1、Designation: D3988 05 (Reapproved 2017)Standard Test Method forVanadium in Paint Driers by EDTA Method1This standard is issued under the fixed designation D3988; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi
2、sion. 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 the titrimetric determination ofvanadium in liquid vanadium driers and utilizes the disodiumsalt of eth
3、ylenediaminetetraacetic acid dihydrate (EDTA).1.2 This test method is limited to the determination of thevanadium content of a liquid vanadium drier that does notcontain other drier elements. This test method is not applicableto drier blends.1.3 All cations that can be titrated with EDTA in alkaline
4、media interfere and must not be present in the sample.1.4 This test method has been tested for concentrations of 3and 4 % vanadium, but there is no reason to believe that it isnot suitable for higher or lower vanadium concentrationsprovided specimen size is adjusted proportionately.1.5 The values st
5、ated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 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 a
6、nd health practices and determine the applica-bility of regulatory limitations prior to use.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standa
7、rds, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D600 Specification for Liquid Paint DriersD1193 Specification for Reagent WaterE180 Practice for Determining the Precision of ASTMMethods for
8、Analysis and Testing of Industrial and Spe-cialty Chemicals (Withdrawn 2009)3E300 Practice for Sampling Industrial Chemicals3. Summary of Test Method3.1 The amount of vanadium drier used in oxidizing-typecoatings significantly affects their drying properties. The vana-dium drier is acidified and hea
9、ted to make the vanadiumavailable for chelation with EDTA. It is then chelated, the pHadjusted, and the excess titrated with zinc chloride solution,using Eriochrome Black T as the indicator.4. Significance and Use4.1 This test method may be used to confirm the statedcontent of a pure liquid vanadium
10、 drier manufactured for useby the coatings industry.5. Apparatus5.1 Centrifuge, capable of developing 1000 to 2000 g.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of
11、the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of
12、WaterUnless otherwise indicated, referenceto water shall be understood to mean reagent water conformingto Type II of Specification D1193.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, andApplications and is the direct responsibility ofSubco
13、mmittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved July 1, 2017. Published July 2017. Originally approvedin 1981. Last previous edition approved in 2011 as D3988 05 (2011). DOI:10.1520/D3988-05R17.2For referenced ASTM standards, visit the ASTM website, www.ast
14、m.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 last approved version of this historical standard is referenced onwww.astm.org.4Reagent Chemicals, American Chemical So
15、ciety Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacop
16、eial Convention, Inc. (USPC), Rockville,MD.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 standardization established in the Decisio
17、n on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.16.3 Ammonium Hydroxide (sp gr 0.90)Concentrated am-monium hydroxide (NH4OH).6.4 Ascorbic Acid.6.5 Buffer SolutionAdd 350 mL of
18、 concentrated NH4OHto 54 g of ammonium chloride and dilute to 1 L with water.6.6 Eriochrome Black T IndicatorMix and grind thor-oughly in a mortar a mixture of 0.2 g of Eriochrome Black Tand 100 g of sodium chloride. Store the mixture in a tightlystoppered bottle where it is stable indefinitely.6.7
19、EDTA, Standard Solution (0.01 M)Weigh about 3.73 gof EDTA to the nearest 0.01 g, dissolve in water, and dilute toapproximately 1 L in a glass-stoppered bottle.6.8 Hydrochloric Acid (sp gr 1.19)Concentrated hydro-chloric acid (HCl).6.9 Isopropyl Alcohol, 99.5 %.6.10 Zinc Chloride, Standard Solution (
20、ZnCl2) (0.01 M)Weigh about 0.65 g of zinc (Note 1) to 5 mg. Transfer to a 1-Lvolumetric flask, and add 25 mL of dilute hydrochloric acid(1 + 3). Warm if necessary on a steam bath to dissolve thematerial completely. Cool, dilute to the mark with water andmix thoroughly.NOTE 1Store the zinc ribbon in
21、a tightly closed container to preventthe surface of the zinc from oxidizing.7. Sampling7.1 Take a small sample of liquid drier from bulk using theprocedure in Practice E300 appropriate for the size of thecontainer: section on Bottle Sampling for tanks and tank cars,or section on Tube Sampling for dr
22、ums and cans.NOTE 2Liquid driers are normally homogeneous so that only simplephysical tests, such as specific gravity or solids content, on top and bottomsamples from tanks, are required to confirm that separation has notoccurred. Agitate the drums in accordance with the section on TubeSampling of P
