Reference

NATL INST. OF STAND & TECH

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NBS TECHNICAL NOTE 1153

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U.S. DEPARTMENT OF COMMERCE/ National Bureau of Standards

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No. 1153

1982

A Survey of the Recent Literature

on Sampling for Chemical Analysis
NATIONAL BUREAU OF STANDARDS

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A Survey of the Recent Literature on Sampling

for Chemical Analysis u^. > . .

Byron G. KratochviP

Chemistry Department

University of Alberta

Edmonton, Alberta, Canada T6G2G2

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John K. Taylor

Center for Analytical Chemistry

National Measurement Laboratory

National Bureau of Standards

Washington, DC 20234

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National Bureau of Standards

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

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Issued January 1982
^:ii

National Bureau of Standards Technical Note 1153

Nat. Bur. Stand. (U.S.), Tech. Note 1153, 27 pages (Jan. 1982) CODEN:NBTNAE

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1982
Table of Contents

Page

1 . Introduction 1

2. General Comments on Sampling 2

3. Search Techniques 3

4. Annotated References 4

A. General References 4

B. Sampling Agricultural Products 15

C. Sampling the Atmosphere and Gases 16

D. Sampling Water and Waste Water 19

E. Sampling Miscellaneous Materials 21

n 1

A Survey of the Recent Literature on Sampling

for Chemical Analysis

Byron G. Kratochvil

University of Alberta, Edmonton, Alberta, Canada

and

John K. Taylor

National Bureau of Standards

Abstract

Sampling is one of the most important steps in chemical analysis, yet

it is often poorly planned and executed. One reason is that key information on sampling is scattered and relatively inaccessible. This

article summarizes the more important published articles obtained as the

result of a literature search to obtain essential background information

for the design of sampling plans and protocols for the National Environmental Specimen Bank. Each reference is briefly described so that its

applicability to a specific sampling question can be judged. The compilation consists of 56 references on general aspects of sampling, 9 references on sampling agricultural and food products, 14 references on sampling atmospheres and gases, 18 references on sampling water and waste

water, and 18 references on sampling miscellaneous materials.

Key words: Chemical analysis; sampling; sampling atmospheres;

sampling food; sampling miscellaneous materials; sampling plan;

sampling water.

1 . Introduction

Sampling is often the least-considered step in a chemical analysis.

Typically, the analyst has very little to do with the actual sampling

process. The sample received is assumed to be valid and to merit the

analytical work requested, which may be substantial. Too frequently, the

analyst is not a specialist in the discipline area of the material and

must trust the expertise of the specialist in that field. Usually neither

is an expert in sampling theory or practice, although more informed on the latter than the former. Accordingly, optimum sampling practices may

not have been followed.

There is a considerable amount of information on sampling available

in the technical literature but it is not easy to find. Some of it is

embedded in the discipline area of the matrix or in materials science.

Much of it is presented incidental to other problems so that careful

search is needed to discover it. The statistical aspects of sampling for

acceptance testing have been extensively covered, but this literature has

not been generally applied to materials investigations.

1
The references presented in this paper result from a literature

search in connection with the National Environmental Specimen Bank

(NESB). The MESB must pay careful attention to a wide variety of

problems ranging from sample selection, handling, subdivision, homogenization, preservation, to treatment prior to analysis. The search for

the available information on such problems was necessarily general since

there has been little or no prior research in sample banking. Since no extensive compilations of sampling information were discovered in this

search, it seemed appropriate to summarize the more important references

to assist others who may need to look more closely at the sampling

aspects of their analytical problems.

2. General Comments on Sampling

The g reviewed i 4A]. The

almost eve sample its case of th or for the

frequently

representa

from which

the measur

situations

and homoge

sampl ing m drawn from

eneral aspects of

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sample and the mea

ry chemical compos

el f is the only it

e identification o diagnosis of a he

, the test specime

five, and can prov

it was drawn. Ct

ement of samples c require careful c nization may also

ust be careful ly p the data.

sampling for c by the presen

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itional invest

em of composit

f a particular

al th probl em o

n is analyzed

ide informatio

her problems m ollected over onsideration o be involved,

lanned to perm

hemical analysis were

t authors [See Ref. 37, Section

share equal importance in

igation. Sometimes the test

ional concern, such as in the

specimen for forensic purposes

f a particular individual. More

because it is considered to be

n about the larger population

ay be quite complex, involving

intervals of time and space. All

f sample handling and treatment;

In most cases, all aspects of

it statistical inferences to be

The following is a brief summary of the most important questions that

must be addressed in designing a sampling plan:

* Is the sample unique or a member of a larger population?

* Is the sample considered to be homogeneous or heterogeneous

relative to the data requirements? If heterogeneous, is the

heterogeneity general, localized, or stratified?

* Is the composition constant or variable with respect to time,

temperature, pressure, or other physical conditions?

* What mode of sampling, should be used: random; systematic;

continuous; intermittent; discrete; composite?

* Is generally available sampling equipment suitable or are there

special requirements with respect to design, materials of

construction, and mode of operation? Does the problem require

discriminatory or non-discriminatory sampling equipment such

as special filters, or iso-kinetic sampling, for example?
* Does the problem require mean compositional data, information

about the extremes, or population distribution?

* Will the sample change due to interactions of components,

chemical or physical reactions with the container, or due to

environmental influences during transit or storage? Is stabilization required? What are the stabilizers that should

be used?

* What pre-treatment will be required, such as drying, mixing,

pulverization, sterilization, sieving, compositing, removal of

"foreign" substances, homogenization , and sub-sampling? What are the conditions and equipment requirements to handle such

operations effectively without damage to the sample?

* What number and what size of individual samples are required to

yield statistically meaningful results? What are the sampling

and measurement sequences required to identify the sample

variability in the presence of overall measurement variability?

* What are the quality assurance measures that need to be taken,

including the proper identification of samples and an operational chain of custody?

