REFERENCE

OCT 1 * 1975

rS) STATES ITMENT OF IMERCE

.ICATION EN

175094- - (24

woo NBS TECHNICAL NOTE 582

«T,»0«'

Activities of the

NBS Spectrochemical

Analysis Section

July 1970 to June 1971

U.S.

WTMENT

OF

; too
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards1 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 measure- ment 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 consists of the Institute for Basic Standards, the Institute for Materials

Research, the Institute for Applied Technology, the Center for Computer Sciences and

Technology, and the Office for Information Programs.

THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consistent system of physical measurement; coordinates

that system with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of a Center for Radiation Research, an Office of Measurement Services and the following divisions: Applied Mathematics—Electricity—Heat—Mechanics—Optical Physics—Linac

Radiation2—Nuclear Radiation2—Applied Radiation2—Quantum Electronics3—

Electromagnetics3—Time and Frequency3—Laboratory Astrophysics3—Cryogenics3

. THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research lead- ing to improved methods of measurement, standards, and data on the properties of

well-characterized materials needed by industry, commerce, educational institutions, and

Government; provides advisory and research services to other Government agencies;

and develops, produces, and distributes standard reference materials. The Institute consists of the Office of Standard Reference Materials and the following divisions: Analytical Chemistry—Polymers—Metallurgy—Inorganic Materials—Reactor

Radiation—Physical Chemistry.

THE INSTITUTE FOR APPLIED TECHNOLOGY provides technical services to pro- mote the use of available technology and to facilitate technological innovation in industry and Government; cooperates with public and private organizations leading to the development of technological standards (including mandatory safety standards), codes

and methods of test; and provides technical advice and services to Government agencies

upon request. The Institute also monitors NBS engineering standards activities and

provides liaison between NBS and national and international engineering standards

bodies. The Institute consists of the following divisions and offices: Engineering Standards Services—Weights and Measures—Invention and

Innovation—Product Evaluation Technology—Building Research—Electronic

Technology—Technical Analysis—Measurement Engineering—Office of Fire

Programs.

THE CENTER FOR COMPUTER SCIENCES AND TECHNOLOGY conducts re- search and provides technical services designed to aid Government agencies in improving cost effectiveness in the conduct of their programs through the selection, acquisition,

and effective utilization of automatic data processing equipment; and serves as the principal focus within the executive branch for the development of Federal standards for automatic data processing equipment, techniques, and computer languages. The Center

consists of the following offices and divisions: Information Processing Standards—Computer Information—Computer Services —Systems Development—Information Processing Technology.

THE OFFICE FOR INFORMATION PROGRAMS promotes optimum dissemination

and accessibility of scientific information generated within NBS and other agencies of

the Federal Government; promotes the development of the National Standard Reference

Data System and a system of information analysis centers dealing with the broader

aspects of the National Measurement System; provides appropriate services to ensure

that the NBS staff has optimum accessibility to the scientific information of the world,

and directs the public information activities of the Bureau. The Office consists of the following organizational units: Office of Standard Reference Data—Office of Technical Information and

Publications—Library—Office of International Relations.

1 Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted; mailing address Washington, D.C. 20234.

2 Part of the Center for Radiation Research.

3 Located at Boulder, Colorado 80302.
riONAL BUREAU OF STANDARDS

MAR 2 2 1972

-c

UNITED STATES DEPARTMENT OF COMMERCE

Maurice H. Stans, Secretary

NATIONAL BUREAU OF STANDARDS • Lewis M. Branscomb, Director

NBS

i

TECHNICAL NOTE 582

ISSUED JANUARY 1972

Nat. Bur. Stand. (U.S.), Tech. Note 582, 126 pages (Jan. 1972)

CODEN: NBTNAE

Activities of the NBS Spectrochemical Analysis Section

July 1970 to June 1971

K. F. J. Heinrich and S. D. Rasberry

Institute for Materials Research

National Bureau of Standards

Washington, D.C. 20234

NBS Technical Notes are designed to supplement the Bureau's regular publications program. They provide a means for making available scientific data that are of transient or limited interest. Technical Notes may be

listed or referred to in the open literature.

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

(Order by SD Catalog No. C 13.46:582). Price $1.25.

FOREWORD

The Analytical Chemistry Division was established as a

separate division at the National Bureau of Standards on

September 1, 1963, and became part of the Institute for

Materials Research in the February 1, 1964, reorganization.

It consists at present of nine Sections and about 100 technical personnel encompassing some 45 different analytical

competences from activation analysis to x-ray spectroscopy.

These competences, and in turn the Sections which they comprise,

are charged with research at the forefront of analysis as well

as awareness of the practical sample, be it standard reference

material or service analysis. In addition it is their responsibility to inform others of their efforts.

Formal publication in scientific periodicals is a highly

important output of our laboratories. In addition, however,

it has been our experience that informal, annual summaries of

progress describing efforts of the past year can be very valuable in disseminating information about our programs. A word

is perhaps in order about the philosophy of these yearly

progress reports. In any research program a large amount of

information is obtained and techniques developed which never

find their way into the literature. This includes the

"negative results" which are so disappointing and unspectacular but which can often save others considerable work. Of

importance also are the numerous small items which are often

explored in a few days and which are not important enough to

warrant publication -- yet can be of great interest and use to

specialists in a given area. Finally there are the experimental techniques and procedures, the designs and modifications

of equipment, etc., which often require months to perfect and

yet all too often must be covered in only a line or two of a

journal article.

in
Thus our progress reports endeavor to present this information which we have struggled to obtain and which we

feel might be of some help to others. Certain areas which

it appears will not be treated fully in regular publications

are considered in some detail here. Other results which are

being written up for publication in the journal literature

are covered in a much more abbreviated form.

At the National Bureau of Standards publications such

as these fit logically into the category of a Technical

Note. In 1971 we plan to issue these summaries for all of

our Sections. The following is the seventh annual report

on progress of the Spectrochemical Analysis Section.

W. Wayne Meinke, Chief

Analytical Chemistry Division

IV
PREFACE

The seventh annual progress report of the Spectrochemical

Analysis Section covers a period of intense evolution. The

current trend towards increasingly complex and sophisticated

analytical tools is reflected in the prospects of the Ion

Probe Mass Analyzer; the installation of the Division Computer

System will accelerate the already existing trend towards

automatic experiment programmation and data handling. However,

the human and financial resources of the Section are limited;

hence, a continuing process of reevaluation of priorities is

required. The potentials and limitations of new tools must

be explored in order to insure their rational utilization;

at the same time, we must give full use to established techniques which continue to render valuable services.

On January 11, 1971, Mr. B. F. Scribner, who had been

in charge of this Section since its inception, left it to

assume the position of Deputy Division Chief. It is a difficult task for his successors to maintain the high levels

of efficiency established by him.

This report reviews the progress in research, instrumentation, and service activities of the Section for the past

year. In order to specify procedures adequately, it has been

necessary occasionally to identify commercial materials and

equipment. In no case does such identification imply recommendation or endorsement by the National Bureau of Standards,

nor does it imply that the material or equipment identified

is necessarily the best available for the purpose.

Kurt F. J. Heinrich, Acting Chief

Spectrochemical Analysis Section

Stanley D. Rasberry, Acting Assistant

Chief

Spectrochemical Analysis Section
TABLE OF CONTENTS

PAGE

ABSTRACT 1

INTRODUCTION .... 3

A. Changes in Facilities 3

B. Personnel and Activities 5

2. OPTICAL SPECTROSCOPY 8

A. Research 8

B. Applications to Analysis 8

1. Analyses of Standard Reference

Materials 8

2. Other Service Analyses 10

C. Description of Homogeneity Testing Method . . 13

D. Modification of Gas-Sheath Arc Unit 16

3. X-RAY FLUORESCENCE SPECTROMETRY 20

A. Instrumentation 20

B. Computations for Quantitative Analysis .... 22

C. Characterization of Standard Reference

Materials 27

1. Preliminary Testing 27

2. Homogeneity Testing . . . 28

3. Certification of Composition 30

4. Utility of Standard Reference

Materials 30

5. Production Quality Control . 31

D. Service Analyses 31

E. Investigation for Special Applications .... 33

F. Other Applications 34

4. ELECTRON PROBE MICROANALYSIS ... 35

A. Instrumental Improvements 35

1. Scan Driver . 35

2. Electron Lens and Power Supplies for

Higher Beam Resolution 42

3. Residual Gas Analyzer (RGA) 42

VI
PAGE

B. Scanning Techniques and Sample Preparation for

Small Particles and Biological Thin Cuts ... ^5

1. Handling of Particles 46

2. Analysis of Biological Specimens ^9

C. Quantitative Analysis 53

1. Limit of Detection 54

2. Further Measurements on Standard Reference

Materials . 56

3. Computer Programs 57

4. Studies on Binary Alloys 60

D. Service Analyses 62

5. PRECONCENTRATION TECHNIQUES 64

A. Interaction of Nitrilotriacetic Acid (NTA)

Solution with River Sediments 64

B. Orchard Leaves, Standard Reference

Material 1571 68

1. Determination of Fe 3 Pb 3 Zn, Cu, Ni

,

and Se 68

2. Determination of Mercury 70

6. LIST OF PERSONNEL AND "ACTIVITIES 73

A. Personnel 73

B. Publications 74

C. Talks Given 75

D . Committee Activities 78

7. ACKNOWLEDGMENTS 80

8. LIST OF REFERENCES 82

APPENDIX A: CERTIFICATES FOR NBS STANDARD REFERENCE

MATERIALS RECENTLY ISSUED 86

1. SRM 1261 AISI 4340 Steel 87

2. SRM 1262 AISI 94B17 Steel (Modified) 90

3. SRM 1263 Cr-V Steel (Modified) 93

4. SRM 1264 High-Carbon Steel (Modified) .... 96

5. SRM 1265 Electrolytic Iron 99

6. SRM 483 Fe-3Si Alloy Microprobe Standard . . . 102

7. SRM 485 Austenite in Ferrite 103

Vll
PAGE

8. SRM's 1206-2, 1207-1, 1207-2, 1208-1, 1208-2

High-Temperature Alloys: Rene 41, Waspaloy,

and Inco 718 105

9. SRM 1134 High-Silicon Steel 107

10. SRM 1623 Sulfur in Residual Fuel Oil 109

11. SRM 1624 Sulfur in Distillate Fuel Oil .... 110

12. SRM 654a Titanium Alloy, 6A1-4V Ill

13. SRM 917 D-Glucose 112

14. SRM 918 Potassium Chloride 113

15. SRM 984 Rubidium Chloride 114

16. SRM 106lc Magnesium Cyclohexanebutyrate . . . 115

APPENDIX B: FUNCTIONAL BLOCK DIAGRAM OF ELECTRON BEAM

SCANNING SYSTEM 116

LIST OF FIGURES

FIGURE NO.

1. Hardware analyzed for alloy identification . . 12

2. Sampling of steel bar for homogeneity

studies 13

3. Time-sequence of measurements for a four-slice

by four-spot homogeneity test 16

4. Computer output for analysis of variance of

the phosphorus concentration in cast

iron 17

5. Schematic drawing of the modified gas-sheath

arc unit 18

6. Resolution test for our lithium-drifted silicon detector 21

7. A qualitative representation of possible

interelement effects 23

8. Experimental data for the determination of

iron in ternary alloys of iron, chromium

and nickel 25

9. Homogeneity test for calcium in Portland

Cement 2 8

vin
PAGE

FIGURE NO.

10. Homogeneity test for sulfur in Portland

Cement 29

11. X-ray fluorescence calibration curve for the

determination of sulfur in oil 32

12. X-ray fluorescence calibration curve for the

determination of phosphorus in cloth .... 3^

13. Electromagnetic translation of the field of

view 36

14

.

Rotation sequence through steps of 180° ... 37

15. Normal image and mirror image of same view

field 38

16. Electronic line scan on the same specimen as

Fig. 13 ' 39

17. Y-axis modulation of target current signal

with oblique view-field presentation .... ^0

18. Residual gas analyzer mounted on top of the

tank of the electron probe microanalyzer . . ^3

19. Residual gas spectra of the atmosphere within

the tank 44

20. Diagram of particle mounted within thin

organic film ^7

21. Absorbed electron scanning image of fly ash

particles mounted in collodion 49

22. Pulse-height spectra of four fly ash particles

mounted on collodion film 51

23. Schematics of specimen holder for the detection of scattered (transmitted)

electrons 52

24. Scanning transmission electron micrograph of

unstained cartilage tissue 53

25. Cr Ka signal from low-alloy steels 55

ix
PAGE

FIGURE NO.

26. The copper Ka measurements in gold-copper

binaries 58

27. Experimental and theoretical intensity ratios

of Cu Ka for a nominally Au60-Cu40 alloy . . 59

28. Apparatus for digestion of organic samples

and equilibration of mercury 71

LIST OP TABLES

TABLE NO

1. Results for Fe-Ni-Cr alloys using two computation procedures 26

2. Summary of results for x-ray fluorescence

tests of homogeneity of seven new Portland

cement Standard Reference Materials .... 30

3. Concentrations in micrograms of element per

milliliter of solution which had been interacted with river bottom sediment (Pb , Hg, Sn

,

Cd, Zn, Cu and Pe

)

6 7

4. Concentrations in micrograms of element per

milliliter of solution which had been interacted with river bottom sediment (Ba, Sb , Mo,

Sr 3 Cr, Ni and Ag) 68

5. Average concentrations in the solution

obtained from wet-ashing one-gram samples of

Orchard Leaves SRM 1571 7°
ACTIVITIES OF THE NBS SPECTROCHEMICAL

ANALYSIS SECTION

July 1970 to June 1971

Edited by K. F. J. Heinrich and S. D. Rasberry

Spectrochemical research activities, improvements in

equipment and applications, especially to the certification

of NBS Standard Reference Materials, are summarized. In

optical emission spectroscopy, studies have been carried out

on a modified gas-sheath arc excitation source. Application

has been made of this source and several other conventional

excitation sources to analytical problems related to both

Standard Reference Materials and other materials being

investigated at NBS. Newly derived computation procedures

for quantitative x-ray fluorescence analysis are described

as well as new instrumentation added for x-ray spectrochemical studies. In electron probe microanalysis, research

and new instrumentation has been directed to improved

detection limits and quantitation; special emphasis has

been given to methods for small particles and biological

thin cuts. Methods of preconcentrat Ion of impurities have

been advanced and applied, in some cases at parts per

billion (10 ) limits, to water pollution, river sediment

specimens. Mercury, cadmium, and lead were among the elements determined. Work on Standard Reference Materials

resulted in certification of several special steels,

several high temperature alloys, a high-silicon steel and

a titanium alloy, among others. Listings are given of 8

publications and 25 talks by members of the Section during

the year.
Key words

Analysis; computer program; electron probe; microanalysis; optical spectrometry; preconcentration techniques;

spectrochemical analysis; Standard Reference Materials; x-ray

fluorescence analysis.
1. INTRODUCTION

The programs and aims of the Section, as well as the

instrumentation available for its activities, are described

in earlier reports of this series [1-6], which will be used

as reference in the current report. Copies of the earlier

reports are available on request. They contain records of

the research activities, publications, talks given, and

analytical work. In the present report, we have aimed to

maintain the format established by the previous editor,

B. F. Scribner, who is now Deputy Chief, Analytical Chemistry

Division, NBS

.

A . Changes in Facilities

The major equipment of the Section has been listed in

last year's report [6]. The only substantial addition to

this list is the solid state x-ray detector system for x-ray

fluorescence spectrometry analysis, which is described in

Section 3 of this report.

An ion microprobe mass analyzer has been purchased and

is expected to arrive at NBS in the winter of 1971. This

instrument has been acquired jointly with NASA (Goddard Space

Flight Center). Since the device will considerably enlarge

the research activities and analytical capabilities of this

Section, we will briefly describe its characteristics and

suggested applications.

The ion microprobe mass analyzer is based on mass

spectrometric analysis of secondary ions sputtered from a

specimen surface under the impact of a monoisotopic ion beam,

focused to a diameter of 1-300 urn. It is thus a tool for

elemental and isotopic analysis of a microvolume at the

surface of a solid specimen. The basic design of the instrument is analogous to that of the electron probe microanalyzer

,

with the electron optics replaced by ion optics, and a mass
spectrometer substituting for the x-ray spectrometer. The

analogy is completed by the fact that both instruments allow

for line and raster scanning of the respective beams.

Compared with the electron probe, the ion microprobe mass

analyzer offers several significant advantages:

1. The sensitivity for most elements, particularly

those with low atomic numbers, is better by several orders of

magnitude

.

2. Isotopic ratios can be determined.

3. Since the ions do not appreciably diffuse in depth

or laterally, the analysis is essentially of the surface, and

the resolution is practically identical with the beam diameter - which can be made to be 1 ym or less.

4. It is not necessary that the specimens be good conductors of heat or electricity.

5. Since there is a choice of positive or negative ions

of several elements, the relative sensitivities of elements

to be determined can be varied within wide ranges.

The ion microprobe has the following disadvantages:

1. The method is destructive, since the specimen is

slowly eroded during the ion bombardment. (This, however, can

be turned into an advantage, since variations in concentration can be observed as a function of depth within the

specimen .

)

2. As the physical process involved is more complex

than that of x-ray excitation by electrons, it is anticipated

that the accuracy of quantitative analysis will be inferior

to that of electron probe microanalysis.

In spite of these disadvantages, we anticipate that the

potential of this instrument in microanalysis is enormous.

The possibility of applying this type of trace analysis on

the micron dimensional level to biological specimens is

particularly intriguing. The usefulness and importance of

the technique to the study of mineralogical specimens has

already been demonstrated [7]. We expect to be active before
the end of the fiscal year '72 in the study of both the

instrment and its applications.

Adding the Ion Microprobe Mass Analyzer will require some

reorganization of the available laboratory space. Studies of

plans for this reorganization are presently under way.

The Division- wide computerized data acquisition system

has been mentioned previously [6]. Midway through this fiscal

year, the computer was delivered and put into operation by

the Technical Services Group of the Division. They have prepared and installed part of the Interfacing equipment which

will be needed to join various experiments to the system.

None of our equipment is on-line yet, but we are planning to

use the system with the following devices: electron probe

microanalyzer , x-ray fluorescence spectrometer, three optical

emission spectrometers and a microphotometer . In each of

these applications we will begin with simple data collection.

(Each instrument is currently capable of transferring digital

data to a teletype.) In addition, the interfacing for the

electron probe will Include, at an early stage, control provisions for beam positioning. Other extensions will be made

on an add-as-we-go basis.

Preliminary programming for the Division computer has

been carried out by Robert Myklebust. He has adapted MULTI 8

(see Section 4.C) for processing electron probe data on the new

computer. Other programming and computer usage has continued

with the NBS Univac 1108 and with a variety of time-sharing

services

.

B. Personnel and Activities

A list of the present personnel of the Section is given

in Section 6. Aside from the changes in Summer Assistants,

the following changes should be noted. B. P. Scribner,

Section Chief, was promoted in January of 1971 to Deputy

Division Chief of the Analytical Chemistry Division. The
administrative tasks of Section 310.02 were transferred to

K. F. J. Heinrich (now Acting Section Chief) , with assistance

by S. D. Rasberry (now Acting Assistant Section Chief). V. C.

Stewart and D. M. Bouchette retired, and J. R. Henoc (Guest

Worker), B. L. Hammond (Research Associate), E. Belkas (Guest

Worker), B. W. Pas tine (Chemist, part-time), and C. P. Wren

(part-time clerical) ended their activities within the Section.

The Section has endeavored to maintain the research and

service activities on a satisfactory level, in face of this

drastic reduction in force. As previously, the personnel are

grouped into four task forces: 1. Optical Emission Spectroscopy, 2. X-ray Fluorescence Spectrometry, 3. ElectronProbe Microanalysis, and 4. Enrichment Techniques. Within

each of these task forces, the activities continue being

divided between (a) research and development, and (b ) service

activities

.

In optical emission spectroscopy , the position of research

spectroscopist has been vacant; our research effort was mainly

concentrated on the characterization of materials of interest

in pollution studies, such as the analysis of river bottom

sediments, and proposed Standard Reference Materials. We

have now secured an investigator who will re-initiate research

into the more theoretical aspects of optical emission spectroscopy, particularly the potentials of novel and unconventional excitation sources. These activities will commence

in the fall of 1971.

As in previous years, a large number of determinations

were performed by x-ray fluorescence spectrometry on proposed

Standard Reference Materials, as well as on other types of

specimens. Analytical research in this area resulted in

novel and greatly improved calculation procedures for the

correction of interelement effects in complex matrices.

In electron probe microanalysis , we have continued

the projects on which we were working the previous year.
The computer program COR has been cast into a definite form

and is now considered completely debugged; the extensive work

of documentation which is necessary to make this procedure

effectively available to other research analysts is almost

completed, and a Technical Note containing the program and its

documentation will be forthcoming soon. The program, as well

as the shorter correction program MULTI 8, was used in the

interpretation of further experimental measurements on the

microprobe Standard Reference Materials in the gold-silver

and gold-copper systems [8]. The results of these measurements

were documented and discussed in an NBS Special Publication [9]

issued in summer of 1971

We have started an investigation of the analysis of

particles and thin films, particularly biological thin sections

This year, we were concerned mainly with scanning transmission

techniques, and with mounting media for such specimens. The

aspects of x-ray detection and quantitative evaluation will

be considered in detail at a later time.

