ASTM D6729-01
(Test Method)Standard Test Method for Determination of Individual Components in Spark Ignition Engine Fuels by 100 Meter Capillary High Resolution Gas Chromatography
Standard Test Method for Determination of Individual Components in Spark Ignition Engine Fuels by 100 Meter Capillary High Resolution Gas Chromatography
SCOPE
1.1 This test method covers the determination of individual hydrocarbon components of spark-ignition engine fuels and their mixtures containing oxygenate blends (MTBE, ETBE, ethanol, and so forth) with boiling ranges up to 225C. Other light liquid hydrocarbon mixtures typically encountered in petroleum refining operations, such as blending stocks (naphthas, reformates, alkylates, and so forth) may also be analyzed; however, statistical data was obtained only with blended spark-ignition engine fuels.
1.2 Based on the cooperative study results, individual component concentrations and precision are determined in the range of 0.01 to approximately 30 mass %. The procedure may be applicable to higher and lower concentrations for the individual components; however, the user must verify the accuracy if the procedure is used for components with concentrations outside the specified ranges.
1.3 The test method also determines methanol, ethanol, t-butanol, methyl t-butyl ether (MTBE), ethyl t-butyl ether (ETBE), t-amyl methyl ether (TAME) in spark ignition engine fuels in the concentration range of 1 to 30 mass %. However, the cooperative study data provided sufficient statistical data for MTBE only.
1.4 Although a majority of the individual hydrocarbons present are determined, some co-elution of compounds is encountered. If this test method is utilized to estimate bulk hydrocarbon group-type composition (PONA) the user of such data should be cautioned that some error will be encountered due to co-elution and a lack of identification of all components present. Samples containing significant amounts of olefinic or naphthenic (for example, virgin naphthas), or both, constituents above n-octane may reflect significant errors in PONA type groupings. Based on the gasoline samples in the interlaboratory cooperative study, this procedure is applicable to samples containing less than 25 mass % of olefins. However, some interfering coelution with the olefins above C7 is possible, particularly if blending components or their higher boiling cuts such as those derived from fluid catalytic cracking (FCC) are analyzed, and the total olefin content may not be accurate.
1.4.1 Total olefins in the samples may be obtained or confirmed, or both, if necessary, by Test Method D 1319 (volume %) or other test methods, such as those based on multidimensional PONA type of instruments.
1.5 If water is or is suspected of being present, its concentration may be determined, if desired, by the use of Test Method D 1744, or equivalent. Other compounds containing oxygen, sulfur, nitrogen, and so forth, may also be present, and may co-elute with the hydrocarbons. If determination of these specific compounds is required, it is recommended that test methods for these specific materials be used, such as Test Methods D 4815 and D 5599 for oxygenates, and D 5623 for sulfur compounds, or equivalent.
1.6 of this test method compares results of the test procedure with other test methods for selected components, including olefins, and several group types for several interlaboratory cooperative study samples. Although benzene, toluene, and several oxygenates are determined, when doubtful as to the analytical results of these components, confirmatory analyses can be obtained by using specific test methods.
1.7 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information purposes only.
1.8 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
Designation: D 6729 – 01
Standard Test Method for
Determination of Individual Components in Spark Ignition
Engine Fuels by 100 Meter Capillary High Resolution Gas
Chromatography
This standard is issued under the fixed designation D 6729; 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 boiling cuts such as those derived from fluid catalytic cracking
(FCC) are analyzed, and the total olefin content may not be
1.1 This test method covers the determination of individual
accurate.
hydrocarbon components of spark-ignition engine fuels and
1.4.1 Total olefins in the samples may be obtained or
their mixtures containing oxygenate blends (MTBE, ETBE,
confirmed, or both, if necessary, by Test Method D 1319
ethanol, and so forth) with boiling ranges up to 225°C. Other
(volume %) or other test methods, such as those based on
light liquid hydrocarbon mixtures typically encountered in
multidimensional PONA type of instruments.
