ABSTRACT
Tandem mass spectrometry (MS/MS) is a set of methodologies in which there is serial linkage of two MS separations. These separation steps can be performed either by linking two mass spectrometers in series or by performing two or more separation steps sequentially over time within a single instrument. There is an increasing diversity of mass spectrometers and options for introducing specimens into mass spectrometers that permit a wide range of applications from therapeutic drug monitoring, toxicology, endocrine testing, proteomics, and metabolomics as described in reviews [1-14]. Gas chromatography (GC) for many years has been linked to MS, with many applications of GC-MS/MS. The reader is referred to other publications for examples of GC-MS/MS applications [15,16]. Capillary electrophoresis (CE) also has been used as a separation technique linked to MS/MS [17]. The major focus of the present report, though, will be on liquid chromatography (LC) linked to MS/MS, as this has been the technique with most rapid growth in MS/MS applications [1-14]. There is a complex range of options for the latter technique based on different chromatographic methods, interfaces with mass spectrometers, types of mass spectrometers, and methods for molecular fragmentation. Another recent development has been growth in techniques for direct MS/MS analysis of specimens without any chromatographic separation [18-23]. These techniques, which show promise for applications such as forensic analysis and environment sampling, will also be discussed briefly in this chapter.
