is highly

dependent on the electrode conditioning procedure, which is

currently being optimized.

303
Because of the enhanced toxicity of mercury as organomercurials

,

especially methylmercury, electrochemical methods were applied

to the quantitation of the compound. Initially, cyclic voltammetry (CV) was used to observe the overall redox behavior.

During this study, a previously unreported reduction (or

adsorption) peak was observed during the anodic cycle of the

scan (see Figure 42.2). This observation, along with other

unreported fine structure in the cyclic voltammograms , may

provide new insights into the mechanisms of mercury transformations .

Using a P.A.R. Model 174 polarograph in the differential

pulse mode, the first reduction wave of methylmercury was

quantified by a standard addition procedure. Linear response

was observed over the concentration range from 60 to 900 ppb

.

It is anticipated that the detection limit can be further

reduced to 10 ppb or less.

In preparation for studies of complexation by natural

substances, two commercial samples of humic acid were obtained.

Saturated solutions were prepared and the resulting mixtures

characterized by sedimentation. One sample separated into

two layers (a light-brown colloidal solution phase and a dark-brown sediment) in one day, while the other sample

sedimented into several layers after two days and into the

two final layers (as above) after more than three days. From

this simple experiment, it is clear that considerable

differences exist in humic acids depending on their source

and method of preparation. It was also found that for both

of these samples the soluble (fulvic acid) and colloidal

fraction represented a concentration of 0.15 +_ .02 percent

by weight.

Future studies of cadmium- fulvic acid complexation will be

performed under controlled conditions in which the alkalinity

and pH are fixed by NaHCO- solutions equilibrated with CO^/N, mixtures in order to first measure hydroxide and carbonate

complexation. The interactions of cadmium and fulvic acid

will then be monitored by means of the ion-selective electrode

and differential pulse polarography.

304
o

+

COa O

+

O

+

O

+

oI

<

-5t

Figure 42.1 Anodic Stripping Voltammetry of cadmium, lead and

copper from a thin mercury film glassy carbon efLectrode plated

in situ. Curve 1: blank containing lyM HgN03. Curve 2: Ippb % ^

Cd#,Pb#,Cu#(lyM Hg#). Allsolutions contain lyM Na^CO adjustea co O

pH=5.05 by C0_/N„ gas mixtures. Deposition time 5 mln. on rotating GCE (650 rpm) . Stripping scan rate: 50 mV/s.

305
CHsHgCI

5 ppm 0.1 MA

200 mV/s A

I

V vs. SCE

Figure 42.2 Cyclic Voltammetry of methyImercury chloride. Cathodic scan

shows two reduction peaks at -0.6 and -1.4 V. Anodic scan at 50mV/s shows

an anomalous reduction peak at -1.3 V which disappears at 200mV/s.

306
43. Development of Reference Materials for Sediment Analysis

Project Leader: John K. Taylor, Analytical Chemistry Division

Other Personnel: Harry Rook, E. R. Deardorff, M. Darr, and

W. P. Schmidt

Objective

The objective of this project is to develop and characterize

reference standards for the chemical analysis of sediment

materials in the beds of rivers, lakes, and harbors. The

reliability of the chemical analysis of sediments from

bodies of water, required for environmental impact studies

for example, is unknown. Discordant results are partly due

to sampling problems as well as to analytical uncertainties.

Concern about this situation by many analysts and especially

by EPA, has prompted the latter to sponsor a project at NBS

to provide reference standards. The availability of such

standards will make possible the evaluation of methods used

for the analysis of key substances, and stimulate the development of new techniques where existing ones are inadequate.

Above all, the standards should verify the accuracy of

analytical values obtained for environmental impact studies

used for the basis of environmental decisions and minimize

controversy presently based on discrepancies in analytical

data. While initially intended to help EPA in its regulatory

problems, the materials are expected to ultimately appear as

Standard Reference Materials, for use both as quality control

purposes and as general reference materials for analytical

research and development.

307
Approach

A series of sediments will be obtained from typical locations--

rivers, lakes, harbors --homogenized and their stability

studied under storage conditions. Materials of most suitable

composition will be selected, in consultation with EPA and

analyzed by state-of-the-art procedures for such components

as toxic metals, nutrients, and a variety of organic compounds.

Progress

Work during Fiscal Year 1974, concerned with examination of

candidate sediments, provided the basis for selection of the

Indiana Harbor Canal as the site for collection of the

large amount of material for use as reference standard. A

large quantity of sediment (approximately 2500 lb ) was

collected by means of a clam-shell dredge. A preliminary

screening was done to remove foreign objects.

The screened material was freeze-dried under contract by a commercial processor prior to delivery to NBS. The material

was then radiation sterilized as a precautionary measure.

Preliminary studies indicated that homogeneity would be

facilitated by sieving through a 80-mesh screen. This was

done and the material so treated was accepted as the sample.

This was extensively mixed in a V-blender before bottling.

The material was then packaged to obtain 5000 bottles, each

containing 80 g of sediment.

Initial homogeneity studies were made on the blended material

by neutron activation analysis and by measurement of the

chemical oxygen demand (dichromate method) but the major

investigation was done after bottling. A statistical sampling

of 30 bottles from the lot was used for measurement of the

following parameters: chemical oxygen demand; loss on

ignition; total phosphorous; Kjeldahl nitrogen; heavy metals

by x-ray fluorescence measurement. These measurements indicate

that these and other parameters are not expected to vary more

than 2 percent between bottles, making the material adequate

for the intended purpose.

Certification analyses have been initiated for issuing the

material as a Standard Reference Material. The analytical work

is substantially complete and the material is expected to

be issued as SRM #1645, River Sediment on or about January 1,

1977. The development of additional sediment reference

materials, including a marine sediment, is under consideration.

In the meantime, 2500 bottles of the material have been

delivered to EPA for use by them in method evaluation studies.

Publications

[1]. Taylor, J.K. and Rook, H.L., Development of a Reference

Material for Sediment Analysis. Puhl. 208 (1975).

308
44. Development of Precipitation Standards

Project Leader: J. K.

Other Personnel: E. R.

T. C.

Taylor, Analytical Chemistry Division

Deardorff, R. A. Durst, E. J. Maienthal,

Rains, and E. P. Scheide

Objective

The chemical composition of atmospheric precipitation (e.g.,

rainwater) is an important indicator of pollution levels.

The analysis of precipitation must be done on a global scale

and by use of techniques which are presently not standardized.

At the request of EPA, and under their sponsorship, NBS

initiated a project to develop reference materials that could

be used to evaluate the various methods presently in use for

this purpose, and to serve as quality control materials for

data collected in global monitoring programs.

Approach

Dilute solutions containing 10 commonly occurring metallic

elements and 5 anions associated with them were prepared in

such concentrations that, on dilution with pure water, they

would simulate the full range of concentrations found in

atmospheric samples. A series of 4 samples were utilized

for this purpose. After initial studies of stability and

compatibility of components, the samples were prepared in

bulk and sealed in individual ampoules for subsequent

dilution at time of use. The most accurate analytical

techniques presently available were used to certify their

composition and to attest the homogeneity between individual

samples. In addition two "blind samples" were prepared in a similar manner for use by the World Meteorological Organization

in a quality control program.

Progress

This project was completed during Fiscal Year 1976. The

reference materials were prepared in concentrations such that

a 50-fold dilution would produce solutions simulating the

composition of natural rainwater. Four levels were prepared

to cover the range found in various locations. The complexity

of precipitation analysis is evident from inspection of the

number of components and the concentration levels involved:

309
Constituent, ionic Range, mg/l

Sulfate 1-10

Nitrate, Fluoride, Chloride 0.1-18

Ammonium, Sodium 0.1- 5

Potassium 0.1- 3

Calcium, Magnesium 0.1- 3

Zinc, Cadmium, Copper

Nickel, Lead, Manganese 0.02-1

The solutions were prepared in bulk by dissolving the pure

salts in water. They were sealed in 10 ml ampoules using the

automatic filling equipment of the NBS Office of Standard

Reference Materials. In use, the samples will be quantitatively diluted to 500 ml to prepare reference samples at

the indicated concentration levels.

While the concentrations are expected to be stable for a limited time, neither their long-term stability nor the

stability of the diluted solutions is presently known.

Accordingly, samples from the productions lot have been

retained and will be analyzed periodically to answer such

questions which are important if Standard Reference Materials

of this kind are considered.

Three hundred ampoules were prepared at each of three levels

and five hundred were prepared at a fourth concentration

level. The original bulk solutions were analyzed and

statistically selected ampoules from the production lot were

also measured.

Publications

[1]. Taylor, J.K., Deardorff, E.R., Durst, R.A. , Maienthal,

E.J., Rains, T.C. and Schiede, E.P., Simulated Precipitation

Reference Materials, NBSIR 75-968 (1975) .

310
45 . Mixed Heavy Metals in Water SRM

Project Leader: I. L. Barnes, Analytical Chemistry Division

Other Personnel: B. I. Diamondstone, E. L. Garner, J. W.

Gramlich, J. R. Moody, T. J. Murphy, P. J.

Paulsen, T. C. Rains, and H. L. Rook

Objective

To determine stability of mixed heavy metals in acidified

water and to investigate methods for certification of at

least ten elements at the ng/g concentration level.

Approach

A solution of ten mixed heavy metals in . 5N nitric acid

solution was to be analyzed during the first week after

preparation and at 6 and 16 week intervals. The concentration of these elements was selected to be at the upper limit

of the proposed EPA standard. The techniques to be used were

neutron activation analysis, atomic absorption spectrophotometry, isotope dilution mass spectrometry, spark source

isotope dilution mass spectrometry and spectrofluorimetry.

The stability of the trace elements in the solution were to

be studied in Teflon FEP, polyethylene, and quartz containers.

Progress

Preparation of Solution: The Teflon FEP, quartz, and polyethylene bottles used in this study were thoroughly cleaned

by prolonged leaching with diluted nitric and hydrochloric

acids. A large 24 liter polyethylene carboy was cleaned by

storing (1+10) HNO3 in the carboy for several weeks. The

carboy was then emptied, rinsed, and filled with ultra pure

water three times.

The elements to be incorporated into the standard were arsenic,

beryllium, cadmium, chromium, copper, mercury, manganese, lead,

selenium, and zinc. A trace quantity of gold was to be added

to stabilize mercury. Standards of varying concentrations

(Table 45.1) were prepared by dissolving weighted amounts of

the pure element (as metal) in acid and diluting to 10 ml in

a volumetric flask. An intermediate solution of As, Si, Cr,

Cd, Pb , Mn, Be, Au, and Hg was prepared by adding aliquots

if

the standard solutions of the elements to another volumetric

311

1
flask and diluting to volume. Since this was a trial solution

no attempt was made to calibrate the glassware used. The 24

liter carboy was filled (by weight) with 23 liters of . 5N

nitric acid. An aliquot of the intermediate solution and

separate aliquots of the Cu and Zn standards were added and

the solution was stirred for 16 hours by a magnetic stirrer.

The solution was then transferred to 15 one liter Teflon

bottles, 9 two-hundred-fifty milliliter quartz flasks and

12 five-hundred milliliter polyethylene bottles.

Analysis of Standard: The initial analysis for all elements

were taken within one week of preparation of the standard.

With the exception of arsenic, the results were in fairly

good agreement with the calculated concentration. Arsenic

was 30 percent low and may have been lost during the preparation of the sample.

Considering the concentration of the mixed heavy metals, the

agreement between techniques was good for some elements (Be,

Cu, Hg, and Zn) but poor for others (Cd, Cr, Mn, and Se)

.

It ranged from 0.5 percent for Be to 50 percent for selenium.

Obviously, more work is needed before some elements could be

certified in a standard.

The standard was again sampled and analyzed after 17 weeks

storage in the containers. The results as reported in

Table 45.1 show that no significant loss of any element

occurred over this time interval. For some elements there

are apparent increases in concentration when stored in

Teflon but these are within analytical uncertainties.

The results of analyses after storage in Teflon, polyethylene

and quartz are shown in Table 45.2. Foi^ "the most elements,

there was no apparent difference between the three materials.

There was an apparent increase in mercury content on storage

in polyethylene but further determinations are necessary to

verify this. Based on these results and the fact the quartz

flasks are difficult to seal. Teflon would be the preferred

container material for a future standard.

Future plans call for the refinement of measurement methodology

and the re-analysis of this standard at a three to six month

interval to further study stability on storage. We plan to

propose to the Office of Standard Reference Materials that a SRM of mixed heavy metals in water be certified but with lower

copper and zinc concentrations.

312
TABLE 45.1 Multi-Element Water Standard Stored

in Teflon FEP

Calculated

Concentration

yg/g

Initial Analysis

yg/g

Analysis

17 week

yg/g

after

s

As 0.0937 0.0603

0.062

NAA

AA

0.0630

0.0599

NAA

AA

Au 0.0017

Be 0.0397 0.0404

0.0406

AA

SF

0.0412

0.0409

AA

SF

Cd 0.01365 0.0146

0.0146

0.0185

NAA

AA

SS

0.0149 AA

Cr -0.047 0.060

0.0498

0.053

NAA

AA

SS

0.056

0.0471

NAA

AA

Cu 0.8069 0.851

0.814

0.78

AA

NAA

SS

0.849

0.849

0.848

AA

NAA

IDMS

Hg 0.00184 0.0018

0.00182

NAA

AA 0.00175 AA

Mn 0.0418 0.042

0.0391

NAA

AA

0.047

0.0455

NAA

AA

Pb 0.0469 0.0498

0.0467

AA

IDMS

0.0459

0.0465

AA

IDMS

Se 0.01009 0.0105

0.0107

0.016

NAA

AA

SS

0.0098 AA

Zn 4.8928 4.96

4.96

5.16

NAA

AA

SS

5.08

5.083

NAA

AA

Key: AA Atomic Absorption Spectrophotometry

IDMS Isotope Dilution Mass Spectrometry

NAA Neutron Activation Analysis

SS Spark Source Isotope Dilution Mass Spectrometry

SF Spectrof luorimetry

313
TABLE 45.2 Storage of Multi-Element Water Standard

in Various Containers^

Element Tefl on Polye thylene Quartz

Initial 17 Weeks Initial 17 Weeks Initial 17 Weeks

yg/g yg/g VJg/g yg/g ug/g yg/g

As 0.062 0.0599 0.064 0.0595 0.064 0.0591

Be 0.0404 0.0412 0.0381 0.0412 0.040 0.0417

Cd 0.0146 0.0149 0.0138 0.0141 0.0146

Cr 0.0498 0.0471 0.0481 0.0473 0.0488 0.0467

Cu 0.851 0.856 0.850 0.855 0.852 0.857

Hg 0.00182 0.00175 0.00209 0.0246 0.00186 0.00183

Mn 0.0391 0.0455 0.0398 0.0459 0.0386 0.0461

Pb 0.0498 0.0459 0.0492 0.0471 0.0484 0.0476

Se 0.0107 0.00986 0.0128 0.00986 0.0112 0.00966

Zn 4.96 5.083 4.98 5.096 4.97 5.075

3. All determinations by atomic absorption spectrophotometry.

314
46 . Trace Hydrocarbon Analysis

Project Leaders H. S. Hertz and S. N. Chesler

Analytical Chemistry Division

Other Personnel: S. M. Dyszel, D. P. Enagonio, B. H. Gump,

D. A. Becker, and W. .E. May

Objective

To develop chromatographic and mass spectrometric separation

and analysis techniques for the quantitative determination of

trace levels of petroleum hydrocarbons, especially aromatic

hydrocarbons. To establish meaningful analytical values for

existing levels of crude oil pollution in the marine environment .

Progress

The method of analysis developed in this laboratory [1,2]

involves dynamic headspace sampling for volatile hydrocarbon

components of the sample followed by coupled-column liquid

chromatography for the non-volatile components. These techniques require minimal sample handling, reducing the risk of

sample component loss and/or sample contamination.

Volatile sample components are separated from the matrix in

a closed system and concentrated on a TENAX-GC packed precolumn, free from large amounts of solvent and ready for

GC/GC-MS analysis. Non-volatile compounds, such as the

benzpyrenes, may be extracted from large volumes of water

and concentrated on a Bondapak C18 packed pre -column for

coupled-column liquid chromatographic separation and analysis.

315
Prior to the development o£ oil transfer facilities in Port

Valdez and exploratory drilling in the Northeastern Gulf of

Alaska, this area is presently relatively pristine, the

principal economic activity being commercial fisheries.

Except near natural oil seeps, hydrocarbons in the environment are expected to be present at the microgram per kilogram

level and may well be non-petroleum in origin. A number of

sites were selected for sampling within the Prince William

Sound and the Northeastern Gulf of Alaska to reflect the

various types of environments found there. Tables 46.1 and 46

summarize the data obtained over several seasons for sediment

and water from these various sites.

Some seasonal variability in hydrocarbon content is observed

in the different sites, however, no reproducible pattern is

discernible. High values do not necessarily represent

petroleum pollution but could be of biological origin.

