atomic absorption spectrophotometry cookbook原子吸收分光光度法食谱

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1、ATOMICABSORPTIONSPECTROPHOTOMETRYCOOKBOOKSection1BasicConditionsofAnalysisofAtomicAbsorptionSpectrophotometryAtomicAbsorptionSpectrophotometryCookbook-25-Section1CONTENTS1.PrincipalofAtomicAbsorptionSpectrophotometry11.1Whyatomsabsorblight11.2Relationbetween

2、lightabsorptionrateandatomicdensity21.3Sampleatomizationmethod3a)Flameatomicabsorption3b)Electro-thermalatomicabsorption52.BasicConditionforAnalysis92.1Conditionsofequipment9a)Analysisline9b)Slitwidth13c)Lampcurrentvalue142.2Analysisconditionsofflameatomicab

3、sorption15a)Flameselection15b)Mixingratioofoxidantandfuelgas17c)Beampositioninflame172.3Analysisconditionsofelectro-thermalatomicabsorption18a)Dryingcondition18b)Ashingcondition19c)Atomizingcondition21d)Sampleinjectionquantity231.PrincipalofAtomicAbsorptionS

4、pectrophotometry-25-1.1WhyatomsabsorblightTheatomicabsorptionspectrometryusesabsorptionoflightofintrinsicwavelengthsbyatoms.Allatomsareclassifiedintothosehavinglowenergiesandthosehavinghighenergies.Thestatehavinglowenergiesiscalledthegroundstateandthestateha

5、vinghighenergiesiscalledtheexcitedstate.Theatominthegroundstateabsorbsexternalenergiesandisputintheexcitedstate.Forexample,sodiumismainlyintwoexcitedstates,havinghigherenergiesby2.2eVand3.6eVrespectivelythaninthegroundstate,asshowninFig.1.1.(eVisaunittomeasu

6、reenergiesandiscalledanelectronvolt”.)When2.2eVenergyisgiventothesodiumatominthegroundstate,itmovesuptotheexcitedstatein(I)andwhen3.6eVenergyisgiven,itmovesuptotheexcitedstatein(II).Energyisgivenaslight,and2.2eVand3.6eVrespectivelycorrespondtoenergyoflightat

7、589.9nmand330.3nmwavelength.Inthecaseofsodiuminthegroundstate,onlylightofthesewavelengthsareabsorbedandnootherwavelengthlightisabsorbedatall.Fig.1.1SodiumenergystatesThedifferencebetweenenergiesinthegroundstate,andintheexcitedstateisfixedbytheelementandwavel

8、engthoflighttobeabsorbed.Atomicabsorptionspectrometryusesthehollowcathodelamp(HCL).TheHCLgivesofflightcharacteristictotheelementalwavelengthbeingmeasured.Thus,thelightabsorbedmeasurestheatomicde