ASTM D5504-20

Standard Test Method for Determination of Sulfur Compounds in Natural Gas and Gaseous Fuels by Gas Chromatography and Chemiluminescence

SIGNIFICANCE AND USE
5.1 Many sources of natural and petroleum gases contain sulfur compounds that are odorous, corrosive, and poisonous to catalysts used in gaseous fuel processing.  
5.2 Low ppm amounts of sulfur odorants are added to natural gas and LP gases for safety purposes. Some odorants are unstable and react to form compounds having lower odor thresholds. Quantitative analysis of these odorized gases ensures that odorant injection equipment is performing to specification.  
5.3 Although not intended for application to gases other than natural gas and related fuels, this test method has been successfully applied to fuel type gases, including refinery, landfill, cogeneration, and sewage digester gas. Refinery, landfill, sewage digester, and other related fuel type gases inherently contain volatile sulfur compounds that are subject to federal, state, or local control. The methane fraction of these fuel type gases is occasionally sold to distributors of natural gas. For these reasons, both regulatory agencies and production and distribution facilities may require the accurate determination of sulfur to satisfy regulatory, production, or distribution requirements. Fuel gases are also used in energy production or are converted to new products using catalysts that are poisoned by excessive sulfur in the feed gas. Industry frequently requires measurement of sulfur in these fuel type gases to protect their catalyst investments.  
5.4 Analytical Methods—Gas chromatography (GC) is commonly used in the determination of fixed gas and organic composition of natural gas (Test Method D1945). Other standard ASTM methods for the analysis of sulfur in fuel gases include Test Methods D1072 and D4468 for total sulfur and Test Methods D4010 and D4884 for hydrogen sulfide.
SCOPE
1.1 This test method is primarily for the determination of speciated volatile sulfur-containing compounds in high methane content gaseous fuels such as natural gas. It has been successfully applied to other types of gaseous samples, including air, digester, landfill, and refinery fuel gas. The detection range for sulfur compounds, reported as picograms sulfur, is 0.01 to 1000. This is equivalent to 0.01 to 1000 mg/m3, based upon the analysis of a 1 cc sample.  
1.2 The range of this test method may be extended to higher concentration by dilution or by selection of a smaller sample loop.
Note 1: Dilution will reduce method precision.  
1.3 This test method does not purport to identify all sulfur species in a sample. Only compounds that are eluted through the selected column under the chromatographic conditions chosen are determined. The detector response to sulfur is equimolar for all sulfur compounds within the scope (1.1) of this test method. Thus, unidentified compounds are determined with equal precision to that of identified substances. Total sulfur content is determined from the total of individually quantified components.  
1.4 Units—The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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-Oct-2020
• ICS: 75.160.01 - Fuels in general
• 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 E594-96(2019) - Standard Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
• Effective Date: 01-Sep-2019
• Refers: ASTM D4150-08(2016) - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 01-Jul-2016
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM D4884-13 - Standard Test Method for Strength of Sewn or Bonded Seams of Geotextiles
• Effective Date: 15-Mar-2013
• Refers: ASTM D1072-06(2012) - Standard Test Method for Total Sulfur in Fuel Gases by Combustion and Barium Chloride Titration
• Effective Date: 01-Nov-2012
• Refers: ASTM D4884-12 - Standard Test Method for Strength of Sewn or Thermally Bonded Seams of Geotextiles
• Effective Date: 01-Jul-2012
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM E594-96(2011) - Standard Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
• Effective Date: 01-Nov-2011
• Refers: ASTM D4468-85(2011) - Standard Test Method for Total Sulfur in Gaseous Fuels by Hydrogenolysis and<br> Rateometric Colorimetry
• Effective Date: 01-Nov-2011
• Refers: ASTM E177-10 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2010
• Refers: ASTM D3609-00(2010) - Standard Practice for Calibration Techniques Using Permeation Tubes
• Effective Date: 01-Apr-2010
• Refers: ASTM D1945-03(2010) - Standard Test Method for Analysis of Natural Gas by Gas Chromatography
• Effective Date: 01-Jan-2010

Overview

ASTM D5504-20 is the standard test method established by ASTM for the determination of sulfur compounds in natural gas and other gaseous fuels. This method utilizes gas chromatography coupled with sulfur chemiluminescence detection. Accurate analysis of sulfur compounds is essential because sulfur is odorous, corrosive, and can poison catalysts in fuel processing. The standard provides a reliable approach for identifying and quantifying speciated volatile sulfur-containing compounds, especially in high methane content gases, but is also applicable to other fuel-type gases and even air samples.

This method is widely used to ensure regulatory compliance, protect catalyst investments, and maintain safety in the supply of natural gas, liquefied petroleum gases (LP gases), and related fuels via quantitative sulfur analysis.

Key Topics

• Purpose and Scope

  • Designed primarily for natural gas and high methane content fuels, with proven application on refinery, landfill, cogeneration, or sewage digester gases.
  • Enables the determination of speciated volatile sulfur compounds in the range of 0.01 to 1000 mg/m³ sulfur, using a 1 cc sample size.

• Analytical Technique

  • Employs gas chromatography (GC) with sulfur chemiluminescence detection (SCD) for high specificity and sensitivity.
  • Detector response is equimolar for all sulfur compounds eluting from the chromatographic column.

• Calibration and Accuracy

  • Utilizes accurate sulfur standards, either from permeation tubes or compressed gas standards, for quantitation and instrument calibration.
  • Ensures system precision and quality through regular calibration, spiked sample analysis, and duplicate sample checks.
  • Provides guidance on sample handling to prevent degradation and improve analytical outcomes.

• Regulatory Compliance

  • Addresses needs driven by federal, state, or local sulfur emission limits in gaseous fuels.
  • Supports industry efforts to comply with quality, environmental, and occupational safety regulations.

Applications

• Natural Gas Quality Monitoring

  • Control and verify sulfur odorant injection levels for safety and specification compliance.
  • Detect both intentionally added odorants and naturally occurring sulfur compounds.

• Fuel Production and Distribution

  • Analyze refinery, landfill, and sewage digester gases sold to natural gas distributors.
  • Ensure that sulfur levels meet contract and regulatory limits before blending or sale.

• Catalyst Protection

  • Quantify volatile sulfur to minimize catalyst poisoning in gas-to-liquid, ammonia, and hydrogen production processes.
  • Ensure feed gas quality for sensitive catalytic processes in the chemical and energy sectors.

• Environmental Control

  • Meet requirements for air quality and sulfur emissions in industrial and municipal energy generation.
  • Monitor landfill and digester gas outputs for regulatory reporting and environmental impact assessments.

