Simultaneous screening for marbofloxacin and ofloxacin residues in animal-derived foods using an indirect competitive immunoassay

Abstract

ABSTRACTA broad-specificity immunoassay was established to monitor marbofloxacin (MBF) and ofloxacin (OFX) residues in raw milk and porcine muscle samples. The main influential parameters in the assay buffer were investigated to improve the assay performance. The cross-reactivities (CRs) were lower than 0.25%, except for OFX (41.38%). The quantitative working ranges for MBF and OFX based on fortified matrices ranged from 0.11 to 30.85 ng mL−1, with a 50% inhibitory concentration of 0.76±0.12 ng mL−1 for MBF and 2.70±0.28 ng mL−1 for OFX. The detection limits of enzyme-linked immunosorbent assay (ELISA) ranged from 0.053 to 0.358 ng mL−1 in spiked samples. The mean recoveries were in the range of 80.52–95.46%, less than 12.06% of the coefficient of variation. A good correlation between the ELISA results and those from instrument methods demonstrated the practical application of the novel ELISA. Therefore, the immunoassay proposed is feasible for MBF and OFX analysis in animal-derived foods.