petroleum refining operations, such as blending stocks (naph-
1.5 If water is or is suspected of being present, its concen-
thas, reformates, alkylates, and so forth) may also be analyzed;
tration may be determined, if desired, by the use of Test
however, statistical data was obtained only with blended
Method D 1744, or equivalent. Other compounds containing
spark-ignition engine fuels.
oxygen, sulfur, nitrogen, and so forth, may also be present, and
1.2 Based on the cooperative study results, individual com-
may co-elute with the hydrocarbons. If determination of these
ponent concentrations and precision are determined in the
specific compounds is required, it is recommended that test
range of 0.01 to approximately 30 mass %.The procedure may
methods for these specific materials be used, such as Test
be applicable to higher and lower concentrations for the
Methods D 4815 and D 5599 for oxygenates, and D 5623 for
individual components; however, the user must verify the
sulfur compounds, or equivalent.
accuracy if the procedure is used for components with concen-
1.6 Annex A1 of this test method compares results of the
trations outside the specified ranges.
test procedure with other test methods for selected compo-
1.3 The test method also determines methanol, ethanol,
nents, including olefins, and several group types for several
t-butanol, methyl t-butyl ether (MTBE), ethyl t-butyl ether
interlaboratory cooperative study samples. Although benzene,
(ETBE), t-amyl methyl ether (TAME) in spark ignition engine
toluene, and several oxygenates are determined, when doubtful
fuels in the concentration range of 1 to 30 mass %. However,
as to the analytical results of these components, confirmatory
the cooperative study data provided sufficient statistical data
analyses can be obtained by using specific test methods.
for MTBE only.
1.7 The values stated in SI units are to be regarded as the
1.4 Although a majority of the individual hydrocarbons
standard. The values given in parentheses are provided for
present are determined, some co-elution of compounds is
information purposes only.
encountered. If this test method is utilized to estimate bulk
1.8 This standard does not purport to address all of the
hydrocarbon group-type composition (PONA) the user of such
safety concerns, if any, associated with its use. It is the
data should be cautioned that some error will be encountered
responsibility of the user of this standard to establish appro-
due to co-elution and a lack of identification of all components
priate safety and health practices and determine the applica-
present. Samples containing significant amounts of olefinic or
bility of regulatory limitations prior to use.
naphthenic (for example, virgin naphthas), or both, constitu-
ents above n-octane may reflect significant errors in PONA
2. Referenced Documents
type groupings. Based on the gasoline samples in the inter-
2.1 ASTM Standards:
laboratory cooperative study, this procedure is applicable to
D 1319 Test Method for Hydrocarbon Types in Liquid
samples containing less than 25 mass % of olefins. However,
Petroleum Products by Fluorescent Indicator Adsorption
some interfering coelution with the olefins above C is pos-
D 1744 Test Method for Determination of Water in Liquid
sible, particularly if blending components or their higher
Petroleum Products by Karl Fisher Reagent
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricantsand is the direct responsibility of Subcommittee
D02.04 on Hydrocarbon Analysis. Annual Book of ASTM Standards, Vol 05.01.
Current edition approved Nov. 10, 2001. Published January 2002. Discontinued; see 1999 Annual Book of ASTM Standards, Vol 05.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 6729
D 4815 Test Method for Determination of MTBE, ETBE, 6.2 Inlet—a capillary split/splitless inlet system operated in
TAME, DIPE, t-Amyl Alcohol and C to C Alcohols in thesplitmodeisrecommended.Itmustbeoperatedinitslinear
1 4
Gasoline by Gas Chromatography range. Refer to 8.4 to determine the proper split ratio.
D 5599 Test Method for Determination of Oxygenates in 6.2.1 Carrier Gas Pneumatic Control—Constant carrier gas
Gasoline by Gas Chromatography and Oxygen Selective pressurecontrolwasusedbyallcooperativestudyparticipants.
