1、Designation: D6296 98 (Reapproved 2013)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 to 5.0 liquid-volume % or mass %, or both, can bedetermined directly on the as-received sample whereas olefinsin samples containing higher co
4、ncentrations are determinedafter appropriate sample dilution prior to 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 also be diluted to the 5.0
5、 % 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 carbon numbers than C10.NO
6、TE 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 any, associated with its use
7、. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1319 Test Method for Hydrocarbon Types in Liquid Petro-leum Products by Flu
8、orescent 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 Determination of MTBE, ETBE,TAME, DIPE, tertiary-Amyl Alcohol and C1to C
9、4Alco-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 Standard:3.1.1 trap, na device utilized to selectively retain specificp
10、ortions (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. Summary of Test Method4.1 A reproducible 0.2-L volume of a represent
11、ativesample, or a dilution thereof, is introduced into a computercontrolled gas chromatographic system3consisting of a series1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility ofSubcommittee D02.04.0L o
12、n Gas Chromatography Methods.Current edition approved Oct. 1, 2013. Published October 2013. Originallyapproved in 1998. Last previous edition approved in 2008 as D6296 98(2008).DOI: 10.1520/D6296-98R13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Serv
13、ice 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 apparatus known to the committee at this time, theAC FTO Analyzer, is AC Analytical Controls, Inc., 3494 Progress Dr., Bensalem,P
14、A 19020. If you are aware of alternative suppliers, please provide this informationto ASTM Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical committee,1which you may attend.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Co
15、nshohocken, PA 19428-2959. United States1of columns, traps, and switching valves operating at varioustemperatures. The valves are actuated at predetermined timesto direct portions of the sample to appropriate columns andtraps. The sample first passes through a polar column thatretains C12+ hydrocarb
16、ons, 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 decene and lower boiling olefins, enters an ether/alcohol trapwhere the ethers and alc
17、ohols 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 trap. The olefinsare selectively retained while the saturated hydrocarbons elute,pass thro
18、ugh 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 retained on theolefin trap, are desorbed by heating. The desorbed olefins enterand elute f
19、rom 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 volume % of the olefins because the density of lowboiling olefins differs from that of high
20、 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 followed by the application of flameionization detector response factors. The quantita
21、tion 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 to comply with governmentregulations.5.2 Knowledge of the total olefin content provides
22、 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 20 min followingcalibration, and maximizes automation to reduce operatorlabor.5.4 This
23、 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 oxygenate traps ultimatelyreducing the trap capacity. However, a variety of spark-igniti
24、onengine 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 tointerfere with this test method.6.3 Commercial detergent additives utilized in spark-ig
25、nition 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 anhydrous sodium sulfate or other dryingagent to permit injection of accurate sample volu
26、mes.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. These modifications include columns,traps, and valves which are described as follows
27、and in Section8. Fig. 1 illustrates a typical flow diagram and componentconfiguration. Other configurations, components, or conditionsFIG. 1 Typical Flow Diagram and Component ConfigurationD6296 98 (2013)2may be utilized provided they are capable of separating theolefins and producing a precision th
28、at 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 to 160C at approximately20C/min, equipped with heated flash vaporization sampleinlets, a single flame ionization detector, necessary flowcontr
29、ollers, and computer control.7.3 Sample Introduction System , manual or automatic,capable of injecting a reproducible 0.2-L injection volume ofliquid. The total injected sample must be introduced to thechromatographic system, thus excluding the use of split injec-tions or carrier gas purging of the
30、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 reproducible flow and pressure of heliumto the chromatographic system, and hydrogen and air for thefla
31、me 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 the following specifications (see Note 3):7.5.1 Capacity for 150 peaks for each analysis,7.5.2 E
32、xternal 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 give20 points across peak),7.5.5 Peak width detection for narrow and broad peaks, and7.5.6 Perpendicular drop.NOTE 3Standard
33、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, analytical, capable of weighing 0.0001 g.7.8 Glassware:7.8.1 Vial, autosampler, with caps and includi
34、ng 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- and 2-mL capacity.7.8.4 Pipette, total volume, 1, 3, 5, 10, 20 and 25-mLcapacity.7.9 Septa, polytetrafluoroethylen
35、e (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 required. Allsystem components that contact the sample must be heated toa temperature that will prevent condensati
36、on 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 cooling,while one requires reproducible temperature programming.The indicated temperatures are typical; however, th
37、e controlsystems utilized must have the capability of operating attemperatures 620 of those indicated to accommodate specificsystems. Temperature control may be by any means that willmeet the requirements of Table 1.NOTE 4The system components and temperatures listed in Table 1and Section 8 are spec
38、ific 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 temperatures.7.11 Valves, Column, and Trap Switching automated6-port rotary valves are recommended. The valves must beint
39、ended 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 condensa-tion.7.11.2 The valves must be constructed of materials that arenonreactive with the sample under analysis con
40、ditions. 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.7.12 Valves, Air, to control pressurized air for ether/alcoholand olefin trap cooling; 3-port automated valves ar
41、e 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 manufacturers instructions.8. Reagents and Materials8.1 Air, compressed, 10 mg/kg each of total hydrocarbonsand H2O. ( Warni
42、ngCompressed 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(WarningExtremely flammable gas under high pressure.)8.4 2,2,4-trimethylpenane (isooctane) , 99.99 % pure(Warnin
43、gFlammable. Harmful if inhaled.)8.5 Columns and Traps (System Components) This testmethod requires the use of two chromatographic columns andtwo traps (see Note 4). Each system component is indepen-dently temperature controlled as described in 7.10 and Table 1.4PFA and Vespel are trademarks of E.I.
44、DuPont de 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, ; 20C/minEther/alcohol trap 120 to 280 1 5Olefin trap 155 to
45、280 1 5Column switching 100 isothermalValvesSample lines 100 isothermalD6296 98 (2013)3Refer to Fig. 1 for the location of the components in thesystem. The following list of columns and traps containsguidelines that are to be used to judge suitability.8.5.1 Polar Column At a temperature of 160C, thi
46、scolumn must retain all aromatic components in the sample andelute all nonaromatic components boiling below 200C, whichincludes decene and lower boiling olefins, within 2 min aftersample injection.8.5.1.1 This column must elute all aromatics and othercomponents retained from 8.5.1 within 8 min of wh
47、en it isbackflushed.8.5.2 Ether/Alcohol TrapAt a temperature of 140C, thistrap must retain alcohols and ethers and elute all non-oxygenates boiling below 200C within 4.5 to 5.0 min aftersample injection.8.5.2.1 At a temperature of 280C, this trap must elute allretained components.8.5.3 Olefin Trap W
48、ithin a temperature range from 140 to165C, this trap must quantitatively retain (trap) all olefins inthe C4to C10range for at least 10 min after sample injectionwhile eluting all non-olefin components boiling below 200C.8.5.3.1 At a temperature of 280C, this trap must quantita-tively elute all trapp
49、ed olefins.8.5.4 Nonpolar Column At a temperature of 160C, thiscolumn must elute paraffins and naphthenes through C11within2 min.8.5.4.1 This column must distribute the C4through C10olefins by carbon number when temperature programmed from60 to 160C at approximately 20C/min.8.6 Set Up Mixtures Two qualitative synthetic mixturescontaining isooctane and ethers are required to verify that allinstrument components, temperatures, and cut times are satis-factory to produce accurate analyses and to aid in makingoperating adjustments as columns and
