Determination of fenbendazole and its metabolites in milk by the method of liquid chromatography coupled with tandem mass-spectrometry

Abstract

Objective of research: Development of methods for the determination of fenbendazole and its metabolites in milk by liquid chromatography coupled with tandem mass spectrometry. Materials and methods: Fenbendazole was administered orally to five cows. Samples of milk were taken on 1, 3, 5 and 10 days of drug application. The research method includes a description of reagents, plates and equipment; mass-spectrometric conditions for analysis of fenbendazole and its metabolites; preparation of the equipment to operation; preparation of eluent solution; preparation of the chromatograph to analysis; determination of chromatographic parameters of standard drug samples; preparation of milk samples to analysis; establishment of parameters of extracts’ chromatography; procedure of calibration of fenbendazole and its metabolites in eluent. Results and discussion: When studying the pharmacokinetics of fenbendazole and its metabolites (sulfone and sulfoxide) in milk, it was found that the maximal concentrations were determined 24 h after drug administration and were 22,6 ng/ml for fenbendazole sulfone, 34,0 ng/ml for fenbendazole sulfoxide and 19,7 ng/ml for fenbendazole. 10 days after treatment, the concentrations of fenbendazole and its metabolites in milk did not exceed permitted values.