ASTM D6296-98(2008)
(Test Method)Standard Test Method for Total Olefins in Spark-ignition Engine Fuels by Multidimensional Gas Chromatography
Standard Test Method for Total Olefins in Spark-ignition Engine Fuels by Multidimensional 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 standard. No other units of measurement are included in this 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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Standards Content (Sample)
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Designation:D6296 −98(Reapproved 2008)
Standard Test Method for
Total Olefins in Spark-ignition Engine Fuels by
Multidimensional Gas Chromatography
This standard is issued under the fixed designation D6296; 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 2. Referenced Documents
1.1 This test method provides for the quantitative determi- 2.1 ASTM Standards:
nation of total olefins in the C to C range in spark-ignition D1319 Test Method for Hydrocarbon Types in Liquid Petro-
4 10
engine fuels or related hydrocarbon streams, such as naphthas leum Products by Fluorescent Indicator Adsorption
and cracked naphthas. Olefin concentrations in the range from D4052 Test Method for Density, Relative Density, and API
0.2 to 5.0 liquid-volume % or mass %, or both, can be Gravity of Liquids by Digital Density Meter
determined directly on the as-received sample whereas olefins D4307 Practice for Preparation of Liquid Blends for Use as
in samples containing higher concentrations are determined Analytical Standards
after appropriate sample dilution prior to analysis. D4815 Test Method for Determination of MTBE, ETBE,
TAME, DIPE, tertiary-Amyl Alcohol and C to C Alco-
1 4
1.2 This test method is applicable to samples containing
hols in Gasoline by Gas Chromatography
alcohols and ethers; however, samples containing greater than
D5599 Test Method for Determination of Oxygenates in
15 % alcohol must be diluted. Samples containing greater than
Gasoline by Gas Chromatography and Oxygen Selective
5.0 %ethermustalsobedilutedtothe5.0 %orlesslevel,prior
Flame Ionization Detection
to analysis. When ethyl-tert-butylether is present, only olefins
in the C to C range can be determined.
4 9 3. Terminology
1.3 Thistestmethodcannotbeusedtodetermineindividual
3.1 Definitions of Terms Specific to This Standard:
olefin components.
3.1.1 trap, n—a device utilized to selectively retain specific
portions (individual or groups of hydrocarbons or oxygenates)
1.4 This test method can not be used to determine olefins
of the test sample and to release the retained components by
having higher carbon numbers than C .
increasing the trap temperature.
NOTE 1—Precision was determined only on samples containing MTBE
and ethanol. 3.2 Acronyms:
3.2.1 ETBE—ethyl-tert-butylether.
1.5 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this 3.2.2 MTBE—methyl-tert–butylether.
standard.
4. Summary of Test Method
1.6 This standard does not purport to address all of the
4.1 A reproducible 0.2-µL volume of a representative
safety concerns, if any, associated with its use. It is the
sample, or a dilution thereof, is introduced into a computer
responsibility of the user of this standard to establish appro-
controlled gas chromatographic system consisting of a series
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
This test method is under the jurisdiction of ASTM Committee D02 on the ASTM website.
Petroleum Products and Lubricantsand is the direct responsibility of Subcommittee The sole source of supply of apparatus known to the committee at this time, the
D02.04.0L on Gas Chromatography Methods. AC FTO Analyzer, is AC Analytical Controls, Inc., 3494 Progress Dr., Bensalem,
Current edition approved May 1, 2008. Published September 2008. Originally PA19020. If you are aware of alternative suppliers, please provide this information
´1
approved in 1998. Last previous edition approved in 2003 as D6296–98(2003) . to ASTM Headquarters. Your comments will receive careful consideration at a
DOI: 10.1520/D6296-98R08. 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
D6296−98 (2008)
FIG. 1Typical Flow Diagram and Component Configuration
of columns, traps, and switching valves operating at various 5.2 Knowledge of the total olefin content provides a means
temperatures. The valves are actuated at predetermined times to monitor the efficiency of catalytic cracking processes.
