Determination of oxyhalides and bromide in drinking water using a compact ion chromatography system coupled with a single quadrupole mass spectrometer

Importance of the topic

Maintaining safe drinking water requires controlling disinfection byproducts such as chlorite, chlorate and bromate, which can pose health risks even at trace levels. Bromate is classified as a potential human carcinogen with regulatory limits of 3–10 µg/L globally.

Goals and Overview

This study develops a robust method to simultaneously quantify oxyhalides and bromide in drinking water by coupling a compact eluent‐generation ion chromatography system with a single quadrupole mass spectrometer (IC‐MS), leveraging both suppressed conductivity and mass spectrometric detection.

Used Instrumentation

• Dionex Integrion HPIC system with eluent generator, pump, degasser and conductivity detector
• ISQ EC single quadrupole mass spectrometer with HESI-II electrospray interface
• AXP-MS auxiliary pump for suppressor regeneration
• Thermo Scientific AS-AP autosampler and PEEK Viper fittings

Methodology

A Thermo Scientific IonPac AS19-4 µm column (2 × 250 mm, 30 °C, 0.25 mL/min) was used with automated hydroxide eluent generation. An AERS 500e suppressor in external water mode removed eluent cations before detection. A 6-port diverter valve directed flow to MS only during analyte elution (5–18 min). