Graphite paste electrode integrated with pomegranate peel extract-derived ZnO nanoparticles and MWCNTs for green voltammetric analysis of asenapine maleate

The growing need for environmentally favorable analytical methods has encouraged the development of eco-friendly materials for drug analysis. This work explores the use of green nanoparticles for the electrochemical sensing of the antipsychotic drug asenapine maleate (ASEP). Pomegranate peel extract (PPE) was utilized as a green reducing and stabilizing agent for the synthesis of zinc oxide nanoparticles (PPE@ZnO NPs). The synthesized PPE@ZnO NPs were characterized by UV–Vis, SEM–EDX, XRD, HR-TEM, and FT-IR, revealing a spherical morphology and hexagonal wurtzite structure, with a mean particle diameter of 5.28 ± 1.0 nm based on TEM image analysis and a crystallite size of 8.86 nm estimated from XRD. The PPE@ZnO NPs were integrated with multi-walled carbon nanotubes (MWCNTs) into a graphite paste matrix to fabricate the optimized green electrochemical sensor (5% MWCNTs/10% PPE@ZnO/GPE). Under optimized conditions at pH 5, differential pulse voltammetry (DPV) exhibited an irreversible anodic peak for ASEP at + 0.98 V. The proposed method showed a linear range of 8 × 10⁻⁶–1 × 10⁻⁴ M, with detection and quantification limits of 1.71 × 10⁻⁶ and 5.18 × 10⁻⁶ M, respectively. The method was successfully applied to the determination of ASEP in commercial tablets, yielding a satisfactory mean percentage found of 100.13 ± 1.70%. The Analytical GREEnness (AGREE) metric and Analytical Eco-Scale indicated a favorable greenness profile for the proposed method, with an AGREE score of 0.76. Overall, the study highlights the potential of PPE-derived ZnO nanoparticles as green electrode-modifying materials for the voltammetric determination of ASEP.