1、Designation: D 7039 07An American National StandardStandard Test Method forSulfur in Gasoline and Diesel Fuel by MonochromaticWavelength Dispersive X-ray Fluorescence Spectrometry1This standard is issued under the fixed designation D 7039; the number immediately following the designation indicates t
2、he 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of to
3、tal sulfurby monochromatic, wavelength-dispersive X-ray fluorescence(MWDXRF) spectrometry in single-phase gasolines, dieselfuels, and refinery process streams used to blend gasoline anddiesel, at concentrations from 2 mg/kg to 500 mg/kg. Theprecision of this test method was determined by an interlab
4、o-ratory study using representative samples of the liquids de-scribed in 1.1 and 1.2. The pooled limit of quantitation (PLOQ)was estimated to be 4 mg/kg.NOTE 1Volatile samples such as high-vapor-pressure gasolines orlight hydrocarbons might not meet the stated precision because of theevaporation of
5、light components during the analysis.1.2 Gasoline samples containing oxygenates may be ana-lyzed with this test method provided the matrix of thecalibration standards is either matched to the sample matricesor the matrix correction described inAnnexA1 is applied to theresults. The conditions for mat
6、rix matching and matrix correc-tion are provided in the Interferences section (Section 5).1.3 Gasolines and diesels with sulfur contents above 500mg/kg can be analyzed after dilution with appropriate solvent(see 5.2). The precision and bias of sulfur determinations ondiluted samples has not been det
7、ermined and may not be thesame as shown for neat samples (Section 15).1.4 When the elemental composition of the samples differsignificantly from the calibration standards used to prepare thecalibration curve, the cautions and recommendation in Section5 should be carefully observed.1.5 The values sta
8、ted in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.6 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 a
9、nd health practices and determine the applica-bility of regulatory limitations prior to use. For specific hazardinformation, see 3.1.2. Referenced Documents2.1 ASTM Standards:2D 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4177 Practice for Automatic Sampling of Petroleum an
10、dPetroleum ProductsD 6299 Practice for Applying Statistical Quality AssuranceTechniques to Evaluate Analytical Measurement SystemPerformanceD 6300 Practice for Determination of Precision and BiasData for Use in Test Methods for Petroleum Products andLubricants2.2 EPA Documents:340 CFR 80.584 Code of
11、 Federal Regulations; Title 40; Part80; U.S. Environmental Agency, July 1, 20053. Summary of Test Method3.1 A monochromatic X-ray beam with a wavelength suit-able to excite the K-shell electrons of sulfur is focused onto atest specimen contained in a sample cell (see Fig. 1). Thefluorescent Ka radia
12、tion at 0.5373 nm (5.373 ) emitted bysulfur is collected by a fixed monochromator (analyzer). Theintensity (counts per second) of the sulfur X rays is measuredusing a suitable detector and converted to the concentration ofsulfur (mg/kg) in a test specimen using a calibration equation.Excitation by m
13、onochromatic X rays reduces background,simplifies matrix correction, and increases the signal/background ratio compared to polychromatic excitation used inconventional WDXRF techniques.4(WarningExposure toexcessive quantities of X-ray radiation is injurious to health.The operator needs to take appro
14、priate actions to avoidexposing any part of his/her body, not only to primary X rays,but also to secondary or scattered radiation that might be1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.03
15、on Elemental Analysis.Current edition approved May 1, 2007. Published June 2007. Originallyapproved in 2004. Last previous edition approved in 2004 as D 703904.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of
16、 ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from U.S. Government Printing Office, 732 N. Capitol Street, NW,Washington, DC 20401.4Bertin, E. P., Principles and Practices of X-ray Spectrometric Analysis , PlenumPress, New York, 1975, p
17、p. 115-118.1*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.present. The X-ray spectrometer should be operated in accor-dance with the regulations governing the use of
18、ionizingradiation.)4. Significance and Use4.1 This test method provides for the precise measurementof the total sulfur content of gasolines and diesels with minimalsample preparation and analyst involvement. The typical timefor each analysis is two to three minutes.4.2 Knowledge of the sulfur conten
