1、Designation: D5986 96 (Reapproved 2015)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: 0.1 volume % to 20 volume % per component forethers and a
5、lcohols; 0.1 volume % to 2 volume % benzene;1 volume % to 15 volume % for toluene, 10 volume % to40 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 blen
6、ding ofgasolines.1.4 The values stated in SI units 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
7、to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1298 Test Method for Density, Relative Density, or APIGravity of Crude Petroleum and Liquid Petroleum Prod-ucts by Hydrometer Meth
8、odD4052 Test Method for Density, Relative 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 T
9、his Standard:3.1.1 aromaticsrefers 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
10、introduction system which is set at 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 withini
11、njectors. The sample is injected directly 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 ga
12、pin gas chromatography, refers to 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
13、 chromatogram obtained bysumming the 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 is1
14、This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility ofSubcommittee D02.04.0L on Gas Chromatography Methods.Current edition approved Oct. 15, 2015. Published December 2015. Originallyapproved in 1996. Last
15、 previous edition approved in 2011 as D5986 96 (2011).DOI: 10.1520/D5986-96R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page o
16、nthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1not available and whose concentrations are estimated from theresponse factor of a calibrated aromatic component.3.1.8 wall coated open tubular (WCOT)a type of capillary
17、column prepared by coating or bonding the inside wall of thecapillary 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-co
18、lumninjector capable of injecting a small sample size 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 sa
19、mple. Multipointcalibrations consisting of at least 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-tetramethylb
20、enzene and summedwith the other calibrated aromatic 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, benze
21、ne, and thearomatic content of gasoline are necessary 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
22、interfere with the analysis of benzene and otheraromatics 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,0.1 L) sample siz
23、es at the head of the WCOT column or aretention gap. 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 m to 5 m, is
24、 recommended toprevent column sample overload.6.2 FTIR 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) d
25、etector capable of detecting from atleast 4000 cm-1 to 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 m
26、inimum purity of the carrier gas used mustbe 99.85 mole %. 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 solv
27、ent in the preparation of the calibrationmixture. Reagent 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 aro
28、matics. (WarningThe gasoline samples and sol-vents used as reagents such as heptane and toluene areFIG. 1 Light-Pipe GC/FTIR SystemFIG. 2 Vapor Phase Spectrum of BenzeneD5986 96 (2015)2flammable and may be harmful or fatal if ingested or inhaled.Benzene is a known carcinogen. Use with proper ventila
29、tion.Safety glasses and gloves are required while preparing samplesand standards.)7.3 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 wav
30、elengthrange must be determined to generate a SWC which 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 unatt
31、ended operation. (WarningHelium andhydrogen are supplied 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 ai
32、r has not been tested,but should be adequate.NOTE 1The 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
33、.6 Standards for Calibration and Identification, all at 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 t
34、heother calibration components must be known and used tocorrect 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 forestablish
35、ing the identification by retention time in conjunctionwith 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
36、 pipelines. Sampling tomeet certain regulatory specifications 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 labor
37、atory chill the samplein its original container to 0 C to 5 C (32 F to 40 F) beforeand after 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
38、remain-der of the sample immediately and protect from evaporation 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.Prepa
39、re calibration solutions as described in 9.1 9.1.4 foreach set. Adjust these concentrations, as necessary, to ensurethat the concentrations of the components in the actual samplesare bracketed by the calibration concentrations. Solid compo-nents are weighed directly into the flask or vial. The speci
40、fiedvolumes of each calibration component are weighed into100 mL volumetric flasks or 100 mL septum capped vials.Prepare a calibration standard as follows. Cap and record thetare weight of the 100 mL volumetric flask or vial to 0.1 mg.Remove the cap and carefully add components to the flask orvial s
41、tarting with the least volatile component. Cap the flaskand record the net mass (Wi) of the aromatic component addedto 0.1 mg. Repeat the addition and weighing procedure foreach component. Similarly add the internal standard and recordits net mass (Ws) to 0.1 mg. Store the capped calibrationstandard
42、s in a refrigerator at 0 C to 5 C (32 F to 40 F) whennot in use.NOTE 2Mix all calibration solutions for at least 30 s on a Vortex mixerTABLE 1 GC/FTIR Oxygenates Calibration ComponentsCompound CASMethyl-t-butyl ether (MTBE) 1634-04-4Ethyl-t-butyl ether (ETBE) 637-92-3Methyl-t-amyl ether (TAME) 994-0
43、5-8Di-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) (Internal Standard) 110-71-4TABLE 2 GC/FTIR Aromatic Hydrocarbons CalibrationComponents (Calibrate
44、d 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 98-82-8Propyl-benzene 103-65-11-methyl-3-ethylbenzene 620-14-41-methyl-4-ethylbenzene 622-96-81,3
45、,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 135-01-31,2,4,5-Tetramethylbenzene 95-93-21,2,3,5-Tetramethylbenzene 527-53-7Naphthalene 91-20-32-
46、methyl-naphthalene 91-57-61-methyl-naphthalene 90-12-0D5986 96 (2015)3after preparation or equivalent. Highly precise sample robotic samplepreparation systems are available commercially. These systems may beused provided that the results for the quality control reference material(Section 11) are met
47、 when 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 volume% to 20 volume % range. Set 1: for MTBE, DIPE, ETBE,TAME; Set 2: MeOH, EtOH, 2-PrOH, t-BuOH; and Set 3:1-PrOH, 2-BuOH, i-Bu
48、OH, 1-BuOH.9.1.1.2 For each above Set: 1 mL, 3 mL, 5 mL, 10 mL,15 mL, and 20 mLaliquots of each component are pipetted intorespective 100 mL volumetric flasks or vials while accuratelyrecording the masses. For example, for Set 1, into flask one add1.0 mL MTBE, 1.0 mL DIPE, 1.0 mL ETBE, 1.0 mL TAME;i
49、nto flask two add 3.0 mLMTBE, 3.0 mLDIPE, 3.0 mLETBE,3.0 mL TAME; and so forth. Add the oxygenate in reverseorder of their boiling points. The above procedure produces sixcalibration solutions for each set with the concentrations ofeach analyte at 1 volume %, 3 volume %, 5 volume %,10 volume %, 15 volume %, and 20 volume %. 10.0 mL ofDME (internal standard) is then added at constant volumes toeach flask or vial while recording its mass. The flasks or vialsare then filled to 100 mL total volume with toluene. It is notnecessary to weigh the amount of
