Monoclonal antibody production and the development of a quantitative time-resolved fluoroimmunoassay for rifaximin in milk

Rifaximin (RIF) is an important drug in clinical veterinary, and its residue in milk might pose a potential threat to human health. To monitor RIF residue in milk, a europium nanospheres-based time-resolved fluorescence immunoassay (TRFIA) was developed. The TRFIA is based on the competitive reaction between RIF-ovalbumin (OVA) and the target RIF in milk for binding to the Eu-Nanospheres-mAbs. The limit of detection (LOD) and limit of quantity (LOQ) were 3.05 and 6.63 ng/mL, respectively. The recoveries of the TRFIA to detect RIF in spiked milk samples ranged from 73.7% to 103.9%, and the interday and intraday variation were respectively less than 12.1% and 10.5%. A quantitative comparison of TRFIA and UPLC-MS/MS method exhibited a significant correlation (R2 = 0.9725) at the six various spiked levels. These results indicated that the TRFIA we developed was applicable for the detection of large numbers of milk samples.