CAN CGSB-3 0 NO 19 5-2011 Methods of testing petroleum and associated products Determination of lead in automotive gasoline (Atomic absorption).pdf

1、CAN/CGSB3.0No. 19.52011Supersedes CAN/CGSB-3.0 No. 19.5-2004Methods of Testing Petroleum and Associated ProductsDetermination of Lead in Automotive Gasoline (Atomic Absorption)ICS 71.040.50National Standard of CanadaThe CANADIAN GENERAL STANDARDS BOARD (CGSB), under whose auspices this National Stan

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20、5-2004METHODS OF TESTING PETROLEUM AND ASSOCIATED PRODUCTS DETERMINATION OF LEAD IN AUTOMOTIVE GASOLINE (ATOMIC ABSORPTION)CETTE NORME NATIONALE DU CANADA EST DISPONIBLE EN VERSIONSFRANAISE ET ANGLAISE.NATIONAL STANDARD OF CANADA CAN/CGSB3.142006Prepared by the Approved by the Canadian General Stand

21、ards Board Standards Council of CanadaPublished May 2011 by the Canadian General Standards Board Gatineau, Canada K1A 1G6 HER MAJESTY THE QUEEN IN RIGHT OF CANADA, as represented by the Minister of Public Works and Government Services, the Minister responsible for the Canadian General Standards Boar

22、d (2011). No part of this publication may be reproduced in any form without the prior permission of the publisher.CANADIAN GENERAL STANDARDS BOARDCOMMITTEE ON PETROLEUM TEST METHODS(Voting membership at date of approval)ChairWispinski, D. Alberta Innovates Technology Futures (User)General Interest C

23、ategoryMnard, L. Advanced Engine Technology Ltd.Snow, M. PerkinElmerSt-Laurent, A. Canadian Coast GuardProducer CategoryBoroniec, J. Suncor EnergyBoulton, L. Husky EnergyFalkiner, R.J. Imperial OilPorter, S. Canadian Renewable Fuels AssociationRiel, K. Shell Canada Ltd.Samiullah, M. Sentinel CanadaW

24、hite, M. North AtlanticRegulator CategoryTardif, M. Environment CanadaUser CategoryJacula, T. Maxxam AnalyticsLam, M. National DefenceMacDonald, P. Natural Resources CanadaMcRae, M. SGS Canada Inc.Squires, B. OTI Canada GroupVidian-Jones, C. Certispec Services Inc.Secretary (Nonmember)Newman, M. Can

25、adian General Standards BoardAcknowledgment is made for the translation of this National Standard of Canada by the Translation Bureau of Public Works and Government Services Canada.CAN/CGSB3.0 No. 19.52011No. 19.52011 1CAN/CGSB3.0 No. 19.52011Supersedes CAN/CGSB-3.0 No. 19.5-2004CANADIAN GENERAL STA

26、NDARDS BOARDMETHODS OF TESTING PETROLEUM AND ASSOCIATED PRODUCTSDetermination of Lead in Automotive Gasoline (Atomic Absorption)1. SCOPE1.1 This method is used to determine the lead content of gasolines, including those containing ethanol. Lead in the range of 1 to 1100 mg/L can be measured.1.2 The

27、testing and evaluation of a product against this method may require the use of materials and/or equipment that could be hazardous. This document does not purport to address all the safety aspects associated with its use. Anyone using this method has the responsibility to consult the appropriate auth

28、orities and to establish appropriate health and safety practices in conjunction with any applicable regulatory requirements prior to its use.2. REFERENCED PUBLICATIONS2.1 The following publications are referenced in this method:2.1.1 ASTM InternationalD4057 Standard Practice for Manual Sampling of P

29、etroleum and Petroleum ProductsD6299 Standard Practice for Applying Statistical Quality Assurance Techniques to Evaluate Analytical Measurement System PerformanceE969 Standard Specification for Glass Volumetric (Transfer) Pipets.2.2 A dated reference in this method is to the issue specified. An unda

30、ted reference in this method is to the latest issue, unless otherwise specified by the authority applying this method. The sources are given in the Notes section.3. SUMMARY OF TEST METHOD3.1 The gasoline sample is diluted with methyl isobutyl ketone, the lead alkyl compounds are stabilized by a reac

31、tion with iodine, and the resultant lead alkyl iodide is complexed with a quaternary ammonium salt. The lead content of the sample is determined by atomic absorption spectrophotometry at 283.3 nm. Standards prepared from reagent-grade lead chloride are used for calibration. The method compensates fo

32、r variations in gasoline composition and is independent of the lead alkyl type.4. SIGNIFICANCE AND USE4.1 This method is used to ensure compliance of automotive gasolines with product or regulatory standards.5. APPARATUSNote: It is good laboratory practice to segregate apparatus that will be reused,

33、 such as sample bottles, volumetric flasks and pipettes, into two sets. Reserve one set for leaded gasoline and another set for unleaded gasoline.2 No. 19.520115.1 Spectrophotometer: atomic absorption, capable of scale expansion and nebulizer adjustment and equipped with a slot burner and premix cha

