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1、METHOD9022TOTALORGANICHALIDES(TOX)BYNEUTRONACTIVATIONANALYSIS1.0SCOPEANDAPPLICATION1.1Method9022determinesTotalOrganicHalides(TOX)inaqueoussamples.ThemethodusesacarbonadsorptionprocedureidenticaltothatofMethod9020(TOXanalysisusingamicrocoulometric-titrationdetector),irradiati
2、onbyneutronbombardment,andthendetectionusingagamma-raydetector.1.2Method9022detectsallorganichalidescontainingchlorine,bromine,andiodinethatareadsorbedbygranularactivatedcarbonundertheconditionsofthemethod.Eachhalogencanbequantitatedindependently.1.3Method9022isrestrictedtous
3、eby,orunderthesupervisionof,analystsexperiencedintheoperationofneutronactivationanalysisandfamiliarwithspectralinterferences.1.4Thismethod,whichmaybeusedinplaceofMethod9020,hastheadvantageofdeterminingtheindividualconcentrationsofthehalogenschlorine,bromine,andiodineinadditio
4、ntoTOX.2.0SUMMARYOFMETHOD2.1Asampleofwaterthathasbeenprotectedagainstthelossofvolatilesbytheeliminationofheadspaceinthesamplingcontainer,andthatisfreeofundissolvedsolids,ispassedthroughacolumncontaining40mgofgranularactivatedcarbon(GAC).Thecolumniswashedtoremoveanytrappedinor
5、ganichalides.TheGACsampleisexposedtothermalneutronbombardment,creatingaradioactiveisotope.Gamma-rayemission,whichisuniquetoeachhalogen,iscounted.Theareasoftheresultingpeaksaredirectlyproportionaltotheconcentrationsofthehalogens.3.0INTERFERENCES3.1Methodinterferencesmaybecause
6、dbycontaminants,reagents,glassware,andothersampleprocessinghardware.Allthesematerialsmustberoutinelydemonstratedtobefreefrominterferencesundertheconditionsoftheanalysisbyrunningmethodblanks.3.1.1Glasswaremustbescrupulouslycleaned.Cleanallglasswareassoonaspossibleafterusebytre
7、atingwithchromaticcleaningsolution.Thisshouldbefollowedbydetergentwashinginhotwater.Rinsewithtapwateranddistilledwateranddraindry;glasswarewhichisnotvolumetricshould,inaddition,beheatedinamufflefurnaceat90221CD-ROMRevision0DateSeptember1986400ECfor15to30min.Volumetricwareshou
8、ldnotbeheatedinamufflefurnace.Glasswareshouldbesealedandstoredinacle
