Determination of Multiple Pesticide Residues in Honey Using Gas Chromatography-Electron Impact Ionization-Mass Spectrometry

An analytical method was developed for the simultaneous determination of 23 pesticide residues in various commercial honeys. Meanwhile, the characteristic ions and fragmentation mechanism of three pesticides in the process of electron impact ionization mass spectrometry (EI/MS) were evaluated. After the optimization of different parameters such as the extraction solvent, pesticides were extracted from honey with ethyl acetate in an ultrasonic bath, cleaned up on a Florisil column by an elution of mixture of hexane and ethyl acetate (7/3, v/v), and analyzed by gas chromatography-electron impact ionization mass spectrometry (GC-EI/MS) in the selected ion-monitoring mode (SIM) with PCB103 as internal standard. Recovery studies were performed at 50, 100 and 200 μg/kg fortification levels for each pesticide, and the recoveries ranged from 82% to 120% with relative standard deviations between 1.8% and 11.0% for different pesticides. The limit of detection (LOD) was less than 10.0 μg/kg for all the pesticides. The developed method was linear in the range of 10–500 μg/kg, with correlation coefficients larger than 0.995. Finally, the developed analytical method has been successfully applied to the determination of pesticide residues in several honey samples.