A method for the quantitative analysis of nitroimidazoles and their metabolites in four kinds of animal-derived foods by liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with dispersive solid phase extraction (dSPE) was established. The samples (2.0 g) were extracted with ethyl acetate. The extracts were degreased with hexane and purified with 50 mg primary-secondary amine (PSA), and then filtered through a hydrophilic polytetrafluoroethylene (PTFE) membrane. The analytes were separated on a C18 column, and detected in selected reaction monitoring (SRM) mode via positive electrospray ionization. The matrix matching and internal standard method was used. The nitroimidazoles and their metabolites showed good linearity in the range of 0.5-20.0 μg/L with correlation coefficients greater than 0.99. The limits of detection of the nitroimidazoles and their metabolites in animal-derived foods were between 0.1 and 0.5 μg/kg. The recoveries varied between 84.2% and 120.8%, with relative standard deviations (n=6) ranging from 2.0% to 16.2% at spiked levels of 1.0, 3.0, and 10.0 μg/kg. The proposed method is accurate, fast, cheap, easy, and can satisfy the requirements of monitoring nitroimidazoles and their metabolites in animal-derived foods.
Keywords: animal derived foods; dispersive solid phase extraction (dSPE); liquid chromatography-tandem mass spectrometry (LC-MS/MS); nitroimidazoles and their metabolites.