Glow Discharge Mass Spectrometry : Trace Element Determinations in Solid Samples

Glow discharge mass spectrometry (GDMS) is a mature, versatile technique for the direct determination of trace elements in a variety of materials. The technique is an extension of the earliest forms of mass spectrometry. Processes inherent to the glow discharge, namely cathodic sputtering coupled with Penning ionization, yield an ion population from which semi-quantitative results can be directly obtained. QuantiÐcation in GDMS is achieved both through standard elemental mass spectrometric procedures and more innovative approaches. The analytical performance of GDMS compares favorably with competing elemental mass spectrometric methods and newer experiments use this ionization method for both molecular and elemental analysis. As with any analytical technique, the future of GDMS lies in improvements with respect to instrumental implementation and extension to new areas of application. If the method is to remain competitive, commercial GDMS systems must incorporate advances in mass spectrometric technology to increase analytical performance while decreasing the size, complexity and cost of the technique. Continued e†orts to develop improved quantitation procedures are needed to provide greater accuracy. The method should continue to mature as sustained e†orts demonstrate its utility in the solution of new and more varied problems.