1、Designation: D 6277 07An American National StandardStandard Test Method forDetermination of Benzene in Spark-Ignition Engine FuelsUsing Mid Infrared Spectroscopy1This standard is issued under the fixed designation D 6277; the number immediately following the designation indicates the year oforiginal
2、 adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of the per-centage of b
3、enzene in spark-ignition engine fuels. It is appli-cable to concentrations from 0.1 to 5 volume %.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if an
4、y, associated with its use. It is theresponsibility of the user of this standard 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:2D 1298 Test Method for Density, Relative Density (
5、SpecificGravity), or API Gravity of Crude Petroleum and LiquidPetroleum Products by Hydrometer MethodD 4052 Test Method for Density and Relative Density ofLiquids by Digital Density MeterD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4177 Practice for Automatic Sampling of P
6、etroleum andPetroleum ProductsD 4307 Practice for Preparation of Liquid Blends for Use asAnalytical StandardsD 5769 Test Method for Determination of Benzene, Tolu-ene, and Total Aromatics in Finished Gasolines by GasChromatography/Mass SpectrometryD 5842 Practice for Sampling and Handling of Fuels f
7、orVolatility MeasurementD 5854 Practice for Mixing and Handling of LiquidSamples of Petroleum and Petroleum ProductsE 168 Practices for General Techniques of Infrared Quanti-tative AnalysisE 1655 Practices for Infrared Multivariate QuantitativeAnalysisE 2056 Practice for Qualifying Spectrometers and
8、 Spectro-photometers for Use in Multivariate Analyses, CalibratedUsing Surrogate Mixtures3. Terminology3.1 Definitions:3.1.1 multivariate calibrationa process for creating acalibration model in which multivariate mathematics is appliedto correlate the absorbances measured for a set of calibrationsam
9、ples to reference component concentrations or propertyvalues for the set of samples.3.1.1.1 DiscussionThe resultant multivariate calibrationmodel is applied to the analysis of spectra of unknown samplesto provide an estimate of the component concentration orproperty values for the unknown sample.3.1
10、.1.2 DiscussionIncluded in the multivariate calibrationalgorithms are Partial Least Squares, Multilinear Regression,and Classical Least Squares Peak Fitting.3.1.2 oxygenatean oxygen-containing organic compoundwhich may be used as a fuel or fuel supplement, for example,various alcohols and ethers.4.
11、Summary of Test Method4.1 Asample of spark-ignition engine fuel is introduced intoa liquid sample cell.Abeam of infrared light is imaged throughthe sample onto a detector, and the detector response isdetermined. Wavelengths of the spectrum, that correlate highlywith benzene or interferences, are sel
12、ected for analysis usingselective bandpass filters or by mathematically selecting areasof the whole spectrum. A multivariate mathematical analysisconverts the detector response for the selected areas of thespectrum of an unknown to a concentration of benzene.5. Significance and Use5.1 Benzene is a c
13、ompound that endangers health, and theconcentration is limited by environmental protection agenciesto produce a less toxic gasoline.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04.0F on Absor
14、ption Spectroscopic Methods.Current edition approved Nov. 1, 2007. Published December 2007. Originallyapproved in 1998. Last previous edition approved in 2006 as D 627701(2006).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. F
15、or 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 Box C700, West Conshohocken, PA 19428-2959, United States.5.2
16、 This test method is fast, simple to run, and inexpensive.5.3 This test method is applicable for quality control in theproduction and distribution of spark-ignition engine fuels.6. Interferences6.1 The primary spectral interferences are toluene and othermonosubstituted aromatics. In addition, oxygen
17、ates can inter-fere with measurements made with filter apparatus. Properchoice of the apparatus, proper design of a calibration matrix,and proper utilization of multivariate calibration techniquescan minimize these interferences.7. Apparatus7.1 Mid-IR Spectrometric Analyzer (of one of the followingt
18、ypes):7.1.1 Filter-based Mid-IR Test ApparatusThe type ofapparatus suitable for use in this test method minimallyemployes an IR source, an infrared transmission cell or a liquidattenuated total internal reflection cell, wavelength discrimi-nating filters, a chopper wheel, a detector, an A-D converte