Related Standards

• ASTM D1072 - Test Method for Total Sulfur in Fuel Gases
• ASTM D1945 - Analysis of Natural Gas by Gas Chromatography
• ASTM D4468 - Total Sulfur in Gaseous Fuels by Hydrogenolysis and Colorimetry
• ASTM D4010 and D4884 - Methods for measuring hydrogen sulfide in fuel gases
• ASTM D3609 - Calibration techniques using permeation tubes
• ASTM D4150 - Terminology relating to gaseous fuels
• USEPA Method 301 - General procedures for demonstrating method equivalency

This suite of standards complements ASTM D5504-20, providing a broad framework for the comprehensive analysis and regulatory reporting of sulfur in natural gas and related fuels.

---

By implementing ASTM D5504-20, laboratories and industry stakeholders can reliably determine speciated volatile sulfur compounds in natural gas and gaseous fuels, ensuring product quality, operational safety, environmental compliance, and optimal process performance. This standard is a critical tool for anyone involved in fuel supply, energy production, and environmental monitoring.

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: D5504 − 20
Standard Test Method for
Determination of Sulfur Compounds in Natural Gas and
Gaseous Fuels by Gas Chromatography and
Chemiluminescence
This standard is issued under the fixed designation D5504; 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 Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
1.1 This test method is primarily for the determination of
Barriers to Trade (TBT) Committee.
speciated volatile sulfur-containing compounds in high meth-
ane content gaseous fuels such as natural gas. It has been
2. Referenced Documents
successfully applied to other types of gaseous samples, includ-
2.1 ASTM Standards:
ing air, digester, landfill, and refinery fuel gas. The detection
D1072 Test Method for Total Sulfur in Fuel Gases by
range for sulfur compounds, reported as picograms sulfur, is
Combustion and Barium Chloride Titration
0.01 to 1000. This is equivalent to 0.01 to 1000 mg/m , based
D1945 Test Method for Analysis of Natural Gas by Gas
upon the analysis of a 1 cc sample.
Chromatography
1.2 The range of this test method may be extended to higher
D3609 Practice for Calibration Techniques Using Perme-
concentration by dilution or by selection of a smaller sample
ation Tubes
loop.
D4010 Specification for Waterless Hand Cleaner (With-
drawn 2000)
NOTE 1— Dilution will reduce method precision.
D4150 Terminology Relating to Gaseous Fuels
1.3 This test method does not purport to identify all sulfur
D4468 Test Method for Total Sulfur in Gaseous Fuels by
species in a sample. Only compounds that are eluted through
Hydrogenolysis and Rateometric Colorimetry
the selected column under the chromatographic conditions
D4884 Test Method for Strength of Sewn or Bonded Seams
chosen are determined. The detector response to sulfur is
of Geotextiles
equimolar for all sulfur compounds within the scope (1.1) of
E177 Practice for Use of the Terms Precision and Bias in
this test method. Thus, unidentified compounds are determined
ASTM Test Methods
with equal precision to that of identified substances. Total
E594 Practice for Testing Flame Ionization Detectors Used
sulfur content is determined from the total of individually
in Gas or Supercritical Fluid Chromatography
quantified components.
E691 Practice for Conducting an Interlaboratory Study to
1.4 Units—The values stated in SI units are to be regarded
Determine the Precision of a Test Method
as standard. The values given in parentheses after SI units are
provided for information only and are not considered standard.
3. Terminology
1.5 This standard does not purport to address all of the
3.1 For definitions of general terms used in D03 Gaseous
safety concerns, if any, associated with its use. It is the
Fuels standards, refer to Terminology D4150.
responsibility of the user of this standard to establish appro-
4. Summary of Test Method
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
4.1 The analysis of gaseous sulfur compounds is challeng-
1.6 This international standard was developed in accor-
ing due to the reactivity of these substances. They are difficult
dance with internationally recognized principles on standard-
to sample and analyze. Ideally, analysis is performed on-site to
ization established in the Decision on Principles for the
eliminate sample deterioration as a factor in analysis. Sampling
1 2
This test method is under the jurisdiction of ASTM Committee D03 on Gaseous For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Fuels and is the direct responsibility of Subcommittee D03.06.01 on Analysis of contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Major Constituents by Gas Chromatography. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Nov. 1, 2020. Published December 2020. Originally the ASTM website.
approved in 1994. Last previous edition approved in 2012 as D5504 – 12. DOI: The last approved version of this historical standard is referenced on
10.1520/D5504-20. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5504 − 20
must be performed using non-reactive containers, such as tion of sulfur to satisfy regulatory, production, or distribution
4 5
Silcosteel lined vessels, Tedlar bags with polypropylene requirements. Fuel gases are also used in energy production or
fittings, or the equivalent. Tedlar bag samples require protec- are converted to new products using catalysts that are poisoned
tion from light and heat. Laboratory equipment must be inert or by excessive sulfur in the feed gas. Industry frequently requires
passivated to ensure reliable results.
measurement of sulfur in these fuel type gases to protect their
catalyst investments.
4.2 A one cc (mL) sample is injected into a gas chromato-
graph where it is eluted through a megabore, thick film, methyl
5.4 Analytical Methods—Gas chromatography (GC) is com-
silicone liquid phase, open tubular partitioning column or other
monly used in the determination of fixed gas and organic
suitable column, and separated into its individual constituents.
composition of natural gas (Test Method D1945). Other
standard ASTM methods for the analysis of sulfur in fuel gases
4.3 Sulfur Chemiluminescence Detection—As sulfur com-
include Test Methods D1072 and D4468 for total sulfur and
