ASTM D6494-22

Standard Test Method for Determination of Asphalt Fume Particulate Matter in Workplace Atmospheres as Benzene Soluble Fraction

SIGNIFICANCE AND USE
5.1 Asphalt is a material used in the construction of roads and as a roofing material and sealant.  
5.2 This test method provides a means of evaluating exposure to asphalt fume in the working environment at the presently recommended exposure guidelines (for example, Threshold Limit Values and Biological Exposure Indices, ACGIH).7  
5.3 This procedure has been adapted from NIOSH Method 5023 (withdrawn prior to 4th edition (1994) and replaced in 1998 with NIOSH Method 5042) and OSHA Method 58 to reduce the level of background contamination providing better reproducibility.
SCOPE
1.1 This test method covers the determination of asphalt fume particulate matter (as benzene soluble fraction) and total particulate matter weight in workplace atmospheres using a polytetrafluoroethylene (PTFE) filter methodology.  
1.2 This procedure has been adapted from NIOSH Method 5023 (withdrawn prior to 4th edition (1994) and replaced in 1998 with NIOSH Method 5042) and OSHA Method 58. This adaptation was made to reduce the level of background contamination providing better reproducibility.  
1.3 This procedure is compatible with high flow rate personal sampling equipment–0.5 to 2.0 L/min. It can be used for personal or area monitoring.  
1.4 The sampling method develops a time-weighted average (TWA) sample and can be used to determine short-term exposure limit (STEL).  
1.5 The applicable concentration range for the TWA sample is from 0.2 to 2.0 mg/m3.
Note 1: A study has suggested candidate solvents for benzene replacement.2 A less toxic solvent for this analysis would be more appropriate, although the substitution with a solvent other than benzene needs further validations with field data.  
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.7 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. For more specific precautionary statements, see Section 9.  
1.8 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

• Status: Published
• Publication Date: 28-Feb-2022
• ICS: 13.040.30 - Workplace atmospheres
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.04 - Workplace Air Quality

Relations

• Refers: ASTM D1356-20a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Sep-2020
• Refers: ASTM D1356-20 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Mar-2020
• Refers: ASTM D1357-95(2019) - Standard Practice for Planning the Sampling of the Ambient Atmosphere
• Effective Date: 01-Aug-2019
• Refers: ASTM D6062-19 - Standard Guide for Personal Samplers of Health-Related Aerosol Fractions
• Effective Date: 01-Apr-2019
• Refers: ASTM D4840-99(2018)e1 - Standard Guide for Sample Chain-of-Custody Procedures
• Effective Date: 15-Aug-2018
• Refers: ASTM D1356-15a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Oct-2015
• Refers: ASTM D1356-15 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Jul-2015
• Refers: ASTM D1356-14b - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Dec-2014
• Refers: ASTM D1356-14a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-May-2014
• Refers: ASTM D1356-14 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Jan-2014
• Refers: ASTM D6062-07(2012) - Standard Guide for Personal Samplers of Health-Related Aerosol Fractions
• Effective Date: 01-Apr-2012
• Refers: ASTM D5337-11 - Standard Practice for Flow Rate for Calibration of Personal Sampling Pumps
• Effective Date: 15-Nov-2011
• Refers: ASTM D1357-95(2011) - Standard Practice for Planning the Sampling of the Ambient Atmosphere
• Effective Date: 01-Oct-2011
• Refers: ASTM D1356-05(2010) - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Apr-2010
• Refers: ASTM D4840-99(2010) - Standard Guide for Sampling Chain-of-Custody Procedures
• Effective Date: 01-Feb-2010

Overview

ASTM D6494-22, titled Standard Test Method for Determination of Asphalt Fume Particulate Matter in Workplace Atmospheres as Benzene Soluble Fraction, provides a rigorously defined approach for measuring the concentration of asphalt fume particulate matter in the air at worksites. This method focuses on isolating the benzene soluble fraction (BSF) from airborne particulates, ensuring reliable exposure assessments for workers in environments where asphalt materials are present. Employing a polytetrafluoroethylene (PTFE) filter-based sampling process, the standard supports both area and personal air monitoring. This method aligns with internationally recognized occupational exposure limits, including those established by ACGIH, and builds upon former NIOSH and OSHA methods to improve reproducibility and lower background contamination.

