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1、METHOD7000AATOMICABSORPTIONMETHODS1.0SCOPEANDAPPLICATION1.1Metalsinsolutionmaybereadilydeterminedbyatomicabsorptionspectroscopy.Themethodissimple,rapid,andapplicabletoalargenumberofmetalsindrinking,surface,andsalinewatersanddomesticandindustrialwastes.Whiledrinkingwaterfreeofparticu
2、latemattermaybeanalyzeddirectly,groundwater,otheraqueoussamples,EPextracts,industrialwastes,soils,sludges,sediments,andothersolidwastesrequiredigestionpriortoanalysisforbothtotalandacidleachablemetals.Analysisfordissolvedelementsdoesnotrequiredigestionifthesamplehasbeenfilteredandac
3、idified.1.2Detectionlimits,sensitivity,andoptimumrangesofthemetalswillvarywiththematricesandmodelsofatomicabsorptionspectrophotometers.ThedatashowninTable1providesomeindicationofthedetectionlimitsobtainablebydirectaspirationandbyfurnacetechniques.Forcleanaqueoussamples,thedetectionl
4、imitsshowninthetablebydirectaspirationmaybeextendeddownwardwithscaleexpansionandupwardbyusingalesssensitivewavelengthorbyrotatingtheburnerhead.Detectionlimitsbydirectaspirationmayalsobeextendedthroughconcentrationofthesampleand/orthroughsolventextractiontechniques.Forcertainsamples,
5、lowerconcentrationsmayalsobedeterminedusingthefurnacetechniques.ThedetectionlimitsgiveninTable1aresomewhatdependentonequipment(suchasthetypeofspectrophotometerandfurnaceaccessory,theenergysource,thedegreeofelectricalexpansionoftheoutputsignal),andaregreatlydependentonsamplematrix.De
6、tectionlimitsshouldbeestablished,empirically,foreachmatrixtypeanalyzed.Whenusingfurnacetechniques,however,theanalystshouldbecautionedastopossiblechemicalreactionsoccurringatelevatedtemperatureswhichmayresultineithersuppressionorenhancementoftheanalysiselement.Toensurevaliddatawithfu
7、rnacetechniques,theanalystmustexamineeachmatrixforinterferenceeffects(seeStep3.2.1)and,ifdetected,treatthemaccordingly,usingeithersuccessivedilution,matrixmodification,ormethodofstandardadditions(seeStep8.7).1.3Wheredirect-aspirationatomicabsorptiontechniquesdonotprovideadequatesens
8、itivity,referenceis
