ASTM D8098-23

Standard Test Method for Permanent Gases in C<inf>2</inf> and C<inf>3</inf> Hydrocarbon Products by Gas Chromatography and Pulse Discharge Helium Ionization Detector

SIGNIFICANCE AND USE
5.1 The presence of trace amounts of hydrogen, oxygen, carbon monoxide, and carbon dioxide can have deleterious effects in certain processes using hydrocarbon products as feed stock. This test method is suitable for setting specifications, for use as an internal quality control tool, and for use in development and research work.
SCOPE
1.1 This test method covers the determination of hydrogen, nitrogen, oxygen, methane, carbon monoxide, and carbon dioxide in the parts per billion mole (nmol/mol) to parts per million mole (µmol/mol) range in C2 and C3 hydrocarbons.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  For some specific hazard statements, see Annex A1.  
1.3.1 The user is advised to obtain LPG safety training for the safe operation of this test method procedure and related activities.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 28-Feb-2023
• ICS: 75.060 - Natural gas
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.D0.02 - Ethylene

Relations

• Refers: ASTM D6300-24 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Mar-2024
• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D6300-23a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Dec-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM F307-13(2020) - Standard Practice for Sampling Pressurized Gas for Gas Analysis
• Effective Date: 01-Apr-2020
• Refers: ASTM D6300-19a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Dec-2019
• Refers: ASTM E260-96(2019) - Standard Practice for Packed Column Gas Chromatography
• Effective Date: 01-Sep-2019
• Refers: ASTM D6300-16 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Apr-2016
• Refers: ASTM D2505-88(2015) - Standard Test Method for Ethylene, Other Hydrocarbons, and Carbon Dioxide in High-Purity Ethylene by Gas Chromatography (Withdrawn 2024)
• Effective Date: 01-Jun-2015
• Refers: ASTM D6300-15 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Jun-2015
• Refers: ASTM D6300-14a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Jun-2014
• Refers: ASTM D6300-14ae1 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Jun-2014
• Refers: ASTM D7915-14 - Standard Practice for Application of Generalized Extreme Studentized Deviate &#40;GESD&#41; Technique to Simultaneously Identify Multiple Outliers in a Data Set
• Effective Date: 01-May-2014
• Refers: ASTM D6300-14 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-May-2014
• Refers: ASTM D6300-13a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Dec-2013

Overview

ASTM D8098-23, titled "Standard Test Method for Permanent Gases in C₂ and C₃ Hydrocarbon Products by Gas Chromatography and Pulse Discharge Helium Ionization Detector," is a leading standard developed by ASTM International. This test method enables the precise quantification of trace amounts of permanent gases-hydrogen, nitrogen, oxygen, methane, carbon monoxide, and carbon dioxide-in C₂ (ethane, ethylene) and C₃ (propane, propylene) hydrocarbon products.

Using gas chromatography combined with a pulse discharge helium ionization detector (PDHID), this method achieves detection limits from parts per billion mole (nmol/mol) to parts per million mole (µmol/mol). Accurate measurement of these gases is critical, as even trace concentrations can affect downstream industrial processes, product quality, and feedstock reliability.

Key Topics

• Permanent Gas Detection: The method covers six primary target gases-hydrogen, nitrogen, oxygen, methane, carbon monoxide, and carbon dioxide-relevant for monitoring and control in hydrocarbon feedstocks.
• Gas Chromatography Technology: The use of gas chromatography ensures separation of components. The PDHID offers high sensitivity and low detection limits for accurate quantification.
• Quality Assurance: Suitable for specification setting, internal quality control, and research and development applications.
• Sampling Procedures: Emphasizes the necessity of representative sampling from high-pressure gas cylinders, using validated vaporization and purging techniques to prevent contamination.
• Purity Requirements: Only ultra-high purity helium is utilized as the carrier gas, with inline purification to prevent trace contaminants from affecting results.
• Safety Practices: The method calls for adherence to rigorous safety, health, and environmental protocols, especially concerning the handling of LPG, hydrogen, oxygen, and other compressed gases.
• Standardization and International Alignment: Published in line with World Trade Organization (WTO) principles, ensuring international applicability.

