Poly(bis(2,2′-bipyridine) hydroxy Copper(II) iodide modified glassy carbon electrode for electrochemical determination of chloroquine in pharmaceuticals and biological samples

Abstract

A new electrochemical sensor, poly(bis(2,2′-bipyridine)hydroxycopper(II) iodide modified glassy carbon electrode (poly([Cu(Bip)2OH]I)/GCE), was prepared by electropolymerization of bis(2,2′-bipyridine)chlorocopper(II) iodide ([Cu(Bip)2Cl]I) on glassy carbon electrode (GCE) for voltammetric determination of chloroquine (CQ). The synthesized complex (bis(2,2′-bipyridine)chlorocopper(II) iodide) was characterized using UV–Vis, CHN elemental analysis, atomic absorption spectroscopy (AAS), electrolytic conductivity, melting point and Fourier transform infrared spectroscopy (FT-IR) were used to characterize and confirm the synthesis of the desired complex (bis(2,2′-bipyridine)chlorocopper(II) iodide). The Uv-Vis, FTIR and electrochemical data of the synthesized polymer supports the replacement of chloro ligand by hydroxyl ligand during electropolymerization of the monomer in aqueous solution. The fabricated electrode (poly([Cu(Bip)2OH]I)/GCE) was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The voltammetric behavior of CQ was examined using CV and square wave voltammetry (SWV). Compared to the bare GCE, poly(Bip)/GCE, and Cu/GCE, the current signal of CQ was significantly enhanced at poly([Cu(Bip)2OH]I)/GCE, which demonstrates excellent electrocatalytic behavior of poly([Cu(Bip)2OH]I)/GCE towards electrochemical oxidation of CQ. Under the optimum experimental conditions, the SWV current signal of poly([Cu(Bip)2OH]I)/GCE offered linearity on the concentration range of CQ between 0.5 and 250 μM with LOD and LOQ values of 4.22 ×10−2 and 1.4 × 10−1 μM, respectively. In the presence of possible interfering substances including glucose, paracetamol, adenine and guanine, the voltammetric determination of CQ was also considered, and their interventions were found to be insignificant, which evidenced the selectivity of the introduced electrode. The analytical application of the established sensor was successfully applied in the determination of CQ in pharmaceuticals, milk, serum, and urine samples. The detected amount of CQ in the tablet samples was in the range between 100.5 and 110.2% with RSD of 1.5 and 1.87%, respectively. The spiked recovery results in pharmaceuticals, milk, serum, and urine biological samples were in the range of 100.5 to 110.2%, 97.13 to 98.12, 103.7 to 103.6% and 95.50 to 97.05%, respectively. These results confirm that the developed method exhibits high applicability for electrochemical determination of CQ in various real samples.