A conjugated polymer-based ratiometric fluorescent probe for on-site quantitative detection of bisulfite in food samples by smartphone assay

Bisulfite (HSO3−), as a preservative, is commonly used in food production and storage, whereas its excessive addition will cause some serious illness to humans. Therefore, it is urgent to develop a convenient method for the quantitative detection of HSO3− in food samples. In this work, a novel conjugated polymer-based ratiometric fluorescent probe PFTQ has been synthesized. In probe PFTQ, the electron-deficient CC bond conjugated with quinolinium moiety specifically reacts with nucleophile HSO3− by 1,2-addition reaction, consequently causing the emission to be changed from red to steelblue. Meanwhile, the signal of fluorescence color can be converted into the digital values by our smartphone optical platform, and a linear relationship of RGB ratio (B/R) with HSO3− concentration is established. The fluorescence sensing is completed within 6 min, and the detection limit is calculated to be 106 nM. Finally, this sensing platform achieves the quantitative detection of HSO3− in crystal sugar, red wine and beer samples with high accuracy.