ASTM_D_3401_-_97_2012.pdf

Designation:D340197(Reapproved 2012)Standard Test Methods forWater in Halogenated Organic Solvents and TheirAdmixtures1This standard is issued under the fixed designation D3401;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()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 These test methods describe the use of the Karl Fischer(KF)titration for determination of water in halogenated or-ganic solvents and mixtures thereof.Water concentrations from2 to 1000 ppm can be determined in these solvents.Two testmethods are covered as follows:1.1.1 Test Method A,Water Determination Using a Coulo-metric KF TitratorThe coulometric test method is known forits high degree of sensitivity(typically 10 g H2O)andshould be the test method of choice if water concentrations aretypically below 50 ppm or if only small amounts of sample areavailable for water determinations.This test method requiresthe use of equipment specifically designed for coulometrictitrations.1.1.2 Test Method B,Water Determination Using a Volumet-ric KF TitratorThe volumetric test method is a more tradi-tional approach to KF water determinations.Although titratorsare specifically designed for KF volumetric determinations,many automatic titrators on the market can be adapted toperform KF titrations.1.2 Either of these test methods can be used to determinetypical water concentrations(15 to 500 ppm)found in haloge-nated solvents.1.3 These test methods recommend the use of commerciallyavailable Karl Fischer titrators and reagents.1.4 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.For specificprecautionary statements,see Sections 11 and 15.2.Referenced Documents2.1 ASTM Standards:2E203 Test Method for Water Using Volumetric Karl FischerTitration3.Summary of Test Methods3.1 In the Karl Fischer reaction,water will react with iodinein the presence of sulfur dioxide,alcohol,and an organic baseaccording to the following equation:H2O1I21SO21CH3OH13RNRNH!SO4CH312RNH!I(1)where RN=organic base.3.2 When the volumetric titration test method is used forthis determination,the halogenated sample is added to a KFsolvent that usually consists of sulfur dioxide and an aminedissolved in anhydrous methanol.This solution is titrated withan anhydrous solvent containing iodine.The iodine titrant isfirst standardized by titrating a known amount of water.3.3 In the coulometric titration test method,the sample isinjected into an electrolytic cell where the iodine required forthe reaction with water is produced by anodic oxidation ofiodide.With this technique,no standardization of reagents isrequired.3.4 In both test methods,the end point is determinedamperometrically with a platinum electrode that senses a sharpchange in cell resistance when the iodine has reacted with allof the water in the sample.4.Significance and Use4.1 High water concentrations can have a detrimental effecton many uses of halogenated solvents.4.1.1 Water can cause corrosion and spotting when solventsare used for metal cleaning.1These test methods are under the jurisdiction of ASTM Committee D26 onHalogenated Organic Solvents and Fire Extinguishing Agents and are the directresponsibility of Subcommittee D26.04 on Test Methods.Current edition approved March 1,2012.Published June 2012.Originallyapproved in 1975.Last previous edition approved in 2006 as D3401 97(2006).DOI:10.1520/D3401-97R12.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.1.2 Water can reduce the shelf life of aerosol formula-tions.4.1.3 Water can inhibit desired reactions when solvents areused in formulations.5.Interferences5.1 Certain compounds or classes of compounds interferewith the accurate determination of water by the Karl Fischertest method.They include aldehydes,ketones,free halogens,ferric salts,and strong oxidizing and reducing agents.5.2 Free halogens can oxidize the iodate in the KF reagentsto form iodine;this causes erroneously low water values.5.3 A more detailed discussion of KF interferences can befound in Test Method E203 and other sources.3,46.Apparatus6.1 Coulometric Titrator,5(for Test Method A only)con-sisting of a single or dual bath electrolytic cell,dual platinumelectrode,magnetic stirrer,and control unit.6.2 Volumetric Titra