Trace detection of nitroaromatic compounds with layer-by-layer assembled {SBA/PSS}_n/PDDA modified electrode

The {SBA/PSS}_n/PDDA films modified electrode was prepared by layer-by-layer (LBL) assembly with mesoporous SiO₂ (SBA), poly(sodium 4-styrene-sulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDDA) in this paper. SBA is a large pore-size mesoporous material with highly ordered hexagonally arranged mesochannels and high thermal stability etc. The electrochemical characteristics of the {SBA/PSS}_n/PDDA 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- at the formal potential of 0.230 V. The ultratrace nitroaromatic compounds (NACs) such as TNT, TNB, DNT and DNB were determined by differential pulse voltammetry (DPV) measurement. The sensitivities for NACs determination with {SBA/PSS}_n/PDDA modified electrode were 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 to 10^-7 mol/l. The results showed that the {SBA/PSS}_n/PDDA modified electrode established a new way for fast, simple and sensitive analysis of NACs.