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[Hg2+] versus EMF response over a wide concentration range of 1.778×10−6–1.0×10−1 M with Nernstian slope of 29 mV per decade with the detection limit of 1.0×10−6 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 Hg2+ ions in comparison with the alkali, alkaline and some heavy metal ions; most of these metal ions do not show significant interference (KPotHg, 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 Hg2+ions with I− and Cr2O72−.