Carbon film-based interdigitated array microelectrode used in capillary electrophoresis with electrochemical detection

A carbon film based interdigitated ring-shaped array (IDRA) microelectrode was applied to capillary electrophoresis with electrochemical detection to enhance the detection sensitivity on the basis of the redox cycling of elec trochemical reversible species at the IDRA microelectrode. We propose a sim ple capillary-electrode connection device that consists of an X-Y-Z fiber a ligner, an electrochemical cell, and a Nafion tubing joint that will enable the detection capillary to be aligned easily on the IDRA microelectrode an d isolate the separation voltage from the electrochemical detection system. We used the off-column amperometric detection of aqueous ferrocene and cat echolamines by capillary electrophoresis with an IDRA microelectrode to inv estigate the effects of the capillary-to-electrode distance and the separat ion voltage on the response currents in single and dual modes and the colle ction efficiencies (CE) and redox cycles (Rc) at the IDRA microelectrode. T he results show that CE and Rc increase when we increase the distance and l ower the separation voltage. The limiting currents also increase as the sep aration voltage decreases in the dual mode. Under optimum conditions, the C E and Rc of catechol, with good reversibility, reach 83.9% and 3.67, respec tively. Our results showed that dual-mode detection with the IDRA microelec trode was capable of achieving lower detection limits than single-mode dete ction.