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Editors' Column of 1 μL· in the form of 1000 identical aliquots. Hieftje also described a new variation on ion chromatography, which he called "replacement" ion chromatography. Cations are first sep arated as in conventional ion chroma tography. After passing through a sup pressor column, the effluent flows through a column containing lithium ions, where the sample ions are "re placed" by the lithium ions. These lithium ions can then be detected by flame photometry. A similar proce dure can also be applied to anions. Unlike conventional conductometiric detection, the method offers potential sensitivities in the sub-ppb range and a useful operating range up to 105. According to Stephen Weber of the University of Pittsburgh, photoelectroanalytical chemistry (PEAC) is so new a technique that reports of it have not yet appeared in the analytical lit erature. PEAC is based on electro chemical detection of light-generated species and combines the advantages of catalytic activity at an electrode surface with photosensitivity. The method has potential applications in techniques involving labeling, such as immunoassay and chromatographic detection. Weber and co-workers have achieved detection limits of 5 X 1 0 - 1 1 M in clean solutions and are currently determining the limit of de tection in human serum. Thanks to recent developments in laser and fiber-optic technology, in vivo analytical measurements are no longer an impossibility. M. J. Sepaniak of the University of Tennessee— Knoxville described the use of microscale fluoroprobes for the measure ment of drugs in a number of biologi cal matrices, including in vivo mea surements in laboratory mice. Other papers presented in the Advanced Spectroscopy session were devoted to topics such as multiwavelength meth ods, trace metal determinations by laser-enhanced ionization spectrome try, and element-selective inductively coupled plasma detection. This year's symposium was once again sponsored by Oak Ridge Nation al Laboratory (ORNL) and the Ameri can Association for Clinical Chemis try, with support from Instrumenta tion Laboratories, Eastman Kodak, and the Ames Division of Miles Labo ratories. According to chairman Carl Burtis of ORNL, symposium organiz ers are considering nearby Knoxville for the site of next year's meeting. As in past years, most of the papers presented at the symposium will be published in the September issue of Clinical Chemistry. Marcia S. Vogel
