ON-CHIP MICROBAND ARRAY ELECTROCHEMICAL DETECTOR FOR USE IN CAPILLARYELECTROPHORESIS

A new electrochemical detector, designed for use with conventional cap illary 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 capil laries. 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 separatio n 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 efficienc y of the electrochemical method was reduced, as expected for the off-c olumn detection mode.