Mass spectrometry involves the ionization of a sample to produce either positive or negative ions. These are accelerated in a vacuum system and the mass of the intact molecule determined. In addition the masses of fragments produced during the ionisation processes can be determined to give structural information. Accurate mass measurement of the molecular ions can lead to the determination of elemental composition. A study of the fragmentation patterns can lead to the identification of unknown reaction products through computer library matching. “Soft” ionization techniques such as Chemical Ionization, (CI), Liquid Secondary Ion Mass Spectrometry (LSIMS, - often called FAB), Matrix-assisted Laser Desorption / Ionization (MALDI), Electrospray Ionization (ESI) and Atmospheric Pressure Chemical Ionization (APCI) can be used to reduce fragmentation and enhance the abundance of the intact molecular ion.
Coupling of chromatography (gas or liquid) to mass spectrometry allows separation and analysis of mixtures. These techniques of GC/MS and LC/MS assist in the identification of organic compounds from a wide variety of sources: synthetic, natural or biomedical.