ASTM D4084-23

Standard Test Method for Analysis of Hydrogen Sulfide in Gaseous Fuels (Lead Acetate Reaction Rate Method)

SIGNIFICANCE AND USE
5.1 This test method is useful in determining the concentration of hydrogen sulfide in gaseous samples and in verifying compliance with operational needs and/or environmental limitations for H2S content. The automated performance operation of this method allows unattended measurement of H2S concentration. The user is referred to Practice D7166 for unattended on-line use of instrumentation based upon the lead acetate reaction rate method.
SCOPE
1.1 This test method covers the determination of hydrogen sulfide (H2S) in gaseous fuels. It is applicable to the measurement of H2S in natural gas, liquefied petroleum gas (LPG), substitute natural gas, landfill gas, sewage treatment off gasses, recycle gas, flare gasses, and mixtures of fuel gases. This method can also be used to measure the hydrogen sulfide concentration in carbon dioxide. Air does not interfere. The applicable range is 0.1 to 16 parts per million by volume (ppm/v) (approximately 0.1 to 22 mg/m3) and may be extended to 100 % H2S by manual or automatic volumetric dilution.  
1.2 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.  
1.3 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: 31-May-2023
• ICS: 75.160.30 - Gaseous fuels
• Technical Committee: D03 - Gaseous Fuels

Relations

• Refers: ASTM D4150-19 - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 15-Dec-2019
• Refers: ASTM D4150-08(2016) - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 01-Jul-2016
• Refers: ASTM D2420-13 - Standard Test Method for Hydrogen Sulfide in Liquefied Petroleum (LP) Gases (Lead Acetate Method)
• Effective Date: 15-Jun-2013
• Refers: ASTM D2420-12a - Standard Test Method for Hydrogen Sulfide in Liquefied Petroleum (LP) Gases (Lead Acetate Method)
• Effective Date: 01-Nov-2012
• Refers: ASTM D2420-12 - Standard Test Method for Hydrogen Sulfide in Liquefied Petroleum (LP) Gases (Lead Acetate Method)
• Effective Date: 15-Aug-2012
• Refers: ASTM D3609-00(2010) - Standard Practice for Calibration Techniques Using Permeation Tubes
• Effective Date: 01-Apr-2010
• Refers: ASTM D1914-95(2010) - Standard Practice for Conversion Units and Factors Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Apr-2010
• Refers: ASTM D7166-10 - Standard Practice for Total Sulfur Analyzer Based On-line/At-line for Sulfur Content of Gaseous Fuels
• Effective Date: 01-Jan-2010
• Refers: ASTM D4150-08 - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 01-Dec-2008
• Refers: ASTM D2420-07 - Standard Test Method for Hydrogen Sulfide in Liquefied Petroleum (LP) Gases (Lead Acetate Method)
• Effective Date: 15-Feb-2007
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D3609-00(2005) - Standard Practice for Calibration Techniques Using Permeation Tubes
• Effective Date: 01-Oct-2005
• Refers: ASTM D7166-05 - Standard Practice for Total Sulfur Analyzer Based On-line/At-line for Sulfur Content of Gaseous Fuels
• Effective Date: 15-Jun-2005
• Refers: ASTM D1914-95(2004)e1 - Standard Practice for Conversion Units and Factors Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Oct-2004
• Refers: ASTM D4150-03 - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 10-Aug-2003

Overview

ASTM D4084-23, titled Standard Test Method for Analysis of Hydrogen Sulfide in Gaseous Fuels (Lead Acetate Reaction Rate Method), establishes procedures for the determination of hydrogen sulfide (H₂S) concentrations in gaseous fuels. Issued by ASTM International, this standard is vital for gas industry stakeholders, regulatory bodies, and analytical laboratories tasked with ensuring operational safety and environmental compliance.

This method applies to natural gas, liquefied petroleum gas (LPG), synthetic and substitute natural gas, landfill gas, sewage treatment off gases, recycle gas, flare gases, and fuel gas mixtures, as well as carbon dioxide. The test method features a lead acetate reaction rate technique, using automated colorimetric analysis for high efficiency and unattended measurement.

