A mercury(II) ion-selective electrode based on neutral salicylaldehyde thiosemicarbazone

A new ion-selective PVC membrane electrode based on salicylaldehyde thiosemicarbazone as an ionophore is developed successfully as sensor for mercury(II) ions. The electrode shows excellent potentiometric response characteristics and displays a linear log[Hg(2+)] versus EMF response over a wide concentration range of 1.778x10(-6)-1.0x10(-1) M with Nernstian slope of 29 mV per decade with the detection limit of 1.0x10(-6) M. The response time of the electrode is less than 30 s and the membrane electrode operates well in the pH range of 1.0-3.0. The lifetime of the sensor is about 2 months. The electrode shows better selectivity towards Hg(2+) ions in comparison with the alkali, alkaline and some heavy metal ions; most of these metal ions do not show significant interference (K(Pot)(Hg,)(M) values of the order of 10(-3)-10(-4)). The present sensor showed comparable or even better performance vis-à-vis similar PVC based ion-selective electrodes reported in literature. The sensor was also applied as an indicator electrode for potentiometric titration of Hg(2+)ions with I(-) and Cr(2)O(7)(2-).