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AuthorMichaelJ.Szelewski,KennethR.Weiner,andChin-KaiMengAgilentTechnologies,Inc.2850CentervilleRoadWilmington,Delaware19808-1610USAIntroductionThetechniquesofRetentionTimeLocking(RTL)[1],TargetCompoundScreening[2],andDeconvo-lutionReporting[3]alluseretentiontimes(RTs)foranadditionallevelofcompoundconfirmation.Itisimportantthatformaximumproductivityandquality,RTsareconstant/reproducibleandembed-dedinmassspectrallibraries[4].However,notallcompoundsareinacommerciallyavailablemassspectrallibrary,andmostmassspectrallibrariesdonothaveRTs.Thistechnicaloverviewdescribesbuildingandediting(forexample,addingcompounds)thefollowing:RTLScreenerdatabases,RTLQuantdatabases,andMassSpectralLibraries.Thesetasksareaccom-plishedusingtheGC/MSDChemStationsoftwareandMicrosoftExcel.RTLQuantdatabasesandMassSpectralLibrariescanalsobeusedwithAgilent'sDeconvolutionReportingSoftware[3].BuildingandEditingRTLScreener/QuantDatabasesandLibrariesTechnicalOverviewSoftwareRequirements•GC/MSDrevisionD.01.01(D.01.00sp1)orhigherMicrosoftExcelFileLocations(Filetypes:*.d,*.l,*.scd,and*.tab)Datafiles(*.d)inC:\MSDchem\1\data\Libraryfiles(*.l)inC:\Database\Screenerdatabasefiles(*.scd)inC:\DatabaseTAB-delimitedfiles(*.tab)inC:\Database2ColumnHeaderAopen(columnAisusedinGCforretentiontime(RT),notusedinMSD)Bname(compoundname,forexampledimethyl…)Ccas(CASnumberwithoutdashes,forexample,12345,not00012-34-5)Dmolecularformula(forexample,C6H14N2O,nocommas,dashes,quotesetc)Emolecularweight(forexample,32.04)FRT(GC/MSD,inminutes,forexample,12.34)Gopen(notused)HcompanyID(auniqueidentifier,forexample,cmpd01-moreexplanationonthislater)Ifilename(completefilepathfor.dusedforlibrarycreationsuchasC:\MSDchem\1\data\oxymix.d)Jtargetion(scdtargetion)Kq1(qualifier1)Lq1ratio(qualifier1ratio)Mq1unc(qualifier1uncertainty)Nq2(qualifier2)Oq2ratio(qualifier2ratio)Pq2unc(qualifier2uncertainty)Qq3(qualifier3)Rq3ratio(qualifier2ratio)Sq3unc(qualifier3uncertainty)Tunctp:0=rel,1=abs(uncertaintytype)URefLibName(libraryname)*VRefLibentrynum(entrynumberinthelibrary,suchas15)*BuildinganMSSpectralLibrary1.Builda(Screener)Libraryfromdatafiles(*.d)anda.tabfile.SeeTable1.The*.dfilesconsistofthepeaks/spectraofthelibraryentries.Table1.ExplanationofColumnsin.tabFileThecolumnsB,C,D,E,F,andIarerequired.Allothercolumnsareleftblank.Useonecompoundperrow.Seetheexamplebelow:Notethefirsttwolines(andonlytwolines)areforcommentandheaderinformation.*Notusedfororiginallibrarycreation.32.Makesureyousavethespreadsheetfilein.tabformatintheDatabasefolder.GotoFile|Saveas|andchooseText(Tabdelimited)(*.txt).Putthefilenameinquoteswitha.tabextensionsuchas“original.tab”.Thiswillsaveinatab-delimitedformatwitha.tabextension.3.ClickYestokeeptheformat.4.CLOSEtheExcelfile,otherwiseyouwillgetanerrormessage(Couldnotopenfile:C:\database\original.tab)fromMSDChemStation.5.ClickNo.46.GotoEnhancedDataAnalysis.Onthecom-mandlinetypertl_importandthenclickExecute.7.SelectLibraryonly,clickOK.8.YouwillbepromptedforafiletoselectfromtheDatabasefolder.Selectthe.tabyouwant,clickOpen.(Thescreenerdatabasecanalsobegeneratedatthesametimebyselectingthe“LibraryandSCD”optionasseeninalatersection.)59.Givethelibraryaname(maximumeightchar-acters),suchasoxymix.LandclickOK.EnhancedDAwillcalleachofthefilesinColumnIofyour.tabfile.ItwillthengototheRTyouspeci-fiedinColumnFandcreateaLibraryentryusingthatspectrumandtheinformationfromColumnsB,D,andE.Youshouldseechromatogramsflash-ingbeforeyoureyes.IfyoufillincolumnHofthe*.tabfile,youwillgeta.savdirectorywhenthelibraryisbuilt.Thefollowingscreenshowsthenewlibrary,Oxymix.L,theoxymix.tabfile,andthe.savdirectory.6Whatisthe.savdirectory?The.savisafoldercre-atedinDatabasefolderwhenyoucreateaLibraryfroma.tab.The.savfoldercontainsone.savfileforeachentryintheLibraryyoujustcreated.Each.savfilecontainsthespectrumoftheLibraryentry.The.savfilenameistakenfromColumnH.IfColumnHisleftblankyouwillgetnousable.savfiles.YoucanrebuildtheLibraryusingthe.savfilesifyoulosttheoriginaldatafiles.Inthedia-logueboxwhereyouenteredtheLibrarynamewhenyoufirstcreatedit,thereisa“more”button.Clicking“more”givesyouafieldtospecifywhetheryou'reusingoriginaldataor.savfiles.ListtheContentofaLibrary(*.l)1.Afterthelibraryisbuilt,typelistlibonthecommandlineandthenclickExecute.72.ChoosethelibrarynameyoujustcreatedthenclickOK.3.ClickNotothedetailedgraphicsquestion.Ifallwentwellyouwillseealistofyourlibraryentries,compoundnames,MW,CAS,etc.Ifyouseeonlyafewlinesoftextatthetop,thelibrarywasnotbuiltproperly.Gobackandfollowthebuild-a-librarystepsagaincarefully,especiallyenteringthecorrectdatafilenameandthedatapathincolumnIofthe.tabfile.8CreateanSCDandaLibraryFroma.tabFileThebestwaytocreatean.scdistocreateitwhenyoucreatetheLibrary.DoALMOSTexactlywhatyoudidtocreateaLibraryintheprevioussection.1.Afteryouexecutethertl_importcommand,select“LibraryandSCD”.2.ClickYes.An.scdwillbecreatedwiththesamenameyougivethelibrary.Thelargestionwillbethetargetion,andthenthenextthreelargestionswillbethequalifiers.Uncertaintypercentwillbegloballysetto20.Uncertaintytypewillbegloball