Department of Chemistry, Federal University of Viçosa, Viçosa, MG 36570-900, Brazil.
Department of Chemistry, Federal University of Viçosa, Viçosa, MG 36570-900, Brazil.
Ecotoxicol Environ Saf. 2021 Apr 15;213:112043. doi: 10.1016/j.ecoenv.2021.112043. Epub 2021 Feb 13.
We describe a green new method for the synthesis of water-soluble photoluminescent carbon dots (CDs) that were functionalized with methimazole (MTZ) and applied to determine Hg based on the fluorescence extinction. Starch obtained from rice was used as a natural source for the production of CDs by hydrothermal treatment. Also, it was proposed a factorial design to optimize the parameters for CD synthesis and the results showed that the luminescence intensity is a function of temperature and not of the heating time in the hydrothermal process. The synthesized CDs were characterized using fluorescence techniques, Fourier transform infrared spectroscopy (FTIR), and UV-Vis spectroscopy. Through transmission electron microscopy (TEM) and dynamic light scattering (DLS), it was found the formation of CDs on a nanometer scale with an average size of 11 nm. The functionalization with MTZ, eliminated all interferences from other metals, indicating a selective response to Hg ions. The method was applied to Hg determination in waters. Under optimal conditions, was obtained a limit of detection of 1.8 × 10 mol L with a linear range from 3.3 × 10 to 50.0 × 10 mol L. Therefore, the proposed method can be considered a simple, selective, and precise alternative that minimizes the number of reagents used for Hg determination in natural waters, and can be applied on a large scale in environmental analyzes.
我们描述了一种绿色的新方法，用于合成水溶性发磷光的碳点（CDs），这些碳点用甲巯咪唑（MTZ）功能化，并应用于基于荧光消光的 Hg 测定。我们使用大米中的淀粉作为天然来源，通过水热处理来生产 CDs。此外，我们还提出了一种析因设计来优化 CD 合成的参数，结果表明，在水热过程中，发光强度是温度的函数，而不是加热时间的函数。通过荧光技术、傅里叶变换红外光谱（FTIR）和紫外-可见光谱对合成的 CDs 进行了表征。通过透射电子显微镜（TEM）和动态光散射（DLS），发现形成了纳米级的 CDs，平均尺寸为 11nm。用 MTZ 功能化消除了其他金属的所有干扰，表明对 Hg 离子有选择性响应。该方法应用于水样中 Hg 的测定。在最佳条件下，检测限为 1.8×10 mol L，线性范围为 3.3×10 至 50.0×10 mol L。因此，该方法可以被认为是一种简单、选择性好且精确的方法，它最大限度地减少了用于测定天然水样中 Hg 的试剂数量，并可在环境分析中大规模应用。
