GAS-CHROMATOGRAPHIC STUDY OF SOLVATION ENTHALPY BY SOLVATOCHROMICALLY BASED LINEAR SOLVATION ENERGY RELATIONSHIPS

Solute retention in capillary GC columns can be correlated with a linear solvation energy relationship (LSER) equation using chromatographically determined solute parameters (log L(16), pi(2)*,(C), alpha(2)(C) and beta(2)(C)). The LSER coefficients obtained form correlation studies serve to quantitatively characterize the stationary phase. The effect of column temperature on retention was characterized by the temperature dependence of the LSER coefficients. Enthalpy and entropy of the retention process were also fitted quite well to the LSER equation. The main contributions to retention are from the solute-solvent interactions that give large favorable entropies and small unfavorable entropies. The LSER coefficients for the free energy and enthalpy regressions are linearly correlated.