Determination of Haloacetic Acids in Drinking Water by LC/MS/MS

Importance of the Topic

The chlorination of drinking water, while highly effective in controlling waterborne pathogens, generates disinfection by-products such as haloacetic acids (HAAs), bromate, and chlorate. These compounds pose potential health risks even at trace levels. Sensitive, rapid, and robust analytical methods are essential to monitor compliance with regulatory limits and to safeguard public health.

Objectives and Study Overview

This study presents the development and validation of a direct-injection liquid chromatography–tandem mass spectrometry (LC/MS/MS) method for the simultaneous determination of nine HAAs, bromate, and chlorate in drinking water. The method targets faster analysis times and lower detection limits compared to the standard US EPA Method 557.

Methodology and Used Instrumentation

A direct injection workflow eliminates sample filtration and concentration steps. Key instrumentation and conditions include:

• Agilent 1290 Infinity II LC system with high-speed pump, multisampler, and multicolumn thermostat
• Agilent InfinityLab Poroshell 120 HPH-C18 column (3.0 × 150 mm, 2.7 µm) at 40 °C
• Mobile phase: water/0.05% formic acid (A) and methanol (B) with a 12 min gradient, 0.25 mL/min
• Agilent 6470A triple quadrupole MS with AJS electrospray source in negative mode, dynamic MRM acquisition
• Monochloroacetic acid-2-13C as internal standard at 5 µg/L

Main Results and Discussion

The method achieves complete separation of all analytes within 8 minutes and a total runtime of 12 minutes—approximately five times faster than EPA 557. Limits of detection range from 0.003 to 0.04 µg/L, well below EU and US regulatory requirements. Calibration was linear (R² > 0.997) from 0.02 to 100 µg/L. Mean recoveries in spiked drinking water ranged from 85.2% to 107.7% with no significant matrix suppression. The method also proved robust in a high-ionic synthetic matrix.

Benefits and Practical Applications

The direct injection LC/MS/MS protocol offers:

• Enhanced laboratory throughput and minimal sample preparation
• Improved sensitivity and selectivity for routine monitoring
• Compliance with stringent regulatory limits for HAAs, bromate, and chlorate
• Applicability in municipal and industrial quality-control laboratories

Future Trends and Opportunities

Potential developments include automated sample handling to increase throughput further, expansion of analyte panels to cover additional disinfection by-products, and adaptation to portable or on-site MS systems for real-time water quality screening.

Conclusion

The proposed direct-injection LC/MS/MS method efficiently quantifies nine HAAs, bromate, and chlorate in drinking water with high speed, sensitivity, and robustness. Its performance surpasses existing protocols, making it a valuable tool for compliance monitoring and public health protection.

Reference

• Agilent Technologies. Determination of Haloacetic Acids in Drinking Water by LC/MS/MS. Application Note 5994-1275EN, 2019.
• U.S. Environmental Protection Agency. Method 557: Determination of Haloacetic Acids, Bromate, and Dalapon in Drinking Water by Ion Chromatography–MS/MS.
• Richardson SD. Disinfection By-Products and Other Emerging Contaminants in Drinking Water. Trends Anal. Chem. 2003;22:666–684.
• Stevens AA, et al. Chlorination of Organics in Drinking Water. Journal AWWA. 1976;68:615–620.
• Liang L, Singer PC. Factors Influencing the Formation and Distribution of Haloacetic Acids in Drinking Water. Environ. Sci. Technol. 2003;37:2920–2928.