1、Designation: D 3348 98 (Reapproved 2003)e1An American National StandardStandard Test Method forRapid Field Test for Trace Lead in Unleaded Gasoline(Colorimetric Method)1This standard is issued under the fixed designation D 3348; the number immediately following the designation indicates the year ofo
2、riginal 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.e1NOTEWarning notes were editorially moved into the standard text in Ju
3、ly 2003.1. Scope1.1 This test method is intended for use in the field bynontechnical people for the quantitative measurement of leadin unleaded gasoline in the range from 0.01 to 0.10 g Pb/U.S.gal (2.64 to 26.4 mg Pb/L). This method applies to allcommercial gasolines and responds to all types of lea
4、d alkylsas well as to other organic and inorganic forms of lead.NOTE 1This test method is based on 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 Test Method D 3116, Test Method D 3229, or TestMethod D 3237.1.2 The valu
5、es stated in SI units shall be regarded asstandard.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 applica-bility of
6、regulatory limitations prior to use. For specificwarning statements, see Section 7.2. Referenced Documents2.1 ASTM Standards:D 3116 Test Method for Trace Amounts of Lead in Gaso-line2D 3229 Test Method for Low Levels of Lead in Gasoline byX-Ray Spectrometry3D 3237 Test Method for Lead in Gasoline by
7、 AtomicAbsorption Spectroscopy43. Summary of Test Method3.1 The gasoline is treated with iodine and tetraethyl am-monium chloride in chloroform and subjected to ultravioletlight. The lead alkyls form water-soluble lead alkyl iodides,which are removed from the gasoline by shaking it with anaqueous am
8、monium nitrate solution. The aqueous extract isfiltered into a solution of 4-(2-pyridylazo)-resorcinol disodiumsalt (PAR) and ammonium hydroxide. The lead is determinedby measuring its PAR complex colorimetrically at 490 nmusing a previously prepared calibration curve.4. Significance and Use4.1 This
9、 test is used to determine trace quantities of lead inunleaded gasoline. Unwarranted amounts of lead may causedeposits in automotive pollution control equipment and poi-soning of catalytic mufflers.5. Interferences5.1 PAR also reacts with many other metals forming highlycolored complexes. However, n
10、one of these are normally foundpresent in a soluble form in gasoline. The following metalswere found to form colors with PAR and if present mayinterfere to give high results: Fe II, Fe III, Co II, Ni II, Cu II,Zn II, Cd II, Mn II, Sn II, V IV, Pb II, U VI, Ti IV, and the rareearths.6. Apparatus6.1 U
11、ltraviolet Lamp,5long wavelength, 3660 , placed ina standard 4-W fluorescent fixture.NOTE 3A 3-min electric timer6,7is connected to the fixture in theprototype kit.6.2 Measuring Block, aluminum, drilled to hold an 18 by150-mm test tube, with a mark at a level equal to 5.0 mL ofliquid in the test tub
12、e.6.3 Colorimeter, Portable, capable of operating at 490 mm.Any equivalent instrument capable of measurement near 514nm (the optimum Pb-PAR complex wavelength) may be used.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsi
13、bility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved May 10, 2003. Published July 2003. Originallyapproved in 1974. Last previous edition approved in 1998 as D 334898.2Annual Book of ASTM Standards, Vol 05.01.3Discontinued. See 1992 Annual Book of ASTM Standards, Vol 05.02.4An
14、nual Book of ASTM Standards, Vol 05.02.5Lamp F4T5.BL, available from the General Electric Co., or equivalent, hasbeen found satisfactory for this purpose.6The sole source of supply of the 3min timer known to the committee at thistime is H. M. Rhodes, Avon, CT 06001, Catalog No. 90021.7If you are awa
15、re of alternative suppliers, please provide this information toASTM International Headquarters. Your comments will receive careful consider-ation at a meeting of the responsible technical committee,1which you may attend.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoho
16、cken, PA 19428-2959, United States.6.4 Test Tubes,7,8borosilicate, 18 by 150 mm.6.5 Pipets, 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 Funn
17、el, plastic, 2 in. in inside diameter.6.7 Filter Paper, ashless, hardened, smooth, very fast, 11.0cm 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,7,9with cap
18、s, disposable, 1-oz capacity.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society, wheresuch specifications
19、 are available.10Other 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, referenceto water shall be understood to mean distilled water
20、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 6 0.1 g of ammonium nitrate (NH4NO3) in 750 mL ofwater in a 1-L volumetric flask. Dilute to the mark with water.7.5 Chloroform (CHCl3)(WarningMay
21、be fatal ifswallowed. 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 vapors ifburned. See A1.1.)8The sole source of supply of t
22、he disposable culture tubes known to thecommittee at this time is Sargent Welch Co., 35 Stern Ave., Springfield, NJ 07081,Catalog No. S-79523K.9The 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. 6
23、0957.10Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Phar
