1、Designation: D6296 98 (Reapproved 2017)Standard Test Method forTotal Olefins in Spark-ignition Engine Fuels byMultidimensional Gas Chromatography1This standard is issued under the fixed designation D6296; the number immediately following the designation indicates the year oforiginal adoption or, in
2、the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method provides for the quantitative determi-nation of total olefins in th
3、e C4to C10range in spark-ignitionengine fuels or related hydrocarbon streams, such as naphthasand cracked naphthas. Olefin concentrations in the range from0.2 liquid-volume % or mass % to 5.0 liquid-volume % ormass %, or both, can be determined directly on the as-receivedsample whereas olefins in sa
4、mples containing higher concen-trations are determined after appropriate sample dilution priorto analysis.1.2 This test method is applicable to samples containingalcohols and ethers; however, samples containing greater than15 % alcohol must be diluted. Samples containing greater than5.0 % ether must
5、 also be diluted to the 5.0 % or less level, priorto analysis. When ethyl-tert-butylether is present, only olefinsin the C4to C9range can be determined.1.3 This test method can not be used to determine individualolefin components.1.4 This test method can not be used to determine olefinshaving higher
6、 carbon numbers than C10.NOTE 1Precision was determined only on samples containing MTBEand ethanol.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns, if a
7、ny, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accor-dance with internatio
8、nally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1319 Test
9、 Method for Hydrocarbon Types in Liquid Petro-leum Products by Fluorescent Indicator AdsorptionD4052 Test Method for Density, Relative Density, and APIGravity of Liquids by Digital Density MeterD4307 Practice for Preparation of Liquid Blends for Use asAnalytical StandardsD4815 Test Method for Determ
10、ination of MTBE, ETBE,TAME, DIPE, tertiary-Amyl Alcohol and C1to C4Alco-hols in Gasoline by Gas ChromatographyD5599 Test Method for Determination of Oxygenates inGasoline by Gas Chromatography and Oxygen SelectiveFlame Ionization Detection3. Terminology3.1 Definitions of Terms Specific to This Stand
11、ard:3.1.1 trap, na device utilized to selectively retain specificportions (individual or groups of hydrocarbons or oxygenates)of the test sample and to release the retained components byincreasing the trap temperature.3.2 Acronyms:3.2.1 ETBEethyl-tert-butylether.3.2.2 MTBEmethyl-tertbutylether.4. Su
12、mmary of Test Method4.1 A reproducible 0.2 L volume of a representativesample, or a dilution thereof, is introduced into a computercontrolled gas chromatographic system3consisting of a seriesof columns, traps, and switching valves operating at various1This test method is under the jurisdiction of AS
13、TM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility ofSubcommittee D02.04.0L on Gas Chromatography Methods.Current edition approved Oct. 1, 2017. Published November 2017. Originallyapproved in 1998. Last previous edition approved in 2013 as D6296 98(20
14、13).DOI: 10.1520/D6296-98R17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The sole source of supply of ap
15、paratus known to the committee at this time, theAC FTO Analyzer, is AC Analytical Controls, Inc., 3494 Progress Dr., Bensalem,PA 19020. If you are aware of alternative suppliers, please provide this informationto ASTM Headquarters. Your comments will receive careful consideration at ameeting of the
16、responsible technical committee,1which you may attend.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in
17、the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.151 temperatures. The valves are actuated at predetermined timesto direct portions of the sample to appropriate colu
18、mns andtraps. The sample first passes through a polar column thatretains C12+ hydrocarbons, all aromatics, C11+ olefins, andsome alcohols, all of which are subsequently backflushed tovent. The fraction eluting from the polar column, whichcontains C11and lower boiling saturated hydrocarbons as wellas
19、 decene and lower boiling olefins, enters an ether/alcohol trapwhere the ethers and alcohols are selectively retained and alsosubsequently backflushed. The fraction eluting from the ether/alcohol trap, which consists of C11and lower boiling saturatedhydrocarbons and the olefins, enters an olefin tra
