1、Designation: D444 88 (Reapproved 2014)Standard Test Methods forChemical Analysis of Zinc Yellow Pigment (Zinc ChromateYellow)1This standard is issued under the fixed designation D444; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 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.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 These test methods
3、cover procedures for the chemicalanalysis of the pigment known commercially as “zinc yellow”or “zinc chromate yellow.”1.2 The analytical procedures appear in the following order:SectionsMoisture and Other Volatile Matter 7Combined Water 8Chromium:Dichromate Method 911Thiosulfate Method 9, 12, and 13
4、Zinc:Hydroxyquinoline Method 9, 14, and 15Ferrocyanide Method 9, 16, and 17Alkaline Salts 18 and 19Sulfates 20 and 21Chlorides 22 and 23Matter Insoluble in Dilute AceticAcid24Coarse Particles 251.3 The values stated in SI units are to be considered thestandard. The values given in parentheses are fo
5、r informationonly.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 u
6、se.2. Referenced Documents2.1 ASTM Standards:2D185 Test Methods for Coarse Particles in PigmentsD280 Test Methods for Hygroscopic Moisture (and OtherMatter Volatile Under the Test Conditions) in PigmentsD478 Specification for Zinc Yellow (Zinc Chromate) Pig-mentsD1193 Specification for Reagent Water
7、E11 Specification for Woven Wire Test Sieve Cloth and TestSievesE50 Practices for Apparatus, Reagents, and Safety Consid-erations for Chemical Analysis of Metals, Ores, andRelated Materials3. Significance and Use3.1 This test method has been developed to standardize thechemical analysis of zinc chro
8、mate yellow pigment and toprovide alternate methods of analysis for chromium and zinc.4. Preparation of Sample4.1 Mix the laboratory sample thoroughly. Take a sufficientquantity for the chemical analyses and pass it through a180-m (No. 80) sieve, grinding in a mortar if necessary.NOTE 1Detailed requ
9、irements for this sieve are given in SpecificationE11.5. Reagents5.1 Purity of ReagentsUnless otherwise indicated, it isintended that all reagents shall conform to the specifications ofthe Committee onAnalytical Reagents of theAmerican Chemi-cal Society, where such specifications are available.3Othe
10、rgrades may be used, provided it is first ascertained that thereagent is of sufficiently high purity to permit its use withoutlessening the accuracy of the determination.5.2 Purity of WaterUnless otherwise indicated, referencesto water for use in the preparation of reagents and in analyticalprocedur
11、es shall conform to Type II reagent water, in Specifi-cation D1193.1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of Subcommittee D01.31 on Pigment Specifications.Current edition approved
12、 Dec. 1, 2014. Published December 2014. Originallyapproved in 1937. Last previous edition approved in 2008 as D444 88 (2008).DOI: 10.1520/D0444-88R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStand
13、ards 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
14、 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 States16. Precision6.
15、1 Precision statements have not been established.MOISTURE AND OTHER VOLATILE MATTER7. Procedure7.1 Determine moisture and other volatile matter in accor-dance with Test Method A of Test Methods D280.COMBINED WATER8. Procedure8.1 Weigh to 0.1 mg3goftheoven-dried material from thedetermination of mois
16、ture and other volatile matter (Note 2 andNote 3), and place in a porcelain boat. Introduce the boat withthe charge into a refractory combustion tube in an electrically-heated combustion furnace of the type used for the determina-tion of carbon in steel by direct combustion (Note 4). Place theboat a
17、t the center of the combustion tube maintained at atemperature of 1000C for 4 h. Draw a current of pure dry airor dry nitrogen through the tube to sweep the evolved moistureinto a previously weighed absorption tube containing anhy-drous magnesium perchlorate (Mg(ClO4)2) or other efficientdesiccant.
18、The weight increase of the absorption tube repre-sents the “combined water.”NOTE 2Loss on ignition of the pigment does not suffice for thedetermination of combined water in zinc yellow.NOTE 3If the pigment contains an organic treating agent, first removethis treating agent by washing with ether or c
19、hloroform.NOTE 4See Apparatus No. 1 for the determination of total carbon bydirect combustion as described in Practices E50.SPECIMEN SOLUTION FOR DETERMINATION OFCHROMIUM AND ZINC9. Procedure9.1 Weigh to 0.1 mg about a 4-g specimen and mix with 50mL of cold sulfuric acid (H2SO4) (1+5). It should dis
20、solvecompletely at this stage (Note 5). Dilute the solution to 500 mLin a volumetric flask.NOTE 5A cloudy solution may result if the pigment contains asurface-treating agent. In this case, it usually can be cleared by cooling inan ice-bath and filtering through a medium porosity fritted disk. If the
21、solution is not clarified by this treatment, extract a portion of the originalsample with a solvent such as chloroform before the analysis is begun.CHROMIUM BY THE DICHROMATE TESTMETHOD10. Reagents10.1 Ferrous Ammonium Sulfate SolutionDissolve 80 g offerrous ammonium sulfate (FeSO4 (NH4)2SO46H2O) in
22、 50mL of H2SO4(sp gr 1.84) and enough water to make 1 L ofsolution. Mix thoroughly before use. This solution is approxi-mately 0.2 N.10.2 Ortho-Phenanthroline Indicator Solution0.5 % inwater.10.3 Potassium Dichromate, Standard Solution(0.1 N)Dissolve 4.9035 g of dried potassium dichromate (K2Cr2O7)i
23、nwater and dilute to 1 L in a volumetric flask.11. Procedure11.1 Pipet 50 mL of the solution of the specimen (Section 7)into a 600-mL beaker. Add 200 to 250 mL of water and 10 mLof H2SO4(sp gr 1.84). Cool to 35C or below.11.2 Add an excess of ferrous ammonium sulfate solutionand back-titrate with 0.
