Universidade Federal Da Paraíba, Centro de Ciências Exatas e Da Natureza, Departamento de Química, 58051-900 João Pessoa, Paraíba, Brasil.
Spectrochim Acta A Mol Biomol Spectrosc. 2024 Nov 15;321:124669. doi: 10.1016/j.saa.2024.124669. Epub 2024 Jun 18.
The synthesis of carbon quantum dots (CQDs) using chemical precursors with different organic groups is a strategy to improve optical properties and expand applications in several fields of research such as Analytical Chemistry. Ascorbic acid and riboflavin are widely used in human food supplementation, making quality monitoring of these vitamin supplements relevant and necessary. In this work, disodium ethylenediaminetetraacetic, sodium thiosulfate and urea were applied to obtain CQDs through a single-step microwave-assisted synthesis. The CQDs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, infrared spectroscopy, zeta potential measurements, ultraviolet-visible spectroscopy and photoluminescence spectroscopy. The synthesized nanoparticles exhibited satisfactory and stable optical properties with luminescence at 430 nm, water solubility, and fluorescence quantum yield of 8.9 %. They were applied in the quantification of ascorbic acid and riboflavin in vitamin supplements. The fluorescence mechanisms observed were dynamic quenching for the CQDs/Cr(VI) sensor, followed by a return of fluorescence in the presence of ascorbic acid, and static quenching and inner filter effect in the interaction with riboflavin. Factorial designs 2 and 2 were used to optimize the analytical parameters. The CQDs/Cr(VI) sensor used in the determination of ascorbic acid, employing an on-off-on strategy, resulted in a linear range of 0.5 to 50 µg mL and a limit of detection of 0.15 µg mL. The ratiometric fluorescence used in the determination of riboflavin resulted in a linear range of 0.1 to 7 µg mL and a limit of detection of 0.09 µg mL. The analytical results for ascorbic acid were compared to the reference method of the Brazilian pharmacopeia, showing accuracy and precision according to the Brazilian Health Regulation Agency. Therefore, the synthesized CQDs were used to determine ascorbic acid and riboflavin in vitamin supplements, and the application of this nanomaterial can be expanded to different analytes and matrices, using simple and low-cost analysis techniques.
使用具有不同有机基团的化学前体制备碳量子点（CQDs）是一种改善光学性质并扩展在分析化学等多个研究领域应用的策略。抗坏血酸和核黄素广泛用于人类食品补充剂，因此对这些维生素补充剂的质量监测是相关且必要的。在这项工作中，采用乙二胺四乙酸二钠、硫代硫酸钠和尿素通过一步微波辅助合成来获得 CQDs。通过透射电子显微镜、X 射线光电子能谱、X 射线粉末衍射、红外光谱、zeta 电位测量、紫外-可见光谱和光致发光光谱对 CQDs 进行了表征。合成的纳米粒子表现出令人满意且稳定的光学性质，在 430nm 处具有发光、水溶性和荧光量子产率为 8.9%。它们被应用于维生素补充剂中抗坏血酸和核黄素的定量。观察到的荧光机制是 CQDs/Cr(VI)传感器的动态猝灭，随后在存在抗坏血酸时荧光恢复，以及与核黄素相互作用时的静态猝灭和内滤效应。因子设计 2 和 2 用于优化分析参数。用于抗坏血酸测定的 CQDs/Cr(VI)传感器采用开-关-开策略，线性范围为 0.5 至 50μgmL，检测限为 0.15μgmL。用于核黄素测定的比率荧光得到的线性范围为 0.1 至 7μgmL，检测限为 0.09μgmL。抗坏血酸的分析结果与巴西药典的参考方法进行了比较，根据巴西卫生监管机构的规定，结果显示出准确性和精密度。因此，合成的 CQDs 被用于测定维生素补充剂中的抗坏血酸和核黄素，并且可以使用简单且低成本的分析技术将这种纳米材料的应用扩展到不同的分析物和基质。
