Abstract:

A simple and reliable method was developed for simultaneous determination of multi-class antibiotic residues in aquatic environment, including three fluoroquinolones (ofloxacin, norfloxacin, ciprofloxacin), three sulfonamides (sulfadiazine, sulfamethoxazole, sulfamethazine), chloramphenicol and trimethoprim. Samples were extracted and concentrated through hydrophilic-lipophilic balance (HLB) cartridges. Selected antibiotic compounds were determined by high performance liquid chromatography (HPLC) using internal standard quantification method. Antibiotics were separated on an Agilent XRD C18 column (150 mm×3.0 mm, 3.5 μm) with a gradient elution using acetonitrile and 0.1% (v/v) formic acid in purified water at a flow rate of 0.25 mL/min and the column temperature of 25 ℃. Fluoroquinolones were quantified by fluorescence detection (FLD) and the others by ultraviolet detection at 280 nm. The recoveries for the antibiotics are ranging from 80% to 120% for spiked tap water, and 63% to 106% for urban river water samples, respectively, with relative standard deviation lower than 18%. The limits of quantification were 0.030-0.080 μg/L for surface waters. The method has been successfully applied to monitor the occurrence of antibiotic residues in the urban river waters from the Pearl River in Guangzhou. Sulfamethoxazole, ofloxacin, norfloxacin and ciprofloxacin were detected at mass concentrations ranging from 0.197 to 0.510 μg/L.

Key words: antibiotics, high performance liquid chromatography (HPLC), urban water system
, solid phase extraction (SPE)