1、Designation: D5769 10 (Reapproved 2015)D5769 15Standard Test Method forDetermination of Benzene, Toluene, and Total Aromatics inFinished Gasolines by Gas Chromatography/MassSpectrometry1This standard is issued under the fixed designation D5769; the number immediately following the designation indica
2、tes 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. Scope Scope*1.1 This test method covers the determina
3、tion of benzene, toluene, other specified individual aromatic compounds, and totalaromatics in finished motor gasoline, including gasolines containing oxygenated blending components, by gas chromatography/mass spectrometry (GC/MS).1.2 This test method has been tested for the following concentration
4、ranges, in liquid volume percent, for the followingaromatics: benzene, 0.1 % to 4 %; toluene, 1 % to 13 %; and total (C6 to C12) aromatics, 10 % to 42 %. The round-robin studydid not test the method for individual hydrocarbon process streams in a refinery, such as reformates, fluid catalytic cracked
5、naphthas, and so forth, used in the blending of gasolines.1.3 Results are reported to the nearest 0.01 % for benzene and 0.1 % for the other aromatics by liquid volume.1.4 This test method includes a relative bias section for EPA spark-ignition engine fuel benzene regulations reporting based onPract
6、ice D6708 accuracy assessment between Test Method D5769 and Test Method D3606 as a possible Test Method D5769alternative to Test Method D3606. The Practice D6708 derived correlation equation is only applicable for blended fuels in thebenzene concentration range from 0.0 % to 2.50 % by volume as meas
7、ured by Test Method D5769. The applicable Test MethodD3606 range for benzene is from 0.0 % to 2.47 % by volume as reported by Test Method D3606.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not pur
8、port to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to its use.2. Referenced Documents2.1 ASTM Standards:2
9、D1298 Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products byHydrometer MethodD3606 Test Method for Determination of Benzene and Toluene in Finished Motor and Aviation Gasoline by Gas Chromatog-raphyD4052 Test Method for Density, Relative Density
10、, and API Gravity of Liquids by Digital Density MeterD4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsD4307 Practice for Preparation of Liquid Blends for Use as Analytical StandardsD6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test M
11、ethods that Purportto Measure the Same Property of a Material3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 aromaticany hydrocarbon compound containing a benzene or naphthalene ring.1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liqui
12、d Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.04.0M on Mass Spectroscopy.Current edition approved June 1, 2015Dec. 1, 2015. Published July 2015December 2015. Originally approved in 1995. Last previous edition approved in 20102015 asD5769 10.D5769 10 (2015). DOI: 10.1520
13、/D5769-10R15.10.1520/D5769-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM st
14、andard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all ca
15、ses only the current versionof the standard as published by ASTM is to be considered the official document.*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. United States13.1.2 calibrat
16、ed aromatic componentthe individual aromatic components that have a specific calibration.3.1.3 cool on-column injectorin gas chromatography, a direct sample introduction system that is set at a temperature at orbelow the boiling point of solutes or solvent on injection and then heated at a rate equa
17、l to or greater than the column. Normallyused to eliminate boiling point discrimination on injection or to reduce adsorption on glass liners within injectors, or both. Thesample is injected directly into the head of the capillary column tubing.3.1.4 open split interfaceGC/MS interface used to mainta
18、in atmospheric pressure at capillary column outlet and to eliminatemass spectrometer vacuum effects on the capillary column. Can be used to dilute the sample entering the mass spectrometer tomaintain response linearity.3.1.5 reconstructed ion chromatogram (RIC)a limited mass chromatogram representin
19、g the intensities of ion massspectrometric currents for only those ions having particular mass to charge ratios. Used in this test method to selectively extractor identify aromatic components in the presence of a complex hydrocarbon matrix, such as gasoline.3.1.6 retention gapin gas chromatography,
