ASTM D2427-06(2019)
(Test Method)Standard Test Method for Determination of C2 through C5 Hydrocarbons in Gasolines by Gas Chromatography (Withdrawn 2023)
Standard Test Method for Determination of C<inf>2</inf> through C<inf>5</inf> Hydrocarbons in Gasolines by Gas Chromatography (Withdrawn 2023)
SIGNIFICANCE AND USE
4.1 In hydrocarbon type analyses of gasolines, highly volatile fuels can need to be stabilized by depentanization (Test Method D2001) prior to analysis. A knowledge of the composition of light hydrocarbons in the overhead from the depentanization process is useful in converting analyses of the depentanized fraction to a total sample basis.
SCOPE
1.1 This test method covers the determination of the two (C2) through five (C5-) carbon paraffins and mono-olefins in gasolines. The concentrations by volume or mass (weight) of the following components are generally reported:
1.1.1 Ethylene plus ethane
1.1.2 Propane
1.1.3 Propylene
1.1.4 Isobutane
1.1.5 n-Butane
1.1.6 Butene-1 plus isobutylene
1.1.7 trans-Butene-2
1.1.8 cis-Butene-2
1.1.9 Isopentane
1.1.10 3-Methylbutene-1
1.1.11 n-Pentane
1.1.12 Pentene-1
1.1.13 2-Methylbutene-1
1.1.14 trans-Pentene-2
1.1.15 cis-Pentene-2
1.1.16 2-Methylbutene-2
1.2 This test method does not cover the determination of cyclic olefins, diolefins, or acetylenes. These are usually minor components in finished gasolines.
1.3 Samples to be analyzed should not contain significant amounts of material boiling lower than ethylene.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4.1 Exception—Alternative units, in common usage, are also provided to improve the clarity and aid the user of this test method.
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.
WITHDRAWN RATIONALE
This test method covered the determination of the two (C2) through five (C5-) carbon paraffins and mono-olefins in gasolines.
The reasons for withdrawing the test method are as follows: (1) The test method was developed with older technology which is not readily available today. As a result, there is no easy mechanism to update the test method without method development and a new ILS. (2) The test method has a precision statement based on an old ASTM practice but not the currently accepted D6300. (3) There is no referenced research report. ASTM archives do not have a research report on file. The ASTM Form and Style Manual requires a research report. (4) The committee understands that this method is rarely used. There are several test methods (for example, D6730, D6729) that provide compositional data for gasolines as possible alternatives. (5) ASTM will continue to provide copies of the test method for those that may need it in the original format.
Formerly under the jurisdiction of Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants, this test method was withdrawn in October 2023 and replaced by Test Method D6730 on the Determination of Individual Components in Spark Ignition Engine Fuels by 100-Metre Capillary (with Precolumn) High-Resolution Gas Chromatography and Test Method D6729 on Determination of Individual Components in Spark Ignition Engine Fuels by 100 Metre Capillary High Resolution Gas Chromatography1
General Information
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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: D2427 − 06 (Reapproved 2019)
Standard Test Method for
Determination of C through C Hydrocarbons in Gasolines
2 5
by Gas Chromatography
This standard is issued under the fixed designation D2427; 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 priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.1 This test method covers the determination of the two
1.6 This international standard was developed in accor-
(C ) through five (C -) carbon paraffins and mono-olefins in
2 5
dance with internationally recognized principles on standard-
gasolines. The concentrations by volume or mass (weight) of
ization established in the Decision on Principles for the
the following components are generally reported:
Development of International Standards, Guides and Recom-
1.1.1 Ethylene plus ethane
mendations issued by the World Trade Organization Technical
1.1.2 Propane
Barriers to Trade (TBT) Committee.