pounds elute from the gas chromatographic column, they are
Test Methods D4010 and D4884 for hydrogen sulfide.
processed in a flame ionization detector (FID) or a heated
combustion zone. The products are collected and transferred to
a sulfur chemiluminescence detector (SCD). This technique 6. Apparatus
provides a sensitive, selective, linear response to volatile sulfur
6.1 Chromatograph—Any gas chromatograph of standard
compounds and may be used while collecting hydrocarbon and
manufacture, with hardware necessary for interfacing to a
fixed gas data from a FID.
chemiluminescence detector and containing all features neces-
4.3.1 Detectors in Series With a SCD—A SCD can fre-
sary for the intended application(s) can be used. Chromato-
quently be used in series with other fixed gas and hydrocarbon
graphic parameters must be capable of obtaining retention time
detectors. However, regulatory bodies may question detector
repeatability of 0.05 min (3 s) throughout the scope of this
compatibility and require demonstration of equivalence be-
analysis.
tween a SCD in a multi-detector system and a SCD operated
6.1.1 Sample Inlet System—A sample inlet system capable
using a FID or combustion zone. The user is referred to USEPA
of operating continuously at the maximum column temperature
Method 301 for an example of a general equivalence proce-
is used. A split/splitless injection system capable of splitless
dure.
operation and split control from 10:1 up to 50:1 may be used
4.3.2 Alternative Detectors—This test method is written for
with capillary columns, or when interferants are encountered.
the sulfur chemiluminescent detector, but other sulfur specific
An automated gas sampling valve is required for many
detectors can be used, provided they have sufficient sensitivity,
applications. The inlet system must be conditioned or con-
respond to all eluted sulfur compounds, do not suffer from
structed of inert material and evaluated frequently for compat-
interferences, and satisfy quality assurance criteria. Regulatory
ibility with trace quantities of reactive sulfur compounds.
agencies may require demonstration of equivalency of alterna-
6.1.2 Carrier and Detector Gas Control—Constant flow
tive detection systems to the SCD.
control of carrier and detector gases is critical for optimum and
5. Significance and Use consistent analytical performance. Control is achieved by use
of pressure regulators and fixed flow restrictors. The gas flow
5.1 Many sources of natural and petroleum gases contain
is measured by appropriate means and adjusted. Mass flow
sulfur compounds that are odorous, corrosive, and poisonous to
controllers, capable of maintaining gas flow constant to 61 %
catalysts used in gaseous fuel processing.
at the flow rates necessary for optimal instrument performance
5.2 Low ppm amounts of sulfur odorants are added to
can be used.
natural gas and LP gases for safety purposes. Some odorants
6.1.3 Detector—Sulfur compounds are processed using a
are unstable and react to form compounds having lower odor
flame ionization detector (FID), a heated combustion zone, or
thresholds. Quantitative analysis of these odorized gases en-
a similar device. The products are collected and delivered to a
sures that odorant injection equipment is performing to speci-
sulfur chemiluminescence detector (SCD).
fication.
6.1.3.1 FID—The detector must meet or exceed the speci-
5.3 Although not intended for application to gases other
fications in Table 1 of Practice E594 while operating within
than natural gas and related fuels, this test method has been
manufacturer’s specifications. The detector must be capable of
successfully applied to fuel type gases, including refinery,
operating at the maximum column temperature. The flow path
landfill, cogeneration, and sewage digester gas. Refinery,
from the injection system through the column to the FID must
landfill, sewage digester, and other related fuel type gases
remain at or above the column temperature throughout the
inherently contain volatile sulfur compounds that are subject to
analysis. The FID must allow for the insertion of a SCD
federal, state, or local control. The methane fraction of these
sampling probe into the flame without compromising the
fuel type gases is occasionally sold to distributors of natural
ability of the FID to detect hydrocarbons. Flow rates of air and
gas. For these reasons, both regulatory agencies and production
hydrogen or, alternatively of oxygen and hydrogen, must be
and distribution facilities may require the accurate determina-
optimized to produce a hydrogen rich flame or combustion
zone that is capable of combusting hydrocarbons. This is
necessary to minimize matrix effects. When performing the
Silcosteel is a trademark of Restek Corporation, 110 Benner Circle, Bellefonte,
simultaneous detection of hydrocarbons is necessary, a FID
PA, 16823.
Tedlar is a trademark of DuPont. and heated combustion zone can be used in series. Zero air is
D5504 − 20
TABLE 1 Example Retention Times Using 4 μ Capillary Column
necessary when performing the simultaneous determination of
A
(30 m × 0.32 mm)
sulfur gases and hydrocarbons.
Conditions as in Table 2
6.1.3.2 SCD—The sulfur chemiluminescence detector shall
Compound Ave. RT min Compound Ave. RT min
meet or exceed the following specifications: (1) greater than
Methane 1.458 ?S 16.363
Ethane 1.730 n-Octane 16.423
10 linearity, (2) less than 5 pg S/s sensitivity, with modern
Ethylene 1.733 ?S 16.425
detectors reaching as low as 0.5 pg S/s, (3) greater than 10
Hydrogen Sulfide 2.053 ?S 16.592
selectivity for sulfur compounds over hydrocarbons, (4) no
Propylene 2.550 ?S 16.692
quenching of sulfur compound response, and (5) no interfer- Carbonyl Sulfide 2.586 ?-EtThiophene 16.983
Propane 2.679 ?S 17.183
ence from co-eluting compounds at the usual GC sampling
Sulfur Dioxide 2.815 ?S 17.319
volumes.
i-Butane 4.422 ?S 17.631
Butene-1 5.263 ?S 17.754
6.1.3.3 Heated Combustion Zone—Sulfur compounds elut-
n-Butane 5.578q m&p-Xylene 17.788
ing from the chromatographic column are processed in a heated
Methanethiol 5.804 ?S 17.913
hydrogen rich combustion zone or a flame ionization detector t-Butene-2 5.938 ?S 18.063
2,2-DMO3 6.009 ?S 18.139
fitted to the end of the column. Products are transferred under
