SELİN CANSU ÖZTÜRK ŞEYMA ATAKUL SEZİN GÜNER

SELİN CANSU ÖZTÜRK ŞEYMA ATAKUL SEZİN GÜNER

ATOMIC ABSORPTION SPECTROMETER Introduction Invention Working Principle of AAS Instrumentation Interferences & Correlation Methods Applications

INVENTION Introduced in 1955 by Alan Walsh in Australia Firstly used for mining, medical treatment&agriculture Alan Walsh(1916-1998) http://www.science.org.au/academy/memoi rs/walsh2.html

PROPERTIES OF AAS The most widely used method in analysis of elements Based on the absorption of radiation So sensitive (ppb) Quantitative analysis

WORKING PRINCIPLE OF AAS Electrons promote to higher orbitals for a short amount of time by absorbing a energy M + hv M* Relises on Beer-Lambert Law A= a.b.c

INSTRUMENTATION www.scientificlib.com

LIGHT SOURCES Hollow Cathode Lamps Anot-Tungsten wire Cathode made from the element of interest (Na,K,Ca..) Argon or neon gas http://www.safir.be/aas.ht

LIGHT SOURCES Electrodeless Discharge Lamp Typically argon gas at low pressure Narrower line width Not prefered www.freepatentsonline.com

ATOMIZATION Compounds making up the sample are broken into free atoms. High temperature is necessary Basic two types -Flame atomizer -Electrothermal atomizer

TYPES OF ATOMIZERS FLAME ATOMIZER Simplest atomization Converts analyte into free atoms of vapor phase Flammable &caustic gases Not has an inert medium ( ) Short analysis time ( )

TYPES OF ATOMIZERS ELECTROTHERMAL ATOMIZER A cylindirical graphite tube Inert gas medium (Argon gas) Longer anlaysis time than flame Superior sensitivity, high accuracy

MONOCHROMATOR Also it is called wavelengh selector Select the specific wavelenght Polychromatic light monochromatic light Simple one is enough for AAS

DETECTOR Electromagnetic waves electric current The most used one Photomultiplier tube Have fast response times www.answers.com

CALIBRATION TECHNIQUES Two main techniques Calibration curve method Standart addition method

CALIBRATION TECHNIQUES CALIBRATION CURVE METHOD Draw a graph Have two or more variables -One is set at known values -One is measured response Most convenient for a large number of similar samples analysis.

CALIBRATION TECHNIQUES An example of calibration curve method

CALIBRATION TECHNIQUES STANDART ADDITION METHOD To measure the analyte concentration in a complex matrix. Most convenient for small number of samples analysis Prevent effect of chemical & spectral interferences

INTERFERENCES Causes higher or lower absorbance value Two major groups Chemical Interferences Spectral Interferences

CHEMICAL INTERFERENCES The most common one in flame atomizer. Consequence of chemical reactions. Reduce amount of oxygen in flame to overcome

SPECTRAL INTERFERENCES Absorption or emission of the radiation at the same wavelength Radiation which is absorbed pozitive errors Radiation which is emmitted negative errors

SPECTRAL CORRELATION METHODS TWO-LINE CORRELATION METHOD Select two line characteristic wavelength of analyte very close to analyte line but not absorbed by analyte Measure the difference between two lines

SPECTRAL CORRELATION METHODS CONTINUUM SOURCE CORRELATION METHOD Select two lamps Deuterium lamp & hollow cathode lamp When hollow cathode lamp is used total absorbace is measured When deuterium lamp is used only background absorption is measured Measure the difference between two lines.

SPECTRAL CORRELATION METHODS ZEEMAN EFFECT CORRELATION METHOD Presence of magnetic field. Splitting of spectral lines.

CONCLUSION One of the most important technique in quantitative analysis It is based on the absorption of radiation Measurements could be done at ppb levels It s widely used method The preparation of the sample is usually simple and rapid

CONCLUSION There are many adventages High sensitivity [10-10 g (flame), 10-14 g (non-flame)] Good accuracy (Relative error 0.1 ~ 0.5 % ) High selectivity

APPLICATIONS OF AAS Water analysis (e.g. Ca, Mg, Fe, Si, Al, Ba content) Food analysis Analysis of animal feedstuffs (e.g. Mn, Fe, Cu, Cr, Se,Zn) Analysis of soils Clinical analysis (blood samples: whole blood, plasma,serum; Ca, Mg, Li, Na, K, Fe)

REFERENCES http://www.scribd.com/doc/10513921/atomic- Absorption-Determination-of-Zinc-and-Copper-in-a- Multivitamin http://www.hemlin.pp.se/usstarten.html http://www.learn-english-today.com/businessenglish/presentations-phrases.htm

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