7LIGHT SOURCES Hollow Cathode Lamps Anot-Tungsten wire Cathode made from the element of interest (Na,K,Ca..)Argon or neon gas
8LIGHT SOURCES Electrodeless Discharge Lamp Typically argon gas at low pressureNarrower line widthNot prefered
9ATOMIZATION -Flame atomizer Compounds making up the sample are broken into free atoms.High temperature is necessaryBasic two types-Flame atomizer-Electrothermal atomizer
10TYPES OF ATOMIZERS FLAME ATOMIZER Simplest atomization Converts analyte into free atoms of vapor phaseFlammable &caustic gasesNot has an inert medium (−)Short analysis time (−)
11TYPES OF ATOMIZERS ELECTROTHERMAL ATOMIZER A cylindirical graphite tubeInert gas medium (Argon gas)Longer anlaysis time than flameSuperior sensitivity, high accuracy
12MONOCHROMATOR Also it is called wavelengh selector Select the specific wavelenghtPolychromatic light →monochromatic lightSimple one is enough for AAS
13DETECTOR Electromagnetic waves → electric current The most used one Photomultiplier tubeHave fast response times
14CALIBRATION TECHNIQUES Two main techniquesCalibration curve methodStandart addition method
15CALIBRATION TECHNIQUES CALIBRATION CURVE METHODDraw a graphHave two or more variables-One is set at known values-One is measured responseMost convenient for a large number of similar samples analysis.
16CALIBRATION TECHNIQUES An example of calibration curve method
17CALIBRATION TECHNIQUES STANDART ADDITION METHODTo measure the analyte concentration in a complex matrix.Most convenient for small number of samples analysisPrevent effect of chemical & spectral interferences
18INTERFERENCES Causes higher or lower absorbance value Two major groups Chemical InterferencesSpectral Interferences
19CHEMICAL INTERFERENCES The most common one in flame atomizer.Consequence of chemical reactions.Reduce amount of oxygen in flame to overcome
20SPECTRAL INTERFERENCES Absorption or emission of the radiation at the same wavelengthRadiation which is absorbed→pozitive errorsRadiation which is emmitted→negative errors
21SPECTRAL CORRELATION METHODS TWO-LINE CORRELATION METHODSelect two linecharacteristic wavelength of analytevery close to analyte line but not absorbed by analyteMeasure the difference between two lines
22SPECTRAL CORRELATION METHODS CONTINUUM SOURCE CORRELATION METHODSelect two lampsDeuterium lamp & hollow cathode lampWhen hollow cathode lamp is used total absorbace is measuredWhen deuterium lamp is used only background absorption is measuredMeasure the difference between two lines.
23SPECTRAL CORRELATION METHODS ZEEMAN EFFECT CORRELATION METHODPresence of magnetic field.Splitting of spectral lines.
24-12CONCLUSIONOne of the most important technique in quantitative analysisIt is based on the absorption of radiationMeasurements could be done at ppb levelsIt’s widely used methodThe preparation of the sample is usually simple and rapid
25CONCLUSION There are many adventages High sensitivity [10-10 g (flame), g (non-flame)]Good accuracy(Relative error 0.1 ~ 0.5 % )High selectivity
26APPLICATIONS OF AASWater analysis (e.g. Ca, Mg, Fe, Si, Al, Ba content)Food analysisAnalysis of animal feedstuffs (e.g. Mn, Fe, Cu, Cr, Se,Zn)Analysis of soilsClinical analysis (blood samples: whole blood, plasma,serum; Ca, Mg, Li, Na, K, Fe)