Our research in preconcentration techniques , in combination with spark source mass spectrometry, has produced a method for the determination of mercury, and other elements, in

biological materials. These techniques are a prerequisite

for characterizing Standard Reference Materials of this type.

Due to lack of personnel, the activities in bibliographic

areas were restricted to keeping up our awareness files,

particularly in electron probe microanalysis.

The research activities outlined above, as well as analytical service performed, will be discussed in more detail in

the ensuing chapters.

K. F. J. Heinrich and S. D. Rasberry
2. OPTICAL SPECTROSCOPY

A

.

Research

During the past year, few resources could be allocated

to excitation studies. In consequence, we have worked mainly

on improving spectrochemical methods of analysis and have

studied the limitations of these methods relative to the

Standard Reference Materials (SRM's) for which we are responsible. This work is documented more fully In sections B and

C of this chapter.

Major improvements in spectrochemical analysis seem to

be imminent, especially in the area of excitation sources;

consequently, we are anxious to pursue this field. We have

been successful in recruiting an active investigator who is

interested in this specific area. Dr. Danold Golightly will

join our staff in September. 1971 to conduct basic and applied

research into excitation sources for spectrochemical analysis

B. Applications to Analysis

The optical emission instrumentation at our laboratory

is employed for analytical work as well as for research

activities. For the period July 1970 through June 1971,

analyses were performed by optical emission spectroscopy

involving 318 samples, 9569 determinations, and 97 reports.

Some high points of the analyses will be described.

1. Analyses of Standard Reference Materials

As in the past, optical emission spectroscopy has continued to perform an important role in the program for production and certification of SRM's. The ultimate output of

this activity is the issuance of well-characterized SRM's

certified for their chemical composition. Studies are performed in cooperation with the Office of Standard Reference

8
Materials , with other Sections of the Analytical Chemistry

Division, and with various laboratories in industry, universities, and Government.

The contribution of the optical emission group to this

program consists of four phases: (1) preliminary analysis for

acceptance, (2) study of homogeneity of the bulk material,

(3) quantitative analyses of the material, and (4) measurements on Standard Reference Materials to test their utility

with given methods of analysis.

Analysis for acceptance for some materials often involves

only a semiquantitative method employing dc-arc excitation.

This screening process will show if the material is pure

enough for the intended purpose. For other materials such

as alloys, analysis usually involves highly precise and

accurate methods to ensure compliance with composition requirements . Once the material has been accepted as having the desired

composition, the next step is to test the homogeneity to

ensure suitability for the intended use. A common procedure

is to select samples from chosen positions in the bulk material

and to analyze these samples for the important elements. In

this work, emphasis is placed on precision rather than accuracy

since, at this time, we are interested in differences among

samples rather than absolute determination of composition.

Experiments have been designed to obtain the maximum information from the minimum measurements, but employing both

optical emission and x-ray fluorescence spectrometers to

increase the power for detection of inhomogeneity . A more

complete description of this testing is given in Section 2.C

of this report

.

Next, we are involved, although to a lesser degree, in

the analyses for certification of Standard Reference Materials. Here the spectrochemical analysis must be made by a
primary method relative to standards synthesized from pure

materials. The samples are converted to powders or to solutions

to provide a form for comparison with the synthesized standards.

Powders are usually analyzed by controlled arc excitation,

and solutions by the plasma jet or by the spark and rotating

electrode technique.

The final step in our contribution to Standard Reference

Material production is the intercomparison of those Standard

Reference Materials used in emission spectroscopy to test

their workability with currently used methods of spectrochemical analysis. It is recognized that differences in

structure and/or combinations of elements in given classes

of Standard Reference Materials may change signal intensities.

Hence, the history of preparation of materials 3 and the

presence or absence of tramp elements may result in Standard

Reference Materials that yield calibration curves which are

displaced. Such displacements frequently can be minimized

or eliminated by changing the excitation conditions; however,

this information is vital to eventual users.

Compatibility studies also are made to ensure standardization of the measurement system. Further, work is undertaken

to optimize discharge conditions for particular alloy systems.

During the past year, we have made many determinations on the

1261-1265 set of low-alloy steels to test the compatibility

of these Standard Reference Materials with existing methods.

A publication of this work is forthcoming.

Examples of certificates for Standard Reference Materials

issued in the past year, to which this Section contributed,

are given in the Appendix.

2 . Other Service Analyses

This Section performs many analyses for groups within

NBS and for other Government Agencies. Most analyses are

surveys by optical spectroscopy in which 50 to 70 elements

10
are sought. This type of analysis is semiquantitative and

quite often provides sufficient information for the solution

of a problem. A wide variety of samples were examined in

the past year by this method. Sample size ranged from microsize particles to large sections of metal from which appropriate samples were taken. The typical sample was one ranging

from 5- to 20-mg total weight. For those samples weighing

less than 0.5 mg, the identification of major metallic constituents was often the only data required. For the other

samples, 50 to 70 elements were determined semiquantitatively

or reported as not detected. Typical analyses include air

pollution samples, sediments from natural waters, enzymes,

cloth, vegetation, detergents and cleaning compounds, surface

scale, and thin-film deposits on glass.

Quantitative analyses are frequently performed to determine if a part of a machine or structure is the alloy specified

by the designer. These analyses are usually part of a detailed

failure study made at NBS. An example of this is the investigation of the cause of an aircraft wing member failure which

led to its crashing. In this case, the chemical composition

was correct for the alloy specification; it was learned later

that improper heat treatment was responsible for the failure

.

Another example is the analyses of aluminum plate and weld

joints of a liquid oxygen tank car which exploded, causing

several deaths. Material of the tank car was scattered

over a large area, and by determining the composition of

aluminum alloy fragments collected at several locations, the

direction of the blast, and ultimately its cause, was determined

We are also called on to perform analyses of materials

in failure avoidance programs. For example, a number of

nuts, bolts, washers, and concrete studs and anchors have

been submitted in the past year by the District of Columbia

Department of Highways and Traffic for alloy identification.

11
This material is for use in the subway system now being

built in Washington, D. C. Because of the possibility of

corrosion, the parts are specified to be type 304 stainless

steel. However, our analyses showed that a large fraction

of the submitted material was not 304 stainless. Consequently,

several lots had to be rejected (Figure 1).

Figure 1. Hardware analyzed for alloy identification,

for the District of Columbia Department of

Highways and Traffic for alloy identification
C. Description of Homogeneity Testing Method

In the last publication of this series [6], the homogeneity testing of materials intended as spectrochemical Standard

Reference Materials was described. This year we will describe

the homogeneity testing procedure for Standard Reference

Materials which are machined into chips primarily for use

in checking chemical methods of analysis. An illustration of

a typical sampling procedure for homogeneity testing is shown

in Figure 2

.

Figure 2. Sampling of steel bar for homogeneity studies

13
Typically, an ingot is cropped, forged, and rolled up

into a round bar 5 1/4 inch in diameter. This bar is cut

into approximately 36-inch (92-cm) sections with care being

taken to preserve identity of each section's relative position.

Based on the results of homogeneity testing, sections are

selected for machining on lathes with special tools to provide

metal chips of a uniform and desired size and to the requisite

homogeneity. The chipping process stops when the sections are

reduced typically to a diameter of 1 3/4 inches (4.4 cm)

because of physical and economic considerations. Chipping

may be stopped at any diameter shown by the testing to be the

beginning of excessive inhomogeneity . The choice of test

positions on the cross sections also makes it possible, should

suitable homogeneity be observed, to further process the cores

remaining after chipping to the usual solid disk samples for

use in optical emission and x-ray spectrometric methods of

analysis. For most materials, however, the required homogeneity for spectrometric analysis can be achieved only by special

melting, casting, and fabrication procedures.

In the illustration, slices, about 3/4-inch (1.9 cm)

thick, are taken from the front-face of section 1 and tails

of sections 5, 10, and 15 to provide samples to determine if

variations in chemical composition occur along the length of

the bar. Similarily, each of the slices is samples at four

positions (spots) along the cross-section to determine if

radial inhomogeneity occurs. The positions of these spots

are at radii of zero (center), 7/8-inch (2.2 cm) (where chipping

typically stops), 1 11/16-inch (4.3 cm) (mid-point of chipping),

and 2 1/2-inch (6.4 cm) (where chipping starts). A cross-section

of one of the slices is shown in the lower right corner of

Figure 2 with the spots for sampling indicated. The sixteen

positions thus chosen are representative of the extremes of

the bar.

14
The instrumental methods employed in the homogeneity

testing, usually optical emission or x-ray fluorescence

spectrometry j are subject to linear trends with time (drift).

Therefore, the measurements are run in a sequence which is

designed to balance the effects of these trends. The experimental design was devised by NBS statisticians for our needs

[10]. The time-sequence of individual measurements is

arranged in such a way that linear drift does not introduce

a false concentration gradient, either longitudinally or

radially. To determine a time-sequence design, we establish

a matrix in which each row represents one slice and each

column represents the distance of a spot from the center.

We then assign to each location in this matrix a number

indicating the order measurements are to be made. The numbers

are chosen so that the sums for all rows are equal and the

sums for all columns are equal. This distributes the effects

of drift evenly over all the rows and columns. An illustration

of this is shown in Figure 3- The first measurement to be

made is that of position (1,1) of the matrix; i.e., slice 1,

spot 1. Next follows position (2,3), slice 2, spot 3. The

sixteenth measurement is made at slice 3, spot 3- This sequence usually is repeated at least four times to provide

adequate data for suitable statistical evaluation.

Data from the emission and x-ray spectrometers are

recorded directly in digital form and entered into a computer

for analysis of variance. A computer output sheet for a

four-slice by three-spot array (center spot not used in this

case) is shown in Figure 4. The material used for this

illustration is cast iron and the element to be tested for

homogeneity is phosphorus. While the material is to be certified for phosphorus to the third decimal place only, the

computer calculates a value to the fifth decimal place. The

last two decimal places provide important information regarding

the variation in the third decimal place. In the example

given, no excessive inhomogeneity was observed for phosphorus.

15
SPOT 12 3

1 1 12 7 14 34

W p 8 13 2 11 34

£

3

CO 4

10

15

3

6

16

9

5

4

34

34

34 34 34 34

RUN NO. 1 2 3 4 5 — 13 14 15 . 16

SLICE 1 2 3 4 3

2 1 4 3

SPOT 1 3 2 4 4 2 4 1 3

Figure 3- Time-sequence of measurements for a four-slice

by four-spot homogeneity test

.

D. Modification of Gas-Sheath Arc Unit

Various types of gas-sheath arc units — developed both

at NBS and elsewhere — which exclude atmospheric oxygen and

nitrogen from the vicinity of the arc have been in use in

this laboratory for a number of years . An improved gas-sheath

arc unit which we developed to overcome a number of problems

encountered in using the other units has now been in use on

all dc-arc runs for a period of six months. This unit is

16
HOMOGENEITY OF 20G, GVAC ANALYST-JL WEt^ER 11/26/71

ELEMENT P ANALYSIS oE VARIANCE

DE SUM OF SQUARES mEAm SQUARE F TOTAL ^7 2.1MH1M-0S <«, 56201-07 1.73

TRENO M 1.56560-06 3.91M01-07 l. M8

RUNS 3 7.7M385-06 2.58128-06 9.77

SLICE 3 2.75009-06 9.16698-07 3.M7

SPOT 1.31192-07 6.S5960-08 .25

ERROR 35 9.25068-06 2.6*430^07

SD .00051

AV6 .01300

CV 3«9S<466

TL .00Q26

CF ,0000920

AVERAGES

SPOT 1 SpOT 2 SPOT 3 AVG.

SLICE 1 .01297 .01308 .013M7 .01317

SLICE 2 .01313 .013 38 .01338 .013 30

SLICE 3 .01251 .01269 .01299 .01273

SLICE M .01313 .01290 .01239 .01280

AVERAGE .01293 .01301 .01306 .nl300

Figure 4. Computer output for analysis of variance of the

phosphorus concentration in cast iron

a modification of a commercially available unit which is easy

to disassemble and clean between individual runs. The major

problems which have been encountered were related to electrode

positioning and cooling, control of the atmosphere around

the arc to give satisfactory burns, and removal of dense

fumes when samples of up to 100 mg were run. These problems

have been solved in the design shown in Figure 5. A detailed

drawing with exact dimensions will be included in a later

publication.

17
COUNTER ELECTRODE

OPENING

l

OPTICAL OPENING

.ADJUSTABLE

/CHUCK

ARGON

ROTATE TO LOCK

ELECTRODE

PYREX GLASS

COVER

C 70% ARGON - 30 % OXYGEN

Figure 5. Schematic drawing of the modified gas-sheath

arc unit

.

In the modified version, the sample electrode is held

in an adjustable chuck (A) in such a manner that the exact

electrode height above the base can be adjusted easily and

locked in position by rotating the base extension (B). This

arrangement gives improved water cooling and excellent electrical contact without danger of arcing around the electrode

It also eliminates freezing of electrodes in the holder,

18
even on long-time, high amperage runs. The jaws of the chuck

have been designed to allow a flow of gas — 70% argon + 30%

oxygen -- which enters at the bottom of the chuck (C) to form

an envelope around the electrodes. A stream of 100% argon,

which enters at D, flows through an enlarged opening around

the chuck filling the chamber formed by the cover (E) with

argon. This excludes air which might be pulled into the

chamber at the opening for the optical path. Breakage of

the chamber cover has been reduced by replacing the small

quartz dome with a larger-volume pyrex cover. This also

allows better dilution and removal of dense vapors formed

with samples such as lead oxide. The flow rates of the two

gas lines (100% A and 70% A + 30% ) can now be adjusted

independently to suit the requirements of the particular

samples being run.

J. L. Weber, M. M. Darr

19
3 . X-RAY FLUORESCENCE SPECTROMETRY

As in past years, the x-ray fluorescence spectrometry

laboratory has served a dual role in performing both research

and service. The broad aim of our research has been to seek

improvements in methodology which will increase the accuracy

of this technique or widen its applicability. In some cases

where we were consulted, lowering a detection limit or

increasing the speed of analysis has been critical to extendini

x-ray fluorescence to a new application. In other instances,

communication has been the barrier and our role has been to

show others how existing x-ray methodology can be applied to

new problem areas.

A. Instrumentation

Our instrumentation for x-ray fluorescence has been

reviewed in prior technical notes of this series [1-6].

In the latter reference, details are given of the improvements

made on our single-channel vacuum x-ray fluorescence spectrometer. This instrument has continued to be our main tool

in both research and applied work.

The only change made to the single-channel x-ray spectrometer over the past year is the addition of a removable

gas fitting for the purpose of introducing helium into the

spectrometer housing. The need for a helium filling to reduce

x-ray absorption arises occasionally; for example, in determining light elements (from magnesium to calcium) in volatile

liquids. In such cases, evacuation of the spectrometer is

not practical, especially when disposable, non-hermetic liquid

holders are to be used. In our modified instrument, helium

is continually leaked into the spectrometer through a fitting

attached to the vent port; this maintains a positive pressure

of helium. Each time samples are introduced into the device,

20
the mechanical vacuum pump is operated for about three seconds

to expel the air which is introduced.

The use of lithium-drifted silicon solid state detectors

has been demonstrated by the electron-probe group [6] to

considerably increase their efficiency in performing qualitative analyses. Further, reports in the literature [22]

indicate the usefulness of these detectors for quantitative

analysis at trace levels. These were two of several factors

which led us to purchase a large-area (80 mm ) lithium-drifted

silicon detector. It was received in the last week of the

fiscal year; consequently, the details of even its earliest

applications will be given in next year's report. Performance

tests of the detector indicate unusually good energy resolution

for a large-area detector (see Figure 6). At low count rates,

ouuuu | -y1 55

Fe, 1 hr CO ~500 cps

1—

8.89 eV/CH

IDo

(J 40000 - - <

1 -*/ l«- 187 eV

X

_J

20000 .. — <

t—o

1- / MnKa \

/n*\!K0

80 120 160 200

CHANNEL NUMBER

240

Figure 6. Resolution test for our lithium-drifted silicon

detector. A spectrum obtained by directly

counting x-ray emission from an iron-55

radioisotope

.

21
resolution for MnKa x-rays was found to be less than 190 eV

width at 50$ of peak height (FWHM) . At higher total count

rates (up to 20,000 cps), the resolution degrades by only

about 2 eV.

B. Computations for Quantitative Analysis

A substantial part of our research effort this year has

been a continued study of empirical calibration techniques for

quantitative x-ray fluorescence analysis in the presence of

interelement effects [12-14]. An account of this study,

together with a detailed discussion of the computation procedure we have developed, will be presented to the Colloquium

Spectroscopicum Internationale XVI in October, 1971. An

extended abstract of the work will be published at that time.

Here we wish to indicate the nature of the problem and some

of the results we have obtained with a new computation procedure

Characteristic x-rays emitted by an element in a matrix

emerge only after undergoing partial absorption, the extent

of which is dependent upon what elements are present in the

matrix. If we neglect the effects of differences in primary

radiation, and the mass absorption coefficients are nearly the

same for the measured element and the matrix, the relative

intensity is directly proportional to the concentration of

the element. This is illustrated by case A in Figure 7- In

case B, the absorption by the matrix is greater than that of

the element; consequently, the measured intensity is depressed.

We have confirmed, experimentally, that in this case binaries

follow a hyperbolic function:

R = (1)

C + a(l-C)

where R is the measured relative intensity (assumed corrected

for background and counting deadtime), C is the concentration

of the measured element (mass fraction), and a is a constant.

22
CONCENTRATION .0

Figure 7. A qualitative representation of possible interelement effects; A. No interelement effect, B.

Absorption, C. Transparency of matrix, D.

Secondary fluorescence.

The magnitude of a depends upon the displacement of the hyperbola from the degenerate, straight-line case. The value of a must be a positive, real number; it is greater than one for

absorption, where the measured intensity is depressed. When

the specimen absorbs the radiation less than does the pure

element used as a standard, "negative" absorption (transparency

of matrix) results. See case C. Other workers [14] imply

that this curve also is fit by the hyperbolic equation (a is

less than one). A fourth case, secondary fluorescence, is

sometimes obtained and is illustrated in Figure 7 as case D.

Secondary fluorescence occurs in conjunction with the photoelectric absorption by the analyte element of a characteristic

x-ray produced by one of the matrix elements. We have

23
confirmed, by experiment, the fact that this case does not

follow exactly a hyperbolic function. This is intuitively

reasonable since fluorescence must increase with the concentrations of both the exciting and the excited element. When

the concentration of the analyte is near unity, there is very

little of the exciting element available to cause secondary

fluorescence; however, in a binary, at the lower concentrations

of the analyte, an increase in the effect is noted due to the

greater presence of exciting element.

Calibration data of the type illustrated in Figure 7 can

be studied more incisively if C/R is plotted as a function of

C, as is illustrated in Figure 8. When this is done, the

horizontal line, C/R = 1 for all C, denotes the case of no

net effect of either absorption or fluorescence. Points where

absorption is dominant have C/R values greater than unity due

to the reduction in relative intensity and consequently fall

above the "no effect" line. Conversely, when secondary fluorescence is dominant, the points fall below the "no effect" line

An important feature of the graph of C/R as a function of

C is the fact that the hyperbolas plotted in Figure 7 are

represented as straight lines with this new choice of coordinates. The experimental data presented in Figure 8 are for

the calibration of iron in alloys containing iron, nickel and

chromium; the upper boundary curve represents the case of Fe

absorbed by Cr in Fe-Cr binaries, whereas the lower curve

shows the secondary fluorescence of Fe by Ni in Fe-Ni binaries.

All intermediate points (closed circles) are for Fe in Fe-Ni-Cr

ternaries

.

In order to establish a calibration equation which will

permit the determination of Fe in the presence of Ni and Cr,

we make two observations regarding Figure 8. First, whatever

equation is selected must be appropriate in the absence of

either Ni or Cr, i.e., it must fit the boundary conditions

of both binary curves. Secondly, it must take into account

24
Fe-Cr BINARY

Fe-Ni BINARY

1 1 1

0.2 04 0.6 0.8

CONCENTRATION, IRON [C]

1.0

Figure 8. Experimental data for the determination of iron

in ternary alloys of iron, chromium and nickel.

the non-hyperbolic curvature observed in the case of secondary

fluorescence. We make the assumptions in this study that

the x-ray intensities are obtained from specimens which are

infinitely thick to x-ray penetration, are homogeneous, and

have smooth surfaces.

25
We have measured x-ray intensities for a set of standards

and unknown Fe-Ni-Ur alloys. These data have been submitted

to the new computation procedure mentioned above and also to

a procedure which treats secondary fluorescence as "negative"

absorption. The results are summarized in Table 1. In this

table the new procedure is abbreviated "PBM2", while the

"negative" absorption procedure is abbreviated "N-A".

