All-solid-state sodium-selective electrodes based on room temperature vulcanizing-type silicone rubber matrix

Sodium-selective membranes based on room temperature vulcanizing-type silicone rubber (RTV-type SR) matrix and tert-butyl calix[4]arene-tetraacetic acid tetraethyl ester (1.0 wt %) have been developed for all-solid-state-type electrodes. It was observed that the potentiometric response, stability and lifetime of these SR membrane-based all-solid-state electrodes critically depend on the type of lipophilic salts employed. Among the several phenyl berate derivative-based additives examined, the SR membranes prepared with 0.5 wt % tetrakis[3,5-bis(trifluoromethyl)phenyl] berate salt (TFPB) exhibited low impedance, resulting in electrochemical performance comparable to that of the PVC-based membranes mounted in conventional electrodes. The lifetime of all-solid-state electrodes with SR/TPFB/ tert-butyl calix[4]arene tetraethyl ester was longer than 230 days.