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atomic absorption spectrophotometry (AAS)
Principle:
- an atom dissociated from its chemical bonds absorbs light of specific wavelength in its ground state
- the wavelength of light absorbed is characteristic of the atom; the amount of light absorbed is a measure of the concentration of atoms in the light path
Methods:
Dissociation methods:
1) graphite furnace*
- atoms are dissociated from chemical bonding by placing a small sample of solution in a graphite tube, where the sample vaporizes in an inert atmosphere when an electric current passes through the tube.
2) flame
- a flame may also be used to dissociate atoms from their chemical bonds.
* method of choice
General
spectrophotometry
References
- Clinical Guide to Laboratory Tests, 3rd ed. Teitz ed.,
W.B. Saunders, 1995
- Clinical Diagnosis & Management by Laboratory Methods,
19th edition, J.B. Henry (ed), W.B. Saunders Co.,
Philadelphia, PA. 1996, pg 58