1、Designation: D7220 12 (Reapproved 2017)Standard Test Method forSulfur in Automotive, Heating, and Jet Fuels byMonochromatic Energy Dispersive X-ray FluorescenceSpectrometry1This standard is issued under the fixed designation D7220; the number immediately following the designation indicates the year
2、oforiginal adoption or, in the 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.1. Scope1.1 This test method specifies an energy-dispersive X-rayfluo
3、rescence (EDXRF) method for the determination of totalsulfur in automotive, No. 2 heating, and jet fuels with aconcentration range of 3 mg kg to 942 mg kg.1.1.1 The pooled limit of quantitation of this test method asobtained by statistical analysis of inter laboratory test results is3 mg kg sulfur.1
4、.1.2 This test method is applicable to gasoline, oxygenenriched gasoline (RFG), diesel, diesel/biodiesel blends con-taining up to twenty volume percent biodiesel, kerosene, jetfuel, jet fuel/biodiesel blends containing up to five volumepercent biodiesel and No. 2 home heating oil.1.2 A fundamental a
5、ssumption in this test method is that thestandard and sample matrix is well matched. Matrix mismatchcan be caused by C/H ratio differences between samples andstandards or by the presence of other heteroatoms.1.3 The values stated in SI units are to be regarded asstandard. No other units of measureme
6、nt are included in thisstandard.1.3.1 The preferred concentration units are mg/kg sulfur.1.4 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 practice
7、s and determine the applica-bility of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Re
8、com-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD6299 Practice for
9、Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD6300 Practice for Determination of Precision and BiasData for Use in Test Methods for Petroleum Products andLubricantsE29 Practice for Using Significant Digits in Test Data toDe
10、termine Conformance with Specifications3. Terminology3.1 Definitions:3.1.1 monochromatic X-radiation, nan incident X-raybeam on a sample having a selected photon energy with anarrow energy bandwidth of 65 % relative to the selectedenergy.3.1.1.1 DiscussionMonochromatic X-ray radiation inEDXRF instru
11、mentation can be obtained by using Bragg optics(at an angle of=456 5, in the low energy range). Braggoptics (monochromators) create very intense mono-energeticradiation. A combination of a selected X-ray tube (typically aPd or Ag anode) with a highly ordered pyrolytic graphite(HOPG) Bragg optic can
12、be used to create monochromaticradiation of the characteristic radiation of the anode material ofthe X-ray tube. The use of such radiation for sample excitationresults in increased sensitivity for the determination of sulfur inpetroleum products.3.2 Abbreviations:3.2.1 DBSactual mass of Di-n-butyl s
13、ulfide, g3.2.2 Kcpskilo-counts per second.1This test 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 May 1, 2017. Published July 2017. Origi
14、nally approvedin 2006. Last previous edition approved in 2012 as D7220 12. DOI: 10.1520/D7220-12R17.2For 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 to the standards Do
15、cument Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on
16、 Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.3 EDXRFEnergy dispersive X-ray spectrometry3.2.4 PTFEPolytetrafluorethylene3.2.5 SDBSmass % of sulfur in Di-n-butyl sulfide, t
17、ypi-cally 21.91 %3.2.6 SStdmg/kg sulfur in the calibration standard3.2.7 SStockmg/kg of sulfur in the stock standard3.2.8 STKactual mass of stock standard, g4. Summary of Test Method4.1 The sample is placed in the monochromatic X-ray beam,and the peak area of the sulfur K line at 2.307 keV ismeasure
18、d. The background spectrum, measured with a sulfurfree white oil or other matrix matching blank sample (see 8.4)is adapted to the measured spectrum using adjustment regionsfollowing the instrument manufacturers instructions and thensubtracted from the measured spectrum. The resultant netcounting rat
