1、Designation: D 5186 03An American National StandardStandard Test Method forDetermination of the Aromatic Content and PolynuclearAromatic Content of Diesel Fuels and Aviation Turbine FuelsBy Supercritical Fluid Chromatography1This standard is issued under the fixed designation D 5186; the number imme
2、diately following the designation indicates the year 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. Scope *1.1 T
3、his test method covers the determination of the totalamounts of monoaromatic and polynuclear aromatic hydrocar-bon compounds in motor diesel fuels, aviation turbine fuels,and blend stocks by supercritical fluid chromatography (SFC).The range of aromatics concentration to which this test methodis app
4、licable is from 1 to 75 mass %. The range of polynucleararomatic hydrocarbon concentrations to which this test methodis applicable is from 0.5 to 50 mass %.1.2 The values stated in SI units are to be regarded asstandard. The values stated in inch-pound units are for infor-mation only.1.3 This standa
5、rd 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 Documents2.1 AST
6、M Standards:D 1319 Test Method for Hydrocarbon Types in LiquidPetroleum Products by Fluorescent Indicator Adsorption2D 1655 Specification for Aviation Turbine Fuels2D 2425 Test Method for Hydrocarbon Types in MiddleDistillates by Mass Spectrometry2D 6299 Practice for Applying Statistical Quality Ass
7、uranceTechniques to Evaluate Analytical Measurement SystemPerformance33. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 critical pressure, nthat pressure needed to condensea gas at the critical temperature.3.1.2 critical temperature, nthe highest temperature atwhich a gaseous fl
8、uid may be converted to a liquid by meansof compression.3.1.3 mononuclear aromatic hydrocarbons, nhydro-carbon compounds containing exactly one aromatic ring. Thisgroup includes benzene, alkyl-substituted benzenes, indans,tetralins, alkyl-substituted indans, and alkyl-substituted tetra-lins.3.1.4 po
9、lynuclear aromatic hydrocarbons, nall hydrocar-bon compounds containing two or more aromatic rings. Theserings may be fused as in naphthalene and phenanthrene, orseparate as in biphenyl.3.1.5 restrictor, na device, attached to the outlet of achromatographic column, to restrict the mobile phase flows
10、uch that the mobile phase is maintained in the supercriticalstate throughout the chromatographic column.3.1.6 supercritical fluid, na fluid maintained in a thermo-dynamic state above its critical temperature and critical pres-sure.3.1.7 supercritical fluid chromatography, na class ofchromatography t
11、hat employs supercritical fluids as mobilephases.4. Summary of Test Method4.1 A small aliquot of the fuel sample is injected onto apacked silica adsorption column and eluted using supercriticalcarbon dioxide mobile phase. Monoaromatics and polynucleararomatics in the sample are separated from nonaro
12、matics anddetected using a flame ionization detector.4.2 The detector response to hydrocarbons is recordedthroughout the analysis time. The chromatographic areascorresponding to the monoaromatic, polynuclear aromatic, andnonaromatic components are determined and the mass %content of each of these gr
13、oups in the fuel is calculated by areanormalization.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04 on Hydrocarbon Analysis.Current edition approved May 10, 2003. Published June 2003. Origina
14、llyapproved in 1991. Last previous edition approved in 1999 as D 518699.2Annual Book of ASTM Standards, Vol 05.01.3Annual Book of ASTM Standards, Vol 05.03.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consho
15、hocken, PA 19428-2959, United States.5. Significance and Use5.1 The aromatic hydrocarbon content of motor diesel fuelsis a factor that can affect their cetane number and exhaustemissions. The aromatic hydrocarbon content and the naphtha-lenes content of aviation turbine fuels affect their combustion
16、characteristics and smoke-forming tendencies. These proper-ties represent specifications for aviation turbine fuels (seeSpecification D 1655).5.2 The United States Environmental Protection Agency(USEPA) regulates the aromatic content of diesel fuels. Cali-fornia Air Resources Board (CARB) regulation
17、s place limits onthe total aromatics content and polynuclear aromatic hydrocar-bon content of motor diesel fuel, thus requiring an appropriateanalytical determination to ensure compliance with the regu-lations. Producers of diesel fuels will require similar determi-nations for process and quality co
