Concentration dependent color-tunable N, Br co-doped carbon quantum dots as fluorescent probes for the sensitive detection of sunset yellow in foodstuff

Sunset Yellow (SY), a widely used food additive, poses health risks when consumed in excess. Therefore, it is necessary to develop method for the detection of SY in different foodstuffs. In this study, we synthesized concentration-tunable nitrogen and bromine co-doped functional carbon quantum dots (CQDs) through a simple solvothermal method utilizing Tetrabromophthalic anhydride and Ethylenediamine. The synthesized CQDs were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–Vis absorption spectra and fluorescence spectrophotometer. Notably, the CQDs exhibited a high fluorescence quantum yield of 25.85 %, and their fluorescence was effectively quenched by SY, thus enabling the development of a fluorescent probe for SY detection. Consequently, a novel fluorescent probe was established with a linear range of 0.03–100 μmol/L and a limit of detection (LOD) of 0.01 μmol/L. This probe was validated for SY quantification in various food samples, achieving recovery rates between 98.27 % and 108.67 %, with a relative standard deviation (RSD) of less than 3.76 %, indicating promising application prospects.