Multiresidue method for the determination of pharmacologically active substances in egg and honey using a continuous solid-phase extraction system and gas chromatography-mass spectrometry

A sensitive, selective, efficient gas chromatography-mass spectrometry method for the simultaneous determination of 22 pharmacologically active substances (antibacterials, nonsteroidal antiinflammatories, antiseptics, antiepileptics, lipid regulators, β-blockers and hormones) in eggs and honey was developed. The sample pretreatment includes precipitation of proteins and lipids with acetonitrile:water (3:2, v/v), centrifugation and continuous solid-phase extraction for cleanup and preconcentration. The proposed method was validated with quite good analytical results including limits of detection of 0.4-3.3 ng/kg for 2 g of sample and good linearity (r2 > 0.995) throughout the studied concentration ranges. The recoveries of analytes from real honey and egg samples spiked at concentrations of 15-2000 ng/kg fell in the range 87-102%, with relative standard deviations from 2.6% to 7.0%. The method was successfully used to determine the target compounds in various types of eggs (hen, quail and duck) and honey samples (flower, forest, acacia, sunflower, clover and pine tree). Two samples of hen eggs bought at supermarkets and one of quail eggs were found to contain florfenicol, pyrimethamine, estrone and 17β-estradiol at levels from 0.095 to 2.7 μg/kg.