Determination of residues of the beta-agonist clenbuterol in liver of medicated farm animals by gas chromatography mass spectrometry using diphasic dialysis as an extraction procedure

A method has been developed for the rapid confirmation of clenbuterol in cow liver using gas chromatography coupled with detection by mass spectrometry of the trimethylsilyl derivatives of clenbuterol. The technique used for the extraction was diphasic dialysis. It was observed that the best suitable solution to homogenize the liver the barium hydroxide-barium chloride buffer, the optimal extraction solvent was tert.-butylmethyl ether at an extraction temperature of 37 degrees C, and stirring should be applied at 150 rpm for 4 h. This extraction method improves clenbuterol recovery up to values of 99.3%. With the use of the barium buffer, derivatization is performed more efficiently and the detection and quantification limits can be decreased to values close to 250 ppt and 500 ppt, respectively.