The first reported use of a carbon paste electrochemical detector for microchip capillary electrophoresis (CE) is described. Poly (dimethylsiloxane) (PDMS)-based microchip CE devices were constructed by reversibly sealing a PDMS layer containing separation and injection channels to a layer containing seapration and injection channels to a separate PDMS layr that conmtained carbon paste working electrodes. End-channel amperometric detection with a single electrode was used to detect amino acids derivatized with naphthalene dicarboxaldehyde.Two electrodes were placed in series for dual electrode detection. This approach was demonstrated for the detection 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 derection of thiols folowing a CE separation. These dervices illustrate the potential for an easily constructed microchip CE system with a carbon-based detector that exhibits adjustable selectivity.
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