ASTM D4597-03(2009)e1
(Practice)Standard Practice for Sampling Workplace Atmospheres to Collect Gases or Vapors with Solid Sorbent Diffusive Samplers
Standard Practice for Sampling Workplace Atmospheres to Collect Gases or Vapors with Solid Sorbent Diffusive Samplers
SIGNIFICANCE AND USE
Regulations such as those promulgated by the U.S. Occupational Safety and Health Administration in 29 CFR 1910.1000 designate that certain hazardous gases and vapors must not be present in the workplace air at concentrations above specific values.
This practice, when used in conjunction with an analytical technique, such as that given for organic compounds in Practice D3687, may provide a means for the determination of time-weighted airborne concentrations of many of the hazardous gases and vapors in applicable regulations (for example, 29CFR 1919.1000,), as well as others.
The manufacturer's literature should be consulted for the appropriate list of chemicals which may be sampled by a particular device.
SCOPE
1.1 This practice covers the sampling of workplace atmospheres for the presence of certain gases or vapors by means of diffusion across a specified quiescent region and subsequent sorption on a solid sorbent (1).
1.2 A list of organic compounds which are applicable to solid sorbent sampling where the sorbent is contained in a bed through which air is passed is given in Annex A1 of Practice D3686. Diffusive samplers may be applicable to a similar range of compounds but this must be confirmed by reference to the individual sampler manufacturers' literature.
1.3 The valid use of diffusive samplers depends on the existence of actual laboratory or field validation, or both. Guidance on validation can be obtained from published protocols (2-6). This practice is not designed to cover the verification, validation, or specific test procedures used to assess the accuracy or precision of diffusive samplers.
1.4 The values stated in SI units shall be regarded as the 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:D4597–03 (Reapproved 2009)
Standard Practice for
Sampling Workplace Atmospheres to Collect Gases or
Vapors with Solid Sorbent Diffusive Samplers
This standard is issued under the fixed designation D4597; 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 (´) indicates an editorial change since the last revision or reapproval.
´ NOTE—Reapproved with editorial changes in October 2009.
1. Scope D3686 Practice for Sampling Atmospheres to Collect Or-
ganic Compound Vapors (Activated Charcoal Tube Ad-
1.1 This practice covers the sampling of workplace atmo-
sorption Method)
spheres for the presence of certain gases or vapors by means of
D3687 Practice for Analysis of Organic Compound Vapors
diffusion across a specified quiescent region and subsequent
Collected by the Activated Charcoal Tube Adsorption
sorption on a solid sorbent (1).
Method
1.2 A list of organic compounds which are applicable to
D6306 Guide for Placement and Use of Diffusion Con-
solid sorbent sampling where the sorbent is contained in a bed
trolled Passive Monitors for Gaseous Pollutants in Indoor
through which air is passed is given in Annex A1 of Practice
Air
D3686. Diffusive samplers may be applicable to a similar
2.2 Other Document:
rangeofcompoundsbutthismustbeconfirmedbyreferenceto
Title 29CFR 1910.1000 Subpart Z Occupational Health and
the individual sampler manufacturers’ literature.
Safety Standard
1.3 The valid use of diffusive samplers depends on the
existence of actual laboratory or field validation, or both.
3. Terminology
Guidance on validation can be obtained from published proto-
3.1 Terminology D1356 contains definitions of terms used
cols (2-6). This practice is not designed to cover the verifica-
in this practice.
tion, validation, or specific test procedures used to assess the
3.2 Definitions of Terms Specific to This Standard:
accuracy or precision of diffusive samplers.
3.2.1 diffusion—the movement of gas or vapor molecules
1.4 The values stated in SI units shall be regarded as the
from a region of high concentration to a region of low
standard.
concentration as described by Fick’s first law (8.1).
1.5 This standard does not purport to address all of the
3.2.2 diffusive sampler—assembly used for sampling gas or
safety concerns, if any, associated with its use. It is the
vapor molecules from the atmosphere.
responsibility of the user of this standard to establish appro-
3.2.3 sampling rate—theratioofmassofagivencompound
priate safety and health practices and determine the applica-
collectedbyadiffusivesamplerperunittimeofexposuretothe
bility of regulatory limitations prior to use.
concentration of that compound in the atmosphere being
2. Referenced Documents sampled. The sampling rate is sometimes referred to as the
uptake rate. Units are ng (or mg)/ mg/m /min (or h), which are
2.1 ASTM Standards:
dimensionally equivalent to a volume flow-rate (for example
D1356 Terminology Relating to Sampling and Analysis of
cm /min).
Atmospheres
4. Summary of Practice
4.1 Molecules (gases and vapors) are sampled from the
This practice is under the jurisdiction ofASTM Committee D22 onAir Quality
and is the direct responsibility of Subcommittee D22.04 on WorkplaceAir Quality.
atmosphere by a diffusive sampler. During the sampling
Current edition approved Oct. 1, 2009. Published December 2009. Originally
process, the molecules diffuse from the environment adjacent
approved in 1987. Last previous edition approved in 2003 as D4597 – 03. DOI:
to the sampler through a region of defined geometric structure
10.1520/D4597-03R09E01.
