ASTM D3341-2005 Standard Test Method for Lead in Gasoline-Iodine Monochloride Method《汽油中铅含量的标准试验方法 单氯化碘法》.pdf
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1、Designation: D 3341 05An American National StandardStandard Test Method forLead in GasolineIodine Monochloride Method1This standard is issued under the fixed designation D 3341; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear 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. Scope*1.1 This test method determines total lead in gasolinescontaining lead alkyls at concentrations between 0.026 and
3、 1.3g Pb/L, and 0.12 and 6.0 g Pb/UK gal, 0.1 and 5.0 g Pb/US gal.1.2 The preferred units are grams per litre although bothgram per US gallon and grams per UK gallon are acceptabledue to their widespread use in the industry.1.3 This standard does not purport to address all of thesafety concerns, if
4、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 Sections 6 and 8.2. Referenced Documents2.1 ASTM Standa
5、rds:2D 1193 Specification for Reagent WaterD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 6299 Practice for Applying Statistical Quality AssuranceTechniques to Evaluate Analytical Measurement SystemPerformance3. Summary of Test Method3.1 A known volume of the sample is dilut
6、ed with heavydistillate and shaken with aqueous iodine monochloride re-agent. Any tetraalkyl lead compounds present react with theiodine monochloride and are extracted into the aqueous phaseas the dialkyl lead compounds. The aqueous extract is sepa-rated from the gasoline and evaporated to low bulk
7、to decom-pose free iodine monochloride. Any organic matter present isremoved by oxidation with nitric acid, which also serves toconvert the dialkyl lead compounds into inorganic lead com-pounds. The residue is dissolved in distilled water and bufferedto pH 5 using sodium acetate-acetic acid buffer.
8、The leadcontent of the buffered solution is determined by titration withEDTA using xylenol orange as indicator.4. Significance and Use4.1 This test method determines the concentration of leadalkyl additives in gasoline. These additives improve the anti-knock properties.5. Apparatus5.1 Separatory Fun
9、nel, borosilicate glass, capacity 250 mL,glass-stoppered with preferably an iodine flask type of neck.5.2 Erlenmeyer Flask, borosilicate glass, capacity 500 mL.6. Reagents and Materials6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended
10、 thatall reagents shall conform to the specifications 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
11、lessening theaccuracy of the determination.6.1.1 Commercially available reagents may be used in placeof laboratory preparations when they conform to the specifi-cations in 6.1.6.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Typ
12、e III or Type IV of Specification D 1193.6.3 Ammonia Solution (1 + 1)Mix 1 volume of concen-trated ammonia solution (rel dens 0.90) with 1 volume ofdistilled water.6.4 Bromthymol Blue Indicator Solution Dissolve 0.1 g ofbromthymol blue in 50 mL of ethanol and dilute to 100 mLwith distilled water.6.5
13、 EDTA, Standard Solution (0.005 M)Dissolve approxi-mately 3.75 g of diaminoethanetetra-acetic acid, disodium salt,in 2-L of distilled water. Determine the molarity of the solutionby standardization with lead nitrate solution as follows:1This test method is under the jurisdiction of ASTM Committee D0
14、2 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved May 1, 2005. Published May 2005. Originallyapproved in 1974. Last previous edition approved in 2000 as D 334100.2For referenced ASTM standards, visit the ASTM w
15、ebsite, 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.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For s
16、uggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1*A Summary of Changes sec
17、tion appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.5.1 Using a pipet, transfer 25.0 mL of the standard leadnitrate solution to a 250-mL Erlenmeyer flask. Dilute to about75 mL with distilled wate
18、r and add several drops of bromthy-mol blue indicator solution. Titrate with 1 + 1 ammonia solu-tion until the color of the solution just changes to blue; then add10 mLof sodium acetate-acetic acid buffer solution and 5 dropsof xylenol orange indicator solution. In the presence of lead thesolution w
19、ill have a rose color. Titrate with the EDTA solution.The color changes near the end point, this being indicated by asharp change from orange to a permanent bright lemon-yellow.6.5.2 Record the titer and calculate the molarity of theEDTA solution. The addition of excess EDTA produces nofurther color
20、 change at the end point.6.6 Heavy DistillateA straight-run, lead-free, petroleumdistillate of low bromine number, with approximately 10 %distilling at 400F (205C) and 90 % at 460F (240C)(WarningCombustible).6.7 Iodine Monochloride Reagent (1.0 M) (WarningIodine monochloride will react with ammonium
21、 ions undercertain conditions to yield nitrogen triiodide, which is explo-sive. Take care, therefore, that this reagent does not come intocontact with ammonia or ammonium salts.) Dissolve 111.0 g ofpotassium iodide (KI) in approximately 400 mL of distilledwater. Add 445 mL of concentrated hydrochlor
22、ic acid (sp gr1.18) and cool to room temperature. Add 75.0 g of potassiumiodate (KIO3) slowly and with stirring, until all the free iodineinitially formed has just redissolved to give a clear orange-redsolution (the amounts of KI and KIO3are calculated to give aslight excess of iodate; if a greater
23、excess is present, this willcause precipitation of lead and indifferent end points in theEDTA titration). Cool to room temperature and dilute to 1 Lwith distilled water. Store in a glass-stoppered bottle(WarningDo not use rubber stoppers to stopper vesselscontaining iodine monochloride solutions.).6
24、.8 Lead Nitrate, Standard Solution (0.005 M)Weigh withan accuracy of 60.001 g about 1.7 g of lead nitrate (Pb(NO3)2)that has been dried at 105C and cooled in a desiccator.Dissolve it in distilled water and add 10 mL of concentratednitric acid. Dilute to 1 L with distilled water in a volumetricflask
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