Table 1. Results (in mass fraction) for Fe-Ni-Cr alloys

using two computation procedures*

Specimen

5054

5202

5364

3987

1188

Fe

Given

PBM2 N-A

0.7250

7257 .6779

.6303

6300 .589

4721

4776 .471

3431

3403 .171

0616

Element

Ni

G iven

PBM2 N-A

.0663 .0639

0. 0015

0016 .0016

.1480

1511 .159

.2357

2413 .246

.6552

6540 .827

.7370

7227 .752

Cr

Given

PBM2 N-A

0.2577

.2497 .2740

.2130

.2067 .242

.2784

.2650 .270

.0000

.0000 .0001

.1540

.1405 .140

*The values underlined are given by wet chemical analysis.

PBM2 is the new procedure and N-A is the "negative" absorption

procedure

.

26
The results by the new procedure agree reasonably well

with the wet chemical values,, generally within 2% to 4% 3 relative. There appears to be no degradation in accuracy in

cases of severe secondary fluorescence, where the "negative"

absorption method may be prone to failure. See, for example,

Pe in specimen 3987-

C . Characterization of Standard Reference Materials

Approximately 1500 man-hours have been spent this year in

performing 7500 separate quantitative determinations by x-ray

fluorescence methods. Some of these determinations have been

for service analysis; however, most of them have been undertaken in the characterization of Standard Reference Materials.

We are routinely called on to support the production of

Standard Reference Materials in five distinct ways. These

are cited below, with an example drawn from this year's work

to illustrate each one.

1 . Preliminary Testing

When a material is received at NBS proposed as a Standard

Reference Material, it is usually subjected to a preliminary

test of composition by rapid instrumental methods. Preliminary

tests of this kind, together with the examination of physical

characteristics, formed the basis for rejection of the first

lot of Special Steel 1264 produced. X-ray fluorescence was

a help in making the decision to reject the lot and to begin

production of a new lot. The second lot of 1264 passed preliminary testing and, as have the other four Standard Reference

Materials in the set of Special Steels 1261-1265, exhibited

suitable homogeneity by x-ray fluorescence methods. To date,

all five have been certified for the important specified

elements and additional certification is underway. Certificates

for these standards are appended to this report.

27
HOMOGENEITY TEST - UNIVERSAL

ELEMENT CA

ANALYSIS OF VARIANCE

JF S UM OF SOJa>RES

TOTAL 127 4.33023+00

TREM^ 4 4.14672-01

RUNS 3 2.16845400

SLICE 15 1.75033--01

SPOT 1 2.23257--0 2

ERROk 104 1.59630+00

S3 .12391

AVG o 3.2U000

Q\J .19606

TL .06196

CF .00 0270

AVERA3LS

S^OT 1 SPOT 2 AVS.

slice i 63.20 o3.21 63.21

SLICE £ 63.16 63.22 63.19

slice 3 63.19 63.29 63.24

slice 4 63.29 63.13 63.21

slice 5 53.21 63.29 63.25

slice 5 63.13 63.13 63.15

slice 1 63.18 63.14 63.16

SuICE 63.12 o3.20 63.16

SlICE 9 63.22 63.22 63.22

SLICE1U 63.22 63.23 53.22

SLlCEli 63.09 63.23 63.16

SLICE12 63.15 63.12 53.13

SlICEIj 63.25 53.22 53.24

SlICE1+ 63.23 63.17 63.20

SLlCElb 63.21 53.33 53.27

SLiCElo 63.13 63. 25 63.19

AVERASE 63.19 53.21 53.20

Figure 9 . Homog<Bneity tes t for- c

— 6-71

MEAN S3U4RE

3.44904-02

1.03658-01

7.22317-01

1.13639-02

2.23257-02

1.53533-02

F

2.25

6.75

47.08

.77

1.45

Analysis of variance data are presented, followed

by the value obtained for calcium concentration

at individual test locations.

2 . Homogeneity Testing

The next phase of Standard Reference Material production

is perhaps the most important of all. The function of homogeneity testing is to determine how uniform, in terms of composition, is the material to be sold. Some discussion of the

experimental designs we use in measuring homogeneity is given

28
in a previous note in this series [6] and in Section 4.C of

this report. Besides the work mentioned above for steels 3 we have also determined the homogeneity for seven new Portland

Cement Standard Reference Materials. In Figure 9 and 10,

complete results are shown for one of the materials. A summary

for all the materials is given in Table 2.

HOMOGENEITY TEST - UNIVERSAL — 6-71

ELEMENT S

ANALYSIS OF VARIANCE

QF SUM OF SQUARES MEAN SQUARE F

TOTAL 127 3.19778-02 2.51794-04 1.58

TREND 4 7.52766-04 1.88191-04 1.18

RUNS 3 4.38183-03 1.46061-03 9.19

SLICE 15 1.02739-02 6.84925-04 4.31

SPOT 1 3.34153-05 3.34153-05 .21

ERROR 104 1.65359-02 1.58999-04

SD .01261

AVG 2.20000

CV .57316

TL .00630

CF .0000400

AVERAGES

spot 1 spot 2 avg.

slice i 2.130 2.183 2.132

SulCE 2 2.200 2.194 2.197

SlICe 3 2.181 2.189 2.185

Slice 4 2.200 2.192 2.195

SlICE 5 2.193 2.196 2.195

slice 6 2.130 2.199 2.190

SLICE 7 2.203 2.211 2.207

slice a 2.204 2.220 2.212

SuICE 9 2.195 2.201 2.193

i>LlCE10 2.212 2.191 2.202

SLICE11 2.191 2.227 2.209

SLICE12 2.227 2.193 2.210

SL1CE13 2.213 2.206 2.209

SLICE14 2.204 2.195 2.200

SLICE15 2.215 2.205 2.210

SLICE16 2.194 2.204 2.199

AVERAGE 2.199 2.201 2.200

Figure 10. Homogeneity test for sulfur (calculated as SCO

in Portland Cement. Analysis of variance data

are presented, followed by the value obtained

for sulfur concentrations at individual test

locations

.

29
Table 2. Summary of results for x-ray fluorescence tests

of homogeneity on seven new Portland Cement

Standard Reference Materials

Nominal Concentration

SRM Number (in wt. %)

C_a S0

3

633 65 2.2

634 63 2.2

635 60 6.8

636 64 2.2

637 66 2.4

638 62 2.4

639 67 2.5 .08 0.018

St andan

( in

1 Deviation

wt . %)

Ca SO0.14

.13

.013

0.013

.14

.15

0.028

0.015

.14

.11

0.013

.014

3

.

Certification of Composition

Certification of composition is not normally undertaken

by methods of analysis which rely on standardization by

reference materials of similar type, except in the case of

replacement for a Standard Reference Material going out of

stock. In these cases, a precise relative method, such as

x-ray fluorescence, can be very useful in determining the

composition values to be certified. This year, a titanium

alloy (6A1-4V) was certified using x-ray fluorescence as a principal measurement technique. The certificate for this

material is appended.

4

.

Utility of Standard Reference Materials

When a Standard Reference Material is issued as a calibration standard for an instrumental method of analysis

and has been certified by umpire wet chemical procedures, it

is necessary to test directly the utility of the material

30
to the method for which it is intended. Tests of this type

were undertaken this year on two Standard Reference Materials

which are important to air pollution control. Two new

sulfur- bearing oil Standard Reference Materials were produced

in order to extend downward the range of concentration of

sulfur in oil offered by the NBS . This extension has become

important in view of tighter sulfur-emission controls incorporated into the pollution laws of many cities. The new

Standard Reference Materials were found to be consistent with

the two previous ones, when all four are measured according

to ASTM Standard Method D 2622-67 for x-ray fluorescence

determination of sulfur in oil. A graph of the calibration

curve obtained is presented in Figure 11. Certificates are

appended

.

5 . Production Quality Control

In some cases. Standard Reference Materials of quite

different compositions are identical in appearance and can

therefore be mislabeled accidentally. We use x-ray fluorescence to check the identity and labeling of such Standard

Reference Materials because the technique is not destructive

and does not alter the condition of a specimen which may

be ready for sale. In one instance this year, ten specimens,

labeled 1172, were suspected of being incorrectly labeled.

They were submitted to us and on the same day a report was

issued verifying the ten specimens as Standard Reference

Material 1172. Accurate determinations of niobium and chromium

for each sample confirmed the identities with less than one

man-hour required to perforin the task.

D. Service Analyses

The service analyses we perform are undertaken in support

of NBS projects as well as to aid important work underway at

other Government Agencies. Typical analyses include:

31
2000

U

LU i6oo

CO\

CO

1200 - o

o

I 800

OH

400 .

CO

HP HP "T" 1

-

1622

-

- ^

-

- ^

1621

-

A^162.3

/1624

^MINERAL OIL ^i ^j^ i^

-

0.4 0.8 1.2 1.6 2.0

SULFUR - IN WT. %

Figure 11 X-ray fluorescence calibration curve for

the determination of sulfur in oil. The

analytical procedure used follows ASTM,

Standard Method D 2622-67-

32
1. Stainless steel for fabrication of parts for the

NBS nuclear reactor. Stringent composition specifications

must be met in this application for both mechanical safety

and radiation safety reasons.

2. Fasteners and components to be used in the subway

system which is being constructed in metropolitan Washington,

D. C. Safe operation and economical future maintenance of

this system depend on both proper design and use of the specified materials.

3. Iron foils for a research project being carried

out at NBS were analyzed. The role minor elements were

playing in the requester's experiments was being studied.

E

.

Investigation for Special Applications

Cooperation and consultation with the NBS group responsible for research in fabric flammability has introduced to

us a problem to which an x-ray fluorescence technique may

provide a solution.

Phosphorus compounds have been proven as flame retardants

when "set" in textiles. Numerous methods exist for determining

phosphorus in cloth when the cloth can be sampled. However,

a rapid non-destructive technique, which can be used on-line

in the treating area of a mill, is needed for quality control

of the phosphorus concentration. We have demonstrated (see

Figure 12) that tube-excited x-ray fluorescence meets some of

the requirements for this kind of quality control. Furthermore,

we discussed the problem with the AEC group for development

of radioisotope applications and they have arranged for demonstrations of the feasibility of using isotope^excited x-ray

fluorescence in this application.

Not all the problems connected with the determination

of phosphorus in cloth have been solved in the brief study

which has been thus far undertaken. We hope to present more

detailed results in a later report.

33
1 "T" r—

i

O 300 — THPOH-4 «. LU

CO\

CO

1-2 •

Z> THPOH-3

o

<~> 200 - - B

*: THPOH-2 •

AP-4

CO

DC AP-2

AP-3

* •• DAP-4

O 100 . — X DAP-2

Q_ DAP-1 # COO • X

THPOH-1

| 1

1 1 .50 1-0 PHOSPHORUS1.5 -IN WT. %

2.0 2.25

Figure 12 X-ray fluorescence calibration curve for the

determination of phosphorus in cloth. The data

are for several different treatments and thickness of textile; this may account for part of

the scatter observed.

Two other new application areas which we have just

begun reviewing are the analysis of air particulate samples

and toxic metals in paint films

.

P . Other Applications

Fielding Ogburn, Virginia Pennington, and Carole Shriner

(from the Metallurgy Division) have continued a project concerning thickness measurements on electroplated metal coatings

S. D. Rasberry

34
4. ELECTRON PROBE MICROANALYSIS

A . Instrumental Improvements

1 . Scan Driver

A new beam scanning driver has been constructed ' which

takes advantage of the highly stable operational amplifiers

and electronics now available. The device incorporates a number of useful control functions which are performed by the

operational amplifiers. Easy access is provided to all pertinent summing points. This access will permit inclusion of

functions that may be needed in the future. Such needs are

expected to arise when the Division computer is Interfaced

to the microprobe.

The functions included in the present design are as

follows

a. Translation and rotation of an entire scanning

area. See Figures 13 and 14

.

b. Continuous control of magnification (zoom

control)

.

c. A mirror image - normal image switch to permit

inverting the X-sweep direction in the electron probe with

respect to the oscilloscope. See Figure 15.

d. A dash generator to mark the locus used in

line scanning. See Figure 16.

e. A switch for selection of sweep speeds. The

available positions are: fixed slow - fixed fast - variable

sweep speed.

f. A vertical-sweep counter control which permits,

for purpose of photography, a predetermined number of sweeps,

after which the display scope is blanked and an indicator is

activated. The range extends from 2 to 99 sweeps.

g. Provisions for Y-axis-modulation and oblique

oscilloscope display (See Figure 17)- We have incorporated

35
Sir

K?^v_>^ ^

—-.*,.,•

~* HLp TM V *^ ^•^.

-' v- o • > V" <

c P —

Figure 13- Electromagnetic translation of the field of

view. Target current images of a two-phase

nickel-aluminum alloy. One large division

equal to 66 ym (150 X).

36
i

» >

V".

!*?*"*'_^JhMtf ' i*i£~^''~**% ' 'J i /' ^^^ (s

/

r

-

» J

Figure 14. Rotation sequence through steps of 180° (twostep variation between images), same specimen

and magnification as Fig. 13.

37
Figure 15. Normal image and mirror image of same view

field. Same specimen and magnification as

Pig. 13.

38
Figure 16 . Electronic line scan on the same specimen as Fig. 13, superposed on target current area scan

Full lines show Al Ka signal and background;

broken line shows location of line scan on the

specimen, with respect to the area scan. One

large division equal to 66 ym (150 X).

this feature for special cases, although usually a derivative

signal brightness modulation and rectangular format are

preferred when secondary electron or target current signals

are used [15]. X-ray signals from a ratemeter can also

be employed to modulate the Y-axis.

The following is a more detailed description of several

of the functions.

a. Translation and rotation of an entire area

Electronic translation of the field of scanning, especially at high magnification, simplifies positioning the area

selected to be analyzed. It removes the need for mechanical

manipulations, which can be cumbersome at high magnification.

Rotation is most useful when a line scan is performed. It

permits adjusting the angular position of the line scan on

the specimen without mechanical manipulation. Rotation is

always about the center of the field of view, and independent

of translation. Electronic translation and rotation are as

easy for the operator at high magnification as the mechanical

equivalents are at lower magnification.

39
Figure 17. Y-axis modulation of target current signal

with oblique view-field presentation. Same

specimen and area as Fig. 13

.

40
b

.

Zoom control

The zoom magnification capability, which was available

in the original equipment, has been retained in our design.

Besides the obvious advantage of continuous control of magnification, at any kilovoltage, the following mode of operation is useful. Since one can increase magnification until

no beam deflection occurs in the electron probe, (infinite

magnification), one can go from a scanning mode to a static

(point-analysis) mode in a continuous fashion. This obviates

the need for a separate static-beam control. The advantage

of going to a static beam in the above manner lies in the

security that one gains by watching the beam scan collapse

into the spot selected for analysis.

c

.

Fast Scanning

There are several advantages in examining a specimen,

particularly a large one, by scanning techniques, rather than

using the optical microscope of the electron probe. In the

first place, the magnification of scanning can be adjusted

continuously and quickly over a very wide range. The depth

of focus of the scanning image is far larger than that of the

optical image, and the quality of electronic image is generally

better than that of the optical image, particularly on nonmetallic specimens. Furthermore, the oscilloscope scanning

image can be observed simultaneously by several persons.

However, at slow scanning speeds, the completion of a scanning

frame must be obtained every time the position of the area

scan on the specimen is changed. Therefore, on the new

scanner, we have provided speeds which produce a continuous,

coherent picture so that mechanical translation of the specimen is followed instantaneously by the corresponding change

of image on the oscilloscope.

The new beam scanner is a self-contained, versatile

device of excellent long term stability. It may be used with

any X-Y display oscilloscope accepting 10-volt level signals

for X-, Y- and Z-axes. It contains most of the imaging and

41
x-ray selection functions of the microprobe under the control

of one rotary switch.

A diagram of the scan driver is located at the end of

this publication as Appendix II.

2

.

Electron Lens and Power Supplies for Higher Beam

Resolution

In order to reduce the diameter of the electron beam,

we have acquired and installed a new condenser lens of

shorter focal length and a new Wehnelt cylinder (grid cap).

With these modifications, it is now possible to realize,

_o

routinely, probe diameters of 1/4 ym at a current of 2 x 10 A,

Previously, our probe diameter, at this current, was 1/2 ym.

At a beam current of 10 A, these improvements should reduce

o the beam diameter to 500 A. However, using this beam intensity for scanning images would require the installation of a

secondary electron detector. Such an installation would be

impossible without fairly extensive redesigning of the instrument . We have also constructed new power supplies for both

objective and condenser lenses. These supplies are interchangeable and are far more stable than the previous units.

Present long-term stability is + 5 yA in .1 A (50 ppm) after

one hour warm-up. This eliminates any perceptible drift in

the field strength of the lenses.

3

.

Residual Gas Analyzer (RGA)

This device (Figure 18), installed on the top of the

electron probe tank, permits us to characterize residual gas

composition in the electron probe after pump-down. The

RGA is a small mass spectrometer that ionizes residual gases

by means of a heated filament. The range extends from mass

to charge ratios of 2 to 100.

42
Figure 18. Residual gas analyzer mounted on top of the

tank of the electron probe microanalyzer

.

A useful observation made with this device concerns

the pump-down cycle of the microprobe. Bleeding atmospheric

air into the sample chamber, and especially the main tank,

leaves a considerable amount of water in the system. This

water adheres tenaciously to the walls, requiring up to 24

hours to pump out. Water is known to be a significant cause

of corrosion of the filament. Hence, we now eliminate the

water contamination by venting dry nitrogen into the sample

chamber, rather than air. Figure 19a shows the magnitude

of the water signal immediately after pumping down the sample

chamber (which had been vented with air). This signal exceeds

those of all other constituents. After 24 hours of pumping,

the water signal is still fairly large (Figure 19b). The

argon shown in the spectra is due to leaking of the filling

(Ar, 10$ CHk ) of the thin-window x-ray detectors.

43
Figure 19. Residual gas spectra of the atmosphere within

the tank; immediately after venting the sample

chamber with air (a), and after 24 hours of

continuous pumping (b).

44
An initial attempt at observing, with the RGA, ions

freed from the sample surface due to impact of the electron

beam met with no success. The samples used were organics

and salts. Other investigators successfully applied this

technique in rare gas determinations in stoney meteorites

[16], and lunar material [17].

B. Scanning Techniques and Sample Preparation for Small

Particles and Biological Thin Cuts

In the past, most of our research has been focused on

large, flat specimens of thickness exceeding the depth of

electron penetration. This is the form of specimen in which

most of the metallurgical and mineral materials are presented

to the electron probe; quantitative techniques are usually

based on the assumption that the specimen is flat and of

"infinite" depth and width.

There are, however, areas of application in which such

a specimen configuration is impossible. The analysis of

small particles (in this context, of diameter below 10 um)

is of great significance, for instance, in studies of air

pollution. The importance of the analysis of thin films

(thickness less than 1 ym) in many technological devices is

well recognized. An especially difficult case is presented

by biological materials. The low density of soft tissue

renders the paths of penetration of the electron undesirably

large at the usual acceleration potentials. One can increase

resolution in spatial dimensions by analyzing thin sections;

such sections are also required in the customary microscopic

techniques (light microscopy of stained sections and transmission electron microscopy). But such thin sections,

particularly if not stained with heavy elements, show poor

contrast in the usual target-current or secondary -electron

imaging procedures in the electron probe. It is for this

45
reason that costly transmission electron microscopy attachments [18-20] are frequently used for biological specimens.

The analysis of biological materials is beset by two

further difficulties: biological tissues are easily damaged

by the heat which is produced by the impinging electron beam;

and the x-ray signals one obtains are generally weak, since

elements other than carbon, hydrogen, oxygen, and nitrogen

are present at low concentrations.

We have started a research program to explore the

conditions of analysis of small particles and thin films.

The ultimate goal of such a program ought to be the development of quantitative methods of analysis. However, a particle

or a detail of a histological specimen cannot be analyzed

unless they can be found in the electron probe; after locating

the feature, we still need conditions of specimen preparation

and mounting, and of excitation and x-ray detection, which

permit the reception of signals of sufficient intensity

without destruction of the specimen. We must therefore begin

by examining techniques of imaging and contrast production,

and then pay attention to the attainable x-ray intensities,

before considering the more complex problems of quantitation.

In this preliminary phase, we must reexamine matters already

covered by other investigators; therefore, we do not claim,

at this stage, priority or originality.

1. Handling of Particles

Quantitative analysis of dust particles is complicated

by their unknown geometry, since the smaller particles do

not stop all electrons penetrating them. Besides backscatter,

we have thus to consider the transmission of electrons.

Another practical problem arises from the electrostatic

charging of nonconductive particles. The charges may

create forces which not only may deviate or repel the electron

beam, but also may dislodge the particle if it is not firmly

46
mounted. Furthermore , a particle may suffer a large rise

in temperature if it or its surroundings have low thermal

conductivity and specific heat. These problems place

stringent requirements on the techniques for mounting particles, since these must be firmly held and have good

thermal contact with the mounting medium. Yet, the medium

must not be too heavy so as to significantly absorb the

impinging electrons or the x-rays emitted from the particle,

or to emit continuous or characteristic x-rays at a level

which would obscure the weak signals from the particle.

Further, the electrical resistance from the particle to ground

Q

should not exceed the order of 10 0, . A technique in which particles are mounted in very thin

films of formvar or collodion is presently under development.