c-Butene-2 6.409 o-Xylene 18.279
reduced pressure to the reaction chamber of a chemilumines-
3-Me-Butene-1 7.463 n-None 18.448
cence detector. An excess of ozone present in the chamber i-Pentane 8.035 ?S 18.450
Pentene-1 8.500 ?S 18.567
reacts with the sulfur combustion product(s) to liberate blue
Ethanethiol 8.583 ?S 18.642
(480 nm) and ultraviolet light (260 nm).
2-Me-Butene-1 8.717 DiEthylDiSulfide 18.767
n-Pentane 8.860 ?S 18.911
6.1.3.4 SCD operation is based on the chemiluminescence
Isoprene 8.983 ?S 19.008
(light emission) produced by the reaction of ozone with an
t-Pentene-2 9.096 ?S 19.125
unidentified sulfur species produced in a combustion zone, Dimethylsulfide 9.117 ?S 19.292
o-Pentene-2 9.321 ?S 19.979
flame ionization detector, or related device. The chemilumi-
2-Me-Butene-2 9.463 2,2,4-TriMeBz 20.227
nescent sulfur species is the subject of on-going research. The
Carbon Disulfide 9.617 n-Decane 20.308
appendix describes two chemiluminescence reaction models. 2,2-DMO4 9.898 ?S 20.550
i-Propanethiol 10.222 ?S 21.396
The sulfur combustion product(s) and an excess of ozone are
Cyclopentene 10.392 ?S 21.733
drawn into a low pressure (<20 Torr) reaction cell. The ozone
3-MePentadiene 10.525 ?S 21.808
reacts to produce blue light (480 nm), oxygen, and other CP/2,3-DMO4 10.733 n-Undecane 22.033
2-MO5 10.883 ?S 22.208
products. A blue sensitive photomultiplier tube detects the
3-MO5 11.269 ?S 23.046
emitted light, which is then amplified for display or output to
t-Butanethiol 11.278 ?S 22.417
a data collection system. Hexene-1 11.392 n-Dodecane 23.631
n-Propanethiol 11.625 Benzothiophene 23.717
6.2 Column—A variety of columns can be used in the n-Hexane 11.720 n-Tridecane 25.134
MethylEthylSulfide 11.779 MeBzThiophene 25.225
determination of sulfur compounds. Typically, a 60 m ×
MeCyC5 12.457 MeBzThiophene 25.328
0.54 mm ID fused silica open tubular column containing a
Benzene 13.154 MeBzThiophene 25.433
s-Butanethiol 13.154 MeBzThiophene 25.550
5 μm film thickness of bonded methyl silicone liquid phase is
A
used. The selected column should provide retention and
The 4 μ column may not have the molecular loading capable of meeting the
detection range as described in the method.
resolution characteristics such as listed in Table 2 and illus-
trated in Fig. 1. The column must be inert towards sulfur
compounds. The column must be inert towards sulfur com-
TABLE 2 Typical Gas Chromatographic Operating Parameters
pounds. The column must also demonstrate a sufficiently low
Injector, gas sample loop: 150 °C 0.5 cc
liquid phase bleed at high temperature such that loss of the
Injector, splitless: 150 °C 100 % sample to
SCD response is not encountered while operating the column at
column
Flame ionization detector (FID): 250 °C
200 °C.
H2: 200 cm /min
Air: 400 cm /min
6.3 Data Acquisition:
Make-up gas (He): 20 cm /min
6.3.1 Recorder—A 0 to 1 mV range recording potentiometer
Or a Heated combustion zone (HCZ): 800 °C
H2: 100 cm /min
or equivalent, with a full-scale response time of 2 s or less can
Air: 40 cm /min
be used.
SCD: output at 0–1 V cell pressure at 6.0 torr
6.3.2 Integrator—An electronic integrating device or com- Column Program: 1.5 min at 30 °C
15.0°/min to 200 °C
puter can be used. A dual channel system is necessary for
hold at 200 °C as required
simultaneous acquisition of both the FID and SCD signals. The
Carrier gas (helium): adjust to methane retention time of 1.10 min
device and software must have the following capabilities: Carrier: 11 cm /min
6.3.2.1 Graphic presentation of the chromatogram.
6.3.2.2 Digital display of chromatographic peak areas.
7. Reagents and Materials
6.3.2.3 Identification of peaks by retention time or relative
NOTE 2—Warning: Sulfur compounds contained in permeation tubes
retention time, or both.
or compressed gas cylinders may be flammable and harmful or fatal if
6.3.2.4 Calculation and use of response factors.
ingested or inhaled. Permeation tubes and compressed gas standards
6.3.2.5 External standard calculation and data presentation. should only be handled in well ventilated locations away from sparks and
D5504 − 20
Hydrogen sulfide (H S)
Carbonyl sulfide (COS)
Methyl mercaptan (CH SH)
7.2.3 The following substances can also be included in a
compressed gas standard.
Ethyl mercaptan (CH CH SH)
3 2
1-propanethiol (CH CH CH SH)
3 2 2
2-propanethiol (CH CHSHCH )
3 3
Dimethyl sulfide (CH SCH )
3 3
7.2.4 The following compounds are not recommended for
inclusion in mixed component standards due to their potential
for promoting degradation.
Carbon disulfide (CS )
FIG. 1 Standard: Perm Tube Analysis Run
Dimethyl disulfide (CH SSCH )
3 3
Other disulfides
7.2.5 All multicomponent compressed gas standards must
flames. Improper handling of compressed gas cylinders containing air,
be re-certified as recommended by the manufacturer or as
nitrogen, or helium can result in explosion. Rapid release of nitrogen or
needed to ensure accuracy.
helium can result in asphyxiation. Compressed air supports combustion.
7.2.6 For the analysis of complex samples, such as refinery
7.1 Sulfur Standards—Accurate sulfur standards are re-
fuel and related fuel type gases, the SCD system must
quired for sulfur gas quantitation. Permeation and compressed
demonstrate the capability of eluting common relatively high
gas standards should be stable, of high purity, and of the
molecular weight volatile sulfur compounds including di-n-
highest available accuracy.
propyl sulfide (propyl sulfide). A retention time standard for
7.1.1 Permeation Devices—Sulfur standards can consist of
demonstrating this capability can be prepared from the com-
permeation tubes, one for each selected sulfur species gravi-
pound (ACS Grade) at approximately 160 ppmv concentration
metrically calibrated and certified at a convenient operating
by addition of a 1 μL aliquot of the liquid to a 10 L Tedlar bag
temperature. With constant temperature, calibration gases cov-
filled with UHP nitrogen or helium.
ering a wide range of concentration can be generated by
7.2.7 Carrier Gas—Helium or nitrogen of high purity. Use
varying and accurately measuring the flow rate of diluent gas
of molecular sieves or other suitable agents to remove water,
passing over the tubes. These calibration gases are used to
