1、Designation: D 7041 04An American National StandardStandard Test Method forDetermination of Total Sulfur in Light Hydrocarbons, MotorFuels, and Oils by Online Gas Chromatography with FlamePhotometric Detection1This standard is issued under the fixed designation D 7041; the number immediately followi
2、ng 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method c
3、overs the determination of total sulfurin liquid hydrocarbons with a final boiling point less than450C by gas chromatography using a flame photometricdetector.1.2 This test method is applicable for total sulfur levels from0.5 to 100 mg S/kg.NOTE 1The pooled limit of quantification (PLOQ) derived fro
4、m the2002 interlaboratory cooperative test program was determined to be 1mgS/kg.NOTE 2Samples can also be tested at other total sulfur levels, but theprecision statements may not apply.1.3 The values stated in SI units are to be regarded asstandard.1.4 This standard does not purport to address all o
5、f 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. For specific hazardstatements see Section 7.2. Referenced Documen
6、ts2.1 ASTM Standards:2D 1298 Test Method for Density, Relative Density (SpecificGravity), or API Gravity of Crude Petroleum and LiquidPetroleum Products by Hydrometer MethodD 4052 Test Method for Density and Relative Density ofLiquids by Digital Density MeterD 4057 Practice for Manual Sampling of Pe
7、troleum Prod-uctsD 4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsE 840 Practice for Using Flame Photometric Detectors inGas Chromatography3. Summary of Test Method3.1 The sample is analyzed by gas chromatography with aflame photometric detector. A fixed amount of sample isin
8、jected into the gas chromatograph where it is vaporized. Theair carrier stream carries the vaporized sample into a hightemperature zone (900C) where the compounds present inthe sample are oxidized. Sulfur compounds are converted tosulfur dioxide (SO2). The carrier stream carries the oxidationcompone
9、nts onto a chromatographic column where they areseparated and the SO2is quantified by the flame photometricdetector. Calibration of the detector is achieved by the use of anappropriate external standard.4. Significance and Use4.1 This test method can be used to determine total sulfurlevels in proces
10、s feeds and finished products that fall within thescope of this test method.4.2 Low levels of sulfur in process feed stocks can poisonexpensive catalysts used in petroleum refining processes. Thistest method can be used to monitor sulfur levels in thesefeedstocks.5. Apparatus5.1 Gas Chromatograph, e
11、quipped with automatically con-trolled valves, capable of automatic calibration with an exter-nal standard and having a flame photometric detector with anoverall sensitivity to detect at least 0.5 mg/kg of SO2. It mustbe able to automatically control all valve switching times.Although originally dev
12、eloped with online analytical measure-ment equipment in an offline mode of operation, suitable onlineor laboratory gas chromatographs may apply this test methodas described. Typical instrument parameters are listed in Table1.5.1.1 Carrier and Detector Gas ControlThe chromato-graph must be equipped w
13、ith flow controllers or pressurecontrollers capable of maintaining a constant supply of carrier1This 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 J
14、uly 1, 2004. Published July 2004.2For 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 Document Summary page onthe ASTM website.1Copyright ASTM Internationa
15、l, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.gas and detector supply gases. Electronic pressure or flowcontrol is highly recommended.5.1.2 Sample Injection SystemAn automatic sample injec-tion device is required. The injector must allow the introduc-tion of
16、small sample sizes (0.1 to 1 L). The sample must beaccurately and repeatably injected into the gas chromatograph.Rotary or stem type liquid injection valves or auto injectors arerecommended. The valve or injector must be equipped with aheated vaporizer section capable of being heated to at least285C
17、.5.2 Pyrolysis FurnaceA furnace capable of maintaining asufficient temperature (900C) to pyrolyze the entire sampleand oxidize the sulfur compounds to SO2.5.3 Quartz Combustion TubeQuartz tube capable of with-standing temperatures up to 1200C. The oxidation sectionshall be large enough to ensure com
18、plete oxidation of thesample.5.4 ColumnA column that can provide complete separa-tion of SO2from the CO2quench and the other oxidizedcomponents such as H2O.5.5 DetectorAny flame photometric detector (FPD) canbe used, provided it can detect a minimum peak height twicethat of the baseline noise fora1L
