Trace determination of fluoroquinolone antibacterial agents in solid-phaseextraction urban wastewater by and liquid chromatography with fluorescencedetection

Fluoroquinolones (FQs) are among the most important antibacterial agents (s ynthetic antibiotics) used in human and veterinary medicine. An analytical method based on reversed-phase liquid chromatography with fluorescence dete ction was developed and validated for the simultaneous determination of nin e FQs and the quinolone pipemidic acid in urban wastewater. Aqueous samples were extracted using mixed-phase cation-exchange disk cartridges that were subsequently eluted by ammonia solution in methanol. Recoveries were above 80% at an overall precision of better than 10%. Instrumental quantificatio n limits varied between 150 and 450 pg injected. The presented method was s uccessfully applied to quantify FQs in effluents of urban wastewater treatm ent plants. The two most abundant human-use FQs, ciprofloxacin and norfloxa cin, occurred in primary and tertiary wastewater effluents at concentration s between 249 and 405 ng/L and from 45 to 120 ng/L, respectively. The ident ity of FQs in urban wastewater was confirmed by recording full fluorescence spectra and liquid chromatography directly coupled to tandem mass spectrom etry. These results indicate that conventional environmental risk assessmen t overestimates FQ concentrations in surface waters by 1 to 2 orders of mag nitude.