The details of sampling for routine analytical testing, for monitoring

industrial processes, for acceptance of materials, and for regulatory

compliance are generally well defined and have been standardized in some cases. A number of examples of such are included in Section 4. However,

there are many materials investigations for which the sampling plan needs

to be individually developed. The references of Section 4 have been

annotated to assist in indicating their possible usefulness and/or

applicability to a given situation.

3. Search Techniques

The search techniques used in this compilation included a computer

search of Chemical Abstracts, using the key words "sampling" and "method",

"procedure" or "program", a search of the subject files at the NBS library,

and a search of the NBS standards collection (ASTM, ISO, BSI). Because of

the vast literature on the sampling of specific substances under specific

conditions, and the varying extents to which sampling is treated in

conjunction with other areas, it was decided to make the coverage selective. The papers, chapters, and books listed here were selected for

inclusion on the basis of their breadth of coverage and range of applicability. In a compilation of this kind the selection necessarily reflects

the backgrounds and interests of the authors; we hope that the references

included here provide a beginning from which the list of references can be

extended in any given area of interest. For this purpose the Science

Citation Index is useful.
Much of the pioneering work in sampling has come from research on biological systems, but important contributions have also been made by

workers in mining and mineral exploration, and in water, soil, and air

studies. Therefore, many fields have contributed to the development of

sampling theory, and a variety of approaches are available for application

to most sampling problems. Considerable experience and common sense is

required to select the most appropriate and efficient sampling plan from

this variety.

4. Annotated References

A. General References

[1] Allen, T. ; Khan, A. A. Critical evaluation of powder sampling

procedures. Chem. Eng. 238:108-112; 1970.

Mixtures of coarse and fine sand and of sugar and sand were sampled by five procedures — scoop sampling, cone and

quartering, table sampler, chute riffler, and spinning

riffler. The spinning riffler was judged superior to the

other methods because of low maximum sampler error, high

sampler efficiency, and low operator bias.

[2] American Society for Testing and Materials, Probability sampling

of materials, ANSI/ASTM E105-58 (Reapproved 1975) Philadelphia, 1975,

Recommended practice for the preparation of a sampling plan

for a specific material.

[3] American Society for Testing and Materials, Choice of sample size to

estimate the average quality of a lot or process, ANSI/ASTM E122-72

(Reapproved 1979) Philadelphia, 1979.

Recommended practice for calculating how many units of a lot

to include in a sample to estimate, with a prescribed

precision, the average of some characteristic of the lot.

[4] American Society for Testing and Materials, Acceptance of evidence

based on the results of probability sampling, ANSI/ASTM E141-69

(Reapproved 1975) Philadelphia, 1975.

Presentation of a rule based on statistical evidence by which

to judge evidence based on samples. The rule provides an estimate of the result expected if the entire lot were investigated in the same way as the sample.
[5] American Society for Testing and Materials, Sampling industrial

chemicals. ANSI/ASTM E300-73 (Reapproved 1979) Philadelphia, 1979.

An outline of principles to be observed in establishing

procedures for sampling several classes of industrial

chemicals. Included is information on statistical considerations, equipment, time and place of sampling, sample

reduction, and slurry sampling.

[6] American Society for Testing Materials, Definitions of terms relating to statistical methods. ANSI/ASTM E456-72, Philadelphia, 1972.

A list of definitions for the terms accuracy, assignable

cause, lot, universe (population), precision, repeatability,

reproducibility, and sample.

[7] Anders, 0. U. Representative sampling and the proper use of

reference materials. Anal. Chem. 49:33A-36A; 1977.

A summary of a plenary discussion held at the International

Conference: Modern Trends in Activation Analysis, September 1976,

[8] Bauer, E. L. A statistical manual for chemists, 2nd Ed. New York:

Academic Press; 1971. 131-144.

An excellent discussion of sampling by attributes and sampling

by variables, including hov; to calculate the number of samples

to analyze in order to achieve a preselected degree of confidence in the results.

[9] Beech, D. G. Sampling of hard heterogeneous materials. II.

Detailed statistical treatment. Trans. Brit. Ceram. Soc. 70:13-17;

1971.

A nonmathematical discussion of the statistical analysis of

three sampling experiments on chrome are described by

Bennett, Eardley, and Beech in reference [11], below.

[10] Benedetti-Pichler, A. A. Theory and principles of sampling for

chemical analysis, chapter in Physical methods in chemical analysis.

Vol. III. W. G. Berl , ed. New York: Academic Press; 1956. 183-217.

Treats theory of sampling, computation of sample size, and

multiple sampling operations in approximately the first half

of the article, and the practice of sampling, including particle

size reduction, mixing, and sampling techniques, in the second

half. Somewhat out of date, but provides useful background

information.
[11] Bennett, H. ; Eardley, R. P.; Beech, D. G. Sampling of hard heterogeneous materials. I. Derivation of a new and simple technique.

Trans. Brit. Ceram. Soc. 70:1-12; 1971.

Studies on three chromite ores showed that, for two of them,

the composition of the ore was fairly independent of the

diameter of the pieces selected in the sample. The third ore was uniform also except for the finer (<l/8 inch diameter) and

the largest pieces (12 inches or more in diameter).

[12] Bicking, C. A. The sampling of bulk materials. Mat. Res. Stds.

7:95-116; 1967.

A review of the problems of physically obtaining samples of

material occurring in bulk form, and of the use of statistics

in providing information on the minimum sampling adequate to

make a reliable judgment about a lot.

[13] Bicking, C. A. Sampling, Kirk-Othmer Encyclopedia of Chemical

Technology, 2nd Ed. 17:744-762; 1968.

A general discussion of the problems associated with the

sampling of chemicals and how to solve them.

[14] Bicking, C. A. Principles and methods of sampling, chapter in

Treatise on analytical chemistry, 2nd Ed., Vol. I. I. M. Kolthoff

and P. J. Elving,'eds. New York: John Wiley & Sons; 1979. 299-359.

A discussion primarily of techniques and methods of sampling

fluids, compact solids, and particulate solids, but including

definitions and problems of sampling, determination of sample

size, and sampling to determine the average of some property

of a lot or to identify and measure the variations in a non- homogeneous material.

