ASTM D6832-13(2018)
(Test Method)Standard Test Method for the Determination of Hexavalent Chromium in Workplace Air by Ion Chromatography and Spectrophotometric Measurement Using 1,5-diphenylcarbazide
Standard Test Method for the Determination of Hexavalent Chromium in Workplace Air by Ion Chromatography and Spectrophotometric Measurement Using 1,5-diphenylcarbazide
SIGNIFICANCE AND USE
5.1 Airborne hexavalent chromium is carcinogenic (1-3),4 and analytical methods for the measurement of this species in workplace aerosols are desired. Worker exposure to hexavalent chromium occurs primarily through inhalation (1-3), and this test method provides a means for exposure assessment to this highly toxic species. Analytical results from this procedure can be used for regulatory compliance purposes (4).
SCOPE
1.1 This test method specifies a method for the determination of the time-weighted average mass concentration of hexavalent chromium in workplace air samples.
1.2 This test method is applicable to the personal sampling of the inhalable fraction of airborne particles, as defined in ISO 7708, and to area (static) sampling.
1.3 The sample dissolution procedure specifies separate procedures for soluble and insoluble hexavalent chromium.
1.4 This test method is applicable to the determination of masses of 0.01 μg to 10 μg of hexavalent chromium per sample without dilution.
1.5 The concentration range for hexavalent chromium in air for which this procedure is applicable is approximately 0.1 μg/m3 to 100 μg/m3, assuming 1 m3 of air sample. The range can be extended upwards by appropriate dilution.
1.6 Interconversion of trivalent and hexavalent chromium species may occur during sampling and sample preparation, but these processes are minimized to the extent possible by the sampling and sample preparation procedures employed.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6832 − 13 (Reapproved 2018)
Standard Test Method for
the Determination of Hexavalent Chromium in Workplace Air
by Ion Chromatography and Spectrophotometric
Measurement Using 1,5-diphenylcarbazide
This standard is issued under the fixed designation D6832; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This test method specifies a method for the determina-
tion of the time-weighted average mass concentration of
2. Referenced Documents
hexavalent chromium in workplace air samples.
2.1 ASTM Standards:
1.2 This test method is applicable to the personal sampling
D1193Specification for Reagent Water
of the inhalable fraction of airborne particles, as defined in
D1356Terminology Relating to Sampling and Analysis of
ISO7708, and to area (static) sampling.
Atmospheres
1.3 The sample dissolution procedure specifies separate
D3195Practice for Rotameter Calibration
procedures for soluble and insoluble hexavalent chromium.
D4840Guide for Sample Chain-of-Custody Procedures
E882Guide for Accountability and Quality Control in the
1.4 This test method is applicable to the determination of
Chemical Analysis Laboratory
massesof0.01µgto10µgofhexavalentchromiumpersample
E1370Guide for Air Sampling Strategies for Worker and
without dilution.
Workplace Protection
1.5 The concentration range for hexavalent chromium in air
2.2 ISO Standards:
for which this procedure is applicable is approximately 0.1
3 3 3 ISO648Laboratory Glassware—One-mark Pipets
µg/m to 100 µg/m , assuming 1 m of air sample. The range
ISO 1042 Laboratory Glassware—One-mark Volumetric
can be extended upwards by appropriate dilution.
Flasks
1.6 Interconversion of trivalent and hexavalent chromium
ISO3585Glass Plant, Pipeline and Fittings—Properties of
species may occur during sampling and sample preparation,
Borosilicate Glass 3.3
but these processes are minimized to the extent possible by the
ISO7708Air Quality—Particle Size Definitions for Health-
sampling and sample preparation procedures employed.
related Sampling
1.7 The values stated in SI units are to be regarded as ISO8655Piston and/or Plunger-operated Volumetric Appa-
ratus (6 Parts)
standard. No other units of measurement are included in this
standard.
3. Terminology
1.8 This standard does not purport to address all of the
3.1 Fordefinitionsoftermsusedinthistestmethod,referto
safety concerns, if any, associated with its use. It is the
Terminology D1356.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
4. Summary of Test Method
mine the applicability of regulatory limitations prior to use.
1.9 This international standard was developed in accor-
4.1 A known volume of air is drawn through a filter to
dance with internationally recognized principles on standard-
collect particulate hexavalent chromium. The sampler is de-
ization established in the Decision on Principles for the
signedtocollecttheinhalablefractionofairborneparticles(see
Development of International Standards, Guides and Recom-
ISO7708).
1 2
This test method is under the jurisdiction of ASTM Committee D22 on Air For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Quality and is the direct responsibility of Subcommittee D22.04 on WorkplaceAir contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Quality. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Dec. 1, 2018. Published December 2018. Originally the ASTM website.
