State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science & Technology, Anhui Agricultural University, Hefei 230036, China.
Anhui Public Inspection Research Institute Co Ltd, Hefei 230001, China.
Food Chem. 2022 Dec 15;397:133790. doi: 10.1016/j.foodchem.2022.133790. Epub 2022 Jul 27.
The higher extraction efficiency of analytes is crucial for developing immunoassays with high accuracy. Here, we evaluated the extraction efficiency of neonicotinoids in tea samples in terms of grinding degrees, extraction solvents types and contents. Fragments for fresh tea leaves (1 g, 5-10 mm) or tea powder (1 g, 35 mesh) for commercial tea was extracted with 100 % methanol. The extraction (1 mL) was diluted 10-fold with buffer solution, and then submitted to gold nanoparticles-based lateral flow immunoassay. This optimal extraction protocol exhibited a higher extraction efficiency (72.4-99.3 %) for the positive neonicotinoids samples. The cut-off values of lateral flow immunoassay were 0.325 or 0.65 μg/g, 0.3 or 0.45 μg/g, 0.3 or 0.45 μg/g, 0.03 or 0.06 μg/g for thiamethoxami, clothianidin, acetamiprid and midacloprid in fresh tea leaves and commercial tea. In summary, this proposed lateral flow immunoassay can be used as the point-of-needs analysis method for four neonicotinoids in tea.
对于开发具有高精度的免疫分析方法，分析物的高提取效率至关重要。在这里，我们从研磨程度、提取溶剂类型和含量等方面评估了茶样中新型烟碱类农药的提取效率。对于新鲜茶叶（1 g，5-10 mm）或商用茶叶的茶粉（1 g，35 目），用 100%甲醇进行提取。提取液（1 mL）用缓冲溶液稀释 10 倍，然后进行基于金纳米粒子的侧向流动免疫分析。该最佳提取方案对阳性新型烟碱类农药样品的提取效率更高（72.4-99.3%）。对于新鲜茶叶和商用茶叶中的噻虫嗪、噻虫胺、乙酰甲胺磷和吡虫啉，侧向流动免疫分析的截止值分别为 0.325 或 0.65 μg/g、0.3 或 0.45 μg/g、0.3 或 0.45 μg/g、0.03 或 0.06 μg/g。总之，该拟议的侧向流动免疫分析可作为茶中四种新型烟碱类农药的现场即时分析方法。
