1、Designation: D6334 12 (Reapproved 2017)Standard Test Method forSulfur in Gasoline by Wavelength Dispersive X-RayFluorescence1This standard is issued under the fixed designation D6334; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 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 covers the quantitative determinationof total sulfur in gasoline and gasoline-oxygenate
3、blends. ThePooled Limit of Quantitation (PLOQ) was determined to be15 mgkg. Therefore, the practical range for this test method isfrom 15 mgkg to 940 mgkg.NOTE 1This concentration range is based on that used in theinterlaboratory round robin, which shows that the range of sulfur in theround robin sa
4、mples was from 1.5 mg kg to 940 mg kg; however, below15 mg kg, the reproducibility approaches 100 % of the concentration.1.2 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-p
5、riate safety and health practices and determine the applica-bility of regulatory limitation prior to use.1.3 The values stated in SI units are to be regarded as thestandard. The preferred units are mg/kg sulfur.1.4 This international standard was developed in accor-dance with internationally recogni
6、zed principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D2622 Test Method for S
7、ulfur in Petroleum Products byWavelength Dispersive X-ray Fluorescence SpectrometryD3210 Test Method for Comparing Colors of Films fromWater-Emulsion Floor PolishesD4045 Test Method for Sulfur in Petroleum Products byHydrogenolysis and Rateometric ColorimetryD4057 Practice for Manual Sampling of Pet
8、roleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD4294 Test Method for Sulfur in Petroleum and PetroleumProducts by Energy Dispersive X-ray Fluorescence Spec-trometryD5453 Test Method for Determination of Total Sulfur inLight Hydrocarbons, Spark Ign
9、ition Engine Fuel, DieselEngine Fuel, and Engine Oil by Ultraviolet FluorescenceD5842 Practice for Sampling and Handling of Fuels forVolatility MeasurementD5854 Practice for Mixing and Handling of Liquid Samplesof Petroleum and Petroleum ProductsD6299 Practice for Applying Statistical Quality Assura
10、nceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD6792 Practice for Quality Management Systems in Petro-leum Products, Liquid Fuels, and Lubricants TestingLaboratories3. Summary of Test Method3.1 The sample is placed in the X-ray beam, and theintensity of the su
11、lfur K line at 5.373 is measured. Theintensity of a corrected background, measured at a recom-mended wavelength of 5.190 , or if a rhodium tube is used,5.437 , is subtracted from this intensity. The resultant netcounting rate is then compared to a previously preparedcalibration curve or equation to
12、obtain the concentration ofsulfur in mg/kg. (WarningExposure to excessive quantitiesof X radiation is injurious to health. Therefore, it is imperativethat the operator avoid exposing any part of his or her person,not only to primary X-rays, but also to secondary or scatteredradiation that might be p
13、resent. The X-ray spectrometer shouldbe operated in accordance with the regulations of recommen-dations governing the use of ionizing radiation.)4. Significance and Use4.1 Knowledge of the presence of sulfur in petroleumproducts, especially fuels, helps predict performancecharacteristics, potential
14、corrosion problems, and vehicle emis-sion levels. In addition, some regulatory agencies mandatereduced levels of sulfur in reformulated type gasolines.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility
15、 ofSubcommittee D02.03 on Elemental Analysis.Current edition approved May 1, 2017. Published July 2017. Originally approvedin 1962. Last previous edition approved in 2012 as D6334 12. DOI: 10.1520/D6334-12R17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custom
16、er Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document 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 develop
17、ed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15. Interferences5.1 F
18、uels with compositions that vary from those specifiedin 9.1 may be analyzed with standards made from basematerials that are of similar composition to minimize matrixeffects.5.1.1 Fuels containing oxygenates may be analyzed usingstandards prepared with similar amounts of the same oxygenateadded to th
19、e standard dilution matrix. However, round robinstudies done by the Western States PetroleumAssociation haveshown no significant bias in determining sulfur in gasolineswith and without oxygenates at regulatory levels (0 to 2.7weight percent oxygen).5.1.2 Methanol fuels (M85 and M100) exhibit interfe
