1、Designation: D5986 96 (Reapproved 2011)Standard Test Method forDetermination of Oxygenates, Benzene, Toluene, C8C12Aromatics and Total Aromatics in Finished Gasoline by GasChromatography/Fourier Transform Infrared Spectroscopy1This standard is issued under the fixed designation D5986; 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.1. Scope1.1 Thi
3、s test method covers the quantitative determinationof oxygenates: methyl-t-butylether (MTBE), di-isopropyl ether(DIPE), ethyl-t-butylether (ETBE), t-amylmethyl ether(TAME), methanol (MeOH), ethanol (EtOH), 2-propanol (2-PrOH), t-butanol (t-BuOH), 1-propanol (1-PrOH), 2-butanol(2-BuOH), i-butanol (i-
4、BuOH), 1-butanol (1-BuOH); benzene,toluene and C8C12aromatics, and total aromatics in finishedmotor gasoline by gas chromatography/Fourier Transforminfrared spectroscopy (GC/FTIR).1.2 This test method covers the following concentrationranges: 0.120 volume % per component for ethers andalcohols; 0.12
5、 volume % benzene; 115 volume % fortoluene, 1040 volume % total (C6C12) aromatics.1.3 The method has not been tested by ASTM for refineryindividual hydrocarbon process streams, such as reformates,fluid catalytic cracking naphthas, etc., used in blending ofgasolines.1.4 The values stated in SI units
6、are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 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 and health practic
7、es and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1298 Test Method for Density, Relative Density (SpecificGravity), or API Gravity of Crude Petroleum and LiquidPetroleum Products by Hydrometer MethodD4052 Test Method for Density, R
8、elative Density, and APIGravity of Liquids by Digital Density MeterD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4307 Practice for Preparation of Liquid Blends for Use asAnalytical Standards3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 aromaticsrefers
9、 to any organic compound contain-ing a benzene or naphthalene ring.3.1.2 calibrated aromatic componentin this test method,refers to the individual aromatic components which have aspecific calibration.3.1.3 cool on-column injectorin gas chromatography,adirect sample introduction system which is set a
10、t a temperatureat or below the boiling point of solutes or solvent on injectionand then heated at a rate equal to or greater than the column.Normally used to eliminate boiling point discrimination oninjection or to reduce adsorption, or both, on glass liners withininjectors. The sample is injected d
11、irectly into the head of thecapillary column tubing or retention gap.3.1.4 Gram-Schmidt chromatograma nonselective sum-mation of total intensity from a spectral scan per unit timewhich resembles in profile a flame ionization detector chro-matogram.3.1.5 retention gapin gas chromatography, refers to
12、adeactivated precolumn which acts as a zone of low retentionpower for reconcentrating bands in space. The polarity of theprecolumn must be similar to that of the analytical column.3.1.6 selective wavelength chromatogram (SWC)in thistest method, refers to a selective chromatogram obtained bysumming t
13、he spectral intensity in a narrow spectral wavelengthor frequency range as a function of elution time which isunique to the compound being quantitated.3.1.7 uncalibrated aromatic componentin this testmethod, refers to individual aromatics for which a calibration isnot available and whose concentrati
14、ons are estimated from theresponse factor of a calibrated aromatic component.1This 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.Current edition approved May 1, 2
15、011. Published May 2011. Originallyapproved in 1996. Last previous edition approved in 2006 as D5986 96 (2006).DOI: 10.1520/D5986-96R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume in
16、formation, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.8 wall coated open tubular (WCOT)a type of capil-lary column prepared by coating or bonding the inside wal
17、l ofthe capillary with a thin film of stationary phase.4. Summary of Test Method4.1 A gas chromatograph equipped with a methylsiliconeWCOT column is interfaced to a Fourier transform infraredspectrometer. The sample is injected through a cool on-columninjector capable of injecting a small sample siz
18、e withoutoverloading the column.4.2 Calibration is performed using mixtures of specifiedpure oxygenates and aromatic hydrocarbons on a mass basis.Volume % data is calculated from the densities of the indi-vidual components and the density of the sample. Multipointcalibrations consisting of at least
19、five levels and bracketing theconcentration of the specified individual aromatics is required.Unidentified aromatic hydrocarbons present which have notbeen specifically calibrated for are quantitated using theresponse factor of 1,2,3,5-tetramethylbenzene and summedwith the other calibrated aromatic
20、components to obtain a totalaromatic concentration of the sample.4.3 Specified quality control mixture(s) are analyzed tomonitor the performance of the calibrated GC/FTIR system.5. Significance and Use5.1 Test methods to determine oxygenates, benzene, and thearomatic content of gasoline are necessar
21、y to assess productquality and to meet new fuel regulations.5.2 This test method can be used for gasolines that containoxygenates (alcohols and ethers) as additives. It has beendetermined that the common oxygenates found in finishedgasoline do not interfere with the analysis of benzene and otherarom
22、atics by this test method.6. Apparatus6.1 Gas Chromatograph:6.1.1 System equipped with temperature programmable gaschromatograph suitable for cool-on-column injections. Theinjector must allow the introduction of small (for example, 0.1L) sample sizes at the head of the WCOT column or aretention gap.
