1、Designation: D 6729 04e1An American National StandardStandard Test Method forDetermination of Individual Components in Spark IgnitionEngine Fuels by 100 Metre Capillary High Resolution GasChromatography1This standard is issued under the fixed designation D 6729; the number immediately following the
2、designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTECorrected 6.3 editorially in Ma
3、rch 2008.1. Scope*1.1 This test method covers the determination of individualhydrocarbon components of spark-ignition engine fuels andtheir mixtures containing oxygenate blends (MTBE, ETBE,ethanol, and so forth) with boiling ranges up to 225C. Otherlight liquid hydrocarbon mixtures typically encount
4、ered inpetroleum refining operations, such as blending stocks (naph-thas, reformates, alkylates, and so forth) may also be analyzed;however, statistical data was obtained only with blendedspark-ignition engine fuels.1.2 Based on the cooperative study results, individual com-ponent concentrations and
5、 precision are determined in therange of 0.01 to approximately 30 mass %. The procedure maybe applicable to higher and lower concentrations for theindividual components; however, the user must verify theaccuracy if the procedure is used for components with concen-trations outside the specified range
6、s.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 enginefuels in the concentration range of 1 to 30 mass %. However,the cooperative study data provided sufficient statistical datafor
7、 MTBE only.1.4 Although a majority of the individual hydrocarbonspresent are determined, some co-elution of compounds isencountered. If this test method is utilized to estimate bulkhydrocarbon group-type composition (PONA) the user of suchdata should be cautioned that some error will be encounteredd
8、ue to co-elution and a lack of identification of all componentspresent. Samples containing significant amounts of olefinic ornaphthenic (for example, virgin naphthas), or both, constitu-ents above n-octane may reflect significant errors in PONAtype groupings. Based on the gasoline samples in the int
9、er-laboratory cooperative study, this procedure is applicable tosamples containing less than 25 mass % of olefins. However,some interfering coelution with the olefins above C7is pos-sible, particularly if blending components or their higherboiling cuts such as those derived from fluid catalytic crac
10、king(FCC) are analyzed, and the total olefin content may not beaccurate.1.4.1 Total olefins in the samples may be obtained orconfirmed, or both, if necessary, by Test Method D 1319(volume %) or other test methods, such as those based onmultidimensional PONA type of instruments.1.5 If water is or is
11、suspected of being present, its concen-tration may be determined, if desired, by the use of TestMethod D 1744, or equivalent. Other compounds containingoxygen, sulfur, nitrogen, and so forth, may also be present, andmay co-elute with the hydrocarbons. If determination of thesespecific compounds is r
12、equired, it is recommended that testmethods for these specific materials be used, such as TestMethods D 4815 and D 5599 for oxygenates, and D 5623 forsulfur compounds, or equivalent.1.6 Annex A1 of this test method compares results of thetest procedure with other test methods for selected compo-nent
13、s, including olefins, and several group types for severalinterlaboratory cooperative study samples. Although benzene,toluene, and several oxygenates are determined, when doubtfulas to the analytical results of these components, confirmatoryanalyses can be obtained by using specific test methods.1.7
14、The values stated in SI units are to be regarded as thestandard. The values given in parentheses are provided forinformation purposes only.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04.0L o
15、n Gas Chromatography Methods.Current edition approved Nov. 1, 2004. Published November 2004. Originallyapproved in 2001. Last previous edition approved in 2001 as D 672901.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C
16、700, West Conshohocken, PA 19428-2959, United States.1.8 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility o
17、f regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1319 Test Method for Hydrocarbon Types in LiquidPetroleum Products by Fluorescent Indicator AdsorptionD 1744 Test Method for Determination of Water in LiquidPetroleum Products by Karl Fisher Reagent3D 4815 Test Method