Included in this report are results of a detailed GC-MS analysis of sediment from Katalla River. The gas chromatogram

obtained from the sediment indicated the presence of a "petroleum hump". The total ion chromatogram (computergenerated gajS chromatogram) for the sediment is presented in

Figure 46. IC. Figure 46. IB contains the m/e 43 mass chromatogram

for the sample. (Mass chromatograms are computer-generated

mass specific gas chromatograms used in locating particular

compounds or classes of compounds containing an indicative

m/e peak in their mass spectra.) A peak at m/e 43 is indicative of aliphatic hydrocarbons and in Figure 46. IB this mass

chromatogram helps identify the homologous series which one

could not have visually identified in the complex gas

chromatogram.

The GC-MS analyses of the sediments from Katalla River confirm that the major constituents are all hydrocarbons. Due

to the large number of aromatic hydrocarbons and to the

absence of any even/odd preference in the aliphatic series,

the presence of petroleum is indicated. This is an expected

result since the Katalla River site is downstream from known

oil seeps. One final note of interest concerns the complexity

of the petroleum hump, which contains a large number of unresolved hydrocarbons. By the use of mass chromatograms

some compounds can be easily resolved. An example is shown

in Figure 46. lA which contains the composite mass chromatograms

for m/e 142, 156, and 170, the molecular ions indicating the

presence of C, , C-, and C_-naphthalenes , respectively.

See last page of text for detailed information on Figure

46.1 C. ^T^ 316
Percent of total Hydrocarbons by Total maximum hydro- Molecular Weight Region

carbon Content (ug/kg

wet weight) Obtained by Site/Season Headspace Sampling Hlnchlnbrook Is. Summer 73 83 (1) E

Fall 73 115 (1) Spring 7" 63 ± 10 CO

Fall 71 91 t 29 (tJ Mineral Creek Summer 73 121 Pall 73 I'il t 20 (1) Spring 71 190 ± 2 (2) Dayvllle Mud Flats Summer 73 25t t 12 (3) Fall 73 153 t 23 (3) Spring 7t lt7 51 (D

Fall 71 167 t 26 (3) Wells Bay Low Beach

Fall 73 118 t 18 (2) Spring 7t 123 ± 3 (2) Wells Bay High Beach

Sunaner 73 255 ± '<7 (2) Spring 71 175 t 38 (2) Old Valdez

Spring 7t 91 ± 8 (2) Fall 71 167 ± 8 (2)

Orca Bay Spring 7t 288 1 65 (3) 52 t 5 21 ± H 23 Bllgh Island Summer 73 Fall 73 Spring 71 Slwash Bay Spring 71 Fall 71 Cape Yakataga

Fall 71

Katalla River t. Fall 71 566 t 113 (3) 28 ± 8 31 t 2 10 t 11 D

value for combined region

MacLeod Harbor

Pall 71 121 » 19 (5) 22 ± 1 23 t 3 31 * 5 21 ± 5 Mlddleton Island

Fall 71 155 t 115 (1) 32 « 6 36 t 8 1I t 1 18 t 2 Squirrel Bay i Fall 71 956 i 63 (2) Q

11 t K i( t 3 81 t 6 D

value for combined region

Meal bylene Naphthalene

Propylnaphthalene

Trlmethylnaphtha]

(or ene) . Phenanthrene

3526

13 1 9 25 1 10

29

26 26

10 ±

32 3110

36

18

t 10

t 2 51 - 11

31 29 i 1 32 1 6

31 28 ± 26 t

12 12

12

31

t 1

t 6

28 , 30 t 33 t 6 t2

815

3

30 1 26 ± 26 t

3 ±

2

3

3

1

1241

11

11

* 1

* 7

* 13

* 5 80 ± 8

17 ± 51 t

36 32 t 32 t 1

6 20

16

t 3

t

3718 .

1 26 t 25 t

1

1 3626

t 3

1 1

26 t 12 ±

11 18 t 11 115 56 ± 1value

71 t for combined region

171 219

t

t 9 12

(1)

(2) (5)

105

311

61 t

12

8

6

(3)

2)

3)

72

367

1 16

(1)

(3)

566 t 113 (3)

121 t 19 (5)

155 * 15 (1)

956 t 63 (2)

25

31 ± 13 ± 1

3

1822 4 1 26 t 1

29 t 15 t 53 t

9

12

26 t 3 36 t 1 20 ± 5

26 t 37 10 13 t 5 18

28 t 8 31 t 2

22 1 1 23 t 3

32 '- 6 36 1 8

11 t 1 1 t 3

5716

30

1 3

1

1520

6

6

lvalue 27 t for

8' b

combined regl on

12

8

1 2 18

37

* 17

3. ( ) denotes the number of samples analyzed.

K Phenanthrene internal standard not recovered so component amounts Included In propylnaphthalene (or trlmethylnaphthalene) molecular weight region. n Abnormally high value for maximum hydrocarbon content not consistent with low values obtained from water analyses. This was a very adsorptive sediment requiring 5x the amount of Internal standard to be seen In the gas chromatogram.

This site visually appears to be quite pristine. It Is under continuing Investigation.

Table 46.1. Hydrocarbon Content of Sediment Samples

as Expressed in Percentages by Molecular Weight Region.

317
00

CJ •H

CO

CM

JO

toco

J3 E U O

«J -H U bO O 0) ?^ CC X x;

bO

rH -H

0) OJ o

E-" t,

(fl <M rH O. 3o

•P 0) C rH

0)O

Oh

X)Xi rO XI roo

\o CM mrH

OJc

0)

i-H 1 0) rH £ CT\ >>-P i-i rH ax: o a +1 +1 u m

CU, 2 ^ o ^ C\J

C\J

CVJ CM

+1H +1 -H

rvj CM t— VO rH CMCM

OJ -3-

CO

+1

CMm

+1 +1 oo o

CM rH r-i

QJC

0) o

>11 > CM rH vo

•H +1 +1 +1

to

(U VX3 00 t--o s mm CM CM

rH rH COon ^ VO o

rH orH

+1 +1 +1 +1 +1 -M «

rH irv CM Lr» cnt~-vD

CM

rH

C

-:3^ -3- CM -3-

rH c

rt o "O

PL, J3

C '^ ( ca •H b£ f—

CO

O to c" on ^^

<D o 4-> -H <-—

N . . ^^

m

t< XlrH m(M >^^ V) V o a — —

oo >s >5 e en cr> X ^ CO O CM • • I—

bOcO ^ o o

rt E i; t-\

O •-{ ^ 3 \ 0/ ^-^ +1 H-t ±3 E bOc +J +i <i •H 3.>C ONin m X —' a t-VO • CT\ • Jh t« to ^ • rH £ P T3 CM rH rH O rH o c to +J rH 0) <U rt ^ PO

px; cO >i EH 0£ll to

r-\-=X OO rH CM T-\ rH • • • • ^-^ « • • O O r-t O r-i t-t --^ ^^o fH^>

H-l >

rH rH rH

+1

M " irx ** "-^

+1 H^ ovo m • O •

^3-

O ON ITlrH OO <>-> ir> r- mm in mrH ^ ir>

O 4-> to (U !<« E u3 O

CO rH

u

0) <u

CO 0) <« e 3 o

CO rH

to ^ w tl> to > OJ -p a> H Q) >

CO o (CO o

Jn! to CO o

to ^ to <«

>->

u rH ^ u 3 r-{ 3 o

0) CO (0 CO x: o -P C

CO CO c o !*i •*

u

(U d) O -P

CO <U

(h30CO rH , nM o a x> o t. o <u CO

^^

O

K

XI cd c <;-.

D

H (h

C

x: 3 <L o CO -i c c

•H (S X s

TJC

OJ rHm >:

u l-H

u at t<

0) 0) « > 0> 0) cu 01 «> O 4i C o a O -P O 4-> as a> o Id (t at a> rH at 0) <« e -p «- n- E a> i« t=

r< 0) (<

X ^ U

b 3 O rH 3 0! 30 U 30

CO rH o

•o•Hs m

a

col

CO rH 3

CT CO

WrH o

(hat T3C

at • p o m

a>N r-> >.cd

rH

C

01U

C 9) at -pC m «H

0) rH c

a-rH E

afo

0) 9i •n «H 3 o w-f u

(hC

0) •»H XIb 4J 3 o C c

a> o:

0) c

-p OJ o u c x:

a>

p o c

at

^-^

C

a; x: >

a.

nS rO

318
E

Figure 46.1 GC-MS analysis of Katalla River sediment

319
Due to the presence of petroleum hydrocarbons in the Katalla

River sediment, studies are underway using this sediment as

a petroleum-in-sediment interlaboratory calibration material.

Large quantities o£ the Katalla River sediment have been

collected and are being distributed to various laboratories

for hydrocarbon analysis using their particular methodologies.

Comparison of the interlaboratory data should provide a measure of the analytical variability among the participating

laboratories

.

An analytical method for the determination of petroleum hydrocarbons in various marine tissue samples has been developed

in our laboratory. The method involves dynamic headspace

sampling of the tissue homogenate followed by liquid chromatographic removal of the biogenic polar components prior to

quantitation of the petroleum hydrocarbons using high resolution gas chromatography. Since most of the organic compounds

being removed from the tissue homogenate are of biological

origin, a liquid chromatographic cleanup is necessary to

remove these biogenic components. Figure 46. 2A is a gas chromatogram obtained from headspace sampled Mytilus tissue

homogenate without removal of the polar biogenic components.

An effective LC cleanup is achieved using a yBondapak NH2

column (Figure 46. 2E), thereby reducing the biogenic background

in the gas chromatogram and allowing greater sensitivity for

the individual petroleum hydrocarbon components. When using

a nonpolar mobile phase such as pentane, the yBondapak NH2

column provides a class separation similar to that obtained

using a silica column, i.e., saturated hydrocarbons elute

before unsaturated hydrocarbons and aromatics, and the

elution volume for the aromatics increases with the number

of condensed rings.

Using a nonpolar mobile phase, the biogenic compounds, which

are thought to be long-chain aliphatic alcohols, are retained

on the polar LC column. These compounds are removed from the

column by increasing the polarity of the mobile phase. The

polar biogenic components which were retained on the column

during the LC cleanup are shown in Figure 46. 2C after removal

from the column using methanol.

Analyses using this method are presently being performed to

determine the baseline hydrocarbon levels in Mytilus tissue

collected at sites in Prince William Sound and Northeastern

Gulf of Alaska.

320
JL-J*^

Figure 46.2 Gas chromatographs of headspaced sampled Mytilus tissue with

50pig crude oil added without any LC cleanup of the TENAX-GC pre-column(A)

and with LC cleanup using a yBondapak NH- column (B) . Numbered peaks correspond

to the internal standard compounds each added at the '^'50yg/kg level (1=2-

methylundecane,2=naphthalene, 3=5-methyltetradecane,4=trimethylnaphthalene,

5=7-methylhexadecane,6=phenanthrene, and 7=2-methyloctadecane. Gas chromatogram

of biogenic compounds removed from LC column with methanol (C).

321
Fluorescence spectroscopy has been investigated as a means

of achieving added sensitivity and selectivity for liquid

chromatographic detection of polynuclear aromatic hydrocarbons (PAH's). Fluorescence LC detection has been

particularly useful for the identification of PAH's of suspected petroleum origin in sediment and marine tissue.

Extracts of two sediment samples with known petroleum exposure

were found to contain relatively high concentrations of a single PAH that may be useful as a petroleum marker compound.

These sediments were collected at a tanker facility in

Freeport, Grand Bahamas and on the beach in Santa Barbara,

California (see Figures 46.3 and 46.4, respectively). Liquid

chromatographic analysis of the sediment extracts indicated

a marker compound content of ~150 ppb at the Bahamas tanker

facility and ~13 ppb at the Santa Barbara beach. Extracts

of sediment from a control site in the Prince William Sound

in Alaska showed very little evidence of the marker compound

(<1.3 ppb), which has been tentatively identified as benzo(a)-

pyrene based on chromatographic retention, mass spectrometric,

and fluorescence data.

Measureable quantities of PAH's have also been identified in

marine tissue samples using fluorescence detection. Samples

of oysters collected in the Elizabeth River in Virginia were

extracted and analyzed for PAH's by LC. Figure 46.5 compares

the chromatograms obtained for UV 254 nm detection (A) and

fluorescence detection (B) . Peaks 1 and 2 were identified

on the basis of retention time and fluorescence spectra as

chrysene and benzo(a)pyrene, respectively.

Figure 46.1 C. Identifications followed by "?" are not definite

due to incompletely resolved spectra.

a-C2- cyclohexane q-n-C,, gg-C, -naphthalene

h-C2-4> ^'^A'r hh-n-C^.

c-C^' T s-Cr-cyclohexane ii-n-C^y

d-C^-thiophene t-C^-decalin jj-prisrane

e-n-Cg u-n-C,2 kk-n-C,g

f-Cj-cyclohexane v-C"^- cyclohexane 11-phytane

g-prom^l-9 w-C, -naphthalene mm-n-C,Q

h-C--^ x-C, -naphthalene

i-^3-> >^"^^13

J -C^-f 5 C. -thiophenez-ethyl-naphthalene

k-C. -thio^hene aa-C2-naphthalene

1-n-C^Q bb-n-C, .^C^-naphthalene

m-C,-0 cc-U2-naphrhalene

n-C. -cyclohexane dd-C 2 -naphthalene

o-C.-f ee-ethyl-naphthalene ? p-C^-thiophene ? ff-n-C,r

322
u

(U

U

O

O -H

CO >

^^ CO

4-1

M3

COOJa

j-i o

en

OJ Q)

T3 3

cn /—

0)

O -H P iH 3 -O Xi CU O O e 4J

CO

O

[-J CO bO U o ^-l -y X

CO (U EO 4.) s^ C X OJ •H -H CD 3 W

cr -H ,C

hJU

to - cu <: X3 • CO

COo

COu

4-1 o

CI, OJ

en !-i eo d -3 O p! _ •H cO (^

cn eg cn*> I •H (U e c

0) -H

0) TS C (U

01 ^a cn

cn CO

cu -3 9 s 3 CO

O

•H

4J

CO 4J •HO

a) • 4J pq CO • ^ o e u

13 ^a

c-j

OJ

S-i 3 O H

CO

OJ <U 3

3-1 -H 3 -H -H -3

.HO 3o

•Hu e U O

CU J_l

4-1 4J

0)

O

T3 J3

13

•HrHO

cn

(U3

0)

^^ o

(0' Ee o — s

323
Figure 46.4 Santa Barbara sediment. A. Liquid chromatogram

of extract of sediment; B. Fluorescence emission spectra of peak

1, excitation -300 nm.

B

Tlm«

324
c CO o ^

•H CO

J-) CU

03

a 4J

w •H

u c CJ o

•H

X •—1

cn 0) CO - e s w c M-l ^4 o

<u o

-u ON « CsJ CO >< j:: o .c 4J

4-1 ao

v< •H

C

0) S cu > i-H •H 6 0) ci C >

CO ^ o &

JJ o

:<u <r J= ^ 4J

rt 4-1 •H N CO :s •HiH c c W o §

•H o

'•Mw 4=

O

•H

Cfi

-u E <U o q; M

CO CO u 0)

4-1

a CN

fN

n

<U <u XI o C c cc CO rt <u

V-i I—I

l^-l o o 3 CO rH 4^ w P^ CT3 e CU CO Id p.

Vi

C

bO CO

U

O

O

4-1 • U-l tn ^^ e < CO o v—

U

i-i 4-1 ,c e O o c CUD. •a <r CO •H LO 3 CNJ cu cr O H 4J c

H-l CO cu c CO fi LO o cu G • •H u

\D 4-)

O

C

-cr

O

a -H

cu rH

cu 4J in

C

Vi QJ (1) 3 T3 • >

60 /-N-H

t^

pa

M

c»

<i5 9E >3

325
47 . Organochlorine Analyses

Project Leaders: S. N. Chesler and H. S. Hertz, Analytical

Chemistry Division

Obj ectives

1. Set up a laboratory for organochlorine (RCl) analysis.

2. Procure equipment and other objects necessary to implement ASTM procedure for the analysis of polychlorinated

biphenyls (PCB's), ASTM designation D3304-74.

3. Using D3304-74 obtain acceptable blanks (< .i^).

4. Analyze samples supplied by Monsanto (consisting of

distilled and river waters spiked with Aroclor 1254 or

1016) .

5. Note shortcomings in ASTM D3304-74 procedure.

6. Familiarize ourselves with proper laboratory procedures

for RCl analyses.

Accomplishments

1. Single laboratory module (6-105/222) was cleaned and

Teflon coated bench coverings applied to all work surfaces. The existing exhaust hood was modified to accept

the evaporation apparatus required by D3304-7.

2. Approximately $3K spent in obtaining extraction and

evaporation glassware. A linearized electron capture

(EC) gas chromatographic instrument was set up and

checked out.

3. To obtain 0.1% blanks, it was necessary to follow the

criteria below:

a) Prior to use, all glassware must be soap and water

washed, then be immersed in a hot acid bath (HaSOi^

at 105°C) for at least one hour, and finally rinsed

with hydrocarbon-free water.

b) Glass wool and NaaSOt, used in D3304-74 must be

cleaned by exhaustive soxhlet extraction (minimum

of 18 h) with pesticide grade hexane.

