Determining pesticide contamination in honey by LC-ESI-MS/MS - Comparison of pesticide recoveries of two liquid-liquid extraction based approaches

Honey, a valuable food product, may be contaminated by xenobiotics during its production and/or harvest. The determination of trace levels of contaminants in a complex matrix like honey still presents a challenge to analytical chemists. The aim of this work was to assess and compare the extraction efficiencies of 30 pesticide residues (acaricides, insecticides, herbicides, fungicides), belonging to over 15 different chemical classes. Two common extraction approaches were applied the increasingly popular QuEChERS method and extraction on a diatomaceous earth support. Both are used for pesticide determinations in fruits and vegetables, and with some adjustments they can be used for honey samples. In order to assess whether the differences in recoveries between the two investigated methods were statistically significant, the F-Snedecor and T-test were employed. The recoveries ranged from 34 to 96%, and in the case of 4 pesticides the differences in the values were statistically significant. Both methods showed good linearity (R-2 > 0.991), and the extraction efficiencies enabled method quantification limits well below EU-recommended Maximum Residue Levels to be achieved for the investigated pesticides. (C) 2013 Elsevier Ltd. All rights reserved.