ASTM D2427-92(1996)

NOTICE: This standard has either been superseded and replaced by a new version or
withdrawn.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: D 2427 – 92 (Reapproved 1996) An American National Standard
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
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 D 2427; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 1319 Test Method for Hydrocarbon Types In Liquid
Petroleum Products by Fluorescent Indicator Adsorption
1.1 This test method provides for the determination of the
D 2001 Test Method for Depentanization of Gasoline and
two (C ) through five(C -) carbon paraffins and mono-olefins
2 5
Naphthas
in gasolines. The concentrations by volume or mass (weight) of
the following components are generally reported:
3. Summary of Test Method
1.1.1 Ethylene plus ethane
3.1 The sample is injected into a gas - liquid partition
1.1.2 Propane
column. The components are separated as they pass through
1.1.3 Propylene
the column with an inert carrier gas and their presence in the
1.1.4 Isobutane
effluent is detected and recorded as a chromatogram. Materials
1.1.5 n-Butane
containing components having more than five carbon atoms
1.1.6 Butene-1 plus isobutylene
can either be backflushed from the system without measure-
1.1.7 trans-Butene-2
ment, or recorded as a broad peak by reversing the direction of
1.1.8 cis-Butene-2
the carrier gas through the column at such time as to regroup
1.1.9 Isopentane
the higher-boiling portion (C and heavier) of the sample. If
3-Methylbutene-1
backflushing is used, the concentration of C through C
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1.1.10 n-Pentane
hydrocarbons may be related to the whole sample by adding a
1.1.11 Pentene-1
known quantity of low-boiling internal standard to the sample
1.1.12 2-Methylbutene-1
prior to analysis. Alternatively, a known amount of sample can
1.1.13 trans-Pentene-2
be charged and compared to a standard sample run under the
1.1.14 cis-Pentene-2
same conditions. Sample composition is determined from the
1.1.15 2-Methylbutene-2
chromatogram by comparing peak areas with those obtained
1.2 This test method does not provide for the determination
using known amounts of calibration standards or a synthetic
of cyclic olefins, diolefins, or acetylenes. These are usually
blend.
minor components in finished gasolines.
1.3 Samples to be analyzed should not contain significant
4. Significance and Use
amounts of material boiling lower than ethylene.
4.1 In hydrocarbon type analyses of gasolines, such as Test
1.4 SI (metric) units of measurement are preferred and used
Method D 1319, highly volatile fuels can need to be stabilized
throughout this standard. Alternative units, in common usage,
by depentanization (Test Method D 2001) prior to analysis. A
are also provided to improve the clarity and aid the user of this
knowledge of the composition of light hydrocarbons in the
test method.
overhead from depentanization is useful in converting analyses
1.5 This standard does not purport to address all of the
of the depentanized fraction to total sample.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
5. Apparatus
priate safety and health practices and determine the applica-
5.1 Chromatograph—Any chromatograph having a thermo-
bility of regulatory limitations prior to use.
stated oven and a detection system of adequate sensitivity may
be used. The detection system must have sufficient sensitivity
2. Referenced Documents
to produce a recorder deflection of at least 5 mm for 0.1 liquid
2.1 ASTM Standards:
volume percent of pentene-1 in the sample or synthetic blend
being analyzed.
1 NOTE 1—If the sensitivity of a given system is inadequate, it can be
This test method is under the jurisdiction of ASTM Committee D-2 on
increased by using a more sensitive recorder or detector, or by using more
Petroleum Products and Lubricantsand is the direct responsibility of Subcommittee
D02.04 on Hydrocarbon Analysis.
Current edition approved Oct. 15, 1992. Published December 1992. Originally
published as D 2427 – 65 T. Last previous edition D 2427 – 87. Annual Book of ASTM Standards, Vol 05.01.
D 2427
sample if the resolution is substantially unaffected.
the desired separation. Preparation of the packing is not
difficult once the support, partitioning liquid, and loading level
5.2 Recorder—A 1 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
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
of chemically inert, low-boiling solvent equal to approximately
capable of resolving the individual C to C paraffins and
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twice the volume of support.
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
6.1 Compounds for calibration shall be of a purity of not
further settling occurs during a 2-min period. Remove a small
less than 99 mole %. Calibrants should include compounds
amount of packing from the open end, plug with a wad of glass
1.1.5-1.1.15 as listed in Section 1. The concentration of
wool, and shape the column to fit the chromatograph.
ethylene, ethane, propylene, and propane is generally so low in
7.1.8 If multiple columns are joined by tubing unions, the
most samples that calibration with these materials is unneces-
dead volume in the union should be filled with column
sary (Warning—See Note 2 and Note 3.) Commercially
packing.
available certified blends of light hydrocarbons may be used to
7.2 Chromatograph—Mount the column in the chromato-
establish calibration data where their compositions are appli-
graph and establish the operating conditions required to give
cable. If an internal standard is used to relate the concentration
the desired separation (see Annex A1). Allow sufficient time
of light hydrocarbons to the whole sample it must be included
for the instrument to reach equilibrium as indicated by a stable
as a calibrant.
recorder base line. Control the oven temperature so that it is
constant to within 0.5°C without thermostat cycling which
NOTE 2—Warning: Extremely flammable gas under pressure.
causes an uneven base line. Set the carrier gas flow rate,
NOTE 3—Warning: Extremely flammable liquids.
