scale) images of small areas in transmission electron microscopy. Ultra high vacuum and the use of reflection imaging and through-surface imaging have served to meet some of these requirements. Surfaces in separations science Leading off t h e final session on Wednesday morning was Sarah Rutan of Virginia Commonwealth University, who spoke about the use of UV-vis and fluorescence solvatochromic methods for characterizing TLC and HPLC stationary phases. Multiple internal-reflection spectroscopy is being used to sample only the near-surface region of approximately 100-200 /um. Harold McNair presented the next paper on surface effects of capillary GC performance. Use of silanol-deactivating reagents such as chlorosilanes, disilazanes, cyclic siloxanes, and pyrolyzed polyethylene glycols produces capillary columns that can be used to determine trace levels of amines. He illustrated the use of classical surface energy/tension methods (i.e., the Zisman contact angle approach) to determine the surface characteristics of stationary-phase materials. William Cooper of Florida State University then discussed the use of inverse, heterogeneous gas-solid chromatography for characterizing LCbonded phases. Adsorbate-adsorbent interaction energies are calculated from the pressure dependence of retention volumes. A surface polarity scale and a surface selectivity triangle have been developed that are analogous to the Rohrschneider scale and the Snyder solvent selectivity scheme, respectively. "Derivatization and Characterization of Chromatographic Surfaces" was the topic of the next presentation, by John Dorsey. By using ultrasound to derivatize silica surfaces, higher chainpacking densities have been achieved. Dill's theoretical predictions for reversed-phase retention show good agreement with the results obtained at these chromatographic surfaces. The final paper was given by Roger Gilpin of Kent State University on the use of NMR techniques to characterize bonded phases and retention mechanisms. Results from wide-line deuterium NMR provide information on the chemical and structural nature of these surfaces, uniformity of surface coverage, modes of motion for the immobilized stationary-phase molecules, and retention mechanisms. The organizing committee should be congratulated for preparing a strong technical program and a pleasant environment in which to learn. The infor-
mal and formal social portions were also well done, and symposium participants had an opportunity to enjoy the sights and scenery of the Blue Ridge region. Both the technical program and the local arrangements were excellent. The excitement and enthusiasm evident at Virginia Tech will surely be part of next summer's symposium at Oak Ridge National Laboratories, and we look forward to seeing you in Tennessee next July.
Fred M. Hawkridge is professor of chemistry at Virginia Commonwealth University in Richmond, VA. Joseph A. Gardella, Jr., is associate professor of chemistry and codirector of the Industry University Center for Biosurfaces at the State University of New York at Buffalo. Both are currently visiting scientists in the analytical and surface chemistry program of the chemistry division at the National Science Foundation.
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ANALYTICAL CHEMISTRY, VOL. 6 1 , NO. 23, DECEMBER 1, 1989 • 1335 A
