ASTM D6296-98(2003)e1
(Test Method)Standard Test Method for Total Olefins in Spark-Ignition Engine Fuels by Multi-dimensional Gas Chromatography
Standard Test Method for Total Olefins in Spark-Ignition Engine Fuels by Multi-dimensional Gas Chromatography
SIGNIFICANCE AND USE
The quantitative determination of olefins in spark-ignition engine fuels is required to comply with government regulations.
Knowledge of the total olefin content provides a means to monitor the efficiency of catalytic cracking processes.
This test method provides better precision for olefin content than Test Method D 1319. It also provides data in a much shorter time, approximately 20 min following calibration, and maximizes automation to reduce operator labor.
This test method is not applicable to M85 or E85 fuels, which contain 85 % methanol and ethanol, respectively.
SCOPE
1.1 This test method provides for the quantitative determination of total olefins in the C4 to C10 range in spark-ignition engine fuels or related hydrocarbon streams, such as naphthas and cracked naphthas. Olefin concentrations in the range from 0.2 to 5.0 liquid-volume % or mass %, or both, can be determined directly on the as-received sample whereas olefins in samples containing higher concentrations are determined after appropriate sample dilution prior to analysis.
1.2 This test method is applicable to samples containing alcohols and ethers; however, samples containing greater than 15 % alcohol must be diluted. Samples containing greater than 5.0 % ether must also be diluted to the 5.0 % or less level, prior to analysis. When ethyl-tert-butylether is present, only olefins in the C4 to C9 range can be determined.
1.3 This test method can not be used to determine individual olefin components.
1.4 This test method can not be used to determine olefins having higher carbon numbers than C10.
Note 1—Precision was determined only on samples containing MTBE and ethanol.
1.5 The values stated in SI units are to be regarded as the standard.
1.6 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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An American National Standard
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Designation: D 6296 – 98 (Reapproved 2003)
Standard Test Method for
Total Olefins in Spark-ignition Engine Fuels by
Multidimensional Gas Chromatography
This standard is issued under the fixed designation D 6296; 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.
e NOTE—Warning notes were editorially moved into the standard text in August 2003.
1. Scope Liquids by Digital Density Meter
D 4307 PracticeforPreparationofLiquidBlendsforUseas
1.1 This test method provides for the quantitative determi-
Analytical Standards
nation of total olefins in the C to C range in spark-ignition
4 10
D 4815 Test Method for Determination of MTBE, ETBE,
engine fuels or related hydrocarbon streams, such as naphthas
TAME, DIPE, tertiary-Amyl Alcohol and C to C Alco-
1 4
and cracked naphthas. Olefin concentrations in the range from
hols in Gasoline by Gas Chromatography
0.2 to 5.0 liquid-volume % or mass %, or both, can be
D 5599 Test Method for Determination of Oxygenates in
determined directly on the as-received sample whereas olefins
Gasoline by Gas Chromatography and Oxygen Selective
in samples containing higher concentrations are determined
Flame Ionization Detection
after appropriate sample dilution prior to analysis.
1.2 This test method is applicable to samples containing
3. Terminology
alcohols and ethers; however, samples containing greater than
3.1 Definitions of Terms Specific to This Standard:
15 % alcohol must be diluted. Samples containing greater than
3.1.1 trap, n—a device utilized to selectively retain specific
5.0 %ethermustalsobedilutedtothe5.0 %orlesslevel,prior
portions (individual or groups of hydrocarbons or oxygenates)
to analysis. When ethyl-tert-butylether is present, only olefins
of the test sample and to release the retained components by
in the C to C range can be determined.
4 9
increasing the trap temperature.
1.3 Thistestmethodcannotbeusedtodetermineindividual
3.2 Acronyms:
olefin components.
3.2.1 ETBE—ethyl-tert-butylether.
1.4 This test method can not be used to determine olefins
3.2.2 MTBE—methyl-tert–butylether.
having higher carbon numbers than C .