ɛ1 3
approved in 2002. Last previous edition approved in 2013 as D6832–13 . DOI: Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
10.1520/D6832-13R18. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6832 − 13 (2018)
4.2 The filter and collected sample are subjected to a occur on filter media (6), and efforts should to taken to
dissolutionprocedureinordertoextracthexavalentchromium. minimize this contribution to sample loss. Oxidation of triva-
The sample dissolution procedure may consist of one (or both) lent chromium to hexavalent species can occur in strong base
of two techniques: one for soluble and one for insoluble and in the presence of air (7), so efforts should be taken to
hexavalent chromium. minimize these contributions to analytical bias. In plating mist
samples and in some welding fume samples, interference from
NOTE 1—If it is desired to measure both soluble as well as total
iron may be problematic (5).
hexavalent chromium, the soluble procedure is used first, and this is
followed by the procedure for insoluble hexavalent chromium com-
pounds. Thus, total Cr[VI] is the sum of soluble and insoluble hexavalent
7. Apparatus
chromium compounds. On the other hand, if it is desired to measure total
7.1 Samplers, designed to collect the inhalable fraction of
hexavalent chromium without first isolating insoluble Cr[VI] compounds,
onlytheprocedureforinsolubleCr[VI]isrequired(thiswilldissolveboth airborne particles, for use when the exposure limits of interest
soluble and insoluble hexavalent chromium compounds).
apply to the inhalable fraction of airborne particles (as defined
in ISO7708).
4.2.1 For dissolution of soluble hexavalent chromium, dis-
tilled water with no heating is used to treat the sample.
NOTE 2—In general, personal samples for collection of the inhalable
Alternatively, a weakly basic ammonium sulfate/ammonium
fraction of airborne particles do not exhibit the same size selective
hydroxide buffer solution with no heating is used to extract characteristics if used for area (static) sampling.
NOTE 3—Consider whether the sample is meant to constitute only that
soluble forms of hexavalent chromium.
material which is collected on filter material, or whether the sample
4.2.2 For dissolution of insoluble hexavalent chromium, a
comprises all particulate that is captured within the sampler (that is, all
basic carbonate buffer solution with heating by a hot plate is
material on the filter, backup pad (if applicable), and on the inside walls
used for sample treatment. Alternatively, an ultrasonic bath is
of the sampler). See Appendix X1 for guidance on handling of wall
used instead of a hot plate. deposits within sampling cassettes.
7.2 Filters, of a diameter suitable for use with the samplers
4.3 Aliquots of sample extracts are subjected to ion chro-
matography in order to separate extracted hexavalent chro- (7.1), with a collection efficiency of not less than 99.5% for
particles with a 0.3-µm diffusion diameter (ISO7708), and
mium from trivalent chromium and other metal cations. An
compatible with the sample preparation and analysis method.
ammonium sulfate/ammonium hydroxide eluent solution is
used as the mobile phase.
NOTE 4—Typical filter diameters for personal sampling are 25 mm and
37 mm.
4.4 Following separation, hexavalent chromium is reacted
with an acidic solution of 1,5-diphenylcarbazide to form a
7.2.1 FiltersshouldnotreactwithCr(VI).Thefollowingare
characteristic violet chromium-diphenylcarbazone complex.
acceptable:
Post-column derivatization is used in order to react hexavalent
7.2.1.1 Polyvinyl Chloride (PVC) Membrane Filters, 5-µm
chromium with 1,5-diphenylcarbazide.
pore size or below.
7.2.1.2 Polyvinyl Fluoride (PVF) Membrane Filters, 5-µm
4.5 The absorbance of the chromium-diphenylcarbazone
pore size or below.
complex is measured at 540 nm using visible spectrophotom-
7.2.1.3 Polytetrafluorinated Ethylene (PTFE) Membrane
etry. Analytical results are obtained by plotting the measured
Filters, 5-µm pore size or below.
absorbance as a function of concentration of the chromium-
7.2.1.4 Glass Fiber Filters, binder-free.
diphenylcarbazone complex.
7.2.1.5 Quartz Fiber Filters.
4.6 The analysis results may be used for the assessment of
7.2.1.6 PVC/Acrylic Copolymer Membrane Filters, 5-µm
workplace exposures to hexavalent chromium in air.
pore size or less.
5. Significance and Use
NOTE 5—Several types of filters have been found to cause reduction of
4 hexavalent chromium (6). Mixed cellulose ester (MCE) filters may cause
5.1 Airborne hexavalent chromium is carcinogenic (1-3),
significant reduction of hexavalent chromium, and are generally unsuit-
and analytical methods for the measurement of this species in
able. Some PVC filters have been reported to cause hexavalent chromium
workplaceaerosolsaredesired.Workerexposuretohexavalent
reduction; this should be investigated prior to choosing PVC filters.
chromium occurs primarily through inhalation (1-3), and this NOTE6—Whensamplingchromicacidmist,thereisanadvantageifthe
oxidizing potential of hexavalent chromium is lowered, for instance by
test method provides a means for exposure assessment to this
impregnating the filter with alkali. For example, this can be accomplished
highlytoxicspecies.Analyticalresultsfromthisprocedurecan
by soaking the filter overnight in 1 M sodium hydroxide, and allowing it
be used for regulatory compliance purposes (4).
to dry. This lessens the tendency of Cr(VI) to react with organic
compoundsinthefiltermaterial,orreducingagentsanddustpresentinthe
6. Reactions
sampled air, or both. Filter materials such as PVC and PTFE can be
unsuitable for alkali treatment since they tend to be hydrophobic and
6.1 Reduction of hexavalent chromium to trivalent species
therefore not easily wetted. PVF and vinyl/acrylic copolymer membrane
can occur in acidic environments, and also in the presence of
filters have been found to be suitable for alkali treatment (5).
organic material or environments having high iron concentra-
7.3 Backup Pads, if necessary for use in the particular
tions in air (5). Reduction of hexavalent chromium can also
sampler employed.
