Simultaneous determination of paracetamol and codeine phosphate in combined tablets by an electrochemical method using TiO₂/rGO modified glassy carbon electrode

In the present paper, a nanocomposite of rGO and TiO₂ nanoparticles (TiO₂/rGO) was prepared by a facile synthesis method with peroxo titanium complexes as TiO₂ precursor. The morphology and structure of TiO₂/rGO nanocomposite were investigated by X-ray diffraction (XRD), Raman spectroscopy, nitrogen adsorption/desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX)-elementary mapping spectroscopy. It was found that TiO₂/rGO nanocomposites with high surface area were formed involving strong coupling interaction between TiO₂ and rGO. Based on the synergistic effect of rGO and TiO₂ nanoparticles, an electrochemical sensor for paracetamol (PAR) and codeine (COD) was fabricated by modifying the glassy carbon electrode (GCE) with TiO₂/rGO material. The cyclic voltammetry (CV) and differential pulse anodic stripping voltammetry (DP-ASV) were used to determine the electrochemical signals of these analytes. CVs of this sensor provided distinct and sharp oxidation peaks for PAR and COD. The DP-ASV parameters were optimized. It was found that the proposed electrode exhibits excellent electrochemical activity toward PAR and COD. Under the optimal conditions, the A low limit of detection of 0.28 µM for PAR and 0.25 µM for COD were achieved in the linear range from 0.4 to 2.0 µM for both PAR and COD. The proposed method was free from the interference effects of glucose, ascorbic acid, caffeine, and other inorganic salts. This electrode was also highly stable and sensitive making it applicable in the analysis of various real pharmaceutical samples.