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1、THINLAYERCHROMATOGRAPHYReference:1.Schoffstall,Gaddis,Druelinger,MicroscaleandMiniscaleOrganicChemistryLaboratoryExperiments,2ndedition,McGrawHill2.Dickson,Kittredge,Sarquis,J.Chem.Ed,Vol81,No7,PP1023–1025,July2004TheoryChromatographictechniquesareusedextensivelyinorganicchemist
2、rylaboratoriesforroutineanalysis.Thinlayerchromatography(TLC)canbeusedtodeterminethepurityofacompound,toanalyzethecompositionofamixtureortofollowtheprogressofareaction.Thecomponentsofamixturearedifferentiatedbyexposingtotwocompetingphases,thestationaryandthemobilephases.InTLC,th
3、estationaryphaseisapolaradsorbentsuchassilicageloralumina,whichhasbeencoatedonaplasticplate.Themobilephaseisanorganicsolvent.Thesolventmovesuptheplatebycapillaryaction.Acoatedanddriedglassorplasticplateiscalledathin-layerplate.Themixturetobeanalyzedisdissolvedinasuitablesolventa
4、ndappliedasspotsnearthebaseoftheplate.Thisprocessisknownasspotting.Spottingisachievedbyrepeatedapplicationsofthemixturefromacapillarypipet.Whenthefilledpipettouchestheplate,theliquidisdeliveredontotheplatebycapillaryaction.Theplateisimmersedinadevelopmentchamber(usuallyabeaker)t
5、hatcontainsasolventoramixtureofsolvents.Thesolventinthedevelopmentchamberisalsoreferredtoastheeluentorelutingsolvent.Asthesolventrisesuptheplatebycapillaryaction,itcarriesthemixturewithit.Thecomponentsofthemixtureareseparatedonthestationaryphasedependingontheirpolarity.Thisproce
6、ssisknownasdevelopingorrunningtheTLCplate.Polarcompoundsareattractedtothesilicagelandareheldmoretightlycomparedtononpolarcompounds.Aseparationresultsduetothedifferenceinratesatwhichindividualcomponents14moveontheplate.Ingeneral,nonpolarcompoundsmovefasterthanpolarcompoundsonaTLC
7、platecoatedwithsilicagel.Whentheplatehasbeendeveloped,itisremovedandallowedtodry.Therewillaseriesofverticalspotsontheplate.Eachspotcorrespondstoaseparatecomponentoftheoriginalmixture.Ifthecomponentsarecolorless,thespotsareinvisible.Toseethespots,avisualizationmethodisused.Ultrav
8、ioletlampisacommonvisualizationmethod.Thedistan
