A method is described for the extraction of clebuterol from bovine retina samples by diphasic dialysis using gas chromatography—mass spectrometry (GC-MS) as the procedure of determination. Following chemical digestion of retinal tissue in alkaline medium at 80°C, clenbuterol is extracted by diphasic dialysis using diethyl ether as solvent at 37°C, for 4 h at 150 rpm. Diethyl ether is evaporated to dryness and clenbuterol determined by GC-MS after butylboronic acid (BBA) derivatization. A detection limit of 2.5 ng g⁻¹, repeatability of 9.0% and reproducibility of 22.9%, with recoveries always >86% (n=5), are achieved as validation criteria.