19、r, amicroprocessor, and a method to introduce the sample. Thefrequencies and bandwidths of the filters are specified in Table1.7.1.2 Fourier Transform Mid-IR SpectrometerThe type ofapparatus suitable for use in this test method employs an IRsource, an infrared transmission cell or a liquid attenuate
20、d totalinternal reflection cell, a scanning interferometer, a detector, anA-D converter, a microprocessor, and a method to introducethe sample. The following performance specifications (throughthe ATR cell) must be met:scan range 4000 to 600 cm1resolution 4 cm1S/N at 674 cm1300:1 RMSThe signal to no
21、ise level will be established by taking asingle beam spectrum using air or nitrogen as the reference anddeclaring that spectrum as the background. The backgroundsingle beam spectrum obtained can be the average of multipleFTIR scans, but the total collection time shall not exceed 60 s.If interference
22、 from water vapor or carbon dioxide is aproblem, the instrument shall be purged with dry air ornitrogen. A subsequent single beam spectrum shall be takenunder the same conditions and ratioed to the backgroundspectrum. The RMS noise of the ratioed spectra, the 100 %line, shall not exceed 0.3 % transm
23、ittance in the region from700 to 664 cm1.7.2 Absorption Cell The absorption cell can be eithertransmission or attenuated total reflectance.7.2.1 Transmission Cells, shall have windows of potassiumbromide, zinc selenide, or other material having a significanttransmission from 712 cm1to 660 cm1. The c
24、ell path lengthof the transmission cell shall be 0.025 (6 0.005) mm. The useof a wedged transmission cell with the same nominal pathlength is acceptable.7.2.2 Attenuated Total Reflectance (ATR) Cells, shall havethe following specifications:ATR element material ZnSebeam condensing optics conical, non
25、-focussing opticsintegral to cell bodyelement configuration circular cross section withcoaxial conical endscone half angle 60element length 1.55 in.element diameter 0.125 in.angle of incidence atsample interface 53.8maximum range ofincidence angles 6 1.5standard absorbance(1428 cm1 band of acetone)
26、0.38 6 0.02 AUmaterial of construction 316 stainless steelseals Chemraz or Kalraz o-rings8. Reagents and Materials (see Note 1)8.1 Standards for Calibration, Qualification, and QualityControl Check StandardsUse of chemicals of at least 99 %purity, where available, for quality control checks is requi
27、redwhen preparing samples. (WarningThese materials areflammable and may be harmful if ingested or inhaled.)8.1.1 tert-Amyl methyl ether, TAME 994-05-8.8.1.2 Benzene 1076-43-3.8.1.3 tert-Butyl ethyl ether, ETBE 637-92-3.8.1.4 tert-Butyl methyl ether, MTBE 1634-04-4.8.1.5 1,3 Dimethylbenzene (m-xylene
28、).8.1.6 Ethanol 64-17-5.8.1.7 Ethylbenzene 100-41-4.8.1.8 3Ethyltoluene 620-14-4.8.1.9 Heavy aromatic/reformate petroleum stream (highboiling cut: IPB of 150 6 5 C and EPof 245 6 8 C) certifiedto contain less than 0.025 % benzene (an absorbance of lessthan 0.03 at 675 cm1using a 0.2 mm cell and a ba
29、selinebetween approximately 680 cm1and 670 cm1) 64741-68-0.8.1.10 Hexane (an absorbance versus water of less than 0.1at 250 nm usinga1cmcell) 110-54-3.8.1.11 2,2,4-Trimethylpentane (isooctane) 540-84-1.8.1.12 Pentane (an absorbance versus water of less than 0.1at 250 nm usinga1cmcell) 109-66-0.8.1.1
30、3 Propylbenzene 103-65-1.8.1.14 Toluene 108-88-3.8.1.15 1,3,5-Trimethylbenzene (mesitylene) 108-67-8.8.1.16 m-Xylene 108-38-3.NOTE 1Only some of the reagents are required in each calibration orqualification procedure.9. Sampling and Sample Handling9.1 General Requirements:9.1.1 The sensitivity of th
31、e measurement of benzene to theloss of benzene or other components through evaporation andthe resulting changes in composition is such that the utmostTABLE 1 Specification for Filters Used in Filter-based Mid-IRTestCenter Wavenumber Bandwidth (in wavelength units)(6 0.15 % of wavenumber) (full width
32、 at half height)673 cm-11%oflc729 cm-11%oflc769 cm-11%oflc1205 cm-11%oflc1054 cm-11%oflc1188 cm-11%oflc1117 cm-11%oflcD6277072precaution and the most meticulous care in the drawing andhandling of samples is required.9.1.2 Fuel samples to be analyzed by the test method shallbe sampled using procedure
33、s outlined in Practices D 4057,D 4177,orD 5842, where appropriate. Do not use the “Sam-pling by Water Displacement.” With some alcohol containingsamples, the alcohol will dissolve in the water phase.9.1.3 Protect samples from excessive temperatures prior totesting. This can be accomplished by storag
34、e in an appropriateice bath or refrigerator at 0 to 5C.9.1.4 Do not test samples stored in leaky containers. Discardand obtain a new sample if leaks are detected.9.2 Sample Handling During Analysis:9.2.1 When analyzing samples by the mid infrared appara-tus, the sample must be between a temperature
