ASTM D6591-2018 Standard Test Method for Determination of Aromatic Hydrocarbon Types in Middle Distillates&x2014 High Performance Liquid Chromatography Method w.pdf

1、Designation: D6591 18Designation: 548/06Standard Test Method forDetermination of Aromatic Hydrocarbon Types in MiddleDistillatesHigh Performance Liquid ChromatographyMethod with Refractive Index Detection1This standard is issued under the fixed designation D6591; the number immediately following the

2、 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 () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis test method has the

3、same title as IP 548-06 and is intended to be technically equivalent. TheASTM format for test methods has been used, and where possible, equivalent ASTM test methodshave replaced the IP or ISO standards.The test method is intended to be used as one of several possible alternative instrumental testme

4、thods that are aimed at quantitative determination of hydrocarbon types in fuels. This does notimply that a correlation necessarily exists between this and any other test method intended to give thisinformation, and it is the responsibility of the user to determine such correlation if necessary.1. S

5、cope*1.1 This test method covers a high performance liquidchromatographic test method for the determination of mono-aromatic, di-aromatic, tri+-aromatic, and polycyclic aromatichydrocarbon contents in diesel fuels and petroleum distillatesboiling in the range from 150 C to 400 C. The total aromaticc

6、ontent in % m/m is calculated from the sum of the corre-sponding individual aromatic hydrocarbon types.NOTE 1Aviation fuels and petroleum distillates with a boiling pointrange from 50 C to 300 C are not determined by this test method andshould be analyzed by Test Method, D6379 or other suitable equi

7、valenttest methods.1.2 The precision of this test method has been establishedfor diesel fuels and their blending components, containingfrom 4 % to 40 % (m/m) mono-aromatic hydrocarbons, 0 % to20 % (m/m) di-aromatic hydrocarbons, 0 % to 6 % (m/m)tri+-aromatic hydrocarbons, 0 % to 26 % (m/m) polycycli

8、caromatic hydrocarbons, and 4 % to 65 % (mm) total aromatichydrocarbons.1.3 Compounds containing sulfur, nitrogen, and oxygen arepossible interferents. Mono-alkenes do not interfere, but con-jugated di- and poly-alkenes, if present, are possible interfer-ents.1.4 By convention, this standard defines

9、 the aromatic hy-drocarbon types on the basis of their elution characteristicsfrom the specified liquid chromatography column relative tomodel aromatic compounds. Quantification is by externalcalibration using a single aromatic compound, which may ormay not be representative of the aromatics in the

10、sample, foreach aromatic hydrocarbon type. Alternative techniques andmethods may classify and quantify individual aromatic hydro-carbon types differently.1.5 Fatty Acid Methyl Esters (FAME), if present, interferewith tri+-aromatic hydrocarbons. If this method is used fordiesel containing FAME, the a

11、mount of tri+-aromatics will beover estimated.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, health, and environmental practices and deter-mine the applic

12、ability of regulatory limitations prior to use.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by th

13、e World Trade Organization TechnicalBarriers to Trade (TBT) Committee.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.04.0C on Liquid Chromatography.This test method is based on m

14、aterial published in IP Standard Methods forAnalysis and Testing of Petroleum and Related Products and British Standard 2000Parts, copyright The Institute of Petroleum, 61 New Cavendish Street, LondonW1M 8AR. Adapted with permission of The Institute of Petroleum.Current edition approved Oct. 1, 2018

15、. Published December 2018. Originallyapproved in 2000. Last previous edition approved in 2017 as D6591 11 (2017).DOI: 10.1520/D6591-18.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.

16、United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barr

17、iers to Trade (TBT) Committee.12. Referenced Documents2.1 ASTM Standards:2D1319 Test Method for Hydrocarbon Types in Liquid Petro-leum Products by Fluorescent Indicator AdsorptionD2425 Test Method for Hydrocarbon Types in Middle Dis-tillates by Mass SpectrometryD4057 Practice for Manual Sampling of

18、Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD5186 Test Method for Determination of the AromaticContent and Polynuclear Aromatic Content of DieselFuels and Aviation Turbine Fuels By Supercritical FluidChromatographyD6379 Test Method for Deter

19、mination of Aromatic Hydro-carbon Types in Aviation Fuels and PetroleumDistillatesHigh Performance Liquid ChromatographyMethod with Refractive Index Detection2.2 Energy Institute Standard:3IP 548 Test Method for Determination of Aromatic Hydro-carbon Types in Middle Distillates High PerformanceLiqui