1.1.3 Propylene
1.1.4 Isobutane
2. Referenced Documents
1.1.5 n-Butane
2.1 ASTM Standards:
1.1.6 Butene-1 plus isobutylene
D2001 Test Method for Depentanization of Gasoline and
1.1.7 trans-Butene-2
Naphthas
1.1.8 cis-Butene-2
1.1.9 Isopentane
3. Summary of Test Method
1.1.10 3-Methylbutene-1
1.1.11 n-Pentane
3.1 The sample is injected into a gas-liquid partition col-
1.1.12 Pentene-1
umn. The components are separated as they pass through the
1.1.13 2-Methylbutene-1
column with an inert carrier gas and their presence in the
1.1.14 trans-Pentene-2
effluent is detected and recorded as a chromatogram. Materials
1.1.15 cis-Pentene-2
containing components having more than five carbon atoms
1.1.16 2-Methylbutene-2
can either be backflushed from the system without
measurement, or recorded as a broad peak by reversing the
1.2 This test method does not cover the determination of
direction of the carrier gas through the column at such time as
cyclic olefins, diolefins, or acetylenes. These are usually minor
to regroup the higher-boiling portion (C and heavier) of the
components in finished gasolines.
sample. If backflushing is used, the concentration of C
1.3 Samples to be analyzed should not contain significant
through C hydrocarbons may be related to the whole sample
amounts of material boiling lower than ethylene.
by adding a known quantity of low-boiling internal standard to
1.4 The values stated in SI units are to be regarded as
the sample prior to analysis.Alternatively, a known amount of
standard. No other units of measurement are included in this sample can be charged and compared to a standard sample run
standard.
under the same conditions. Sample composition is determined
1.4.1 Exception—Alternative units, in common usage, are from the chromatogram by comparing peak areas with those
also provided to improve the clarity and aid the user of this test
obtained using known amounts of calibration standards or a
method. synthetic blend.
1.5 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 4.1 In hydrocarbon type analyses of gasolines, highly vola-
tile fuels can need to be stabilized by depentanization (Test
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 D02.04.0L on Gas Chromatography Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Dec. 1, 2019. Published December 2019. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1965. Last previous edition approved in 2015 as D2427 – 06 (2015). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D2427-06R19. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2427 − 06 (2019)
Method D2001) prior to analysis. A knowledge of the compo- Compressed gas under high pressure.) (Warning—Hydrogen
sition of light hydrocarbons in the overhead from the depen- is extremely flammable under pressure.) Nitrogen or argon can
tanization process is useful in converting analyses of the be used with ionization or gas density detectors (Warning—
depentanized fraction to a total sample basis. Compressed gas under high pressure).
6.3 Liquid Phase—See Annex A1.
5. Apparatus
5.1 Chromatograph—Any chromatograph having a thermo- 6.4 Solid Support, for use in packed column; usually
stated oven and a detection system of adequate sensitivity may crushed firebrick or diatomaceous earth. Mesh size should be
be used. The detection system must have sufficient sensitivity appropriate to the system selected from the supplement.
to produce a recorder deflection of at least 5 mm for 0.1 liquid
volume percent of pentene-1 in the sample or synthetic blend
7. Preparation of Apparatus
being analyzed.
7.1 Column Preparation—The method used to prepare the
NOTE 1—If the sensitivity of a given system is inadequate, it can be
column is not critical as long as the finished column produces
increased by using a more sensitive recorder or detector, or by using more
the desired separation. Preparation of the packing is not
sample if the resolution is substantially unaffected.
difficult once the support, partitioning liquid, and loading level
5.2 Recorder—A 1 mV to 10 mV recorder with a full-scale
have been determined. Some stationary phases are susceptible
response time of 2 s or less and a noise level no greater than
to oxidation and must be protected from excessive exposure to
60.3 % of full scale.
air during the evaporation and drying steps. The following
general directions have been found to produce columns of
5.3 Columns:
acceptable characteristics:
5.3.1 A description of columns and valving arrangements
7.1.1 Weigh out the desired quantity of support, usually
that meet the requirements of this method are described in
twice that required to fill the column.
