Fluorescence Polarization Immunoassay for Determination of Enrofloxacin in Pork Liver and Chicken
Guangdong Provincial Key Laboratory of Food Quality and Safety, South China Agricultural University, Guangzhou 510642, China
State Key Laboratory of Food Science and Technology, School of Food Science of Jiangnan University, Wuxi 214122, China
A.N. Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky prospect 33, 119071 Moscow, Russia
Chemical Department, M. V. Lomonosov Moscow State University, Leninskie Gory, 119991 Moscow, Russia
Author to whom correspondence should be addressed.
Molecules 2019, 24(24), 4462; https://doi.org/10.3390/molecules24244462
Received: 9 October 2019 / Revised: 30 November 2019 / Accepted: 2 December 2019 / Published: 5 December 2019
(This article belongs to the Section Analytical Chemistry)
Enrofloxacin (ENR) is a widely used fluoroquinolone (FQ) antibiotic for antibacterial treatment of edible animal. In this study, a rapid and highly specific fluorescence polarization immunoassay (FPIA) was developed for monitoring ENR residues in animal foods. First, ENR was covalently coupled to bovine serum albumin (BSA) to produce specific polyclonal antibodies (pAbs). Three fluorescein-labeled ENR tracers (A, B, and C) with different spacers were synthesized and compared to obtain higher sensitivity. Tracer C with the longest arm showed the best sensitivity among the three tracers. The developed FPIA method showed an IC50 (50% inhibitory concentration) of 21.49 ng·mL−1 with a dynamic working range (IC20–IC80) of 4.30–107.46 ng·mL−1 and a limit of detection (LOD, IC10) of 1.68 ng·mL−1. The cross-reactivity (CR) of several structurally related compounds was less than 2%. The recoveries of spiked pork liver and chicken samples varied from 91.3% to 112.9%, and the average coefficients of variation were less than 3.83% and 5.13%, respectively. The immunoassay took only 8 min excluding sample pretreatment. This indicated that the established method had high sensitivity, specificity, and the advantages of simplicity. Therefore, the proposed FPIA provided a useful screening method for the rapid detection of ENR residues in pork liver and chicken.