ASTM D7833-12
(Test Method)Standard Test Method for Determination of Hydrocarbons and Non-Hydrocarbon Gases in Gaseous Mixtures by Gas Chromatography
Standard Test Method for Determination of Hydrocarbons and Non-Hydrocarbon Gases in Gaseous Mixtures by Gas Chromatography
SIGNIFICANCE AND USE
5.1 The hydrocarbon component distribution of gaseous mixtures is often required for end-use sale of this material. Applications such as chemical feedstock or fuel require precise compositional data to ensure uniform quality. Trace amounts of some hydrocarbon impurities in these materials can have adverse effects on their use and processing. Certain regulations may require use of such method.
5.2 The component distribution data of gaseous mixtures can be used to calculate physical properties such as relative density, vapor pressure, and heating value calculations found in Practice D3588. Precision and accuracy of compositional data is extremely important when this data is used to calculate various properties of petroleum products.
SCOPE
1.1 This test method is intended to quantitatively determine the non-condensed hydrocarbon gases with carbon numbers from C1 to C5+ and non-hydrocarbon gases, such as H2, CO2, O2, N2, and CO, in gaseous samples. This test method is a companion standard test method to Test Method D1945 and Practice D1946 differing in that it incorporates use of capillary columns instead of packed columns and allows other technological differences.
1.2 Hydrogen sulfide can be detected but may not be accurately determined by this procedure due to loss in sample containers or sample lines and possible reactions unless special precautions are taken.
1.3 Non-hydrocarbon gases have a lower detection limit in the concentration range of 0.03 to 100 mole percent using a thermal conductivity detector (TCD) and C1 to C6 hydrocarbons have a lower detection limit in the range of 0.005 to 100 mole percent using a flame ionization detector (FID); using a TCD may increase the lower detection limit to approximately 0.03 mole percent.
1.3.1 Hydrocarbon detection limits can be reduced with the use of pre-concentration techniques and/or cryogenic trapping.
1.4 This test method does not fully determine individual hydrocarbons heavier than benzene, which are grouped together as C7+ When detailed analysis is not required the compounds with carbon number greater than C5 may be grouped as either C6+, or C7+. Accurate analysis of C5+ components depends on proper vaporization of these compounds during sampling at process unit sources as well as in the sample introduction into the analyzer in the laboratory.
1.5 Water vapor may interfere with the C6+ analysis if a TCD detector is used.
1.6 Helium and argon may interfere with the determination of hydrogen and oxygen respectively. Depending on the analyzer used, pentenes, if present, may either be separated or grouped with the C6+ components.
1.7 The values stated in SI units are to be regarded as standard.
1.8 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.
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Designation: D7833 − 12
StandardTest Method for
Determination of Hydrocarbons and Non-Hydrocarbon
Gases in Gaseous Mixtures by Gas Chromatography
This standard is issued under the fixed designation D7833; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope analyzer used, pentenes, if present, may either be separated or
grouped with the C + components.
1.1 This test method is intended to quantitatively determine
the non-condensed hydrocarbon gases with carbon numbers 1.7 The values stated in SI units are to be regarded as
from C to C + and non-hydrocarbon gases, such as H,CO , standard.
1 5 2 2
O,N , and CO, in gaseous samples. This test method is a
2 2 1.8 This standard does not purport to address all of the
companion standard test method to Test Method D1945 and
safety concerns, if any, associated with its use. It is the
Practice D1946 differing in that it incorporates use of capillary
responsibility of the user of this standard to establish appro-
columns instead of packed columns and allows other techno-
priate safety and health practices and determine the applica-
logical differences.
bility of regulatory limitations prior to use.
1.2 Hydrogen sulfide can be detected but may not be
2. Referenced Documents
accurately determined by this procedure due to loss in sample
containersorsamplelinesandpossiblereactionsunlessspecial
2.1 ASTM Standards:
precautions are taken.
