A Highly Selective and Sensitive Potentiometric Sensor for Copper (II) Ions Using a Schiff Base-Derived Ionophore (E)-2 ((1H-pyrrol-2-yl) methylene amino) benzenethiol

A copper (II)-selective electrode based on a PVC membrane was fabricated using the Schiff base (E)-2-((1H-pyrrol-2-yl) methylene amino) benzenethiol (I) as the ionophore, and its performance was systematically evaluated. The optimized membrane composition consisted of PVC, ionophore, and plasticizer in a 35:2:63 ratio. The sensor exhibited a Nernstian response toward Cu²⁺ ions, with a detection limit of 2.0 × 10⁻8 M and an effective linear range from 3.1 × 10⁻8 M to 1.0 × 10⁻¹ M. A rapid response time of about 8 seconds was observed upon immersion in the test solution. The electrode potential remained stable across a pH interval of 2.0 to 10 The electrode exhibited stable and reliable performance for nearly four months without any noticeable potential drift. In addition, it showed excellent selectivity toward Cu²⁺ ions in the presence of alkali, alkaline earth, transition, and other heavy metal ions. The sensor was effectively employed as an indicator electrode in the potentiometric titration of Cu²⁺ with EDTA and was successfully utilized for the determination of copper ions in real sample matrices.