2023學(xué)年完整公開課版Determinationmethodofopticalrotation 省賽獲獎

PharmaceuticalanalysisAuthor:NiuXiaodongDeterminationmethodofopticalrotationDeterminationmethodofopticalrotationOverviewThestructureoforganiccompoundcontainschiralcarbonatomofopticalrotation.Theanalyticalmethodofdeterminingtheopticalrotationofmedicineforqualitative,impuritytestandquantitativeanalysisiscalledopticalrotationdetermination.Chiralcarbonatomsrefertocarbonatomsconnectedwithfourdifferentatomsorgroups,whichareoftenmarkedwith"*"MaincontentsBasicconceptsFactorsaffectingthedeterminationofopticalrotationInstrumentanddeterminationmethodApplicationofpolarimetryAssignmentsI.BasicconceptsOpticalrotation:Whenplanepolarizedlightpassesthroughliquidorsolutioncontainingsomeopticallyactivecompounds,itcancauseopticalrotation,whichmakestheplaneofpolarizedlightrotateleftorright.Thedegreeofrotationiscalledopticalrotation(expressedbyα).Specificrotation:Whenpolarizedlightpassesthroughthesolutionwithalengthof1dmandcontaining1gofopticallyactivesubstanceper1ml,itsopticalrotationmeasuredatcertainwavelengthandtemperatureiscalledspecificrotation(expressedby).II.FactorsaffectingthedeterminationofopticalrotationOpticalrotationisnotonlyrelatedtochemicalstructure,butalsorelatedtosolutionconcentration,liquidlayerthickness,temperature,lightwavelengthandsolvent.DisDlineofsodiumspectrum;tisthetemperaturefordeterminationαismeasuredopticalrotation;Lislengthofdeterminationtube(dm)Cistheweightofthesubstancetobemeasuredin100mlsolution(g,basedondryoranhydrousmatter)(I)ChemicalstructureofsubstanceDifferentchemicalstructuresofsubstanceleadtodifferentopticalactivity:Underthesameconditions:somerotationanglesarelarge,andsomerotationanglesaresmall;someareleft-handed("-")andsomeareright-handed("+"),andsomesubstanceshavenochiralcarbonatomsandnoopticalactivity.(II)ConcentrationofsolutionThegreaterthesolutionconcentrationis,thegreatertheopticalrotationis.Inacertainconcentrationrange,thereisalinearrelationshipbetweentheconcentrationofmedicinesolutionandtheopticalrotation.Themeasurementofspecificrotationshouldbecarriedoutinacertainconcentrationofsolution.(III)SolventTheeffectofsolventonopticalrotationiscomplex,whichvarieswithsolventsandmedicines:somesolventshavenoeffectonmedicines,whileothersaffectthedirectionandmagnitudeofopticalrotation.Thenameofsolventshouldbemarkedwhendeterminingtheopticalrotationandspecificrotationofmedicine.(III)Solvent(IV)ThicknessofliquidlayerwherelightpassesthroughAsthethicknessoflightpassingthroughliquidlayerrises,theopticalrotationincreasesUnlessotherwisespecified,1dmdeterminationtubeisadoptedinChinesePharmacopoeia(2015).(III)Solvent(V)WavelengthoflightTheshorterthewavelengthis,thegreatertheopticalrotationis.ChinesePharmacopoeia(2015)adoptsDline(589.3nm)ofsodiumspectrumtodeterminetheopticalrotation.Ingeneral,theeffectcausedbythetemperatureisnotgreat.Formostsubstances,undertheyellowsodiumlight,whenthetemperaturerisesby1℃,thespecificrotationdecreasesbyabout1‰.(VI)TemperatureIII.InstrumentanddeterminationmethodChinesePharmacopoeia(2015)stipulatesthatacalibratedpolarimeterwithareadingof0.01°shouldbeused.Commonlyusedpolarimeter:DiscpolarimeterWZZ-1polarimeterWZZ-2polarimeterStructuralprincipleBasiccomponentsofpolarimeter:Monochromaticsource,polarizer,determinationtube,analyzeranddetector.Principle:Beforetheopticallyactivesubstanceisplacedbetweenthepolarizerandanalyzer,ifthedirectionofpolarizedlightallowedtopassthroughbythepolarizerandtheanalyzeristhesame,thevisualfieldobservedbehindtheanalyzerisbright;Ifopticallyactivesubstanceisplacedbetweenthepolarizerandtheanalyzer,thepolarizedlightfromthepolarizerisrotatedbyanangleαduetotheopticalactivityofthesubstance,