4. Summary of Test Method
NOTE 1—Precision was determined only on samples containing MTBE
and ethanol.
4.1 A reproducible 0.2-µL volume of a representative
1.5 The values stated in SI units are to be regarded as the sample, or a dilution thereof, is introduced into a computer
standard.
controlled gas chromatographic system consisting of a series
1.6 This standard does not purport to address all of the of columns, traps, and switching valves operating at various
safety concerns, if any, associated with its use. It is the
temperatures. The valves are actuated at predetermined times
responsibility of the user of this standard to establish appro- to direct portions of the sample to appropriate columns and
priate safety and health practices and determine the applica-
traps. The sample first passes through a polar column that
bility of regulatory limitations prior to use. retains C + hydrocarbons, all aromatics, C + olefins, and
12 11
some alcohols, all of which are subsequently backflushed to
2. Referenced Documents
vent. The fraction eluting from the polar column, which
2.1 ASTM Standards:
contains C and lower boiling saturated hydrocarbons as well
D 1319 Test Method for Hydrocarbon Types in Liquid
asdeceneandlowerboilingolefins,entersanether/alcoholtrap
Petroleum Products by Fluorescent Indicator Adsorption
where the ethers and alcohols are selectively retained and also
D 4052 Test Method for Density and Relative Density of
Annual Book of ASTM Standards, Vol 05.02.
1 4
This test method is under the jurisdiction of ASTM Committee D02 on Annual Book of ASTM Standards, Vol 05.03.
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee The sole source of supply of apparatus known to the committee at this time, the
D02.04 on Hydrocarbon Analysis. AC FTO Analyzer, is AC Analytical Controls, Inc., 3494 Progress Dr., Bensalem,
Current edition approved May 10, 2003. Published August 2003. Originally PA19020. If you are aware of alternative suppliers, please provide this information
approved in 1998. Last previous edition approved in 1998 as D 6296–98. to ASTM Headquarters. Your comments will receive careful consideration at a
Annual Book of ASTM Standards, Vol 05.01. meeting of the responsible technical committee, which you may attend.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D 6296 – 98 (2003)
FIG. 1 Typical Flow Diagram and Component Configuration
subsequently backflushed. The fraction eluting from the ether/ 6. Interferences
alcohol trap, which consists of C and lower boiling saturated
6.1 Some types of sulfur-containing compounds are irre-
hydrocarbons and the olefins, enters an olefin trap. The olefins
versibly absorbed in the olefin and oxygenate traps ultimately
are selectively retained while the saturated hydrocarbons elute,
reducingthetrapcapacity.However,avarietyofspark-ignition
pass through a nonpolar column, and are detected by a flame
engine fuels have been analyzed without significant perfor-
ionization detector (FID). When the saturated hydrocarbons
mance deterioration of these traps.
have completely eluted to the FID, the nonpolar column oven
6.2 Commercial dyes used to distinguish between grades
is cooled and the olefins, which have been retained on the
and types of spark-ignition engine fuels have not been found to
olefin trap, are desorbed by heating.The desorbed olefins enter
interfere with this test method.
and elute from the nonpolar column, which is temperature
6.3 Commercial detergent additives utilized in spark-
programmed to separate the olefins by boiling point, and are
ignition engine fuels have not been found to interfere with this
detected by the FID.
test method.
6.4 Dissolved water in spark-ignition engine fuels has not
NOTE 2—Separation of olefins by boiling point is necessary for the
been found to interfere with this test method. Free water must
calculation of the volume % of the olefins because the density of low
be removed using anhydrous sodium sulfate or other drying
boiling olefins differs from that of high boiling olefins and, therefore, a
density correction must be applied.
agent to permit injection of accurate sample volumes.
