Institute of Chemistry, Saint-Petersburg University, Saint Petersburg State University, SPbSU, SPbU, 7/9 Universitetskaya nab., St. Petersburg, 199034, Russia.
Institute of Chemistry, Saint-Petersburg University, Saint Petersburg State University, SPbSU, SPbU, 7/9 Universitetskaya nab., St. Petersburg, 199034, Russia.
Anal Chim Acta. 2024 Dec 15;1332:343356. doi: 10.1016/j.aca.2024.343356. Epub 2024 Oct 26.
Deep eutectic solvents (DES) have emerged as effective solvents that address many challenges in analytical chemistry, particularly in microextraction. However, until now, their use has been primarily focused on extraction processes. This has significantly limited their application in analytical chemistry, especially in flow analysis, where the high viscosity of DES has made their use difficult.
This paper presents a novel DES-based liquid-liquid microextraction approach for the separation and determination of trace metals in foods using an automated flow analysis system. In this study, a DES composed of thymol and thionalide was first prepared and thoroughly characterized by spectroscopic (IR, NMR) and differential scanning calorimetry techniques. The COSMO-SAC model was employed to predict the solubility of metal salts (Cu, Cd, Pb, and Hg) in the new DES. The solvent was applied to glass fiber as a stationary phase in an extraction column in a flow analysis. After microwave digestion of food samples, metals were extracted by this DES in an automated mode and subsequently eluted with an aqueous thiourea solution. The procedure demonstrated limits of detection (LOD) of 6 μg kg for mercury, 4 μg kg for copper, 6 μg kg for lead and 0.6 μg kg for cadmium.
This study represents the first application of a DES-based stationary phase in automated flow analysis, significantly enhancing extraction efficiency. The procedure enables precise and reliable determination of trace metals in food products, aligning with green chemistry principles by minimizing waste.
深共熔溶剂 (DES) 作为一种有效的溶剂已经出现，解决了分析化学中的许多挑战，特别是在微萃取中。然而，到目前为止，它们的应用主要集中在萃取过程中。这极大地限制了它们在分析化学中的应用，特别是在流动分析中，DES 的高粘度使得它们的使用变得困难。
本文提出了一种新的基于 DES 的液-液微萃取方法，用于使用自动化流动分析系统分离和测定食品中的痕量金属。在本研究中，首先制备了由百里酚和硫代苯甲酰胺组成的 DES，并通过光谱（IR、NMR）和差示扫描量热法技术对其进行了彻底表征。采用 COSMO-SAC 模型预测了金属盐（Cu、Cd、Pb 和 Hg）在新 DES 中的溶解度。该溶剂被应用于玻璃纤维作为萃取柱中的固定相在流动分析中。在对食品样品进行微波消解后，这些金属以自动化模式被这种 DES 萃取，然后用硫脲水溶液洗脱。该程序显示汞的检测限 (LOD) 为 6μg kg，铜的检测限为 4μg kg，铅的检测限为 6μg kg，镉的检测限为 0.6μg kg。
本研究代表了基于 DES 的固定相在自动化流动分析中的首次应用，显著提高了萃取效率。该程序能够精确可靠地测定食品中痕量金属，符合绿色化学原则，最大限度地减少废物。
