1、Designation: D4294 10Standard 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 ca
2、se 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.1. Scope*1.1 This tes
3、t 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, kerosine, other distillate oil,napht
4、ha, 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 this test method, butthe precisio
5、n 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 accurate results.1.2 Interlaboratory studies on precision revealed the scopeto be 17 mg/kg to 4.6 mass %.An estim
6、ate of this test methodspooled limit of quantitation (PLOQ) is 16.0 mg/kg as calcu-lated by the procedures in Practice D6259. However, becauseinstrumentation covered by this test method can vary insensitivity, the applicability of the test method at sulfurconcentrations below approximately 20 mg/kg
7、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 mass % sulfur can bediluted to b
8、ring 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 hydrocarbons) may not meet the stated pre
9、cisionbecause 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 by C/H ratio differences between
10、 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 concerns, if any, associated with it
11、s 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:3D4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4
12、177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD6259 Practice for Determination of a Pooled Limit ofQuantitation1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.03 on Eleme
13、ntal Analysis.Current edition approved Feb. 15, 2010. Published March 2010. Originallyapproved in 1983. Last previous edition approved in 2008 as D429408a1. DOI:10.1520/D4294-10.2Analytical Chemistry, Vol 55, 1983, pp. 2210-2218.3For referenced ASTM standards, visit the ASTM website, www.astm.org, o
14、rcontact ASTM Customer Service at serviceastm.org. For 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 3Eth
15、anol (Note 11)8.6Methanol (Note 11)6Fatty Acid Methyl 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 representativesa
16、mples containing approximately 3 % of interfering substances 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.D6299 Practice for Applying Statistical Q
17、uality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD7343 Practice for Optimization, Sample Handling, Cali-bration, and Validation of X-ray Fluorescence Spectrom-etry Methods for Elemental Analysis of Petroleum Prod-ucts and LubricantsE29 Practice for
18、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 countsfrom previously pr
19、epared 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 D7343.)4. Significance and Use4.1 This te
20、st 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.4.2 The quality of many petroleum products is related to theamount of sulfur present. Knowledge of sulfur concent
21、ration 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 petroleum productmeets spec
22、ification 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. Interferences5.1 Spectral int
23、erferences 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 samples contain-ing
24、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 operating-guide tocomp
25、ensate 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 in gasoline, may af
26、fect 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 concentration of sulfur, or
27、 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 contemporary instruments wit
28、h 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 withstandards made from base
29、 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 aremore accurate than re
30、sults 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 is greatest if the w
31、ater 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. Apparatus6.1 Energy-disper
32、sive 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 of X-ray Excitation
33、, 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 resolutionvalue (Full Width at
34、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.6.1.5 Signal conditioning and data handling electronics thatinclude the functions of X-ray intensity counting, a minimumTABLE 2 Matrix Diluen
35、tsMatrix Matrix Diluent Alternate Diluent#2 Diesel #2 Diesel KerosineNaphtha Kerosine Kerosine Kerosine #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
36、= mineral oil white lightD4294 102of 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 ofsulfur at the 0.
37、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 % sulfurand/or mg/kg sulfur.
38、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 chemicals shall beused
39、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 that the reagent is
40、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 exactconcentrations of the ca
41、libration 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) (Optional)Several differ-e
42、nt 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 recommended. Liquids, press
43、ed 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 rate, in combination w
44、ithcount 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 factor (see 15.6).7.3.1
45、 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, generally nonyl polysulfide
46、s 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 properties such as low vis
47、cosity, 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 comparison analysis agai
48、nst 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 base material needs to
49、 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 polypropylene, polycarbonat
