1、Designation: D 126 87 (Reapproved 2006)Standard Test Methods forAnalysis of Yellow, Orange, and Green Pigments ContainingLead Chromate and Chromium Oxide Green1This standard is issued under the fixed designation D 126; the number immediately following the designation indicates the year oforiginal ad
2、option or, in the case of revision, 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.
3、1. Scope1.1 These test methods cover procedures for the chemicalanalysis of yellow, orange, and green pigments containing leadchromate and chromium oxide green.1.2 The analytical procedures appear in the following order:SectionsCHROME YELLOW,CHROME ORANGE, AND MOLYBDATE ORANGEOrganic Colors and Lake
4、s 7Moisture and Other Volatile Matter 8Matter Soluble in Water 9Lead Chromate 10 and 11Total Lead 12Sulfate 13 and 14Carbon Dioxide 15Molybdenum 16 and 17Extenders 18-22Calculation of Substances Other than Insoluble LeadCompounds 23 and 24PURE CHROME GREEN AND REDUCED CHROME GREENOrganic Colors and
5、Lakes 25Moisture and Other Volatile Matter 26Matter Soluble in Water 27Iron Blue 28Lead Chromate 29 and 30Barium Sulfate and Insoluble Siliceous Material 31Total Lead 32Sulfate 33Calcium Oxide Soluble in Acid 34 and 35Extenders 36Calculation of Insoluble Lead Com-pounds 37CHROMIUM OXIDE GREENOrganic
6、 Colors and Lakes 38Moisture and Other Volatile Matter 39Matter Soluble in Water 40Total Chromium as Chromium Oxide 411.3 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 thesa
7、fety problems, 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. Specific hazardstatements are given in Note 3.2. Referenced Documents2.1
8、 ASTM Standards:2D 280 Test Methods for Hygroscopic Moisture (and OtherMatter Volatile Under the Test Conditions) in PigmentsD 521 Test Methods for Chemical Analysis of Zinc Dust(Metallic Zinc Powder)D 1013 Test Method for Determining Total Nitrogen inResins and PlasticsD 1193 Specification for Reag
9、ent WaterE11 Specification for Wire Cloth and Sieves for TestingPurposes3. Summary of Test Methods3.1 Chrome Yellow, Chrome Orange, and Molybdate Or-ange:3.1.1 Organic colors and lakes are determined qualitativelyby boiling the sample in water, then ethyl alcohol, and finallychloroform.3.1.2 Moistur
10、e and other volatile matter are determined inaccordance with Test Method A of Test Methods D 280.3.1.3 Matter soluble in water is determined by boiling inwater and filtering.3.1.4 Lead chromate is determined by dissolving the samplein dilute HCl, filtering and titrating potentiometrically withFeSO4s
11、olution after addition of HClO4.3.1.5 Total lead is determined by precipitation as leadsulfide solution with H2SO4and final precipitation as leadsulfate.3.1.6 Sulfate is determined by dissolving the sample inacetic acid, neutralizing with sodium carbonate, plus additionof HCl to an aliquot followed
12、by addition of BaCl2toprecipitate as barium sulfate.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 Nov. 1, 2006.
13、Published November 2006. Originallyapproved in 1922. Last previous edition approved in 2002 as D 126 87 (2002).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 s
14、tandards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.7 Carbon dioxide is determined by evolution.3.1.8 Molybdenum is determined by precipitation as thesulfide, solution in HNO3and H2SO
15、4, addition of NH4OH andH2SO4. The solution is reduced in a Jones reductor, collectedunder Fe2(SO4)3solution and titrated with KMnO4solution.3.1.9 Extenders are either:3.1.9.1 Calcium carbonate, calcium sulfate, magnesium car-bonate or;(a) The compounds in 3.1.9.1 are determined qualitativelyby prec
16、ipitation with ammonium solution.(b) If chromium is present, it is reduced and the lead saltsdissolved in dissolving solution. Hydroxides and hydrousoxides are precipitated by addition of HCl and NH4OH andfiltered. CaC2O4is precipitated with calcium oxalate solutionand filtered, ashed and weighed as
17、 CaO. Alternatively, theprecipitate is dissolved in H2SO4and titrated with KMnO4.Magnesium is determined on the filtrate from calcium deter-mination by precipitation as the phosphate with ammoniumphosphate solution.3.2 Chromium Oxide Green:3.2.1 Organic colors and lakes are determined qualitativelyb
18、y boiling the sample in water, then ethyl alcohol, and finallycholoroform.3.2.2 Moisture and other volatile matter are determined inaccordance with Test Method A of Test Methods D 280.3.2.3 Matter soluble in water is determined by boiling inwater and filtering.3.2.4 Total chromium as chromium oxide