The particles are entirely enclosed in a thin film as shown

in Figure 20. This creates good thermal and electrical

contact, while it does not impair electron or x-ray transmission. This film is mounted in such a manner that the

electrons traversing it travel more than 20 mm before impinging

upon an absorber of low atomic number. This arrangement

practically eliminates the detection of background radiation

other than the continuum generated in the particle itself.

€ I

Figure 20. Diagram of particle mounted within thin organic

film.

^7
Separate paths into the imaging electronics are provided

for the electrons absorbed within the specimen and for those

transmitted through the specimen and collected by the

absorber. This permits imaging configurations of high contrast. The parameters regulating the intensity of x-ray

emission will be studied in more detail at a later date.

The film is highly transparent to light, and the specimens can be examined with a standard microscope and then

transferred to the electron probe without changing the

mounting.

The preparation, as developed to date, is as follows.

A 10$ formvar (powder) - 90$ ethylene dichloride (by weight)

solution is prepared and the particles are suspended in this

slightly viscous liquid. One drop of the solution is now placed

onto a pure water surface and a very thin formvar film forms

instantly, extending over several square centimeters of the

water surface. The particulates are entrapped in the film.

A common fiber washer, with an inside diameter of 1/4

inch, is placed on the film. By delicately pressing the

washer into the film, a bond is made. After trimming off

the film outside the washer, it may be lifted from the surface

of the water.

Electrical conductivity is provided by evaporating

carbon onto both sides of the film, with the bottom side

receiving a somewhat heavier coat than the top. The carbon

film also improves the thermal and mechanical properties of

the formvar film.

An analogous procedure is followed if collodion rather

than formvar is used. A 50$ ethyl alcohol - 50$ Flexible

Collodion U.S. P. solution seems to be adequate in this case.

The chief difference between the two materials is that formvar

films are more uniform in thickness while collodion tends to

develop a fibrous structure. A scanning electron micrograph

of a collodion film is shown in Figure 21.

48
Figure 21. Absorbed electron scanning image of fly ash

particles mounted in collodion. Magnification

25 ym/cm.

The x-ray signals from four randomly chosen particles

in the area of Figure 22 (small fly ash in collodion) are

shown in the accompanying graph. The elements present are

labeled on the abscissa. The ordinate is in arbitrary

intensity units

.

2 . Analysis of Biological Specimens

In the study of biological specimens, the observer must

distinguish and recognize microscopical features of interest

before attempting to analyze them. The ease of observation

and orientation frequently determines success or failure of

biological microanalysis. Typically, the biologist has

observed a thin tissue section with either the help of optical

microscopy or of transmission electron microscopy. The first

task in electron probe microanalysis is to identify locations

and features first observed with the above mentioned tools.

49
While optical microscopes are incorporated in the electron probe, their quality is usually unsatisfactory for histological observation, owing to spacial limitations. Besides,

the investigation of the distribution of elements in watersoluble form precludes the use of staining procedures. The

same objection must frequently be raised to the use of

staining with heavy elements as sometimes employed in transmission electron microscopy. There is undoubtedly a demand

for a scanning procedure which provides a sub-micron resolution

and sufficient contrast to be used with unstained preparations

of thickness below one micron.

Special electron probe instruments containing optical

microscopes of high resolution [21] or provisions for transmission electron microscopy [18-20] are now available. Still,

in view of the wide diffusion of standard electron probes,

it is worthwhile to experiment with alternative solutions

which are available with the standard instrument. The extensive use of scanning electron microscopy in electron probe

microanalysis suggests that such techniques be investigated.

However, as stated before, in order to achieve the desirable

spatial resolution, we are frequently forced to use thin

sections; the contrast obtainable from such specimens,

particularly if unstained, is insufficient if either target

current or secondary electron signals are employed.

We are presently experimenting with scanning electron

microscopy using transmitted current as a signal. The specimen is mounted on a thin film, as advocated by Hall [22];

this is a prerequisite for the observation of low concentrations which require maintaining a low x-ray background. The

contrast in the observation of such thin specimens by transmission electron microscopy is created, not by absorption,

but by scattering of electrons [23]. The same principle can

be applied to the observation of specimens which are scanned

with an electron beam. In this case, the undeflected beam is

50
Figure 22

.

Pulse-height spectra of four fly ash particles

mounted on collodion film, obtained with lithiumdrifted silicon detector. Abscissa represents

photon energy, ordinate represents x-ray intensity

on an arbitrary scale.

51
To Specwea/

To Ground •

To T/1A6//V6

ELECTRONICS

Electron Beak

Biolo&ical Matekial

Shadow /Iask

ScATTEAEO ElECTXOA/S

i Trra/smtted

Electron Collector

Figure 23. Schematics of specimen holder for the detection

of scattered (transmitted) electrons.

intercepted and led to ground; the electrons which were

scattered out of their original direction are collected in

a ring-shaped collector, and used to form the signal. Figure

23 schematically shows a specimen holder we have developed

for this purpose. An electron micrograph prepared with this

technique is shown in Figure 24.

We mount the biological tissue sections on thin organic

films, such as collodion, formvar, or stretched polypropylene

The microtome cuts can be floated on water and picked up with

such a film, stretched over a small fiber washer. After the

assembly has dried, both sides of the film are coated with

carbon.

Satisfactory constrast can be obtained by this method

from unstained tissue sections of thickness below 1 urn. Since supporting grids are avoided, and since the supporting

film is very thin, the x-ray background is also very low,

and there are no characteristic lines present which are not

generated within the specimen.

52
Figure 24. Scanning transmission electron micrograph of

unstained cartilage tissue obtained with the

device shown in Fig. 23- Operating voltage:

20 keV. Magnification: 6.6 urn/ cm (1500 X).

C . Quantitative Analysis

Research in quantitative electron probe analysis this

fiscal year was a continuation of the investigations initiated

last year [6]. 1. The study of the background corrections

was expanded to include measurement's of the limit of detection. 2. The theoretical study of the corrections for fluorescence due to both characteristic lines and continuous radiation has been complemented by the measurements of the Standard

Reference Materials (SRM's 48l and 482) of Au-Ag and Au-Cu

alloys [8]. 3. The documentation of the computer program,

COR, extensively described in our last report [6], has been

completed and the program MULTI 8 has been rewritten in

Fortran IV. 4. The practical aspects of determining the

compositions of phases in binary alloys have been examined.

We will now comment, in more detail, on some aspects

of the research outlined above.

53
1. Limit of Detection

Electron probe microanalysis is typically a microanalytical but not a trace analytical technique. Most proposed limits of detection are based on the assumption that

no errors other than those inherent in the Poissonian counting

statistics are present. However, as an investigator increases

his efforts to lower the limit of detection, non-Poissonian

errors become more prevalent, and he is left with an optimistic

estimate rather than a true measure of detection limits.

Thus, an estimate of the experimental standard deviation of

the background is a more appropriate expression of statistical

precision at the trace level than the Poissonian estimate of

standard deviation.

In an effort to determine the experimental standard

deviation of the background on realistic specimens, we have

measured the intensity of the CrKa x-ray line in a series

of lo'w alloy steels. The Standard Reference Materials 461

through 468 were chosen for this purpose for two reasons.

First, these steels have been well analyzed and range in

composition from 0.004 weight percent chromium to 0.74 weight

percent chromium. There are many other elements present in

these steels; however, all of them are low in concentration

and were not considered in our measurements. Second, and

of equal importance for microanalysis, these materials appear

to be homogeneous on a micron level. Standard Reference

Materials 46l and. 463 had been previously investigated by

electron probe microanalysis and by quantitative metallographic techniques [24-25]. It was then concluded that they

are sufficiently homogeneous so that any presently available

microanaly tical technique can be carried out with little

change of inaccuracy due to inhomogeneity . Multiple measurements on the other Standard Reference Materials in this

54
series indicate that they are equally homogeneous; however,

studies should be performed on these alloys to determine

the homogeneity of each Standard Reference Material.

The experimental conditions were chosen to match those

used typically on the electron probe. The target current

— ft was 2 x 10 amps at 20 keV and the counting time was 20 sec

for each data point. Some of the data obtained are plotted

in Figure 25. The results were fit to the line

k = mC + b (1)

by the method of least squares [26], where:

k = CrKa intensity (total counts)

m = slope

C = mass fraction (concentration) of chromium in specimen

and

b = background (k-intercept at C=0).

•

i

I0K

-

»ji

8

u

' [/r ::::rtii! ' < ..-., '

i

uc

"• -Or* Coctttt Crafts!

rir^

%:::::

-

' -

Figure 25. Cr Ka signal from low-alloy steels . Vertical

signal shows number of counts obtained in

20 sec.

55
The estimate of the standard deviation of the background

(s, ) could then be calculated with the following equation [26]

s b

(2)

where s, = estimate of the standard deviation of k

k

n = number of data points

and C. = concentration at point i.

1

The summations in equation 2 are for values of i from 1 to n The result is an estimate of the standard deviation of the

x-ray signal intensity obtained when the element is absent

(C = 0, k=b). In order to determine the estimate of the

standard deviation of the concentration, it is necessary to

divide s, by the slope of the line (m)

where s is an estimate of the standard deviation of a single

c

to measurement of the concentration at the background. Different authors have defined the limit of detection in a variety of ways; however, most definitions can easily be

related to the estimate of the standard deviation (s ) defined above. For one case of 20 data points, the limit

of detection (s ) for chromium in iron was calculated to be

c 0.008 weight percent.

2 . Further Measurements on Standard Reference Materials

Our efforts to improve the accuracy of quantitative

electron probe microanalysis have been in two directions.

The first involves careful measurements on well characterized

materials, as described in this Section, and the second is

56
concerned with developing the best possible computer program

for calculating the correction procedures, as described in

the following Section.

Intensity ratios were measured for CuKa, CuLa, AuMa

,

AuLa and AuL3 in the Cu-Au system Standard Reference Materials,

and for AgLa, AgL3 3 AuMa and AuLa in the Ag-Au system Standard

Reference Materials at 5, 10, 15, 20, 30, 40, and 48.5 keV.

An example of the results is shown in Figure 26 where the

ratios of the relative intensities to the concentrations are

plotted versus the relative intensities for CuKa.

Comparisons of theoretically calculated intensity ratios

with the experimentally measured ratios are being made in

hopes of improving the calculations. Data on CuKa obtained

from the 40Cu-60Au alloy are shown in Figure 27. The complete results of these measurements are in the process of

being published as an NBS Special Publication [9]-

3 . Computer Programs

The above mentioned computer programs, COR and MULTI 8

have been used for the calculations mentioned in Section 2.

Both of these programs are to appear shortly in a publication

describing the calculation procedures used and explaining

how to use the programs. The program, COR, has been extensively tested, documented, and flow-sheets have been drawn.

MULTI 8 is a comparatively short computer program written

in the BASIC language for the correction of electron probe

microanalyzer x-ray data on a time-shared computer. The

following comments briefly outline the calculations performed

by the program. The generation equation (atomic number

correction) follows a modified procedure of Poole and Thomas

[27]. The stopping power is calculated from the Bethe equation [28], employing the mean ionization potentials proposed

by Berger and Seltzer [29]. The backscatter losses are

57
k/c I5kv

Au-Cu

Cu Ka

Figure 26

.

The copper Ka measurements in gold-copper binaries

are represented by plotting the ratio k/C on the

ordinate, and k on the abscissa. The thin,

almost vertical lines connect points corresponding to the same composition, which can

be read on the horizontal scale, where k=C

.
.52

.51

V

• EXPERIMENTAL

a COR b a S .50 A a A COR B a S ( no cont.

)

» COR DUNCUMB

V COR DUNCUMB (no cont.)

.49 °*

MULTI8 BS S O MULTI8 DUNCUMB

O MULTI8 B BS (no fl.) COR bss (nofl.)

.48 o\ D MULTI8 BBS KAMAN

.47 -

O 9

\ T

.46 &

A T\ °

.45 o A \ »

.44

O

A \

\

.43 — A \

\

\ B

.42 ~~ \ A O

.41 O ~~1

.40 A

.39 O

.38

.37

1 1

i 1 1 1 1 1 i i 10 20

1

30 40

kv

I

1

50

1 .96 .85 .80 f(X)

Figure 27. Experimental and theoretical intensity ratios

of Cu Ka for a nominally Au60-Cu^0 alloy. Note

the spread of theoretical predictions depending

on the choice of theory and parameters. (For

a detailed discussion on this subject see [9]).

59
calculated by a procedure advocated by Duncumb and Reed [30].

The calculation of the absorption of primary x-rays uses the

modification by Heinrich [31] of the procedure of Philibert

[32] and Duncumb [33]- The fluorescence by characteristic

lines is calculated by the method of Reed [3^]. There is

no provision for correcting the effects of fluorescence

produced by continuous radiation. The iteration procedure

is a modification [31] of that proposed by Criss and Birks

[35]. Since we use this program extensively for calculating

the electron probe results,, we rewrote it in Fortan IV for

the Division's new EMR 6135 computer. The rewriting of this

program also allowed us to gain some experience in programming

the new computer.

4 . Studies on Binary Alloys .

In cooperation with Mr. R. M. Waterstrat, of the Dental

Research Group, we have compiled the following list of

advantages of the use of an electron probe microanalyzer for

determining the compositions of phase boundaries in binary

alloys, with suggestions concerning this technique. These

boundaries have usually been determined by either optical

methods [36] or by x-ray diffraction methods [37]- The major

difficulty with both of these techniques is the large number

of specimens required to determine a particular phase boundary

Our observations are based on extensive microprobe analyses

of the binary alloys chromium- platinum, chromium-iridium,

chromium-rhodium and vanadium- pi at! num. The results of

this work may be found in an NBS report [38].

Two types of specimens may be examined with the electron

probe to directly yield the phase boundary compositions.

In the past, solid state diffusion couples have been studied

with the electron probe microanalyzer > in many instances,

with reasonable success [39]. This method is attractive,

since it requires only one specimen for an entire phase

60
diagram. However, sometimes the phase regions are too narrow

to obtain good quantitative results, and some phases may be

missing entirely from the diffusion couple. The other type

of specimen, discussed below, is annealed and quenched from

within a two phase region in the same manner as for the optical

method mentioned above

.

All the specimens we studied were formed by arc-melting

the two pure components together into a button of the particular composition required. These buttons are then annealed

at various controlled temperatures at which information is

required, and they are quenched. The resulting button is

cross-sectioned, mounted in bakelite and metallographically

polished. The electron probe microanaly zer may then be used

to examine the phases present. This technique has the following advantages over the older methods mentioned above:

a. Analyses may be easily performed on material

located near the center of a button. Material near the outer

edge of a button could have changed composition due to preferential vaporization of one component during arc-melting or

annealing.

b. Small oxide inclusions which may form during

melting can be avoided during analysis.

c. Specimens which may have become contaminated

can easily be tested for the impurities.

d. The compositions of the phase boundaries on

either side of a particular specimen can be determined by

analyzing both phases in that specimen. As a result, fewer

specimens are required than are necessary when either optical

metallography or x-ray diffraction is used.

e. Broken areas of brittle specimens and holes in

porous specimens can easily be avoided. This could possibly

save an otherwise unusable specimen.

In order to obtain the best results from an electron

probe microanalysis, the following suggestions are offered.

61
a. A good optical examination should be made prior

to electron probe microanalysis. One must beware of decompositions into fine-structured material such as an eutectoid.

Very fine precipitates may be missed either optically or

with the microprobe.

b. Specimens near a eutectic composition should

not be used. Eutectics are usually too fine-grained to yield

good quantitative analyses. Near a phase boundary, the minor

phase forms larger grains and is more easily analyzed.

c. For dependable results, the phases should be

evenly distributed throughout the specimen and all grains

of the same phase should have the same composition.

D . Service Analyses

We have performed a large number of service analyses on

a wide variety of materials, including the following.

1. Variations in concentration of several silicate

minerals were investigated in thin sections of lunar materials

from Apollo 11, 12 and 14 in a cooperative program with NASA

Goddard.

2. Analysis on various materials affected by corrosion

or other failure processes. These include:

a. Cracks in a helicopter part

b. A section removed from a part of a ruptured

tank car

c. A scab on an aluminum alloy section from a

ruptured liquid-oxygen cargo tank

d. Corrosion of an aluminum aircraft propeller

e. Oxidic surface on test specimens of TD-nickel

heat shields for a simulated atmospheric

reentry vehicle

62
3. Binary two-phase alloys: Very accurate measurements

were performed on the systems chromlum-iridium and chromiumrhodium as part of a program to investigate the respective

equilibrium phase diagrams [38]. The compositions and homogeneity of tungsten-rhenium lamp wires were also measured.

4. A variety of single crystals were analyzed for

composition and for variations in composition. These include:

a. Lead-tin-tellurium crystals

b. TITe and TlBiTe

2 crystals

c. A $-Ca~ (PCOp micro-sphere crystal

5. Extensive analyses were performed to determine the

compositions and distributions of inclusions in the steels,

SRM 661-5 . This was done in order to ascertain their suitability as microanalytical standards. At the present time,

the certificates on the Standard Reference Materials are

being prepared.

6. Qualitative analyses of fine particulates such as

fly ash and air pollutants have been performed.

7. Other miscellaneous investigations included the

quantitative analyses of evaporated thin films of various

alloys, variation in composition around a laser lesion in

glass, the homogeneity of an In-Ga alloy, and qualitative

analyses of "polywater"* solder on a circuit board, crystals

on a filter paper, a surface smear on aluminum oxide, ink

on counterfeit money, and the calcium distribution in a human bone

.

C. E. Piori, R. L. Myklebust

63
5. PRECONCENTRATION TECHNIQUES

In previous Annual Reports of this Section's activities

[4-6] , separation and preconcentration procedures have been

reported for determining trace elements in a variety of

materials. This year's focus has been placed on developing

procedures for analyzing important types of environmental

samples and certifying several new Standard Reference Materials. Examples of these applications will be given in some

detail to illustrate the utility of the techniques.

A. The Interaction of Nitrilotriacetic Acid (NTA) Solution

with River Sediments

The sodium salt of nitrilotriacetic acid (NTA) was one

of the materials proposed by detergent manufacturers to

replace polyphosphates in detergents. However, because of

its chelating properties, dilute solutions of NTA could potentially extract and solubilize metallic elements contained in

the suspended matter and sediments of bodies of water. By

this process, toxic metals present in a relatively innocuous

form could be converted to a bio-assimilable form. Biological

retention of these metals in the food chain could result in

concentrations occuring in food fish that would be harmful

for human consumption.

To investigate these potential ecological faults of

NTA, the Federal Water Quality Administration, (now Water

Quality Office, Environmental Protection Agency) established

a project at NBS. The basic study in this investigation was

the interaction of sediments with very dilute NTA solutions

under conditions reasonably to be expected in bodies of water.

Trace analytical techniques were used to determine the chelating action of NTA.

64
A number of river and coastal sediments were obtained,

from which samples were taken for qualitative optical emission

analysis by Mrs. M. Darr. These analyses permitted the selection of sediments having elements of special interest at

diverse concentrations, for equilibration studies with water

and with 20-ppm NTA solutions. R. A. Paulson, of the Microchemical Analysis Section, performed the equilibrations by

using a mechanical shaker to agitate the sediments with water

and 20-ppm NTA solutions. Following agitation, the solutions

were centrifuged.

An isotope dilution, preconcentration technique, using

spark-source mass spectrometry (ID-SSMS), was one of the

methods developed to analyze these solutions. Previous

applications of this method have been described [40-42].

In the ID-SSMS method, the concentration of an element in

a matrix is determined from the change produced in Its

natural isotopic composition by the addition of a known

quantity of the same element, the isotopic composition of

which has been artificially altered (spike). Since an isotopic ratio of the final isotopically equilibrated material

is measured to obtain the concentration, the results are not

invalidated by losses of the trace element analytes. By

the use of preconcentration techniques and multiple spikings,

a number of trace elements can be determined simultaneously

with high sensitivity. The results are calculated using:

W K (A - B R)

C = sp S£_

M (BR - A)

where C is the concentration in ppm (yg/g), W is the weight

of isotopically enriched materials (spike) added in ug, M is

the weight of sample in g, A and B are the natural abundances

of the analyte isotopes a and b, A and B are the abundances

S ]j s p

of isotopes a and b in the spike, R is the measured altered

ratio of isotope a to isotope b, and K is the ratio of the

natural atomic weight to the atomic weight of the spike.

65
In the method developed, information was obtained on

the concentrations of fourteen elements in the solutions from

the equilibrations of the sediments with water and 20 ppm

NTA solutions. These elements were: Ag, Ba, Cd, Cr, Cu, Fe

,

Hg, Mo, Ni , Pb, Sb, Sn , Sr , and Zn. Solutions of the enriched

isotope materials were prepared for the elements to be determined. Chemically compatible solutions were combined and

volumetric additions of these "multiple-spike" solutions were

introduced into volumetric flasks. The flasks were made to

volume by adding portions of the water (0 ppm NTA) and 20

ppm NTA solutions that had been equilibrated with the sediments. Aliquots of these spiked samples were pipetted into

small quartz flasks and 0.3 ml of a 1:1 nitric-perchloric

acid mixture were added to each flask. The acids were of

high-purity grade. After evaporating the solutions in a

"clean environment chamber" [40], the solutions were heated

further to HCIOl fumes. This step destroyed the NTA and

equilibrated the analytes with the enriched isotope spikes.

