1、Designation: D 7096 05An American National StandardStandard Test Method forDetermination of the Boiling Range Distribution of Gasolineby Wide-Bore Capillary Gas Chromatography1This standard is issued under the fixed designation D 7096; the number immediately following the designation indicates the y
2、ear 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.1. Scope1.1 This test method covers the determination of the boi
3、lingrange distribution of gasoline and liquid gasoline blendingcomponents. It is applicable to petroleum products and frac-tions with a final boiling point of 280C (536F) or lower, asmeasured by this test method.1.2 This test method is designed to measure the entireboiling range of gasoline and gaso
4、line components with eitherhigh or low vapor pressure and is commonly referred to asSimulated Distillation (SimDis) by gas chromatographers.1.3 This test method has been validated for gasoline con-taining ethanol. Gasolines containing other oxygenates are notspecifically excluded, but they were not
5、used in the develop-ment of this test method.1.4 This test method can estimate the concentration ofn-pentane and lighter saturated hydrocarbons in gasoline.1.5 The values stated in SI units (degrees Celsius) are to beregarded as the standard. Results in degrees Fahrenheit can beobtained by simply su
6、bstituting Fahrenheit boiling points in thecalculation of the boiling point-retention time correlation.1.6 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 h
7、ealth practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D86 Test Method for Distillation of Petroleum Products atAtmospheric PressureD 2421 Practice for Interconversion of Analysis of C5andLighter Hydrocarbons to Gas-Volume,
8、Liquid-Volume, orMass BasisD 3700 Practice for Obtaining LPG Samples Using a Float-ing Piston CylinderD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4307 Practice for Preparation of Liquid Blends for Use asAnalytical StandardsD 4626 Practice for Calculation of Gas Chromatogr
9、aphicResponse FactorsD 4814 Specification forAutomotive Spark-Ignition EngineFuelD 4815 Test Method for Determination of MTBE, ETBE,TAME, DIPE, tertiary-Amyl Alcohol and C1to C4Alco-hols in Gasoline by Gas ChromatographyD 5191 Test Method for Vapor Pressure of Petroleum Prod-ucts (Mini Method)D 5599
10、 Test Method for Determination of Oxygenates inGasoline by Gas Chromatography and Oxygen SelectiveFlame Ionization DetectionE 594 Practice for Testing Flame Ionization Detectors Usedin Gas ChromatographyE 1510 Practice for Installing Fused Silica Open TubularCapillary Columns in Gas Chromatographs3.
11、 Terminology3.1 Definitions:3.1.1 area slice, narea under a chromatogram within aspecified retention time interval.3.1.2 final boiling point (FBP), nthe point at which acumulative volume count equal to 99.5 % of the total volumecounts under the chromatogram is obtained.3.1.3 initial boiling point (I
12、BP), nthe point at which acumulative volume count equal to 0.5 % of the total volumecounts under the chromatogram is obtained.3.1.4 relative volume response factor (RVRF), nthe vol-ume response factor (see 3.1.8) of a component i relative to thevolume response factor of n-heptane.3.1.5 slice time, n
13、the retention time at the end of a givenarea slice.3.1.6 slice width, nthe fixed duration (1 s, or less) of theretention time intervals into which the chromatogram is di-vided. It is determined from the reciprocal of the frequencyused in the acquisition of data.1This test method is under the jurisdi
14、ction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04 on Hydrocarbon Analysis.Current edition approved April 1, 2005. Published May 2005.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Serv
15、ice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.7 volume count, nthe product of a slice
16、area (or anarea under a peak) and a volume response factor.3.1.8 volume response factor, na constant of proportion-ality that relates the area under a chromatogram to liquidvolume.4. Summary of Test Method4.1 The sample is vaporized and transported by carrier gasinto a non-polar, wide-bore capillary
17、 gas chromatographiccolumn. The column temperature is raised at a reproducible,linear rate so as to elute the hydrocarbon components in boilingpoint order for measurement by a flame ionization detector.Conditions are selected such that n-pentane and lighter satu-rated hydrocarbons in the calibration
18、 mixture are resolveddiscretely. Linear correlation between hydrocarbon boilingpoint and retention time is established using a known mixtureof hydrocarbons covering the boiling range expected in thesample. Area slices are converted to volume using theoreticalhydrocarbon volume response factors. Oxyg