andthevisualfieldbecomesdarkerwhenobservedbehindtheanalyzer.Iftheanalyzerisrotatedatacertainangleandrestoredtotheoriginalbrightness,theangleanddirectionoftheanalyzerrotationwillbetheopticalrotationofthetestsample.StructuralprincipleCrystalaxisCrystalaxisEyelensOpticalsourcePolarizerPolarizedlightLiquidtubePolarizedlightafterrotationAnalyzerPolarizedlightpassingthroughtheanalyzera.Thepolarizedlightgeneratedbypolarizer(I)vibratesinplane00.b.Thevibrationplaneofpolarizedlightpassingthroughthemagneticrotationcoilswingsatβangle.c.Thevibrationplaneofpolarizedlightpassingthroughthesamplerotatesbya1°.d.Afterthedisplayoftheinstrumentisbalanced,thepolarizer(I)rotatereverselybya1?tocompensatetheopticalrotationofthesample.PolarizingaxisofOOpolarizer(I)PolarizingaxisofOOpolarizer(II)Three-fieldofviewGreater(orless)thanzerofieldofviewZerofieldofviewLess(orgreater)thanzerofieldofviewWhenthelightpassesthroughthepolarizerfromthelightsourceandthenthroughtheopticalrotationtubecontainingopticallyactivesubstance,thelightcannotpassthroughthesecondprismbecauseoftheopticalactivityofthesubstance,sotheanalyzermustberotatedbeforethelightcanpassthrough.Therefore,itisnecessarytoadjusttheanalyzerforlightdistribution.Fromthemovingangleonthescaleplate,therotationangleofprism2canbeindicated,thatis,theopticalrotationofthesubstanceatthisconcentration.DiagramofpolarimeterSodiumlightsourceLocationforplacingsampletubeKnoboffocallengthsettingDialwindowKnobofopticalrotationsettingSampletube:Observationwindowwiththree-fieldofviewOperationmethod:Attentionsindetermination:1.Conductblankcorrectionwiththesolventbeforedetermination.Afterdetermination,correctagaintodeterminewhetherthezeropointchangesindetermination;ifitisfoundinthesecondcorrectionthatthezeropointchangesindetermination,determinetheopticalrotationagain.2.Adjustthetemperatureto20±0.5℃(specifiedtemperatureundereachdrug)insolutionpreparationanddetermination.3.Thesolutionofliquidorsoliddrugtobetestedshouldnotbeturbidorcontainsuspendedsmallparticles.Otherwiseitshouldbefilteredinadvanceandtheprimaryfiltrateshouldbediscarded.IV.Applicationofpolarimetry(I)DeterminationofspecificrotationThedeterminationshouldbeconductedstrictlyaccordingtotheconditions(temperature,solvent,wavelength,concentration,etc.)recordedintheliteratureandcalculatedasbelow:IV.Applicationofpolarimetry(II)Contentdeterminationofsolution1.SpecificrotationmethodUsedwhenspecificrotationisgiven

2.Standardcurvemethod1.SpecificrotationmethodDeterminationmethod:Takeacertainamountoftestproductbypreciseweighing.Preparesolutionofcertainconcentration.Putitinadeterminationtubetodetermineitsopticalrotationandthencalculateitscontent:1.SpecificrotationmethodForexample:ContentdeterminationofglucoseinjectionTakeacertainamountofthisproduct(equaltoabout10gofglucose)bypreciseweighing.Putitina100mlvolumetricflaskandadd0.2mlofammoniatestsolution(tobalancethemutarotationofglucosesolution).Diluteittograduationbywater.Shakeitevenlyandkeepitstandfor10min.Accordingtothepharmacopoeiaappendix,theopticalrotationoftheinjectionis+4.9,andthatoftheblanktestis0.Findtheglucosecontent(C6H12O6·H2O)intheglucoseinjection.AccordingtoprovisionofChinesePharmacopoeia(2005):Thespecificrotationofanhydrousglucoseat25℃shouldbe+52.5°-+53.0°. Thatis:Accordingtotheformula:Thecalculationresultisthecontentofanhydrousglucose.IfcalculateaccordingtoC6H12O6·H2O,then:itcanbeobtainedthat:C=α×2.08522.0852istheweight(g)ofC6H12O6·H2Oineach100mlofthesolutiontobetestedper1oopticalrotation.2.Standardcurvemethod1.First,determinetheopticalrotationofaseriesofstandardsolutions.Thendrawtheopticalrotation-concentration(α-C)curvewiththeopticalrotationastheordinateandtheconcentrationofthes