Determination of Organophosphorus Pesticides in Cucumber Using Dispersive Liquid-Liquid Microextraction Coupled to Gas Chromatography- Mass Spectrometry

High amount of organophosphorus pesticides (OPs) are used to control of pest on various crops and therefore measurement of their residue in the crops is very important. In this study dispersive liquid–liquid microextraction technique (DLLME) coupled with gas chromatography–mass spectrometric detection (GC–MS) was developed for the extraction and determination of OPs, Dichlorvos, Diazinon, Etrimfos, Methyl parathion, Fenitrothion, Malathion, Bromophos, Ethion in cucumber. Acetone was used as the extracting solvent for the extraction of OPs from plant samples. When the extraction process was completed, a mixture of Tetrachloroethylene (extraction solvent) and acetone extract (disperser solvent) were rapidly added to pure water. After centrifugation, the sedimented phase of Tetrachloroethylene was collected and injected into the GC–MS for separation and determination of OPs.
Influential parameters, such as, type and volume of extraction solvent, disperser solvent, salt and pH effects were studied and optimized. Under optimum conditions the enrichment factors and extraction recoveries ranged between 101. 1- 119 and 77. 1- 89. 25٪ for most of the analytes. The linear range was wide (20–500 μgkg−1) and the limits of detection were between 0. 006 and 13. 78 μgkg−1. The relative standard deviations (RSDs) were obtained in the range of 2- 23. 3٪. The developed method was successfully applied for determination of OPs residues in cucumber samples purchased from the local store.