D1945Test Method for Analysis of Natural Gas by Gas
Chromatography
1.3 Non-hydrocarbon gases have a lower detection limit in
D1946Practice for Analysis of Reformed Gas by Gas
the concentration range of 0.03 to 100 mole percent using a
Chromatography
thermal conductivity detector (TCD) and C to C hydrocar-
1 6
D3588Practice for Calculating Heat Value, Compressibility
bons have a lower detection limit in the range of 0.005 to 100
Factor, and Relative Density of Gaseous Fuels
mole percent using a flame ionization detector (FID); using a
E355PracticeforGasChromatographyTermsandRelation-
TCD may increase the lower detection limit to approximately
ships
0.03 mole percent.
E1510Practice for Installing Fused Silica Open Tubular
1.3.1 Hydrocarbon detection limits can be reduced with the
Capillary Columns in Gas Chromatographs
use of pre-concentration techniques and/or cryogenic trapping.
F307Practice for Sampling Pressurized Gas for GasAnaly-
1.4 This test method does not fully determine individual
sis
hydrocarbons heavier than benzene, which are grouped to-
2.2 ASTM Publication:
gether as C + When detailed analysis is not required the
ASTMDS4B,1991PhysicalConstantsofHydrocarbonand
compounds with carbon number greater than C may be
Non-Hydrocarbon Compounds
grouped as either C +, or C +. Accurate analysis of C +
6 7 5
components depends on proper vaporization of these com-
3. Terminology
pounds during sampling at process unit sources as well as in
the sample introduction into the analyzer in the laboratory.
3.1 Terminology related to the practice of gas chromatog-
raphy can be found in Practice E355.
1.5 Water vapor may interfere with the C + analysis if a
TCD detector is used.
3.2 Definitions:
3.2.1 sample set—a collection of samples taken from the
1.6 Helium and argon may interfere with the determination
same source or at similar component composition and concen-
of hydrogen and oxygen respectively. Depending on the
trations.
ThistestmethodisunderthejurisdictionofASTMCommitteeD03onGaseous
Fuels and is the direct responsibility of Subcommittee D03.07 on Analysis of For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Chemical Composition of Gaseous Fuels. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved Nov. 1, 2012. Published December 2012. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D7833-12. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7833 − 12
TABLE 1 List of Components Typically Analyzed (Hydrocarbons)
4. Summary of Test Method
Component FID TCD
4.1 Components in a representative sample are physically
C olefin / C + composite X X
5 6
separated by gas chromatography (GC) and compared to
oxygen/argon composite X
calibration data obtained under identical operating conditions
hydrogen X
carbon dioxide X
from a reference standard mixture of known composition. The
hydrogen sulfide X
numerous heavy-end components of a sample can be grouped
nitrogen X
intoirregularpeaksbyreversingthedirectionofthecarriergas
carbon monoxide X
methane X X
through the column at such time as to group the heavy ends
ethane X X
either as C and heavier, C and heavier, or C and heavier or
5 6 7
ethylene X X
alternatively elute them in the non-backflushed mode and
propane X X
propylene X X
summed accordingly. The composition of the sample is calcu-
acetylene X X
lated by comparing the peak areas with the corresponding
isobutane X X
values obtained with the reference standard. propadiene X X
n-butane X X
trans-2-butene X X
5. Significance and Use
1-butene X X
isobutylene X X
5.1 The hydrocarbon component distribution of gaseous
cis-2-butene X X
mixtures is often required for end-use sale of this material.
neopentane X X
cyclopentane X X
Applicationssuchaschemicalfeedstockorfuelrequireprecise
isopentane X X
compositionaldatatoensureuniformquality.Traceamountsof
methyl acetylene X X
some hydrocarbon impurities in these materials can have
n-pentane X X
1,3-butadiene X X
adverseeffectsontheiruseandprocessing.Certainregulations
may require use of such method.