24、1 N K2Cr2O7solution, using ortho-phenanthroline indicator. Carry out a blank titration of thesame amount of ferrous ammonium sulfate solution at the sametime and in the same manner.11.3 CalculationCalculate the percent of chromium C asCrO3, as follows:C 5 B12 V1!N130.03334/S13100where:B1=K2Cr2O7solu
25、tion required for titration of theblank, mL,V1=K2Cr2O7solution required for back-titration ofthe specimen, mL,N1= normality of the K2Cr2O7solution, andS1= specimen in the aliquot used, g.0.03334 = milliequivalents weight of CrO3.11.4 Alternatively, the solution of the specimen may betitrated directl
26、y with the ferrous ammonium sulfate solution,using an electrometric titration assembly to detect the endpoint. Standardize the ferrous solution against K2Cr2O7.CHROMIUM BY THE THIOSULFATE TESTMETHOD12. Reagents12.1 Potassium Iodide Solution (150 g/L)Dissolve 150 gof potassium iodide (KI) in water an
27、d dilute to 1 L.12.2 Sodium Thiosulfate, Standard Solution (0.1 N)Dissolve 24.8 g of sodium thiosulfate of (Na2S2O35H2O) in1 L of freshly boiled and cooled water contained in a sterileglass bottle. If sulfur precipitates during preparation or uponsubsequent use, discard the solution and prepare a ne
28、w one.Standardize against iodine.12.3 Starch Indicator SolutionStir up 2 to3gofpotatostarch with 100 mL salicylic acid solution (1 %), and boil themixture until the starch is practically dissolved, then dilute to1 L with water.13. Procedure13.1 Pipet a 25-mL aliquot of the solution of the specimen(S
29、ection 9) into a 500-mL glass-stoppered Erlenmeyer iodime-tric flask or other suitable glass-stoppered bottle containing 200mL of H2SO4(1+39). Add 20 mL of KI solution (150 g/L),stopper, and allow the solution to stand for approximately 5min.13.2 Titrate the liberated iodine with 0.1 NNa2S2O3solutio
30、nat room temperature until the reddish brown iodine colorbecomes quite faint. Add 5 mL of starch solution and continuethe titration until the final color change becomes pale greenwith no blue tinge. Titrate this final titration by swirling theflask at least three times after each addition of the Na2
31、S2O3D444 88 (2014)2solution, being sure that there is no further color change,especially at the final stage of the titration. The green end pointis definite and sharp.13.3 CalculationCalculate the percent of chromium C asCrO3as follows:C 5 V2N230.03334!/S2# 3100where:V2=Na2S2O3solution required for
32、titration of thespecimen, mLN2= normality of the Na2S2O3solution, andS2= specimen in the aliquot used, g.ZINC BY THE HYDROXYQUINOLINE TESTMETHOD(Suitable if No Interfering Substances Are Present)14. Reagents14.1 Acetone Solution of 8-Hydroxyquinoline (50 g/L)Dissolve5gof8-hydroxyquinoline in 100 mL
33、of acetone.15. Procedure15.1 Pipet 50 mL of the solution of the specimen (Section 9)into a 250-mL beaker and dilute to 100 mL with water. Add 5to 10 g of ammonium chloride (NH4Cl) and heat to boiling.Add a slight excess of ammonium hydroxide (NH4OH) and letstand a few minutes to allow any precipitat
34、e to coagulate. Filterthrough an ashless, rapid paper into a 400-mL beaker andwash.15.2 Heat the filtrate to boiling and add 5 mL of NH4OH (spgr 0.90). Add dropwise 10 mL of the acetone solution of8-hydroxyquinoline (Note 6). Let stand 10 to 20 min and filterthrough a medium-porosity sintered-glass
35、crucible. Wash wellwith water.NOTE 6The reagent is used in acetone solution rather than alcoholsolution to eliminate the danger of reducing some of the chromate byalcohol. Avoid adding an excess of reagent and lengthy boiling after itsaddition. Ten millilitres of hydroxyquinoline (50 g/L) is suffici
36、ent for anormal zinc yellow. The solution can be tested for complete precipitation,but since the reagent itself is rather insoluble, the results may bemisleading. The insoluble reagent will dissolve in a hot solution and alsoin an excess of alcohol or acetone, whereas the zinc oxyquinolate will not.
