ATOMIC SPECTROMETRY UPDATE - ATOMIC-EMISSION SPECTROMETRY

This Atomic Spectrometry Update is the latest in an annual series appe aring under the title 'Atomic Emission Spectrometry'. The review descr ibes developments in all aspects of atomic emission spectrometry, incl uding fundamental processes and instrumentation. The renaissance of at omic emission spectrometry, brought about by the commercial introducti on of the ICP about a quarter of a century ago, continues to flower. T he major stimulus to research in recent years has undoubtedly come fro m another step change in technology, this time in the form of array de tectors. There can be few areas of atomic emission spectrometry which have not been influenced by improvements in detector technology, as ev idenced by the wide range of applications described in this year's Upd ate. The ability to achieve simultaneous multi-element analysis across the full wavelength range is perhaps the most obvious advantage of th ese new detectors. However, the opportunities to interrogate multivari ate data in a way not previously possible has spawned an entire resear ch field devoted to the application of chemometrics. Examples of the u se of principal component analysis, multiple least squares, multilinea r regression, wavelets and neural networks have been published. The fa ct that measurements can be now made both rapidly and simultaneously h as allowed the exploitation of transient signal measurement from sourc es, such as the single spark or laser ablation. The specific exploitat ion of this feature in terms of time-resolved analysis has been much i n evidence. The use of CCD camera systems for spatial imaging of spect ral sources has also been the subject of attention. In terms of source design, two areas stand out as being particularly active. The glow di scharge is clearly the source of the moment, and developments in funda mental understanding are progressing in tandem with the design of new instrumentation. Supplementary excitation using rf, microwave, magneti c fields and pulsing of the basic de discharge has remained a major fi eld of research activity. This offers a great deal of scope for plasma diagnostic approaches, and the use of modelling and mathematical simu lation has also been a recurrent theme in glow discharge research. The use of the laser as a primary emission source is undoubtedly on the i ncrease, in part due to the development of rapid data acquisition sign als to discriminate against non-specific background in the time domain . The compact nature and reliability of modern lasers also makes them attractive as portable analysers, particularly if the possibility of o peration at atmospheric pressure in air is realised. The possibilities for practical depth profiling by LA-AES has moved closer with the rec ognition of the role of beam optics on ablation control.