34、mber for use with an air-acetylene flame.5.2 Pipettes: glass, with capacities of 0.5, 1, 2, 3, 4, and 5 mL, “to deliver” and Class A volume accuracy in accordance with ASTM E969.5.3 Volumetric flasks: borosilicate with ground-glass stoppers, with capacities of 25, 50, 100, 250 and 1000 mL.5.4 Microp

35、ipette: Eppendorf type or equivalent, 100 L capacity.5.5 Sample bottles: brown glass with polyethylene or polytetrafluoroethylene-lined (PTFE-lined) caps, or amber polypropylene bottles and caps, with nominal capacities of 50, 100, 250 and 1000 mL.6. REAGENTSReagent-grade chemicals are required for

36、this method.6.1 Methyl isobutyl ketone (MIBK): certified lead free 4-methyl-2-pentanone.6.2 Iodine solution: dissolve 3.0 g of iodine crystals in toluene and dilute to 100 mL.6.3 Aliquot 336 (tricaprylmethylammonium chloride).6.4 Aliquot 336/MIBK solution (10% v/v): dissolve 100 mL (88.0 g) of Aliqu

37、ot 336 in MIBK and dilute to 1 L.6.5 Aliquot 336/MIBK solution (1% v/v): dissolve 10 mL (8.8 g) of Aliquot 336 in MIBK and dilute to 1 L.6.6 Lead chloride: (PbCl2).6.7 Isooctane (2,2,4trimethylpentane): certified lead free.6.8 Air: compressed.6.9 Acetylene: compressed.6.10 Stock lead solution (1000

38、mg lead/L): dissolve 0.3356 g of lead chloride previously dried at 105oC for 3 h, in approximately 200 mL of 10% Aliquot 336/MIBK solution in a 250 mL volumetric flask. Dilute to the mark with the 10% Aliquot 336/MIBK solution, mix and store in a sample bottle. The most serious potential source of e

39、rror in this method lies in the preparation of this solution. Therefore, the utmost care is required in its preparation and handling.6.11 Working standard lead solutions (5, 10, 20, 30, 40 and 50 mg lead/L): transfer 0.5, 1, 2, 3, 4 and 5 mL of the 1000 mg lead/L solution by pipette to 100 mL volume

40、tric flasks and dilute to the mark with MIBK. Mix well and store in sample bottles. These solutions should be prepared and used within one day.7. SAFETY PRECAUTIONS7.1 Gasolines are flammable and explosive. All appropriate safety precautions should be observed.8. PROCEDURE8.1 Sampling Sampling is to

41、 be carried out in accordance with ASTM D4057 in recognition that test results are dependent upon the integrity of the samples provided. Samples that must be stored for more than one day should be refrigerated between 0 and 4C to minimize losses. Allow the samples to warm to room temperature just pr

42、ior to analysis.No. 19.52011 38.2 Analysis8.2.1 Optimize the atomic absorption spectrophotometer for lead at 283.3 nm. Light the air-acetylene flame. Using the reagent blank (par. 9.1.5) adjust the gas mixture and the sample aspiration rate to obtain an oxidizing flame. MIBK solutions should be aspi

43、rated at about one-third the rate of aqueous solutions so that the flame remains blue.8.2.2 In order to achieve the lower detection limits of this method, optimization of the atomic absorption operating parameters and equipment is recommended. The absorbance of the 30 mg/L calibration standard shoul

44、d be optimized to its maximum value, which is typically greater than 0.15.8.2.3 Dilute the gasoline sample, if necessary, in accordance with Table 1. Samples with a lead concentration exceeding 50 mg/L must first be diluted with isooctane to bring the lead concentrations below this level. Table 1 sh

45、ows the necessary dilutions for concentrations up to 1000 mg/L. Dilutions have been chosen so that the concentration to be measured lies in the middle to upper range for the method.8.2.4 Pipette 5 mL of the gasoline sample into a 50 mL volumetric flask containing approximately 30 mL of MIBK and mix.

46、8.2.5 Add 100 L of iodine solution using the micropipette, mix well and allow the mixture to react for one minute.8.2.6 Add 5 mL of 1% Aliquot 336/MIBK solution using a pipette, mix well and dilute to volume with MIBK. Mix again. Allow the sample to stabilize for five minutes.8.2.7 Aspirate the samp

47、le into the calibrated atomic absorption spectrophotometer (see section 9) and record the absorbance value. Frequently check the zero reading with the reagent blank.9. CALIBRATION9.1 Gasoline standards and samples should be at the same temperature. It is necessary to prepare six working standards (5

48、, 10, 20, 30, 40 and 50 mg/L) and a blank to cover the full measurement range of the method. For unleaded gasolines with a lead content of less than 30 mg/L, only four working standards (5, 10, 20 and 30 mg/L) are required. These standards are prepared as described in par. 6.11.Note: To maximize acc

49、uracy, matrix matching may be necessary for gasolines containing ethanol. When matrix matching is required, prepare calibration standards and blanks to contain approximately the same concentration of ethanol as the samples of interest.9.1.1 To each of six 50 mL volumetric flasks containing 30 mL of MIBK add, with a pipette, 5 mL of the working standard lead solutions prepared as specified in par. 6.11.9.1.2 Add 5 mL of isooctane, using a pipette, and mix.9.1.3 Add 100 L of iodine solution using the micropipette, and mix.9.1.4 Add 5 mL of 1% Aliq