[Determination of nitroimidazoles in oral hygiene by ultra-performance liquid chromatography-tandem mass spectrometry].

A method for the simultaneous determination of metronidazole, tinidazole, ornidazole, ronidazole and dimetridazole in oral hygiene by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) has been developed. The sample was diluted with 0.1% formic acid/acetonitrile (95:5, v/v), then centrifuged and filtered with a membrane. The separation was carried out on a Cloversil C18 column (100 mm x 2.1 mm, 3.5 microm) with the gradient elution of 0.1% formic acid and acetonitrile as the mobile phases. The analytes were determined by UPLC-MS/MS and quantified by external standard method. The calibration curves showed good linearity in the range of 1.0-60.0 microg/L with r > or = 0.9992. The recoveries were 91.5%-108% at the three spiked levels of 10.0, 20.0 and 100 mg/kg, and the relative standard deviations were 1.14%-5.22%. This method is easy, sensitive and suitable for the determination of nitroimidazoles in oral hygiene.