1、Designation: D7398 11Standard Test Method forBoiling Range Distribution of Fatty Acid Methyl Esters(FAME) in the Boiling Range from 100 to 615C by GasChromatography1This standard is issued under the fixed designation D7398; the number immediately following the designation indicates the year oforigin
2、al adoption or, in 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. Scope*1.1 This test method covers the determination of the boilingrange di
3、stribution of fatty acid methyl esters (FAME). This testmethod is applicable to FAMES (biodiesel, B100) having aninitial boiling point greater than 100C and a final boiling pointless than 615C at atmospheric pressure as measured by thistest method.1.2 The test method can also be applicable to blends
4、 ofdiesel and biodiesel (B1 through B100), however precision forthese samples types has not been evaluated.1.3 The test method is not applicable for analysis ofpetroleum containing low molecular weight components (forexample naphthas, reformates, gasolines, crude oils).1.4 Boiling range distribution
5、s obtained by this test methodare not equivalent to results from low efficiency distillationsuch as those obtained with Test Method D86 or D1160,especially the initial and final boiling points.1.5 This test method uses the principles of simulated distil-lation methodology. See Test Methods D2887, D6
6、352, andD7213.1.6 The values stated in SI units are to be regarded asstandard. The values given in parentheses are for informationonly.1.7 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 est
7、ablish appro-priate safety and health 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 PressureD1160 Test Method for Distillation of Petroleum Productsat R
8、educed PressureD2887 Test Method for Boiling Range Distribution ofPetroleum Fractions by Gas ChromatographyD2892 Test Method for Distillation of Crude Petroleum(15-Theoretical Plate Column)D4626 Practice for Calculation of Gas ChromatographicResponse FactorsD6352 Test Method for Boiling Range Distri
9、bution ofPetroleum Distillates in Boiling Range from 174 to 700Cby Gas ChromatographyD6751 Specification for Biodiesel Fuel Blend Stock (B100)for Middle Distillate FuelsD7213 Test Method for Boiling Range Distribution ofPetroleum Distillates in the Boiling Range from 100 to615C by Gas Chromatography
10、E355 Practice for Gas Chromatography Terms and Rela-tionshipsE594 Practice for Testing Flame Ionization Detectors Usedin Gas or Supercritical Fluid ChromatographyE1510 Practice for Installing Fused Silica Open TubularCapillary Columns in Gas Chromatographs3. Terminology3.1 Definitions:3.1.1 This tes
11、t method makes reference to many commongas chromatographic procedures, terms, and relationships.Detailed definitions of these can be found in Practices E355,E594, and E1510.3.1.2 biodiesel, nfuel composed of mono-alkyl esters oflong chain fatty acids derived from vegetable oils or animalfats, design
12、ated B100.3.2 Definitions of Terms Specific to This Standard:3.2.1 area slice, narea resulting from the integration ofthe chromatographic detector signal within a specified reten-tion time interval. In area slice mode (6.4.2), peak detectionparameters are bypassed and the detector signal integral is
13、recorded as area slices of consecutive, fixed duration timeintervals.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04.0H on Chromatographic Distribution Methods.Current edition approved Oct. 1
14、, 2011. Published November 2011. Originallyapproved in 2007. Last previous edition approved in 2007 as D7398-07. DOI:10.1520/D7398-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume info
15、rmation, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.2 atmospheric equivalent temperature (AET)
16、,ntemperature converted from the measured vapor tempera-ture obtained at sub-ambient pressure to atmospheric equiva-lent temperature (AET) corresponding to the equivalent boilingpoint at atmospheric pressure, 101.3 kPa (760 mm Hg), TheAET is the expected distillate temperature if the distillationwas
17、 performed at atmospheric pressure and there was nothermal decomposition.3.2.3 corrected area slice, narea slice corrected for base-line offset, by subtraction of the exactly corresponding areaslice in a previously recorded blank (non-sample) analysis.3.2.4 cumulative corrected area, naccumulated su
18、m ofcorrected area slices from the beginning of the analysis througha given retention time, ignoring any non-sample area (forexample, solvent).3.2.5 initial boiling point (IBP), ntemperature (corre-sponding to the retention time) at which a cumulative correctedarea count equal to 0.5 % of the total
