Determination of Haloacetic Acids in Water by GC/μECD Using Agilent J&W DB-35ms Ultra Inert and DB-XLB Columns

Importance of the Topic

Haloacetic acids (HAAs) are common disinfection byproducts regulated due to their potential carcinogenicity.
They are formed during chlorination of natural organic matter and bromide in water and represent the second largest class of regulated DBPs after trihalomethanes.

Objectives and Study Overview

This study aimed to develop a reliable analytical workflow for nine regulated HAAs (HAA9) in water using solid-phase extraction (SPE) and gas chromatography with micro electron capture detection (GC/µECD).
A dual-column strategy employing Agilent J&W DB-35ms Ultra Inert and DB-XLB capillary columns was used to achieve confirmation and quantitation of the methylated HAA derivatives.

Methodology

• Sample extraction by Bond Elut SAX strong anion exchange cartridges, conditioning with methanol and reagent water, loading 50 mL sample at pH 5.
• Elution of HAAs with acidified methanol (10% H₂SO₄ in MeOH) followed by methylation via heating with MTBE containing internal standard.
• Phase separation with sodium sulfate and neutralization with sodium bicarbonate before GC/µECD analysis.

Instrumentation Used

• Agilent 7890A GC system with dual µECD detectors
• Agilent 7683B autosampler (5 µL syringe)
• Inert Tee split (1:1) and retention gap
• DB-35ms Ultra Inert column, 30 m × 0.25 mm, 0.25 µm film
• DB-XLB confirmation column, 30 m × 0.25 mm, 0.5 µm film
• Helium carrier gas, constant flow (3.2 mL/min)

Main Results and Discussion

• Complete separation of HAA methyl esters in under nine minutes, with coelutions on one column resolved on the orthogonal column.
• Detection limits of 0.05–0.5 ng/mL, well below regulatory maximum contaminant levels.
• Calibration linearity with R² ≥ 0.998 across a six-point procedural calibration.
• Recoveries between 82.5% and 116.5% at fortification levels of 0.2–40 ng/mL, with RSDs < 3.5%.
• Application to real water samples detected dichloroacetic acid and other low-level HAAs in tap water; no HAAs found in bottled spring water.

Benefits and Practical Applications

• High sensitivity and reproducibility for trace-level HAAs.
• Reduced solvent consumption and faster sample preparation compared to liquid-liquid extraction.
• Effective confirmatory analysis via dual-column approach.
• Adaptable workflow for routine compliance monitoring.

Future Trends and Potential Applications

• Automation and high-throughput SPE for large-scale monitoring.
• Integration of GC–MS or tandem MS for improved selectivity.
• Miniaturized extraction techniques to further reduce solvent use.
• Extension of the method to other polar DBPs and complex matrices.

Conclusion

The combination of Bond Elut SAX SPE and GC/µECD with Agilent J&W DB-35ms UI and DB-XLB columns delivers a robust, sensitive, and efficient protocol for monitoring regulated haloacetic acids in drinking water, facilitating compliance with environmental regulations.

References

1. U.S. Environmental Protection Agency. National Primary Drinking Water Regulations: Disinfectants and Disinfection Byproducts Rule. Federal Register 63(241):69406, 1998.
2. U.S. Environmental Protection Agency. Stage 1 Disinfectants and Disinfection Byproducts Rule. EPA 815-F-98-010, 1998.
3. U.S. Environmental Protection Agency. Method 552.3. Determination of Haloacetic Acids and Dalapon in Drinking Water by LLE, Derivatization, and GC/ECD. Revision 1.0, 2003.
4. U.S. Environmental Protection Agency. List of Drinking Water Contaminants & MCLs. Retrieved 2003.
5. Waseem S, Abdullah MP. Validation of SPE for Determination of Halogenated Acetic Acids in Drinking Water. Sains Malaysiana 39(2):227–231, 2010.
6. Rahman MA, Abdullah MP, Daud JM, Waseem S. Development of an Analytical Method for HAAs in Drinking Water. Malays J Anal Sci 10(1):75–80, 2006.
7. Čulík J, Horák T, Jurková M, Čejka P, Kellner V. Determination of Haloacetic Acids in Beer. ECOpole 2008.