Designation:D2668−07(Reapproved2013)StandardTestMethodfor2,6-di-tert-Butyl-p-Cresoland2,6-di-tert-ButylPhenolinElectricalInsulatingOilbyInfraredAbsorption1ThisstandardisissuedunderthefixeddesignationD2668;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversthedeterminationoftheweightpercentof2,6-ditertiary-butylparacresol(DBPC)and2,6-ditertiary-butylphenol(DBP)inneworusedelectricalinsu-latingoilinconcentrationsupto0.5%bymeasuringitsabsorbanceatthespecifiedwavelengthsintheinfraredspec-trum.1.2ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2D923PracticesforSamplingElectricalInsulatingLiquidsD2144PracticesforExaminationofElectricalInsulatingOilsbyInfraredAbsorptionD3487SpecificationforMineralInsulatingOilUsedinElectricalApparatus3.SignificanceandUse3.1Thequantitativedeterminationof2,6-ditertiary-butylparacresoland2,6-ditertiary-butylphenolinanewelectricalinsulatingoilmeasurestheamountofthismaterialthathasbeenaddedtotheoilasprotectionagainstoxidation.Inausedoilitmeasurestheamountremainingafteroxidationhasreduceditsconcentration.Thetestisalsosuitableformanu-facturingcontrolandspecificationacceptance.3.2Whenaninfraredspectrumisobtainedofanelectricalinsulatingoilinhibitedwitheitherofthesecompoundsthereisanincreaseinabsorbanceofthespectrumatseveralwave-lengths(orwavenumbers).2,6ditertiary-butylparacresolpro-ducespronouncedincreasesinabsorbanceat2.72µm(3650cm−1),and11.63µm(860cm−1).2,6ditertiary-butylphenolpr...
