1、Designation: D 7220 06An American National StandardStandard Test Method forSulfur in Automotive Fuels by Polarization X-rayFluorescence Spectrometry1This standard is issued under the fixed designation D 7220; the number immediately following the designation indicates the year oforiginal adoption or,
2、 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.1. Scope1.1 This test method specifies an energy-dispersive X-rayfluorescence (EDXRF) metho
3、d for the determination of totalsulfur in automotive fuels with a concentration range of 6mg/kg to 50 mg/kg.1.1.1 The pooled limit of quantitation of this test method asobtained by statistical analysis of inter laboratory test results is6 mg/kg sulfur.1.2 A fundamental assumption in this test method
4、 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 as thestandard. The preferred concentration units are mg/kg sulfur.1
5、.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 practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Do
6、cuments2.1 ASTM Standards:2D 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD 6299 Practice for Applying Statistical Quality AssuranceTechniques to Evaluate Analytical Measurement SystemPerformanceE29 Pract
7、ice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 ISO Standard:3ISO 4259 Determination and application of precision datain relation to methods of test3. Terminology3.1 Definitions:3.1.1 polarization X-ray fluorescence, ntypically a polar-ization EDXRF instr
8、ument is used. In difference to directexcitation EDXRF spectrometry, polarization X-ray fluores-cence uses polarized radiation for excitation. Combined withCartesian geometry (of excitation, sample and detection sys-tem) this results in a significant improvement of the detectionlimit compared to dir
9、ect excitation EDXRF.43.2 Abbreviations:3.2.1 DBSactual mass of Di-n-butyl sulfide, g3.2.2 EDXRFEnergy dispersive X-ray spectrometry3.2.3 PTFEPolytetrafluorethylene3.2.4 SDBSmass % of sulfur in Di-n-butyl sulfide, typi-cally 21.91%3.2.5 SStdmg/kg sulfur in the calibration standard3.2.6 SStockmg/kg o
10、f sulfur in the stock standard3.2.7 STKactual mass of stock standard, g4. Summary of Test Method4.1 The sample is placed in the polarized X-ray beam, andthe peak area of the sulfur Ka line at 2.307 keV is measured.The background spectrum, measured with a sulfur free whiteoil or other matrix matching
11、 blank sample (see 8.4) is adaptedto the measured spectrum using adjustment regions followingthe instrument manufacturers instructions and then subtractedfrom the measured spectrum. The resultant net counting rate isthen compared to a previously prepared calibration curve orequation to obtain the co
12、ncentration of sulfur in mg/kg.(WarningExposure to excessive quantities of X-radiation isinjurious to health. The operator needs to take appropriateactions to avoid exposing any part of their body, not only toprimary X-rays, but also to secondary or scattered radiationthat might be present. The X-ra
13、y spectrometer should be1This 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 Feb. 15, 2006. Published March 2006.2For referenced ASTM standards, visi
14、t the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from International Organization for Standardization (ISO), 1, rue deVaremb, Case posta
15、le 56 CH-1211 Geneva 20, Switzerland.4Wissmann, D., “Latest Improvements on Using Polarized X-Ray ExcitationEDXRF for the Analysis of Low Sulfur Content in Automotive Fuel,” Journal ofASTM International, Vol 2, Issue 9, Paper ID JAI12975, October 2005. Visit theASTM website, www.astm.org, Books beyo
16、ndwhich additional sample does not significantly affect the countrate. Generally, fill the sample cell to a minimum of three-fourths of the cells capacity. Make a small vent hole in the lidof the sample cell.12.3 Place the sample in the instrument, and performmeasurement according to instrument manu
17、facturers instruc-tions.12.4 Determine the peak area of the sulfur Ka radiation at2.307 keV. The net count-rate will be calculated by subtractingthe background. The background spectrum, measured with asulfur-free white oil or other matrix matching blank sample(see 8.4) is adapted to the measured spe
18、ctrum using adjustmentregions following the instrument manufacturers instructionsand then subtracted from the measured spectrum.NOTE 5When using a Pd target X-ray tube, background adjustmentregions at 2.86-2.92 keV and 2.95-3.04keV have been found suitable.12.5 Determine the corrected counting rate
19、and calculate theconcentration of the sample as described in Section 13.NOTE 6It is recommended to prepare and analyze each sampledirectly. Also, it is recommended to take care not to leave the test samplein the instrument after the measurement process has finished. If thespectrometer is equipped wi
20、th an autosampler, it is recommended to useonly one position of the autosampler. This minimizes the risks of samplecell leakage, or deformation, or both.13. Calculation or Interpretation of Results13.1 When using the drift correction monitor described in8.3, calculate a correction factor for changes
