Multiclass Method for the Determination of Pesticide Residues in Oat Using Modified QuEChERS with Alternative Sorbent and Liquid Chromatography with Tandem Mass Spectrometry

Abstract

Many pesticides are used for pest control during oat production and storage, making necessary to employ multiclass methods for pesticide residue determination. In this work, an efficient QuEChERS method was established for multiresidue determination of 60 pesticides in oats by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Different sorbents, such as chitosan, Forisil®, C18, PSA, Supel QuE Z-Sep+, and EMR-Lipid were evaluated for cleanup by dispersive solid-phase extraction (d-SPE). The original QuEChERS method had the best performance and the biosorbent chitosan presented similar results to the other conventional sorbents evaluated and being an efficient and low-cost biodegradable material was chosen for the cleanup step. The method presented adequate accuracy and precision using blank samples spiked between 5 and 100 μg kg−1, with recovery from 70 to 120% and RSD < 20% for all 60 pesticides and limits of quantification of 5 μg kg−1 for almost all studied pesticides, with exception of triflumizole for which was 10 μg kg−1. The method was successfully applied in real samples proven to be a good option for routine analysis. Oat samples presented residues of azoxystrobin, metalaxyl, and thiamethoxam.