Gold Immunochromatography Assay for the Rapid Detection of Spiramycin in Milk and Beef Samples Based on a Monoclonal Antibody

Abstract

Spiramycin (SP) residues in food do harm to human health. It is necessary to establish rapid detection method for SP. In this work, a monoclonal antibody (mAb)-based gold immunochromatography assay (GICA) is developed for the rapid detection of SP. Under optimum conditions, the half-maximal inhibitory concentration of SP-mAb is 0.43 ng mL^-1 . The subtype of SP-mAb is IgG2b. This antibody has no cross-reactivity with other analogues and has high affinity (4.52 × 10¹⁰ L mol^-1 ). Qualitative results can be visualized with the naked eye, with a visual detection limit of 1.0 ng mL^-1 and cut-off value of 10 ng mL^-1 . A hand-held strip scanner is used for the quantitative analysis, with LOD 0.43 ng mL^-1 in assay buffer. The recoveries of SP ranged from 72.3% to 112% in milk and 98.5% to 115% in beef, with variable coefficient ranging from 9.4% to 11.7% in milk and 8.14% to 15.4% in beef. Besides, the proposed GICA method for SP is confirmed by LC-MS/MS in SP-spiked milk and beef samples. Overall, the developed GICA can be a useful tool for SP residues on-site screening in milk and beef samples.

Keywords: beef; gold immunochromatography assay; milk; spiramycin; strip.