TANDEM MASS-SPECTROMETRY - A PRIMER

Tandem mass spectrometry (MS/MS) employs two stages of mass analysis i n order to examine selectively the fragmentation of particular ions in a mixture of ions. The various types of instruments which can be used to perform this experiment are described, including those based on se paration of the mass-analysis events in time and those based on measur ements in physically separate analysers. The several MS/MS scan types- product scans, precursor scans and neutral loss scans-are presented an d examples of their applications are provided. These include the chara cterization of individual compounds and the recognition of groups of c ompounds with specified functional groups. Applications are shown to t he determination of compounds present in complex mixtures. The improve ment in signal-to-noise ratio achieved by MS/MS when compounds are ion ized by methods which produce high chemical noise is illustrated for c holine derivatives. Fundamental aspects of collisional activation in t he low and high collision energy range are reviewed.