Design and synthesis of surface-decorated zinc-doped carbon quantum dots as fluorescent probes for tartrazine detection in real food samples exploiting the inner filter effect mechanism

We developed a rapid and sensitive method for detecting tartrazine (Tar), a common food colorant, using zinc-doped carbon quantum dots (Zn-doped CQDs). Synthesized from biowaste pigeon pod shells and zinc acetate, the Zn-doped CQDs exhibited a high quantum yield (47.63%) and were characterized by photo-stability, non-toxicity, and water solubility. The inner filter effect (IFE) allows selective attenuation of Zn-doped CQD fluorescence by Tar, enabling precise detection. The approach obtains a low detection limit of 20.35 ng/mL and a quantification limit of 61.69 ng/mL within a linear range of 0–100 ng/mL under optimal conditions when employing the Box-Behnken statistical design. The approach demonstrates excellent reproducibility, successfully detecting Tar in real food samples with recovery rates ranging from 89% to 102.2%. This high accuracy confirms the sensor's reliability and effectiveness in practical applications. This cost-effective and rapid technique presents a promising solution for monitoring Tar levels in food products.