A novel preconcentration/extraction method for fenitrothion residues and its electrochemical sensing in pistachio kernels

The accumulation of organophosphate pesticides (OPPs) in the environment has turned into a predicament for ecological balance and human health. So in this study, a sensitive, easy, and efficient method has been offered for the preconcentration and quantification of the low levels of fenitrothion, one of the prevalent organophosphates, in pistachio kernels. In this technique, at the first step, fenitrothion from aqueous medium was extracted into a few microliters of chloroform using dispersive liquid–liquid microextraction method. After centrifugation and separation of the fenitrothion-containing chloroform drop, it was casted on the surface of a glassy carbon electrode modified with carbon nanotubes. Then, chloroform was allowed to be evaporated at room temperature. Finally, the electrode was immersed into 0.10 M phosphate buffer solution (pH 7.0), where cyclic voltammogram of the deposited fenitrothion was recorded. After optimization of different experimental parameters affecting extraction and electrochemical steps, the concentration linear range of fenitrothion was obtained to be 0.54–6.84 µM. Detection limit was 0.090 µM and the relative standard deviation for seven replicate measurements of the 1.80 µM fenitrothion solution was 3.3%.