20、d Chromatography Method with Refractive IndexDetection3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 di-aromatic hydrocarbons (DAHs), nin this testmethod, compounds that have a longer retention time on thespecified polar column than the majority of mono-aromatichydrocarbons,

21、but a shorter retention time than the majority oftri+-aromatic hydrocarbons.3.1.2 mono-aromatic hydrocarbons (MAHs), nin this testmethod, compounds that have a longer retention time on thespecified polar column than the majority of non-aromatichydrocarbons but a shorter retention time than the major

22、ity ofDAHs.3.1.3 non-aromatic hydrocarbons, nin this test method,compounds that have a shorter retention time on the specifiedpolar column than the majority of mono-aromatic hydrocar-bons.3.1.4 polycyclic aromatic hydrocarbons (POLY-AHs), ninthis test method, sum of the di-aromatic hydrocarbons andt

23、ri+-aromatic hydrocarbons.3.1.5 total aromatic hydrocarbons, nin this test method,sum of the MAHs, DAHs, and T+AHs.3.1.6 tri+-aromatic hydrocarbons (T+AHs), nin this testmethod, compounds that have a longer retention time on thespecified polar column than the majority of DAHs.3.1.6.1 DiscussionThe e

24、lution characteristics of aromaticand non-aromatic compounds on the specified polar columnhave not been specifically determined for this test method.Published and unpublished data indicate the major constituentsfor each hydrocarbon type as follows: (1) non-aromatic hydro-carbons: acyclic and cyclic

25、alkanes (paraffins and naphthenes),mono-alkenes (if present), (2) MAHs: benzenes, tetralins,indanes, thiophenes, and conjugated poly-alkenes, (3) DAHs:naphthalenes, biphenyls, indenes, fluorenes, acenaphthenes,and benzothiophenes and dibenzothiophenes, (4) T+AHs:phenanthrenes, pyrenes, fluoranthenes

26、, chrysenes,triphenylenes, and benzanthracenes.4. Summary of Test Method4.1 A known mass of sample is diluted in the mobile phase,and a fixed volume of this solution is injected into a highperformance liquid chromatograph, fitted with a polar column.This column has little affinity for the non-aromat

27、ic hydrocar-bons while exhibiting a pronounced selectivity for aromatichydrocarbons. As a result of this selectivity, the aromatichydrocarbons are separated from the non-aromatic hydrocar-bons into distinct bands in accordance with their ring structure,that is, MAHs, DAHs, and T+AHs. At a predetermi

28、ned time,after the elution of the DAHs, the column is backflushed toelute the T+AHs as a single sharp band.4.2 The column is connected to a refractive index detectorthat detects the components as they elute from the column. Theelectronic signal from the detector is continually monitored bya data pro

29、cessor. The amplitudes of the signals (peak areas)from the sample aromatics are compared with those obtainedfrom previously measured calibration standards in order tocalculate percent m/m MAHs, DAHs, and T+AHs in thesample. The sum of the percentages by mass of DAHs andT+AHs is reported as the perce

30、nt m/m POLY-AH. The sum ofMAHs, DAHs, and T+AHs is reported as the total aromaticcontent (percent m/m) of the sample.5. Significance and Use5.1 The aromatic hydrocarbon content of motor diesel fuelis a factor that can affect exhaust emissions and fuel combus-tion characteristics, as measured by ceta

31、ne number.5.2 The United States Environmental Protection Agency(US EPA) regulates the aromatic content of diesel fuels.California Air Resources Board (CARB) regulations placelimits on the total aromatics content and polynuclear aromatichydrocarbon content of motor diesel fuel, thus requiring anappro

32、priate analytical determination to ensure compliance withthe regulations.5.3 This test method is applicable to materials in the sameboiling range as motor diesel fuels and is unaffected by fuelcoloration. Test Method D1319, which has been mandated bythe US EPA for the determination of aromatics in m

33、otor dieselfuel, excludes materials with final boiling points greater than315 C (600 F) from its scope. Test Method D2425 is appli-cable to the determination of both total aromatics and poly-nuclear aromatic hydrocarbons in diesel fuel, but is much morecostly and time-consuming to perform. Test Meth

34、od D5186,currently specified by CARB, is also applicable to the deter-mination of both total aromatics and polynuclear aromatichydrocarbons in diesel fuel. Test Method D5186, however,2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.

