Potentiometric Detection of Monovalent Anions Separated by Ion Chromatography using All Solid-State Contact PVC Matrix Membrane Electrode

Abstract

An all solid-state contact tubular PVC-matrix membrane electrode has been applied for potentiometric detection of inorganic and organic monovalent anions using phosphate and hydrogen phosphate eluents at low concentrations. This is a "monovalent detection method" as the selectivity of the electrode towards monovalent anions results in some other anions being undetected unless the concentration of those other anions is higher than 10(-3) mol dm(-3) in the sample solution injected. It takes only eight minutes to complete the separation with a good resolution. Theoretical and practical considerations are discussed, and in particular, sensitivity, linearity, detection limit and dynamic behaviour are presented. The use of an all solid-state contact bromide-selective electrode as a detector offers so far the best simultaneous sensitivity toward all anions when compared with other detection methods. Determination of Cl- and NO3- ions in river, rain and drinking water samples without any further sample preconcentration has been successfully achieved. The detection limit is sub-ppb for most of anions in a 20 mu L injection volume.