ASTM D7675-22

Standard Test Method for Determination of Total Hydrocarbons in Hydrogen by FID-Based Total Hydrocarbon (THC) Analyzer

SIGNIFICANCE AND USE
5.1 Low operating temperature fuel cells such as proton exchange membrane fuel cells (PEM-FC) require high purity hydrogen for maximum material performance and lifetime. Analysis to 0.1 part per million (ppm(v)) concentration of THCs (measured as CH4) in hydrogen is necessary for ensuring a feed gas of sufficient purity to satisfy fuel cell system needs as defined in SAE J2719 or as specified in regulatory codes.  
5.2 Dynamic dilution techniques using highly accurate mass flow controllers can be used with test samples that have THC content exceeding the upper limit of the instrument’s linear range, without the need to recalibrate the instrument using higher levels of calibration standards. The sample can be diluted with a high purity grade of hydrogen (99.999 %, so long as it contains  
5.3 Although not intended for application to gases other than hydrogen, techniques within this test method can be applied to other non-hydrocarbon gas samples requiring THC content determination. This can be achieved by using a zero gas and a calibration gas that consist of the same background gas as the actual sample. As an example, for the THC determination of nitrogen, the instrument zero point must be determined with a high purity grade of nitrogen (99.999 % and 4 in nitrogen in the appropriate range. This will correct for any interferences caused by the background gas.
SCOPE
1.1 This test method describes a procedure for total hydrocarbons (THC’s) measurement in hydrogen intended as a fuel on a methane (C1) basis. The determination of THC on a C1 basis is an analytical technique where all the hydrocarbons are assumed to have the same response as methane (CH4). Sensitivity from 0.1 parts per million by volume (ppm(v), µmol/mol) up to 1000 ppm(v) concentration is achievable. Higher concentrations can be analyzed using appropriate dilution techniques. This test method can be applied to other gaseous samples requiring analysis of trace constituents provided an assessment of potential interferences has been accomplished.  
1.2 This test method is a Flame Ionization Detector-based (FID-based) hydrocarbon analysis method without the use of separation columns. Therefore, this method does not provide speciation of individual hydrocarbons. Several varieties of instruments are manufactured and can be used for this method.  
1.2.1 This method provides a measure of THC “as CH4,” because all hydrocarbon species are quantified the same as CH4 response, which is the sole species used for calibration. Magnitude of the FID response to an atom of carbon is dependent on the chemical environment of this atom in the molecule. This method provides the THC result as if all carbon atoms are from aliphatic, aromatic, olefinic, or acetylenic compounds, where the detector response caused by these atoms is approximately relative to the number of carbon atoms present in the molecule. Other types of molecules, including those containing oxygen or chlorine atoms, will respond differently and usually much lower than the corresponding aliphatic hydrocarbon. Therefore, other methods (Test Methods D7653, D7892, or equivalent) must be utilized to determine the exact constituents of the THC response determined by this method.  
1.3 The proper handling of compressed gas cylinders containing air, nitrogen, hydrogen, or helium requires the use of gas regulators to preclude over-pressurization of any instrument component  
1.4 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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 re...

General Information

• Status: Published
• Publication Date: 31-May-2022
• ICS: 27.075 - Hydrogen technologies
• Technical Committee: D03 - Gaseous Fuels
• Drafting Committee: D03.14 - Hydrogen and Fuel Cells

Relations

• Refers: ASTM D4150-19 - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 15-Dec-2019
• Refers: ASTM D7653-18 - Standard Test Method for Determination of Trace Gaseous Contaminants in Hydrogen Fuel by Fourier Transform Infrared (FTIR) Spectroscopy
• Effective Date: 01-Dec-2018
• Refers: ASTM D7606-17 - Standard Practice for Sampling of High Pressure Hydrogen and Related Fuel Cell Feed Gases
• Effective Date: 01-Nov-2017
• Refers: ASTM D4150-08(2016) - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 01-Jul-2016
• Refers: ASTM D7606-11 - Standard Practice for Sampling of High Pressure Hydrogen and Related Fuel Cell Feed Gases
• Effective Date: 01-Mar-2011
• Refers: ASTM D7653-10 - Standard Test Method for Determination of Trace Gaseous Contaminants in Hydrogen Fuel by Fourier Transform Infrared (FTIR) Spectroscopy
• Effective Date: 01-Sep-2010
• Refers: ASTM D4150-08 - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 01-Dec-2008
• Refers: ASTM D4150-03 - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 10-Aug-2003
• Refers: ASTM D4150-00 - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 10-Jun-2000