19、enated samplesrequire experimental determination of oxygenate responsefactors.5. Significance and Use5.1 The determination of the boiling range distribution ofgasoline by gas chromatographic simulated distillation pro-vides an insight into the composition of the components fromwhich the gasoline has
20、 been blended. Knowledge of the boilingrange distribution of gasoline blending components is usefulfor the control of refinery processes and for the blending offinished gasoline.5.2 The determination of the boiling range distribution oflight hydrocarbon mixtures by gas chromatographic simulateddisti
21、llation has better precision than the conventional distilla-tion by Test Method D86. Additionally, this test methodprovides more accurate and detailed information about thecomposition of the light ends. The distillation data produced bythis test method are similar to that which would be obtainedfrom
22、 a cryogenic, true boiling point (15 theoretical plates)distillation.6. Interferences6.1 Ethanol or other oxygenates may coelute with hydrocar-bons present in the sample. Since the response of oxygenates issubstantially different from the response of hydrocarbons,response factors are used to correct
23、 the area slice for the elutioninterval of oxygenates.6.2 Concentrations of n-pentane and lighter saturated com-pounds may be estimated from the analysis. However, earlyeluting olefins present in the gasoline samples may coelutewith these compounds.7. Apparatus7.1 Gas ChromatographAny gas chromatogr
24、aph (GC)designed for use with wide-bore (0.53 mm inside diameter)capillary columns, that meets the performance criteria specifiedin Section 11, and has the following features may be used.Typical operating conditions are shown in Table 1.7.1.1 Column Oven Temperature ProgrammingThe gaschromatograph s
25、hall be capable of linear temperature-programmed operation from 40 to 280C at rates up to25C/min.7.1.2 Injection PortThe injection port shall be capable ofoperation at temperatures required to completely volatize andtransfer the sample to the GC column. Non-splitting orsplit/splitless vaporizing sam
26、ple ports optimized for use withwide-bore capillary columns are acceptable. If using a splitinlet port, it should be designed to provide a linear sample splitinjection.7.1.3 Flame Ionization DetectorThe detector shall beoptimized for the use of wide-bore capillary gas chromato-graphic columns and sh
27、all conform to the specifications asdescribed in Practice E 594.7.1.4 Carrier Gas ControlsThe associated carrier gascontrols shall be of sufficient precision to produce reproduciblecolumn flows in order to maintain analytical integrity.7.1.5 Baseline CorrectionThe gas chromatograph (or an-other comp
28、onent of the gas chromatographic system) shall beTABLE 1 Typical Operating Conditions for Wide BoreColumn InletsColumn length (m) 30 15Column I.D. (mm) 0.53 0.53Stationary phase 100 % poly-dimethylsiloxane100 % poly-dimethylsiloxaneFilm thickness (m) 5 5Carrier gas helium heliumCarrier flow (mL/min)
29、 20 15Auxiliary flow (mL/min) 10 10Column initial temperature (C) 40 40Initial time (min) 1 1Program rate (C/min) 25 20Final temperature (C) 265 230Final hold (min) 4.00 2.50Injection inlet purged-packed purged-packedSample introduction auto syringe injection auto syringe injectionInjector temperatu
30、re (C) 250 250Detector temperature (C) 280 300Hydrogen flow (mL/min) 45 30Air flow (mL/min) 450 300Sample size (L) 0.1 0.2 0.2Area slice width (s) 0.5 0.2 0.5 0.2Datarate(Hz) 25 25TABLE 2 Typical Operating Conditions for Capillary Column InletColumn length (m) 30Column I.D. (mm) 0.53Stationary phase
31、 100 % polydimethylsiloxaneFilm thickness 5 mCarrier gas helium (ramped flow)Carrier flow (mL/min) 5mL/min (0.5 min) to 20mL/min 60mL/minColumn initial temperature (C) 40Initial time (min) 1Program rate (C/min) 25Final temperature (C) 245Final hold (min) 4Injection port splitSample introduction auto
32、matic syringe injectionInjector temperature (C) 250Detector temperature (C) 250Hydrogen flow (mL/min) 30Air flow (mL/min) 300Sample size (L) 1 uLSplit ratio 1:50Data rate 5 HzD7096052capable of subtracting the area slice of a blank run from thecorresponding area slice of a sample run. This can be do
33、neinternally on some gas chromatographs (baseline compensa-tion) or externally by subtracting a stored, digitized signal froma blank run.7.2 Sample IntroductionSample introduction may be bymeans of a constant volume liquid sample valve or by injectionwith a micro syringe through a septum. An automat
34、ic sampleintroduction device is essential to the reproducibility of theanalysis. Manual injections are not recommended. Poor injec-tion technique can result in poor resolution. If column overloadoccurs, peak skewing may result, leading to variation inretention times.7.2.1 Samples with a vapor pressu
