Construction of a silver-doped carbon dots-based fluorescent probe for trace tartrazine analysis in foodstuffs

In this study, we report the synthesis of silver-doped yellow-green fluorescent carbon dots (Ag-YGCDs) using a facile solvothermal method with L-citrulline, phthalamide, and silver nitrate as precursors. The Ag-YGCDs exhibited a maximum emission at 530 nm when excited at 450 nm, with a fluorescence quantum yield of 5.9 %. Paramountly, the Ag-YGCDs exhibited exceptional fluorescence quenching performance with high sensitivity and selectivity towards tartrazine, enabling a novel fluorescent probe for trace tartrazine detection. A wide linear response range spanning 0.10-45 μM was exhibited by the probe for tartrazine quantification, while maintaining a detection limit as low as 27 nM. The constructed method was then successfully applied in various food matrices, including cocktails, juices, energy drinks, hard candies, gummy candies, and chocolate confectioneries. The recovery rates ranged from 91.4 % to 120 %, with relative standard deviations between 1.1 % and 3.7 %, confirming the method's reliability and accuracy.