On-Column Electrochemical Detection for Microchip Capillary Electrophoresis

Author(s): Osbourn, Damon M., Craig E. Lunte

Journal: Anal. Chem. (2003) 75: 2710-2714.

Abstract:
The development of a cellulose acetate decoupler for oncolumn electrochemical detection in microchip capillary electrophoresis is presented. The capillary based laseretched decoupler is translated to the planar format to isolate the detector circuit from the separation circuit. The decoupler is constructed by aligning a series of 20 30- µm holes through the coverplate of the microchip with the separation channel and casting a thin film of cellulose acetate within the holes. The decoupler shows excellent isolation of the detection circuit for separation currents up to 60 µA, with noise levels at or below 1 pA at a carbon fiber electrode. Detection limits of 25 nM were achieved for dopamine. This decoupler design combines excellent mechanical stability, effective shunting of high separation currents, and ease of manufacture.