Development of a direct by competitive time resolved fluoroisnmunoassay for olaquindox based on Eu'3'+ labeling

In order to evaluate the effect of daguindox monoclonal antibody on Eu'3'+ labeling, the Eu'3'+ was conjugated to OLA-mAb by cyDTPA to obtain the Eu'3'+ -OLAmAb. The optimal conditions of coating antigen (OLA-OVA), Eu'3'+ -OLAmAb, coating buffer (CBS), ionic strength of PBS and organic solvent were 1.2 μg · mL^-1, 2.0 μg · mL^-1, 0.05 mol · L^-1, 0.01 mol · L^-1 (pH value 7.0) and 5% methnol-PBS, respectively. Finally, a sigmoid standard curve of OLA was established with the IC₅₀ value of 9.29 ng · mL^-1 and the IC₁₀ value of 0.66 ng · mL^-1. The average recoveries of determination for OLA spiked in feedstuff were between 84.80 ∼ 113.60%, and their mean coefficients of variation were below 14%. The established direct-competitive TRFIA method which has the advantages of high sensitivity and good stability lays the foundation for development of OLA immunoassay kit. (authors)