A Chip-Based Electrophoresis System with Electrochemical Detection and Hydrodynamic Injection

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Abstract
A simple capillary electrophoresis system in the planar format that uses a new, hydrodynamic injection principle is described. The system was realized with poly(dimethylsiloxane)−glass chips and microdisk electrodes for amperometric detection. Using a double-tee injector, no precise voltage control of the electrolyte reservoirs was needed, thus making the microchip CE system more user-friendly. The analytical characteristics of chip-based CE-EC were evaluated using ascorbic acid as the model analyte. The reproducibility of migration time and signal height was expressed by relative standard deviations of 1.2% and 5.1%, respectively (n = 5). The limit of detection for ascorbic acid was ∼5 μM at a signal-to-noise ratio of 3. Practical application concerning the determination of physiologically relevant compounds such as noradrenaline and l-dopa are discussed.