Multi-Walled Carbon Nanotubes Decorated with Silver Nanoparticles as a Cost-Effective Voltammetric Sensor for the Determination of Paracetamol in Environmental and Pharmaceutical Samples: Experimental–Theoretical Methodology

Paracetamol (PA) treats mild to moderate pain and fever with a high relative safety factor when administered properly. However, PA overuse creates harmful metabolites and serious illnesses. Thus, PA must be continually monitored and measured in environmental, pharmaceutical, and biological samples. In this work, voltammetric sensing of PA using silver nanoparticles (AgNPs) and carboxylated multi-walled carbon nanotubes (AgNPs@HOOC-MWCNT) deposited on screen-printed carbon electrode (SPCE) has been demonstrated. The AgNPs were prepared through a simple reduction method with an average particle size of 46 nm. Both AgNPs and modified electrodes were characterized by ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray analysis. The electrochemical behaviour of PA over the modified (AgNPs@HOOC-MWCNT@SPCE) was studied using cyclic voltammetry (CV). It has been demonstrated that a relatively small quantity of AgNPs results in a considerable improvement in the active surface area of the modified electrode and an increase in the oxidation current of PA. In addition, a computational study was performed to complement the experimental work. Using square wave voltammetry (SWV) under optimal conditions (pH 7.4 and 25 °C), AgNPs@HOOC-MWCNT@SPCE sensor shows an efficient sensing potential with a limit of detection of 0.24 µM in the concentration range of 0.5 to 1000 µM. The reproducibility and repeatability studies and long-term stability for 60 days were illustrated. Ultimately, the practical applications of the proposed method for determining PA in environmental and pharmaceutical samples were demonstrated with satisfactory results.