Ion-Selective Electrode Based on Thiosemicarbazide Schiff Base As Ionophore for Pb (II) Ion Sensor

Abstract

Schiff bases ligands of thiosemicarbazide have received attention because of their biological and electrochemical activity as ionophore. For the present work, Schiff base was synthesised with thiosemicarbazide and thiophene-2 aldehyde in ethanol solvent. Pb (II) ion-selective electrode has been developed by using synthesized Schiff base ligand as ionophore in PVC matrix. This ISE was tested with various parameters such as slope of potential curve, linear response, effect of pH, selectivity and respose time etc. The prposed sensor can be used over a wide concentration range (1.0 ×10–7 to 1.0 ×10–2 M) for lead(II) with a slope of 29.4 ± 0.1 mV decade–1. It has releatively fast reasponse time (<10 s) with high selectivity in presence of various foreign ions. This ISE showed best performance with a membrane composition of PVC: DOP: Ionophore: NaTPB as 33: 59: 3.4: 4.6 (w/w %). The detection limit of the electrode was approximately 4.0 × 10–8 M and the electrode works well in the pH range of 2.4–8.0. The proposed electrode has found application as an indicator electrode for potentiometric titration of Pb(II) with EDTA. It can also be employed for the determination of Pb(II) ions in various wastewater samples. Figure 1