thin layer chromatography of vegetables - …蔬菜的薄层色谱法—…

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1、ThinLayerChromatographyofVegetablesIntroduction:Thinlayerchromatography(TLC)isonetypeofchromatography.InTLC,thestationaryphaseisathinlayerofadsorbentparticlesattachedtoasolidplate.Asmallamountofsampleisapplied(spotted)nearthebottomoftheplate,andtheplateisplacedinthemobilephase.Thissolventisdr

2、awnupbycapillaryaction.Separationoccursaseachcomponent,beingdifferentinchemicalandphysicalcomposition,interactswiththestationaryandmobilephasestoadifferentdegree,creatingtheindividualbandsontheplate.Theretardationfactor,Rfvalue,isusedtocharacterizeandcomparecomponentsofvarioussamples.Rfvalue=

3、distancefromorigintocomponentspotdistancefromorigintosolventfrontThepigmentsinvegetables,flowers,andleavescanbeseparatedandidentifiedbyusingthin-layerchromatography.Greenpigments,knownaschlorophylls,serveasthemainphotoreceptormoleculesofplants.Carotenoids,yellowpigments,aidtheplantinthephotos

4、ynthesisprocess.Inaddition,xanthrophyllsarecontainedinthechloroplastswhichcanbeisolatedandidentifiedusingchromatographictechniques.PigmentColorRfvaluecaroteneyellow-orange0.91pheophytinaGrey0.75pheophytinblt.grey(maynotbevisible)0.63-0.75chlorophyllablue-green0.63chlorophyllbGreen0.58xanthoph

5、yllsYellow0.53xanthophyllsYellow0.47xanthophyllsYellow0.32Purpose:Thepurposeofthislaboratoryexperimentistoisolatethepigmentsfromspinachandcarrotsbyusingthinlayerchromatography.Equipment/Materials:TLCsilicagelplatescapillarytubeschromatographychambers70:30hexane-acetonesolventspinachmortarshre

6、ddedcarrotspestlehexanethinstemmedpipetsacetonetesttubeSafety:·Alwayswearanapronandgogglesinthelaboratory.Procedures:1.Obtainaspinachleaf,andtearitintosmallpieces.Placethespinachpiecesinamortar.2.Addapproximately2mLofacetoneandcarefullygrindthespinachandacetonetogetherwiththepestle.Continuegr

7、indinguntiltheacetonebecomesdarkgreenincolor.Moreacetonemaybeaddedtocompensateforevaporation.3.Usingathin-stemmedpipet,extracttheacetoneandplaceitinasmalltesttube.Becarefulnottoextractthesmallpiecesofspinach.4.Repeatsteps2and3usingthesamespin