Applications

• Feedstock Quality Control: The standard is instrumental in monitoring hydrocarbon purity for use as feedstock in chemical manufacturing, polymerization, and refinery operations.
• Specification Compliance: Supports producers and users in confirming that C₂ and C₃ hydrocarbon products meet strict industry or contractual specifications regarding allowable permanent gas content.
• Process Optimization: Detects impurities that could poison catalysts, interfere with industrial reactions, or impact material performance.
• Research and Development: Facilitates development of new products and processes by providing accurate, repeatable gas composition data.
• Regulatory Reporting: Enables compliance with environmental and safety regulations where trace gas concentration in hydrocarbons must be documented.

Related Standards

Several ASTM and external standards are referenced to ensure consistency and reliability in hydrocarbon gas analysis:

• ASTM D2505: Test method for hydrocarbons and carbon dioxide in high-purity ethylene by gas chromatography.
• ASTM D4175: Terminology relating to petroleum products, liquid fuels, and lubricants.
• ASTM D6300: Guidelines for statistical evaluation of precision and bias in test methods.
• ASTM D7915: Application of outlier identification in test data.
• ASTM E260: Practice for packed column gas chromatography.
• ASTM F307: Sampling of pressurized gas for analysis.
• Compressed Gas Association G-4 and G-4.1: Safe practices for the handling of oxygen.

These references ensure that laboratories and facilities using ASTM D8098-23 employ consistent, best-in-class methodologies for sampling, analysis, and data interpretation.

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Keywords: ASTM D8098-23, permanent gases, gas chromatography, PDHID, hydrocarbon analysis, ethane, ethylene, propane, propylene, trace gas detection, quality control, specification testing, gas purity, analytical methods.

