Nitrogen doped carbon dots for sensitive detection of permanganate and hydrazine by a fluorescence off-on strategy

In this work, nitrogen doped carbon dots (N-CDs) were synthesized through one step hydrothermal reaction using ginkgo fruit and ethylenediamine as precursors. The luminescence of the N-CDs was speculated to be related with the electron transition of C=N bonds derived from grafting amines groups onto the the functional groups on the surface. MnO4- could selectively quench the fluorescence of N-CDs due to the formation of N-CDs-MnO4- complex on the surface. The linear relation between quenching efficiency and MnO4- concentration ranged from 1 to 60 mu mol/L with a detection limit of 0.64 mu mol/L. In the presence of hydrazine (N2H4), MnO4- was reduced to Mn2+ and the fluorescence of carbon dots was recovered. Results indicated that it can act as a secondary fluorescent probe for quantitative analysis of N2H4 in the scope of 0.5 to 14 mu mol/L with a detection limit of 0.384 mu mol/L. The N-CDs were successfully applied to analyze MnO4- and N2H4 in real samples with satisfactory recoveries (97.34-104.0% and 97.56-104.4%, respectively), implying good applicability in practical analysis.