1、Designation: D 2373 05Standard Test Method forDetermination of Cobalt in Paint Driers by EDTA Method1This standard is issued under the fixed designation D 2373; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a titrimetric determination ofcobalt in liquid paint driers that can be dissolved in glacialacetic acid
3、 and utilizes the disodium salt of ethylenediamine-tetraacetic acid dihydrate (EDTA).1.2 This test method is not applicable to drier blends. Ifdriers other than cobalt are present, they may interfere byreacting with EDTA under the conditions used for analysis.1.3 All cations that can be titrated wit
4、h EDTA in alkalinemedia interfere and must not be present in the sample.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its us
5、e. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 600 Specification for Liquid Paint DriersD 1193 Specification for Reagent
6、 WaterE 180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial ChemicalsE 300 Practice for Sampling Industrial Chemicals3. Summary of Test Method3.1 The liquid drier is dissolved in glacial acetic acid,diluted with isopropyl alcohol and water, and treated wi
7、th anexcess of standard EDTA solution. The excess is titrated withstandard cupric sulfate solution using PAN as the metalindicator.4. Significance and Use4.1 The amount of cobalt drier used in oxidizing-typecoatings significantly affects their drying properties. This testmethod may be used to confir
8、m the stated cobalt content of apure liquid cobalt drier soluble in glacial acetic acid andmanufactured for use by 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 otherwi
9、se indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purit
10、y to permit its use without lessening theaccuracy of the determination.6.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Type II of Specification D 1193.6.3 Ammonium Chloride (NH4Cl).6.4 Ammonium Hydroxide (sp gr 0.90) Concentrat
11、ed ammo-nium hydroxide (NH4OH).6.5 Buffer Solution (pH 10.0)Dissolve 67.5 g of NH4Cl inwater, add 570 mL of concentrated NH4OH (sp gr 0.90), anddilute to 1 L.6.6 Cupric Sulfate, Standard Solution (0.05 M)Dissolve12.5 g of cupric sulfate pentahydrate (CuSO45H2O) in waterand dilute to 1 L.6.7 Eriochro
12、me Black-T IndicatorTriturate 0.20 g of theconcentrated dye with 100 g of sodium chloride (NaCl) andstore in a tightly stoppered jar. This mixture remains stable forseveral years.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, andApplication
13、s and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved Jan. 1, 2005. Published February 2005. Originallyapproved in 1965. Last previous edition approved in 1999 as D 2373 85 (1999).2For referenced ASTM standards, visit the
14、 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.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC
15、. 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. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM Int
16、ernational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.8 EDTA, Standard Solution (0.05 M)Dissolve 18.62 gof EDTA in water and dilute to 1 L. Store in a polyethylene orborosilicate glass bottle.6.9 Glacial Acetic Acid (sp gr 1.06).6.10 Isopropyl Alcohol, 99.
17、5%.6.11 Methyl Red Indicator SolutionDissolve 0.2 g ofmethyl red in 100 mL of methanol, ethanol, or isopropanol.6.12 PAN Indicator(1(2-Pyridylazo)-2-Naphthol) Prepare adilute solution of the indicator by dissolving 0.10 g in 100 mLof ethanol or isopropanol.6.13 Sodium Acetate SolutionPrepare a satur
18、ated aqueoussolution of sodium acetate (NaC2H3O2) in water.6.14 Sodium Chloride (NaCl).6.15 Sodium Hydroxide Solution (80 g/L)Dissolve 80 g ofsodium hydroxide (NaOH) in water and dilute to 1 L.6.16 Sulfuric Acid (8+1)Carefully mix 8 volumes ofconcentrated sulfuric acid (H2SO4, sp gr 1.84) with 1 vol
19、umeof water.6.17 Zinc Oxide (ZnO).7. Sampling7.1 Take a small sample of liquid drier from bulk using theprocedures in Practice E 300 appropriate for the size of thecontainer: see the section on Bottle Sampling for tanks andtank cars, or the section on Tube Sampling for drums and cans.NOTE 1Liquid dr