19、e is then compared to a previously preparedcalibration curve or equation to obtain the concentration ofsulfur in mg/kg. (WarningExposure to excessive quantitiesof X-radiation is injurious to health. The operator needs to takeappropriate actions to avoid exposing any part of their body,not only to pr
20、imary X-rays, but also to secondary or scatteredradiation that might be present. The X-ray spectrometer shouldbe operated in accordance with the regulations governing theuse of ionizing radiation.)5. Significance and Use5.1 This test method provides measurement of total sulfur inautomotive, No. 2 he
21、ating, and jet fuels with a minimum ofsample preparation.Atypical analysis time is 180 s to 360 s persample.5.2 The quality of automotive, No. 2 heating, and jet fuelcan be related to the amount of sulfur present. Knowledge ofsulfur concentration is necessary for processing purposes.There are also r
22、egulations promulgated in federal, state, andlocal agencies that restrict the amount of sulfur present in somefuel.5.3 If this test method is applied to petroleum materials withmatrices significantly different from the calibration materialsspecified in this test method, the cautions and recommenda-t
23、ions in Section 6 should be observed when interpreting theresults.6. Interferences6.1 When the elemental composition (excluding sulfur) ofsamples differs significantly from the standards, errors in thesulfur determination can result. For example, differences in thecarbon-hydrogen ratio of sample and
24、 calibration standardsintroduce errors in the determination.6.2 M-85 and M-100 are fuels containing 85 % and 100 %methanol, respectively. They have a high oxygen contentleading to significant absorption of sulfur K radiation. Suchfuels can, however, be analyzed using this test method pro-vided eithe
25、r that correction factors are applied to the results(when calibrating with white oils) or that the calibrationstandards are prepared to match the matrix of the sample.6.3 In general, petroleum materials with compositions thatvary from the calibration samples as specified in Section 11 canbe analyzed
26、 with standards made from base materials that areof the same or similar composition. Thus a gasoline may besimulated by mixing isooctane and toluene in a ratio thatapproximates the expected aromatic content of the samples tobe analyzed. Standards made from this simulated gasoline canproduce results
27、that are more accurate than results obtainedusing white oil standards.7. Apparatus7.1 Monochromatic X-ray Fluorescence AnalyzerAMonochromatic Excitation Energy Dispersive XRF spectrom-eter may be used if its design incorporates as a minimum, thefollowing features:7.1.1 Source of X-ray Excitation, X-
28、ray end window tubewith Ag or Pd anode, in combination with HOPG Braggmonochromating X-ray optics. The monochromator must pro-duce monochromatic Ag or Pd L radiation. Other anodematerials and monochromators may be utilized, however statedprecision and bias may not apply.7.1.2 Sample Cell, providing
29、a sample depth of at least4 mm and equipped with replaceable X-ray transparent filmwindow.7.1.3 X-ray Detector, with a resolution value not to exceed175 eV at 5.9 Kcps (10 000 cps). A Si drift chamber has beenfound suitable for use. Using a detection system with thisminimum spectral resolution has b
30、een shown to eliminate thepotential effect of interference from chlorine on sulfur shouldeither salt contamination, or chlorine from other sources (forexample, recycled vegetable oils) occur.7.1.4 He-flush, the system must allow flushing of the opticalpath with helium (see 8.6).Alternatively, a vacu
31、um of 4.0 kPa(30.4 Torr) is applied to the optical path.7.1.5 Signal Conditioning and Data Handling Electronics,including the functions of X-ray intensity counting, spectrahandling by background subtraction and deconvolution, calcu-lation of overlap corrections and conversion of sulfur X-rayintensit
32、y into mg/kg sulfur concentration.8. Reagents and Materials8.1 Purity of Reagents3Reagent 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 where
33、such specifications are available. Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.8.2 Di-n-butyl Sulfidea high-purity standard with a certi-fied analysis for sulfur content.