20、refers to a deactivated precolumn which acts as a zone of low retention power forreconcentrating bands in space. The polarity of the precolumn must be similar to that of the analytical column.3.1.7 split ratioin capillary gas chromatography, the ratio of the total flow of carrier gas to the sample i
21、nlet versus the flowof the carrier gas to the capillary column, expressed by:split ratio5S1C!/C (1)where:S = flow rate at the splitter vent, andC = flow rate at the column outlet.3.1.8 total ion chromatogram (TIC)mass spectrometer computer output representing either the summed intensities of allscan
22、ned ion currents or a sample of the current in the ion beam for each spectrum scan plotted against the corresponding spectrumnumber. Generally, it can be correlated with a flame ionization detector chromatogram.3.1.9 uncalibrated aromatic componentindividual aromatics for which a calibration is not
23、available. These components areestimated from the calibration of several calibrated aromatic components.3.1.10 wall coated open tubular (WCOT)a type of capillary 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
24、gas chromatograph equipped with a dimethylpolysiloxane WCOT column is interfaced to a fast scanning massspectrometer that is suitable for capillary column GC/MS analyses. The sample is injected either through a capillary splitter portor a cool-on-column injector capable of introducing a small sample
25、 size without overloading the column. The capillary columnis interfaced directly to the mass spectrometer or by way of an open split interface or other appropriate device.4.2 Calibration is performed on a mass basis, using mixtures of specified pure aromatic hydrocarbons. Volume percent data iscalcu
26、lated from the densities of the individual components and the density of the sample. A multipoint calibration consisting ofat least five levels and bracketing the expected concentrations of the specified individual aromatics is required. Specified deuteratedhydrocarbons are used as the internal stan
27、dards, for example, d6-benzene for quantitating benzene. Unidentified aromatichydrocarbons present that have not been specifically calibrated for are quantitated using the calibration of an adjacent calibratedcompound and summed with the other aromatic components to obtain a total aromatic concentra
28、tion of the sample.4.3 Specified quality control mixture(s), such as synthetic quality control mixtures must be analyzed to monitor the performanceof the calibrated GC/MS system. Analysis of a gasoline as a reference material is strongly recommended.5. Significance and Use5.1 Test methods to determi
29、ne benzene and the aromatic content of gasoline are necessary to assess product quality and to meetfuel regulations.5.2 This test method can be used for gasolines that contain oxygenates (alcohols and ethers) as additives. It has been determinedthat the common oxygenates found in finished gasoline d
30、o not interfere with the analysis of benzene and other aromatics by thistest method.6. Apparatus6.1 Gas Chromatography:6.1.1 System equipped with temperature-programmable gas chromatograph suitable for split injections with WCOT column orcool-on-column injector that allows the injection of small (fo
31、r example, 0.1 L) samples at the head of the WCOT column or aretention gap. An autosampler is mandatory for the on-column injections.D5769 1526.1.2 WCOTcolumn containing dimethylpolysiloxane bonded stationary phase, meeting the specification in the following table.For on-column injections, a column
32、containing a thicker film of stationary phase, such as 45 m, is recommended to preventcolumn sample overload.Resolution R between 1,3,5-trimethylbenzene and 1-methyl-2-ethylbenzene at the 3 mass % leveleach must be equal to or greater than2.0R5 2st12t2d1.699sy21y1dt2 = retention time of 1,3,5-trimet
33、hylbenzenet1 = retention time of1-methyl-2-ethylbenzeney2 = peak width at half heightof 1,3,5-trimethylbenzeney1 = peak width at half height1-methyl-2-ethyl benzene6.2 Mass Spectrometry:6.2.1 Mass spectrometer capable of producing electron impact spectra at 70, or higher, electron volts or equivalen
34、t, and capableof scanning the range of the specified quantitation masses or m/e. The mass scan range shall cover the masses of interest forquantitation and should yield at least 5 scans across the peak width at half peak width for a 1 to 3 mass percent toluene and coverthe masses of interest for qua
35、ntitation. A scan range of 41 to 200 daltons is adequate.6.2.2 The mass spectrometer must be capable of being interfaced to a gas chromatograph and WCOT columns. The interfacemust be at a high enough temperature to prevent condensation of components boiling up to 220 C, usually 20 C above the finalc