23、ractice E300.7.2 Examine the sample of drier for sediment or suspendedmatter which, if present, is evidence of noncompliance withSpecification D600.7.3 If the sample is homogeneous keep it in a stopperedvessel to prevent solvent evaporation prior to analysis.8. Standardization8.1 Zinc Chloride, Stan
24、dard Solution (0.01 M)Calculatethe molarity, M1as follows:M15 S1/65.37 (1)where:S1= zinc used, g, and65.37 = zinc to producea1Msolution, g/L.8.2 EDTA, Standard Solution (0.01 M)Transfer 40.00 mLof this solution from a buret into a 250-mL assay beaker orwide-mouth flask. Add 50 mL of isopropyl alcoho
25、l, 10 mL ofbuffer solution, and about 0.2 g of indicator mixture. Mixthoroughly by swirling. Titrate with the standard ZnCl2solu-tion to the first permanent appearance of a red color.NOTE 3If the end point is overstepped, add 1.0 mL of the EDTAsolution to the mixture and titrate again with standard
26、ZnCl2solution. Usetotal volume of each solution for the calculation.8.2.1 Calculate the molarity of the EDTA solution, M2,asfollows:M25 V1M1/V2(2)where:V1= volume of ZnCl2solution, mL,M1= molarity of ZnCl2solution, andV2= volume of EDTA solution, mL.9. Procedure9.1 Check the clarity of the drier. If
27、 not clear, centrifuge aportion of the sample until it is clear, keeping the centrifugetube stoppered to prevent solvent evaporation.9.2 Place a few grams of the drier in a 50-mL Erlenmeyerflask fitted with a cork through which passes a dropping tubeand rubber bulb (or eye dropper) and obtain the to
28、tal weight.Weigh by difference to 0.5 mg two or three 0.18 to 0.22-gspecimens into 250-mL wide-mouth flasks.NOTE 4This is the correct specimen weight range for a vanadiumdrier containing 3 to 6 % of vanadium (16 to 24 mL of standard 0.01 MZnCl2solution is required for the titration).9.3 Add to each
29、flask, 15 mL of isopropyl alcohol and 1.0mL of concentrated HCl. Boil the solutions (use a steam bathif possible, and boiling aids) gently for 5 min, then cool for 5to 10 min in a cold water bath (Note 5). Add 35 mL more ofisopropyl alcohol to each flask.NOTE 5Boiling with HCl converts, bi-, tri-, a
30、nd tetravalent vanadiumto the relativity stable vanadyl ion, VO+. The latter chelates with EDTAina1to1molar ratio as do other metallic ions.9.4 From a buret, measure 40.0 mL of EDTA solution intoeach flask.Add 0.1 g of ascorbic acid (solution should be blue)and swirl to dissolve (Note 6). Add 15 to
31、20 mL of buffersolution and about 0.3 g of indicator mixture (Note 7). Mixthoroughly by swirling.NOTE 6Ascorbic acid, a reducing agent, is added to reduce anymetavanadate ion, VO3+, to vanadyl ion, VO+.NOTE 7The amounts of ascorbic acid and indicator mixture are notcritical. With a little experience
32、, these may be added from the tip of aspatula.9.5 Titrate with standard ZnCl2solution to the first perma-nent tinge of red (see Note 8 and Note 9). Maintain vigorousswirling during the titration to ensure thorough mixing of thetwo phases that may appear.NOTE 8The color change at the end point is fro
33、m blue to blue with ared tinge. Adding more ZnCl2solution gives a violet color.NOTE 9Use a good titration light to assist in detecting the end point.10. Calculation10.1 Calculate the percent of the vanadium present, A,asfollows:A 5V3M22 V4M1! 5.10#S2(3)D3988 05 (2017)2where:V3= volume of EDTA soluti
34、on, mL,M2= molarity of EDTA solution,V4= volume of ZnCl2solution, mL,M1= molarity of ZnCl2solution,5.10 = millimolar weight of vanadium 100, andS2= specimen used, g.11. Precision511.1 The precision estimates are based on an interlaboratorystudy in which one operator in five different laboratoriesana
35、lyzed in duplicate on two different days two samples ofvanadium drier containing 3 and 4 % vanadium. The vanadiumdrier was commercially supplied. The results were analyzedstatistically in accordance with Practice E180 and the within-laboratory standard deviation was found to be 0.025 % vana-dium at
36、9 df and the between-laboratory standard deviation0.07 % vanadium at 7 df. Based on these standard deviations,the following criteria should be used for judging the accept-ability of results at the 95 % confidence level:11.1.1 RepeatabilityTwo results, each the mean of dupli-cate determinations, obta
37、ined by the same operator on differentdays should be considered suspect if they differ by more than0.08 % absolute at concentrations of 3 to 4 % vanadium.11.1.2 ReproducibilityTwo results, each the mean of du-plicate determinations, obtained by operators in different labo-ratories should be consider
38、ed suspect if they differ by morethan 0.22 % absolute at concentrations of 3 to 4 % vanadium.12. Bias12.1 Bias cannot be determined for this method becausethere are no accepted standards for vanadium in paint driers.13. Keywords13.1 EDTA-analysis; liquid drier; paint driers; vanadiumdrierASTM Intern
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