Simultaneous determination of seven fluoroquinolones in sewage sludge by high performance liquid chromatography with fluorescence detection

We have developed an analytical method for simultaneous determination of seven fluoroquinolones(FQs)in sewage sludge based on solid-phase extraction and high performance liquid chromatography with fluorescence detection (HPLC/FLD) in this study to monitor the FQ contents and levels in sewage sludge. The homogenized sludge sample was subjected to pH 3 phosphate buffer/acetonitrile (1:1, V:V) solution treatment, then loaded onto an Oasis HLB solid phase column after vortexing and eluted with methanol solvent. The FQs in the extract were detected by HPLC/FLD with acetonitrile and 0.1% formic acid as the mobile phase, and quantified using external standards. The standard curves for all the compounds were linear over the concentration ranges of 0.005 to 1.0 mg/L with R2 equaling 0.9927-0.9998. The spiked recoveries at 0.05, 0.5 and 1.0 mg/L levels ranged between 78.3%-106.4%, with relatives standard deviations (RSD) ranging between 3.68%-12.06%(N=5). The limit of detection (LOD) was between 0.001-0.01 mg/kg, and the limit of quantification (LOQ) ranged between 0.0046-0.0384 mg/kg. We used this method to analyze seven FQs in sewage sludge collected from three sewage treatment plants in Beijing. and found the FQ concentrations to be from ND to 1.09 mg/kg in tested samples. © 2019, Editorial Office of Earth Science Frontiers. All right reserved.