The residue was dissolved in distilled water and the resulting

solution was transferred to a Teflon electrolysis cell. The

isotopically altered analytes were electrodeposited onto two

high-purity gold wire cathodes connected in parallel. Two

gold wires served as the anodes. The cathodes were sparked

in the spark-source mass spectrograph and the spectra were

photographically recorded. Por the initial samples, it was

found that the solutions had been "over-spiked," that is,

the concentrations of the trace elements were appreciably

lower than anticipated. Consequently, to obtain suitable

isotope ratios for more accurate measurement, aliquots of

the spiked samples were diluted with known volumes of the

sample solutions and the procedure was repeated. The results,

in micrograms per milliliter of solution, were computed from

the isotope dilution equations. Method blank determinations

were made under the same experimental conditions using the

same volumes of acids.

66
Tables 3 and 4 list the Isotope dilution-spark source

mass spectrographic determinations of the fourteen trace

elements in water (0 ppm NTA) and 20 ppm NTA solutions

equilibrated with sediments. The elemental determinations

were made simultaneously in each sample. These data, together

with those obtained in the Division using several other analytical techniques, formed the basis for the conclusions presented in a formal report to the Environmental Protection

Agency

.

Table 3. Concentrations in micrograms of element per

milliliter of solution which had been interacted with

river bottom sediment (Pb, Hgj Sn 3 Cd, Zn, Cu and Fe)

Sample ppm

Designation NTA Pb Hg Sn_ Cd Zn Cu Fe

#14 0.06 <.01 0.002 <.001 0.03 0.02 0.3

pH 9 20 .04 <.01 .002 <.001 .02 .02 .6

#15

pH 7

#16

pH 8.2

#22

pH 7

#34

pH 9

#34

pH 7

#35

pH 7.7

• 03 0.1 <. 01 0.002 .02 .04 .5

20 .08 .1 <. 01 .007 .1 .02 • 5

.09 .03 . 02 .001 .05 .04 4

20 .06 . 01 .003 .001 .07 .02 2

.03 .2 <. 004 <. 001 .03 .03 1

20 .02 .2 <.004 <. 005 .04 .03 1

.11 .01 .002 .001 .06 . 020 1

20 .12 .01 . 001 . 002 .07 .02

6

1

.2 .2 <.002 <. 005 .08 .02 1.4

20 .1 .2 — — .05 .02 1.5

.1 .01 <.001 .002 .08 . 02 2

20 .2 <. 01 <. 001 . 002 .5 .03 1

67
Table 4. Concentrations in micrograms of element per

milliliter of solution which had been interacted with

river bottom sediment (Ba, Sb , Mo, Sr, Cr, Ni and Ag)

Sample ppm

Designation NTA Ba Sb Mo_ Sr_ Cr_ Ni_ Ag_

#14 0.06 .02 .2 1.1 — C).03 <. 001

pH 9 20 .06 . 02 .1 1.2 .2 .04 <. 001

#15 .07 — — • 3 .04 . 01 ^.002

pH 7 20 .1 -- — .4 .05 .2 <". 001

#16 — .004 .05 — .1 .06 .006

pH 8.,2 20 — . 004 .03 — .1 • X

5

. 001

#22 <0 <.l — .03 .02 .03 .01 <.001

pH 7 20 <.l — — .09 .3 . 06 <. 001

#34 — . 001 < . 003 .3 — — <.001

pH 9 20 .04 .001 .006 .3 -- -- <.001

#34 <.03 — — .2 . 02 . 01 <.001

pH 7 20 <.03 — <. 004 .2 . 006 .08 --

#35 .2 .001 .003 — .1 .04 <.001

pH 7. 7 20 . 001 . 002 .1 •v <.001

B. Orchard Leaves, St.andard Reference Mat;erial 1571

1. De term! nation of Fe, Pb, Zn , Cu, Ni , arid Se

The concentrations of certain elements in leaf samples

from fruit trees are important in diagnosing nutrient disorders and suggesting cultural treatment [43]. Other elements

are also of interest. For these analyses, rapid instrumental

68
methods are generally used. Synthesized standards are often

used to calibrate the Instrumental response. However, more

reliable results can be obtained when a botanical matrix

with reliable concentration values is used for the calibration;

and, such a Standard Reference Material can be used to check

for bias in the analytical procedure. In making interlaboratory comparisons of the results obtained on the analysis

of kale powder, Bowen [44] listed a number of elements for

which the results from different laboratories were in disagreement. "Gross discrepancies" were reported for nickel

and mercury

.

We have developed a preconcentration ID-SSMS method for

simultaneously determining Ni , Fe , Pb, Zn, Cu, and Se in a ground orchard-leaf material subsequently issued as Standard

Reference Material 1571- Because of its volatility, mercury

was determined separately by a special ID-SSMS procedure.

In one of the procedures, enriched-isotope spikes of Fe , Pb

,

Zn, Cu, Ni, and Se were added to samples which were oxidized

with nitric and perchloric acids . The solutions were then

evaporated to dryness to remove the acids. After adding a small amount of water, the equilibrated trace elements from

an aliquot of the solution were electrodeposited on highpurity gold wire electrodes. The wires were sparked in the

mass spectrograph and the spectra were photographically

recorded. Results were computed from the measured isotopic

ratios using the general isotope dilution equation. These

results are shown in Table 5- As part of the method, the

concentrations of the spike solutions were verified and

system blanks were determined.

During the course of the analysis, a white residue was

observed after destruction of the organic matter. This

residue was approximately ,k% by weight. A qualitative

optical-emission analysis by Mrs. V. C. Stewart indicated

that it contained mainly aluminum and silicon. Iron and

69
Table 5« Average concentrations in the solution obtained

from wet-ashing one-gram samples of Orchard Leaves

SRM 1571 - determined by isotope dilution spark-source

mass spectrometry

Average Cone.,

Element ppm by wt

.

Iron 278 + 43

Lead 43 + 4

Zinc 28+3

Copper 12+2

Nickel 1.2 + 0.2

Selenium 0.0 8 + 0.02

aUncertainty is expressed as the 95% confidence limits of a single determination.

copper were estimated to be 0.1 to 1% } and 0.001 to 0.01$

respectively of the residue. The most sensitive spectral

lines were not detected for the other elements being determined by ID-SSMS. Selenium is not evaluated in the optical

emission procedure used.

2 . Determination of Mercury

A preconcentration method using ID-SSMS was developed

for determining the mercury content of Orchard Leaves,

Standard Reference Material 1571. Since we intend to detail

the method in a future publication, only a brief description

of the method is given here. A number of experiments were

made with the apparatus shown in Figure 28, which is similar

in design to that described for wet-oxidizing organic matter

[45]. In our procedure, an additional function of the apparatus is to promote equilibrium between the natural mercury

in the sample and the enriched isotope spike, as will be

described.

70
A~-^

w

n

Figure 28. Apparatus for digestion of organic samples

and equilibration of mercury.

71
Samples were weighed into flasks, spiked with known

volumes of solution containing an enriched isotope of mercury,

and heated with nitric acid after assembling the apparatus

.

Perchloric and nitric acids were then added through the

condenser and heated. To completely oxidize the organic

material, the stopcock to the chamber was closed so that

nitric acid could distill and collect in the chamber, thus

increasing the concentration of perchloric acid in the flask.

Because some of the mercury accompanies the distillate, the

stopcock was opened, returning the distillate to the flask,

thus equilibrating the mercury. After this step, loss of

mercury does not invalidate the results. To concentrate

the isotopically equilibrated mercury for electrodeposition

onto gold- wire cathodes, the chamber and bubbler were removed

and the acids distilled through the condenser from which water

had been removed. After the electrolysis, the analysis was

completed by sparking the wires in the mass spectrograph,

measuring the isotopic ratios, and calculating the concentrations from the general isotope dilution equation. The

results obtained agreed with those by activation analysis

and atomic absorption spectroscopy, leading to a proposed

certified value of 0.155+0.015 yg/g.

These activities have been conducted as a join investi'

gation with Dr. Paul J. Paulsen of the Analytical Mass

Spectrometry Section.

R. Alvarez

72
6. LIST OF PERSONNEL AND ACTIVITIES

A . Personnel

Spectrochemical Analysis Section

Bourdon F. Scribner_, Chief (Promoted 1/71 to Deputy

Division Chief)

Kurt F. J. Heinrich, Acting Chief (as of 1/71

)

Stanley D. Rasberry, Acting Assistant Chief (as of

1/7D

Karen L. Loraski, Secretary

Donald C. Reid (Cooperative student program 1971)

Shelia M. Cregger (Youth summer program 1971)

Carolyn Perry (Youth summer program 1970

)

Mary Simms (Youth summer program 1970)

Group I. Electron Probe Microanalysis

Kurt F. J. Heinrich, Chemist

Robert L. Myklebust, Chemist

Charles E. Fiori, Electronics Technician

Donald L. Vieth (Extended leave for educational

purposes

)

Group II. X-Ray Fluorescence Spectrometry

Stanley D. Rasberry, Physicist

Jerome S. McKay , Jr., Laboratory Assistant

Group III. Optical Spectrometry

Joseph L. Weber, Jr., Physicist

Martha M. Darr, Chemist

Virginia C. Stewart, Chemist (Retired)

Doward M. Bouchette, Physical Science Technician

(Retired)

Group IV. Enrichment Techniques

Robert Alvarez, Chemist

73
B. Publications

1. French^ B. M., Walter, L. S. , and Heinrich, K. F. J.

Quantitative Mineralology of an Apollo 11 Lunar

Sample, Geochim. Cosmochim. Acta 1, 433-44 (1970).

2. Heinrich, K. F. J.

Present State of the Classical Theory of Quantitative

Electron Probe Microanalysis, NBS Tech. Note 521

(1970)

.

3. Ahearn, A. J.

Quantitative Analysis of Solids by Spark Source Mass

Spectrometry in Proceedings of International Conference on Mass Spectroscopy , Kyoto, Japan, Sept. 8-13,

1969, 150-157 (1970).

4. Scribner, B. F. (Editor)

Activities of the NBS Spectrochemical Analysis Section

July 1969 to June 1970, NBS. Tech. Note 542 (1970).

5. Yakowitz, H., Fiori, C. E., and Michaelis, R. E.

Homogeneity Characterization of Fe-3Si Alloy, Nat.

Bur. Stand. (U.S.), Spec. Publ. 260-22, 22 pages

(1971).

6. Hicho, G. E., Yakowitz, H., Rasberry, S. D., and

Michaelis, R. E.

A Standard Reference Material Containing Nominally

Four Percent Austenite, Nat. Bur. Stand. (U.S.),

Spec. Publ. 260-25, 14 pages (1971).

7. Hicho, G. E., Yakowitz, H., Rasberry, S. D., and

Michaelis, R. E.

A Standard Reference Material Containing Nominally

Four Percent Austenite in Advances in X-ray Analysis , 14, 78-91, Plenum Press, N. Y. (1971).

8. Heinrich, K. F. J., Myklebust, R. L., Rasberry, S. D.,

and Michaelis, R. E.

Evaluation of SRM's 48l and 482 Gold-Silver and GoldCopper Alloys for Microanalysis, Nat. Bur. Stand.

(U.S.), Spec. Publ. 260-28, 89 pages (1971).

74
Talks Given

1. Rasberry, S. D., "The Division Computer System," Division

310 Scientific Discussion, July 15, 1970.

2. Heinrich, K. F. J., "Uncertainties in Quantitative

Electron Probe Microanalysis," Fifth National Conference on Electron Microprobe Analysis, Electron

Probe Analysis Society of America, New York, New York,

July 22, 1970.

3. Heinrich, K. F. J., "An Improved Target Current Amplifier

for the Electron Microprobe and the Scanning Electron

Microscope," Fifth National Conference on Electron

Microprobe Analysis, Electron Probe Analysis Society

of America, New York, New York, July 24, 1970.

4. Alvarez, R., "The Analysis of a New NBS Standard Reference

Material of Orchard Leaves by Isotope Dilution and

Spark Source Mass Spectrometry," The Chemical Institute

of Canada, Alberta, Canada, Aug. 20, 1970.

5. Heinrich, K. F. J., "Electron Probe Microanalysis, Quantitative Evaluation of Measurements (Theoretical

Aspects)," VI International Symposium on Microtechniques, Graz , Austria, Sept. 10, 1970.

6. Heinrich, K. F. J., "Simultaneous Display of Composition

and Topography by Color Composites of Electron Probe

Microanalyzer Scans," The Royal Microscopical Society

Symposia on Microscopy, London, England, Sept. 14 , 1970.

7. Rasberry, S. D., "X-ray Fluorescence and Optical Emission

Analysis of Five New Special Iron and Steel Standard

Reference Materials," Ninth National Meeting of the

Society for Applied Spectroscopy, New Orleans, La.,

Oct. 5, 1970.

8. Alvarez, R., "Llectrodeposition of Trace Elements on

Mercury-Coated Electrodes and Their Determination by

High-Voltage Spark Excitation," Ninth National Meeting

of the Society for Applied Spectroscopy, New Orleans,

La. , Oct. 9, 1970.

9. Alvarez, R., "Trace Determinations by Isotope DilutionSpark Source Mass Spectrometry," Division 310 Scientific Discussion, Oct. 14, 1970.

10. Heinrich, K. F. J., "Electron Probe Microanalysis," Wayne

State University, Detroit, Mich., Nov., 1970.

75
11. Rasberry, S. D., "Quantitative X-ray Spectrography

Regression Methods," Eastern Analytical Symposium,

New York, N. Y. , Nov. 8, 1970.

12. Alvarez, R., "The Determination of Problem Elements in

New NBS Standard Reference Materials by Isotope Dilution, Spark Source Mass Spectrometry," Middle Atlantic

Regional Meeting of the American Chemical Society,

Baltimore, Md. , Feb. 4, 1971.

13. Heinrich, K. F. J., "Electron Probe Microanalysis and

Its Geochemical Applications," Department of Chemistry,

University of Maryland, College Park, Md. , Feb. 5, 1971.

14

.

Heinrich, K. F. J., "Electron Probe Microanalysis and

Its Geochemical Applications," Division 310 Scientific

Discussion, Feb. 10, 1971.

15. Rasberry, S. D. , "Computers in Spect rochemical Analysis - The Software Byte," Pittsburgh Conference on Analytical

Chemistry and Applied Spectroscopy, Cleveland, Ohio,

March 3, 1971.

16. Alvarez, R., "The Characterization of an NBS Botanical

Standard Reference Material for Environmental Lead

and Nutrient Element Monitoring," Pittsburgh Conference

on Analytical Chemistry and Applied Spectroscopy,

Cleveland, Ohio, March 4, 1971.

17. Heinrich, K. F. J., "The Analysis of Trace Constituents

with the Electron Probe Microanaly zer , " l6lst National

Meeting of the American -Chemical Society, Los Angeles,

Calif., March 30, 1971.

18. Rasberry, S. D., "Recent Developments in X-ray Fluorescence Spectroscopy," Division 310 Scientific Discussion,

April 21, 1971.

19. Alvarez, R., "Chemical Preconcentration Techniques for

Analyzing NBS Standard Reference Materials by Optical

Emission Spectroscopy," "Metrochem ! 71," American

Chemical Society, San Juan, Puerto Rico, May 2, 1971.

20. Alvarez, R., "Simultaneous Determination of Cu , Ag, Zr,

Se, Te, Ce, and Nd in Special Steel NBS SRM 1261 by

Isotope Dilution, Spark Source Mass Spectrometry,"

"Metrochem '71/' American Chemical Society, San Juan,

Puerto Rico, May 2, 1971.

21. Darr, M. M., "Observations on Unique Sample Handling

and Spectroscopic Techniques in Several Laboratories,"

Division 310 Scientific Discussion, May 5, 1971.

76
22. Heinrich, K. F. J., "Advances of Electron Probe Microanalysis at the National Bureau of Standards,"

Canadian Probe Users' Group, London, Ontario, Canada,

May 11, 1971-

23. Alvarez, R., "Scientific Activities in Puerto Rico,"

Division 310 Scientific Discussion, May 19, 1971

24. Heinrich, K. F. J., "Scanning Electron Probe Analysis

Techniques," Lehigh University, 3ethlehem, Penn.,

June 22, 1971.

25. Heinrich, K. F. J., "Quantitative Electron Probe Analysis

Evaluation of Correction Procedures," Lehigh University,

Bethlehem, Penn., June 23, 1971.

77
D. Committee Activities

B. F. Scribner

Member, ASTM Committee E-2 on Emission Spectroscopy

Member, ASTM Committee E-13 on Absorption Spectroscopy

Member, Advisory Board, Spectrochimica Acta, Atomic

Section

Member, Analytical Services Committee, NBS Analytical

Chemistry Division

Member, Washington Editorial Review Board, NBS

Member, David Richardson Medal Committee, Optical

Society of America

Member, Publications Committee, Society for Applied

Spectros copy

K . F . J . Heinrich

Past President, Electron Probe Analysis Society of

America, 1970

Assistant Editor, Mikrochimica Acta

R. Alvarez

Member, ASTM Committee E-2 on Emission Spectroscopy

Member, Awards Committee, Baltimore-Washington Section,

SAS, 1970

J. L. Weber, Jr.

Member, ASTM Committee E-2 on Emission Spectroscopy,

Subcommittees IV, VII, and IX; Liaison to Committee B-7

Member, ASTM Committee B-7 on Light Metals and Alloys,

Cast and Wrought; Liaison to Committee E-2

Column Editor, Applied Spectroscopy

Alternate Delegate to Eastern Analytical Symposium from

Baltimore-Washington Section, SAS

S. D. Ras berry

Member, Laser Task Group, ASTM Committee E-2

Delegate, Baltimore-Washington Section, SAS, 1970-72

Member, Membership Education Committee, SAS, 1971

Member, Computer Evaluation Committee, NBS Analytical

Chemistry Division

78
M. M. Parr

Member, ASTM Committee E-2 on Emission Spectroscopy,

Subcommittee XII

R. L. Myklebust

Member, Yearbook Committee, Washington Section, ASM,

1970-72

79
7. ACKNOWLEDGMENTS

It is a pleasure to acknowledge the contributions to

our work of people from other groups. Frequently, their

cooperation has smoothed otherwise difficult paths.

In the area of developing microanalytical methods for

biological tissue, we gratefully acknowledge the advice and

cooperation of Dr. William Banfield, National Institutes of

Health, and Dr. Steven Doty, The Johns Hopkins University.

Dr. Richard Waterstrat, of the Dental Analysis Section,

h*as given us useful information on the identification of

metal alloy phases.

The cooperation of Dr. Gerald Sleater, of the Building

Research Division, on initial studies for detecting lead in

paint has been most helpful.

In the design and development of electronic instrumentation for spectrochemical analysis, the help of Louis Marzetta,

Measurement Engineering Division, has been indispensable.

Morris Schwartzmann of the same group has contributed to the

repair of electronic equipment.

As in past years, excellent support has been received

from the various NBS shops. Alex Fussinger of the Chemistry

Division Contact Shop has been especially helpful in the

fabrication of instrument parts without detailed drawings.

On numerous occasions, Herbert Carter and Eugene Deardorff,

Office of Standard Reference Materials, have lent an extra

measure of skill to the solution of difficult specimen

preparation problems; James Izlar, of the same group, has

given us needed laboratory assistance in times when our own

Section was under-manned.

Mrs. Rosemary Maddock and her group have continued to

give us much assistance in the planning of slides for talks

and illustrations for publication.

80
Finally, but most important, Karen Loraski, our Section

Secretary, has daily provided valuable assistance to members

of the Section in a variety of activities, especially in the

preparation and typing of complex manuscripts and reports.

This list of acknowledgments is clearly incomplete;

we are appreciative for assistance and counsel by many of

our friends within and outside of NBS.

81
LIST OP REFERENCES

[1] Scribner, B. F., Editor, "Spectrochemical Analysis:

Optical Spectrometry , X-Ray Fluorescence Spectrometry, and Electron Probe Microanalysis Technique,

July 1964 to June 1965/' U.S. National Bureau of

Standards Technical Note 272, U.S. Government Printing

Office, Washington, D. C. 20402 (Oct. 1965).

[2] Scribner, B. F., Editor, "rictivities of the NBS Spectrochemical Analysis Section, July 1965 through

June 1966," U.S. National Bureau of Standards

Technical Note 401, U.S. Government Printing Office,

Washington, D. C. 20402 (Sept. 1966).

[3] Scribner, B. F. , Editor, "Activities of the NBS Spectrochemical Analysis Section, July 1966 through

June 1967j" U.S. National Bureau of Standards

Technical Note 422, U.S. Government Printing Office,

Wasington, D. C. 20402 (Jan. 1968).

[4] Scribner, B. F., Editor, "Spectrochemical Analysis

Section: Summary of Activities July 1967 to June

1968," U.S. National Bureau of Standards Technical

Note 542, U.S. Government Printing Office, Washington, D. C. 20402 (Sept. 1968).

