文档介绍：该【Lecture 9 Introduction to Chromatography “The Science of 9讲介绍色谱学” 】是由【孔乙己】上传分享，文档一共【22】页，该文档可以免费在线阅读，需要了解更多关于【Lecture 9 Introduction to Chromatography “The Science of 9讲介绍色谱学” 】的内容，可以使用淘豆网的站内搜索功能，选择自己适合的文档，以下文字是截取该文章内的部分文字，如需要获得完整电子版，请下载此文档到您的设备，方便您编辑和打印。Lecture9IntroductiontoChromatography“TheScienceof9讲介绍色谱学”

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Gradientconstruction:
High-pressuregradient
Low-pressuregradient(morecommon)wherepro-portioningofthesolvents(upto4)throughafour-wayvalveatlowpressuretakesplace,thenpumpingthemixtureathighpressureintothecolumnisperformed.
Requirementsofpumpingsystem:
Pulsefreeoutput.
-10mL/min.
%.
Corrosionresistant(stainlesssteel&Teflon).
Generationofpressureupto6000psi(400Bar).
ModernHPLCsystemshavebeenimprovedtoworkatmuchhigherpressures,andthereforeareabletousemuchsmallerparticlesizesinthecolumns(<2 μm).These"UltraHighPerformanceLiquidChromatographyUPLC"systemsworkatupto100 MPa(15,000 lbf/in²),orabout1000 Bar.
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Lecture7–HPLC,23-10-2019
DoeshighpressureinHPLCconstituteanexplosionhazard?Why?
tocolumn
solvent
ballcheck
valves
topulse
damper
(in90%ofsystems)
Disadvantage: pulsedflow,thusdampingnecessary
Advantages: smallinternalvolume(35–400L),highoutputpressure(10,000psi)adaptabilityforgradientelution,constantflowrates(largelyindependentofcolumnback-pressureandsolventviscosity).
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Lecture7–HPLC,23-10-2019
Analyticalcolumn:
length:5–30cm.
ID:1–5mm.
madeofsteelorplastic.
expensive(>.),easilydamagedbydustorparticlesinthesampleorsolvent.
Protection:
.
bypassingsolventsandsamplesthroughfilters(m).

Preparativecolumn:industrialscale(for1kgofmaterial,volume300L)
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Lecture7–HPLC,23-10-2019

Packedcolumn
TypicallyusedinHPLC
TypicallyusedinGC:
Rapidequilibrationoftheanalytesbetweenstationaryandmobilephaseisaccomplishedbydecreasingstationaryphasethicknessandreducingcolumndiameter.
Diffusionofliquidsis~100timesslowerthandiffusioningases.
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Lecture7–HPLC,23-10-2019

Thesyringeisusedtowashandloadtheloopwithfreshsampleatatmosphericpressure.
Whenthevalveisrotated60°counterclockwise,thecontentofthesampleloopisinjectedintothecolumnathighpressure.
Mostcommoninjectionvalve:six-portorRheodyne™valve
Syringe:bluntneedletoavoiddamagetoinjectionport
Interchangeableloops(sizes:L).
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Lecture7–HPLC,23-10-2019

Ingeneral,the“diluteandshoot”approachcanbeusedformostdrugsubstancesandparenteralproducts.
Acommonprocessof“grind→extract→dilute→filter”isusedformostsoliddosageformssuchastabletsorcapsules.
Morecomplexdosageforms,suchassuppositories,lotions,andcreams,andphysiologicalsamples(serumorplasma)mightrequireadditionalsampleclean-upandextractionsuchasliquid-liquidextractionorsolid-phaseextraction(SPE).
TheoutputofpharmaceuticalsamplepreparationistypicallyanHPLCvialcontainingthefinaltestingsolutionwiththeextractedanalytesreadyforHPLCanalysis.
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Requirementsofadetector:
Sensitivetolowconcentrationsofeveryanalyte.
Smallvolumetoavoidpeakbroadening.
Linearresponse.
Insensitivetochangesintemperatureorsolventcomposition.
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Lecture7–HPLC,23-10-2019

:usingaflowcell,mostcommontype(why?).Employdeuterium,tungstenorxenonlampswithmonochromatorstochoosetheoptimumλ.
AspecialtypeofUVdetectors:thephotodiodearraydetectors(PDA).
:
Fluorescenceismeasuredafterexcitationoftheeluatewithalaser.
Adv.:verysensitiveDisadv.:-fluorescinganalytesbycovalentattachmentoffluorophorstoanalyteseitherpriortochromatographicseparation,orbyaddingderivatizationreagentstotheeluatebetweencolumnanddetector.
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Theflowcell

:
Respondstomostsolutes
Uselessingradientelution,.
Smalllinearrangeonly
Detectionlimit1000xpoorerthanthatofUVdetector
Itisadeflection-typedetector:
Twotriangular5-to10-Lcompartmentswherepuresolventoreluatepasses; whensoluteofdifferentrefractiveindexentersthecell,thebeamisdeflectedandthephotocelloutputchanges.
IRradiationmustberemoved(avoidheatingofsamplesoln.!)
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Lecture7–HPLC,23-10-2019