19、is determined bydissolving the sample in dilute HCl, filtering and titratingpotentiometrically with FeSO4solution after addition ofHClO4.4. Significance and Use4.1 These test methods are for analysis designed as an aid inquality of yellow, orange, and green pigments containing leadchromate and chrom
20、ium oxide green. Some sections may beapplicable to analysis of these pigments when extracted fromwhole paints.5. Purity of Reagents and Water5.1 ReagentsUnless otherwise indicated, it is intendedthat all reagents shall conform to the specifications of theCommittee on Analytical Reagents of the Ameri
21、can ChemicalSociety, where such specifications are available.3Other gradesmay be used, provided it is first ascertained that the reagent isof sufficiently high purity to permit its use without lesseningthe accuracy of the determination.5.2 WaterUnless otherwise indicated, references to waterfor use
22、in the preparation of reagents and in analyticalprocedures shall be understood to mean reagent water con-forming to Type II of Specification D 1193.6. Preparation of Sample6.1 Mix the sample thoroughly and take a representativeportion for analysis. Reduce any lumps or coarse particles to afine powde
23、r by grinding. Grind extracted pigments to pass aNo. 80 (180-m) sieve (Note 1). Discard any skins that do notpass through the sieve. Thoroughly mix the finely groundpigment and preserve in stoppered and suitably identifiedbottles or containers.NOTE 1Detailed requirements for this sieve are given in
24、SpecificationE11.6.2 Moisten the weighed portions of extracted pigmentswith a small amount of suitable wetting agent (Note 1) beforeadding reagents for analysis.NOTE 2A 0.1 % solution of sodium dioctylsuccinosulfonate has beenfound satisfactory. (This material is sold under the trade name of Aerosol
25、OT.) Wetting agents containing mineral salts, sulfates, or sulfonates whichmay be hydrolyzed to sulfates, should be avoided; the use of alcohol isalso undesirable because of its tendency to reduce chromates.NOTE 3Warning: As the National Institute for Occupational Safetyand Health has stated that he
26、xavalent chromium compounds are hazardousto health, care should be exercised in preparation of the sample. Thewearing of a respirator and rubber or synthetic gloves are recommended.If hexavalent chromium materials come in contact with the skin, washthoroughly with soap and water.CHROME YELLOW, CHROM
27、E ORANGE, AND MOLYBDATE ORANGE(Primrose, Lemon, and Medium Yellows; Chrome Oranges; Lead Molybdate or Basic Lead Chromate; Molybdate Orange)ORGANIC COLORS AND LAKES7. Procedure7.1 Boil 2 g of the sample 2 min with 25 mL of water, letsettle, and decant the supernatant liquid. Similarly, boil theresid
28、ue with 25 mL of ethyl alcohol (absolute or 95 %) anddecant as before. Likewise boil with 25 mL of chloroform andagain decant. If any one of the above solutions is colored,organic colors are present. If all solutions remain colorless,organic colors are presumably absent. The presence of organic3Reag
29、ent 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 Pharmacopeiaa
30、nd National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D 126 87 (2006)2colors resistant to the above reagents is unlikely, but may betested for by reference to procedures given in standard refer-ence works.4MOISTURE AND OTHER VOLATILE MATTER8. Procedure8.1 Determine moisture
31、 and other volatile matter in accor-dance with Test Method A of Test Methods D 280.MATTER SOLUBLE IN WATER9. Procedure9.1 Place 2.5 g of the sample in a graduated 250-mL flask.Add 100 mLof water and boil for 5 min. Cool, dilute to exactly250 mL, mix, and allow to settle. Filter the supernatant liqui
32、dthrough a dry paper and discard the first 20 mL. Evaporate 100mL of the clear filtrate to dryness in a weighed dish, heat for 1h at 105 to 110C, cool, and weigh.9.2 CalculationCalculate the % of matter soluble in wateras follows:Matter soluble in water, % 5 R 3 2.5 3 100!/S (1)where:R = weight of r
33、esidue, andS = specimen weight, g.LEAD CHROMATE510. Reagents10.1 Dissolving SolutionSaturate 1 L of water with NaCl.Filter.Add to the filtered solution 150 mLof water and 100 mLof HCl (sp gr 1.19).10.2 Ferrous Sulfate, Standard Solution (0.3 N)Dissolve86 g of FeSO47H2O in 500 mL of water to which 30
34、 mL ofH2SO4(sp gr 1.84) has been added with constant stirring.Dilute to 1 L and standardize not more than 6 h before use bypotentiometric titration against 0.7-g portions of K2Cr2O7.11. Procedure11.1 Dissolve1gofthesample in 150 mL of the dissolvingsolution. Agitate for 10 to 15 min, keeping the sol
35、ution colduntil dissolution is complete (Note 4). If dissolution is notcomplete, filter through fine grade filter paper and wash withthree 10-mLportions of cold dissolving solution.Add 10 mLofHClO4(70 %), dilute to 250 mL, and titrate potentiometricallywith FeSO4solution.NOTE 4Incomplete solution of
