Immunobiosensor determination of (beta)-agonists in urine using integrated immunofiltration clean-up

A fast immunobiosensor assay for screening of agonists in urine, using integrated immunofiltration clean-up with 30 kDa cutoff centrifugal filter, was developed. The same antibody aliquot was used for clean-up and biosensor analysis, and no organic solvent was needed. Matrix interference from urine was efficiently reduced. Two antibodies with different cross-reactivities were compared. Although both antibodies were able to detect clenbuterol (CBL) below 1 ng mL^ -1, a polyclonal antibody directed against salbutamol was chosen because of its ability to recover several (beta)-agonists. The decision limit (CC(alpha)) of the final assay was 0.29 ng mL^-1, and an (alpha)-error of 1% gave a (alpha)-error of (less than)1% for twenty reference bovine samples spiked with 1 ng mL^-1 CBL.