Carbon paste-based electrochemical detectors for microchip capillary electrophoresis/electrochemistry

The first reported use of a carbon paste electrochemical detector for micro chip capillary electrophoresis (CE) is described. Poly(dimethylsiloxane) (P DMS)-based microchip CE devices were constructed by reversibly sealing a PD MS layer containing separation and injection channels to a separate PDMS la yer that contained carbon paste working electrodes. End-channel amperometri c detection with a single electrode was used to detect amino acids derivati zed with naphthalene dicarboxaldehyde. Two electrodes were placed in series for dual electrode detection. This approach was demonstrated for the detec tion of copper(II) peptide complexes. A major advantage of carbon paste is that catalysts can be easily incorporated into the electrode. Carbon paste that was chemically modified with cobalt phthalocyanine was used for the de tection of thiols following a CE separation. These devices illustrate the p otential for an easily constructed microchip CE system with a carbon-based detector that exhibits adjustable selectivity.