Square-Wave Voltammetry Detection for Capillary Electrophoresis

A square-wave voltammetry (SWV) detection method for capillary electrophoresis (CE) using end-capillary detection is investigated. Although sensitive detection methods have been reported using off-capillary electrochemical detection methods, these methods typically use fragile carbon fiber electrodes and complex decoupling apparatus to separate the high separation voltage from the detection electronics. While end-column detection systems are not usually as sensitive as off-column techniques, they require much simpler instrumentation and are more robust. By modifying the Osteryoung SWV method to accommodate the high-frequency sample rate required by CE, a detection limit of 5 × 10-7 M (S/N = 10) was obtained for dopamine using end-capillary detection, which is comparable to sensitivities obtained using off-capillary detection with amperometric detection.