ASTM_D_1959_-_97.pdf

Designation:D 1959 97Standard Test Method forIodine Value of Drying Oils and Fatty Acids1This standard is issued under the fixed designation D 1959;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.This standard has been approved for use by agencies of the Department of Defense.1.Scope1.1 This test method covers the Wijs procedure for deter-mination of unsaturation(iodine value)in drying oils.It isapplicable to all natural and synthetic drying oils and their fattyacids.1.2 When the iodine value is determined on oils or fattyacids having conjugated systems,the result is not a measure oftotal unsaturation,but rather is an empirical value that affordsa comparison of total unsaturation.1.3 To obtain the total iodine value on conjugated samples,use Test Method D 1541.NOTE1This test method is essentially equivalent to Test MethodsD 2075 and D 2078.1.4 This standard may involve hazardous materials,opera-tions,and equipment.This standard does not purport toaddress all of the safety problems associated with its use.It isthe responsibility of the user of this standard to establishappropriate safety and health practices and determine theapplicability of regulatory limitations prior to use.For specifichazard statements,see Section 8.2.Referenced Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water2D 1541 Test Method for Total Iodine Value of Drying Oilsand Their Derivatives3D 2075 Test Method for Iodine Value of Fatty Amines,Amidoamines,and Diamines3D 2078 Test Method for Iodine Value of Fatty QuarternaryAmmonium Chlorides3D 5768 Test Method for Iodine Value of Tall Oil FattyAcids33.Terminology3.1 Definitions:3.1.1 iodine valuea measure of the unsaturation of oilsand fatty acids and is expressed in terms of the number ofcentigrams of iodine per gram of sample(weight percent ofabsorbed iodine).3.1.1.1 DiscussionTotal unsaturation of conjugated sys-tems may be measured in accordance with Test MethodD 1541.The Wijs iodine value method is not reliable for tall oilfatty acids containing an appreciable quantity of rosin acids.4.Summary of Test Method4.1 The determination of the iodine value of oils containingisolated double bonds is based on the absorption of halogenunder conditions selected to promote stoichiometrical results.5.Significance and Use5.1 This test method measures the unsaturation as iodinevalue by addition of an iodine/chlorine reagent.The amount ofreagent absorbed is determined by back titrating the excessreagent and comparing it to a blank determination.5.2 In samples containing conjugated double bonds,theiodine value obtained is empirical since the reagent does notreact stoichiometrically with conjugated unsaturation.Whereno conjugation is present,the iodine value obtained is ameasure of the total unsaturation.By using proper specimenweights,the empirical values obtained are useful for compara-tive purposes.6.Apparatus6.1 BottlesGlass-stoppered bottles or wide-mouth(Note2)Erlenmeyer flasks of 500-mL capacity.NOTE2Wide-mouth bottles or flasks are essential if stirring is doneby mechanical means.6.2 Pipets,20 and 25-mL capacity.7.Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests unless otherwise specified.Unless otherwiseindicated,it is intended that all reagents shall conform to theSpecifications of the Committee on Analytical Reagents of the1This test method is under the jurisdiction of ASTM Committee D-1 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D 01.32 on Drying Oils.Current edition approved Aug.10,1997.Published October 1997.Originallypublished as D 1959 61.Last previous edition D 1959 85.2Annual Book of ASTM Standards,Vol 11.01.3Annual Book of ASTM Standards,Vol 06.03.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTMAmerican Chemical Society,where such specifications areavailable.4Other grades may be used provided it is firstascertained that the reagent is of sufficiently high purity topermit its use without lessening the accuracy of the determi-nation.7.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water conformingto Type I of Specification D 1193.7.3 Acetic Acid(Glacial)(Cautionsee 8.1)Verify theabsence of substances reducing permanganate as follows:Dilute 2 mL of the acid with 10 mL of water and add 0.1 mLof 0.1 N potassium permanganate(KMnO4)solution.The pinkcolor should not be entirely discharged at the end of 2 h.57.4 Solvent:isooctane or fresh cyclohexane to replace longused carbon tetrachloride,now banned as too hazardous(CautionSee 8.2).7.5 Carbon Tetrachloride(CCl4)(CautionSee 8.2).7.6 Chlorine(99