A sensitive and quantitative fluorescent multi-component immuno-chromatographic sensor for β-agonist residues

A sensitive and quantitative fluorescent multi-component immuno-chromatographic sensor was developed for detection of three β-agonizts: clenbuterol, ractopamine and salbuterol. A competitive immune strategy between antibody conjugated fluorescent beads and β-agonist or their antigens was employed. Each monoclonal antibody specifically recognizes it is corresponding β-agonist in the conjugating zone. The unreacted antibodies were captured by β-agonist antigens immobilized at three test lines in nitrocellulose membrane reaction zone. This enables simultaneous detection of 3 β-agonizts in one single test without any further sample preparation. The test results can be obtained within 10 min. Limit of detections for clenbuterol, ractopamine and salbuterol were 0.10 ng/mL, 0.10 ng/mL and 0.09 ng/mL, respectively. Recoveries ranged from 70.0% to 100.5% and relative standard deviations were below 15%. The assay was evaluated using spiked and real samples and the results were compared with LC-MS/MS. The developed novel assay method provides a low cost, sensitive and rapid approach for on site detection of β-agonizts.