19、sample area under thechromatogram is obtained.3.2.6 final boiling point (FBP), ntemperature (corre-sponding to the retention time) at which a cumulative correctedarea count equal to 99.5 % of the total sample area under thechromatogram is obtained.3.2.7 slice rate, nfrequency of data sampling or the
20、frequency of data bunching provided that the frequency of dataacquisition is larger than the frequency of bunching. The unitof frequency is points/seconds or Hz.3.2.8 slice time, ncumulative slice rate (analysis time)associated with each area slice throughout the chromatographicanalysis. The slice t
21、ime is the time at the end of eachcontiguous area slice.3.2.9 total sample area, ncumulative corrected area, fromthe initial point to the final area point.3.3 Abbreviations:3.3.1 Acommon abbreviation of hydrocarbon compounds isto designate the number of carbon atoms in the compound. Aprefix is used
22、to indicate the carbon chain form, while asubscripted suffix denotes the number of carbon atoms (forexample, normal decane n-C10; iso-tetradecane = i-C14).3.3.2 A common abbreviation for FAME compounds is todesignate the number of carbon atoms and number of doublebonds in the compound. The number of
23、 carbon atoms isdenoted by a number after the “C” and the number followinga colon indicates the number of double bonds (for example,C16:2; FAME with 16 carbon atoms and 2 double bonds).4. Summary of Test Method4.1 The boiling range distribution by distillation is simu-lated by the use of gas chromat
24、ography. A non-polar opentubular (capillary) gas chromatographic column is used to elutethe hydrocarbon and FAME components of the sample in orderof increasing boiling point.4.2 A sample aliquot is diluted with a viscosity reducingsolvent and introduced into the chromatographic system. Thesolvent sh
25、all be apolar and not interfere with measurement ofthe sample in the 100 to 615C range. Sample vaporization isprovided by separate heating of the point of injection or inconjunction with column oven heating.4.3 The column oven temperature is raised at a reproduciblelinear rate to effect separation o
26、f the FAME components inorder of increasing boiling point relative to a n-paraffincalibration mixture. The elution of sample components isquantitatively determined using a flame ionization detector.The detector signal integral is recorded as area slices forconsecutive retention time intervals during
27、 the analysis.4.4 Retention times of known normal paraffin hydrocarbons,spanning the scope of the test method (C5C60), are deter-mined and correlated to their boiling point temperatures. Thenormalized cumulative corrected sample areas for each con-secutive recorded time interval are used to calculat
28、e the boilingrange distribution. The boiling point temperature at eachreported percent off increment is calculated from the retentiontime calibration.4.5 The retention time versus boiling point curve is cali-brated with normal paraffin hydrocarbons since these boilingpoints are well defined. A mixtu
29、re of FAMEs is analyzed tocheck column resolution. A triglyceride is analyzed to verifythe systems ability to detect unreacted oil.5. Significance and Use5.1 The boiling range distribution of FAMES provides aninsight into the composition of product related to the transes-terification process. This g
30、as chromatographic determination ofboiling range can be used to replace conventional distillationmethods for product specification testing with the mutualagreement of interested parties.5.2 Biodiesel (FAMES) exhibits a boiling point rather thana distillation curve. The fatty acid chains in the raw o
31、ils andfats from which biodiesel is produced are mainly comprised ofstraight chain hydrocarbons with 16 to 18 carbons that havesimilar boiling temperatures. The atmospheric boiling point ofbiodiesel generally ranges from 330 to 357C. The Specifica-tion D6751 value of 360C max at 90 % off by Test Met
32、hodD1160 was incorporated as an precaution to ensure the fuel hasnot been adulterated with high boiling contaminants.6. Apparatus6.1 ChromatographThe following gas chromatographicsystem performance characteristics are required:6.1.1 Column OvenCapable of sustained and linear pro-grammed temperature
33、operation from near ambient (for ex-ample 35 to 50C) up to 400C.6.1.2 Column Temperature ProgrammerThe chromato-graph must be capable of linear programmed temperatureoperation up to 400C at selectable linear rates up to 20C/min.The programming rate must be sufficiently reproducible toobtain the rete
34、ntion time repeatability of 0.03 min (3 s) for eachcomponent in the calibration mixture described in 7.3.6.1.3 DetectorThis test method requires a flame ioniza-tion detector (FID). The detector must meet or exceed thefollowing specifications as detailed in Practice E594. Thespecification of flame je