Key Topics

• Purpose: Determination of hydrogen sulfide content in gaseous samples, supporting compliance with operational and regulatory H₂S limits.
• Applicability: Suitable for a wide range of gaseous fuels, including natural gas, LPG, landfill and flare gases, and other fuel mixtures. The standard is also effective for measuring H₂S in carbon dioxide.
• Measurement Range: Measures H₂S concentrations from 0.1 to 16 ppm by volume (approximately 0.1 to 22 mg/m³), with possible extension up to 100% H₂S via dilution.
• Lead Acetate Method: Utilizes a lead-acetate-impregnated paper tape; H₂S exposure forms a brown stain, proportional to H₂S level, which is measured by an optical detection system.
• Automated Operation: Compatible with automated analyzers for continuous, unattended H₂S monitoring and reporting.
• Calibration & Quality Control: Emphasizes regular calibration against known standards and strict quality control protocols, referencing ASTM D7166 and D3609 for calibration practices.
• Sample Handling: Stresses prompt and careful sample handling to minimize losses or degradation, with detailed recommendations for container types and sample line materials.

Applications

ASTM D4084-23 has significant practical value in several areas:

• Pipeline and Utility Gas Monitoring: Ensures that flammable gas pipelines and utilities maintain H₂S levels within required safety and environmental thresholds.
• Refineries and Gas Processing Plants: Used to monitor and control H₂S in process streams, helping protect equipment, personnel, and the environment.
• Environmental Compliance: Supports verification of regulatory compliance for emission limits on sulfur compounds from flares, landfill operations, and sewage treatment plants.
• On-line and Routine Monitoring: Automated analyzers based on this method enable continuous monitoring in facilities, reducing manual labor and increasing measurement reliability.
• Instrument Calibration: Provides protocols for calibration using reference gases, ensuring traceability and accuracy necessary for compliance and reporting.

Related Standards

This standard is used in conjunction with several key ASTM documents for comprehensive H₂S measurement and quality assurance:

• ASTM D7166: Practice for Total Sulfur Analyzer Based On-line/At-line for Sulfur Content of Gaseous Fuels
• ASTM D1193: Specification for Reagent Water
• ASTM D1914: Practice for Conversion Units and Factors Relating to Sampling and Analysis of Atmospheres
• ASTM D2420: Test Method for Hydrogen Sulfide in Liquefied Petroleum (LP) Gases (Lead Acetate Method)
• ASTM D3609: Practice for Calibration Techniques Using Permeation Tubes
• ASTM D4150: Terminology Relating to Gaseous Fuels
• ISO 10725: Guidelines for establishing uncertainty budgets in chemical analysis

Keywords: hydrogen sulfide analysis, gaseous fuels testing, lead acetate method, ASTM D4084-23, H₂S in natural gas, fuel gas standards, environmental compliance, gas quality assurance

For further guidance on implementing this standard within your operations, always consult the current version as published by ASTM International.

