Electrochemical Detection Using an Engraved Microchip Capillary Electrophoresis Platform

The present study describes a simple strategy to integrate electrochemical detection with an assembled microchip-capillary electrophoresis platform. The electrochemical cell was integrated with a microfluidic device consisting of five plastic squares interconnected with fused silica capillaries, forming a four-way injection cross between the separation channel and three side-arms (each of 15 mm in length) acting as buffer/sample reservoirs. The performance of the system was evaluated using electrodes made with either carbon ink, carbon nanotubes, or gold and under different experimental conditions of pH, capillary length, and injection time. Using this system it was possible to separate the neurotransmitters dopamine and cathecol and to quantify phenol from a real sample using a linear calibration curve with a calculated LOD of 0.7 mu M. A similar concept was applied to determine glucose, by including a pre-reactor filled with beads modified with glucose oxidase (GOx). The latter system was used to determine glucose in a commercial sample, with a recovery of 95.2%. Overall, the presented approach represents a simple, inexpensive, and versatile approach to integrate electrochemical detection with CE separations without requiring access to microfabrication facilities.