ASTM D2427-06(2011)
(Test Method)Standard Test Method for Determination of C2 through C5 Hydrocarbons in Gasolines by Gas Chromatography
Standard Test Method for Determination of C<sub>2</sub> through C<sub>5</sub> Hydrocarbons in Gasolines by Gas Chromatography
SIGNIFICANCE AND USE
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 and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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 2011)
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 and health practices and determine the applica-
bility of regulatory limitations prior to use.
1.1 This test method covers the determination of the two
(C ) through five(C -) carbon paraffins and mono-olefins in
2 5 2. Referenced Documents
gasolines. The concentrations by volume or mass (weight) of
2.1 ASTM Standards:
the following components are generally reported:
D2001 Test Method for Depentanization of Gasoline and
1.1.1 Ethylene plus ethane
Naphthas
1.1.2 Propane
1.1.3 Propylene
3. Summary of Test Method
1.1.4 Isobutane
3.1 The sample is injected into a gas-liquid partition col-
1.1.5 n-Butane
umn. The components are separated as they pass through the
1.1.6 Butene-1 plus isobutylene
column with an inert carrier gas and their presence in the
1.1.7 trans-Butene-2
effluent is detected and recorded as a chromatogram. Materials
1.1.8 cis-Butene-2
containing components having more than five carbon atoms
1.1.9 Isopentane
can either be backflushed from the system without
1.1.10 3-Methylbutene-1
measurement, or recorded as a broad peak by reversing the
1.1.11 n-Pentane
direction of the carrier gas through the column at such time as
1.1.12 Pentene-1
to regroup the higher-boiling portion (C and heavier) of the
1.1.13 2-Methylbutene-1
sample. If backflushing is used, the concentration of C
1.1.14 trans-Pentene-2
through C hydrocarbons may be related to the whole sample
1.1.15 cis-Pentene-2
by adding a known quantity of low-boiling internal standard to
1.1.16 2-Methylbutene-2
the sample prior to analysis.Alternatively, a known amount of
1.2 This test method does not cover the determination of
sample can be charged and compared to a standard sample run
cyclic olefins, diolefins, or acetylenes. These are usually minor
under the same conditions. Sample composition is determined
components in finished gasolines.
from the chromatogram by comparing peak areas with those
obtained using known amounts of calibration standards or a
1.3 Samples to be analyzed should not contain significant
synthetic blend.
amounts of material boiling lower than ethylene.
4. Significance and Use
1.4 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
4.1 In hydrocarbon type analyses of gasolines, highly vola-
standard.
tile fuels can need to be stabilized by depentanization (Test
1.4.1 Exception—Alternative units, in common usage, are
Method D2001) prior to analysis. A knowledge of the compo-
also provided to improve the clarity and aid the user of this test
sition of light hydrocarbons in the overhead from the depen-
method.
tanization process is useful in converting analyses of the
1.5 This standard does not purport to address all of the depentanized fraction to a total sample basis.
safety concerns, if any, associated with its use. It is the
5. Apparatus
responsibility of the user of this standard to establish appro-
5.1 Chromatograph—Any chromatograph having a thermo-
stated oven and a detection system of adequate sensitivity may
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 May 1, 2011. Published August 2011. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1965. Last previous edition approved in 2006 as D2427–06. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D2427-06R11. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2427 − 06 (2011)
be used. The detection system must have sufficient sensitivity 6.4 Solid Support, for use in packed column; usually
to produce a recorder deflection of at least 5 mm for 0.1 liquid crushed firebrick or diatomaceous earth. Mesh size should be
appropriate to the system selected from the supplement.
volume percent of pentene-1 in the sample or synthetic blend
being analyzed.
7. Preparation of Apparatus
NOTE 1—If the sensitivity of a given system is inadequate, it can be
7.1 Column Preparation—The method used to prepare the
increased by using a more sensitive recorder or detector, or by using more
column is not critical as long as the finished column produces
sample if the resolution is substantially unaffected.
the desired separation. Preparation of the packing is not
5.2 Recorder—A 1 to 10-mV recorder with a full-scale
difficult once the support, partitioning liquid, and loading level
response time of 2 s or less and a noise level no greater than
have been determined. Some stationary phases are susceptible
60.3 % of full scale.
to oxidation and must be protected from excessive exposure to
air during the evaporation and drying steps. The following
5.3 Columns:
general directions have been found to produce columns of
5.3.1 A description of columns and valving arrangements
acceptable characteristics:
that meet the requirements of this method are described in
7.1.1 Weigh out the desired quantity of support, usually
Annex A1. Persons using other column materials must estab-
twice that required to fill the column.
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
2 5
twice the volume of support.
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.
