Potentiometric detection in capillary electrophoresis with a conducting oligomer electrode Original Research Article

A conducting oligomer-based electrode was used as a potentiometric detector for capillary electrophoresis. The electrodes were made by coating copper wires (250 μm diameter) with conducting oligomer blends. The oligomer was of the phenylene vinylene type. The potential changes occurring at the surface of the conducting oligomer electrode were measured in a wall-jet configuration. A mixture of 10 linear saturated fatty acids was separated using different buffers as running electrolytes. For hexanoic acid, the calibration curve showed linearity up to injected concentrations of 7×10−4 M and a detection limit of 1×10−6 M was obtained. The intra-electrode variation was 1.7%. The electrode showed a lifetime of at least three weeks. A theoretical model was given to describe the behaviour of the potentiometric detector.