Highly efficient N-doped carbon dots for ultrasensitive and selective detection of picric acid in explosive residues

A new variety of nitrogen-doped carbon dots (NCDs) was produced using a hydrothermal synthesis method, based on propanedioic acid and barbituric acid as the sources of carbon and nitrogen. The NCDs were analyzed by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Zeta Potential，X-ray Diffraction(XRD)，Thermogravimetry-Derivative Thermogravimetry(TG-DTG)，Fourier transform infrared spectroscopy (FTIR) and Fluorescence Lifetime. The characterization results indicate that NCDs possess an average diameter of approximately 2.35 nm, and blue fluorescence is visualized under UV light irradiation, with a high fluorescence quantum yield of 31.5 %. The NCDs demonstrate selective recognition capabilities for picric acid (PA). The fluorescence intensity of NCDs correlated linearly with the concentration of PA within the range of 0 to 3 μmol/L (y = 0.14× + 0.0047, R² = 0.9954, the limit of detection (LOD) was 0.24 μmol/L). The NCDs had been effectively been utilized for the quantitative determination of PA in simulated explosive dust and real-case samples, resulting in satisfactory recovery percentages. The proposed method was characterized by its strong specificity, rapid response time, high sensitivity, and minimal interference from structurally similar compounds, demonstrating its potential for rapid and visual detection of PA in explosive residues.