Accumulation of the beta(2)-adrenoceptor agonist clenbuterol in calf hair of different pigmentation

The objective of this study was to develop an analytical approach to detect the illegal application of Clenbuterol in cattle as an anabolic agent by hair analysis. Special emphasis was layed on the time course of the incorporation of Clenbuterol into growing hair and on the influence of hair pigmentation on Clenbuterol concentrations in hair. Twelve male veal calves of different coal color were fed with .8 mu g of Clenbuterol/kg BW, twice daily, for 10 d as prescribed for the therapeutic use that is registered in most European countries. During and after the treatment hair samples were obtained and analyzed for Clenbuterol residues. An appropriate method to extract Clenbuterol from hair for subsequent enzyme immunological quantification was developed. Clenbuterol residues could be detected in hair from d 4 (similar to 1 ng/g) of the treatment to d 60 after the end of treatment (similar to 20 ng/g). The accumulation of Clenbuterol was considerably higher in black hair (similar to 100 ng/g) than in lighter colored hair (similar to 5 ng/g) demonstrating the importance of hair pigmentation for the binding of Clenbuterol to the hair matrix. During d 11 to 25 of the experiment most of the incorporated Clenbuterol could be detected in the hair fiber (similar to 300 ng/g for black hair vs. similar to 20 ng/g for lighter colored hair). Our results suggested that hair analysis is a powerful mean to detect and track the illegal use of Clenbuterol in animal production.