Determination of dimethoate in olive oil by adsorptive stripping square-wave voltammetry

A method for the determination of dimethoate in olive oil by adsorptive stripping square-wave voltammetry has been developed on the base that this pesticide is hydrolyzed in basic media giving rise to an adsorptive-reductive peak at -0.780 V. Extraction of dimethoate from olive oil with ethanol-water and posterior clean-up with C18 cartridges is carried out. Response Surface Methodology has been used for the optimization of the extraction procedure. A matrix effect is observed in olive oil extract; therefore the standard addition method must be used. The detection limit is 19.00 ng g(-1) and recoveries for three levels of fortification are ranged from 79.9% to 104.5%.