[Self-assembled gold nanoparticles modified electrode for electrochemical detection nitrite].

A modified sensor was fabricated by N-[3-(trimethoxysilyl)propyl]-ethylene diamine(TSPED) and colloidal gold particles(AuNPs) on glass carbon electrode(GCE).Atomic force microscopy(AFM) demonstrated that the colloidal gold particles were self-assembled onto the amine groups of the sol-gel.Due to the excellent electrocatalytic activity of gold nanoparticles toward the oxidation of nitrite and the interaction between the protonated TSPED film and the negatively-charged nitrite,the operating potential for nitrite oxidation was shifted about 140mV to negative side,compared to bare GCE.The differential pulse voltammetry and the differential pulse amperometry were employed in the process of electrochemical measurements.Under the optimal conditions,a highly linear response to nitrite in the concentration range of 5.0 × 10-7-1.0 × 10-3 mol.L-1 was observed,with a detection limit of 2.0 × 10-7 mol.L-1(S /N = 3).The real water samples were investigated and the results were in good agreement with those obtained by standard spectrophotometric method.This method proposed by this paper possesses high sensitivity and good reproducibility.