1、Designation: D3348 07D3348 12Standard 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 of revisio
2、n, 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. Scope*1.1 This test method covers and is intended for use in the field by nontechnical people for the quantitati
3、ve 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 all commercialgasolines and responds to all types of lead alkyls as well as to other organic and inorganic forms of lead.NOTE 1This test method is based on the use o
4、f the Mobil Lead Test Kit (Fig. 1).NOTE 2This test method is a screening test and is not to be used as a replacement for withdrawn Test Method D3116, withdrawn Test Method D3229,or Test Method D3237. , Test Method D3341, or Test Method D5059.1.2 The values stated in SI units are to be regarded as st
5、andard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the a
6、pplicability of regulatorylimitations prior to use. For specific warning statements, see Section 7.2. Referenced Documents2.1 ASTM Standards:2D3116 Test Method for Trace Amounts of Lead in Gasoline (Withdrawn 1994)3D3229 Test Method for Low Levels of Lead in Gasoline by X-Ray Spectrometry (Withdrawn
7、 1992)3D3237 Test Method for Lead in Gasoline by Atomic Absorption SpectroscopyD3341 Test Method for Lead in GasolineIodine Monochloride MethodD5059 Test Methods for Lead in Gasoline by X-Ray SpectroscopyD6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Eva
8、luate Analytical Measure-ment System PerformanceD6792 Practice for Quality System in Petroleum Products and Lubricants Testing Laboratories3. Summary of Test Method3.1 The gasoline is treated with iodine and tetraethyl ammonium chloride in chloroform and subjected to ultraviolet light. Thelead alkyl
9、s form water-soluble lead alkyl iodides, which are removed from the gasoline by shaking it with an aqueous ammoniumnitrate solution. The aqueous extract is filtered into a solution of 4-(2-pyridylazo)-resorcinol disodium salt (PAR) and ammoniumhydroxide. The lead is determined by measuring its PAR c
10、omplex colorimetrically at 490 nm using a previously preparedcalibration curve.4. Significance and Use4.1 This test is used to determine trace quantities of lead in unleaded gasoline. Unwarranted amounts of lead may cause depositsin automotive pollution control equipment and poisoning of catalytic m
11、ufflers.1 This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.03 onElemental Analysis.Current edition approved Dec. 1, 2007Dec. 1, 2012. Published January 2008 January 2013. Originally approved in
12、1974. Last previous edition approved in 20032007 asD334898(2003)D3348 1.07. DOI: 10.1520/D3348-07.10.1520/D3348-12.2 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 th
13、e standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.This document is 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
14、version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes
15、section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Interferences5.1 PAR also reacts with many other metals forming highly colored complexes. However, none of these are normally foundpresent i
16、n a soluble form in gasoline. The following metals were found to form colors with PAR and if present may interfere togive 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 rare earths.6. Apparatus6.1 Ultraviolet Lamp, long wavelength, 366
17、0 , placed in a standard 4-W fluorescent fixture.NOTE 3A 3-min electric timer4,5 is connected to the fixture in the prototype kit.6.2 Measuring Block, aluminum, drilled to hold an 18 by 150-mm test tube, with a mark at a level equal to 5.0 mL of liquidin the test tube.6.3 Colorimeter, Portable, capa
18、ble of operating at 490 mm. Any equivalent instrument capable of measurement near 514 nm(the optimum Pb-PAR complex wavelength) may be used.6.4 Test Tubes,5,6borosilicate, 18 by 150 mm.6.5 Pipets, glass, dropping, capable of delivering 2.0 mL with a 2-mL bulb. (WarningGasoline or any of the reagents
19、 mustnot come in contact with rubber. If this happens, discard the bulb and pipet and start again.)6.6 Funnel, plastic, 2 in. in inside diameter.6.7 Filter Paper, ashless, hardened, smooth, very fast, 11.0 cm in diameter.4 The sole source of supply of the 3min timer known to the committee at this ti
