Two Reaction-Based Fluorescent Sensors with Cationic Group Enable High-Selective Detection of HSO3– in the Environment

Fluorescent PVBTI and HPVBTI with D-pi-A structure were synthesized and could sensitively and selectively sense bisulfite (HSO3-) in phosphate-buffered saline solution (pH 7.4) via a Michael-addition mechanism. The introduction of a cationic group in two sensors efficiently avoided the interference of common cations in environmental samples. PVBTI and HPVBTI had high-selectivity to HSO3- over other anions and cations and they could detect HSO3- with the low detection limits of 13.3 nM and 26.7 nM, respectively. Their sensing mechanism was confirmed by H-1 NMR and LC-MS spectra. HSO3- was detected by two fluorescent sensors in tap water, lake water, river water, and paddy water with satisfactory results, suggesting that PVBTI and HPVBTI could be as the practical sensing platform for sensitive and selective analysis of HSO3- in the environment.