A highly sensitive fenobucarb electrochemical sensor based on graphene nanoribbons-ionic liquid-cobalt phthalocyanine composites modified on screen-printed carbon electrode coupled with a flow injection analysis

Abstract

A sensitive and rapid method for the determination of fenobucarb by using screen-printed carbon electrode modified with graphene nanoribbons - ionic liquid - cobalt phthalocyanine (GNRs-IL-CoPc/SPCE) composites based on flow injection analysis (FIA) was developed and applied to vegetable samples. The prepared GNRs-IL-CoPc composite was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Moreover, cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) were used to characterize the electrochemical behavior of the modified SPCE. The amperometric current responses were obtained from the oxidation of 2-sec-butyl-phenol, which is the product of alkaline hydrolysis of fenobucarb. The optimization of chemical variables and instrumental analysis such as composite amounts, pH, applied potential, and flow rate were carried out to obtain the best measurement. Under the optimal conditions, the proposed sensor yielded sensitivity of 0.0884 M/A·cm2, a wide linear range for detection of fenobucarb from 0.025 to 110 μM with a low detection, and quantification limits of 0.0089 μM and 0.0252 μM, respectively. Additionally, the developed sensor showed good repeatability (RSD = 3.5%, n = 10 measurements) and good reproducibility (RSD = 3.9%, n = 5 sensors). The proposed method could be effectively applied for the determination of fenobucarb in vegetable samples.