Overview

ASTM D7675-22 is a standard test method developed by ASTM International for the determination of total hydrocarbons (THCs) in hydrogen gas using a flame ionization detector (FID)-based THC analyzer. This method is particularly significant for evaluating the purity of hydrogen fuel used in applications like proton exchange membrane fuel cells (PEM-FC). Ensuring low levels of residual hydrocarbons is critical, as even trace contaminants can impact the performance and lifespan of sensitive fuel cell systems. The standard enables quantification of total hydrocarbons down to 0.1 parts per million by volume (ppm(v)), with the measurement made on a methane (CH4) equivalence basis.

Key Topics

• FID-Based Total Hydrocarbon Analysis
  The test method uses flame ionization detection for direct measurement of total hydrocarbon content in hydrogen. All hydrocarbons are assumed to generate the same FID response as methane, making the process efficient but non-specific in identifying individual hydrocarbon species.

• Analytical Range and Sensitivity
  Sensitivity ranges from 0.1 ppm(v) to 1000 ppm(v), catering to both trace and higher concentration levels. For samples above the upper measurement limit, dynamic dilution using high-purity hydrogen is allowed without recalibration.

• Calibration and Quality Assurance
  Daily calibration with certified methane-in-hydrogen standards and regular verification of instrument linearity are required. Control charts and replicate analyses are recommended for quality assurance, supporting reliable detection limits and data integrity.

• Applicability to Other Gases
  While primarily intended for hydrogen, the procedure can be adapted to other non-hydrocarbon gases (e.g., nitrogen), provided that the background matrix is matched in both calibration and zero gases to mitigate interference.

• Safety and Handling
  The standard emphasizes safe handling of pressurized gases and the importance of appropriate safety practices, including the use of gas regulators and leak-tight systems to avoid hazards associated with hydrogen and compressed gases.

Applications

• Hydrogen Fuel Quality Verification
  Key for hydrogen suppliers and users in the fuel cell industry, this method ensures compliance with fuel quality guidelines such as SAE J2719, supporting the operational requirements of PEM and other low-temperature fuel cells.

• Hydrogen Production and Distribution
  Utilized in hydrogen production plants, refueling stations, and pipeline operations to monitor and maintain hydrogen purity, thus protecting equipment and end-use applications.

• Regulatory Compliance and Certification
  Supports adherence to both international fuel quality standards and governmental regulations, helping manufacturers and distributors demonstrate product safety and suitability.

• Adaptability for Other Gaseous Samples
  The technique can be tailored to analyze THC in gases like nitrogen, where hydrocarbon quantification at trace levels is important for industrial, research, or environmental monitoring.

Related Standards

• SAE J2719 - Hydrogen Fuel Quality Guideline for Fuel Cell Vehicles: defines allowable impurity levels, including THC, in hydrogen for automotive fuel cells.
• ASTM D7653 - Determination of Trace Gaseous Contaminants in Hydrogen Fuel by FTIR Spectroscopy.
• ASTM D7892 - Determination of Total Organic Halides, Non-Methane Hydrocarbons, and Formaldehyde in Hydrogen Fuel by GC/MS.
• ASTM D7606 - Practice for Sampling of High Pressure Hydrogen and Fuel Cell Feed Gases.
• ISO 14687 - Hydrogen Fuel Quality - Product Specification.
• EPA 40 CFR Part 136 Appendix B - Method detection limit procedures, referenced for establishing sensitivity requirements.

Implementing ASTM D7675-22 ensures reliable, reproducible quantification of total hydrocarbons in hydrogen, directly supporting fuel integrity and regulatory confidence in hydrogen supply chains.

