A paper-based competitive lateral flow immunoassay for multi β-agonist residues by using a single monoclonal antibody labelled with red fluorescent nanoparticles

An ultrasensitive paper based lateral flow assay is described for rapid and simultaneous fluorometric detection of several beta-agonists including clenbuterol and its chemical analogues (mabuterol, brombuterol, cimaterol, cimbuterol, bromchlorbuterol and banbuterol). A nonspecific monoclonal antibody (mAb) against clenbuterol and its analogues was prepared and employed in a competitive immunoassay where mAb conjugated to fluorescent nanoparticles and free beta-agonists compete for the binding sites. This enables rapid screening for the 7 beta-agonists in a single run that takes about 8 min. Detection limits for the seven beta-agonists are <50 pg g(-1) of pork. Recoveries ranged from 69.5% to 102.4%, and relative standard deviations were +/- 15%. The assay was applied to the analysis of both using spiked and unspiked pork for beta-agonists, and the results compare well to those obtained by HPLC-MS.