Synergistic Fe(III)-Clinoptilolite and Multi-Walled Carbon Nanotube Composite for Enhanced Voltammetric Determination of Opipramol in Complex Matrices

This work introduces a novel electrochemical sensor based on a Fe(III)-exchanged natural zeolite clinoptilolite (Fe-CLIN) and multi-walled carbon nanotubes (MWCNTs) nanocomposite, applied to the voltammetric determination of opipramol (OPI). The Fe-CLIN/MWCNTs layer was drop-cast onto a glassy carbon electrode (GCE) to fabricate a modified sensor (Fe-CLIN/MWCNTs-GCE) exhibiting enhanced electrochemical performance due to the synergistic combination of the ion-exchange properties of zeolite and the high conductivity of MWCNTs, which confirmed the results of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. In the quantitative analysis of OPI, the differential pulse voltammetry (DPV) technique was employed, with the method optimized for instrumental parameters, the pH value of the supporting electrolyte, and the preconcentration time (tacc). In McIlvaine buffer solution (pH 5.0), the Fe-CLIN/MWCNTs-GCE demonstrates linear response to the OPI concentration in the range of 0.004 to 0.27 mg L-1 with the limit of detection (LOD) equal to 0.5 µg L-1 (tacc = 90 s). The method was successfully applied to the determination of OPI in pharmaceutical tablets and synthetic biological and environmental matrices with recovery of 90.0 - 115.0%, confirming the analytical utility and robustness of the presented sensor for real sample analysis.