Little is known of the release of trace elements in vivo from dental implant materials. Conflicting data have been reported in the literature as to the levels of trace elements released and their potential consequences, mainly because of sampling and analytical methodological errors. In this study methods for average concentration levels of Al, Cr, Co, Mo, Ni, Ti, and V in organs were developed using rabbit tissue from an in vivo implantation study. At least 50% of the brain, liver, lung, kidney, and spleen were taken minimizing contamination. The tissue was homogenized by cryogenic milling at LN2 temperature and then freeze-dried. Samples were digested in nitric acid and hydrogen peroxide using microwave energy. Standard reference materials were utilized for quality control. One liver sample was analyzed 10 times to assess the method precision. Absorbance values in blanks, standards, and test samples were measured using a Varian GTA 95 graphite furnace and 875 spectrophotometer. Very satisfactory method precision and quality control were recorded. Low or very low levels of the trace elements were found in the various organs.

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generally be expected to at least reduce, if not eliminate, interference from "fluorescence background" by the proper choice of modulation conditions. Selective modulation should be particularly useful for the identification and quantitation of the minor component in a mixture of two fluorophores. This capability might be useful, for example, in studying unresolved peaks in the chromatography of fluorescent compounds. For very complex mixtures, the combination of a chromatographic separation followed by selective modulation fluorescence spectrophotometry might be especially useful. In fact, since the selective modulation system works in real time, a fluorescence detector for LC and GC could utilize the selective modulation principle. Another area of application might be in energy-transfer studies. It is possible that the energy transferred from a radiationally-excited doner may be able to be modulated by wavelength modulation of the excitation monochromator.On this basis, it may be possible to distinguish an energy transfer process from direct radiational excitation of the acceptor.Of course, there are limitations. First, it must be realized that selective modulation does not in any way reduce the total intensity of the nulled luminescence at the photode-

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This paper describes a selection of the major developments in the field of analytical methodology for elemental speciation over the period from January 1986 to December 1990. Methods for a number of elements will be highlighted. Judging by the number and diversity of published reports, there has been increasing interest and activity in the development of new and modified analytical methods. Further, it is very encouraging to observe the number of papers concerned with the accuracy and precision of such analytical methods, and with comparisons between two or more methods. Among electrochemical methods of analysis, anodic stripping voltammetry has provided an important basis for measurements of concentrations of labile metals in aqueous media. The fastest growing area of method development is the coupling of separation methods, usually chromatography, with a single- or multi-element detector. Most importantly, inductively coupled plasma mass spectrometry has recently been described as a very sensitive, multi-element detector. The success of a 'coupled' method is greatly dependent on a suitable interface. Several papers have been published recently describing useful interfaces. Chemical extraction procedures continue to occupy an important place. Applications of analytical elemental speciation methods have included environmental, biological, clinical and geological samples. A number of methods for elements most frequently studied will be discussed.