AN INORGANIC GEL MEMBRANE SENSOR FOR CADMIUM IONS

A new solid state membrane sensor has been fabricated using polytungst oantimonate as the electroactive phase. The membrane exhibits promisin g selectivity for cadmium which can be estimated in the range 6.31 x 1 0(-5) to 1.00 x 10(-1) M at pH 5-7 with a near Nerstian slope of 26 mV per decade of concentration. The roman potentials generated across th e membrane are reproducible and the response time is less than a minut e. The electrode works well even in partially non-aqueous medium. Sele ctivity coefficient values for various interfering ions indicate reaso nably good selectivity for Cd2+ ions. The electrode can also be used a s an end point indicator in the titration of cadmium with EDTA.