Fluorescent probes based on N-CQDs: For direct detection of food additives STPP and Al³

Sodium tripolyphosphate (STPP), as one of the many food additives, can cause gastrointestinal discomfort and a variety of adverse reactions when ingested by the human body, which is a great potential threat to human health. Therefore, it is necessary to develop a fast, sensitive and simple method to detect STPP in food. In this study, we synthesized a kind of nitrogen-doped carbon quantum dots (N-CQDs), and were surprised to find that the addition of STPP led to the gradual enhancement of the emission peaks of the N-CQDs, with a good linearity in the range of 0.067-1.96 μM and a low detection limit as low as 0.024 μM. Up to now, there is no report on the use of carbon quantum dots for the direct detection of STPP. Meanwhile, we found that the addition of Al³⁺ effectively bursts the fluorescence intensity of N-CQDs@STPP solution and has a good linear relationship in the range of 0.33-6.25 μM with a lower detection limit of 0.24 μM. To this end, we developed a fluorescent probe to detect STPP and Al³⁺. In addition, the probe was successfully applied to the detection of bread samples, which has great potential for practical application.