1、Designation: D3348 12 (Reapproved 2017)Standard Test Method forRapid Field Test for Trace Lead in Unleaded Gasoline(Colorimetric Method)1This standard is issued under the fixed designation D3348; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、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 reapproval.1. Scope1.1 This test method covers and is intended for use in thefield by nontechnical people for the qu
3、antitative measurementof lead in unleaded gasoline in the range from 0.01 g to 0.10 gPb/U.S. gal (2.64 mg to 26.4 mg Pb/L). This method applies toall commercial gasolines and responds to all types of leadalkyls as well as to other organic and inorganic forms of lead.NOTE 1This test method is based o
4、n the use of the Mobil Lead TestKit (Fig. 1).NOTE 2This test method is a screening test and is not to be used as areplacement for withdrawn Test Method D3116, withdrawn Test MethodD3229, Test Method D3237, Test Method D3341, or Test Method D5059.1.2 The values stated in SI units are to be regarded a
5、sstandard. No other units of measurement are included in thisstandard.1.3 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-priate safety and health practices and determine the
6、 applica-bility of regulatory limitations prior to use. For specificwarning statements, see Section 7.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of Internatio
7、nal Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D3116 Test Method for Trace Amounts of Lead in Gasoline(Withdrawn 1994)3D3229 Test Method for Low Levels of Lead in Gasoline byX-Ray
8、 Spectrometry (Withdrawn 1992)3D3237 Test Method for Lead in Gasoline byAtomicAbsorp-tion SpectroscopyD3341 Test Method for Lead in GasolineIodine Mono-chloride MethodD5059 Test Methods for Lead in Gasoline by X-Ray Spec-troscopyD6299 Practice for Applying Statistical Quality Assuranceand Control Ch
9、arting 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 gasoline is treated with iodine and tetraethyl am-monium chloride in chloroform
10、 and subjected to ultravioletlight. The lead alkyls form water-soluble lead alkyl iodides,which are removed from the gasoline by shaking it with anaqueous ammonium nitrate solution. The aqueous extract isfiltered into a solution of 4-(2-pyridylazo)-resorcinol disodiumsalt (PAR) and ammonium hydroxid
11、e. The lead is determinedby measuring its PAR complex colorimetrically at 490 nmusing a previously prepared calibration curve.4. Significance and Use4.1 This test is used to determine trace quantities of lead inunleaded gasoline. Unwarranted amounts of lead may causedeposits in automotive pollution
12、control equipment and poi-soning of catalytic mufflers.5. Interferences5.1 PAR also reacts with many other metals forming highlycolored complexes. However, none of these are normally foundpresent in a soluble form in gasoline. The following metalswere found to form colors with PAR and if present may
13、1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.03 on Elemental Analysis.Current edition approved May 1, 2017. Published June 2017. Originallyapproved in 1974. Last previous editi
14、on approved in 2012 as D3348 12. DOI:10.1520/D3348-12R17.2For 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.3The
15、 last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on stand
16、ardization 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.1interfere to give high results: Fe II, Fe III, Co II, Ni II, Cu II,Zn II, Cd II, Mn II, S
17、n II, V IV, Pb II, U VI, Ti IV, and the rareearths.6. Apparatus6.1 Ultraviolet Lamp, long wavelength, 3660 , placed in astandard 4 W fluorescent fixture.NOTE 3A 3 min electric timer4,5is connected to the fixture in theprototype kit.6.2 Measuring Block, aluminum, drilled to hold an 18 mmby 150 mm tes
18、t tube, with a mark at a level equal to 5.0 mL ofliquid in the test tube.6.3 Colorimeter, Portable, capable of operating at 490 mm.Any equivalent instrument capable of measurement near514 nm (the optimum Pb-PAR complex wavelength) may beused.6.4 Test Tubes,5,6borosilicate, 18 mm by 150 mm.6.5 Pipets
19、, glass, dropping, capable of delivering 2.0 mLwith a 2 mL bulb. (WarningGasoline or any of the reagentsmust not come in contact with rubber. If this happens, discardthe bulb and pipet and start again.)6.6 Funnel, plastic, 2 in. in inside diameter.6.7 Filter Paper, ashless, hardened, smooth, very fa