to direct portions of the sample to appropriate columns and
5.3 This test method provides better precision for olefin
traps. The sample first passes through a polar column that
content than Test Method D1319. It also provides data in a
retains C + hydrocarbons, all aromatics, C + olefins, and
12 11
much shorter time, approximately 20 min following calibra-
some alcohols, all of which are subsequently backflushed to
tion, and maximizes automation to reduce operator labor.
vent. The fraction eluting from the polar column, which
5.4 This test method is not applicable to M85 or E85 fuels,
contains C and lower boiling saturated hydrocarbons as well
which contain 85 % methanol and ethanol, respectively.
asdeceneandlowerboilingolefins,entersanether/alcoholtrap
where the ethers and alcohols are selectively retained and also
6. Interferences
subsequently backflushed. The fraction eluting from the ether/
alcohol trap, which consists of C and lower boiling saturated 6.1 Some types of sulfur-containing compounds are irre-
versibly absorbed in the olefin and oxygenate traps ultimately
hydrocarbons and the olefins, enters an olefin trap. The olefins
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
andtypesofspark-ignitionenginefuelshavenotbeenfoundto
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.
NOTE 2—Separation of olefins by boiling point is necessary for the
6.4 Dissolved water in spark-ignition engine fuels has not
calculation of the volume % of the olefins because the density of low
been found to interfere with this test method. Free water must
boiling olefins differs from that of high boiling olefins and, therefore, a
density correction must be applied.
be removed using anhydrous sodium sulfate or other drying
agent to permit injection of accurate sample volumes.
4.2 Quantitation of the detected olefin peak areas to provide
volume % or mass %, or both, is accomplished through the use
7. Apparatus
of an external standard followed by the application of flame
ionization detector response factors. The quantitation also
7.1 Thecompletesystemusedtoobtaintheprecisiondatais
takes into consideration the baseline compensation, sample
comprised of a computer controlled gas chromatograph, auto-
dilution, and density corrections.
mated sample injector, computer software, and specific hard-
ware modifications. These modifications include columns,
5. Significance and Use
traps, and valves which are described as follows and in Section
5.1 The quantitative determination of olefins in spark- 8. Fig. 1 illustrates a typical flow diagram and component
ignition engine fuels is required to comply with government configuration. Other configurations, components, or conditions
regulations. may be utilized provided they are capable of separating the
D6296−98 (2008)
TABLE 1 Temperature Control Ranges of System Components
olefins and producing a precision that is equivalent, or better,
than that shown in the table of precision data. Typical Operating
Temperature Heating Time, min, Cooling Time, min,
7.2 Gas Chromatograph, dual column, temperature pro-
Component Range, °C max max
Polar column 60 to 160 temperature
grammable over a range from 60 to 160°C at approximately
Nonpolar column 60 to 160 programmed, ; 20°C/min
20°C/min, equipped with heated flash vaporization sample
Ether/alcohol trap 120 to 280 1 5
inlets, a single flame ionization detector, necessary flow
Olefin trap 155 to 280 1 5
Column switching 100 isothermal
controllers, and computer control.
Valves
7.3 Sample Introduction System , manual or automatic, Sample lines 100 isothermal
capable of injecting a reproducible 0.2-µL injection volume of
liquid. The total injected sample must be introduced to the
chromatographic system, thus excluding the use of split injec-
systems utilized must have the capability of operating at
tionsorcarriergaspurgingoftheinletseptum.Anautoinjector
temperatures 620° of those indicated to accommodate specific
is recommended but optional. The precision data was obtained
systems. Temperature control may be by any means that will
using an automated sample injector.
meet the requirements of Table 1.
7.4 Gas Flow and Pressure Controllers , with adequate
NOTE 4—The system components and temperatures listed in Table 1
precision to provide reproducible flow and pressure of helium
andSection8arespecifictotheanalyzerusedtoobtaintheprecisiondata.
to the chromatographic system, and hydrogen and air for the
Other columns and traps that can adequately perform the required
flame ionization detector. Control of air flow for rapid cooling separations are also satisfactory but may require different temperatures.
of specific system components and for automated valve opera-
7.11 Valves, Column, and Trap Switching —automated
tion is also required.