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—See Note 8. Procedure
4.) (Warning—See Note 5). Nitrogen or argon can be used
8.1 Calibration—Determine the relative area response of
with ionization or gas density detectors (Warning—See Note
the compounds to be reported by injecting known quantities of
4.)
the pure compounds or by using synthetic blends of known
composition. For those compounds that are normally gases at
NOTE 4—Warning: Compressed gas under high pressure.
NOTE 5—Warning: Hydrogen is extremely flammable under pressure.
room temperature it is advantageous to use commercially
available certified light hydrocarbon blends. Sample light
6.3 Liquid Phase—See Annex A1.
hydrocarbon blends contained in pressure containers from the
6.4 Solid Support, for use in packed column; usually
liquid phase (Warning—See Note 2.) Blends of those hydro-
crushed firebrick or diatomaceous earth. Mesh size should be
carbons that are normally liquid at room temperature are easily
appropriate to the system selected from the supplement.
prepared by volume with sufficient accuracy to establish
7. Preparation of Apparatus
relative response factors (Warning—See Note 3.) If measure-
7.1 Column Preparation—The method used to prepare the ment of the C and heavier material by reverse flow through the
column is not critical as long as the finished column produces detector is intended, an average calibration factor for these
D 2427
heavy materials must be determined. Gasolines that have been 8.2.1.2 Single Column—If a single column is used, it may
depentanized by laboratory distillation may be used as cali- be backflushed if an appropriate valving system has been
brants for this purpose (Warning—See Note 6.) If use of an
installed. The operations described above are performed except
internal standard is contemplated, the internal standard selected that backflushing is commenced only when all the C and
should be included in the calibration program.
lighter hydrocarbons and internal standard have been eluted.
The purpose of backflushing in this case is not to improve the
NOTE 6—Warning: Extremely flammable.
separation, but merely to shorten the total analysis time and
8.2 Analysis:
avoid passage of higher boiling hydrocarbons through the
8.2.1 Backflush Method—When the backflush technique is
detector.
used, add a known quantity of internal standard equal to about
8.2.2 Reverse Flow Method—If reverse flow of the C and
5 % to the sample. The internal standard can be added on either
heavier portion through the detector is employed, the addition
a weight or volume basis depending upon the method of
of an internal standard is unnecessary if adequate calibration
reporting. One method of adding the internal standard that has
has been performed and the composition of the C and heavier
been found convenient is given in Annex A1. Alternatively,
portion does not differ significantly from that of the depenta-
quantitative results can be obtained by injecting repeatable
nized gasolines used as calibrants. An internal standard can be
quantities of the sample and of a known blend, and comparing
used periodically to assure that analytical accuracy is main-
the peak areas obtained for the sample with those obtained for
tained (Note 7). Adjust the valving so that carrier gas is flowing
the known concentration of components in the blend.
through the instrument in the normal direction. Charge suffi-
8.2.1.1 Precut Column—If a precut column is used, adjust
cient sample to ensure a minimum of 10 % recorder deflection
the valving so that carrier gas is flowing in the normal direction
for a 0.1 percent sample concentration of 2-methylbutene-2 at
through both the precut and analysis columns. Using a chilled
the highest sensitivity. As soon as the last pentene peak
syringe, charge sufficient sample to ensure a minimum of 10 %
(2-methylbutene-2) has been eluted, position the valving so
recorder deflection for a 0.1 % sample concentration of
that the carrier gas flow is reversed. After the flow has
2-methylbutene-2 at the most sensitive setting of the instru-
stabilized, adjust the base line. Attenuate for the C + portion
ment. When all of the C and lighter hydrocarbons plus internal
as necessary. The run is complete when the recorder returns to
standard, if used, have entered the analyzer column, position
the base line after elution of the C portion. This part of the
the valves so that backflushing of the precut column is
sample will generally emerge as one broad peak with only
initiated. The time at which backflushing is commenced is
slight indications of any separation. Proceed as described in
critical and may have to be determined by trial and error. If
9.1.2.
properly done, it results in the elimination of any interference
from low-boiling six-carbon paraffins and produces a chro-
NOTE 7—All reverse flow determinations, including the C and heavier
matogram that exhibits peaks for C through C paraffins and
2 5
calibration runs should be made in the same carrier gas flow direction. All
olefins only (Fig. 1). When the last compound has been eluted,
single-peak determinations and corresponding calibrations will then be
remove the chromatogram and proceed as described in 9.1.1. made in the opposite carrier gas flow direction. The column should be kept
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
...