Potentiometric detection in capillary electrophoresis with a conducting oligomer electrode

A conducting oligomer-based electrode was used as a potentiometric detector for capillary electrophoresis. The electrodes were made by coating copper wires (250 mu m diameter) with conducting oligomer blends. The oligomer was of the phenylene vinylene type. The potential changes occurring at the sur face of the conducting oligomer electrode were measured in a wall-jet confi guration. A mixture of 10 linear saturated fatty acids was separated using different buffers as running electrolytes. For hexanoic acid, the calibrati on curve showed linearity up to injected concentrations of 7 x 10(-4) M and a detection limit of 1 x 10(-6) M was obtained. The intra-electrode variat ion was 1.7%. The electrode showed a lifetime of at least three weeks. A th eoretical model was given to describe the behaviour of the potentiometric d etector. (C) 1999 Elsevier Science B.V. All rights reserved.