5.2 The component distribution data of gaseous mixtures
can be used to calculate physical properties such as relative
6.1.3 Other detectors or combination of detectors may be
density,vaporpressure,andheatingvaluecalculationsfoundin
used provided that they have sufficient response, linearity, and
Practice D3588. Precision and accuracy of compositional data
sensitivity to measure the components of interest at the
is extremely important when this data is used to calculate
concentration levels required for this application and meeting
various properties of petroleum products.
all of the quality controls specified in this method. Some
analyzers, such as micro-analyzers, may contain up to
6. Apparatus
4-channels and separation systems to accomplish the analysis
6.1 Gas Chromatograph (GC)—This method allows the use
described in this method.
of most gas chromatographic analyzers designed for gas
6.2 Data Acquisition—Any commercial computerized data
analysis. Generally, any gas chromatographic instrument with
acquisition system may be used for display of the chromato-
a linear temperature programmable column oven or adequate
graphicdetectorsignalandpeakareaintegrationfromallofthe
temperature control to provide the required separation of
detectors used in the analysis.The device should be capable of
gaseous compounds being analyzed may be used. The tem-
generating and storing a calibration and reporting the final
perature control must be capable of obtaining retention time
corrected response factor results.
repeatability within 5% of the retention time for each compo-
nent throughout the scope of this analysis for hydrocarbon and
6.3 Sample Introduction and System Configurations—
non-hydrocarbon gas analyses.
Sample introduction is typically performed with automated
6.1.1 Detector—The type and number of detectors em- valves containing sampling ‘loops’of appropriate sizes. Fig. 1
ployed is dependent on gas analyzer model and vendor used.
gives a suggested configuration, although systems may vary
Detectors that can be used include, but are not limited to FID, slightly among gas analyzers. The combination of valve
TCD,AED (Atomic Emission Detector), HID (Helium Ioniza-
injection size and/or splitting inlet ratio must be selected such
tionDetector),andMS(MassSpectrometer).Manysystemsuse that the required sensitivity for the application is achieved and
a 3 detector system:
also that no component concentration in a sample is greater
(1)One FID (Flame Ionization Detector) for the determi- than the detector upper linearity limit.The sample inlet system
nation of the hydrocarbon gases for the compounds listed in
shall be constructed of materials that are inert and non-
Table 1, adsorptive with respect to the components in the sample. The
(2)One TCD (Thermal Conductivity Detector) dedicated
preferred material of construction is stainless steel. Copper,
to the determination of hydrogen utilizing nitrogen or argon as
brass, and other copper-bearing alloys are unacceptable. The
a carrier gas, and
sample size limitation of 0.5 mLor smaller is selected relative
(3)One TCD for the determination of all other required
to the linearity of the detector response, and efficiency of
non-hydrocarbon gases using helium as the carrier gas.
column separation. Larger samples may be used to determine
6.1.2 A TCD may also be used for the analysis of the low-quantity components to increase measurement accuracy.
hydrocarbongases(replacingtheFID)whenhighsensitivity(< Sample sizes may be determined by experimentation or as
0.03 mole percent) for trace analysis is not required. recommended by analyzer vendors.
D7833 − 12
FIG. 1 Example of a Three Detector System for Analysis of Hydrocarbons and Non-Hydrocarbon Gases
FIG. 2 Example Chromatogram of Non-Hydrocarbon and Light Hydrocarbon Gases from System Configuration in Fig. 1
6.3.1 Hydrogen Sulfide and Other Reactive Gases— may benefit from use of surface treated metal surfaces, such as
Samples containing hydrogen sulfide and trace reactive gases
D7833 − 12
NOTE 1—For the hydrocarbon analysis, the Al O PLOT was used.