oxygen, and hydrocarbons is recommended. Gas pressure must
calibrate the GC/SCD system.
be sufficient to ensure a constant carrier flow rate (see 6.1.2).
7.1.1.1 Permeation System Temperature Control—
7.2.8 Hydrogen—High purity hydrogen is required as fuel
Permeation devices are maintained at the calibration tempera-
for a flame ionization detector, a heated combustion zone, or a
ture within 0.1 °C
similar device.
7.1.1.2 Permeation System Flow Control—The permeation
7.2.9 Air—High purity air is required as oxidant for a flame
flow system measures diluent gas flow over the permeation
ionization detector, a heated combustion zone, or a similar
tubes within 62 %.
device.
7.1.1.3 Permeation tubes are inspected and weighed to the
nearest 0.01 mg on at least a monthly basis using a balance
7.2.10 Oxygen—High purity oxygen supply gas to the SCD
calibrated against NIST traceable “S” class weights or the
ozone generator may be used for maximum detector sensitivity.
equivalent. Analyte concentration is calculated by weight loss
and dilution gas flow rate as per Practice D3609. These devices
8. Equipment Preparation
are discarded when the liquid contents are reduced to less than
8.1 Chromatograph—Place in service in accordance with
ten (10) percent of the initial volume or when the permeation
the manufacturer’s instructions. Many operating conditions can
surface is unusually discolored or otherwise compromised.
be used to perform sulfur gas speciation and quantitation.
7.2 Compressed Gas Standards—Alternatively, blended
Typical, minimal performance criteria for chromatographic
gaseous sulfur standards in nitrogen, helium, or methane base
conditions are:
gas may be used. Care must be exercised in the use of
8.1.1 The conditions must separate all volatile sulfur com-
compressed gas standards since they can introduce errors in
pounds required for calibration.
measurement due to lack of uniformity in their manufacture or
8.1.2 Chromatographic conditions must elute all sulfur
instability in their storage and use. The protocol for com-
species of interest.
pressed gas standards contained in the appendix can be used to
8.1.3 The injection system must transfer, without loss or
ensure uniformity in compressed gas standard manufacture and
absorption, all sulfur compounds of interest to the GC column
provide for traceability to a NIST or NMi reference material.
without reaction between sulfur species or excessive carryover
7.2.1 Compressed gas standard regulators must be appropri-
between samples.
ate for the delivery of sulfur gases and attached fittings must be
passivated or inert to sulfur gases. 8.1.4 The operating conditions presented in Table 1 have
7.2.2 The following sulfur compounds are recommended been successfully used to fulfill the above criteria. Table 1
for inclusion in a compressed gas standard. provides a listing of the retention times of selected sulfur
D5504 − 20
compounds obtained using the parameters in Table 2. Figs. 2
and 3 illustrate typical analyses of a standard mixture and
natural gas.
8.2 SCD—Place in service in accordance with the manufac-
turer’s instructions. FID, heated combustion zone, and mixed
FID/heated combustion zone interface configurations can be
successfully applied to the analysis of sulfur gases in gaseous
samples. For each of these interface configurations, optimiza-
tion of the oxidant/fuel ratio is critical for ensuring complete
combustion of hydrocarbon components in a sample. A flame
or combustion zone that is too hydrogen rich will result in
incomplete combustion and will produce a methane peak
before elution of H S (Fig. 4). Matrix interference is occasion-
FIG. 3 Natural Gas Analysis-Hydrocarbon Compounds
ally observed when changing sample size. Matrix interference
is also indicated by recoveries less than 90 % or greater than
110 % for samples spiked with calibration gas or samples
diluted with air. When matrix interference is indicated, samples
gases. Samples demonstrating high hydrocarbon interference
may be analyzed by dilution or application of other mitigation
can frequently be analyzed using this configuration.
efforts provided a spiked sample performed using the mitiga-
tion procedure results in recoveries within 10 % of theoretical
9. Calibration
results. Operational features specific to the interface configu-
9.1 Sample Introduction—Using passivated or inert
ration employed are described in the following.
equipment, transfer an aliquot of calibration standard to the GC
8.2.1 FID Interface—Placed into service as per the SCD
sample loop. The aliquot must be of sufficient size to com-
manufacturer’s instructions. For this interface, probe place-
pletely flush and fill the sample loop. Generally, a sample size
ment is critical for optimal sensitivity and reproducibility.
10 times the volume of the sample loop and inlet line is
Response that remains the same or decreases with increasing
sufficient. Inject the sample in the sample loop into the GC
sample size indicates questionable interface efficiency (Figs. 5
column and start the chromatographic program. Appropriate
and 6).
analyte concentrations should be selected for calibration.
8.2.2 Flameless Interface or Other Heated Combustion
Zone—Placed into service as per manufacturer’s instructions.
9.2 SCD Calibration—Monthly, or whenever maintenance
The typical flameless/combustion zone interface contains ce- is performed, a three-point calibration curve forced through
ramic tubes in its construction. The performance of these tubes
zero and prepared for each analyte of interest is suggested and
is critical to performance of the SCD system. Compromised may be required for certain applications. Linearity confirma-
ceramic tubes are susceptible to matrix effects. Compromised
tion is consistent with acceptable SCD performance.
tubes may allow for reproducible duplicate sample analysis but
9.2.1 When needed, linearity can be established according
will fail QA procedures such as matrix dilution and spike
to the following procedure. For each concentration of analyte,
analyses. Poorly functioning tubes can also result in severe
the standard is analyzed until three (3) consecutive trials yield
instrument drift, loss of equimolar response, and general
a maximum range of 5 %. The avera
...

