Abstract: A membrane for use in chloride-sensitive electrodes, comprises a polymer matrix with at least one electroactive component. The polymer matrix of the membrane contains an epoxy resin with an amino compound as a curing agent. For the purpose of reducing the danger of contamination and improving the useful life of the electrode, the epoxy resin is provided with at least one epoxy resin compatible flexibilizer, and the content of epoxy resin plus added flexibilizer in the electrode membrane amounts to more than 60% by weight, while that of the electroactive component is not more than 35% by weight, and preferably not more than 30% by weight.

Abstract: Biological components such as enzymes are immobilized in a three-dimensional cross-linked hydrophobic polymer. An enzyme is mixed with an aqueous solvent and a non-crosslinked prepolymer having an essentially nonpolar main chain with attached polar hydrophilic groups and cross-linking groups. The resultant mixture is exposed to cross-linking temperatures to react the prepolymer via the cross-linking groups without additional catalyst or cross-linking agents, and the aqueous solvent is evaporated to form a three-dimensional cross-linked hydrophobic polymer matrix containing the enzyme. The prepolymer can be an oil alkyl resin containing the main chain with attached polar hydrophilic groups and cross-linking groups. The oil alkyl resin is cross-linked by autoxidation, and aqueous solvent is evaporated to form the polymer matrix.

Abstract: In order to produce a sensitive membrane electrode with high selectivity with respect to other anions and lipophilic ions or interfering substances, the membrane is based on an unplasticized polymer matrix whose content of electroactive component is between 50 and 90 percent by weight.