TABLE OF CONTENTS Mass spectrometers are used for a wide variety of studies, from investigations of gas-phase ion chemistry to the authentication of works of art. Mass spectrometers may be used to measure the ages of rocks or skeletons, identify illicit drugs taken by athletes or given to racehorses, probe the chemical topography of new materials, quantify trace elements in semiconductors, measure the masses of proteins, or look for signs of life on other planets. Such a diverse set of applications requires several different types of mass spectrometer and new designs are being developed all the time. Some mass spectrometers easily fit in the boot of a car, others fill an entire room. Therefore, the discussion presented here must be restricted. The types most usually encountered in chemical and biochemical applications will be featured. Instruments for measuring mass spectra are extensively described in the literature and references to such information are included where appropriate. Manufacturers of mass spectrometers frequently publish news releases which provide much detail of specific instruments and can keep the mass spectrometrist abreast of commercial developments.
Whilst diverse designs do exist, the essential features of a mass spectrometer are common and are presented in block form in figure 2.1. Each of these features is clearly seen in the photograph (figure 2.2) of a modern mass spectrometer capable of high resolving powers and used mainly for organic compounds. A brief discussion of each feature in turn is necessary for a proper understanding of how a mass spectrum is produced.