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: D5504 − 12 D5504 − 20
Standard Test Method for
Determination of Sulfur Compounds in Natural Gas and
Gaseous Fuels by Gas Chromatography and
Chemiluminescence
This standard is issued under the fixed designation D5504; 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 is primarily for the determination of speciated volatile sulfur-containing compounds in high methane content
gaseous fuels such as natural gas. It has been successfully applied to other types of gaseous samples, including air, digester, landfill,
and refinery fuel gas. The detection range for sulfur compounds, reported as picograms sulfur, is ten (10) to one million (1 000
000). 0.01 to 1000. This is equivalent to 0.01 to 1 000 1000 mg/m , based upon the analysis of a 1 cc sample.
1.2 The range of this test method may be extended to higher concentration by dilution or by selection of a smaller sample loop.
NOTE 1— Dilution will reduce method precision.
1.3 This test method does not purport to identify all sulfur species in a sample. Only compounds that are eluted through the
selected column under the chromatographic conditions chosen are determined. The detector response to sulfur is equimolar for all
sulfur compounds within the scope (1.1) of this test method. Thus, unidentified compounds are determined with equal precision
to that of identified substances. Total sulfur content is determined from the total of individually quantified components.
1.4 Units—The values stated in SI units are to be regarded as standard. The values stated in inch-pound given in parentheses after
SI units are provided for information only.only and are not considered 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.6 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:
D1072 Test Method for Total Sulfur in Fuel Gases by Combustion and Barium Chloride Titration
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 June 1, 2012Nov. 1, 2020. Published November 2012December 2020. Originally approved in 1994. Last previous edition approved in 20082012
as D5504 – 08.D5504 – 12. DOI: 10.1520/D5504-12.10.1520/D5504-20.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5504 − 20
D1945 Test Method for Analysis of Natural Gas by Gas Chromatography
D3609 Practice for Calibration Techniques Using Permeation Tubes
D4010 Specification for Waterless Hand Cleaner (Withdrawn 2000)
D4150 Terminology Relating to Gaseous Fuels
D4468 Test Method for Total Sulfur in Gaseous Fuels by Hydrogenolysis and Rateometric Colorimetry
D4884 Test Method for Strength of Sewn or Bonded Seams of Geotextiles
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E594 Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 For definitions of general terms used in D03 Gaseous Fuels standards, refer to Terminology D4150.
4. Summary of Test Method
4.1 The analysis of gaseous sulfur compounds is challenging due to the reactivity of these substances. They are difficult to sample
and analyze. Ideally, analysis is performed on-site to eliminate sample deterioration as a factor in analysis. Sampling must be
4 5
performed using non-reactive containers, such as Silcosteel lined vessels, Tedlar bags with polypropylene fittings, or the
equivalent. Tedlar bag samples require protection from light and heat. Laboratory equipment must be inert or passivated to ensure
reliable results.
4.2 A one cc (mL) sample is injected into a gas chromatograph where it is eluted through a megabore, thick film, methyl silicone
liquid phase, open tubular partitioning column or other suitable column, and separated into its individual constituents.
4.3 Sulfur Chemiluminescence Detection—As sulfur compounds elute from the gas chromatographic column, they are processed
in a flame ionization detector (FID) or a heated combustion zone. The products are collected and transferred to a sulfur
chemiluminescence detector (SCD). This technique provides a sensitive, selective, linear response to volatile sulfur compounds
and may be used while collecting hydrocarbon and fixed gas data from a FID.
4.3.1 Detectors in Series withWith a SCD—A SCD can frequently be used in series with other fixed gas and hydrocarbon detectors.
However, regulatory bodies may question detector compatibility and require demonstration of equivalence between a SCD in a
multi-detector system and a SCD operated using a FID or combustion zone. The user is referred to USEPA Method 301 for an
example of a general equivalence procedure.
4.3.2 Alternative Detectors—This test method is written for the sulfur chemiluminescent detector, but other sulfur specific
detectors can be used, provided they have sufficient sensitivity, respond to all eluted sulfur compounds, do not suffer from
interferences, and satisfy quality assurance criteria. Regulatory agencies may require demonstration of equivalency of alternative
detection systems to the SCD.
5. Significance and Use
5.1 Many sources of natural and petroleum gases contain sulfur compounds that are odorous, corrosive, and poisonous to catalysts
used in gaseous fuel processing.
5.2 Low ppm amounts of sulfur odorants are added to natural gas and LP gases for safety purposes. Some odorants are unstable
and react to form compounds having lower odor thresholds. Quantitative analysis of these odorized gases ensures that odorant
injection equipment is performing to specification.
5.3 Although not intended for application to gases other than natural gas and related fuels, this test method has been successfully
applied to fuel type gases, including refinery, landfill, cogeneration, and sewage digester gas. Refinery, landfill, sewage digester,
and other related fuel type gases inherently contain volatile sulfur compounds that are subject to federal, state, or local control.
The methane fraction of these fuel type gases areis occasionally sold to distributors of natural gas. For these reasons, both
The last approved version of this historical standard is referenced on www.astm.org.
Silcosteel is a trademark of Restek Corporation, 110 Benner Circle, Bellefonte, PA, 16823.
Tedlar is a trademark of DuPont.
D5504 − 20
regulatory agencies and production and distribution facilities may require the accurate determination of sulfur to satisfy regulatory,
production, or distribution requirements. Fuel gases are also used in energy production or are converted to new products using
catalysts that are poisoned by excessive sulfur in the feed gas. Industry frequently requires measurement of sulfur in these fuel type
gases to protect their catalyst investments.
5.4 Analytical Methods—Gas chromatography (GC) is commonly used in the determination of fixed gas and organic composition
of natural gas (Test Method D1945). Other standard ASTM methods for the analysis of sulfur in fuel gases include Test Methods
D1072 and D4468 for total sulfur and Test Methods D4010 and D4884 for hydrogen sulfide.
6. Apparatus
6.1 Chromatograph—Any gas chromatograph of standard manufacture, with hardware necessary for interfacing to a chemilumi-
nescence detector and containing all features necessary for the intended application(s) can be used. Chromatographic parameters
must be capable of obtaining retention time repeatability of 0.05 min (3 s) 0.05 min (3 s) throughout the scope of this analysis.
6.1.1 Sample Inlet System—A sample inlet system capable of operating continuously at the maximum column temperature is used.
A split/splitless injection system capable of splitless operation and split control from 10:1 up to 50:1 may be used with capillary
