ZnS quantum dots-based fluorescence spectroscopic technique for the detection of quercetin.

Water-soluble ZnS quantum dots (QDs) modified by mercaptoacetic acid (MPA) were used to determinate quercetin in aqueous solutions by a fluorescence spectroscopic technique. The results showed that the fluorescence of the modified ZnS QDs could be quenched by quercetin effectively in physiological buffer solution. The optimum fluorescence intensity was found to be at incubation time 10 min, pH 7.0 and temperature 25°C. Under the optimal conditions, the detection limit of quercetin was 5.71 × 10(-7) mol/L. Moreover, the quenching mechanism was discussed to be a static quenching procedure, which was proved by the quenching rate constant Kq (1.14 × 10(13) L/mol/s).