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: D4084 − 23
Standard Test Method for
Analysis of Hydrogen Sulfide in Gaseous Fuels (Lead
Acetate Reaction Rate Method)
This standard is issued under the fixed designation D4084; 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 D4150 Terminology Relating to Gaseous Fuels
D7166 Practice for Total Sulfur Analyzer Based On-line/At-
1.1 This test method covers the determination of hydrogen
line for Sulfur Content of Gaseous Fuels
sulfide (H S) in gaseous fuels. It is applicable to the measure-
E2165 Practice for Establishing an Uncertainty Budget for
ment of H S in natural gas, liquefied petroleum gas (LPG),
the Chemical Analysis of Metals, Ores, and Related
substitute natural gas, landfill gas, sewage treatment off gasses,
Materials (Withdrawn 2007)
recycle gas, flare gasses, and mixtures of fuel gases. This
method can also be used to measure the hydrogen sulfide
3. Terminology
concentration in carbon dioxide. Air does not interfere. The
3.1 For definitions of general terms used in D03 Gaseous
applicable range is 0.1 to 16 parts per million by volume
(ppm/v) (approximately 0.1 to 22 mg/m ) and may be extended Fuels standards, refer to Terminology D4150.
to 100 % H S by manual or automatic volumetric dilution.
4. Summary of Test Method
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 4.1 Measurement of H S is accomplished by ratiometrically
responsibility of the user of this standard to establish appro-
comparing a reading of an unknown sample with that of a
priate safety, health, and environmental practices and deter- known standard using a differential colorimetric detection.
mine the applicability of regulatory limitations prior to use. Pure H S is used as a primary standard and mixed volumetri-
1.3 This international standard was developed in accor- cally with a sulfur free matrix gas that is ideally similar in
dance with internationally recognized principles on standard- composition to the sample gas. A gaseous sample at constant
ization established in the Decision on Principles for the flow is humidified and passed over lead-acetate-impregnated
Development of International Standards, Guides and Recom- paper. H S reacts with lead acetate to form a brown stain on the
mendations issued by the World Trade Organization Technical
paper. The rate of reaction and resulting rate of color change is
Barriers to Trade (TBT) Committee. proportional to the concentration of H S in the sample. The
analyzer is comprised of an optical system, a photon detection
2. Referenced Documents
system, a signal differentiation system of first order, and a
signal output system. When there is no change in the color of
2.1 ASTM Standards:
the tape, and no resulting change in photodetector output, E,
D1193 Specification for Reagent Water
the first derivative, dE/dt, is zero. This results in an analyzer
D1914 Practice for Conversion Units and Factors Relating to
that automatically zeroes when there is no H S.
Sampling and Analysis of Atmospheres
D2420 Test Method for Hydrogen Sulfide in Liquefied
5. Significance and Use
Petroleum (LP) Gases (Lead Acetate Method)
D3609 Practice for Calibration Techniques Using Perme-
5.1 This test method is useful in determining the concentra-
ation Tubes
tion of hydrogen sulfide in gaseous samples and in verifying
compliance with operational needs and/or environmental limi-
tations for H S content. The automated performance operation
This test method is under the jurisdiction of ASTM Committee D03 on Gaseous
of this method allows unattended measurement of H S con-
Fuels and is the direct responsibility of Subcommittee D03.06.03 on Analysis by
centration. The user is referred to Practice D7166 for unat-
Spectroscopy.
tended on-line use of instrumentation based upon the lead
Current edition approved June 1, 2023. Published June 2023. Originally
approved in 1981. Last previous edition approved in 2017 as D4084 – 07 (2017). acetate reaction rate method.
DOI: 10.1520/D4084-23.
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 last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4084 − 23
6. Apparatus 7.3.1 Hydrogen Sulfide Source—99.5 % by volume purity or
better. An alternative H S source is an H S mixture obtained
2 2
6.1 Volumetric Measuring Devices—A graduated 10-L cyl-
using permeation tube procedures. Hydrogen sulfide generated
inder (see Fig. 1) having a movable piston for volumetrically
from a solid heated to generate H S may be used instead of a
measuring test gas. Gastight syringes of 0.1-mL and 0.5-mL
H S source if desired. H S contained in permeation tubes or
2 2
volume for volumetrically measuring 100 % H S. Gas tight
compressed gas cylinders may be flammable and harmful or
syringes of other volumes can be used. These graduated
fatal if ingested or inhaled. Permeation tubes and compressed
devices are not needed when the permeation tube method of
gas standards should only be handled in well ventilated
