1、Designation: D 444 88 (Reapproved 2008)Standard Test Methods forChemical Analysis of Zinc Yellow Pigment (Zinc ChromateYellow)1This standard is issued under the fixed designation D 444; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 These test methods co
3、ver 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 9-11Thiosulfate 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:2D 185 Test Methods for Coarse Particles in PigmentsD 280 Test Methods for Hygroscopic Moisture (and OtherMatter Volatile Under the Test Conditions) in PigmentsD 478 Specification for Zinc Yellow (Zinc Chromate) Pig-mentsD 1193 Specification for Reagent W
7、aterE11 Specification for Wire Cloth and Sieves for TestingPurposesE50 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 c
8、hromate 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 r
9、equirements 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.3O
10、thergrades 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 analyticalproce
11、dures shall conform to Type II reagent water, in Specifi-cation D 1193.1These 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 appr
12、oved Feb. 1, 2008. Published February 2008. Originallyapproved in 1937. Last previous edition approved in 2003 as D 444 88 (2003).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informat
13、ion, 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 LaboratoryChemi
14、cals, 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.6. Precision6.1 Precision stateme
15、nts 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 D 280.COMBINED WATER8. Procedure8.1 Weigh to 0.1 mg3goftheoven-dried material from thedetermination of moisture and other vol
16、atile 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 at the center of th
17、e 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. The weight increas
18、e 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 chloroform.NOTE 4Se
19、e 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 dissolvecompletely at
20、 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 thesolution is not cl
21、arified 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 50mL of H2SO4(sp
22、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)inwater and dilute
23、 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 0.1 N K2Cr2O7soluti
24、on, 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!N13 0.03334/S13 100where:B1=K2Cr2O7solution required f
25、or 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 directly with the ferr
26、ous 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 and dilute to 1 L
27、.12.2 Sodium Thiosulfate, Standard Solution (0.1 N)Dissolve 24.8 g of sodium thiosulfate of (Na2S2O35H2O) in 1L of freshly boiled and cooled water contained in a sterile glassbottle. If sulfur precipitates during preparation or upon subse-quent use, discard the solution and prepare a new one.Standar
28、dize 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(Section 9) int
29、o a 500-mL glass-stoppered Erlenmeyer iodi-metric flask or other suitable glass-stoppered bottle containing200 mL 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 NNa2S2O3solutionat room tempe
30、rature 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 Na2S2O3solution,
31、being sure that there is no further color change,especially at the final stage of the titration. The green end pointis definite and sharp.D 444 88 (2008)213.3 CalculationCalculate the percent of chromium CasCrO3as follows:C 5 V2N23 0.03334!/S2# 3 100where:V2=Na2S2O3solution required for titration of
32、 the speci-men, 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 of acetone
33、.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 precipitate to coagu
34、late. 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 crucible.
35、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 sufficient for an
36、ormal 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.15.3 Dry t
37、he 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 3 0.2303!/S3# 3 100where:P = zinc oxyquinolate, g, andS3= specimen in aliquot used, g.0.2303 = ZnO/zinc oxyquinolate = 81.38/353.37ZINC BY THE FERRO
38、CYANIDE 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 zincor fres
39、hly 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 water an
40、d heat nearly to boiling. Run in theK4Fe(CN)6solution slowly from a buret, while stirring con-stantly, 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 70C dur
41、ing 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 of gra
42、ms 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 theblank, mL.16.3 Thymol Blue Indicator Soluti
43、on (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 specimen (
44、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 the solu
45、tion 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 with hot
46、 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 ferrous am
47、monium sulfate solution asan internal indicator.17.4 CalculationCalculate the percent zinc A as ZnO, asfollows:A 5 V4Z/S4! 3 100where:V4=K4Fe(CN)6solution required for titration of the speci-men, mL,Z = ZnO equivalent of the K4Fe(CN)6solution, g/mL, andS4= specimen in the aliquot used, g.D 444 88 (2
48、008)3ALKALINE 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 acid
49、(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 fewdrop
