Co-Doped S, N-Carbon Dots and its Fluorescent Film Sensors for Rapid Detection of Cr (VI) and Ascorbic Acid

Abstract In this work, an “on-off-on” fluorescent sensor of sulfur and nitrogen co-doped carbon dots (S, N-CDs) was explored for the identification of Cr (VI) and ascorbic acid (AA), which showed a good selectivity and anti-interfere ability to more than 30 interfering substances. We also realized the fluorescence recognition in liquid and solid media under optimal conditions based on the internal filtration effect (IFE). In the liquid medium, the linear dynamic range of Cr (VI) was 0.03-50 μM and the limit of detection (LOD) was 21.14 nM. The linear detection range and the LOD of AA were 1-1000 μM and 0.28 μM, respectively. For solid-phase detection, we embed S, N-CDs into polyvinyl alcohol (PVA) to synthesize a visual fluorescent film sensor, which was irradiated by 365 nm ultraviolet light, for easily and accurately detecting Cr (VI) and AA on-site. The ranges of linearity were 0.1-50 μM and 10-500 μM, respectively, and the LODs were 92.48 nM and 6.99 μM, respectively. This is of great significance such as low cost, user-friendliness, and fast response for the analysis of environmental water samples.