Highly Fluorescent Terbium-Doped Graphene Quantum Dots (Tb-GQD) for Rapid and Selective Detection of Tartrazine in Food Matrices.

Terbium-doped graphene quantum dots (Tb-GQDs) were synthesized using carbonization and surface coordination and subsequently used as efficient fluorescent probes for the quantitative and selective determination of tartrazine in food samples. The doping of terbium enhanced the photostability of GQDs. Photoluminescence emission spectra revealed that the fluorescence of Tb-GQDs was effectively quenched by increasing concentrations of tartrazine, which was attributed to a combination of static quenching and the inner filter effect (IFE). Under optimized conditions, the Tb-GQD probe showed a linear response with a detection limit of 6.7 nM. Tb-GQDs functioned as effective sensor platforms for the selective detection of tartrazine. Analytical studies using commercial food samples demonstrated recovery rates ranging from 97.4 to 101.5%, confirming the reliability and practical applicability of the proposed method. Because of their straightforward synthesis, rapid response, and high sensitivity, Tb-GQDs show strong potential for real-time monitoring of synthetic food colorants such as tartrazine.