20、p. The olefinsare selectively retained while the saturated hydrocarbons elute,pass through a nonpolar column, and are detected by a flameionization detector (FID). When the saturated hydrocarbonshave completely eluted to the FID, the nonpolar column ovenis cooled and the olefins, which have been ret
21、ained on theolefin trap, are desorbed by heating. The desorbed olefins enterand elute from the nonpolar column, which is temperatureprogrammed to separate the olefins by boiling point, and aredetected by the FID.NOTE 2Separation of olefins by boiling point is necessary for thecalculation of the volu
22、me % of the olefins because the density of lowboiling olefins differs from that of high boiling olefins and, therefore, adensity correction must be applied.4.2 Quantitation of the detected olefin peak areas to providevolume % or mass %, or both, is accomplished through the useof an external standard
23、 followed by the application of flameionization detector response factors. The quantitation alsotakes into consideration the baseline compensation, sampledilution, and density corrections.5. Significance and Use5.1 The quantitative determination of olefins in spark-ignition engine fuels is required
24、to comply with governmentregulations.5.2 Knowledge of the total olefin content provides a meansto monitor the efficiency of catalytic cracking processes.5.3 This test method provides better precision for olefincontent than Test Method D1319. It also provides data in amuch shorter time, approximately
25、 20 min followingcalibration, and maximizes automation to reduce operatorlabor.5.4 This test method is not applicable to M85 or E85 fuels,which contain 85 % methanol and ethanol, respectively.6. Interferences6.1 Some types of sulfur-containing compounds are irre-versibly absorbed in the olefin and o
26、xygenate traps ultimatelyreducing the trap capacity. However, a variety of spark-ignitionengine fuels have been analyzed without significant perfor-mance deterioration of these traps.6.2 Commercial dyes used to distinguish between gradesand types of spark-ignition engine fuels have not been found to
27、interfere with this test method.6.3 Commercial detergent additives utilized in spark-ignition engine fuels have not been found to interfere with thistest method.6.4 Dissolved water in spark-ignition engine fuels has notbeen found to interfere with this test method. Free water mustbe removed using an
28、hydrous sodium sulfate or other dryingagent to permit injection of accurate sample volumes.7. Apparatus7.1 The complete system used to obtain the precision data iscomprised of a computer controlled gas chromatograph, auto-mated sample injector, computer software, and specific hard-ware modifications
29、. These modifications include columns,traps, and valves which are described as follows and in Section8. Fig. 1 illustrates a typical flow diagram and componentFIG. 1 Typical Flow Diagram and Component ConfigurationD6296 98 (2017)251 configuration. Other configurations, components, or conditionsmay b
30、e utilized provided they are capable of separating theolefins and producing a precision that is equivalent, or better,than that shown in the table of precision data.7.2 Gas Chromatograph, dual column, temperature pro-grammable over a range from 60 C to 160 C at approxi-mately 20 C min, equipped with
31、 heated flash vaporizationsample inlets, a single flame ionization detector, necessary flowcontrollers, and computer control.7.3 Sample Introduction System, manual or automatic, ca-pable of injecting a reproducible 0.2 L injection volume ofliquid. The total injected sample must be introduced to thec
32、hromatographic system, thus excluding the use of split injec-tions or carrier gas purging of the inlet septum.An auto injectoris recommended but optional. The precision data was obtainedusing an automated sample injector.7.4 Gas Flow and Pressure Controllers, with adequateprecision to provide reprod
33、ucible flow and pressure of heliumto the chromatographic system, and hydrogen and air for theflame ionization detector. Control of air flow for rapid coolingof specific system components and for automated valve opera-tion is also required.7.5 Electronic Data Acquisition System, must meet or ex-ceed
34、the following specifications (see Note 3):7.5.1 Capacity for 150 peaks for each analysis,7.5.2 External standard calculation of selected peaks withresponse factors and background correction,7.5.3 Noise and spike rejection capability,7.5.4 Sampling rate for fast (5 Hz to give 20points across peak),7.
