In order to determine the concentration of melamine, nitrogen-doped carbon dots (NCDs) were synthesized in one step as a fluorescent probe. Uric acid and diethylenetriamine were used as carbon source and nitrogen source, respectively. The experimental results showed that the fluorescence of NCDs can be quenched by mercury ions (Hg²⁺). Due to the strong coordination affinity between the carbon-nitrogen heterocyclic of melamine and Hg²⁺, part of Hg²⁺ coordinated with melamine when melamine was mixed with Hg²⁺. Then, the fluorescence of the added NCDs was quenched by the remaining Hg²⁺. Therefore, the concentration of melamine could be determined. The results show that the method has high sensitivity in wide measuring range that the linear ranges are 50–400 μg/L and 800–2500 μg/L, and the R² is 0.997 and 0.988, respectively, with the limit of detection (LOD) of 21.76 μg/L. The NCDs are easy to fabricate, and the detection method is easy to implement. In this study, a new method for melamine detection was established, and the proposed method for melamine detection can provide some insights for food safety detection.

中文翻译：

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基于氮掺杂碳点荧光变化的三聚氰胺检测

为了确定三聚氰胺的浓度，一步合成了氮掺杂的碳点（NCD）作为荧光探针。尿酸和二亚乙基三胺分别用作碳源和氮源。实验结果表明，NCDs的荧光可以被汞离子（Hg ²⁺）猝灭。由于三聚氰胺的碳氮杂环与Hg ²⁺之间具有很强的配位亲和力，当三聚氰胺与Hg ²⁺混合时，部分Hg ²⁺与三聚氰胺配位。然后，添加的NCD的荧光被剩余的Hg ²⁺淬灭。。因此，可以确定三聚氰胺的浓度。结果表明，该方法在测量范围宽高灵敏度，线性范围是50-400  μ g / L和800-2500  μ克/升，且- [R ²分别为0.997和0.988，与检测限的21.76（LOD）  μ克/升。NCD易于制造，并且检测方法易于实施。本研究建立了一种新的三聚氰胺检测方法，该方法可为食品安全检测提供一些见识。