Amperometric Ion Detector for Ion Chromatography

Abstract

A new type of amperometric detector for nonredox ions based on ion-transfer reactions at the water|2-nitrophenyl octyl ether−poly(vinyl chloride) gel microinterface has been developed. The polarized interface between water and a polymer composite membrane that can incorporate ionophores such as dibenzo-18-crown-6 and valinomycin provides a selective transducer for an amperometric detection of nonredox ions under flow conditions. Such a sensor is employed as a detector for cation-exchange ion chromatography and shows detectability similar to that obtained with a conductivity detection. The main advantage of this approach is that selectivity can be tailored by the choice of the ionophore and by the polarization potential. As an example, we show how to detect ammonium in the presence of an excess of sodium.