This project is in the general area of analytical and surface chemistry and in the subfield of separation science. During the tenure of this three-year continuing grant, Professor Olesik and her students will pursue fundamental investigations of the physicochemical properties of conventional liquid chromatography mobile phases that have been mixed with supercritical fluids, particularly supercritical carbon dioxide, to provide new mobile phases with enhanced fluidities and diffusivities. These new mobile phases will enable more rapid analysis by high performance liquid chromatography (HPLC) and size exclusion chromatography (SEC). %%% This research builds upon preliminary results and new theoretical developments from Dr. Olesik's laboratory. In addition to contributing to the fundamental basis of liquid chromatography, these studies are relevant to other technologically important areas such as solvent extraction and synthesis where enhanced fluidity reaction environments can give rise to more efficient chemical processes.