会员注册 | 登录 | 微信快捷登录 QQ登录 微博登录 | 帮助中心 人人文库renrendoc.com美如初恋!
站内搜索 百度文库

热门搜索: 直缝焊接机 矿井提升机 循环球式转向器图纸 机器人手爪发展史 管道机器人dwg 动平衡试验台设计

外文翻译--毛细管电泳电化学检测方法 中文版.pdf外文翻译--毛细管电泳电化学检测方法 中文版.pdf -- 5 元

宽屏显示 收藏 分享

资源预览需要最新版本的Flash Player支持。
您尚未安装或版本过低,建议您

JournalofChromatographyA,834199989–101ReviewElectrochemicaldetectionmethodsincapillaryelectrophoresisandapplicationstoinorganicspeciesThomasKappes,PeterC.HauserUniversityofBasel,DepartmentofChemistry,Spitalstrasse51,CH4056Basel,SwitzerlandAbstractThethreeelectrochemicaldetectionmethodsincapillaryelectrophoresis,namelyconductometry,amperometryandpotentiometry,arediscussedandcomparedtothemorecommonopticaldetectionmethods.Theprinciplesofeachmethodandtheirimplementationsaredetailedandreportedapplicationstoinorganicspeciesarereviewed.1999ElsevierScienceB.V.Allrightsreserved.KeywordsElectrochemicaldetectionDetection,electrophoresisReviewsInorganicanionsMetalcationsContents1.Introduction............................................................................................................................................................................892.Conductometricdetection........................................................................................................................................................902.1.Principle.........................................................................................................................................................................902.2.Implementations.............................................................................................................................................................913.Amperometricdetection...........................................................................................................................................................923.1.Principle.........................................................................................................................................................................923.2.Implementations.............................................................................................................................................................934.Potentiometricdetection..........................................................................................................................................................954.1.Principle.........................................................................................................................................................................954.2.Implementations.............................................................................................................................................................955.Applicationstoinorganicspecies..............................................................................................................................................996.Conclusions............................................................................................................................................................................100References..................................................................................................................................................................................1001.Introductionformofconductometry,amperometryorpotentiometryareanattractivealternative,which,howDetectionincapillaryelectrophoresisCEisever,hasbeenexploredcomparativelylittle.Thisiscommonlycarriedoutusingopticalmeansabsorpininterestingcontrasttoionchromatography,thetionandfluorescence.Electrochemicalmeansintheotherandoldergeneralmethodforiondetermination,whichmainlyemploysconductivitydetectionCorrespondingauthor.Fax141612671013.andwhereopticalmethodsareseldomused.Perhaps,00219673/99/–seefrontmatter1999ElsevierScienceB.V.Allrightsreserved.PIIS002196739800685290T.Kappes,P.C.Hauser/J.Chromatogr.A834199989–101thisisevenmoresurprisingwhenoneconsidersthattionandfluorescencemeasurementsarealsoreopticaldetectionismademoredifficultincapillarystrictedtospeciesthatshowtherespectivepropelectrophoresisbecauseofthesmallercellvolumeserties.Forthisreason,indirectopticalmethodsareandthefactthatmanyionscannotbedetectedoftenusedinwhichthedisplacementofasenseddirectlybyopticalmeans.Theexplanationforthisauxiliaryagentbytheanalytesismonitoredforcedsituationmaybetwofold.Firstly,itisfairlyeasytobytherequirementtohaveoverallchargeneutrality.adaptabsorptiondetectors,aswidelyusedinhighThisapproachmayalsobeusedforelectrochemicalperformanceliquidchromatographyHPLC,fordetectionmethodswhentheanalytespeciescannotcapillaries.ManyCEinstrumentmanufacturersapbesenseddirectly.ChemicalderivatizationofthepeartohavegonethisrouteandhaveincorporatedanalyteinordertoimpartdetectabilityisanotherexistingdetectorsintotheirCEequipment.Secondly,possibleapproach.Neitherofthesemeansisideal,theappliedhighseparationvoltageisanintrinsichowever,asindirectdetectiononlyallowsanarrowinterferenceinelectrochemicaldetection.Intheearlydynamicconcentrationrangeandderivatizationaddsdays,elaborateschemeswereemployedtoovercometothecomplexityofthemethod.Inpractice,thethisdifficulty.Inrecentyears,ithas,however,choiceofthedetectionmethodshouldperhaps,inthebecomeevidentthat,withthecorrectdesignofthefirstinstance,exploitanintrinsicpropertyfordirectsystem,thisdoesnothavetobeaproblem.sensingand,secondly,bebasedontheachievableCommontoallthreevariantsofelectrochemicalandrequireddetectionlimits.Acompromisemaydetectionmeansisthefactthattheyareintrinsicallyhavetobefoundwhenseveralspeciesaretobesimplerthantheopticalmethods.Anelectricalsignaldeterminedasnotallmayhavethesamesetofisobtaineddirectlywithouttheinvolvementofandetectableproperties.intermediatephysicalparameter,suchasradiationOtherreviewsonelectrochemicaldetectioninintensityinopticalmethods.Thedetectorhardwarecapillaryelectrophoresisareavailable1–5.consistsofthreeorfewersmallelectrodesandsomefairlysimpleelectroniccircuitry,whereasforopticaldetection,alightsource,monochromator,optical2.Conductometricdetectiondetectorsandfocussingopticsarenecessary.Inopticalmethods,thecellvolumedirectlyaffectsthe2.1.Principlesignalviatheopticalpathlengthand,forthisreason,thecapillarydiametersalwaysshouldbeaslargeasHeretheabilityofionstoconductchargeinpossible.Forelectrochemicaldetection,thecellsizesolutionisexploited.Thecurrentproducedbetweensamplevolumehasonlyadirectbearingincontwoelectrodeswhenapplyingavoltageismeasuredductivitymeasurements.Inamperometry,thesignaland,accordingtoOhmslaw,yieldstheresistanceorisrelatedtotheareaoftheworkingelectrode,thetheconductanceoftheelectrolytesolution.Inordersizeofwhichwillbelimitedbytheavailablesampletosuppresstheinfluenceofanyredoxreactiontakingvolume.Forpotentiometricdetection,thesignalisplaceattheelectrodes,conductometricmeasurecompletelyindependentofthesensorsizeand,mentsareusuallycarriedoutbyemployinga.c.therefore,ofthecellvolumeandcapillarydiameter.voltagesatafrequencyoftypically1kHz.IfhigherOpticalmethods,ontheotherhand,havetheadvanfrequenciesareused,itispossibletoemployelectageofprovidingcompleteelectricalisolationofthetrodesthatarenotincontactwiththesolution,butdetectorfromtheseparationvoltageappliedtotheattachedoutsidethesamplecell6.Theconductcapillary.anceofasolutionLisdependentontheelectrodeConductivitydetectioncanberegardedasaareaA,theirdistancel,theconcentrationcofuniversalmethod,whileamperometricdetectionisthechargecarriersandtheirmobilitylintherestrictedtoelectroactivespeciesandpotentiometricelectricfield,accordingtoEq.1detectionisnotpossibleforcertainsmallionswithmultiplecharges.VerylowdetectionlimitshavebeenAreportedforamperometricdetection.OpticalabsorpL5Olc1iilT.Kappes,P.C.Hauser/J.Chromatogr.A834199989–10191Themobilityofionsisafunctionoftheirsizemethoddidnotfindwideracceptance.ACconradiusofhydratedionandthenumberofcharges,ductivitydetectionwasintroducedbyEveraertsandincidentally,thisisthesamepropertythatisexVerheggen8.Intheearlystudies,relativelylargeploitedfortheelectrophoreticseparationoftheions.boreseparationchannelsandcapillarieswereusedConductometricmeasurementsarethereforenotandthedetectorelectrodeswereplacedaheadoftheselectiveand,asstandalonemethods,theseareterminalelectrolytechamberdirectlyintothesepalimitedtocircumstanceswheretheoverallsamplerationchannel.ThisarrangementisillustratedinFig.compositioniswellknown.Thefactthatallions1A.Thetwodetectorelectrodesareideallyarrangedgivearesponseinconductometryisontheotherdirectlyoppositeandperpendiculartotheseparationhandexactlywhatisrequiredfordetectioninachannelinordertoavoidsensinganypotentialseparationmethodforionsand,forthisreason,gradientinthechannel.WithcarefuldesignoftheconductometricdetectioniswidelyusedinionchroACdetectorelectronics,itshouldalsobepossibletomatography7.ThisfeatureontheotherhandalsodiscriminateagainsttheDCfieldorlowfrequencyleadstoaresponsetoanybackgroundion,suchasfluctuationsthereof.InafirstreportonconductivitythoserequiredasaneluentinionchromatographyordetectionwithmodernsilicacapillariesbyHuangetaspHandionicstrengthbufferincapillaryelectroal.12,twosmallholeswerelaserdrilledintothephoresisandthecounterionsofoppositechargetoseparationcapillaryforinsertingthetwodetectortheanalyteion.Forthelatterreason,theconductivityelectrodes.Simplifiedendcolumndetectorswereequationhastoincludethesummationterminalllaterintroduced13.Thislatterarrangementconcases.Ahighbackgroundconductivitymaycomsistsofanelectrodemountedinthewalljetarrangepromisethedetectionlimitfortheanalytespecies.mentdirectlyattheoutletofthecapillaryandaSocalledsuppresseddetectionmethodsarethereforesecondgroundelectrodelocatedatadistanceintheusedforionchromatographyinwhichthebackgroundionsareremovedfromthestreambeforedetectiontakesplace.Itisalsonoteworthythatthecellsdimensionsentertheequationviatheelectrodeareaanddistanceand,therefore,thecellvolumeaffectsthemeasuredsignal.2.2.ImplementationsInearlycapillaryzoneelectrophoresisandisotachophoresissystems,usewasmadeofsocalledpotentialgradientdetection8–11.Here,thesolutionpotentialinthedetectionregionbroughtaboutbytheapplicationoftheelectricfieldissensedwithasingleelectrodeorapairofinertelectrodes.Thevoltagedropovertheseparationcapillaryisnotuniformiftheconductivityvarieswithsamplezones.Asthisisafunctionoftheconductivity,thiscanbeviewedasaclevermeansofsensingthispropertywithouttheneedforapplyingameasuringsignal.Itmaybeexpected,however,thatsuchanarrangementismorepronetoinherentnoisethanthenormalACmodeofconductivitymeasurementstheFig.1.A.c.conductometricdetection.AAnearliersystemwithaddedcomplicationofneedingtoapplyasignaltwodetectorelectrodesDEsinline,electricallyindependentofshouldbeoffseteasilybytheinherentdiscriminationelectrophoreticgroundGND.BAlatersystemwithasingleagainstelectricalnoise.Perhapsforthisreasonthedetectorelectrodeusedagainstelectrophoreticground.92T.Kappes,P.C.Hauser/J.Chromatogr.A834199989–101instrumentwithelectrochemicaldetectionthatappearstobeavailablepresentlyincorporatessuchanendcolumnconductivitycell14.Detectionlimitsfornormalconductivitydetectionandnonstackingsampleinjectionarerelatively25high,beingtypically10mol/l.Thesuppresseddetectiontechniqueallowsthedetectionofcon27centrationsaslowas10mol/l15–18.BackgroundbufferionsareremovedbyusingweakacidsFig.2.Conductometricdetectionwithachemicalsuppressor.orbasesthatarerenderednonionicwhenincontactElectrophoreticgroundisinthecontainerwiththesuppressantwithanionexchangermembrane,deliveringprotonssolution.Theconductivitymaybemeasuredattheendoftheorhydroxideions.Toachievethisincapillarycolumnagainstthisgroundasshownorwithaseparatetwoelectrophoresiswithoutexcessivebandbroadening,aelectrodesystem.tubeoftheionexchangermaterialwithsimilardimensionsisattachedtotheseparationcapillarybuffercontainer,asillustratedinFig.1B.Here,theaheadofthedetectorcell,asillustratedinFig.2.conductivityismeasuredagainsttheelectrophoreticWhilelowerlevelscanbedetermined,theimground.Theconductivitysignalwilllargelyariseatplementationismorecomplicatedthannonsupthecapillaryoutletwherethedetectorelectrodeispressedconductivitydetectionandposeslimitationslocatedduetothemuchlargercrosssectionoftheonthechoiceofthebufferemployed.fluidaroundthecounterelectrode.ThisgeometryAdifferentapproachtoloweringthedetectionalsoleadstoanimmediatelossoftheelectricfieldlimitistheuseofsamplestackingmethods,andoutsidethecapillaryend.Theonlycommercialconcentrationsbelow1ppbhavebeendetermined14,19,20.AnelectropherogramforalowppbstandardmixtureisgiveninFig.3toillustratethistechnique.Samplestackingis,however,onlypossiblewithsamplesoflowionicstrengthandtheuseofinternalstandardizationmaybenecessarytoobtainadequateprecision.Acontactlessconductivitydetectorcellhasalsorecentlybeendescribed.Twotubularelectrodesareplacedoverthecapillaryandcouplingtothedetectionvolumeisachievedcapacitivelybyapplyingana.c.fieldof40kHz21.Theconstructionofthiscellisverysimpleandallowscombinationwithaseconddetector.Limitsofdetectionappeartobecomparabletonormalendcolumndetection.3.Amperometricdetection3.1.PrincipleAmperometricdetectionreliesonoxidationorreductionoftheanalytespeciesonaworkingelectrode.ThemethodisthereforenotasuniversalasFig.3.Electropherogramusingconductivitydetectionforananionconductivitydetection,asonlyelectroactivespeciesstandardmixtureoflowconcentrationsdeterminedbysamplestackingreproducedwithpermissionfromRef.14.areaccessible.Ontheotherhand,verylowdetection
编号:201311171155026124    大小:151.53KB    格式:PDF    上传时间:2013-11-17
  【编辑】
5
关 键 词:
教育专区 外文翻译 精品文档 外文翻译
温馨提示:
1: 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供交流平台,并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
  人人文库网所有资源均是用户自行上传分享,仅供网友学习交流,未经上传用户书面授权,请勿作他用。
0条评论

还可以输入200字符

暂无评论,赶快抢占沙发吧。

当前资源信息

4.0
 
(2人评价)
浏览:22次
英文资料库上传于2013-11-17

官方联系方式

客服手机:13961746681   
2:不支持迅雷下载,请使用浏览器下载   
3:不支持QQ浏览器下载,请用其他浏览器   
4:下载后的文档和图纸-无水印   
5:文档经过压缩,下载后原文更清晰   

相关资源

相关资源

相关搜索

教育专区   外文翻译   精品文档   外文翻译  
关于我们 - 网站声明 - 网站地图 - 友情链接 - 网站客服客服 - 联系我们
copyright@ 2015-2017 人人文库网网站版权所有
苏ICP备12009002号-5