20、st,11.0 cm in diameter.NOTE 4Certain filter papers that would allow the organic layer(gasoline/chloroform) to filter through are not acceptable.6.8 Graduated Cylinder, plastic, 10 mL.6.9 Glass Vials,5,7with caps, disposable, 1 oz capacity.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shal
21、l beused in all tests. Unless otherwise indicated, it is intended that4The sole source of supply of the 3 min timer known to the committee at thistime is H. M. Rhodes, Avon, CT 06001, Catalog No. 90021.5If you are aware of alternative suppliers, please provide this information toASTM International H
22、eadquarters. Your comments will receive careful consider-ation at a meeting of the responsible technical committee,1which you may attend.6The sole source of supply of the disposable culture tubes known to thecommittee at this time is Sargent Welch Co., 35 Stern Ave., Springfield, NJ 07081,Catalog No
23、. S-79523K.7The sole source of supply of the glass vials known to the committee at this timeis J. W. Wilson Glass Co., 501 S. Park Ave., Linden, NJ 07036, Catalog No. 60957.FIG. 1 Mobil Lead Test KitD3348 12 (2017)2all reagents conform to the specifications of the Committee onAnalytical Reagents of
24、the American Chemical Society, wheresuch specifications are available.8Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7.2 Purity of WaterUnless otherwise indicated, referenc
25、eto water shall be understood to mean distilled water or water ofequal purity.7.3 Ammonium Hydroxide (sp gr 0.90)Concentrated am-monium hydroxide (NH4OH).7.4 Ammonium Nitrate Solution (Reagent B)Dissolve15.0 g 6 0.1 g of ammonium nitrate (NH4NO3) in 750 mL ofwater in a 1 L volumetric flask. Dilute t
26、o the mark with water.7.5 Chloroform (CHCl3)(WarningMay be fatal if swal-lowed. Harmful if inhaled. May produce toxic vapors ifburned. Chronic or repeated exposure can cause liver or kidneydamage. Harmful if inhaled or swallowed. Carcinogen (animalpositive). Skin and eye irritant. May produce toxic
27、vapors ifburned. See A1.1.)7.6 Disodium Salt of 4-(2-pyridylazo)-Resorcinol Dihydrate(PAR2H2O) (Reagent C)Dissolve 25.0 mg 6 0.1 mg of PARin 750 mL of water in a 1 L volumetric flask. Add 10.0 mL 60.1 mL of concentrated NH4OH. Dilute to the mark with water.Store this in brown bottles out of direct s
28、unlight or in the dark.(WarningLow results are obtained if the monosodium orunsalted PAR is used in this test. Field experience has shownthat the PAR reagent can deteriorate within two to six months.The PAR reagent should be tested by adding the reagent to atest tube and determining the percent tran
29、smittance. If thepercent transmittance is less than 80 %, the reagent should bediscarded.)7.7 Gasoline, Lead-FreeGasoline containing less than0.05 g Pb/gal (13.0 mg Pb/L). (WarningExtremely flam-mable. Harmful if inhaled. Vapors may cause flash fire. SeeA1.2.)7.8 Iodine.7.9 Iodine/TEAC/CHCl3Solution
30、 (Reagent A)Dissolve1.000 g 6 1 mg of iodine in 75 mL of chloroform (CHCl3)ina 100 mL volumetric flask. Add 1.000 g 6 1 mg of tetraethyl-ammonium chloride (TEAC) and mix until dissolved. Dilute tothe mark with CHCl3.NOTE 5Solutions described in 7.4, 7.6, and 7.9 have been found to bestable for at le
31、ast 2 months.7.10 Lead StandardsThis method was developed usinglead standards prepared by addition of known amounts ofvarious lead alkyls to blended unleaded gasoline to cover therange of this method.7.11 Tetraethylammonium Chloride Monohydrate (TEAC).7.12 Quality Control (QC) Sample(s), preferably
32、are por-tions of one or more gasoline materials or product standards ofknown lead content that were not used in the generation of theinstrument calibration curve. These (QC) samples are to beused to check the validity of the testing process as described inSection 10. An ample supply of QC sample mat
33、erial shall beavailable for the intended period of use, and must be homoge-neous and stable under the anticipated storage conditions.8. Calibration8.1 Prepare a calibration curve as follows, using at least fourgasoline standards of known lead content that cover the rangefrom 0.01 g to 0.10 g Pb/gal
34、(2.64 mg to 26.4 mg Pb/L).8.1.1 Rinse the 2 mL graduated pipet three times with thegasoline sample.Add 2.0 mL of the sample to a 1 oz glass vial.Add 2.0 mL of iodine/TEAC/CHCl3solution (ReagentA) fromanother pipet, to the vial containing the gasoline. Tightly capthe vial.8.1.2 Place the vial on the