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: D7675 − 22
Standard Test Method for
Determination of Total Hydrocarbons in Hydrogen by FID-
Based Total Hydrocarbon (THC) Analyzer
This standard is issued under the fixed designation D7675; 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 1.3 The proper handling of compressed gas cylinders con-
taining air, nitrogen, hydrogen, or helium requires the use of
1.1 This test method describes a procedure for total hydro-
gas regulators to preclude over-pressurization of any instru-
carbons (THC’s) measurement in hydrogen intended as a fuel
ment component
on a methane (C ) basis. The determination of THC on a C
1 1
1.4 Units—The values stated in SI units are to be regarded
basis is an analytical technique where all the hydrocarbons are
as standard. No other units of measurement are included in this
assumed to have the same response as methane (CH ). Sensi-
standard.
tivityfrom0.1partspermillionbyvolume(ppm(v),µmol/mol)
1.5 This standard does not purport to address all of the
up to 1000 ppm(v) concentration is achievable. Higher con-
safety concerns, if any, associated with its use. It is the
centrations can be analyzed using appropriate dilution tech-
responsibility of the user of this standard to establish appro-
niques. This test method can be applied to other gaseous
priate safety, health, and environmental practices and deter-
samples requiring analysis of trace constituents provided an
mine the applicability of regulatory limitations prior to use.
assessment of potential interferences has been accomplished.
1.6 This international standard was developed in accor-
1.2 This test method is a Flame Ionization Detector-based dance with internationally recognized principles on standard-
(FID-based) hydrocarbon analysis method without the use of ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
separation columns. Therefore, this method does not provide
mendations issued by the World Trade Organization Technical
speciation of individual hydrocarbons. Several varieties of
Barriers to Trade (TBT) Committee.
instruments are manufactured and can be used for this method.
1.2.1 This method provides a measure of THC “as CH ,”
2. Referenced Documents
becauseallhydrocarbonspeciesarequantifiedthesameasCH
2.1 ASTM Standards:
response, which is the sole species used for calibration.
D4150 Terminology Relating to Gaseous Fuels
Magnitude of the FID response to an atom of carbon is
D7653 Test Method for Determination of Trace Gaseous
dependent on the chemical environment of this atom in the
Contaminants in Hydrogen Fuel by Fourier Transform
molecule.This method provides theTHC result as if all carbon
Infrared (FTIR) Spectroscopy
atoms are from aliphatic, aromatic, olefinic, or acetylenic
D7606 Practice for Sampling of High Pressure Hydrogen
compounds,wherethedetectorresponsecausedbytheseatoms
and Related Fuel Cell Feed Gases
is approximately relative to the number of carbon atoms
D7892 Test Method for Determination of Total Organic
present in the molecule. Other types of molecules, including
Halides, Total Non-Methane Hydrocarbons, and Formal-
those containing oxygen or chlorine atoms, will respond
dehyde in Hydrogen Fuel by Gas Chromatography/Mass
differently and usually much lower than the corresponding
Spectrometry
aliphatichydrocarbon.Therefore,othermethods(TestMethods
2.2 EPA Standard:
D7653,D7892,orequivalent)mustbeutilizedtodeterminethe
40 CFR Part 136 Appendix B: Definition and Procedure for
exact constituents of the THC response determined by this
the Determination of the Method Detection Limit
method.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
ThistestmethodisunderthejurisdictionofASTMCommitteeD03onGaseous contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Fuels and is the direct responsibility of Subcommittee D03.14 on Hydrogen and Standards volume information, refer to the standard’s Document Summary page on
Fuel Cells. the ASTM website.
Current edition approved June 1, 2022. Published June 2022. Originally AvailablefromUnitedStatesEnvironmentalProtectionAgency(EPA),William