[5] Scribner, B. F., Editor, "Activities of the NBS Spectrochemical Analysis Section, July 1968 to June

1969," U.S. National Bureau of Standards Technical

Note 502, U.S. Government Printing Office, Washington,

D. C. 20402 (Dec. 1969).

[6] Scribner, B. F., Editor, "Activities of the NBS Spectrochemical Analysis Section, July 1969 to June

1970," U.S. National Bureau of Standards Technical

Note 542, U.S. Government Printing Office (Nov. 1970).

[7] Andersen, C. A., Hinthorne, J. R., and Fredriksson, K.,

Proceedings of the Apollo 11 Lunar Science Conference,

Geochim. and Cosmochim. Acta Suppl . 1, p. 159 (1970).

[8] Standard Reference Materials, NBS Certificates of

Analysis 48l and 482 (1969).

[9] Heinrich, K. F. J., Myklebust, R. L., Rasberry, S. D.,

and Michaelis, R. E., U.S. National Bureau of

Standards Special Publication 260-28, U.S. Government

Printing Office, Washington, D. C. 20402 (1971).
[10] Mesner, D. and Cameron, J. M., unpublished (1959).

[11] Yamamoto, S., Anal. Chem. 4_1, 337 (1969).

[12] Alley, B. J. and Myers, R. H. , Anal. Chem. 37_, 1685

(1965) •

[13] Lucas-Tooth, H. J. and Pyne, C., Advances In X-Ray

Analysis 7_, 523, Plenum Press, New York (1964).

[14] Crlss, J. W. and Birks, L. S., Anal. Chem. 4_0_, 1080

(1968).

[15] Heinrich, K. F. J., Fiori, C. E., and Yakowitz, H.

Science l67_, 1129 (1970).

[16] Z&hringer, J., Primordial Helium Detection by Microprobe Technique, Earth Planet. Sci . Lett. 1, 20-22

(1966).

[17] Kirstin, T., Steinbaunn, F., and ZShringer, J., Study

of Distribution and Variations of Rare Gases in

Lunar Material by a Microprobe Technique, Proceedings

of the Apollo 11 Lunar Science Conference, Geochim.

and Cosmochim. Acta 2, 1331-1343 (1970).

[18] Nixon, W. C. and Buchanan, R., in X-Ray Optics and

X-Ray Microanalysis, Pattee, H. H., Cosslett, V. E.,

and Engstro'm, A., Editors, p. 441, Academic Press,

New York (1963)

.

[19] Duncumb, P., in The Electron Microprobe, McKinley, T. D.,

Heinrich, K. F. J., and Wittry, D. B., Editors,

p. 490, J. Wiley and Sons, New York (1964).

[20] Conty, C, Rouberol, J. M., and Tong, M. , in X-Ray

Optics and Microanalysis, Mttllenstedt, C. and

Gaukler, K. H., Editors, p. 282, Springer-Verlag,

Berlin (1969) •

[21] Fontijn, L. A., Bok, A. B., and Kornet , J. G., in

Proceedings Vth International Congress on X-Ray

Optics and Microanalysis, Mftllenstedt , G. and

Gaukler, K. H., Editors, p. 26l, Springer-Verlag,

Berlin (1969).

[22] Hall, T., in U.S. National Bureau of Standards Special

Publication 298, p. 274, U.S. Government Printing

Office, Washington, D. C. 20402 (1968).

[23] Hall, C. E., Introduction to Electron Microscopy, p. 258,

McGraw-Hill, New York (1966).

83
[24] Michaelis, R. E., Yakowitz, H., and Moore, G. A., U.S.

National Bureau of Standards Special Publication

260-3, U. S. Government Printing Office, Washington,

D. C. 20402 (1964).

[25] Yakowitz, H., Vieth, D. L . , Heinrich, K. P. J., and

Michaelis, R. E., U.S. National Bureau of Standards

Special Publication 260-10, U.S. Government Printing

Office, Washington, D. C. 20402 (1965).

[26] Natrella, M. G., Experimental Statistics, U.S. National

Bureau of Standards Handbook 91, U.S. Government

Printing Office, Washington, D. C. 20402 (1963).

[27] Thomas, P. M. , Report 4593, Atomic Energy Research

Establishment, U.K.A.E.A., United Kingdom (1964).

[28] Bethe, H. A., Annalen der Physik 5, 325 (1930).

[29] Berger, M. J. and Seltzer, S. R. , National Academy

of Science, National Research Council Publication

1133 , 205 (1964).

[30] Duncumb, P. and Reed, S. J. B., in U.S. National

Bureau of Standards Special Publication 298, p. 133,

U.S. Government Printing Office, Washington, D. C.

20402 (1968).

[31] Heinrich, K. F. J., U.S. National Bureau of Standards

Technical Note 521, p. 6, U.S. Government Printing

Office, Washington, D. C. 20402 (1970).

[32] Philibert, J., in X-ray Optics and X-ray Microanalysis,

Pattee, H. H. , Cosslett, V. E., and Engstrflm, A.,

Editors, p. 379, Academic Press, New York (1963).

[33] Duncumb, P. and Shields, P. K., The Electron Microprobe,

p. 284, McKinley, T. D., Heinrich, K. F. J., and

Wittry, D. B., Editors, J. Wiley and Sons, New York

(1964) .

[34] Reed, S. J. B. , Brit. J. Appl. Phys. 16_, 913 (1965).

[35] Criss, J. W. and Birks, L. S. , The Electron Microprobe,

p. 217, McKinley, T. D., Heinrich, K. F. J., and

Wittry, D. B., J. Wiley and Sons, New York (1964).

[36] Rhines, J. N., Phase Diagrams in Metallurgy, McGrawHill, New York (1956).

84
[37] Barrett, C. S., Structure of Metals, Third Edition,

McGraw-Hill, New York (1966).

[38] Waterstrat, R. M. and Manuszewski, R. C., Private

communication

.

[39] Heinrich, K. P. J., in X-Ray and Electron Probe

Analysis, ASTM Special Technical Publication 349,

p. 163, ASTM, 1915 Race St., Philadelphia, Pennsylvania 19103 (1963).

Alvarez, R. , Paulsen, P. J., and Kelleher, D. E.,

Anal. Chem. 4l_, 955 (1969).

Paulsen, P. J., Alvarez, R., and Kelleher, D. E.,

Spectrochim. Acta 24B , 535 (1969).

Paulsen, P. J., Alvarez, R. , and Mueller, C. W.,

Anal. Chem. 42_, 673 (1970).

Kenworthy, A. L. , Amer. Inst, of Biological Sciences

Publ. No. 8 (1961).

Bowen, H. J. M. , Analyst 92., 124 (1967).

Bethge, P. 0., Anal. Chim. Acta 10, 317-320 (1954).

[40]

[41]

[42]

[43]

[44]

[45]

85
APPENDIX A

CERTIFICATES FOR NBS STANDARD REFERENCE

MATERIALS RECENTLY ISSUED

86
U. S. Depa; Mauric (Utttxixtntt of (Attaints

Standard Reference Material 1261

AISI 4340 Steel

This standard is in the form of disks 31 mm (1 1/4 in) in diameter and 19 mm (3/4 in) thick,

generally for use in optical emission and x-ray spectrometric analysis.3

Element Percent, by weight

Carbon 0.382 Manganese 66

Phosphorus 015

Sulfur 017

Silicon 223

Copper 042

Nickel 1.99 Chromium 0.69 Vanadium 011

Molybdenum 19

Cobalt Titanium

Arsenic Tin

Aluminum (total)

Niobium

Zirconium

Antimony

Cerium

a This material also is available SRM1095, 6.4 mm (1/4 in) i vacuum fusion and neutroq^acti 51 mm (2 in) long for source mass spectroi

SRM 361, for use in chemical methods of analysis; rods, 102 mm (4 in) long for the determination of gases in metals by

ethods of analysis; and rods, SRM 661, 3.2 mm (1/8 in) in diameter and

ochemical methods of analysis such as electron probe microanalysis, spark

laser probe analysis. PROVISIONAL CEr^IFICATION: The value listed for a certified element is the present best estimate of the true value based on the results of the cooperative analytical program. The value

listed is not expected to deviate from the true value by more than ± 1 in the last significant figure

reported; for a subscript figure, the deviation is not expected to be more than ± 5. Based on the

results of homogeneity testing, maximum variations within and among samples are estimated less than the accuracy figures given above. The overall direction and coordination of the technical measurements at NBS leading to certifi- cation were performed under the direction of 0. Menis, B. F. Scribner, J.I. Shultz, and J. L. Weber, Jr.

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 R. E. Michaelis.

Washington, D.C. 20234

July 26, 1970

J. Paul Cali, Acting Chief

Office of Standard Reference Materials

'over)

87
PLANNING, PREPARATION, TESTING, ANALYSIS: This standard is one of five replacements

for the original eight 1100 series iron and steel SRMs. Material from the same melt is available in a variety of forms to serve in checking methods of analysis and in calibrating instrumental techniques.

The material for this standard was vacuum melted and cast at the Carpenter Technology Corporation, Reading, Pennsylvania, under a contract with the National Bureau of Standards. The contract was made possible by a grant from the American Iron and Steel Institute.

The ingots were processed by Carpenter Technology Corporation to provide material of the

highest possible homogeneity. Following acceptance of the composition based on NBS analyses, selected portions of the ingot material were extensively tested for homogeneity at NBS by D. M.

Bouchette, S. D. Rasberry, and J. L. Weber, Jr. Only that material meeting a critical evaluation was

processed to the final sizes.

Chemical analyses for certification generally were made on composite samples representative of

each final shape and size; for certain elements, however, and based on previous experience, only one

composite sample was analyzed with the results applied to the other forms of the material.

Cooperative analyses for certification were performed in the analytical laboratories of Bethlehem

Steel Corporation, Sparrows Point Plant, Maryland, R. H. Rouse; Carpenter Technology Corporation, Research and Development Center, Reading, Pennsylvania, E. J. Cramer; The Timken Roller

Bearing Company, Steel & Tube Division, Canton, Ohio, R. G. Cover; United States Steel Corporation, Applied Research Laboratory, Monroeville, Pennsylvania, L. Melnick, and Gary Steel Works,

Gary, Indiana, E. H. Shipley.

Analyses were performed in the Analytical Chemistry Division of the National Bureau of Standards by the following: R. Alvarez, J. R. Baldwin, D. A. Becker, E. L. Garner, T. E. Gills, E. J. Maienthal, C. W. Mueller, P. J. Paulsen, K. M. Sappenfield, B. A. Thompson, S. A. Wicks, and

J- Wing.

88
ADDITIONAL INFORMATION ON THE COMPOSITION: Provisional certification

is made only for the elements indicated. The five replacements.

however, contain a graded series for 40 elements and information

on the elements not initially certified mav be of imoortance in

the use of the material. Although these are not certified , values are presented in the following table for the remaining

elements. (Some may be certified at a later date.)

Value from a single laboratory

Element Percent, by weight

Tungsten

Tantalum

Lead

Bismuth

Silver

Selenium

Tellurium

Lanthanum

Neodymium

Nitrogen

Iron (by difference)

Approximate value from heat analysis

Boron

Calcium

Magnesium

Zinc

Praseodymium

Germanium

Oxygen

Hydrogen

Gold

Hafnium

(0.011)

( .021)

(<.ooni)

( .0004)

( .0004)

( .004)

( .0006)

( .0004)

( .0003)

( .0037)

95.6)

(0.0005)

( .0001)

( .0002)

( .0005)

( .0002)

( .006)

( .001)

(<.0005)

(<. 00005)

( .0002)

89
U. S. Department? of Commerce

MauricqiB. Stans

(dttixixtntt of (Analg0t0

Standard Reference Material 1262

AISI 94B17 Steel (Modified)

This standard is in the form of disks 31 mm (1 1/4 in) in diameter and 19 mm (3/4 in) thick,

generally for use in optical emission and x-ray spectrometric analysis.3

Element Percent, by weight

Carbon 0.16 Manganese ". 1.04 Phosphorus 0.042

Sulfur 038

Silicon 39

Copper 50

Nickel 59

Chromium 30

Vanadium yP^i

Molybdenum N. . Y16 a

Cobalt •'^^v 1> • ^30

Antimony ^^1^7^.. . .012

^his material also is available in the form of chips, SRM SKJTforYse Vfcgtlfcmical methods of analysis; rods, SRM 1096, 6.4 mm

(1/4 in) in diameter and 102 mm (4 in) long for the i&erkttngHpnVrf gases in metals by vacuum fusion and neutron activation methods of analysis', and rods, SRM 662, 3.2 mmff/ffw in dmnefer and 51 mm (2 in) long for application in microchemical methods of analysis such as electron probejnjcrooialyaft. 9ggtK source mass spectrometric analysis, and laser probe analysis. PROVISIONAL CERTIFICA^foN\ TM value listed for a certified element is the present best estimate of the true v^SsbSwedo/i the results of the cooperative analytical program. The value

listed is not expec±^ff\fccvd«5«u^rrom the true value by more than ± 1 in the last significant figure

reported; for a suDsenpr&gure, the deviation is not expected to be more than ± 5. Based on the

results of homogeneWjr testing, maximum variations within and among samples are estimated less than the accuracy figures given above. The overall direction and coordination of the technical measurements at NBS leading to

certification were performed under the direction of 0. Menis, B. F. Scribner, J. I. Shultz, and J. L. Weber, Jr. 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 R. E. Michaelis.

Washington, D. C. 20234 J. Paul Cali, Acting Chief

July 27, 1970 Office of Standard Reference Materials

90
PLANNING, PREPARATION, TESTING, ANALYSIS: This standard is one of five replacements

for the original eight 1100 series iron and steel SRMs. Material from the same melt is available in a

variety of forms to serve in checking methods of analysis and in calibrating instrumental techniques.

The material for this standard was vacuum melted and cast at the Carpenter Technology

Corporation, Reading, Pennsylvania, under a contract with the National Bureau of Standards. The

contract was made possible by a grant from the American Iron and Steel Institute. The ingots were processed by Carpenter Technology Corporation to provide material of the

highest possible homogeneity. Following acceptance of the composition based on NBS analyses, selected portions of the ingot material were extensively tested for homogeneity at NBS by D. M.

Bouchette, S. D. Rasberry, and J. L. Weber, Jr. Only that material meeting a critical evaluation was

processed to the final sizes. Chemical analyses for certification generally were made on composite samples representative

of each final shape and size; for certain elements, however, and based on previous experience, only one composite sample was analyzed with the results applied to the other forms of the material. Cooperative analyses for certification were performed in the analytical laboratories of Al- legheny Ludlum Steel Corporation Research Center, Brackenridge, Pennsylvania, R. B. Fricioni; Inland Steel Company, East Chicago, Indiana, R. W. Bley and J. E. Joyce; Republic Steel Corporation, Canton, Ohio, R. W. Jones; and The Youngstown Sheet and Tube Company, Youngstown,

Ohio, L. E. Chalker.

Analyses were performed in the Analytical Chemistry Division of the National Bureau of

Standards by the following: J. R. Baldwin, R. K. Bell, R. W. Burke, T. E. Gills, L. T. McClendon,

B. A. Thompson, and S. A. Wicks.

91
ADDITIONAL INFORMATION ON THE COMPOSITION: Provisional certification is made only

for the elements indicated. The five replacements, however, contain a graded series for 40 elements

and information on the elements not initially certified may be of importance in the use of the

material. Although these are not certified , values are presented in the following table for the

remaining elements. (Some may be certified at a later date)

Value from a single laboratory

Element Percent, by weight

Titanium (0.083)

Arsenic ( .094)

Tin ( .016)

Aluminum (soluble) ( .086)

Boron ( .0025)

Lanthanum ( .0004)

Nitrogen ( .0041)

Oxygen ( .001)

Gold (<00006)

Iron (by difference) (95.3)

Approximate value from heat analysis

Tungsten (0.20)

Niobium ( .28)

Tantalum ( .20)

Lead ( .0006)

Zirconium ( .21)

Bismuth ( .006)

Silver ( .0009)

Calcium ( .0003)

Magnesium ( .0007)

Selenium ( .001)

Tellurium ( .001)

Zinc ( .001)

Cerium ( .002)

Praseodymium ( .0003)

Neodymium ( .0005)

Germanium ( .002)

Hydrogen (<0005

Hafnium ( .006)

92
U. S. Department'* of Commerce

MauriceiJj. Stans

(fterttfttate of (Attaint*

Standard Reference Material 1263

Cr-V Steel (Modified)

This standard is in the form of disks 31 mm (1 1/4 in) in diameter and 19 mm (3/4 in) thick,

generally for use in optical emission and x-ray spectrometric analysis. 3

Element Percent, by weight

Carbon 0.62 Manganese 1.50 Phosphorus 0.029 Sulfur 008

Silicon 74

Copper 098 Nickel .32 Chromium 1.31 Vanadium "^-31 Molybdenum .h^. \Q3J

Cobalt '

!V?^VW- • 048 Antimony ^t^^TT?'^. . . . .001 6

a This material also is available in the form of chips i?KM JwJ/vjiyjfce in chemical methods of analysis; and will be

available in the form of rods, SRM 1097, 6.4j.m«i (Jyfcfcm) irtydiameter and 102 mm (4 in) long for the determination of gases in metals by vacuum fusion anal neNnronaopvation methods of analysis; and rods, SRM 663, 3.2 mm

(1/8 in) in diameter and 51 mm (2 inVI^Rg fnr apWJjcSSon in microchemical methods of analysis such as electron probe microanalysis, spark source

/j^B»ipec^ihietnc analysis, and laser probe analysis. PROVISIONAL CMLT^pQAKrQ^: The value listed for a certified element is the present best estimate of the trfuQ^tuTmiSed on the results of the cooperative analytical program. The value

listed is not expectexKto deviate from the true value by more than ± 1 in the last significant figure

reported; for a subscript figure, the deviation is not expected to be more than ± 5. Based on the

results of homogeneity testing, maximum variations within and among samples are estimated less than the accuracy figures given above.

The overall direction and coordination of the technical measurements at NBS leading to the

certification were performed under the direction of 0. Menis, B. F. Scribner, J. I. Shultz, and J. L. Weber, Jr.

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 R. E. Michaelis.

Washington, D. C. 20234 J. Paul Cali, Acting Chief

October 2, 1970 Office of Standard Reference Materials

(over)

93
PLANNING, PREPARATION, TESTING, ANALYSIS: This standard is one of five replacements

for the original eight 1100 series iron and steel SRMs. Material from the same melt is available in a variety of forms to serve in checking methods of analysis and in calibrating instrumental techniques.

The material for this standard was vacuum melted and cast at the Carpenter Technology Corporation, Reading, Pennsylvania, under a contract with the National Bureau of Standards. The contract was made possible by a grant from the American Iron and Steel Institute.

The ingots were processed by Carpenter Technology Corporation to provide material of the

highest possible homogeneity. Following acceptance of the composition based on NBS analyses, selected portions of the ingot material were extensively tested for homogeneity at NBS by D. M.

Bouchette, S. D. Rasberry, and J. L. Weber, Jr. Only that material meeting a critical evaluation was

processed to the final sizes.

Chemical analyses for certification generally were made on composite samples representative of

each final shape and size; for certain elements, however, and based on previous experience, only one

composite sample was analyzed with the results applied to the other forms of the material.

Cooperative analyses for certification were performed in the analytical laboratories of Climax

Molybdenum Company of Michigan, Ann Arbor, Michigan, J. W. Mann and H. E. Trapp; MidvaleHeppenstall Co., Nicetown, Philadelphia, Pennsylvania, W. L. MacBride; Standard Steel Co., Burn- ham, Pennsylvania, J. Metzgar; and The Steel Company of Canada, Hamilton, Ontario, Canada,

0. P. Bhargava.

Analyses were performed in the Analytical Chemistry Division of the National Bureau of Standards by the following: R. K. Bell, R. W. Burke, T. E. Gills, E. J. Maienthal, L. T. McClendon, T. C. Rains, T. A. Rush, B. A. Thompson, and S. A. Wicks.

94
ADDITIONAL INFORMATION ON THE COMPOSITION: Provisional certification is made only

for the elements indicated. The five replacements, however, contain a graded series for 40 elements

and information on the elements not initially certified may be of importance in the use of the

material. Although these are not certified , values are presented in the following table for the

remaining elements. (Some may be certified at a later date.)

Value from a single laboratory

Element Percent, by weight

Tungsten (0.050)

Arsenic ( .010)

Lead ( .0016)

Bismuth ( .0008)

Silver ( .0038)

Calcium. (C0001)

Magnesium ( .0005)

Tellurium ( .0022)

Zinc . ( .0004)

Lanthanum ( .0006)

Gold ( .0005)

Iron (by difference) (94.4)

Approximate value from heat analysis

Titanium

Tin

Aluminum

Niobium

Tantalum

Boron

Zirconium

Selenium

Cerium

Praseodymium.

Nitrogen ( .0042)

Germanium ( .010)

Oxygen ( .0006)

Hydrogen. (C0005)

Hafnium ( .0015)

0.06)

.094)

.25)

.049)

.04)

.0010)

.048)

.0001)

.002)

.0005)

95
U. S. Department of Commerce Mauricejg. Stans PgSBH

Certificate of (Analgsb

Standard Reference Material 1264

High-Carbon Steel (Modified)

This standard is in the form of disks 31 mm (1 1/4 in) in diameter and 19 mm (3/4 in) thick,

generally for use in optical emission and x-ray spectrometric analysis."

