Electrochemical sensor based on nanocomposite of nickel oxide nanoparticles and polypyrrole for the detection of metoprolol as a doping agent in biological fluids and food samples

In this work, a new electrochemical sensor for the detection of the doping agent metoprolol (MTP) in food samples and bodily fluids is presented. The sensor’s foundation is a nanocomposite made of polypyrrole (PPy) and nickel oxide nanoparticles (NiO NPs) on a glassy carbon electrode (GCE). Pyrole was electropolymerized to create the nanocomposite, and then NiO NPs were electrodedeposited on the GCE surface (NiO NPs/PPy/GCE). By combining the benefits of PPy with NiO NPs, this technique offers good electrocatalytic activity and a large surface area for analyte interaction. The nanocomposite was characterized using structural analyses such as scanning electron microscopy (SEM), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). These analyses revealed a network-like structure that improved the accessibility of the electrolyte ions and showed that the nanocomposite had been successfully deposited on the GCE surface. The electrochemical MTP sensor was examined using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) tests. The sensor’s sensitivity was 0.03074 μA/μM, and it demonstrated a linear connection between the peak currents and the MTP concentrations (5–1600μM). The suggested sensor’s limit of quantification (LOQ) and limit of detection (LOD) were determined to be 0.581 μM and 0.018 μM, respectively. The prepared urine sample produced acceptable recovery rates in the range of 98.40–99.86% in the real sample analyses, together with low relative standard deviation values (below 4.16%). In a similar vein, the prepared apple juice sample analysis revealed low relative standard deviation values (less than 4.28%) and respectable recovery rates ranging from 97.20 to 99.66%. The results showed low relative standard deviation values and good recovery rates, demonstrating the high precision and dependability of the suggested approach.