Anal Chim Acta67812633.docx

Anal Chim Acta67812633.docx

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AnalChimActa67812633

Quantitativeanalysisoftriazineherbicidesinenvironmentalsamplesbyusinghighperformanceliquidchromatographyanddiodearraydetectioncombinedwithsecond-ordercalibrationbasedonanalternatingpenaltytrilineardecompositionalgorithm

Yuan-NaLi,Hai-LongWu*,Xiang-DongQing,QuanLi,Shu-FangLi,Hai-YanFu,Yong-JieYu,andRu-QinYu

StateKeyLaboratoryofChemo/BiosensingandChemometrics,CollegeofChemistryandChemicalEngineering,HunanUniversity,Changsha,Hunan410082,PRChina

Correspondingauthor.Tel.:

+86-731-88821818.

Fax:

+86-731-88821818.

E-mail:

hlwu@（H.L.WU）.

Abstract

Anovelapplicationofhighperformanceliquidchromatography-diodearraydetection（HPLC-DAD）withsecond-ordercalibrationmethodbasedonanalternatingpenaltytrilineardecomposition（APTLD）algorithmispresentedtoallowaccurateandreliablequantitativeandqualitativeanalysisofatrazine（ATR）,ametryn（AME）andprometryne（PRO）insoil,riversedimentandwastewatersamples.Satisfactoryresultsareobtainedalthoughtheelutionandspectralprofilesoftheanalytesareheavilyoverlappedwiththebackgroundinenvironmentalsamples.TheaveragerecoveriesforATR,AMEandPROinsoilsamplesare99.7±1.5,98.4±4.7and97.0±4.4%,respectively;inriversedimentsamplesare100.1±3.2,100.7±3.4and96.4±3.8%,respectively;andinwastewatersamplesare100.1±3.5,101.8±4.2and101.4±3.6%,respectively.Furthermore,theaccuracyandprecisionoftheproposedmethodisinvestigatedbyusingtheellipticaljointconfidenceregion（EJCR）test.Themethodproposedlightsanewavenuetodeterminequantitativelyherbicidesinenvironmentalsampleswithasimplepretreatmentprocedureandprovidesthescientificbasisforanimprovedenvironmentmanagementthroughabetterunderstandingofthewastewater-soil-riversedimentsystemasawhole.

Keywords:

atrazine,ametryn,prometryne,second-ordercalibration,highperformanceliquidchromatography-diodearraydetection,alternatingpenaltytrilineardecompositionalgorithm

1.Introduction

Manualweedingisatraditionalwayforcontrollingweedsinagriculture.Thepracticeisalaborcosting,labor-intensiveandcostlypractice,althoughthe“naturalandcleaning”advantagesareobtained.Alternatively,herbicidesprovidegreatbenefitsforweedcontrolinmodernagriculturedomain.Triazineherbicides,suchasatrazine（ATR）,ametryn（AME）andprometryne（PRO）,areappliedinagricultureasselectivepre-andpost-emergenceweedcontrolforcorn,rice,wheat,sugarcaneandonionetc.However,ithasbeenestimatedthatonly0.1%ofherbicidesappliedtocropsreachtheirtargets,andalargeproportionremainsintheenvironment[1].Theresiduesoftriazineherbicideshaveattractedgreatconcernworldwideandtheyarealsointhelistofchemicalpollutantsthatneedtobemoreheavilymonitoredowingtotheirwidespreaduseandtheirtoxicity,persistence,cumulationinwater,soilandriversediment.Moreover,atrazine,onenumberofthetriazinefamily,hasalsobeenclassifiedasapossiblehumancarcinogen[2].Ontheotherhand,thequantitativeanalysesofherbicides,inordertomonitor,assessandcontroltheireffectsontheenvironmentandhumanhealth,isoneofthemostimportantfieldsinanalyticalchemistry.

Nowadays,anumberofarticleshavebeenreportedfordeterminationofoneortwotriazineherbicides.Chuangetal.[3]determinedatrazine（ATR）incomplexsamplemediausingimmunoaffinitycolumnchromatography.DeterminationofATRinsoilandwaterusingmercuryfilmelectrodewasreportedbyMalekietal.[4].Themolecularlyimprintedsolid-phaseextraction（MISPE）techniquewasemployedforquantitativeanalysisofametryn（AME）inenvironmentalmatrices[5,6].Determinationofprometryne（PRO）inwaterandsoilbyhigh-performanceliquidchromatography-ultravioletdetector（HPLC-UV）usingcloud-pointextractionwasreportedbyZhouetal.[7].Arangeofanalyticaltechniqueshavebeeninvestigatedfortheirabilitytodetecttwoandmoretriazineherbicides[2,8-11].Whilesometimesmeetingwithsignificantsuccess,thesemethods（ionmobilityspectrometry,HPLC-UVandenzyme-linkedimmunosorbentassay（ELISA））aretimeconsuming,employingdifferentextractionmethodsandgenerallydestroythesamplematerials.AdvantagesanddrawbacksofboththeextractionandchromatographicanalysistothetriazineherbicidesfromenvironmentalsampleswerediscussedbyDeanetal.[12].

