Designation:D1681−05(Reapproved2014)StandardTestMethodforSyntheticAnionicActiveIngredientinDetergentsbyCationicTitrationProcedure1ThisstandardisissuedunderthefixeddesignationD1681;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Directtitrationofananionicsurfactantwithastandard-izedcationicreagentisasimpleandconvenientmethodforthequantitativedeterminationofthecontentofactiveingredient.Theendpointisdetffectedbythetransferofacoloredcomplexfromanorganicsolventphasetoanaqueousphase.Therelationshipbetweenanionicandcationicagentsisnotalwaysstoichiometric,andformaximumaccuracytheanionictypeofinterestshouldfirstbecharacterizedandthenusedtostandard-izethecationicreagent.Inmostcases,however,thedifferentanionicsurfactantslikelytobeencounteredreactinthesameproportions.Thatis,acationictitratingsolutionstandardizedagainstacharacterizedanionicagentcanbeusedtoanalyzeotheranionicsofknownmolecularweights.1.2Thistestmethodisapplicabletoalkylarylsulfonatesandfattyalkylsulfates.Lowresultsareobtainedwithalkyl-benzenesulfonateshavingthealkylchainlengthlessthaneightcarbonatoms.Lowresultsarealsoobtainedforalkylsulfateswiththealkylchainlengthoflessthantwelvecarbonatoms.TheanionicsurfactantscharacterizedinaccordancewithSections17–23shouldbethesodiumsaltandnotamine,ammonium,orpotassiumsalts.Incaseonlyamineorammo-niumsaltsareavailable,theyshouldbefirstconvertedtothesodiumsaltbeforeproceedingwiththisanalysis.1.3Theanalyticalproceduresappearinthefollowingorder:SectionsSeparationofAlcohol-SolubleMatter8and9SeparationofOil-FreeSulfonate10and11DeterminationofSodiumChloride(NaCl)Content12–17CharacterizationofAnionicSurfactantStandard:PartI.DeterminationofSurfactant,SO3Content,andSolutionMolarity18–20PartII.DeterminationofSurfactant,SO3andActiveIngredientContentsCombiningWeight,an...
