Meeting the requirements of US and European water standards

Significance of the Topic

Ensuring the safety of drinking, surface and ground waters under U.S. and European regulations is an ongoing challenge as analytical requirements become more stringent and contaminant lists continue to grow. Modern water analysis must address legacy pollutants (e.g., trace metals, haloacetic acids, semivolatiles) as well as emerging contaminants (e.g., per- and polyfluoroalkyl substances, disinfection by-products, nitrosamines, endocrine-disrupting compounds, pharmaceuticals, flame retardants). Achieving the low parts-per-trillion (ppt) to parts-per-quadrillion (ppq) detection limits required by EPA and EU directives demands innovative sample preconcentration, highly selective chromatography, and cutting-edge mass spectrometry, all while maximizing laboratory throughput and minimizing costs.

Study Objectives and Overview

This compilation of studies demonstrates how modern analytical platforms—ion chromatography tandem mass spectrometry (IC-MS/MS), gas chromatography coupled with triple quadrupole or Orbitrap mass spectrometry (GC-MS/MS, GC-HRAM), liquid chromatography-MS/MS (LC-MS/MS), and inductively coupled plasma optical emission and mass spectrometry (ICP-OES, ICP-MS)—can be configured and validated to meet regulatory compliance for a broad spectrum of water contaminants. Key goals include:

• Developing direct, cryogen-free methods for drinking‐water disinfection by-products (haloacetic acids, nitrosamines, PBDEs, iodo-DBPs).
• Optimizing automated headspace GC methods for gasoline range organics.
• Implementing high‐throughput IC-MS/MS for US and EU regulated anions and cations.
• Leveraging microfluidic two-dimensional GC for air toxics and ozone precursors in ambient air.
• Demonstrating ICP-OES/ICP-MS techniques for multielement analysis in wastewater and estuarine waters.
• Validating LC-MS/MS workflows for Per- and Polyfluoroalkyl Substances (PFAS) and hormones at low ppt levels.
• Assessing method performance using EPA or ISO protocol, including detection limits, linearity, reproducibility, and recovery in real matrices.

Methods and Instrumentation

Sample collection and preservation varied by matrix (drinking water, reclaimed water, surface or ground water, wastewater, sediments, air). Key sample preparation approaches included:

• Solid phase extraction (SPE) and on-line SPE preconcentration for polar organics (PFAAs, hormones, nitrosamines).
• Automated headspace sampling for volatile organics (haloacetic acids, SVOCs, GRO).
• Thermal desorption with cryogen-free water removal for air VOCs.
• Soxhlet or accelerated solvent extraction followed by deactivated alumina cleanup for PBDEs and nitrosamines.
• Dilution with argon gas in high salinity (brackish/estuarine) waters for ICP-MS.

Chromatographic separation was performed with specialized columns: ion-exchange IC columns for anions/cations; polar and nonpolar GC columns for volatiles and semivolatiles; reversed-phase LC columns for PFAS, hormones, and pharmaceuticals. Detection was carried out on:

• Thermo Scientific IC-MS/MS systems with integrated suppressors for low-conductivity eluents.
• Thermo Scientific GC-MS/MS systems (ISQ 7000, Trace 1310-TSQ series) with helium saver injectors, high-throughput PTV in split/splitless mode, and HRAM Orbitrap detectors (Q Exactive, Exactive GC) for non-targeted screening.
• Thermo Scientific LC-MS/MS systems (Vanquish-TSQ Altis/Q Exactive) for trace PFAS and hormonal analyses using SIM/SRM and PRM modes.
• Thermo Scientific ICP-OES (iCAP 7400 Duo, iCAP RQ, iCAP 7000) and ICP-MS (iCAP RQ, ISQ 7000) for multielement profiling at low µg/L and ng/L levels, with axial/radial views and kinetic energy discrimination.

Main Results and Discussion

Sensitivity and detection limits achieved included:

• Haloacetic acids: detection limits < 0.2 µg/L and run times < 35 min by IC-Orbitrap MS/MS.
• SVOCs: 0.2–200 ppm range in 66 s using GC-MS/MS with split/splitless modes.
• Ozone precursors and air toxics: complete suite in a 52-min GC-MS run without cryogen, retention-time RSD < 0.05%.
• PFAS (EPA 537): LCMRLs < 1 ng/L in full-scan HRAM and SRM modes; recoveries 80–120% in spiked matrices.
• Nitrosamines (EPA 521): LOQs 0.1–0.5 ng/L in drinking water with advanced EI source on TSQ 9000.
• Gasoline range organics: LODs 0.1–7.0 µg/L, recoveries 80–120% by headspace GC-FID.
• Trace metals (EPA 200.8): 52 analyses/hour using automated organic/inorganic workflows on ICP-MS with argon dilution.
• PBDEs and DBPs: separation of 27 congeners in < 11 min, LOQs as low as 50 fg on column, mass accuracy < 2 ppm.
• Hormones (EPA 539): LCMRLs 0.1–0.5 ng/L using PRM full scan on Q Exactive Orbitrap.

All methods demonstrated linearity (R2 > 0.995), reproducibility (RSD < 10% at low levels), and recoveries within established quality control limits.

Benefits and Practical Applications

These advanced workflows offer:

• Compliance with stringent EPA and EU regulations (SDWA, WFD, UCMR, MCERTS).
• High sample throughput using automation, overlapping cycles, and efficient chromatography.
• Minimal sample preparation and cryogen requirements.
• Simultaneous targeted quantitation and non‐targeted screening.
• Full regulatory data packages for method validation and accreditation.
• Automated QC monitoring and data review with integrated LIMS connectivity.

Future Trends and Potential Uses

Emerging areas include:

• Expanded non‐targeted analysis for unknown contaminants using HRAM and spectral libraries.
• In-field monitoring with portable GC/MS and IC systems.
• Integration of machine learning for peak identification and trend prediction.
• Advanced specimen matrices such as biota and sediment.
• Development of integrated workflows for simultaneous multi‐class contaminant analysis.

Conclusion

By leveraging the latest generation of chromatographic and mass spectrometric technologies, environmental laboratories can meet and exceed the requirements for trace analysis of both regulated and emerging contaminants across a wide range of water matrices, ensuring safe water supplies and compliance with evolving regulatory standards.

Reference

1. EPA Method 537. Determination of Select PFAS in drinking water by SPE-LC-MS/MS.
2. Water Framework Directive (2000/60/EC) and QA/QC Directive for WFD (2009/90/EC).
3. EPA UCMR 3, Contaminant Monitoring.
4. Pan et al. Identification of 9 HAAs in water by IC-Orbitrap MS. J. Chromatogr. A 2018.
5. E. Richardson et al. Disinfection By-Products in Drinking Water. Mutat. Res. 2007.
6. EPA Method 521. Determination of Nitrosamines in Drinking Water by GC-MS.
7. ASTM D7979. Determination of PFAS in Water by LC-MS/MS.
8. Corcoran et al. GC-Orbitrap MS for PBDEs. Anal. Bioanal. Chem. 2017.
9. Parker & Park. GC-MS/MS for SVOC. Thermo Fisher Scientific Application Note 10522.