Annex A1. Persons using other column materials must estab-
lish that the column gives results that meet the precision 7.1.2 Calculate and weigh out the required quantity of
requirements of Section 10.
partitioning agent. Dissolve the partitioning agent in a volume
5.3.2 Analyzer Column—The column system used must be ofchemicallyinert,low-boilingsolventequaltoapproximately
capable of resolving the individual C to C paraffins and
twice the volume of support.
2 5
olefins well enough so that the individual hydrocarbons listed
7.1.3 Graduallyaddthesupportmaterialtothesolutionwith
in Section 1 may be reported. The resolution should be such
gentle stirring.
that at the operating conditions selected, the distance from the
7.1.4 Slowly evaporate the solvent while gently agitating
base line in the valley between two peaks representing com-
the mixture until the packing is nearly dry and no free liquid is
pounds reported is not greater than 50 % of the height of the
apparent.
smaller peak. If an internal standard is used, it must be
7.1.5 Spread the packing in thin layers on a nonabsorbent
completely resolved from the other components.
surface and air or oven dry as required to remove all traces of
5.3.3 Precut Column—This column must be capable of
solvent.
separating the C and lighter olefins and paraffins from the C
5 6
7.1.6 Resieve the packing to remove fines and agglomerates
andheavierolefinsandparaffins.Theresolutionshouldbesuch
produced in the impregnation step.
that at the operating conditions selected, the distance from the
7.1.7 Fill the column tubing with packing by plugging one
base line to the valley between 2-methylbutene-2 and 2,2-
end with a wad of glass wool and pouring the packing into the
dimethylbutane is not greater than 50 % of the height of the
other end through a small funnel. Vibrate the tubing continu-
smaller peak. If an internal standard is used, it must be eluted
ously over its entire length while filling. When the packing
with the C and lighter materials.
ceases to flow, tap the column gently on the floor or bench top
6. Reagents and Materials
whilevibratingiscontinued.Addpackingasnecessaryuntilno
further settling occurs during a 2 min period. Remove a small
6.1 Compounds for calibration shall be of a purity of not
amount of packing from the open end, plug with a wad of glass
less than 99 mole %. Calibrants should include compounds
wool, and shape the column to fit the chromatograph.
1.1.5 – 1.1.16 as listed in Section 1. The concentration of
7.1.8 If multiple columns are joined by tubing unions, the
ethylene, ethane, propylene, and propane is generally so low in
dead volume in the union should be filled with column
most samples that calibration with these materials is unneces-
packing.
sary (Warning—Extremely flammable gas under pressure.
Extremely flammable liquids.) Commercially available certi-
7.2 Chromatograph—Mount the column in the chromato-
fied blends of light hydrocarbons may be used to establish
graph and establish the operating conditions required to give
calibration data where their compositions are applicable. If an
the desired separation (see Annex A1). Allow sufficient time
internal standard is used to relate the concentration of light
for the instrument to reach equilibrium as indicated by a stable
hydrocarbons to the whole sample it must be included as a
recorder base line. Control the oven temperature so that it is
calibrant.
constant to within 0.5 °C without thermostat cycling which
6.2 Carrier Gas—A carrier gas appropriate to the type of causes an uneven base line. Set the carrier gas flow rate,
detector used should be employed. Helium or hydrogen can be measured with a soap film meter, so that it is constant to within
used with thermal conductivity detector (Warning— 1 mL/min of the selected value.
