Development and validation of dispersive liquid-liquid microextraction for the determination of multiclass pesticide residues in complex food matrix

Abstract

In this study, dispersive liquid-liquid microextraction (DLLME) which is known for its simplicity, rapidity and high recovery was developed coupling with gas chromatography-flame ionization detector (GC-FID) for the determination of pesticides of different chemical groups in tomato and cucumber samples. Parameters affecting the extraction efficiency of DLLME such as types and volume of extraction solvent and dispersive solvent, extraction time and ionic strength of aqueous solution were studied and optimized. Under the optimized conditions (0.8 mL acetone, dispersive solvent; 14.2 μL tetrachloroethylene, extraction solvent; 20 s extraction time; no salt addition), the relative recoveries of pesticides from tomato and cucumber samples at a dilution factor of 1:25 were in the range of 94.58-103.34% and 96.46-109.45% respectively. The limits of detections (LODs) of all pesticides except diuron from tomato and cucumber extracts were ranged from 7.5-15 μg/L and 15-39 μg/L respectively. All the LODs of pesticides except diuron extracted from both tomato and cucumber extracts using the proposed DLLME method coupled with GC-FID were still found to be lower than the maximum residue levels (MRLs) established by European Union and / or Codex Alimentarius.