1、Designation: D 2352 85 (Reapproved 2005)Standard Test Method forSulfur Dioxide in White Pigment Separated from Solvent-Reducible Paints1This standard is issued under the fixed designation D 2352; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、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.1. Scope1.1 This test method covers the determination of sulfurdioxide in white pigment separated from s
3、olvent-reduciblepaints.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
4、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 use.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specificati
5、on for Reagent WaterD 2371 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 soluti
6、on and potassium iodide (KI). 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
7、 Calcium sulfate pigments such as 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 i
8、n all tests. Unless otherwise indicated, 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 i
9、s ofsufficiently high purity to permit 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 D 1193.5.3 Hydrochloric Acid (1 + 3)Mix 1 volume of concen-tra
10、ted hydrochloric acid (HCl, sp gr 1.19) with 3 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,
11、diluteto the mark with water, and mix. Standardize the solutionagainst 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
12、 sodium thiosulfate Na2S2O3in water(that has been well boiled to 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 Paintan
13、d Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved Jan. 1, 2005. Published February 2005. Originallyapproved in 1965. Last previous edition approved in 1999 as D 2352 85 (1
14、999).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 standards Document Summary page onthe ASTM website.3Reagent Chemicals, American Chemical Society Specificat
15、ions, 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 Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention,
16、 Inc. (USPC), Rockville,MD.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.standardizing. Standardize4with pure resublimed iodine, purepotassium biiodate, or pure potassium iodate. This solution willbe approximately 0.05 N, and it is
17、 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 water. Add to thi
18、s 1 L ofboiling water, stir rapidly, and cool. Salicylic acid (1.25 g/L)may be added to preserve the indicator. If long storage isrequired, the solution should be kept in a refrigerator at 4 to10C (40 to 50F). Prepare fresh indicator when the end pointof the titration from blue to colorless or blue
19、to light green failsto be sharp.6. Preparation of Sample6.1 Separate and prepare the pigment for this determinationin accordance with Test Method D 2371.7. Procedure7.1 Transfer 10 g of the pigment to a suitable flask, insert astopper fitted with a separatory funnel and a spray trap deliverytube (No
20、te 1), and attach the latter to a condenser. Place about150 mL of HCl (1 + 3) in the funnel, the stopcock being closed(Note 2), and connect the other end of the condenser with adelivery tube that passes through a two-hole stopper andextends nearly to the bottom of an absorption flask; through theoth
21、er hole of the stopper connect a tube or flask to serve as asafety device. Place 25 mL of 0.05 N iodine solution (5.4)inthe absorption flask (dilute with water if necessary) and 20 mLof KI solution (100 g/L) in the safety tube; fit the stopper in theabsorption flask. Open the stopcock and allow the
22、acid toslowly enter the flask. Before all of the acid is admitted, forceair (washed with sodium hydroxide (NaOH) solution) throughthe top of the separatory funnel (about 2 bubbles per second inthe KI solution). Boil the solution 3 min with air passingthrough then remove the source of heat and pass a
23、ir through for30 min.NOTE 1A Knorr CO2apparatus is very convenient. In this case, thevertical condenser may be connected with an absorption tower containingthe iodine solution, followed by the KI solution in a suitable tube.NOTE 2To minimize, if not eliminate, any possible oxidation by theair, add a
24、bout 1 g (in one piece) of sodium bicarbonate (NaHCO3)totheevolution flask, then add the acid directly to the flask, omitting theseparatory funnel and the current of air. Boil the solution until about 50mL of distillate has passed over.7.2 Disconnect the absorption vessels, wash the KI solutioninto
25、the iodine solution, and titrate at once with 0.05 NNa2S2O3solution using starch indicator. Run a blank determi-nation in exactly the same manner except for the omission ofthe pigment. Subtract the figure obtained for the blank deter-mination from the figure obtained for titration of the sampleand c
26、alculate the final result to SO2(1 mL 0.05 N io-dine = 0.0016 g SO2).8. Calculation8.1 Calculate the percent of sulfur dioxide, A, as follows:A 5 V 2 B!I/S 3 100where:V = 0.05 N iodine solution required for titration of speci-men, mL,B = 0.05 N iodine solution required for titration of theblank, mL,
27、I =SO2equivalent of the 0.05 N iodine solution, g/mL,andS = sample used, g.9. Precision9.1 Data are not available to determine the precision of thistest method. There are no plans at present to obtain such data.This test method has been in use for several years and isconsidered acceptable.10. Keywor
28、ds10.1 sulfate analysis; sulfur dioxide; white pigmentASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent r
29、ights, 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 committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either f
30、or revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair heari
31、ng 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, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard m
32、ay 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).4Buehrer, T. F., and Mason, C. M., “Thiosulfate, Standardization of,” AnalyticalChemistry, Vol 2, 1930, p. 138.D 2352 85 (2005)2