[15] British Standards Institution. Methods for sampling chemical products

Part 1. Introduction and general principles. BS 5309, London; 1976.

Background to subsequent parts 2 to 4, which provide specific

instruction for sampling gases, liquids, and solids.

Part 1 covers definitions, basic purposes and principles of

sampling, statistical information, and safety.

[16] Brown, G. H. ; Fisher, N. I. Subsampling a mixture of sampled

material. Technometrics 14:663-668; 1972.

A mathematical treatment of the effect of the degree of

blending of a composite sample on the adequacy of the

sample as a representative of the lot.
[17] Cochran, W. G. Sampling techniques, 2nd Ed., New York: John Wiley

& Sons; 1963. 9-17 and 374-389.

A book emphasizing sociological and business surveys, but

containing some general information useful to chemical

sampling situations. Pages 9-17 treat the role of sampling

theory, probability sampling, use of the Gaussian distribution, bias and its effects, and mean square error. Pages

374-389 cover a mathematical model for errors of measurement,

effects of constant bias (systematic error), effects of errors that are uncorrected within a sample, effects of

intrasample correlation between errors, and treatment of

interpenetrating subsamples.

[18] Duncan, A. J. Bulk sampling. Section 25A, in Quality control

handbook. J. M. Juran, ed. New York: McGraw-Hill; 1974. 25A1-25A13.

A clear, readable treatment of bulk sampling that emphasizes

the need to create a "sampling model" that can be used to

determine the sample size needed for each type of bulk material.

.Included is statistical theory applicable to the sampling of

bulk materials.

[19] Engels, J. C. ; Ingamells, C. 0. Effect of sample inhomogeneity on K-Ar dating. Geochim. Cosmochim. Acta 34:1007-1017; 1970.

Quantitative effects of grain size of a rock or mineral sample,

and of the composition of contaminating minerals, are evaluated.

[20] Grant, C. L. ; Pelton, P. A. Role of homogeneity in powder sampling,

ASTM Special Technical Publication No. 540; American Society for

Testing and Materials. Philadelphia, 1973, 16-29.

The importance of homogeneity in sampling powders for analysis

is discussed in terms of the size of a segregation unit relative

to the size of the sample. Both theoretical and experimental

treatments are included. Much of this work is included in

reference [21].

[21] Grant, C. L.; Pelton, P. A. Influence of sampling on the quality

of analyses with emphasis on powders. Advances in X-ray Analysis

17:44-67; 1974.

A discussion of the effect of sampling on the determination

of trace elements. The Wilson-modified form of the BenedettiPichler equation for calculating sampling error is discussed

and tested experimentally on two particulate systems. Agreement between the predicted and experimentally-found error was satisfactory.
[22] Gy, P. Theory and practice of sampling bulk particulate mixtures.

New York: Elsevier; 1979.

This book provides an in-depth study of the sources of error

in sampling of bulk materials. It is not addressed to users

of sampling, but rather to those studying the mechanisms

whereby sampling errors are generated.

[23] Hackler, W. C; Clatfeller, T. E.; Farley, J. M.; Heckler, C. L. ; Rilee, E. E. , Jr. Statistics in sampling of bulk material.

Ceramic Bull. 52:882; 1973.

Sampling plans for evaluating the quantity of the mineral

kyanite and for assessing variability at four sampling

stages are presented. The minimum sample size required,

and the results of a composite sample, are also treated.

[24] Hahn, G. J. How large a sample do I need for 95% confidence?

CHEMTECH 5:61-62; 1975.

A note outlining briefly but clearly how to calculate

the sample size required to estimate a population average

with some desired precision.

[25] Harnby, N. The statistical analysis of particulate mixtures.

Part 1. The sampling of mixtures and the resultant precision of

estimates based on the sample. Powder Technology 5:81-86; 1971/72,

A treatment of the use of average, standard deviation, and

variance as statistical descriptors of particulate mixtures

is discussed. The precision of the results was found to

depend on sampling techniques, number of samples, and nature

of the mixture.

[26] Harnby, N. The statistical analysis of particulate mixtures.

Part 2. The application of social survey statistical techniques

to solids mixing problems. Powder Technology 5:155-165; 1971/72.

The application of statistical methods developed in social

survey sampling to the sampling of particulate mixtures for

analysis is discussed. The coefficient of correlation provides a measure of the homogeneity of the elements within

a sample; the relationship between the coefficient of correlation and sample size is derived for several mixture models.

[27] Harris, W. E.; Kratochvil, B. Sampling variance in analysis for

trace components in solids. Anal. Chem. 46:313-315; 1974.

A note discussing the question of how large a sample must

be taken for a single analysis when the component of interest

is in discrete small particles.
[28] Heiland, R. E. ; Richardson, W. J. Work sampling. New York:

McGraw-Hill; 1957.

Excellent discussion of Gaussian distribution, probability,

and the binomial theorem in clear, simple language.

[29] Ingamells, C. 0. New approaches to geochemical analysis and

sampling. Talanta 21:141-155; 1974.

A discussion of the problems of preparation of a geological

field sample for chemical analysis, and of the use of sampling

constants as a guide to the description of the optimum size

and the characteristics of samples and subsamples.

[30] Ingamells, C. 0. Control of geochemical error through sampling and

subsampling diagrams. Geochem. Cosmochim. Acta 38:1225-1237; 1974.

Sampling error can be estimated and controlled during

analysis of mixtures through use of sampling diagrams based

on statistical models that combine Gaussian and Poisson

statistics.

[31] Ingamells, C. 0. Preparation, analysis, and sampling constants for

a biotite, in Accuracy in trace analysis. Nat. Bur. Stand. (U.S.)

Spec. Publ. 422; 1976 August, p 415.

Figure 2 in this article illustrates a sampling diagram for

the determination of potassium in a biotite, and shows how

the sampling error decreases with increasing sample size.

[32] Ingamells, C. 0. General sampling theory, in Sampling and

assaying precious metals. Corrigan, D. A.; Browning, B., eds.

