INFLUENCE OF FLUORINE SUBSTITUTION ON THE SOLVATION PROPERTIES OF TETRAALKYLAMMONIUM ALKANESULFONATE PHASES IN GAS-CHROMATOGRAPHY

A series of tetraalkylammonium alkanesulfonate and perfluoroalkanesulfonate liquid organic salts are studied as model solvents to characterize quantitatively the influence of fluorine substitution on retention in gas-liquid chromatography. Interpretation of solvation interactions is performed using two new thermodynamic models suggested by Kollie and Poole and Abraham and co-workers. For the solvents studied any reduction in dispersive interactions accompanying the introduction of fluorine must be approximately offset by an increase in the cavity term. Of the polar interactions, orientation interactions are large but only weakly influenced by the introduction of fluorine; solvent hydrogen-bond base interactions are strong and significantly influenced by the inductive effect of fluorine on the electron density on the sulfonate group; solvent hydrogen-bond acid interactions are negligible for all salts.