Screening for Emerging Chemical Contaminants in Water Using LC/Q-TOF and Mass Profiler Professional Software

Importance of the topic

Municipal wastewater contains thousands of organic molecules, many unregulated and potentially harmful. Emerging contaminants at trace levels pose risks to ecosystems and human health. With increasing water scarcity and the adoption of water reuse, there is a critical need for sensitive, comprehensive analytical tools to track these compounds through treatment processes.

Objectives and Study Overview

The study demonstrates an untargeted workflow combining UHPLC-Q-TOF MS and Mass Profiler Professional (MPP) to profile organic contaminants in wastewater. It compares untreated effluent with samples treated by various ozone doses to identify compounds that are removed, resistant, or formed during ozonation.

Methodology

• Sample collection: Secondary effluent from a wastewater plant, treated with 0–5.6 mg/L ozone.
• Sample preparation: Glass fiber filtration and solid phase extraction with methanol/MTBE.
• UHPLC separation: Agilent ZORBAX Eclipse Plus column (50×2.1 mm, 1.8 µm) at 35 °C; gradient from 95 % aqueous to 100 % acetonitrile in 13 min.
• High-resolution MS: Agilent 6540 UHD Accurate-Mass Q-TOF in positive ESI mode, m/z 25–3200, resolving power ~20 000, <2 ppm mass accuracy.
• Data processing: Molecular feature extraction, recursive analysis, and multivariate statistics in MPP.

Instrumentation

• Agilent 1290 Infinity UHPLC System
• Agilent 6540 Ultra High Definition Q-TOF LC/MS
• Agilent MassHunter and Mass Profiler Professional software

Main Results and Discussion

The workflow detected 24 779 features, filtered to 9 493 high-confidence compounds after blank subtraction and recursive alignment. PCA clearly separated samples by ozone dose with tight replicate clustering. Hierarchical clustering divided compounds into:

• A,B: removed by ozone
• C,D,E: formed during ozonation
• F: resistant to oxidation

ANOVA and Tukey’s test identified 8 244 compounds whose abundances varied significantly with ozone dose. A representative compound (warfarin) from a removal cluster was successfully identified via METLIN PCDL, illustrating the potential to select indicator molecules for cluster behavior.

Benefits and Practical Applications

The presented method offers a sensitive, untargeted approach to monitor the fate of thousands of organic contaminants in water treatment. It enables the selection of key indicator compounds, provides an archive for retrospective analysis, and supports optimized process control in wastewater reuse.

Future Trends and Applications

• Integration of high-throughput data mining with expanded spectral libraries for rapid identification.
• Application to other advanced oxidation processes and combined treatment trains.
• Real-time monitoring platforms linking high-resolution MS data with process control.
• Use of retrospective Q-TOF archives to track emerging threats over time.

Conclusion

The combination of UHPLC-Q-TOF MS and MPP software provides a robust, comprehensive strategy for screening emerging contaminants in wastewater. It differentiates compound behaviors under ozonation and supports the development of targeted indicators for water quality monitoring.

References

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3. Arnold RG et al. Direct potable reuse of reclaimed wastewater: it is time for a rational discussion. Rev Environ Health. 27:197–206 (2012).
4. National Research Council. Water Reuse: Potential for Expanding the Nation's Water Supply Through Reuse of Municipal Wastewater. Washington, DC: The National Academies Press (2012).
5. Ikehata K, Gamal El-Din M, Snyder SA. Ozonation and advanced oxidation treatment of emerging organic pollutants in water and wastewater. Ozone-Science & Engineering. 30:21–26 (2008).