19、t of diesel fuels, gaso-lines, and refinery process streams used to blend gasolines isimportant for process control as well as the prediction andcontrol of operational problems such as unit corrosion andcatalyst poisoning, and in the blending of products to com-modity specifications.4.3 Various fede
20、ral, state, and local agencies regulate thesulfur content of some petroleum products, including gasolineand diesel fuel. Unbiased and precise determination of sulfur inthese products is critical to compliance with regulatory stan-dards.5. Interferences5.1 Differences between the elemental compositio
21、n of testsamples and the calibration standards can result in biased sulfurdeterminations. For diesels and gasolines within the scope ofthis test method, the only important elements contributing tobias resulting from differences in the matrices of calibrants andtest samples are hydrogen, carbon, and
22、oxygen. A matrix-correction factor (C) can be used to correct this bias; thecalculation is described in Annex A1. For general analyticalpurposes, the matrices of test samples and the calibrants areconsidered to be matched when the calculated correction factorC is within 0.98 to 1.04. No matrix corre
23、ction is requiredwithin this range. Samples used in the 2002 interlaboratorystudy fall within this category. A matrix correction is requiredwhen the value of C is outside the range of 0.98 to 1.04. Formost testing, matrix correction can be avoided with a properchoice of calibrants. For example, base
24、d on the example graphin Annex A1 (Fig. 2), a calibrant with 86 mass % carbon and14 mass % hydrogen can cover non-oxygen containing sampleswith C/H ratios from 5.4 to 8.5. For gasolines with oxygenates,up to 2.3 mass % oxygen (12 mass % MTBE) can be toleratedfor test samples with the same C/H ratio
25、as the calibrants.5.2 To minimize any bias in the results, use calibrationstandards prepared from sulfur-free base materials of the sameor similar elemental composition as the test samples. Whendiluting samples, use a diluent with an elemental compositionthe same or similar to the base material used
26、 for preparing thecalibration standards.5.2.1 A base material for gasoline can be approximatelysimulated by mixing 2,2,4-trimethylpentane (isooctane) andtoluene in a ratio that approximates the expected aromaticcontent of the samples to be analyzed.5.2.2 Fuels containing oxygenates may be analyzed u
27、singcalibration standards containing the same amount of the sameoxygenate in the test fuel.6. Apparatus6.1 Monochromatic Wavelength Dispersive X-ray Fluores-cence (MWDXRF) Spectrometer5, equipped for X-ray detec-tion at 0.5373 nm (5.373). Any spectrometer of this type canbe used if it includes the f
28、ollowing features, and the precisionand bias of test results are in accordance with the valuesdescribed in Section 15.6.1.1 X-ray Source, capable of producing X rays to excitesulfur. X-ray tubes with a power 25W capable of producingRh La,PdLa,AgLa,TiKa,ScKa, and Cr Ka radiation arerecommended for th
29、is purpose.6.1.2 Incident-beam Monochromator, capable of focusingand selecting a single wavelength of characteristic X rays fromthe source onto the specimen.5The sole source of this apparatus known to the committee at this time is X-rayOptical Systems, Inc., 15 Tech Valley Drive, East Greenbush, NY
30、12061. If you areaware of alternative suppliers, please provide this information to ASTM Interna-tional Headquarters. Your comments will receive careful consideration at a meetingof the responsible technical committee, which you may attend.FIG. 1 Schematic of the MWDXRF AnalyzerD70390726.1.3 Optical
31、 Path, designed to minimize the absorptionalong the path of the excitation and fluorescent beams using avacuum or a helium atmosphere. A vacuum of 2.7 kPa (20Torr) is recommended. The calibration and test measurementsmust be done with identical optical paths, including vacuum orhelium pressure.6.1.4
32、 Fixed-channel Monochromator, suitable for dispers-ing sulfur Ka X rays.6.1.5 Detector, designed for efficient detection of sulfur KaX rays.6.1.6 Single-Channel Analyzer, an energy discriminator tomonitor only sulfur radiation.6.1.7 Removable Sample Cell, an open-ended specimenholder compatible with
33、 the geometry of the MWDXRF spec-trometer and designed to use replaceable X-ray transparent film(see 6.1.8) to hold a liquid specimen with a minimum depth of5mm. The sample cell must not leak when fitted with X-raytransparent film. A disposable cell is recommended.6.1.8 X-Ray Transparent Film, for c