Proceedings of second international seminar; 1980; Brooklyn,

New York, Int. Precious Met. Inst., Inc., pp 39-63.

A review of sampling of uniform and segregated materials for

chemical analysis.

[33] Ingamells, C. 0.; Pitard, F. F. ; Fox, J. J.; Samland, P. K. ; Bright, M. J. Evaluation of skewed exploration data. Extended

abstracts - international symposium anal. chem. explor. min.

process mater. CSIR, Pretoria, South Africa; 1977. pp 208-13.

The major sources of variance in skewed data, large- and

small-scale inhomogeneity and subsampling error, are modeled

as a double Poisson distribution, the parameters of which

reflect the characteristics of the ore-body (relevant

variance) and of the sample reduction process (irrelevant

variance)
[34] Ingamells, C. 0,; Switzer, P. A proposed sampling constant for use in geochemical analysis. Talanta 20:547-68; 1973.

To distinguish between analytical and subsampling error, the use of a sampling constant, defined as K = R^^^^^ where R is

the relative standard deviation of a set of measurements of

the sought-for substance and w is the weight of material

taken for each measurement, is recommended. The approach

is considered reliable if the value of K is based on ten or more measurements, and if the sought-for material is not

present at trace levels in a highly heterogeneous form.

[35] Japanese Industrial Standard, General rules for methods of sampling

bulk materials, JIS M 1800-1973, Japanese Standards Association.

English translation, Tokyo; 1975. 75 pp.

This document covers: (1) general background, including

definitions and overall sampling procedures; (2) methods of

determining the size and number of increments and forming

subsamples, and sampling from moving belts, from bins such

as ship holds, and from trucks or railway cars; (3) methods

of sample preparation, such as crushing and division, prior

to analysis; and the method for determination of particle

size distribution of a sample. Appendices describe experimental methods for checking precision or bias in sampling

operations, and for evaluating variations in two-stage

sampling and in stratified and periodic systematic sampling.

[36] Kateman, G. ; Muskens, P. J. W. M. Sampling of internally correlated

lots. The reproducibility of gross samples as function of sample

size, lot size, and number of samples. II. Implications for

practical sampling and analysis. Anal. Chim. Acta 103:11-20; 1978.

This paper describes how to reach a required accuracy in the

composition of a gross sample relative to the lot from which

it has been taken. (See Ref. 46 for Part I.)

[37] Kratochvil, B. G. ; Taylor, J. K. Sampling for chemical analysis.

Anal. Chem. 53:A-938A; 1981.

A general discussion of the importance of sampling, and the

development of sampling plans.

[38] Kleeman, A. W. Sampling error in the chemical analysis of rocks.

J. Geol. Soc. Aust. 14:43-47; 1967.

An application of the approach of Benedetti-Pichler to the

estimation of minimum sample size as a function of particle

size.

10
[39] Kristensen, H. G. Statistical properties of random and non-random

mixtures of dry solids. Part I. A general expression for the

variance of the composition of samples. Powder Technology 1:249-

257; 1973.

An equation is derived for the variance of the composition

of samples drawn from a mixture of two or more components.

Among the factors incorporated is a coefficient of correlation

that gives the degree of correlation between the composition

of neighboring particles in the mixture.

[40] Kristensen, H. G. Statistical properties of random and non-random

mixtures of dry solids. Part II. Variance-sample size relationships derived by autocorrelation theories. Powder Technology

8:149-157; 1973.

The properties of the coefficient of correlation described

in Part I are examined theoretically and experimentally,

and an equation relating the variance between samples and

the sample size is derived.

[41] Ku, H. H. Statistical sampling and environmental trace organic

analysis, in Trace organic analysis: A new frontier in analytical

chemistry. Nat. Bur. Stand. (U.S.) Spec. Publ . 519; 1979 April,

pp 1-6.

A general discussion of the place of statistical sampling

schemes in the field of analytical chemistry, both historically

and for the future. The design of a sampling scheme depends

almost entirely on the purpose of the analytical operation.

[42] Kwolek, W. F. ; Lillehoj, E. B. Analytical variation when proportions

of sampled units contain the active agent. J. Assoc. Off. Anal.

Chem. 59:787-794; 1976.

A statistical procedure is outlined for the determination of

the effect of sample size, sub-sample size, and particle

size on the precision of an assay. In the procedure it is

assumed that the active agent is present in only a portion

of the particles comprising the sample.

[43] Mace, A. E. Sample size determination. New York: Reinhold; 1964.

A manual that provides mathematical procedures for determining

the optimum size of a research experiment. Emphasis is on engineering applications. Major topics include estimation

problems, tests of hypotheses, selection problems, sequential

sampling, and lot acceptance sampling.

11
[44] Military Standard 105D, Sampling procedures and tables for

inspection by attributes. Washington, D.C.: U. S. Government

Printing Office; 1963 April.

This publication provides sampling procedures and reference

tables for use in planning and conducting inspection by

attributes.

[45] Military Standard 414, Sampling procedures and tables for

inspection by variables for percent defective. Washington, D.C.:

U. S. Government Printing Office; 1957.

A set of sampling plans based on variables rather than on attributes. Plans based on variables are more desirable

when measurement data are available because fewer samples

need be measured to provide the same level of confidence as for plans based on attributes.

[46] Muskens, P. J. W. M. ; Kateman, G. Sampling of internally correlated

lots. The reproducibility of gross samples as a function of sample

size, lot size, and number of samples. Part I. Theory. Anal.

Chem. Acta 103:1-9; 1978.

The relation between lot size, sample size, and number of

samples is derived for lots with internal correlation. (See

Ref. 36 for Part II.)

[47] Quackenbush, F. W. ; Rund, R. C. The continuing problem of sampling.

J. Assoc. Off. Anal. Chemists 50:997-1006; 1967.

Sampling procedures are discussed in a general way, with

special reference to sampling tools, the applicability of

random sampling, and statistical considerations.

