STEREOSELECTIVE DETERMINATION OF CLENBUTEROL IN HUMAN URINE BY CAPILLARY-ELECTROPHORESIS

The effectiveness of capillary electrophoresis (CE) in the field of st ereoselective determination of drugs in biological matrices is demonst rated by analyzing clenbuterol in human urine. Due to the very low the rapeutical doses of 20-40 mu g per day the total concentrations in uri ne are 1-10 ng/ml. The sample was extracted with hexane-tert.-butyl me thyl ether (99.5:0.5). The reconstituted sample was injected electroki netically (50 s, 10 kV). Using phosphate buffer, pH 3.3 and hydroxyeth yl-beta-cyclodextrin as chiral selector the total analysis time was be low 15 min. The limit of determination was estimated as 0.5 ng/ml per enantiomer. S-(-)-Bupranolol was used as internal standard. Both preci sion and accuracy of the method were within the limits for biological samples. The application to human urine from patients having received therapeutical doses showed a slightly predominant excretion of the (+) -enantiomer to the (-)-enantiomer. (C) 1998 Elsevier Science B.V. All rights reserved.