Sensitive determination of fenitrothion in water samples based on an electrochemical sensor layered reduced graphene oxide, molybdenum sulfide (MoS2)-Au and zirconia films

An efficient, highly sensitive and selective electrochemical sensor was developed for determination of fenitrothion in tap water, cropland water and canal water samples. The synthesized reduced graphene oxide (RGO) and molybdenum sulfide (MoS2)-Au were introduced using their synergetic enhancement effect to improve the sensor sensitivity. Zirconia (ZrO2) nanoparticles were electro-deposited onto modified gold electrode to selectively adsorb fenitrothion, which can be further captured by cyclic voltammetry or square wave voltammetry on the basis of its redox behavior of nitrobenzene group. The immobilization process was characterized by electrochemical impedance spectroscopy, illustrating the enhancement of RGO/MoS2-Au composite and the successful electro-deposition of ZrO2. Systematical method validation was performed including linearity, sensitivity, selectivity, reproducibility, regeneration and stability. The current is linearly correlated with the fenitrothion concentration from 5.0 to 600 ng mL−1 with the limit of detection of 2.2 ng mL−1. The developed electrochemical sensor displayed satisfactory performance in real water samples analysis.