D2427 − 06 (2019)
8. Procedure 8.2.1.1 Precut Column—If a precut column is used, adjust
thevalvingsothatcarriergasisflowinginthenormaldirection
8.1 Calibration—Determine the relative area response of
through both the precut and analysis columns. Using a chilled
the compounds to be reported by injecting known quantities of
syringe, charge sufficient sample to ensure a minimum of 10 %
the pure compounds or by using synthetic blends of known
recorder deflection for a 0.1 % sample concentration of
composition. For those compounds that are normally gases at
2-methylbutene-2 at the most sensitive setting of the instru-
room temperature it is advantageous to use commercially
ment.WhenalloftheC andlighterhydrocarbonsplusinternal
available certified light hydrocarbon blends. Sample light 5
standard, if used, have entered the analyzer column, position
hydrocarbon blends contained in pressure containers from the
the valves so that backflushing of the precut column is
liquid phase (Warning—Extremely flammable gas under pres-
initiated. The time at which backflushing is commenced is
sure.) Blends of those hydrocarbons that are normally liquid at
critical and may have to be determined by trial and error. If
roomtemperatureareeasilypreparedbyvolumewithsufficient
properly done, it results in the elimination of any interference
accuracy to establish relative response factors (Warning—
from low-boiling six-carbon paraffins and produces a chro-
Extremely flammable liquids.) If measurement of the C and
matogram that exhibits peaks for C through C paraffins and
heavier material by reverse flow through the detector is 2 5
olefins only (Fig. 1). When the last compound has been eluted,
intended, an average calibration factor for these heavy mate-
remove the chromatogram and proceed as described in 9.1.1.
rials must be determined. Gasolines that have been depenta-
nized by laboratory distillation may be used as calibrants for 8.2.1.2 Single Column—Ifasinglecolumnisused,itmaybe
this purpose (Warning—Extremely flammable.) If use of an
backflushed if an appropriate valving system has been in-
internalstandardiscontemplated,theinternalstandardselected
stalled. The operations described above are performed except
should be included in the calibration program.
that backflushing is commenced only when all the C and
lighter hydrocarbons and internal standard have been eluted.
8.2 Analysis:
The purpose of backflushing in this case is not to improve the
8.2.1 Backflush Method—When the backflush technique is
separation, but merely to shorten the total analysis time and
used, add a known quantity of internal standard equal to about
avoid passage of higher boiling hydrocarbons through the
5 %tothesample.Theinternalstandardcanbeaddedoneither
detector.
a weight or volume basis depending upon the method of
reporting. One method of adding the internal standard that has 8.2.2 Reverse Flow Method—If reverse flow of the C and
heavier portion through the detector is employed, the addition
been found convenient is given in Annex A1. Alternatively,
quantitative results can be obtained by injecting repeatable of an internal standard is unnecessary if adequate calibration
has been performed and the composition of the C and heavier
quantities of the sample and of a known blend, and comparing
the peak areas obtained for the sample with those obtained for portion does not differ significantly from that of the depenta-
the known concentration of components in the blend. nized gasolines used as calibrants.An internal standard can be
Column:
Precut: SF96-50 silicone fluid
Analyzer: tricresylphosphate plus DC 550 silicone fluid 4.5/1 by wt followed by ethylene glycol in series.
FIG. 1 Typical Chromatogram of Light Components in a Catalytic Gasoline
D2427 − 06 (2019)
used periodically to assure that analytical accuracy is main- components. Calibration factors relative to volume or weight
tained(Note2).Adjustthevalvingsothatcarriergasisflowing percentages may be used. Calculate the percentage of each
through the instrument in the normal direction. Charge suffi- component as follows:
cient sample to ensure a minimum of 10 % recorder deflection
P
3100 (3)
for a 0.1 % sample concentration of 2-methylbutene-2 at the
E
highest sensitivity. As soon as the last pentene peak (2-
where:
methylbutene-2) has been eluted, position
...
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D2427 − 06 (Reapproved 2019)
Standard Test Method for
Determination of C through C Hydrocarbons in Gasolines
2 5
by Gas Chromatography
This standard is issued under the fixed designation D2427; 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 priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.1 This test method covers the determination of the two
1.6 This international standard was developed in accor-
(C ) through five (C -) carbon paraffins and mono-olefins in
2 5
dance with internationally recognized principles on standard-
gasolines. The concentrations by volume or mass (weight) of
ization established in the Decision on Principles for the
the following components are generally reported:
Development of International Standards, Guides and Recom-
1.1.1 Ethylene plus ethane
mendations issued by the World Trade Organization Technical
1.1.2 Propane
Barriers to Trade (TBT) Committee.
