| The use of Ractopamine by competitive athletes to aid physical performance, doping, has been banned by the International Olympic Committee. Also, Ractopamine has the repartitioning effect. So when administered by the intraperitoneal rout animals had increased weight gains with improved feed efficiency. In addition, lipolysis was stimulated by ractopamine in porcine adipose tissue; protein synthesis was increased by ractopamine in rat myotubes. Its illegal use in livestock production has led to toxic effects after human consumption of meat products. The use of Ractopamine has been banned as growth promoters in livestock and for improving athletic performance.Our research aimed to find a better means to detect the Rctopamine residue in forage and food. The antigen was synthesized by using a Ractopamine-anhydride derivative couple to a bovine serum albumin, then injected to Balb/c mouse. The spleen cells of BALB/c mice immunized by RACT-BSA were fused with SP2/0 plasmacytoma cells using PEG4000. A cell line, 3E1-C9-E10 which secretes monoclonal antibodies against Ractopamine stably was obtained by the technology of hybridoma.(A hybridoma cell line of 3E1-C9-E10 was screened for specificity to RACT and cloned by limited dilution method ,which secrete stable monoclonal antibodies against RACT)The antibody characterized by IgG1 isotype and generally had 24% cross-reactivity to Dobutamine, and showed little or no cross-reactivity to Salbutamol and Clenbuterol. The hybridoma cells line which average number of chromosome 96 steadily secretes antibodies after subcultured 15 times. The ELISA titers of cells supernate and ascites were exceeded 1: 105and 1×107separately.An indirect competitive ELISA was founded base on the monoclonal antibody. It's detection limit for Ractopamine was 2 ng/ml. Recovery range in forage and urine is from 80% to 105% .We can say ELISA is a better means to detect the Ractopamine residue in food by comparing limit, efficiency, definition, fee, etal. with other means.
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