36、 the pigment is evidence of the possiblepresence of barium sulfate, silica, silicates, or other acid-insolubleextenders (see Section 18). Some chrome yellows may contain organicaddition agents and will give a turbid solution at this point.Newer chemically resistant-type lead chromate type pigments (
37、silicaencapsulated) cannot be decomposed by the procedures described in thismethod. Pigments of this type may require treatment with strong alkalihydroxide or hydrofluoric acid.Also, if trivalent antimony has been used in manufacturing the product,pentavalent antimony may be present which would inte
38、rfere in thedetermination of lead chromate.11.2 Alternatively, the solution may be reduced by a knownexcess of FeSO4solution and back-titrated with KMnO4solution in the presence of MnSO4, or excess KI may be addedand the liberated iodine titrated with Na2S2O3solution, usingstarch indicator. The iodi
39、ne liberation method is not applicablein the presence of molybdenum.TOTAL LEAD512. Procedure12.1 Dissolve 0.5 g of sample as described in Section 11.Add 5 mLof ethyl alcohol (95 % or absolute) and boil until thechromium is reduced, as indicated by a green color. Filter ifany insoluble residue is pre
40、sent, retaining the filtrate andwashings for the determination. Add NH4OH (sp gr 0.90) tothis solution until a faint precipitate begins to form; then add 5mL of HCl (sp gr 1.19) slowly, dilute to 500 mL, and pass arapid current of H2S into the solution until precipitation iscomplete. Settle, filter,
41、 and wash with water containing H2S.12.2 Rinse the precipitate from the filter (Note 5) into abeaker containing 25 mL of HNO3(1+3) and boil until all PbShas dissolved. Add 10 mL of H2SO4(1+1) and evaporate tostrong fumes of SO3. Cool and add 50 mL of water and 50 mLof ethyl alcohol (95 %) (Note 6).
42、Let stand 1 h; then filter ona tarred Gooch crucible. Wash with ethyl alcohol (95 %), dry,ignite at 500 to 600C, and weigh as PbSO4.NOTE 5If a trace of sulfide remains on the paper, the stained portionof the paper may be separately treated with bromine water, the paperfiltered off, and the filtrate
43、added to the body of the solution.NOTE 6Any sulfur remaining from decomposition of the sulfides maybe mechanically removed as a globule of solidified sulfur at this point.SULFATE513. Reagents13.1 Barium Chloride SolutionDissolve 117 g of BaCl22H2O in water and dilute to 1 L.13.2 Dissolving SolutionS
44、ee 10.1.13.3 Sodium Carbonate Solution (saturated)Prepare asolution containing excess Na2CO3at laboratory temperature,and free of SO4. Decant the clear solution for use as required.14. Procedure14.1 Digest 1.25 g of the sample with 100 mL of dissolvingsolution at 100C for 5 min. Add 25 mL of glacial
45、 acetic acidand 15 mL of ethyl alcohol and heat gently for 10 min toreduce chromium, as indicated by the green color of thesolution. Cool. Neutralize with saturated Na2CO3solution andadd a slight excess. Transfer to a 250-mL volumetric flask,dilute to the mark with distilled water, and mix. Filter w
46、ithoutwashing through a dry filter paper, discarding the first 10 to 15mL.14.2 Take a 200-mL aliquot of the filtrate, neutralize withHCl (1+1), and add 10 mL excess. Heat to boiling and boil for5 min. To the gently boiling solution, add 15 mL of BaCl24Reference may be made to the following: Payne, H
47、. F., “Organic CoatingsTechnology,” Vol II, John Wiley then add 10 mL of H2SO4(sp gr 1.84).17.3 Cool the solution and reduce by passing through aJones reductor at a rate not exceeding 100 mL/min, collectingthe effluent under 200 mL of Fe2(SO4)3solution. Titrate withKMnO4solution. A blank determinati
48、on should also be made.EXTENDERS518. General Considerations18.1 Extenders fall into two groups, depending on theirsolubility or insolubility in the dissolving solution described inSection 10, as follows:A. Extenders Soluble in Dissolving SolutionCalcium sul-fate (gypsum), calcium carbonate (whiting)
49、, and magnesiumcarbonate.B. Extenders Insoluble in Dissolving SolutionSilica, mag-nesium silicate, and clay (Note 7).18.2 Extenders of group A may be present if the analysisshows sulfates and carbonates to be in the pigment, and areabsent if sulfate and carbonate are absent. Since the lattersituation rarely exists, it is advisable to test for the presence ofcalcium and magnesium to determine if extenders are present.Extenders of group B are recognized as an insoluble residuefollowing acid solution of the pigment, and may be determinedquantitatively if desired,
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