Mass spectrometry is perhaps the ultimate analytical tool – it involves counting the individual ions, and thus it is the most sensitive detection system possible. After an introduction to the basic components of a mass spectrometer (ion source, separation device for charged ions, and ion detector), we review the various types of spectrometer (single focusing, double focusing, quadrupole). We then introduce the systematics relevant to the study of light isotopes (hydrogen, carbon, nitrogen), and outline the role that these isotopes now play in environmental research. Our attention then turns to the quite different systematics relevant to heavy isotope research (lead and strontium). Highlighted applications of isotope archaeology include palaeodietary research from light stable isotopes on human bones and teeth, “provenancing” humans from light stable isotopes and also heavy isotopes in bone and teeth, and the use of lead isotopes to track the circulation of metal artifacts. There are several excellent texts of isotopes in geochemistry and the environmental sciences, including Faure (1986) and Hoefs (1997).

Separation of ions by electric and magnetic fields

Mass spectrometry in chemistry is widely used as a tool for organic structural analysis, where precise measurement of the mass of the sample and of its fragmentation products is of prime importance. In many ways, however, mass spectrometry is also the ultimate tool as a detector for a wide range of techniques of inorganic chemical analysis, since it allows the counting of individual ions, giving what should be the best possible analytical sensitivity.