2 3
FIG. 3 Example Chromatogram of Hydrocarbons from System Configuration in Fig. 1
3 4
Silcosteel or Sulfinert processes. Such specially treated carrier gas is used to ensure that the hydrogen ‘peak’remains
surfaces are also recommended for sample containers that may positive over the concentration range of interest. Any column
contain such reactive species.
or multiple columns may be used, as long as helium and
6.3.2 With Capillary Columns—The gas chromatograph hydrogen are separated and also separated from the other
must include a heated splitting type inlet that is operated
components. Typically, a dedicated TCD is used for this
isothermally, or if appropriate, direct connection to the valve analysis. The gas-sampling valve shall provide a repeatability
may be possible as long as sample sizes are adjusted
ofatleast 62%relativetothesamplevolumeintroductionfor
accordingly, the calibrations are linear in the range of interest, major compounds present at >5 vol%.
and the required resolution of the compounds of interest is
NOTE 1—When helium is not expected to be present in samples the
maintained. When using a split injection, split ratios in the resolution of hydrogen from helium is not critical.
range of 5:1 to 200:1, with a typical value of 100:1, have been
6.5 Non-Hydrocarbon and Light Hydrocarbon GasAnalysis
usedsuccessfullydependinguponthesampleinjectionvolume
(Except Hydrogen) (Thermal Conductivity Detector)—A 10-
and sensitivity required.
portgassamplingvalveincombinationwitha6-portswitching
6.3.3 With Pre-concentrator and/or Cryogenic Trapping—
valve or equivalent is used with helium or hydrogen carrier to
Pre-concentratorand/orcryogenictrappingcanbeusedpriorto
analyze for CO,O,N , CH4, C H , and CO and in some
2 2 2 2 6
sample introduction into the gas chromatograph. These items
cases H S. Any column or multiple columns may be used as
may enable lower detection limits on the components detailed
longasthedesiredcomponentsarewellseparated.ATCDmay
by the manufacturer to be concentrated.
also be used for the analysis of the hydrocarbon gases
6.4 Hydrogen Gas Analysis (Thermal Conductivity
(replacingtheFID)whenhighsensitivity(<300ppm)fortrace
Detector)—A10-portgas-samplingvalveorequivalentmaybe
analysis is not required. The gas-sampling valve shall provide
used with nitrogen or argon carrier gas. Nitrogen or argon
a repeatability of at least 6 2% relative to the sample volume
introduction for major compounds present at >5 vol%.
Silcosteel is a trademarked of SilcoTek, 112 Benner Circle, Bellefonte, PA
6.6 Hydrocarbon Gas Analysis (Flame Ionization
16823.
Detector)—A6-port gas-sampling valve in combination with a
SulfinertisatrademarkedofRestekCorporation110BennerCircleBellefonte,
PA 16823. 6-port pre-column switching valve (backflush) for the C+or
D7833 − 12
C + hydrocarbons is typically used. These valves shall be pre-column that provides separation between the components
contained in a heated enclosure and operated at a sufficiently ofinterestandthecompositeheaviercomponentsmaybeused.
high temperature, and within the limits of the valve operating Choices may include lengths of column such as a 10 to 30 m
temperature as specified by manufacturer, to prevent conden- section of 0.53 mm (I.D.) 3-µm film thickness dimethyl
sation of the C + components in the sample. The use of a frit polysiloxane ora9to15cm section of the same column
or packed-screen type filter ahead of the sample introduction material as the analytical column or any pre-column that
port is recommended with use of PLOT columns. The gas- provides the desired retention of pentenes, hexanes, and
sampling valve shall provide a repeatability of at least 6 2% heavier components. This pre-column acts to keep the heavier
relative to the sample volume introduction for major com- components away from the analytical alumina PLOT column
pounds present at >5 vol%. and to backflush the heavier components as a composite peak
to the detector for quantification. If analysis of individual
6.7 Column Series/Reversal Switching Valve—If desired, a
C -C componentsisrequired,extendthebackflushvalvetime
6 7
multi-port valve may be used to provide the C olefin/C+or
5 6
until the desired components have eluted and prior to back-
C + determination for this analysis. Other switching valve
flushing the remaining heavier compounds.
configurations may be used to allow the elution of the gaseous
compounds. Consult instrument manufacturer for optimum 6.12 Analytical Columns for Hydrogen Analysis—Generally
configuration.
hydrogen analysis consists of a pre-column to remove most of
NOTE 2—If a dimethylsilicone capillary column or
...
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