Novel PVC-membrane Potentiometric Sensors based on 2-Amino-N-(2-Mercapto phenyl) Benzamid for Silver Ion

A new highly selective silver (I) electrode was prepared with a PVC membrane using 2-amino-N-(2-Mercapto phenyl) Benzamid (L) as an electroactive material, 2-nitrophenyloctylether (o-NPOE) as a plasticizer and sodium tetraphenylborate (NaTPB) as an additive in the percentage ratio of 3:5:57:35 (NaTPB:L:o-NPOE:PVC, w:w). Potentiometric evaluation of the poly(vinyl chloride) (PVC) membranes containing L showed excellent affinity and selectivity to silver (I) ion over alkali, alkaline earth and other transition metal cations. These electrode works well over wide range of concentration (1.0×10-2 to 1.0×10-7 M) with a Nernstian slope 59.1±0.2 mV/decade. The potentiometric responses are independent of the pH of the test solution in the pH range 2.9–10.3. The electrodes possess advantages of low resistance, fast response time and relatively long lifetimes. The electrodes were used, as indicator electrodes, in the potentiometric titration of silver ion and in the determination of Ag+ in waste water.