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: D8098 − 23
Standard Test Method for
Permanent Gases in C and C Hydrocarbon Products by
2 3
Gas Chromatography and Pulse Discharge Helium
Ionization Detector
This standard is issued under the fixed designation D8098; 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* Fuels, and Lubricants
D6300 Practice for Determination of Precision and Bias
1.1 This test method covers the determination of hydrogen,
Data for Use in Test Methods for Petroleum Products,
nitrogen, oxygen, methane, carbon monoxide, and carbon
Liquid Fuels, and Lubricants
dioxide in the parts per billion mole (nmol/mol) to parts per
D7915 Practice for Application of Generalized Extreme
million mole (μmol/mol) range in C and C hydrocarbons.
2 3
Studentized Deviate (GESD) Technique to Simultane-
1.2 The values stated in SI units are to be regarded as
ously Identify Multiple Outliers in a Data Set
standard. No other units of measurement are included in this
E260 Practice for Packed Column Gas Chromatography
standard.
F307 Practice for Sampling Pressurized Gas for Gas Analy-
sis
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 2.2 Other Standards:
responsibility of the user of this standard to establish appro- G-4 and G-4.1, Compressed Gas Association Booklet on the
priate safety, health, and environmental practices and deter- Use of Oxygen
mine the applicability of regulatory limitations prior to use.
3. Terminology
For some specific hazard statements, see Annex A1.
1.3.1 The user is advised to obtain LPG safety training for 3.1 For definitions of terms used in this standard, see
the safe operation of this test method procedure and related
Terminology D4175.
activities.
4. Summary of Test Method
1.4 This international standard was developed in accor-
4.1 The sample is separated in a gas chromatographic
dance with internationally recognized principles on standard-
system using gas chromatography columns. Hydrogen,
ization established in the Decision on Principles for the
oxygen, nitrogen, methane, carbon monoxide, and carbon
Development of International Standards, Guides and Recom-
dioxide (also known as the permanent gases) are detected on a
mendations issued by the World Trade Organization Technical
pulse discharge detector. The concentration of the gases to be
Barriers to Trade (TBT) Committee.
determined is calculated from the peak areas relative to an
2. Referenced Documents external standard. Helium is the required carrier gas for this
detector. Ultra-high purity carrier gases and leak-free gas
2.1 ASTM Standards:
chromatography (GC) systems with getters are essential due to
D2505 Test Method for Ethylene, Other Hydrocarbons, and
the extreme sensitivity of the detector. Argon, if present in the
Carbon Dioxide in High-Purity Ethylene by Gas Chroma-
sample, may interfere with oxygen determination.
tography
D4175 Terminology Relating to Petroleum Products, Liquid
5. Significance and Use
5.1 The presence of trace amounts of hydrogen, oxygen,
1 carbon monoxide, and carbon dioxide can have deleterious
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of effects in certain processes using hydrocarbon products as feed
Subcommittee D02.D0.02 on Ethylene.
stock. This test method is suitable for setting specifications, for
Current edition approved March 1, 2023. Published May 2023. Originally
use as an internal quality control tool, and for use in develop-
approved in 2017. Last previous edition approved in 2017 as D8098 – 17. DOI:
ment and research work.
10.1520/D8098-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to this standard’s Document Summary page on Available from Compressed Gas Association (CGA), 14501 George Carter
the ASTM website. Way, Suite 103, Chantilly, VA 20151, http://www.cganet.com.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8098 − 23
6. Apparatus validated to ensure that sample discrimination is avoided.
Pressure sampling devices may be used to inject a small
6.1 Chromatograph—Any gas chromatograph capable of
amount of the liquid directly into the carrier gas.
maintaining the temperatures, pressures, and flows necessary
for this analyses. The GC should also be capable of tempera-
6.6 Materials of Construction—The sample inlet system
ture programming of the oven to obtain optimum separation of
shall be constructed of materials that are inert and non-
the components. A typical configuration is shown in Fig. 1.
adsorptive with respect to the components in the sample. The
preferred material of construction is stainless steel. Copper,
6.2 Detectors—(PDHID Pulse Discharge Detector Helium
brass, and other copper-bearing alloys are unacceptable. The
Ionization)—The PDHID detector is very sensitive to most
analysis of oxygen and carbon monoxide may benefit from the
organic or inorganic chemicals, thus requiring separation of the
use of treated metal surfaces.
product gases from the permanent gas components.
6.2.1 Alternative Detectors—This test method is written for
6.7 Column—Any column may be used provided it will
the pulsed discharge helium detector (PDHID), but other
resolve the trace compound peaks present in concentrations of
detectors can be used provided they have sufficient sensitivity,
20 ppmv or more so that the resolution ratio, A/B, will not be
