Fast Determination of Haloacetic Acids in Drinking Water According to EPA Method 552.3 using Rtx-CLPesticides Columns and Hydrogen Carrier Gas

Significance of the Topic

The analysis of haloacetic acids (HAAs) in drinking water is crucial due to their status as regulated disinfection byproducts with carcinogenic potential. Monitoring nine HAAs (HAA9) and dalapon helps public health compliance under EPA Method 552.3 and supports water treatment oversight.

Objectives and Study Overview

This work aimed to evaluate a faster GC method for determining HAA9 and dalapon in water by:

• Replacing conventional Rtx-1701 and Rxi-5Sil-MS columns with Restek Rtx-CLPesticides (primary) and Rtx-CLPesticides2 (confirmation).
• Using hydrogen as a carrier gas to reduce run time and cost.
• Validating performance against EPA Method 552.3 criteria.

Methodology and Used Instrumentation

A Shimadzu GC-2030 system with dual split/splitless inlets, dual electron capture detectors (ECD-exceed), and dual autosamplers was employed. Samples were derivatized to methyl esters and extracted into MTBE with a 10× concentration factor. Key instrument details:

• Primary column: Rtx-CLPesticides, 30 m × 0.32 mm × 0.32 µm.
• Confirmation column: Rtx-CLPesticides2, 30 m × 0.32 mm × 0.25 µm.
• Carrier gas: Hydrogen at constant linear velocity (25 cm/s).
• GC temperature program: 35 °C (4 min), ramp 10 °C/min to 250 °C (1 min).

Main Results and Discussion

The dual-column CLP set achieved a ~33 % reduction in total run time for the last eluting HAA (TBAA) compared with the EPA column set (from ~27 min to ~16 min). Calibration curves (1–50 ppb) showed r2 > 0.995 with 1/A weighting. Calibration accuracy fell within ±21 % at 1 ppb and ±10 % at higher levels, meeting EPA requirements. Solvent blanks displayed no interfering peaks above one-third of the reporting limit. Additionally, the Rtx-CLP column resolved 20 organochlorine pesticides in under 5 min, demonstrating system versatility.

Benefits and Practical Applications of the Method

This approach offers:

• Faster throughput and lower per-sample cost due to hydrogen carrier gas and shorter run times.
• Regulatory compliance for HAA5 and HAA9 monitoring.
• Single GC setup adaptable for both HAA and organochlorine pesticide analyses.

Future Trends and Opportunities

Advances may include further column chemistry refinements to improve selectivity, integration with automated sample preparation, and extension to other disinfection byproducts. Hydrogen-based methods align with sustainability goals by reducing helium consumption.

Conclusion

The Rtx-CLPesticides/Rtx-CLPesticides2 column set with hydrogen carrier gas provides a reliable, time-saving alternative for EPA Method 552.3 analysis of HAAs and dalapon. The system meets all quality criteria while expanding laboratory flexibility to multiple environmental assays.

References

1. EPA Method 552.3: Haloacetic Acids and Dalapon in Drinking Water by GC-ECD, 2003.
2. EPA Unregulated Contaminant Monitoring Rule 4 (UCMR4) Fact Sheet, 2016.
3. Shimadzu Application News GC-2002, Determination of HAAs with Hydrogen Carrier Gas, 2020.
4. EPA Method 608.3: Organochlorine Pesticides and PCBs by GC/HSD, 2014.
5. SW-846 Test Method 8081B: Organochlorine Pesticides by GC, EPA, 2007.