A Novel BODIPY-Derived Fluorescent Sensor for Sulfite Monitoring

Sulfur dioxide (SO2) is commonly employed as an antioxidant and preservative in food processing, but excessive intake of SO2 can pose significant health risks. Therefore, accurate detection of sulfite content in food is crucial for ensuring food quality and safety. A novel fluorescent probe, BODIPY-Y, composed of a BODIPY derivative and an ethyl cyanoacetate group linked by a carbon–carbon double bond, was synthesized for detecting sulfur dioxide derivatives. When the BODIPY-Y probe interacts with SO32−, the probe exhibits enhanced fluorescence at 514 nm. Spectrometric experiments show that the probe exhibits high sensitivity (LOD: 0.263 μmol/L), a fast response time (50 s) and excellent selectivity for SO32−. Mechanistic studies confirm that the BODIPY-Y probe operates via an intramolecular charge transfer (ICT) mechanism. The carbon–carbon double bond in BODIPY-Y undergoes nucleophilic addition with SO32−, blocking the ICT process and resulting in a blue shift in the fluorescence spectrum. In addition, the probe was applied to quantify SO32− levels in real food samples. The measured concentrations of SO2 in the white sugar and red wine were 15.93 μmol/L and 7.30 μmol/L, respectively, with recovery rates of 77.9–98.1%. This work presents a prospective chemical tool for monitoring sulfur dioxide derivatives in food products.