Development of a Monoclonal Antibody-Based Immunochromatographic Assay Detecting Ractopamine Residues in Swine Urine

Research paper by Amin Liu, Junxiao Lin, Mingyan Dai, Bio Ma, Yingying Wu, Jiehong Fang, Mingzhou Zhang

Indexed on: 29 Dec '15Published on: 29 Dec '15Published in: Food Analytical Methods


A lateral-flow immunochromatographic assay (LFIA) using monoclonal antibody was developed for the rapid detection of ractopamine residues in swine urine. The assay procedure could be accomplished within 5 min, and the results of this qualitative one-step assay were evaluated visually according to whether test lines appeared or not. When applied to the swine urines, the detection limit and the half maximal inhibitory concentration (IC50) of the lateral-flow immunochromatographic test strip under an optical density scanner were calculated to be 0.1 ± 0.013 and 0.71 ± 0.056 ng/mL, respectively. The cut-off level was observed with the naked eye of 1 ng/mL for detection of ractopamine residue in swine urine. Parallel analysis of swine urine samples with ractopamine showed comparable results obtained from the LFIA and LC-MS/MS. Therefore, the described lateral-flow test strip can be used as a reliable, rapid and cost-effective on-site screening technique for the determination of ractopamine residues in swine urine.