Optimization of QuEChERS method for determination of 315 pesticides residues: prelude to risk assessment using LC-ESI-MS/MS

Abstract

A residual analytical method for the determination of 315 pesticide compounds (including a wide range of physicochemical properties) in cereals was optimized and validated. The pesticide residues extraction was carried out using QuEChERS method and the determination was achieved using liquid chromatography tandem mass spectrometry (LC-MS/MS). Sample preparation efficiency was optimized by adding 10 ml water on 2g sample for hydration, before extracting with acetonitrile. The developed method was validated according to European Union guidelines (SANTE/2017/11813). The recovery tests were studied at three spiking levels of low concentration (0.01, 0.05, and 0.1 mg/kg). Most of the studied pesticides (301 compounds) have acceptable recovery between 70 and 120% with good precision. The developed method was successfully applied for the analysis of 60 collected cereals samples (wheat and maize) from Egyptian markets and grain storage silos. Twenty nine samples were free from any pesticide residues while 9 pesticides were found in 31 samples without exceed Codex and EU MRL limits. Finally, the residue data was used for estimation of dietary risk employing FAO/WHO approach.