Key Topics

• Air Monitoring and Exposure Assessment: Establishes a robust means for determining worker exposure to hazardous asphalt fumes in occupational environments such as road construction and roofing.
• Sampling Methodology: Specifications for PTFE filter cassettes (2μm pore size), sampling pumps capable of 0.5 to 2.0 L/min flow rates, and chain-of-custody requirements for sample integrity.
• Benzene Soluble Fraction (BSF): Defines the gravimetric procedure for extracting and measuring only the benzene soluble fraction from collected particulate matter, a key indicator linked to occupational health guidelines.
• Time-Weighted Average (TWA) and Short-Term Exposure Limit (STEL): Method generates time-weighted average data, facilitating regulatory compliance over both short- and long-duration exposures in the concentration range from 0.2 to 2.0 mg/m³.
• Precision and Bias: Details on repeatability, accuracy, and quality assurance parameters to ensure defensible monitoring results.
• Safety Considerations: Addresses the proper handling of hazardous reagents like benzene and dichloromethane and stresses the importance of adhering to laboratory safety protocols.

Applications

• Workplace Air Quality Monitoring: Essential for industrial hygienists and safety professionals tasked with monitoring and controlling occupational exposure to asphalt fumes in sectors such as highway construction, paving, and roofing.
• Regulatory Compliance: Supports efforts to meet occupational exposure limits (e.g., ACGIH TLVs and BEIs) and informs hazard assessments required by OSHA and other regulatory agencies.
• Health and Safety Programs: Provides critical data for evaluating the effectiveness of engineering controls, personal protective equipment, and process modifications.
• Laboratory Analysis: Outlines procedures suitable for use in accredited laboratories, compatible with high flow rate personal monitoring equipment, and consistent with ISO/IEC 17025 requirements for testing and calibration laboratories.
• Research and Development: Offers baseline methodology for scientific studies investigating the toxicity, exposure routes, or mitigation of asphalt fumes in various workplace scenarios.

Related Standards

For comprehensive workplace air sampling and analysis, users of ASTM D6494-22 should consider the following related standards:

• ASTM D1356 - Terminology Relating to Sampling and Analysis of Atmospheres
• ASTM D1357 - Practice for Planning the Sampling of the Ambient Atmosphere
• ASTM D4840 - Guide for Sample Chain-of-Custody Procedures
• ASTM D5337 - Practice for Flow Rate Adjustment of Personal Sampling Pumps
• ASTM D6062 - Guide for Personal Samplers of Health-Related Aerosol Fractions
• ASTM D8358 - Guide for Assessing and Including Wall Deposits in Airborne Particulate Matter Analysis
• OSHA Method 58 - Coal Tar Pitch Volatiles
• NIOSH Method 5042 - Benzene Soluble Fraction and Total Particulate (Asphalt Fume)
• ISO/IEC 17025 - General Requirements for the Competence of Testing and Calibration Laboratories

Employing ASTM D6494-22 helps ensure that air quality measurements for asphalt fume particulate matter in workplace atmospheres are scientifically sound, reproducible, and defensible, thereby protecting worker health and supporting regulatory compliance initiatives.

