ABSTRACT
Atomic absorption spectrometry (AAS) is the most widely used method for metal and trace metal analysis. Atomic absorption is a special technique of ultraviolet-visible (UV-VIS) spectrometry covering the wavelength range from 190 to 860 nm based on the excitation of free atoms in the ground state by photons. Atomic absorption corresponds to electron transitions from low to higher energy states of free atoms in an excitation process by energy carried by photons. To avoid the use of very expensive high-resolution monochromators Walsh suggested the use of atomic spectral line source of the element measured as light source combined with a medium resolution monochromator with spectral band width of 0.2 to 1 nm. The other way for the measurement of the narrow line absorption of free atoms is with the use of intense UV-VIS continuum light source and a very high resolution monochromator with a band width 0.001 nm.
