An extremely high temperature source is used to excite the metal atoms in a digested sample so that the light emitted by the metal atoms can be used to determine how much is present. The source used in this technique is Inductively Coupled Plasma (ICP) and the light emitted is detected by means of Optical Emission Spectroscopy (OES).
In order to utilize this technique samples must be dissolved and introduced to the plasma where they are excited by the extremely high-temperature. The excited metal ions emit a characteristic emission line. ICP-OES has the ability to detect and quantify single or multiple elements simultaneously.