Fabrication of electrochemical nanosensor based on polyaniline film-coated AgNP-MWCNT-modified GCE and its application for trace analysis of fenitrothion

Abstract

A simple, inexpensive, highly sensitive and selective electrochemical nanosensor based on electrochemically synthesized silver nanoparticles (AgNPs) and multiwalled carbon nanotubes (MWCNTs) was fabricated. The electrochemical pretreatment of modified electrode with conducting polyaniline film was performed to enhance the electrocatalytic activity, sensitivity, and detection limits. The designed electrochemical nanosensor was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), field emission scanning electron microscopy (FESEM), powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The as-fabricated electrochemical sensor was applied for examining the electrochemical behavior of an organophosphorus (OP) pesticide, fenitrothion (FT) in surfactant media by adsorptive differential pulse stripping voltammetry (AdDPSV) and cyclic voltammetry (CV). Different experimental parameter such as pH, scan rate, accumulation time, and potential has been optimized for trace determination of FT. Various kinetics parameters like the number of electrons transferred (n), electron transfer coefficient (α), formal redox potential (E0), standard heterogeneous rate constant (k0), charge due to adsorption (Qads), surface coverage of FT (Γ), charge transfer coefficient (Rct), and apparent electron-transfer rate constant (kapp) were evaluated. FT exhibited a linear range from 0.1 to 5.67 μg mL−1 and 0.1 to 1.5 μg mL−1 with low detection limits of 0.000193 and 0.000265 μg mL−1 at the modified glassy carbon electrode (GCE) by AdDPSV and CV, respectively. The fabricated sensor exhibited good accuracy and stability and efficacy for quantitative determination of FT in some real samples with notable recoveries ranging from 95.2 to 100.04%.