Microfibre matrix-supported ion-selective PVC membranes

Abstract

In this paper we present a new ion-selective membrane that allows the production of very low-cost ion-selective electrodes (ISEs). The key innovation is the use of a double-matrix membrane. The ion-selective polymeric membrane is formed in the volume of an electrochemically inert microfibre matrix (MFM). The MFM can be filter paper, membrane filters, a glass-fibre matrix or another microporous material. A casting or dipping technique is used to bring the ISE membrane-cocktail solution (standard cocktails used for the production of a conventional ISE) into the MFM, where it is homogeneously distributed of the MFM, which can be a mass product with a high quality, i.e., parameter control can be achieved. The concept is applicable to electrodes with liquid internal solution and to coated film electrodes. The response of the new ISEs with double-matrix membranes is comparable to the response of classical ISEs with the same liquid membranes. No significant differences in selectivity, detection limit or slope are observed. Since the production of double-matrix membranes is a large-area process, it should become possible to form ISEs with almost identical properties.