34、 Use the certified sulfur contentwhen calculating the exact concentrations of the calibration3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Stand
35、ards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D7220 12 (2017)2standards (see 11.1). (WarningDi- n-butyl sulfide is bothflammable and toxic.)NOTE 1It is essential to know
36、the concentration of sulfur in thedi-n-butyl sulfide, not the purity, since impurities may also be sulfurcontaining compounds.8.3 Drift Correction Monitor(s) (Optional)Several differ-ent materials have been found to be suitable for use as driftcorrection monitors. Examples of sulfur containing mater
37、ialsthat have been found to be suitable include a renewable liquidpetroleum material or a fused glass disk. The monitors countrate, in combination with count time, shall be sufficient to givea relative counting error of less than 1 %. The count rate for themonitor sample is determined during calibra
38、tion (see 11.4) andagain at the time of analysis (see 12.1). These counting ratesare used to calculate a drift correction factor (see 13.1).8.3.1 Drift correction is usually implemented automaticallyin software, although the calculation can readily be donemanually. For X-ray instruments that are hig
39、hly stable, themagnitude of the drift correction factor may not differ signifi-cantly from unity.8.4 White Oil (Light Paraffn Oil) or Matrix-MatchingBlank Sample, with a certified content of less than 0.2 mg kgsulfur. If only one matrix is to be analyzed (for example, diesel)accuracy of results may
40、be improved by using a matrixmatched diluent. In these cases, the matrix matched diluentshould match approximately the C/H ratio and oxygen contentof the material to be analyzed.8.5 X-ray Transparent FilmAny film that resists attack bythe sample, is free of sulfur, and is sufficiently X-ray transpar
41、-ent can be used, with film thickness of between 2 m to 6 m.Films can include polyester, polypropylene, polycarbonate, andpolyimide. Typically polycarbonate with a thickness of 5 m to6 m is used. However, samples of high aromatic content candissolve polyester and polycarbonate films. It is important
42、 thatsamples, standards, and blanks be measured using the samebatch of film to avoid bias.8.6 Helium Gas, minimum purity 99.9 %.8.7 Sample Cells, compatible with the sample and thegeometry requirements of the spectrometer. Disposable cellsare recommended.8.8 Calibration Check Samples, portions of on
43、e or moreliquid petroleum or product standards of known sulfur contentand not used in the generation of the calibration curve. Thecheck samples shall be used to determine the accuracy of theinitial calibration (see 11.5).8.9 Quality Control Samples, stable petroleum or productsamples representative
44、of the samples of interest that are run ona regular basis to verify that the system is in statistical control.NOTE 2Verification of system control through the use of QC samplesand control charting is highly recommended. It is recognized that QCprocedures are the province of the individual laboratory
45、. Suitable QCsamples can often be prepared by combining retains of typical samples.9. Sampling, Test Specimens, and Test Units9.1 Samples shall be taken in accordance with the instruc-tions in Practices D4057 or D4177 when applicable.9.2 When reusable sample cells are used, clean and dry cellsbefore
46、 each use. Disposable sample cells shall not be reused.For each sample, an unused piece of X-ray film is required forthe sample cell. Avoid touching the inside of the sample cell,the portion of the window film in the cell, or the instrumentwindow that is exposed to X-rays. Oil from fingerprints cana
47、ffect the reading when determining low levels of sulfur.Wrinkles in the film will affect the intensity of the sulfur X-raystransmitted. Therefore, it is essential that the film be taut andclean to ensure reliable results. When handling the windowfilm, avoid touching the central part (the part that a
48、ctuallyforms the optical window) as this can lead to contaminationfrom sweat, grease, or other petrochemical products. Similarly,discard any film that has been exposed to the atmosphere (forexample, hanging outside of the film roll dispensing box).Also, when opening a new roll of film, discard the f
49、irst metre,since some films are packaged in plastic bags that containsulfur. The analyzer may need recalibration if the type orthickness of the window film is changed. After the sample cellis filled, make a small vent hole in the lid of the sample cell.Place the sample in the cell using techniques consistent withgood practice for the particular instrument being used. Al-though sulfur radiation will emerge from only a small distanceinto the sample, scatter from the sample cell and the samplecan vary. Laboratory personnel shall ensure that
