1、Designation: D3341 05 (Reapproved 2011)D3341 16Standard Test Method forLead in GasolineIodine Monochloride Method1This standard is issued under the fixed designation D3341; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f 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. Scope Scope*1.1 This test method determines total lead in gasolines containing lead alkyls at concentrations between 0.0260.0
3、26 g and 1.3g 1.3 g Pb/L, and 0.120.12 g and 6.0 g Pb/UK gal, 0.10.1 g and 5.0 g 5.0 g Pb/US gal.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.2.1 The preferred units are grams per litre although both gram per US gallo
4、n and grams per UK gallon are acceptable dueto their widespread use in the industry.1.2.2 Temperature is given in degrees Fahrenheit and degrees Celsius in this test method.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibi
5、lityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. For specific hazard statements, see Sections 6 and 8.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD4057 Prac
6、tice for Manual Sampling of Petroleum and Petroleum ProductsD4177 Practice for Automatic Sampling of Petroleum and Petroleum ProductsD6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-ment System Performance3. Summary of Test Meth
7、od3.1 A known volume of the sample is diluted with heavy distillate and shaken with aqueous iodine monochloride reagent. Anytetraalkyl lead compounds present react with the iodine monochloride and are extracted into the aqueous phase as the dialkyl leadcompounds. The aqueous extract is separated fro
8、m the gasoline and evaporated to low bulk to decompose free iodinemonochloride. Any organic matter present is removed by oxidation with nitric acid, which also serves to convert the dialkyl leadcompounds into inorganic lead compounds. The residue is dissolved in distilled water and buffered to pH 5
9、using sodiumacetate-acetic acid buffer. The lead content of the buffered solution is determined by titration with EDTA using xylenol orange asindicator.4. Significance and Use4.1 This test method determines the concentration of lead alkyl additives in gasoline. These additives improve the antiknockp
10、roperties.5. Apparatus5.1 Separatory Funnel, borosilicate glass, capacity 250 mL, 250 mL, glass-stoppered with preferably an iodine flask type ofneck.5.2 Erlenmeyer Flask, borosilicate glass, capacity 500 mL. 500 mL.1 This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Prod
11、ucts Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.03 on Elemental Analysis.Current edition approved May 1, 2011July 1, 2016. Published August 2011July 2016. Originally approved in 1974. Last previous edition approved in 20052011 asD3341D3341 05 (2011).05
12、. DOI: 10.1520/D3341-05R11.10.1520/D3341-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is
13、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. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropri
14、ate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1
15、6. Reagents and Materials6.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, wheresuch specifications are av
16、ailable.3 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determination.6.1.1 Commercially available reagents may be used in place of laboratory preparations when they conform to the spe
17、cificationsin 6.1.6.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean reagent water as defined byType III or Type IV of Specification D1193.6.3 Ammonia Solution (1 + 1)Mix 1 volume of concentrated ammonia solution (rel dens 0.90) with 1 volume of distilledw
18、ater.6.4 Bromthymol Blue Indicator Solution Dissolve 0.1 g 0.1 g of bromthymol blue in 50 mL 50 mL of ethanol and dilute to100 mL 100 mL with distilled water.6.5 EDTA, Standard Solution (0.005 M)(0.005 M)Dissolve approximately 3.75 g 3.75 g of diaminoethanetetra-acetic acid,disodium salt, in 2-L2 L
19、of distilled water. Determine the molarity of the solution by standardization with lead nitrate solution asfollows:6.5.1 Using a pipet, transfer 25.0 mL25.0 mLof the standard lead nitrate solution to a 250-mL250 mLErlenmeyer flask. Diluteto about 75 mL 75 mL with distilled water and add several drop
20、s of bromthymol blue indicator solution. Titrate with 1 + 1ammonia solution until the color of the solution just changes to blue; then add 10 mL 10 mL of sodium acetate-acetic acid buffersolution and 5 drops of xylenol orange indicator solution. In the presence of lead the solution will have a rose
