Emergence and impact of alternative sources and mass analyzers in plasma source mass spectrometry

Abstract

Inductively coupled plasma mass spectrometry (ICPMS) has become an invaluable tool for the measurement of elemental concentrations in samples of all kinds. However, the ICP was by far not the first source employed for elemental mass spectrometry, and arguments can be made that it is not the best, especially in specific situations. Chemical flames, arcs, sparks, microwave plasmas, glow discharges, electrospray sources, thermal-ionization sources, and novel atmospheric-pressure plasmas have all been explored and many, such as the thermal-ionization source, occupy a niche in the analytical arsenal that is unlikely to be occupied by an ICP of the present form. Similarly, quadrupole mass filters and sector-field spectrometers that are now the most commonly used are not the only ones that have been coupled with plasma sources for elemental determinations. Others, such as Fourier-transform mass spectrometers, ion traps, time-of-flight mass spectrometers, and multi-channel detector systems have all been joined with ICPs and other sources to yield improved capabilities in targeted applications. In this manuscript, these alternative sources and mass analyzers will be examined; greatest emphasis will be placed on mass analyzers, for brevity. This historical walk through instrumental developments will be a somewhat subjective one, taken from the author's viewpoint and including a number of personal experiences and those involving his research group. It will be shown that exciting opportunities exist for even greater capabilities from future instrumentation for plasma source mass spectrometry.