PLASMA SOURCE-MASS SPECTROMETRY

Over the past decade, plasma-source mass spectrometry (PSMS) has become a viable alternative for multielemental analysis. The method offers (1) detection limits that are ordinarily two orders of magnitude below those offered by competitive emission techniques, (2) effective semiquantitative analysis, (3) isotope-analysis and isotope-ratio capability, (4) a broad linear dynamic range, and (5) virtually complete elemental coverage. However, even the most modern PSMS instruments remain plagued by a number of problems. High concentrations of sample material often pose difficulties, a number of spectral interferences (isobaric overlaps) can be devastating, instrumental drift is often troublesome, and new kinds of matrix interferences, not yet satisfactorily explained, are frequently encountered. In this paper, the current status of PSMS is first briefly reviewed, with an emphasis on current capabilities and shortcomings. A sampling of recent activities in the field is then documented. These activities understandably are aimed mostly at overcoming the remaining shortcomings of the method. Finally, recent instrumental developments are outlined. Included in these developments are modifications of conventional plasma ion sources, the introduction of new plasmas for PSMS, and the use of alternative mass spectrometers for elemental analysis.