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SELİN CANSU ÖZTÜRK ŞEYMA ATAKUL SEZİN GÜNER. ATOMIC ABSORPTION SPECTROMETER Introduction Invention Working Principle of AAS Instrumentation Interferences.

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Presentation on theme: "SELİN CANSU ÖZTÜRK ŞEYMA ATAKUL SEZİN GÜNER. ATOMIC ABSORPTION SPECTROMETER Introduction Invention Working Principle of AAS Instrumentation Interferences."— Presentation transcript:

1 SELİN CANSU ÖZTÜRK ŞEYMA ATAKUL SEZİN GÜNER

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

3 INVENTION Introduced in 1955 by Alan Walsh in Australia Firstly used for mining, medical treatment&agriculture Alan Walsh( ) rs/walsh2.html

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

5 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

6 INSTRUMENTATION

7 LIGHT SOURCES Hollow Cathode Lamps Anot-Tungsten wire Cathode made from the element of interest (Na,K,Ca..) Argon or neon gas

8 LIGHT SOURCES Electrodeless Discharge Lamp Typically argon gas at low pressure Narrower line width Not prefered

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

10 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 ( − )

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

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

13 DETECTOR Electromagnetic waves → electric current The most used one Photomultiplier tube Have fast response times

14 CALIBRATION TECHNIQUES Two main techniques  Calibration curve method  Standart addition method

15 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.

16 CALIBRATION TECHNIQUES An example of calibration curve method

17 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

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

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

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

21 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

22 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.

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

24 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

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

26 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)

27 REFERENCES Absorption-Determination-of-Zinc-and-Copper-in-a- Multivitamin Absorption-Determination-of-Zinc-and-Copper-in-a- Multivitamin english/presentations-phrases.htm english/presentations-phrases.htm

28 THANKS FOR YOUR ATTENTION..


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