LC foundational exam文档格式.docx
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LC foundational exam文档格式.docx
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CThestationaryphaseonly.
7Qualitativeanalysisisusedtodeterminetheanountofaparticularcompoundinasample.错
Section2
1Whichofthefollowingwouldbeconsideredasanacceptablevalueforpeakasymmetry?
A1.2B1.5C2.0D5
2Ifretentiontime=20.5minutesandvoidvolume=1.5minutes,whatistheretentionfactor?
A5.3B9.7C12.7D15.3
3Whichofthefollowingisthelargestfactorcontributingtoband–broadening?
AmobilephaseBflowrateCPHDcolumn
4Itisimportanttohavewell-resolvedpeaksonthechromatogramsothataccuratemeasurementsmaybemadeoftheareaand/ortheheightofeachindividualspeak.对
5Highretentionfactorsindicatethatthesampleisinteractingstronglywiththestationaryphase.对
6Forhighretentionfactorvalues,increasingtheselectivityorefficiencyisausefulwaytoimproveresolution.对
7Theefficiencyofapeakisameasureofthe“spread”oftheanalytebandthroughthecolumnandsystem.Ameasureofthedispersioniscalledtheplatenumber(N)orplatecount.
8Whatisthemosteffectivewaytoaltertheretentionfactorofapeak?
Apreparethesampleinadifferentway
Bchangethetemperatureofthecolumnduringtheexperiment
Cincreasetheflowratefortheexperiment
Dadjustthesolventstrengthofthemobilephase
9Doublingthecolumnlengthdoublestheanalysis,andalso:
Aincreaseresolutionbyafactorof2
Bincreaseresolutionbyafactorofabout1.4
Cdecreasesresolutionbyafactorof2
Ddecreasesresolutionbyafactorofabout1.4
10Ifthevoidvolume=1.5min,theretentionforpeakA=4min,andretentiontimeforpeakB=9min,whatistheselectivity?
A3B5C7D9
11Forwhichrangedoeschangingtheresolutionfactorhavethegreatesteffectonincreasingresolution?
A1to5
B5to10
C10to15
D15andhigher
12Factorsthataffecttheselectivityofaseparationarethestationaryphase(thecolumn),temperatureandorganicsolvent
Section3
1Whatisthenameoftheequationthatcombinesthemainfactorscontributingtobandbroadeningwithinacolumn?
AVanderwaals
BVanHuygens
CVanderboys
DVanDeemter
2Smallerparticlesincolumnswithafixedlinearflowleadtowhichofthefollowing?
Aboraderpeaks
BNarrowerpeaks
3Inordertominimizelongitudinaldiffusion,andkeeppeaksasnarrowaspossible,youshould:
Akeepsystemtubingasshortaspossible
BUsecorrectnuts,ferrulesandfittings
Cusehigherflowratesofmobilephase
DAlloftheabove
4WhichtermintheequationHETP=A+B/u+Curepresentseddydiffusion?
AA
BB/u
CCu
5Inordertominimizemasstransfereffects,andkeeppeaksasnarrowaspossible,youshould:
Auselargerdiameterparticlesinthestationaryphase
Busehighermobilephaseflowrates
Ccoolthecolumn
Dnoneoftheabove
Section4
1WhichoneofthefollowingfactorschangesdurninggradientHPLCanalysis?
Atheflowrate
Bthemobilephasecomposition
Cthesampleconcentration
Dthepressure
2ThemainreasonfortheshapeofthepeaksingradientHPLCisthateachcompoundelutesformthecolumnatapproximatelythesamespatetimearedifferent
3Importantparametersforagradientare
AtheinitialproportionofsolventBinthemobilephase
BthefinalproportionofsolventBinthemobilephase
Cthegradienttimes(steepness)inmovingfromintial%Btofinial%B
Dalloftheabove
4Gradientelutionismostusefulforreverse-phaseofion-exchangeLCexperiments
5WhichoneofthefollowingfactorsremainsconstantinisocraticHPLC
Athetemperature
Bthebackpressureinthesystem
Ctheflowrate
Dthecompositonofthemobilephase
6Whenseparationtimeisavitalissue,youshouldusealongcolumnandranatanormalflowrate
7Whenmaximumresolutionsisimportant,youshoulduseashortcolumnandahighflowrate
8ForagradientHPLCexperiments,ifthecolumnlengthischangedforthesamesample,itispossiblethattheelutionorderforthecomponentswillvary.
9ForgradientHPLCacquisitions,theresinoneedforanyspecialequipmenttomixthesolventson-line.
10Gradientelutionisverysuitableforwhichofthefollowing(checkallthatapply)?
@applicationswithstrongly-retainedadditives
@lonpairapplications
@normalphaseLConbaresilica
@noneoftheabove
11ForagradientHPLCexperiment,thepeaksaregenerallynarrowwithalmostequalpeakwidths.
12Isocraticmethodscanleadtoirreversiblecontaminationofthecolumnbyadsorptionofsomesampleconponentsontothecolumn
13PoorresolutionorearlyelutionofpeaksisapossibleprobleminanisocraticHPLCanalysis.
Section5
1Youdonotneedtoknowwhathecompoundactuallyisinordertogetanaccuratevaluefortheconcentrationinthesample.
2Peakswithsymmetryvaluesgreaterthan3canstillbeusedinquantitation
3Calibrationsisvitaltoobtainaccurateconcentrationlevelsforacompoundinasample
4Inquantitativeanalysis,itisimportantthatyouknowtheidentityofthecomponenttobeanalyzed.
5Inordertobemoreconfidentinpeakidentification,itisbettertoruntheunknownsamplesandtheknownreferenceunder
Retentiontimesandresponse
6Injectionvolumedoesnotimpactheightorareaofchromatographicpeaks
7Inquantitativeanalysis,itisnotimportantthatseparationofbaseline-resolved,overlapping,ortailingpeakscanstillbeaccuratelyanalyzed.
8Theregressioncoefficientisastatisticalmeasureoftheaccuracyoffitfortheregressionlinetotheactualdatapointsofacalibration.
9Inquantitativeanalysis,itisnotimportantforsamplepreparationtobereproducible.
10Inallcases,theuseofknownreferencestandardsunderidenticalexperimentalconditionspermitesthecorrectidentificationoftheunknowncomponent
11Thepurposeofqualitativeanalysisistodeterminethecomponentsthatareactuallyinasample
12Whichofthefollowingareproblemswiththearea%(normalization)method?
Aitassumesequaldetectorresponseforallcomponentsandanalytes
Bitassumesthatallcomponentselutefromthecolumn
Ccontaminants,carry-over,andsimalrissuesmayinterferewithquantitation
13Whichofthefollowingisthetermfortheminimumamountofanalytethatcanbereliablydetected?
Alimitofquantitation
Blimitofdetection
Climitofcalibration
Dnoneoftheabove
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