Carbon-nanotube/copper composite electrodes for capillary electrophoresis microchip detection of carbohydrates

The preparation of carbon nanotube (CNT)/copper composite electrodes, based on co-mixing CNT and Cu powders within mineral oil, is described. The new composite electrode is used for improved amperometric detection of carbohydrates following their capillary electrophoresis (CE) microchip separations. The CNT/Cu composite electrode detector displays enhanced sensitivity compared to detectors based on copper or CNT alone. The marked catalytic action of the CNT/Cu composite material permits effective low potential (+0.5 V vs. Ag/AgCl) amperometric detection, and is coupled to the renewability, bulk modification and versatility advantages of composite electrodes. The CNT/Cu composite surface also leads to a greater resistance to surface fouling compared to that observed at the copper electrode. Factors affecting the electrocatalytic activity and the CE microchip detection are examined and optimized. The CNT/Cu composite electrode is also shown to be useful for the detection of amino acids as indicated from preliminary results. While the present work has focused on the enhanced CE microchip detection of carbohydrates and amino acids, the CNT/metal-composite electrode route should benefit the detection of other important groups of analytes.