Simultaneous qualitative detection of ClO− and NO2− based on time differentiation with a Fe2+@N-CDs probe

A sensitive and selective fluorescent nitrogen-doped carbon dots (N-CDs) probe was synthesized by using glucosamine as a single reagent in a one-step hydrothermal treatment and was also characterized by UV-Vis spectrophotometer, fluorescence spectrophotometer, transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectrometer, X-ray diffractometer (XRD), and X-ray photoelectron spectrometer (XPS). N-CDs exhibited a superior water solubility and an excellent fluorescence characteristic and was used as a fluorophore to measure ClO− and NO2− based on their oxidation in the presence of Fe2+. The quenching mechanism of ClO− and NO2− to the system probe of Fe2+@N-CDs was also demonstrated. The detection limit of the probe to ClO− was 0.75 μM in the linear range of 1 to 17.5 μM and for NO2− was 0.85 μM with the linear range of 2.5 to 20 μM. Speciation analysis of ClO− and NO2− could be distinguished due to the different reactive response time to the system probe of Fe2+@N-CDs, and the accuracy was further confirmed by detecting them in actual river water and tap water samples.