Highly Selective and Sensitive Electrochemical Detection of Levodopa and Benserazide Using SWCNT–Modified Polyaniline–Based Sensor

This study presents the development of a highly selective and sensitive electrochemical sensor for the simultaneous determination of levodopa (LD) and benserazide (BS), essential pharmaceutical compounds in Parkinson’s disease treatment. The sensor was fabricated through electropolymerization of aniline on a glassy carbon electrode (GCE) in a nonaqueous medium, followed by modification with single-walled carbon nanotubes (SWCNTs). The incorporation of SWCNTs enhanced the electrode’s conductivity, surface area, and electrocatalytic properties, leading to improved detection performance. Various experimental parameters, including pH, polymerization conditions, and SWCNT concentration, were systematically optimized to achieve maximum sensitivity and selectivity. The developed sensor exhibited a linear response range of 500–1000 µM for LD and 100–500 µM for BS, with detection limits of 183.2 µM and 44.5 µM, respectively. The sensor’s robustness was demonstrated by its stability in the presence of ascorbic acid, a common interfering species, ensuring accurate determination of target analytes. Furthermore, real sample analysis was conducted using pharmaceutical formulations and human urine, confirming the practical applicability of the proposed sensor. The results indicate that the SWCNT-modified polyaniline-based electrochemical sensor offers a rapid, reliable, and cost-effective approach for the simultaneous quantification of LD and BS, making it a promising tool for pharmaceutical and clinical applications.