20、rencesat this level of detection (100 mgkg). They can be analyzedusing a calibration curve produced by diluting the standards ina similar matrix of M85 or M100 or by Test Method D2622.6. Apparatus6.1 Wavelength Dispersive X-Ray Fluorescence Spectrom-eter (WDXRF), equipped for soft ray detection in t
21、he 5.37 range. For optimum sensitivity to sulfur, equip the instrumentwith the following:6.1.1 Optical Path, of helium.6.1.2 Pulse-Height Analyzer, or other means of energydiscrimination.6.1.3 Detector, designed for the detection of long wave-length X-rays.6.1.4 Analyzing Crystal, suitable for the d
22、ispersion of sulfurK X-rays within the angular range of the spectrometeremployed. Pentaerythritol and germanium are the mostpopular, although materials, such as EDDT,ADP, graphite, andquartz, may be used.6.1.5 X-Ray Tube, capable of exciting sulfur Kradiation.Tubes with anodes of rhodium, chromium,
23、and scandium aremost popular, although other anodes may be suitable.7. Reagents7.1 Di-n-Butyl Sulfide (MW 146.30), a high-purity gradestandard with a certified sulfur analysis.7.2 Thiophene MW 84.14), a high-purity (98+ %) gradestandard with a certified sulfur analysis.7.3 2-Methylthiophene MW 98.17
24、), a high purity (98+ %)grade standard with a standard sulfur analysis.7.4 2,2,4-Trimethylpentane, (isooctane), reagent grade,MW-114.23.7.5 Methylbenzene, (Toluene), reagent grade, MW-92.14.7.6 Drift Correction Monitor(s), (Optional), several differ-ent materials have been found to be suitable for u
25、se as driftcorrection monitors. Examples of sulfur containing materialsthat meet these requirements are renewable liquid petroleummaterials, semipermanent solids, pressed powder pellets, metalalloys, or fused glass disks. Bracket the calibration range withconcentrations of monitor samples. The count
26、ing rate for eachmonitor is determined during calibration (see 9.7) and again atthe time of analysis (see 10.1). These counting rates are used tocalculate a drift correction factor (see 11.1).7.7 Calibration Check Standards, one or more liquid petro-leum or product standards of known sulfur content
27、(which donot represent one of the samples prepared in Section 9) areused to verify the accuracy of the calibration curve.7.8 Quality Control (QC) Sample, one or more stable liquidpetroleum or product samples, which are used to verify that themeasurement system is in control. Preferably the QC sample
28、(s)should be representative of the samples typically analyzed. Incases where volatility of the QC sample(s) may affect thesample integrity, precautions need to be taken to minimize oreliminate sample losses prior to analysis to ensure that a stableand representative sample can be taken and analyzed
29、over theperiod of intended use. It is permissible to use calibrationstandards for this purpose. Since standard samples are dis-carded after each determination, it is recommended that alower cost material be used for daily calibration checks.8. Sampling and Specimen Preparation8.1 Samples shall be ta
30、ken in accordance with the instruc-tions in Practice D4057, D4177, D5842,orD5854, whereappropriate.8.2 Clean and dry reusable cells before use. Disposablesample cups are not to be reused. Window material usually is8 m polyester, 8 m polycarbonate, or 6 m polypropylenefilm. Renewal of the window of t
31、he sample cup is essential forthe measurement of each sample. Avoid touching the inside ofthe sample cup, the portion of the window film in the cup, orthe instrument window that is exposed to X-rays. Oil fromfingerprints can affect the reading when analyzing for lowlevels of sulfur. Wrinkles in the
32、film will affect the number ofsulfur X-rays transmitted. Therefore, the importance of thefilms tautness and cleanliness cannot be over stressed. Reca-librate the analyzer when you change the type or thickness ofthe window film.8.3 Polyester films often contain impurities that may affectthe measureme
33、nt of low levels of sulfur and may vary from lotto lot. Therefore, if using a polyester film, check the calibrationwith the start of each new roll.8.4 X-ray films may vary in thickness from batch to batch.Check the calibration when starting a new roll of any film.8.5 Samples of high aromatic count m
34、ay dissolve polyesterand polycarbonate films. In these cases, other materials besidesthese films may be used for X-ray windows, provided that theydo not contain any elemental impurities that can adverselyaffect the results obtained by this test method.9. Calibration9.1 Prepare calibration standards
