By Sunil Bhardwaj

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The main components of AAS are:

1) Source of Radiations: It is consist of the glass jacket containing cup shaped cathode made up of the same element which is under Study. A tungsten wire (plate) Acts as anode which is arranged in the same glass jacket. The glass jacket is filled with the inert gas like Neon (Ne) or Argon (Ar) at a low pressure. When a Potential of 500-1000 volt is applied between the two electrodes from the power supply the atoms of the inert-gas is ionized. The positive charged ions moving towards cathode. These fast moving ions remove the atoms from the surface of cathode. This process is called Sputtering. These metallic atoms then collide with highly energetic gas ions and some of them are excited. These excited metal atoms emit their characteristics radiations when they return to the original state with emitting their characteristic radiations.

The cathode and anode is connected with the power supply from where we supply the potential of 500-1000 volt. The gas taken in the bulb is ionized. The cations of the gas are moving fast towards cathode and remove the atoms from the cathode. These atoms strike With the gas ions and transition take place, return to the original state with the emission of characteristic radiations which pass (penetrate) out the quartz window and are incident on rotating chopper, it produce intermittent radiations which are incident on the Unexcited atoms present in the flame of the burner. These atoms absorb the radiations. The transmitted is incident on the prism which is connected with the PMT. In PMT current is produced. PMT is connected with read out meter which gives the absorbance. Now, by applying the Beer-Lamberts Low, we can find out the conc. of solution by knowing the absorbance.

Application:

1. Quantitative Analysis can be done using Calibration Curve Method.

2. Very low concentration which is 1 ppm or less than that can also be analyzed accurately with the help of A.A.S.

3. With the help of A.A.S. we can detect the toxic elements such as Cu, Ni, Zn present in the food products.

4. The phenomenon is used to estimate Na and K present in the Blood serum.

5. How much amount of Pb (lead) is present in the Petrol can be found out with the help of A.A.S.

6. Soil extracts plant materials fertilizers have been analyzed for determination of Na, K, Cu, Mg, Mo, V etc. are present.

7. The amount of Ti and V present in the steel alloy can also be determined with the help of A.A.S.

Limitations:

1. Simultaneous analysis of many elements is not possible.

2. Metals like La, W, Si, etc. form the stable metallic oxide and so cannot be analyzed.

3. For alkali metals like Li, Na, K etc. which has low I.P. in such cases low temp. of the flame is required to minimize the ionization of the elements.

4. Each element requires the separate lamp.

5. If the sample contains the two elements which absorb the light of same Wavelength ((lambda)) e.g. Mn and Ga both absorb at 403nm can not be analyzed. In such case we must remove the interfering radical.

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