18、 for Determination of MTBE, ETBE,TAME, DIPE, t-Amyl Alcohol and C1to C4Alcohols inGasoline by Gas ChromatographyD 5599 Test Method for Determination of Oxygenates inGasoline by Gas Chromatography and Oxygen SelectiveFlame Ionization DetectionD 5623 Test Method for Sulfur Compounds in Light Petro-leu
19、m Liquids by Gas Chromatography and Sulfur Selec-tive DetectionE 355 Practice for Gas Chromatography Terms and Rela-tionships3. Terminology3.1 DefinitionsThis test method makes reference to manycommon gas chromatographic procedures, terms, and relation-ships. Detailed definitions can be found in Pra
20、ctice E 355.4. Summary of Test Method4.1 Representative samples of the petroleum liquid areintroduced into a gas chromatograph equipped with an opentubular (capillary) column coated with the specified stationaryphase. Helium carrier gas transports the vaporized samplethrough the column, in which it
21、is partitioned into individualcomponents which are sensed with a flame ionization detectoras they elute from the end of the column. The detector signalis recorded digitally by way of an integrator or integratingcomputer. Each eluting component is identified by comparingits retention time to that est
22、ablished by analyzing referencestandards or samples under identical conditions. The concen-tration of each component in mass % is determined bynormalization of the peak areas after correction of selectedcomponents with detector response factors. The unknowncomponents are reported individually and as
23、 a summary total.5. Significance and Use5.1 Knowledge of the specified individual component com-position (speciation) of gasoline fuels and blending stocks isuseful for refinery quality control and product specification.Process control and product specification compliance for manyindividual hydrocar
24、bons may be determined through the use ofthis test method.6. Apparatus6.1 Gas Chromatograph, a gas chromatograph equippedwith cryogenic column oven cooling and capable of producingrepeatable oven ramps from 0 to at least 300C is required.The following features are useful during the sample analysisph
25、ase: electronic flow readout, electronic sample split-ratioreadout, and electronic pneumatic control of flow. Though theiruse is not required, careful review of this test method willdemonstrate the usefulness of a gas chromatograph equippedwith these features. These features will replace the need to
26、carry out the manual calculations that must be performed aslisted in 8.1 and 8.2.6.2 Inleta capillary split/splitless inlet system operated inthe split mode is recommended. It must be operated in its linearrange. Refer to 8.4 to determine the proper split ratio.6.2.1 Carrier Gas Pneumatic ControlCon
27、stant carrier gaspressure control was used by all cooperative study participants.This may be either direct pressure to the inlet (injector) or byusing a total flow/back pressure system.6.2.2 Pneumatic Operation of the ChromatographTheuse of constant pressure was the mode of operating the gaschromato
28、graphy used by the participants in the interlaboratorycooperative study. Other carrier gas control methods such asconstant flow (pressure programming) may be used, but thismay change the chromatography elution pattern unless thetemperature programming profile is also adjusted to compen-sate for the
29、flow differences.6.2.3 Temperature ControlThe injector operated in thesplit mode shall be heated by a separate heating zone andheated to temperatures of 200 to 275C.6.3 Column, a fused silica capillary column, 100 m in lengthby 0.25 mm inside diameter, coated with a 0.5 m film ofbonded dimethylpolys
30、iloxane. The column must meet theresolution requirements expressed in 8.3. Columns from twodifferent commercial sources were used in the interlaboratorycooperative study.6.4 Data System, a computer based chromatography datasystem capable of accurately and repeatedly measuring theretention time and a
31、reas of eluting peaks. The system shall beable to acquire data at a rate of at least 10 Hz.Although it is notmandatory, a data system which calculates column resolution(R) is extremely useful as it will replace the need to carry outthe manual calculations which must be performed as listed in8.3.6.4.
