1、Designation: D 4450 85 (Reapproved 2007)Standard Test Method forAnalysis of Zinc Hydroxy Phosphite Pigment1This standard is issued under the fixed designation D 4450; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、 revision. 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 is intended for the determination ofzinc oxide and phosphorous acid content of the pigmentcommercially k
3、nown 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 followin
4、g order:SectionsZinc oxide 6 through 8Phosphorous acid 9 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
5、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 1193 Specification for Reagent Water3. Summary of Test Method3.1 The zinc is de
6、termined 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 acalibr
7、ation 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 other
8、wise 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 pur
9、ity 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 D 1193.TOTAL ZINC AS ZINC OXIDE6. Reagents6.1 Ammonium Hydroxide (sp gr 0.90), concentrated am-m
10、onium 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 C
11、upric Sulfate Solution (0.1 M)Dissolve 25 g ofCuSO45H2O in distilled water and dilute to 1 L.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
12、 of lead standard (6.6) to a 400-mLbeaker.Add concentrated ammonium hydroxide (6.1) dropwise1This 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.Cur
13、rent edition approved Nov. 1, 2007. Published November 2007. Originallyapproved in 1985. Last previous edition approved in 2002 as D 4450 - 85 (2002)2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStanda
14、rds 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
15、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 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.until a perman
16、ent 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 25 3 0.01036/L 3 0.20721 (1)where L =
17、EDTA solution, mL. Also 1 mL of primary standard0.05 M lead nitrate = 0.01036 g of lead and 0.20721 is themilliequivalent 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 Copper-EDTA
18、SolutionMix equivalent amounts ofcupric sulfate solution (6.4) and EDTA solution (6.5) and storein a dropping bottle. The cupric sulfate EDTAequivalence maybe determined as follows:6.7.1 Pipet 10 mL of cupric sulfate into a beaker, and addconcentrated ammonium hydroxide (6.1) dropwise until thepreci
19、pitate that forms just redissolves. Dilute to 200 mL withwater, add two Murexide indicator tablets, crush with a stirringrod to dissolve, and titrate immediately with EDTA to purple.6.8 Pan Indicator 1-(2-pyridylazo)-2-naphtholDissolve0.1 g in 100 mL of ethanol.6.9 Murexide Indicator TabletsAmmonium
20、 salt of purpu-ric acid.6.10 Nitric acid (sp gr 1.42)Concentrated nitric acid(HNO3).7. Procedure7.1 Weigh accurately 0.2 g of pigment and transfer to a400-mL beaker. Add 5 mL of nitric acid (6.10) and 50 mL ofwater and boil gently for 10 min. Cool, and add ammoniumhydroxide (6.1) until the pH of the
21、 solution is from 5 to 5.5 (asindicated by pH paper). Add 25 mL of acid ammonium acetate(6.3), boil 5 min, dilute to 200 mL with water, heat to boiling,add 4 drops of copper-EDTA (6.7) and 12 drops of PAN (6.8),and titrate while hot with standard EDTA to a clear yellow.8. Calculation8.1 Calculate th
22、e percent zinc oxide, A, as follows:A 5 L 3 M 3 0.08137 3 100/S (2)where:L = EDTA required for titration, mL,M = molarity of EDTA solution,S = specimen, g, and0.8137 = milliequivalent weight of zinc oxide.TOTAL PHOSPHORUS AS PHOSPHOROUS ACID9. Reagents9.1 Standard Phosphorus SolutionDissolve 0.9156
23、g ofsecondary sodium phosphate (Na2HPO4) in about 200 mL ofwater. Add 20 mL of nitric acid (sp gr 1.42), dilute to 1 L, andmix. 1 mL = 0.0002 g P.9.2 Ammonium Vanadate SolutionDissolve 2.5 g of am-monium vanadate (NH4VO3) in 500 mL of hot water. Whensolution is complete, add 10 mL nitric acid (sp gr
