Determination of haloacetic acids, bromate, and dalapon in drinking water using ion chromatography coupled to high-resolution accurate-mass (IC-HRAM) mass spectrometry

Importance of the topic

Chlorinated brominated and iodinated haloacetic acids bromate and dalapon are regulated disinfection byproducts in drinking water due to health risks from disinfection processes that react with natural organic matter. Accurate monitoring is critical to meet regulatory limits and protect public health.

Objectives and study overview

This study evaluates an ion chromatography coupled to high resolution accurate mass mass spectrometry IC HRAM method using a quadrupole orbitrap instrument to identify quantify nine haloacetic acids bromate and dalapon in drinking water. Three acquisition modes full scan with data dependent tandem MS targeted selected ion monitoring and parallel reaction monitoring are compared.

Methodology and instrumentation

The analysis uses direct injection of water samples preserved with ammonium chloride into a high pressure ion chromatography system with a Dionex IonPac AS31 column kept at subambient temperature to prevent analyte degradation. Elution is performed with a gradient KOH eluent neutralized by a dynamically regenerated suppressor. Detection uses a Q Exactive HF hybrid quadrupole orbitrap mass spectrometer operating in negative electrospray ionization. Instrument methods include full scan ddMS2 tSIM ddMS2 and PRM with high resolving power accurate mass assignment. Calibration uses isotope labeled internal standards and synthetic sample matrix for method performance assessment.

Main results and discussion

All three modes achieved excellent linearity with coefficients of determination above 0.998 across relevant concentration ranges. Single laboratory limits of detection were as low as 1.1 nanograms per liter for bromate and 1 microgram per liter for haloacetic acids meeting or exceeding regulatory requirements. Precision relative standard deviations were below 8 percent and recoveries ranged from 70 to 130 percent in reagent water synthetic matrices and tap water. Full scan data allowed detection of non target anions enabling retrospective analysis without rerunning samples. Comparison of modes showed PRM offered highest sensitivity and selectivity in complex matrices while full scan provided broad screening capabilities.

Benefits and practical applications

• Simultaneous quantification of multiple regulated and unregulated disinfection byproducts with minimal sample preparation
• High sensitivity allows determination well below maximum contaminant levels
• Simplified method setup requires no extensive MS tuning or additional make up solvents
• Retrospective data mining of untargeted compounds in full scan mode

Future trends and potential uses

Advances in high resolution accurate mass instrumentation may extend regulated methods to additional anions beyond current chlorinated byproducts. Integration with automated data processing and high throughput sampling will enhance compliance monitoring in real time. Emerging software tools may further improve retrospective screening of non regulated compounds and unknowns.

Conclusion

The IC HRAM MS method using a Q Exactive instrument delivers a rapid highly sensitive accurate and flexible approach for monitoring haloacetic acids bromate and dalapon in drinking water. It meets regulatory performance criteria simplifies operation and enables both targeted quantification and non targeted screening in a single analysis.

Reference

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