ArabLab: Analysis of Disinfection Byproducts by Ion Chromatography

Importance of the Topic

Disinfection byproducts (DBPs) such as bromate, chlorite, chlorate and haloacetic acids form during water treatment and pose significant health risks if not monitored accurately. Ion chromatography (IC) methods offer sensitive, selective and potentially automatable analysis of trace DBPs, supporting regulatory compliance and public health protection.

Objectives and Study Overview

• Explain basic principles and practical applications of modern IC for DBP analysis.
• Evaluate single-channel IC, two-dimensional IC and IC coupled to mass spectrometry for key DBPs including bromate and HAA fractions.

Methodology

• Single-channel IC using suppressed conductivity detection with carbonate or hydroxide eluents to quantify bromate and chlorite at low µg/L levels.
• Two-dimensional IC (2D-IC) employing a large-loop first dimension for sample cleanup and a capillary second dimension for high-sensitivity separation.
• IC-MS/MS for direct HAA detection, eliminating liquid-liquid extraction and derivatization steps.
• Standard EPA methods (300-series for bromate, 552.3 and 557 for HAAs) served as benchmarks.

Used Instrumentation

• Thermo Scientific Dionex ICS-5000+ HPIC system with RFIC capabilities
• Eluent generators (EGC 500, capillary cartridges) and AERS/ACES suppressors
• Dionex IonPac columns (AS9-HC, AS19, AS24, AS26) and concentrator columns (IonSwift MAC-200)
• Autosampler and dual pump configurations for 2D-IC
• Mass spectrometer interface for IC-MS/MS detection

Main Results and Discussion

• Bromate detection limits as low as 0.014 µg/L with IC-ICP/MS; 2D-IC achieved sub-µg/L MDLs and effective matrix separation in simulated waters.
• 2D-IC for HAA9 attained lowest concentration minimum reporting levels (LCMRLs) comparable to EPA Method 557.
• Recoveries of HAAs ranged from 87 % to 112 % across reagent water and natural matrices with RSD below 1 %.
• 2D-IC matched or exceeded performance of EPA Methods 552.3 and 557 while eliminating extensive sample prep.

Benefits and Practical Applications of the Method

• Direct injection reduces sample handling, avoids derivatization and lowers labor time.
• 2D-IC enhances sensitivity and selectivity, effectively separating analytes from complex matrices.
• Single-system solution streamlines workflows for monitoring compliance under the Safe Drinking Water Act.
• Applicable to both regulated DBPs (e.g., TTHMs, HAAs, bromate) and emerging contaminants.

Future Trends and Opportunities

• Regulatory approval of 2D-IC methods for additional DBPs (perchlorate, hexavalent chromium) is in progress.
• Further integration with high-resolution MS for structural confirmation and non-target screening.
• Advances in microfluidics and capillary IC could enable field-deployable platforms.
• Data automation and cloud-based management will streamline real-time quality control.

Conclusion

IC techniques, especially two-dimensional configurations and MS coupling, provide robust, sensitive and streamlined analysis of disinfection byproducts. Adoption of these methods reduces sample prep, improves accuracy and supports regulatory compliance for safe drinking water surveillance.

References

• EPA Method 300.0(B), 300.1, 302, 317.0, 321.8, 326.1
• EPA Method 552.3 and 557 for haloacetic acids
• Thermo Fisher Scientific White Paper on IC and RFIC technology