respond to all of the species in the scope, do not suffer from
less than 0.4, where A is the depth of the valley on either side
interferences, and satisfy quality assurance criteria. Regulatory
of peak B and B is the height above the baseline of the smaller
agencies may require demonstration of equivalency of alterna-
of any two adjacent peaks (see Fig. 2). For compounds present
tive detection systems to the PDHID.
in concentrations of less than 20 ppm, the ratio A/B may be less
6.3 Gas Sample Valve—Any valve that allows for column than 0.4. In the case where the small-component peak is
adjacent to a large one, it may be necessary to construct the
and/or sample inlet system selection. This valve may be purged
with helium to minimize atmospheric air contamination into baseline of the small peak tangent to the curve as shown in Fig.
3.
the valve rotor and column system.
6.7.1 Columns used to obtain the results in Fig. 4 using
6.4 Helium Purifier—Ultra-high purity carrier gas with an
instrument conditions in Table 1:
inline helium purifier installed to remove impurities is recom-
6.7.1.1 Column 1, Porous divinylbenzene homopolymer,
mended. The purifier should be able produce gas with outlet
30 m × 0.53 mm × 6 μm.
impurities less than 10 nmol/mol of H O, H , O , N , NO,
2 2 2 2
NH , CO, and CO , based on 100 μmol/mol total inlet
6.7.1.2 Column 2, Porous divinylbenzene homopolymer,
3 2
impurities. A leak-free GC system is essential due to the high 30 m × 0.53 mm × 6 μm.
sensitivity of the detector.
6.7.1.3 Column 3, Molecular sieve, 30 m × 0.53 mm ×
25 μm.
6.5 Constant-volume Gas Sampling Valve—Any gas sam-
pling valve capable of delivering a consistent volume of gas. 6.7.1.4 Restrictor, Fused silica open tube, 0.60 m × 5 m,
restrictor should be sized as such to provide the same restric-
6.5.1 Liquefied Petroleum Gas Samples—Samples should
be vaporized to allow introduction to the constant-volume gas tion as the molecular sieve column as to balance the flow
sampling valve. The vaporization technique used must be across the six port bypass valve.
FIG. 1 Typical GC Configuration
D8098 − 23
8.2 Sample system purging may require the use of an
automated sampling system which provides for suitable sample
system purge to eliminate atmospheric air contamination.
Non-reproducible oxygen and nitrogen results relative to
methane (refer to Table 1) indicate air contamination.
9. Calibration
9.1 Bring the equipment and columns to equilibrium and
maintain a constant carrier gas rate and temperature.
9.2 Inject a known volume of the standard blends (prepared
or purchased).
NOTE 2—The use of stripper columns, valves, and reverse-flow arrange-
ment will facilitate removal of heavier gases and decrease the elapsed time
FIG. 2 Illustration of A/B Ratio of analysis.
9.3 Identify all of the desired peaks from the prepared
synthetic blend. Multiple levels of blends can be used for
generation of calibration tables.
9.4 The recommended method of measuring peak areas is
electronic integration with capabilities of changing integration
parameters. For each component present in the calibration
standard, calculate the response factor according to Eq 1.
RFi 5 Ci⁄Ai (1)
where:
RFi = the response factor for component i,
Ci = the known concentration of i, and
Ai = the integrated area of peak i.
9.5 A data system may be used to automate these calcula-
FIG. 3 Illustration of A/B Ratio for Small-component Peak
tions and to plot peak areas versus concentrations of each
compound in parts per million, by mole (μmol/mol).
6.8 Data System—Any analytical data system that is capable 10. Procedure
of storing the retention time, integrating peak areas, and
10.1 Connect the sample cylinder containing a gaseous
naming peaks is acceptable.
sample to the gas sample valve inlet. Sample inlet system shall
be purged thoroughly to eliminate ambient air. Either manual
7. Reagents and Materials
or automated purging may be used and shall be determined to
7.1 Gases for Calibration—Pure or research-grade
be reliable when the lowest calibration standard containing
hydrogen, oxygen, nitrogen, carbon monoxide, and carbon
oxygen and nitrogen are repeatable to less than 2 % relative
dioxide will be needed to prepare synthetic standard samples as
standard deviation and the concentration is not decreasing from
described in Test Method D2505. (Warning—Flammable
five successive injections.
gases. Hazardous pressure. See A1.1 through A1.5.)
10.2 Close the cylinder valve and allow the pressure of the
(Warning—Flammable. Poison. Harmful if inhaled. Danger-
sample in the tube to stabilize.
ous when exposed to flame. See A1.5.) (Warning—Hazardous
pressure. See A1.2.) Certified calibration blends are commer- 10.3 Inject the sample into the instrument using the gas
sampling valve. The same valve should be used for calibration
cially available from numerous sources and can be used as the
synthetic standard samples. standard and sample (pressure of sample and calibration gas
must be the same in the sample loop at injection time).
7.2 Carrier Gases—Helium, ultra-high purity (99.999 %
pure, also known as 5.0 grade).
11. Calculation
NOTE 1—Practice E260 contains information that will be helpful to
11.1 The data system will automatically record the peak
those using this test method.
retention ti
...

