Microchip Capillary Electrophoresis with an Integrated Indium Tin Oxide Electrode-Based Electrochemiluminescence Detector

Abstract

This paper describes an indium tin oxide (ITO) electrode-based Ru(bpy)₃²⁺ electrochemiluminecence (ECL) detector for a microchip capillary electrophoresis (CE). The microchip CE-ECL system described in this article consists of a poly(dimethylsiloxane) (PDMS) layer containing separation and injection channels and an electrode plate with an ITO electrode fabricated by a photolithographic method. The PDMS layer was reversibly bound to the ITO electrode plate, which greatly simplified the alignment of the separation channel with the working electrode and enhanced the photon-capturing efficiency. In our study, the high separation electric field had no significant influence on the ECL detector, and decouplers for isolating the separation electric field were not needed in the microchip CE-ECL system. The ITO electrodes employed in the experiments displayed good durability and stability in the analytical procedures. Proline was selected to perform the microchip device with a limit of detection of 1.2 μM (S/N = 3) and a linear range from 5 to 600 μM.