Improved Extraction and Analysis of Haloacetic Acids from Water Samples

Significance of the Topic

Water chlorination generates haloacetic acids that pose health risks such as carcinogenicity and reproductive toxicity. Monitoring their levels in drinking water is essential to protect public health and comply with regulatory standards.

Objectives and Study Overview

This work set out to refine the EPA Method 552.1 extraction procedure by introducing a high-capacity polymeric strong anion exchange SPE sorbent (Strata-X-A). Primary aims included

• Reducing solvent consumption and handling time
• Eliminating the risk of sorbent dry-out
• Maintaining or improving analyte recovery and reproducibility

Methodology and Instrumentation

Samples of 100 mL water spiked with 10–100 µg/L of seven haloacetic acids underwent SPE using 100 mg Strata-X-A cartridges. Conditioning and elution steps were optimized to minimize solvent volumes. Eluates were derivatized with MTBE at 50 °C, neutralized with sodium bicarbonate, and spiked with 1,2,3-trichloropropane as internal standard. Analytical separation employed a dual-column GC/ECD setup:

• Zebron ZB-XLB-HT Inferno and ZB-MR2 columns (30 m × 0.32 mm × 0.25 µm) in parallel
• Helium carrier gas at 2.3 mL/min, pulsed injection at 250 °C
• Multistep oven program from 30 °C to 150 °C
• Electron capture detector at 340 °C

Main Results and Discussion

The optimized protocol achieved absolute recoveries between 89 % and 97 % (RSD 1.3–9.5 %) for all regulated haloacetic acids. Compared to conventional Bio-Rad AG 1-X8 resin, total solvent usage was reduced by approximately 70 mL per sample. Dual-column GC provided clear peak separation and reliable compound confirmation.

Benefits and Practical Applications

Key advantages include

• Prepacked, dry-out resistant cartridges for higher sample throughput
• Lower operational costs through reduced solvent purchase and disposal
• Compliance with regulatory recovery and precision requirements
• Applicability in routine environmental and industrial water quality testing

Future Trends and Potential Applications

Emerging SPE materials with mixed-mode retention could extend this approach to a wider range of disinfection by-products. Automation of SPE and coupling with mass spectrometry will enhance sensitivity and throughput. Continued focus on green chemistry will drive further reductions in solvent use and alternative derivatization methods.

Conclusion

The Strata-X-A based SPE protocol offers a robust alternative to the traditional EPA 552.1 method. It delivers high recoveries, reproducible results, and significant solvent savings while eliminating sorbent dry-out, making it well suited for modern water quality laboratories.

Reference

Hodgeson J.W.; Becker D. EPA Method 552.1: Determination of Haloacetic Acids. U.S. Environmental Protection Agency; August 1992.