approved in 2011. Last previous edition approved in 2015 as D7675 – 15. DOI: Jefferson Clinton Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20460,
10.1520/D7675-22. http://www.epa.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7675 − 22
2.3 SAE Standard: 4.5 This test method determines total carbon, and all of the
SAE J2719 Hydrogen Fuel Quality for Fuel Cell Vehicles hydrocarbons are assumed to have the same response as CH .
Therefore, if the THC result is 1 ppm(v) and the hydrocarbon
3. Terminology
was CH , there would be 1 µmole of CH /mole of hydrogen.
4 4
However, if the THC result is 1 ppm(v) and as an example, the
3.1 Definitions—For definitions of general terms used in
hydrocarbon was propane (C H ), there would be 0.36 µmole
3 8
D03 Gaseous Fuels standards, refer to Terminology D4150.
of propane per mole of hydrogen.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 C Hydrocarbon, n—a hydrocarbon carbon content
5. Significance and Use
expressed in terms of CH .
5.1 Low operating temperature fuel cells such as proton
3.2.2 pressurized sampling, n—collection of a sample in a
exchange membrane fuel cells (PEM-FC) require high purity
container with a (final) container pressure above atmospheric
hydrogen for maximum material performance and lifetime.
pressure.
Analysis to 0.1 part per million (ppm(v)) concentration of
THCs(measuredasCH )inhydrogenisnecessaryforensuring
3.2.3 Shewart Control Chart, n—statistical tool for moni-
toring and improving quality, originated by Walter Shewart in a feed gas of sufficient purity to satisfy fuel cell system needs
as defined in SAE J2719 or as specified in regulatory codes.
1924.
3.3 Abbreviations: 5.2 Dynamicdilutiontechniquesusinghighlyaccuratemass
flow controllers can be used with test samples that have THC
3.3.1 C —Methane basis
content exceeding the upper limit of the instrument’s linear
3.3.2 CH —Methane
range, without the need to recalibrate the instrument using
3.3.3 FID—Flame Ionization Detector
higher levels of calibration standards. The sample can be
3.3.4 MDL—Method Detection Limit
diluted with a high purity grade of hydrogen (99.999 %, so
long as it contains < 0.1 ppm(v) THCs) to achieve a result of
3.3.5 ppm(v)—parts per million by volume
the THC content by applying the appropriate dilution factor to
3.3.6 THC—Total Hydrocarbon
the result. Samples that contain THC concentrations greater
than 1000 ppm(v) may be determined, although results will
4. Summary of Test Method
likey be achieved with reduced precision and should be
4.1 A hydrogen gas sample is analyzed via appropriate gas
analyzed by the dilution method.
inlet system by a THC analyzer and compared to a reference
5.3 Although not intended for application to gases other
standard mixture of known composition.
than hydrogen, techniques within this test method can be
4.2 The THC analyzer utilizes the flame ionization method
applied to other non-hydrocarbon gas samples requiring THC
of detection. The sensor is a burner in which a regulated flow
content determination. This can be achieved by using a zero
of sample gas passes through a flame sustained by regulated
gas and a calibration gas that consist of the same background
flows of air and a fuel gas (hydrogen or a hydrogen/diluent
gas as the actual sample. As an example, for the THC
mixture).Within the flame, the hydrocarbon components of the
determination of nitrogen, the instrument zero point must be
sample stream undergo a complex ionization that produces
determined with a high purity grade of nitrogen (99.999 % and
electrons and positive ions. Polarized electrodes collect these
< 0.1 ppm(v) THCs) and the instrument calibration must be
ions, causing current to flow through electronic measuring
done with a certified standard of CH in nitrogen in the
circuitry. The ionization current is proportional to the rate at
appropriate range. This will correct for any interferences
which carbon atoms enter the burner, and is therefore a
caused by the background gas.
measure of the concentration of hydrocarbons in the original
