Kinetic study on solute permeation at the interface of molecular aggregates by partial filling capillary electrophoresis.

Abstract

Moment analysis method using partial filling CE was developed for the kinetic study on solute permeation at the interface of spherical molecular aggregates. Moment equations for partial filling CE were developed by classifying CE systems into five categories according to the migration velocities of solute and molecular aggregate. The method was applied to the study on the dissolution of electrically neutral solutes into SDS micelles. Elution peaks were measured by partial filling CE while changing the concentration of SDS and the filling ratio of SDS micellar zone to the capillary (ϕM ). Partition equilibrium constants (Kp ) and rate constants of interfacial solute permeation of SDS micelles (kin and kout ) were determined from the first absolute and second central moments of the elution peaks by using the moment equations. Their values were comparable irrespective of ϕM and were almost the same as those previously measured by complete filling CE. The positive correlation of Kp with the hydrophobicity of the solutes was explained in terms of the change in kin and kout . It was demonstrated that the moment analysis method using partial filling CE is effective for studying solute permeation kinetics at the interface of spherical molecular aggregates.