23、 An autosampler is mandatory.6.1.2 WCOT column containing a methylsilicone stationaryphase which elutes the aromatic hydrocarbons according totheir boiling points.Acolumn containing a relatively thick filmof stationary phase, such as 4 to 5 m, is recommended toprevent column sample overload.6.2 FTIR
24、 Spectrometer:6.2.1 This test method requires a light-pipe GC/FTIR sys-tem (Fig. 1). No data have been acquired with matrix-isolationor other deposition type systems.6.2.2 The spectrometer must be equipped with a mercury-cadmium-telluride (MCT) detector capable of detecting from atleast 4000 cm-1 to
25、 550 cm-1.6.2.3 The lower limit of 550 cm-1 is necessary for theaccurate determination of benzene. Fig. 2 gives an acceptableinfrared spectra of benzene.7. Reagents and Materials7.1 Carrier GasHelium and hydrogen have been usedsuccessfully. The minimum purity of the carrier gas used mustbe 99.85 mol
26、e %. Additional purification using commerciallyavailable scrubbing reagents is recommended to remove traceoxygen which may deteriorate the performance of the GCWCOT column.7.2 Dilution Solventsn-heptane and methylbenzene (tolu-ene) used as a solvent in the preparation of the calibrationmixture. Reag
27、ent grade. All at 99 % or greater purity. Freefrom detectable oxygenates and aromatics which may interferewith the analysis.7.2.1 Toluene should be used as a solvent only for thepreparation of C9+ components and must be free from inter-fering aromatics. (WarningThe gasoline samples and sol-vents use
28、d as reagents such as heptane and toluene areflammable and may be harmful or fatal if ingested or inhaled.Benzene is a known carcinogen. Use with proper ventilation.Safety glasses and gloves are required while preparing samplesand standards.)FIG. 1 Light-Pipe GC/FTIR SystemFIG. 2 Vapor Phase Spectru
29、m of BenzeneD5986 96 (2011)27.3 Internal Standard1,2-dimethoxyethane (DME) ordeuterated compounds, or both, have been used successfully.Asingle internal standard such as DME may be used. If otherinternal standards are used, a narrow selective wavelengthrange must be determined to generate a SWC whic
30、h yields nointerference from other components in the sample.7.4 Liquid Nitrogen, supplied from low pressure dewar.Required for cooling of the MCT detector. Dewar may beconnected through an electronic solenoid to the MCT coolingreservoir for unattended operation. (WarningHelium andhydrogen are suppli
31、ed under high pressure. Hydrogen can beexplosive and requires special handling. Hydrogen monitorsthat automatically shut off supply to the GC in case of seriousleaks are available from GC supply manufacturers.)7.5 Spectrometer Purge Gas,N2dry air has not been tested,but should be adequate.NOTE 1The
32、FTIR spectrometer can be protected by installing appro-priate filters to remove volatile oils or contaminants that may be presentin commercial low quality nitrogen supplies. A liquid nitrogen dewar maybe used as a source for the nitrogen purge.7.6 Standards for Calibration and Identification, all at
33、 99 %or greater purity (Table 1 and Table 2). If reagents of highpurity are not available, an accurate assay of the reagent mustbe performed using a properly calibrated GC or other tech-niques. The concentration of the impurities which overlap theother calibration components must be known and used t
34、ocorrect the concentration of the calibration components. Be-cause of the error that may be introduced from impuritycorrections, the use of only high purity reagents is stronglyrecommended. Standards are used for calibration as well forestablishing the identification by retention time in conjunction
35、with spectral match.8. Sampling8.1 Make every effort to ensure that the sample is represen-tative of the fuel source from which it is taken. Follow therecommendations of Practice D4057 or its equivalent whenobtaining samples from bulk storage or pipelines. Sampling tomeet certain regulatory specific
36、ations may require the use ofspecific sampling procedures. Consult appropriate regulations.8.2 Take appropriate steps to minimize the loss of lighthydrocarbons from the gasoline sample while sampling andduring analyses. Upon receipt in the laboratory chill the samplein its original container to 0 to
