EPA 9250 CHLORIDE (COLORIMETRIC, AUTOMATED FERRICYANIDE AAI)

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1、METHOD9250CHLORIDE(COLORIMETRIC,AUTOMATEDFERRICYANIDEAAI)1.0SCOPEANDAPPLICATION1.1Thisautomatedmethodisapplicabletogroundwater,drinking,surface,andsalinewaters,anddomesticandindustrialwastes.Theapplicablerangeis1to250mgClperliterofsample.2.0SUMMARYOFMETHOD2.1Thiocyanateion(SCN)isliberatedfromme

2、rcuricthiocyanatethroughsequestrationofmercurybychlorideiontoformun-ionizedmercuricchloride.Inthepresenceofferricion,theliberatedSCNformshighlycoloredferricthiocyanateinaconcentrationproportionaltotheoriginalchlorideconcentration.3.0INTERFERENCES3.1Nosignificantinterferences.4.0APPARATUSANDMATE

3、RIALS4.1Automatedcontinuous-flowanalyticalinstrument:4.1.1SamplerI.4.1.2Continuousfilter.4.1.3Manifold.4.1.4Proportioningpump.4.1.5Colorimeter:equippedwith15-mmtubularflowcelland480-nmfilters.4.1.6Recorder.5.0REAGENTS5.1ASTMTypeIIwater(ASTMD1193):Watershouldbemonitoredforimpurities.5.2Ferricamm

4、oniumsulfate:Dissolve60gofFeNH4(SO4)2@12H2Oinapproximately500mLTypeIIwater.Add355mLofconcentratedHNO3anddiluteto1literwithTypeIIwater.Filter.92501CD-ROMRevision0DateSeptember19865.3Saturatedmercuricthiocyanate:Dissolve5gofHg(SCN)2in1literofTypeIIwater.Decantandfilteraportionofthesaturatedsupern

5、atantliquidtouseasthereagentandrefillthebottlewithdistilledwater.5.4Sodiumchloridestocksolution(0.0141NNaCl):Dissolve0.8241gofpre-dried(140EC)NaClinTypeIIwater.Diluteto1literinavolumetricflask(1mL=0.5mgCl).5.4.1Prepareaseriesofstandardsbydilutingsuitablevolumesofstocksolutionto100.0mLwithTypeII

6、water.Thefollowingdilutionsaresuggested:StockSolution(mL)Concentration(mg/L)1.05.02.010.04.020.08.040.015.075.020.0100.030.0150.040.0200.050.0250.0Choosethreeoftheninestandardconcentrationsinsuchawaythatthechosenstandardswillbrackettheexpectedconcentrationrangeofthesample.6.0SAMPLECOLLECTION,PR

7、ESERVATION,ANDHANDLING6.1AllsamplesmusthavebeencollectedusingasamplingplanthataddressestheconsiderationsdiscussedinChapterNineofthismanual.6.2Nospecialrequirementsforpreservation.7.0PROCEDURE7.1Noadvancesamplepreparationisrequired