1.1.3 Propylene
1.1.4 Isobutane
2. Referenced Documents
1.1.5 n-Butane
2.1 ASTM Standards:
1.1.6 Butene-1 plus isobutylene
D2001 Test Method for Depentanization of Gasoline and
1.1.7 trans-Butene-2
Naphthas
1.1.8 cis-Butene-2
1.1.9 Isopentane
3. Summary of Test Method
1.1.10 3-Methylbutene-1
1.1.11 n-Pentane
3.1 The sample is injected into a gas-liquid partition col-
1.1.12 Pentene-1
umn. The components are separated as they pass through the
1.1.13 2-Methylbutene-1
column with an inert carrier gas and their presence in the
1.1.14 trans-Pentene-2
effluent is detected and recorded as a chromatogram. Materials
1.1.15 cis-Pentene-2
containing components having more than five carbon atoms
1.1.16 2-Methylbutene-2
can either be backflushed from the system without
measurement, or recorded as a broad peak by reversing the
1.2 This test method does not cover the determination of
direction of the carrier gas through the column at such time as
cyclic olefins, diolefins, or acetylenes. These are usually minor
to regroup the higher-boiling portion (C and heavier) of the
components in finished gasolines. 6
sample. If backflushing is used, the concentration of C
1.3 Samples to be analyzed should not contain significant
through C hydrocarbons may be related to the whole sample
amounts of material boiling lower than ethylene.
by adding a known quantity of low-boiling internal standard to
1.4 The values stated in SI units are to be regarded as the sample prior to analysis. Alternatively, a known amount of
standard. No other units of measurement are included in this
sample can be charged and compared to a standard sample run
standard. under the same conditions. Sample composition is determined
1.4.1 Exception—Alternative units, in common usage, are
from the chromatogram by comparing peak areas with those
also provided to improve the clarity and aid the user of this test obtained using known amounts of calibration standards or a
method.
synthetic blend.
1.5 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 4.1 In hydrocarbon type analyses of gasolines, highly vola-
tile fuels can need to be stabilized by depentanization (Test
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 D02.04.0L on Gas Chromatography Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Dec. 1, 2019. Published December 2019. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1965. Last previous edition approved in 2015 as D2427 – 06 (2015). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D2427-06R19. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2427 − 06 (2019)
Method D2001) prior to analysis. A knowledge of the compo- Compressed gas under high pressure.) (Warning—Hydrogen
sition of light hydrocarbons in the overhead from the depen- is extremely flammable under pressure.) Nitrogen or argon can
tanization process is useful in converting analyses of the be used with ionization or gas density detectors (Warning—
depentanized fraction to a total sample basis. Compressed gas under high pressure).
6.3 Liquid Phase—See Annex A1.
5. Apparatus
5.1 Chromatograph—Any chromatograph having a thermo- 6.4 Solid Support, for use in packed column; usually
stated oven and a detection system of adequate sensitivity may crushed firebrick or diatomaceous earth. Mesh size should be
be used. The detection system must have sufficient sensitivity appropriate to the system selected from the supplement.
to produce a recorder deflection of at least 5 mm for 0.1 liquid
volume percent of pentene-1 in the sample or synthetic blend
7. Preparation of Apparatus
being analyzed.
