1、Designation:D722006 Designation: D7220 12Standard Test Method forSulfur in Automotive Fuels by Polarization X-rayFluorescence SpectrometrySulfur in Automotive, Heating,and Jet Fuels by Monochromatic Energy Dispersive X-rayFluorescence Spectrometry1This standard is issued under the fixed designation
2、D7220; the number immediately following the designation indicates the year 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 reapp
3、roval.1. Scope1.1This test method specifies an energy-dispersive X-ray fluorescence (EDXRF) method for the determination of total sulfur inautomotive fuels with a concentration range of 6 mg/kg to 50 mg/kg.1.1.1The pooled limit of quantitation of this test method as obtained by statistical analysis
4、of inter laboratory test results is6mg/kg sulfur.1.1 This test method specifies an energy-dispersive X-ray fluorescence (EDXRF) method for the determination of total sulfurin automotive, No. 2 heating, and jet fuels with a concentration range of 3 to 942 mg/kg.1.1.1 The pooled limit of quantitation
5、of this test method as obtained by statistical analysis of inter laboratory test results is3 mg/kg sulfur.1.1.2 This test method is applicable to gasoline, oxygen enriched gasoline (RFG), diesel, diesel/biodiesel blends containing upto twenty volume percent biodiesel, kerosene, jet fuel, jet fuel/bi
6、odiesel blends containing up to five volume percent biodiesel andNo. 2 home heating oil.1.2 A fundamental assumption in this test method is that the standard and sample matrix is well matched. Matrix mismatch canbe caused by C/H ratio differences between samples and standards or by the presence of o
7、ther heteroatoms.1.3The values stated in SI units are to be regarded as the standard. The preferred concentration units are mg/kg sulfur.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3.1 The preferred concentration uni
8、ts are mg/kg sulfur.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to u
9、se.1This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.03 onElemental Analysis.Current edition approved Feb. 15, 2006. Published March 2006. DOI: 10.1520/D7220-06.Current edition approved Jan. 15,
10、 2012. Published March 2012. Originally approved in 2006. Last previous edition approved in 2006 as D722006. DOI:10.1520/D7220-12.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version.
11、Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 1
12、00 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2. Referenced Documents2.1 ASTM Standards:2D4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsD4177 Practice for Automatic Sampling of Petroleum and Petroleum ProductsD6299 Practice for Applying Sta
13、tistical Quality Assurance and Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD6300 Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and LubricantsE29 Practice for Using Significant Digits in Test Data to Determine
14、Conformance with Specifications2.2 ISO Standard:ISO 4259Determination and application of precision data in relation to methods of test3. Terminology3.1 Definitions:3.1.1 polarization X-ray fluorescencemonochromatic X-radiation, ntypically a polarization EDXRF instrument is used. Indifference to dire
15、ct excitation EDXRF spectrometry, polarization X-ray fluorescence uses polarized radiation for excitation.Combined with Cartesian geometry (of excitation, sample and detection system) this results in a significant improvement of thedetection limit compared to direct excitation EDXRF. an incident X-r
16、ay beam on a sample having a selected photon energy witha narrow energy bandwidth of 65% relative to the selected energy.3.1.1.1 DiscussionMonochromatic X-ray radiation in EDXRF instrumentation can be obtained by using Bragg optics (at anangle of=456 5, in the low energy range). Bragg optics (monoch
17、romators) create very intense mono-energetic radiation. Acombination of a selected X-ray tube (typically a Pd or Ag anode) with a highly ordered pyrolytic graphite (HOPG) Bragg opticcan be used to create monochromatic radiation of the characteristic radiation of the anode material of the X-ray tube.
