溴化容量法测定水质中挥发酚两种标准方法的比较

溴化容量法测定水质中挥发酚两种标准方法的比较1. IntroductionVolatile phenols (VPs) are a group of organic compounds that ca

溴化容量法测定水质中挥发酚两种标准方法的比较 1.Introduction Volatilephenols(VPs)areagroupoforganiccompoundsthat canbefoundinseveralwastewatersources,suchasindustrial effluentsoragriculturalrunoff.VPshavebeenidentifiedasa majorsourceofwaterpollutionduetotheirtoxicand carcinogenicproperties.Forthisreason,theEuropeanUnion(EU), theUnitedStatesEnvironmentalProtectionAgency(USEPA),and theWorldHealthOrganization(WHO)haveestablishedguidelines forthepermissiblelevelofVPsinwatersources. ThedeterminationofVPsinwaterisacriticalstepin assessingthequalityofwatersources.Severalanalyticalmethods havebeendevelopedforthequantificationofVPsinwater, includinggaschromatography(GC),high-performanceliquid chromatography(HPLC),andspectrophotometry.Amongthese methods,thebromineindex(BI)anddichromateindex(DI) methodsarewidelyusedtoassesstheconcentrationofVPsin watersources. 2.Bromineindex(BI)method TheBImethod,alsoknownasthebrominecapacitymethod, isoneofthemostcommonlyusedmethodsforthedetermination ofVPsinwater.Thistechniqueisbasedonthereactionbetween VPsandbromine,whichresultsintheformationofacomplexthat canbequantifiedusingspectrophotometry. TheBImethodinvolvesaddingaknownvolumeofbromine solutiontoawatersamplecontainingVPs.Thesampleisthen acidifiedandshakenforafewminutestoallowthereaction betweenbromineandVPstooccur.Theremainingbromineinthe solutionisthentitratedwithsodiumthiosulfatesolution,andthe BIvalueiscalculatedusingthefollowingequation: BI=(Vb×Cb×1000)/Vw WhereVbisthevolumeofbrominesolutionadded,Cbisthe concentrationofbrominesolution,andVwisthevolumeofthe watersample. TheBIvaluerepresentstheamountofbrominethatreacted withVPsandisproportionaltotheconcentrationofVPsinthe