Melamine is a kind of small molecule compound, which has been illegally adulterated in dairy food because of the rich nitrogen content and stable chemical properties. Therefore, the detection of melamine is of great significance to food safety and human's health protection. Melamine can emit weak fluorescence, making it difficult to detect melamine directly. However melamine can significantly enhance the emission of the tetracycline-europium (EuTC) complex at a wavelength of 616 nm, hence this work uses EuTC complex as a fluorescent probe to detect melamine. According to the characterizations of absorption spectra, molecular electrostatic potential distribution and the time-resolved spectra, we speculated that tetracycline and melamine may form a complex through hydrogen bonding interaction, causing the melamine closer approach to Eu3+ and reducing the non-radiative energy loss of water molecules to EuTC complex, which significantly enhanced the fluorescence intensity of EuTC. The fluorescence intensity with melamine concentration in the range of 0.5~40 μM shows a good linear relationship, and the correlation coefficient is 0.9951 with the detection limit of 0.0785 μM, which shows a high sensitivity in detection of melamine. As far as we know, EuTC complex is the first time that has been used as a fluorescent probe to detect melamine, which provides a supplement and extension for the detection of melamine in fluorescence spectroscopy.

三聚氰胺是一种小分子化合物，因其含氮量丰富，化学性质稳定，被非法掺入乳制品中。因此，三聚氰胺的检测对食品安全和人类健康保护具有重要意义。三聚氰胺会发出微弱的荧光，因此很难直接检测三聚氰胺。然而，三聚氰胺可以显着增强四环素-铕 (EuTC) 复合物在 616 nm 波长处的发射，因此本工作使用 EuTC 复合物作为荧光探针来检测三聚氰胺。根据吸收光谱、分子静电势分布和时间分辨光谱的表征，我们推测四环素和三聚氰胺可能通过氢键相互作用形成络合物，导致三聚氰胺更接近Eu3+，减少了水分子对EuTC复合物的非辐射能量损失，显着增强了EuTC的荧光强度。三聚氰胺浓度在0.5~40 μM范围内荧光强度呈良好的线性关系，相关系数为0.9951，检出限为0.0785 μM，显示出对三聚氰胺检测的高灵敏度。据我们所知，EuTC复合物是首次作为荧光探针来检测三聚氰胺，为荧光光谱中三聚氰胺的检测提供了补充和延伸。三聚氰胺浓度在0.5~40 μM范围内荧光强度呈良好的线性关系，相关系数为0.9951，检出限为0.0785 μM，显示出对三聚氰胺检测的高灵敏度。据我们所知，EuTC复合物是首次作为荧光探针来检测三聚氰胺，为荧光光谱中三聚氰胺的检测提供了补充和延伸。三聚氰胺浓度在0.5~40 μM范围内荧光强度呈良好的线性关系，相关系数为0.9951，检出限为0.0785 μM，显示出对三聚氰胺检测的高灵敏度。据我们所知，EuTC复合物是首次作为荧光探针来检测三聚氰胺，为荧光光谱中三聚氰胺的检测提供了补充和延伸。