The first paper describing the coupling of an argon plasma, a highly efficient ion source, and a mass spectrometer was published in 1980 (Houk et al.) as a result of the collaboration between the research group at the Ames Laboratory, Iowa State University (USA) and Gray at the University of Surrey (UK). Work was also under way by Douglas and colleagues at Sciex Inc., Toronto (Canada), and commercial instruments were introduced in 1983, by Sciex in Canada and by VG Isotopes in the UK. Gray and Date (British Geological Survey) carried out much of the early work on prototype units of the VG instrument. Reviews on the subject of inductively coupled plasma mass spectrometry, ICP-MS, have been written by Date and Gray (1983), Gray (1985a), Douglas and Houk (1985) and Houk (1986). The attractive features of ICP-MS are simpler spectra, wide linear dynamic range (104-105), flexibility, the ability to measure isotope ratios as well as elemental concentrations, and detection limits in solution in the range 0.01-0.1 ngml-1.