Smart caffeine sensing: an e-MIP-based screen-printed voltammetric cell for beverage quality control

Caffeine, a widely consumed stimulant, requires rapid screening methods for quality control in the food and pharmaceutical industries. In this context, the present study proposes an electrochemical sensor for caffeine using screen-printed voltammetric cells with a carbon-ink working electrode modified with an electrosynthesized overoxidized polypyrrole molecularly imprinted polymer (e-MIP_ox). Screen-printed electrodes offer advantages like versatility and low cost. Modifying them with e-MIPs, prepared in this case with pyrrole and caffeine as a template, enhances sensitivity and selectivity. Moreover, electropolymerization allows precise control over the polymeric film thickness on the electrode. Differential Pulse Voltammetry (DPV) was employed for the measurements, exploiting the caffeine oxidation peak. The e-MIP_ox sensor outperformed unmodified and non-imprinted electrodes in terms of sensitivity and reproducibility, while demonstrating high selectivity in interference tests. Successfully applied to soft drink samples with recovery rates of 90-110 %, this sensor shows promise as a reliable and efficient tool for food analysis.