According to the American Society for Mass Spectrometry (ASMS), a mass spectrometer “is an instrument that measures the masses of individual molecules that have been converted to ions; i.e., molecules that have been electrically charged.” The ASMS describes the mass spectrometer as helping scientists identify molecules present in solids, liquids, and gases; determine the quantity of each type of molecule; and determine which atoms compose a molecule and how they are arranged.