Electrochemically Embedded Cerium Oxide Nanoparticles on Activated Carbon Electrode for Simultaneous Determination of Quercetin and Rutin

Flavonoids (FLs) are bioactive compounds commonly found in medicinalplants, fruits, andvegetables. FLs have received considerable attention due to their medical applications as therapeutic agents. This study presents an electrochemical sensor for detecting two well-known FLs, quercetin (Qrt) and rutin (Ru). The sensor utilizes a preanodized screen-printed carbon electrode (SPCE*) modified with cerium oxide nanoparticles (CeO₂). Preanodization activates the carbon surface of the electrode to enhance its electroactivity, while the immobilized CeO₂ acts as an electrocatalyst. The modified electrode SPCE*/CeO₂ was characterized using various techniques, including field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS). Compared to the unmodified SPCE, SPCE*/CeO₂ exhibits superior conductivity, increased active surface area, and oxygen vacancies, all of which contribute to improved performance in electrochemical sensing for Qrt and Ru. Under optimized conditions, the constructed sensor, analyzed by differential pulse voltammetry (DPV), achieved low limits of detection (LOD), with linear ranges of 0.6–45 and 0.6–35 μM for Qrt and Ru, respectively. Furthermore, the developed assay exhibited low interference, good reproducibility, and moderate stability. The method successfully detected Qrt and Ru in fruit juice via the standard addition approach with satisfactory recoveries, demonstrating its potential application in the food industry.