5 ceases to flow, tap the column gently on the floor or bench top
whilevibratingiscontinued.Addpackingasnecessaryuntilno
6. Reagents and Materials
further settling occurs during a 2-min period. Remove a small
amount of packing from the open end, plug with a wad of glass
6.1 Compounds for calibration shall be of a purity of not
wool, and shape the column to fit the chromatograph.
less than 99 mole %. Calibrants should include compounds
7.1.8 If multiple columns are joined by tubing unions, the
1.1.5 – 1.1.16 as listed in Section 1. The concentration of
dead volume in the union should be filled with column
ethylene, ethane, propylene, and propane is generally so low in
packing.
most samples that calibration with these materials is unneces-
7.2 Chromatograph—Mount the column in the chromato-
sary (Warning—Extremely flammable gas under pressure.
graph and establish the operating conditions required to give
Extremely flammable liquids.) Commercially available certi-
the desired separation (see Annex A1). Allow sufficient time
fied blends of light hydrocarbons may be used to establish
for the instrument to reach equilibrium as indicated by a stable
calibration data where their compositions are applicable. If an
recorder base line. Control the oven temperature so that it is
internal standard is used to relate the concentration of light
constant to within 0.5°C without thermostat cycling which
hydrocarbons to the whole sample it must be included as a
causes an uneven base line. Set the carrier gas flow rate,
calibrant.
measured with a soap film meter, so that it is constant to within
6.2 Carrier Gas—A carrier gas appropriate to the type of
1 mL/min of the selected value.
detector used should be employed. Helium or hydrogen can be
used with thermal conductivity detector (Warning—
8. Procedure
Compressed gas under high pressure.) (Warning—Hydrogen
8.1 Calibration—Determine the relative area response of
is extremely flammable under pressure.) Nitrogen or argon can
the compounds to be reported by injecting known quantities of
be used with ionization or gas density detectors (Warning—
the pure compounds or by using synthetic blends of known
Compressed gas under high pressure).
composition. For those compounds that are normally gases at
6.3 Liquid Phase—See Annex A1. room temperature it is advantageous to use commercially
D2427 − 06 (2011)
available certified light hydrocarbon blends. Sample light ment.WhenalloftheC andlighterhydrocarbonsplusinternal
hydrocarbon blends contained in pressure containers from the standard, if used, have entered the analyzer column, position
liquid phase ( Warning—Extremely flammable gas under the valves so that backflushing of the precut column is
pressure.) Blends of those hydrocarbons that are normally initiated. The time at which backflushing is commenced is
liquid at room temperature are easily prepared by volume with critical and may have to be determined by trial and error. If
sufficient accuracy to establish relative response factors properly done, it results in the elimination of any interference
(Warning—Extremely flammable liquids.) If measurement of from low-boiling six-carbon paraffins and produces a chro-
the C and heavier material by reverse flow through the matogram that exhibits peaks for C through C paraffins and
6 2 5
detector is intended, an average calibration factor for these olefins only (Fig. 1). When the last compound has been eluted,
heavy materials must be determined. Gasolines that have been remove the chromatogram and proceed as described in 9.1.1.
depentanized by laboratory distillation may be used as cali-
8.2.1.2 Single Column—Ifasinglecolumnisused,itmaybe
brants for this purpose (Warning—Extremely flammable.) If
backflushed if an appropriate valving system has been in-
use of an internal standard is contemplated, the internal
stalled. The operations described above are performed except
standard selected should be included in the calibration pro-
that backflushing is commenced only when all the C and
gram.
lighter hydrocarbons and internal standard have been eluted.
The purpose of backflushing in this case is not to improve the
8.2 Analysis:
separation, but merely to shorten the total analysis time and
8.2.1 Backflush Method—When the backflush technique is
avoid passage of higher boiling hydrocarbons through the
used, add a known quantity of internal standard equal to about
detector.
5 %tothesample.Theinternalstandardcanbeaddedoneither
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 heavier portion through the detector is employed, the addition
been found convenient is given in Annex A1. Alternatively, of an internal standard is unnecessary if adequate calibration
quantitative results can be obtained by injecting repeatable has been performed and the composition of the C and heavier
quantities of the sample and of a known blend, and comparing portion does not differ significantly from that of the depenta-
the peak areas obtained for the sample with those obtained for nized gasolines used as calibrants.An internal standard can be
the known concentration of components in the blend. used periodically to assure that analytical accuracy is main-
8.2.1.1 Precut Column—If a precut column is used, adjust tained(Note2).Adjustthevalvingsothatcarriergasisflowing
thevalvingsothatcarriergasisflowinginthenormaldirection through the instrument in the normal direction. Charge suffi-
through both the precut and analysis columns. Using a chilled cient sample to ensure a minimum of 10 % recorder deflection
syringe, charge sufficient sample to ensure a minimum of 10 % for a 0.1 percent sample concentration of 2-methylbutene-2 at
recorder deflection for a 0.1 % sample concentration of the highest sensitivity. As soon as the last pentene peak
2-methylbutene-2 at the most sensitive setting of the instru- (2-methylbutene-2) has been eluted, position the valving so
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 (2011)
that the carrier gas flow is reversed. After the flow has where:
stabilized, adjust the base line. Attenuate for the C + portion
6 P = corrected peak area, and
as necessary. The run is complete when the recorder returns to
E = sum of correlated peak areas.
the base line after elution of the C portion. This part of the
sample will generally emerge as one broad peak with only
10. Precision and Bias
slight indications of any separation. Proceed as described in
10.1 The precision of this test method as obtained by
9.1.2.
statistical examination of interlaboratory test results is as
NOTE 2—All reverse flow determinations, including the C and heavi
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.