Orange Luminescent Carbon Dots as Fluorescent Probe for Detection of Nitrite

Orange luminescent nitrogen doped carbon dots (N-CDs) were prepared via one-step hydrothermal treatment with p-phenylenediamine and citric acid as precursors. The morphology and optical properties of the N-CDs were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectra (FTIR), ultraviolet-visible absorption spectroscopy (UV-vis) and fluorescence (FL) spectroscopy. The synthesized N-CDs had an extreme small size ((1.62 ± 0.35) nm), good water solubility and excellent fluorescent stability. The addition of nitrite (NO2−) caused fluorescence increase of N-CDs. Based on this phenomenon, a new fluorescence analysis method for detecting NO2− was established. Moreover, the possible fluorescence enhancement mechanism was proposed. The constructed fluorescence sensing system was applied to the detection of NO2− in sausage, pickle and tap water samples with recoveries from 97.1% to 104.5% and relative standard deviations (RSDs) of 1.1% to 3.5%.