MOBILE PHASE EFFECTS IN REVERSED-PHASE CHROMATOGRAPHY .1. CONCOMITANT DEPENDENCE OF RETENTION ON COLUMN TEMPERATURE AND ELUENT COMPOSITION

Enthalpy-entropy compensation observed in reversed-phase chromatography affords an expression of the free energy change associated with the chromatographic process asd a function of both the eluent composition and temperature. It takes a simple form and reveals the existence of a non-compensating enthalpy residue in the absence of heat capacity effects when the free energy change is linear in slvent composition. Statistical analysis confirmed that the resulting three-parameter equation suffices to transform retention data for a solute obtained at a given temperature and solvent composition to another set of experimental conditions. With arylalkanes investigated so far, the parameters exhibit a linear relationship with the carbon number of the solutes. These findings suggest the possibility of constructing a hydrophobic indix system for characterization of biological substances on the basis of retention data. © 1979.