Development of a tube enzyme immunoassay for ‘on-site’ screening of urine samples in the presence of β-agonists

An on-site screening test for the detection of β-agonistic drugs in urine was developed. The test is based on the principle of an enzyme immunoassay in polystyrene tubes. Results can be obtained by visual interpretation or by measurement with a differential photometer. The total time required to perform the test for a set of samples (five samples + one cut-off standard) is about 20 min (visual interpretation) with an additional 2 min for an instrumental interpretation. Owing to its speed and simplicity, the test can be performed in slaughter-and farmhouses. In the tube test, a mixture of antibodies raised against clenbuterol and salbutamol is used, which makes this test sensitive towards a range of β-agonists (multi-test). In this study, the test was applied to the screening of 269 bovine urine samples. Bovine urine samples with a level of 3 ng ml–1 of clenbuterol and higher were found positive with this on-site test. Owing to fewer matrix effects, a lower level (1 ng ml–1) could be detected in calf urine. The detection of positive samples at the place of sampling can result in more effective control of the illegal use of β-agonists.