Influences of the mobile phase composition and temperature on the retention behavior of aromatic alcohol homologues in hydrophobic interaction chromatography

Abstract

To eliminate the very complicated effects of chromatographic thermodynamics in hydrophobic interaction chromatography (HIC) with biopolymers as solutes, homologues of neutral aromatic alcohols were selected as solutes for investigating their thermodynamic behavior in HIC. The effects of the mobile phase composition and temperature (0∼80°C) on the retention behavior of the homologues were studied extensively. The retention behavior of the homologue was characterized by the linear parameters in the stoichiometric displacement model for retention (SDM-R). The retention of small molecules is essentially controlled by non-specific interaction in HIC as well as reversed phase liquid chromatography (RPLC), and the parameters obtained were found to follow the homologue rule. Plots of the logarithm of retention of solutes in four kinds of salt solution versus the reciprocal of the absolute temperature over a wide range were nonlinear, indicating a large heat capacity change associated with retention. The thermodynamic parameters demonstrate the retention of small molecules in HIC to be entropy-driven at low temperature and enthalpy-driven at high temperature.