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: D6494 − 22
Standard Test Method for
Determination of Asphalt Fume Particulate Matter in
Workplace Atmospheres as Benzene Soluble Fraction
This standard is issued under the fixed designation D6494; 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.
1. Scope ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
1.1 This test method covers the determination of asphalt
mendations issued by the World Trade Organization Technical
fume particulate matter (as benzene soluble fraction) and total
Barriers to Trade (TBT) Committee.
particulate matter weight in workplace atmospheres using a
polytetrafluoroethylene (PTFE) filter methodology.
2. Referenced Documents
1.2 This procedure has been adapted from NIOSH Method
2.1 ASTM Standards:
5023 (withdrawn prior to 4th edition (1994) and replaced in
D1356 Terminology Relating to Sampling and Analysis of
1998 with NIOSH Method 5042) and OSHA Method 58. This
Atmospheres
adaptation was made to reduce the level of background
D1357 Practice for Planning the Sampling of the Ambient
contamination providing better reproducibility.
Atmosphere
D4840 Guide for Sample Chain-of-Custody Procedures
1.3 This procedure is compatible with high flow rate per-
D5337 Practice for Flow RateAdjustment of Personal Sam-
sonal sampling equipment–0.5 to 2.0 L/min. It can be used for
pling Pumps
personal or area monitoring.
D6062 GuideforPersonalSamplersofHealth-RelatedAero-
1.4 Thesamplingmethoddevelopsatime-weightedaverage
sol Fractions
(TWA) sample and can be used to determine short-term
D8358 GuideforAssessmentandInclusionofWallDeposits
exposure limit (STEL).
in the Analysis of Single-Stage Samplers for Airborne
1.5 The applicable concentration range for the TWAsample
Particulate Matter
is from 0.2 to 2.0 mg/m .
2.2 Occupational Safety and HealthAdministration (OSHA)
NOTE1—Astudyhassuggestedcandidatesolventsforbenzenereplace-
Methods:
ment. A less toxic solvent for this analysis would be more appropriate,
OSHA Method 58 Coal Tar Pitch Volatiles
although the substitution with a solvent other than benzene needs further
2.3 National Institute for Occupational Safety and Health
validations with field data.
(NIOSH) Manual of Analytical Methods:
1.6 The values stated in SI units are to be regarded as
NIOSH Method 5023 Coal Tar Pitch Volatiles
standard. No other units of measurement are included in this
NIOSH Method 5042 Benzene —Soluble Fraction andTotal
standard.
Particulate (Asphalt Fume)
1.7 This standard does not purport to address all of the
2.4 Other Documents:
safety concerns, if any, associated with its use. It is the
ISO/IEC17025 Generalrequirementsforthecompetenceof
responsibility of the user of this standard to establish appro-
testing and calibration laboratories
priate safety, health, and environmental practices and deter-
3. Terminology
mine the applicability of regulatory limitations prior to use.
For more specific precautionary statements, see Section 9.
3.1 Definitions—For definitions of terms relating to this test
1.8 This international standard was developed in accor-
method, refer to Terminology D1356.
dance with internationally recognized principles on standard-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction of ASTM Committee D22 on Air contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Quality and is the direct responsibility of Committee D22.04 on Workplace Air Standards volume information, refer to the standard’s Document Summary page on
Quality. the ASTM website.
Current edition approved March 1, 2022. Published June 2022. Originally Available from Occupational Safety and Health Administration (OSHA), 200
approved in 1999. Last previous edition approved in 2015 as D6494 – 99 (2015). Constitution Ave., NW, Washington, DC 20210, http://www.osha.gov.
DOI: 10.1520/D6494-22. AvailablefromNationalInstituteforOccupationalSafetyandHealth(NIOSH),
Sutter, B., Ravera, C., Hussard, C., Langlois, E., “Alternatives for Benzene in Cincinnati, OH. http://www.cdc.gov
the Extraction of Bitumen Fume from Exposure Sample Media,” Ann. Occup. Hyg., Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
