HYDROGEN-BONDING .17. THE CHARACTERIZATION OF 24 GAS-LIQUID-CHROMATOGRAPHIC STATIONARY PHASES STUDIED BY POOLE AND COWORKERS, INCLUDING MOLTEN-SALTS, AND EVALUATION OF SOLUTE STATIONARY PHASE INTERACTIONS

The general solvation equation log K = c + rR2 + s-pi(2)H + a-alpha(2)H + b-beta(2)H + l log L16 has been used to characterise 24 gas-liquid chromatographic stationary phases for which Poole and co-workers have determined log K values for a series of solutes at 121.4-degrees-C. The explanatory variables are R2, a solute excess molar refraction, pi(2)H, the solute dipolarity, alpha(2)H and beta(2)H, the solute hydrogen-bond acidity and basicity, and log L16, where L16 is the solute gas-liquid partition coefficient on hexadecane at 25-degrees-C. It is shown that the b-beta(2)H term is not significant for any phase, and that the molten salts are all strongly dipolar and basic, with large s and a constants. A term-by-term analysis of the solvation equation yields a quantitative measure of the contribution to log K of various solute-stationary phase interactions, and leads to an understanding of how these interactions affect solute retention. The use of the characteristic constants c, r, s, a, b and l in the selection of stationary phases for particular separations is described.