Abstract
This study aimed to identify antimicrobial contaminants in the aquatic environment with effect-directed analysis. Wastewater influent, effluent, and surface water (up- and downstream of the discharge location) were sampled at two study sites. The samples were enriched, subjected to high-resolution fractionation, and the resulting 80 fractions were tested in an antibiotics bioassay. The resulting bioactive fractions guided the suspect and nontargeted identification strategy in the high-resolution mass spectrometry data that was recorded in parallel. Chemical features were annotated with reference databases, assessed on annotation quality, and assigned identification confidence levels. To identify antibiotic metabolites, Phase I metabolites were predicted in silico for over 500 antibiotics and included as a suspect list. Predicted retention times and fragmentation patterns reduced the number of annotations to consider for confirmation testing. Overall, the bioactivity of three fractions could be explained by the identified antibiotics (clarithromycin and azithromycin) and an antibiotic metabolite (14-OH(R) clarithromycin), explaining 78% of the bioactivity measured at one study site. The applied identification strategy successfully identified antibiotic metabolites in the aquatic environment, emphasizing the need to include the toxic effects of bioactive metabolites in environmental risk assessments.
Original language | English |
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Article number | 138093 |
Pages (from-to) | 1-10 |
Number of pages | 10 |
Journal | Chemosphere |
Volume | 320 |
Early online date | 7 Feb 2023 |
DOIs | |
Publication status | Published - Apr 2023 |
Bibliographical note
Funding Information:The authors gratefully acknowledge Dr. Wilfried Niessen (hyphen MassSpec) for the assistance in the interpretation of the fragmentation spectra. This work is part of the research program RoutinEDA with project number 15747, which is (partly) financed by the Dutch Research Council (NWO).
Publisher Copyright:
© 2023 The Authors
Keywords
- Antibiotic
- Bioassay
- Clarithromycin
- Effect-directed analysis
- Metabolite
- Nontarget screening