Vol 60, No. 1, 2015, pp. 101–112. 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
D6494 − 22
3.1.1 asphalt fume particulate matter—particulate matter 7.1.1.2 There exists the possibility that sample may enter
generated during the processing of hot asphalt. the sampling cassette and be collected on the inner surfaces of
the sampler rather than on the filter. The use of conductive
4. Summary of Test Method
cassettes rather than polystyrene should reduce the amount of
fine particulate electrostatically attracted to the inner walls of
4.1 A known volume of sample air is passed through a
thecassette,butmaynoteliminatetheissueentirely.SeeGuide
PTFE filter mounted in an appropriate air sampler. Asphalt
D8358 for additional guidance on including non-filter sampler
fumes are removed from the air stream by deposition on the
deposits for analysis.
filter.
7.1.2 Personal Sampling Pumps, portable, battery-operated,
4.2 The asphalt fume is extracted with a known volume of
capable of maintaining a flow rate between 0.5 L⁄min and
benzene. The benzene extract is then evaporated to dryness in
2 L⁄min through the 2 µm PTFE filter for a period of 8 h.
a vacuum oven. The benzene soluble fraction (BSF) is then
7.1.3 Flow Measuring Device, used in accordance with
determined gravimetrically.
Practice D5337.
7.1.4 Flexible Tubing, of a diameter suitable for making a
5. Significance and Use
leak-proofconnectionfromthepersonalsamplingpumpstothe
5.1 Asphalt is a material used in the construction of roads
samplers.
and as a roofing material and sealant.
7.2 Analytical Equipment:
5.2 This test method provides a means of evaluating expo-
7.2.1 Balance, electronic capable of measuring 0.01 mg.
sure to asphalt fume in the working environment at the
7.2.2 Polonium Antistatic Strip.
presently recommended exposure guidelines (for example,
7.2.3 Desiccator.
Threshold Limit Values and Biological Exposure Indices,
7.2.4 Tube Heater Block.
ACGIH).
7.2.5 Concentrator Tubes, 10 mL.
7.2.6 Gas Sparge Manifold, for nitrogen blow down of
5.3 This procedure has been adapted from NIOSH Method
extracts.
5023 (withdrawn prior to 4th edition (1994) and replaced in
7.2.7 Vacuum Oven.
1998 with NIOSH Method 5042) and OSHA Method 58 to
7.2.8 Filtration Unit, containing disposable 0.5 µm PTFE
reduce the level of background contamination providing better
filter and syringe fitting.
reproducibility.
7.2.9 Aluminum Weighing Cups, disposable or reusable
6. Interferences weighing cups capable of holding at least 1 mL of benzene
without leakage.
6.1 All materials (not just asphalt fume) collected that are
soluble in benzene will be included in the benzene soluble
NOTE 3—PTFE may be used if appropriate aluminum cups cannot be
obtained.
fraction weight.
7.2.9.1 If reusable weighing cups are used, appropriate
6.2 Changes in temperature or humidity during pre- and
cleaning procedures must be employed to ensure no cross
post-collection weighing may affect accuracy.
contamination from sample to sample.
7.2.10 Pasteur Pipes, disposable, glass, or equivalent.
7. Apparatus
7.2.11 Miscellaneous Borosilicate Glassware (Pipets,
7.1 Sampling Apparatus:
Syringes, and so forth)—All pipets and syringes shall be
7.1.1 Filter Sampling Cassette—A sampling cassette is a
calibrated Class A volumetric glassware.
two-pieceopaquefiltercassettecontaininga37mmpurePTFE
filter with 2 µm pore size seated upon a 37 mm PTFE spacer
8. Reagents
ring. PTFE filters should be preweighed (see 11.2.2) and the
8.1 Benzene—HPLC grade or equivalent with evaporation
cassette labeled prior to use.Asampler designed to collect the
residue of <0.0005 %.
inhalable fraction of airborne particles (see Guide D6062) can
8.1.1 To determine benzene evaporation residue, perform
be used when the exposure limits apply (for example, ACGIH
the following:
TLV, see 5.2), to the inhalable fraction.
8.1.1.1 Add 6.5 mLof benzene to a concentrator tube, place
7.1.1.1 Toaccuratelydeterminelowlevelsofasphaltfumes,
the tube in the heater block with a gentle flow of nitrogen.
a low background PTFE filter is required. Filter blank values
8.1.1.2 Evaporate the benzene to approximately 0.5 mL,