18、 The use ofsuch radiation for sample excitation results in increased sensitivity for the determination of sulfur in petroleum products.3.2 Abbreviations:3.2.1 DBSactual mass of Di-n-butyl sulfide, g3.2.2 Kcpskilo-counts per second.3.2.3 EDXRFEnergy dispersive X-ray spectrometry3.2.33.2.4 PTFEPolytet
19、rafluorethylene3.2.43.2.5 SDBSmass % of sulfur in Di-n-butyl sulfide, typically 21.91%3.2.53.2.6 SStdmg/kg sulfur in the calibration standard3.2.63.2.7 SStockmg/kg of sulfur in the stock standard3.2.73.2.8 STKactual mass of stock standard, g4. Summary of Test Method4.1 The sample is placed in the po
20、larizedmonochromatic X-ray beam, and the peak area of the sulfur Ka line at 2.307 keV ismeasured. The background spectrum, measured with a sulfur free white oil or other matrix matching blank sample (see 8.4) isadapted to the measured spectrum using adjustment regions following the instrument manufa
21、cturers instructions and thensubtracted from the measured spectrum. The resultant net counting rate is then compared to a previously prepared calibration curveor equation to obtain the concentration of sulfur in mg/kg. (WarningExposure to excessive quantities of X-radiation is injuriousto health. Th
22、e operator needs to take appropriate actions to avoid exposing any part of their body, not only to primary X-rays, butalso to secondary or scattered radiation that might be present. The X-ray spectrometer should be operated in accordance with theregulations governing the use of ionizing radiation.)5
23、. Significance and Use5.1 This test method provides measurement of total sulfur in automotive, No. 2 heating, and jet fuels with a minimum of samplepreparation. A typical analysis time is 200180 to 300360 s per sample.5.2 The quality of automotive, No. 2 heating, and jet fuel can be related to the a
24、mount of sulfur present. Knowledge of sulfurconcentration is necessary for processing purposes. There are also regulations promulgated in federal, state, and local agencies thatrestrict the amount of sulfur present in some fuel.5.3 If this test method is applied to petroleum materials with matrices
25、significantly different from the calibration materialsspecified in this test method, the cautions and recommendations in Section 6 should be observed when interpreting the results.2For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.or
26、g. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.D7220 1226. Interferences6.1 When the elemental composition (excluding sulfur) of samples differs significantly from the standards, errors in the sulfurdetermination can result. F
27、or example, differences in the carbon-hydrogen ratio of sample and calibration standards introduceerrors in the determination.6.2 M-85 and M-100 are fuels containing 85 and 100 % methanol, respectively. They have a high oxygen content leading tosignificant absorption of sulfur Ka radiation. Such fue
28、ls can, however, be analyzed using this test method provided either thatcorrection factors are applied to the results (when calibrating with white oils) or that the calibration standards are prepared to matchthe matrix of the sample.6.3 In general, petroleum materials with compositions that vary fro
29、m the calibration samples as specified in Section 11 can beanalyzed with standards made from base materials that are of the same or similar composition. Thus a gasoline may be simulatedby mixing isooctane and toluene in a ratio that approximates the expected aromatic content of the samples to be ana
30、lyzed.Standards made from this simulated gasoline can produce results that are more accurate than results obtained using white oilstandards.7. Apparatus7.1 PolarizationMonochromatic X-ray Fluorescence AnalyzerAPolarizedMonochromatic Excitation Energy Dispersive XRFspectrometer may be used if its des
31、ign incorporates as a minimum, the following features:7.1.1 Source of X-ray Excitation , X-ray end window tube with Pd or Rh anode and Beryllium window, in combination withpolarizing X-ray optics. The polarizer must polarize Pd or Rh La radiation. , X-ray end window tube with Ag or Pd anode, incombi
32、nation with HOPG Bragg monochromating X-ray optics. The monochromator must produce monochromatic Ag or Pd Lradiation. Other anode materials and monochromators may be utilized, however stated precision and bias may not apply.7.1.2 Sample Cell, providing a sample depth of at least 4 mm and equipped wi
33、th replaceable X-ray transparent film window.7.1.3 X-ray Detector, with a resolution value not to exceed 175 eV at 5.9 keV (10.000cps).Kcps (10 000 cps).ASi drift chamberhas been found suitable for use. Using a detection system with this minimum spectral resolution has been shown to eliminate thepot
