Therapeutic Monitoring of Proguanil in Urine Using a CuS/CuO@MWCNT-Based Electrochemical Sensor

This study presents a ternary nanocomposite comprising copper sulphide (CuS) and copper oxide (CuO) nanoparticles coated multi-walled carbon nanotubes (MWCNT) for the determination of Proguanil in urine. The composite was synthesised via a simple one-step, environmentally friendly hydrothermal method. A modified working electrode was fabricated by drop-casting the composite on the surface of the bare electrode. The resulting electrochemical sensor (CuS/CuO@MWCNT/GCE) demonstrated a low limit of detection (LOD) of 3.4 × 10 − 7 M and a broad linear detection range from 1 × 10 − 5 to 8 × 10⁻⁵ M for Proguanil. The fabricated electrode successfully detected Proguanil in urine samples prepared in phosphate buffer (pH 3.5), achieving an LOD of 4.5 × 10 − 7 M, thereby confirming its applicability for real sample analysis. Furthermore, the fabricated sensor exhibited excellent selectivity in the presence of various interfering agents, with an average accuracy of 96.71%, and showed high reproducibility, with a relative standard deviation (RSD) of 0.45% across three identically fabricated electrodes tested in triplicate. These results demonstrate the potential of the CuS/CuO@MWCNT/GCE sensor as a reliable tool for proguanil monitoring in urine.