Lead(II)-Selective Potentiometric Sensor Based on Schiff Base of Thiophene-2-Aldehyde Thiosemicarbazone (TATS) in PVC Matrix

A new lead(II) PVC membrane sensor incorporating thiophene-2-aldehyde thiosemicarbazone (TATS) as ionophore, tetraphenylborate (NaTPB) in the form of anion excluder and dioctylphthalate (DOP) as a plasticizer was constructed. The optimum membrane prepared with composition as 33:59:3.4:4.6 (w/w%) of PVC:DOP:Ionophore:NaTPB, exhibits best results with linear potential response in the concentration range (1.0×10–7 to 1.0×10–2 M) and 29.4±0.1 mV/decade of slope. The performance of electrode and its electrochemical response to Pb2+ were thoroughly studied and found good over a pH range of 2.4–8.0, with a short response time of <15 s. The sensor can be used for at least 4 months with reproducible results and is inert in non-aqueous content up to 15% (v/v). It exhibits good selectivity among a wide variety of alkali, alkaline earth and other metal ions. The electrode was usefully applied in the form of an indicator electrode for potentiometric titration of Pb (II) ion with EDTA and to determine Pb2+ ion in some water samples.