35、of 15 to 38 C.Equilibrate all samples to the temperature of the laboratory (15to 38C) prior to analysis by this test method.9.2.2 After analysis, if the sample is to be saved, reseal thecontainer and store the sample in an ice bath or a refrigeratorat 0 to 5C.10. Calibration and Qualification of the
36、 Apparatus10.1 Before use, the instrument must be calibrated accord-ing to the procedure described in Annex A1. This calibrationcan be performed by the instrument manufacturer prior todelivery of the instrument to the end user. If, after maintenance,the instrument calibration is repeated, the qualif
37、ication proce-dure must also be repeated.10.2 Before use, the instrument must be qualified accordingto the procedure described inAnnexA1. The qualification needonly be carried out when the instrument is initially put intooperation, recalibrated, or repaired.11. Quality Control Checks11.1 Confirm the
38、 calibration of the instrument each day it isused by measuring the benzene concentration using the proce-dure outlined in Section 12 on at least one quality controlsample of known benzene content. The preparation of knownbenzene concentration is described in 11.1.1 and 11.1.2.11.1.1 Standard(s) of k
39、nown benzene concentration shall bemade up by mass according to A1.1 and converted to volume% using the measured density as outlined in Section 13.Atleast one standard shall be made up at 1.2 (6 0.2) mass %benzene, that is, nominally 1.0 volume %.Additional standardsmay also be prepared and used for
40、 quality control checks.11.1.2 Standard(s) should be prepared in sufficient volumeto allow for a minimum of 30 quality control measurements tobe made on one batch of material. Package or store, or both,quality control samples to ensure that all analyses of qualitycontrol samples from a given lot are
41、 performed on essentiallyidentical material.11.2 If the benzene volume % value estimated for thequality control sample prepared at 1.2 mass % benzene differsfrom the known value by more than 0.12 volume %, then themeasurement system is out-of-control and cannot be used toestimate benzene concentrati
42、ons until the cause of the out-of-control behavior is identified and corrected.11.3 If correction of out-of-control behavior requires repairto the instrument or recalibration of the instrument, thequalification of instrument performance described inA1.3 shallbe performed before the system is used to
43、 measure benzenecontent on samples.12. Procedure12.1 Equilibrate the samples to between 15 and 38C beforeanalysis.12.2 Clean the sample cell. If a separate baseline using theempty cell is required, and if residual fuel is in the sample cell,remove the fuel by flushing the cell and inlet-outlet lines
44、 withenough pentane to ensure complete washing. Evaporate theresidual pentane with either dry air or nitrogen.12.3 If needed, obtain a baseline spectrum in the mannerestablished by the manufacturer of the equipment.12.4 Prior to the analysis of unknown test samples, establishthat the equipment is ru
45、nning properly by collecting thespectrum of the quality control standard(s), by analyzing thespectrum with the calibration model, and by comparing theestimated benzene concentration to the known value for the QCstandard(s). Introduce enough standard to the cell to ensure thatthe cell is washed a min
46、imum of three times with the standardsolution.12.5 Introduce the unknown fuel sample in the mannerestablished by the manufacturer. Introduce enough of the fuelsample to the cell to ensure the cell is washed a minimum ofthree times with the fuel.12.6 Obtain the spectral response of the fuel sample.12
47、.6.1 If a filter based mid IR instrument is used, acquire theabsorbance for the fuel sample at the wavelengths correspond-ing to the specified filters.12.6.2 If an FTIR is used, acquire the digitized spectral datafor the fuel sample over the frequency region from 4000 cm1to 600 cm1.12.7 Determine th
48、e benzene concentration (volume %) ac-cording to the appropriate calibration equation developed inAnnex A1.12.7.1 For filter based mid IR instruments, apply the cali-bration equation determined in A1.2.4 to convert the absor-bances at each of the wavelengths to the benzene concentrationexpressed in
49、volume %.12.7.2 For FTIR instruments using a PLS calibration, deter-mine the benzene concentration using the calibration modelsdeveloped inA1.2.5 by following the steps outlined as follows.12.7.2.1 Baseline correct the spectrum using a linear base-line fit to absorbances measured between 712 and 658 cm1.12.7.2.2 Estimate the benzene concentration in the fuelsample by applying the low calibration (see A1.2.5.1)tothebaseline corrected spectrum in the region of 712 to 664 cm1.12.7.2.3 If the estimated benzene concentration (