dynamic mixing is used to prepare the reference sample since
locations away from sparks and flames. (Warning—Hydrogen
this method will generate a reference mixture.
sulfide is an extremely toxic gas.)
6.2 Sample Pump—A pump capable of providing more than
7.3.2 Dilution Gases—Chemically pure grade or purified
8 mL/s (approximately 1 ft /h) or less than 1 mL/s at 70 kPa
gas. Blend or obtain a sulfur-free gas of the same relative
(approximately 10.15 psig). Gas-wetted parts are ideally con-
density as the sample gas to be analyzed. Blends of gases, of
structed from either aluminum or polytetrafluorethylene
similar composition to the sample gas, are prepared from pure
(PTFE). Stainless steel may be used when higher safety than
gases by mixing, using a 10-L cylinder with piston. Pipeline
afforded by aluminum or PTFE is required.
gas scrubbed through activated charcoal and sodium
6.3 Colorimetric Rate of Reaction Sensor—Select a device
hydroxide-asbestos absorbent is satisfactory.
of sufficient sensitivity to measure a minimum rate of change
7.3.3 Gas Mixtures—Another alternative H S source is a
of color density corresponding to 0.1-ppm H S by volume in
2 certified H S mixture obtained from a gas standard vendor.
the sample gas. (See Fig. 2.)
Such mixtures are in a sulfur free carrier gas that is of the same
type, or a close approximation, as the gas to be analyzed. These
6.4 Recorder, having an adjustable span of 1-V to 10-V full
mixtures can be either a primary standard, which is then diluted
scale with an input impedance of 1 MΩ or higher. A printer or
to the desired H S concentration using a 10-L cylinder with a
other output means, such as a data logger or Distributed
piston, or a standard in a pressurized cylinder containing the
Control System (DCS), can be used.
desired H S concentration. Because of the potential for
7. Reagents and Materials
degradation, H S mixtures obtained from a gas standard
vendor must be properly stored and used only within the stated
7.1 Warning—Hydrogen Sulfide contained in lecture
certification period. In the event of a discrepancy, H S mixtures
bottles, permeation tubes or compressed gas cylinders may be
prepared from a 99.5 % by volume or better purity H S lecture
flammable and harmful or fatal if ingested or inhaled. Lecture 2
bottle or obtained using permeation tube procedures must be
bottles, permeation tubes and compressed gas standards should
used.
only be handled in well ventilated locations away from sparks
and flames. Improper handling of compressed gas cylinders 7.3.3.1 Compressed Gas Standards—The protocol for com-
pressed gas standards contained in the appendix can be used to
containing air, nitrogen or hydrocarbons can result in explo-
sion. Rapid release of nitrogen or hydrocarbon gasses can ensure uniformity in compressed gas standard manufacture and
provide for traceability to a NIST or NMi reference material.
result in asphyxiation. Compressed air supports combustion.
7.3.3.2 Compressed gas standard regulators must be appro-
7.2 Acetic Acid Solution—Add 50 mL of glacial acid
priate for the delivery of sulfur gases and attached fittings must
(CH COOH) to distilled water or dionized water to make 1 L
be passivated or inert to sulfur gases.
of solution (5 %). Type II distilled water as specified in
Specification D1193 is satisfactory for the dilution. Water
7.4 Lead Acetate Sensing Paper—Prepare in accordance
dionized to 1 megaohm-centimeter is also satisfactory for the
with Test Method D2420, using appropriate size strips and
dilution.
drying in an H S-free environment. Commercially available
test paper has been found satisfactory. Used Lead Acetate
7.3 Reference Gas:
Sensing Paper should be disposed of in accordance with local,
state, and/or federal environmental regulations.
7.5 Permeation Devices—Hydrogen Sulfide standards can
be prepared using a permeation tube gravimetrically calibrated
and certified at a convenient operating temperature. At constant
temperature, calibration gases covering a wide range of con-
centration can be generated by varying and accurately measur-
ing the flow rate of diluent gas passing over the tubes. These
calibration gases are used to calibrate the analyzer.
7.5.1 Permeation System Temperature Control—Permeation
devices are maintained at the calibration temperature within
0.1 °C.
7.5.2 Permeation System Flow Control—The permeation
flow system measures diluent gas flow over the permeation
FIG. 1 Calibration Sample Preparation Cylinder with
Movable Piston tubes within 62 %.
D4084 − 23
FIG. 2 Flow System for H S Measurement Showing Calibration, LPG, and Gaseous Sample Connections
7.5.3 Permeation tubes are inspected and weighed to the such as polypropylene or equivalent and silica lined sample
nearest 0.01 mg on at least a monthly basis using a balance containers can also be used for sample collection. Tedlar bags
calibrated against NIST traceable “S” class weights or the containing sample require protection from light and heat. The
equivalent. Analyte concentration is calculated by weight loss
