Electrochemical Sulfite Sensing: Current Trends and Challenges in Food Quality Control and Real Samples

The analytical surveillance of sulfite species (SO₃^2-, SO₂ and HSO₃^-) is critical for food safety due to their roles as preservatives and potent allergens. Despite stringent regulations, conventional methods like Monier-Williams distillation remain limited by labor-intensive protocols and matrix interferences. This review elucidates the chemical mechanisms of sulfites in food matrices and critically evaluates recent advancements in electrochemical sensing. A primary focus is placed on delineating physicochemical bottlenecks, such as electrode fouling and cross-reactivity from polyphenols and organic acids, which hinder commercialization. We analyze the strategic integration of nanostructured interfaces-including bimetallic nanoparticles, carbon-based hybrids (rGO/PPy), and nanozymes-to reduce oxidation overpotentials and enhance sensitivity below regulatory thresholds. Furthermore, the transition from laboratory prototypes to decentralized, field-deployable platforms using screen-printed electrodes (SPEs) and smartphone-based potentiostats is explored. By synthesizing technical innovations with "green" analytical principles, this work provides a roadmap for real-time quality control in the food industry, bridging the gap between fundamental electrochemistry and industrial scalability.