The performance of the new analytical atomic techniques of Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is assessed. A detailed examination of ICP-MS instrumentation was carried out to derive data on performance criteria such as precision, resolution, dynamic range and limits of detection. For most elements, sub ng.mL-1 limits of detection can be achieved together with a linear dynamic range of 4-5 orders of magnitude. Spectral simplicity is one of the attractions of ICP-MS; however, the technique is prone to spectral interference from polyatomic, analyte oxide and doubly charged ions. The significance of these species was studied together with methods for reducing their levels, in particular with use of a cooled spray chamber. Plasma operating parameters were found to effect system performance so a detailed examination of the effects of varying plasma operating parameters was carried out and showed that for ICP-MS systems used in this study, optimisation for maximum elemental signal response resulted in near minimal levels of interference species. Having assessed the optimum operating conditions and potential drawbacks of the technique, the final part of the study was devoted to elemental and isotope ratio determinations using conventional and 'novel' sample introduction methods. The study demonstrates that, apart from the interference problems identified, the technique of ICP-MS is a very useful addition to the field of analytical atomic spectrometry.