37、15.3 Dry the precipitate at 165C for at least 2 h and weighas zinc oxyquinolate.15.4 CalculationCalculate the percent zinc A as zincoxide (ZnO), as follows:A 5 P 30.2303!/S3# 3100where:P = zinc oxyquinolate, g, andS3= specimen in aliquot used, g.0.2303 = ZnO/zinc oxyquinolate = 81.38 353.37ZINC BY T
38、HE FERROCYANIDE TEST METHOD16. Reagents16.1 Methyl Orange Indicator SolutionDissolve 0.1 g ofmethyl orange in 100 mL of water.16.2 Potassium Ferrocyanide, Standard SolutionDissolve22 g of potassium ferrocyanide (K4Fe(CN)63H2O) in waterand dilute to 1 L. To standardize, transfer 0.2 g of metallic zin
39、cor freshly ignited ZnO to a 400-mL beaker. Dissolve in 10 mLof hydrochloric acid (HCl, sp gr 1.19) and 20 mL of water.Drop in a small piece of litmus paper, add ammoniumhydroxide (NH4OH) until slightly alkaline, then add HCl untiljust acid, and then 3 mL more of HCl. Dilute to about 250 mLwith hot
40、water and heat nearly to boiling. Run in theK4Fe(CN)6solution slowly from a buret, while stirringconstantly, until a drop tested on a white porcelain plate with adrop of the uranyl indicator solution shows a brown tinge afterstanding 1 min. Do not allow the temperature of the solution tofall below 7
41、0C during the titration. Run a blank using thesame amounts of reagents and water as in the standardization.The standardization must be made under the same conditionsof temperature, volume, and acidity as obtained when thespecimen is titrated. Calculate the strength of the K4Fe(CN)6solution in terms
42、of grams of zinc as follows:Z 5 W/V32 B2!where:Z = zinc equivalent of the K4Fe(CN)6solution, g/mL,W = zinc used (or equivalent to the ZnO used), g,V3=K4Fe(CN)6solution required for titration of thestandard, g, andB2=K4Fe(CN)6solution required for titration of the blank,mL.16.3 Thymol Blue Indicator
43、Solution (0.5 g/L)Dissolve0.1 g of thymol blue indicator in 200-mL of methanol, ethanol,or isopropanol.16.4 Uranyl Acetate Indicator Solution (50 g/L)Dissolve5gofUO2(C2H3O2)2H2O in water made slightly acid withacetic acid and dilute to 100 mL.17. Procedure17.1 Pipet 50 mL of the solution of the spec
44、imen (Section 9)into a 400-mL beaker. Add 35 mL of H2SO4(1+5) and 3 to 4drops of thymol blue indicator solution. First add NH4OH (spgr 0.90) and finally NH4OH (1+10) until the color of theindicator changes to a salmon shade intermediate between pinkand yellow. This gives a pH of about 2.4. Dilute th
45、e solution to300 mL and heat to just under boiling. Pass in H2Satamoderate rate for 40 min. Allow the precipitate to settle for 1h and filter. Wash the filter ten times with water saturated withhydrogen sulfide gas (H2S).17.2 Dissolve the precipitate in hot HCl (1+3) and wash thefilter paper well wi
46、th hot water. Boil out the H2S, neutralize tomethyl orange with NH4OH, and dilute to 300 mL. Add2gofNH4Cl and 3 mL of HCl (sp gr 1.19), and heat to boiling.17.3 Titrate the hot solution with K4Fe(CN)6solution(16.2), using uranyl acetate as an external indicator on a spotplate or 1 to 2 drops of ferr
47、ous ammonium sulfate solution asan internal indicator.17.4 CalculationCalculate the percent zinc A as ZnO, asfollows:A 5 V4Z/S4! 3100D444 88 (2014)3where:V4=K4Fe(CN)6solution required for titration of thespecimen, mL,Z = ZnO equivalent of the K4Fe(CN)6solution, g/mL, andS4= specimen in the aliquot u
48、sed, g.ALKALINE SALTS18. Reagents18.1 Gelatin Solution (0.2 g/L)Dissolve 0.2 g of low-ashgelatin in water and dilute to 1 L.18.2 Lead Acetate Solution (100 g/L)Dissolve 117 g ofPb(C2H3O2)23H2O in water and dilute to 1 L.19. Procedure19.1 Dissolve exactly1g(Note 7) of a specimen in 10 mLof acetic aci
49、d (1+1) and add 25 mL of water. Heat untildissolved. Dilute to 250 mL and heat to boiling. Add 20 mL oflead acetate solution (100 g/L) and allow the precipitate tosettle. Filter and wash the precipitate with hot water.NOTE 7The specimen should not be greater than 1 g because above 1g the loss in alkali metals due to adsorption on the precipitate becomesexcessive.19.2 Saturate the filtrate with hydrogen sulfide (H2S) for 40min. Add 10 mL of gelatin solution (0.2 g/L) and stirvigorously. Filter and wash with H2S water acidified with a f
