Objective A sensitive liquid chromatography-tandem mass spectrometry(LC-MS/MS) method was developed for the simultaneous determination of 3 kinds of banned nitroimidazole veterinary drug and their metabolites including metronidazole,ronidazole,dimetridazole,metronidazole-OH(the metabolite of metronidazole),and 2-hydroxymethyl-1-methyl-5-nitroimidazole(the metabolite of ronidazole and dimetridazole) in milk and milk powder.Methods The protein in samples were precipitated with acetonitrile and the...