Abstract

Pharmaceuticals in waters represent a worldwide problem of today. Advanced oxidation processes (AOPs) are being researched for elimination of the ecological hazard. Among the substances, the fluoroquinolone antibiotic lomefloxacin was selected for investigation in this study. Lomefloxacin (LOM) was found in the German river Erft. Near and far ultraviolet (UVA, UVC) radiation were used as AOPs and compared for efficiency depending on pH, water matrix, and catalysts. Chemical kinetics description revealed that UVC at pH 8–9 led to the fastest degradation of LOM. The catalysts hydrogen peroxide and titanium dioxide had only limited influence on the degradation rate. Seven novel transformation products were structurally identified by high-resolution higher-order mass spectrometry. Ecotoxicity of the novel and known compounds was assessed by quantitative structure-activity relationship (QSAR) analysis. In addition, irradiation time dependent minimal, and half-maximal inhibitory concentrations (MIC, IC50) of LOM solutions were determined and suggested as ecotoxicological hazard indicators. From MIC and kinetic rate constants, the irradiation time required for compound and activity removal could be predicted.

Highlights

  • Numerous recent studies have confirmed the presence of various anthropogenic micropollutants in water bodies [1,2,3]

  • For the identification of transformation products at high sensitivity and high reliability, mass spectrometry was used as a detection system after chromatographic separation

  • The investigation of water samples from the German river Erft showed the presence of the fluoroquinolone LOM

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Summary

Introduction

Numerous recent studies have confirmed the presence of various anthropogenic micropollutants in water bodies [1,2,3]. The main entry route focuses on wastewater treatment plants (WWTPs), which often fail to completely eliminate these substances through the conventional purification processes. They enter the aqueous environment where they become ecotoxicologically hazardous. Advanced purification stages for the elimination of these anthropogenic micropollutants are currently being tested worldwide, including chemical catalysts and UV irradiation. Some of these methods, such as UV irradiation, produce OH radicals, which act as strong oxidants with an oxidation. Ophnolytoodneegsrtauddayticoonuoldf fblueoforouqnudincoonlocnerensiinngcpohmobtoindaetgiroandwatiiothnQofSflAuRor[o2q3]u.iBnaosloendeosninMcoICmabnindatcihoenmwicitahl QkiSnAetRics[2, 3ir]r.aBdaiasetidonontimMeICs daenpdenchdeinmgicoanl akqinueattiiccs,coirnradditiiaotniosncotiumldesbdeeppreenddicitnegd.on aquatic conditions could be predicted

Experiments
Solid-Phase Extraction of River Water Samples
Photodegradation Experiments
HPLC-ESI-Q-TOF-MS and HPLC-ESI-IT-MS
Determination of Quantum Efficiency
Photoinduced Degradation of Lomefloxacin—Kinetic of Degradation
F NNFNNFFF N
Assessment of Ecotoxicity
Conclusions
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