POTENTIOMETRIC DETECTION OF INORGANIC ANIONS AND CATIONS IN CAPILLARYELECTROPHORESIS 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 a re used as potentiometric end-column detectors for monovalent anions a nd alkali and alkaline earth metal cations separated by capillary elec trophoresis. In comparison to conventional micropipette electrodes the se all solid state electrodes showed a similar performance but much hi gher mechanical robustness and a longer lifetime which was found to be 9 and 8 days, respectively. Calibration curves for Cl- and Ca2+ demon strate the wide dynamic range of these detectors and detection limits of lower than 10(-7) and 10(-8) M could be achieved using the electros tacking technique.