ASTM_D_4450_-_85_2012.pdf

Designation:D445085(Reapproved 2012)Standard Test Method forAnalysis of Zinc Hydroxy Phosphite Pigment1This standard is issued under the fixed designation D4450;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,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.Scope1.1 This test method is intended for the determination ofzinc oxide and phosphorous acid content of the pigmentcommercially known as zinc hydroxy phosphite.The zinccontent is determined by ethylenediaminetetraacetate(EDTA)titration and calculated as zinc oxide(ZnO),while the phos-phorus content is determined colorimetrically and calculated asphosphorous acid(H3PO3).1.2 The analytical procedures appear in the following order:SectionsZinc oxide6 through 8Phosphorous acid9 through 141.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 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 regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent Water3.Summary of Test Method3.1 The zinc is determined by dissolving the test sample innitric acid,adjusting the pH of the solution to 5 to 5.5 andtitrating with EDTA.3.2 The phosphorus is determined colorimetrically with theaid of nitric acid,ammonium vanadate,and ammonium mo-lybdate.The absorbance of the test sample is compared to acalibration curve that yields the number of milligrams ofphosphorus.4.Significance and Use4.1 This test method may be used to confirm the stated zincoxide and phosphorous acid content of zinc hydroxy phosphitepigment.5.Purity of Reagents5.1 Reagent grade chemicals shall be used in all tests.Unless otherwise indicated,it is intended that all reagents shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society,where suchspecifications are available.3Other grades may be used,pro-vided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.5.2 Unless otherwise indicated,references to water shall beunderstood to mean reagent water conforming to Type II ofSpecification D1193.TOTAL ZINC AS ZINC OXIDE6.Reagents6.1 Ammonium Hydroxide(sp gr 0.90),concentrated ammo-nium hydroxide(NH4OH).6.2 Glacial Acetic Acid(min 99.7%),concentrated glacialacetic acid(CH3COOH).6.3 Acid Ammonium Acetate BufferMix 400 mL of dis-tilled water and 400 mLof reagent grade ammonium hydroxide(sp gr 0.90).Add 375 mL of reagent grade glacial acetic acidslowly while stirring.6.4 Cupric Sulfate Solution(0.1 M)Dissolve 25 g ofCuSO45H2O in distilled water and dilute to 1 L.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.31 on Pigment Specifications.Current edition approved Nov.1,2012.Published November 2012.Originallyapproved in 1985.Last previous edition approved in 2007 as D4450 85(2007)DOI:10.1520/D4450-85R12.2For referenced ASTM standards,visit the 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.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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.5 Disodium Ethylenediaminetetraacetate Dihydrate(0.05M)(EDTASolution)Dissolve 18.6 g of the reagent grade saltin distilled water and dilute to 1 L.Standardize the solution asfollows:6.5.1 Transfer 25 mL of lead standard(6.6)to a 400-mLbeaker.Add concentrated ammonium hydroxide(6.1)dropwiseuntil a permanent precipitate just forms.Add 25 mL of acidammonium acetate(6.3),dilute to 200 mL,heat to boiling,add4 drops of copper EDTA(6.7)and 12 drops of PAN(6.8),andtitrate with EDTA to a clear yellow.6.5.2 Calculate the molarity of the EDTA,M,as follows:M 5 2530.01036/L 30.20721(1)where L=EDTA solution,mL.Also 1 mL of primary stan-dard 0.05 M lead nitrate=0.01036 g of lead and 0.20721 isthe milliequivalent weight of lead.6.6 Primary Standard(0.05 M lead nitrate)Dissolve16.5615 g reagent grade lead nitrate in distilled water anddilute to 1 L(1 mL=0.01036 g lead).6.7 Copp