Screening of multiclass pesticide residues in honey by SPE-GC/MSD: a pilot study

Analytical method for the monitoring of residues of multiclass pesticides (variable chemical structure and chromatographic behavior) in honey has been optimized and in-house validated in the present study. Chemical confirmation of 35 selected pesticides (in-hive-treated pesticides and pesticides applied for agricultural practices in vicinity of apiaries) has been successfully achieved with the acetonitrile extraction/partitioning and cleanup by modified US EPA solid-phase extraction (SPE) protocol following analysis on the GC/MS DRS Pesticide Screener. The applied extraction procedure has given acceptable recoveries with an associated precision (RSD) for selected pesticides within the range as suggested by SANTE at MQL of 10 μg kg^-1. Potential matrix effect for selected analytes was calculated by using honey from five different floral sources. The optimized method was used to determine levels of pesticide residues in honey samples randomly collected from 26 different apiaries in Pakistan. Residues of nine selected pesticide (dichlorvos, mevinphos, ethalfluralin, trifluralin, lindane, chlorpyrifos-methyl, dieldrin, profenofos, 4,4-DDE) were frequently detected in the ranges of 3-48.8 μg kg^-1 in 26.9% of analyzed samples (n = 26) and 15.3% of the studied samples exceeded maximum residue limits (MRLs). In-hive-treated acaricides, i.e., coumaphos, tau-fluvalinate, and malathion, were not detected in any of the analyzed honey samples.