EPA Method 306

2077METHOD306-DETERMINATIONOFCHROMIUMEMISSIONSFROMDECORATIVEANDHARDCHROMIUMELECTROPLATINGANDCHROMIUMANODIZINGOPERATIONS-ISOKINETICMETHODNote:Thismethoddoesnotincludeallofthespecifications(e.g.,equipmentandsupplies)andprocedures(e.g.,samplingandanalytical)essentialtoitsperformance.Somematerialisincorporatedbyreferencefromothermethodsin40CFRPart60,AppendixA.Therefore,toobtainreliableresults,personsusingthismethodshouldhaveathoroughknowledgeofatleastMethod5.1.0ScopeandApplication.1.1Analytes.AnalyteCASNo.SensitivityChromium7440-47-3SeeSec.13.21.2Applicability.Thismethodappliestothedeterminationofchromium(Cr)inemissionsfromdecorativeandhardchromeelectroplatingfacilities,chromiumanodizingoperations,andcontinuouschromiumplatingoperationsatironandsteelfacilities.1.3DataQualityObjectives.[Reserved]2.0SummaryofMethod.2.1Sampling.AnemissionsampleisextractedisokineticallyfromthesourceusinganunheatedMethod52078samplingtrain(40CFRPart60,AppendixA),withaglassnozzleandprobeliner,butwiththefilteromitted.Thesampletimeshallbeatleasttwohours.TheCremissionsarecollectedinanalkalinesolutioncontaining0.1Nsodiumhydroxide(NaOH)or0.1Nsodiumbicarbonate(NaHCO3).Thecollectedsamplesarerecoveredusinganalkalinesolutionandarethentransportedtothelaboratoryforanalysis.2.2Analysis.2.2.1Totalchromiumsampleswithhighchromiumconcentrations(35Fg/L)maybeanalyzedusinginductivelycoupledplasmaemissionspectrometry(ICP)at267.72nm.NOTE:TheICPanalysisisapplicableforthismethodonlywhenthesolutionanalyzedhasaCrconcentrationgreaterthanorequalto35Fg/LorfivetimesthemethoddetectionlimitasdeterminedaccordingtoAppendixBin40CFRPart136.2.2.2Alternatively,whenlowertotalchromiumconcentrations(35Fg/L)areencountered,aportionofthealkalinesamplesolutionmaybedigestedwithnitricacidandanalyzedbygraphitefurnaceatomicabsorptionspectroscopy(GFAAS)at357.9nm.2.2.3Ifitisdesirabletodeterminehexavalentchromium(Cr+6)emissions,thesamplesmaybeanalyzedusing2079anionchromatographequippedwithapost-columnreactor(IC/PCR)andavisiblewavelengthdetector.ToincreasesensitivityfortracelevelsofCr+6,apreconcentrationsystemmaybeusedinconjunctionwiththeIC/PCR.3.0Definitions.3.1TotalChromium-measuredchromiumcontentthatincludesbothmajorchromiumoxidationstates(Cr+3,Cr+6).3.2May-Impliesanoptionaloperation.3.3Digestion-Theanalyticaloperationinvolvingthecomplete(ornearlycomplete)dissolutionofthesampleinordertoensurethecompletesolubilizationoftheelement(analyte)tobemeasured.3.4Interferences-Physical,chemical,orspectralphenomenathatmayproduceahighorlowbiasintheanalyticalresult.3.5AnalyticalSystem-Allcomponentsoftheanalyticalprocessincludingthesampledigestionandmeasurementapparatus.3.6SampleRecovery-Thequantitativetransferofsamplefromthecollectionapparatustothesamplepreparation(digestion,etc.)apparatus.Thistermshouldnotbeconfusedwithanalyticalrecovery.3.7MatrixModifier-AchemicalmodificationtothesampleduringGFAASdeterminationstoensurethatthe2080analyteisnotlostduringthemeasurementprocess(priortotheatomizationstage)3.8CalibrationReferenceStandards-Qualitycontrolstandardsusedtochecktheaccuracyoftheinstrumentcalibrationcurvepriortosampleanalysis.3.9ContinuingCheckStandard-Qualitycontrolstandardsusedtoverifythatunacceptabledriftinthemeasurementsystemhasnotoccurred.3.10CalibrationBlank-Ablankusedtoverifythattherehasbeennounacceptableshiftinthebaselineeitherimmediatelyfollowingcalibrationorduringthecourseoftheanalyticalmeasurement.3.11InterferenceCheck-Ananalytical/measurementoperationthatascertainswhetherameasurableinterferenceinthesampleexists.3.12InterelementCorrectionFactors-Factorsusedtocorrectforinterferingelementsthatproduceafalsesignal(highbias).3.13DuplicateSampleAnalysis-Eithertherepeatmeasurementofasinglesolutionorthemeasurementofduplicatepreparationsofthesamesample.Itisimportanttobeawareofwhichapproachisrequiredforaparticulartypeofmeasurement.Forexample,nodigestionisrequiredfortheICPdeterminationandtheduplicateinstrument2081measurementisthereforeadequatewhereasduplicatedigestion/instrumentmeasurementsarerequiredforGFAAS.3.14MatrixSpiking-Analyticalspikesthathavebeenaddedtotheactualsamplematrixeitherbefore(Section9.2.5.2)orafter(Section9.1.6).Spikesaddedtothesamplepriortoapreparationtechnique(e.g.,digestion)allowfortheassessmentofanoverallmethodaccuracywhilethoseaddedafteronlyprovideforthemeasurementaccuracydetermination.4.0Interferences.4.1ICPInterferences.4.1.1ICPSpectralInterferences.Spectralinterferencesarecausedby:overlapofaspectrallinefromanotherelement;unresolvedoverlapofmolecularbandspectra;backgroundcontributionfromcontinuousorrecombinationphenomena;and,straylightfromthelineemissionofhigh-concentratedelements.Spectraloverlapmaybecompensatedforbycorrectingtherawdatawithacomputerandmeasuringtheinterferingelement.Atthe267.72nmCranalyticalwavelength,iron,manganese,anduraniumarepotentialinterferingelements.Backgroundandstraylightinterferencescanusuallybecompensatedforbyabackgroundcorrectionadjacenttotheanalyticalline.Unresolvedoverlaprequirestheselectionofanalternative2082chromiumwavelength.Consultth