1、Designation: D 4294 03An American National StandardStandard Test Method forSulfur in Petroleum and Petroleum Products by Energy-Dispersive X-ray Fluorescence Spectrometry1This standard is issued under the fixed designation D 4294; the number immediately following the designation indicates the year o
2、foriginal 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 measurement of sulfur inhydrocarbons, such as diesel, naphtha, kerosine, residuals,lubricating base oils, hydraulic oils, jet fuels, crude oils,gasoline (all unleaded), and other distillates. In addition, sulfurin other products, such as M-85 and
4、M-100, may be analyzedusing this technique. The applicable concentration range is0.0150 to 5.00 mass % sulfur.1.2 The values stated in SI units are to be regarded as thestandard. The preferred concentration units are mass % sulfur.1.3 This standard does not purport to address all of thesafety concer
5、ns, 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. For specificwarning statements, see Section 7.2. Referenced Documents2.1 ASTM Stand
6、ards:2D 3120 Test Method for Trace Quantities of Sulfur in LightLiquid Petroleum Hydrocarbons by Oxidative Microcou-lometryD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsE 29 Practice for Using Significan
7、t Digits in Test Data toDetermine Conformance with Specifications3. Summary of Test Method3.1 The sample is placed in the beam emitted from an X-raysource. The resultant excited characteristic X radiation ismeasured, and the accumulated count is compared with countsfrom previously prepared calibrati
8、on standards that bracket thesample concentration range of interest to obtain the sulfurconcentration in mass %.4. Significance and Use4.1 This test method provides rapid and precise measure-ment of total sulfur in petroleum products with a minimum ofsample preparation. A typical analysis time is 2
9、to 4 min persample.4.2 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 som
10、e fuels.4.3 This test method provides a means of compliance withspecifications or limits set by regulations for sulfur content ofpetroleum products.4.4 If this test method is applied to petroleum matrices withsignificantly different composition than the white oil calibra-tion materials specified in
11、this test method, the cautions andrecommendations in Section 5 should be observed wheninterpreting the results.4.5 Compared to other test methods for sulfur determina-tion, Test Method D 4294 has high throughput, minimal samplepreparation, good precision, and is capable of determiningsulfur over a w
12、ide range of concentrations. The equipmentspecified is in most cases less costly than that required foralternative methods. Consult the ASTM website2or ASTMSubject Index3for names of alternative test methods.5. Interferences5.1 Spectral interferences result when some sample compo-nent element or ele
13、ments emit X-rays that the detector cannotresolve from sulfur X-ray emission. As a result, the linesproduce spectral peaks that overlap with each other. Spectralinterferences may arise from samples containing water, leadalkyls, silicon, phosphorus, calcium, potassium, and halides ifpresent at concen
14、trations greater than one tenth of the mea-sured concentration of sulfur, or more than a few hundred1This test method is under the jurisdiction of Committee D02 on PetroleumProducts and Lubricants and is the direct responsibility of Subcommittee D02.03 onElemental Analysis.Current edition approved N
15、ov. 1, 2003. Published December 2003. Originallyapproved in 1983. Last previous edition approved in 2002 as D 4294-02.2For 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 t
16、o the standards Document Summary page onthe ASTM website.3Annual Book of ASTM Standards, Vol 00.01.1*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.milligrams/kilogram.
17、 Follow the manufacturers operating-guide to compensate 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
18、 additives, suchas oxygenates in gasoline, can affect the apparent sulfurreading. These types of interferences are always present inX-ray fluorescence analysis and are completely unrelated tospectral interferences.5.3 Both types of interferences are compensated for incontemporary instruments with th
19、e use of built-in software. Itis recommended that these interferences be checked from timeto time and that the software corrections offered by themanufacturer not be accepted at face value. Corrections shouldbe verified for new formulations.5.4 M-85 and M-100 are fuels containing 85 and 100 %methano
20、l, respectively. As such, they have a high oxygencontent, hence, absorption of sulfur Ka radiation. Such fuelscan, however, be analyzed using this test method provided thatthe calibration standards are prepared to match the matrix ofthe sample. There may be a loss of sensitivity and precision.The re
21、peatability, reproducibility, and bias obtained in this testmethod did not include M-85 and M-100 samples.5.5 In general, petroleum materials with compositions thatvary from white oils as specified in 9.1 may be analyzed withstandards made from base materials that are of the same, orsimilar, composi
22、tion. 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 oils.NOTE 1In the case o
23、f 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 transparent filmas it will attenuate the X-ray intensity
24、 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 AnalyzerAnyenergy dispersive X-ray fluorescence analyzer may b
25、e used ifits design incorporates, as a minimum, the following features:6.1.1 Source of X-ray Excitation, X-ray source with energyabove 2.5 keV. (WarningIn addition to other precautions, ifa radioactive source is used, it must be well shielded tointernational standard requirements and, therefore, not
26、 presentany safety hazard. However, attention to the source is only tobe carried out by a fully trained and competent person using thecorrect shielding techniques.)NOTE 2Operation of analyzers using X-ray tube sources is to beconducted in accordance with the manufacturers safety instructions andloca
27、l regulations.6.1.2 Sample Cell, providing a sample depth of at least 4mm and equipped with a replaceable X-ray transparent plasticfilm window.6.1.3 X-ray Detector, with sensitivity at 2.3 keV and aresolution value not to exceed 800 eV. A gas filled proportionalcounter has been found to be suitable
