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《EPA METHOD 9067 Phenolics (Spectrophotometric, MBTH with Distillation)》由會(huì)員上傳分享，免費(fèi)在線閱讀，更多相關(guān)內(nèi)容在行業(yè)資料-天天文庫(kù)。
1、METHOD9067PHENOLICS(SPECTROPHOTOMETRIC,MBTHWITHDISTILLATION)1.0SCOPEANDAPPLICATION1.1Thismethodisapplicabletotheanalysisofgroundwater,drinking,surface,andsalinewaters,anddomesticandindustrialwastes.1.2Themethodiscapableofmeasuringphenolicmaterialsatthe
2、2ug/Llevelwhenthecoloredendproductisextractedandconcentratedinasolventphaseusingphenolasastandard.1.3Themethodiscapableofmeasuringphenolicmaterialsthatcontainfrom50to1,000ug/Lintheaqueousphase(withoutsolventextraction)usingdifferentkindsofphenols.1.4It
3、isnotpossibletousethismethodtodifferentiatebetweendifferentkindsofphenols.2.0SUMMARYOFMETHOD2.1ThismethodisbasedonthecouplingofphenolwithMBTHinanacidmediumusingcericammoniumsulfateasanoxidant.Thecouplingtakesplaceinthep-position;ifthispositionisoccupie
4、d,theMBTHreagentwillreactatafreeo-position.Thecolorsobtainedhavemaximumabsorbancefrom460to595nm.Forphenolandmostphenolicmixtures,theabsorbanceis520and490nm.3.0INTERFERENCES3.1Formostsamplesapreliminarydistillationisrequiredtoremoveinterferingmaterials.
5、3.2ColorresponseofphenolicmaterialswithMBTHisnotthesameforallcompounds.Becausephenolic-typewastesusuallycontainavarietyofphenols,itisnotpossibletoduplicateamixtureofphenolstobeusedasastandard.Forthisreason,phenolhasbeenselectedasastandardandanycolorpro
6、ducedbythereactionofotherphenoliccompoundsisreportedasphenol.Thisvaluewillrepresenttheminimumconcentrationofphenoliccompoundspresentinthesample.3.3InterferencesfromsulfurcompoundsareeliminatedbyacidifyingthesampletoapHoflessthan4.0withH2SO4andaeratingb
7、rieflybystirring.3.4Oxidizingagentssuchaschlorine,detectedbytheliberationofiodineuponacidificationinthepresenceofpotassiumiodide,areremovedimmediatelyaftersamplingbytheadditionofanexcessofferrousammonium90671CD-ROMRevision0DateSeptember1986sulfate(seeP
8、aragraph5.11).Ifchlorineisnotremoved,thephenoliccompoundsmaybepartiallyoxidizedandtheresultsmaybelow.3.5Phosphatecausesaprecipitatetoform;therefore,phosphoricacidshouldnotbeusedforpreservation.Allglasswareshouldbephosphatefree.3.5Highco
