ASTM D2427-2006 Standard Test Method for Determination of C2 through C5 Hydrocarbons in Gasolines by Gas Chromatography《气相色谱法测定汽油中C2至C5烃的标准试验方法》.pdf

1、Designation: D 2427 06An American National StandardStandard Test Method forDetermination of C2through C5Hydrocarbons in Gasolinesby Gas Chromatography1This standard is issued under the fixed designation D 2427; the number immediately following the designation indicates the year oforiginal adoption o

2、r, 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. Scope*1.1 This test method covers the determination of the two(C2) through five(C5-) c

3、arbon paraffins and mono-olefins ingasolines. The concentrations by volume or mass (weight) ofthe following components are generally reported:1.1.1 Ethylene plus ethane1.1.2 Propane1.1.3 Propylene1.1.4 Isobutane1.1.5 n-Butane1.1.6 Butene-1 plus isobutylene1.1.7 trans-Butene-21.1.8 cis-Butene-21.1.9

4、Isopentane1.1.10 3-Methylbutene-11.1.11 n-Pentane1.1.12 Pentene-11.1.13 2-Methylbutene-11.1.14 trans-Pentene-21.1.15 cis-Pentene-21.1.16 2-Methylbutene-21.2 This test method does not cover the determination ofcyclic olefins, diolefins, or acetylenes. These are usually minorcomponents in finished gas

5、olines.1.3 Samples to be analyzed should not contain significantamounts of material boiling lower than ethylene.1.4 The values stated in SI units are to be regarded as thestandard. Alternative units, in common usage, are also pro-vided to improve the clarity and aid the user of this testmethod.1.5 T

6、his 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 of regulatory limitations prior to use.2. Referenced Docume

7、nts2.1 ASTM Standards:2D 2001 Test Method for Depentanization of Gasoline andNaphthas3. Summary of Test Method3.1 The sample is injected into a gas-liquid partition col-umn. The components are separated as they pass through thecolumn with an inert carrier gas and their presence in theeffluent is det

8、ected and recorded as a chromatogram. Materialscontaining components having more than five carbon atomscan either be backflushed from the system without measure-ment, or recorded as a broad peak by reversing the direction ofthe carrier gas through the column at such time as to regroupthe higher-boil

9、ing portion (C6and heavier) of the sample. Ifbackflushing is used, the concentration of C2through C5hydrocarbons may be related to the whole sample by adding aknown quantity of low-boiling internal standard to the sampleprior to analysis. Alternatively, a known amount of sample canbe charged and com

10、pared to a standard sample run under thesame conditions. Sample composition is determined from thechromatogram by comparing peak areas with those obtainedusing known amounts of calibration standards or a syntheticblend.4. Significance and Use4.1 In hydrocarbon type analyses of gasolines, highly vola

11、-tile fuels can need to be stabilized by depentanization (TestMethod D 2001) prior to analysis. A knowledge of the com-position of light hydrocarbons in the overhead from thedepentanization process is useful in converting analyses of thedepentanized fraction to a total sample basis.5. Apparatus5.1 C

12、hromatographAny chromatograph having a thermo-stated oven and a detection system of adequate sensitivity may1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04.0L on Gas Chromatography Methods.Cu

13、rrent edition approved Nov. 1, 2006. Published November 2006. Originallyapproved in 1965. Last previous edition approved in 2001 as D 242792 (2001).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandar

14、ds volume information, 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.be used. The detection system mu

15、st have sufficient sensitivityto produce a recorder deflection of at least 5 mm for 0.1 liquidvolume percent of pentene-1 in the sample or synthetic blendbeing analyzed.NOTE 1If the sensitivity of a given system is inadequate, it can beincreased by using a more sensitive recorder or detector, or by

16、using moresample if the resolution is substantially unaffected.5.2 RecorderA 1 to 10-mV recorder with a full-scaleresponse time of 2 s or less and a noise level no greater than60.3 % of full scale.5.3 Columns:5.3.1 A description of columns and valving arrangementsthat meet the requirements of this m

17、ethod are described inAnnex A1. Persons using other column materials must estab-lish that the column gives results that meet the precisionrequirements of Section 10.5.3.2 Analyzer ColumnThe column system used must becapable of resolving the individual C2to C5paraffins andolefins well enough so that