34、ontaining and support-ing the test specimen in the sample cell (see 6.1.7) whileproviding a low-absorption window for X rays to pass to andfrom the sample. Any film resistant to chemical attack by thesample, free of sulfur, and X-ray transparent can be used, forexample, polyester, polypropylene, pol
35、ycarbonate, and poly-imide. However, samples of high aromatic content can dissolvepolyester and polycarbonate films.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specificati
36、ons of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.6Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7.2 Calibr
37、ation-Check Samples, for verifying the accuracyof a calibration. The check samples shall have known sulfurcontent and not be used in determining the calibration curve. Astandard from the same reliable and consistent source ofcalibration standards used to determine the calibration curve isconvenient
38、to check the calibration.7.3 Di-n-butyl Sulfide, a high-purity liquid with a certifiedsulfur concentration. Use the certified sulfur concentrationwhen calculating the exact concentrations of sulfur in calibra-tion standards.7.4 Drift-Monitor Sample (Optional), to determine andcorrect instrument drif
39、t over time (see 10.4, 11.1, and 12.1).Various forms of stable sulfur-containing materials are suitabledrift-correction samples, for example, liquid petroleum, solid,pressed powder, metal alloy, and fused glass. The count ratedisplayed by the monitor sample, in combination with aconvenient count tim
40、e (T), shall be sufficient to give a relativestandard deviation (RSD) of1%(see Appendix X1).NOTE 2Calibration standards may be used as drift-monitor samples.6Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, D.C. For suggestions on the testing of reag
41、ents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.FIG. 2 Matrix Correction for a Test Sample vs. C/H and Tot
42、al Oxygen Content Using Chromium Ka for the Excitation BeamD7039073Because it is desirable to discard test specimens after each determination,a lower cost material is suggested for daily use.Any stable material can beused for daily monitoring of drift.NOTE 3The effect of drift correction on the prec
43、ision and bias of thistest method has not been studied.7.4.1 Drift correction can be done automatically if theinstrument embodies this option, although the calculation canbe readily done by conventional methods of data reduction andprocessing.7.5 Quality-Control (QC) Samples , for use in establishin
44、gand monitoring the stability and precision of an analyticalmeasurement system (see Section 14). Use homogeneousmaterials, similar to samples of interest and available insufficient quantity to be analyzed regularly for a long period oftimeNOTE 4Verification of system control through the use of QC sa
45、mplesand control charting is highly recommended.NOTE 5Suitable QC samples can be prepared by combining retains oftypical samples.7.6 White Oil, use a high purity mineral oil and account forits sulfur content when calculating the sulfur concentrations ofthe calibration standards.7.7 Helium, minimum p
46、urity 99.9 %, for use as an opticalpath.8. Sampling and Sample Handling8.1 Sample fuel according to the procedures in PracticesD 4057 or D 41778.2 Use the utmost care in sampling and handling gasolineto prevent evaporation of light ends which could change theconcentration of sulfur in the sample. St
47、ore gasoline in a leaktight container at 0 to 4C until ready for analysis. If possible,maintain at this temperature throughout any transfer andhandling processes.Analyze test specimens as soon as possibleafter sub-sampling from bulk container. Do not allow bulkcontainer to remain uncovered any longe
48、r than is needed toobtain desired sub-samples.8.3 For each sample, an unused piece of X-ray film isrequired for the sample cell. Avoid touching the inside of thesample cell, any portion of the film exposed to the liquid or theX-ray beam, and also avoid touching the instrument window.(It is highly re
49、commended that clean, disposable rubber orplastic gloves be used when preparing test specimens.) Oilfrom fingerprints and wrinkles can generate errors in theanalysis of sulfur. Therefore, make sure the film is taut andclean to ensure reliable results. Use calibration-check samples(see 7.2) to verify calibration integrity if the type and thicknessof the window film is changed. After the sample cell is filled,provide a vent above the sample to prevent bowing of the filmby accumulating vapors. When reusable sample cells are used,thoroughly clean and dry cells before each use. D
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