19、injection of a 0.5 mg S/kgstandard. Detector linearity shall be at least equal to or greaterthan 103. The user is referred to Practice E 840 for assistancein optimizing the operation and performance of the FPD.5.6 Data Acquisition SystemUse any integrator or com-puterized data acquisition system for
20、 peak area integration, aswell as for recording the chromatographic trace. The deviceand software must have the following capabilities:5.6.1 Identification of peak by retention time.5.6.2 Calculation and use of response factors.5.6.3 External standard calibration calculation.5.6.4 Graphic presentati
21、on of the chromatogram.5.7 Analytical BalanceAny balance capable of accuratelyweighing materials to the nearest 0.01 mg.6. Reagents and Materials6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the s
22、pecifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determinati
23、on.6.2 Carrier-GasZero grade air is recommended.(WarningCompressed air is a gas under high pressure thatsupports combustion.)6.3 HydrogenChromatographic grade recommended,minimum purity 99.995 %. (WarningHydrogen is an ex-tremely flammable gas under high pressure.)6.4 Solvent (Reagent Grade)the solv
24、ent chosen should becapable of dissolving the sulfur-containing compound used toprepare the standard. The solvent of choice should have adensity similar to the samples being analyzed and it shouldhave sulfur concentrations less than the instrument detectionlimit. Mixed solvents such as an isooctane
25、/ toluene mixturecan be used to reach the desired density. (WarningSolventsused as reagents such as toluene and isooctane are flammableand may be harmful or fatal if ingested or inhaled.)6.5 Standards for Calibration and Peak IdentificationStandards are used for peak identification and retention tim
26、edetermination. Also standards of known concentrations arerequired for external standard calibration of the gas chromato-graph.6.5.1 Preparation of Stock Solution (mass/volume), 100 gS/mL (see Notes 3 and 4). Accurately weigh to the nearest 0.1mg, 0.0456 g of butyl sulfide into a suitable container
27、such asa 100 mL volumetric flask. Dilute to volume with the selectedsolvent. This stock solution can be further diluted to the desiredsulfur concentration. Other sulfur containing compounds suchas thiophene or thianaphthene can be substituted for n-butylsulfide if desired. The concentration of the s
28、tock solution canbe calculated as follows:g S/mL 5 M 3 32.06! 3 1 3 106!g/g!/100 mL 3 FW! (1)where:M = exact mass of sulfur reference compound (g), andFW = formula weight of sulfur reference compound.NOTE 3Commercial standards can be used provided they are checkedfor accuracy.NOTE 4Stock solutions w
29、ill have a shelf life of approximately 2 to 3months and should be remixed accordingly.6.5.2 Preparation of Stock Solution: (mass/mass), 100 gS/g (see Notes 3 and 4). Accurately weigh to the nearest 0.1mg, 0.0456 g of butyl sulfide into a suitable container. Add 100g (accurately weighed to the neares
30、t 0.1 g) of the selectedsolvent. This stock solution can be further diluted to the desiredsulfur concentration. Other sulfur containing compounds such3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents not
31、listed by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K. and the United States Pharmacopoeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.TABLE 1 Typical Instrument ParametersCarrier gas Zero airCarrier f
32、low rate 30 mL/minHydrogen flow rate 60 mL/minDetector Flame photometric detectorDetector temperature 120CInjector temperature 285CFurnace temperature 1000CColumn 40 ft by18 in. stainless steel tubing,12 % polyphenyl ether/1.5 % H3PO4on 40/60 Chromosorb TColumn temperature 115CD7041042as thiophene o
33、r thianaphthene can be substituted for butylsulfide if desired. The concentration of the stock solution canbe calculated as follows:mgS/kg 5 M 3 32.06! 3 1 3 106!mg/kg!/100 g 3 FW! (2)6.6 Butyl SulfideFW 146.29, 21.92 % (m/m) S.6.7 ThiopheneFW 84.14, 38.1 % (m/m) S.6.8 ThianaphtheneFW 134.20, 23.90
34、% (m/m) S.7. Hazards7.1 Consult current Occupational Safety Health Administra-tion (OSHA) regulations, supplier Material Safety Data Sheets,and local regulations for all materials used in this test method.7.2 High temperatures are used in this method; extra pre-caution should be exercised when worki
35、ng with flammablematerials near the pyrolysis furnace.8. Sampling8.1 General Requirements:8.1.1 Collect samples in accordance with Practice D 4057 orD 4177.8.1.2 To prevent the loss of volatile components, which maybe present in some samples, protect samples from excesstemperatures prior to testing.
