Ions-sensitive cell having easily replaceable membrane - with all-round flow, clamped in position by screw

A through-flow cell for continuous measurements of ions activity comprises a cell block through which a narrow bore conducts the medium to be measured. Perpendicular to the bore is a second, wider bore, in which an ion-sensitive membrane is mechanically fitted with sealing rings, so that a narrow channel is formed around (on both sides of) the membrane for the medium to flow past it. Pref. there are two such wider bores, the second one housing a reference electrode or a second membrane. The two wider bores are pref. parallel to each other. Pref. the ion-sensitive membrane is screwed into the bore and the cell block is of plastic. Standard membranes, made by pressing or crystallisation, canbe used, resulting in a very economical arrangement. Axial pressure is applied to the membrane by a screw, giving a good sealing action and reliable electrode functioning. It is only necessary to undo this screw in order to remove and replace the membranes. Membranes can be rapidly replaced for measurements of different types of ions. Also, several different membranes can be incorporated in a single block, so that activities and concentrations of different ions can be measured simultaneously. Solid or liquid conductors from the membranes can be used with equal facility. Since the duct around the membrane can be made as wide as desired, the adjustment time is dependent upon the setting up of conviction and not of diffusion, and therefore adjustment times of a few seconds are attainable.