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ThinLayerChro__tographyof____gesicsIntroduction:Over-the-counter____gesicstypicallycontainoneormoreofthefollowingactiveingre___nts:a__taminophenaspirincaffeineibuprofenphena__tinorsalicylamide.Thinlayerchro__tographyTLCoffersa______methodof____ysisfortheseproducts.Chro__tographyisatermthatiswidelyusedtodescribeafamilyofcloselyrelatedseparationmethods.Thereare__nyseparationmethodsbutthefeaturethatdistinguisheschro__tographyfromotherphysicalandchemicalmethodsofseparationisthatbothastationaryandmobilephasewhichareincapableofbeingmixedcomeintocontactandthesampletobeseparatedinteractsnumeroustimeswiththesephases.Thesampleiscarriedthroughthesystemviathemobilephaseandtheinteractionsthatoccurareduetothedifferen__sinthephysicalandchemicalpropertiesthatgoverntherateatwhichtheindividualcomponentsofthesamplepassoverthestationaryphaseundertheinfluen__ofthemobilephase.Thinlayerchro__tographyTLCisonetypeofchro__tographywherethestationaryphaseisathinlayerofadsorbentparticlesattachedtothesolidplate.A__allamountofsampleisappliedspottednearthebottomoftheplateandtheplateispla__dinthemobilephase.Thissolventisdrawnupbycapillaryactiontoapredeterminedheight.Separationoccursbecauseeachcomponentinteractsdifferentlywiththemobilephase.Eachcomponentbeingdifferentinchemicalandphysicalcompositionwillinteractwiththemobilephasetodifferentdegreestherebycreatingtheindividualbandsontheplate.TheretentiontimeorretentionfactorRfisusedtocharacterizeandcomparecomponentsofvarioussamples.Rf=____distan__fromorigintospot_____distan__fromorigintosolventfrontPurpose:Thepurposeofthisexperimentistodeterminethecontentofover-the-counter____gesics.Equipment/__terials:____gesictabletsibuprofincaffeinemortarandpestleEx__drinA__taminophenmetricrulera__tylsalicylicacidcottoncapillarytubesNeoproxinUVlightdevelopingchambers19:1Ethylfor__te:88%formicacidPasteurpipettes16:4:1Toluene:ethylfor__te:88%formicaciddevelopingsolutionSafety:Alwayswearanapronandgogglesinthelab.Usecautioninhandlingtheethylfor__teformicacidtolueneandmixturescontainingthesechemicals.__oidlookingdirectlyattheUVlightorshiningthelightinanyone’seyes.Pro__dure:Preparationofsample
1.Pusha__allwadofcottonthroughthetopofapipettesothatisformsaplugatthepointwherethepipettenarrows.
2.Pulverizean____gesictabletandtransferthetablettothepipette.
3.Fillthepipettewith19:1Ethylfor__te:88%formicacidtodissolvesomeofthe____gesicandthenfor__thesolutionoutthroughthecottonfilterintoavial.Labelthevialwiththenameofthe____gesicbeingtested.
4.Repeatthepro__dureforeachofthe__ailabletabletsandknownstandards.Spottingofthesample
1.Prepareamicrocapillarytubeforeach____gesicandeachstandard.Yourinstructorwilldemonstratethistechnique.
2.Immersethe__allendofthetubeintothesamplevialuntilsomeofthesampleisdrawnintothetube.
3.Verygentlypressthe__allendofthetubeontotheplateaboutonecmfromthebottomoftheplate.Keepthespots__allandcon__ntratedbyapplyingthesample5timesandallowingthespottodrybetweenapplications.Additionalspots__yberequiredfortheibuprofenstandardinordertoseeitsspotclearly.
4.Repeatthispro__dureforeachofthestandards__ailable.
5.Twoormoresamples__ybeappliedtoeachplateiftheyarekeptonecmapart.__rkthepositionofthespotslightlyinPENCILandbesuretokeeparecordofwhichspotrepresentseachproduct.DevelopmentoftheTLCplates
1.Prepareadevelopingchamberbyadding15-20mlofsolvent16:4:1Toluene:ethylfor__te:88%formicacid.
2.Pla__theTLCplatesinthechambersothattheydonottouch.Allowthesolventtorisetowithinonecmofthetopoftheplates.
3.Removetheplates__rkthesolventfrontandallowthemtodry.
4.VisualizethespotsbyilluminationunderaUVlamp.
5.Tra__aroundeachspotwithapencilandthenmeasurethedistan__tr__eledbyeachcomponent.
6.CalculatetheRfbydividingthedistan__ofthesolventfrontbythedistan__ofthespot.TheRfvalueischaracteristicofeachsubstan__and__ybeusedforidentificationofthesubstan__.Name__________________________Period_________________________Date__________________________ThinLayerChro__tographyof____gesicsData:Drawtheobservedchro__tographsRecordtheRfvalueforeachofthestandardsandidentifythecomponentsoftheunknownsComponentDistan__spotDistan__solventRfa__taminophenAspirinCaffeineIbuprofenPhena__tinSalicylamideQuestions:
1.Whatisthestationaryphaseandwhatisthemobilephaseinthisexperiment
2.Whatisthepurposeofthe__allwadofcottoninthepipette
3.Whyisapencilnotapenusedto__rkthepositionofthespots
4.WhyisanRfvalueratherthanthedistan__thespotmovedusedtohelpidentifyasubstan__byTLC
5.Whatisco-spotting
6.Whyisco-spottingagoodtechniquefordeterminingtheidentityofacomponentbyTLCThinLayerChro__tographyof____gesicsTeacherNotesLabTime:about90minutesPreparations:Time:lessthan15minutesT:__keonesetofequipmentand__terials__ailabletoeachlabgroup.T:Eachstudentshouldbringasampleof____gesictothelab.T:Theinstructorshouldsetupademonstrationon__kingmicrocapillarytubes.V:ThestandardspipettessolventsiodinechambersUVlightandcapillarytubeswillbebroughtbythevan.Anyother__terialsmustberequested.AnswerstoQuestions:
1.WhatisthestationaryphaseandwhatisthemobilephaseinthisexperimentThestationaryphaseistheTLCplate.Themobilephaseisthedevelopingsolutioncomposedoftolueneethylfor__teandformicacid.
2.Whatisthepurposeofthe__allwadofcottoninthepipetteToremovestarchandotherinsolublecompoundsfromthe____gesictablets.
3.Whyisapencilnotapenusedto__rkthepositionofthespotsTheinksfromthepenwouldseparateduringchro__tography.
4.WhyisanRfvalueratherthanthedistan__thespotmovedusedtohelpidentifyasubstan__byTLCThedistan__thespotmovesdependsontime.Itisalsoinfluen__dbyrateofevaporation.ByusinganRfvaluethemovementofthesolventbecomesacommonfactorthusresultinginamoreaccuratecomparison.
5.Whatisco-spottingSpottinganunknownsubstan__andthesubstan__itisbelievedtobeontopofeachother.
6.Whyisco-spottingagoodtechniquefordeterminingtheidentityofacomponentbyTLCThetwosubstan__sarespottedtogetherthuseliminatinganyfactorsduetoaslightdifferen__inspottingoranymeasurementun__rtainty.Iftwospotsresultthesubstan__saredifferent.Consideration:ThislabreallyallowsthestudentstogetagoodunderstandingofTLC.Thepracti__of__kingmicrocapillarytubesandthepreparationandinterpretationoftheplateswillgivethemastrongbackgroundinthistypeofchro__tography.Lastupdated8-0118-A-1。