New Ni(II) Ion-Selective Electrode Based on the N-S Schiff Base Ligand as Neutral Carrier in PVC Matrix

Abstract

A nickel(II) [Ni(II)] ion-selective electrode was prepared by incorporating a new N-S Schiff base ligand, glyoxal-bis(S-benzyldithiocarbazate) (GBSB), as a neutral carrier into the PVC matrix. The proposed electrode exhibits an excellent near-Nernstian response for Ni²⁺ ions, ranging from 2.8 × 10⁻⁷ to 1.0 × 10⁻¹ mol/L with a detection limit of 1.2 × 10⁻⁷ mol/L and a slope of 31.9 ± 0.3 mV/dec in pH 4.0 nitrate buffer solution at 25°C. It has an appropriate response time and suitable reproducibility and can be used for at least 3 months. The operational pH range of the proposed electrode is 4.0–7.5. The response mechanism is discussed in view of the alternating current (AC) impedance technique. In addition, the electrode was successfully used as an indicator electrode in potentiometric titration of Ni²⁺ ion and in the direct determination of Ni²⁺ ion in milk power and chocolate samples.

Keywords:

• Ion-selective electrode
• nickel
• N-S Schiff base ligand
• potentiometric response characteristic
• PVC membrane

This project was supported by Chongqing Municipal Key Laboratory on Luminescence and Real-Time Analysis, Southwest University (CSTC, 2006CA8006), the National Natural Science Foundation of China (20675064), and the Natural Science Foundation of Chongqing City, China (CSTC-2004BB4149).