Development of an Immunoassay for Determination of Fluoroquinolones Pollutant in Environmental Water Samples

An immunoassay method for determination of Fluoroquinolones (FQs) residues in water samples has been developed. For this purpose, NHS ester technology was employed to synthesize the immunogen and coating antigen of Sarafloxacin (SAR). SDS-PAGE, UV-visible spectra and Infrared spectra identification showed that the artificial antigen was conjugated successfully. Based on the square matrix titration, an icELISA method was established. The dynamic range in assay buffer was from 0.048 to 62.4 ng/mL, with LOD and IC50 value of 0.018 ng/mL and 2.5 ng/mL, respectively. This assay showed a high cross-reactivity to Difloxacin (86.7%), Norfloxacin (63.2%), and Pefloxacin (33.8%). When applied in authentic tap water, river water and fishing water samples, the recoveries for Sarafloxacin, Difloxacin, Norfloxacin and Pefloxacin were 89.5-119.5, 90.5-121.2, 92.1-118.6, and 88.2-116.8%, respectively, with coefficient of variation (CV) values all <10%. The results suggest this immunoassay can be used for simultaneous detecting Sarafloxacin, Difloxacin, Norfloxacin, and Pefloxacin residues in water samples.