Department of Applied Chemistry, China Agricultural University, Beijing, China.
Luminescence. 2023 Oct;38(10):1729-1737. doi: 10.1002/bio.4549. Epub 2023 Aug 22.
Glyphosate, the most used herbicide in the world, has a residue problem that cannot be ignored. However, glyphosate itself does not have fluorescence emission and lacks the conditions for fluorescence detection. In this work, a rapid and selective fluorescence detection method of glyphosate was designed by an 'on-off-on' fluorescent switch based on a luminous covalent organic framework (L-COF). Only the fixed concentration of Fe as an intermediate could trigger the fluorescent switch and no incubation step was required. The proposed method showed good accuracy with a correlation coefficient of 0.9978. The method's limits of detection and quantitation were 0.88 and 2.93 μmol/L, which were lower than the maximum allowable residue limits in some regulations. Environmental water samples and tomatoes were selected as actual samples to verify the application in a complex matrix. A satisfactory mean recovery from 87% to 106% was gained. Furthermore, Fe could induce fluorescence quenching of L-COF through the photo-induced electron transfer (PET) effect, while the addition of glyphosate could block the PET effect to achieve detection. These results demonstrated the proposed method had abilities to detect glyphosate and broaden the application of L-COF.
草甘膦是世界上使用最广泛的除草剂，其残留问题不容忽视。然而，草甘膦本身没有荧光发射，缺乏荧光检测的条件。在这项工作中，基于发光共价有机框架（L-COF）设计了一种基于“开-关-开”荧光开关的草甘膦快速选择性荧光检测方法。只有固定浓度的 Fe 作为中间体能触发荧光开关，且不需要孵育步骤。该方法的相关系数为 0.9978，具有良好的准确性。该方法的检出限和定量限分别为 0.88 和 2.93μmol/L，低于某些法规中规定的最大允许残留限量。选择环境水样和西红柿作为实际样品来验证在复杂基质中的应用，获得了 87%至 106%的满意平均回收率。此外，Fe 可以通过光诱导电子转移（PET）效应诱导 L-COF 的荧光猝灭，而添加草甘膦可以阻断 PET 效应以实现检测。这些结果表明，该方法具有检测草甘膦的能力，并拓宽了 L-COF 的应用。
