Development of rotating electrochemical detectors for capillary electrophoresis

A rotating disk electrode (RDE) has been evaluated and optimized for the de tection of electroactive species separated by capillary electrophoresis (CE ), With catechol as a working model, the limit of detection was estimated t o be 0.3 muM i.e., similar to2.5-fold better than that of the stationary di sk electrode (0.7 muM). Separation efficiency was significantly improved as exemplified by an increase of theoretical plates from 26 000 plates/m at 0 rpm to 67 000 plates/m at 500 rpm. Of particular importance was the capabi lity of RDE to alleviate electrode passivation and electrical interference associated with high separation potential fields. Therefore, rotation amper ometry was especially useful for analytes such as phenolic compounds that t ended to rapidly foul the electrode surface. The RDE/CE system was capable of separation and determination of pentachlorophenol in contaminated soils, and the result obtained agreed well with conventional liquid chromatograph y, an EPA recommended procedure.