Development and validation of a screening method for DES, zeranol, and beta-zearalanol in bovine urine by HRGC-MS and evaluation of robustness for routine survey of the Brazilian herd.

A method and evaluated for screening and confirmation of diethylstilbestrol (DES), alpha- and beta-zearalanol in bovine urine was developed. The residues were extracted from urine by C18 cartridges and purified on alumina columns. For screening and confirmation purposes, the anabolic derivatives were analyzed by gas chromatography-mass spectrometry after derivatization with BSTFA + 1% TMCS or a solution of PFPA/acetone (1:2, v/v), respectively. The recovery of most analytes for the whole procedure was higher than 96%, with a detection limit of 0.5 ppb. This procedure is being routinely applied to the Brazilian National Program for the Control of Residues in Meat (PNCRBC).