A ratiometric fluorescence sensor based on Mn doped ZnS QDs for highly selective detection of ascorbic acid

A ratiometric fluorescence sensor based on Mn doped ZnS QDs was designed to detect ascorbic acid with highly selectivity . The synthesized Mn doped ZnS QDs showed a new luminescence performance due to new electron hole recombination center formed in the nanocrystals . The dopant-related luminescence of Mn 2+ appeared at 590 nm, and the best dopant-related luminescence effect can be obtained by changing the doping amount of Mn 2+ during the synthesis process. Ascorbic acid (AA) is known to be oxidized by Fe 3+ to generate dehydroascorbic acid (DHAA). If DHAA combined with o-phenylenediamine (OPD), a fluorescent product quinoxaline DFQ was obtained. Mixing DFQ with Mn doped ZnS QDs , two fluorescence emission appeared at 434 nm and 590 nm. After optimizing the concentration of Fe 3+ and OPD, solution pH and reaction time, the results showed a good linear relationship between AA and the ratio of F 434 /F 590 . The linear range of this ratiometric fluorescence sensor for detection of ascorbic acid were 0.5–40 μmol·L −1 and 40–80 μmol·L −1 , and the detection limit was low to 0.21 μmol·L −1 . Compared with the single fluorescence analysis method for AA detection, this work has stronger anti-interference and greatly improved sensitivity and selectivity by ratiometric fluorescence.