{MSU/PDDA}_n LBL assembled modified sensor for electrochemical detection of ultratrace explosive nitroaromatic compounds

In this paper, layer-by-layer {MSU/PDDA}_n films assembled by alternate adsorption of mesoporous SiO₂ (MSU) and Poly (diallyldimethylammonium chloride) (PDDA) onto a glassy carbon electrode were reported. MSU that we used in this work was synthesized by the precursor of zeolite Y and ionic liquid of 1-hexadecane-3-methylimidazolium bromide (CMIMB), which was used as a template in basic medium. It exhibited larger pore diameter, pore volume and surface area. The electrochemical characteristics of the {MSU/PDDA}_n films have been studied by electrochemical impedance spectroscopy in 0.1 M KCl solution containing 5.0 mM Fe (CN)₆^{3 -} / Fe (CN)₆^{4 -}. By differential pulse voltammetry (DPV) measurement, the ultratrace nitroaromatic compounds (NACs) such as TNT, TNB, DNT and DNB can be detected with nM level. The sensitivity for NACs determination in {MSU/PDDA}_n films was dependent on the number of layers, pH and ionic strength of electrolyte, based on which a set of optimized conditions for film fabrication was inferred. The current responses were linear with NACs ranging from 10^-9 mol/L to 10^-7 mol/L with low detection limits. It is a sensitive, rapid and easy-to-use method for the fast determination of NACs.