Baltimore Ecosystem Study Institute of Ecosystem Studies

2011 BES Annual Meeting Presentation and Poster Abstracts

Solid-phase extraction and HPLC determination of fluoroquinolones in Baltimore-area wastewater
He, Ke
Co-Authors: Lee Blaney

Solid-phase extraction and HPLC determination of fluoroquinolones in Baltimore-area wastewater Fluoroquinolones (FQs) are one of the most widely prescribed classes of antibiotics and are employed for human and veterinary health. For this reason, it is unsurprising that FQs have been extensively detected at trace concentrations in the aquatic environment. An analytical method that employs offline solid-phase extraction (SPE) and reversed-phase high performance liquid chromatography with fluorescence detection (HPLC-FLD) was developed here for simultaneous determination of 11 FQs, namely ciprofloxacin, difloxacin, enrofloxacin, fleroxacin, gatifloxacin, lomefloxacin, moxifloxacin, norfloxacin, ofloxacin, orbifloxacin, and sarafloxacin, in wastewater. The optimized method uses a weak cation exchange SPE cartridge for FQ extraction from wastewater samples; after loading, the cartridge undergoes a water rinse and methanol wash to remove interference from background dissolved organic matter. Recovery of FQs from wastewater matrices was generally >80% with relative standard deviations of <5%. Chromatographic separation of the 11 FQs was achieved using a 20 mM phosphate buffer (pH 2.4)/methanol/acetonitrile gradient elution with a 150mm pentafluorophenyl column. The method provides complete resolution of the 11 FQs in less than 30 minutes with detection limits below 2 ng/L in raw wastewater. This method was successfully applied to determine FQ concentrations in wastewater samples from two regional wastewater treatment plants and one hospital. Of the 11 FQs investigated, seven (i.e. ciprofloxacin, difloxacin, enrofloxacin, fleroxacin, moxifloxacin, norfloxacin, and ofloxacin) were routinely detected. Typical concentrations of FQs in hospital wastewater, raw wastewater, and wastewater effluent ranged from < 1 to 829 ng/L, < 2 to 1916 ng/L, and < 1 to 212 ng/L, respectively.