chromatography飞鱼星1260

AgilentTechnologiesAgilent1260InfinityIIHT-ELSD(G7826A)-ForMolecularWeightDeterminationTechnicalNoteHT-ELSDforMWDThe1260InfinityIIHT-ELSD(G7826A)canprovidealinearizedanalogueoutputwhichallowsthedetectortobeusedasalinearconcentrationdetectorreplacingrefractiveindex(DRI)orInfraRed(IR)inHT-GPCapplications.
Themainadvantageofusingthisdetectorforthisapplicationisthesignificantincreasedsensitivityofthehightemperatureevaporativelightscatteringdetector(ELSD)comparedwiththeDRIandIR;typically,theELSDis30timesmoresensitivitythanaDRI.
ThisincreasedsensitivityenablesdetectionofmuchlowerconcentrationwhichisessentialfortheanalysisofUHMWPEsamples.
DeterminationofthePowerFunctionTheELSDsignalinthefunctionofconcentrationislinearized,basedonapowerlawfunction:ELSDsignalintensitykELSDconcentrationaELSDTheexponent,αELSD,definedbyLinFintheinstrumentinterfaceissolventdependentbutNOTpolymertypedependent.
InTable1onpage2belowarepredeterminedPowerfunctionforcommonhightemperatureGPCsolvents.
Table1ELSDparametersfordifferentsolventsforHT-GPCofpolyolefinsSolventPolymersPowerReferencesTCBPS,PE,PP1.
612[]1,o-DCBPS,PE,PP1.
20butylalPS,PE,PP1.
35[3]xylenePS,PE,PP1.
40[4]Ifanewsolventisusedthatdoesn'thaveapredeterminedPowerfunctionthenyou'llneedtomeasurethearearesponseforseveralconcentrationsofaccuratelypreparedsolutionsintherange5–500g/ml[5].
Plottheresponseagainstconcentrationandfitthedatatoapowerfunctionasdescribedinreference[2].
ThepowercoefficientwhichbestfitsthedataistheonetobeusedasLinFparameterfortherespectivesolventandtestconditions.
2DeterminationofthePowerFunction1A.
Boborodea,S.
O'Donohue,Newevaporativelightscatteringdetectorforhightemperaturegelpermeationchromatography,,Int.
J.
Polym.
Anal.
Charact.
,vol22,no7,631-638(2017)2A.
Boborodea,S.
O'Donohue,Linearizationofevaporativelightscatteringdetectorsignal,Int.
J.
Polym.
Anal.
Charact.
,vol22,no8,685-689(2017)3A.
Boborodea,A.
Brookes,Polyolefincharacterizationindibutoxymethanebyhightemperaturegelperme-ationchromatographywithanewevaporativelightscatteringdetector,Polym.
Test.
,vol64,217-220(2017)4A.
Boborodea,F.
Mirabella,S.
O'Donohue,PolyolefinCharacterizationinXylenebyHigh-TemperatureGelPer-meationChromatographywithaNewEvaporativeLightScatteringDetector,Chromatographia,vol81,no3,419-424(2018)5A.
Boborodea,A.
Brookes,Investigationofsamplepreparationforhightemperaturegelpermeationchroma-tographyusingalowsolventconsumptionmethod,Polym.
Test.
,vol63,210-213(2017)3SettingUptheInstrumentSettingUptheInstrumentOncethepowerfunctionhasbeendeterminedfortheoperatingsolventitcanbeenteredontheinstrumentviathesecondsub-screenasshownbelow:MainScreenSub-screen1Sub-screen2Navigationbetweenthescreensisachievedbythearrowsonthekeypadwhenthecursorisonthearrow.
Sub-screen2allowschangestothefollowingelectronicparameters:DefaultRangeLinFLinearizationfunction1.
01.
00–2.
00ZEROBaselinepositiontheinstrumentiszeroedto100.
1–10SCALEScalingfactortoincreasepeakheightafterlinearizationfunctionapplied1.
01–354SettingUptheInstrumentOncetheLinFhasbeensetforthesolventbeingused,eachdatapointiscorrectedbythefollowingequation:CorrectedELSDELSDSignal1LinFTheneteffectisthatsignalislinear(seefigurebelow),buttheapparentsignalsensitivityisreducedandthereforetocompensateforthislossinsensitivitytheScalecanbeappliedtoamplifythesignalagain.
