Potentiometric detection of inorganic anions and cations in capillary electrophoresis with coated-wire ion-selective electrodes

The construction of coated-wire ion-selective electrodes of small size with two different PVC-based membranes is described. The electrodes are used as potentiometric end-column detectors for monovalent anions and alkali and alkaline earth metal cations separated by capillary electrophoresis. In comparison to conventional micropipette electrodes these all solid state electrodes showed a similar performance but much higher mechanical robustness and a longer lifetime which was found to be 9 and 8 days, respectively. Calibration curves for Cl− and Ca2+ demonstrate the wide dynamic range of these detectors and detection limits of lower than 10−7 and 10−8 M could be achieved using the electrostacking technique.