Comparative Evaluation of QuEChERS Method Coupled to DLLME Extraction for the Analysis of Multiresidue Pesticides in Vegetables and Fruits by Gas Chromatography-Mass Spectrometry

An economical and rapid multiresidue method has been developed using quick, easy, cheap, effective, rugged and safe (QuEChERS) procedure combined with dispersive liquid-liquid microextraction (DLLME) for the quantitative determination of 36 multiclass, multiresidue pesticides (13 organochlorines, 11 organophosphates, and 12 synthetic pyrethroids) in different vegetables and fruits without primary and secondary amine (PSA) cleanup step followed by gas chromatography-mass spectrometry (GC-MS) analysis. The procedure mainly involves the acetonitrile extraction in the presence of anhydrous MgSO4 and NaCl followed by DLLME using carbon tetrachloride (extraction solvent) and acetonitrile (disperser solvent). Experimental parameters were optimized using design of experiments (DoE) approach. The method developed without PSA cleanup step has yield similar analytical performance with that of method with PSA cleanup step for all the pesticides analyzed. The precision of the developed method was found to be less than 12 % and limit of detection for all the analyzed pesticides was found to be in the range of 0.001-0.010 mg kg(-1). This method was successfully applied in different fruits and vegetables and the recoveries were found to be in the range of 87-106 % at 0.05 mg kg(-1) with an acceptable precision (< 16 %). Coupling of QuEChERS with DLLME may be an appropriate replacement to eliminate costly PSA and makes the QuEChERS method more economical, time saving, without losing its analytical efficiency. The samples collected from Lucknow City, India, were analyzed for the presence of pesticides and only three pesticides beta-cypermethrin, lambda-cyhalothrin, and chlorpyrifos were found to have value above PFA-1954/CODEX-MRL values. The method has immense utility to use it for routine analysis of multiclass, multiresidue pesticides in fruits and vegetables.