Kinetic Study of the Intermolecular Interaction between 2-Phenoxypropionic Acid and β-Bromo-cyclodextrin Affixed on the Stationary Phase by Liquid Chromatography

Abstract

The intermolecular interaction between 2-phenoxypropionic acid and β-bromo-cyclodextrin affixed on the stationary phase surface in a chiral HPLC system was studied by the moment analysis method. At first, pulse response and peak parking experiments were conducted to measure some parameters concerning the column geometry, adsorption equilibrium, and mass-transfer kinetics. Then, the first absolute moment (μ1) and second central moment (μ2′) of the elution peaks were analyzed by the moment equations, which were developed by assuming that the reaction kinetics between the solute molecules and the functional ligands can be represented by the Langmuir-type rate equation. Finally, the flow-rate dependence of HETP calculated from μ1 and μ2′ was analyzed by using the values of the parameters to determine the association and dissociation rate constants of the intermolecular interaction. It was demonstrated that the combination of the chromatographic experiments and moment analysis is one of the effective strategies for the kinetic study of intermolecular interactions.

Kinetic Study of Chiral Intermolecular Interactions by Moment Analysis Based on Affinity Capillary Electrophoresis

“…The variables determined during the analysis of μ 2 ′ are listed in Table . Previously, the rate constants of intermolecular interaction between PPA and β-bromo-cyclodextrin affixed on stationary phase of HPLC were reported . For ( R )-PPA, those values were k a = 2.1 × 10 3 mol dm –3 s –1 and k d = 22 s –1 , and for ( S )-PPA, they were 2.6 × 10 3 mol dm –3 s –1 and 24 s –1 .…”

“…Previously, the rate constants of intermolecular interaction between PPA and β-bromo-cyclodextrin affixed on stationary phase of HPLC were reported. 58 For (R)-PPA, those values were k a = 2.1 × 10 3 mol dm −3 s −1 and k d = 22 s −1 , and for (S)-PPA, they were 2.6 × 10 3 mol dm −3 s −1 and 24 s −1 . The values of k a were similar, but k d was larger for capillary electrophoresis, which could be caused by immobilization of βbromo-cyclodextrin.…”

Moment Analysis Theory for Size Exclusion Capillary Electrochromatography with Chemical Reaction of Intermolecular Interaction

“…8 In practice, the reaction rate constants (ka and kd) were determined for the intermolecular interaction between 2-phenoxypropionic acid and β-bromo-cyclodextrin by chromatographic experiments with the MA theory. 9 On the other hand, regarding separation technique, capillary electrochromatography (CEC) has some intrinsic characteristics. Separation behavior of CEC is correlated with both the chromatographic behavior of liquid chromatography (LC) and electrophoretic behavior of capillary electrophoresis (CE) because CEC is based on the two separation techniques.…”