Cobalt(II) bis-(1,10-phenanthroline) complex electropolymerized glassy carbon electrode and its electrocatalytic sensing of diclofenac in pharmaceuticals and biological samples

Abstract

Diclofenac (DCF) is a nonsteroidal anti-inflammatory drug (NSAID) that is used to treat acute and chronic inflammatory diseases. High consumption and indiscriminate use of DCF pose serious health issues, prompting the consideration of electroanalytical methods for detecting and controlling DCF levels in various samples. A sensitive and highly selective sensor was established for voltammetric determination of diclofenac (DCF) based on poly[cobalt(II) bis-(1,10-phenanthroline) complex] modified glassy carbon electrode (poly(Co(Phen)2)/GCE). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the performance of a poly(Co(Phen)2)/GCE sensor, revealing a negative oxidation potential shift and higher DCF peaks of current. CV and adsorptive stripping square wave voltammetry (AdSSWV) were used to evaluate the electrochemical behavior of DCF at poly(Co(Phen)2)/GCE. Under the optimized experimental conditions, AdSSWV current signal of DCF at poly(Co(Phen)2)/GCE provided linearity over the range of 1–250 μM with a limit of detection (LOD) and limit of quantification (LOQ) of 6.40 ×10−2 and 2.13 ×10−1, and 5.60×10−2 and 2.27×10−1 µM for Ip I and Ip II, respectively. The sensor for determining DCF was tested in pharmaceuticals, milk, serum, and urine samples, demonstrating excellent selectivity despite potential interferences like atorvastatin (ATS), chloroquine (CQ), and sulfamethoxazole (SMX). The detected DCF amounts ranged between 92.3% and 106.6%. The established sensor demonstrated excellent performance in determining DCF in real samples, with spiked recoveries exceeding 95.6%, demonstrating low LOD, high sensitivity, selectivity, repeatability, and long-term stability. These results confirm that the established method displays outstanding applicability for electrochemical determination of DCF in numerous real samples.