326

i
c) The clean NaaSO,, must be used quickly (1 week)

otherwise it will pick up contaminants and cause

high blanks

.

d) Hexane extracts containing PCB's at mg levels are

not stable for long periods of time. Thus new standards must be prepared at least weekly.

Results of Analyses were not obtained due to the deterioration of the water samples provided by Monsanto. The

samples were exposed to moderately high (~50°C) temperatures when refrigeration equipment in which they were

stored failed. We postulate that this caused deterioration of PCB containing samples.

The major shortcoming of D-3304-74 is the lack of

detailed protocol for clean-up of glassware, chemicals,

and apparatus necessary to achieve consistently low

blanks. The data reduction section of D-3304-74 is

confusing.

We find that it is not a trivial undertaking to set up

and run RCl samples. Great care is needed to maintain

the integrity of the analyses undertaken. We feel that

NBS cannot undertake to realistically perform state-ofthe-art RCl analyses without a concentrated and well run

experimental program.

327
48. Fate and Effects of Oil Discharged on the Marine

Environment

Project Leader:

Other Personnel:

S. Wasik, Physical Chemistry Division

F. P. Schwarz, R. N. Boyd, R. L. Brown,

J. I. Minor, T. Krishnamurthy

Objective

To provide a technical basis to formulate, promulgate, and

defend international regulations concerning permissible

discharges of oil from ships. More specifically, these

objectives are: (1) to measure the partitioning of petroleum products in the environment, (2) to develop methods,

based on physical and chemical concepts, for sampling,

handling, and analyzing hydrocarbons in an aquatic environment, and (3) to evaluate the sensitivity and selectivity

of spectrofluorimetry for measuring aromatic hydrocarbons

in water and to apply this technique to elucidate the

physical and chemical properties of aromatic hydrocarbons

in aqueous systems.

Progress

The Partiti

Environment

mining the

hydrocarbon

used to mea

to 100 over

[l,2,^ det

carbon cone

liquid or s

oning of Petroleum and

: Three methods have b

partition coefficients

s in fresh and sea wate

sure partition coeffici

a temperature range 0-

ermines by gas chromato

entration of the gas ph

olid. A known volume o 328

Petroleum Products in the

een developed for deterand solubilities of

r. These methods can be

ents in the range of 0.01

25°C. The first method

graphy, the relative hydro

ase in equilibrium with a

f the gas phase is then
purged out of the apparatus and replaced with clean air.

The relative hydrocarbon concentration in the gas phase is

measured after the second equilibrium. The partition

coefficient is calculated from the area ratios of the solute

peaks and the volume of the gas and liquid phases.

The second method consists of extracting dissolved hydrocarbons from a sea-water extract with small hydrogen bubbles

generated electrolytically from a gold electrode located in

the bottom of a cylindrically shaped cell [3,11] . The partition coefficient is determined by measuring the decrease

in hydrocarbon concentration as a function of the volume ot

hydrogen bubbled through the cell.

A third method for determining the partitioning of hydrocarbons

between water and air was developed for the high molecular

weight polycyclic aromatics [l3]. This method is similar to

the first method except fluorimetry is used to determine the

hydrocarbon concentrations in the water phase.

Using these methods, the partition coefficients and solubilities

of most of the aromatic hydrocarbons of interest in oil spill

studies have been determined as a function of temperature and

salinity.

A method [IZ has been developed for determining the partition

coefficient of aromatic solutes between water and a lipid phase

(1-octanol). This method also uses fluorimetry to determine

the hydrocarbon concentration in the water phase.

Development of Methods for the Analysis of Trace Amounts of

Hydrocarbons in the Aquatic Environment: A method was

developed for the analysis of trace amounts of hydrocarbons

in sea water using the concept of extracting the organic

material by electrolytically generated hydrogen [4,8] . The

advantages of this method are: (1) the hydrocarbons are

extracted from the analytical cell as hydrocarbon groups,

(2) no impurities are added to the sea water by the extracting

solvent, and (3) a minimum of sample handling is required for

analysis

.

In conjunction with this work, new types of chromatography

columns were developed in order to separate the aromatic

hydrocarbons. A liquid crystal column [iq was used to

separate the naphthalene homologues and a solid silver

nitrate column [^ was used to separate the alkyl-substituted

benzenes

.

A gas-chromatography plasma detector was built for elementary

and deuterium analyses. This detector will be used in stable

isotope analysis to determine bio-concentrations and hydro329
carbon breakdown in live fish. This detector will also be

used to determine vapor pressures o£ polycyclic aromatics.

Sensitivity and Selectivity of Spectrofluorimetry : A spectro fluorimeter was assembled using photon counting techniques. Fluorescence spectra, quantum yields, and sensitivities were

determined for fine representative polycyclic aromatic hydro- carbons in aqueous solutions to ascertain the applicability

of using this technique for pollution studies [5 , ^ .

References

[1]. Wasik, S. P., and Brown, R.L., 'Determination of hydrocarbon solubility in sea water and the analysis of hydrocarbons

in water-extracts," (Proc. 1973 Conf. on Prevention ^ Control

of Spills, March 13-15, 1973, Wash., DC, Section on Identification of Oil), pp. 223-227 (The American Petroleum Institute,

Wash. , DC, 1973)

.

[2]. Brown, R. L. , and Wasik, S.P_.,. "A method for measuring

the solubilities of hydrocarbons in aqueous solutions," J. Res.

BBS 78A , 453 (1974)

.

[3]. Wasik, S. P., "Determination of hydrocarbons in sea

water using an electrolytic stripping cell," J. Chromatog . Sei.

12 845 (1974).

[4]. Wasik, S. P., and Boyd, R.N. , "Determination of aromatic

hydrocarbons in sea water using an electrolytic stripping cell,"

NBS Sveo.Puhl, 409 » (Proc. 1974 Symposium and Workshop on

Marine Pollution Monitoring (Petroleum), May 13-17, 1974, NBS,

Gaithersburg, Maryland) pp. 117-118.

[5]. Schwarz, F. P., and Wasik, S. P., 'Fluorescence measurements

of benzene, naphthalene, anthracene^ pyrene, f luoranthene, and

benzo [e]pyrene in water," Anal. Chem.

^

524 (1976).

[6]. Schwarz, F. P., and Wasik, S.P., Fluorescence measurements

of carcinogenic and polycyclic aromatic hydrocarbons in water",

(Proc. International Conference on Environmental Sensing and

Assessment, Vol. 2, Sept. 14-19, 1975, Las Vegas, Nevada), Session

30-2, pp. 1-5 (Institute of Electrical 5 Electronics Engineers,

Inc., New York, NY, 1976).

[7]. Wasik, S. P., Brown, R.L. and Minor, J. I. Jr., "Partition

coefficients and solubility measurements of dimethylmercury

in fresh and sea water over a temperature range 0-25°C, Environmental Lett. 11.

330
[8]. Wasik, S. P., and Schwarz, F.P., "The analysis o£ hydrocarbons in sea water by a head-space method," (Proc. NBS-EPA

Workshop on Standard Reference Materials for Offshore Drilling

for Petroleum, Oct. 6-7, 1975, Santa Barbara, CA) NBS Spec. Pub.

(in press) .

[9]. Wasik, S. P., and Brown, R.L., 'The analysis of complex

aromatic hydrocarbon mixtures using solid silver nitrate columns,"

Anal. Clnem. (in press).

[10]. Wasik, S. P., and Chesler, S., 'Use of a nematic liquid

crystal for gas-liquid chromatographic separation of naphthalene

homologues," to appear in Proc. 11th International Symposium

on Chromatography, July 5-9, 1975, Warwickshire, England.

[11]. Wasik, S. P., "Solubility of Aromatic Hydrocarbons in

Sea Water," (In preparation).

[12]. Krishnamurthy, T. , and Wasik, S.P.,, "The Partitioning

of naphthalnee homologues between water and 7-octanol," (In

preparation)

.

[13]. Schwarz, F. P., and Wasik, S.P.., " Fluorescence method

for the measurement of the partition coefficients of naphthalene,

1-methyl-naphthane , and 1-ethylnaphthalene in water," (Submitted to

Analytzcal Chemistry

:

331
49. DDT Propagation Models

Project Leaders: A. J. Goldman and L. S. Joel, Applied

Mathematics Division

Obj ective

The interagency Federal Working Group on Pest Management, in

connection with its efforts to test existing mathematical

models of DDT and develop superior models as needed, requested

support to the Ad Hoc Committee on Mathematical Models of its

Research Panel. The present project provides the support

component of mathematical modeling and analysis pledged by

the Director of NBS through DoC's Deputy Assistant Secretary

for Environmental Affairs. Its objective is to assist a significant interagency effort to determine the suitability of

current mathematical models and data for predicting and

evaluating residues in soil, water, and air of pesticides

(specifically DDT), to create improved models and secure

additional data as required, and to identify critical research

needs in this field.

Approach

Mathematical analyses are performed of the logical consistency,

algorithmic quality and data-fitting capability of proposed

or newly synthesized models, with special attention to the

sensitivity of outputs to uncertainties in data or model

structure. Related numerical computations are funded by EPA

(Project 2050407)

.

Pr ogress

At the Working Group's request we have focused on a particular

model which applies J. W. Forrester's "Systems Dynamics" approach and the associated "DYNAMO" simulation language to the

construction of computerized ecosystem models. The model is

documented in [1] .

The model uses a set of difference equations to trace over

time the flow and accumulation of DDT among/in 5 major

ecological "compartments" (soil, air, rivers, oceans and

fish) , each considered as a single homogeneous worldwide

332

I
aggregate. The flow is triggered by application of DDT, and

its analysis stops short of considering the takeup of DDT by

life forms higher than fish.

We recognized 5 goals: (a) to obtain and check-out a DYNAMO

compiler compatible with the NBS computer and its operating

system, (b) to check that the Systems Dynamics model accurately

represented the differential-equations system which follows

directly from the defining transfer relationships, (c) to

identify the most critical model assumptions and parameters

in terms of sensitivity of outputs, (d) to identify the model

assumptions most questionable because of absence of corroborating data (or presence of alternative plausible hypotheses

also compatible with data) , and (e) to identify critical

directions and data requirements for refining this very crude

model.

Goals

(a) An updated compiler, DYNAMO Up has been acquired and is

at present undergoing acceptance test and integration

into the executive system of NBS' Univac 1108 computer.

(b) Two rudimentary extensions of the DYNAMO model have been

initiated: A partition of "soil" into two compartments

to study the effects of the application of DDT in one

part of the world's land mass on accumulation elsewhere

and the addition of an aggregated compartment, representing food chains above the level of fish, to furnish

a source of feedback (through mortality and excretion)

from what was previously treated as a sink.

Further disaggregation to isolate regions with apparently

high relative concentrations of DDT such as estuarine

waters and lakes will be attempted.

(c) Sensitivity analysis of the system through parameter

variation in model runs (in progress) will be supplemented by further mathematical treatment of the

differential equations.

Additional modeling systems, e.g., CSMP will be examined

and compared with DYNAMO.

(d) Redefinition of some model components and reorganization

of outputs, e.g., calculation of concentrations in place

of mass levels, will be made to facilitate comparison of

modeling results to those from other models.

333
Future Plans

We are intensifying our efforts to develop guidelines for:

The selection and testing of mathematical procedures and

computer software for modeling and the determination of

levels of model aggregation and data precision consistent

with given modeling objectives.

I

334
50 . Reactor Effluent and Environmental Radioactivity

Standar"3s"

Project Leader: J. M. R. Hutchinson, Center for Radiation

Research

B. M. Coursey, L. L. Lucas, P. A. Mullen,

J. R. Noyce, F. J. Schima, M. P. Unterweger

Obj ective

The objective is to improve the accuracy of measurements of

radioactivity in the environment and in the effluents from

nuclear facilities. In order to accomplish this, an immediate goal is to make all such measurements in the United

States either directly or indirectly traceable to the

National Bureau of Standards.

Approach

Current activities on this project can be grouped into the

following three categories: (1) Establishing traceability

of radioactivity measurements performed by the Nuclear

Regulatory Commission (NRC) and Environmental Protection

Agency (EPA) ; (2) Development and Production of radioactivity

sources calibrated for activity or emission rate and issued

as standard reference materials (SRMs) to be used as either

test sources or for the calibration of detectors by environmental monitoring laboratories. Much of the work in developing radioactivity standards of "heavy element" radionuclides,

including those in the natural decay chains has been supported

under an EPA sponsored "energy program". Milestones are

shown in Table 50. 1; (3) Performance of developmental work

aimed at maintaining a "state-of-the-art" measurement capability and dissemination of information through committees,

publications and talks.

335
TABLE 50.1

RADIOLOGICAL POLLUTANT ASSURANCE'

Performing Agency: National Bureau o£ Standards

(EAP I.D. No.: 77 BCN)

Task 1. Radiological FY

Standard Reference 76

Materials

(Funding $K)

FYFYFYFYFY FY FY FY FY

77 78 79 80 1976 1977 1978 1979 1980

1.1 Establish Lab

Facility

1.2 21%

Standard

1.3 ^^^Ra Soil,

Mixed Gaiiima

Solution,

Pu

40^ _. _. ._ ._ ^

10^ .. .. .. ._ ^

41^ 15 -- -- --

1.4 Mixed Gamma

Soil

1.5 ^^°Ili,^^^Pu,

241

Pu

1.6 24V 24 V'U,

238U

!0 5

15 10

35 15

1.7 210pb,232^,243^^^

244

Cm

35 30

Totals '1" 50 50 50 30

Issuance of all SRM's are subject to satisfactory performance as defined by

NBS SRM criteria.

This is the only one of the three subagreements in which funds from EPA

FY s 75 and 76 will be expended entirely in the NBS FY 76.

^Funding from EPA FY 75 Allocation.

*Tunding from EPA FY 76 Allocation.

I

336
Trace ability . Since 1971 we have engaged in a traceability

study with the Health Services Laboratory (HSL) of the U. S.

Atomic Energy Commission (AEC) in Idaho Falls. We have also,

recently initiated a traceability program with the Quality

Assurance Branch of the U. S. Environmental Protection Agency

(EPA). Agreements have been reached specifying how traceability to NRC and EPA is to be established and maintained.

These agreements require that NBS provide approximately 15

test samples to each of the two laboratories and also to perform some testing of NRC and EPA sources. The status of the

projects for the 1974-1976 period are summarized in Table 50.2

for NRC and Table 50.3 for EPA.

Standard Reference Materials . The following SRM's have been

developed over the three year period.

o Low-Energy-Photon-Emission Rate Standards ("Point

Source")

Iron-55

Strontium-85

Cadmium-109

Iodine-125

o Natural Matrix Standards

River sediment

Homogeneous river sediment

Mancos shale (in preparation)

Dead water (in preparation)

Radon Blanks (in preparation)

Gaseous Standards

Argon-37

Argon-39

Krypton- 85

Xenon-127 (in preparation)

Xenon-133

o Alpha-Particle-Emitting Solution Standards

Americium-241

Americium-243

Plutonium-239

Plutonium-242

337
?-• +-» CD eg U Q

•P • T3 C O-H

(U 'H i-H

C O-H

M 0) U Q

(1> +J I T3

(=! O-H

.3

LO LO LO LO LO

t-» r-- r^ t~~~ r- &0 bO (30 bO bO

iH LO 00 c-~- en

LO \0 CX3 to l>0

Lf) LO LT) LD LO r^ t^ r^ t^ r- bO bO &0 bO (30

CJ S >H u u

uo LO 00 to to

bO

c .a bO o rt •H +J •H <D H C -P t) ^ 8 •H rH o [5 '^ CO (rt (D Ch 13 p b o

(1> ^ ^:^

2 ^ >-«

UO LO LO LO

I--, r-- t~^ r~-

eg o o fi g 2 u u (^5 < CM t^ O LO 00

(N Lo \o 00 a>

LO •"^ •^ «^ LT) c^ r-. r- r^ r^

rt u d 3^ S O "-2 •-3 S

S c^' o <a

LO O O o to ^3 '^-^

»* »* to

r-. r-« fJ-< ^ -P ^^8

fH <D bO

CJ CO X iH uo to

UO t-^ O

bO a

•H P 0}

tfl P bO

a> (- q trt

C_J P 13

iH P -H J Sri tl 13 O W 3

•H 'H C

> p >^o

•H 3 eg -H 13 «H a 13

LO vO ^ r- r- c^

>> >>

iH -H

Csl \o to

to to \0

LD LO

^'3

CJ CO ^ O r-l Oi

CO CO

en o 00 CT)

vO vO vO

t^ r^ t^

13 O g o eu <

00 O 1—

(

«^ rH Tt

1-1 CSl CM

LO LO LO

r^ r-- r--

•^2 "-0

S5I cr> (Ni to

to ^ "^

CM (N CN]

o

-^ P -H

eU bO U

^.S3

338
•P (U U -M

<u rt U Q

vO

t>^ o^

iH

fe (U +J 1 -tS c o •H -H i-H Kfd u ^^ 3

+-> 0)

>-l •P

(U rt U Q

IT) t^

a>

rH

fe (D /"> +J 1 "0 ^3 e! O •H • (U •H rH

4-> Vi ^3 y

o

cS U

V '

f^l

• o

LO • +J <u

f-. +-) c5^

X^ "<* rt t^ H rH

+J 1 c o •H

(D •H rH MT^ y

Oh ^ s

•M U

to

to

•H

totoiotototo^to > > > bO > JH _ _ _ O 3 O 2 222^2

>

£ O C Ji ^H t/) <U SUM>HC/DCOUCJ

•^fo LO 00 cn o r^ '^ LOvOvOOOOOO^tO"*

m -^ o ^.

rt

V) Ti

4-> V) g

a> P H C/D CO hJ^

339
rec

iH

JC

ctf H

NO

IN.

to

to

SUM COG

Tt o in

m vO NO

CO

00

u u

CO CO o> o

00 a>

QQ

CO

at cd

P tH CO S

< rt

CO u

in ^

00 ro

9) O ti bC

Ui L3 U <

0^ O 0> g

LO vO O O

^ V V) bO

U CO U X

iH in t». to m t*N to o

iH (M

Oh CO

r«i o

lO CT»

C-)

CO O

O^

^1 CO

00

OQ

(0

0) <

u cu

^1 w

3

o >>

CO JO •Mta

w a>

a> (^ H P

(/) CO (tf m o> ZS

V)

(/) a>u

boo

a

n

•H

0)

cd

V) M

€

o

>-« 3

(0

cd

(U p

cd <p

a>

cdu

•H

p:

(0

0)

(0

t:;

cd Oh

<

W

340
Beta-Particle-Emitting Solution Standards and Test

Samples

Strontium- 89

Strontium-90

Mixed ^^Sr + ^°Sr (test sample)

Gamma-Ray-Emitting Solution and "Point Source"

Standards and Test Samples

Mixed -gamma -ray -emit ting standards

(i) solution in 50 ml and 450 ml sizes

(ii) Point source standards

Europium-152

Cesium-134

P

I

Developmental Work and Other Activities

1. An interlaboratory intercomparison by 14 laboratories was

conducted by NBS using mixed-radionuclide-test samples.