24、 1.42), cool,dilute to 1 L, and mix.9.3 Ammonium Molybdate SolutionDissolve 100 g ofammonium molybdate (NH4)6Mo7O244H2O in 800 mL ofwater and dilute to 1 L. Filter before use.9.4 Bromine, reagent grade.9.5 Bromine Water, distilled water saturated with bromine.9.6 Nitric Acid (sp gr 1.42), concentrat
25、ed nitric acid(HNO3).9.7 Nitric Acid (2:3)Dilute 200 mL of nitric acid (sp gr1.42) to 500 mL with water.10. Apparatus10.1 Photoelectric Colorimeter, either a single- or double-beam spectrophotometer with a wavelength capability of 465m.10.2 Volumetric Flasks, 100-mL.10.3 Tubes, 10-mm or 20-mm.10.4 F
26、ilter Paper, medium texture.11. Calibration Curve11.1 Transfer from a pipet 0.0, 1.0, 3.0, 7.0, 10.0, 15.0, and20.0-mL aliquots of standard phosphorus solution (9.1)toa100-mL volumetric flask. To each flask add 10 mL of nitricacid (9.7), 10 mL of ammonium vanadate (9.2), and 10 mL ofammonium molybda
27、te (9.3), dilute to the mark, and mix.Allowsolutions to stand 20 min and transfer to a 20-mm tube. Readthe absorbance of the solution at 465 m. Construct a calibra-tion curve for phosphorus by plotting the absorbance versusmilligrams of phosphorus in 100 mL of solution for eachstandard solution.12.
28、Procedure12.1 Weigh accurately 0.2 g of pigment and transfer to a150-mL beaker. Add 25 mL of bromine water (9.5), 10 mLnitric acid (9.6), and 0.5 mL bromine (9.4), and mix thesolution. Allow to stand in a warm place for about12 h, andthen gently boil off the bromine until the solution is clear.12.2
29、Cool the solution and transfer to a 100-mL volumetricflask. Make to the mark with water and mix.12.3 Pipet 10 mL of the solution into a 100-mL volumetricflask and add 10 mL nitric acid (9.7), 10 mL of ammoniumvanadate (9.2), and 10 mL of filtered ammonium molybdate(9.3).12.4 Dilute the sample to the
30、 mark, mix, and allow to standfor 20 min, and transfer to a 20-mm tube.12.5 Read the absorbance of the sample at 465 m and fromthe calibration curve, read the number of milligrams ofphosphorus in the test solution.12.6 Run a blank with the sample.13. Calculation13.1 Calculate the percent phosphorus
31、acid, C, as follows:C 5 A 2 B 3 2.646/S 3 10 (3)D 4450 85 (2007)2where:A = phosphorus in test solution, mg,B = phosphorus in reagent blank, mg,S = specimen in aliquot, g and2.646 = gravimetric factor to convert phosphorus to phos-phorous acid.14. Precision414.1 In an interlaboratory study of this te
32、st method, in whichtwo samples containing 18.5 to 19.0 % H3PO3and 77.0 to78.0 % ZnO were analyzed by one operator in each of fourlaboratories for H3PO3and five laboratories for ZnO, thewithin-laboratory and between-laboratories pooled standarddeviations, after discarding one days results from one la
33、bora-tory for both samples of ZnO (see Table 1). Based on thesestandard deviations, the following criteria should be used forjudging the acceptability of results at the 95 % confidencelevel:14.1.1 RepeatabilityTwo results, each the mean of tworuns, obtained by the same operator should be considereds
34、uspect if they differ by more than 0.65 % absolute at H3PO3contents of 18 to 20 % and more than 0.63 % absolute at ZnOcontents of 75 to 80 %.14.1.2 ReproducibilityTwo results, each the mean of tworuns, obtained by operators in different laboratories should beconsidered suspect if they differ by more
35、 than 1.78 % absolutefor H3PO3and 1.37 % absolute for ZnO at the same contents asin 14.1.1.15. Keywords15.1 phosphorus acid; pigment analysis; zinc; zinc hydroxyphosphite; zinc oxideASTM International takes no position respecting the validity of any patent rights asserted in connection with any item
36、 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 technical commi
37、ttee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a me
38、eting 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 Harbor Drive,
39、 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).4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D011048TABLE 1 Standard DeviationWithin-laboratory Between-laboratoryswDF sbDFH3PO30.198 8 0.515 6ZnO 0.193 8 0.42 8D 4450 85 (2007)3
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