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: D8098 − 17 D8098 − 23
Standard Test Method for
Permanent Gases in C and C Hydrocarbon Products by
2 3
Gas Chromatography and Pulse Discharge Helium
Ionization Detector
This standard is issued under the fixed designation D8098; 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 Scope*
1.1 This test method covers the determination of hydrogen, nitrogen, oxygen, methane, carbon monoxide, and carbon dioxide in
the parts per billion mole (nmol/mol) to parts per million mole (μmol/mol) range in C and C hydrocarbons.
2 3
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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. For some specific hazard statements, see Annex A1.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of
the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. For some specific hazard statements, see Annex A1.
1.3.1 The user is advised to obtain LPG safety training for the safe operation of this test method procedure and related activities.
1.4 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:
D2505 Test Method for Ethylene, Other Hydrocarbons, and Carbon Dioxide in High-Purity Ethylene by Gas Chromatography
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D6300 Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and
Lubricants
D7915 Practice for Application of Generalized Extreme Studentized Deviate (GESD) Technique to Simultaneously Identify
Multiple Outliers in a Data Set
E260 Practice for Packed Column Gas Chromatography
F307 Practice for Sampling Pressurized Gas for Gas Analysis
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.D0.02 on Ethylene.
Current edition approved July 15, 2017March 1, 2023. Published September 2017May 2023. Originally approved in 2017. Last previous edition approved in 2017 as
D8098 – 17. DOI: 10.1520/D8098-17.10.1520/D8098-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to this standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8098 − 23
2.2 Other Standards:
G-4 and G-4.1, Compressed Gas Association Booklet on the Use of Oxygen
3. Terminology
3.1 For definitions of terms used in this standard, see Terminology D4175.
4. Summary of Test Method
4.1 The sample is separated in a gas chromatographic system using gas chromatography columns. Hydrogen, oxygen, nitrogen,
methane, carbon monoxide, and carbon dioxide (also known as the permanent gases) are detected on a pulse discharge detector.
The concentration of the gases to be determined is calculated from the peak areas relative to an external standard. Helium is the
required carrier gas for this detector. Ultra-high purity carrier gases and leak-free gas chromatography (GC) systems with getters
are essential due to the extreme sensitivity of the detector. Argon, if present in the sample, may interfere with oxygen
determination.
5. Significance and Use
5.1 The presence of trace amounts of hydrogen, oxygen, carbon monoxide, and carbon dioxide can have deleterious effects in
certain processes using hydrocarbon products as feed stock. This test method is suitable for setting specifications, for use as an
internal quality control tool, and for use in development and research work.
6. Apparatus
6.1 Chromatograph—Any gas chromatograph capable of maintaining the temperatures, pressures, and flows necessary for this
analyses. The GC should also be capable of temperature programming of the oven to obtain optimum separation of the components.
A typical configuration is shown in Fig. 1.
6.2 Detectors—(PDHID Pulse Discharge Detector Helium Ionization)—The PDHID detector is very sensitive to most organic or
inorganic chemicals, thus requiring separation of the product gases from the permanent gas components.
6.2.1 Alternative Detectors—This test method is written for the pulsed discharge helium detector (PDHID), but other detectors can
FIG. 1 Typical GC Configuration
Available from Compressed Gas Association (CGA), 14501 George Carter Way, Suite 103, Chantilly, VA 20151, http://www.cganet.com.
D8098 − 23
be used provided they have sufficient sensitivity, respond to all of the species in the scope, do not suffer from interferences, and
satisfy quality assurance criteria. Regulatory agencies may require demonstration of equivalency of alternative detection systems
to the PDHID.
6.3 Gas Sample Valve—Any valve that allows for column and/or sample inlet system selection. This valve may be purged with
helium to minimize atmospheric air contamination into the valve rotor and column system.
6.4 Helium Purifier—Ultra-high purity carrier gas with an inline helium purifier installed to remove impurities is recommended.
The purifier should be able produce gas with outlet impurities less than 10 nmol/mol of H O, H , O , N , NO, NH , CO, and CO ,
2 2 2 2 3 2
based on 100 μmol/mol total inlet impurities. A leak-free GC system is essential due to the high sensitivity of the detector.