21、color. Titrate withthe EDTAsolution. The color changes near the end point, this being indicated by a sharp change from orange to a permanent brightlemon-yellow.6.5.2 Record the titer and calculate the molarity of the EDTA solution. The addition of excess EDTA produces no further colorchange at the e
22、nd point.6.6 Heavy DistillateAstraight-run, lead-free, petroleum distillate of low bromine number, with approximately 10 % distillingat 400F (205C)400 F (205 C) and 90 % at 460F (240C)460 F (240 C) (WarningCombustible).6.7 Iodine Monochloride Reagent (1.0 M) (1.0 M) (WarningIodine monochloride will
23、react with ammonium ions undercertain conditions to yield nitrogen triiodide, which is explosive. Take care, therefore, that this reagent does not come into contactwith ammonia or ammonium salts.) Dissolve 111.0 g 111.0 g of potassium iodide (KI) in approximately 400 mL400 mLof distilledwater. Add 4
24、45 mL 445 mL of concentrated hydrochloric acid (sp gr 1.18) and cool to room temperature. Add 75.0 g 75.0 g ofpotassium iodate (KIO3) slowly and with stirring, until all the free iodine initially formed has just redissolved to give a clearorange-red solution (the amounts of KI and KIO3 are calculate
25、d to give a slight excess of iodate; if a greater excess is present, thiswill cause precipitation of lead and indifferent end points in the EDTA titration). Cool to room temperature and dilute to 1 L 1 Lwith distilled water. Store in a glass-stoppered bottle (WarningDo not use rubber stoppers to sto
26、pper vessels containing iodinemonochloride solutions.).6.8 Lead Nitrate, Standard Solution (0.005 M)Weigh with an accuracy of 60.001 g about 1.7 g 60.001 g about 1.7 g of leadnitrate (Pb(NO3)2) that has been dried at 105C105 C and cooled in a desiccator. Dissolve it in distilled water and add 10 mL1
27、0 mL of concentrated nitric acid. Dilute to 1 L 1 L with distilled water in a volumetric flask and shake thoroughly to mix.Calculate the molarity of the solution according to the equation:Molarity5wt g!of lead nitrate/331.23 (1)6.9 Nitric Acid, concentrated (rel dens 1.42).concentrated, relative den
28、sity 1.42.6.10 Sodium Acetate, Acetic Acid Buffer SolutionDissolve 23.0 g 23.0 g of anhydrous sodium acetate in about 500 mL500 mLof distilled water. Using a buret, add 6.2 mL6.2 mLof glacial acetic acid. Dilute to 1 L1 Lwith distilled water in a 1-L1 Lvolumetric flask and shake to mix.6.11 Xylenol
29、Orange Indicator Solution Dissolve 0.2 g 0.2 g of xylenol orange, sodium salt, in 100 mL 100 mL of distilledwater and add 1 drop of 1 + 1 hydrochloric acid. (Prepare freshly each week.)7. Sampling7.1 Samples shall be taken in accordance with the instructions in PracticePractices D4057 or D4177.3 Rea
30、gent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, 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
31、 and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D3341 1628. Procedure8.1 Transfer 50 mL 50 mL of the iodine monochloride reagent and 25 mL 25 mL of heavy distillate to the 250-mL250 mLseparatory funnel. Measure the temperature of the sample to the nearest 0.5C (1F)0
32、.5 C (1 F) (Note 1). Using a pipetWarning(Never suck leaded gasoline or corrosive liquids into a pipet by the mouth), transfer 2525 mL 6 0.05 mL 0.05 mL ofthe sample of the gasoline to the separatory funnel. Immediately stopper the funnel and shake the contents for 60 s. 60 s. Allowthe funnel to sta
33、nd for several minutes, until the two phases have separated and run the lower aqueous phase into a 500-mL500 mLErlenmeyer flask made of borosilicate glass. Wash the gasoline phase by shaking with three separate 20-mL20 mL portions ofdistilled water and add the washings to the Erlenmeyer flask.NOTE 1
34、For cool gasolines having a Reid vapor pressure above 7.0 lb 7.0 lb cool the sealed sample container to approximately 60F (15C)60 F(15 C) before removing the sample for analysis.8.2 Place several glass beads in the flask, cover the mouth of the flask with a small ribbed watch glass, and place on a h
35、ot plate.Heat the contents and allow to boil until the volume of the solution is 1515 mL to 20 mL. 20 mL. Without removing the flask fromthe hot plate, add 5 mL 5 mL of concentrated nitric acid down the side of the flask and evaporate the contents almost to drynessto oxidize any organic material pre