21、 in daily instru-ment sensitivity as follows:F 5 A 4 B (4)where:A = counting rate of the drift correction monitor as deter-mined at the time of calibration (see 11.4), andB = counting rate of the drift correction monitor as deter-mined at the time of analysis (see 12.1).13.2 The net counting rate is
22、 given by the spectral decon-volution of the sulfur Ka line after subtracting the backgroundspectrum.13.2.1 The use of the factor F to correct the counting rate ofsulfur is optional.13.3 Calculate the sulfur content of the sample by insertingthe corrected net counting rate in the chosen calibration
23、modelfrom Section 11. In many cases the instrument vendor willprovide software or the required calculations.14. Report14.1 For all samples analyzed, report the result calculated in13.3. Report the result as the total sulfur content in mg/kgrounding to two significant figures up to 10 mg/kg and to th
24、reeTABLE 2 Nominal Calibration StandardsSulfur Content,mg/kgMass of White Oil orMatrix-Matching Blank,gMass ofStock Standard,g0 100.0 0.05 99.8 0.210 99.6 0.430 98.8 1.250 98.0 2.060 97.6 2.4D7220064significant figures for results greater or equal 10 mg/kg usingPractice E29. State that the results w
25、ere obtained in accor-dance with Test Method D 7220.15. Precision and Bias15.1 The precision and bias of the test method, as deter-mined by statistical examination of interlaboratory test results,7was determined according to ISO 4259. One certified dieselsample, LGC 3023,8was supplied as check sampl
26、e. Anothercertified diesel sample, LGC 3021,8was provided as a testsample (result not supplied) to determine the bias of the testmethod.15.2 The precision of the test method is as follows:15.2.1 RepeatabilityThe difference between successivetest results obtained by the same operator with the sameapp
27、aratus under constant operation conditions on identical testmaterial would, in the long run, in the normal and correctoperation of the test method, exceed the value:1.0348 X0.25mg/kg (5)where:X = the mean sulfur content, only in one case in twenty.(See Table 3.)15.2.2 ReproducibilityThe difference b
28、etween two singleand independent results obtained by different operators work-ing in different laboratories on identical test material would, inthe long run, in the normal and correct operation of the testmethod, exceed the value:2.0591 X0.25mg/kg (6)where:X = the mean sulfur content, only in one ca
29、se in twenty.(See Table 4.)15.3 BiasA certified diesel sample LGC 30218was pro-vided as a test sample (result not supplied). Subsequentstatistical evaluation showed no apparent bias with the follow-ing results:Sample Certified Value, mg/kg S ILS Result, mg/kgLGC 3021 11.00 6 0.50 11.1 6 1.316. Keywo
30、rds16.1 automotive fuel; diesel; gasoline; petroleum; polariza-tion; spectrometry; sulfur; X-rayAPPENDIX(Nonmandatory Information)X1. QUALITY CONTROL INFORMATIONX1.1 The performance of the instrument or test procedureshould be confirmed by analyzing quality control (QC)samples.X1.1.1 As part of the
31、QC procedure, a portion of the whitemineral oil used to make up the calibration standards should beanalyzed in order to confirm the instrument blank value has notchanged since the initial calibration.X1.2 Prior to routine use of this test method, the usershould determine the average value and contro
32、l limits of theQC samples. See Practice D 6299 and MNL 7.9X1.3 The QC results should be recorded and monitored bycontrol charts or other statistically equivalent techniques todetermine the statistical control status of the total testingprocess. See Practice D 6299 and MNL 7.9X1.4 The frequency of co
33、ntrol testing is dependent on thecriticality of the quality being measured, the demonstratedstability of the testing process, and customer requirements.Generally, a QC sample should be analyzed each testing daywith routine samples. The QC frequency should be increased ifa large number of samples are
34、 routinely analyzed. However,when it is demonstrated that the testing is under statisticalcontrol, the QC testing frequency may be reduced. The QCsample testing precision should be periodically checked againstthe ASTM method precision to ensure data quality. SeePractice D 6299 and MNL 7.9X1.5 It is
35、recommended that, if possible, the type of QC7Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D02-1592.8Supplied by LGC Promochem, Queens Road, Teddington, Middlesex, TW110LY, United Kingdom.9MNL 7, Manual on Presentation of Dat
36、a Control Chart Analysis, 6th Edition,ASTM International, W. Conshohocken, PA.TABLE 3 Repeatability for Selected DifferentSulfur ConcentrationsSulfur Content,mg/kgRepeatability,mg/kg10 1.830 2.450 2.8TABLE 4 Reproducibility for Selected DifferentSulfur ConcentrationsSulfur Content,mg/kgReproducibili
37、ty,mg/kg10 3.730 4.850 5.5D7220065sample that is regularly tested be representative of the materialroutinely analyzed. An ample supply of QC sample materialshould be available for the intended period of use, and must behomogeneous and stable under anticipated storage conditions.ASTM International ta
38、kes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own r
39、esponsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addre
40、ssed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at t
41、he address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D7220066
