ASTM D4294-2008 Standard Test Method for Sulfur in Petroleum and Petroleum Products by Energy Dispersive X-ray Fluorescence Spectrometry.pdf

1、Designation: D 4294 08An American National StandardStandard Test Method forSulfur in Petroleum and Petroleum Products by EnergyDispersive X-ray Fluorescence Spectrometry1This standard is issued under the fixed designation D 4294; the number immediately following the designation indicates the year of

2、original 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.This standard has been approved for use by agencies of the Department

3、of Defense.1. Scope*1.1 This test method covers the determination of total sulfurin petroleum and petroleum products that are single-phase andeither liquid at ambient conditions, liquefiable with moderateheat, or soluble in hydrocarbon solvents. These materials caninclude diesel fuel, jet fuel, kero

4、sene, other distillate oil,naphtha, residual oil, lubricating base oil, hydraulic oil, crudeoil, unleaded gasoline, gasohol, biodiesel (see Note 2), andsimilar petroleum products.NOTE 1Oxygenated fuels with ethanol or methanol contents exceed-ing the limits given in Table 1 can be dealt with using t

5、his test method, butthe precision and bias statements do not apply (see Appendix X2).NOTE 2For samples with high oxygen contents (3 wt %) sampledilution as described in 1.3 or matrix matching must be performed toassure accurate results.1.2 Interlaboratory studies on precision revealed the scopeto be

6、 17 mg/kg to 4.6 mass %.An estimate of this test methodspooled limit of quantitation (PLOQ) is 17.0 mg/kg as calcu-lated by the procedures in Practice D 6259. However, becauseinstrumentation covered by this test method can vary insensitivity, the applicability of the test method at sulfurconcentrati

7、ons below approximately 20 mg/kg must be deter-mined on an individual basis. An estimate of the limit ofdetection is three times the reproducibility standard deviation,and an estimate of the limit of quantitation2is ten times thereproducibility standard deviation.1.3 Samples containing more than 4.6

8、 mass % sulfur can bediluted to bring the sulfur concentration of the diluted materialwithin the scope of this test method. Samples that are dilutedcan have higher errors than indicated in Section 16 thannon-diluted samples.1.4 Volatile samples (such as high vapor pressure gasolinesor light hydrocar

9、bons) may not meet the stated precisionbecause of selective loss of light materials during the analysis.1.5 A fundamental assumption in this test method is that thestandard and sample matrices are well matched, or that thematrix differences are accounted for (see 5.2). Matrix mis-match can be caused

10、 by C/H ratio differences between samplesand standards (see Section 5) or by the presence of otherheteroatoms.1.6 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.7 This standard does not purport to address all of thesafety con

11、cerns, if any, 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:3D 4057 Practice for Manual Sampling of

12、 Petroleum andPetroleum ProductsD 4177 Practice for Automatic Sampling of Petroleum andPetroleum Products1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition

13、approved March 1, 2008. Published April 2008. Originallyapproved in 1983. Last previous edition approved in 2003 as D 429403.2Analytical Chemistry, Vol 55, 1983, pp. 2210-2218.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. Fo

14、r Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.TABLE 1 Concentrations of Interfering SpeciesAElement Mass % ToleratedPhosphorus 0.3Zinc 0.6Barium 0.8Lead 0.9Calcium 1Chlorine 3Ethanol (Note 11)8.6Methanol (Note 11)6Fatty Acid Methyl

15、 Ester (FAME) 5AThe concentrations of substances in this table were determined by thecalculation of the sum of the mass absorption coefficients times mass fraction ofeach element present. This calculation was made for dilutions of representativesamples containing approximately 3 % of interfering sub

16、stances and 0.5 % sulfur.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.D 6259 Practice for Determination of a Pooled Limit ofQuantitationD 6299 Practice for Applying

17、 Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD 7343 Practice for Optimization, Sample Handling, Cali-bration, and Validation of X-ray Fluorescence Spectrom-etry Methods for Elemental Analysis of Petroleum Prod-ucts and LubricantsE2

18、9 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications3. Summary of Test Method3.1 The sample is placed in the beam emitted from an X-raytube. The resultant excited characteristic X radiation is mea-sured, and the accumulated count is compared with countsfro