The boldface numbers in parentheses refer to the list of references at the end of andintoaregioncontainingthesorbentmedium.Thetheoryof
this practice.
diffusive sampling is given in this practice.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Code of Federal Regulations, available from U.S. Government Printing Office,
the ASTM website. Washington, DC 20402.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D4597–03 (2009)
4.2 Instructionsaregivenforthecorrectuseofthesampling substrate and opening at the other to the environment. The
devices to enable their field application. cavity or group of cavities form a region of defined geometry
4.3 Informationonthecalculationofenvironmentalconcen- whichactsasacontrolontherateofgaseousdiffusionfromthe
tration based on sampler assay is given. external environment to the sorbent substrate. Barriers to the
entry of external air movements are common. Samplers where
5. Significance and Use the diffusion of gas or vapor is through materials other than air
are covered by this practice, but it should be noted that the
5.1 Regulations such as those promulgated by the U.S.
influence of temperature on diffusion may be more pro-
Occupational Safety and Health Administration in 29 CFR
nounced.
1910.1000 designate that certain hazardous gases and vapors
7.1.2 Diffusive samplers are equipped with a means of
must not be present in the workplace air at concentrations
attachment to the body for personal sampling or to a suitable
above specific values.
support for area sampling. Samplers are contained in vapor
5.2 This practice, when used in conjunction with an analyti-
impermeable packages or are sealed with vapor impermeable
cal technique, such as that given for organic compounds in
caps both before and after sampling. Labels for unique identi-
Practice D3687, may provide a means for the determination of
fication of a collected sample are required.
time-weighted airborne concentrations of many of the hazard-
ous gases and vapors in applicable regulations (for example,
8. Diffusive Sampling Theory
29CFR 1919.1000,), as well as others.
8.1 Fick’s first law of diffusion states that for a constant
5.3 The manufacturer’s literature should be consulted for
concentration gradient, the mass of material transferred to the
the appropriate list of chemicals which may be sampled by a
sampling layer can be expressed as follows:
particular device.
DA
M 5 ~C 2 C !t (1)
o
L
6. Interferences
6.1 The diffusive sampling process can be jeopardized by
where:
physicalblockageofentrancestotheinteriorofthedevicesuch M = mass of material, ng,
as by liquid droplets or dust particles. D = diffusion co-efficient, cm /min (Note 1),
A = crosssectionalareaofdiffusioncavity(ies),cm (Note
6.2 The diffusive sampling process can be jeopardized by
2),
structural damage to any membranes or other elements used to
L = length of diffusion path, cm (Note 3),
control either the geometry of the diffusion path or turbulence
C = gas phase concentration at face of sampler, ng/cm ,
within the diffusion path.
C = gas phase concentration at sorbent surface, ng/cm ,
o
6.3 The diffusive sampling process can be jeopardized by
and
air movement within the diffusion path. Recent sampler de-
t = exposure time, min.
signs have incorporated elements to decrease this possibility.
6.4 The diffusive sampling process can be jeopardized by
NOTE 1—The diffusion coefficient of a molecule is a function of the
insufficient mixing of the air external to the sampler. This is temperature and the nature of the medium through which it is diffusing.
Shouldthemediumbeacompressiblefluid(forexample,air)thediffusion
known as starvation. The manufacturer should provide a
coefficient will also be a function of the pressure.
recommended minimum ambient air velocity, below which the
NOTE 2—The presence of barriers to the entry of external air move-
sampler should not be used.
ments may alter the effective cross-sectional area of the sampler.
6.5 The diffusive sampling process can be jeopardized if the
NOTE 3—Under certain circumstances the length of the diffusion path
concentration in air at the sorbent interface becomes sufficient
can be significantly extended into the thickness of the sorbent layer during
to significantly alter the diffusion gradient within the diffusion sampling. Certain types of sampler make use of this phenomenon to give
a length of stain read-out. In this situation, the mathematical treatment of
path.This can occur through sorbent saturation, either from the
Fick’s law is more complex than that given here.
presenceofcompetingspecies(whichmayincludewatervapor
8.2 The sampling rate (SR) of a diffusive sampler for a
molecules), or the selection of an inappropriate sorbent mate-
rial for the concentration and time of exposure, or by increased specific gas or vapor may be expressed as follows:
temperature. The manufacturer should provide, or the user
DA M
SR 5 5 (2)
should determine, the range of conditions over which signifi-
L C 2 C !t
~
o
cant bias from sorbent saturation will not occur.
where:
6.6 Errors may arise in estimating exposure using diffusive
SR = sampling rate, cm /min.
samplers in instances in which the concentration of the gas or
where:
vapor being sampled varies significantly over time.
concentration (C, C ) is given in ppm (v/v) the units of SR
6.7 Where multiple gases or vapors are sampled simulta- o
become ng/ppm/min.
neously, care must be exercised to ensure there is no mutual
8.2.1 Sampling rates may be estimated from diffusion coef-
interference in the analytical method chosen.
ficient ratios if the sampling rate of one substance is known:
7. Apparatus SR
SR 5 D (3)
2 2
D
7.1 Diffusive Sampling Devices:
7.1.1 A diffusive sampler consists of a cavity or group of However, where diffusion coefficients are calculated values
cavities containing air and terminated at one end by a sorbent rather than measurements, the potential for error exists in this
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D4597–03 (2009)
procedure.Wherepossible,samplingratesshouldbeconfirmed Ensure the open face of the sampler is facing toward the
by the results of
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