Selenium oxide nanostructure-based electrodes for rapid and simultaneous electrochemical determination of oxalic and ascorbic acids in food matrices.

The development of nanostructured electrochemical platforms for rapid and selective sensing of coexisting biomolecules remains a key challenge in food analysis. Herein, selenium oxide nanostructures (SeO2NSs) were synthesized and integrated into carbon-based electrodes to enable the simultaneous electrochemical detection of ascorbic acid (AA) and oxalic acid (OA) in complex food matrices. Comprehensive morphological, structural, and electrochemical characterization studies confirmed the uniform distribution, high surface area, and excellent redox activity of the SeO2NSs. Under optimized chronoamperometric conditions, the SeO2NS-modified electrode exhibited wide linear response ranges of 5.0-550 µM for OA and 5.0-455 µM for AA, with low detection limits of 0.50 µM and 0.43 µM, respectively. The sensor demonstrated remarkable selectivity and stability against common interfering species, ensuring accurate quantification in real samples. Thus, the developed platform was successfully applied to the simultaneous determination of AA and OA in fresh fruits and vegetables (guava, spinach, and mango) and in beverages derived from coffee beans and tea leaves. This work highlights the potential of selenium oxide nanostructures as efficient electroactive materials for high-performance, cost-effective, and reliable electrochemical sensing in food-quality monitoring and safety assessment.