Atomic Spectrometry Update—Atomic Emission Spectrometry

Abstract

This Atomic Spectrometry Update is the latest in an annual series appearing under the title ‘Atomic Emission Spectrometry’. The review describes developments in all aspects of atomic emission spectrometry, including fundamental processes and instrumentation, reported in the Atomic Spectrometry Updates references published in JAASin Volumes 10 and 11 (95/183–96/c947). The full references and names and addresses of authors can readily be found in the relevant issues of JAAS. However, as an additional service to readers, an abbreviated form of each references quoted (expect those of Conference Proceedings)is given at the end of the review.

Descriptions of novel de arc sources for AES continue to appear in the literature. These are either the subject of fundamental spectroscopic or diagnostic study, or have been designed to contribute in a particular application. Very few reports of spark AES have been received and it must now be doubtful as to whether the technique will remain of interest in the research domain. The most active area of research in AES concerns the development of glow discharge sources. In addition to further characterization of dc GD sources, much of the work reported has focused on the use of radiofrequency powered devices which can be more readily used by application to the analysis of insulators. The use of microwave- and magnetically-enhanced and pulsed GD sources continues to attract attention, and effort has also been devoted to modelling sputtering processes. A significant increase has been noted in the use of hollow cathode and glow discharge sources for the analysis of liquids (with desolvation)and gases.

The development of solid state array detectors such as charge-injection devices (CIDs)and charge-coupled devices (CCDs) has now affected almost every field of AES, including arcs and sparks. The attraction of rapid multi-line analysis with simultaneous background correction capabilities is self-evident, and these capabilites have been used to good effect in laser ablation AES, where discrimination against a rapidly changing background signal is important. The CCD has also been utilized as an imaging detector in studies of furnace atomization plasma emission spectrometry systems. However, the major application of these detectors continues to be in ICP-AES, and there has been a growth in the use of multivariate statistics and chimometrics associated with the production of this type a data set. As a result of the introduction of commercial equipment there has been much work emphasizing the benefits of echelle spectrometers with solid state detectors, and of the advantages and disadvantages of axial viewing of ICPs. The fundamental study of excitation in the ECP remains a subject of considerable controversy and both LTE and non-LTE behaviour continues to be reported. As in most years, the development of sample introduction systems for ICP-AES remains a mainstream topic of research. The greatest over-all impact has been made by the use of ultrasonic nebulizers and desolvation systems. The utilization of HPLC and hydride generation techniques in ICP-AES speciation studies has continued.

Applications of GC–MIP-AES systems to organometallic speciation continue to be reported in significant numbers. Fundamental studies of new, higher power, MIP sources have been reported, but on the whole, research has been restricted to elements which are relatively insensitive in ICP-AES (e.g., halogens). Further work has been carried out on direct nebulization into the MIP, using desolvation to remove solvent vapour. The demise of the DCP as an AES source has continued, and only a few applications papers were received in the year under review.