35、ultraviolet light and set the timerto give the sample a 3 min exposure.8.1.2.1 (WarningUltraviolet light can be harmful to theeyes.Aprotective shield has been provided in the prototype kit.DO NOT remove it or otherwise defeat its purpose. DO NOTstare at the light.)8.1.3 After exposure, remove and un
36、cap the vial. Measure10.0 mL of ammonium nitrate solution (Reagent B) into the10 mL graduated cylinder. Add this to the vial containing thesample. Recap and shake the vial vigorously for 1 min. (Thetimer in the kit may be used.)8.1.4 Place a clean 18 mm test tube in the aluminummeasuring block. Add
37、5.0 mL of PAR solution (Reagent C) tothe test tube using the mark on the block such that the upperlevel of liquid in the tube is equal to the mark on the block.Place the plastic funnel in the test tube. Fold a piece of filterpaper and place in the funnel.8.1.5 When the two layers of liquid in the vi
38、al haveseparated (8.1.3), pour the entire contents of the vial inside thefilter paper. The aqueous layer will filter into the test tube; thegasoline/CHCl3layer will remain in the filter paper. Tap thefunnel to add any remaining drops of aqueous solution to thetest tube. Remove the funnel and discard
39、 its contents. Swirl thetest tube gently using a wrist action to obtain a uniform color.NOTE 6The lead-PAR complex formed in 8.1.5 must be measuredwithin 10 min after starting 8.1.5.NOTE 7A few drops of the organic layer may come through the filterpaper. This will not alter the results and can there
40、fore be tolerated.However, if more than 10 drops do come through, refilter the aqueouslayer through a fresh filter paper into a clean empty test tube.NOTE 8Swirling may cause air bubbles to be trapped in the liquid.Wait for these to settle before continuing. Wipe the test tube off with aclean towel
41、to remove any fingerprints that may be present on the surfaceof the tube.8.2 Zero and standardize the colorimeter as follows:8.2.1 Set the colorimeter at 490 nm. Set zero absorbance(100 % transmittance) with water in an 18 mm test tube. Readand record the absorbance (or percent transmittance) obtain
42、edfor the standards.8.2.2 Plot the absorbance values versus concentration onrectangular coordinate paper. (If percent transmittance values8Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by th
43、e American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D3348 12 (2017)3are used, plot them versus concentration using semilog paper,wi
44、th the percent transmittance values on the log scale.) Draw abest fit line by eye. (See Fig. 2 and Fig. 3 for examples.) Whenplotting absorbance versus concentration note that the curvedoes not pass through the origin.9. Procedure9.1 Prepare the sample in accordance with the directionsgiven in 8.1.1
45、 8.1.5.NOTE 9Short form instructions are outlined in Appendix X1.9.2 Place the test tube containing the water in the colorim-eter and set the absorbance to zero, or to 100 % transmittance.9.3 Place the sample in the colorimeter and read theabsorbance or percent transmittance.NOTE 10Time LimitThe PAR
46、-lead solution obtained for the samplein 9.1 must be read within 10 min after the step described in 8.1.5.9.4 From the calibration curve, find the lead content of thesample. Determine the lead content to the nearest 0.001 g gal(0.26 mg L) value. Report the lead content to 0.01 g gal(2.64 mg L).NOTE
47、11The lead content may be obtained from the calibration curveto three significant figures (0.001 g gal); however, the value must berounded to two significant figures (0.01 g gal) for reporting purposes.When the third digit is 5 the value should be rounded to the nearest evennumber. For example, 0.03
48、5 g gal would be reported as 0.04 g gal, while0.045 g gal would also be reported as 0.04 g gal.10. Quality Control10.1 Confirm the performance of the apparatus or theprocedure, or both, each day it is in use by analyzing a QCsample (7.12) that is representative of samples typicallyanalyzed. Increase
49、 the analysis frequency of the QC sample ifa large number of samples are analyzed. Analysis of theresult(s) from the QC sample(s) can be carried out usingcontrol charts,9or other statistically equivalent techniques, toascertain the control status of the total testing process. Any outof control data should trigger investigation for root cause. TheQC sample precision shall be checked against the ASTMmethod precision to ensure data quality. Further guidance onquality control can be found in Practices D6299 and D6792.11. Precision11.1 The prec
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