shouldbecheckedpriortouse.Aminimumofthreefiltersfrom
then transfer the concentrate with 3 small rinses of approxi-
each lot of filters should be analyzed for benzene soluble
mately 0.2, 0.2, and 0.1 mL of benzene using a precleaned
contamination (see 11.2.3) prior to use.
Pasteur pipet to a preweighed weighing boat. Let stand in a
NOTE 2—Only filters with average background contamination below
laboratory fume hood for 1 h.
0.06 mg should be used.
8.1.1.3 Transfer the weighing boat to a vacuum oven. The
vacuum oven should be vented into a fume hood to prevent
release of benzene vapors into the work area.
ACGIH Threshold Limit Values and Biological Exposure Indices, available
8.1.1.4 Allowthesampletofurtherevaporateinthevacuum
from American Conference of Governmental Industrial Hygienists, Inc. (ACGIH),
oven at ambient temperature and 20 mm Hg to 25 mm Hg
1330 Kemper Meadow Dr., Cincinnati, OH 45240, www.acgih.org, updated
annually. vacuumfor24h(oratleastovernight).Slowlyreleasevacuum.
D6494 − 22
Remove weighing boats and reweigh. If the evaporation 11.1.6 Check the pump periodically to ensure that it is still
residue is 0.03 mg or greater, do not use the benzene. running and within acceptable limits.
11.1.7 At the end of the sampling period, determine and
8.2 Dichloromethane—HPLC grade.
record the flow rate, or pump register reading, if appropriate,
turn the pump off, and note and record the time, temperature,
9. Safety Precautions
and barometric pressure.
9.1 Benzene is a known carcinogen and flammable. Dichlo-
NOTE 6—(Minimum recommended sample volume is 15 L.)
romethane is a known animal carcinogen. Dichloromethane
can cause nausea and central nervous system effects. Dermal
11.1.8 Disconnect the sampling device from the sampling
contactcancauseirritationandburns.Handlingofbenzeneand
pump. Plug the inlet and outlet of the filter cassette usin
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6494 − 99 (Reapproved 2015) D6494 − 22
Standard Test Method for
Determination of Asphalt Fume Particulate Matter in
Workplace Atmospheres as Benzene Soluble Fraction
This standard is issued under the fixed designation D6494; 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.
1. Scope
1.1 This test method covers the determination of asphalt fume particulate matter (as benzene soluble fraction) and total particulate
matter weight in workplace atmospheres using a polytetrafluoroethylene (PTFE) filter methodology.
1.2 This procedure has been adapted from NIOSH Method 5023 (withdrawn prior to 4th edition (1994) and replaced in 1998 with
NIOSH Method 5042) and OSHA Method 58 58. This adaptation was made to reduce the level of background contamination
providing better reproducibility.
1.3 This procedure is compatible with high flow rate personal sampling equipment–0.5 to 2.0 L/min. It can be used for personal
or area monitoring.
1.4 The sampling method develops a time-weighted average (TWA) sample and can be used to determine short-term exposure
limit (STEL).
1.5 The applicable concentration range for the TWA sample is from 0.2 to 2.0 mg/m .
NOTE 1—A study has suggested candidate solvents for benzene replacement. A less toxic solvent for this analysis would be more appropriate, although
the substitution with a solvent other than benzene needs further validations with field data.
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.7 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. For more specific precautionary statements, see Section 9.
1.8 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.
This test method is under the jurisdiction of ASTM Committee D22 on Air Quality and is the direct responsibility of Committee D22.04 on Workplace Air Quality.
Current edition approved Oct. 1, 2015March 1, 2022. Published October 2015June 2022. Originally approved in 1999. Last previous edition approved in 20102015 as
D6494 – 99 (2010).(2015). DOI: 10.1520/D6494-99R15.10.1520/D6494-22.
Sutter, B., Ravera, C., Hussard, C., Langlois, E., “Alternatives for Benzene in the Extraction of Bitumen Fume from Exposure Sample Media,” Ann. Occup. Hyg., Vol
60, No. 1, 2015, pp. 101–112.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6494 − 22
