Department of Physical and Analytical Chemistry, Faculty of Experimental Sciences, University of Jaén, Campus Las Lagunillas, Jaén, Spain.
Luminescence. 2019 Aug;34(5):460-464. doi: 10.1002/bio.3592. Epub 2019 Jan 16.
Consumption of herbal teas, infusions and other plant-related products has always been popular due to the related health benefits. However, the safety of these products needs to be assessed, for example monitoring the potential presence of contaminants such as pesticides. In this paper, we report an analytical method for determining three neonicotinoid insecticides - thiacloprid, thiamethoxam, and imidacloprid - that are widely used worldwide. This method is based on quenching by analytes of the luminescence signal of terbium ions. Terbium presents a time-resolved luminescence signal at 256/545 nm/nm, which is quenched by the presence of low concentrations of the selected analytes. Detection limits of 0.1, 0.2 or 0.75 μg ml were obtained for thiamethoxam, thiacloprid and imidacloprid, respectively. Recovery experiments in different teas (green tea, black tea, chamomile, peppermint) were performed at concentrations lower than the maximum residue limits established by the European Union and the Codex Alimentarius for tea samples. In all cases, satisfactory recovery yields were observed, and the results were compared with a chromatographic reference method. The proposed method therefore proved suitable for quantifying these insecticides, fulfilling the current legislation.
由于相关的健康益处，草药茶、浸剂和其他植物相关产品的消费一直很受欢迎。然而，这些产品的安全性需要进行评估，例如监测潜在的污染物（如农药）的存在。在本文中，我们报告了一种用于测定三种新烟碱类杀虫剂——噻虫啉、噻虫嗪和吡虫啉——的分析方法，这些杀虫剂在全球范围内广泛使用。该方法基于分析物对铽离子荧光信号的猝灭作用。铽在 256/545nm/nm 处呈现出时间分辨的荧光信号，而所选分析物的低浓度会使其猝灭。噻虫嗪、噻虫啉和吡虫啉的检测限分别为 0.1、0.2 和 0.75μg/ml。在浓度低于欧盟和食品法典委员会为茶叶样品设定的最大残留限量的情况下，在不同的茶（绿茶、红茶、洋甘菊、薄荷）中进行了回收实验。在所有情况下，均观察到令人满意的回收率，并且将结果与色谱参考方法进行了比较。因此，该方法适用于定量这些杀虫剂，符合现行法规。
