APPLICATION OF AN ENZYME-LINKED-IMMUNOSORBENT-ASSAY KIT FOR BETA-AGONIST SCREENING OF BOVINE URINES IN NORTH-EASTERN ITALY

The application and the results of a commercially available enzyme-linked immunosorbent assay (ELISA) kit for the screening of beta-agonists are presented. The kit was adopted as a screening method because it allows very rapid multi-analyte detection without extraction. Beta-Agonists such as clenbuterol, mabuterol, salbutamol and terbutaline can be detected in bovine urine with a decision limit of 0.6, 0.9, 1.6 and 2.5 ng ml-1, respectively, Confirmation of positive ELISA results concerning the presence of clenbuterol and salbutamol was made by liquid chromatography and by gas chromatography-mass spectrometry, with immunoaffinity clean-up. By employing the described strategy, in a 5-month period, 59 out of 815 samples were found to be positive. Positive groups of samples were from both therapeutic and anabolic use of beta-agonist drugs. Adopting 1 ng ml-1 clenbuterol as a cut-off value, the percentage of unconfirmed positive ELISA herds was 3.6%. The reliability of the overall control strategy and of the kit in terms of the percentage of false-positive results is evaluated.