35、5.5 Peak width detection for narrow and broad peaks, and7.5.6 Perpendicular drop.NOTE 3Standard supplied software is typically satisfactory.7.6 Gas Purifiers, to remove moisture and oxygen fromhelium, moisture and hydrocarbons from hydrogen, and mois-ture and hydrocarbons from air.7.7 Balance, analy
36、tical, capable of weighing 0.0001 g.7.8 Glassware:7.8.1 Vial, autosampler, with caps and including a capcrimper (required when the recommended optional autosam-pler is used).7.8.2 Pipette, Pasteur, disposable, with bulb.7.8.3 Pipette, volumetric, graduated in 0.01 mL increments,1 mL and 2 mL capacit
37、y.7.8.4 Pipette, total volume, 1 mL, 3 mL, 5 mL, 10 mL,20 mL, and 25 mL capacity.7.9 Septa, polytetrafluoroethylene (PTFE) lined for injector.7.10 Temperature Controllers of System ComponentsTheindependent temperature control of two columns and two traps,column switching valves, and sample lines is
38、required. Allsystem components that contact the sample must be heated toa temperature that will prevent condensation of any samplecomponent. Table 1 lists the system components and operatingtemperature (see Note 4). Some of the components requireisothermal operation, some require rapid heating and c
39、ooling,while one requires reproducible temperature programming.The indicated temperatures are typical; however, the controlsystems utilized must have the capability of operating attemperatures 620 of those indicated to accommodate specificsystems. Temperature control may be by any means that willmee
40、t the requirements of Table 1.NOTE 4The system components and temperatures listed in Table 1and Section 8 are specific to the analyzer used to obtain the precision data.Other columns and traps that can adequately perform the requiredseparations are also satisfactory but may require different tempera
41、tures.7.11 Valves, Column, and Trap Switchingautomated6-port rotary valves are recommended. The valves must beintended for gas chromatographic usage and meet the follow-ing requirements:7.11.1 The valves must be capable of continuous operationat operating temperatures that will prevent sample conden
42、sa-tion.7.11.2 The valves must be constructed of materials that arenonreactive with the sample under analysis conditions. Stain-less steel, PFA, and Vespel4are satisfactory.7.11.3 The valves must have a small internal volume butoffer little restriction to carrier gas flow under analysis condi-tions.
43、7.12 Valves, Air, to control pressurized air for ether/alcoholand olefin trap cooling; 3-port automated valves are recom-mended.NOTE 5New valves, tubing, columns, traps, and other materials thatcontact the sample or gasses may require conditioning prior to operationin accordance with the manufacture
44、rs instructions.8. Reagents and Materials8.1 Air, compressed, 10 mg kg each of total hydrocarbonsand H2O. (WarningCompressed gas under high pressurethat supports combustion.)8.2 Helium, 99.999 % pure, 0.1 mg kg H2O(WarningCompressed gas under high pressure.)8.3 Hydrogen, 99.999 % pure, 0.1 mg kg H2O
45、(WarningExtremely flammable gas under high pressure.)8.4 2,2,4-trimethylpenane (isooctane), 99.99 % pure(WarningFlammable. Harmful if inhaled.)8.5 Columns and Traps (System Components)This testmethod requires the use of two chromatographic columns and4PFA and Vespel are trademarks of E.I. DuPont de
46、Nemours and Co.TABLE 1 Temperature Control Ranges of System ComponentsTypical OperatingComponentTemperatureRange, CHeating Time, min,maxCooling Time, min,maxPolar column 60 to 160 temperatureNonpolar column 60 to 160 programmed, ; 20 C minEther/alcohol trap 120 to 280 1 5Olefin trap 155 to 280 1 5Co
47、lumn switching 100 isothermalValvesSample lines 100 isothermalD6296 98 (2017)351 two traps (see Note 4). Each system component is indepen-dently temperature controlled as described in 7.10 and Table 1.Refer to Fig. 1 for the location of the components in thesystem. The following list of columns and
48、traps containsguidelines that are to be used to judge suitability.8.5.1 Polar ColumnAt a temperature of 160 C, thiscolumn must retain all aromatic components in the sample andelute all nonaromatic components boiling below 200 C, whichincludes decene and lower boiling olefins, within 2 min aftersampl
49、e injection.8.5.1.1 This column must elute all aromatics and othercomponents retained from 8.5.1 within 8 min of when it isbackflushed.8.5.2 Ether/Alcohol TrapAt a temperature of 140 C, thistrap must retain alcohols and ethers and elute all non-oxygenates boiling below 200 C within 4.5 min to 5.0 minafter sample injection.8.5.2.1 At a temperature of 280 C, this trap must elute allretained components.8.5.3 Olefin TrapWithin a temperature range from 140 Cto 165 C, this trap must quantitatively retain (trap) all olefinsin the
