Separation of metal ions by capillary electrophoresis – diversity, advantages, and drawbacks of detection methods

Abstract

Capillary electrophoresis (CE) has been applied to metal-ion analysis during the last 10 years. To improve sensitivity and selectivity different modes of detection have been adapted or developed. The selection of commercially available detection systems for metal-ion analysis is still primarily limited to UV–Vis detection, although other commercial systems, e.g. fluorescence, conductivity, or interfaces for coupling to mass spectrometry (MS) or inductively coupled plasma mass spectrometry (ICP–MS) are becoming available. High demands are made on any detector used in CE, because the analytical signal has to be extracted from less than 1 nL of sample, which corresponds to a total amount of ≤ 10^–12 to 10^–15 mol analyte. This paper compares currently available and recently developed detection methods for CE as applied to the analysis of metal ions. Commercially available techniques, for example UV– Vis, fluorescence, or mass spectrometry, and other new detection methods including electrochemistry, radioactivity, and XRF, are discussed and future trends are anticipated.