Atomic Absorption Spectroscopy uses optical radiation and the absorption characteristics of particular elements in order to quantify the concentration of an analyte in a sample. When atoms are exposed to energy, their electrons are excited to higher orbitals. In the case of atomic absorption this energy is in the form of optical light. Particular electron transitions in particular elements are excited by unique wavelengths, thus providing specificity among multiple analytes. The amount of energy absorbed by an analyte at a specific wavelength corresponds to the concentration of the element known to be excited by that wavelength. A sample is first atomized. This is traditionally done using flame or electrothermal atomizers. The atomized sample then is exposed to the optical light at the predetermined wavelength specific to the analyte of interest. The absorption is measured at each wavelength of interest. Using the Beer-Lambert Law, the amount of energy absorbed correlates directly with the concentration of the specific analyte. This procedure is common for analyzing metals in biological fluids, observing quantities of a catalyst remaining in a drug product, or analyzing the metal content of water.