35、t orifice is approximately 0.45 mm(0.018 in.).6.1.3.1 Operating Temperature, 400C.6.1.3.2 Sensitivity, 0.005 coulombs/ g carbon.6.1.3.3 Minimum Detectability,13 10-11g carbon / s.6.1.3.4 Linear Range, 106D7398 1126.1.3.5 Connection of the column to the detector must besuch that no temperature below
36、the column temperature exists.Refer to Practice E1510 for proper installation and condition-ing of the capillary column.6.1.4 Sample Inlet SystemAny sample inlet system ca-pable of meeting the performance specification in 6.1.5 and 7.3may be used. Programmed temperature vaporization (PTV)and program
37、mable cool on-column injection systems havebeen used successfully.6.1.5 Carrier Gas Flow ControlThe chromatograph shallbe equipped with carrier flow control capable of maintainingconstant carrier gas flow control through the column through-out the column temperature program cycle as measured withthe
38、 use of flow a sensor. Flow rate must be maintained within1 % through out the temperature program.6.2 MicrosyringeA microsyringe with a 23 gauge orsmaller stainless steel needle is used for on-column sampleintroduction. Syringes of 0.1 to 10 L capacity are available.6.2.1 Automatic syringe injection
39、 is recommended toachieve best precision.6.3 ColumnThis test method is limited to the use ofnon-polar wall coated open tubular (WCOT) columns of highthermal stability. Glass, fused silica, and stainless steel col-umns, with a 0.53 mm diameter have been successfully used.Cross-linked or bonded 100 %
40、dimethyl-polysiloxane station-ary phases with film thickness of 0.5 to 1.0 m have been used.The column length and liquid phase film thickness shall allowthe elution of at least C60n-paraffin (BP = 615C) and triolein.The column and conditions shall provide separation of typicalpetroleum hydrocarbons
41、and saturated FAMES in order ofincreasing boiling point and meet the column resolutionrequirements of 8.2.1. The column shall provide a resolutionbetween five (5) and fifteen (15) using the test methodoperating conditions.6.4 Data Acquisition System:6.4.1 RecorderA 0 to 1 mV range recording potentio
42、m-eter or equivalent, with a full-scale response time of2sorlessmay be used to provide a graphical display.6.4.2 IntegratorMeans shall be provided for determiningthe accumulated area under the chromatogram. This can bedone by means of an electronic integrator or computer basedchromatography data sys
43、tem. The integrator/computer systemshall have normal chromatographic software for measuring theretention time and areas of eluting peaks (peak detectionmode). In addition, the system shall be capable of convertingthe continuously integrated detector signal into area slices offixed duration (area sli
44、ce mode). These contiguous area slices,collected for the entire analysis, are stored for later processing.The electronic range of the integrator/computer (for example, 1V, 10 V) shall be operated within the linear range of thedetector/electrometer system used.NOTE 1Some gas chromatographs have an al
45、gorithm built into theiroperating software that allows a mathematical model of the baselineprofile to be stored in memory. This profile is automatically subtractedfrom the detector signal on subsequent sample runs to compensate for thecolumn bleed. Some integration systems also store and automatical
46、lysubtract a blank analysis from subsequent analytical determinations.7. Reagents and Materials7.1 GasesThe following compressed gases are utilized forthe operation of the gas chromatograph.7.1.1 Helium, 99.999 %. (WarningCompressed gas un-der high pressure.) This gas can be used as carrier gas. Ens
47、uresufficient pressure for a constant carrier gas flow rate. It is notto contain more than 5 mL/m3of oxygen and the total amountof impurities are not to exceed 10 mL/m3.7.1.2 Nitrogen, 99.999 %. (WarningCompressed gas un-der high pressure.) This gas can be used as carrier gas. Ensuresufficient press
48、ure for a constant carrier gas flow rate. It is notto contain more than 5 mL/m3of oxygen and the total amountof impurities are not to exceed 10 mL/m3.7.1.3 Hydrogen, 99.999 %. (WarningExtremely flam-mable gas under high pressure.) The total impurities are not toexceed 10 mL/m3. This gas can be used
49、as carrier gas. Ensuresufficient pressure for a constant carrier gas flow rate. It is alsoused as fuel for the flame ionization detector (FID).7.1.4 Air, 99.999 %. (WarningCompressed gas underhigh pressure and supports combustion.) Total impurities arenot to exceed 10 mL/m3. This gas is used to sustain combustionin the flame ionization detector (FID).7.2 SolventsUnless otherwise indicated, it is intended thatall solvents conform to the specifications of the committee onanalytical Reagents of the American Chemical Society wheresuch specifica