20、me is H. M. Rhodes, Avon, CT 06001, Catalog No. 90021.5 If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical committee,1 which you may attend.6 The sole
21、 source of supply of the disposable culture tubes known to the committee at this time is Sargent Welch Co., 35 Stern Ave., Springfield, NJ 07081, Catalog No.S-79523K.FIG. 1 Mobil Lead Test KitD3348 122NOTE 4Certain filter papers that would allow the organic layer (gasoline/chloroform) to filter thro
22、ugh 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 shall be used in all tests. Unless otherwise indicated, it is intended that allreagents conform to the specifications of the
23、Committee on Analytical Reagents of the American Chemical Society, where suchspecifications are available.8 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purityto permit its use without lessening the accuracy of the determination.7.2 Purity of Wa
24、terUnless otherwise indicated, reference to water shall be understood to mean distilled water or water of equalpurity.7.3 Ammonium Hydroxide (sp gr 0.90)Concentrated ammonium hydroxide (NH4OH).7.4 Ammonium Nitrate Solution (Reagent B)Dissolve 15.0 6 0.1 g of ammonium nitrate (NH4NO3) in 750 mL of wa
25、ter ina 1-L volumetric flask. Dilute to the mark with water.7.5 Chloroform (CHCl3)(WarningMay be fatal if swallowed. Harmful if inhaled. May produce toxic vapors if burned.Chronic or repeated exposure can cause liver or kidney damage. Harmful if inhaled or swallowed. Carcinogen (animal positive).Ski
26、n and eye irritant. May produce toxic vapors if burned. See A1.1.)7.6 Disodium Salt of 4-(2-pyridylazo)-Resorcinol Dihydrate (PAR2H2O) (Reagent C)Dissolve 25.0 6 0.1 mg of PAR in 750mL of water in a 1-L volumetric flask. Add 10.0 6 0.1 mL of concentrated NH4OH. Dilute to the mark with water. Store t
27、his inbrown bottles out of direct sunlight or in the dark. (WarningLow results are obtained if the monosodium or unsalted PAR isused in this test. Field experience has shown that the PAR reagent can deteriorate within two to six months. The PAR reagentshould be tested by adding the reagent to a test
28、 tube and determining the percent transmittance. If the percent transmittance is lessthan 80 %, the reagent should be discarded.)7.7 Gasoline, Lead-FreeGasoline containing less than 0.05 g Pb/gal (13.0 mg Pb/L). (WarningExtremely flammable.Harmful if inhaled. Vapors may cause flash fire. See A1.2.)7
29、.8 Iodine.7.9 Iodine/TEAC/CHCl3 Solution (Reagent A)Dissolve 1.000 g 6 1 mg of iodine in 75 mL of chloroform (CHCl3) in a100-mL volumetric flask. Add 1.000 g 6 1 mg of tetraethylammonium chloride (TEAC) and mix until dissolved. Dilute to themark with CHCl3.NOTE 5Solutions described in 7.4, 7.6, and
30、7.9 have been found to be stable for at least 2 months.7.10 Lead StandardsThis method was developed using lead standards prepared by addition of known amounts of various leadalkyls to blended unleaded gasoline to cover the range of this method.7.11 Tetraethylammonium Chloride Monohydrate (TEAC).7.12
31、 Quality Control (QC) Sample(s), preferably are portions of one or more gasoline materials or product standards of knownlead content that were not used in the generation of the instrument calibration curve. These (QC) samples are to be used to checkthe validity of the testing process as described in
32、 Section 10. An ample supply of QC sample material shall be available for theintended period of use, and must be homogeneous and stable under the anticipated storage conditions.8. Calibration8.1 Prepare a calibration curve as follows, using at least four gasoline standards of known lead content that
33、 cover the range from0.01 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 the gasoline sample. Add 2.0 mL of the sample to a 1-oz glass vial. Add2.0 mL of iodine/TEAC/CHCl3 solution (Reagent A) from another pipet, to the vial containing the gasoline. Tig
34、htly cap the vial.8.1.2 Place the vial on the ultraviolet light and set the timer to give the sample a 3-min exposure.8.1.2.1 (WarningUltraviolet light can be harmful to the eyes.Aprotective shield has been provided in the prototype kit. DONOT remove it or otherwise defeat its purpose. DO NOT stare