6.5 Constant-volume Gas Sampling Valve—Any gas sampling valve capable of delivering a consistent volume of gas.
6.5.1 Liquefied Petroleum Gas Samples—Samples should be vaporized to allow introduction to the constant-volume gas sampling
valve. The vaporization technique used must be validated to ensure that sample discrimination is avoided. Pressure sampling
devices may be used to inject a small amount of the liquid directly into the carrier gas.
6.6 Materials of Construction—The sample inlet system shall be constructed of materials that are inert and non-adsorptive with
respect to the components in the sample. The preferred material of construction is stainless steel. Copper, brass, and other
copper-bearing alloys are unacceptable. The analysis of oxygen and carbon monoxide may benefit from the use of treated metal
surfaces.
6.7 Column—Any column may be used provided it will resolve the trace compound peaks present in concentrations of 20 ppmv
or more so that the resolution ratio, A/B, will not be less than 0.4, where A is the depth of the valley on either side of peak B and
B is the height above the baseline of the smaller of any two adjacent peaks (see Fig. 2). For compounds present in concentrations
of less than 20 ppm, the ratio A/B may be less than 0.4. In the case where the small-component peak is adjacent to a large one,
it may be necessary to construct the baseline of the small peak tangent to the curve as shown in Fig. 3.
6.7.1 Columns used to obtain the results in Fig. 4 using instrument conditions in Table 1:
6.7.1.1 Column 1, Porous divinylbenzene homopolymer, 30 m × 0.53 mm × 6 μm.
6.7.1.2 Column 2, Porous divinylbenzene homopolymer, 30 m × 0.53 mm × 6 μm.
6.7.1.3 Column 3, Molecular sieve, 30 m × 0.53 mm × 25 μm.
6.7.1.4 Restrictor, Fused silica open tube, 0.60 m × 5 m, restrictor should be sized as such to provide the same restriction as the
molecular sieve column as to balance the flow across the six port bypass valve.
6.8 Data System—Any analytical data system that is capable of storing the retention time, integrating peak areas, and naming
peaks is acceptable.
FIG. 2 Illustration of A/B Ratio
D8098 − 23
FIG. 3 Illustration of A/B Ratio for Small-component Peak
7. Reagents and Materials
7.1 Gases for Calibration—Pure or research-grade hydrogen, oxygen, nitrogen, carbon monoxide, and carbon dioxide will be
needed to prepare synthetic standard samples as described in Test Method D2505. (Warning—Flammable gases. Hazardous
pressure. See A1.1 through A1.5.) (Warning—Flammable. Poison. Harmful if inhaled. Dangerous when exposed to flame. See
A1.5.) (Warning—Hazardous pressure. See A1.2.) Certified calibration blends are commercially available from numerous sources
and can be used as the synthetic standard samples.
7.2 Carrier Gases—Helium, ultra-high purity (99.999 % pure, also known as 5.0 grade).
NOTE 1—Practice E260 contains information that will be helpful to those using this test method.
8. Sampling
8.1 Samples shall be supplied to the laboratory in high-pressure sample cylinders, obtained using the procedures described in
Practice F307 or similar methods. All cylinders should meet all applicable safety requirements.
8.2 Sample system purging may require the use of an automated sampling system which provides for suitable sample system purge
to eliminate atmospheric air contamination. Non-reproducible oxygen and nitrogen results relative to methane (refer to Table 1)
indicate air contamination.
9. Calibration
9.1 Bring the equipment and columns to equilibrium and maintain a constant carrier gas rate and temperature.
9.2 Inject a known volume of the standard blends (prepared or purchased).
NOTE 2—The use of stripper columns, valves, and reverse-flow arrangement will facilitate removal of heavier gases and decrease the elapsed time of
analysis.
9.3 Identify all of the desired peaks from the prepared synthetic blend. Multiple levels of blends can be used for generation of
calibration tables.
9.4 The recommended method of measuring peak areas is electronic integration with capabilities of changing integration
parameters. For each component present in the calibration standard, calculate the response factor according to Eq 1.
RFi 5 Ci⁄Ai (1)
where:
RFi = the response factor for component i,
Ci = the known concentration of i, and
D8098 − 23
FIG. 4 Typical Chromatogram for Hydrogen, Oxygen, Nitrogen, Methane, Carbon Monoxide, and Carbon Dioxide
TABLE 1 Instrument Conditions
Temperatures
Valve Box 100 °C
Column 50 °C (hold 5 min), ramp 20 °C/min to 85 °C (hold 1 min)
PDHID 200 °C
Flows
Column 1, 2, 3 15 mL/min
Valve Timing
Valve 1 (10 port) On @ 0.01 min, Off @ 2.00 min
Valve 2 (6 port) On @ 3.20 min, Off @ 3.80 min
Ai = the integrated area of peak i.
9.5 A data system may be used to automate these calculations and to plot peak areas versus concentrations of
...