[48] Scheide, E. P.; Filliben, J. J.; Taylor, J. K. Survey of the

occurrence of mercury, lead, and cadmium in the VJashington, D.C. area. NBSIR 78-1428; 1977.

This report describes the development of a plan to comprehensively survey the occurrence of potentially toxic substances

in a defined geographical area. It describes the basic

philosophy of such a survey, the development of the sampling

plan, and methods of data reduction using unique computergenerated plots to show concentration profiles.

12
[49] Skogerboe, R. K. ; Morrison, G. H. Role of sampling in trace

analysis. In Preprints of contributed papers. Symposium on trace

characterization-chemical and physical. Nat. Bur. Stand (U.S.).

1966 October, pp 589-595.

This paper- examines the problems of obtaining representative

samples for the analysis of trace elements that are distributed heterogeneously, and for establishing the topographical

" distribution of these traces.

[50] Slack, K. V. ; Averett, R. C. ; Greeson, P. E.; Lipscomb, R. G. Methods for collection and analysis of aquatic biological and

microbiological samples. Chapter A4 of Book 5, Laboratory

analysis in techniques of water-resources investigations of the

U. S. Geological Survey. Washington, D.C.: U. S. Government

Printing Office; 1973. 6-26.

A discussion of biological sampling and statistics.

The first part describes distribution patterns of organisms

in nature and the design of monitoring programs. The

second part describes distribution models, sampling

statistics (including sample size; random, stratified

random, and two-stage sampling), and biological diversity.

[51] Tomlinson, R. C. Sampling, in Comprehensive analytical chemistry.

Vol. lA. W. L. Wilson; D. W. Wilson, eds. New York: Elsevier;

1959. 36-75.

A treatment of sampling in three parts: general principles,

practical problems, and methods of calculating sampling

precision. Provides useful general information on the

number and size of sample increments. Well written and readable,

[52] Visman, J. A general sampling theory. Mat. Res. Stds. 9:9; 1969.

A general theory is presented for sampling, based on the

premise that the variance in a bulk lot of a material can

be expressed by a relation incorporating two sampling

constants. The relation may be used to design sampling

programs, and to determine in advance the precision of a sampling experiment as a function of sample size and

the number of increments. See also discussions of this

article listed below:

Duncan, A. J. Comments on "A general sampling theory", Mat.

Res. Stds. 11(1):25; 1971.

In this note it is shown that the empirical results

of Visman can in part be derived from statistical

theory.

13
Visman, J.; Duncan, A. J.; Lerner, M. Further discussion:

"A general theory of sampling", Mat. Res. Stds. 11 (8): 32;

1971.

In this note Visman and Duncan discuss the generality

of the Visman approach, as well as its validity under

certain circumstances. Lerner summarizes their points

of view, and concludes that the Visman procedure, while

not strictly 'general', is a giant step above the

previous rules-of-thumb often used.

Visman, J.; Duncan, A. J. Discussion 3 on "A general

theory of sampling". J. Mat. 7:345; 1971.

Here Visman develops further the factors that hold

the constant relating to segregation variance at a stable value. Duncan agrees with Visman 's treatment

and conclusions, and develops the statistical theory

for Visman 's approach.

[53] Williams, W. H. A sampler on sampling. New York: Wiley; 1978.

A readable discussion of the problem of sampling, with many

examples from real life, particularly from social and

financial sources.

[54] Wilrich, P. Th.; Leers, K. J. Statistical considerations in the

sampling of bulk goods. Ber. Dt. Keram. Ges. 51:256; 1974.

The problems of efficient and economical sampling are discussed under eight points. The authors stress that

preliminary information on the standard deviation of

sampling is necessary before a rational sampling procedure

can be established, or the degree of representativeness of

the samples taken be determined.

[55] Wilson, A. D. The sampling of silicate rock powders for chemical

analysis. Analyst 89:18; 1964.

The sampling errors in a heterogeneous rock powder depend

fundamentally on the weight multinominal distribution of

the mineral particles. For samples of varying particle

size, the total number of particles is of no special

significance and should be replaced by a weighted

reciprocal mean.

14
[56] Youden, W. J. The role of statistics in regulatory work. J. Assoc. Off. Analyt. Chemists 50:1011-1013; 1967.

Sampling variance in bulk materials is considered.

A library of sampling experience on a given material is shown

to be a useful guide to how many samples are required from a given lot to achieve a desired certainty in the result.

B. Sampling Agricultural and Food Products

[1] Horwitz, W. ; Howard, J. W. Sampling methods in trace organic

analysis in food. Nat. Bur. Stand (U.S.) Spec. Publ . 519; 1979

April, pp 231-242.

Excellent overall discussion of sampling problems in foods,

presented in a non-theoretical way. Includes examples of

sampling for pesticide residues, aflatoxins, and N-nitrosamines

[2] Lento, H. G. The role of sample preparation in nutritional food

labeling. Nat. Bur. Stand. (U.S.) Spec. Publ. 519; 1979 April,

pp 243-248.

A brief outline of the problems encountered by the food

scientist when removing samples for nutritional analysis

from large lots.

[3] Schuller, D. L.; Horwitz, W. ; Stoloff, L. Review of sampling plans

and collaboratively studied methods of analysis for aflatoxin.

J. Assoc. Off. Anal. Chem. 59:1315-1343; 1976.

A detailed review of the methods developed for the sampling

and testing for aflatoxins in foods and feeds. Aflatoxins

are the only food contaminants routinely monitored on an international scale at the 10 ppb level.

[4] Whitaker, T. B.; Dickens, J. W. Variability of aflatoxin test

results. J. Am. Oil Chem. Soc . 51:214-218; 1974.

A discussion of the uncertainty introduced into results

for the measurement of aflatoxins in peanuts owing to

sampling variance.

[5] Williams, C. J.; Peterson, R. G. Variation in estimates of milk

fat, protein, and lactose content associated with various bulk

milk sampling programs. J. Dairy Sci. 61:1093-1102; 1978.

The variation associated with various sampling programs

was tested. Random sampling was indicated to be cheaper

and more accurate than composite sampling.