19、m previously prepared calibration samples to obtain thesulfur concentration in mass % and/or mg/kg. A minimum ofthree groups of calibration samples are required to span theconcentration range: 0.0 to 0.1 mass %, 0.1 to 1.0 mass %, and1.0 to 5.0 mass % sulfur. (See Practice D 7343.)4. Significance an

20、d Use4.1 This test method provides rapid and precise measure-ment of total sulfur in petroleum and petroleum products witha minimum of sample preparation. A typical analysis time is 1to 5 minutes per sample.4.2 The quality of many petroleum products is related to theamount of sulfur present. Knowled

21、ge of sulfur concentration isnecessary for processing purposes. There are also regulationspromulgated in federal, state, and local agencies that restrictthe amount of sulfur present in some fuels.4.3 This test method provides a means of determiningwhether the sulfur content of petroleum or a petrole

22、um productmeets specification or regulatory limits.4.4 When this test method is applied to petroleum materialswith matrices significantly different from the calibration mate-rials specified in 9.1, the cautions and recommendations inSection 5 should be observed when interpreting results.5. Interfere

23、nces5.1 Spectral interferences are caused by the closeness of theX-ray characteristic lines of the elements present in a sampleand the limited detector ability to completely resolve them. Asa result, the lines produce spectral peaks that overlap with eachother. Spectral interferences may arise from

24、samples contain-ing lead alkyls, silicon, phosphorus, calcium, potassium, ha-lides and catalyst particles if present at concentrations greaterthan one tenth of the measured concentration of sulfur, or morethan a few hundred milligrams/kilogram (parts per millionmass ppm). Follow the manufacturers op

25、erating-guide tocompensate for the interferences.5.2 Matrix effects are caused by concentration variations ofthe elements in a sample. These variations directly influenceX-ray absorption and change the measured intensity of eachelement. For example, performance enhancing additives, suchas oxygenates

26、 in gasoline, may affect the apparent sulfurreading. Other matrix related interferences may arise fromheavy metal additives, lead alkyls, and elements such assilicon, phosphorus, calcium, potassium, and the halides,especially if present at concentrations greater than one tenth ofthe measured concent

27、ration of sulfur, or more than a fewhundred milligrams/kilogram (parts per millionppm). Thesetypes of interferences are always present in X-ray fluorescenceanalysis and are completely unrelated to spectral interferences.5.3 The interferences mentioned in 5.1 and 5.2 may becompensated for in contempo

28、rary instruments with the use ofbuilt-in software for spectra deconvolution or overlap correc-tion and inter-element correction by multiple regression or byother mathematical methods.5.4 In general, petroleum materials with compositions thatvary from oils as specified in 9.1 may be analyzed withstan

29、dards made from base materials that are of the same, orsimilar, composition. Thus, a gasoline may be simulated bymixing isooctane and toluene in a ratio that approximates thetrue aromatic content of the samples to be analyzed. Standardsmade from this simulated gasoline will produce results that arem

30、ore accurate than results obtained using white oils. Sugges-tions are given in Table 2.NOTE 3In the case of petroleum materials that contain suspendedwater, it is recommended that the water be removed before testing or thatthe sample be thoroughly homogenized and immediately tested. Theinterference

31、is greatest if the water creates a layer over the transparent filmas it will attenuate the X-ray intensity for sulfur. One such method toaccomplish the removal of water is to centrifuge the sample first underambient sealed conditions, taking care that the sample integrity is notcompromised.6. Appara

32、tus6.1 Energy-dispersive X-ray Fluorescence AnalyzerEnergy dispersive X-ray fluorescence analyzer may be used ifits design incorporates, as a minimum, the following featuresand if test results from it are shown to be equivalent on thesamples of interest. Required design features include:6.1.1 Source

33、 of X-ray Excitation, X-ray tube with excitationenergy above 2.5 keV.6.1.2 Removable Sample Cup, equipped with replaceableX-ray transparent plastic film windows and providing a sampledepth of at least 4 mm and a diameter of at least 10 mm.6.1.3 X-ray Detector, with high sensitivity and a resolutionv

34、alue (Full Width at Half Maximum, FWHM) not to exceed800 eV at 2.3 keV.6.1.4 Filters or other means of discriminating betweensulfur Ka radiation and other X-rays of higher energy.TABLE 2 Matrix DiluentsMatrix Matrix Diluent Alternate Diluent#2 Diesel #2 Diesel KerosineNaphtha Kerosine Kerosine Keros

