1、Designation: D6379 11Designation: 436/01Standard Test Method forDetermination of Aromatic Hydrocarbon Types in AviationFuels and Petroleum DistillatesHigh Performance LiquidChromatography Method with Refractive Index Detection1This standard is issued under the fixed designation D6379; the number imm
2、ediately 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 () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThi
3、s test method is intended to be technically equivalent to IP 436-01 with an identical title. 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 alternat
4、ive instrumental testmethods 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 correl
5、ation if necessary.1. Scope*1.1 This test method covers a high performance liquidchromatographic test method for the determination of mono-aromatic and di-aromatic hydrocarbon contents in aviationkerosines and petroleum distillates boiling in the range from 50to 300C, such as Jet A or Jet A-1 fuels.
6、 The total aromaticcontent is calculated from the sum of the individual aromatichydrocarbon-types.NOTE 1Samples with a final boiling point greater than 300C thatcontain tri-aromatic and higher polycyclic aromatic compounds are notdetermined by this test method and should be analyzed by Test MethodD6
7、591 or other suitable equivalent test methods.1.2 This test method is calibrated for distillates containingfrom 10 to 25 % m/m mono-aromatic hydrocarbons and from0 to 7 % m/m di-aromatic hydrocarbons.1.3 The precision of this test method has been establishedfor kerosine boiling range distillates con
8、taining from 10 to25 % m/m mono-aromatic hydrocarbons and from 0 to 7 %m/m di-aromatic hydrocarbons.1.4 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.1.5 This sta
9、ndard does not purport to address the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standa
10、rds:2D4052 Test Method for Density, Relative Density, and APIGravity of Liquids by Digital Density MeterD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD6591 Test Method for Determination of Aromatic Hydro-c
11、arbon Types in Middle DistillatesHigh PerformanceLiquid Chromatography Method with Refractive IndexDetection1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04.0C on Liquid Chromatography.Current
12、 edition approved May 1, 2011. Published June 2011. Originallyapproved in 1999. Last previous edition approved in 2004 as D637904. DOI:10.1520/D6379-11.In the IP, this test method is under the jurisdiction of the StandardizationCommittee.2For referenced ASTM standards, visit the ASTM website, www.as
13、tm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards 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
14、Box C700, West Conshohocken, PA 19428-2959, United States.2.2 Energy Institute Standards:3IP 436 Test Method for Determination of Automatic Hydro-carbon Types in Aviation Fuels and Petroleum Distillates-High Performance Liquid Chromatography Method withRefractive Index3. Terminology3.1 Definitions o
15、f Terms Specific to This Standard:3.1.1 di-aromatic hydrocarbons (DAHs), ncompoundsthat have a longer retention time on the specified polar columnthan the MAHs.3.1.2 mono-aromatic hydrocarbons (MAHs),ncompounds that have a longer retention time on thespecified polar column than the non-aromatic hydr
16、ocarbons buta shorter retention time than the di-aromatic hydrocarbons.3.1.3 non-aromatic hydrocarbons, ncompounds that havea shorter retention time on the specified polar column than themono-aromatic hydrocarbons.3.1.4 total aromatic hydrocarbons, nsum of the MAHsand DAHs.NOTE 2The elution characte
17、ristics of aromatic and non-aromaticcompounds on the specified polar column have not been specificallydetermined for this test method. Published and unpublished data indicatethe major constituents for each hydrocarbon type as follows: (1) Non-aromatic hydrocarbons: acyclic and cyclic alkanes (paraff
18、ins and naph-thenes), mono-alkenes (if present). (2) MAHs: benzenes, tetralins, in-danes, thiophenes, conjugated poly-alkenes. (3) DAHs: naphthalenes,biphenyls, indenes, fluorenes, acenaphthenes, benzothiophenes.4. Summary of Test Method4.1 The test portion is diluted 1:1 with the mobile phase,such
19、as heptane, and a fixed volume of this solution injectedinto a high performance liquid chromatograph fitted with apolar column. This column has little affinity for the non-aromatic hydrocarbons and exhibits a pronounced selectivityfor aromatic hydrocarbons. As a result of this selectivity, thearomat
20、ic hydrocarbons are separated from the non-aromatichydrocarbons into distinct bands in accordance with their ringstructure, that is, MAHs and DAHs.4.2 The column is connected to a refractive index detectorthat detects the components as they elute from the column. Theelectronic signal from the detect
21、or is continually monitored bya data processor. The amplitudes of the signals (peak areas)from the sample aromatics are compared with those obtainedfrom previously-run calibration standards in order to calculatethe percent m/m MAHs and DAHs in the sample. The sum ofthe MAHs and DAHs is reported as t
22、he total aromatic content(percent m/m) of the sample.5. Significance and Use5.1 Accurate quantitative information on aromatic hydro-carbon types can be useful in determining the effects ofpetroleum processes on production of various finished fuels.This information can also be useful for indicating t
23、he quality offuels and for assessing the relative combustion properties offinished fuels.6. Apparatus6.1 High Performance Liquid Chromatograph (HPLC)Any high performance liquid chromatograph capable of pump-ing the mobile phase at flow rates between 0.5 and 1.5 mL/min3Available from Energy Institute
24、, 61 New Cavendish St., London, WIG 7AR,U.K.FIG. 1 Example Chromatogram of an Aviation Fuel Showing Integration Points and Aromatic Hydrocarbon Type GroupsD6379 112with a precision better than 0.5 % and a pulsation of 1 % fullscale deflection under the test conditions described in Section9. See Fig.
