Size-Based Characterization by the Coupling of Capillary Electrophoresis to Taylor Dispersion Analysis

In this work, a new methodology is presented for performing capillary electrophoresis (CE) coupled to Taylor dispersion analysis (TDA). The CE step allows the separation of the different compounds of the injected mixture, while the diffusion coefficient related to each sample zone can be derived from the subsequent TDA step. TDA is an absolute and straightforward nonseparative method allowing the determination of the diffusion coefficient (or hydrodynamic radius) from the peak dispersion obtained in an open tube under Poiseuille laminar flow conditions. With a mass concentration sensitive detector, the hydrodynamic radius derived from TDA is a weight average value calculated upon all the molecules present in the sample zone. Since CE can be hardly coupled to light scattering detection for technical reasons (low volumes, short detection path length), TDA represents an interesting alternative for the size characterization, without calibration, of sample mixtures using CE-based separation techniques. The coupling of CE to TDA can be implemented on a commercial CE apparatus.