35、at the light.)8.1.3 After exposure, remove and uncap the vial. Measure 10.0 mL of ammonium nitrate solution (Reagent B) into the 10-mLgraduated cylinder. Add this to the vial containing the sample. Recap and shake the vial vigorously for 1 min. (The timer in thekit may be used.)7 The sole source of
36、supply of the glass vials known to the committee at this time is J. W. Wilson Glass Co., 501 S. Park Ave., Linden, NJ 07036, Catalog No. 60957.8 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggestions on the testing of reagents not list
37、ed bythe American Chemical Society, see Annual Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D3348 1238.1.4 Place a clean 18-mm test tube in the aluminum measuring
38、 block.Add 5.0 mLof PAR solution (Reagent C) to the test tubeusing the mark on the block such that the upper level of liquid in the tube is equal to the mark on the block. Place the plastic funnelin the test tube. Fold a piece of filter paper and place in the funnel.8.1.5 When the two layers of liqu
39、id in the vial have separated (8.1.3), pour the entire contents of the vial inside the filter paper.The aqueous layer will filter into the test tube; the gasoline/CHCl3 layer will remain in the filter paper. Tap the funnel to add anyremaining drops of aqueous solution to the test tube. Remove the fu
40、nnel and discard its contents. Swirl the test tube gently usinga wrist action to obtain a uniform color.NOTE 6The lead-PAR complex formed in 8.1.5 must be measured within 10 min after starting 8.1.5.NOTE 7A few drops of the organic layer may come through the filter paper. This will not alter the res
41、ults and can therefore be tolerated. However,if more than 10 drops do come through, refilter the aqueous layer 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 of
42、f with a clean towelto remove any fingerprints that may be present on the surface of 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. Read andrecord the absorbance (or percent
43、 transmittance) obtained for the standards.8.2.2 Plot the absorbance values versus concentration on rectangular coordinate paper. (If percent transmittance values are used,plot them versus concentration using semilog paper, with the percent transmittance values on the log scale.) Draw a best fit lin
44、eby eye. (See Fig. 2 and Fig. 3 for examples.) When plotting absorbance versus concentration note that the curve does not passthrough the origin.9. Procedure9.1 Prepare the sample in accordance with the directions given in 8.1.1-8.1.5.NOTE 9Short form instructions are outlined in Appendix X1.9.2 Pla
45、ce the test tube containing the water in the colorimeter and set the absorbance to zero, or to 100 % transmittance.9.3 Place the sample in the colorimeter and read the absorbance or percent transmittance.NOTE 10Time LimitThe PAR-lead solution obtained for the sample in 9.1 must be read within 10 min
46、 after the step described in 8.1.5.FIG. 2 Graph of Transmittance Values Versus ConcentrationD3348 1249.4 From the calibration curve, find the lead content of the sample. Determine the lead content to the nearest 0.001 g/gal (0.26mg/L) value. Report the lead content to 0.01 g/gal (2.64 mg/L).NOTE 11T
47、he lead content may be obtained from the calibration curve to three significant figures (0.001 g/gal); however, the value must be roundedto two significant figures (0.01 g/gal) for reporting purposes. When the third digit is 5 the value should be rounded to the nearest even number. Forexample, 0.035
48、 g/gal would be reported as 0.04 g/gal, while 0.045 g/gal would also be reported as 0.04 g/gal.10. Quality Control10.1 Confirm the performance of the apparatus or the procedure, or both, each day it is in use by analyzing a QC sample (7.12)that is representative of samples typically analyzed. Increa
49、se the analysis frequency of the QC sample if a large number of samplesare analyzed. Analysis of the result(s) from the QC sample(s) can be carried out using control charts,9 or other statisticallyequivalent techniques, to ascertain the control status of the total testing process.Any out of control data should trigger investigationfor root cause. The QC sample precision shall be checked against the ASTM method precision to ensure data quality. Furtherguidance on quality control can be found in Practices D6299 and D6792.11. Precision11.1 The prec
