- a device for identifying the kinds of particles present in a given substance: the particles are ionized and beamed through an electromagnetic field and the manner in which they are deflected is indicative of their mass and, thus, their identity.
- an analytical instrument in which ions, produced from a sample, are separated by electric or magnetic fields according to their ratios of charge to mass. A record is produced (mass spectrum) of the types of ion present and their relative amounts
