Abstract: A liquid chromatography-tandam mass spectrometry (LC-MS/MS) method was developed for the determination of chlordimeform and its metabolite (4-chloro-o-toluidine) residue in acacia honey, chaste honey, comb honey, multifloral honey and wild honey. The samples were dissolved and diluted with sodium hydroxide solution, and cleaned up by a Waters Oasis HLB solid phase extraction column. The separation was performed on an Agilent XDB-C18 column with gradient elution using 0.1% formic acid solution and acetonitrile. The residues of chlordimeform and its metabolite were determined by electrospray ionization-tandem mass spectrometry, and quantified by the method of matrix-matched external standard. The calibration curves for chlordimeform and its metabolite showed good linearity in the range of 2.5~250 μg/L with the correlation coefficients (r) higher than 0.999. The limit of quantification was 5 μg/kg, and the limit of detection was 2.5 μg/kg. The recoveries of chlordimeform and 4-chloro-o-toluidine in honey at the spiked levels of 5, 10 and 20 μg/kg were in the ranges of 75.8%~113.8% and 85.6%~114.3%, respectively. The relative standard deviations were 4.8%~10.2% and 4.7%~9.1%, respectively. The method can meet the requirements for the determination of chlordimeform and 4-chloro-o-toluidine in honey for import and export inspection.

Key words: chlordimeform, honey , metabolite, liquid chromatography-tandem mass spectrometry (LC-MS/MS)