Highperformanceliquidchromatographyincombinationwithdiodearraydetection（HPLC-DAD）hasbeenbroadlyusedindeterminationoforganicpollutantsonaccountofitsabilityofanalyzingbothpolarandnonpolarthermodegradablecompounds.However,itisnotpossibletoachieveperfectseparation,eitherbecauseofthecomplexityofthesamplesorbecausefasterchromatographicrunsarepreferred.Sometimes,evenunderthebestexperimentalconditions,theprobabilityofpeakoverlapinchromatographicseparationscanbecomequitesevere,especiallyforthehighlycomplexsamples.Sopriortoquantitativeanalysis,asamplepretreatmentprocedurewouldberequiredbecauseitcanreducetheinterferenceofsamplematrix.However,theextractionprocessesareusuallynotselectiveenough,andoftenanumberofinterferingcomponentsarecoextractedwiththeanalytesofinterest.Aswillbediscussedbelow,amodernapproachtoimprovetheselectivityofanalyticalmethodsistheuseofadvancedsecond-orderchemometricmethods,whichmightlighttoanewavenuetoutilize“mathematicalseparation”toinsteadofthe“physicalorchemicalseparation”ofuncalibratedbackgroundorinterferencesbythechemometricseparationoftheirsignals.Thestrengthofthemethodsisthecapacitytodeterminethecontentoftheanalytesofinteresteveninthepresenceofunknowninterferents,whichisknownas“second-orderadvantage”[13-16].Inrecentdecades,agreatvarietyofsecond-ordercalibrationmethodshavebeenproducedforathree-waydataarray,suchasparallelfactoranalysis（PARAFAC）[17,18],generalizedrankannihilationmethod（GRAM）[19],multivariatecurveresolution-alternatingleastsquares（MCR-ALS）[20],alternatingtrilineardecomposition（ATLD）[21]andalternatingpenaltytrilineardecomposition（APTLD）[22].Theapplicationofsecond-ordercalibrationforHPLC-DADdataarrayhasbeenahottopicinthecurrentchemometricdomain,andhasbeensuccessfullyemployedformanypracticalapplications[21,23-27]andevenforremovalforthree-dimensionalbackgrounddriftincomprehensivetwo-dimensional（2D）liquidchromatographycoupledwithdiodearraydetection（LC×LC-DAD）data[28].

Inthepresentstudy,arapidandeffectivestrategyforsimultaneousdeterminationofATR,AMEandPROinsoil,riversedimentandwastewaterhasbeenproposed,bycombiningHPLC-DADwithsecond-ordercalibrationmethodsbasedontheAPTLDalgorithms.ThemainsuccessofthemethodcanbetoobtaintheATR,AMEandPROconcentrationsincomplexmatricesthatexistingco-elutionofcompoundsandspectraloverlapping.Validationofthemethod,throughassessingitsfiguresofmerit,isacrucialstep,notonlyforassessingthereliabilityoftheresults,butforconsistentlyapplyingthemethodtofuturesituations.Therefore,somestatisticalparametersandfiguresofmeritofAPTLDareevaluated.Theintegratedanalysisofthreetriazineherbicidesofthreedifferentenvironmentalcompartments:

wastewater,soilandriversediment,allowsabetterunderstandingofthewastewater-soil-sedimentsystemasawholeandsummarizingthedistributionoftheherbicidespollution.

2.Experimental

2.1.Reagentsandchemicals

Atrazine（ATR）,ametryn（AME）andprometryne（PRO）werepurchasedfromaChinesepharmacyCorporation.StockstandardsolutionsofATR（45.4µgmL-1）,AME（36.9µgmL-1）andPRO（35.5µgmL-1）werepreparedinmethanolandstoredat4℃untilused,respectively.MethanolandacetonitrilewereofHPLCgrade.UltrapurewaterwaspreparedusingaMilli-Qwaterpurificationsystem（Millipore,USA）.

2.2.InstrumentationandChromatographicconditions

TheHPLCsystemusedwasaLC-20ATliquidchromatographicsystem（ShimadzuCorporation,Japan）,whichconsistsofadegasser,fourpumps,amanualinjectorprovidedwitha10lloop,acolumnovenandadiodearraydetector（DAD）.TheseparationwascarriedoutinaHypersil-ODSanalyticalcolumn（125mm×4.0mm,5.0m,Shimadzu,Japan）.TheLCsolutionsoftwarewasusedforcontrollingtheinstrument,dataacquisition,anddatainterpretation.Inthesamplepreparationprocedure,acentrifuge（Sigma,Germany）andultrasonicinstrument（KQ-250TDB,Jiangsu,China）wereused.

Themobilephasewasisocraticandconsistedofmethanol（85%,v/v）andwater（15%,v/v）,pumpedataflowrateof1.0mLmin-1withsampleinjectionvolumeof10l.Thesolventswerefiltereddailythrougha0.45μmcellulosemembranefilterbeforeinjectionintoHPLCcolumn.Thecolumntemperaturewassetat30℃.Photometricdetectionwasperformedintherangeof190-300nm,withaspectralresolutionof1.2nm.Datawasobtainedoveranintegrationperiodof640msperspectrum.IntheMATLABenvironmentallhome-madeprogramswerewrittenandfurtherusedfordataanalysis.

2.3.Samplecollectionandpreparation

ThesoilsamplesandriversedimentsampleswerecollectedfromcroplandandthebankoftheXiangjiangRiverinHunanProvinceofChina,respectively.ThewastewaterwascollectedfromapoolinresidentialareainChangsha,China.Thecollectedsoilsamplesandriversedimentsampleswerestoredinplasticbagsandwedidnotcarryoutanypretreatment.Thesesamplesweredriedatroomtemperature,andgroundwithamortar.Then,100