collection of samples that are either in two phases or that will
and dilution gas flow rate as per Practice D3609. These devices form two phases before analysis can be performed must be
are discarded when the liquid contents are reduced to less than
avoided. The presence of liquids causes H S to partition
ten (10) % of the initial volume or when the permeation surface
unequally between the liquid and gas phases. Such a partition
is unusually discolored or otherwise compromised. Used per-
of H S results in inaccurate measurement of H S content.
2 2
meation tubes should be disposed of in accordance with local,
Samples must be analyzed with as little delay as possible and
state, and/or federal environmental regulations.
reported as “proximate analyses from cylinders” with length of
residence time noted. Because of the broad reactivity of H S,
8. Sampling
an extended delay between obtaining the sample and analyzing
8.1 Because of the chemical activity and adsorptive proper- the sample can result in inaccurate results.
ties of H S, it is highly desirable to connect the test apparatus
2 NOTE 1—Each new sample container to be used for a test specimen can
directly to the sample source using minimum lengths of be filled with a sample and analyzed over a period of time and the
resulting data examined to determine the rate of deterioration of the
stainless steel, hastalloy, aluminum or fluorocarbon sample
sample. Repeated filling with a representative sample will tend to
lines. Do not use copper containing, that is, brass or copper
passivate a container. Approximately 10 L (approximately ⁄3 ft ) of
flow system parts. In the event that direct sampling is not
sample, at atmospheric pressure, is convenient for analysis and will
practical, clean aluminum, stainless steel, or fluorocarbon lined
normally not deteriorate appreciably within 1 h. Slow instrument response
sample containers may be used. Tedlar bags with inert fittings to changes in H S concentration indicates the need for a thorough cleaning
D4084 − 23
of the flow system. (See Appendix X1 for a suggested cleaning proce-
11.2 External Calibration—Procedures delineated in 10.1
dure.) Errors caused by ambient temperature and pressure changes are
validate the use of a single-point calibration. At least once a
compensated for by comparison to a reference standard prepared at the
day, analyze the calibration standard and determine standard
time of analysis. Preparation of the reference sample is described in
response factors. Typically, standards are analyzed until three
Section 12.
(3) consecutive trials yield a maximum range consistent with
9. Instrument Preparation
Section 14, Precision.
9.1 Fill a humidifier or humidifying bubbler to the full mark
11.3 Blank Analysis—Confirmation of a lack of significant
with acetic acid solution. The acetic acid minimizes some
carry-over or contamination is recommended and may be
interfering species. Set the range of the analyzer for the range
required for certain applications. This is accomplished through
expected in the sample. Connect the pump and set the
analysis of a blank in a nitrogen, air, or other gas matrix that is
flowmeter for a nominal flow of 8 mL/s (approximately
representative of the sample being analyzed. The significance
1 ft /h). Note: analyte gas can also be delivered to the analyzer
of observed carryover is defined by the users need and should
by use of a compressed gas cylinder or a permeation tube
be determined before performance of this method.
device. Alternative flow settings, such as a nominal 1 mL/s, can
11.4 Sample Analysis—The analysis of each sample in
be used. Obtain a blank reading by flowing dilution gas
duplicate is strongly suggested and may be required for certain
through the analyzer. Record the reading of the blank sample as
applications. Duplicate sample analysis will verify adequate
B in 13.1. Do not adjust the instrument zero until verification
system conditioning and performance.
is obtained, that the room air or the carrier gas does not contain
H S. Verification is accomplished by analyzing a room air or
11.5 Quality Assurance—The following quality assurance
carrier gas sample after it has been passed through an activated
(QA) procedures are suggested and may be required in certain
charcoal filter absorbent.
applications.
11.5.1 Spiked Samples—A spiked sample is analyzed each
10. Calibration
day as part of a QA/QC program. Spikes are prepared by
10.1 Immediately after preparing the calibration standard,
quantitative addition of hydrogen sulfide in a gas to a known
obtain its response on the analyzer. Practice D3609 is accept-
volume of sample gas. An acceptable recovery should match
able as an alternative method for preparation of a reference
the theoretical amounts of H S in the spiked sample within a
standard. Certified compressed gas calibration standards ob-
tolerance consistent with Section 14, Precision, to verify
tained from a gas standard vendor can a
...

