Mass spectrometry (MS) (Chemistry Dictionary)

Mass spectrometry (MS) : An analytical technique that measures the mass-to-charge ratio of ions in a chemical sample by bombarding the sample with electrons to the point of ionization and then separating the charged fragments by subjecting them to an electric or magnetic field, typically in order to determine the elemental or isotopic signatures of an unknown substance, the masses of its constituent particles, and/or the identities or structures of the molecules within it. The results are presented as a mass spectrum, a plot of the intensity of ion signals as a function of the mass-to-charge ratio.