Distribution of zeranol in bovine tissues determined by selected ion monitoring capillary gas chromatography/mass spectrometry.

Bovine tissues, including liver, muscle, kidney, bile, serum, and urine, have been quantified by selected ion monitoring capillary gas chromatography/mass spectrometry to establish the distribution of the anabolic drug, zeranol, and its metabolites, taleranol and zearalanone, after administration of zeranol to 9 bovine animals. The method used to isolate, confirm, and quantify zeranol is undergoing validation by the United States Department of Agriculture, Food Safety Inspection Service (FSIS). Application of this method demonstrates utility in determining residue levels of zeranol in a variety of tissues with levels ranging over 4 orders of magnitude (i.e., 100 parts per trillion (ppt) to 1 part per million (ppm]. The analyte levels determined in this study complement previously reported pharmacokinetic data on the distribution of zeranol in addition to providing more specific information for taleranol and zearalanone. In this quantitative study it is shown that the liver is the main organ of deposition for zeranol, taleranol, and zearalanone, that taleranol is the main metabolite in the bovine, and that zeranol is efficiently eliminated.