ASTM D4294-2008ae1 Standard Test Method for Sulfur in Petroleum and Petroleum Products by Energy Dispersive X-ray Fluorescence Spectrometry.pdf

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1、Designation: D4294 08a1Standard Test Method forSulfur in Petroleum and Petroleum Products by EnergyDispersive X-ray Fluorescence Spectrometry1This standard is issued under the fixed designation D4294; the number immediately following the designation indicates the year oforiginal adoption or, in the

2、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.This standard has been approved for use by agencies of the Department of Defense.1NOTENIST 2723a no

3、longer appears in Appendix X1; deleted related Note X1.1 editorially in November 2009.1. 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 h

4、ydrocarbon solvents. These materials caninclude diesel fuel, jet fuel, kerosine, 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 methano

5、l contents exceed-ing the limits given in Table 1 can be dealt with using this test method, butthe precision and bias statements do not apply (see Appendix X3).NOTE 2For samples with high oxygen contents (3 wt %) sampledilution as described in 1.3 or matrix matching must be performed toassure accura

6、te results.1.2 Interlaboratory studies on precision revealed the scopeto be 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 D6259. However, becauseinstrumentation covered by this test method can var

7、y insensitivity, the applicability of the test method at sulfurconcentrations 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

8、thereproducibility standard deviation.1.3 Samples containing more than 4.6 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.

9、4 Volatile samples (such as high vapor pressure gasolinesor light hydrocarbons) 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 thematr

10、ix differences are accounted for (see 5.2). Matrix mis-match can be caused 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 thiss

11、tandard.1.7 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Refe

12、renced Documents2.1 ASTM Standards:31This 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 approved Oct. 15, 2008. Published November 2008. Originallyapproved i

13、n 1983. Last previous edition approved in 2008 as D429408. DOI:10.1520/D4294-08AE01.2Analytical 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. For Annual Book of ASTMStandards volume inf

14、ormation, 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 Ester (FAME) 5AThe concentrations of sub

15、stances 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 substances and 0.5 % sulfur.1*A Summary of C

16、hanges 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.D4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum Pr

17、oductsD6259 Practice for Determination of a Pooled Limit ofQuantitationD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD7343 Practice for Optimization, Sample Handling, Cali-bration, and Validation of X-ray

18、Fluorescence Spectrom-etry Methods for Elemental Analysis of Petroleum Prod-ucts and LubricantsE29 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 exci

19、ted characteristic X radiation is mea-sured, and the accumulated count is compared with countsfrom 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

20、 mass %, 0.1 to 1.0 mass %, and1.0 to 5.0 mass % sulfur. (See Practice D7343.)4. Significance and 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 min per sample.4

21、.2 The quality of many petroleum products is related to theamount of sulfur present. Knowledge 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 tes

22、t method provides a means of determiningwhether the sulfur content of petroleum or a petroleum 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 cautio

23、ns and recommendations inSection 5 should be observed when interpreting results.5. Interferences5.1 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 line

24、s produce spectral peaks that overlap with eachother. Spectral interferences may arise from 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 moretha

25、n a few hundred milligrams/kilogram (parts per millionmass ppm). Follow the manufacturers operating-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 measur

26、ed intensity of eachelement. For example, performance enhancing additives, suchas oxygenates 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 h

27、alides,especially if present at concentrations greater than one tenth ofthe measured concentration 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 in

28、terferences.5.3 The interferences mentioned in 5.1 and 5.2 may becompensated for in contemporary 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

29、 materials with compositions thatvary from oils as specified in 9.1 may be analyzed withstandards 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 sampl

30、es to be analyzed. Standardsmade from this simulated gasoline will produce results that aremore 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

31、testing or thatthe sample be thoroughly homogenized and immediately tested. Theinterference 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 under

32、ambient sealed conditions, taking care that the sample integrity is notcompromised.6. Apparatus6.1 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 sho

33、wn to be equivalent on thesamples of interest. Required design features include:6.1.1 Source 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 an

34、d a diameter of at least 10 mm.6.1.3 X-ray Detector, with high sensitivity and a resolutionvalue (Full Width at Half Maximum, FWHM) not to exceed800 eV at 2.3 keV.TABLE 2 Matrix DiluentsMatrix Matrix Diluent Alternate Diluent#2 Diesel #2 Diesel KerosineNaphtha Kerosine Kerosine Kerosine #2 DieselRes

35、iduals 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 lightD4294 08a126.1.4 Filters or other means of discriminating betweensulfur Ka radiation and ot

36、her X-rays of higher energy.6.1.5 Signal conditioning and data handling electronics thatinclude 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

37、shall have the sensitivity under opti-mized measurement conditions to measure the concentration 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

38、 measurements of less than 1000 mg/kg.6.1.7 Display or Printer that reads out in mass % sulfurand/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

39、 with the manufacturers safety instructions.7. Reagents7.1 Purity of ReagentsReagent grade chemicals 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

40、 such specifications are available.4Other grades may beused, provided it is first ascertained that 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 c

41、ontent. Use the certified sulfurcontent and the material purity when calculating the exactconcentrations 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,

42、since impurities may also be sulfurcontaining compounds.7.3 Drift Correction Monitor(s) (Optional)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 repeatedex

43、posure to X-rays. Stable liquids like polysulfide oils, glass ormetallic specimens are recommended. 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 arene

44、wable liquid petroleum material, a metal alloy, or a fusedglass disk. The monitors counting rate, 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 th

45、e timeof analysis (see 12.2). These counting rates are used tocalculate a drift correction factor (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

46、 drift correction factor may not differ signifi-cantly from unity.7.4 Polysulfide Oil, generally 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

47、 concentrations of sulfur, as high as 50 weight percent. They exhibitexcellent physical properties 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

48、 concentrate is determined via mass dilution in sulfur-free white oilfollowed by a direct comparison 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. Whe

49、n low level (200mg/kg) measurements are anticipated, then the sulfur content,if any, of the base 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-