Atomic mass spectrometry

The format of this year's Update follows that used in last year's(1) with some minor changes in the section headings. Although an attempt is made to consider all relevant refereed papers, conference abstracts, reports, book chapters and patents for inclusion, this review does not aim at being comprehensive in its coverage. The selection of papers is based on criteria applied to focus sharply on the most significant developments reported during the period (approximately corresponding to 1998) covered by this Update. The prime consideration is that the reports should present advances in instrumentation and methodology or improved understanding of the fundamental phenomena involved in the MS process. As a general rule, conference abstracts are not included because they rarely provide sufficient information to judge whether or not they meet the criteria. We consider it better to wait for full details to appear in a refereed journal. A similar policy applies to those papers in a language other than English and unlikely to reach a wide readership. Routine applications of atomic MS are not covered in this Update and readers are referred to the Updates on Industrial analysis: metals, chemicals and advanced materials,(2) Environmental analysis(3) and Clinical and biological materials, food and beverages.(4) A book that can be thoroughly recommended is that edited by Gill(5) on Modern Analytical Geochemistry. Chapters on most of the techniques included in this Update gave full yet concise descriptions of the underlying principles of the techniques, with examples of applications in geochemistry and environmental science. The substantial review (269 references) of Becker and Dietze(6) covered in detail the inorganic MS techniques that are used for inorganic trace analysis. This Update follows the policy set by JAAS in deciding the scope of papers which can be considered for inclusion. With the increased use of atomic spectroscopy techniques, in particular MS, in speciation studies the scope has been widened to include not only elemental but also speciation studies, including those in which molecular species are determined as long as the focus of the study is the element and its chemical form. With the boundaries between atomic and molecular MS becoming less well defined, the judgement of the authors of this Update becomes important in achieving a correct balance. In general, studies of unstable nuclei are excluded but the determination of radioactive elements in 'real' samples are included. The trends apparent for the various MS techniques are highlighted in the appropriate sections. In general, more attention continues to be paid to sample preparation and introduction rather than instrumentation. A common feature for many of the techniques reviewed is the need for analysis of smaller samples. This has presented challenges of reducing the levels of contamination and background noise and also calibration and standardization. The use of ICP-MS for the measurement of isotope ratios is noted as an increasingly important application.