ABSTRACT Due to a rising demand for fast and cost-effective analysis, the pharmaceutical and food industries are actively developing portable devices to improve the daily workflow of analysts. Therefore, the present research centers on creating electrochemical sensors that are both economically and environmentally sustainable, with particular focus on a chemically modified electrode referred to as CPE@[VIIO(salen)]. The objective is to enable interaction with theobromine and accurately measure this analyte in powdered chocolate samples. We use atomic force microscopy (AFM) to characterize the electrodes’ surface. Electrochemical techniques, including cyclic voltammetry and square wave voltammetry, demonstrated significant results compared to classical high-performance liquid chromatography (HPLC). The CPE@[VIIO(salen)] electrode, when applied to cyclic voltammetry, indicated electron exchange through diffusion between CPE@[VIIO(salen)] and theobromine. For oxidation, the electrode exhibited an average sensitivity of 2.91 (±0.10) μmol L-1/μA, a limit of detection (LOD) of 0.22 (±0.01) μmol L-1, and a limit of quantification (LOQ) of 0.74 (±0.02) μmol L-1. Reduction processes showed an average sensitivity of 18.66 (±0.44) μmol L-1/μA, LOD of 0.38 (±0.01) μmol L-1, and LOQ of 1.29 (±0.30) μmol L-1. Square wave voltammetry provided sensitivity, LOD, and LOQ values of 5.38 (±0.17) μA/μmol L-1, 0.40 (±0.01) μmol L-1, and 1.35 (±0.04) μmol L-1 in the anodic sweep, and 2.60 (±0.05) μmol L-1/μA, 0.41 (±0.01) μmol L-1, and 2.42 (±0.04) μmol L-1 in the cathodic sweep, respectively. Comparative validation using HPLC indicated sensitivity, LOD, and LOQ for sample 1 at 0.00732 (±2.8310-4) µmol L-1/mAU min-1, 4.93 (±0.02) μmol L-1, and 14.94 (±0.02) μmol L-1, respectively. The sensor demonstrated potential for theobromine detection in food during industrial quality control analyses, aligning with reported values in the literature for classical techniques like HPLC. The results emphasize the viability of CPE@[VIIO(salen)] as a sensitive and selective tool for electrochemical detection, offering promising applications in food analysis and quality control.
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