The Fundamentals of Atomic Absorption Spectroscopy

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Published: 06th November 2012
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The analytical method used to qualitatively and quantitatively determine the amount of chemical elements in a given sample is known as Atomic Absorption Spectroscopy or AAS. Here are some main fundamentals about Atomic Absorption Spectroscopy

The analytical method used to qualitatively and quantitatively determine the amount of chemical elements in a given sample is known as Atomic Absorption Spectroscopy or AAS. Absorption of light by free atoms in their gaseous state is employed in this method. Analytical Chemistry uses this procedure to find out the concentration of a particular element, known as the analyte, in the sample under consideration. Around 70 different elements in solution or solid samples can be determined with this method.

A Short History

This method and its underlying principles of Atomic Absorption Spectroscopy were pioneered in the last half of the 19th century by the of Heidelberg professors Gustav Robert Kirchhoff and Robert Wilhelm Bunsen. A modern touch was given to Atomic Absorption Spectroscopy by the team of Australian Chemists led by Sir Alan Walsh during the 1950ís.

AAS Instrumentation

In order to effectively examine a sample using Atomic Absorption Spectroscopy, it has to be atomized first. Different kinds of atomizers are available in the market for this purpose, but the most commonly used ones are flames and electrothermal atomizers. Shortly afterwards, the atoms are subjected to optical radiation. The radiation source is either an element-specific line source or a continuum radiation source. The radiation then goes through a monochromator such that the radiation belonging to the particular element is separated from the others.

Flame Atomizers

One of the most widely used kind of atomizers in Atomic Absorption Spectroscopy are Flame Atomizers. Liquid as well as dissolved samples can be used with flame atomizers. The sample under examination is first aspirated with the help of a pneumatic nebulizer and after that it is transformed into aerosol which in further introduced into a spray chamber. The flame gases in the chamber are then missed with this and the conditioning is done so well that only the finest droplets enter the flame. This process is responsible for confirming that only 5% of the sample reaches the flame, along with guaranteeing a high freedom from interference.

The burner head, which is placed on top of the spray chamber, is what is responsible for emitting a flame that is generally 5-10 cm long and a few mm deep. The radiation beam then passes through the fame and you have to adjust the flame gas flow rates to enable the production of highest concentration of free atoms is produced. You might also have to adjust the burner height so that the radiation beam passes through the zone that has the highest atom could density and thus making up the highest sensitivity.

Electrothermal Atomizers

Atomic Absorption Spectroscopy that uses graphite tube atomizers was first introduced by Boris Lívov in Russia around the late 1950s. Later it was further enhanced by Hans Massmann in Dortmund, Germany. A large variety of graphite tubes has been designed and created over the years. However, the most commonly used dimensions today are 20-25mm in length and 5-6mm in diameter. Direct analysis of liquid, dissolved, solid and gaseous samples are possible with this technique. A known volume of sample is sent into the graphite tube and this is then subjected to a temperature program.

Atomic Absorption Spectroscopy is today widely used for applications in mining and exploration fields. It is also used for processing of materials in these industries. To know more about the details of this process, the instruments used and the benefits it offers, you can take a look at websites like www.aurorabiomed.com.

Aurora Biomed has atomic absorption spectrometers for Atomic Absorption Spectroscopy. Contact : http://www.aurorabiomed.com/atomic-absorption-spectroscopy.htm

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