2. To enable us to make measurements on such materials as

fresh water sediment, we have had to develop our low

level measurement capability. In this regard we have

developed, tested and are presently using an anticompton, anti-coincidence shielded Ge(Li) system, we

have upgraded the Omnigard low level beta particle

measurements systems, and have installed and are using

a relatively low level liquid scintillation system.

3. In 1974, we surveyed European laboratories to determine

whether mutually beneficial, joint programs could be

developed which related to measurements of low level

radioactive effluents from nuclear power reactors.

4. Standardization of solutions of the alpha particle emitting radionuclides ^^"Poj ^'*^Pu and ^"^^Am have been

accomplished using the newly developed liquid-scintillation

counter.

5. New standards and method for measurement of reactor off

gases by gamma ray spectrometry have been developed.

6. Committee involvement includes work on (a) the Interagency

Committee on Plutonium and Other transuranium elements

(b) NCRP SC18A (which is developing a revised version of

NBS Handbook 80) (c) ANSI N42.2 Subcommittee on Radioactive Reference Standards, (d) International Committee

for Radionuclide Metrology, Low Level Techniques Group.

341
A seminar will be held in Paris in October to determine

what the needs are in the metrology of environmental

radioactivity. It is hoped that the recommendations from

the seminar will provide a basis for a coherent international effort in the development of environmental

radioactivity standards.

7. A technique for the spiking of sediment, which is then

homogenous in radioactive concentration, has been developed.

8. NBS has distributed many standards (Table 50 . 4)iirectly to

state laboratories in line with our desire to develop an

active "states program".

Publications

[1]. Hutchinson, J.M.R.,Mann, W.B.and Perkins, R.W. , LowLevel Radioactivity Measurements, 1st International Summer

School of Radionuclide Metrology, Herceg-Novi, Yugoslavia,

August 21-September 1,1972. Nuol.Inst. and Met/2, j Vol . 112 , pp. 305 (1973).

[2]. Ayres , R.L., Cavallo, L.M., Coursey, B .M. , Hutchinson, J .M.R.

and Mann, W. B . ,National Bureau of Standards Gamma-Ray

Standards and Techniques for Gamma-Ray Measurements . ,!"£'£'£' Transactions on l^ualeav Saienae. TANSAO 16_,pp.69 (1973).

[3]. Mann, W.B.,Schima, F.J., and Unterweger, M.P., Radioactivity Standards of the Noble Gases., Noble Gases Symposium,

Las Vegas, Nevada, September 24-28, 1973. (To be published

in Symposium Proceedings).

[4]. Coursey, B.M., Noyce, J.R. and Hutchinson, J. M. R. , Interlaboratory Intercomparisons of Radioactivity Measurements

Using National Bureau of Standards Mixed Radionuclide Test

Solutions. ,/l/55 Teohnioal Note 575^ (Aug. 1975).

[5]. Hutchinson, J,M. R. and Mullen, P. A., Standardization and

Decay- to- the-Ground-State of Selenium- 75 . ,Jnt. J. Appl.Radiat.

Isotopes, 27_,A7 (1976) . [6, 7]. Lucas, L.L. and Hutchinson, J.M.R., Study of the Scattering

Correction for Thick Uranium-Oxide and other Alpha-Particle

Sources (Parti : Theoretical) ;Hutchinson, J. M. R. , Lucas, L.L. and

Mullen,P.A. , (Partll :Experimental) , Int. J. Appl. Radiat.

Isotopes, 11_, 35:43 (1975).

[8]. Noyce, J.R., Hutchinson, J.M.R.,Mann, W.B. and Mullen,

P. A., Development of a National Bureau of Standards Environ- ' mental Radioactivity Standard: River Sediment. To be published

in the Proceedings of the International Conference on Environmental Sensing and Assessment, Las Vegas, Nevada, Sept. 15-19,

1975.

[9]. Mann, W.B. and Hutchinson, J.M.R., The Standardization

of Iodine-129 by 3-y Coincidence Counting ,Jnt. J. Appl.Radiat.

Isotopes, 27_,1S7 (1976) . [10]. Coursey, B.M. , Hutchinson, J. M.R. and Unterweger, M.P.,

Calibration of Ge(Li) Gamma-Ray Spectrometers for the

Measurement of Radioactive Noble Gases. {In preparation).

342
o

0)

WI—I

pao

E-o

E-<

E-OQW

E-D

tf) I—I

PHH

C/3

C/3 <Q<

EC/D PQ2

boC

•H >N

fH o o c w o c bC o<| aCO

M-i

w

O <U <P • rt O -M 2 CO

vh

0} tJ

U

C «)

(D 0) .-h>h|

rt U

uZU<o

CM

U < < < pe^ (Hh Oi Ph 2 W W W

o^ tn rg o^

iH r^ Csi ro

CM

CJ < < CJ

U

oi Ph CL, ce; pc; 2 W W 2 2

en c C o O

•H •H

xt -M +J

(h 3 P

vi i-H iH xt O O

p: CO CO

cd •p JK >^

COw cd rt

W) ctt »H ^ Olw

w

M-i OJ c:) 1 1 o (U to rt rt O u

LO

rt 1—1 e

iH 1 o KD

o; to 00

g S 1 r-i

X 6 to t^

Pu to 1 rt rt e to CO 3 to rj

>^ l-l

C CJS

u s iH •H I-H I-H E- 1 o •H 1 tf) c 1 1 e: +-> 13 ^ c a o o c c o p< (D <i> O O o 4-> o o a >s X X iH C c 3 c c

9i ^< •H •HO (U 03 i-H c <u

X i^ S s cu

x S cx

XX

cti rt c3 cj o

•H

+J

cd

pi.

rt

343
[11]. Hutchinson, J.M.R., Mann, W.B. and Mullen, P. A., Development of NBS Low-Energy-Photon-Emission-Rate Standards., ERDA

Symposium on X- and Gamma-Ray Sources and Applications , 1976

.

[12]. Hutchinson, J.M.R., NBS Standards for Monitoring Radioactive Effluents from Power Plants. NBS Special Publication,

Workshop on SRM's for Power Plant Operation, Feb. 19-20, 1976.

[13]. Coursey, B.M. , Use of NBS Mixed Radionuclide Gamma-Ray

Standards for Ge (Li)Detector Calibration for Use in the Assay

of Environmental Radioactivity .Measurements for the Safe Use

of Radiation^ NBS Special Puhliaation (March 1-4, 1976).

[14]. Seidel, C.W. and Hutchinson, J.M.R.,ANSI Quality

Assurance Program. ^Measurements for the Safe Use of Radiation^

NBS Special Publication (March 1-4, 1976).

Invited Talks

B. M. Coursey, NBS Radioactivity Standards for Use in State

Radiological Health Programs , Annual EPA Region IV Radiological

Health Symposium, December 4, 1975.

J. M. R. Hutchinson, Radioactivity Standards and Traceability

Programs at NBS , Health Physics Instrumentation and Monitoring, A Symposium Sponsored by the New Jersey Chapter, Health

Physics Society, South Plainfield, New Jersey, March 24, 1976.

344
51. Radioactivity Decay Schemes

Project Leader: D. Hoppes, Applied Radiation Division

Objective

This project aids the determination of radioactive pollutants

by supplying decay scheme information and techniques necessary

for the preparation and use of radioactivity standards.

Approach

The efficiency versus energy of several radiation detector

systems appropriate to different radiations and energy ranges

are calibrated with present supposedly well-known standards,

furnishing a check of the consistency of existing decay

schemes, calibrations, and techniques. These detectors are

then used to check discrepant values and determine the

intensity of radiations in other nuclides. For a given nuclide,

these data, together with direct coincidence measurements,

determine the fraction of the total nuclear decays represented

by any one radiation.

Progress

The application of NRC guidelines requiring the quantitative

identification of detectable gamma-ray-emitting nuclides in

nuclear power plant effluents is leading to extensive use of

spectroscopy-grade equipment in the field. During the past

year our development of calibrated gamma-ray detectors has

meshed with a program in the Radioactivity Section to supply

standards for calibrating and testing such effluent-checking

detectors. We developed accurate gamma-ray intensity analysis

methods; searched all source materials for impurities;

compared (with about II accuracy) various dilutions and

nuclides of similar energy; and checked multi-component

standards for possible difficulties in analysis. In turn, the

constancy of our detectors and the applicability limits of

our analysis schemes were under continual scrutiny.

The calibration of a stable Ge(Li) gamma-ray spectrometry

system was continued with the addition of efficiency points

for Cr, Mn, and Zn. A simple computer-generated curve

now relates the counting efficiency at 19 different measured

energies from 279 to 1836 KeV, with a mean deviation of 1%.

Discrepant points are being investigated before application

of this efficiency curve to the analysis of data in hand for

345
''^"^Ag, ^^Se, '•^^Sb, and -"-^^Ba. Measurement of a ^^Sr source

calibrated as to total decay rate led to the determination of

a gamma fraction of (.0102 + .0010)1.

A pure germanium x- and gamma- ray system for the energy region

20 to 400 KeV was secured and used to compare the emission

rates fro© standards of Am, I, Cd, Co, Hg, and

Sn- "^In. This calibration was used to check the

relative intensity of several gamma rays from mul tip le- gamma

75 169 13j ray-emitting nuclides ( Se , Yb, Ba) . A calibration of

169 the total disintegration rate of an Yb source was made by

summing the contributions of all major gamma rays.

346
AIR AND WATER POLLUTION PUBLICATIONS ^^^l - 1976

BASS, A. M. , Ultraviolet Photometer for Ozone Calibration,

Proc. of the 8th Materials Research Symposium, National Bureau

of Standards, Sept. 20-24, 1976, in press.

BECKER, D. A. and LaFLEUR, P. D. , Production and Certification

of NBS Biological Standard Reference Materials, Proceedings

of the Fourth Annual Conference on Trace Substances in

Environmental Health, Columbia, Missouri, p. 433 (1970).

BECKER, D. A. and LaFLEUR, P. D. , Neutron Activation Analysis:

Application to Trace Element Analysis in Biological and

Environmental Materials, Proceedings, Fifth Annual Conference

on Trace Substances in Environmental Health, Columbia,

Missouri, p. 447 (1971).

BECKER, D. A., Accuracy and Precision in Activation AnalysisCounting, Proceedings, Nuclear Methods in Environmental Research,

University of Missouri, Columbia, Missouri, p. 69 (1974).

BECKER, D. A. , Achieving Accuracy in Environmental Measurements

Using Activation Analysis, Proc. of the 8th Materials Research

Symposium, National Bureau of Standards, Sept. 20-24, 1976,

in press.

BECKER, D. A., LaFLEUR, P. D. , and LeROY,A. , Spontaneous

Deposition Radiochemical Separation for Platinum Determination

in Biological Materials, Trans. Am. Nual. Soa.j Supplement S

to Volume 21, p. 5 (1975)

.

BEERS, Y. , HOWARD, C. J., The Microwave Spectrum of HO2 Near

65 GHz, J, chem. Phys. '^1, No. lO, 4212 (1975).

BEERS, Y. , HOWARD, C. J., The Spectrum of DO2 Near 60 GHz and

the Structure of the Hydroperoxyl Radical, j. Chem. Phys. , 64 , No. 4, February (1976).

BLAIR, W. , IVERSON, W. P., and BRINCK>4AN, F. E., Application

of a Gas Chromatograph - Atomic Absorption Detection System

to a Survey of Mercury Transformations by Chesapeake Bay

Microorganisms, Chemosphere 3^^ No. 4, 167-174 (1974).

BRAUN, W., PETERSON, N. C, BASS, A. M. , and KURYLO , M. J.,

A Vacuum Ultraviolet Atomic Emission Detector. Quantitative and

Qualitative Chromatographic Analysis of Typical C, N, and S

Containing Compounds, J. Chromatog, 55_, 237 (1971).

BRAUN, W. , KURYLO, M. J., KALDOR, A., and WAYNE, R. P., Infrared

Laser Enhanced Reactions: Spectral Distribution of the NO^

Chemiluminescence Produced in the Reaction of Vibrationally

Excited 0^ with NO, J- Chem. Phys. 61, 461 (1974).

^ 347
BRAUN, W. , KURYLO, M. J., and KALDOR, A., Infrared Laser

Enhanced Reactions: V^T Energy Transfer in the 0,-SiF--0-

System. Chem. Phys, Lett- 28.. ^40 (1974).

BREITER, D. N. , PELLA, P. A., and HEINRICH, K. F. J., Thin

Film Standards for X-Ray and Proton Induced X-Ray Fluorescence,

Proc. of the 8th Materials Research Symposium, National Bureau

of Standards, Sept. 20-24, 1976, in press.

BRINCKMAN, F. E. and IVERSON, W. P., Chemical and Bacterial

Cycling of Heavy Metals in the Estuarine System, Proc. ACS

Symposium on Marine Chemistry, Series No. 18, in the Coastal

Environment, T. Chruch, Ed., pp. 319-342 (1975).

BRINCKMAN, F. E., JEWETT, K. L., BLAIR, W. R. , IVERSON, W. P.,

and HUEY, C. , Mercury Distribution in the Chesapeake 'Qdij , Pvogvsss

'k^n Water Technology, Suppl., Vol. 7, Krenkel, Ed., 251 (1975).

BRINCKMAN, F. E., IVERSON, W. P., and BLAIR, W. R. , Approaches

to the Study of Microbial Transformation of Metals, Proc.

Third Internat. Biodegradation Symp . , (J. M. Sharpley, and

A. M. Kaplan, Eds.) Appl. Soi. Publ, (London), pp. 919-936

(1976).

BRINCKMAN, F. E., PARRIS, G. E., BLAIR, W. R. , JEWETT, K. L.,

IVERSON, W. P., and BELLAMA, J. M. , Questions Concerning

Environmental Mobility of Arsenic: Needs for a Chemical Data

Base and Means for Speciation of Trace Organoarsenicals

,

Environ. Health Perspectives , in press.

CABANA, A., LAURIN, M. , LAFFERTY, W. J., and SAMS, R. L.,

High-Resolution Infrared Spectra of the Vj and 2v, Bands of

^^N^^02, ^^'^^ J- Pi^ys- ,53, 1902 (1975).

CABANA, A., LAURIN, M. , PEPIN, C. , and LAFFERTY, W. J., HighResolution Infrared Spectrum of the V3 and V2+V3-V2 Bands of

N O2, =^- ^^^- Spectros. 5^^ 13 (1976).

CADOFF, B. C. , HUGHES, E. E., ALVAREZ, R. , TAYLOR, J. K.

,

Preparation of Charcoal Sampling Tubes Containing Known

Quantities of Adsorbed Solvents, NBSIR 74-520 (1974).

CADOFF, B. C, PELLA, P. A., HUGHES, E. E., SCHEIDE, E. P.,

ANGOTTI, A. A., and TAYLOR, J. K. , Development of Analytical

Reference Materials and Contaminant Generation Systems - Work Complete During Fiscal Year 1973, NBSIR 73-411 (1974).

CADOFF, B. C. , DORKO, W. D. , TAYLOR, J. K. , Vinyl Chloride

Reference Material, EPA (1975).