25、 1.6.2 Sample Injection SystemThe sample injection systemshall be capable of injecting 10 L (nominal) of samplesolution with a repeatability better than 2 %.6.2.1 An equal and constant volume of the calibration andsample solutions shall be injected into the chromatograph.Both manual and automatic sa
26、mple injection systems (usingeither complete or partial filling of the sample loop) will, whenused correctly, meet the repeatability requirements laid downin 6.2. When using the partial loop filling mode, it is recom-mended that the injection volume should be less than half thetotal loop volume. For
27、 complete filling of the loop, best resultsare obtained by overfilling the loop at least six times.6.2.2 Sample injection volumes other than 10 L (typicallyin the range from 3 to 20 L) may be used provided they meetthe requirements laid down for injection repeatability (see 6.2),refractive index sen
28、sitivity and linearity (see 9.4 and 10.1), andcolumn resolution (see 9.4)6.3 Sample Filter (Optional)A microfilter of porosity0.45 m or less, which is chemically-inert towards hydrocar-bon solvents, is recommended for the removal of particulatematter from the sample solutions.6.4 Column SystemAny st
29、ainless steel HPLC column(s)packed with an approved amino-bonded (or polar amino/cyano-bonded) silica stationary phase4is suitable, provided itmeets the resolution requirements laid down in 9.4.3. Columnlengths from 150 to 300 mm with an internal diameter from 4to 5 mm and packed with 3 or 5 m parti
30、cle size stationaryphase have been found to be satisfactory. The use of a guardcolumn (for example, 30 by 4.6-mm internal diameter) packedwith silica or amino-bonded silica is recommended but notessential.6.5 HPLC Column OvenAny suitable HPLC column oven(block heating or air circulating) capable of
31、maintaining aconstant temperature (61C) within the range from 20 to 40C.NOTE 3The refractive index detector is sensitive to both sudden andgradual changes in the temperature of the eluent. All necessary precau-tions should be taken to establish constant temperature conditionsthroughout the liquid ch
32、romatograph system.NOTE 4Alternative forms of temperature control, for example,temperature-controlled laboratories, are permitted.6.6 Refractive Index DetectorAny refractive index detec-tor may be used provided it is capable of being operated overthe refractive index range from 1.3 to 1.6, meets the
33、 sensitivityrequirement specified in 9.4.2, gives a linear response over thecalibration range, and has a suitable output signal for the datasystem. If the refractive index detector has a facility forindependent temperature control, it is recommended that this isset at the same temperature as the col
34、umn oven.6.7 Computer or Computing IntegratorAny data systemcan be used provided it is compatible with the refractive indexdetector, has a minimum sampling rate of 1 Hz, and is capableof peak area and retention time measurement. The data systemshould also have minimum facilities for post-analysis da
35、taprocessing, such as baseline correction and reintegration. Theability to perform automatic peak detection and identificationand to calculate sample concentrations from peak area mea-surements is recommended but not essential.6.8 Volumetric Flasks, Grade B, or better, of 10 mL and 100mL capacity.6.