Figure1OverlayofPS135kchromatograms,concentrations:5to500g/mlFigure2PeakareaversusconcentrationlinearcorrelationovertwoordersofmagnitudeToobtaincorrectmolecularweightsthezerooffsetvalueappliedneedstosetthebaselineasclosetozeroaspracticallypossiblewithoutthedatabeatorbelowzeroorthecalculationwilljustreturnzeroandthuslossofdata.
ForTCB,therecommendedZerovalueis0.
1,butthisvaluecanbeslightlyincreasedupto1forsolventspresentingahigherlevelofbaselinenoise.
ToensurethatthebaselineissettothezerooffsetvaluebeforeeachrunweadviseusingCable(G7826-60015)withtheAgilent1260InfinityIIHTGPCSystemwhichisconnectedbetweentheInjSyncatthebackofthecontroldrawerandtheAuxI/OportattherearoftheHT-ELSDpriortoeachrun.
ThesamecanbeachievedforthirdpartyusersbyusingCable(0890-0055)withbothInjectSyncandAutozerolinesconnectedtotheinjector.
5Example–AnalysisofSRM1475aExperimentalConditionsExample–AnalysisofSRM1475aExperimentalConditionsAgilent1260InfinityIIHighTemperatureGPCSystem(G7820B)interfacedtoanAgilent1260InfinityIIHT-ELSD(G7826A).
Table2ChromatographyConditionsMobilephase1,2,4Tricholobenzene+250ppmBHTColumns3xPL-OlexisColumns,7.
5mmx300mmColumnOventemperature160°CFlowRate1.
0mL/minInjectionvolume200LConcentration1mg/mlforSRMPE1475aCalibrationStandardsEasiVialsPSstandardsPS-HTable3DetectorConditionsXfer(Transferlinetemperature)160°CNeb(Nebulisertemperature)160°CEvap(Evaporationtemperature)120°CGas(Gasflowrate)0.
4SLMSmth(smoothingfactor)60LED(Lightsourcepower)100%LinF1.
61Zero0.
3Scale16Example–AnalysisofSRM1475aAnalysisofPESRM1475sampleAnalysisofPESRM1475sampleEightanalyseswereperformedonPESRM1475sampleduringseveraldays,usingthesamesettingforthepowercoefficientforELSD,LinF=1.
61.
TheoverlayoftheobtainedchromatogramsinFigure3onpage6showsanexcellentreproducibility:Figure3OverlayofchromatogramsofPESRM1475sample7Example–AnalysisofSRM1475aAnalysisofPESRM1475sampleTheaveragemolecularweights,presentedinTable4onpage7areinexcellentagreementwiththeexpectedvaluesprovidedbyPESRM1475certificate(Mn=18310,Mw=53070g/mol,Mz=138000g/mol).
Table4AveragemolecularweightsdeterminedfromtheHT-ELSDchromatogramsusingconven-tionalGPCandpolystyrenecalibrationstandards(EasivialPS-H)InjectionMn(g/mol)Mw(g/mol)Mz(g/mol)NIST1475(01)1824257925145027NIST1475(02)1835357648144716NIST1475(03)1831457537143238NIST1475(04)1841157434142142NIST1475(05)1796056259138325NIST1475(06)1795056369140288NIST1475(07)1804456323139180NIST1475(08)1817056434139052ThefollowingMarkHouwink-SakuradaparameterswereusedinthecalculationtoconvertthePolystyreneequivalentmolecularweightvaluestoPolyethylenevalues:KPS=19*10-3mL/g;αPS=0.
655KPE=39*10-3mL/g;αPE=0.
725Example–AnalysisofSRM1475aAnalysisofPESRM1475sample*G7826-90020**G7826-90020*G7826-90020Edition:08/2018PrintedinGermanyAgilentTechnologies,Inc2018AgilentTechnologies,IncHewlett-Packard-Strasse876337WaldbronnGermanyThelinearizedELSDsignalisindependentofmolecularweightandthisisdemonstratedbytheexcellentagreementbetweentheMWDobtainedwithclassicalDRIdetectorandtheonegivenbyELSD,aspresentedinFigure4onpage8:Figure4ComparisonbetweenMWDobtainedwithDRIdetectorandELSDinTCBat160°CforPESRM1475sample