資源描述：
《EPA METHOD 9040C pH Electrometric Measurement》由會員上傳分享，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。
1、METHOD9040CpHELECTROMETRICMEASUREMENT1.0SCOPEANDAPPLICATION1.1ThismethodisusedtomeasurethepHofaqueouswastesandthosemultiphasewasteswheretheaqueousphaseconstitutesatleast20%ofthetotalvolumeofthewaste.1.2Thecorrosivityofconcentratedacidsandbases,orofconcentratedacidsandbasesmixedwithinertsubsta
2、nces,cannotbemeasured.ThepHmeasurementrequiressomewatercontent.2.0SUMMARY2.1ThepHofthesampleisdeterminedelectrometricallyusingeitheraglasselectrodeincombinationwithareferencepotentialoracombinationelectrode.ThemeasuringdeviceiscalibratedusingaseriesofstandardsolutionsofknownpH.3.0INTERFERENCE
3、S3.1Theglasselectrode,ingeneral,isnotsubjecttosolutioninterferencesfromcolor,turbidity,colloidalmatter,oxidants,reductants,ormoderate(<0.1molarsolution)salinity.3.2SodiumerroratpHlevels>10canbereducedoreliminatedbyusingalow-sodium-errorelectrode.3.3Coatingsofoilymaterialorparticulatemattercan
4、impairelectroderesponse.Thesecoatingscanusuallyberemovedbygentlewipingordetergentwashing,followedbyrinsingwithdistilledwater.Anadditionaltreatmentwithhydrochloricacid(1:10)maybenecessarytoremoveanyremainingfilm.3.4TemperatureeffectsontheelectrometricdeterminationofpHarisefromtwosources.Thefir
5、stiscausedbythechangeinelectrodeoutputatvarioustemperatures.Thisinterferenceshouldbecontrolledwithinstrumentshavingtemperaturecompensationorbycalibratingtheelectrode-instrumentsystematthetemperatureofthesamples.ThesecondsourceoftemperatureeffectsisthechangeofpHduetochangesinthesampleasthetemp
6、eraturechanges.Thiserrorissample-dependentandcannotbecontrolled.Itshould,therefore,benotedbyreportingboththepHandtemperatureatthetimeofanalysis.4.0APPARATUSANDMATERIALS4.1pHmeter--Laboratoryorfieldmodel.Manyinstrumentsarecommerciallyavailablewithvariousspecificationsandoptionalequipment.4.2Gl
7、asselectrode.4.3Referenceelectrode--Asilver-silverchlorideorotherreferenceelectrodeofconstantpotentialmaybeused.9040C-1Revision3November2004NOTE:Combinationelectrodesincorporatingbothmeasuringandreferencedfunctionsareconvenienttouseandareavai