columns, or when interferants are encountered. An automated gas sampling valve is required for many applications. The inlet
system must be conditioned or constructed of inert material and evaluated frequently for compatibility with trace quantities of
reactive sulfur compounds.
6.1.2 Carrier and Detector Gas Control—Constant flow control of carrier and detector gases is critical for optimum and consistent
analytical performance. Control is achieved by use of pressure regulators and fixed flow restrictors. The gas flow is measured by
appropriate means and adjusted. Mass flow controllers, capable of maintaining gas flow constant to 61 % at the flow rates
necessary for optimal instrument performance can be used.
6.1.3 Detector—Sulfur compounds are processed using a flame ionization detector (FID), a heated combustion zone, or a similar
device. The products are collected and delivered to a sulfur chemiluminescence detector (SCD).
6.1.3.1 FID—The detector must meet or exceed the specifications in Table 1 of Practice E594 while operating within
manufacturersmanufacturer’s specifications. The detector must be capable of operating at the maximum column temperature. The
flow path from the injection system through the column to the FID must remain at or above the column temperature throughout
the analysis. The FID must allow for the insertion of a SCD sampling probe into the flame without compromising the ability of
the FID to detect hydrocarbons. Flow rates of air and hydrogen or, alternatively of oxygen and hydrogen, must be optimized to
produce a hydrogen rich flame or combustion zone that is capable of combusting hydrocarbons. This is necessary to minimize
matrix effects. When performing the simultaneous detection of hydrocarbons is necessary, a FID and heated combustion zone can
be used in series. Zero air is necessary when performing the simultaneous determination of sulfur gases and hydrocarbons.
6.1.3.2 SCD—The sulfur chemiluminescence detector shall meet or exceed the following specifications: (1) greater than 10
linearity, (2) less than 5 pg S/s sensitivity, with modern detectors reaching as low as 0.5 pg S/s, (3) greater than 10 selectivity for
sulfur compounds over hydrocarbons, (4) no quenching of sulfur compound response, and (5) no interference from co-eluting
compounds at the usual GC sampling volumes.
6.1.3.3 Heated Combustion Zone—Sulfur compounds eluting from the chromatographic column are processed in a heated
hydrogen rich combustion zone or a flame ionization detector fitted to the end of the column. Products are transferred under
reduced pressure to the reaction chamber of a chemiluminescence detector. An excess of ozone present in the chamber reacts with
the sulfur combustion product(s) to liberate blue (480 nm) and ultraviolet light (260 nm).
6.1.3.4 SCD operation is based on the chemiluminescence (light emission) produced by the reaction of ozone with an unidentified
sulfur species produced in a combustion zone, flame ionization detector, or related device. The chemiluminescent sulfur species
is the subject of on-going research. The appendix describes two chemiluminescence reaction models. The sulfur combustion
product(s) and an excess of ozone are drawn into a low pressure (<20 Torr) reaction cell. The ozone reacts to produce blue light
(480 nm), oxygen, and other products. A blue sensitive photomultiplier tube detects the emitted light, which is then amplified for
display or output to a data collection system.
6.2 Column—A variety of columns can be used in the determination of sulfur compounds. Typically, a 60 m × 0.54 mm 0.54 mm
ID fused silica open tubular column containing a 5 μm 5 μm film thickness of bonded methyl silicone liquid phase is used. The
selected column mustshould provide retention and resolution characteristics such as listed in Table 2 and illustrated in Fig. 1. The
D5504 − 20
TABLE 1 Example Retention Times Using 4μ4 μ Capillary Column
A
(30 m × 0.32 mm)
Conditions as in Table 2
Compound Ave. RT min Compound Ave. RT min
Methane 1.458 ?S 16.363
Ethane 1.730 n-Octane 16.423
Ethylene 1.733 ?S 16.425
Hydrogen Sulfide 2.053 ?S 16.592
Propylene 2.550 ?S 16.692
Carbonyl Sulfide 2.586 ?-EtThiophene 16.983
Propane 2.679 ?S 17.183
Sulfur Dioxide 2.815 ?S 17.319
i-Butane 4.422 ?S 17.631
Butene-1 5.263 ?S 17.754
n-Butane 5.578q m&p-Xylene 17.788
Methanethiol 5.804 ?S 17.913
t-Butene-2 5.938 ?S 18.063
2,2-DMO3 6.009 ?S 18.139
c-Butene-2 6.409 o-Xylene 18.279
3-Me-Butene-1 7.463 n-None 18.448
i-Pentane 8.035 ?S 18.450
Pentene-1 8.500 ?S 18.567
Ethanethiol 8.583 ?S 18.642
2-Me-Butene-1 8.717 DiEthylDiSulfide 18.767
n-Pentane 8.860 ?S 18.911
Isoprene 8.983 ?S 19.008
t-Pentene-2 9.096 ?S 19.125
Dimethylsulfide 9.117 ?S 19.292
o-Pentene-2 9.321 ?S 19.979
2-Me-Butene-2 9.463 2,2,4-TriMeBz 20.227
Carbon Disulfide 9.617 n-Decane 20.308
2,2-DMO4 9.898 ?S 20.550
i-Propanethiol 10.222 ?S 21.396
Cyclopentene 10.392 ?S 21.733
3-MePentadiene 10.525 ?S 21.808
CP/2,3-DMO4 10.733 n-Undecane 22.033
2-MO5 10.883 ?S 22.208
3-MO5 11.269 ?S 23.046
t-Butanethiol 11.278 ?S 22.417
Hexene-1 11.392 n-Dodecane 23.631
n-Propanethiol 11.625 Benzothiophene 23.717
n-Hexane 11.720 n-Tridecane 25.134
MethylEthylSulfide 11.779 MeBzThiophene 25.225
MeCyC5 12.457 MeBzThiophene 25.328
Benzene 13.154 MeBzThiophene 25.433
s-Butanethiol 13.154 MeBzThiophene 25.550
A
The 4 μ column may not have the molecular loading capable of meeting the
detection range as described in the method.
TABLE 2 Typical Gas Chromatographic Operating Parameters
Injector, gas sample loop: 150°C 0.5 cc
Injector, gas sample loop: 150 °C 0.5 cc
Injector, splitless: 150°C 100 % sample to
column
Injector, splitless: 150 °C 100 % sample to
column
Flame ionization detector (FID): 250°C
Flame ionization detector (FID): 250 °C
H2: 200 cm /min
Air: 400 cm /min
Make-up gas (He): 20 cm /min
Or a Heated combustion zone (HCZ): 800°C
Or a Heated combustion zone (HCZ): 800 °C
H2: 100 cm /min
Air: 40 cm /min
SCD: output at 0–1 V cell pressure at 6.0 torr
Column Program: 1.5 min at 30°C
Column Program: 1.5 min at 30 °C
15.0°/min to 200°C
15.0°/min to 200 °C
hold at 200°C as required
hold at 200 °C as required
Carrier gas (helium): adjust to methane retention time of 1.10 min
Carrier: 11 cm /min
D5504 − 20
FIG. 1 Standard: Perm Tube Analysis Run
column must be inert towards sulfur compounds. The column must be inert towards sulfur compounds. The column must also
demonstrate a sufficiently low liquid phase bleed at high temperature such that loss of the SCD response is not encountered while
operating the column at 200°C.200 °C.
6.3 Data Acquisition:
6.3.1 Recorder—A 0 to 1 mV range recording potentiometer or equivalent, with a full-scale response time of 2 s or less can be
used.
6.3.2 Integrator—An electronic integrating device or computer can be used. A dual channel system is necessary for simultaneous
acquisition of both the FID and SCD signals. The device and software must have the following capabilities:
6.3.2.1 Graphic presentation of the chromatogram.
6.3.2.2 Digital display of chromatographic peak areas.
6.3.2.3 Identification of peaks by retention time or relative retention time, or both.
6.3.2.4 Calculation and use of response factors.
6.3.2.5 External standard calculation and data presentation.
7. Reagents and Materials
NOTE 2—Warning: Sulfur compounds 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. Improper
handling of compressed gas cylinders containing air, nitrogen, or helium can result in explosion. Rapid release of nitrogen or helium can result in
asphyxiation. Compressed air supports combustion.
