Potentiometric detection of monovalent anions separated by ion chromatography using all solid-state contact PVC matrix membrane electrode

An all solid-state contact tubular PVC-matrix membrane electrode has been a pplied for potentiometric detection of inorganic and organic monovalent ani ons using phosphate and hydrogen phosphate eluents at low concentrations. T his is a "monovalent detection method" as the selectivity of the electrode towards monovalent anions results in some other anions being undetected unl ess 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 considerat ions are discussed, and in particular, sensitivity, linearity, detection li mit and dynamic behaviour are presented. The use of an all solid-state contact bromide-selective electrode as a dete ctor 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 precon centration has been successfully achieved. The detection limit is sub-ppb f or most of anions in a 20 mu L injection volume.