Highly Ordered Binary Assembly of Silica Mesochannels and Surfactant Micelles for Extraction and Electrochemical Analysis of Trace Nitroaromatic Explosives and Pesticides

Abstract

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.

Vertically Ordered Silica Mesochannel Modified Bipolar Electrode for Electrochemiluminescence Imaging Analysis

“…The integrity, permeability and permselectivity of SMC film were also examined using cyclic voltammetry (CV) by immersing the SMC/ITO BPE in solutions containing a redox probe, such as Fe(CN) 6 3− or Ru(NH 3 ) 6 3+ . As shown in Figure S1, before removal of cetyltrimethylammonium bromide (CTAB) molecules from the mesochannels, the SMC/ITO electrode did not display obvious faradaic current signals for either Fe(CN) 6 3− or Ru(NH 3 ) 6 3+ , indicating the SMC film was compact and fully covered the ITO electrode surface . After excluding cetyltrimethylammonium bromide (CTAB) molecules, obvious current waves were obtained for both probes, suggesting the redox species in the bulk solution can freely transport to the underlying ITO electrode surface through the vertically ordered SMCs.…”

Platinized Silica Nanoporous Membrane Electrodes for Low‐Fouling Hydrogen Peroxide Detection

“…For example, nanoporous gold electrodes have been employed for the detection of DNAs in diluted biofluids . SNM modified electrodes have also illustrated excellent antifouling ability and allowed the direct detection of a variety of targets in complex samples and rat brain with high sensitivities . Our previous study shows that the SNM modified carbon fiber microelectrode (SNM/CFME) can work stably in rat brain up to 2 h .…”

A Facile and High Selectivity Novel Fluorescence Sensing Determination of 2, 4, 6-Trinitrophenol Based on Cationic Water-Soluble Pillar[6]arene Graphene Nanocomposite

“…TNP is currently determined by using solid-phase microextraction, [5,6] spectrophotometry, [7] X-ray imaging, [8] gas chromatography (GC), [9] capillary electrophoresis (CE), [10] high-performance liquid chromatography (HPLC), [11] and electrochemical methods. [12,13] Unfortunately, these methods often need a complicated synthetic process or labeling procedure-these are time consuming, expensive and complicated. In recent years, fluorescence techniques have been shown to be a promising method for the detection of TNP.…”