sample, present as CH . The analyzer provides a readout on a
6. Apparatus
front panel digital display and a selectable output for an
6.1 Instrument—Any instrument of standard manufacture,
accessory recorder.
with hardware necessary for interfacing to a pressurized
4.3 To ensure stable, drift-free operation, particularly in
hydrogen sample and containing all the features necessary for
high-sensitivity applications, an internal temperature controller
the intended application(s) can be used.
maintains the analyzer interior at a constant temperature. A
6.1.1 This method uses a Flame Ionization Detector (FID).
temperature of 50 6 1 °C is appropriate. This feature mini-
The principle components of the burner are the manifold,
mizes temperature-dependent variations in electronic current
burner jet, and the collector. Streams of sample, fuel, and air
measuring circuitry and adsorption/desorption equilibrium of
delivered by the analyzer flow system are routed through
background hydrocarbons within the internal flow system.
internal passages in the manifold and into the interior of the
burner (see Fig. 1). Here the sample and fuel pass through the
4.4 To minimize system response time, an internal sample
burner jet and into the flame; the air stream flows around the
bypass feature provides high velocity sample flow through the
periphery of the flame.
analyzer.
6.1.2 The burner jet and the collector function as electrodes.
The jet is connected to the positive terminal of a polarizing
voltage. The collector is connected to the signal amplifier. The
Available from SAE International (SAE), 400 Commonwealth Dr.,Warrendale,
PA 15096-0001, http://www.sae.org. two polarized electrodes establish an electrostatic field in the
D7675 − 22
FIG. 1 Typical FID Burner Diagram
vicinity of the flame. The field causes the charged particles better. (Warning—Extremely flammable gas under high pres-
formed during combustion to migrate. Electrons go to the sure.)
burner jet; positive ions go to the collector. Thus a small
7.4 Other concentrations of CH in hydrogen as needed.
ionization current flows between the two electrodes. Magni-
7.5 The use of oxygen scrubbers, water dryers, and hydro-
tude of the current depends on the concentration of carbon
carbon scrubbers are used in all gases supplied to the THC
atoms in the sample. The burner current serves as the input
analysis system. Follow supplier instructions in the use of such
signal to the electronic measuring circuitry.
gas purifiers and replace as necessary.
6.2 Detector Gas Control—Constant flow control of detec-
tor gases is critical for optimum and consistent analytical 8. Hazards
performance. Control is achieved by use of pressure regulators
8.1 Compressed gas cylinders should only be handled in
and flow controllers. The gas flow is measured by appropriate
well-ventilated locations away from sparks and flames. Im-
means and adjusted as necessary.
proper handling of compressed gas cylinders containing air,
6.3 Data Acquisition—Data acquisition and storage can be nitrogen, hydrogen, or helium can result in explosion. Rapid
release of nitrogen or helium can result in asphyxiation.
accomplished using a number of devices and media. Following
are some examples. Compressed air supports combustion.
6.3.1 Recorder—A0to1mVrangerecordingpotentiometer
8.2 The hydrogen delivery system must be leak-free or a
or equivalent can be used.
flammable situation could occur. Safety measures such as
6.3.2 Data Storage—Most instruments come equipped with
hydrogen monitors are recommended to ensure that potentially
an RS-232 port. This allows the instrument to report its data to
combustible gas mixtures do not come in contact with any
a computer or to a serial printer for data storage.
ignition source
7. Reagents and Materials
9. Preparation of Apparatus
7.1 A high purity grade of hydrogen that meets 99.999 %
9.1 Set up the instrumentation and optimize the FID in
minimum purity and <0.1 ppm(v) THC content. (Warning—
accordance with the manufacturer’s instruction or as specified
Extremely flammable gas under high pressure.)
herein. Optimization of the
...

