Fluoroquinolones in Hospital Wastewater: Analytical Method, Occurrence, Treatment with Ozone and Residual Antimicrobial Activity Evaluation

Fluoroquinolones antimicrobials are partially excreted in natura after administration. Their occurrence was investigated in hospital raw sewage (HRS) and treated wastewater (TW) using an online solid phase extraction-ultra high-performance liquid chromatography-tandem mass spectrometry method (SPE-UHPLC-MS/MS). The analytical curves ranged from 0.25 to 46 ng mL-1 and the matrix effect, assessed for marbofloxacin and lomefloxacin, ranged from –63 to +1%. All HRS samples contained ciprofloxacin (1-34 ng mL-1) and ofloxacin (0.9-27 ng mL-1), while norfloxacin was detected in 17% of the samples (0.8-4.4 ng mL-1). Only ciprofloxacin (0.5-5.6 ng mL-1) was detected in TW samples. The antimicrobial activity of the HRS samples for E. coli was higher than a ciprofloxacin solution of 1 mg L-1, due to the presence of other antimicrobial agents. Ozonation (10 mg O3 L-1 min-1 ; 10 min) degraded up to 84% of the fluoroquinolones and removed the antimicrobial activity of HRS samples.