1、Designation: D4294 161Standard 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 c
2、ase 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 U.S. Department of Defense.1NOTEThe overal
3、l layout of the Appendix sections was editorially corrected in February 2016.1. 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 hydrocarbo
4、n solvents. These materials caninclude diesel fuel, jet fuel, kerosine, other distillate oil,naphtha, residual oil, lubricating base oil, hydraulic oil, crudeoil, unleaded gasoline, gasoline-ethanol blends, biodiesel (seeNote 2), and similar petroleum products.NOTE 1Oxygenated fuels with ethanol or
5、methanol 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 weight %) sampledilution as described in 1.3 or matrix matching must be performed toas
6、sure accurate results.1.2 Interlaboratory studies on precision revealed the scopeto be 17 mg kg to 4.6 mass %. An estimate of this testmethods pooled limit of quantitation (PLOQ) is 16.0 mg kg ascalculated by the procedures in Practice D6259. However,because instrumentation covered by this test meth
7、od can varyin sensitivity, 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
8、ten times 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
9、samples.1.4 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 th
10、at thematrix 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 include
11、d in thisstandard.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 u
12、se.2. Referenced Documents2.1 ASTM Standards:3D4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD6259 Practice for Determination of a Pooled Limit ofQuantitation for a Test MethodD6299 Practice for Applying St
13、atistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD7343 Practice for Optimization, Sample Handling,Calibration, and Validation of X-ray Fluorescence Spec-trometry Methods for Elemental Analysis of PetroleumProducts and Lubricants1This test
14、 method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.03 on Elemental Analysis.Current edition approved Jan. 1, 2016. Published February 2016. Originallyapproved in 1983. Last previous edition ap
15、proved in 2010 as D4294 10. DOI:10.1520/D4294-16E01.2Analytical 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 information, refer to the standards
16、 Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1E29 Practice for Using Significant Digits in Test Data toDetermine Conformance
17、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 ismeasured, and the accumulated count is compared with countsfrom previously prepared calibration samples to obtain thesulfur concentration in
18、mass percent or mg/kg, or both. Aminimum of three groups of calibration samples are required tospan the concentration range: 0.0 mass % to 0.1 mass %,0.1 mass % to 1.0 mass %, and 1.0 mass % to 5.0 mass %sulfur. (See Practice D7343.)4. Significance and Use4.1 This test method provides rapid and prec
19、ise measure-ment of total sulfur in petroleum and petroleum products witha minimum of sample preparation. A typical analysis time is1 min to 5 min per sample.4.2 The quality of many petroleum products is related to theamount of sulfur present. Knowledge of sulfur concentration isnecessary for proces
20、sing 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 specification or regulatory limit
21、s.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 interferences are caused by the
22、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 lead alkyls, silicon, phospho
23、rus, calcium, potassium,halides, and catalyst particles if present at concentrationsgreater than one tenth of the measured concentration of sulfur,or more than a few hundred milligrams/kilogram (parts permillionmass ppm). Follow the manufacturers operating-guide to compensate for the interferences.5
24、.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 affect the apparent sulfurreadin
25、g. 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 more than a fewhundred millig
26、rams/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 with the use ofbuilt-in software
27、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 materials that are of the sam
28、e, 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 results obtained using white oil
29、s. 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 water creates a layer over the
30、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-dispersive X-ray Fluorescence Analyz
31、erEnergy 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 , X-ray tube with excitatione
32、nergy above 2.5 keV.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 substances in this table were determined by the calcula
33、-tion of the sum of the mass absorption coefficients times mass fraction of eachelement present. This calculation was made for dilutions of representative samplescontaining approximately 3 % of interfering substances and 0.5 % sulfur.TABLE 2 Matrix DiluentsMatrix Matrix Diluent Alternate Diluent#2 D
34、iesel #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 = mineral oil white lightD4294 16126.1.2 Remo
35、vable 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 Half Maximum, FWHM) not to exceed800 eV at 2.3 keV.6.1.4 Fi
36、lters or other means of discriminating betweensulfur K 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 minimumof two energy regions, spectral overlap corrections, and con-version of sulfur X-
37、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 0.05 % level with a demonstrated error due tocounting statistics with one standard deviation not greater than0.5 % re
38、lative 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 percentsulfur or mg/kg sulfur, or both.6.2 Analytical Balance, with an accuracy and resolution of0.1 mg and capable of weighing up to 100 g.NOTE 4Ope
39、ration 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 in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the
40、 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 ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 Di-n-Butyl
41、 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 calibration standards (see 9.1).(WarningDi-n-butyl sulfide is flammable and toxic.)NOTE 5It is essential to know
42、 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-ent materials have been found to be suitable for use as driftcorrection monitors. Appropriate drift monitor sam
43、ples shouldbe permanent materials that are stable with respect to repeatedexposure to X-rays. Stable liquids like polysulfide oils, glass,or metallic specimens are recommended. Liquids, pressedpowders, and solid materials that degrade with repeated expo-sure to X-rays should not be used. Examples of
44、 sulfurcontaining materials that have been found to be suitableinclude a renewable liquid petroleum material, a metal alloy, ora fused glass disk. The monitors counting rate, in combinationwith count time, shall be sufficient to give a relative countingerror of less than 1 %. The counting rate for t
45、he monitor sampleis determined during calibration (see 9.2.1) and again at thetime of 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 do
46、nemanually. 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 polysulfides containinga known percentage of sulfur diluted in a hydrocarbon matrix.(WarningMay cause allergic skin reac
47、tions.)NOTE 6Polysulfide oils are high molecular weight oils that containhigh concentrations of sulfur, as high as 50 weight %. They exhibitexcellent physical properties such as low viscosity, low volatility, anddurable shelf life while being completely miscible in white oil. Polysulfideoils are rea
48、dily 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 against NIST reference materi-als.7.5 Mineral Oil, White (MOW), ACS Reagent Grade con-taining less than 2 mg/kg sulfur
49、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 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
