Determination of Haloacetic Acids and Acrylamide in Drinking Water by Direct Injection Using Liquid Chromatography-Tandem Quadrupole Mass Spectrometry

Importance of the Topic

Haloacetic acids (HAAs) are by-products of water chlorination with potential carcinogenic effects and acrylamide is a known human carcinogen that can enter water supplies via industrial contamination. Monitoring these contaminants is critical to ensure drinking water safety and compliance with evolving regulations.

Objectives and Study Overview

This study demonstrates a rapid direct injection reversed-phase LC-MS/MS method for simultaneous determination of nine haloacetic acids and acrylamide in drinking water. It aims to exceed the limits set by the EU Drinking Water Directive 2020 and improve laboratory efficiency by eliminating extensive sample preparation.

Methodology

Water samples (tap and mineral) were preserved with ammonium chloride and spiked at three concentration levels for HAAs (2, 4, 30 µg/L) and acrylamide (0.02, 0.04, 0.08 µg/L). Samples were acidified with formic acid and analyzed by direct injection (10 µL) without derivatization. Calibration was matrix-matched for mineral water, and acrylamide quantification used an isotopically labeled internal standard (acrylamide-d3).

Instrumentation Used

• LC system: ACQUITY UPLC I-Class PLUS with HSS C18 SB column (2.1 x 100 mm, 1.8 µm)
• Mass spectrometer: Xevo TQ-S micro operating in ESI+ for acrylamide and ESI− for HAAs
• Data acquisition: Multiple Reaction Monitoring (MRM) via MassLynx v4.2

Main Results and Discussion

• Average recoveries ranged from 97 to 102% with RSDs below 8% across all spike levels.
• Calibration curves were linear (R2 > 0.996) with residuals < 15%.
• Limits of quantification: 0.5 µg/L for individual HAAs and 0.02 µg/L for acrylamide, surpassing EU limits (60 µg/L sum HAA, 0.1 µg/L acrylamide).
• 270 consecutive injections of a 2 µg/L HAA and 0.1 µg/L acrylamide standard showed RSD < 10% for peak area and < 1% for retention time, demonstrating method robustness.

Benefits and Practical Applications

• Simultaneous analysis of HAAs and acrylamide increases throughput and reduces turnaround time.
• No need for derivatization, pre-concentration, or specialized ion chromatography, simplifying workflows.
• Short run time (under 8 minutes) allows high sample throughput in routine monitoring.

Future Trends and Applications

• Integration with online water quality monitoring systems for real-time assessment.
• Expansion of analyte panels to include emerging disinfection by-products.
• Adoption of high-resolution mass spectrometry for suspect screening and non-target analysis.
• Automation of sample handling to further improve laboratory efficiency and reproducibility.

Conclusion

The direct injection LC-MS/MS method on an ACQUITY UPLC I-Class PLUS and Xevo TQ-S micro platform offers a fast, robust, and sensitive approach for monitoring nine haloacetic acids and acrylamide in drinking water. It exceeds current regulatory requirements and supports laboratories in delivering reliable data without extensive sample preparation.

Reference

1. US EPA Method 557, Determination of Haloacetic Acids and Dalapon by IC-ESI-MS/MS, 2009.
2. Nikolaou et al., Water Research, 2002, 36:1089–1094.
3. WHO Guidelines for Drinking-Water Quality, First Addendum, 2017.
4. EU Directive 2020/2184 on Drinking Water Quality, 2020.
5. US EPA National Primary Drinking Water Regulations, 2020.