1、Designation:D235285(Reapproved 2015)Standard Test Method forSulfur Dioxide in White Pigment Separated from Solvent-Reducible Paints1This standard is issued under the fixed designation D2352;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revi
2、sion,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 covers the determination of sulfurdioxide in white pigment separated from solvent-reducib
3、lepaints.1.2 This test method is not applicable in the presence ofsulfides decomposable under the conditions given.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafet
4、y 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 Water
5、D2371 Test Method for Pigment Content of Solvent-Reducible Paints3.Summary of Test Method3.1 The extracted pigment is placed in a flask and thensulfur dioxide(SO2)is released by addition of hydrochloricacid(HCl)and bubbled through an absorption flask containingiodine solution and potassium iodide(KI
6、).The solution istitrated with sodium thiosulfate(Na2S2O3)using starch indi-cator.3.2 A blank is run as directed in 3.1 with the pigmentomitted.The blank is then subtracted from the figure obtainedfor the sample titration and SO2is calculated.4.Significance and Use4.1 Calcium sulfate pigments such a
7、s titanium-calcium havebeen used in paints in varying degrees in the past years.Assuch it is useful to the formulator and the user to be able tomonitor the amount of this compound in whole paints.5.Reagents5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indic
8、ated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused,provided it is first ascertained that the reagent is ofsufficiently high purity to permi
9、t its use without lessening theaccuracy of the determination.5.2 Unless otherwise indicated,references to water shall beunderstood to mean Type II reagent grade water,in accordancewith Specification D1193.5.3 Hydrochloric Acid(1+3)Mix 1 volume of concen-trated hydrochloric acid(HCl,sp gr 1.19)with 3
10、 volumes ofwater.5.4 Iodine,Standard Solution(0.05 N)(for SO2)Place 15to 20 g of pure potassium iodide(KI)in a 1-L flask,dissolvein as little water as possible,and then add about 6.4 g ofresublimed iodine.Shake until the iodine is all dissolved,diluteto the mark with water,and mix.Standardize the so
11、lutionagainst 0.05 N Na2S2O3solution to obtain its true normality.5.5 Potassium Iodide Solution(100 g/L)Dissolve 100 g ofpotassium iodide(KI)in water and dilute to 1 L.5.6 Sodium Thiosulfate,Standard(0.05 N)Solution(forSO2)Dissolve pure sodium thiosulfate Na2S2O3in water(that has been well boiled to
12、 free it from carbon dioxide)in theproportion of 12.42 g of Na2S2O35H2O to 1 L of the solution.It is best to let this solution stand for about two weeks before1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct r
13、esponsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved June 1,2015.Published June 2015.Originallyapproved in 1965.Last previous edition approved in 2010 as D2352 85(2010).DOI:10.1520/D2352-85R15.2For referenced ASTM standards,visit the ASTM we
14、bsite,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
15、 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 Dr
16、ive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 standardizing.Standardize4with pure resublimed iodine,purepotassium biiodate,or pure potassium iodate.This solution willbe approximately 0.05 N,and it is best to leave it as it is afterdetermining its exact iodine value,rather than to attempt toadjust it to exactly 0.05 N.Preserve in a stock bottle providedwith a guard tube filled with soda lime.5.7 Starch Indicator SolutionMake a homogenous pasteof 10 g of soluble starch in cold wat