18、ntrol. This test method can beused to make such determinations.5.3 This test method is applicable to materials in the boilingrange of motor diesel fuels and is unaffected by fuel coloration.Test Method D 1319, which has been mandated by the USEPAfor the determination of aromatics in motor diesel fue
19、l,excludes materials with final boiling points greater than 315C(600F) from its scope. Test Method D 2425 is applicable tothe determination of both total aromatics and polynucleararomatic hydrocarbons in diesel fuel, but is much more costlyand time-consuming to perform.5.4 Results obtained by this t
20、est method have been shown tobe statistically more precise than those obtained from TestMethod D 1319 for typical diesel fuels, and this test methodhas a shorter analysis time.4Cooperative study data5havefound this test method to be more precise than the publishedprecision of Test Method D 1319 when
21、 applied to aviationturbine fuels and diesel fuels. Results from this test method fortotal polynuclear aromatic hydrocarbons are also expected tobe at least as precise as those of Test Method D 2425.6. Apparatus6.1 Supercritical Fluid Chromatograph (SFC)Any SFCinstrumentation can be used that has th
22、e following capabilitiesand meets the performance requirements in Section 8.6.1.1 PumpThe SFC instrumentation must include apump capable of delivering supercritical carbon dioxide to thecolumn without pressure fluctuations and at constant flow. Thepump is typically a single-stroke-type (syringe) pum
23、p or ahighly dampened reciprocating pump with pressure fluctua-tions not exceeding 60.3 % of the operating pressure.6.1.2 DetectorThis test method is limited to the use of theflame ionization detector (FID). The detector must havesufficient sensitivity to detect 0.1 mass % toluene in hexade-cane und
24、er instrument conditions employed in this test method.6.1.3 Column Temperature ControlThe chromatographmust be capable of column temperature control of at least60.5C (1F) at the operating temperature.6.1.4 Sample Inlet SystemA liquid sample injection valveis required, capable of reproducibly introdu
25、cing samples in the0.05 to 0.50-L liquid volume range. The inlet system shouldbe operated at between 25 and 30C. The sample inlet systemmust be connected to the chromatographic column so that lossof chromatographic efficiency is avoided.6.1.5 Post-column RestrictorA device capable of main-taining mo
26、bile phase supercritical conditions within the col-umn and up to the detector inlet must be connected to the endof the column.6.1.6 ColumnAny liquid or supercritical fluid chromato-graphic column may be used that provides separation ofnonaromatic, monoaromatic, and polynuclear aromatic hydro-carbons
27、 and meets the performance requirements of Section 8.Some columns and conditions that have been used successfullyare shown in Table 1.6.1.7 IntegratorMeans must be provided for the determi-nation of both discrete chromatographic peak areas and theaccumulated area under the chromatogram. This can be
28、doneby means of a computer or electronic integrator. The computeror integrator must have the capability of correcting for baselineshifts during the run.4Supporting data (obtained in a comparison study of Test Methods D 1319 andD 5186) have been filed at ASTM International Headquarters and may be obt
29、ainedby requesting Research Report RR: D02-1276.5Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D02-1388.TABLE 1 Typical Operating ConditionsParameter A B C DColumn Vendor Chromegasphere Suprex YMC Hewlett-PackardPacking SI 60
30、Petro-Pak SASI 60 HP-HydrocarbonLength (mm) 250 250 500 250ID (mm) 2214.6Particle size, mm 5 5 10 5Temperature, C 30 40 30 28CO2pressure, atm 115 125 115 197BFlow rate, mL/minC40 37 33 20Injection, L 0.1 0.1 0.06 0.5FID, temperature, C 350 385 350 350Air, mL/min 300 800 280 400H2, mL/min 50 80 33 50
31、Air makeup, mL/min 15 n/a n/a n/aAnalysis time, min 1520 15 24 5ATrademark.BPost-column (downstream) pressure regulation.CDecompressed, gaseous CO2flow, measured at column exit.D51860327. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise
32、indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.6Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit
33、its use without lessening the accuracy ofthe determination.7.2 AirZero grade (hydrocarbon-free) is used as the FIDoxidant. (WarningAir is usually supplied as a compressedgas under high pressure and supports combustion.)7.3 Carbon Dioxide (CO2)Supercritical fluid chromato-graphic grade, 99.99 % minim
34、um purity, supplied pressurizedin a cylinder equipped with a dip tube for removal of liquidCO2.(WarningLiquid at high pressure. Release of pressureresults in production of extremely cold solid CO2and gas,which can dilute available atmospheric oxygen.)7.4 Check StandardA commercial standard reference
