Based upon the intramolecular charge transfer (ICT) mechanism, a novel ratiometric fluorescent probe EB was developed to detect SO32−/HSO3−. The probe displayed both colorimetric and ratiometric responses toward SO32−/HSO3−. It displayed a quick response (within 60 s), good selectivity and high sensitivity (a detection limit of 28 nM) towards SO32−/HSO3−. The SO32−/HSO3− sensing mechanism was confirmed as the Michael addition reaction by ESI-MS. Moreover, the probe could be applied to measure the level of sulfite in real samples, like sugar and chrysanthemum, and it could also be used to detect SO32−/HSO3− in HepG2 cells through confocal fluorescence microscopy, which proved its practical application in clinical diagnosis.
