Electromembrane extraction combined with a functionalized multi-walled carbon nanotube modified electrode for highly sensitive determination of dextromethorphan in pharmaceutical formulations

This study introduces a robust and highly sensitive sensing platform for the pharmaceutical analysis of dextromethorphan (DXM) by integrating electromembrane extraction (EME) with a functionalized multi-walled carbon nanotube-modified screen-printed carbon electrode (fMWCNTs/SPCE). The analyte was selectively extracted from an aqueous donor phase, passed through a liquid membrane of 2-octanol supported in a hollow fiber, and preconcentrated into an acidic acceptor phase under a constant electrical potential. The enriched acceptor phase was subsequently analyzed using the fMWCNTs/SPCE. The electrochemical behavior of DXM at the surface of the modified SPCE was investigated using cyclic voltammetry (CV) and square wave voltammetry (SWV). The results demonstrated that the fMWCNTs/SPCE significantly enhanced the peak current and accelerated electron transfer kinetics compared to bare SPCEs. Under optimized EME conditions (100 V for 15 min), the method achieved a detection limit of 50 nM within a linear range of 0.1–50 µM. The developed EME-fMWCNTs/SPCE methodology was successfully validated through the analysis of DXM in pharmaceutical tablets and syrups, yielding excellent recoveries of 99.07% and 99.69%, respectively.