Element Percent, by weight

Carbon 0.87 Manganese 255 Phosphorus 018 Sulfur 029 Silicon 065

Copper 249 Nickel 139 Chromium 063 Vanadium 10s Molybdenum

Cobalt Lead ./s. ,vv.u. .«j. 9

a Thie material also will be available in the form of chips, SRI

(1/4 in) in diameter and 102 mm (4 in) long for the M

methods of analysis; and rods, SRM 664, 3.2 mm V

methods of analysis such as electron probe micjpanal

emical methods of analysis; rods, SRM 1098, 6.4 mm

' gases in metals by vacuum fusion and neutron activation

' and 51 mm (2 in) long for application in microchemical

: mass spectrometric analysis, and laser probe analysis. PROVISIONAL CERTinCAMONVjTfib! value listed for a certified element is the present best estimate of the true vaKfe^aredoJ* the results of the analytical program. The value listed is not expected to deviate^r^m^fe^tpJevalue by more than ± 1 in the last significant figure reported; for a subscript figure, Xtfe deviation is not expected to be more than ± 5. Based on the results of homogeneity testing,^»aximum variations within and among samples are estimated less than the accuracy figures given above.

The overall direction and coordination of the technical measurements at NBS leading to the

certification were performed under the direction of O. Menis, B. F. Scribner, J. I. Shultz, and J. L. Weber, Jr.

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 R. E. Michaelis.

Washington, D. C. 20234

January 20, 1971

J. Paul Cab, Acting Chief

Office of Standard Reference Materials

96
PLANNING, PREPARATION, TESTING, ANALYSIS: This standard is one of five replacements

for the original eight 1100 series iron and steel SRMs. Material from the same melt is available in a variety of forms to serve in checking methods of analysis and in calibrating instrumental techniques.

The material for this standard was vacuum melted and cast at the Carpenter Technology Corporation, Reading, Pennsylvania, under a contract with the National Bureau of Standards. The contract was made possible by a grant from the American Iron and Steel Institute.

The ingots were processed by Carpenter Technology Corporation to provide material of the

highest possible homogeneity. Following acceptance of the composition based on NBS analyses, selected portions of the ingot material were extensively tested for homogeneity at NBS by D. M.

Bouchette, S. D. Rasberry, and J. L. Weber, Jr. Only that material meeting a critical evaluation was

processed to the final sizes.

Chemical analyses for certification generally were made on composite samples representative of

each final shape and size; for certain elements, however, and based on previous experience, only one

composite sample was analyzed with the results applied to the other forms of the material.

Analyses were performed in the Analytical Chemistry Division of the National Bureau of Standards by the following: R. K. Bell, T. E. Gills, E. J. Maienthal, S. D. Rasberry, B. A. Thompson, and

S. A. Wicks.

CAUTION: This standard has been found generally satisfactory for application in x-ray spec- trometric analysis with the analytical points fitting on curves established by use of the 1100 Series. However, in preliminary application testing for optical emission spectrometric analysis with conventional air-spark excitation, some biases were observed relative to curves from the 1100 series —

particularly for the carbide-forming elements. This may be due to metallurgical structure differences

in this standard (more carbides) or composition interferences (higher carbon, molybdenum, and

titanium). In any event the user is cautioned in application of this standard to test its comparability

with other available SRMs.

97
ADDITIONAL INFORMATION ON THE COMPOSITION: Provisional

certification is made only for the elements indicated. The

five replacements, however, contain a graded series for 40

elements and information on the elements not initially

certified may be of importance in the use of the material.

Although these are not certified , values are presented in the

following table for the remaining elements. (Some may be

certified at a later date.)

Value from a single laboratory

Element Percent, by weight

Tungsten

Titanium

Arsenic

Niobium

Tantalum

Zirconium

Lanthanum

Gold

Iron (by difference)

0.10)

.24)

.057)

.157)

.11)

.070)

.00007)

.00007)

(96.7)

Approximate value from heat analysis

Tin

Aluminum

Boron

Antimony

Bismuth

Silver

Calcium

Magnesium

Selenium

Tellurium

Zinc

Cerium

Praseodymium

Nitrogen

Germanium

Oxygen

Hydrogen

Hafnium

Neodymium

0.005)

.014)

.014)

.025)

.002)

.00005)

.00005)

.00005)

.0003)

.0002)

.0005)

.0005)

.0001)

.003)

.003)

.0017)

<.0005)

.005)

.0002)

98
U. S. Department? of Commerce

MauriceiJi. Stans

Rational ^mmn of js»iatularcte

(Eerttfttate of JVttal^t*

Standard Reference Material 1265

Electrolytic Iron

This standard is in the form of disks 32 mm (1 1/4 in) in diameter and 19 mm (3/4 in) thick,

generally for use in optical emission and x-ray spectrometric analysis. 3

Element Percent, by weight

Carbon 0.0067

Manganese .0057

Phosphorus 002s Sulfur 0059

Silicon 008

Copper 0058

Nickel 041

Chromium .0072 Vanadium 0006

Molybdenum 0050

Cobalt 007

Titanium 0006

Arsenic (.0002)b Aluminum (Total) (.0007)

Boron 00013

Lead 00002

Iron (by difference) 99.9

a This material also is available in the form of chips, SRM 365, for use in chemical methods of analysis; rods, SRM 1099, 6.4 mm

(1/4 in) in diameter and 102 mm (4 in) long for the determination of gases in metals by vacuum fusion and neutron activation methods of analyses; and rods, SRM 665, 3.2 mm (1/8 in) in diameter and 51 mm (2 in) long for application in microchemical methods of analysis such as electron probe microanalysis, spark source mass spectrometric analysis, and laser probe analysis. "Values in parenthesis are not certified since they are based on the results from a single laboratory.

CERTIFICATION: The value listed for a certified element is the best estimate of the true value based on the results of the cooperative analytical program. The value listed is not expected to

deviate from the true value by more than ±1 in the last significant figure reported; for a subscript

figure, the deviation is not expected to be more than ±5. Based on the results of homogeneity

testing, maximum variations within and among samples are estimated to be less than the accuracy

figures given above.

Washington, D. C. 20234 J. Paul Cali, Chief

August 6, 1971 Office of Standard Reference Materials

(over)

99
PLANNING, PREPARATION, TESTING, ANALYSIS: This standard is one of five replacements

for the original eight 1100 series iron and steel SRM's. Material from the same melt is available in a variety of forms to serve in checking methods of analysis and in calibrating instrumental techniques.

The material for this standard was vacuum melted and cast at the Carpenter Technology

Corporation, Reading, Pennsylvania, under a contract with the National Bureau of Standards. The

contract was made possible by a grant from the American Iron and Steel Institute.

The ingots were processed by Carpenter Technology Corporation to provide material of the

highest possible homogeneity. Following acceptance of the composition based on NBS analyses,

selected portions of the ingot material were extensively tested for homogeneity at NBS by J. R. Baldwin, D. M. Bouchette, S. D. Rasberry, and J. L. Weber, Jr. Only that material meeting a critical evaluation was processed to the final sizes.

Chemical analyses for certification were made on composite samples representative of the

accepted lot of material.

Cooperative analyses for certification were performed in the Research Laboratories of Armco

Steel Corporation by R. L. LeRoy and J. F. Woodruff.

Analyses were performed in the Analytical Chemistry Division of the National Bureau of Standards by the following: R. Alvarez, J. R. Baldwin, E. Belkas, B. S. Carpenter, M. M. Darr, E. R.

Deardorff, E. L. Garner, T. E. Gills, L. A. Machlan, E. J. Maienthal, L. J. Moore, C. W. Mueller, T. J. Murphy, P. J. Paulsen, K. M. Sappenfield, B. A. Thompson, and S. A. Wicks.

The overall direction and coordination of the technical measurements at NBS leading to certifi- cation were performed under the direction of O. Menis, B. F. Scribner, J. I. Shultz, and J. L. Weber, Jr.

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 R. E. Michaelis.

100
ADDITIONAL INFORMATION ON THE COMPOSITION: Certification is made only for the

elements indicated. The five replacements, however, contain a graded series for 40 elements and

information on the elements not initially certified may be of importance in the use of the material.

Although these are not certified, upper limit values are presented in the following table for the

remaining elements. (Some may be certified at a later c

Elements Detected (ppm by weight)

Element

Upper (Estimated

Limit value)

W

Sn

Nb

Ag

Zn

< 1 ( 0.4 ) < 5 ( 2 ) < 0.5 (<0.1 ) < 0.2 ( 0.02)

< 3 ( 2 ) N

Ge

H

<20 (^11 ) <50 (^14 ) <70 ( 63 ) < 5 ( 1 )

Elements Sought But Not Detected (ppm by weight)

Element

Upper

Limit

Ta

ZrSb

Bi

Ca

<0.5

<0.1

<0.5

<0.1

<0.1

Mg

Se

Te

Ce

La

<0.2

<0.1

<0.1

<0.05

<0.05

PrAu

Hf

Nd

<0.05

<0.02

<0.2

<0.05

Method

Neutron activation

Spark source mass spectrometry

Spark source mass spectrometry

Spark source mass spectrometry

Spark source mass spectrometry

Distillation- photometric

Spark source mass spectrometry

Vacuum fusion

Vacuum fusion

Method

Neutron activation

Spark source mass spectrometry

Neutron activation

Spark source mass spectrometry

Atomic absorption

Atomic absorption

Spark source mass spectrometry

Spark source mass spectrometry

Spark source mass spectrometry

Spark source mass spectrometry

Spark source mass spectrometry

Neutron activation

Spark source mass spectrometry

Spark source mass spectrometry

101
U. S. Department' of Commerce

MauriceiH. Stans

(Eerttfttate of (Attaint*

Standard Reference Material 483

Fe-3Si Alloy Microprobe Standard

This standard is characterized for chemical homogeneity of iron and silicon at the micrometer

level of spatial resolution and is satisfactory for use as a homogeneous material for electron probe

microanalysis.

Silicon Iron (by difference)

SRM Weight, percent

483 3.22b ± 0.02c 96.7 - 96.8

a

Size: 3 mm X 3 mm X 0.28 mm thick. The material is from coarse-grained sheet stock having the so-called Goss orientation in which a [110] grain is parallel to the surface and [001 ] is the rolling direction. Each sample is supplied HF etched and ready for metallographic mounting and polishing. "Determination of silicon involved 49 samples of SRM 483. SRM 125b, certified at 2.89 wt. % Si, was used as a control standard and

2.90 wt % Si was found. Method: One gram samples were dissolved in hydrochloric and nitric acids. A double dehydration of the silicon with perchloric acid was made with an intervening filtration. The weight of silicon present was determined from the loss resulting from treatment with

hydrofluoric acid. Analyst — R. A. Paulson, NBS Analytical Chemistry Division.

c Standard deviation of a single determination based on results obtained on SRM's 483 and 125b, but also including similar method

error estimations from previous determinations.

HOMOGENEITY TESTING AND QUANTITATIVE ANALYSIS BY

ELECTRON PROBE MICROANALYSIS

Homogeneity was checked by means of quantitative raster scanning in which a square matrix

(1.1 mm X 1.1 mm) of individual points is analyzed by the microprobe. Each matrix represents 400

separate analyses. Six selected matrices were run for iron and silicon with three of these rerun. The

coefficient of variation for both the iron and silicon is less than one percent. Analysts — H. Yakowitz, NBS Metallurgy Division, and C. E. Fiori, NBS Analytical Chemistry Division.

Quantitative microprobe analysis of this alloy gave a silicon content of 3.14 wt. % and an iron

content of 96.9%. Analyst — H. Yakowitz, NBS Metallurgy Division.

Details of the microprobe testing and analyses, as well as the sample preparation, are given in NBS Special Publication 260-22, Standard Reference Materials: Homogeneity Characterization of

Fe-3Si Alloy, H. Yakowitz, C. E. Fiori, and R. E. Michaelis, Feb. 1971.

The technical and support aspects involved in the preparation, certification, and issuance of this standard were coordinated through the Office of Standard Reference Materials by R. E. Michaelis.

Washington, D. C. 20234 J. Paul Cali, Chief

June 11, 1971 Office of Standard Reference Materials

102
U. S. Departri^n*f of Commerce Maurice:jt, Stana

National Bureau wfl Standards

L. M. BrartsetfBtto\ Director

(Utrtxixttdt

Standard Reference Material 485

Austenite in Ferrite

This standard is provided for the calibration of x-ray diffraction equipment used in determining

the amount of retained austenite in ferrous materials. X-ray diffraction procedures require accurate measurements of integrated intensity for a number of selected peaks; however, as the amount of retained austenite decreases, the accuracy of these measurements deteriorates. This nominally four

percent austenite standard should serve the calibration needs at the low levAls.

SRM No. Description "\^-^ U

Austenite, percent

485 4(Nominal) b

mn)J(l$fl6 in) in diameter by 2.5 mm (0.10 in) thick, ppow^e «ce is labeled with the determined austenite content to the evedaccurate to ± 0.2 percent . CAUTION: Damage to the certified

a The austenite standard is available in disk fo "Only one face on each disk is certifi nearest 0.1 percent. The certifieit^vikrs is" face renders the certificatioiLof (bat diaft vol

The preparation^! sWcimens, and the technical measurements leading to certification, were

directed and coordinated r>y G. E. Hicho.

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 R. E. Michaelis.

Washington, D. C. 20234

July 30, 1970

J. Paul Cab, Acting Chief

Office of Standard Reference Materials

(over)

103
SUPPLEMENTARY INFORMATION

The austenite content of this standard is directly related to the nickel content as a result of

blending austenitic stainless steel powder (20.4% Ni) with ferritic stainless steel powder (<0.1% Ni).

Therefore, accurate and rapid x-ray fluorescence analysis could be used for the determination of the

nickel content, and hence the austenite content, of each sintered and pressed compact.

An x-ray fluorescence analytical curve relating Ni Ka count rate to austenite content was established using five specially prepared compacts which were characterized by the following two

methods:

1. Quantitative Television Microscopy: Eighty fields were observed on each of the five compacts

containing 5, 10, 15, 20, and 25 percent austenite, respectively. Observation covered three different time intervals. (D. E. Harne and G. E. Hicho)

2. Electro-Mechanical Drum Scanner: Five fields were observed on each compact: the center, and four mid-points of the center and the radius at 45 degrees with the horizontal and vertical. (D. E. Harne, G. E. Hicho, and G. A. Moore)

The x-ray fluorescence curve established through the use of the compacts characterized by the above methods was found valid to within ± 0.2 percent of austenite. The certified value for each

disk of SRM 485 is based on the results of three determinations of the Ni Ker count rate converted

to austenite content. (S. D. Rasberry and H. Yakowitz)

This standard has been established to provide a means for calibrating x-ray diffraction equip- ment. The SRM 485, in special cases, may be used as an x-ray fluorescence standard for determining

the nickel content in nickel-iron or nickel-chromium-iron composites.

The powder for SRM 485 was prepared at the Federal Mogul Corporation, Detroit, Michigan,

and the compacts were prepared at SKC/PM Engineering of Hawthorne, New Jersey.

104
U. S. Department of Commerce

Maurice >M. Stans SecxatarV

National BireaG 9f) Standards

L. M. Brari-5«Dt*. Director Certtfttate of (Attalgstg

Standard Reference Materials

1206-2, 1207-1, 1207-2, 1208-1, 1208-2

High-Temperature Alloys: Rene 41, Waspaloy, and Inco 718

These standards are in the form of solid sections primarily for application in x-ray spectrometric

analysis although they also may be useful in optical emission spectrometric analysis.

Rene' 41 Waspaloy Inco 718

1206-2 1207-1 1207-2 1208-1 1208-2

Carbon 0.21 7 Manganese

Phosphorus

Sulfur

.030

(.004) .006

Silicon •21 6 Copper

Nickel .040

53.3 Chromium 19.17 Molybdenum

Titanium

10.3

2.94 Aluminum 1.74 Cobalt 11.5,

Niobium

Iron 0.46 Tantalum

0.043

.34 .005 .009

.472 .026

56.1 18.88 4.50

3.09

1.26

13.0S

0.083

•29 5 .005

.009

.61 5 .033 55.7

19.44 4.34

2.54

0.046 385 .003

.01, .434 .14 7 51.9

17.5

3.24 0.46

.15) .82 5.3 8 19.2

(0.012)

0.022 23

.003 .007

.08, .077

51.5

17.4 3.13

(0.8S )

( -8 5 ) .76 4.9 8 19.8

(0.012)

aValues in parenthesis are not certified but are pre SIZE AND METALLURGIC

and 19 mm (3/4 in) thick; th^y W

CERTIFIED PO; (5/16 in) from th' portion only was a

[Information on the composition. ITKJNrSamples are approximately 31 mm (1 1/4 in) square

-cast by a rapid unidirectional solidification technique.

rtified portion for each sample is that extending upward 8 mm

or test surface (the largest surface opposite the numbered surface). This

in the cooperative program for certification. PROVISIONAL CERTIFICATION: The value listed for a certified element is the present best estimate of the true value based on the results of the cooperative analytical program. The value

listed is not expected to deviate from the true value by more than ± 1 in the last significant figure

reported; for a subscript figure, the deviation is not expected to be more than + 5. Based on the

results of homogeneity testing, maximum variations within and among samples are estimated less than the accuracy figures given above.

Note 1. The total for elements determined in SRMs 1206-2, 1207-1, and 1207-2 is 100.0 percent

±0.05; for SRMs 1208-1 and 1208-2 the total is 99.7 percent ± 0.05, suggesting the presence of one or more additional elements not yet sought nor determined. Note 2: Metallographic examination of the material from SRM 1206-1 revealed considerable porosity precluding certification at this time.

Washington, D.C. 20234

November 6, 1970

J. Paul Cali, Acting Chief

Office of Standard Reference Materials

(over)

105
PREPARATION, TESTING, ANALYSIS: The material for the standards was melted and east al the American Cast Iron Pipe Company, Birmingham, Alabama, with use of the NBS chill-cast mold

assembly. This procedure for the preparation and homogeneity testing was similar to that described

in NBS Misc. Publ. 260-1, Standard Reference Materials: Preparation of NBS White Cast Iron Spectrochemical Standards, Robert E. Michaelis and LeRoy L. Wyman, June 19, 1964.

Homogeneity testing was performed at NBS by D. M. Bouchene and was found to be satisfac- tory for the elements certified.

Cooperative analyses for certification were performed in the analytical laboratories of Cameron

Iron Works, Inc., Houston, Texas, R. A. Clarke; Carpenter Technology Corporation, Research and

Development Center, Reading, Pennsylvania, E. J. Cramer; Ladish Co., Cudahy, Wisconsin, F. J. Kohls, J. Rafalski, and J. Szmania; and Cyclops Corporation, Universal-Cyclops Specialty Steel Division, Bridgeville, Pennsylvania, R. C. Host.

Analyses were performed in the Analytical Chemistry Division of the National Bureau of Standards by R. K. Bell, and S. A. Wicks.

Technical measurements performed at NBS for certification were coordinated by J. I. Shultz and

J . L. Weber, Jr. under the chairmanship of B. F. Scribner.

The technical and support aspects involved in the preparation, certification, and issuance of

these standard reference materials were coordinated through the Office of Standard Reference

Materials by R. E. Michaelis. CAUTIONS:

1. Determinations made on other than the chill-cast or test surface are not recommended because

of the unidirectional solidification structure.

2. These chill-cast standards are designed for calibration in the analysis of samples prepared in the same manner; samples prepared by other casting techniques may result in considerable bias.

3. Because the samples exhibit some change with respect to the solidification structure, both

among standards and from bottom to top of the certified portion of the samples, the surface preparation for x-ray spectrometric analysis may be critical. (A metallographic polishing tech- nique is recommended.)

4. Because of the poor heat conductivity of the high-temperature alloys, difference in volatility rates for certain elements in emission spectrometric analysis may occur depending on the loca- tion of the burn and the source parameters.

106
U. S. Department of Commerce

Maurice H. Stans

Secretary

National B«n?a*I of Standards

L. M. Brartseomb, Director

Certificate of JVnalgsb

STANDARD REFERENCE MATERIAL 1134

High-Silicon Steel

SIZE AND METALLURGICAL CONDITION: Samples are 1 1/4 in (31.8 mm) in diameter and 3/4

in (19.1 mm) thick, and are issued in the annealed condition. This material also is available in chip

form as SRM 125b, primarily for application in chemical methods of analysis.

COHCO

>-—

1

<Z

<

C Mn P S Si Cu Ni Cr Mo Sn Al

til <o —

3 E.E IS

PeroxydisulfateArsenite

MolybdenumBluePhotometric CombustionIodate

Titration

Perchloric

Acid

Dehydration

'SE

o

JS0.