Flame Ionization Detection This may be either direct pressure to the inlet (injector) or by
D 5623 Test Method for Sulfur Compounds in Light Petro- using a total flow/back pressure system.
leum Liquids by Gas Chromatography and Sulfur Selec- 6.2.2 Pneumatic Operation of the Chromatograph—The
tive Detection use of constant pressure was the mode of operating the gas
E 355 Practice for Gas Chromatography Terms and Rela- chromatography used by the participants in the interlaboratory
tionships cooperative study. Other carrier gas control methods such as
constant flow (pressure programming) may be used, but this
3. Terminology
may change the chromatography elution pattern unless the
temperature programming profile is also adjusted to compen-
3.1 Definitions—This test method makes reference to many
sate for the flow differences.
common gas chromatographic procedures, terms, and relation-
6.2.3 Temperature Control—The injector operated in the
ships. Detailed definitions can be found in Practice E 355.
split mode shall be heated by a separate heating zone and
heated to temperatures of 200 to 275°C.
4. Summary of Test Method
6.3 Column,afusedsilicacapillarycolumn,100minlength
4.1 Representative samples of the petroleum liquid are
by 0.25 mm inside diameter, coated with a 0.5 mm film of
introduced into a gas chromatograph equipped with an open
bonded dimethylpolysiloxane. The column must meet the
tubular (capillary) column coated with the specified stationary
resolution requirements expressed in 8.3. Columns from two
phase. Helium carrier gas transports the vaporized sample
different commercial sources were used in the interlaboratory
through the column, in which it is partitioned into individual
cooperative study.
components which are sensed with a flame ionization detector
6.4 Data System, a computer based chromatography data
as they elute from the end of the column. The detector signal
system capable of accurately and repeatedly measuring the
is recorded digitally by way of an integrator or integrating
retention time and areas of eluting peaks. The system shall be
computer. Each eluting component is identified by comparing
abletoacquiredataatarateofatleast10Hz.Althoughitisnot
its retention time to that established by analyzing reference
mandatory, a data system which calculates column resolution
standards or samples under identical conditions. The concen-
(R) is extremely useful as it will replace the need to carry out
tration of each component in mass % is determined by
the manual calculations which must be performed as listed in
normalization of the peak areas after correction of selected
8.3.
components with detector response factors. The unknown
6.4.1 Electronic Integrators, shall be capable of storing up
components are reported individually and as a summary total.
to 400 components in the peak table and shall be able to
acquire the data at 10 Hz or faster speeds. They shall be
5. Significance and Use
capable of integrating peaks having peak widths at half height
5.1 Knowledge of the specified individual component com-
which are 1.0s wide. The integrator must be capable of
position (speciation) of gasoline fuels and blending stocks is
displaying the integration mode of partially resolved peaks. In
useful for refinery quality control and product specification.
addition, these integrators should be able to download a
Process control and product specification compliance for many
commonly readable format of data (that is, ASCII) to a
individual hydrocarbons may be determined through the use of
computer in order to facilitate data processing.
this test method.
6.5 Sample Introduction—Sample introduction by way of a
valve, automatic injection device, robotic arm or other auto-
6. Apparatus
matic means is highly recommended. An automatic sample
6.1 Gas Chromatograph, a gas chromatograph equipped
introduction device is essential to the reproducibility of the
with cryogenic column oven cooling and capable of producing
analysis. Manual injections are not recommended. All of the
repeatable oven ramps from 0° to at least 300°C is required.
reproducibility data reported by this test method for the
The following features are useful during the sample analysis
samples analyzed were gathered using automatic injection
phase: electronic flow readout, electronic sample split-ratio
devices.
readout,andelectronicpneumaticcontrolofflow.Thoughtheir
6.6 Flame Ionization Detector (FID)—The gas chromato-
use is not required, careful review of this test method will
graph should possess a FID having a sensitivity of 0.005
demonstrate the usefulness of a gas chromatograph equipped
coulombs/g for n-butane. The linear dynamic range of the
with these features. These features will replace the need to 6
detector should be 10 or better. The detector is heated to
carry out the manual calculations that must be performed as
300°C.
listed in 8.1 and 8.2.
7. Reagents and Materials
7.1 Calibrating Standard Mixture—Aspark ignition engine
fuelstandardofknowncompositionandconcentrationbymass
Annual Book of ASTM Standards, Vol 05.03.
