Mass spectrometry (MS) is an analytical technique that ionizes chemical species and sorts the ions based on their mass to charge ratio.
In simpler terms, a mass spectrum measures the masses within a sample.
Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures.
These spectra are used to determine the elemental or isotopic signature of a sample, the masses of particles and of molecules, and to elucidate the chemical structures of molecules, such as peptides and other chemical compounds.
In a typical MS procedure, a sample, which may be solid, liquid, or gas, is ionized, for example by bombarding it with electrons.
This may cause some of the sample's molecules to break into charged fragments.
These ions are then separated according to their mass-to-charge ratio, typically by accelerating them and subjecting them to an electric or magnetic field: ions of the same mass-to-charge ratio will undergo the same amount of deflection.
The ions are detected by a mechanism capable of detecting charged particles, such as an electron multiplier.