This project is in the general area of analytical and surface chemistry and in the subfield of separations science. During the tenure of this three-year continuing grant, Professor Guiochon and his students will investigate the influence of the thermodynamics and kinetics of phase equilibria on chromatographic separations performed at high concentrations. This research, which builds upon results obtained under NSF grant CHE-8901382, addresses the theoretical basis for liquid chromatography at high concentrations and the experimental verification of that theoretical basis. This work includes studies of nonlinear, nonideal systems that are common to both preparative scale and analytical chromatography. %%% This research is of both theoretical and practical significance and has as a goal the development of preparative scale separations that are of critical importance in biotechnology.