Cd(II) Ion-Selective Electrode Based on 2–Acetylthiophene Semicarbazone in Polymeric Membrane

A new polyvinylchloride membrane sensor for Cd2+ ions has been prepared using 2–acetylthiophene Semicarbazone (ATS) ligand as an electroactive ionophore and dibutylphthalate (DBP) as a plasticizing agent. The best performance was recorded with a membrane composition of PVC: DBP: Ionophore: NaTPB as 31: 64: 3.2: 1.8 (w/w %). The sensor exhibits a Nernstian response for Cd2+ ions over a wide concentration range (1.0×10–5 to 1.0×10–1M) with a slope of 29.4±0.2 mV decade–1. It has a fast response time of ˂10 s and can be used for at least 5 weeks without any divergence in potential. The electrode can be used in the pH range from 3.4 to 7.6. The proposed sensor revealed relatively good selectivity and high sensitivity for Cd2+ ions in presence of a number of mono, di and trivalent interfering cations within the working range of the electrode. The electrode was successfully applied for the direct determination of Cd2+ in solution and, as an indicator electrode, in potentiometric titration of cadmium ions using ethylenediamine tetraacetic acid (EDTA) as titrant.