36、9 Analytical Balance, accurate to 60.0001 g.7. Reagents7.1 Cyclohexane, $99 % pure.NOTE 5Cyclohexane may contain benzene as an impurity.7.2 Heptane, HPLC Grade. For use as HPLC mobile phase.(WarningHydrocarbon solvents are highly flammable andmay cause irritation by inhalation, ingestion, or skin co
37、ntact.)NOTE 6It is recommended practice to degas the HPLC mobile phasebefore use.7.3 1-Methylnaphthalene, $ 98 % pure. (WarningGloves should be worn when handling aromatic compounds(for example, disposable vinyl gloves).)NOTE 7Purity is determined by gas chromatography with flameionization detection
38、. The highest purity standards available should beused. Standards of $ 98 % purity are commercially available from allmajor suppliers.7.4 o-Xylene (1,2-Dimethylbenzene), $ 98 % pure.8. Sampling8.1 The laboratory fuel sample from which an aliquot isbeing drawn for the purposes of this test method sha
39、ll berepresentative of the lot of fuel. The laboratory sample shouldbe obtained by following Practice D4057 or D4177,orasimilar standard.9. Apparatus Preparation9.1 Set up the chromatograph, injection system, column andcolumn oven, refractive index detector, and computing inte-grator in accordance w
40、ith the appropriate equipment manuals.The HPLC column shall be installed in the column oven.NOTE 8The column oven is optional if alternative arrangements aremade to maintain a constant temperature environment, for example, atemperature-controlled laboratory (see 6.5).9.2 Adjust the flow rate of the
41、mobile phase to a constant 1.06 0.2 mL/min and ensure that the reference cell of therefractive index detector is full of mobile phase (see 6.6.1).Allow the temperature of the column oven (and refractiveindex detector if equipped with temperature control) to stabi-lize.9.2.1 To minimize drift, it is
42、essential to make sure that thereference cell is full of solvent. The best way to accomplish thisis either to (1) flush the mobile phase through the reference cell(then isolate the reference cell to prevent evaporation of thesolvent) immediately prior to analysis, or (2) continuouslymake up for solv
43、ent evaporation by supplying a steady flowthrough the reference cell. The makeup flow is optimized sothat reference and analytical cell mismatch due to drying-out,temperature, or pressure gradients are minimized. Typically4Stationary phases known to give suitable results include Spherisorb 3NH2,Sphe
44、risorb 5NH2, Partisil 5 PAC, and Partisphere 5 PAC.D6379 113this can be accomplished with a makeup flow set at one tenthof the analytical flow.NOTE 9The flow rate may be adjusted (typically within the rangefrom 0.8 to 1.2 mL/min) to an optimum value to meet the resolutionrequirements specified in 9.
45、4.3.9.3 Prepare a system resolution standard (SRS) by weighingcyclohexane (1.0 6 0.1 g), o-xylene (0.5 6 0.05 g), and1-methylnaphthalene (0.05 6 0.005 g) into a 100 mL volumet-ric flask and making up to the mark with heptane.NOTE 10The SRS may be kept for up to one year if stored in a tightlystopper
46、ed bottle in a dark place between 5 and 25C.9.4 When operating conditions are steady, as indicated by astable horizontal baseline, inject 10 L of the SRS (see 9.3) andrecord the chromatogram using the data system.NOTE 11Baseline drift over the period of the HPLC analysis runshould be less than 0.5 %
47、 of the peak height for cyclohexane. A baselinedrift greater than this indicates problems with the temperature control ofthe column/refractive index or polar material eluting from the column, orboth. A period of up to 1 h may be required before the liquid chromato-graph reaches steady state conditio
48、ns.9.4.1 Ensure that baseline separation is obtained between allthree components of the SRS.9.4.2 Ensure that the data system can accurately measure thepeak area of 1-methylnaphthalene.NOTE 12The S/N (signal to noise) ratio for 1-methylnaphthaleneshould be 3:1 or greater.9.4.3 Ensure that the resolu
49、tion between cyclohexane ando-xylene is not less than five.9.4.3.1 Column ResolutionCalculate the resolution be-tween cyclohexane and o-xylene as follows:Resolution 52 3 t2 t1!1.699 3 y21 y1!(1)where:t1= retention time of cyclohexane peak in seconds,t2= retention time of o-xylene peak in seconds,y1= half-height peak width of cyclohexane in seconds, andy2= half-height peak width of o-xylene in seconds.If the resolution is less than five, check to see that all systemcomponents are functioning correctly and that the chromato-graphic dead volum