32、1 Electronic Integrators, shall be capable of storing upto 400 components in the peak table and shall be able toacquire the data at 10 Hz or faster speeds. They shall becapable of integrating peaks having peak widths at half heightwhich are 1.0s wide. The integrator must be capable ofdisplaying the
33、integration mode of partially resolved peaks. Inaddition, these integrators should be able to download acommonly readable format of data (that is, ASCII) to acomputer in order to facilitate data processing.6.5 Sample IntroductionSample introduction by way of avalve, automatic injection device, robot
34、ic arm or other auto-matic means is highly recommended. An automatic sampleintroduction device is essential to the reproducibility of theanalysis. Manual injections are not recommended. All of the2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
35、 serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.D672904e12reproducibility data reported by this test method for thesamples analyzed were gathered using automatic injectiondevices.6.6 Flame Ionization De
36、tector (FID)The gas chromato-graph should possess a FID having a sensitivity of 0.005coulombs/g for n-butane. The linear dynamic range of thedetector should be 106or better. The detector is heated to300C.7. Reagents and Materials7.1 Calibrating Standard MixtureA spark ignition enginefuel standard of
37、 known composition and concentration by masscan be used. In order to corroborate the identification of thesample, a typical chromatogram (Fig. 1) was obtained fromreference sample ARC96OX.47.2 Gas Chromatograph GasesAll of the following gasesshall have a purity of 99.999 % (V/V) or greater.NOTE 1War
38、ning: Gases are compressed. Some are flammable and allgases are under high pressure.7.2.1 HeliumThe test data was developed with helium asthe carrier gas. It is possible that other carrier gases may beused for this test method.At this time, no data is available fromthis test method with other carrie
39、r gases.7.2.2 Air, Hydrogen and Make-up Gas (Helium or Nitro-gen), shall have a purity of 99.999 % (V/V) or greater.8. Instrument Check Out Prior to Analysis8.1 Setting:8.1.1 Linear Gas VelocityIf the gas chromatograph isequipped with an electronic flow readout device, set the flow to1.8 mL/min. Thi
40、s is achieved by setting the carrier gas flowrate by injection of methane or natural gas at 35C. Ensure thatthe retention time is 7.00 6 0.05 min. This corresponds to alinear velocity of 25 to 26 cm/s. This is equivalent to retentiontimes of methane at 0C ranging from 6.5 to 6.8 min.8.1.2 If the gas
41、 chromatograph is not equipped with anelectronic flow readout device, calculate the linear gas velocityin cm/s using Eq 1.linear gas velocity 5 V 5column length cm!retention time of methanes!(1)8.1.3 The typical retention times for methane and linear gasvelocity for helium are 6.5 to 6.8 and 24 to 2
42、6 cm/s,respectively.8.2 Setting the Split RatioIf the gas chromatograph isequipped with an electronic split-ratio readout device, set thesplit ratio to a sample split of 200:1. If the gas chromatographis not equipped with an electronic split-ratio readout device,one must first calculate column flow
43、rate and then proceed tocalculating split ratio using Eq 2 and 3.column flow rate 5 F 560 p r2! LTref! 2Pi Po!T!3Pref!Pi2 Po2!(2)where:F = flow rate as calculated by using the equation,r = column radius, cm,L = column length, cm,Pi= inlet pressure,Po= outlet pressure,Pref= reference pressure, 1 atm,
44、T = temperature of the column oven,Tref= temperature at the column outlet, and = linear velocity, cm/s.split ratio 5 S 5split vent flow 1 FF(3)8.2.1 The column flow rate is calculated by the use of Eq 2.Use the results obtained from Eq 3 to adjust the split flow untila split flow of approximately 20
45、0:1 is achieved.8.3 Evaluation of Column Performance:8.3.1 Prior to using the column described in Table 1,measure the resolution of the column under the conditions ofTable 2. Check that the resolution for the following pairs ofcomponents is obtained using Eq 4 to calculate the resolutionof a pair of
46、 components:R 52tR2 tR1!1.699 Wh11 Wh2!(4)where:R = resolution,tR2= retention time of the first member of the pair,tR1= retention time of the second member of the pair,Wh1= peak width at half height of the first member of thepair, andWh2= peak width at half height of the second member ofthe pair.8.3
47、.1.1 Column resolution should be checked frequently byexamining the resolution of these compounds.8.3.2 Evaluation of the BaselineCarry out a blank base-line run utilizing no solvent injection, by setting the GC inaccordance with the conditions of Table 1.8.3.3 Subtract the baseline from a sample ch
48、romatogramand verify that the residual signal at the beginning of thechromatogram does not differ from the end of the chromato-gram by more than 2 %.8.4 Evaluation of Splitter LinearityUsing the referencegasoline sample, inject this sample according to the schedulelisted in Table 3.8.4.1 Select from
49、 the chromatogram about 10 to 15 compo-nents, which have concentrations in the range of .01 to 30weight %. Tabulate for each split ratio the concentrations of the10 to 15 components. Verify that for each component selected,its concentration does not vary by more than 3 %.9. Procedure9.1 Set the operating conditions of the gas chromatograph asshown in Table 1. These conditions will elute all componentsup to and including pentadecane (nC15).9.2 All of the parameters in Table 1 can be marginallychanged to optimize for sample types and optimize for ch