348
CADOFF, B. C, GREIFER, B., PELLA, P. A., and TAYLOR, J. K.

Development of Contaminant Generation Systems for

of Portable Air Sampling Instruments, msiR 74-573

Certification

(1975).

CADOFF, B. C. and TAYLOR, J. K. , Development of a Solid Sorption

Tube and Analytical Procedure for Hydrogen Cyanide in the

Workplace Atmosphere, NBSIR 76-998 (1976).

CADOFF, B. C. , Standard Reference Materials for the Analysis

of Organic Vapors in Air, Proceedings of the 8th Materials

Research Symposium, National Bureau of Standards, Sept. 20-24,

1976, in press.

CAVALLO, L. M. , COURSEY, B. M. , GARFINKEL, S. B. , HUTCHINSON,

J. M. R. , and MANN, W. B., Needs for Radioactivity Standards

and Measurements in Different Fields, 1st International Summer

School on Radionuclide Metrology, Herceg-novi, Yugoslavia,

August 21-September 1, 1972, Nucl. Instr. ondMetho.^

Vol. 112 (1973).

CELOTTA, R. J., MIELCZAREK, S. R. , and KUYATT, C. E., Electron

Energy Loss Spectrum of Ozone, Chem. Phys. Lett.

428-430, February 1, 1974.

24, No. 3,

CELOTTA, R. , MIELCZAREK, S. R. , and KUYATT, C. E., Report on

Electron Spectroscopy

September 1972.

for Gas Analysis, ms Report 10 915

CHABAY, I., Rapid Measurement of Droplet Size Distributions

Optical Heterodyne Spectroscopy, ms Sveoial Publication 412,

65-72 (1974).

by

CHESLER, S. N., GUMP, B. H. , HERTZ, H. S. , MAY, W. , DYSZEL, S. M.

,

and ENAGONIA, D. P., Trace Hydrocarbon Analysis: The NBS

Prince William Sound/Northeastern Gulf of Alaska Baseline Study,

ms Teohnioal Note 889 (19 76) .

COOK, J. M., EVENSON, K. M. , HOWARD, C. J., CURL, R. P., Jr.,

Laser Magnetic Resonance Spectrum of HCOon the D2O 108 y Laser

Line, J. Chem. Phys. 64, No. 4, 1381 (1976).

COURSEY, B. M., NOYCE, J. R. , and HUTCHINSON, J. M. R. , Inter- iaboratory Intercomparisons of Radioactivity Measurements Using National Bureau of Standards Mixed Radionuclide Test Solutions;

NBS Teohnioal Note 876 ^August 1975).

COURSEY B.M., Use of NBS Mixed-Radionuclide Gamma-Ray Standards for Calibration of Ge(Li) Detectors Used in the Assay of Environmental Radioactivity. Proceedings of the Symposii the Safe Use of Radiation.

(March 1976)

.

NBS Special Publication 456,

urn for

349
CURRIE, L. A., The Measurement of Environmental Levels o£ Rare

Gas Nuclides and the Treatment of Very Low-Level Counting Data,

IF.ee Tvans. NS-19 119 (1972).

CURRIE, L. A., and LINDSTROM, R. M. , The NBS Measurement System

for Natural ^'Ar, Proceedings of the Noble Gases Symposium,

Las Vegas, Nevada, Sept. (1975).

CURRIE, L. A., MURPHY, R. B., Application of Radioisotope Ratios

to the Determination of the Original Residence Times of

Atmospheric Pollution, Proc. of the 8th Materials Research

Symposium, National Bureau of Standards, Sept. 20-24, 1976,

in press.

CURRIE, L. A., Detection and Quantitation in X-Ray Fluorescence

Spectrometry in X-Ray Fluorescence Methods for Analysis of

Environmental Samples, Ann Arbor Science Publ., Ann Arbor

(1976).

DAVIS, D. D. , HUIE, R. E., HERRON, J. T. , KURYLO, J. J., and

BRAUN, W. , Absolute Rate Constants for the Reaction of Atomic

Oxygen with Ethylene Over the Temperature Range 232-500°K,

J, Ch.em. Phys. 56, 4868 (1972).

DAVIS, D. D. , HUIE, R. E., HERRON, J. T., Direct Rate Measurements

Showing Negative Temperature Dependence for Reaction of Atomic

Oxygen with cis-2-butene and Tetramethylethylene , j chem. Phys.

59, 628 (1973).

DAVIS, D. D. , HERRON, J. T. , and HUIE, R. E., Absolute Rate

Constants for the Reaction 0(3p) + NO2 -> NO + O2 Over the

Temperature Range 230-339°K, j. ch^rrK Phys. li, 530 (1973).

DJURICIC, M. v., VITOROVIC, D. , ANDERSEN, B. D. , HERTZ, H. S.,

MURPHY, R. C, PRETI, G. , and BIEMANN, K. , Acids Obtained by

Oxidation of Kerogens of Ancient Sediments of Different Geographic

Origin, Advanoes in Organic GeoohemlstTy ^ 1971, Pergamon Press,

Oxford, P. 305-21 (1972).

DORKO, W. D. , Preparation and Evaluation of a Gaseous Standard

Reference Material, Carbon Monoxide in Nitrogen, Proc. of

Symp. (ASTM 8/75 Meeting in Denver, CO), 23 p.

DURST, R. A., BRINCKMAN, F. E., JEWETT, K. L., and DOODY, J. E.,

Electrochemical Studies of the Methylmercury Cation, Special

Publication - Proc. of the 8th Materials Research Symposium,

National Bureau of Standards, Sept. 20-24, 1976, in press.

350
DURST, R. A. , In-Situ Monitoring with Ion-Selective ElectrodesAdvantages and Pitfalls, or What the Instructions Didn't Say,

Proc. of the 8th Materials Research Symposium, National Bureau

of Standards, Sept. 20-24, 1976, in press.

DZUBAY, T. G., ROOK, H. L., STEVENS, R. K. , The Chemiluminescent

Approach to Measurement of Strong Acid Aerosols , /inaZ. Meth.

ApvjLied to Aiv Pollution Meas., ' "^^"^^ (1974), Ann Arbor

ience Publishers, Inc.

EPSTEIN, M. S., RAINS, T. C. , and O'HAVER, T. C. , A Comparison

of Accuracy in Atomic Emission and Atomic Absorption Spectrometry

Using a Graphite Furnace for Trace Metal Analysis in Water,

Proc. of the 8th Materials Research Symposium, National Bureau

of Standards, Sept. 20-24, 1976, in press.

ETZ, E. S., ROBINSON, R. A., and BATES, R. G., j. Sol. Chem.

1, 507 (1972).

ETZ, E. S., ROBINSON, R. A., and BATES, R. G., j. Sol. Chem.

2, 405 (1973).

ETZ, E. and ROSASCO, G. J., The Identification of Individual

Microparticles with a New Micro-Raman Spectrometer, Proc.

of the 8th Materials Research Symposium, National Bureau of

Standards, Sept. 20-24, 1976, in press.

FREEMAN, D. H. , CURRIE, L. A., KUEHNER, E. C., DIXON, H. D. , and

PAULSON, R. A., Development and Characterization of Ion-Exchange

Bead Microstandards, Anal. Chem. 42^, 203 (1970).

FREEMAN, D. H. , Annual Progress Report, NBS Teahniaal Note 589,

1971.

FREEMAN, D. H. , Interactive Gel Networks. I. Treatment of

Simple Complexation and Masking Phenomena, Anal. Chem.^

December 1971.

FREEMAN, D. H. , and ENAGONIO, D. P., Interactive Gel Networks

for Organic Separations, Nature, Physical Science 230 , 135

(1971).

FREUND, S. M. , and SWEGER, D. M. , Vinyl Chloride Detection Using

CO and CO2 Infrared Lasers, Anal. Chem. , 47^, 930 (1975).

FREUND, S. M. , SWEGER, D. M. , and TRAVIS, J. C. , Quantitative

Detection of Nitrogen Dioxide in Nitrogen Using Laser Magnetic

Resonance at 1616 cm"l. Anal. Chem. , 48^> 1944 (1976).

351

^UB ^A
GARVIN, D., and GEVANTMAN, L. H. , Chemical Kinetics Data Survey

III. Selected Rate Constants for Chemical Reactions of Interest

In Atmospheric Chemistry ^ ubs Revovt 10. 867 (1972), 48 p.

(CKIC) Supersedes NBS Report 9884 (1968) which is out of print

and out of date.

GARVIN, D. , Ed., Chemical Kinetics Data Survey. V. Sixty-six

Contributed Rate and Photochemical Data Evaluations on Ninetyfour Reactions, msiR 73-206 (1973), 115 p., order as COM-73-

11262 (NTIS).

GILLS, T. E., McCLENDON, L. T. , MAIENTHAL, E. J., BECKER, D. A.,

DURSE, R. A., and LaFLEUR, P. D. , Determination of Toxic Trace

Elements in Body Fluid Reference Samples, Proc. Eighth Conference

on Trace Substances in Environmental Health, University of

Missouri, Columbia, Missouri, p. 273 (June 1974).

GRAVATT, C. C. , The Applications of Light Scattering, Appl.

Spect. 25^, 509 (1971).

GRAVATT, C. C. , Real Time Measurement of the Size Distribution

of Particulate Matter" by a Light Scattering Method, japCA 23,

1035 (1973).

GRAVATT, C. C. and ALLEGRINI , I., A New Light Scattering Method

for the Determination of the Size Distribution of Particulate

Matter in Air, Proc. of the Third International Clean Air

Congress (1973).

GRAVATT, C. C. , Light Scattering Methods for the Characterization

of Particulate Matter in Real Time, NBS SP 412, 21 (1974).

GRAVATT, C. C. , System for Determining Parameters of a Particle

by Radiant Energy Scattering Techniques, U. S. Patent

#3,835,315 (1974).

GRAVATT, C. C. , Light Scattering Method and Apparatus for the

Chemical Characterization of Particulate Matter, U. S. Patent

#3,901,602 (1975).

GRAVATT, C. C. , Chemical Characterization of Particulates in Real

Time by a Light Scattering Method, Proc. of the 8th Materials

Research Symposium, National Bureau of Standards, Sept. 20-24,

1976, in press.

352
GRAVATT, C. C. , Chemical Characterization of Aerosols by Light

Scattering, Proc. of the Topical Meeting on Atmospheric Aerosols,

Their Optical Properties and Effects, Optical Society of America,

Williamsburg, Va. , Dec. 13-16, 1976; paper TuA3.

GREIFER, B. and TAYLOR, J. K. , Survey of Various Approaches to

the Chemical Analysis of Environmentally Important Materials,

NBSIR 73-209 , July 1973.

GREIFER, B., CADOFF, B. C. , WING, J., and TAYLOR, J. K.

,

Development of Solid State Samplers for Work Atmospheres,

NBSIR 74— S27 , 54 p. (1974).

GREIFER, B. and TAYLOR, J. K. , Development of Solid State Samplers

for Work Atmospheres: Phosphine, NBSIR 75-977, , 31 p. (1976).

GREIFER, B. and TAYLOR, J. K. , Sampling and Measurement Techniques

in Zinc Analysis. B. Air, Chap.ter in a book entitled "zinc"

in a series of Medical and Biological Effects of Environmental

Pollutants, . 54 p. (1975).

GREIFER, B. and TAYLOR, J. K. , Pollutant Analysis Cost Survey,

EPA-640/2-74-125, 208 p.

GUMP, B. H., HERTZ, H. S. , MAY, W. E., CHESLER, S. N. , DYSZEL,

S. M. , and ENAGONIO, D. P., Drop Sampler for Obtaining Fresh

and Sea Water Samples for Organic Compound Analysis , >inal.

CHem. 47, 1223 (1975).

GUMP, B. H., HERTZ, H. S., MAY, W. E., and CHESLER, S. N. , The

Hydrocarbon Burden in the Marine Environment Surrounding a Refinery Tanker Jetty, in press.

HAMPSON, R. F., Editor, BRAUN, W. , BROWN, R. L., GARVIN, D.

,

HERRON, J. T., HUIE, R. E., KURYLO, M. J., LAUFER, A. H.

,

Mckinley, j. d. , okabe, h. , scheer, m. d., tsang, w., and

STEDMAN, D. H. , Survey of Photochemical and Rate Data for

Twenty-Eight Reactions of Interest in Atmospheric Chemistry,

J. Phys. & Chem. Ref. Data 2, 267 (1973).

HAMPSON, R. F., Ed., Chemical Kinetics Data Survey. VI. Photochemical and Rate Data for Twelve Gas Phase Reactions of

Interest for Stratospheric Chemistry, ^bsir 72-207 (1973).

353
HAMPSON, R. F., and GARVIN, D. , Ed., Chemical Kinetics and

Photochemical Data for Modeling Atmospheric Chemistry, j^-qs

Tech. Note 866 (1975) . HAMPSON, R. F. , Ed., Photochemical and Rate Data for Twentyeight Gas Phase Reactions: A Survey of the Data, j, Phys.

Chem. Ref. Data 2, No. 2, 267 (1973).

HARRISON, S. H. , LaFLEUR, P. D. , ZOLLER, W. H. , An Evaluation

of Lyophilization for the Preconcentration of Natural Water

Samples Prior to Neutron Activation Analysis, Anal. Chem

A7_, 1685 (1975).

HARRISON, S. H. , Neutron Activation Analysis: A Useful Tool

for Evaluating Water Sampling and Analysis Techniques, Trans

Am. Nuct. Soo. . n, 110-111 (1975).

HARRISON, S. H., LaFLEUR, P. D. , and ZOLLER, W. , Sampling

and Sample Handling for Activation Analysis of River Water,

Proc. of the 7th Materials Research Symposium, NBS (1976).

HARRISON, S. H. , Determination of Vanadium and Manganese in

NBS-SRM Tissues, Sediments, and Waters by Neutron Activation

Analysis, ms PubliQation 260.

HERRON, J. T. , SCHEER, M. D. , JOHANNESEN, R. , and McKINLEY,

J., Gaseous Pollutants. Chapter IV, Report of the National

Bureau of Standards Study Group on Air Pollution, Washington,

DC, 1970.

HERRON, J. T. , Mass Spectrometric Studies of Atomic and Free

Radical Reactions, Proc. Conf. Mass Spectrometry, Brussels,

Belgium, 31 August-Sept. 4, 1970), Aavances in Mass Svecit-pgmatvv, Ed., A. Quayle, Vol. 5, pp. 453-461. (The Institute of

Petroleum, London, England, 1971).

HERRON, J. T. and HUIE, R. E., Rate Constants for the

Reactions of Atomic Oxygen (O^P) with Organic Compounds m the

Gas Phase, c7. Phys. & Chem. Ref. Data 2_, 467 (1973).

HERRON, J. T. and HUIE, R. E., Application of Beam Sampling

Mass Spectrometry to the Kinetics of Ozone Reactions,

in^, J. Mass Sipeotrom. Ion Phys. . . 16_, 125 (1975).

HERTZ, H.' S., MAY, W. E., CHESLER, S. N., and GUMP, B. H. , Analysis of yg/kg (ppb) Level Hydrocarbons in Intertidal Zone

Sediments and Water by Gas Chromatography-Mass Spectrometry,

Proc. of the Twenty-Third Annual Conf. on Mass Spectrometry

and Allied Topics, pp. 663-665, Houston, TX, 1975.

354
City, Mexico, 1975.

HIRSHFELD, A. T. , HOPPES, D. D. , and SCHIMA, F. J.,

Germanium Detector Efficiency Calibration with NBS Standards,

Proc. ERDA X-and Gamma-Ray Symp., Ann Arbor, MI, May 19-21,

1976.

HODGESON, J. A., Ozone- -Sampling Analysis and Methods

Evaluation, Proc. of the 15th Conf. Methods in Air Pollution

Studies, California Dept. of Health, Air Resources Board,

1976.

HODGESON, J. A., A Survey of Calibration Techniques for

Atmospheric Ozone Monitors, nbsir 76-1191^ 1976.

HODGESON, J. A., HUGHES, E. E., BASS, A. M. , and SCHMIDT,

W. P. , Methodology for Standardization of Atmospheric Ozone

Measurements, Proc. of the International Conf. on Oxidants,

Research Triangle Park, NC , Vol. 1, Jan. 1977 - EPA-600/3-77-00la,

HOWARD, C. J. and EVENSON, K. M. , Laser Magnetic Resonance

Study of the Gas Phase Reactions of OH with CO, NO, and NO?,

J. Chem. Phys. . ^, No. 5, 1943 (1974).

HOWARD, C. J., and EVENSON, K. M. , Rate Constants for the

Reactions of OH with CH4 and Fluorine, Chlorine, and Bromine

Substituted Methanes at 296 K, j, chem. Phys. 64, No. 1

(1976). ^ —

HOWARD, C. J. and EVENSON, K. M. , Rate Constants for the

Reactions of OH with Ethane and Some Halogen Substituted

Ethanes at 296 K, J". Chem. Phys., 64_, No. 11, 4303 (1976).

[HOWARD, C. J., Rate Constants for the Gas-Phase Reactions of OH

[Radicals with Ethylene and Halogenated Ethylene Compounds,

J. Chem. Phys. 6^, No. 11, 4771 (1976).

iHUEBNER, R. H. , MIELCZAREK, S. R. , and KUYATT , C. E., Electron

Energy-Loss Spectroscopy of Napthalene Vapor, chem, Phys.

