Gradient Performance Checks.pdf

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1、982LCGCNORTHAMERICAVOLUME22NUMBER10OCTOBER2004www.chromatographyonline.comGradientPerformanceChecksLCLCTroubleshootingradientelutionisusedwidelyThismonth’s“LCTroubleshooting”willGbothinresearchandproductiontakeacasestudyformat.We’lllookataliquidchromato

2、graphy(LC)sep-coupleofteststhatweperformduringourarations.Forroutineanalysesofdrugsinsemiannualinstrumentcheckandexaminebiologicalmatrices,ourlaboratorypreferserrorsthatwerediscoveredforoneinstru-tousegradientelutionratherthanisocraticmentthatuseslow-pr

3、essuremixing.Theseseparations.Abuilt-incleaningstepispartwillillustratetheneedforperiodicperfor-JonathanJ.GilroyandofeverygradientmethodthatfinishesatamancechecksofLCinstrumentation.JohnW.Dolanhighpercentageofstrongsolventandgiveslongercolumnlifewith“dir

4、ty”samples.TheTestJusthowgoodareyourModernequipmentprovidesaprecisionOursemiannualcheckincludesmeasure-andaccuracyofgradientcontrolthatwasmentsofflowrate,pressuredecay,retentiongradients?notpossiblewithpreviousgenerationsofreproducibility,andautosamplerp

5、recision.equipment.However,eventhebestequip-Thecoreoftheperformancetest,however,mentcanmalfunctionoccasionallyandisacheckofthesystem’sabilitytogeneratepartscanfail,soitiswisetotesttheperfor-accuratelineargradients.Thetestisquitemanceofthegradientperiodi

6、callytobesimple.HPLC-gradewaterisplacedinthesureitmeetsyourexpectations.Ofparticu-A-solventreservoir,andwatercontaininglarinterestaregradientlinearityandaccu-0.1%acetoneisplacedintheBreservoir.racy.TheseparameterscanaffectgradientThecolumnisremovedandre

7、placedwithreproducibilityandarecriticalforsmoothapproximately1mof0.005-in.i.d.tubing.transferofgradientmethodsfromonesys-Thedetectorwavelengthissetto265nm,temtoanother.andtheflowrateto1–2mL/mintocreateInourlaboratory,weperformasemian-sufficientbackpressu

8、reforreliablechecknualinstrumentperformancecheckonvalveoperation.eachLCsystemtoensurethatitisworkingForhigh-pressuremixingsystems,thereproperlyandtoidentifyanyearlywarningarejusttwotests.First,aseriesof4-minsignsofpendingtrouble.