Moment Analysis Method Using Affinity Capillary Electrophoresis for Thermodynamic Study of Intermolecular Interactions

It was demonstrated that a moment analysis method using affinity capillary electrophoresis (ACE) is effective for thermodynamic study of intermolecular interactions. Thermodynamic characteristics of chemical reaction between phenylboronic acid (PBA) and fructose were studied as a concrete example. Elution peaks of PBA were measured by using ACE under different temperature conditions while changing the concentration of fructose in the mobile phase. The values of association equilibrium constant (KA), association (ka) and dissociation (kd) rate constants of the reaction were determined by analyzing those of the first absolute and second central moments of the elution peaks of PBA on the basis of the moment theory. The Krug’s method was used for the analysis of temperature dependence of KA, ka, and kd to determine the values of the enthalpy change (ΔH), Gibbs free energy change (ΔG), entropy change (ΔS), and activation energy (Ea) relating to the reaction between PBA and fructose. Some intrinsic characteristics of the reaction of PBA with fructose were considered by analyzing the values of the thermodynamic parameters, i.e., ΔH, ΔG, ΔS, and Ea. It was demonstrated that the moment analysis method using ACE is effective for the study of intermolecular interactions from thermodynamic points of view.