NiO nanostructures based functional none-enzymatic electrochemical sensor for ultrasensitive determination of endosulfan in vegetables

Abstract

In an effort to develop a rapid, sensitive and improved electrochemical sensing approach for the selective oxidation of endosulfan, nickel oxide nanoparticles (NiO NPs) were anchored on glassy carbon electrode (GCE). The fabrication of NPs was accomplished via aqueous chemical growth method and subjected to different analytical tools for the determination of surface characteristics, crystallinity and elemental composition. The XRD and FESEM reveal a high crystallinity and nano seeds like morphology for the synthesized NPs with the average size of 22 nm. Cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS) approaches were exploited for the investigation of electrochemical behaviour of modified electrode labelled as (NiO/GCE). A significantly enhanced response of NiO/GCE for the determination of endosulfan manifested the salient role of the developed sensor in facilitating the charge transfer mechanism between the electrode’s surface and the analyte. Differential pulse voltammetry (DPV) was utilized to quantify the amount of endosulfan. The certain parameters were optimized for the fluent determination process of endosulfan such as phosphate buffer of pH 7, scan rate 80 mV/s and potential range from − 0.6 to 0.8. The DPV (Ipa) response was linear over 0.05–25 µM range with the limit of detection of 0.17 nM and limit of quantification 0.51 nM respectively. The applicability of proposed sensor was investigated in real vegetable samples that showed acceptable percent recoveries for tomato and spinach samples which were calculated to be 94, 91, 87.3% and 98, 103, 100.2% respectively.