Atomic Absorption Spectroscopy is an instrumental analytical technique for measuring the elements (metals and metalloids) in samples through the application of characteristic wavelengths of electromagnetic radiation from a element specific light source. . Individual elements will absorb wavelengths differently. In effect, AAS takes advantage of the different radiation wavelengths that are absorbed by different atoms. It is based on element specific wavelength light absorption induced by exciting ground state atoms so that their characteristic wavelengths are emitted. During excitation, electrons move up one energy level in their respective atoms when those atoms absorb a specific energy. As electrons return to their original energy state, they emit energy in the form of light. These very specific wavelengths give the technique excellent specificity and detection limits. Absorption for each element is specific, no other elements absorb this wavelength.
Flame Atomic Absorption Spectroscopy (FAAS)
FAAS relies on atomizing a sample solution in a flame. A beam of light from an element specific light source passes through the flame and into a monochoromator which collminates the light onto the detector to a specific wavelength for maximum absorption of the element. The amount of light absorbed by the flame is inversely proportional to the amount of that element in the sample. Typical detection limits for flame atomic absorption is 10 to 100 ppb.
Graphite Furnace Atomic Absorbance Spectroscopy (GFAAS)
GFAAS is similar to but it differs in that it uses a graphite furnace to atomize the sample, instead of a flame. This technique offers the advantage of greater atomization of the sample, which affords both a lower detection limit and the use of less sample. Typical detection limits for graphite furnace atomic absorption are from 0.05 to 1.0 ppb.