Analysis of several anionic polar pesticides in food of plant and animal origin using QuPPe extraction and CE-MS/MS determination

Although highly polar pesticides such as glyphosate (Gly) are widely used and highly relevant for pesticide residue analysis, their analytical determination is still problematic. Methods involving liquid chromatography in combination with tandem mass spectrometry (LC-MS/MS) often lack sensitivity due to insufficient separation from matrix co-extractives causing severe ion suppression effects on Gly and other anionic pesticides. In this study, capillary electrophoresis (CE) was used for an improved separation of analytes from matrix components, thus increasing sensitivity and robustness of analysis. Gly and 13 other anionic pesticides and selected metabolites (including glufosinate, ethephon, fosetyl, phosphonic acid and chlorate) were studied after extraction with the quick polar pesticides (QuPPe) method. Different tests resulted in an improved separation and sensitivity using a background electrolyte (BGE) containing 15% acetic acid and 20% methanol (MeOH) in water. The study also included the investigation of injection conditions and a thorough study of the matrix effects. Finally, results of method validation in several (strawberry, soybean, milk, liver, lemon) matrices of plant and animal origin are presented.