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: D4084 − 07 (Reapproved 2017) D4084 − 23
Standard Test Method for
Analysis of Hydrogen Sulfide in Gaseous Fuels (Lead
Acetate Reaction Rate Method)
This standard is issued under the fixed designation D4084; 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 hydrogen sulfide (H S) in gaseous fuels. It is applicable to the measurement of
H S in natural gas, liquefied petroleum gas (LPG), substitute natural gas, landfill gas, sewage treatment off gasses, recycle gas, flare
gasses, and mixtures of fuel gases. This method can also be used to measure the hydrogen sulfide concentration in carbon dioxide.
Air does not interfere. The applicable range is 0.1 to 16 parts per million by volume (ppm/v) (approximately 0.1 to 22 mg/m ) and
may be extended to 100 % H S by manual or automatic volumetric dilution.
1.2 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.
1.3 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.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D1914 Practice for Conversion Units and Factors Relating to Sampling and Analysis of Atmospheres
D2420 Test Method for Hydrogen Sulfide in Liquefied Petroleum (LP) Gases (Lead Acetate Method)
D3609 Practice for Calibration Techniques Using Permeation Tubes
D4150 Terminology Relating to Gaseous Fuels
D7166 Practice for Total Sulfur Analyzer Based On-line/At-line for Sulfur Content of Gaseous Fuels
E2165 Practice for Establishing an Uncertainty Budget for the Chemical Analysis of Metals, Ores, and Related Materials
(Withdrawn 2007)
3. Terminology
3.1 For definitions of general terms used in D03 Gaseous Fuels standards, refer to Terminology D4150.
This test method is under the jurisdiction of ASTM Committee D03 on Gaseous Fuels and is the direct responsibility of Subcommittee D03.05 on Determination of
Special Constituents of Gaseous Fuels.
Current edition approved Nov. 1, 2017June 1, 2023. Published December 2017June 2023. Originally approved in 1981. Last previous edition approved in 20122017 as
D4084 – 07 (2017).(2012). DOI: 10.1520/D4084-07R17.10.1520/D4084-23.
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.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4084 − 23
4. Summary of Test Method
4.1 Measurement of H S is accomplished by ratiometrically comparing a reading of an unknown sample with that of a known
standard using a differential colorimetric detection. Pure H S is used as a primary standard and mixed volumetrically with a sulfur
free matrix gas that is ideally similar in composition to the sample gas. A gaseous sample at constant flow is humidified and passed
over lead-acetate-impregnated paper. H S reacts with lead acetate to form a brown stain on the paper. The rate of reaction and
resulting rate of color change is proportional to the concentration of H S in the sample. The analyzer is comprised of an optical
system, a photon detection system, a signal differentiation system of first order, and a signal output system. When there is no
change in the color of the tape, and no resulting change in photodetector output, E, the first derivative, dE/dt, is zero. This results
in an analyzer that automatically zeroes when there is no H S.
5. Significance and Use
5.1 This test method is useful in determining the concentration of hydrogen sulfide in gaseous samples and in verifying compliance
with operational needs and/or environmental limitations for H S content. The automated performance operation of this method
allows unattended measurement of H S concentration. The user is referred to Practice D7166 for unattended on-line use of
instrumentation based upon the lead acetate reaction rate method.
6. Apparatus
6.1 Volumetric Measuring Devices—A graduated 10-L cylinder (see Fig. 1) having a movable piston for volumetrically measuring
test gas. Gastight syringes of 0.10.1-mL and 0.5-mL volume for volumetrically measuring 100 % H S. Gas tight syringes of other
volumes can be used. These graduated devices are not needed when the permeation tube method of dynamic mixing is used to
prepare the reference sample since this method will generate a reference mixture.
6.2 Sample Pump—A pump capable of providing more than 8 mL/s (approximately 1 ft /h) or less than 1 mL/s at 70 kPa
(approximately 10.15 psig). Gas-wetted parts are ideally constructed from either aluminum or polytetrafluorethylene (PTFE).
Stainless steel may be used when higher safety than afforded by aluminum or PTFE is required.
6.3 Colorimetric Rate of Reaction Sensor—Select a device of sufficient sensitivity to measure a minimum rate of change of color
density corresponding to 0.1-ppm H S by volume in the sample gas. (See Fig. 2.)
6.4 Recorder, having an adjustable span of 11-V to 10-V full scale with an input impedance of 1 MΩ or higher. A printer or other
output means, such as a data logger or Distributed Control System (DCS) , (DCS), can be used.
7. Reagents and Materials