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: D7675 − 15 D7675 − 22
Standard Test Method for
Determination of Total Hydrocarbons in Hydrogen by FID-
Based Total Hydrocarbon (THC) Analyzer
This standard is issued under the fixed designation D7675; 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 describes a procedure for total hydrocarbons (THC)(THC’s) measurement in hydrogen intended as a fuel for
fuel cells on a methane (C1)(C ) basis. The determination of total hydrocarbons THC on a C1C basis is an analytical technique
1 1
where all of the hydrocarbons are assumed to have the same response as methane. methane (CH ). Sensitivity from 0.1 partparts
per million by volume (ppm(v), μmole/mole)μmol/mol) up to 1000 parts per million (ppm(v), μmole/mole) concentration
areppm(v) concentration is achievable. Higher concentrations can be analyzed using appropriate dilution techniques. This test
method can be applied to other gaseous samples requiring analysis of trace constituents provided an assessment of potential
interferences has been accomplished.
1.2 This test method is an FID-based a Flame Ionization Detector-based (FID-based) hydrocarbon analysis method without the
use of separation columns. Therefore, this method does not provide speciation of individual hydrocarbons. Several varieties of
instruments are manufactured and can be used for this method.
1.2.1 This method provides a measure of total hydrocarbons THC “as methane,”CH ,” because all hydrocarbon species are
quantified the same as methaneCH response, which is the sole species used for calibration. Magnitude of the FID response to an
atom of carbon is dependent on the chemical environment of this atom in the molecule. This method provides the total hydrocarbon
THC result as if all carbon atoms are from aliphatic, aromatic, olefinic, or acetylenic compounds, where the detector response
caused by these atoms areis approximately relative to the number of carbon atoms present in the molecule. Other types of
molecules, including those containing oxygen or chlorine atoms, will respond differently and usually much lower than the
corresponding aliphatic hydrocarbon. Therefore, other methods (Test Methods D7653, D7892, or equivalent) must be utilized to
determine the exact constituents of the total hydrocarbon THC response determined by this method.
1.3 The proper handling of compressed gas cylinders containing air, nitrogen, hydrogen, or helium requires the use of gas
regulators to preclude over-pressurization of any instrument component
1.4 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of
the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
This test method is under the jurisdiction of ASTM Committee D03 on Gaseous Fuels and is the direct responsibility of Subcommittee D03.14 on Hydrogen and Fuel
Cells.
Current edition approved Nov. 1, 2015June 1, 2022. Published December 2015June 2022. Originally approved in 2011. Last previous edition approved in 20112015 as
D7675D7675 – 15.-11. DOI: 10.1520/D7675–15.10.1520/D7675-22.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7675 − 22
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.
2. Referenced Documents
2.1 ASTM Standards:
D4150 Terminology Relating to Gaseous Fuels
D7653 Test Method for Determination of Trace Gaseous Contaminants in Hydrogen Fuel by Fourier Transform Infrared (FTIR)
Spectroscopy
D7606 Practice for Sampling of High Pressure Hydrogen and Related Fuel Cell Feed Gases
D7892 Test Method for Determination of Total Organic Halides, Total Non-Methane Hydrocarbons, and Formaldehyde in
Hydrogen Fuel by Gas Chromatography/Mass Spectrometry
2.2 EPA Standards:Standard:
EPA 40 CRFCFR Part 136 Appendix B: Definition and Procedure for the Determination of the Method Detection Limit
2.3 SAE Standards:Standard:
SAE J2719 Hydrogen Fuel Quality Guideline for Fuel Cell Vehicles
3. Terminology
3.1 Definitions—For definitions of general terms used in D03 Gaseous Fuels standards, refer to Terminology D4150.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 C1C Hydrocarbon, n—a hydrocarbon carbon content expressed in terms of methane.CH .
1 4
3.1.2 C2 Hydrocarbon, n—a hydrocarbon carbon content expressed in terms of ethane.
3.1.3 contaminant, n—impurity or foreign material that makes a product less suitable or even unsuitable for the intended use or
that adversely affects the components within the processing, storage, or distribution systems.
3.1.4 dynamic calibration, n—calibration of an analytical system using calibration gas standard concentrations generated by
diluting known concentration compressed gas standards with purified inert gas.
3.1.5 gaseous fuel , n—hydrogen used as a fuel source for the operation of the flame ionization detector.
3.1.6 gauge pressure, n—pressure measured above ambient atmospheric pressure. Zero gauge pressure is equal to ambient
atmospheric (barometric) pressure.
3.2.2 pressurized sampling, n—collection of a sample in a container with a (final) container pressure above atmospheric pressure.
3.2.3 Shewart Control Chart, n—statistical tool for monitoring and improving quality, originated by Walter Shewart in 1924.
3.1.9 static calibration, n—calibration of an analytical system using standards in a matrix, state, or manner different than the
samples to be analyzed.
3.1.10 student t-test, n—a t-test is any statistical hypothesis test in which the test statistic follows a student’s t distribution if the
null hypothesis is supported.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from United States Environmental Protection Agency (EPA), William Jefferson Clinton Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20460,
http://www.epa.gov.
Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale, PA 15096-0001, http://www.sae.org.
D7675 − 22
3.3 Abbreviations:
3.3.1 C —Methane basis
3.3.2 CH —Methane
3.3.3 FID—Flame Ionization Detector
3.3.4 MDL—Method Detection Limit
3.3.5 ppm(v)—parts per million by volume
3.3.6 THC—Total Hydrocarbon
4. Summary of Test Method
4.1 A hydrogen gas sample is analyzed via appropriate gas inlet system by a total hydrocarbon THC analyzer and compared to
a reference standard mixture of known composition.
4.2 The total hydrocarbon THC analyzer utilizes the flame ionization method of detection. The sensor is a burner in which a
