ON-CHIP MICROBAND ARRAY ELECTROCHEMICAL DETECTOR FOR USE IN CAPILLARY ELECTROPHORESIS

A new electrochemical detector, designed for use with conventional capillary electrophoresis systems, is described. The sensor incorporates a platinum microband array electrode and three larger electrodes on a silicon chip. The fluid flow is facilitated over the electrodes by an etched FI glass cap which allows simple connection to separation capillaries. The device was evaluated using a series of catecholamines with the lowest detectable amount of hydroquinone being 1.4 fmol (based on three times the standard deviation (3 sigma) of the background noise). Comparison with ultraviolet (UV) detection, using the same separation system, indicated that electrochemical detection was more sensitive for this range of analytes. The UV detection limit of hydroquinone was 58 fmol. Despite this increased sensitivity, the separation efficiency of the electrochemical method was reduced, as expected for the off-column detection mode.