In the measurement of heavy metals by the atomic absorption method, the sample is transferred to a flame or a furnace (in this method, the use of a furnace increases the accuracy of the measurement compared to the use of a flame) and there it turns into a set of atoms. After passing through the monochromator, the light beam hits the detector and the amount of light absorbed by the element converted into atoms in the flame is measured. In some metals, atomic absorption is more sensitive than emission. Because each metal has its own absorption wavelength and the source or lamp is made of the same metal. This fact frees the method from spectral or radiation disturbances. In a limited concentration range, the amount of energy absorbed in the flame at a specific wavelength is proportional to the concentration of the element in the sample. Most atomic absorption devices are also equipped with emission mode, which creates a better linear range for some elements.