18、the individual hydrocarbons listedin Section 1 may be reported. The resolution should be suchthat at the operating conditions selected, the distance from thebase line in the valley between two peaks representing com-pounds reported is not greater than 50 % of the height of thesmaller peak. If an int

19、ernal standard is used, it must becompletely resolved from the other components.5.3.3 Precut ColumnThis column must be capable ofseparating the C5and lighter olefins and paraffins from the C6and heavier olefins and paraffins. The resolution should be suchthat at the operating conditions selected, th

20、e distance from thebase line to the valley between 2-methylbutene-2 and 2,2-dimethylbutane is not greater than 50% of the height of thesmaller peak. If an internal standard is used, it must be elutedwith the C5and lighter materials.6. Reagents and Materials6.1 Compounds for calibration shall be of a

21、 purity of notless than 99 mole %. Calibrants should include compounds1.1.5-1.1.16 as listed in Section 1. The concentration ofethylene, ethane, propylene, and propane is generally so low inmost samples that calibration with these materials is unneces-sary (WarningExtremely flammable gas under press

22、ure.Extremely flammable liquids.) Commercially available certi-fied blends of light hydrocarbons may be used to establishcalibration data where their compositions are applicable. If aninternal standard is used to relate the concentration of lighthydrocarbons to the whole sample it must be included a

23、s acalibrant.6.2 Carrier GasA carrier gas appropriate to the type ofdetector used should be employed. Helium or hydrogen can beused with thermal conductivity detector (WarningCompressed gas under high pressure.) (WarningHydrogenis extremely flammable under pressure.) Nitrogen or argon canbe used wit

24、h ionization or gas density detectors (WarningCompressed gas under high pressure).6.3 Liquid PhaseSee Annex A1.6.4 Solid Support, for use in packed column; usuallycrushed firebrick or diatomaceous earth. Mesh size should beappropriate to the system selected from the supplement.7. Preparation of Appa

25、ratus7.1 Column PreparationThe method used to prepare thecolumn is not critical as long as the finished column producesthe desired separation. Preparation of the packing is notdifficult once the support, partitioning liquid, and loading levelhave been determined. Some stationary phases are susceptib

26、leto oxidation and must be protected from excessive exposure toair during the evaporation and drying steps. The followinggeneral directions have been found to produce columns ofacceptable characteristics:7.1.1 Weigh out the desired quantity of support, usuallytwice that required to fill the column.7

27、.1.2 Calculate and weigh out the required quantity ofpartitioning agent. Dissolve the partitioning agent in a volumeof chemically inert, low-boiling solvent equal to approximatelytwice the volume of support.7.1.3 Gradually add the support material to the solution withgentle stirring.7.1.4 Slowly eva

28、porate the solvent while gently agitatingthe mixture until the packing is nearly dry and no free liquid isapparent.7.1.5 Spread the packing in thin layers on a nonabsorbentsurface and air or oven dry as required to remove all traces ofsolvent.7.1.6 Resieve the packing to remove fines and agglomerate

29、sproduced in the impregnation step.7.1.7 Fill the column tubing with packing by plugging oneend with a wad of glass wool and pouring the packing into theother end through a small funnel. Vibrate the tubing continu-ously over its entire length while filling. When the packingceases to flow, tap the co

30、lumn gently on the floor or bench topwhile vibrating is continued.Add packing as necessary until nofurther settling occurs during a 2-min period. Remove a smallamount of packing from the open end, plug with a wad of glasswool, and shape the column to fit the chromatograph.7.1.8 If multiple columns a

31、re joined by tubing unions, thedead volume in the union should be filled with columnpacking.7.2 ChromatographMount the column in the chromato-graph and establish the operating conditions required to givethe desired separation (see Annex A1). Allow sufficient timefor the instrument to reach equilibri

32、um as indicated by a stablerecorder base line. Control the oven temperature so that it isconstant to within 0.5C without thermostat cycling whichcauses an uneven base line. Set the carrier gas flow rate,measured with a soap film meter, so that it is constant to within1 mL/min of the selected value.8

33、. Procedure8.1 CalibrationDetermine the relative area response ofthe compounds to be reported by injecting known quantities ofthe pure compounds or by using synthetic blends of knowncomposition. For those compounds that are normally gases atroom temperature it is advantageous to use commerciallyavai

34、lable certified light hydrocarbon blends. Sample lighthydrocarbon blends contained in pressure containers from theliquid phase (WarningExtremely flammable gas under pres-sure.) Blends of those hydrocarbons that are normally liquid atD2427062room temperature are easily prepared by volume with suffici

