Malathion is one of the commonly used organophosphate pesticides known to attack the central nervous system, posing a risk to humans and other animals upon exposure. The surface enhanced Raman spectroscopy (SERS) has been identified as an indispensable tool for chemical and biomolecular sensing. In this work, the facile fabrication of activated carbon (AC)-based colloidal SERS active substrate dubbed AC@AgNPs was designed by trapping AgNPs on the surface of AC for detection of varying concentrations of malathion. Apart from the higher concentrations of malathion, the rest of the normal Raman spectra of malathion standard solutions exhibited weak Raman signals. The intensity of peaks for 0.47 mg L⁻¹ were nearly non-existent which is an indication that the malathion pesticide could only be detected up to 0.95 mg L⁻¹ when using silica wafer. On the contrary, all the SERS spectra of malathion in wheat extracts adsorbed on AC@AgNPs substrate exhibited strong Raman signals. Quantitative analysis of malathion was performed by regression models developed using PLSR built with the raw spectra (no pretreatment), SNV-PLSR, and SNV-CARS-PLSR. The model with the most remarkable performance was established by using SNV-PLSR with r = 0.9869 and RPD = 4.61. This research shows that the proposed method can rapidly detect malathion residues in wheat, suggesting that it could be adopted for production process monitoring of other related food products to guarantee their safety for human and animal consumption.

中文翻译：

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活性炭@银纳米颗粒缀合物作为 SERS 底物，用于捕获马拉硫磷分析物分子以进行 SERS 检测

马拉硫磷是一种常用的有机磷农药，已知会攻击中枢神经系统，接触后对人类和其他动物构成风险。表面增强拉曼光谱（SERS）已被认为是化学和生物分子传感不可或缺的工具。在这项工作中，通过将 AgNP 捕获在活性炭 (AC) 的表面上，设计了一种名为 AC@AgNPs 的基于活性炭 (AC) 的胶体 SERS 活性基质，用于检测不同浓度的马拉硫磷。马拉硫磷标准溶液的正常拉曼光谱除马拉硫磷浓度较高外，其余部分均表现出较弱的拉曼信号。^{0.47 mg L -1}的峰强度几乎不存在，这表明使用二氧化硅晶片时只能检测到0.95 mg L ^{-1的马拉硫磷农药。}相反，AC@AgNPs 基质上吸附的小麦提取物中马拉硫磷的所有 SERS 光谱均表现出强烈的拉曼信号。马拉硫磷的定量分析是通过使用原始光谱（无预处理）、SNV-PLSR 和 SNV-CARS-PLSR 构建的 PLSR 开发的回归模型进行的。性能最显着的模型是使用SNV-PLSR建立的，r  = 0.9869，RPD = 4.61。本研究表明，该方法可以快速检测小麦中的马拉硫磷残留，表明该方法可用于其他相关食品的生产过程监测，以保证人类和动物食用的安全。