NOTE 1—Warning: Hydrogen Sulfide contained in lecture bottles, permeation tubes or compressed gas cylinders may be flammable and harmful or fatal
if ingested or inhaled. Lecture bottles, permeation tubes and compressed gas standards should only be handled in well ventilated locations away from
sparks and flames. Improper handling of compressed gas cylinders containing air, nitrogen or hydrocarbons can result in explosion. Rapid release of
nitrogen or hydrocarbon gasses can result in asphyxiation. Compressed air supports combustion.
FIG. 1 Calibration Sample Preparation Cylinder with
Movable Piston
D4084 − 23
FIG. 2 Flow System for H S Measurement Showing Calibration, LPG, and Gaseous Sample Connections
7.1 Warning—Hydrogen Sulfide contained in lecture bottles, permeation tubes or compressed gas cylinders may be flammable
and harmful or fatal if ingested or inhaled. Lecture bottles, permeation tubes and compressed gas standards should only be handled
in well ventilated locations away from sparks and flames. Improper handling of compressed gas cylinders containing air, nitrogen
or hydrocarbons can result in explosion. Rapid release of nitrogen or hydrocarbon gasses can result in asphyxiation. Compressed
air supports combustion.
7.2 Acetic Acid Solution—Add 50 mL of glacial acid (CH COOH) to distilled water or dionized water to make 1 L of solution
(5 %). Type II distilled water as specified in Specification D1193 is satisfactory for the dilution. Water dionized to 1
megaohm-centimeter is also satisfactory for the dilution.
7.3 Reference Gas:
7.3.1 Hydrogen Sulfide Source—99.5 % by volume purity or better. An alternative H S source is an H S mixture obtained using
2 2
permeation tube procedures. Hydrogen sulfide generated from a solid heated to generate H S may be used instead of a H S source
2 2
if desired. H S contained in permeation tubes or compressed gas cylinders may be flammable and harmful or fatal if ingested or
inhaled. Permeation tubes and compressed gas standards should only be handled in well ventilated locations away from sparks and
flames. (Warning—Hydrogen sulfide is an extremely toxic gas.)
D4084 − 23
7.3.2 Dilution Gases—Chemically pure grade or purified gas. Blend or obtain a sulfur-free gas of the same relative density as the
sample gas to be analyzed. Blends of gases, of similar composition to the sample gas, are prepared from pure gases by mixing,
using a 10-L cylinder with piston. Pipeline gas scrubbed through activated charcoal and sodium hydroxide-asbestos absorbent is
satisfactory.
7.3.3 Gas Mixtures—Another alternative H S source is a certified H S mixture obtained from a gas standard vendor. Such mixtures
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are in a sulfur free carrier gas that is of the same type, or a close approximation, as the gas to be analyzed. These mixtures can
be either a primary standard, which is then diluted to the desired H S concentration using a 10-L cylinder with a piston, or a
standard in a pressurized cylinder containing the desired H S concentration. Because of the potential for degradation, H S mixtures
2 2
obtained from a gas standard vendor must be properly stored and used only within the stated certification period. In the event of
a discrepancy, H S mixtures prepared from a 99.5 % by volume or better purity H S lecture bottle or obtained using permeation
2 2
tube procedures must be used.
7.3.3.1 Compressed Gas Standards—The protocol for compressed gas standards contained in the appendix can be used to ensure
uniformity in compressed gas standard manufacture and provide for traceability to a NIST or NMi reference material.
7.3.3.2 Compressed gas standard regulators must be appropriate for the delivery of sulfur gases and attached fittings must be
passivated or inert to sulfur gases.
7.4 Lead Acetate Sensing Paper—Prepare in accordance with Test Method D2420, using appropriate size strips and drying in an
H S-free environment. Commercially available test paper has been found satisfactory. Used Lead Acetate Sensing Paper should
be disposed of in accordance with local, state, and/or federal environmental regulations.
7.5 Permeation Devices—Hydrogen Sulfide standards can be prepared using a permeation tube gravimetrically calibrated and
certified at a convenient operating temperature. At constant temperature, calibration gases covering a wide range of concentration
can be generated by varying and accurately measuring the flow rate of diluent gas passing over the tubes. These calibration gases
are used to calibrate the analyzer.
7.5.1 Permeation System Temperature Control—Permeation devices are maintained at the calibration temperature within
0.1°C.0.1 °C.
7.5.2 Permeation System Flow Control—The permeation flow system measures diluent gas flow over the permeation tubes within
62 percent.62 %.
7.5.3 Permeation tubes are inspected and weighed to the nearest 0.01 mg on at least a monthly basis using a balance calibrated
