Detection of pesticides in crops: A modified QuEChERS approach

The general term pesticide includes a large number of substances that belong to many different chemical classes. Pesticides are applied to crops at various stages of cultivation to provide protection against weeds and pests, and during post-harvest storage to preserve quality. The list of which pesticides are authorized for use in Europe is available on EU pesticides Database. The QuEChERS approach is a method designed for the analysis of pesticides in fruits and vegetables. This method is based on an extraction and clean-up step; it has been designed to be Quick Easy Cheap Effective Rugged and Safe. The aim of this study was to modify the QuEChERS method to be applied in the analysis of 9 organophosphate and 1 pyrethroid pesticides in raw materials for animal feeding introducing an additional liquid -liquid partition step. This additional step allowed us to concentrate the samples, avoiding any solvent evaporation, prior to the instrumental analysis. Once the method was optimized, it was carried out a pesticides quantization study using a GC-MS SIM multi-residue analysis. 45 samples of maize and soy coming from Northern Italy (Piedmont Region) were analysed during ten months. In 30 samples organophosphate pesticides were found up to 12.4 mg kg(-1) of Chlorpyrifos, while no Deltamethrin was detected. (C) 2011 Elsevier Ltd. All rights reserved.