Oligochitosan-modified three-dimensional graphene free-standing electrode for electrochemical detection of imidacloprid insecticide

A simple sensor based on an oligosaccharide-modified three-dimensional graphene (OCS-3D-G) free-standing electrode was developed for the electrochemical determination of the insecticide imidacloprid (IDP). OCS can interact with graphene oxide sheets by pi-pi and electrostatic interactions, leading to graphene oxide sheets arranged as regular and dense porous structures. Therefore, compared with other modifier carbohydrates, OCS-3D-G is more suitable for electrochemical sensing. OCS-3D-G was synthesized by a hydrothermal method and then fabricated as an electrochemical sensor, and its characterization was done and electrochemical behavior studied in detail. The optimized sensor showed good reproducibility, selectivity, and stability, and responded linearly over a wide concentration range (1.0-50.0 mu M) with a limit of detection (LOD) of 0.51 mu M. Finally, the proposed sensor was used for the determination of IDP in brown rice, and the results were in line with those obtained from high-performance liquid chromatography (HPLC). It is thereby shown that the developed free-standing electrode is simple and cheap and can be used as a disposable electrode.