4.2 Quantitation of the detected olefin peak areas to provide
7. Apparatus
volume % or mass %, or both, is accomplished through the use
7.1 The complete system used to obtain the precision data is
of an external standard followed by the application of flame
comprised of a computer controlled gas chromatograph, auto-
ionization detector response factors. The quantitation also
mated sample injector, computer software, and specific hard-
takes into consideration the baseline compensation, sample
ware modifications. These modifications include columns,
dilution, and density corrections.
traps, and valves which are described as follows and in Section
8. Fig. 1 illustrates a typical flow diagram and component
5. Significance and Use
configuration. Other configurations, components, or conditions
5.1 The quantitative determination of olefins in spark-
may be utilized provided they are capable of separating the
ignition engine fuels is required to comply with government
olefins and producing a precision that is equivalent, or better,
regulations.
than that shown in the table of precision data.
5.2 Knowledge of the total olefin content provides a means
7.2 Gas Chromatograph, dual column, temperature pro-
to monitor the efficiency of catalytic cracking processes.
grammable over a range from 60 to 160°C at approximately
5.3 This test method provides better precision for olefin
20°C/min, equipped with heated flash vaporization sample
content than Test Method D 1319. It also provides data in a
inlets, a single flame ionization detector, necessary flow
much shorter time, approximately 20 min following calibra-
controllers, and computer control.
tion, and maximizes automation to reduce operator labor.
7.3 Sample Introduction System, manual or automatic, ca-
5.4 This test method is not applicable to M85 or E85 fuels, pable of injecting a reproducible 0.2-µL injection volume of
which contain 85 % methanol and ethanol, respectively. liquid. The total injected sample must be introduced to the
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D 6296 – 98 (2003)
TABLE 1 Temperature Control Ranges of System Components
systems. Temperature control may be by any means that will
Typical Operating meet the requirements of Table 1.
Temperature Heating Time, min, Cooling Time, min,
NOTE 4—The system components and temperatures listed in Table 1
Component Range, °C max max
andSection8arespecifictotheanalyzerusedtoobtaintheprecisiondata.
Polar column 60 to 160 temperature
Other columns and traps that can adequately perform the required
Nonpolar column 60 to 160 programmed, ; 20°C/min
separations are also satisfactory but may require different temperatures.
Ether/alcohol trap 120 to 280 1 5
Olefin trap 155 to 280 1 5
7.11 Valves, Column, and Trap Switching—automated
Column switching 100 isothermal
Valves 6-port rotary valves are recommended. The valves must be
Sample lines 100 isothermal
intended for gas chromatographic usage and meet the follow-
ing requirements:
7.11.1 The valves must be capable of continuous operation
chromatographic system, thus excluding the use of split injec-
at operating temperatures that will prevent sample condensa-
tionsorcarriergaspurgingoftheinletseptum.Anautoinjector
tion.
is recommended but optional. The precision data was obtained
7.11.2 The valves must be constructed of materials that are
using an automated sample injector.
nonreactive with the sample under analysis conditions. Stain-
7.4 Gas Flow and Pressure Controllers, with adequate
less steel, PFA, and Vespel are satisfactory.
precision to provide reproducible flow and pressure of helium
7.11.3 The valves must have a small internal volume but
to the chromatographic system, and hydrogen and air for the
offer little restriction to carrier gas flow under analysis condi-
flame ionization detector. Control of air flow for rapid cooling
tions.
of specific system components and for automated valve opera-
7.12 Valves, Air, to control pressurized air for ether/alcohol
tion is also required.
and olefin trap cooling; 3-port automated valves are recom-
7.5 Electronic Data Acquisition System, must meet or ex-
mended.
ceed the following specifications (see Note 3):
NOTE 5—New valves, tubing, columns, traps, and other materials that
7.5.1 Capacity for 150 peaks for each analysis,
contact the sample or gasses may require conditioning prior to operation
7.5.2 External standard calculation of selected peaks with
in accordance with the manufacturer’s instructions.
response factors and background correction,
7.5.3 Noise and spike rejection capability,
8. Reagents and Materials
7.5.4 Sampling rate for fast (<4.0 s.) peaks (>5 Hz to give
8.1 Air, compressed, <10 mg/kg each of total hydrocarbons
20 points across peak),
and H O. (Warning—Compressed gas under high pressure
7.5.5 Peak width detection for narrow and broad peaks, and
that supports combustion.)