regulated flow of sample gas passes through a flame sustained by regulated flows of air and a fuel gas (hydrogen or a
hydrogen/diluent mixture). Within the flame, the hydrocarbon components of the sample stream undergo a complex ionization that
produces electrons and positive ions. Polarized electrodes collect these ions, causing current to flow through electronic measuring
circuitry. The ionization current is proportional to the rate at which carbon atoms enter the burner, and is therefore a measure of
the concentration of hydrocarbons in the original sample, present as methane.CH . The analyzer provides a readout on a front panel
digital display and a selectable output for an accessory recorder.
4.3 To ensure stable, drift-free operation, particularly in high-sensitivity applications, an internal temperature controller maintains
the analyzer interior at a constant temperature. A temperature of 50 6 1°C1 °C is appropriate. This feature minimizes
temperature-dependent variations in electronic current measuring circuitry and adsorption/desorption equilibrium of background
hydrocarbons within the internal flow system.
4.4 To minimize system response time, an internal sample bypass feature provides high velocity sample flow through the analyzer.
4.5 This test method determines total carbon, and all of the hydrocarbons are assumed to have the same response as methane.CH .
Therefore, if the THC result is 1 ppm(v) and the hydrocarbon was methane (CHCH ), there would be 1 μmole of
methane/moleCH /mole of hydrogen. However, if the THC result is 1 ppm(v) and as an example, the hydrocarbon was propane
(C H ), there would be 0.36 μmole of propane per mole of hydrogen.
3 8
5. Significance and Use
5.1 Low operating temperature fuel cells such as proton exchange membrane fuel cells (PEM-FC) require high purity hydrogen
for maximum material performance and lifetime. Analysis to 0.1 part per million (ppm(v)) concentration of total hydrocarbons
THCs (measured as methane)CH ) in hydrogen is necessary for ensuring a feed gas of sufficient purity to satisfy fuel cell system
needs as defined in SAE J2719 or as specified in regulatory codes.
5.2 Dynamic dilution techniques using highly accurate mass flow controllers can be used with test samples that have total
hydrocarbon THC content exceeding the upper limit of the instrument’s linear range, without the need to recalibrate the instrument
using higher levels of calibration standards. The sample can be diluted with a high purity grade of hydrogen (99.999 %, so long
as it contains < 0.1 ppm(v) total hydrocarbons) THCs) to achieve a result of the total hydrocarbon THC content by applying the
appropriate dilution factor to the result. Samples that contain total hydrocarbon THC concentrations greater than 1000 ppm(v) may
be determined, although results will likey be achieved with reduced precision and should be analyzed by the dilution method.
5.3 Although not intended for application to gases other than hydrogen, techniques within this test method can be applied to other
non-hydrocarbon gas samples requiring total hydrocarbon THC content determination. This can be achieved by using a zero gas
D7675 − 22
and a calibration gas that consist of the same background gas as the actual sample. As an example, for the total hydrocarbon THC
determination of nitrogen, the instrument zero point must be determined with a high purity grade of nitrogen (99.999 % and < 0.1
ppm(v) total hydrocarbons) THCs) and the instrument calibration must be done with a certified standard of methaneCH in nitrogen
in the appropriate range. This will correct for any interferences caused by the background gas.
6. Apparatus
6.1 Instrument—Any instrument of standard manufacture, with hardware necessary for interfacing to a pressurized hydrogen
sample and containing all the features necessary for the intended application(s) can be used.
6.1.1 This method uses a Flame Ionization Detector (FID). The principle components of the burner are the manifold, burner jet,
and the collector. Streams of sample, fuel, and air delivered by the analyzer flow system are routed through internal passages in
the manifold and into the interior of the burner (see Fig. 1). Here the sample and fuel pass through the burner jet and into the flame;
the air stream flows around the periphery of the flame.
6.1.2 The burner jet and the collector function as electrodes. The jet is connected to the positive terminal of a polarizing voltage.
The collector is connected to the signal amplifier. The two polarized electrodes establish an electrostatic field in the vicinity of the
flame. The field causes the charged particles formed during combustion to migrate. Electrons go to the burner jet; positive ions
go to the collector. Thus a small ionization current flows between the two electrodes. Magnitude of the current depends on the
concentration of carbon atoms in the sample. The burner current serves as the input signal to the electronic measuring circuitry.
6.2 Detector Gas Control—Constant flow control of detector gases is critical for optimum and consistent analytical performance.
Control is achieved by use of pressure regulators and flow controllers. The gas flow is measured by appropriate means and adjusted
as necessary.
6.3 Data Acquisition—Data acquisition and storage can be accomplished using a number of devices and media. Following are
some examples.
6.3.1 Recorder—A 0 to 1 mV range recording potentiometer or equivalent can be used.
6.3.2 Data Storage—Most instruments come equipped with an RS-232 port. This allows the instrument to report its data to a
computer or to a serial printer for data storage.
7. Reagents and Materials
7.1 A high purity grade of hydrogen that meets 99.999 % minimum purity and <0.1 ppm(v) total hydrocarbon THC content.
(Warning—Extremely flammable gas under high pressure.)
FIG. 1 Typical FID Burner Diagram
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7.2 A high purity grade of compressed air with less than 0.1 ppm(v) total hydrocarbon THC content. (Warning—Compressed gas
under high pressure that supports combustion.)
7.3 Reference Standards—The calibration standards used for this test method are standard mixtures of methaneCH in hydrogen
traceable to NIST or
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