Determination of free sulfite in food samples with a novel fluorescent probe as gas-diffusion microextraction acceptor phase

Abstract

Excessive residues of sulfite (SO32−) have negative effects on human health; thus, it is important to monitor SO32− levels in food samples and living cells. In this study, a novel fluorescent probe (E)-4-(2-(2-(7-(diethylamino)-2-oxo-2H-chromen-3-yl) vinyl) −1,1-dimethyl-1H-benzo[e]indol-3-ium-3-yl) butane-1-sulfonate (probe 1) was prepared. This probe was based on a conjugated coumarin–benzindolium system that was detected to exhibit high-response speed and selectivity and sensitivity towards free bisulfite/sulfite (HSO3−/SO32−) anions. Probe 1 was also highly compatible with gas-diffusion microextraction (GDME) because of its good water solubility, reaction rapidness and ratiometric signal response. Extraction and detection tasks could be completed within 30 min under the selected experimental conditions. The developed GDME-FL method showed adequate limits of detection (4.9 μM) and quantification (16.2 μM) for food analysis. The applications of this method for the detection of free HSO3− in product samples were investigated thoroughly. In addition, we successfully applied probe 1 to image lens cleaning paper, onion, Daphnia magna and HeLa cells. Therefore, probe 1 has a promising application potential for measuring the HSO3−/SO32− content of real food samples.