A novel microsphere-based fluorescence immunochromatographic assay for monitoring cefalexin residues in plasma, milk, muscle and liver

摘要

A novel, microsphere-based fluorescence immunochromatographic assay (MFIA), of higher sensitivity and faster detection than the monoclonal-based competitive indirect enzyme-linked immunosorbent assay (ci-ELISA), was developed for the routine surveillance of cefalexin antibiotic residues in plasma, milk, muscle and liver. The cross-reactivities of the fluorescent microspherea€“monoclonal antibody (FMa€“mAb) conjugates to cefaclor, cefadroxil, cefradine and cefixime were 212.7%, 155.6%, 108.1% and 86.6%, respectively. The limits of detection of the proposed MFIA were 0.1 ??g La?’1 in all the cases, with IC50 values in the range from 0.59 to 0.71 ??g La?’1. The recoveries were 84.5% to 107.2% with the coefficient of variation less than 6.9% when cefalexin standards were spiked in selected biological matrices. Good correlations among the MFIA, ci-ELISA and ultra performance liquid chromatography-mass spectrometry/mass spectrometry (UPLC-MS/MS) results for blood samples from a cefalexin-injected rabbit were observed. In summary, the entire assay took about 30 min, and was simple, rapid, highly sensitive and cost-effective for both high-throughput screening and individual testing in food quality control.