Mass spectrometry

An analytical technique that measures the mass of, and identifies, a chemical or biological substance. Its principle rests on the separation, in a gaseous state, of charged molecules (ions) according to their mass-to-charge ratio. A mass spectrometer is composed of: - an ion source: the molecules are vaporized and ionized using different methods, such as Matrix-assisted laser desorption/ionization (MALDI). - the mass analyzer: classes the ions according to their mass, using various physical methods. - the detector: the ions are converted to electrical signals that can be recorded and analysed.