against NIST traceable “S” class weights or the equivalent. Analyte concentration is calculated by weight loss and dilution gas flow
rate as per Practice D3609. These devices are discarded when the liquid contents are reduced to less than ten (10) percent (10) %
of the initial volume or when the permeation surface is unusually discolored or otherwise compromised. Used permeation tubes
should be disposed of in accordance with local, state, and/or federal environmental regulations.
8. Sampling
8.1 Because of the chemical activity and adsorptive properties of H S, it is highly desirable to connect the test apparatus directly
to the sample source using minimum lengths of stainless steel, hastalloy, aluminum or fluorocarbon sample lines. Do not use copper
containing, that is, brass or copper flow system parts. In the event that direct sampling is not practical, clean aluminum, stainless
steel, or fluorocarbon lined sample containers may be used. Tedlar bags with inert fittings such as polypropylene or equivalent and
silica lined sample containers can also be used for sample collection. Tedlar bags containing sample require protection from light
and heat. The collection of samples that are either in two phases or that will form two phases before analysis can be performed
must be avoided. The presence of liquids causes H S to partition unequally between the liquid and gas phases. Such a partition
of H S results in inaccurate measurement of H S content. Samples must be analyzed with as little delay as possible and reported
2 2
as “proximate analyses from cylinders” with length of residence time noted. Because of the broad reactivity of H S, an extended
delay between obtaining the sample and analyzing the sample can result in inaccurate results.
NOTE 1—Each new sample container to be used for a test specimen can be filled with a sample and analyzed over a period of time and the resulting data
examined to determine the rate of deterioration of the sample. Repeated filling with a representative sample will tend to passivate a container.
Approximately 10 L (approximately ⁄3 ft ) of sample, at atmospheric pressure, is convenient for analysis and will normally not deteriorate appreciably
within 1 h. Slow instrument response to changes in H S concentration indicates the need for a thorough cleaning of the flow system. (See Appendix X1
for a suggested cleaning procedure.) Errors caused by ambient temperature and pressure changes are compensated for by comparison to a reference
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standard prepared at the time of analysis. Preparation of the reference sample is described in Section 1112.
9. Instrument Preparation
9.1 Fill a humidifier or humidifying bubbler to the full mark with acetic acid solution. The acetic acid minimizes some interfering
species. Set the range of the analyzer for the range expected in the sample. Connect the pump and set the flowmeter for a nominal
flow of 8 mL/s (approximately 1 ft1 ft /h). Note: analyte gas can also be delivered to the analyzer by use of a compressed gas
cylinder or a permeation tube device. Alternative flow settings, such as a nominal 1 mL/s, can be used. Obtain a blank reading by
flowing dilution gas through the analyzer. Record the reading of the blank sample as B in 12.113.1. Do not adjust the instrument
zero until verification is obtained, that the room air or the carrier gas does not contain H S. Verification is accomplished by
analyzing a room air or carrier gas sample after it has been passed through an activated charcoal filter absorbent.
10. Calibration
10.1 Immediately after preparing the calibration standard, obtain its response on the analyzer. Practice D3609 is acceptable as an
alternative method for preparation of a reference standard. Certified compressed gas calibration standards obtained from a gas
standard vendor can also be used to calibrate the analyzer. The analyzer response is recorded as C in 12.113.1. At least twenty (20)
discrete response replicates should be obtained to adequately demonstrate the statistical repeatability of the analyzer at two times
the standard deviations about the mean. If the analyzer repeatability response fall outside of the published repeatability
specifications then appropriate corrective action must be taken and the repeatability response of the analyzer must be redetermined.
11. Sample Measurement Procedure
11.1 Sampling and Preparation of Samples—Appropriate sampling procedures are critical for meaningful hydrogen sulfide
determinations and must be tailored to the particular sample source.
11.1.1 Samples—Samples are delivered to the laboratory in Tedlar bags with polypropylene fittings or other inert fittings at
atmospheric pressure, protected from heat and light. Samples are normally analyzed within 24 h of sampling to ensure accurate
measurement of hydrogen sulfide in the sample. The holding time can be extended to the li
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