Residue analysis of selected organophosphorus and organochlorine pesticides in commercial tomato fruits by gas chromatography mass spectrometry

In this study, analysis of some selected organophosphorus and organochlorine pesticides was carried out in tomato samples collected from the markets of Mettu town, Ilu Aba Bora Zone, Oromia, Ethiopia. The quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method was used for the extraction of collected samples using acetonitrile with 1% acetic acid, anhydrous magnesium sulfate, and anhydrous sodium acetate, followed by dispersive solid-phase extraction (d-SPE). Chromatographic separation and quantitative determination of the pesticides were performed by gas chromatography equipped with a mass spectrometer. The calibration curves for each analyte constructed in tomato samples were linear in the concentration range of 2–200 μg/kg with R(2) > 0.99 and the LODs and LOQs of the method were in the range of 0.01–0.04 μg/kg and 0.04–0.13 μg/kg, respectively. The recovery and precision study results were within acceptable standard guidelines. Of the fourteen pesticides tested, chlordane, hexachlorobenzene, 4, 4'-DDE, 4, 4'-DDD, 4, 4'- DDT, and profenofos were detected at 0.15, 0.09, 0.17, 0.032, 1.24 and 0.062 μg/kg, respectively. Despite the concentrations of the detected pesticides being lower than the maximum residue limit recommended by FAO/WHO, the presence of these toxic chemicals in tomatoes indicates product contamination and requires extensive further investigation with the inclusion of other pesticides.