37、 5C (32 to 40F) before andafter a sample is obtained for analysis.8.3 After the sample is prepared for analysis with internalstandard(s), chill the sample and transfer to an appropriateautosampler vial with minimal headspace. Re-chill the remain-der of the sample immediately and protect from evapora
38、tion forfurther analyses, if necessary.9. Calibration Procedure9.1 Preparation of Calibration StandardsPrepare multi-component calibration standards using the compounds listed inTable 1 and Table 2 by mass according to Practice D4307.Prepare calibration solutions as described in 9.1-9.1.4 for eachse
39、t.Adjust these concentrations, as necessary, to ensure that theconcentrations of the components in the actual samples arebracketed by the calibration concentrations. Solid componentsare weighed directly into the flask or vial. The specifiedvolumes of each calibration component are weighed into 100mL
40、 volumetric flasks or 100 mL septum capped vials. Preparea calibration standard as follows. Cap and record the tareweight of the 100 mL volumetric flask or vial to 0.1 mg.Remove the cap and carefully add components to the flask orvial starting with the least volatile component. Cap the flaskand reco
41、rd the net mass (Wi) of the aromatic component addedto 0.1 mg. Repeat the addition and weighing procedure for eachcomponent. Similarly add the internal standard and record itsnet mass (Ws) to 0.1 mg. Store the capped calibration standardsin a refrigerator at 0 to 5C (32 to 40F) when not in use.NOTE
42、2Mix all calibration solutions for at least 30 s on a Vortexmixer after preparation or equivalent. Highly precise sample roboticsample preparation systems are available commercially. These systemsmay be used provided that the results for the quality control referencematerial (Section 11) are met whe
43、n prepared in this manner.9.1.1 Ethers and Alcohols:9.1.1.1 Three sets of at least six calibration levels each(eighteen total solutions) are prepared bracketing the 0 to 20volume % range. Set 1: for MTBE, DIPE, ETBE, TAME; SetTABLE 1 GC/FTIR Oxygenates Calibration ComponentsCompound CASMethyl-t-buty
44、l ether (MTBE) 1634-04-4Ethyl-t-butyl ether (ETBE) 637-92-3Methyl-t-amyl ether (TAME) 994-05-8Di-isopropyl ether (DIPE) 108-20-3Methanol 67-56-1Ethanol 64-17-52-Propanol 67-63-0t-Butanol 75-65-01-Propanol 71-23-62-Butanol 15892-23-6Isobutanol 78-83-11-Butanol 71-36-31,2-dimethoxyethane (DME) (Intern
45、al Standard) 110-71-4TABLE 2 GC/FTIR Aromatic Hydrocarbons CalibrationComponents (Calibrated Aromatic Components)Compound CAS No.Benzene 71-43-2Methylbenzene 108-88-3Ethylbenzene 100-41-41,3-Dimethylbenzene 108-38-31,4-Dimethylbenzene 106-42-31,2-Dimethylbenzene 95-47-6(1-Methylethyl)-benzene 98-82-
46、8Propyl-benzene 103-65-11-methyl-3-ethylbenzene 620-14-41-methyl-4-ethylbenzene 622-96-81,3,5-trimethylbenzene 108-67-81-methyl-2-ethylbenzene 611-14-31,2,4-trimethylbenzene 95-63-61,2,3-trimethylbenzene 526-73-8Indan 496-11-71,4-diethylbenzene 105-05-5Butylbenzene 104-51-81,2-Diethylbenzene 135-01-
47、31,2,4,5-Tetramethylbenzene 95-93-21,2,3,5-Tetramethylbenzene 527-53-7Naphthalene 91-20-32-methyl-naphthalene 91-57-61-methyl-naphthalene 90-12-0D5986 96 (2011)32: MeOH, EtOH, 2-PrOH, t-BuOH; and Set 3: 1-PrOH,2-BuOH, i-BuOH, 1-BuOH.9.1.1.2 For each above Set: 1, 3, 5, 10, 15, and 20 mLaliquots of e
48、ach component are pipetted into respective 100 mLvolumetric flasks or vials while accurately recording themasses. For example, for Set 1, into flask one add 1.0 mLMTBE, 1.0 mL DIPE, 1.0 mL ETBE, 1.0 mLTAME; into flasktwo add 3.0 mL MTBE, 3.0 mL DIPE, 3.0 mL ETBE, 3.0 mLTAME; and so forth. Add the ox
49、ygenate in reverse order oftheir boiling points. The above procedure produces six calibra-tion solutions for each set with the concentrations of eachanalyte at 1, 3, 5, 10, 15, and 20 volume %. 10.0 mL of DME(internal standard) is then added at constant volumes to eachflask or vial while recording its mass. The flasks or vials arethen filled to 100 mL total volume with toluene. It is notnecessary to weigh the amount of solvent added since thecalculations are based on the absolute masses of the calibrationcomponents and the internal standard components.
