NEMC: Extending the Quantitative Performance for Haloacetic acids, Bromate, and Dalapon in Water using an IC-MS/MS Workflow

Importance of the Topic

Effective monitoring of haloacetic acids, bromate and dalapon in drinking water is crucial due to health risks associated with disinfection byproducts. Regulatory standards such as U.S. EPA Method 557 drive the need for reliable analytical workflows that ensure public safety.

Objectives and Study Overview

This study aimed to develop a robust and reproducible ion chromatography–tandem mass spectrometry workflow for simultaneous quantitation of nine haloacetic acids, bromate and dalapon in water. The method targets improved sensitivity, streamlined sample handling, and compatibility with existing regulatory requirements.

Methodology

Samples were preserved with ammonium chloride and directly injected (50 µL) without further cleanup. Ion chromatography was performed on a Dionex ICS-6000 system using an electrolytically generated KOH gradient and a suppressor for clean eluents. A post-column addition of isopropyl alcohol and a matrix diversion valve prevented source contamination and enhanced desolvation. MS detection employed selected reaction monitoring in negative electrospray mode with a TSQ Fortis Plus triple quadrupole, optimized for high transmission efficiency of low-mass ions.

Used Instrumentation

• Dionex ICS-6000 Reagent-Free IC system with generator-based hydroxide eluent
• Thermo Scientific TSQ Fortis Plus triple quadrupole mass spectrometer
• Thermo Scientific TraceFinder software version 5.1
• Dionex IonPac AS31 RFIC analytical column with AG31 guard and AXP auxiliary pump

Main Results and Discussion

The workflow achieved excellent separation of target analytes from common inorganic matrix ions, with chromatographic peak area RSDs below 5% at 10 µg/L. Calibration curves were linear (r > 0.995) across 0.0625–20 µg/L. Method limits of quantitation and detection for most compounds were four-fold lower than U.S. EPA 557 values; TCAA and TBAA improved two-fold, while DBCAA matched the EPA performance. Reduced sample volume and direct method transfer without reoptimization highlight the robustness of the platform.

Benefits and Practical Applications

• Enhanced sensitivity and selectivity support regulatory compliance at lower concentration levels
• Streamlined workflow with minimal sample preparation boosts laboratory throughput
• Reduced sample volume requirements conserve reagents and reduce waste
• Direct method transfer minimizes downtime and training for existing users

Future Trends and Possibilities

• Expansion of the IC-MS/MS workflow to additional disinfection byproduct classes
• Integration with automated sample preparation and data processing for high-throughput analysis
• Advances in ion exchange materials and MS source designs to further lower detection limits
• Application of machine learning to optimize method parameters and predict matrix effects

Conclusion

This IC-MS/MS workflow provides a sensitive, reliable and reproducible solution for monitoring haloacetic acids, bromate and dalapon in drinking water. By surpassing EPA performance metrics and simplifying sample handling, it addresses both current regulatory needs and future analytical challenges.

References

• Beck JR et al. EPA Method 557 Quantitation of Haloacetic Acids, Bromate, and Dalapon in Drinking Water Using Ion Chromatography and Tandem Mass Spectrometry. Thermo Fisher Scientific Poster Note 64430, 2016.
• Wang X et al. Disinfection byproducts in drinking water and regulatory compliance: A critical review. Frontiers in Environmental Science and Engineering 2015;9:3–15. doi:10.1007/s11783-014-0734-1.
• Gilchrist ES. A review of oxyhalide disinfection by-products determination in water by ion chromatography and ion chromatography–mass spectrometry. Analytica Chimica Acta 2016;942:12–22. doi:10.1016/j.aca.2016.09.006.