Laboratoire de Chimie Physique et Microbiologie pour les Matériaux et l'Environnement (LCPME), UMR 7564, CNRS - Université de Lorraine , 405 Rue de Vandoeuvre, 54600 Villers-lès-Nancy, France.
ACS Sens. 2018 Feb 23;3(2):484-493. doi: 10.1021/acssensors.7b00920. Epub 2018 Jan 30.
An electrochemical method was developed for rapid and sensitive detection of the herbicide paraquat in aqueous samples using mesoporous silica thin film modified glassy carbon electrodes (GCE). Vertically aligned mesoporous silica thin films were deposited onto GCE by electrochemically assisted self-assembly (EASA). Cyclic voltammetry revealed effective response to the cationic analyte (while rejecting anions) thanks to the charge selectivity exhibited by the negatively charged mesoporous channels. Square wave voltametry (SWV) was then used to detect paraquat via its one electron reduction process. Influence of various experimental parameters (i.e., pH, electrolyte concentration, and nature of electrolyte anions) on sensitivity was investigated and discussed with respect to the mesopore characteristics and accumulation efficiency, pointing out the key role of charge distribution in such confined spaces on these processes. Calibration plots for paraquat concentration ranging from 10 nM to 10 μM were constructed at mesoporous silica modified GCE which were linear with increasing paraquat concentration, showing dramatically enhanced sensitivity (almost 30 times) as compared to nonmodified electrodes. Finally, real samples from Meuse River (France) spiked with paraquat, without any pretreatment (except filtration), were analyzed by SWV, revealing the possible detection of paraquat at very low concentration (10-50 nM). Limit of detection (LOD) calculated from real sample analysis was found to be 12 nM, which is well below the permissible limits of paraquat in drinking water (40-400 nM) in various countries.
电化学方法用于快速和灵敏地检测水样中的除草剂百草枯，使用介孔硅薄膜修饰玻碳电极（GCE）。通过电化学辅助自组装（EASA）将垂直排列的介孔硅薄膜沉积在 GCE 上。循环伏安法显示出对阳离子分析物（排斥阴离子）的有效响应，这要归功于带负电荷的介孔通道表现出的电荷选择性。然后使用方波伏安法（SWV）通过其单电子还原过程来检测百草枯。研究了各种实验参数（即 pH 值、电解质浓度和电解质阴离子的性质）对灵敏度的影响，并根据介孔特性和积累效率进行了讨论，指出在这些受限空间中电荷分布对这些过程的关键作用。在介孔硅修饰的 GCE 上构建了百草枯浓度从 10 nM 到 10 μM 的校准曲线，这些曲线随百草枯浓度的增加呈线性增加，与非修饰电极相比，灵敏度显著提高（几乎提高了 30 倍）。最后，用 SWV 分析了来自法国默兹河的实际样品，未进行任何预处理（除过滤外），表明可以在非常低的浓度（10-50 nM）下检测到百草枯。从实际样品分析中计算出的检测限（LOD）为 12 nM，远低于各国饮用水中百草枯的允许限量（40-400 nM）。
