Determination of Haloacetic Acids (HAA9) and Dalapon in Drinking Water According to EPA Method 552.3 on Dual Columns from a Single Injection

Importance of the topic

Haloacetic acids (HAAs) and dalapon are significant drinking water contaminants generated during disinfectant treatment. Several HAAs are regulated due to their carcinogenic potential, and additional species are monitored under emerging contaminant rules. Reliable, sensitive analytical methods are essential to ensure public health protection and regulatory compliance.

Objectives and overview

This study evaluates the performance of the Shimadzu Nexis GC-2030 system equipped with dual electron capture detectors (ECDs) and a two-way injection port adaptor for simultaneous determination of nine haloacetic acids (HAA9) and dalapon in drinking water. Analysis follows EPA Method 552.3 requirements—derivatization to methyl esters, single injection, dual-column confirmation—using Rtx-1701 and Rxi-5Sil MS capillary columns and helium carrier gas.

Methodology and instrumentation

Reagents include MTBE solvent, methyl ester standards, and internal standard (1,2,3-trichloropropane). The GC-2030 features a split/splitless inlet with a two-way splitter to deliver sample aliquots equally to two columns:

• Analytical column: SH-Rtx-1701 (30 m × 0.25 mm × 0.25 µm)
• Confirmation column: SH-Rxi-5Sil MS (30 m × 0.25 mm × 0.25 µm)

Key operating conditions:

• Injection: 1.5 µL split 1:1 (ramping to 10:1 after 0.5 min)
• Carrier gas: Helium, constant pressure mode (initial linear velocity 40 cm/s)
• Oven program: 35 °C (10 min), 3 °C/min to 65 °C, 10 °C/min to 85 °C, 20 °C/min to 205 °C (5 min)
• Detector: ECDs at 290 °C, N₂ makeup gas 45 mL/min, current 2 nA

Data acquisition and processing were performed with LabSolutions software. Calibration employed seven standards (1–50 µg/L) with quadratic fits and 1/x weighting.

Main results and discussion

System suitability tests confirmed negligible interferences in MTBE blanks (signal-to-noise >20 for 1 ppb). Calibration curves achieved r² >0.997 across all analytes. Accuracy at mid-range (10 ppb) averaged within ±5% of expected values, with precision (RSD) below 5% (n=20). At the lowest level (1 ppb), results met EPA criteria: accuracy within ±35% and RSD ≤16% (n=6). Single-injection, dual-column analysis fulfilled both quantification and confirmation requirements in one run, reducing sample consumption and turnaround time.

Benefits and practical applications

The dual-ECD, dual-column configuration streamlines compliance monitoring of HAA9 and dalapon under EPA Method 552.3. Advantages include:

• Simultaneous quantitation and confirmation from a single injection
• Improved laboratory throughput and reduced sample volume
• Maintained method robustness with standard inlet fittings and minimal dead volume
• Full compliance with regulatory accuracy and precision standards

These strengths support routine water quality laboratories, process control, and regulatory reporting.

Future trends and applications

Advances may include integration of mass spectrometric detectors for broader target lists, miniaturized sample preparation techniques to reduce solvent use, and automated data management for high-throughput monitoring. Adaptations to new EPA rules or additional emerging contaminants will further extend the utility of dual-column GC-ECD configurations.

Conclusion

The Shimadzu Nexis GC-2030 with dual ECDs and a two-way splitter delivers robust, accurate, and precise analysis of haloacetic acids and dalapon in drinking water according to EPA Method 552.3. Its single-injection, dual-column approach enhances throughput and fulfills regulatory requirements for quantification and confirmation in a single run.

Reference

1. EPA. The Fourth Unregulated Contaminant Monitoring Rule (UCMR4) Fact Sheet for Assessment Monitoring – Haloacetic Acid (HAA). 2016.
2. EPA Method 552.3. Determination of Haloacetic Acids and Dalapon in Drinking Water by Liquid-liquid Microextraction, Derivatization, and Gas Chromatography with Electron Capture Detection. EPA 815-B-03-002. 2003.