Letters 16, No. 3, 464-469 (1972).

355
HUEBNER, R. H. , CELOTTA, R. , MIELCZAREK, S. R. , and KUYATT,

C. E. , Electron Energy Loss Spectroscopy of Acetone Vapor,

J. Chem. Phys. 59_, No. 10, 5434, 1973.

HUEBNER, R. H. , CELOTTA, R. J., MIELCZAREK, S. R. , and KUYATT,

C. E. , Oscillator Strength Values Derived from Electron

Energy Loss Spectra of Molecules, Abstracts of Papers of the

VIII International Conf. on the Physica of Electronic and

Atomic Collisions, B. C. Cobic and M. V. Kurepa, Editors,

Held at Beograd, Yugoslavia, July 1973.

HUEBNER, R. H. , FERGUSON, C. H. , CELOTTA, R. J. and

MIELCZAREK, S. R. , Apparent Oscillator Strength Distributions

Derived from Electron Energy-Loss Measurements: Methane and

n-Hexane, Conf. Digest - IV International Conference on

Vacuum-Ultraviolet Radiation Physics, Hamburg, Germany,

July 22-26, 1974.

HUEBNER, R. H. , CELOTTA, R. J., MIELCZAREK, S. R. , and

KUYATT, C. E., Dipole Oscillator-Strength Distributions

Derived for Several Hydrocarbons from Electron Energy-Loss

Spectra, Argonne National Laboratory Report ANL-75-3

(1974).

HUEBNER, R. H. , CELOTTA, R. J., MIELCZAREK, S. R. , and

KUYATT, C. E., Apparent Oscillator Strengths for Molecular

Oxygen Derived from Electron Energy-Loss Measurements,

J. Chem, Phys. • 63, No. 1, 241 (1975).

HUEBNER, R. H. , BUSHNELL, D. L., CELOTTA, R. J., MIELCZAREK,

S. R. , and KUYATT, C. E., Ultraviolet Photoabsorption by

Halocarbons 11 and 12 from Electron Impact Measurements, Nature^

Vol. 257, No. 5525, pp. 376-378 (1975).

HUEBNER, R. H., CELOTTA, R. J., MIELCZAREK, S. R. , and

KUYATT, C. E., Apparent Oscillator Strengths for Nitrous

Oxide, Proc. IX International Conference on the Physics

of Electronic and Atomic Collisions, Electronic and Atomic

Collisions, J. S. Risley and R. Geballe, eds.. University of

Washington Press, Seattle, (1975).

HUEBNER, R. H. , CELOTTA, R. J., MIELCZAREK, S. R. , and KUYATT,

C. E., Apparent Oscillator Strengths for Nitrous Oxide,

Argonne National Lab. Report, No. ANL-7S-6O3 Part I. HUEY, C. W. , BRINCKMAN, F. E., IVERSON, W. P., and GRIM,

S. 0., Bacterial Volatilization of Cadmium, Proc. Internat.

Conf. on Heavy Metals in the Environment, in press.

HUEY, C, BRINCKMAN, F. E., GRIM, S., and IVERSON, W. P.,

The Role of Tin in Bacterial Methylation of Mercury, Proc.

of Internatl. Conf. on Transport of Persistent Chemicals in

Aquatic Ecosystems, Nat. Res. Coun. Ottawa, Canada, pp. II-73-8

(1974).

356
HUGHES, E. E., DORKO, W. D. , SCHEIDE, E. P., HALL, L. C.

,

BEILBY, A. L., and TAYLOR, J. K. , Gas Generation Systems

for the Evaluation of Gas Detecting Devices, NBSIR 73-292,

(1973).

HUGHES, E. E., and TAYLOR, J. K. , Accurate Gas Standards for

Air Pollution Analyses, World Health Org., Tech. Conf. on

Obs. and Meas . of Atmos. Pollution, (1973).

HUGHES, E. E., DORKO, W. D. , TAYLOR, J. K. , System for

Preparation of Known Concentrations of Methane in Air,

NBSIR 73-255 (19 73) . HUGHES, E. E., Development of Standard Reference Materials

for Air Quality Measurement, Proc. of ISA Conference, NY,

p. 1-13 (1974).

HUGHES, E. E., The Role of the National Bureau of Standards

in Calibration Problems Associated with Air Pollution

Measurements, Proc. ASTM Symp . , Boulder,. CO (1975).

HUGHES, E. E., DORKO, W. D. , FREUND, D. , SWEGER, D.

,

Preparation and Evaluation of Vinyl Chloride Standards,

Proc. for Internatl. Symp. on Environ. Monitoring, Las Vegas,

(1975)

.

HUGHES, E. E., ROOK, H. L., DEARDORFF , E. R. , MARGESON, J. H.

,

and FUERST, R. G., Operational Characteristics of Nitrogen

Dioxide Permeation Devices, Anal. Chem. ^ 29 p. (1975).

HUGHES, E. E., and DORKO, W. D. , Long Term Investigation of

the Stability of Gaseous SRM's, Proc. of the 8th Materials

Research Symposium, National Bureau of Standards, Sept. 20-24,

1976, in press.

HUGHES, E. E., and DORKO, W. D. , Dilution Systems for the

Generation of Test Gas Atmospheres, msiR 75-963, , in

press

.

HUIE, R. E., HERRON, J. T. , and DAVIS, D. D. , Absolute Rate

Constants for the Reaction of Atomic Oxygen with 1-Butene

over the Temperature Range of 259-493°K, J. Phys, Chem. 75,

3902 (1971).

'

HUIE, R. E., HERRON, J. T. , Rates of Reaction of Atomic Oxygen

III. Spiropentane , Cyclopentane, Cyclohexane, and Cycloheptane

,

J. Res. NBS 7 6A, 77 (1972).

HUIE, R. E., HERRON, J. T., and DAVIS, D. D. , Rates of

Reaction of Atomic Oxygen with C2H3F, C2H3CI, C2H3Br,

1,1-C2H2F2, and 1,2-C2H2F2, Int. J. Chem. Kinetics IV,

521 (1972).

357
HUIE, R. E., HERRON, J. T. , and DAVIS, D. D. , Absolute Rate

Constants for the Reaction + 02+M-^03+M Over the

Temperature Range 200-346°K, j. Phys. Chem, 76, 2653 (1972).

HUIE, R. E., HERRON, J. T. , and DAVIS, D. D. , Absolute

Rate Constants for the Addition and Abstraction Reactions

of Atomic Oxygen with 1-Butene Over the Temperature Range

of 190-491 K, J. Phys. Chem. 76, 3311 (1972).

HUIE, R. E. and HERRON, J. T. , Kinetics of the Reactions of

Singlet Molecular Oxygen (02-'-Ag) with Organic Compounds in the

Gas Phase, Int. J. Chem. Kinetics V, 197 (1973).

HUIE, R. E. and HERRON, J. T., The Rate Constant for the

Reaction O3 + NO2 -^02+ NO3 Over the Temperature Range

259-362°K, 'Chem. Phys. Lett. 2_7, 411 (1974).

HUIE, R. E., and HERRON, J. T, , Temperature Dependence of the

Rate Constants for Reactions of Ozone with Some Olefins, Proc.

Symp. on Chemical Kinetics Data for the Upper and Lower

Atmosphere, Warrenton, Virginia, Sept. 15-18, 1974, Ed.

Sidney W. Benson, International Jourmxl of Chemical Kinetios^

Symposium No. 1, pp. 165-181 (John Wiley § Sons, Inc., NY,

1975)

.

HUIE, R. E. and HERRON, J. T. , Reactions of Atomic Oxygen

(O^P) with Organic Compounds , Progress in Reaction Kinetics

K. R. Jennings and R. B. Cundall, Editors, Vol. 8, Part 1,

pp. 1-80 (1975). Pergamon Press, London, Great Britain.

HURLOC, S. C, LAFFERTY, W. J., and RAO, K. N. , Analysis of

the V3 Band of 14^1602, J. Mol. Spectrosc. 50, 246 (1974).

HUNT, C. M. , CADOFF, B. C. , POWELL, F. J., Indoor Air

Pollution Status Report, NBS Report 10 591, April 1971.

HUTCHINSON, J. M. R. , LANTZ , J. L., MANN, W. B., MULLEN,

P. A., and RODRIGUEZ-PASQUES, R. H. , An Anti-Coincidence

Shielded Nal(Tl) System at NBS, IEEE Transactions on Nuclear Science^ NS-19 No. 1, p. 117 (1972).

HUTCHINSON, J. M. R. , MANN, W. B., and PERKINS, R. W.,

Low-Level Radioactivity Measurements, 1st International

Summer School on Radionuclide Metrology, Herceg-Novi,

Yugoslavia, Aug. 21 -Sept. 1, 1972. Nucl. Instr. and

Meth., Vol. 112, p. 305 (1973).

HUTCHINSON, J. M. R. , MANN, W. B., and MULLEN P. A., SumPeak Counting with Two Crystals, 1st International Summer

School on Radionuclide. Nucl. Instr. and Meth. ,

' Vol. 112,

p. 187 (1973).

358
HUTCHINSON, J. M. R. , NBS Activities Relating to the Measurement of Radioactive Effluents from Power Plants, NBS

Special Publication^ Workshop on SRM's for Power Plant

Operation, Feb. 19-20, 1976.

HUTCHINSON, J. M. R. , MANN, W. B., and MULLEN, P. A.,

Development of the National Bureau of Standards Low-EnergyPhoton-Emission-Rate Radioactivity Standards, Proc . of

the ERDA Symposium on X- and Gamma-Ray Sources and

Applications, p. 25, Ann Arbor, Michigan, May 19-21, 1976.

HUTCHINSON, J. M. R. , Tritium Measurement Techniques, NCFP

Report No. 47, (1976) . HUTCHINSON, J. M. R. and MULLEN, P. A., Standardization arid

Ground-State Branching of Selenium- 75, int. J. Appl. Rad.

Isotopes 27_, 4 7 (19 76).

IVERSON, W. P., HUEY, C. W. , BRINCKMAN, F. E., JEWETT, K. L.,

and BLAIR, W. , Biological and Non-Biological Transformations

of Mercury in Aquatic Systems, Suppl. Vol. 7, Krenkel, Ed.,

193 (1975).

IVES, J. M. , HUGHES, E. E., TAYLOR, J. K., Toxic Atmospheres

Associated with Real Fire Situations, U. S. National Bureau

of Standards Report 10 807, 1-77 (1972).

JACOX, M. E. and MILLIGAN, D. E., Matrix-isolation Study of

the Vacuum Ultraviolet Photolysis of Chloroform, Infrared

Spectra of the CCI3, HCClJ, and HCCI2 Molecular Ions,

J. Chem. Phys. 54-, 3935 (1971).

JEWETT, K. L. and BRINCKMAN, F. E., Transmethylation of

Heavy Metal Ions in Water, Div. of Environmental Chemistry,

ACS, Preprints of Papers 14-, 218 (1974).

JEWETT, K. L., BRINCKMAN, F. W. , and BELLAMA, J. M.

,

Chemical Factors Influencing Metal Alfylation in Water, Proc.

ACS Symp. (T. Church, Ed.), Series, No. 18, pp. 304-318 (1975),

JOHNS, R. H., TAYLOR, J. K., Reference Materials for

Collaborative Tests of Air Quality Methods, TN 840 (1974).

KALDOR, A., OLSON, W. B., and MAKI , A. G., Pollution Monitor

for Nitric Oxide: A Laser Device Based on the Zeeman

Modulcation of Absorption, Science 176, 508 (1972).

KALDOR, A., and MAKI, A. G., High Resolution Infrared Spectrum

and the Molecular Structure of Sulfur Trioxide, J. Mol.

Struct. 15^, 123 (1973).

359
KALDOR, A., MAKI, A. G., DORNEY, A. J., and MILLS, I. M.,

The Assignment of v2 and V4 of SO3, J. Mot. Speatroso. . 45 , 247 (1973).

KALDOR, A., BRAUN, W. , and KURYLO, M. J., Infrared Laser

Enchanced Reactions: O3 + SO, J. Chem. Phys. 61, 2496 (1974).

KIRCHHOFF, W. H. , Ed., Proc . of the 8th Materials Research

Symposium, National Bureau of Standards, Sept. 20-24, 1976,

in press.

KIRCHHOFF, W. H. , Office of Air and Water Measurement Annual

Report, FY-74-75-76 , in press.

KIRCHHOFF, W. H. , An Overview of the NBS Water Pollution

Measurement Program, Proc. of the Workshop on SRM's for

Off-Shore Drilling- -Petroleum, in press.

KULIN, G. , and COMPTON, P. R., A Guide to Methods and Standards

for the Measurement of Water Flow, NBS SP-421, May 1975.

KULIN, G., Simplified Application of Palmer-Bowlus Flow

Meter, WPCF Jouimal 48, 201, 1976.

KURYLO, M. J., PETERSON, N. C, and BRAUN, W. , Temperature

and Pressure Effects in the Addition of H Atoms to Propylene,

J. Chem. Phys._ 54-, 4662 (1971).

KURYLO, M. J., PETERSON, N. C. , and BRAUN, W. , Absolute Rate

of the Reaction H + H2S, J. Chem. Phys. 54-, 943 (1971).

KURYLO, M. J., Absolute Rate Constants for the Addition of

0(3p) Atoms to Propylene, Chem. Phys. Letters 1£, 117 (1972).

KURYLO, M. J., Absolute Rate Constants for the Reaction of

H + O2 + M -^ HO2 + M Over the Temperature Range 203-404 K,

J. Phys.^ Chem. 76, 3518 (1972).

KURYLO, M. J. and HUIE, R. E., Flash Photolysis Resonance

Fluorescence Study of the Addition of 0(3p) atoms to C2H4 and

C2D4 at 298°K, J. Chem. Phys. 58^, 1258 (1973).

KURYLO, M. J., Kinetics of the reactions OH(v=0) + NH -> H2O + NH2 and OH(v=0) +03^ HO2 + O2 at 298 °K, Chem. Phys. Lett.'

23, 467 (1973).

360
KURYLO, M. J., BRAUN, W. , FREUND, S. M. , and WAYNE, R. P.,

Infrared Laser Enhanced Reactions: Chemistry of Vibrationally

Excited O3 with NO and 02(1a), j. Photoohem. 3, 71 (1974/75)

KURYLO, M. J., BRAUN, W. , and KALDOR, A., A Laser Enhanced

Reaction Technique for the Measurement of V->-T Deactivation

Rates: Deactivation of Vibrationally Excited O3, Chem. Phys.

Lett. 27, 249 (1974).

KURYLO, M. J., BRAUN, W. , XUAN, C. N. , ajid KALDOR, A., Infrared

Laser Enhanced Reactions: Temperature Resolution of the

Chemical Dynamics of the 0^ + NO Reaction System, j. Chem,

Phys. 62, 2065 (1975).

KURYLO, M. J., and BRAUN, W. , Flash Photolysis Resonance

Fluorescence Study of the Reaction CI + O3 -» CIO + O2 Over

the Temperature Range 213-298K, chem. Phys. Lett. 37, 232

(1976).

KURYLO, M. J. and MANNING, R. G., Flash Photolysis Resonance

Fluorescence Investigation of the Reaction of Cl(2p) Atoms

with CIONO2, Chem. Phys. Lett (submitted).

KUYATT, C. E., CELOTTA, R. J., and MIELCZAREK, S'. R. , Application of Electron Spectroscopy to Air Pollution Measurements, T}iQ physias of Eteotronia and Atomia Collisions.

Invited Lectures and Progress Reports of the VIII International Conference, Belgrade, Yugoslavia, 1973, B. C. Cobic

and M. V. Kurepa, editors, published by the Institute of

Physics, Belgrade, Yugoslavia.

KUYATT, C. E., MIELCZAREK, S. R. , and WEISS, M. , Intensities

of Infrared Transitions in N2O and H2CO by Electron Impact

Spectroscopy, j, chem. Phys. 65, No. 9, 3481-3485, (1976).

KRAUSS, M. , MIELCZAREK, S. R. , NEUMANN, D. , and KUYATT, C. E.

,

Mechanism for Production of the Fourth Positive Band System

of CO by Electron Impact on CO2 , j. Geophysiaal Pes. 76,

No. 16, 3733-3737 (1971). "

"

KRAUSS, M. , CELOTTA, R. J., MIELCZAREK, S. R. , and KUYATT,

C. E., Electron Impact Energy Loss Spectra of the i2B2 -^ X^^A^

Transition in NO2, Chem. Phys. Lett, 27, No. 2, 285-288

(1974).

"^ —

LAFFERTY, W. J. and SAMS, R. L., High Resolution Infrared

Spectrum of the 2v^ Band of NO, , j moI Phys 28, 861

(1974). ^ z • • y • —

361
LaFLEUR, P. D. , Reference Materials for the Determination of

Trace Elements in Biological Fluids, ^BSIR 73-406 (1973).

