Screening and Identification of Emerging Contaminants in Wastewater Treatment Plant Effluents Using UHPLC/Q-TOF MS and an Accurate Mass Database and Library

Significance of the Topic

Emerging contaminants in wastewater effluents pose ecological and human health risks due to incomplete removal and formation of transformation products during treatment. Comprehensive screening is critical to ensure compliance with evolving water quality regulations and to protect public health in planned and unplanned water reuse scenarios.

Objectives and Study Overview

The aim was to create an accurate mass library of environmental contaminants and to apply targeted and suspect screening workflows using UHPLC Q TOF MS for the detection of pesticides pharmaceuticals personal care products their metabolites and transformation products in effluents from four municipal wastewater treatment plants. Sampling occurred over 3.5 months during the main pesticide application period.

Methodology and Instrumentation

Sample Preparation

• Composite 14 day effluent samples filtered stored at minus 20 C and directly injected

Chromatography and Mass Spectrometry

• UHPLC using Agilent 1290 Infinity system with ZORBAX RRHD SB Aq column at 40 C and gradient elution from aqueous ammonium acetate to acetonitrile
• Agilent 6550 iFunnel Q TOF MS with Dual Spray Jet Stream electrospray operated in positive and negative modes
• Data acquisition in All Ions MS MS mode with multiple collision energies and Auto MS MS with inclusion list
• Data analysis using Agilent MassHunter Qualitative and Quantitative software combined with a curated Water Screening Personal Compound Database Library containing more than 1400 compounds with accurate mass MS MS spectra

Main Results and Discussion

• Target screening of 390 compounds detected 315 in positive mode and 75 in negative mode with method detection limits in the low ng per liter range for most analytes
• Pharmaceutical residues including contrast media beta blockers analgesics and antibiotics dominated effluents of larger WWTPs at concentrations up to microgram per liter
• Pesticide profiles reflected catchment use with compounds such as DEET metolachlor azoxystrobin and isoproturon detected at tens to hundreds of nanograms per liter
• Temporal trends revealed stable pharmaceutical loads versus seasonal increases of pesticide levels during application period
• Extended suspect screening and targeted MS MS verification identified additional pharmaceuticals antidiabetics angiotensin receptor blockers industrial chemicals and perfluorinated acids with high confidence

Benefits and Practical Applications

• Simultaneous analysis of regulated and emerging contaminants in a single workflow enhances surveillance capabilities
• High resolution accurate mass data support retrospective analysis for new targets without reacquisition
• Custom spectral library enables confident compound identification through fragment coelution and library matching
• Approach is adaptable to routine monitoring research studies and water reuse quality assessment

Future Trends and Opportunities

• Expansion of spectral libraries to include novel transformation products and highly polar contaminants
• Integration of in silico fragmentation prediction tools and machine learning for non targeted screening
• Automation of sample preparation and data processing to increase throughput
• Hybrid workflows combining All Ions MS MS targeted MS MS and suspect screening for full chemical coverage
• Linking chemical occurrence data with toxicity and risk assessment models for comprehensive environmental evaluation

Conclusion

The combined UHPLC Q TOF MS and accurate mass library approach offers a powerful platform for comprehensive screening of wastewater effluents. Integration of targeted suspect and non targeted workflows with a curated compound database delivers sensitive identification and quantification of known and emerging contaminants enabling improved environmental monitoring and water quality management.

Reference

1. P Gago Ferrero et al Extended suspect and non target strategies to characterize emerging polar organic contaminants in raw wastewater with LC HRMS MS 2015
2. Directive 2013 39 EU on priority substances in the field of water policy 2013
3. US EPA method 1694 Pharmaceuticals and personal care products in water soil sediment and biosolids by HPLC MS MS 2007
4. US EPA contaminant candidate list CCL 4 2015
5. M J Gomez et al Rapid automated screening identification and quantification of organic micro contaminants and their main transformation products in wastewater and river waters using LC quadrupole TOF mass spectrometry 2010
6. T Letzel et al LC MS screening techniques for wastewater analysis and analytical data handling strategies 2015
7. C Rodriguez et al Indirect potable reuse a sustainable water supply alternative 2009
8. D H D Yang et al Sensitive screening of pharmaceuticals and personal care products in water using an Agilent 6545 Q TOF MS system 2015
9. E L Schymanski et al Non target screening with high resolution mass spectrometry critical review using a collaborative trial on water analysis 2015