2. Referenced Documents
2.1 ASTM Standards:
D1356 Terminology Relating to Sampling and Analysis of Atmospheres
D1357 Practice for Planning the Sampling of the Ambient Atmosphere
D4840 Guide for Sample Chain-of-Custody Procedures
D5337 Practice for Flow Rate Adjustment of Personal Sampling Pumps
D6062 Guide for Personal Samplers of Health-Related Aerosol Fractions
D8358 Guide for Assessment and Inclusion of Wall Deposits in the Analysis of Single-Stage Samplers for Airborne Particulate
Matter
2.2 Occupational Safety and Health Administration (OSHA) Methods:
OSHA Method 58 Coal Tar Pitch Volatiles
2.3 National Institute for Occupational Safety and Health (NIOSH) Manual of Analytical Methods:
NIOSH Method 5023 Coal Tar Pitch Volatiles
NIOSH Method 5042 Benzene —Soluble Fraction and Total Particulate (Asphalt Fume)
2.4 Other Documents:
ISO/IEC 17025 General requirements for the competence of testing and calibration laboratories
3. Terminology
3.1 Definitions—For definitions of terms relating to this test method, refer to Terminology D1356.
3.1.1 asphalt fume particulate matter—particulate matter generated during the processing of hot asphalt.
4. Summary of Test Method
4.1 A known volume of sample air is passed through a PTFE filter. filter mounted in an appropriate air sampler. Asphalt fumes
are removed from the air stream by deposition on the filter.
4.2 The asphalt fume is extracted with a known volume of benzene. The benzene extract is then evaporated to dryness in a vacuum
oven. The benzene soluble fraction (BSF) is then determined gravimetrically.
5. Significance and Use
5.1 Asphalt is a material used in the construction of roads and as a roofing material and sealant.
5.2 This test method provides a means of evaluating exposure to asphalt fume in the working environment at the presently
recommended exposure guidelines.guidelines (for example, Threshold Limit Values and Biological Exposure Indices, ACGIH).
5.2.1 The threshold limit value (TLV) for asphalt (petroleum) fumes is 5 mg/m 8-h TWA, (1998 Threshold Limit Values and
Biological Exposure Indices, ACGIH ).
5.3 This procedure has been adapted from NIOSH Method 5023 (withdrawn prior to 4th edition (1994) and replaced in 1998 with
NIOSH Method 5042) and OSHA Method 58 to reduce the level of background contamination providing better reproducibility.
6. Interferences
6.1 All materials (not just asphalt fume) collected that are soluble in benzene will be included in the benzene soluble fraction
weight.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from Occupational Safety and Health Administration (OSHA), 200 Constitution Ave., NW, Washington, DC 20210, http://www.osha.gov.
Available from National Institute for Occupational Safety and Health (NIOSH), Cincinnati, OH. http://www.cdc.gov
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available ACGIH Threshold Limit Values and Biological Exposure Indices, available from American Conference of Governmental Industrial Hygienists, Inc. (ACGIH),
1330 Kemper Meadow Dr., Cincinnati, OH 45240, http://www.acgih.org.www.acgih.org, updated annually.
D6494 − 22
6.2 Changes in temperature or humidity during pre- and post-collection weighing may affect accuracy.
7. Apparatus
7.1 Sampling Apparatus:
7.1.1 Filter Sampling Cassette—A sampling cassette is a two-piece opaque filter cassette containing a 37 mm pure PTFE filter with
2 μm pore size seated upon a 37 mm PTFE spacer ring. PTFE filters should be preweighed (see 11.2.2) and the cassette labeled
prior to use. A sampler designed to collect the inhalable fraction of airborne particles (see Guide D6062) can be used when the
exposure limits apply (for example, ACGIH TLV, see 5.2), to the inhalable fraction.
7.1.1.1 To accurately determine low levels of asphalt fumes, a low background PTFE filter is required. Filter blank values should
be checked prior to use. A minimum of three filters from each lot of filters should be analyzed for benzene soluble contamination
(see 11.2.3) prior to use.
NOTE 2—Only filters with average background contamination below 0.06 mg should be used.
