Yan Fei, He Yayun, Ding Longhua, Su Bin
Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310058, China.
Anal Chem. 2015 Apr 21;87(8):4436-41. doi: 10.1021/acs.analchem.5b00433. Epub 2015 Apr 3.
The rapid and sensitive detection of nitroaromatic compounds is of great significance for human health, the environment, and public security. The present work reports on the extraction and electrochemical analysis of trace nitroaromatic compounds, such as explosives and organophosphate pesticides (OPs), using the indium tin oxide (ITO) electrodes modified with a highly ordered and aligned binary assembly of silica mesochannels and micelles (BASMM). With a pore diameter of ca. 2-3 nm, silica mesochannels (SMs) perpendicularly oriented to the ITO electrode surface can provide hard and robust supports to confine the soft cylindrical micelles formed by the aggregation of cationic surfactants, namely, cetyltrimethylammonium bromide (CTAB). Due to the organized self-assembly of hydrocarbon tails of CTAB surfactants, each micelle has a hydrophobic core, which acts as an excellent adsorbent for rapid extraction and preconcentration of trace nitroaromatic compounds from aqueous solutions via the hydrophobic effect. Furthermore, the cylindrical micelles are directly in contact with the underlying electrode surface, to which extracted compounds can freely diffuse and then be reduced therein, thus allowing their determination by means of voltammetry. Using the BASMM/ITO sensor, electrochemical analysis of trace nitroaromatic explosives, including 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenol, 2,6-dinitrotoluene, 3-nitrophenol, and nitrobenzene, and OPs, such as paraoxon, methyl parathion, and fenitrothion, was achieved with a fast response, wide linear range, high sensitivity, and low detection limit at the ppb level. TNT and paraoxon in real apple, tea, and water samples were also determined. By combining the heterogeneous extraction and determination in one ordered binary nanostructure, the BASMM sensor provides a very simple, rapid, and cost-effective way for analysis of nitroaromatic compounds and can be extended to a wide range of lipophilic yet redox-active analytes.
快速灵敏地检测硝基芳香族化合物对人类健康、环境及公共安全具有重大意义。本研究报道了使用经二氧化硅介孔通道与胶束的高度有序排列二元组装体（BASMM）修饰的氧化铟锡（ITO）电极，对痕量硝基芳香族化合物（如炸药和有机磷酸酯农药（OPs））进行萃取及电化学分析。垂直于ITO电极表面取向的二氧化硅介孔通道（SMs），其孔径约为2 - 3 nm，可为通过阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）聚集形成的软质圆柱形胶束提供坚硬且稳固的支撑。由于CTAB表面活性剂烃链的有序自组装，每个胶束都有一个疏水核心，通过疏水作用，该核心作为一种优良的吸附剂，可从水溶液中快速萃取和预富集痕量硝基芳香族化合物。此外，圆柱形胶束直接与下层电极表面接触，萃取的化合物可自由扩散至电极表面并在其中被还原，从而可通过伏安法对其进行测定。使用BASMM/ITO传感器，实现了对痕量硝基芳香族炸药（包括2,4,6 - 三硝基甲苯（TNT）、2,4,6 - 三硝基苯酚、2,6 - 二硝基甲苯、3 - 硝基苯酚和硝基苯）以及OPs（如对氧磷、甲基对硫磷和杀螟硫磷）的电化学分析，具有快速响应、宽线性范围、高灵敏度以及ppb级的低检测限。还测定了实际苹果、茶叶和水样中的TNT和对氧磷。通过在一个有序二元纳米结构中结合非均相萃取和测定，BASMM传感器为硝基芳香族化合物的分析提供了一种非常简单、快速且经济高效的方法，并且可扩展至广泛的亲脂性但具有氧化还原活性的分析物。
