EPA METHOD 9036 Sulfate (Colorimetric, Automated, Methylthymol Blue, AA II)

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1、METHOD9036SULFATE(COLORIMETRIC,AUTOMATED,METHYLTHYMOLBLUE,AAII)1.0SCOPEANDAPPLICATION1.1Thisautomatedmethodisapplicabletogroundwater,drinkingandsurfacewaters,anddomesticandindustrialwastes.-21.2Samplesintherangeof0.5to300mgSO4/litercanbeanalyzed.2.0SUMMARYOFMETHO

2、D2.1Thesampleisfirstpassedthroughasodium-formcation-exchangecolumntoremovemultivalentmetalions.Thesamplecontainingsulfateisthenreactedwithanalcoholsolutionofbariumchlorideandmethylthymolblue(MTB)atapHof2.5-3.0toformbariumsulfate.ThecombinedsolutionisraisedtoapHof

3、12.5-13.0sothatexcessbariumreactswithMTB.TheuncomplexedMTBcolorisgray;ifitisallchelatedwithbarium,thecolorisblue.Initially,-2thebariumandMTBareequimolarandequivalentto30mgSO4/liter;thustheamountofuncomplexedMTBisequaltothesulfatepresent.3.0INTERFERENCES3.1Theion-

4、exchangecolumneliminatesinterferencesfrommultivalent++cations.Amid-scalesulfatestandardcontainingCashouldbeanalyzedperiodicallytoensurethatthecolumnisfunctioningproperly.3.2SampleswithpHbelow2shouldbeneutralizedbecausehighacidconcentrationselutecationsfromtheion-

5、exchangeresin.3.3Turbidsamplesshouldbefilteredorcentrifuged.4.0APPARATUSANDMATERIALS4.1Automatedcontinuous-flowanalyticalinstrument:4.1.1Sampler.4.1.2Manifold:High-orlow-level(Figure1).4.1.3Proportioningpump.4.1.4Heatingbath:Operableatthetemperaturespecified.4.1.

6、5Colorimeter:Equippedwith15mmflowcelland460nminterferencefilters.90361CD-ROMRevision0DateSeptember198690362CD-ROMRevision0DateSeptember19864.1.6Filters:Ofspecifiedtransmittance.4.1.7Recorder.5.0REAGENTS5.1ASTMTypeIIwater(ASTMD1193):Watershouldbemonitoredforimpuri

7、ties.5.2Bariumchloride:Dissolve1.526gofbariumchloridedihydrate.(BaCl22H2O)in500mLofTypeIIwateranddiluteto1liter.5.3Methylthymolblue:Dissolve0.1182gofmethylthymolblue(3'3"-bis-N,N-biscarboxymethyl-aminomethylthymolsulfone-phthaleinpentasodiumsalt)in25mLofbariumchl

8、oridesolution(Paragraph5.2).Add4mLof1.0Nhydrochloricacid,whichchangesthecolortobrightorange.Add71mLofwateranddiluteto500mLwithethanol.ThepHofthissolutionis2.6.