基于金纳米粒子团聚机理快速比色测定甲基硫菌灵

Rapid colorimetric detection of thiophanate-methyl based on the agglomeration mechanism of gold nanoparticles

[目的]基于金纳米粒子(gold nanoparticle,AuNPs)的团聚机理,建立一种直接、快速、可视化的甲基硫菌灵农药检测方法。[方法]在酸性条件下,甲基硫菌灵分子上的=O键和=S键质子化,形成-OH和-SH,甲基硫菌灵通过Au-S键连接到AuNPs表面,再通过分子间的氢键相互作用,使甲基硫菌灵分子间相互连接,从而引起AuNPs的团聚,溶液颜色由酒红色变成蓝黑色,AuNPs在525 nm处的吸光度强度相应减弱,通过比色分析法可以实现对甲基硫菌灵的检测。[结果]甲基硫菌灵在0.05~5 mg/L范围内与AuNPs的相对吸光强度呈现良好的线性关系,相关系数R2为0.9928,检测限为0.04 mg/L。在番茄样本中的加标回收率在82.0%~93.4%之间。[结论]该方法能满足蔬菜实际样品中甲基硫菌灵残留快速检测的需求。

[Aims]This study aims to develop a directly fast and visual approach for colorimetric detection of thiophanate-methyl pesticide based on the agglomeration mechanism of gold nanoparticles(AuNPs). [Methods]After protonation of thiophanate-methyl at the acidic conditions, the thiophanate-methyl can be connected to the surface of AuNPs through Au-S bonds. The thiophanate-methyl are interconnected by hydrogen bond. So that the AuNPs can aggregate. The color of the solution changed from wine red to blue black. And the absorbance intensity of AuNPs also weakened correspondingly. [Results]So an inverse relationship between the relative correlation intensity of AuNPs and thiophanate-methyl concentration in the range from 0.05 to 5 mg/L was found. The correlation coefficients and sensitivity of assay were 0.9928 and 0.04 mg/L, respectively. The recoveries from tomato samples spiked with different concentrations of thiophanate-methyl were in the range of 82.0-93.4%. [Conclusions]This assay can meet the requirement well of rapid detection of thiophanate-methyl residue in vegetable samples.