35、re (VP) of less than 16psia as measured by Test Method D 5191, or equivalent, maybe introduced into the gas chromatograph by syringe injectioninto a heated, vaporizing inlet. Samples with vapor pressuresbetween 12 and 16 psia should be kept chilled (refrigerated orin a cooled sample tray) and may re
36、quire injection with acooled syringe. Samples with a vapor pressure above 16 psiashould be introduced by way of a constant volume liquidsampling valve. Refer to 9.1 for sampling practices.7.3 ColumnAny wide bore (0.53 mm inside diameter)open tubular (capillary) column, coated with a non-polar(100 %
37、polydimethylsiloxane) phase that meets the perfor-mance criteria of 11.3 may be used. Columns of 15 to 30 metrelengths with a stationary phase film thickness of 5.0 m havebeen successfully used. With either of these columns, initialcryogenic temperatures are not necessary.7.4 Data Acquisition System
38、A computer provided with amonitor, printer, and data acquisition software is necessary tocarry out this analysis. The computer should have sufficienthardware capacity and random access memory in order to runthe data acquisition program while acquiring data at a fre-quency of 2 to 5 Hz. The software
39、should also be able to storethe data for future recall, inspection, and analysis. The dataacquisition software should be capable of presenting a real timeplot. It may also be capable of controlling the operatingvariables of the gas chromatograph. Specialized software isnecessary to obtain the boilin
40、g point distribution.7.5 Bulk Sample Containers, floating piston cylinders (see9.1.1); epoxy phenolic-lined metal cans; glass bottles withpolytetrafluoroethylene-lined screw caps.8. Reagents and Materials8.1 Calibration MixtureAsynthetic mixture of pure liquidhydrocarbons with boiling points that en
41、compass the boilingrange of the sample shall be used for retention time determi-nation and response factor validation. Response factors forpropane, isobutane, and n-butane are extrapolated from therelative molar response of the n-paraffins. An example of arelative response factor mixture with sugges
42、ted nominal com-position is given in Table 3. This mixture shall be accuratelyprepared on a mass basis using Practice D 4307 or equivalent.8.1.1 Asingle calibration standard may be used for retentiontime-boiling point determination and response factor validationprovided isopentane and heavier compon
43、ents are known quan-titatively. Gaseous components propane, isobutane, andn-butane are added in small quantities (N+1 N)/(bunched slice width) 1E-7 total chromatogram area, then take slice N+1 as thestart of sample slice.X1.3.2 Store the retention time corresponding to the start ofsample elution.X1.
44、4 Determine End of Sample Elution Time:X1.4.1 Beginning with the baseline-corrected area slices atthe end of the chromatogram and working backwards, calculatethe rate of change between consecutive moving averages of 3slices using Eq X1.1:O5i212 i! 3 100W!Atot!(X1.1)D70960511where:O= rate of change b
45、etween two consecutive movingaverages of three area slices, %/s,i-1= average area of slices i-3, i-2, and i-1,i= average area of slices i-2, i-1, and i,W = slice width, s, andAtot= total of all baseline corrected area slices in chro-matogram.X1.4.2 The slice time of the area slice (i-1) at which the
46、 rateof change of the moving averages first exceeds 0.0001 % persecond is defined as the end of sample.X2. CALCULATION OF BOILING POINT FROM RETENTION TIMEX2.1 Use linear interpolation between adjacent entries inthe calibration table (see Table 3) to determine the exactboiling point corresponding to
47、 a given retention time.X2.1.1 Compare the given retention time (tx) against eachretention time in the the retention time calibration table.X2.1.2 If the given retention time matches that of one of thecalibration mixture components, use the boiling point of thatcomponent.X2.1.3 If the given retentio
48、n time does not match any of thecalibration mixture components, record the retention time (tn-1)and the boiling point (Tn-1) of the calibration mixture compo-nent that is closest to, but less than, the given retention time.Also record the retention time (tn) and boiling point (Tn)ofthecalibration mi
49、xture component that is closest to, but greaterthan, the given retention time.X2.1.4 Use Eq X2.1 to calculate the boiling point (Tx)corresponding to the given retention time.Tx5 Tn211FTn21! 3tx2 tn21!tn2 tn21!G(X2.1)X2.2 ExampleAssume the retention times of octane andm-xylene are 4.354 min respectively and their boiling pointsare 125.7 and 139.1C. The boiling point corresponding to aretention time of 4.500 min. is calculated as follows:Tx5 125.75113999.1 2 125.7! 3 4.500 2 4.354! / 4.896 2 4.354!#5 129.3C (X2.2)X3.
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