Identification of biotransformation products of citalopram formed in activated sludge

Vasiliki G Beretsou; Aikaterini K Psoma; Pablo Gago-Ferrero; Reza Aalizadeh; Kathrin Fenner; Nikolaos S Thomaidis

doi:10.1016/j.watres.2016.07.029

Identification of biotransformation products of citalopram formed in activated sludge

Water Res. 2016 Oct 15:103:205-214. doi: 10.1016/j.watres.2016.07.029. Epub 2016 Jul 14.

Authors

Vasiliki G Beretsou¹, Aikaterini K Psoma¹, Pablo Gago-Ferrero¹, Reza Aalizadeh¹, Kathrin Fenner², Nikolaos S Thomaidis³

Affiliations

¹ Laboratory of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15771, Athens, Greece.
² Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland; Department of Environmental Systems Science (D-USYS), ETH Zürich, 8092, Zürich, Switzerland.
³ Laboratory of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15771, Athens, Greece. Electronic address: ntho@chem.uoa.gr.

PMID: 27459150
DOI: 10.1016/j.watres.2016.07.029

Abstract

Citalopram (CTR) is a worldwide highly consumed antidepressant which has demonstrated incomplete removal by conventional wastewater treatment. Despite its global ubiquitous presence in different environmental compartments, little is known about its behaviour and transformation processes during wastewater treatment. The present study aims to expand the knowledge on fate and transformation of CTR during the biological treatment process. For this purpose, batch reactors were set up to assess biotic, abiotic and sorption losses of this compound. One of the main objectives of the study was the identification of the formed transformation products (TPs) by applying suspect and non-target strategies based on liquid chromatography quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS). The complementary use of reversed phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC) for the identification of polar TPs, and the application of in-house developed quantitative structure-retention relationship (QSRR) prediction models, in addition to the comprehensive evaluation of the obtained MS/MS spectra, provided valuable information to support identification. In total, fourteen TPs were detected and thirteen of them were tentatively identified. Four compounds were confirmed (N-desmethylCTR, CTR amide, CTR carboxylic acid and 3-oxo-CTR) through the purchase of the corresponding reference standard. Probable structures based on diagnostic evidence were proposed for the additional nine TPs. Eleven TPs are reported for the first time. A transformation pathway for the biotransformation of CTR was proposed. The presence of the identified TPs was assessed in real wastewater samples through retrospective analysis, resulting in the detection of five compounds. Finally, the potential ecotoxicological risk posed by CTR and its TPs to different trophic levels of aquatic organisms was evaluated by means of risk quotients.

Keywords: Citalopram; HILIC; LC-QTOF-MS; Metabolites; Retrospective analysis; Transformation products.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biotransformation
Citalopram
Retrospective Studies
Sewage / chemistry*
Tandem Mass Spectrometry*
Water Pollutants, Chemical / chemistry

Substances

Sewage
Water Pollutants, Chemical
Citalopram