34、ential effect of interference from chlorine on sulfur should either salt contamination, or chlorine from other sources (forexample, recycled vegetable oils) occur.7.1.4 He-flush, the system must allow flushing of the optical path with helium (see 8.6). ). Alternatively, a vacuum of#4.0 kPa(# 30.4 To
35、rr) is applied to the optical path.7.1.5 Signal Conditioning and Data Handling Electronics, including the functions of X-ray intensity counting, spectra handlingby background subtraction and deconvolution, calculation of overlap corrections and conversion of sulfur X-ray intensity intomg/kg sulfur c
36、oncentration.8. Reagents and Materials8.1 Purity of Reagents3Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where suchspecifications
37、 are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purityto permit its use without lessening the accuracy of the determination.8.2 Di-n-butyl Sulfidea high-purity standard with a certified analysis for sulfur content. Use the certified
38、 sulfur content whencalculating the exact concentrations of the calibration standards (see 11.1). (WarningDi- n-butyl sulfide is both flammable andtoxic.)NOTE 1It is essential to know the concentration of sulfur in the di-n-butyl sulfide, not the purity, since impurities may also be sulfur containin
39、gcompounds.8.3 Drift Correction Monitor(s) (Optional)Several different materials have been found to be suitable for use as drift correctionmonitors. Examples of sulfur containing materials that have been found to be suitable include a renewable liquid petroleummaterial or a fused glass disk. The mon
40、itors count rate, in combination with count time, shall be sufficient to give a relativecounting error of less than 1 %. The count rate for the monitor sample is determined during calibration (see 11.4) and again at thetime of analysis (see 12.1). These counting rates are used to calculate a drift c
41、orrection factor (see 13.1).8.3.1 Drift correction is usually implemented automatically in software, although the calculation can readily be done manually.For X-ray instruments that are highly stable, the magnitude of the drift correction factor may not differ significantly from unity.8.4 White Oil
42、(Light Paraffn Oil) or Matrix-Matching Blank Sample, with a certified content of less than 0.2 mg/kg sulfur. Ifonly one matrix is to be analyzed (for example, diesel) accuracy of results may be improved by using a matrix matched diluent.In these cases, the matrix matched diluent should match approxi
43、mately the C/H ratio and oxygen content of the material to beanalyzed.3Available from International Organization for Standardization (ISO), 1, rue de Varemb, Case postale 56 CH-1211 Geneva 20, Switzerland.3Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washin
44、gton, DC. For Suggestions on the testing of reagents not listed bythe American Chemical Society, see Annual Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D7220 123
45、8.5 X-ray Transparent FilmAny film that resists attack by the sample, is free of sulfur, and is sufficiently X-ray transparentcan be used, with film thickness of between 2 to 6 m. Films can include polyester, polypropylene, polycarbonate, and polyimide.Typically polycarbonate with a thickness of 5 t
46、o 6 m is used. However, samples of high aromatic content can dissolve polyesterand polycarbonate films. It is important that samples, standards, and blanks be measured using the same batch of film to avoid bias.8.6 Helium Gas, minimum purity 99.9 %.8.7 Sample Cells, compatible with the sample and th
47、e geometry requirements of the spectrometer. Disposable cells arerecommended.8.8 Calibration Check Samples, portions of one or more liquid petroleum or product standards of known sulfur content and notused in the generation of the calibration curve. The check samples shall be used to determine the a
48、ccuracy of the initial calibration(see 11.5).8.9 Quality Control Samples, stable petroleum or product samples representative of the samples of interest that are run on aregular basis to verify that the system is in statistical control.NOTE 2Verification of system control through the use of QC sample
49、s and control charting is highly recommended. It is recognized that QCprocedures are the province of the individual laboratory. Suitable QC samples 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 instructions in Practices D4057 or D4177 when applicable.9.2 When reusable sample cells are used, clean and dry cells before each use. Disposable sample cells shall not be reused. Foreach sample, an unused piece of X-ray film is required for the sample cel
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