20、iers 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 drums in accordance with the section on Tube Samplingin Practice E 300.7.2 Examine the samp
21、le of drier for sediment or suspendedmatter which, if present, is evidence of noncompliance withSpecification D 600.7.3 If the sample is homogeneous keep it in a stopperedvessel to prevent solvent evaporation prior to analysis.8. Standardization8.1 EDTA, Standard Solution (0.05 M)Weigh to the near-e
22、st 0.1 mg approximately 1.5 g of ZnO into a 100-mL beakerand add 10 mL of H2SO4(8+1). Transfer the solution to a500-mL volumetric flask and dilute to the mark with water.Pipet a 50-mLaliquot into a 500-mLErlenmeyer flask, add 100mL of water, 2 or 3 drops of methyl red indicator solution, andneutrali
23、ze with NaOH solution (80 g/L). Add 5 mL of buffersolution, 0.2 g of Eriochrome Black-T indicator, and titratewith EDTA solution until the color changes from red to blue,where the last red shade just disappears.8.1.1 Calculate the molarity, M1, of the EDTA solution asfollows:M15WV13 0.0814!(1)where:
24、W = ZnO used, g,V1= EDTA solution, mL, and0.0814 = molecular weight of ZnO 3 103= millimolar weight of ZnO.8.2 CuSO4, Standard Solution (0.05 M)Determine thetiter of the CuSO4solution by titrating 50 mL of the standardEDTA solution with CuSO4as described in 9.4 using the PANindicator solution.8.2.1
25、Calculate the molarity, M2, of the CuSO4solution asfollows:M25M13 V3!V2(2)where:M1= molarity of EDTA solution,V3= EDTA solution, mL, andV2= CuSO4solution, mL.9. Procedure9.1 Check the clarity of the drier. If not clear, centrifuge aportion of the sample until it is clear. Keep the centrifuge tubesto
26、ppered so that solvent will not evaporate.9.2 Weigh the following specimen amounts into a 500-mLErlenmeyer flask and add 5 mL of glacial acetic acid: (1) for6 % cobalt, 1.0 to 1.3 g, (2) for 8 % cobalt, 0.8 to 1.0 g, and (3)for more or less cobalt use proportionate specimen sizes. Warmon a hot plate
27、 at low heat, swirling the flask until the specimenis completely dissolved.9.3 In a second flask (blank) put the same amount of glacialacetic acid but no sample. Add 200 mL of isopropyl alcohol,100 mL of water, 6 mL of concentrated NH4OH (sp gr 0.90),10 mL of NaC2H3O2solution, and 50 mL of EDTA solu
28、tion toeach flask. Swirl to ensure complete mixing and warm bothflasks at steam bath temperature for 5 min.9.4 To each of the flasks add 2 mLof PAN indicator solutionand titrate with the standard CuSO4solution to a blue endpoint.NOTE 2Because the color of the metal indicators (and some of theircompl
29、exes) is affected by pH changes, the pH must be kept constantduring titration by the recommended buffer during titration.10. Calculation10.1 Calculate the percent of cobalt, A, present as follows:A 5FB 2 V4! 3 M23 FSG3 100 (3)where:B = CuSO4solution required for titration of the blank,mL,V4= CuSO4so
30、lution required for the specimen, mL,M2= molarity of CuSO4solution,F = millimolecular weight for the metal in thesample = 0.05894 for cobalt, andS = specimen used, g11. Precision and Bias (see Practice E 180)11.1 Precision:11.1.1 ReproducibilityTwo results, each the mean of du-plicate determinations
31、, obtained by operators in different labo-ratories, should be considered suspect if they differ by morethan 0.10 % cobalt.D237305211.1.2 RepeatabilityTwo results, each the mean of dupli-cate determinations, obtained by the same operator on differentdays should be considered suspect if they differ by
32、 more than0.05 % cobalt.11.2 BiasBias cannot be determined for this methodbecause there are no accepted standards for cobalt in paintdriers.12. Keywords12.1 cobalt drier analysis; EDTA methodASTM International takes no position respecting the validity of any patent rights asserted in connection with
33、 any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible techni
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35、n at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harb
36、or Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D2373053
