A method for the determination of 29 imidazoles and their metabolites in pork by liquid chromatography-tandem mass spectrometry has been developed. The samples were extracted with ethyl acetate, and then defatted with n-hexane after concentration of the extracts. The analytes were separated on a C18 reversed-phase column with 0.3% (v/v) formic acid aqueous solution and acetonitrile as mobile phases, and finally analyzed using electrospray ionization in positive ion mode (ESI+) with multiple reaction monitoring (MRM). The linear ranges of the 29 compounds were from 0.05 to 20.0 μg/L with the correlation coefficients (r2) more than 0.99. The average recoveries and relative standard deviations were 65.4%-103% and 1.3%-6.8% respectively in the spiked ranges of 1.0-5.0 μg/kg. The limits of detection and the limits of quantification were 0.02-0.3 μg/kg and 0.1-1 μg/kg respectively for the 29 imidazoles. The method is simple, rapid and sensitive. It is suitable for the detection of imidazoles and their metabolites in pork.
Keywords: imidazoles; liquid chromatography-tandem mass spectrometry (LC-MS/MS); pork; residue.