银纳米-泡沫铜基底的透射-表面增强红外光谱法对福美双的检测

表面增强红外光谱(SEIRAS)是一种极具潜力的分析技术,近年来被广泛应用于诸多领域。SEIRAS技术的关键在于具有红外增强效应的基底,但目前已有的SEIRAS基底制备的成本、步骤和耗时等都还有待优化。金属材料由于其不透光性,通常难以用作透射模式(T-SEIRAS)基底的衬底,本研究创新性地使用具有三维孔隙结构的泡沫铜材料作为衬底,基于置换反应在泡沫铜上负载银纳米粒子,研发出一种快速、简便、低成本的T-SEIRAS基底制备方法。优化了银离子溶液浓度、表面活性剂用量、反应时间等主要影响因素,结果表明:硝酸银(0.2 mmol·L^-1)用量为10 mL,聚乙烯吡咯烷酮(PVP)(0.05 g·mL^-1)用量为2 mL,反应时间为30 s时,基底红外增强效果最好。通过扫描电镜(SEM)、X射线光电子能谱(XPS)对SEIRAS透射基底的表征,表明从几十到一百纳米尺度的银纳米被成功负载于泡沫铜衬底上。优化制备的银纳米-泡沫铜SEIRAS透射基底可对探针分子11-巯基十一烷酸(MUA)及福美双农药产生明显的红外信号增强,对MUA在1689 cm^-1处的增强达32.7倍,对福美双在1371 cm^-1处的增强达2.9倍。分别考察了福美双1236,1371和1495 cm^-1处的吸收信号强度与浓度的线性拟合情况,1236 cm^-1处的线性最优,相关系数为0.923。该基底对福美双的检出限为0.024 mg·mL^-1。研究结果为快速、简便制备SEIRAS透射基底提供了新方案,为福美双等有机污染物的现场应急快速检测提供了新思路。

Transmission Surface Enhanced Infrared Spectroscopy Based on AgNPs-Cu Foam Substrate for the Detection of Thiram Pesticides

Surface enhanced infrared absorption spectroscopy is a promising analytical technique and has been widely used in many fields recently.The key to the SEIRAS spectroscopy lies in the preparation of substrate with infrared enhancement effect.However,the cost,process steps and consuming time of the SEIRAS substrate preparation method have yet to be optimized.Metal materials are usually difficult to be used as support materials for transmission SEIRAS(T-SEIRAS)substrates due to its opacity.In this study,we innovatively used copper foam materials with a three-dimensional pore structure as support materials and loaded silver nanoparticles on copper foam based on improved displacement reaction principle.A fast,simple and low-cost method for preparing T-SEIRAS substrate was developed in this research.The dosage of surfactant and reaction time were optimized.The results showed that when the dosage of silver nitrate(0.2 mmol·L^-1)was 10 mL,the dosage of Polyvinylpyrrolidone(PVP)(0.05 g·mL^-1)was 2 mL and the reaction time was 30 s,the infrared enhancement effect of the substrate was optimum.The characterization of SEIRAS substrate by scanning electron microscopy(SEM)and X ray photoelectron spectroscopy(XPS)showed that silver nanoparticles,from tens to one hundred nanometer,were successfully loaded on the Cu foam.The optimized AgNPs-Cu foam SEIRAS transmission substrate could significantly enhance the infrared signal of the probe molecule 11-mercaptoundecanoic acid(MUA)and the thiram pesticide.Its enhancement multiple of MUA at 1689 cm^-1 is 32.7 times,and 2.9 times of thiram at 1371 cm^-1.Linear fitting of absorption signal intensity at 1236,1371,1495 cm^-1 and the concentration of thiram was investigated.Linear optimum was found at 1236 cm^-1 with a correlation coefficient of 0.923.The detection limit of thiram was 0.024 mg·mL^-1.The experimental results of this study provide a new scheme for the rapid and simple preparation of SEIRAS transmission substrate and a new idea for the rapid on-site detection of thiram pesticide.