Liquid-phase microextraction–gas chromatography–mass spectrometry for the determination

JournalofChromatographyA,1148(2007)

145–151

Liquid-phasemicroextraction–gaschromatography–massspectrometryforthedeterminationofbromate,iodate,

bromideandiodideinhigh-chloridematrix

KishanReddy-Noone,ArchanaJain,KrishnaK.Verma

DepartmentofChemistry,RaniDurgavatiUniversity,Jabalpur482001,MadhyaPradesh,IndiaReceived24December2006;receivedinrevisedform5March2007;accepted7March2007

Availableonline16March2007

Abstract

Inthedeterminationofbromateandiodate,anyfreebromideandiodidepresentwasquantitativelyremovedbyanionexchangewithsilverchlorideexploitingthedifferencesinsilversaltssolubilityproduct,beingAgCl,1.8×10 10,AgBr,5.0×10 13,AgI,8.3×10 17,AgBrO3,5.5×10 5andAgIO3,3.1×10 8.Theoxyhalideswerereducedwithascorbicacidtohalidesandconvertedto4-bromo-2,6-dimethylanilineand4-iodo-2,6-dimethylanilinebytheirreactionwith2-iodosobenzoateinthepresenceof2,6-dimethylanilineatpH6.4and2–3,respectively.Singledropmicroextraction(SDME)ofthehaloanilinesin2 loftolueneandinjectionofthewholeextractintoGC–MS,orliquid-phasemicroextraction(LPME)into50 loftolueneandinjectionof2 lofextract,resultedinasensitivemethodforbromateandiodate.Thelattermethodofextractionhasbeenfoundmorerobust,sensitiveandtogivebetterextractioninshorterperiodthanSDME.Totalbromine/iodinewasdeterminedwithoutanytreatmentwithsilverchloride.Highconcentrationofchlorideinthematrixdidnotinterfere.Arectilinearcalibrationgraphwasobtainedfor0.05 g–25mgl 1ofbromate/bromideandiodate/iodide,thelimitofdetectionwere20ngl 1ofbromate,15ngl 1ofiodate,20ngl 1ofbromideand10ngl 1ofiodide(byLPMEin50 loftoluene).Themethodhasbeenappliedtoseawaterandtablesalt.Fromthepooleddata,theaveragerecoveryofspikedoxyhalide/halidetorealsampleswasinrange96.7–105.7%withRSDinrange1.6–6.5%.

©2007PublishedbyElsevierB.V.

Keywords:Bromate;Iodate;Iodide;Bromide;High-chloridematrix;Liquid-phasemicroextraction;Singledropmicroextraction;Gaschromatography–massspectrometry

1.Introduction

Ontheoccurrenceofhighamountsinenvironmentalsamples,bromiderepresentsahazardtopublichealth[1,2].Long-termelevateddietarylevelsofbromideexertchangesonthestatusofthethyroidgland,witheventualsubstitutionofiodidebybro-mideduringbiosynthesisofthyroidhormones[3,4].Brominatedandiodinatedcompoundsareproducedduringthedisinfectionofwaterbychlorineinthepresenceofbromideandiodide[5,6].Toxicologicalstudiessuggestthatbrominatedandiod-inatedcompoundsmaybemorecarcinogenicthanchlorinatedanalogues[7].Ozone,usedasanalternativedisinfectanttochlo-rine,generatesbromateasaby-productinwaterscontainingthe

Correspondingauthor.Tel.:+917612678103;fax:+917612403252.E-mailaddress:arichna@sancharnet.in(K.K.Verma).

precursorbromide.Bromatehasbeenclassi edasagroup2Bprobablehumancarcinogen[8].In1993,theWHOsetalimitof25 gl 1forbromateindrinkingwater[9].Despitethehealthrisks,thisguidelinewasbasedonthelimitationsofthemeasure-menttechniquesforbromate.TheUSEnvironmentalProtectionAgency(EPA)setamaximumcontaminantlevelof10 gl 1bromateunderStage1Disinfectants/DisinfectionByproductsRulein1998[10].TheEUreducedtheirregulatoryvaluefrom50to10 gl 1bromateindrinkingwater[11]andtheWHOalsosetaguidelineof10 gl 1[12].Acancerriskof1in105hasbeenassessedat0.5 gl 1bromatebasedoningestionofdrinkingwater[13].

Ionchromatographyhasbeentraditionallyusedfordeter-miningbromate,otheroxyhalidesandhalidesusingacarbonateeluentandsuppressedconductivitydetection[14].Ahydroxideeluenthasbeenfoundtohavelowersup-pressedbackgroundconductivity[15].Preconcentrationbefore

0021-9673/$–seefrontmatter©2007PublishedbyElsevierB.V.doi:10.1016/j.chroma.2007.03.027

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