28、to use.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 minimumof two energy regions (to correct for background X-rays),spectra
29、l overlap corrections, and conversion of sulfur X-rayintensity into percent sulfur concentration.6.1.6 Display or Printer, that reads out in mass % sulfur.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended that
30、all reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.4Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the
31、accuracy ofthe determination.7.2 Di-n-Butyl Sulfide (DBS), a high purity standard with acertified analysis for sulfur content. Use the certified sulfurcontent when calculating the exact concentrations of thecalibration standards (9.1.7). (WarningDi-n-butyl sulfide isflammable and toxic.)NOTE 3It is
32、essential to know the concentration of the sulfur in thedi-n-butyl sulfide, not the purity, since impurities may also be sulfurcontaining compounds.7.3 Mineral Oil, White (MOW), ACS reagent grade or lessthan 2 mg/kg sulfur.7.4 X-ray Transparent Film, any film that resists attack bythe sample, is fre
33、e of sulfur, and is sufficiently X-ray transpar-ent may be used. Films found to be suitable are polyester,polypropylene, polycarbonate, and polyimide films.7.4.1 Samples of high aromatic content may dissolve poly-ester and polycarbonate films. In these cases, other materialsbesides these films may b
34、e used for X-ray windows, providedthat they do not contain any elemental impurities. An optionalwindow material is polyimide foil. Although polyimide foilabsorbs sulfur X-rays more than other films, it may be apreferred window material as it is much more resistant tochemical attack by aromatics and
35、exhibits higher mechanicalstrength.7.5 Sample Cells, resistant to sample attack and meetgeometry requirements of spectrometer.8. Sampling and Specimen Preparation8.1 Samples shall be taken in accordance with the instruc-tions in Practice D 4057 or D 4177, where appropriate.4Reagent Chemicals, Americ
36、an Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary,
37、U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D4294032Samples should be analyzed immediately after pouring into asample cell and allowing for the escape of the air bubblescaused by mixing.8.2 If using reusable sample cells, clean and dry cells beforeuse. Disposable sample cells are not to
38、 be reused. A new pieceof X-ray film on a reused sample cell is required prior toanalyzing the sample. Avoid touching the inside of the samplecell or portion of the window film in the cell or in theinstrument window that is exposed to X-rays. Oil fromfingerprints can affect the reading when analyzin
39、g for lowlevels of sulfur. Wrinkles in the film will affect the intensity ofsulfur X-rays transmitted. Therefore, it is essential that the filmbe taut and clean to ensure reliable results. The analyzer willneed recalibration if the type or thickness of the window filmis changed.8.3 Impurities or thi
40、ckness variations, which may affect themeasurement of low levels of sulfur, have been found inpolyester films and may vary from lot to lot. Therefore, thecalibration shall be verified after starting each new roll of film.9. Calibration and Standardization9.1 Preparation of Calibration Standards:9.1.
41、1 Although it is possible to make a single calibration tomeasure sulfur in a variety of matrices, it is strongly recom-mended that, whenever possible, the calibration is matrixspecific, that is, a diesel calibration should be based on dieselstandards. This is especially true for the analysis of sulf
42、ur atlow levels. Hence, the matrix diluent should be as close to theform of the matrix being analyzed as possible. White mineraloil (see 7.3) is acceptable as an alternative matrix diluent.9.1.2 Make primary standards independently at normalconcentrations of 0.1 and 5 mass % sulfur and not by serial
43、dilution from a single concentrate. The exact sulfur content ineach standard is to be calculated to four decimal places.9.1.3 Accurately weigh the nominal quantity of matrixdiluent to the nearest 0.1 mg, as shown in Table 1, into asuitable, narrow-necked container and then accurately weigh inthe nom
44、inal quantity of di-n-butyl sulfide. Mix thoroughly (aPTFE-coated magnetic stirrer is advisable) at room tempera-ture.9.1.4 Prepare calibration standards that will bracket theexpected sulfur concentrations in samples, using the matrixdiluent (9.1.1) and the primary standards (9.1.2) to prepare thebl
45、ank and known standard concentrations, respectively, foreach calibration range that is established. Consult the manu-facturers instructions for determining the number of standardsand ranges to prepare. Table 2 provides an example of how twoconcentration ranges can be prepared by diluting each primar
46、ystandard with the applicable matrix diluent.9.1.4.1 Standard 1 on Range 2 in Table 2 may not berequired if the instrument is also calibrated on Range 1.Consult the manufacturers calibration instructions for specificguidance.9.1.5 Alternatively, National Institute of Standards andTechnology (NIST) t
47、raceable certified standards, prepared asdescribed above or composed of the matrix to be analyzed, canbe used.9.1.6 If the matrix diluent being used for the preparation ofstandards contains sulfur, add this value to the calculated sulfurcontent of the prepared standards (consult your supplier for ac
48、ertified sulfur concentration or test the mineral oil using TestMethod D 3120 or any other equivalent low level sulfuranalyzing method with an MDL no higher than 1 ppm).9.1.7 Weigh the DBS and matrix diluent to the recom-mended mass to the nearest 0.1 mg. It is important that theactual mass is known
49、; thus, the actual concentration of theprepared standards is calculated and entered into the instrumentfor calibration purposes. The concentration of sulfur can becalculated using the following equation:S 5 DBS 3 SDBS! 1 MO 3 SMO!#/DBS 1 MO! (1)where:S = mass % sulfur of the prepared standards,DBS = actual mass of DBS, g,SDBS= the mass % sulfur in DBS, typically 21.91 %,MO = actual mass of mineral oil, g,SMO= mass % sulfur in the mineral oil.9.2 Certified Calibration StandardsCalibration standards,which are certified by a national standards organization, maybe used in pla