NOTE 7—Cellulose backup pads should not be used for sampling of
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof chromicacidmist,sincedropletscanpenetratethefilterbycapillaryforce,
this test method. resulting in the possibility of Cr(VI) reduction with the backup pad
D6832 − 13 (2018)
material. Glass or quartz fiber backup pads could be used, or a mesh
7.7.4 Ion Chromatograph, having the following compo-
comprised of material that is resistant to chromic acid.
nents:
7.4 Sampling Pumps, with an adjustable flow rate and
NOTE9—Thefollowingcomponentsshouldbecomprised,totheextent
capable of maintaining the selected flow rate (between 1 and 5
possible, of inert materials.
L/min for personal sampling pumps, and between 5 and 400
7.7.4.1 Pump, capable of delivering a constant flow in the
L/minforhigh-volumesamplingpumps)towithin 65%ofthe
range of 1 to 5 mL/min at a pressure of 15 to 150 MPa.
nominal value throughout the sampling period (up to 8–10 h
7.7.4.2 InjectionValve—Alowdead-volumevalve,(1mLor
for personal sampling, or shorter periods for high-volume
less), nonmetallic, that will allow the loading of sample
sampling). For personal sampling the pumps shall be capable
contents into the eluant stream. Sample loops of up to 1 mL
of being worn by the worker without impeding normal work
volume will provide enhanced detection limits.
activity. Sampling pump flow rates shall be set using either a
NOTE 10—Either an autosampler or a manual injection system, or both,
primaryorsecondarystandard;ifasecondarystandardisused,
is (are) acceptable.
it shall be calibrated using a primary standard (see Practice
7.7.4.3 Guard Column—A column placed before the sepa-
D3195).
rator column (7.7.4.4) to protect the separator column from
NOTE 8—Aflow-stabilized pump may be required to maintain the flow
fouling by particles or strongly adsorbed organic constituents.
rate within the specified limits.
7.7.4.4 Separator Column—A column packed with high
7.5 Flowmeter, Portable, capable of measuring the selected
capacity pellicular anion exchange resin that is suitable for
volumetric flow rate to within 62%, and calibrated against a
resolving hexavalent chromium from other metals and cations.
primary standard (that is, a flowmeter whose accuracy is
7.7.4.5 Reagent Delivery Module—A device capable of
traceable to primary standards).
delivering 0 to 2 mL/min of reagent solution against a back
pressure of up to 40 kPa.
7.6 Ancillary Equipment:
7.7.4.6 Mixing Tee and Reaction Coil—Adevice capable of
7.6.1 Flexible Tubing, of a diameter suitable for making a
mixing two flowing streams with minimal band spreading.
leak-proof connection from the sampler to the sampling pump.
7.7.4.7 Detector—A low-volume flow-through visible ab-
7.6.2 Belts or Harnesses, to which the sampling pump can
sorbance detector with a nonmetallic flow path.
be conveniently fixed for personal sampling (except where
7.7.4.8 Recorder, Integrator, or Computer—A device com-
sampling pumps are small enough to fit inside workers’
patible with detector output, capable of recording detector
pockets).
response as a function of time for the purpose of measuring
7.6.3 Flat-Tipped Forceps, plastic or plastic-tipped, for
peak height or area.
loading and unloading filters into or out of samplers.
NOTE 11—The use of an automated system is recommended.
7.6.4 Filter Transport Cassettes, or similar, if required, in
which to transport samples for laboratory analysis.
7.7.5 Eluant Reservior—A container suitable for storing
7.6.5 Disposable Gloves, for sample handling and preven-
eluant solution.
tion of sample contamination.
7.7.6 Syringe Filter, 0.45 µm, for sample filtration prior to
analysis. The filter material shall be chemically inert.
7.7 Analytical or Laboratory Apparatus—Ordinary labora-
7.7.7 Syringe,equippedwithamalefittingandacapacityof
tory apparatus, and:
at least 1 mL; or auto sampler module with like specifications.
7.7.1 Glassware, made of borosilicate glass 3.3 and com-
plying with the requirements of ISO3585.
8. Reagents
7.7.1.1 Beakers, of capacities between 50 mL and 2 L.
8.1 For the analysis of hexavalent chromium, use only
7.7.1.2 Watch Glasses, to fit the beakers.
reagents of recognized analytical grade, and only water as
7.7.1.3 One-Mark Pipets, complying with the requirements
specified in (8.1.1).
of ISO648.
8.1.1 Water, complying with the requirements of ASTM
7.7.1.4 One-Mark
...
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