Abstract

How to Overstep Matrix Effects for Pesticides Detection Residues

Geraldine Giacinti, Researcher, Institute National Polytechnique de Toulouse

Analysts believed for a long time that concentrating pesticides in extracts was essential to achieve better detection. Recently, they demonstrated that with a sensitive detector like MSD, better detection occurs when extracts are diluted because matrix effects are diluted as well and poorly interfere with pesticides analytes. The aim of this work was to highlight the wider range of pesticides in fruits matrixes. Pesticides are known to concentrate about more than 90% in peels. Three varieties of apples from southwest of France and pesticides commonly used in the corresponding orchards were selected. The target residues were quantified by GC-MS2 with hot splitless injection in fruits and in fruit peels matrixes. Matrix effects occurring in these conditions were investigated. It was observed that quantifying pesticides in peels extracts pointed out the presence of other pesticides than those sprayed as conservative agents on one variety of apples just before the harvest. Quantifying pesticides in fruits extracts only displayed residues from pesticides sprayed on the variety just before the harvest. The results showed important matrix effects that are taken into account in the quantitation of pesticides residues in apples extracts, leading to more investigated pesticides in peels, highlighting cross contamination of pesticides.