24、macopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.FIG. 1 Mobil Lead Test KitD 3348 98 (2003)e127.6 Disodium Salt of 4-(2-pyridylazo)-Resorcinol Dihydrate(PAR2H2O) (Reagent C) Dissolve 25.0 6 0.1 mg of PAR in750 mL of water in a 1-L volumetric flask. Add 10.0 6
25、0.1 mLof concentrated NH4OH. Dilute to the mark with water. Storethis in brown bottles out of direct sunlight 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
26、.The PAR reagent should be tested by adding the reagent to atest tube and determining the percent transmittance. 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-mab
27、le. Harmful if inhaled. Vapors may cause flash fire. SeeA1.2.)7.8 Iodine.7.9 Iodine/TEAC/CHCl3Solution (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 tetraethy-lammonium chloride (TEAC) and mix until dissolved. Diluteto th
28、e mark with CHCl3.NOTE 5Solutions described in 7.4, 7.6, and 7.9 have been found to bestable for at least 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 metho
29、d.7.11 Tetraethylammonium Chloride Monohydrate (TEAC).7.12 Quality Control (QC) Sample(s), preferably areportions of one or more gasoline materials or product standardsof known lead content that were not used in the generation ofthe instrument calibration curve. These (QC) samples are to beused to c
30、heck the validity of the testing process as described inSection 10. An ample supply of QC sample material 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
31、least fourgasoline standards of known lead content that cover the rangefrom 0.01 to 0.10 g Pb/gal (2.64 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 (Reagent A) fromano
32、ther pipet, to the vial containing the gasoline. Tightly capthe vial.8.1.2 Place the vial on the ultraviolet light and set the timerto give the sample a 3-min exposure.8.1.2.1 (WarningUltraviolet light can be harmful to theeyes. A protective shield has been provided in the prototype kit.DO NOT remov
33、e it or otherwise defeat its purpose. DO NOTstare at the light.)8.1.3 After exposure, remove and uncap 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. (Thetim
34、er in the kit may be used.)8.1.4 Place a clean 18-mm test tube in the aluminummeasuring block. Add 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
35、. Fold a piece of filterpaper and place in the funnel.8.1.5 When the two layers of liquid in the vial 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 thef
36、unnel to add any remaining drops of aqueous solution to thetest tube. Remove the funnel and discard 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 o
37、f the organic layer may come through the filterpaper. This will not alter the results and can therefore 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
38、in the liquid.Wait for these to settle before continuing. Wipe the test tube off with aclean towel 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
39、) with water in an 18-mm test tube. Readand record the absorbance (or percent transmittance) obtainedfor the standards.8.2.2 Plot the absorbance values versus concentration onrectangular coordinate paper. (If percent transmittance valuesare used, plot them versus concentration using semilog paper,wi
40、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
41、-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
42、-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 (2.64mg/L).NOTE
43、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
44、5 g/gal would be reported as 0.04 g/gal, while0.045 g/gal would also be reported as 0.04 g/gal.D 3348 98 (2003)e1310. Quality Control10.1 Confirm the performance of the apparatus or theprocedure, or both, each day it is in use by analyzing a QCsample (7.1.2) that is representative of samples typical
45、lyanalyzed. Increase 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,11or other statistically equivalent techniques, toascertain the control status of the total testing process. An
46、y outof control data should trigger investigation for root cause. TheQC sample precision shall be checked against the ASTMmethod precision to ensure data quality.11. Precision11.1 The precision of this test method as determined bystatistical examination of interlaboratory test results is asfollows:1
47、1.1.1 RepeatabilityThe difference between two test re-sults, obtained by the same operator with the same apparatusunder constant operating conditions on identical test material,would in the long run, in the normal and correct operation ofthe test method, exceed the following values only in one casei
48、n twenty:0.01 g/gal (2.64 mg/L)11.1.2 ReproducibilityThe difference between two singleand independent results obtained by different operators work-ing in different laboratories on identical test material would, inthe long run, in the normal and correct operation of the testmethod, exceed the followi
49、ng values only in one case intwenty:0.02 g/gal (5.28 mg/L)12. Keywords12.1 field test; trace lead; unleaded gasoline11ASTM Manual 7, Manual on Presentation of Data and Control ChartAnalysis, ASTM International, W. Conshohocken.FIG. 2 Graph of Transmittance Values Versus ConcentrationD 3348 98 (2003)e14ANNEX(Mandatory Information)A1. WARNING STATEMENTSA1.1 ChloroformMay be fatal if swallowed.Harmful if inhaled. May produce toxic vapors if burned.Keep container closed.Avoid prolonged breathing of vapor or spray mist.Avoid contact with eyes and skin.Do