7.1 Sulfur Standards—Accurate sulfur standards are required for sulfur gas quantitation. Permeation and compressed gas standards
should be stable, of high purity, and of the highest available accuracy.
7.1.1 Permeation Devices—Sulfur standards can consist of permeation tubes, one for each selected sulfur species gravimetrically
calibrated and certified at a convenient operating temperature. With 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 GC/SCD system.
7.1.1.1 Permeation System Temperature Control—Permeation devices are maintained at the calibration temperature within
0.1°C.0.1 °C
7.1.1.2 Permeation System Flow Control—The permeation flow system measures diluent gas flow over the permeation tubes
within 62 percent.62 %.
7.1.1.3 Permeation tubes are inspected and weighed to the nearest 0.01 mg on at least a monthly basis using a balance calibrated
D5504 − 20
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 of the
initial volume or when the permeation surface is unusually discolored or otherwise compromised.
7.2 Compressed Gas Standards—Alternatively, blended gaseous sulfur standards in nitrogen, helium, or methane base gas may be
used. Care must be exercised in the use of compressed gas standards since they can introduce errors in measurement due to lack
of uniformity in their manufacture or instability in their storage and use. 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.
7.2.1 Compressed gas standard regulators must be appropriate for the delivery of sulfur gases and attached fittings must be
passivated or inert to sulfur gases.
7.2.2 The following sulfur compounds are recommended for inclusion in a compressed gas standard.
Hydrogen sulfide (H S)
Carbonyl sulfide (COS)
Methyl mercaptan (CH SH)
7.2.3 The following substances can also be included in a compressed gas standard.
Ethyl mercaptan (CH CH SH)
3 2
1-propanethiol (CH CH CH SH)
3 2 2
2-propanethiol (CH CHSHCH )
3 3
Dimethyl sulfide (CH SCH )
3 3
7.2.4 The following compounds are not recommended for inclusion in mixed component standards due to their potential for
promoting degradation.
Carbon disulfide (CS )
Dimethyl disulfide (CH SSCH )
3 3
Other disulfides
7.2.5 All multicomponent compressed gas standards must be re-certified as recommended by the manufacturer or as needed to
insureensure accuracy.
7.2.6 For the analysis of complex samples, such as refinery fuel and related fuel type gases, the SCD system must demonstrate
the capability of eluting common relatively high molecular weight volatile sulfur compounds including di-n-propyl sulfide (propyl
sulfide). A retention time standard for demonstrating this capability can be prepared from the compound (ACS Grade) at
approximately 160 ppmv 160 ppmv concentration by addition of a 1 μL 1 μL aliquot of the liquid to a 10 L 10 L Tedlar bag filled
with UHP nitrogen or helium.
7.2.7 Carrier Gas—Helium or nitrogen of high purity. Use of molecular sieves or other suitable agents to remove water, oxygen,
and hydrocarbons is recommended. Gas pressure must be sufficient to ensure a constant carrier flow rate (see 5.1.26.1.2).
7.2.8 Hydrogen—High purity hydrogen is required as fuel for a flame ionization detector, a heated combustion zone, or a similar
device.
7.2.9 Air—High purity air is required as oxidant for a flame ionization detector, a heated combustion zone, or a similar device.
7.2.10 Oxygen—High purity oxygen supply gas to the SCD ozone generator may be used for maximum detector sensitivity.
8. Equipment Preparation
8.1 Chromatograph—Place in service in accordance with the manufacturer’s instructions. Many operating conditions can be used
to perform sulfur gas speciation and quantitation. Typical, minimal performance criteria for chromatographic conditions are:
D5504 − 20
8.1.1 The conditions must separate all volatile sulfur compounds required for calibration.
8.1.2 Chromatographic conditions must elute all sulfur species of interest.
8.1.3 The injection system must transfer, without loss or absorption, all sulfur compounds of interest to the GC column without
reaction between sulfur species or excessive carryover between samples.
8.1.4 The operating conditions presented in Table 1 have been successfully used to fulfill the above criteria. Table 1 provides a
listing of the retention times of selected sulfur compounds obtained using the parameters in Table 2. Figs. 2 and 3 illustrate typical
analyses of a standard mixture and natural gas.
8.2 SCD—Place in service in accordance with the manufacturer’s instructions. FID, heated combustion zone, and mixed
FID/heated combustion zone interface configurations can be successfully applied to the analysis of sulfur gases in gaseous samples.
For each of these interface configurations, optimization of the oxidant/fuel ratio is critical for ensuring complete combustion of
hydrocarbon components in a sample. A flame or combustion zone that is too hydrogen rich will result in incomplete combustion
and will produce a methane peak before elution of H S (Fig. 4). Matrix interference is occasionally observed when changing
sample size. Matrix interference is also indicated by recoveries less than 90 % or greater than 110 % for samples spiked with
calibration gas or samples diluted with air. When matrix interference is indicated, samples may be analyzed by dilution or
application of other mitigation efforts provided a spiked sample performed using the mitigation procedure results in recoveries
within 10 % of theoretical results. Operational features specific to the interface configuration employed are described in the
following.
8.2.1 FID Interface—Placed into service as per the SCD manufacturersmanufacturer’s instructions. For this interface, probe
placement is critical for optimal sensitivity and reproducibility. Response that remains the same or decreases with increasing
sample size,size indicates questionable interface efficiency (Figs. 5 and 6).
8.2.2 Flameless Interface or Other Heated Combustion Zone—Placed into service as per manufacturersmanufacturer’s
instructions. The typical flameless/combustion zone interface contains ceramic tubes in its construction. The performance of these
tubes is critical to performance of the SCD system. Compromised ceramic tubes are susceptible to matrix effects. Compromised
tubes may allow for reproducible duplicate sample analysis but will fail QA procedures such as matrix dilution and spike analyses.
Poorly functioning tubes can also result in severe instrument drift, loss of equimolar response, and general response instability.
Compromised tubes must be replaced to restore nominal instrument function.
8.2.3 Mixed FID Heated Combustion Zone Systems—Combining a FID and a heated combustion zone in series can afford the
simultaneous detection of hydrocarbons and sulfur gases. Samples demonstrating high hydrocarbon interference can frequently be
analyzed using this configuration.
9. Calibration
9.1 Sample Introduction—Using passivated or inert equipment, transfer an aliquot of calibration standard to the GC sample loop.
The aliquot must be of sufficient size to completely flush and fill the sample loop. Generally, a sample size 10 times the volume
FIG. 2 Natural Gas Analysis-Sulfur Compounds
D5504 − 20
FIG. 3 Natural Gas Analysis-Hydrocarbon Compounds
of the sample loop and inlet line is sufficient. Inject the sample in the sample loop into the GC column and start the
chromatographic program. Appropriate analyte concentrations should be selected for calibration.
9.2 SCD Calibration—Monthly, or whenever maintenance is performed, a three-point calibration curve forc
...