36、olumn temperature is adequate. Direct column interface to the mass spectrometer can be used. An open split interface withcomputer controlled programmable flow controller(s) can also be used, particularly with cool on-column injections, to maintainall aromatic components within the linearity of the m
37、ass spectrometer and at the same time maintain detectability of lowerconcentration aromatic components. For example, a higher open-split-interface make-up gas flow can be used for the highconcentration components, such as toluene and xylenes, and a lower make-up gas flow rate may be used during the
38、elution of thelower concentration benzene and C9+ components. Other interfaces may be used provided the criteria specified in Sections 9 and10 are met.6.2.3 Acomputer system shall be interfaced to the mass spectrometer to allow acquisition of continuous mass scans or total ionchromatogram (TIC) for
39、the duration of the chromatographic program and be able to analyze repeatedly 0.01 mass percent1,4-diethylbenzene with the specified signal/noise ratio of 5. Software must be available to allow searching any GC/MS run forspecific ions or reconstructed ions and plotting the intensity of the ions with
40、 respect to time or scan number. The ability to integratethe area under a specific ion plot peak is essential for quantitation. The quantitation software must allow linear least squares orquadratic nonlinear regression and quantitation with multiple internal standards. It is also recommended that so
41、ftware be availableto automatically perform the identification of aromatic components as specified in 13.1.1.7. Reagents and Materials7.1 Carrier GasHelium and hydrogen have been used successfully. The recommended minimum purity of the carrier gas usedis 99.999 mol percent. Additional purification u
42、sing commercially available scrubbing reagents may be necessary to remove traceoxygen, which may deteriorate the performance of the GC WCOT. (WarningHelium and hydrogen are supplied under highpressure. Hydrogen can be explosive and requires special handling. Hydrogen monitors that automatically shut
43、 off supply to theGC in case of serious leaks are available from GC supply manufacturers.)7.2 Dilution SolventsReagent grade 2,2,4-trimethylpentane (iso-octane), n-heptane, n-nonane, cyclohexane, or toluene, or acombination thereof, used as a solvent in the preparation of the calibration mixtures. (
44、WarningThe gasoline samples andsolvents used as reagents such as iso-octane, cyclohexane, n-heptane, n-octane, and toluene, are flammable and may be harmfulor fatal if ingested or inhaled. Benzene is a known carcinogen. Use with proper ventilation. Safety glasses and gloves are requiredwhile prepari
45、ng samples and standards. Samples should be kept in well ventilated laboratory areas.)NOTE 1Toluene should be used as a solvent only for the preparation of C9+ components and shall be free from interfering aromatics.7.3 Internal StandardsDeuterated analogs of benzene, ethylbenzene, and naphthalene,
46、as specified in Table 1, shall be usedas internal standards because of their similar chromatographic characteristics as the components analyzed. The use of a fourthinternal standard toluene-d8 is recommended. Deuterated naphthalene is hygroscopic and should be stored away from highhumidity.7.4 Stand
47、ards for Calibration and IdentificationAromatic hydrocarbons used to prepare standards should be 99 % or greaterpurity (see Table 1). If reagents of high purity are not available, an accurate assay of the reagent shall be performed using a properlycalibrated GC or other techniques. The concentration
48、 of the impurities that overlap the other calibration components shall beknown and used to correct the concentration of the calibration components. The use of only high purity reagents is stronglyrecommended because of the error that may be introduced from impurity corrections. Standards are used fo
49、r calibration as wellD5769 153as for establishing the identification by retention time in conjunction with mass spectral match (see 13.1.1). Naphthalene ishygroscopic and should be stored away from high humidity.8. Sampling8.1 Every effort should be made to ensure that the sample is representative of the fuel source from which it is taken. Followthe recommendations of Practice D4057, or its equivalent, when obtaining samples from bulk storage or pipelines. Sampling tomeet certain regulatory specifications may require the use of specific sampling procedur