35、org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,U.K., http:/www.energyinst.org.D6591 182specifies the use of supercritical fluid chromatography equip-ment

36、 that may not be readily available.NOTE 2Test Method D5186 was previously specified by CARB as analternative to Test Method D1319.6. Apparatus6.1 High Performance Liquid Chromatograph (HPLC)Any HPLC capable of pumping the mobile phase at flow ratesbetween 0.5 mLmin and 1.5 mLmin, with a precision be

37、tterthan 0.5 % and a pulsation of 99 % pure.NOTE 7Cyclohexane may contain benzene as an impurity.7.2 Heptane, HPLC Grade. For use as HPLC mobile phase.(WarningHeptane is highly flammable and may causeirritation by inhalation, ingestion, or skin contact.)NOTE 8Batch to batch variation of the solvent

38、quality in terms ofwater content, viscosity, refractive index and purity could cause unpre-dictable column behavior. Drying and filtering the mobile phase couldhelp to reduce the effect of the trace impurities in the solvent.NOTE 9It is recommended practice to degas the HPLC mobile phasebefore use;

39、this can be done conveniently, on-line, or off-line by heliumsparging, vacuum degassing or ultrasonic agitation.Afailure to de-gas themobile phase may lead to negative peaks.7.3 o-Xylene (1,2-Dimethylbenzene), 98 % pure.7.4 1-Methylnaphthalene, 98 % pure.7.5 Phenanthrene, 98 % pure.7.6 Dibenzothioph

40、ene, 95 % pure.7.7 9-Methylanthracene, 95 % pure. (WarningGlovesshould be worn when handling aromatic compounds (forexample, disposable vinyl gloves).)NOTE 10Purity is determined by gas chromatography with flameionization detection. The highest purity standards available should beused.8. Sampling8.1

41、 Unless otherwise specified in the commodityspecification, samples are taken by following Practice D4057or D4177, or a similar standard. In certain situations, samplingis done in accordance with the requirements of nationalstandards or regulations for the sampling of the product undertest.D6591 1839

42、. Apparatus Preparation9.1 Set up the chromatograph, injection system, column,backflush valve, column oven, refractive index detector, andcomputing integrator in accordance with the appropriate equip-ment manuals. Install the HPLC column and backflush valve inthe column oven. Insert the backflush va

43、lve so that the detectoris always connected independently of the direction of flowthrough the column (see Fig. 1). Maintain the sample injectionvalve at the same temperature as the sample solution; in mostcases this will be at room temperature.NOTE 11The column oven is optional if alternative arrang

44、ements aremade to maintain a constant temperature environment, for example, atemperature-controlled laboratory (see 6.5). It is recommended to installthe backflush valve in the column oven and to install the apparatus awayfrom drafts (that is, not near air-conditioning unit or fume cupboard).Pipewor

45、k and/or valving which is not temperature controlled should beinsulated.NOTE 12Regular maintenance of the liquid chromatograph and itscomponents is important to ensure consistent performance. Leakages andpartial blockage of filters, frits, injector needles and valve rotors canproduce flow rate incon

46、sistencies and poor injector performance.9.2 Adjust the flow rate of the mobile phase to a constant1.0 mLmin 6 0.2 mLmin, and ensure the reference cell ofthe refractive index detector is full of mobile phase. Allow thetemperature of the column oven (and refractive index detector,if equipped with tem

47、perature control) to stabilize.9.2.1 To minimize drift, it is essential to make sure thereference cell is full of solvent.The best way to accomplish thisis either (1) to flush the mobile phase through the reference cell(then isolate the reference cell to prevent evaporation of thesolvent) immediatel

48、y prior to analysis, or (2) to continuouslymake up for solvent evaporation by supplying a steady flowthrough the reference cell. The make-up flow is optimized sothat reference and analytical cell miss-match due to drying-out,temperature, or pressure gradients are minimized. Typically,this can be acc

49、omplished with a make-up flow set at one tenthof the analytical flow.NOTE 13The flow rate may be adjusted (typically within the rangefrom 0.8 mL min to 1.2 mL min) to an optimum value in order to meetthe resolution requirements specified in 9.4.3.9.3 Prepare a system performance standard (SPS) by weigh-ing cyclohexane (1.0 g 6 0.1 g), o-xylene (0.5 g 6 0.05 g),dibenzothiophene (0.05 g 6 0.005 g) and 9-methylanthracene(0.05 g 6 0.005 g) into a 100 mL volumetric flask and makingup to the mark with heptane. Ensure that the dibenzothiophen