7.1 Column Preparation—The method used to prepare the
NOTE 1—If the sensitivity of a given system is inadequate, it can be
column is not critical as long as the finished column produces
increased by using a more sensitive recorder or detector, or by using more
the desired separation. Preparation of the packing is not
sample if the resolution is substantially unaffected.
difficult once the support, partitioning liquid, and loading level
5.2 Recorder—A 1 mV to 10 mV recorder with a full-scale
have been determined. Some stationary phases are susceptible
response time of 2 s or less and a noise level no greater than
to oxidation and must be protected from excessive exposure to
60.3 % of full scale.
air during the evaporation and drying steps. The following
general directions have been found to produce columns of
5.3 Columns:
acceptable characteristics:
5.3.1 A description of columns and valving arrangements
7.1.1 Weigh out the desired quantity of support, usually
that meet the requirements of this method are described in
twice that required to fill the column.
Annex A1. Persons using other column materials must estab-
lish that the column gives results that meet the precision
7.1.2 Calculate and weigh out the required quantity of
requirements of Section 10. partitioning agent. Dissolve the partitioning agent in a volume
5.3.2 Analyzer Column—The column system used must be
of chemically inert, low-boiling solvent equal to approximately
capable of resolving the individual C to C paraffins and twice the volume of support.
2 5
olefins well enough so that the individual hydrocarbons listed
7.1.3 Gradually add the support material to the solution with
in Section 1 may be reported. The resolution should be such
gentle stirring.
that at the operating conditions selected, the distance from the
7.1.4 Slowly evaporate the solvent while gently agitating
base line in the valley between two peaks representing com-
the mixture until the packing is nearly dry and no free liquid is
pounds reported is not greater than 50 % of the height of the
apparent.
smaller peak. If an internal standard is used, it must be
7.1.5 Spread the packing in thin layers on a nonabsorbent
completely resolved from the other components.
surface and air or oven dry as required to remove all traces of
5.3.3 Precut Column—This column must be capable of
solvent.
separating the C and lighter olefins and paraffins from the C
5 6
7.1.6 Resieve the packing to remove fines and agglomerates
and heavier olefins and paraffins. The resolution should be such
produced in the impregnation step.
that at the operating conditions selected, the distance from the
7.1.7 Fill the column tubing with packing by plugging one
base line to the valley between 2-methylbutene-2 and 2,2-
end with a wad of glass wool and pouring the packing into the
dimethylbutane is not greater than 50 % of the height of the
other end through a small funnel. Vibrate the tubing continu-
smaller peak. If an internal standard is used, it must be eluted
ously over its entire length while filling. When the packing
with the C and lighter materials.
ceases to flow, tap the column gently on the floor or bench top
6. Reagents and Materials
while vibrating is continued. Add packing as necessary until no
further settling occurs during a 2 min period. Remove a small
6.1 Compounds for calibration shall be of a purity of not
amount of packing from the open end, plug with a wad of glass
less than 99 mole %. Calibrants should include compounds
wool, and shape the column to fit the chromatograph.
1.1.5 – 1.1.16 as listed in Section 1. The concentration of
7.1.8 If multiple columns are joined by tubing unions, the
ethylene, ethane, propylene, and propane is generally so low in
dead volume in the union should be filled with column
most samples that calibration with these materials is unneces-
packing.
sary (Warning—Extremely flammable gas under pressure.
Extremely flammable liquids.) Commercially available certi-
7.2 Chromatograph—Mount the column in the chromato-
fied blends of light hydrocarbons may be used to establish
graph and establish the operating conditions required to give
calibration data where their compositions are applicable. If an
the desired separation (see Annex A1). Allow sufficient time
internal standard is used to relate the concentration of light
for the instrument to reach equilibrium as indicated by a stable
hydrocarbons to the whole sample it must be included as a
recorder base line. Control the oven temperature so that it is
calibrant.
constant to within 0.5 °C without thermostat cycling which
6.2 Carrier Gas—A carrier gas appropriate to the type of causes an uneven base line. Set the carrier gas flow rate,
detector used should be employed. Helium or hydrogen can be measured with a soap film meter, so that it is constant to within
used with thermal conductivity detector (Warning— 1 mL/min of the selected value.
