Multiresidue Analysis of 41 Pesticides in Honey by LC-MS/MS

Evaluation of Two Clean-up Methods

Abstract

Monitoring of pesticide residues in honey is important due to the risk they pose to human health, but also from an environmental point of view, because they provide relevant data on the pesticides that have been used in the hive surroundings. Which pesticides are monitored is crucial for the real significance of the results obtained. The selection of the 41 pesticides employed in this study was based on their relevance for bee products as reflected by the frequency of residue findings in the literature and the pesticides-online database. Recent data concerning the import of pesticides in Uruguay were also considered. A simple variation of the QuEChERS method (Quick, Easy, Cheap, Effective, Rugged and Safe) for the pesticide multiresidue analysis of honey is presented. Two clean-up methods were evaluated: freeze-out (extract placed at -20 °C for 15 h) and d-SPE (dispersive Solid Phase Extraction) using PSA (Primary and Secondary Amine) as sorbent. Pesticides were determined by LC-MS/MS (QTrap) in positive and negative mode. Recoveries were between 81-111 % for the dispersive clean-up except for five acidic pesticides which were recovered by freezing-out (recoveries between 80-114% except for three pesticides). RSD percentages (Relative Standard Deviation) were less than 16% in one day and less than 20% between different days for most of the studied pesticides. All pesticides showed good linearity, with R2 > 0.99 in the range 0.01-0.4 mg/L. Most of the studied pesticides have a limit of quantification of 0.01 mg/kg which is the lowest maximum residue limit set by the European Union for honey. This method serves the double purpose of evaluating the quality of Uruguayan honeys, in terms of food safety with commerce exchange parameters, as well as an input provider for the use of the hive as a bioindicator of environmental quality of a region.