ASTM_D_3873_-_01.pdf

Designation:D 3873 01Standard Test Method forValency State of the Arsenic Component of AmmoniacalCopper Zinc Arsenate Solutions1This standard is issued under the fixed designation D 3873;the number immediately following the designation indicates the year oforiginal adoption 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.1.Scope1.1 This test method is intended for testing batches ofconcentrated ammoniacal copper zinc arsenate(ACZA)solu-tion,prepared by air-oxidation of trivalent arsenic.The testmethod provides a means of confirming that oxidation has beencompleted and that at least 99.5%of the arsenic has beenoxidized.The sample for testing should contain 100 6 20 mgof potentialAs2O5.A200-mL aliquot of a concentrate contain-ing 8 to 12%of preservative oxides is suitable.1.2 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 use.2.Referenced Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water2D 1325 Specification for ACA and ACZA Solutions33.Summary of Test Method3.1 Twenty millilitres of tartaric acid solution is added to a250 mL Erlenmeyer flask,then 2 mL of the ACZA concentrateis added.The resulting solution should be light blue-green.Next,20 mL of sodium bicarbonate solution is added.Theresulting solution will then be light blue.Next,2 ml of thestarch indicator is added.To this solution one drop of iodinesolution is added by means of a buret.If the concentratesolution turns a dark blue and remains,it means the arsenicoxidation by aeration has been completed.4.Significance and Use4.1 This test method tests for the completion of oxidation byaeration which converts trivalent arsenic to pentavalent ar-senic.5.Reagents5.1 Purity of ReagentsReagent grade chemicals shall beused in 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.4Other grades may beused,provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.5.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water as definedin Specification D 1193.5.3 Iodine SolutionAdd 6.3 to 6.4 g of resublimed iodineto a 500-mL standard flask.Add 10 to 12 g of potassium iodideand not more than approximately 20 mL of water.Swirl thecontents of the flask at room temperature until all the iodine hasdissolved,and dilute to the graduation mark.This solution canbe kept for a few weeks if stored in a tightly sealed,glass-stoppered,dark bottle in a cool place.5.4 Sodium Bicarbonate Solution,SaturatedAdd 45 g ofsodium bicarbonate to 400 mL of water,and swirl occasionallyuntil most of the sodium bicarbonate goes into solution.Do notuse heat to dissolve the salt.This solution can be kept in astoppered flask.5.5 Starch Indicator SolutionMake a paste of approxi-mately 1.0 g of soluble starch in 5 mL of water.Pour the pasteinto 200 mL of water,near the boiling point,and then boil for1 min.When the solution has cooled,add a few drops ofchloroform as a preservative and keep in a stoppered bottle.Some batches of starch will not dissolve properly.If thesolution separates into two layers,use the clear,top layer.If thewhole solution is cloudy,prepare a fresh solution,or obtain adifferent supply of starch.5.6 Tartaric Acid SolutionDissolve 27 g of tartaric acid in400 mL of water.1This test method is under the jurisdiction of ASTM Committee D07 on Woodand is the direct responsibility of Subcommittee D07.06 on Treatments for WoodProducts.Current edition approved April 10,2001.Published June 2001.Originallypublished as D 3873 79.Last previous edition D 3873 95.2Annual Book of ASTM Standards,Vol 11.01.3Annual Book of ASTM Standards,Vol 04.10.4“Reagent Chemicals,American Chemical Society Specifications,”Am.Chemi-cal Soc.,Washington,DC.For suggestions on the testing of reagents not listed bytheAmerican Chemical Society,see“Reagent Chemicals and Standards,”by JosephRosin,D.Van Nostrand Co.,New York,NY,and the“United States Pharmacopeia.”1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.6.Procedure6.1 Take a sample of the ACZA concentrate and place in astoppered container(contact of the sample with air should bekept to a reasonable minimum or else misleading results couldbe obtained).Allow the sample to settle for at least 5 minbefore analysis.6.2 Add 20 mL of the tartaric acid solution to a 250-mLErlenmeyer flask.6.3 Using a rubber pipetting bulb,p