Determination of five nitroimidazole residues in artificial porcine muscle tissue samples by capillary electrophoresis

A capillary electrophoresis (CE) method with ultraviolet detection has been developed for simultaneous detection and quantification of five nitroimidazoles including benzoylmetronidazole, dimetridazole, metronidazole, ronidazole, and secnidazole in porcine muscles. Nitroimidazoles in samples were extracted by ethyl acetate with subsequent clean-up by a strong cation exchange solid phase extraction column. The clean extracts were subjected to CE separation with optimal experimental conditions: pH 3.0 running buffer containing 25 mM sodium phosphate and 0.10 mM tetrabutylammonium bromide, 5 s hydrodynamic injection at 0.5 psi and 28 kV separation voltage. The nitroimidazoles could be monitored and detected at 320 nm within 18 min. The limits of detection were below 1.0 μg/kg and limits of quantification were lower than 3.2 μg/kg for all nitroimidazoles in the muscle samples. The recoveries and relative standard deviations were 85.4-96.0, 83.5-92.5, 1.3-3.9, and 1.1-4.2%, respectively for the intra-day and inter-day analyses. The proposed CE method has been successfully applied to determine nitroimidazoles in artificial porcine muscle samples with good accuracy and recovery, demonstrating that it has potential for detection and quantification of multi-nitroimidazole residue in real muscle samples.