15
[6] International Standards Organization, Fresh fruits and vegetables

Sampling. ISO 874; 1980.

General conditions relating to the sampling for the

assessment of quality, stressing acceptance testing.

[7] International Standards Organization, Meat and meat products - Part I - Taking primary samples. ISO 3100/1; 1975.

General principles are set forth for sampling meat and

meat products. Part II in preparation deals with the

number of primary samples to be taken from a lot.

[8] International Standards Organization, Oilseeds - Sampling.

ISO 874; 1980.

General conditions relating to sampling of oil seeds for

assessment of quality when purchased as industrial raw products. Equipment and sampling schemes are described.

Companion standard ISO 664 establishes a procedure to

obtain representative samples.

[9] International Standards Organization, Tea - Preparation of ground

samples of known moisture content. ISO 1572; 1975.

This is a companion standard to be used with ISO 1573

which describes a drying procedure and method for

determination of moisture content.

C. Sampling the Atmosphere and Gases

[1] American Society for Testing and Materials. Standard definitions

of terms relating to atmospheric sampling and analysis. ANSI/ASTM

D1356; 1973.

Seven pages of definitions.

[2] American Society for Testing and Materials. Standard recommended

practice for planning the sampling of the atmosphere. ANSI Z257.1/

ASTM D1357; 1957.

A presentation of the broad concepts of sampling the atmosphere,

with emphasis on statistical planning, meteorological factors

and effects of topography.

16
[3] American Society for Testing and Materials. Standard recommended

practice for sampling atmospheres for analysis of gases and vapors.

ANSI Z257.2/ASTM D1605; 1960.

Detailed discussion of apparatus and procedures for obtaining

valid samples of gaseous materials for industrial and environmental applications.

[4] American Society for Testing and Materials. Standard method for

sampling stacks for particulate matter. ANSI Z257.3/ASTM D2928;

1971.

Specific details of apparatus and procedure are described

in 21 pages.

[5] Axelrod, H. D. ; Lodge, J. P. Sampling and calibration of gaseous

pollutants, chapter in Air pollution, 3rd ed.. Vol. 3. A. C. Stone,

ed.; 1976. 146-182.

A useful broad treatment of materials considered as pollutants, especially at trace levels.

[6] British Standards Institution. Methods for sampling chemical

products. Part 2. Sampling of gases. BS 5309, Part 2; 1976. 21 p.

A critical evaluation of the apparatus and techniques for

collection of spot, continuous, intermittent, and composite

samples. Provides a thorough, clear, treatment.

[7] Bunn, W. W. ; Deane, E. R. ; Klein, D. W. ; Kleopfer, R. D. Sampling

and characterization of air for organic compounds. Water, Air,

Soil Pollution. 4:367; 1975.

A brief treatment of the apparatus and general approach

required to sample organic substances present in air.

[8] Carvagnaro, D. M. Air pollution sampling of particles. National

Technical Information Service PB80-802853; 1979. 209 p.

A bibliography, including abstracts, of 202 references covering

techniques of sampling particles in the earth's atmosphere.

[9] Fox, D. L.; Jefferies, H. E. Air pollution. Anal. Chem. 51:22R-;

1979.

Most recent of a series of biennial reviews on the title

topic that includes some references on sampling.

17
[10] Lamb, S. I.; Petrowski, C; Kaplan, I. R. ; Simoneit, B. R. T.

Organic compounds in the urban atmosphere: a review of distribution, collection, and analysis. J. Air Pollut. Control Assoc.

30:1098-1115; 1980.

A detailed reivew with 421 referencess, of which one-half

page and 24 references are devoted to overall sample collection techniques, and an additonal one and a half pages and

34 references devoted to adsorption traps, filtration,

impingers and impactors, and cryogenic traps for collection

of organic compounds.

[11] Liu, B. Y. H., ed. , Fine particles: Aerosol generation, measurement,

sampling, and analysis. New York: Academic Press; 1976. 837 p.

A detailed treatment of an often neglected component of

atmospheres.

[12] Lodge, J. P., Jr. Accuracy in air sampling. Nat. Bur. Stand.

(U.S.) Spec. Publ. 422; 1976 August, pp 311-320.

A general discussion emphasizing the problem of ensuring

that the sample is representative.

[13] Morrow, N. L.; Brief, R. S.; Bertrand, R. R. Sampling and

analyzing air pollution sources. Chem. Eng. 24:84-98; 1972

January 24.

A good treatment of the precautions necessary for the

collection of a valid sample from a stack.

[14] Tomingas, R. Remarks on the sampling procedures for polycyclic

aromatic hydrocarbons from the atmosphere. Fresenius' Z. Anal. Chem.

297:97-101; 1979.

Analytical results for polycyclic aromatic hydrocarbons

are low owing to losses during sampling. The losses depend

on the vapor pressure of the individual hydrocarbon, the

air flow rate through the sampler, the presence of oxidants

such as sulfur dioxide, and the time of sampling.
D. Sampling Water and Waste Water

[1] Ahmed, S. M. ; Beasley, M. D. ; Efromson, A. C; Hites, R. A. Sampling errors" in the quantitation of petroleum in Boston Harbor

water. Anal. Chem. 46:1858-1860; 1974.

Sampling errors reported to be much greater than the error

in analysis by infrared measurements. A calculation showed

that an increase in the number of replicates was generally

better than larger samples.

[2] American Society for Testing and Materials. Standard practice for

sampling water. ASTM D3370; 1976.

A broadly useful discussion of the apparatus and procedures

for obtaining valid samples from streams, lakes, and other

bodies of water.

[3] Batley, G. E. ; Gardner, D. Sampling and storage of natural waters

for trace metal analysis. Water Res. 11:745-756; 1977.

A comprehensive review of the methods of collection, storage,

and preservation of water samples for trace metal analysis.

[4] Bowtron, C. Reduction of contamination problems in sampling of

antarctic snows for trace element analysis. Anal. Chim. Acta

106:127; 1979.

