A ratiometric fluorescent sensor based on dual-emitting carbon dots for the rapid detection of sulfite.

Sulfur dioxide (SO2) derivatives are typically employed as antioxidants in food and pharmaceutical processing. However, excessive sulfite intake could trigger serious health problems. Hence, it is urgent to establish a rapid and effective system for monitoring SO2. This study adopted a one-step hydrothermal method to synthesize dual-emitting nitrogen-doped carbon quantum dots (CECDs) and developed a ratiometric sensor for sulfite using CECDs-Cr (VI) composites. The emission intensity ratio (I440/I500) of the CECDs-Cr (VI) composites increased considerably with the addition of HSO3-. A method based on the ratiometric sensor was established for SO2 derivatives with advanced efficiency and excellent linearity over a broad concentration range of 0-500 μM (R2 = 0.9946). Four medicine-food homology materials (MFHMs) fumigated with sulfur have been accurately detected using this approach. Furthermore, a portable test tube was prepared to achieve rapid and semi-quantitative detection of SO2 residues and applied to real samples. This work presents an effective approach to develop a rapid on-site detection platform for sulfite residues in food and pharmaceuticals.