The quantitative detection of levofloxacin in treated medical wastewater based on solid-phase extraction assisted dual wavelength absorption

Herein, we proposed a method which integrated solid-phase extraction (SPE) and ultraviolet dual wavelength absorption (UV-DWA) for quantitatively detecting levofloxacin (LEV) in treated medical wastewater. And electrocatalytic technology was utilized to simulate wastewater treatment systems. Tetracycline (TC) and LEV could be preferentially eluted and separated from other antibiotics, given their weaker retention behavior on SPE columns. The optimization of the SPE process was confirmed by high-performance liquid chromatography (HPLC). Based on the principle of wavelength superposition, we developed the DWA equation for wavelengths of 295 nm and 379 nm. TC has the same absorbance at the selected wavelength, so its interference can be eliminated through DWA. And the concentration of LEV was selectively determined. Conclusively, the linear range of SPE-DWA was 10–1000 ng‧mL⁻¹, with the correlation coefficient R² being 0.9984. Validation studies revealed that the limit of detection (LOD) was 2.95 ng‧mL⁻¹. The precision of this method, expressed as relative standard deviation (RSD), 2.49 % and 0.31 % for intra-day and inter-day analyses, respectively. Additionally, the method was successfully applied to the determination of trace levels of LEV in processed medical wastewater, and the recovery of the spiked samples ranged from 76.8 % to 87.8 %. Our findings indicated that the SPE-DWA had the potential for the on-site quantification of LEV residues in discharged medical wastewater, offering the advantages of low instrument, maintenance, and solvent costs. Furthermore, this method provides a technical pathway for the rapid and straightforward evaluation of antibiotic degradation systems in the future.