Multi-residue analysis of pesticide residues and polychlorinated biphenyls in fruit and vegetables using orbital ion trap high-resolution accurate mass spectrometry.

Abstract

With the increasing demand on pesticide residue laboratories to increase their scope of analysis, high-resolution accurate mass (HRAM) systems have found increasing popularity in this area. The systems have the advantage of much more reliable confirmation as high resolution increases the ability to distinguish between masses which are close together and the mass accuracy achieved limits the number of structural formulae. To date, much of the work involving these systems has revolved around developing screening methods and little has been done on use of these systems for quantitative methods. Here we describe the development and validation of a quantitative method for the analysis of 167 pesticide residues and polychlorinated biphenyls (PCBs) in samples of fruit and vegetables according to the protocol described in EU SANTE guidance document. The determination method involves analysis using a GC QExactive orbitrap in full scan mode using EI. The samples were then extracted using the standard mini-Luke method. After extraction with acetone/dichloromethane/petroleum ether 40-60°C, a solvent exchange into ethyl acetate is carried out. Recovery work was carried out in cucumber, lemon and broccoli representing high water content, high acid content and high chlorophyll content commodity groups. The results show that the default MRL of 10ppb can be achieved for more than 93% of the pesticides studied. Mass accuracy, ion ratio and matrix effect studies show that the method is robust and provides a viable alternative to triple quadrupole mass spectrometer systems for the quantification of pesticide residues in fruit and vegetable samples.