Effect of coated open-tubular inorganic-based solid-state ion-selective electrodes on dispersion in flow injection

Abstract

The shape and quality of the analytical signal obtained from coated open-tubular inorganic-based solid-state ion-selective electrodes interfaced to a flow injection system are directly influenced by both the electrode and the flow injection system. The electrode characteristics and response, in a flow-through system, are controlled by the chemical properties of the specific electrode used and the partial dispersion arising from the flow dynamics of the system. The efficiency of electrode functioning depends on the nature of the electrode membrane surface, the way in which the electrode is coated, the conditioning of the electrode and contributions from diffusion-convection transport, all resulting in a concentration-time profile. The effects of these parameters on the dynamic linear response range, practical response time and peak shape are described. The Gaussian peak shape is distorted at the lower front and back part of the peak, which is attributed to the predominance of an electrode mechanism at low chloride concentrations. At the centre portion of the sample plug, however, where the chloride concentration is higher, the influence of dispersion flow dynamics becomes predominant.