Annual Book of ASTM Standards, Vol 14.02. can be used. In order to corroborate the identification of the
D 6729
sample, a typical chromatogram (Fig. 1) was obtained from 7.2 Gas Chromatograph Gases—All of the following gases
reference sample ARC96OX. shall have a purity of 99.999 % (V/V) or greater.
NOTE 1—Warning: Gasesarecompressed.Someareflammableandall
gases are under high pressure.
Reference spark ignition sample No. ARC 960X obtained from the Alberta
7.2.1 Helium—The test data was developed with helium as
Research Council, Edmonton, Alberta, Canada. Other samples are available from
the carrier gas. It is possible that other carrier gases may be
suppliers.
FIG. 1 Chromatogram for Reference Spiked Gasoline
D 6729
FIG. 1 Chromatogram for Reference Spiked Gasoline (continued)
usedforthistestmethod.Atthistime,nodataisavailablefrom 8. Instrument Check Out Prior to Analysis
this test method with other carrier gases.
8.1 Setting:
7.2.2 Air, Hydrogen and Make-up Gas (Helium or Nitro-
gen), shall have a purity of 99.999 % (V/V) or greater.
D 6729
FIG. 1 Chromatogram for Reference Spiked Gasoline (continued)
8.1.1 Linear Gas Velocity—If the gas chromatograph is linear velocity of 25 to 26 cm/s. This is equivalent to retention
times of methane at 0°C ranging from 6.5 to 6.8 min.
equippedwithanelectronicflowreadoutdevice,settheflowto
1.8 mL/min. This is achieved by setting the carrier gas flow
8.1.2 If the gas chromatograph is not equipped with an
rate by injection of methane or natural gas at 35°C. Ensure that
electronic flow readout device, calculate the linear gas velocity
the retention time is 7.00 6 0.05 min. This corresponds to a in cm/s using Eq 1.
D 6729
FIG. 1 Chromatogram for Reference Spiked Gasoline (continued)
column length ~cm!
split ratio to a sample split of 200:1. If the gas chromatograph
linear gas velocity 5 V 5 (1)
retention time of methane~s!
is not equipped with an electronic split-ratio readout device,
one must first calculate column flow rate and then proceed to
8.1.3 The typical retention times for methane and linear gas
velocity for helium are 6.5 to 6.8 and 24 to 26 cm/s, calculating split ratio using Eq 2 and 3.
respectively.
~60 p r ! L~T !2~P – P !
ref i o
8.2 Setting the Split Ratio—If the gas chromatograph is column flow rate 5 F 5 (2)
2 2
T!3 P ! P – P !µ
~ ~ ~
ref i o
equipped with an electronic split-ratio readout device, set the
D 6729
FIG. 1 Chromatogram for Reference Spiked Gasoline (continued)
D 6729
FIG. 1 Chromatogram for Reference Spiked Gasoline (continued)
D 6729
FIG. 1 Chromatogram for Reference Spiked Gasoline (continued)
where: P = outlet pressure,
o
F = flow rate as calculated by using the equation, P = reference pressure, 1 atm,
ref
r = column radius, cm, T = temperature of the column oven,
L = column length, cm, T = temperature at the column outlet, and
ref
P = inlet pressure, µ = linear velocity, cm/s.
i
D 6729
split vent flow 1 F TABLE 2 Resolution Performance Requirements
split ratio 5 S 5 (3)
F
Component Minimum Concentration of Each
Pair Resolution Component, W/W
8.2.1 The column flow rate is calculated by the use of Eq 2.
Benzene 1.0 0.5 %–0.5 %
Use the results obtained from Eq 3 to adjust the split flow until
1-Methyl-cyclopentene
a split flow of approximately 200:1 is achieved.
m-Xylene 0.4 2.0 %–2.0 %
p-Xylene
8.3 Evaluation of Column Performance:
n-Tridecane 1.0 0.5 %–0.5 %
8.3.1 Prior to using the column described in Table 1,
1-Methylnaphthalene
measure the resolution of the column under the conditions of
Table 2. Check that the resolution for the following pairs of
components is obtained using Eq 4 to calc
...
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