V

E

JS

0-

"SVE

J=

0-

'5VE

o

J=

a1 0.024 0.278a 0.029 0.008b 2.89c |0.072d f

) .071«(

0.039 0.016f 0.009f 0.0038 0.332h

2 .028' .276 - .028 .010 2.89c .06 7J .036

\ .019kl

j .0221 ( .008m .004" .329°

3 .025' .277P .0271 .008. 2.88 .072d

.039 .0191 .008 .003" .326 r

Average 0.026 0.277 0.028 0.009 2.89 0.070 0.038 0.019 0.008 0.003 0.329

a Potentiometric titration. 1-g sample burned in oxygen at 1450 °C and sulfur dioxide absorbed in starch-iodide solution. Iodine is liberated from iodide by titration, during the combustion, with standard KIO3 solution.

c Double dehydration with intervening filtration. Diethyldithiocarbamate spectrophotometric method.

e Isotope dilution mass spectrometric method.

Activation analysis.

g Sulfide-iodinemethod. See BS J. Res 8, 309 (1932) RP415.

Flame emission spectrometry.

1 Thermal conductivity method.

J Neocuproine spectrophotometric method.

Chromium oxidized with peroxydisulfate, titration with KMnCj.

Diphenylcarbazide spectrophotometric method. m Thiocyanate-ethyleneglycol molybdenum complex

extracted with monobutyl ether and determined spec- trophotometrically.

n Polarographic method. Aluminum precipitated as phosphate, ignited and weighed as AIPO4.

p Periodate spectrophotometric method.

" Ammonium phosphomolybdate extracted with iso- butyl alcohol reduced to molybdenum-blue, and phos- phorus determined spectrophotometrically.

Ether, mercury-cathode, cupferron, chrome-azurol-S spectrophotometric method.

Washington, D. C. 20234

April 30, 1970

J. Paul Cali, Acting Chief

Office of Standard Reference Materials

(over)

107
PLANNING, PREPARATION, TESTING, ANALYSIS: For many metal SRMs it is desirable to provide the material both in the form of chips primarily for chemical analysis and solids primarily

for optica] emission and x-ray spectrometric methods of analysis. Prior to the preparation of the renewal SRM 125b (chip form) plans were made also to provide this material as SRM 1134 (solid

form).

The material for these standards was prepared by the Armco Steel Corporation. A single ingot was pressed to a slab having one dimension of the cross section four times that of the other

dimension. After cropping top and bottom, the slab was cut lengthwise and the center section,

corresponding to about one-fourth of the original ingot, was discarded. About half of the slab section material corresponding to the top part of the original ingot was rolled to 5-in diameter

rounds and these rounds were subsequently chipped at NBS to form SRM 125b. The remaining slab sections were hot rolled to oversized rods and centerless ground to final rod size, 1 1/4 in (31.8

mm) in diameter.

Extensive homogeneity testing was performed at NBS and included metallographic studies by

R. F. Brady, optical emission spectrometric analysis by D. M. Bouchette and J. L. Weber, Jr., x-rav spectrometric analysis by S. D. Rasberry and J. McKay, and chemical analysis by J. R. Baldwin and

S. A. Wicks. The testing revealed the material to be of high homogeneity.

Chemical analyses were made on a composite chip sample for SRM 125b and on millings cut from the full cross section of the SRM 1134 material. The laboratories and analysts cooperating in the analytical program for certification are as follows:

1. J. R. Baldwin, S. A. Wicks, B. B. Bendigo, E. R. Deardorff, T. A. Rush, T. C. Rains, B. A. Thompson, T. J. Murphy, and E. L. Garner, Analytical Chemistry Division, Institute for Materials Research, National Bureau of Standards.

2. L. M. Melnick, W. R. Bandi, H. S. Karp, J. L. Lutz, R. W. Lewis, J. B. Ferons, and H. M. Lewis,

Applied Research Laboratory, United States Steel Corporation, Monroeville, Pennsylvania.

3. M. Dannis and R. L. LeRoy, Armco Steel Corporation, Middletown, Ohio.

The overall direction and coordination of the technical measurements leading to certification were performed under the chairmanships of 0. Menis and J. I. Shultz.

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 R. E. Michaelis.

108
U' S' %SSf staC

n8mmerCe THIS IS A PRELIMINARY ISSUE OF

SwasHwfr THE PRINTED CERTIFICATE WHICH

Nat^ Bp&sundard. WILL BE AVAILABLE WITHIN 60 DAYS

L. M. Brart»ecfe»tf, Director

(tterttftcate of (Analysts

Standard Reference Material 1623

Sulfur in Residual Fuel Oil

W. P. Schmidt and R. A. Paulson

Sulfur Content 0.268 ± 0.004 weight percent

This standard reference material is an analytical standard

for determining sulfur in residual fuel oil. It is a commer- cially available fuel oil having the following inspection

properties that are supplied for identification only: gravity,

27.0 °API; flash point (Pensky-Martens) , 170 °F; viscosity

(kinematic), 5.8 centistokes; pour point, 47 °F; and carbon

residue (on 10 percent bottoms), 0.31 percent. The following

analytical data are not certified, but are reported for

information only: carbon, 87.4 percent; hydrogen, 12.0 percent;

water, not detected (<0.1 percent); sediment, not detected

(<0.01 percent); ash, not detected (<0.005 percent); and

vanadium 3 ± 1 ng/g.

Sulfur was determined gravimetrically as barium sulfate

after combustion in a Parr Oxygen Bomb using 1 -g samples. The

method is similar to ASTM Method D-129. It differs only in

that any iron present is removed with ammonium hydroxide before

the precipitation of the sulfur as barium sulfate. The uncertainty

shown represents the 95-percent confidence limit of the mean

based on 12 determinations and allowances for known sources of

possible error.

The material was supplied by the Esso Research and

Engineering Company of Linden, New Jersey. Vanadium was determined by T. E. Gills, using non-destructive neutron

activation analysis.

The overall direction and coordination of the technical

measurements leading to certification were performed under the

chairmanship of J. K. Taylor.

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 T. W. Mears.

Washington, D. C. 20234 J. Paul Cali, Chief

April 7, 1971 Office of Standard Reference Materials

109
U. S. Department of Commerce

Maurice.H. Stana

National B^reat «fl Standards

L. M. Brart»e^*tf; Director

THIS IS A PRELIMINARY ISSUE OK

THE PRINTED CERTIFICATE WHICH

WILL BE AVAILABLE 'AITKIN fiO DAYS

Certificate of ^nal^i*

Standard Reference Material 1624

Sulfur in Distillate Fuel Oil

w. Schmidt and R. A. Paulson

Sulfur Content . . . . 0.211 ± 0.004 weight percent

This standard reference material is an analytical standard

for determining sulfur in distillate fuel oil. It is a commercially available oil having the following inspection

properties that are supplied for identification only: gravity,

33.8 °API; flash point (Pensky-Martens) , 138 °F; viscosity

(kinematic), 2.7 centistokes; pour point, -16 °F; carbon

residue (on 10 percent bottoms), 0.15 percent. The following

analytical data are not certified, but are reported for

information only: carbon, 86.6 percent; hydrogen, 12.5 percent;

water, not detected (<0.1 percent); sediment, not detected

(<0.01 percent); ash, not detected (<0.005 percent); vanadium,

14 ± 1 ng/g.

Sulfur was determined gravimetrically as barium sulfate

after combustion in a Parr Oxygen Bomb using 1 -g samples. The

method is similar to ASTM Method D-129. It differs only in

that any iron present is removed with ammonium hydroxide before

the precipitation of the sulfur as barium sulfate. The

uncertainty shown represents the 95 -percent confidence limit

of the mean based on 12 determinations and allowances for

known sources of possible error. The material was supplied by the Esso Research and

Engineering Company of Linden, New Jersey. Vanadium was determined by T. E. Gills, using non-destructive neutron

activation analysis.

The overall direction and coordination of the technical

measurements leading to certification were performed under the

chairmanship of J. K. Taylor.

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 T. W. Mears.

Washington, D. C. 20234

April 7, 1971

J. Paul Cali, Chief

Office of Standard Reference Materials

no
U. S. Department' of Commerce

Maurice. H. Stana Secretary

National Bureau of Standards

L. M. BrartsecmtJ, Director

Ol^rttftcat^ of (Attaint*

Standard Reference Material 654a

Titanium Alloy, 6A1-4V

This standard is in the form of disks 31 mm (1 lA in) in diameter and 6.4 mm (

lA in) thick,

primarily for application in x-ray spectrometric analysis.*

Element Percent, by weight

Al 6.34 V 3.9S

Fe . (0.20)b Cr ( .20) Mn (<.l) Mo (<.05)

a This standard also may be useful in optical emission spectrometric analysis. Bearuse Uk£*siandV^3s> thin, bonding it to a more

massive backing will permit a greater efficiency in consumption of the material. 9^ASB«1vV5wgnati°n E401-70, Recommended

Practice for Bonding Thin Spectrochemical Samples and Standards to a Greart£&}»ssjJ.Ma

"Values in parenthesis are not certified but are given as additional mforajflSJ^olvifnefomposition. PROVISIONAL CERTIFICATION: The vakfe H^te^igjJ/ a certified element is the present best estimate of the true value based on thejp^ltwiNw^riaependent methods of analysis. Deviation of

the true value by more than ± 5 in thmlasKsuhjjmpt figure is not expected. Based on the results of homogeneity testing, maximinjuviaK^tijIns v\khin and among samples are estimated to be less than

the accuracy figure given above/"

PLANNING, PREftCTyV^^PESTING, ANALYSIS: This standard was prepared, in part, to serve

in round-robin tesrvWctmrkin calibration of an ASTM method (E02 SM8-20).

The material for the standard was provided in wrought form by the Research Center, Armco

Steel Corporation, Middletown, Ohio.

Homogeneity testing and analyses for certification were performed in the Analytical Chemistry

Division of the National Bureau of Standards by S. D. Rasberry and J. L. Weber, Jr.

The technical and support aspects involved in the preparation, certification, and issuance of this standard were coordinated through the Office of Standard Reference Materials by R. E. Michaelis.

Washington, D. C. 20234

March 22, 1971

J. Paul Cali. Chief

Office of Standard Reference Materials

111
flkrfifttate of ^ttalgst*

Standard Reference Material 917

D-Glucose

3. Coxon and R. Schaffer

This standard reference material is certified as a chemical of known purity. It is intended

primarily for use in the calibration and standardization of procedures employed in clinical analysis

and for routine critical evaluation of the daily working standards used in these procedures.

Purity 99.9 percent

a-D-Glucopyranose greater than 99.0 percent

/}- D-Glucopyranose less than 1.0 percent

Moisture 0.06 percent

Ash ( 0.002 percent

Insoluble Matter 0.001 to 0.006 percent

Nitrogen less than 0.001 percent

Specific Rotation

[a] 20 = +53.2° (at equil., c 20.1 in water)

[a]|° 6 = +62.8° (at equil., c 20.1 in water)

[a] 2

, = +112.6° (initial, c 10.05 in methyl sulfoxide)

The value for the purity has an estimated inaccuracy of ±0.1 percent.

The D -glucose used for this standard reference material was obtained from Pfanstiehl Laboratories, Inc., of Waukegan, Illinois. Analyses were performed by R. F. Brady, Jr., B. Coxon, M. M.

Darr, T. E. Gills, E. C. Kuehner, R. A. Paulson, T. C. Rains, T. A. Rush, W. P. Schmidt, J. H. Thomas, and W. L. Zielinski of the Analytical Chemistry Division.

The overall direction and coordination of technical measurements leading to the certification were under the chairmanship of R. Schaffer.

The technical and support aspects concerning the preparation, certification, and issuance of this standard reference material were coordinated through the Office of Standard Reference Materials by T. W. Means.

Washington, D. C. 20234 J. Paul Cali, Acting Chief

November 18, 1970 Office of Standard Reference Materials

112
S. Department of Commerce

Maurice H. Stans

National Boreap

L. M. Brart

(tferttftcate of JVmtlgsis

Standard Reference Material 918

Potassium Chloride

(Clinical Standard)

This standard reference material is certified for use in the calibration and standardization of procedures employed in the determination of potassium and chloride ions in clinical analyses. The

sample consists of highly purified potassium chloride. Chemical assay as well as analyses for specific

impurities indicate that the material may be considered essentially pure, except for moisture due to occlusion.

Purity 99.9 ± 0.0 percent

The above value for the purity of the material is based on a sample dried over magnesium

perchlorate for 24 hours. Potassium chloride is hygroscopic when the relative humidity at room

temperature exceeds 75 percent, but ran be dried to the original weight by desiccation over freshly exposed P2O5 or Mg(C104 ) 2 for 24 hours. The material should be stored with such a desiccant. The

potassium was determined by a combination of gravimetric and isotope dilution analyses. More than 99 percent of the potassium was precipitated, filtered, and weighed as potassium perchlorate. The

weight of potassium perchlorate was corrected for rubidium perchlorate. The soluble potassium was

determined by isotope dilution mass spectrometry. Total potassium was the sum of the potassium

from the potassium perchlorate and the potassium from the filtrate. The chloride was determined

by a coulometric argentimetric procedure.

Based on 12 independent measurements for each ion, the sample was considered homogeneous.

Material dried at 500 °C for 4 hours in a platinum or Vycor crucible (Pyrex is unsatisfactory) was

assayed at 99.98 ± 0.01 percent. The loss of moisture by this procedure was about 0.07 percent.

The potassium chloride used for this standard reference material was obtained from the J. T. Baker Chemical Company, of Phillipsburg, New Jersey. Analyses were performed by G. Marinenko,

T. J. Murphy, T. C. Rains, T. A. Rush, W. P. Schmidt, and V. C. Stewart.

The overall direction and coordination of technical measurements leading to the certification were under the chairmanship of W. R. Shields.

The technical and support aspects concerning the preparation, certification, and issuance of this standard reference material were coordinated through the Office of Standard Reference Materials by J. L. Hague.

Washington, D. C. 20234 J. Paul Cali, Chief

January 22, 1971 Office of Standard Reference Materials

(over)

113
U. S. Department' of Commerce

Maurice H. Stans SecroSrV

National B*r«aS vt Standards

L. M. Braitscfti*, Director Certificate of ^nalgsts

Standard Reference Material 984

Rubidium Chloride

RbCl, rubidium assay, weight percent 99.90 ± 0.02 Absolute abundance ratio, 85 Rb/87 Rb 2.593 ± 0.002

This lot of rubidium chloride was prepared to ensure material of intermediate purity and high

homogeneity. The material is somewhat hygroscopic, absorbing approximately 0.6 percent moisture

in a 75 percent relative humidity at room temperature, but can be dried to the original weight by

desiccation over freshly exposed P2 Os or Mg(C104 ) 2 for twenty-four hours. The material should

therefore be stored with a desiccant such as P2 Os

.

The assay of this material is based on the determination of rubidium by a combination of gravimetry and isotope dilution analysis on eight samples of about 2 g each of the dried RbCl. More

than 99% of the rubidium was precipitated, filtered and weighed as rubidium perchlorate. The

weight of RbC104 was corrected for potassium and cesium perchlorate. The soluble rubidium was

determined by isotope dilution mass spectrometry. The total rubidium was the sum of the rubidium

from the rubidium perchlorate and the rubidium from the filtrate. All weighings were corrected to vacuum and the atomic weights used in the calculations were from Ae 1969 Table of Atomic

Weights. The indicated tolerance is at least as large as the 95 percent confidence level for a single determination. -k \^sV V^

Chloride was determined by silver coulometry to bfi^9,3»Tweigat'percent. Preferential oxidation

of iodide and bromide showed that the material /contawis^CO.001% I and <0.003% Br. Flame

emission spectrometry indicated lithium, <Q*d2 pW^gmum, 2.3 ppm, potassium, 420 ppm; and

cesium 24 ppm. Emission spectrograph^exsggmatipn indicated, in addition, calcium, <10 ppm;

magnesium, <10 ppm; silicon, <10 ppm\ an^)aluminum, detection questionable. The loss on

ignition at 500 °C (20 hours^^OlplO^arid the insoluble matter was 0.0001%. A materials balance shows that 99.99 ± Oj02i^eigmJ|)ercent of the material is accounted for.

The absolute jdjrarraante^Stfi^of 8 s Rb/8 7 Rb was determined by triple-filament solid-sample mass spectrometr)^v MixtfureV*bf known 8S Rb/87 Rb ratio, prepared from nearly isotopically pure

separated mbidiunVCisotopes, were used to calibrate the mass spectrometers. The indicated

uncertainties are overall limits of error based on 95 percent confidence limits for the mean and

allowances for the effects of known sources of possible systematic error. Details of the preparation

and measurements are described in a published paper [J Res NBS, 73A, 511-516 (1969)]

.

The following members of the Analytical Chemistry Division contributed to the characterization of this material: T. J. Murphy and P. J. Paulsen - rubidium assay; G. Marinenko - chloride assay; T. C. Rains and T. A. Rush - flame emission determinations; E. K. Hubbard - emission spectro- graphic analysis; and E. J. Catanzaro and E. L. Garner - absolute ratio determination.

The overall direction and coordination of the technical measurements leading to certification were performed under the chairmanship of W. R. Shields.

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 J. L. Hague.

Washington, D. C. 20234

July 27, 1970

J. -Paul Cali, Acting Chief

Office of Standard Reference Materials

114
U. S. Department of Commerce

Maurice 11. Stan.3 Secretary

National B^reay of Standards

L. M. Brartscffmb, Director

Certificate of ^nal^si*

Standard Reference Material 1061c

Magnesium Cyclohexanebutyrate

(Standard for Determination of Magnesium in Petroleum Products)

This compound was prepared to ensure material that is essentially free from other metals and has

suitable solubility, compatibility, and uniformity for use in the preparation of a standard of mag- nesium in lubricating oils.CHEMICAL AND SPECTROGRAPHIC ANALYSES

Procedure and Results of Chemical Analysis

Magnesium, percent 6.45 ± 0.02

The uncertainty shown represents the 95 percent confidence limit oiYthc mean based on twelve determinations and allowances for the effects of known sources of ptJ^stolcwp&rs.

Magnesium was determined by wet-ashing a 1-g sanyatle^jlBQMcJy 48 hr over phosphorus pent- oxide) with sulfuric and nitric -acids, precipitating jtiwicevtvuh diammonium hydrogen phosphate,

and weighing the Mg2 P2 7 after ignition at K

Procedure and Results of Spectrograph

The compound was exarMfrfe^spKwographicaUy for metallic impurities. A 5-mg sample of the compound was excitecLw.a (oireencurrent arc and the photographed spectrum was examined for the

characteristic lines^eOft^le_meBfcs< No significant impurities were found.

STABILITY: Tests^how that standard lubricating-oil solutions of this compound with concentrations of magnesiunriip to 500 ppm are stable for several weeks when prepared by the directions given on the reverse side of this certificate.

The magnesium cyclohexanebutyrate was prepared by the Eastman Kodak Company of Rochester, N. Y. Chemical analyses were conducted by R. K. Bell and spectrographs analyses by V. C. Stewart.

The overall direction and coordination of the technical measurements leading to certification were performed 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 T. W. Mears.

Washington, D. C. 20234 J. Paul Cali, Acting Chief September 9, 1970 Office of Standard Reference Materials

115

FUNCTIONAL BLOCK DIAGRAM

OF

ELECTRON BEAM SCANNING SYSTEM

TO O.C. AMPS 1,2

TO RATE METERS

l-»

IOX

MAGNIFICATION IOK

IX

MODULATION ^OOT

MODE 1 BRIOHTNESS

Y-AREA +V

TRANSLATE

roRM NBS-1'4A (1-71)

1. PUBLICATION OR REPORT NO. NBS TN-582

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

2. Gov't Accession No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Activities of the NBS Spect rochemical Analysis

Section July 1970 to June 1971

5. Publication Date January 1972

6. Performing Organization Code

7. AUTHOR(S)

K. F. J. Heinrich and S. D. Rasberry, Editors

8. Performing Organization

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Proiect/Task/Work Unit No.

11. Contract/Grant No.

12. Sponsoring Organization Name and Address

Same as No. 9

13. Type of Report & Period Covered Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) Spectrochemical research activities, improvements in equipment and

applications , especially to the certification of NBS Standard ReferenceMaterials, are summarized. In optical emission spectroscopy, studies

have been carried out on a modified gas-sheath arc excitation source.

Application has been made of this source and several other conventional

excitation sources to analytical problems related to both standard

reference materials and other materials being investigated at NBS.

Newly derived computation procedures for quantitative x-ray fluorescence

analysis are described as well as new instrumentation added for x-ray

spectrochemical studies. In electron probe microanalysis, research

and new instrumentation has been directed to improved detection limits

and quantitation; special emphasis has been given to methods for small

particles and biological thin cuts. Methods of pre-concentration of

impurities have been advanced and applied, in some cases at parts per

billion (10~9) limits, to water pollution, river sediment specimens.

Mercury, cadmium, and lead were among the elements determined. Work on Standard Reference Materials resulted in certification of several special

steels, several high temperature alloys, a high-silicon steel and a titanium alloy, among others. Listings are given of 8 publications and

25 talks by members of the Section during the year.

17. key words (Alphabetical order, separated by semicolons) Analysis; computer program; electron

probe; microanalysis; optical spectrometry; pre-concentration techniques;

spectrochemical analysis; standard reference materials; x-ray fluorescenc

18. AVAILABILITY STATEMENT analysis

$X\ UNLIMITED.

I I FOR OFFICIAL DISTRIBUTION. DO NOT RELEASE

TO NTIS.

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

126

22. Price SL 25

USCOMM-DC 66244-P7I

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