LUCAS, L. L. and HUTCHINSON, J. M. R. , Study of the Scattering

Correction for Thick Uranium-Oxide and Other Alpha-Particle

Sources (Part I: Theoretical); HUTCHINSON, J. M. R. , LUCAS,

L. L. , and MULLEN, P. A., -^«^- =^- Appl. Had. Isotopes 27,

35 (Part I) and 43 (Part II) (1976).

LUTZ, G. J., STEMPLE, J. S. , and ROOK. H. L., Evaluation by

Activation Analysis of Elemental Retention in Biological

Samples After Low Temperature Ashing, to be published in

J. Radioanal. Chem.

MACHLAN, L. A., GRAMLICH, J. W. , MURPHY, T. J., BARNES, I. L.,

The Accurate Determination of Lead in Biological and

Environmental Samples by Isotope Dilution Mass Spectrometry,

Proc. of the 7th Materials Research Symposium, National Bureau

of Standards, Oct. 7-11, 1974, NBS Speo. Publ. 422, ^ u. S.

Government Printing Office, Washington, DC 20402.

MACHTA, L., and HUGHES, E. E., Atmospheric Oxygen in 1967 to

1970, Saienoe 16_8, 1582-4 (1970).

MAIENTHAL, E. J., Analysis of Botanical Standard Reference

Materials by Cathode Ray Polarography , J- Assoc Off. Anal.

Chem. 55., No. 5, 1109-1133 (1972).

MAIENTHAL, E. J., TAYLOR, J. K., Electrochemical Techniques

in Water Analysis, Water and Water Pollution Handbook Ch. 32,

Ciaccio, L. L., Editor, Vol. 4, 1751-1800, Marcel Dekker,

NY (1972).

MAIENTHAL, E. J., The Application of Linear Sweep Voltammetry to the

Determination of Trace Elements in Biological and Environmental

Materials, Trace Substances in Environmental Health - VIII,

A Symposium, D. D. , Hemphill, Ed., Univ. of MO, Columbia (1974).

MAIENTHAL, E. J., and BECKER, D. A. , A Survey of Current

Literature on Sampling, Sample Handling, and Long Term Storage

for Environmental Materials, NBS Tech. Note 929, U. S. Government

Printing Office, Washington, DC 20402 (1976).

MANN, W. B., The Calibration of the National Bureau of Standards

Tritium Standards by Microcalorimetry and Gas Counting,

Proc. of the Tritium Symposium, Las Vegas, Nevada, Aug. 30 - Sept. 2, 1971, Messenger Graphics, publishers, Phoenix,

Arizona, and Las Vegas, Nevada (p. 86, May 1973)

.

362

01

Tc

HAy

HER

Ana
MANN, W. B., SCHIMA, F. J., and UNTERWEGER, M. P., Radioactivity Standards of the Noble Gases, Noble Gases Symposium,

Las Vegas, Nevada, Sept. 24-28, 1973. (To be published in

Symposium Proceedings)

.

MANN, W. B. , Radionuclide Metrology and Quality Assurance,

Environmental Monitorina Series, EPA-B70/4-75-006 (June 1975).

Symposium "Activities and T^Ieeds Related to Radioactivity

Standards for Environmental Measurements" - Washington, DC,

Aug. 21, 1973.

MANN, W. B., Radioactivity Standards for Use in Monitoring

the Environment, Proc. of the EPA/NBS Energy-Environment

Workshop- -SRM' s Uranium Mining, nbs Svea Puhl • March

22-23, 1976. ' " ' "

MANN, W. B., Reliability and Traceability in Radioactivity

Measurements, Proc. of the Southeastern Workshop on the

Utilization and Interpretation of Environmental Radiation Data.

Orlando, Florida, March 1-3, 1976.

MANN, W. B., The Standardization of Iodine-129 by Beta-Photon

Coincidence Counting, int. J. Awl. Rad. Isotoves 27, 187

(1976). "' "

" MANNING, R. G., BRAUN, W. , and KURYLO, M. J., The Effect of

Infrared Laser Excitation on Reaction Dynamics: + C2H4+

and + OCS"^, J. Chem. Phys.. 6S_, 2609 (1976).

MANNING, R. G. and KURYLO, M. J., Flash Photolysis Resonance

Fluorescence Investigation of the Temperature Dependencies

of the Reactions of Cl(^P) Atoms with CH4 , CH3CI , CH3F,

CH3F+ and C2H6, J. Phys. Chem. 81, (1977).

MARINENKO, G., HUGGETT, R. J., and FRIEND, D. G., An

Instrument with Internal Calibration for Monitoring Chlorine

Residuals in Natural Waters, j. Fish. Res. Board Can. 33,

4, 822-826 (1976).

MAVRODINEANU, R. , BALDWIN, J. R. , and TAYLOR, J. K.

,

Development of Reference Materials for Atmospheric Analysis

of the Occupational Environment: Filter Samples Containing

Toxic Metals, NBSIR 72-256 ,1973).

MAY, W. E., CHESLER, S. N. , CRAM, S. P., GUMP, B. H.

,

HERTZ, H. S., ENAGONIO, D. P., and DYSZEL, S. N. , Chromatographic

Analysis of Hydrocarbons in Marine Sediments and Seawater,

T. Chromatog. Soi. 13, 535 (1975).

363

BHB^DHiaBOl
MAY, W. E., GUMP, B. H. , CHESLER, S. N. , and HERTZ, H. S.

,

Analysis of Polynuclear Aromatic Hydrocarbons in Marine

Samples by Coupled-Column Liquid Chromatography, NBS Speaial

Publication on NBS/EPA Workshop on SRM's for Offshore

Petroleum^ in press.

McNESBY, R. J., Pollution Measurements Lack Standards,

Chemical and Engineering News, May 10, 19 71.

McNESBY, J. R. and LICHTENSTEIN, S. , Measures for Air Quality

Program at NBS: Getting Solid Readings on Air Pollution,

Pollution Abstracts, 1971.

McNESBY, J. R. and BYERLY, R. , Measures for Air Quality,

Annual Report--FY 1971, NBS Tech.. Note 711, ^ 1972.

McNESBY, J. R. , Standard Reference Materials for Air Pollution,

Proc. of the Technical Conf. on the Observation and Measurement of Atmospheric Pollution, Helsinki, July 30-Aug. 4,

1973.

McNESBY, J. R. , Problems in the Measurement of Free Radical

Concentrations in the Atmosphere, Berichte der BunsenGesetlschaft fur Physikalische Chemie, Bd. 78, Nr. 2, 158

(1974).

McNESBY, J. R. and HUGHES, E. E., Calibration Gas Standards,

ISA Conference, NY, p. 1-5 (1974).

McNESBY, J. R. , Measures for Air Quality, Annual Report--

FY 72-73, NBS Techn. Note 828, May 1974.

McNESBY, J. R. , Summary Remarks--lst Interagency Symposium on

Air Monitoring Assurance, Proc. of the Conference, Berkeley,

1975.

McNESBY, J. R. , The Role of SRM's in Environmental Measurement,

Proc. of Fed. Interagency Symposium on Health/Environmental

Effects and Control Aspects of Energy R § D, Feb. 1976.

McNESBY, J. R. , Ozone and Other Photochemical Oxidants,

NAS Report, , in press.

MIELCZAREK, S. R. and MILLER, K. J., Dependence on Generalized

Oscillator Strengths of H2O on Momentum Transfer, Chem. PJiys.

Lett, i^» N°- ^» 2^9 (1971) . ^

364
MILLIGAN, D. E., JACOX, M. E., McAULEY, J. H. , and SMITH, C. E.,

Matrix Isolation Study of the Vacuum-Ultraviolet Photolysis of

HCCIF2 and of HCCI2F. Infrared Spectra of the Parent

Molecules and of the CICF2 and FCCI2 Free Radicals, j moI

Speotros. £5, 377 (1973).

MOODY, J. R. , PAULSEN, P. J., RAINS, T. C, and ROOK. H. L.,

The Preparation and Certification of Trace Mercury in Water

Standard Reference Materials, Proc. of the 7th Materials

Research Symposium, National Bureau of Standards J^^^ ^P ^22 (Aug. 1976,

MOODY, J. R. , ROOK. H. L., PAULSEN, R. J., RAINS, T. C,

BARNES, I. L., and HANAMURA, S., The Preparation and

Certification of a Trace Elements in Water Standard Reference

Material, Proc. of the 8th Materials Research Symposium,

National Bureau of Standards, Sept. 20-24, 1976, in press.

MYKLEBUST, R. L., DARR, M. M. , and HEINRICH, K. F. J.,

Evaluation of X-Ray Fluorescence Analysis for the

Determination of Mercury in Coal, NBSIR 74-675 (1974).

NELSON, J. D., BLAIR, W. , BRINCKMAN, F. E., COLWELL, R. R.

,

and IVERSON, W. P., Biodegradation of Phenylmercuric Acetate

by Mercury-Resistant Bacteria, Applied Microbiology 26 , 321 (1973).

NOYCE, J. R. , HUTCHINSON, J. M. R. , MANN, W. B., and MULLEN,

'P. A., Development of a National Bureau of Standards

Environmental Radioactivity Standard: River Sediment,

Proc. of the International Conference on Environmental

Sensing and Assessment, Las Vegas, Nevada, Sept. 15-19,

:1975. IEEE, Inc., Annals. No. 75CH1004-I 19-5.

OKABE, H. , Fluorescence and Predissociation of Sulfur

Dioxide, J. Amer. Chem. Soo. 93' ^095 (1971).

OKABE, H., SPLITSTONE, P. L., and BALL, J. J., Ambient and

Source SO2 Detector Based on a Fluorescence Method, JAPCA

23, No. 6, 514 (1973)

y

OKABE, H. Fluorescence Quenching of Sulfur Dioxide by Source

Emission Gases, ^nal. Chem. 48, 1457 (1976).

PARRIS, G. E. and BRINCKMAN, F. E., Reactions Which Relate

to the Environmental Mobility of Arsenic and Antimony. I.

Quanternization of Trimethylarsine and Trimethylstibine , J.

Org. Chem. . 40, 3801 (1975).

365
PARRIS, G. E. and BRINCKMAN, F. E., Reactions Which Relate

to the Environmental Mobility of Arsenic and Antimony. II.

Oxidation of Trimethylarsine and Trimethylstibine , Enviv.

Soi. & Tech. (1976) .

PARRIS, G. E., BLAIR, W. R. , and BRINCKMAN, F. E., Chemical

and Physical Consideration in the Use of Atomic Absorption

Detectors Coupled with Gas Chromatographic Systems for

Speciation of Trace Organometals , Arval. Chem. 49_, in press.

PAULE R C Low Level Calibration Mixtures for Gaseous

Pollutants, •;^^^, C^^^^ 44, 1537 (1972).

PELLA, P. A., HUGHES, E. E., and TAYLOR, J. K., A Gas

Dilution System for Hydrogen Fluoride-Air Mixtures, NBSIR

73-261, (1973).

PELLA, P. A., HUGHES, E. E., and TAYLOR, J. K., A Gas Dilution

System for Arsine-Air Mixutres , NBSIR 73-260 (1973).

PELLA, P. A., HUGHES, E. E., and TAYLOR, J. K. , Development of

Gas-Blending Systems for Calibration: Application to

Hydrogen Fluoride, Arsine and Phosgene in Air, American

Industvi-dl Eygiene Association Joiamal, , p. 755-759 (1975).

PELLA, P. A., HEINRICH, K. F. J., Quantitative Multielement

Analysis of Environmental Samples by X-Ray Fluorescence

Spectrometry, Proc. of the 8th Materials Research Symposium,

National Bureau of Standards, Sept. 20-24, 1976, in press.

PELLA, P. A., KUEHNER, E. C, and CASSATT, W. A., Development

of a Particulate Reference Sample on Membrane Filters for

the Standardization of X-Ray Fluorescence Spectrometers,

Adv. X-Ray Anal. 19_, 463 (1976).

RADFORD, H. E., EVENSON, K. M. , HOWARD, C. J., HO2 Detected

by Laser Magnetic Resonance, J. Chem. Phys. . 60, No. 8, 3178

(1974). —

RAINS, T. C, OLSON, C. D. , VELAPOLDI , R. A., WICKS, S. A-.,

MENIS, 0., and TAYLOR, J. K., Preparation of Reference

Materials for Stationary Source Emission Analysis: Beryllium,

NBSIR 74-439 (19 74) . RAYBOLD, R. L. and BYERLY, R. , Investigation of Products

of Tire Wear, NBS Rept 10 834, April 1972.

REBBERT, R. E. and AUSLOOS, P. J., Photodecomposition of

CFCI3 and CF2CI2, ^' Photochem. 4, 419 (1975).

366
REBBERT, R. E. and AUSLOOS, P. J., Gas-Phase Photodecomposition

of Carbon Tetrachloride, J- Photoohem. 6, 265 (1976/77).

RITTER, J. J. and ADAMS, N. K. , Exponential Dilution As A

Calibration Technique, Anal. Chem. £8, 612 (1976).

RODRIQUEZ-PASQUES, R. H. , STEINBERG, H. L., HARDING, J. E.,

MULLEN, P. A., HUTCHINSON, J. M. R. and MANN, W. B. , LowLevel Radioactivity Measurements on Aluminum, Steel and

Copper, Int. J. Appl. Bad. Isotopes^ 23^, 445 (1972).

ROOK, H. L., LaFLEUR, P. D. , GILLS, T. E., Mercury in Coal:

A New Standard Reference Material, Environ. Lett. . 2,4,

195 (1972).

ROOK, H. L., GILLS, T. E., LaFLEUR, P. D. , Method for the

Determination of Mercury in Biological Materials by Neutron

Activation Analysis, Anal. Chem. . (1972).

ROOK, H. L., and MOODY, J. R. , Stabiliz-ation and Determination

of Nanogram Quantities of Mercury in Water, Proc. Nuclear

Methods in Environmental Research, Univ. of Missouri, Columbia,

Conf. 740701 , 44-53 (1974).

ROOK, H. L., MOODY, J. R. , PAULSEN, P. J., and RAINS, T. C.

,

A Study to Define the Long Term Stability of a Mixed Trace

Element Water Standard, to be published in Proc. of the

Mineral Cycling Symposium 4/28-30/76, Savannah River Lab.

ROOK, H. L., The Determination of Iodine in Biological and

Environmental Standard Reference Materials, to be published

in J. Radioanal. Chem.

ROOK, H. L. , LaFLEUR, P. D. , Establishing and Operating a Specimen Bank for Environmental Monitoring, to be published

in the Proc. of International Workshop on Biological Collection

Specimens

.

ROOK, H. L., and GOLDSTINE, G. , Environmental Specimen Bank

Workshop, to be published as ms Teoh. Note.

ROOK, H. L., SUDDUETH, J. E., and BECKER, D. A., Determination

of Iodine-129 at Natural Levels Using Neutron Activation

and Isotopic Separation, Anal. Chem. 4_7, 1557 (1975).

ROSASCO, G. J., ETZ, E. S., and CASSATT, W. A., The Analysis

of Discrete Fine Particles by Raman Spectroscopy, Appl. Speot.

29, 5, 396-404 (1975).

367
RUTHERFORD, W. M. , EVANS, J., and CURRIE, L. A., Isotopic

Enrichment and Pulse Shape Discrimination for Measurement of

Atmospheric Argon-37, Anal. Chem. . 48^, 607, (1976).

SAMS, R. L. and LAFFERTY, W. J., High-Resolution Infrared

Spectrum of the v2 + V3 Band of '^Nl^02, J- Mot. Spectroso.

56, 399 (1975).

SEIDEL, C. W. and HUTCHINSON, J. M. R. , American National

Standards Institute Quality Assurance Program in Radioactivity Measurements, Proc. of the Symposium for the Safe

Use of Radiation, NBS Special Publiaation 456^ , p. 77 (1976).

SCHEIDE, E. P., HUGHES, E. E., and TAYLOR, J. K. , A Gas

Dilution System for Methyl Bromide, NBSIR 73-259, (1973).

SCHEIDE, E. P., HUGHES, E. E., and TAYLOR, J. K. , A Gas

Dilution System for Acrolein, mSIR 73-258 .1973).

SCHEIDE, E. P. and TAYLOR, J. K. , A Piezoelectric Sensor for

Mercury in Air, Environmental Soienoe & Technology, 8,

1097 (1974).

SCHEIDE, E. P. and TAYLOR, J. K., A Piezoelectric Crystal

Dosimeter for Monitoring Mercury Vapor in Industrial

Atmospheres, Am. Ind. Hygiene Assoc. J., 36, No. 12, p. 897

(1975).

Scheide, E. P . , The Piezoelectric-Crystal Mercury Dosimeter,

The Physios Teacher 1^, 1, 47-51 (1977).

Scheide, E. P. and Durst, R. A., Indirect Determination of

Sulfate in Natural Waters by Ion-Selective Electrode, Analytical Letters 1_0, 1, 55-65 (1977).

SCHWARZ, F. P., OKABE, H. , and WHITTAKER, J. K. , Fluorescence

Detection of Sulfur Dioxide in Air at the Parts Per Billion

Level, Anal. Chem. 46, 1024 (1974).

SCHWARZ, F. P., and OKABE, H. , Fluorescence Detection of

Nitric Oxide in Nitrogen, ^ml. Chem. . £7, 703 (1975).

