Determination of flumethasone in calf urine and serum by liquid chromatography-tandem mass spectrometry

Corticosteroids can be illegally administered to cattle as growth promoting agents to improve meat production. We developed a liquid chromatography-at mospheric pressure ionization mass spectrometry-mass spectrometry (LC-MS-MS ) method able to identify and quantify flumethasone, one of the most potent fluorinated synthetic corticosteroid, in serum and urine from treated calv es. The analyte was purified from urine (conjugated and free, following enz ymatic hydrolysis) and from serum by C-18 solid-phase and liquid-liquid ext ractions, then analyzed by LC-MS-MS monitoring the product ions of an abund ant precursor (SRM in negative ionization mode). Results on flumethasone re sidues in biological fluids in three calves treated at different levels are presented. This method allowed the detection of flumethasone in bovine uri ne and serum at the 30-pg/ml level. (C) 2001 Elsevier Science B.V. All righ ts reserved.