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Lab2determinationofheavymetals insoilbyatomicabsorptionspectrometry DATE:2012-9-19 Name:xxx Groupnumber:x Partners:xxx ⅠObjectives 1.Tofurtherunderstandtheprinciplesofatomicabsorptionspectrometry 2.learnhowtooperatetheatomicabsorptionspectrometry. 3.Getfamiliarwiththeapplicationofatomicabsorptionspectrometry 4.Learnhowtouseastandardcurveforquantitativeanalysis ⅡMaterialsandapparatus: Atomicabsorptionspectrometry;Cuhollowcathodelamp;ACvoltagestabilizer;oil-freegascompressor;acetylenecylinder;oscillator;sampleboat;Erlenmeyerflaskwithstopper(100ml);beaker;graduatecylinder;pipette ⅢTheory 1.AtomicAbsorptionSpectrometryisatechniqueformeasuringquantitiesofchemicalelementspresentinenvironmentalsamplesbymeasuringtheabsorbedradiationbythechemicalelementofinterest.Theatomsabsorbultravioletorvisiblelightandmaketransitionstohigherenergylevels.Adetectormeasuresthewavelengthsoflighttransmittedbythesample,andcomparesthemtothewavelengthswhichoriginallypassedthroughthesample.Atomsofanelementemitacharacteristicspectralline.Everyatomhasitsowndistinctpatternofwavelengthsatwhichitwillabsorbenergy,duetotheuniqueconfigurationofelectronsinitsoutershell.Thisenablesthequalitativeanalysisofasample. 2.TheconcentrationiscalculatedbasedontheBeer-Lambertlaw.Theabsorbancewithinacertainrangeisproportionaltotheconcentrationoftheelementundertestinvapor-phasegroundstateatoms.Theconcentrationisusuallydeterminedfromacalibrationcurve,obtainedusingstandardsofknownconcentration. 3.CalibrationCurveMethod:Preparestandardsolutionsofatleastthreedifferentconcentrations,measuretheabsorbanceofthesestandardsolutions,andprepareacalibrationcurvefromthevaluesobtained.Thenmeasuretheabsorbanceofthetestsolutionadjustedinconcentrationtoameasurablerange,anddeterminetheconcentrationoftheelementfromthecalibrationcurve. ⅣProcedures 1.OperatingprocedureforAAS (1)Inspectmajorcomponentstoensureoperatingnormal. (2)Installrequiredhollowcathodelamp.Select“T”beforeturningtothepowerandhollowcathodelamp.Thenselectappropriatelampcurr