Abstract: A method was developed for the rapid determination of 3 nitromidazole residues in honey, including metronidazole, ronidazole and dimetridazole, using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The honey sample was dissolved in water, and the solution was cleaned up with an Oasis HLB cartridge. The cartridge was washed with water and methanol-water solution (1:9, v/v) in turn, and eluted with ethyl acetate. The solution was concentrated and then analyzed by LC-MS/MS. External calibration was used for quantitative determination. The recoveries and relative standard deviations (n=8) were from 76.6% to 89.7% and 5.2% to 9.9%, at the spiked levels of 0.05-2.0 μg/kg, respectively. The limits of detection were 0.1 μg/kg for metronidazole, and 0.2 μg/kg for ronidazole and dimetridazole. The method was successfully applied for the inspection of exported honey. With simple and fast sample preparation, the method is sensitive and specific for the determination. The sensitivity and accuracy of the method meet the requirements of the inspection for the 3 nitromidazole residues in honey in Japan and European Union.

Key words: dimetridazole, honey , metronidazole, ronidazole, liquid chromatography-tandem mass spectrometry (LC-MS/MS)