The procedure involves collection in 10-m deep pits with

clear plexiglass tubes by operators wearing cleanroom

clothes, particle masks, and clean PVC gloves.

[5] Grasshoff, K. , ed. , Methods of seawater analysis. Weinheim:

Verlag Chemie; 1976.

Includes sections on sampling and sample handling.

[6] Hensley, C. P.; Jeffer, W. J.; McKenzie, C; Lair, M. D. Continuous monitoring, automated analysis, and sampling procedures,

J. Water Pollut. Control Fed. 50:1061-1066; 1978.

A review of the title topics. About 10 of the 57 references

deal with sampling.

19
[7] International Standards Organization, Water quality - Sampling - Part 1; Guidance on the design of sampling programmes. ISO 5667/1-

1980(E); 27 p.

This part gives general principles to be applied in the design

of sampling programs for quality control and for identification

of sources of pollution of water, including bottom sediments.

It contains sections on definitions of objectives, identification of sampling situations, time and frequency of sampling,

and flow measurements.

Subsequent parts currently being drafted include Part 2:

General guidelines to sampling techniques, and Part 3: General

recommendations for the preservation and handling of samples.

[8] Kinasford, M. Sampling of surface waters. Water, Soil Tech. Publ

.

2:15; 1977.

Provides guidelines for sampling surface waters, with

principles of sampling and recommended procedures for

sample storage and preservation.

[9] Liebetrau, A. M. Water quality sampling: some statistical

considerations. Water Resour. Res. 15:1717-1725; 1979.

A network of sampling stations is designed on the basis

of probability sampling.

[10] Miller, J. M. The collection and chemical analysis of precipitation. Proc. nat. conf. complete, water reuse, 2nd; 1975; Pub.

1976; 331-337.

A review with four references.

[11] Otson, R.; Williams, D. T.; Bothwell, P. D. ; McCullough, R. S.;

Tate, R. A. Effects of sampling, shipping, and storage on total

organic carbon levels in water samples. Bull. Environ. Contam.

Toxicol . 23:311-318; 1979.

The sampling, storage, and shipping conditions studied had

little effect on the total organic carbon levels in tap and

river water samples at moderate concentrations, but con- tamination is possible at low levels.

[12] Ottendorfer, L. J. Analytical problems concerning natural

waters. Proc. anal. div. chem. soc. 15:52; 1978.

A discussion emphasizing the problems of sampling, sample

handling, and sample transportation.

20
[13] Sharpley, A. N. Phosphorus inputs into a stream draining on agricultural watershed. Water, Air, Soil Pollution 6:39; 1976.

Too low a frequency of sampling intervals led to large errors in estimation of the phosphorus inputs.

[14] Shelley, P. E. Sampling of water and wastewater. National

Technical Information Service, PB Rep., PB-272664; 1977.

A report treating the mechanics of poly-disperse systems

as they affect the collection of analytical samples.

[15] Staff of Research and Education Association, Sampling in wastewater monitoring, chapter 33 in Modern pollution control technology.

Vol. II. New York: Research and Education Association; 1978.

33-1 to 33-25.

A practical discussion of the major considerations in

sampling waste streams. Sample handling and preservation

are covered, and equipment available for sampling is described.

[16] Thompson, R. J. Sampling and analysis techniques in current use

in the EPA/NOAA/WMO precipitation network. World Meteorological

Organization (Publ.) 460:40; 1977.

[17] Wagner, R. Sampling and sample preparation. Water, Z. Anal. Chem.

282:315-321 ; 1976.

A review of the problems and techniques of water sampling.

Applicability and performance of individual, composite, and

automatic sampling are discussed, as is sample storage.

[18] Ziegler, W. J. Variability in water analysis introduced by

sample collection, preservation, or preparation techniques.

Proc. ann. ind. air water pol lut./contam. control semin. 9:14;

1979.

Discussion includes municipal and industrial waste water

as well as water for municipal use.

E. Sampling Miscellaneous Materials

[1] ACS Subcommittee on Environmental Chemistry. Guidelines for data

acquisition and data quality evaluation in environmental chemistry,

Anal. Chem. 52:2242-2249; 1980.

These guidelines include sections on the minimum requirements

of a valid sampling program, and a discussion of how to

employ statistics in planning and interpreting sampling

operations in the environment.

21
[2] Allard, M. Sampling and sample preparation of scrap. Erzmetall

32:437-440; 1979.

A review of sampling non-ferrous scrap that is rejected by

' the electrical and electronics industry but contains precious

metals. "No references are given.

[3] American Pulp and Paper Institute. Standard for sampling and

analysis of coal. TAPPI T6050S.

Detailed outline of the procedure necessary for the valid

sampling of coal

.

[4] Ball, D. F. ; Williams, W. F. Variability of soil chemical properties

efficiency of sampling programs on an uncultivated brown earth.

J. Soil Science 22:60-68; 1971.

The determination of eight different quantities, such as pH,

loss on ignition, total nitrogen, exchangable potassium, and

so on was performed on a large number of samples collected by

nine different sampling programs. The average results for

all the parameters except loss on ignition were found to be

statistically significantly different between programs.

[5] Eberhardt, L. L. ; Gilbert, R. 0.; Hollister, H. L.; Thomas, J. M.

Sampling for contaminants in ecological systems. Environ. Sci

.

Technol. 10:917-925; 1976.

Objectives, models of ecological systems, frequency distributions and sampling designs are discussed. No universal model

appears applicable at present; instead, various individual

models serve specific purposes. The use of body size (length

and weight) as an auxiliary variable in sampling is recommended

for either comparison or estimation.

[6] Ibbott, F. A. Sampling for clinical chemistry. Nat. Bur. Stand.

(U.S.) Spec. Publ. 422; 1976 August, pp 353-360.

A list of three requirements for an acceptable physiological

sample is given: appropriate physical state of patient, such

as fasting; blood samples that are as representative as possible; and proper storage and preservation of the sample.

[7] Lawhorne, S. Demilitarization plan: operation of the chemical

agent munitions disposal system (CAMDS) at Tooele Army Depot,

inclosure number 2, statistically significant sampling program.

