Determination of six neonicotinoid insecticides residues in spinach, cucumber, apple and pomelo by QuEChERS method and LC-MS/MS.

A modified QuEChERS and LC-MS/MS method has been developed for the simultaneous determination of residues of six neonicotinoids in various crops, including spinach, cucumber, apple and pomelo. The method showed good linearity (R(2) ≥ 0.9995) and precision (RSD ≤ 14.0%). Average recoveries of the six neonicotinoids ranged between 73.7% and 103.8% at spiking levels 0.005, 0.1 and 1 mg kg(-1). The LODs and LOQs were in the ranges of 0.20-0.85 μg kg(-1) and 0.66-2.84 μg kg(-1), respectively. The method was satisfactorily validated for the analysis of 50 agricultural samples. Imidacloprid and imidaclothiz were detected at concentration levels ranging from 7 to 5.3 μg kg(-1).