35、ine #2 DieselResiduals Lube Oil MOWHALubricating Base Oils Lube Oil MOWLBHydraulic Oils Lube Oil MOWLBCrude Oil Lube Oil MOWHAJet Fuels Kerosine Gasoline Gasoline AMOWH = mineral oil white heavyBMOWL = mineral oil white lightD42940826.1.5 Signal conditioning and data handling electronics thatinclude

36、 the functions of X-ray intensity counting, a minimumof two energy regions, spectral overlap corrections, and con-version of sulfur X-ray intensity into mass percent sulfurconcentration.6.1.6 The analyzer shall have the sensitivity under opti-mized measurement conditions to measure the concentration

37、 ofsulfur at the 0.05 % level with a demonstrated error due tocounting statistics with one standard deviation not greater than0.5 percent relative at the 500 mg/kg level. This requirementpertains to sample measurements of less than 1000 mg/kg.6.1.7 Display or Printer that reads out in mass % sulfura

38、nd/or mg/kg sulfur.6.2 Analytical Balance, with an accuracy and resolution of0.1 mg and capable of weighing up to 100 g.NOTE 4Operation of analyzers using X-ray tube sources is to beconducted in accordance with the manufacturers safety instructions.7. Reagents7.1 Purity of ReagentsReagent grade chem

39、icals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society (ACS)where such specifications are available.4Other grades may beused, provided it is first ascertained t

40、hat the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 Di-n-Butyl Sulfide (DBS), a high-purity standard with acertified analysis for sulfur content. Use the certified sulfurcontent and the material purity when calculating the exactconce

41、ntrations of the calibration standards (see 9.1).(WarningDi-n-butyl sulfide is flammable and toxic.)NOTE 5It is essential to know the concentration of sulfur in thedi-n-butyl sulfide, not only the purity, since impurities may also be sulfurcontaining compounds.7.3 Drift Correction Monitor(s) (Option

42、al)Several differ-ent materials have been found to be suitable for use as driftcorrection monitors. Appropriate drift monitor samples shouldbe permanent materials that are stable with respect to repeatedexposure to X-rays. Stable liquids like polysulfide oils, glass ormetallic specimens are recommen

43、ded. Liquids, pressed pow-ders, and solid materials that degrade with repeated exposure toX-rays should not be used. Examples of sulfur containingmaterials that have been found to be suitable include arenewable liquid petroleum material, a metal alloy, or a fusedglass disk. The monitors counting rat

44、e, in combination withcount time, shall be sufficient to give a relative counting errorof less than 1 %. The counting rate for the monitor sample isdetermined during calibration (see 9.2.1) and again at the timeof analysis (see 12.2). These counting rates are used tocalculate a drift correction fact

45、or (see 15.6).7.3.1 Drift correction is usually implemented automaticallyin software, although the calculation can readily be donemanually. For X-ray instruments that are highly stable, themagnitude of the drift correction factor may not differ signifi-cantly from unity.7.4 Polysulfide Oil, generall

46、y nonyl polysulfides containinga known percentage of sulfur diluted in a hydrocarbon matrix.(WarningMay cause allergic skin reactions.)NOTE 6Polysulfide oils are high molecular weight oils that containhigh concentrations of sulfur, as high as 50 weight percent. They exhibitexcellent physical propert

47、ies such as low viscosity, low volatility, anddurable shelf life while being completely miscible in white oil. Polysulfideoils are readily available commercially. The sulfur content of the polysul-fide oil concentrate is determined via mass dilution in sulfur-free white oilfollowed by a direct compa

48、rison analysis against NIST reference materi-als.7.5 Mineral Oil, White (MOW), ACS Reagent Grade con-taining less than 2 mg/kg sulfur or other suitable base materialcontaining less than 2 mg/kg sulfur. When low level (200mg/kg) measurements are anticipated, then the sulfur content,if any, of the bas

49、e material needs to be included in thecalculation of calibration standard concentration (see 9.1).When the sulfur content of the solvent or reagent is notcertified, verify the absence of sulfur. Use the purest availablegrades for chemicals to be used for preparing calibrationstandards.7.6 X-ray Transparent FilmAny film that resists attack bythe sample, is free of sulfur, and is sufficiently X-ray transpar-ent can be used. Film types can include polyester, polypropy-lene, polycarbonate, and polyimide. However, samples of higharomatic content can dissolve polypropyle