Voltammetric sensing probe using MoS₂-rGO nanocomposite fabricated pencil graphite electrode for electro-kinetic study of the antidepressant drug paroxetine in pharmaceuticals

Development and design of the nanocomposite fabricated pencil graphite electrode with higher selectivity, low cost, and desirable stability are required to increase the detection ability of the voltammetric sensors. In the present study, molybdenum sulfide–reduced graphene oxide (MoS₂-rGO) nanocomposite fabricated pencil graphite electrode (MoS₂-rGO/PGE) was developed to study the electro-kinetic behavior of the antidepressant medicine paroxetine. A simple one-step and cost-effective hydrothermal method was used to synthesize the micro-flowers of MoS₂ and MoS₂-rGO composite. The XRD, Raman spectroscopy, SEM, and TEM techniques are utilized to characterize the morphology and microstructure of the prepared MoS₂-rGO, which revealed the distribution of the MoS₂ micro-flowers over rGO flakes that enhance the electro-catalytic activity of MoS₂-rGO/PGE. The irreversible electro-oxidation of the paroxetine at MoS₂-rGO/PGE vs. Ag/AgCl electrode is diffusion controlled but also affected slightly by the adsorption process. The different electrochemical quantities such as heterogeneous rate constant (K_h = 5.0 × 10⁻³cms⁻¹), charge transfer coefficient (α = 0.69), diffusion coefficient (D_o = 6.98 × 10⁻⁴cm²s⁻¹), surface coverage (Γ^o = 1.77 × 10⁻⁹ molcm⁻²), and effective electrode surface area (A = 0.0419 cm²) were reported. Advanced differential pulse and square wave voltammetry (DPV and SWV) were utilized for the quantification of the paroxetine in pharmaceutical samples with a linearity range of 0.5 to 2.5 and 0.5 to 3.1 μM with LOD values of 0.46 and 0.42 μM, respectively. The lower values of LOD, LOQ, and RSD% make DPV and SWV viable electro-analytical methods for the sensitive, cost-effective, and eco-friendly detection of the antidepressant drug paroxetine employing MoS₂-rGO/PGE probe.