PHYSICOCHEMICAL MODEL OF RETENTION FOR CAPILLARY SUPERCRITICAL FLUID CHROMATOGRAPHY

the solvating ability of a supercritical fluid mobile phase depends on density and temperature, which in turn govern solute retention. A model is proposed for capillary supercritical fluid chromatography that relates the logarithm of the capacity factor to the logarithm of the reduced density by an empirical equation. This relationship takes into account molecular weight and shape of solute and mobile phase, reduced density, reduced temperature, free energy of solute transfer between phases and film thickness of the stationary phase. Ultimately, each mobile phase and stationary phase combination can be described by a "phase constant" that seems to be dictated by the relative polarizability of the phases. This model has so far been proven valid for a representative group of polyaromatics. © 1990.