36、 This can be done by storage in anice bath or refrigerator.8.1.3 Analyze samples as soon as possible to prevent loss ofsulfur components or contamination.8.1.4 Do not store samples in plastic containers, sincevolatile materials may diffuse through the walls of the con-tainer.8.1.5 Do not test sample
37、s stored in leaky containers. Discardand obtain a new sample if leaks in the containers are detected.9. Preparation of Apparatus9.1 Place in service in accordance with the manufacturersinstructions. Typical instrument parameters are listed in Table1.9.2 Set gas flows and temperatures to the desired
38、operatingconditions, in accordance with the manufacturers instructions.9.3 Ignite the flame photometric detector according to themanufacturers procedure.9.4 Prepare the sample introduction accessories, if required,according to the manufacturers instructions.9.5 Load a sulfur standard (see 6.5) into
39、the injection valveor auto injector and inject into the gas chromatograph. Deter-mine the retention time of the SO2peak.9.6 Set-up a chromatographic analysis method according tothe manufacturers instructions.10. Calibration10.1 Choose which type of calibration method is required(mass/volume or mass/
40、mass) and prepare a calibration standardfrom the stock solution (see 6.5.1 or 6.5.2) by volumetricdilution or mass dilution (see Note 3). The concentration of thecalibration standard should be approximately 50 % of thefull-scale concentration range of the test samples to be ana-lyzed.10.1.1 Load cal
41、ibration standard into injection valve or autoinjector.10.1.2 Inject the calibration standard into the gas chromato-graph. See Table 2 for recommended injection volumes.10.1.3 Analyze the calibration standard and obtain a chro-matogram. Calculate the relative response factor for the SO2peak:RFS5 Cn/
42、 AS! (3)where:RFS= relative response factor of SO2,Cn= sulfur concentration (mgS/kg) of the compound inthe calibration mixture, andAS= peak area of the SO2component.11. Procedure11.1 Obtain a test sample using the procedure outlined inSection 8.11.2 Sample injection volumes can range from 0.1 to 1 L
43、.Experience dictates the best sample volume. The injectionvolume must be the same as used in the calibration procedure.Typical injection volumes are listed in Table 2.11.3 Load the sample into the injection valve or autoinjector according to the manufacturers recommended proce-dure.11.4 Inject the s
44、ample into the chromatograph by startingthe chromatographic method, in accordance with the manufac-turers instructions.11.5 Record concentration reading from gas chromatograph.See Fig. 1 for a typical chromatogram.11.6 Density values needed for the calculations are to betested using Test Methods D 1
45、298, D 4052, or equivalent, atthe temperature at which the sample specimen was taken foranalysis by this test method.12. Calculation12.1 If the analyzer was calibrated on a mass/volume basisthen calculate the sulfur content of the test sample in parts permillion by mass (mg/kg) as follows:sulfur, pp
46、m g/g, mg/kg! 5 CSv/DS(4)where:CSv= concentration reading from analyzer (g/mL), andDS= density of sample (g/mL).12.1.1 If the analyzer was calibrated on a mass/mass basisthen calculate the sulfur content of the test sample in parts permillion by mass (mg/kg) as follows:sulfur, ppm mg/g, mg/kg! 5 CSm
47、!DC!/DS(5)where:CSm= concentration reading from analyzer (mg/kg),DC= density of calibration standard (g/mL), andDS= density of sample (g/mL).TABLE 2 Suggested Injection VolumeSulfur, mg/kg Sample Size, LLess than 1 0.5 to 11 to 100 up to 0.5Greater than 100 0.1 to 0.25D704104313. Report13.1 Report t
48、he total sulfur concentration in parts permillion by mass (mg/kg) to the nearest 0.1 mgS/kg.14. Precision and Bias4,514.1 PrecisionThe precision of this test method as deter-mined by statistical examination of interlaboratory test resultsare as follows:NOTE 5The following precision data were develop
49、ed in a 2002interlaboratory cooperative test program. Nine participants analyzedsample sets of blind duplicates of 16 types of hydrocarbons andhydrocarbon-oxygenate blends. The sample set consisted of eight gasolinesamples and eight diesel samples. For the gasoline sample set, theconcentration range was approximately from 3 to 100 mgS/kg and for thediesel sample set, approximately between 2 to 85 mgS/kg. To facilitate thecalibration of the analyzers involved in the interlaboratory study, acalibration standard was provided