SCHWARZ, F. P. and WASIK, S. P., Fluorescence Measurements of

Benzene, Naphthalene, Anthracene, Pyrene , Fluoranthene , and

Benzo [ejpyrene in Water, Anal. Chem. 4^, 524 (1976).

SCHWARZ, F. P. and WASIK, S. P., Fluorescence Measurements of

Carcinogenic and Polycyclic Aromatic Hydrocarbons in Water,

Proc. International Conf. on Environmental Sensing and

Assessment, 2^, Sept. 14-19, 1975, Las Vegas, NV. , Session 30-2,

pp. 1-5 (Institute of Electrical § Electronics Engineers, Inc.,

NY, 1976).

368
SCHWARZ, F. P. and WASIK, S. P., A Fluorescence Method for

the Measurement of the Partition Coefficients of Naphthalene,

1-Methylnaphthalene , and 1-Ethylnaphthalene in Water, J' Ch^m.

Eng. Data , in press.

SCHWARZ, F. P., Determination of Temperature Dependence of

Solubilities of Polycyclic Aromatic Hydrocarbons in Aqueous

Solutions by a Fluorescence Method, J- Chem. Eng. Data^ ^ in

review.

SMALL, J. and ZOLLER, W. , The Use of Scanning Electron

Microscopy and X-Ray Microanalysis in the Characterization

of Coal Ash, Proc . of the 8th Materials Research Symposium,

National Bureau of Standards, Sept. 20-24, 1976, in press.

SUENRAM, R. D. , and JOHNSON, D. R. , Laboratory Microwave

Spectrum of CIONO2 and Evidence for the Existence of ClONO,

Geoyhysioal Researah Letters 3^ 611 (1976).

SUENRAM, R. D. and JOHNSON, D. R. , ERRATUM: Laboratory

Microwave Spectrum of CIONO2, Geophysieal Researah Letters

3, 768 (1976).

SUENRAM, R. D. and JOHNSON, D. R. , Microwave Spectrum of

Chlorine Nitrate (CINO3) , to be published in J- Mot.

SpectrosG. 19 77.

SWANSON, N. and CELOTTA, R. J. , Observation of Excited States

m Oxone Near the Dissociation Limit

,

Phys. Rev . Letters

35 , No. 12, Sept. 1975.

SWEGER, D. M. , FREUND, S. M. , and TRAVIS, J. C, Highly

Selective Quantitative Measurement of Atmospheric Pollutants

Using CO and CO2 Lasers, Proc. 8th Materials Research

Symposium, National Bureau of Standards, Sept. 20-24, 1976,

in press.

TAYLOR, J. K., ALVAREZ, R. , PAULSON, R. A., RAINS, T. C,

ROOK, H. L., Interaction of Nitrilotriacetic Acid with Suspended

and Bottom Material, Water Pollution Control Research Series

16020 GFR 07/7I3 Environmental Protection Agency Progress

Report, l-Zl, u. S. Government Printing Office, Washington,

DC 20402 (1971)

.

TAYLOR, J. K., ZIELINSKI, W. L., MAIENTHAL, E. J., DURST,

R. A., and BURKE, R. W. , Development of Methods for NTA

Analysis in Raw Water, EPA Report R- 2- 7 2- 057, Sept. 1972.

369
TAYLOR, J. K., DEARDORFF, E. R. , OLSON, C. D. , and BURKE, R. W.

,

Preparation of Simulated Environmental Filters Containing

Quartz and Clay, nbsir 73-400 (1973).

TAYLOR, J. K. and DEARDORFF, E. R. , Sulfur Dioxide Reference

Materials, NBSIR 75-662 (1975).

TAYLOR, J. K. , Water Pollution SRM's, in Standard Reference

Materials and Meaningful Measurements, R. W. Seward, Editor,

NBS Spec. Publ. 408 (1975).

TAYLOR, J. K., Evaluation of Data Obtained by Reference

Methods, ASTM (1975) . TAYLOR, J. K. and ROOK, H. L., Development of a Reference

Material for Sediment Analysis (1975).

TAYLOR, J. K., DEARDORFF, E. R. , DURST, R. A., MAIENTHAL, E. J.,

RAINS, T. C. and SCHEIDE, E. P., Simulated Precipitation

Reference Materials , /i/BS'Ji? 75-958 (1975).

TAYLOR, J. K., The Status of Reference Materials for

Environmental Measurements, Proc. of the 8th Materials

Research Symposium, National Bureau of Standards, Sept. 20-24,

1976, in press.

TSANG, W. and WASIK, S. P., The Application of the Isotope

Dilution GLC Technique to Air Pollution Analysis, J.

Chromatog. Soi. . 9, 567 (1971).

TSANG, W. , A Simple Technique for the Generation of Dilute

Mixtures of Pollutant Gases, J. Res. NBS 78A, 157, April 1974.

TSANG, W. and WALKER, J. A., Instrument for the Generation

of Reactive Gases, Anal. CHem. 49 (1977).

VELAPOLDI, R. A., TRAVIS, J. C. , CASSATT, W. , AND YAP, W.

,

Inorganic Ion-doped Glass Fibers as Microspectrofluorimetric

Standards, j. Miorosoopy^ April 1975.

WALL, L. A., FLORIN, R. E., ALDRIDGE, M. H. , and FETTERS, L. J

Pyrolysis of Monodisperse Poly-a-Methylstyrene, NBS J. of

Researah.

WASIK, S. P. and TSANG, W. , Determination of Trace Amounts of

Contaminants in Water by Isotope Dilution Gas Chromatography,

Anal. Chem. 42^. 1649 (1970).

WASIK, S. P. and TSANG, W. , Gas Chromatographic Determination

of Partition Coefficients of Some Unsaturated Hydrocarbons

and Their Deuterated Isomers in Aqueous Silver Nitrate

Solutions, J. Phys. Chem. 74-, 2970 (1970).

370
WASIK, S. P. and TSANG, W. , Gas-Liquid Chromatography

Separations of Hydrocarbons Using Columns with Aqueous

Solutions of Complexing Metal Ions as Stationary Phases,

Anal. Chem. . 42^, 1648 (1970).

WASIK, S. P. and BROWN, R. L., Determination of Hydrocarbon

Solubility in Sea Water and the Analysis of Hydrocarbons in

Water-Extracts, Proc. 1973 Conf. on Prevention § Control

of Oil Spills, March 13-15, 1973, Washington, DC, Section

on Identification of Oil, pp. 223-227, the American

Petroleum Institute, Washington, DC.

WASIK, S. P. , Determination of Hydrocarbons in Sea Water

using an Electrolytic Stripping Cell, j.. chromatoa. Sai.

12^, 845 (1974).

WASIK, S. P. and BOYD, R. N. , Determination of Aromatic

Hydrocarbons in Sea Water Using an Electrolytic Stripping

Cell, NBS Speo. Pnhl. 409, . Proc. 1974 Symposium and Workshop

on Marine Pollution Monitoring (Petroleum), May 13-17, 1974,

NBS Gaithersburg, MD, pp. 117-118.

WASIK, S. P., BROWN, R. L., and MINOR, J. I., Jr., Partition

Coefficients and Solubility Measurements of Dimethylmercury

in Fresh and Sea Water Over a Temperature Range 0-25°C,

Environmental Lett. 11 . WASIK, S. P. and SCHWARZ, F. P., The Analysis of Hydrocarbons

in Sea Water by a Head-space Method, Proc. NBS-EPA Workshop

on Standard Reference Materials for Offshore Drilling for

Petroleum, Oct. 6-7, 1975, Santa Barbara, CA, NBS Sp_ea.

Publ. ^ . in press.

WASIK, S. P., Determination of Transition Temperatures on

Sodium Stearate Using Gas Chromatography, j. Chvomatog.

Sd., , in press.

WASIK, S. P. and BROWN, R. L., The Analysis of Complex Aromatic

Hydrocarbon Mixtures Using Solid Silver Nitrate Columns,

Anal. Chem. ^ in press.

WASIK, S. P. and CHESLER, S., Use of a Nematic Liquid Crystal

for Gas-Liquid Chromatographic Separation of Naphthalene

Homologues, j. Chromatography:, in press.

WATSON, R. T., Chemical Kinetics Data Survey. VIII. Rate

Constants of ClOx of Atmospheric Interest, nbsir 74-516 1974),

45 p.

371
WEISS, M. J., MIELCZAREK, S. R. , and KUYATT, C. E., Inelastic

Electron Scattering from Nitrous Oxide Between 5.0 and 20.0 eV

Energy Loss, j, chem. Vhys • 11, No. 3, (1971).

WEISS, M. J., KUYATT, C. E., and MIELCZAREK, S., Inelastic

Electron Scattering from Formaldehyde, J. Chem. Phys. . 54,

No. 10, 4147 (1971).

WING, J. and TAYLOR, J. K. , Development of a Solid Sorption

Tube for Sampling Hydrogen Fluoride in the Work Atmosphere,

NBSIR 74-681^ , 58 p. (1974).

I

372
NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. TN 963

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Air and Water Pollution —^Annual Report, FY 74-76

5. Publication Date October 1978

6. Performing Organization Code

William H. Kirchhoff and Eileen Myers

8. Performing Organ. Report No.

9. PERFORMING ORGAN IZATIO^T NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No.

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP) 13. Type of Report & Period Covered

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less (actual summary ol most sigfiilicarjt information. If document includes a significant

bibliography or literature survey, mention it here.) This report covers the projects of the air and water measurement

program during the fiscal years 1974-1976. The participants in the

program are from the divisions under the Institute for Materials

Research. In the past three years the emphasis on the water pollution

effort has increased so much that the name of the office was changed.

The name reflects the office's broader role and responsibilities.

The projects covered in this report deal specifically with:

Air- -Research leading to development of SRM's (Standard Reference Material

or other means for ensuring the accuracy of air measurement methods.

Development of laboratory methods with improved accuracy, sensitivity and specificity for air pollution measurements.

Generation, evaluation, compilation and dissemination of data and

technical information needed to relate the substances emitted from source

of pollution to those found in the atmosphere after chemical reactions

have occurred.

(Continued on attached sheet)

s)

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Air pollution; Measurement; SRM; Water pollution

18. AVAILABILITY [x] Unlimited

|_^ For Official Distribution. Do Not Release to NTIS

|x7' Order From Sup. of Doc, U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. CM

Q^ Order I'rom National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

387

22. Price$6.00

USCOMM.DC 29042-P74

HOBUJ
NBS-IUA (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUni.ICATION OR RKPORT NO.

NRfi .Special Publ. 963

2. Gov't Accessic

No.

3. Recipient's Acces.sion No.

4. TITLE AND SUBTITLE

Air and Water Pollution

Anntial Report FY-74-76

5. Publication Date

6. Performing Organization Code

7. AUTHOR(S)

wm-iam H. Kirnhhoffr F.jleen Mvers

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS ADD NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No.

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP) 13. Type of Report & Period Covered

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less (actual summary of most sigpHicant intormation. II document includes a signilicant

bibliography or literature survey, mention it here.) Water

Evaluation of the accuracy of rtethods for measuring water velocity and flow in

open and closed channels.

Developnent of radioactivity standards

.

Development of Standard Reference Materials for evaluating the accuracy of

instruments and methods for measuring the concentration of pollutants in water and

sediments.

Measurement evaluation and conpliation of physical and chemical properties of

of known pollutants.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons) ^^ pollution; Measurement; SPM; water pollution

18. AVAILABILITY [^Unlimited

Q7! ^°' Official Distribution. Do Not Release to NTIS

I

' Order From Sup. of Doc, U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. CH

I

I Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

22. Pr

USCOMM-DC 29042-P74

<r U. S. GOVERNMENT PRINTING OFFICE : 1978 261-238/247 i
NBS TECHNICAL PUBLICATIONS

PERIODICALS

JOURNAL OF RESEARCH—The Journal of Research

of the National Bureau of Standards reports NBS research and development in those disciplines of the physical and

engineering sciences in which the Bureau is active. These

include physics, chemistry, engineering, mathematics, and

computer sciences. Papers cover a broad range of subjects, with major emphasis on measurement methodology, and

the basic technology underlying standardization. Also in- cluded from time to time are survey articles on topics closely

related to the Bureau's technical and scientific programs. As

a special service to subscribers each issue contains complete

citations to all recent NBS publications in NBS and non- NBS media. Issued six times a year. Annual subscription: domestic $17.00; foreign $21.25. Single copy, $3.00 domestic;

$3.75 foreign. Note: The Journal was formerly published in two sections: Section A "Physics and Chemistry" and Section B "Mathematical Sciences." DIMENSIONS/NBS

This monthly magazine is published to inform scientists, engineers, businessmen, industry, teachers, students, and

consumers of the latest advances in science and technology,

with primary emphasis on the work at NBS. The magazine

highlights and reviews such issues as energy research, fire protection, building technology, metric conversion, pollution

abatement, health and safety, and consumer product per- formance. In addition, it reports the results of Bureau pro- grams in measurement standards and techniques, properties

of matter and materials, engineering standards and services, instrumentation, and automatic data processing.

Annual subscription: Domestic, $12.50; Foreign $15.65.

NONPERIODICALS

Monographs—Major contributions to the technical liter- ature on various subjects related to the Bureau's scientific and technical activities. Handbooks—Recommended codes of engineering and industrial practice (including safety codes) developed in cooperation with interested industries, professional organizations, and regulatory bodies. Special Publications—Include proceedings of conferences sponsored by NBS, NBS annual reports, and other special

publications appropriate to this grouping such as wall charts, pocket cards, and bibliographies.

Applied Mathematics Series—Mathematical tables, manuals, and studies of special interest to physicists, engineers,

chemists, biologists, mathematicians, computer programmers,

and others engaged in scientific and technical work.

National Standard Reference Data Series—Provides quantitative data on the physical and chemical properties of

materials, compiled from the world's literature and critically evaluated. Developed under a world-wide program co- ordinated by NBS. Program under authority of National

Standard Data Act (Public Law 90-396).

NOTE: At present the principal publication outlet for these data is the Journal of Physical and Chemical Reference Data (JPCRD) published quarterly for NBS by the American Chemical Society (ACS) and the American Institute of

Physics (AIP). Subscriptions, reprints, and supplements

available from ACS, 1155 Sixteenth St. N.W., Wash., D.C.

20056.

Building Science Series—Disseminates technical information developed at the Bureau on building materials, components,

systems, and whole structures. The series presents research

results, test methods, and performance criteria related to the

structural and environmental functions and the durability and safety characteristics of building elements and systems. Technical Notes—Studies or reports which are complete in themselves but restrictive in their treatment of a subject.

Analogous to monographs but not so comprehensive in scope or definitive in treatment of the subject area. Often

serve as a vehicle for final reports of work performed at NBS under the sponsorship of other government agencies.

Voluntary Product Standards—Developed under procedures

published by the Department of Commerce in Part 10, Title 15, of the Code of Federal Regulations. The purpose

of the standards is to establish nationally recognized require- ments for products, and to provide all concerned interests with a basis for common understanding of the characteristics of the products. NBS administers this program as a supple- ment to the activities of the private sector standardizing

organizations.

Consumer Information Series—Practical information, based on NBS research and experience, covering areas of interest to the consumer. Easily understandable language and

illustrations provide useful background knowledge for shopping in today's technological marketplace.

Order above NBS publications from: Superintendent of Documents, Government Printing Office, Washington, D.C.

20402. Order following NBS publications—NBSIR's and FIPS from

the National Technical Information Services, Springfield, Va. 22161.

Federal Information Processing Standards Publications (FIPS PUB)—Publications in this series collectively constitute the Federal Information Processing Standards Register.

Register serves as the official source of infonnation in the Federal Government regarding standards issued by NBS

pursuant to the Federal Property and Administrative Services Act of 1949 as amended, Public Law 89-306 (79 Stat. 1127), and as implemented by Executive Order 11717

(38 FR 12315, dated May 11, 1973) and Part 6 of Title 15 CFR (Code of Federal Regulations).

NBS Interagency Reports (NBSIR)—A special series of

interim or final reports on work performed by NBS for outside sponsors (both government and non-government).

In general, initial distribution is handled by the sponsor;

public distribution is by the National Technical Information

Services (Springfield, Va. 22161) in paper copy or microfiche form.

P BIBLIOGRAPHIC SUBSCRIPTION SERVICES

The following current-awareness and literature-survey bibli- ographies are issued periodically by the Bureau: Cryogenic Data Center Current Awareness Service. A litera- ture survey issued biweekly. Annual subscription: Domestic, $25.00; Foreign, $30.00.

Liquified Natural Gas. A literature survey issued quarterly.

Annual subscription: $20.00.

Superconducting Devices and Materials. A literature survey

issued quarterly. Annual subscription: $30.00. Send subscription orders and remittances for the preceding bibliographic

services to National Bureau of Standards, Cryogenic Data

Center (275.02) Boulder, Colorado 80302.
U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington, D.C. 20234

OFFICIAL BUSINESS

Penalty for Private Use. $300

POSTAGE AND FEES PAID

U.S. DEPARTMENT OF COMMERCE COM-215

SPECIAL FOURTH-CLASS RATE

BOOK