Development and Performance Evaluation of an Analytical Method for Resorcylic Acid Lactones in Bovine Urine for Monitoring Japanese Beef Exports to the European Union

A quantitative method for determining resorcylic acid lactones (zeranol, taleranol, zearalanone, and zearalenone) in bovine urine using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and evaluated for use in the monitoring of Japanese beef exports to the European Union. This method involves the hydrolysis of conjugates by ß-glucuronidase/aryl sulfatase, clean-up with an immunoaffinity cartridge, and analysis using LC-MS/MS. The developed method was evaluated for zeranol, taleranol, zearalanone, and zearalenone in bovine urine at concentrations of 1 and 2 μg/L. The trueness ranged from 92 to 101%, with intra-day precision of <9% and inter-day precision of <13%. No interfering peaks were observed in the chromatogram near the analyte retention times. This analytical method is valuable for monitoring taleranol, zearalanone, and zearalenone in beef exports to the European Union. The proposed method is also applicable for screening whether zeranol was illegally administered or ingested via feed contaminated with Fusarium toxins, particularly in cases in which taleranol was detected.