EPA-SW-846-Test-Methods-for-Evaluating-Solid-Waste

THREE-1Revision4February2007CHAPTERTHREEINORGANICANALYTESPriortoemployingthemethodsinthischapter,analystsareadvisedtoconsultthedisclaimerstatementatthefrontofthismanualandtheinformationinChapterTwoforguidanceontheallowedflexibilityinthechoiceofapparatus,reagents,andsupplies.Inaddition,unlessspecifiedinaregulation,theuseofSW-846methodsisnotmandatoryinresponsetoFederaltestingrequirements.TheinformationcontainedineachprocedureisprovidedbyEPAasguidancetobeusedbytheanalystandtheregulatedcommunityinmakingjudgmentsnecessarytomeetthedataqualityobjectivesorneedsfortheintendeduseofthedata.3.1INTRODUCTIONThischapterprovidesguidancefortheanalysisofinorganicanalytesinavarietyofmatrices.Theanalyticalmethodsarewrittenasspecificstepsintheoverallanalysisscheme--samplehandlingandpreservation,sampledigestionorpreparation,andsampleanalysisforspecificinorganiccomponents.Fromthesemethods,theanalystshouldassembleatotalanalyticalprotocolwhichisappropriateforthesampletobeanalyzedandfortheinformationrequired.Thisintroductiondiscussestheoptionsavailableingeneralterms,providesbackgroundinformationontheanalyticaltechniques,andhighlightssomeoftheconsiderationstobemadewhenselectingatotalanalysisprotocol.3.2DEFINITIONSThefollowingtermsarerelevantforthedeterminationofinorganicanalytes:Calibrationblank:Avolumeofreagentwaterpreparedwiththesameamountsofacidsorotherreagentsaswerethestandardsandsamples.Calibrationcurve:Thefunctionalrelationshipbetweenanalyticalresponseandtargetanalyteconcentrationdeterminedforaseriesofcalibrationstandards.Thecalibrationcurveisobtainedbyplottingtheanalyticalresponseversusconcentrationandperformingaregressionanalysisofthedata.Calibrationstandards:Aseriesofsolutionscontainingthetargetanalyteatknownandvaryingconcentrationsusedbytheanalystforinstrumentcalibration(i.e.,preparationofthecalibrationcurve).Continuingcalibrationverification(CCV):Asolutioncontainingaknownconcentrationofanalytederivedfromthesamesourceasthecalibrationstandards.TheCCVisusedtoassurecalibrationaccuracyduringeachanalysisrun.Itshouldberunforeachanalyteasdescribedintheparticularanalyticalmethod.Ataminimum,itshouldbeanalyzedatthebeginningoftherunandafterthelastanalyticalsample.TheCCVconcentrationshouldbeatornearthemid-rangelevelsofthecalibrationcurve.Dissolvedmetals:Theconcentrationofmetalsdeterminedinanaqueoussampleafterthesampleisfilteredthrougha0.45-µmfilter(seeMethod3005).Initialcalibrationverification(ICV)standard:Acertifiedorindependently-preparedsolutionfromasourceotherthanusedforthecalibrationstandardsandusedtoTHREE-2Revision4February2007verifytheaccuracyoftheinitialcalibration.ForICPanalysis,itshouldberunateachwavelengthusedintheanalysis.Instrumentdetectionlimit(IDL):Typicallyusedinmetalsanalysistoevaluatetheinstrumentnoiselevelandresponsechangesovertimeforanalytesofinterest.IDLscanbeestimatedbycalculatingtheaverageofthestandarddeviationsofthreeanalyticalrunsperformedonthreenon-consecutivedaysfromtheanalysisofareagentblanksolutionwithsevenconsecutivemeasurementsperday.Eachmeasurementshouldbeperformedasthoughitwereaseparateanalyticalsample(i.e.,eachmeasurementmustbefollowedbyarinseand/oranyotherprocedurenormallyperformedbetweentheanalysisofseparatesamples).IDLsshouldbedeterminedatleastonceeverythreemonthsorataproject-specificdesignatedfrequencyandtheassociateddocumentationkeptwiththeinstrumentlogbook.Interferencechecksample(ICS):AsolutioncontainingbothinterferingandanalyteelementsofknownconcentrationthatcanbeusedinmetalsICPandICP-MSanalysistoverifybackgroundandinter-elementcorrectionfactors.Laboratorycontrolsample(LCS):Avolumeofreagentwaterspikedwithknownconcentrationsofanalytesandcarriedthroughthesamepreparationandanalysisprocedureasasample.Itisusedtomonitoranalyteloss/recovery.TheLCSmayeitherbepreparedfromthesamesourceasthecalibrationstandardsorindependentlyofthecalibrationstandards.AnindependentlypreparedLCSmayeitherbeobtainedasorpreparedfromacertifiedreferencesolutionorpreparedfromacertifiedreagentsolidorfromanalternatelotreagentsolidrelativetothecalibrationstandardssource.Foreachanalyticalbatch,atleastoneLCSshouldbepreparedfromthesamesourceasthecalibrationstandards.Inthisway,iftherecoveriesofboththeLCSandthematrixspikeareoutsidetheacceptancelimits,theanalystwillbeabletodeterminewhethertheproblemisduetoacalibrationerrororamatrixinterference.Lineardynamicrange:IneitherICP-AESandICP-MSanalysisbasedonaone-pointcalibration,theconcentrationrangeabovethehighestcalibrationpointoverwhichthefunctionalrelationshipbetweenanalytesignalandanalyteconcentrationremainslinear.Asampleresultthatfallswithinthelineardynamicrangeisconsideredvalidandmaybereported,thusavoidingtheneedtodiluteandreanalyzethesample.Methodblank:Avolumeofreagentwaterprocessedthrougheachsamplepreparationprocedure.Analysisofamethodblankisusedtoassesscontaminationfromthelaboratoryenvironment,sampleprocessingequipment,and/orreagents.Lowerlimitofquantitation(LLOQ):Thelowestpointofquantitation,orinmostcases,thelowestpointinthecalibrationcurvewhichislessthanorequaltothedesiredregulatoryac