Haloacetic Acid Analysis by the Agilent Intuvo 9000 Dual ECD System

Significance of the Topic

Haloacetic acids (HAAs) are common disinfection by-products in chlorinated drinking water. Due to their potential health risks and strict regulatory limits set by agencies such as the US EPA and Chinese national standards, sensitive and reliable analytical methods are essential for routine monitoring. Gas chromatography with electron capture detection (GC-ECD) offers high selectivity for HAA methyl esters but faces challenges in balancing throughput, reproducibility, and detection limits.

Objectives and Study Overview

This work evaluated the performance of the Agilent Intuvo 9000 GC system equipped with dual ECD detectors and dual analytical columns for the analysis of nine HAA methyl esters (HAA9) plus dalapon. Study goals included assessing linearity, repeatability, and detection limits under both nitrogen and helium carrier gases following HJ 758-2015 and EPA 552.3 guidelines. Additionally, a rapid analysis method using shortened 15 m columns was developed to improve sample throughput.

Instrumentation

• GC System: Agilent Intuvo 9000 with single split/splitless inlet, inlet splitter, dual columns, dual ECDs.
• Autosampler: Agilent 7650A automatic liquid sampler.
• Columns (30 m): Agilent J&W DB-1701 (30 m × 0.25 mm, 0.25 µm) and DB-5ms UI (30 m × 0.25 mm, 0.25 µm).
• Columns (15 m): Same stationary phases at 15 m length for fast mode.
• Detector Conditions: ECD at 300 °C with 30 mL/min N₂ make-up flow.
• Carrier Gases: Nitrogen or helium at constant flow; method translation tool used for flow rate adjustment when switching to 15 m columns.
• Derivatization: HAA esters prepared in MTBE with internal standard 1,2,3-trichloropropane.

Main Results and Discussion

• Linearity: Excellent calibration over 2–500 µg/L with R² ≥ 0.995 for all analytes on primary DB-1701 column.
• Retention Time Precision: RSD% ranged from 0.001 to 0.074% on 30 m and 15 m columns with both gases.
• Quantitation Precision: RSD% between 0.3 and 3.4%, slightly higher for early-eluting MCAA.
• Limits of Detection: Using helium, LODs ranged from 0.02 to 0.67 µg/L; with nitrogen, from 0.04 to 1.20 µg/L.
• Fast Mode: 15 m columns reduced run times by ~50% (to ~10 min) with acceptable resolution (baseline separation for most analytes; resolution of 1.3 for dalapon/DCAA).

Benefits and Practical Applications

The Intuvo 9000 dual ECD setup delivers robust performance for regulated HAA analysis, offering flexible carrier gas options and straightforward method translation for varying throughput needs. High reproducibility, low detection limits, and rapid run times make this approach suitable for routine QA/QC in water utilities, environmental laboratories, and regulatory agencies.

Future Trends and Applications

Continued advances may include integrated on-line derivatization, further miniaturized columns for ultra-fast screening, coupling with tandem mass spectrometry for enhanced selectivity, and automated workflows for high-throughput monitoring. Expansion to other disinfection by-product classes and portable GC-ECD platforms could enable field-based compliance testing.

Conclusion

The Agilent Intuvo 9000 dual ECD system provides a sensitive, reproducible, and adaptable platform for HAA methyl ester analysis in drinking water. The dual-column, dual-gas approach meets regulatory requirements and offers significant productivity gains when using shortened columns.

References

• Lucio do Lago, C.; Daniel, D. Determination of Haloacetic Acids in Drinking Water by LC/MS/MS. Agilent Technologies application note, publication number 5994-1275EN, 2019.
• HJ 758-2015. Water quality – Determination of haloacetic acids – Gas chromatography. Ministry of Ecology and Environment of the People’s Republic of China.
• EPA 552.3. Determination of Haloacetic Acids and Dalapon in Drinking Water by Liquid-Liquid Micro Extraction, Derivatization, and Gas Chromatography with Electron Capture Detection, EPA 815-B-03-002, Revision 1.0, July 2003.