Dr. Franz Liebetrau
Against the backdrop of an increasing number of positive doping control samples on Clenbuterol, which could partly clearly traced back to the consumption of contaminated food (meat), it was the aim of this work, in cooperation with our partner RIKILT Wageningen UR, to study the possibility whether the enantiomeric composition in a doping control sample allows for a distinction between the sources of Clenbuterol. Therefore stereoselective analytical methods for the matrices human urine and drugs, respectively for meat (cooperation partner) were developed and validated. The enrichment of the S-enantiomer described in literature for the organs of pigs, chickens and rats could be confirmed for bovine liver as well as the assumed racemic composition of Clenbuterol containing drugs and black market products. In an application study in which these three sources with their different enantiomeric compositions were applied, an indubitable distinction between the sources bovine liver and drug formulation could be achieved based on the determination of the enantiomeric composition in the urine samples of subjects. So in cases of positive test results for Clenbuterol the opportunity of exoneration in favour of the athletes would now be given. Based on the study results, a statistical model was build up which would allow for the setting of a limit of S-Clenbuterol in urine samples, provided that the applied enantiomeric composition in the liver of the experimental animal could be confirmed in that amount in other animals. Alternatively, an appropiate statistical hypothesis test could be used to test whether the samples of an athlete tested positive differ significantly from those of the group who had received the drug. In addition, the applicability of the HPLC Modelling Software DryLab® has been successfully tested for chiral separations, with the column used for the analysis of the Clenbuterol enantiomers.