36、sent. Repeat the nitric acid treatment, evaporating almost to dryness until all the organic matterhas been removed and a white residue remains. Finally remove the watch glass and evaporate the solution to dryness. Remove theflask from the hot plate and allow the contents to cool.8.3 Add about 200 mL
37、 200 mL of distilled water to the flask and swirl to dissolve the residue. The residue may be quicklydissolved by heating the solution, but this must be cooled before titrating. Add 5 drops of bromthymol blue indicator and titratewith 1 + 1 ammonia solution until the color just changes to blue; then
38、 add 10 mL 10 mL of sodium acetate-acetic acid buffersolution and 5 drops of xylenol orange indicator solution. In the presence of lead, the solution will now have a rose color.8.4 Titrate with the 0.005 M standard EDTA solution. The color of the solution changes to orange near the end point, the en
39、dpoint being indicated by a sharp change from orange to a permanent bright lemon-yellow. Note the titer. The addition of excessEDTA solution produces no further color change at the end point.8.5 Carry out a blank determination on the reagents, excluding the heavy distillate and omitting the extracti
40、on stage and, ifnecessary, correct the sample titer accordingly.9. Calculation9.1 Calculate the concentration of lead by means of one of the following equations (see also Note 2):Lead,g/US gal at 60F15.5C!531.37 TM 110.00065 t 260! (2)Lead,g/UK gal at 60F15.5C!537.68 TM 110.00065 t 260! (3)Lead,g/La
41、t 15C58.288 TM 110.0012 tx 215! (4)where:T = volume of EDTA solution used to titrate the sample, mL,M = molarity of EDTA solution,t = the temperature of gasoline when pipeting sample, F, andtx = temperature of gasoline when pipeting sample, C.NOTE 2The constant 31.37 is obtained from the expression
42、0.20721 3785.3 25, where 0.20721 is the number of grams of lead equivalent to 1 mLof M EDTA solution, 3785.3 is the number of millilitres in a US gal, and 25 represents the sample volume in millilitres. The constant 37.68 is obtainedby multiplying 31.37 by 1.201 (the ratio of millilitres in 1 UK gal
43、 to millilitres in 1 US gal, 4546.0 and 3785.3 respectively). The constant 8.288 isobtained by dividing 31.37 by 3.7853.NOTE 3The coefficient of expansion of gasolines is taken as 0.00065/C at 60F60 F and 0.0012/C at 15C.15 C.NOTE 4For gasoline containing only tetraethyl-lead (TEL) or tetramethyl-le
44、ad (TML), the grams of lead per unit volume can be converted tomillilitres per unit volume by multiplying by the following factors:For tetraethyl lead TEL!50.946 (5)For tetramethyl lead TML!50.64810. Quality Control10.1 Confirm the performance of the test procedure by analyzing a quality control sam
45、ple that is stable and representative ofthe sample of interest.10.1.1 When the quality control/quality assurance protocols are already established in the testing facility, these may be used toconfirm the reliability of the test reult.10.1.2 When there is no quality control/quality assurance protocol
46、 established in the testing facility, Appendix X1 can be usedto perform this function.D3341 16311. Report11.1 Report the result to the nearest 0.01 g Pb/US gal at 60F,60 F, 0.01 g Pb/UK gal at 60F,60 F, or 0.002 g Pb/L at15C,15 C, as appropriate.12. Precision and Bias12.1 PrecisionThe precision of t
47、he method as determined by statistical examination of interlaboratory test results is asfollows:12.1.1 RepeatabilityThe difference between two test results, obtained by the same operator with the same apparatus underconstant operating conditions on identical test material, would in the long run, in
48、the normal and correct operation of the testmethod, exceed the following values only in one case in twenty:Litre:0.0036510.0073A2 (6)where:A2 = the average of the results in grams of lead per litre at 15.5C.A2 = the average of the results in grams of lead per litre at 15.5 C.US gallon:0.013810.0073A
49、 (7)where:A = the average of the results in grams of lead per US gallon at 60F (15.5C).A = the average of the results in grams of lead per US gallon at 60 F (15.5 C).UK gallon:0.016610.0073A1 (8)where:A1 = the average of the results in grams of lead per UK gallon at 60F (15.5C).A1 = the average of the results in grams of lead per UK gallon at 60 F (15.5 C).12.1.2 ReproducibilityThe difference between two single and independent results obtained by different operators working indifferent laborato
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