Atomic Absorption Spectroscopy| Instrumentation & applications

Definition: Atomic absorption spectroscopy is a type of quantitative analysis where in a specific wave length of light absorbed by atoms in neutral state is detected or recorded.

The more the number of the atoms, the more is the intensity of absorption and vice-verse.

This can also be called as metal analysis spectrometer as it mainly used for metal analysis.

Atomic absorption Spectroscopy theory:

The method relies on absorption method of spectroscopy.

The method involves, the spraying of sample in solution state  over a burner. This leads to evaporation of solvent and leave fine dry residue behind which is nothing but neutral atoms in ground state. To these atoms, a light of specific wave length is passed and the un-absorbed light is recorded over a detector.

Atomic absorption Spectroscopy Instrumentation:

Atomic absorption spectroscopy unlike other spectroscopy methods has two additional requirements like a specially designed lamp to produce light of desired  wave and a burner to prepare the sample for absorption of light.

The instrumentation includes:

1. The burner to dry the sample and produce atoms.

2. Sample container.

3. Fuel and oxidant to burn the sample by heat.

4. Hallow  cathode lamp to produce light of desired wave length.

5. Detector to detect the absorption intensity.

6. Amplifier and data recorder.

 

The burner: Here sample from the capillary rises to the tip of burner where it is burned with flame produced by the fuel and oxidant combination.  The sample after evaporation leaves a fine residue of neutral atoms.

Sample container: This is a beaker like container of sample which is placed below the burner preferably. A capillary tube drains the sample to the tip of burner.

Fuel and oxidant: This is a very important part of entire process to be remembered. If the heat produced is not sufficient then the sample doesn’t form neutral atoms. If the heat of burner is more, the sample molecules may ionize instead of forming atoms. So both are undesirable for experimentation.Hence a proper combination of fuels and oxidant are to be used to produce recommended temperatures. Commonly used flues include propane, Hydrogen and acetylene ad oxidants are mostly air or oxygen.

Hallow cathode lamp: This is another primary requirement in the entire process. If the element to be analyzed is magnesium, the cathode lamp made of magnesium is used and so for all the other metal elements analyzed like Na, Ca, K, Zn etc.

Detector: The used can be a simple photo multiplier tube or photo cell. The current or potential recorded for the sample absorption is recorded in a computer software and then analyzed.

Atomic Absorption Spectroscopy applications:

1. Atomic spectroscopy is used for quantitative analysis of metal elements in any sample.

2. It is specially useful to analyze trace metal elements in plasma  and other body fluids.

3. To determine metal elements in food industry.

4.To estimate Lead in petroleum products.

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