7.5.6 Perpendicular drop.
8.2 Helium, 99.999 % pure, <0.1 mg/kg HO(Warning—
Compressed gas under high pressure.)
NOTE 3—Standard supplied software is typically satisfactory.
8.3 Hydrogen, 99.999 % pure, <0.1 mg/kg H O
7.6 Gas Purifiers, to remove moisture and oxygen from
(Warning—Extremely flammable gas under high pressure.)
helium, moisture and hydrocarbons from hydrogen, and mois-
8.4 2,2,4-trimethylpenane (isooctane), 99.99 % pure
ture and hydrocarbons from air.
(Warning—Flammable. Harmful if inhaled.)
7.7 Balance, analytical, capable of weighing 0.0001 g.
8.5 Columns and Traps (System Components)—This test
7.8 Glassware:
method requires the use of two chromatographic columns and
7.8.1 Vial, autosampler, with caps and including a cap
two traps (see Note 4). Each system component is indepen-
crimper (required when the recommended optional autosam-
dently temperature controlled as described in 7.10 andTable 1.
pler is used).
Refer to Fig. 1 for the location of the components in the
7.8.2 Pipette, Pasteur, disposable, with bulb.
system. The following list of columns and traps contains
7.8.3 Pipette, volumetric, graduated in 0.01 mLincrements,
guidelines that are to be used to judge suitability.
1- and 2-mL capacity.
8.5.1 Polar Column—At a temperature of 160°C, this
7.8.4 Pipette, total volume, 1, 3, 5, 10, 20 and 25-mL
column must retain all aromatic components in the sample and
capacity.
elute all nonaromatic components boiling below 200°C, which
7.9 Septa, polytetrafluoroethylene (PTFE) lined for injector.
includes decene and lower boiling olefins, within 2 min after
7.10 Temperature Controllers of System Components—The
sample injection.
independenttemperaturecontroloftwocolumnsandtwotraps,
8.5.1.1 This column must elute all aromatics and other
column switching valves, and sample lines is required. All
components retained from 8.5.1 within 8 min of when it is
system components that contact the sample must be heated to
backflushed.
a temperature that will prevent condensation of any sample
8.5.2 Ether/Alcohol Trap—At a temperature of 140°C, this
component. Table 1 lists the system components and operating
trap must retain alcohols and ethers and elute all non-
temperature (see Note 4). Some of the components require
oxygenates boiling below 200°C within 4.5 to 5.0 min after
isothermal operation, some require rapid heating and cooling,
sample injection.
while one requires reproducible temperature programming.
The indicated temperatures are typical; however, the control
systems utilized must have the capability of operating at
temperatures 620° of those indicated to accommodate specific PFA and Vespel are trade marks of E.I. DuPont de Nemours and Co.
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D 6296 – 98 (2003)
TABLE 2 Set Up Mixtures TABLE 3 Calibration Standard 1 Containing MTBE
Mixture Approximate Component Density, kg/L Mass % Volume %
No. Component Concentrations, mass %
Pentene 0.6452 1.00 1.09
1 methyl-tert-butylether (MTBE) 5 Hexene 0.6763 1.00 1.04
isooctane 95 Heptene 0.7009 1.00 1.00
Octene 0.7186 1.00 0.98
2 ethyl-tert-butylether (ETBE) 5 Nonene 0.7329 1.00 0.96
isooctane 95 Decene 0.7440 1.00 0.94
Undecane 0.7438 1.00 0.94
Dodecane 0.7521 1.00 0.93
Isooctane 0.6985 87.00 87.41
MTBE 0.7451
...
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