Abstract:In this paper, a method based on liquid chromatography-tandem mass spectrometry for the determination of residues of various nitroimidazoles (metronidazole, lornidazole, isopropynidazole, dimethylnitroimidazole, hydroxymetronidazole, hydroxymethylnitroimidazole) in health food with propolis as the main raw material was established. The samples were dissolved and dispersed with 0.1 mol/L hydrochloric acid solution, mixed well with vortex, then the target components were extracted by ultrasound and purified by HLB SPE column. The extract was separated on a Waters ACQUITY UPLC® BEH C18 column (1.7 μm, 2.1 m×100 mm) with gradient elution using a mobile phase consisting of 0.1% formic acid and acetonitrile. A tandem quadrupole mass spectrometer equipped with electrospray ionization (ESI) source in positive ion mode was employed for the quantitative analysis of the analyte using multiple reaction monitoring (MRM) scanning mode, with ion abundance ratio for qualitative analysis and external standard method for quantitative analysis. Under the optimal conditions, good linearities (R>0.998) were obtained in the related linear ranges. With addition level at 2.5, 5.0, 10.0 μg/kg, the recovery rates were 68.12%~92.20%, the relative standard deviations were 1.20%~5.83%. This method was simple, sensitive, accurate, and reproducible, has great popularization and application value, and could be suitable for the determination of various trace amounts of nitroimidazoles in propolis-derived health foods.