35、by the careful preparationby mass of a 50:50 mixture (based on sulfur content) of thecertified thiophene and 2-methylthiophene or n-butyl sulfidewith 20 % to 80 % mixture of tolueneisooctane or othersuitable base material (see 5.1). Exact standards of the nominalsulfur concentrations listed in Table
36、 1 are recommended.9.2 Preparation of Stock Standard: Weigh approximately0.657 g of thiophene and 0.767 g of 2-methylthiophene andrecord the masses to the nearest 0.1 mg, or weigh 2.286 ofD6334 12 (2017)2n-butyl sulfide to the nearest 0.1 mg. Add the standardmaterials to a tared 100 mL volumetric fl
37、ask. Add mixedsolvent of 20 % toluene and 80 % isooctane (by volume) orother base material (see 5.1) to a net mass of 50.000 g +0.010 g. This stock standard contains approximately 10 mggsulfur. Correct the concentration by multiplying the measuredmasses by the sulfur equivalency in each of the stand
38、ards, thatis thiophene grams 0.3803 purity plus 2-methylthiophenegrams 0.3260 purity (or n-butyl sulfide grams 0.2191 purity) = weight of sulfur in the standard solution. Divide thisnumber by the total mass of the standards and base materialadded to them, multiply by 1000 mg/g and the result is thea
39、ctual sulfur concentration in mg/g. This calculation is asfollows:S, mg/g 5 1000 3T 30.3803 3P1M 30.3260 3PF(1)S, mg/g 5 1000 3DB 30.2187 3PF(2)where:S = final sulfur concentration,T = mass of thiophene added,M = mass of 2-methylthiophene added,DB = mass of di- n-butyl sulfide added,P = purity of th
40、e standard material, andF = final mass of mixture.9.3 Preparation of Diluted Standard: Dilute 25.0 mL ofstock standard to 250 mL using the base material. This gives astandard of approximately 1000 mgkg. Divide the standardconcentration calculated in 9.2 by 10 to determine the actualconcentration.9.4
41、 Serial Dilutions: Prepare serial dilutions of the dilutedstandard by diluting the following volumes to 100 mL usingthe base material:0.5 mL = 5 mg/kg1.0 mL = 10 mg/kg5.0 mL = 50 mg/kg10.0 mL = 100 mg/kg25.0 mL = 250 mg/kg50.0 mL = 500 mg/kgDiluted Standard = 1000 mg/kgNOTE 2Prepare calibrations up
42、to 1000 mg kg sulfur, and dilutesamples with higher concentrations of sulfur to within this concentrationrange.9.5 Establish calibration curve data by carefully measuringthe net intensity of the emitted sulfur radiation from each of thestandards by the procedure described in Sections 10 and 11.9.6 C
43、onstruct a calibration model by:9.6.1 Using the software and algorithms supplied by theinstrument manufacturer.9.6.2 Fitting the data to an equation of the type:S 5 aR1b (3)where:S = sulfur concentration, mg/kg,R = net intensity for the sulfur radiation,a = slope of the calibration curve, andb = int
44、ercept of the calibration curve.9.6.3 Plot corrected net intensity in counts per second (cps)versus sulfur concentration. Plot data in two ranges listed inTable 1.9.7 During collection of calibration data, measure the inten-sity of the drift monitor standards. Use the intensities fromthese standards
45、 to correct for day to day instrument sensitivity.This value corresponds to A in Eq 5, Section 11. Manyinstrument manufacturers have built drift correction proceduresinto their software.9.8 At the completion of the calibration, measure one ormore independent calibration check standards to verify the
46、accuracy of the calibration curve. These standards (see 7.7) areindependent of the calibration set. The measured value shallagree with the standard value within 62 % relative or 2 ppm,whichever is greater.NOTE 3NIST traceable gasoline standards are available at the1 mg kg, 10 mg kg, 40 mg kg, and 30
47、0 mg kg levels. Other concentra-tions may be prepared by dilution of these standards with a solvent ofsimilar matrix to the standards previously prepared.NOTE 4NIST has suggested a “designer” method for the preparationof NIST traceable fossil fuel standards with concentrations intermediate toSRM val
48、ues for sulfur. Laboratories can mix and prepare standards fordistillate fuels oils, residual fuel oil in almost any desired concentrationswith uncertainties that are calculable and traceable to NIST-certifiedvalues. This method enables the SRM user to create a customized seriesof calibration and qu
49、ality control test samples.3NOTE 5A DVD available from NIST includes the above cited paperplus subsequent papers dealing with this subject as well as programmablespreadsheet to calculate blend concentrations and uncertainties. Some ofthe subsequent papers discuss the actual procedure to use when mixingrather than the proof of concept given in the first paper.410. Procedure10.1 Measure the intensity of the drift correction monitor(s)used in 9.7. The value determined corresponds to B in Eq 5,Section 11. This measurement may not be requi
