Potentiometric Detection of Alkali and Alkaline Earth Metal Cations in Capillary Electrophoresis with Simplified Electrode Alignment and Enhanced Separation and Sensitivity

Abstract

Coated-wire electrodes were employed as potentiometric detectors for the analysis of alkali and alkaline earth metals by capillary electrophoresis. Easy electrode alignment was achieved by a Plexiglas capillary-electrode holder, which makes it unnecessary to employ a microscope and a micromanipulator. The addition of a crown ether to the running electrolyte not only renders possible the complete separation of ammonium and potassium but also improves considerably the sensitivity of the coated-wire electrode. We studied the dependence of the migration times on the crown ether concentration as well as the change in sensitivity by means of calibration curves for potassium and calcium.