MICROFIBER MATRIX-SUPPORTED ION-SELECTIVE PVC MEMBRANES

In this paper we present a new ion-selective membrane that allows the production of very lowest ion-selective electrodes (ISEs). The key inn ovation is the use of a double-matrix membrane. The ion-selective poly meric membrane is formed in the volume of an electrochemically inert m icrofibre matrix (MFM). The MFM can be filter paper, membrane filters, a glass-fibre matrix or another microporous material. A casting or di pping technique is used to bring the ISE membrane-cocktail solution (s tandard cocktails used for the production of a conventional ISE) into the MFM, where it is homogeneously distributed by caplliary forces. Th e homogeneity and thickness of the double-matrix membrane depend on th e properties of the MFM, which can be a mass product with a high quali ty, i.e., parameter control can be achieved. The concept is applicable to electrodes with liquid internal solutions and to coated film elect rodes. The response of the new ISEs with double-matrix membranes is co mparable to the response of classical ISEs with the same liquid membra nes. No significant differences in selectivity, detection limit or slo pe 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.