D2427 − 06 (2019)
8. Procedure 8.2.1.1 Precut Column—If a precut column is used, adjust
the valving so that carrier gas is flowing in the normal direction
8.1 Calibration—Determine the relative area response of
through both the precut and analysis columns. Using a chilled
the compounds to be reported by injecting known quantities of
syringe, charge sufficient sample to ensure a minimum of 10 %
the pure compounds or by using synthetic blends of known
recorder deflection for a 0.1 % sample concentration of
composition. For those compounds that are normally gases at
2-methylbutene-2 at the most sensitive setting of the instru-
room temperature it is advantageous to use commercially
ment. When all of the C and lighter hydrocarbons plus internal
available certified light hydrocarbon blends. Sample light
standard, if used, have entered the analyzer column, position
hydrocarbon blends contained in pressure containers from the
the valves so that backflushing of the precut column is
liquid phase (Warning—Extremely flammable gas under pres-
initiated. The time at which backflushing is commenced is
sure.) Blends of those hydrocarbons that are normally liquid at
critical and may have to be determined by trial and error. If
room temperature are easily prepared by volume with sufficient
properly done, it results in the elimination of any interference
accuracy to establish relative response factors (Warning—
from low-boiling six-carbon paraffins and produces a chro-
Extremely flammable liquids.) If measurement of the C and
matogram that exhibits peaks for C through C paraffins and
heavier material by reverse flow through the detector is
2 5
olefins only (Fig. 1). When the last compound has been eluted,
intended, an average calibration factor for these heavy mate-
remove the chromatogram and proceed as described in 9.1.1.
rials must be determined. Gasolines that have been depenta-
nized by laboratory distillation may be used as calibrants for
8.2.1.2 Single Column—If a single column is used, it may be
this purpose (Warning—Extremely flammable.) If use of an
backflushed if an appropriate valving system has been in-
internal standard is contemplated, the internal standard selected
stalled. The operations described above are performed except
should be included in the calibration program.
that backflushing is commenced only when all the C and
lighter hydrocarbons and internal standard have been eluted.
8.2 Analysis:
The purpose of backflushing in this case is not to improve the
8.2.1 Backflush Method—When the backflush technique is
separation, but merely to shorten the total analysis time and
used, add a known quantity of internal standard equal to about
avoid passage of higher boiling hydrocarbons through the
5 % to the sample. The internal standard can be added on either
detector.
a weight or volume basis depending upon the method of
8.2.2 Reverse Flow Method—If reverse flow of the C and
reporting. One method of adding the internal standard that has
been found convenient is given in Annex A1. Alternatively, heavier portion through the detector is employed, the addition
of an internal standard is unnecessary if adequate calibration
quantitative results can be obtained by injecting repeatable
quantities of the sample and of a known blend, and comparing has been performed and the composition of the C and heavier
portion does not differ significantly from that of the depenta-
the peak areas obtained for the sample with those obtained for
the known concentration of components in the blend. nized gasolines used as calibrants. An internal standard can be
Column:
Precut: SF96-50 silicone fluid
Analyzer: tricresylphosphate plus DC 550 silicone fluid 4.5/1 by wt followed by ethylene glycol in series.
FIG. 1 Typical Chromatogram of Light Components in a Catalytic Gasoline
D2427 − 06 (2019)
used periodically to assure that analytical accuracy is main- components. Calibration factors relative to volume or weight
tained (Note 2). Adjust the valving so that carrier gas is flowing percentages may be used. Calculate the percentage of each
through the instrument in the normal direction. Charge suffi- component as follows:
cient sample to ensure a minimum of 10 % recorder deflection
P
3 100 (3)
for a 0.1 % sample concentration of 2-methylbutene-2 at the
E
highest sensitivity. As soon as the last pentene peak (2-
where:
methylbutene-2) has been eluted, position the v
...
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