Determination of clenbuterol residues in bovine hair by using diphasic dialysis and gas chromatography mass spectrometry

A method for the determination of clenbuterol (4-amino-3,5-dichloro-alpha[(tert.-butylamino)methyl]-alcohol hydrochloride) in hair of living cows has been developed. Hair samples were digested in an alkaline medium. The diphasic dialysis technique is a semi-permeable membrane technology developed for the direct extraction of relatively low-molecular-mass analytes such as clenbuterol. In this case, we used sodium citrate buffer to homogenize the digested hair, dichloromethane was used as the extraction solvent at 37 degrees C, and stirring was applied at 150 rpm for 4 h. The analysis was carried out using gas chromatography-mass spectrometry. The calibration curve for clenbuterol in hair was linear in the range from 12.5 to 400 ng g(-1). The detection limit of clenbuterol was 5 ng g(-1) and the quantification Limit was 12.5 ng g(-1), in hair. A good inter-day reproducibility was obtained (R.S.D.=7.08%). The repeatability and intra-day reproducibility (50 ng g(-1) of hair, n=10) show R.S.D.s of 7.1 and 9.5%, respectively. (C) 1999 Elsevier Science B.V. All rights reserved.