ASTM D6246-02
(Practice)Standard Practice for Evaluating the Performance of Diffusive Samplers
Standard Practice for Evaluating the Performance of Diffusive Samplers
SIGNIFICANCE AND USE
Gas or vapor sampling is often accomplished by actively pumping air through a collection medium such as activated charcoal. Problems associated with a pump–inconvenience, inaccuracy, and expense–are inextricable from this type of sampling. The alternative covered by this practice is to use diffusion for moving the compound of interest onto the collection medium. This approach to sampling is attractive because of the convenience of use and low total monitoring cost.
However, previous studies have found significant problems with the accuracy of some samplers. Therefore, although diffusive samplers may provide a plethora of data, inaccuracies and misuse of diffusive samplers may yet affect research studies. Furthermore, worker protections may be based on faulty assumptions. The aim of this practice is to counter the uncertainties in diffusive sampling through achieving a broadly accepted set of performance tests and acceptance criteria for proving the efficacy of any given diffusive sampler intended for use.
SCOPE
1.1 This practice covers the evaluation of the performance of diffusive samplers of gases and vapors for use over sampling periods from 4 to 12 h and for wind speeds less than 0.5 m/s. Such sampling periods and wind speeds are the most common in the indoor workplace setting. Given a suitable exposure chamber, the practice can be extended to cover sampler use for other sampling periods and conditions. The aim is to provide a concise set of experiments for classifying samplers primarily in accordance with a single sampler accuracy figure. Accuracy is defined (3.2.1) in this standard so as to take into account both imprecision and uncorrected bias. Accuracy estimates refer to conditions of sampler use which are normally expected in a workplace setting. These conditions may be characterized by the temperature, atmospheric pressure, humidity, and ambient wind speed, none of which may be constant or accurately known when the sampler is used in the field. Futhermore, the accuracy accounts for the effects of diffusive loss of analyte on the estimation of time-weighted averages of concentrations which may not be constant in time. Aside from accuracy, the samplers are tested for compliance with the manufacturer's stated limits on capacity, possibly in the presence of interfering compounds.
1.2 This practice is an extension of previous research on diffusive samplers (1-14)² as well as Practices D 4597, D 4598, D 4599, and MDHS 27. An essential advance here is the estimation of sampler accuracy under actual conditions of use. Futhermore, the costs of sampler evaluation are reduced.
1.3 Knowledge gained from similar analytes expedites sampler evaluation. For example, interpolation of data characterizing the sampling of analytes at separated points of a homologous series of compounds is recommended. At present the procedure of (9) is suggested. Following evaluation of a sampler in use at a single homologous series member according to the present practice, higher molecular weight members would receive partial validations considering sampling rate, capacity, analytical recovery, and interferences. The test for diffusive analyte loss can be omitted if the effect is found negligible for a given sampler or analyte series.
1.4 Units of the International System of Units (SI) are used throughout this guide and should be regarded as standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D6246–02
Standard Practice for
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Evaluating the Performance of Diffusive Samplers
This standard is issued under the fixed designation D 6246; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope diffusive analyte loss can be omitted if the effect is found
negligible for a given sampler or analyte series.
1.1 This practice covers the evaluation of the performance
1.4 Units of the International System of Units (SI) are used
ofdiffusivesamplersofgasesandvaporsforuseoversampling
throughout this guide and should be regarded as standard.
periods from 4 to 12 h and for wind speeds less than 0.5 m/s.
1.5 This standard does not purport to address all of the
Such sampling periods and wind speeds are the most common
safety concerns, if any, associated with its use. It is the
in the indoor workplace setting. Given a suitable exposure
responsibility of the user of this standard to establish appro-
chamber, the practice can be extended to cover sampler use for
priate safety and health practices and determine the applica-
other sampling periods and conditions. The aim is to provide a
bility of regulatory limitations prior to use.
concisesetofexperimentsforclassifyingsamplersprimarilyin
accordance with a single sampler accuracy figure.Accuracy is
2. Referenced Documents
defined (3.2.1) in this standard so as to take into account both
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2.1 ASTM Standards:
imprecision and uncorrected bias. Accuracy estimates refer to
D 1356 Terminology Relating to Sampling and Analysis of
conditions of sampler use which are normally expected in a
Atmospheres
workplace setting. These conditions may be characterized by
D 4597 Practice for Sampling Workplace Atmospheres to
the temperature, atmospheric pressure, humidity, and ambient
Collect Organic Gases or Vapor with Activated Charcoal
wind speed, none of which may be constant or accurately
Diffusive Samplers
known when the sampler is used in the field. Futhermore, the
D 4598 Practice for Sampling Workplace Atmospheres to
accuracy accounts for the effects of diffusive loss of analyte on
Collect Gases or Vapor with Liquid Sorbent Diffusional
the estimation of time-weighted averages of concentrations
Samplers
which may not be constant in time. Aside from accuracy, the
D 4599 Practice for Measuring the Concentration of Toxic
samplers are tested for compliance with the manufacturer’s
Gases or Vapors Using Length-of-Stain Dosimeters
stated limits on capacity, possibly in the presence of interfering
2.2 International Standards:
compounds.
CEN EN 838 European Standard, Workplace atmospheres -
1.2 This practice is an extension of previous research on
2 Diffusive samplers for the determination of gases or
diffusivesamplers(1-14) aswellasPracticesD 4597,D 4598,
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vapours - Requirements and test methods
D 4599, and MDHS 27. An essential advance here is the
MDHS 27 Protocol for assessing the performance of a
estimation of sampler accuracy under actual conditions of use.
diffusive sampler, Health and Safety Laboratory, United
Futhermore, the costs of sampler evaluation are reduced.
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Kingdom
1.3 Knowledge gained from similar analytes expedites sam-
MDHS 80 Volatile organic compounds in air, Health and
pler evaluation. For example, interpolation of data character-
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Safety Laboratory, United Kingdom
izing the sampling of analytes at separated points of a
homologous series of compounds is recommended. At present
3. Terminology
the procedure of (9) is suggested. Following evaluation of a
3.1 Definitions:
sampler in use at a single homologous series member accord-
3.1.1 For definitions of terms used in this practice, refer to
ing to the present practice, higher molecular weight members
Terminology D 1356.
would receive partial validations considering sampling rate,
3.2 Definitions of Terms Specific to This Standard:
capacity, analytical recovery, and interferences. The test for
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This practice is under the jurisdiction of ASTM Committee D22 on Sampling For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and Analysis of Atmospheres and is the direct responsibility of Subcommittee contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
D22.04 on Workplace Atmospheres. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved October 10, 2002. Published December 2002. Origi- the ASTM website.
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nally published as D 6246 – 98. Last previous edition D 6246 – 01. Available from CEN Central Secretariat, rue de Stassart 36, B-1050 Brussels,
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The boldface numbers in parentheses refer to the list of references at t
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