Abstract: Anti-ractopamine polyclonal antisera were prepared by coupling ractopamine to bovine thyroglobulin and human serum albumin using two different methods. A systematic study of cross-reactions with eleven related compounds showed that the antibodies had a high specificity for ractopamine. Using the purified antiserum R3, an indirect competitive immunoassay for the determination of ractopamine in swine feed and urine was established and a typical competition calibration curve showed good sensitivity of 0.8 ng mL 1, estimated as the value of IC50, with a practical working range between 0.2 and 3 ng mL 1, the limit of detection of 0.15 ng mL 1. Finally, this assay was applied to the analysis of ractopamine in spiked swine feed and urine. The average recoveries of ractopamine were between 80-120% and the coefficients of variations were less than 10%. The results were also confirmed by liquid chromatography-mass spectrometry, which showed good agreement (r2 = 0.997) with the established immunoassay.
Pingli He , Liying Zhang and Tangbin Yang , 2008. Determination of Ractopamine in Swine Feed and Urine Using an Indirect Competitive Immunoassay. Journal of Animal and Veterinary Advances, 7: 268-275.