National Technical Information Service, DRCPM-DRD-TR-74017;

Report 1977; 21 p.

A report describing the tests conducted to determine the

characteristics of stockpiled munitions.

22
[8] Liu, K. ; Cooper, R. ; Soltero, I.; Stamler, J. Variability in

24-hour urine sodium excretion in children. Hypertension (Dallas)

1:631-636; 1979.

Six 24-hour urine specimens must be collected from a child for

sodium measurement if the probability of misclassifying a child

in the top third relative to the bottom third is to be held

to 0.01. The ratio of intra- to inter-individual variances

was estimated to be 1.94 for 24-hour urine sodium.

[9] Maienthal, E. J.; Becker, D. A. A survey of current literature on sampling, sample handling, and long term storage for environmental

materials. Nat. Bur. Stand. (U.S.) Tech Note 929; 1976 October.

40 p.

A critical survey of the title topic, with emphasis on procedures that are most likely to maintain high sample

integrity.

[10] Marinenko, R. B.; Heinrich, K. F. J.; Ruegg, F. C. Microhomogeneity

of NBS standards. Proc. Ann. Conf. - Microbeam Anal. Soc, 14th,

1979; 221-226.

A procedure for testing the microhomogeneity of such standard

reference materials as alloys and glasses is described. An

electron microprobe is programmed to take measurements on the

sample each 1 to 10 ym along the surface.

[11] Maxwell, J. A. Sampling and sample preparation at the geological

survey of Canada. Nat. Bur. Stand. (U.S.) Spec. Pub. 422; 1976

August, pp 285-297.

A general discussion, with emphasis on the importance of

representative sampling. Few details of sampling operations

are provided.

[12] McNair, P.; Nielsen, S. L. ; Christiansen, C; Axelsson, C. Gross errors made by routine blood sampling from two sites using a tourniquet applied at different positions. Clin. Chim. Acta

98:113-118; 1979.

Tourniquets may induce hemoconcentrations , leading to high

levels of serum protein and protein-bound substances.

Increases of 5 to 13 percent were observed. Calcium and

magnesium were similarly affected.

23
[13] Protzer, H. Sampling of alloys susceptible to segregation.

Erzmetall 32:430-437; 1979.

A review with eight references on the factors affecting

segregation in liquid alloys upon solidification. Includes

a discussion of milling and drilling techniques for the

sampling of solid alloys, and ways of preparing homogeneous

samples from molten alloys.

[14] Sansoni, B. ; Iyengar, V. Sampling and sample preparation methods

for the analysis of trace elements in biological material.

Spez. Ber. Kernforschangsanlage Juelich. Juel-Spez 13; 1978; 79 p.

A review with many references about sampling and sample

preparation of human body tissues and fluids.

[15] Scilla, 6. J.; Morrison, G. H. Sampling error in ion microprobe

analysis. Anal. Chem. 49:1529-1536; 1977.

Sampling errors in ion microprobe analysis of heterogeneous

materials are investigated. Use of the sampling constant

concept is suggested. Equations that allow estimation of the

degree of heterogeneity in a sample are presented, and procedures to determine the number of replicate analyses

necessary to achieve a desired precision are outlined.

[16] Spucke, A.; Hoste, J.; Versieck, J. Sampling of biological

materials. Nat. Bur. Stand. (U.S.) Spec. Publ. 422; 1976 August,

pp 299-310.

A discussion emphasizing the need to minimize contamination

when sampling and storing clinical materials. Blood

collection is used as an example.

[17] Temple, P. J.; Wills, R. Sampling and analysis of plants and

soils. Methodol . Assess. Air Pollut. Eff. Veg. , Handb. Spec.

Conf. 1978, Paper No. 13, Heck, W. W. ; Krupa, S. V.; Linzon, S. N.,

eds. Pittsburgh: APCA; 1979. 23 p.

A review discussing the collection, preparat

of vegetation and soils for inorganic residu

and particulate air pollutants. Includes 14

preparation, and analysis

'ues of gaseous

40 references.

[18] Zeigler, R. K. ; Matlack, G. M. ; Rein, J. E.; Metz, C. F. Statistically designed program for sampling and chemical analysis of

reactor fuel materials. National Technical Information Service,

LA-DC-12812; Report 1971; 15 p.

Description of a sampling program, "Variables Sampling Plan'

is given. The program is designed to maintain fuel quality

with minimum costs in analysis and fuel production.

24
NBS-IUA IREV. 2-8CI U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO. NBS IN 1153

2. Performing Organ. Report No. 3. Publication Date

January 1982

4. TITLE AND SUBTITLE

A Survey of the Recent Literature on Sampling for Chemical Analysis

5. AUTHOR(S)

Byron G. Kratochvil and John K. Taylor

6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions;

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8. Type of Report & Period Covered

Final

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State, ZIP)

S ame as ab ove

10. SUPPLEMENTARY NOTES

n Document describes a computer program; SF-185, FlPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most si gnificant information. If document includes a si gnifleant bibliography or literature survey, mention it herej

Sampling is one of the most important steps in chemical analysis, yet it is

often poorly planned and executed. One reason is that key information on sampling

is scattered and relatively inaccessible. This article summarizes the more important published articles obtained as the result of a literature search to obtain

essential background information for the design of sampling plans and protocols for

the National Environmental Specimen Bank. Each reference is briefly described so that its applicability to a specific sampling question can be judged. The compilation consists of 56 references on general aspects of sampling, 9 references on sampling agricultural and food products, 14 references on sampling atmospheres and

gases, 18 references on sampling water and waste water, and 18 references on sampling miscellaneous materials.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Chemical analysis; sampling; sampling atmospheres; sampling food; sampling

miscellaneous materials; sampling plan; sampling water.

13. AVAILABILITY

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\~\ Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D C

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(both government and non-government). In general, initial dis- tribution is handled by the sponsor; public distribution is by the National Technical Information Services, Springfield, VA 22161,

in paper copy or microfiche form.
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