UHPLC-HRMS Suspect Screening Reveals 153 Pharmaceutical Contaminants in Tagus River Basin Ecosystems

The identification of pharmaceutically active compounds (PhACs) in aquatic locations has increased, as has concern regarding the consequences. While the number of new pharmaceuticals authorized each year that have been detected within the environment to compromise the quality and health of ecosystems has increased, comprehensive multimatrix investigations incorporating water, sediments, biota, and wastewater systems remain scarce. In a study performed by the Centre for Energy, Environmental and Technological Research (Madrid, Spain) as a response to this gap, a comprehensive HRMS-based suspect screening workflow was implemented using ultrahigh-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS). The authors of the article based on this research (published in Environmental Pollution¹) state that their study “provides one of the most comprehensive multimatrix suspect screening assessments of PhACs to date.”

While PhACs have played a major role in extending human life expectancy and improving quality of life through preventing, controlling, and treating a variety of diseases, they (as opposed to other chemical substances such as pesticides) are not subject to comprehensive environmental risk assessment requirements prior to market approval.² Their release into natural ecosystems can produce unwanted outcomes for nontarget organisms, and can change ecological processes at different trophic levels, resulting in the ecosystem’s environmental sustainability being threatened.^3,4

The researchers conducted their study using water from the Tagus River basin, the third largest basin on the Iberian Peninsula, and report that, through a multicompartment approach involving water (n=89), sediments (n=28), fish (n=24), wastewater (n=16), and sewage sludge (n=16) matrices collected during 2020-2022, this study identified 153 PhACs (136 active ingredients and 17 metabolites or transformation products). Cardiovascular, psychotropic, pain management, and other nervous system drugs were found to be the dominant therapeutic families, accounting for 63% of all identifications. Surface water contained the highest number of compounds (122), followed by effluents (85). While influents presented fewer compounds, they showed significantly higher total input (p < 0.05). Solid matrices such as sediments and sludge accumulated highly hydrophobic substances (such as telmisartan and citalopram), whereas aqueous matrices contained more polar compounds (such as tramadol) and metabolites. Fish exhibited the lowest number of PhACs (11). Regarding spatial distribution, sites more strongly influenced by human activities displayed higher (p < 0.05) normalized areas and number of compounds.¹

“These findings,” the authors continue,¹ “demonstrate the capability of HRMS-based suspect screening to detect a broad spectrum of PhACs without the need for reference standards, highlighting its value for contaminant prioritization, early warning of newly introduced substances, and supporting regulatory decision-making. This approach also provides a robust basis to guide future ecotoxicological studies and design mitigation and remediation measures such as optimizing removal treatment processes or improving sludge management practices. Additionally, this approach supports retrospective analyses that encompass extended timeframes. Integrating such methodologies into monitoring frameworks will enhance understanding of pharmaceutical behavior, facilitate the identification of high-risk substances, and contribute to the development of more effective environmental protection policies.”

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References

1. Oyano, S.; Escobar-Arnanz, J.; Navarro, I.; et al. Pharmaceutical footprint in the river ecosystem: Suspect screening approach with high-resolution mass spectrometry. Environ Pollut 2026, 127795. DOI: 10.1016/j.envpol.2026.127795
2. European Parliament. Directive 2001/83/EC of the European Parliament and of the Council of 6 November 2001 on the Community Code Relating to Medicinal Products for Human Use. European Union: Brussels, 2001. https://eur-lex.europa.eu/legalcontent/es/ALL/?uri=CELEX%3A32001L0083 (accessed 2025-10-16)
3. Kergoat, L.; Besse-Hoggan, P.; Leremboure, M.; et al. Environmental concentrations of sulfonamides can alter bacterial structure and induce diatom deformities in freshwater biofilm communities. Front Microbiol 2021, 12, 643719. DOI: 10.3389/fmicb.2021.643719
4. Oaks, J.; Gilbert, M.; Virani, M.; et al. Diclofenac residues as the cause of vulture population decline in Pakistan. Nature 2004, 427, 630-633. DOI: 10.1038/nature02317