35、 ma-terial, which has accepted reference values, in accordance within Section 6 on Reference Materials in Practice D 6299.Alternatively, samples subjected to round robin may be used ascheck standards. It is important that the standard deviation ofthe values of the laboratory exchange program not be
36、statisti-cally greater than the reproducibility for the test method.7.5 HydrogenHydrogen of high quality (hydrocarbon-free) is used as the fuel for the flame ionization detector.(WarningHydrogen is usually supplied under high pressureand is extremely flammable.)7.6 Performance MixtureA quantitative
37、mixture of ap-proximately 75 mass % hexadecane (n-C16), 20 mass %toluene, 3 mass % tetralin (1,2,3,4-tetrahydronaphthalene), and2 mass % naphthalene is used for performance checks.7.7 Quality Control SampleA homogeneous material hav-ing similar physical and chemical properties to the samples tobe an
38、alyzed. The choice of such material should be guided bySection 6 on Reference Materials in Practice D 6299. Ex-amples of such material can be motor diesel fuel, aviationturbine fuel or other typical samples containing aromatics andpolynuclear aromatics similar to the samples to be analyzed.8. Prepar
39、ation of Apparatus8.1 Install the SFC instrumentation in accordance with themanufacturers instructions. System operating conditions willdepend upon the column used and optimization of perfor-mance. Conditions listed in Table 1 have been used success-fully. If the performance characteristics in terms
40、 of retentionand resolution, specified in 8.2, are not achieved, modify thetemperature, pressure, or mobile phase flow rate to achievecompliance. A column of low activity may be reactivated bysolvent rinsing using established liquid chromatography acti-vation techniques.NOTE 1This temperature can be
41、 increased (up to 40C) if theresolution between the monoaromatics and polynuclear aromatics is notsatisfactory. Lower temperatures are suggested to improve resolutionbetween nonaromatics and monoaromatics.8.2 System Performance:8.2.1 ResolutionAnalyze the performance mixture pre-pared in 7.6. The re
42、solution between the nonaromatics andmonoaromatics (RNM) must be at least four and resolutionbetween the monoaromatics and polynuclear aromatics (RMD)must be at least two when calculated in accordance with thefollowing equations:RNM52 3 t22 t1!1.699 3 y21 y1!(1)RMD52 3 t42 t3!1.699 3 y41 y3!(2)where
43、:t1= time for the n-C16peak apex, s,t2= time for the toluene peak apex, s,t3= time for the tetralin peak apex, s,t4= time for the naphthalene peak apex, s,y1= peak width at half height of n-C16peak, s,y2= peak width at half height of toluene, s,y3= peak width at half height of tetralin, s, andy4= pe
44、ak width at half height of naphthalene, s.8.2.2 Retention Time ReproducibilityRepeated injectionsof the performance mixture must show a retention timerepeatability (maximum difference between duplicate runs) ofnot more than 0.5 % for n-C16and toluene peaks.8.2.3 Detector Accuracy TestThis test metho
45、d assumesthat the FID response approximates the theoretical unit carbonresponse. To verify this assumption, analyze the performancemixture and calculate the response factors, relative to hexade-cane (RRFi), for each of the components in the performancemix, using the following equations:RFi5AiMi(3)RR
46、Fi5RFiRFC16(4)where:Ai= Component i in performance mix, area %,Mi= Component i in performance mix, known mass%,RFi= response factor of Component i,RFC16= response factor of hexadecane in performancemix, andRRFi= relative response factor of Component i.These values can then be compared to the theoret
47、icalresponse factor for each component in the performance mix ascalculated by the following equation:RRFtheo5S12.01 3 nMWD3S226.412.01 3 16D(5)where:12.01 = atomic mass of carbon,n = number of carbon atoms in component molecule,MW = molecular mass of component,226.4 = molecular mass of hexadecane, a
48、nd6Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmaco
49、peiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D518603316 = number of carbon atoms in hexadecane molecule.The measured RRF for each component in the test mixturemust be within 610 % of the theoretical value as calculatedwith Eq 5 or summarized in Table 2. If this is not attained, itwill be necessary to vary the injection volume, restrictorposition, or detector gas flows, or combination thereof, untilagreement is attained.8.2.4 Detector Linearity Check:8.2.4.1 The following procedure has been found to be u
