薄层层析分离方法.ppt

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1、薄层层析分离技术Thin-layerchromatographyThin-layerchromatographyandcolumnchromatographyandaredifferenttypesofliquidchromatography.Themobile(moving)phaseisaliquid.Thestationaryphaseisusuallysilicaoralumina.Thisphaseisverypolar.Theprincipleofoperationisthesame!ThinLayerChromatograp

2、hyThesurfaceoftheplateconsistsofaverythinlayerofsilicaonaplasticoraluminumbacking.Thesilicaisverypolar.Thisisthestationaryphase.Spotthematerialattheorigin(bottom)oftheTLCplate.Placetheplateintoaglassjarwithasmallamountofasolventintheglassjar.Thissolventactsasthemovingphas

3、e.Removetheplatefromthebottlewhenthesolventisclosetothetopoftheplate.Visualizethespots.Non-polarcompoundswillbelessstronglyattractedtotheplateandwillspendmoretimeinthemovingphase.Thiscompoundwillmovefasterandwillappearclosertothetopoftheplate.Polarcompoundswillbemorestron

4、glyattractedtotheplateandwillspendlesstimeinthemovingphaseandappearlowerontheplate.StationaryPhase:Silica(SiO2)StationaryPhase:AluminaAcidic:-Al-OHNeutral:-Al-OH+-Al-O-Basic:-Al-O-Thin-LayerChromatography:ATwo-ComponentMixtureMorepolar!Lesspolar!solventfrontoriginmixtures

5、olventfrontcomponentBcomponentAoriginsolventfrontcomponentBcomponentAoriginIncreasingDevelopmentTimeBesuretoremovetheTLCplatewhenitappearsthatthesolventfrontisn’tmoving!Reason:thesolventisevaporatingasitmovesuptheplate.Results:Ifyoudon’tremovetheplateallofthespotswillappe

6、arnearthetopoftheplate!!!!!Thisisn’taprettysightandmakesitdifficulttogetgoodRfvalues!Importanthint!VisualizationMethodThepreviousslideshowscoloredspots.Mostofthetime,thespotswon’tshowunlesstheyarevisualized!VizualizationisamethodthatisusedtorendertheTLCspotsvisible.Avisua

7、lizationmethodcanbe:UltravioletlightIodinevaporstostainspotsColoredreagentstostainspotsReagentsthatselectivelystainspotswhileleavingothersunaffected.Thin-LayerChromatography:DeterminationofRfValuesRfofcomponentA=dAdSRfofcomponentB=dBdSTheRfvalueisadecimalfraction,generall

8、yonlyreportedtotwodecimalplacesThin-LayerChromatography:QualitativeAnalysis1、薄层色谱：薄层色谱法，是将适宜的固定相