A distinctive near-infrared fluorescence turn-on probe for rapid, sensitive and chromogenic detection of sulfite in food

Sodium sulfite (Na2SO3) is widely used as a food additive, but the excessive residue of SO32- in food can cause irritative effects and damages to the human body. In this study, we reported a novel near-infrared (NIR) fluorescent probe (DCMQ) for visual detection of SO32- based on a chromogenic reaction. The probe can quantitatively determine SO32- with high specificity and sensitivity, fast response (< 50 s) as well as a low detection limit (31.6 nM). A 1,4-Michael addition reaction was proposed for the sensing mechanism of this probe, which was confirmed by H-1 NMR and HR-MS spectra. The probe has been successfully utilized to determine SO32- in food with good recovery, remarkable chromogenic effect and NIR fluorescence turn-on response. Furthermore, the probe has been prepared as a reagent kit for instant on-site visual detection of SO32- in food. Therefore, this probe has great potential application for the detection of SO32- in food.