Sodium ion-selective electrode system and method for making an ion- selective electrode

摘要

A sensor arrangement for monitoring ionic concentrations in fluids uses anion-selective membrane formed of N,N'-dibenzyl-N,N'- diphenyl-1,2- phenylenedioxydiacetamide suspended in an inert carrier, such as PVC having a high molecular weight. The membrane is disposed on a porous ceramic plug which permits wetting of the side of the membrane facing the plug with an internal fluid of the system, such as saline. The other side of the membrane communicates with the fluid to be assayed, which in certain intravenous embodiments may be the blood of a patient. In one embodiment, the system is provided with a reference electrode which is arranged to communicate with the fluid being monitored via a dialysis membrane. High impedance electronic circuitry produces a signal indicative of the ionic concentration in response to a potential appearing across the reference and sensor electrodes. The electronic circuitry has wide range offset and gain controls which are independent of one another, while maintaining the circuitry simple and safe for connection to a patient.