TAS-990 Atomic Absorption Spectrophotometer is a spectroanalytical apparatus for the quantitative determination of chemical elements using the absorption of optical radiation (light) by free atoms in the gaseous state. In analytical chemistry the technique is used for determining the concentration of a particular element (the analyte) in a sample to be analyzed. AAS can be used to determine over 70 different elements in solution, or directly in solid samples via electrothermal vaporization，and is used in pharmacology, biophysics and toxicology research.