7.1.1.2 There exists the possibility that sample may enter the sampling cassette and be collected on the inner surfaces of the
sampler rather than on the filter. The use of conductive cassettes rather than polystyrene should reduce the amount of fine
particulate electrostatically attracted to the inner walls of the cassette, but may not eliminate the issue entirely. See Guide D8358
for additional guidance on including non-filter sampler deposits for analysis.
7.1.2 Personal Sampling Pumps, portable, battery-operated, equipped with a flow-monitoring device (rotameter, critical orifice)
or a constant-flow device and capable of drawing 2 L/min of air capable of maintaining a flow rate between 0.5 L ⁄min and 2 L ⁄min
through the 2-μm2 μm PTFE filter for a period of 8 h.
7.1.3 Flow Measuring Device, used in accordance with Practice D5337.
7.1.4 Flexible Tubing, of a diameter suitable for making a leak-proof connection from the personal sampling pumps to the
samplers.
7.2 Analytical Equipment:
7.2.1 Balance, electronic capable of measuring 0.01 mg.
7.2.2 Polonium Antistatic Strip.
7.2.3 Desiccator.
7.2.4 Tube Heater Block.
7.2.5 Concentrator Tubes, 10 mL.
7.2.6 Gas Sparge Manifold, for nitrogen blow down of extracts.
7.2.7 Vacuum Oven.
7.2.8 Filtration Unit, containing disposable 0.5 μm PTFE filter and syringe fitting.
7.2.9 Aluminum Weighing Cups, disposable or reusable weighing cups capable of holding at least 1 mL of benzene without
leakage.
NOTE 3—PTFE may be used if appropriate aluminum cups cannot be obtained.
7.2.9.1 If reusable weighing cups are used, appropriate cleaning procedures must be employed to ensure no cross contamination
from sample to sample.
D6494 − 22
7.2.10 Pasteur Pipes, disposable, glass, or equivalent.
7.2.11 Miscellaneous Borosilicate Glassware (Pipets, Syringes, and so forth)—All pipets and syringes shall be calibrated Class
A volumetric glassware.
8. Reagents
8.1 Benzene—HPLC grade or equivalent with evaporation residue of <0.0005 %.
NOTE 3—Benzene evaporation residue should be checked by evaporating 6.5 mL of benzene (see 8.1.1). Benzene with evaporation residue of greater than
0.03 mg for the 6.5 mL is unacceptable.
8.1.1 Add the benzene to a concentrator tube, place the tube in the heater block with a gentle flow of nitrogen. Evaporate the
benzene to approximately 0.5 mL, then transfer the concentrate with 3 small rinses of approximately 0.2, 0.2, and 0.1 mL of
benzene using a precleaned Pasteur pipet to a preweighed weighing boat. Let stand in a laboratory fume hood for 1 h. Transfer
the weighing boat to a vacuum oven. Allow the sample to further evaporate in the vacuum oven at ambient temperature and 20
to 25 mm Hg vacuum for 24 h (or at least overnight). Slowly release vacuum. Remove weighing boats and reweigh. To determine
benzene evaporation residue, perform the following:The vacuum oven should be vented into a fume hood to prevent release of
benzene vapors into the work area.
8.1.1.1 Add 6.5 mL of benzene to a concentrator tube, place the tube in the heater block with a gentle flow of nitrogen.
8.1.1.2 Evaporate the benzene to approximately 0.5 mL, then transfer the concentrate with 3 small rinses of approximately 0.2,
0.2, and 0.1 mL of benzene using a precleaned Pasteur pipet to a preweighed weighing boat. Let stand in a laboratory fume hood
for 1 h.
8.1.1.3 Transfer the weighing boat to a vacuum oven. The vacuum oven should be vented into a fume hood to prevent release of
benzene vapors into the work area.
8.1.1.4 Allow the sample to further evaporate in the vacuum oven at ambient temperature and 20 mm Hg to 25 mm Hg vacuum
for 24 h (or at least overnight). Slowly release vacuum. Remove weighing boats and reweigh. If the evaporation residue is 0.03 mg
or greater, do not use the benzene.
8.2 Dichloromethane—HPLC grade.
9. Safety Precautions
9.1 Benzene is a known carcinogen and flammable. Dichloromethane is a known animal carcinogen. Dichloromethane can cause
nausea and central nervous system effects. Dermal contact can cause irritation and burns. Handling of benzene and methylene
chloride dichloromethane solutions should be done in an app
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