35、entaccuracy to establish relative response factors (WarningExtremely flammable liquids.) If measurement of the C6andheavier material by reverse flow through the detector isintended, an average calibration factor for these heavy mate-rials must be determined. Gasolines that have been depenta-nized by

36、 laboratory distillation may be used as calibrants forthis purpose (WarningExtremely flammable.) If use of aninternal standard is contemplated, the internal standard selectedshould be included in the calibration program.8.2 Analysis:8.2.1 Backflush MethodWhen the backflush technique isused, add a kn

37、own quantity of internal standard equal to about5 % to the sample. The internal standard can be added on eithera weight or volume basis depending upon the method ofreporting. One method of adding the internal standard that hasbeen found convenient is given in Annex A1. Alternatively,quantitative res

38、ults can be obtained by injecting repeatablequantities of the sample and of a known blend, and comparingthe peak areas obtained for the sample with those obtained forthe known concentration of components in the blend.8.2.1.1 Precut ColumnIf a precut column is used, adjustthe valving so that carrier

39、gas is flowing in the normal directionthrough both the precut and analysis columns. Using a chilledsyringe, charge sufficient sample to ensure a minimum of 10 %recorder deflection for a 0.1 % sample concentration of2-methylbutene-2 at the most sensitive setting of the instru-ment. When all of the C5

40、and lighter hydrocarbons plus internalstandard, if used, have entered the analyzer column, positionthe valves so that backflushing of the precut column isinitiated. The time at which backflushing is commenced iscritical and may have to be determined by trial and error. Ifproperly done, it results in

41、 the elimination of any interferencefrom low-boiling six-carbon paraffins and produces a chro-matogram that exhibits peaks for C2through C5paraffins andolefins only (Fig. 1). When the last compound has been eluted,remove the chromatogram and proceed as described in 9.1.1.8.2.1.2 Single ColumnIf a si

42、ngle column is used, it maybe backflushed if an appropriate valving system has beeninstalled. The operations described above are performed exceptthat backflushing is commenced only when all the C5andlighter hydrocarbons and internal standard have been eluted.The purpose of backflushing in this case

43、is not to improve theseparation, but merely to shorten the total analysis time andavoid passage of higher boiling hydrocarbons through thedetector.8.2.2 Reverse Flow MethodIf reverse flow of the C6andheavier portion through the detector is employed, the additionof an internal standard is unnecessary

44、 if adequate calibrationhas been performed and the composition of the C6and heavierportion does not differ significantly from that of the depenta-nized gasolines used as calibrants. An internal standard can beused periodically to assure that analytical accuracy is main-tained (Note 2).Adjust the val

45、ving so that carrier gas is flowingthrough the instrument in the normal direction. Charge suffi-cient sample to ensure a minimum of 10 % recorder deflectionfor a 0.1 percent sample concentration of 2-methylbutene-2 atthe highest sensitivity. As soon as the last pentene peak(2-methylbutene-2) has bee

46、n eluted, position the valving sothat the carrier gas flow is reversed. After the flow hasstabilized, adjust the base line. Attenuate for the C6+ portionas necessary. The run is complete when the recorder returns tothe base line after elution of the C6portion. This part of thesample will generally e

47、merge as one broad peak with onlyslight indications of any separation. Proceed as described in9.1.2.Column:Precut: SF96-50 silicone fluidAnalyzer: tricresylphosphate plus DC 550 silicone fluid 4.5/1 by wt followed by ethylene glycol in series.FIG. 1 Typical Chromatogram of Light Components in a Cata

48、lytic GasolineD2427063NOTE 2All reverse flow determinations, including the C6and heaviercalibration runs should be made in the same carrier gas flow direction. Allsingle-peak determinations and corresponding calibrations will then bemade in the opposite carrier gas flow direction. The column should

49、be keptfree of high-boiling residues by periodically sweeping with carrier gas forseveral hours in the reverse direction. A level base line will quickly beattained in either flow direction when the column is clean and the systemis free of leaks.9. Calculation9.1 Calculate the percentage of the individual componentsusing the following procedure that applies and report to thenearest 0.1 %.9.1.1 Backflush MethodMeasure the areas of all of thepeaks representing compounds to be reported and that of theinternal standard. Adjust each component peak area by use ofthe p