Atomic absorption

Atomic Absorption is a technique used in analytical chemistry to determine the concentration of a specific element in a sample. It is based on the absorption of light by free metallic ions.

Principle

The principle of atomic absorption relies on the Beer-Lambert law, which states that the amount of light absorbed by a substance is directly proportional to its concentration. In atomic absorption, a sample is vaporized in a flame or graphite furnace, and the atoms absorb ultraviolet or visible light, causing electrons to move to higher energy levels. The amount of light absorbed is measured and used to determine the concentration of the element in the sample.

Techniques

There are two main techniques used in atomic absorption: flame atomic absorption spectroscopy (FAAS) and graphite furnace atomic absorption spectroscopy (GFAAS).

Flame Atomic Absorption Spectroscopy

In FAAS, the sample is nebulized and introduced into a flame, where it is desolvated, vaporized, and atomized. The atoms absorb light from a hollow cathode lamp, and the amount of light absorbed is measured.

Graphite Furnace Atomic Absorption Spectroscopy

In GFAAS, the sample is placed in a graphite tube, which is then heated to vaporize and atomize the sample. The atoms absorb light from a hollow cathode lamp, and the amount of light absorbed is measured.

Applications

Atomic absorption is used in a variety of fields, including environmental science, forensic science, pharmaceuticals, and geology. It is particularly useful for analyzing trace elements in samples.

See Also

• Spectroscopy
• Analytical Chemistry
• Atomic Spectroscopy