6-port rotary valves are recommended. The valves must be
intended for gas chromatographic usage and meet the follow-
7.5 Electronic Data Acquisition System, must meet or ex-
ing requirements:
ceed the following specifications (see Note 3):
7.11.1 The valves must be capable of continuous operation
7.5.1 Capacity for 150 peaks for each analysis,
at operating temperatures that will prevent sample condensa-
7.5.2 External standard calculation of selected peaks with
tion.
response factors and background correction,
7.11.2 The valves must be constructed of materials that are
7.5.3 Noise and spike rejection capability,
nonreactive with the sample under analysis conditions. Stain-
7.5.4 Sampling rate for fast (<4.0 s.) peaks (>5 Hz to give
less steel, PFA, and Vespel are satisfactory.
20 points across peak),
7.11.3 The valves must have a small internal volume but
7.5.5 Peak width detection for narrow and broad peaks, and
offer little restriction to carrier gas flow under analysis condi-
7.5.6 Perpendicular drop.
tions.
NOTE 3—Standard supplied software is typically satisfactory.
7.12 Valves, Air, to control pressurized air for ether/alcohol
7.6 Gas Purifiers, to remove moisture and oxygen from
and olefin trap cooling; 3-port automated valves are recom-
helium, moisture and hydrocarbons from hydrogen, and mois-
mended.
ture and hydrocarbons from air.
NOTE 5—New valves, tubing, columns, traps, and other materials that
7.7 Balance, analytical, capable of weighing 0.0001 g.
contact the sample or gasses may require conditioning prior to operation
in accordance with the manufacturer’s instructions.
7.8 Glassware:
7.8.1 Vial, autosampler, with caps and including a cap
8. Reagents and Materials
crimper (required when the recommended optional autosam-
8.1 Air, compressed, <10 mg/kg each of total hydrocarbons
pler is used).
and H O. (Warning—Compressed gas under high pressure
7.8.2 Pipette, Pasteur, disposable, with bulb. 2
that supports combustion.)
7.8.3 Pipette, volumetric, graduated in 0.01 mLincrements,
1- and 2-mL capacity.
8.2 Helium, 99.999 % pure, <0.1 mg/kg HO(Warning—
7.8.4 Pipette, total volume, 1, 3, 5, 10, 20 and 25-mL
Compressed gas under high pressure.)
capacity.
8.3 Hydrogen, 99.999 % pure, <0.1 mg/kg H O
7.9 Septa, polytetrafluoroethylene (PTFE) lined for injector.
(Warning—Extremely flammable gas under high pressure.)
7.10 Temperature Controllers of System Components—The 8.4 2,2,4-trimethylpenane (isooctane) , 99.99 % pure
independenttemperaturecontroloftwocolumnsandtwotraps,
(Warning—Flammable. Harmful if inhaled.)
column switching valves, and sample lines is required. All
8.5 Columns and Traps (System Components) —This test
system components that contact the sample must be heated to
method requires the use of two chromatographic columns and
a temperature that will prevent condensation of any sample
two traps (see Note 4). Each system component is indepen-
component. Table 1 lists the system components and operating
dently temperature controlled as described in 7.10 and Table 1.
temperature (see Note 4). Some of the components require
Refer to Fig. 1 for the location of the components in the
isothermal operation, some require rapid heating and cooling,
while one requires reproducible temperature programming.
The indicated temperatures are typical; however, the control PFA and Vespel are trademarks of E.I. DuPont de Nemours and Co.
D6296−98 (2008)
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 5.00 4.71
system. The following list of columns and traps contains
Total 100.00 100.00
guidelines that are to be used to judge suitability.
8.5.1 Polar Column—At a temperature of 160°C, this col-
umn must retain all aromatic components in the sample and
TABLE 4 Calibration Standard 2 Containing ETBE
elute all nonaromatic components boiling below 200°C, which
Component Density, kg/L Mass % Volume %
Pentene 0.6452 1.00 1.09
includes decene and lower boiling olefins, within 2 min after
Hexene 0.6763 1.00 1.04
sample injection.
Heptene 0.7009 1.00 1.00
8.5.1.1 This column must elute all aromatics and other
...
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