Determination of multi-pesticide residues in honey with a modified QuEChERS procedure followed by LC-MS/MS and GC-MS/MS

This paper presents a modified QuEChERS method to determine 346 pesticide residues in honey by LC/MS-MS and GC/MS-MS. Acetate buffered acetonitrile extraction followed by dispersive SPE clean-up with C18-E, PSA and MgSO4 sorbents were used for sample preparation. This method was validated according to the European Union SANTE/2019/12682 guidelines. Acceptable values were obtained for the linearity, the limit of detection (0.001-0.003 mg/kg), limit of quantification (0.002-0.008 mg/kg), trueness (for the four tested levels, the recovery assays values were between 76 and 112%), precision (RSD <= 20.0%) and measurement uncertainty tests (<50%). The method was used for the analysis of 100 honey samples from Northern Cyprus and residues of 4 pesticides (coumaphos, thiamethoxam, N-(2,4-dimethylphenyl)formamide, piperonyl butoxide) were quantified in 42 honey samples. Coumaphos (29%) and N-(2,4-dimethylphenyl)formamide (11%) were the residues frequently detected in the samples. N-(2,4-dimethylphenyl)formamide concentrations (0.56 and 0.84 mg/kg) were determined above the MRL limits (0.2 mg/kg) in two samples. This study shows that LC/MS-MS and GC/MS-MS in combination with modified QuEChERS can be used to routinely scan pesticide residues in honey samples and direct contamination with acaricides/veterinary drugs applied in the treatment of plagues in the hive during honey harvest is the main source of honey pollution in Northern Cyprus.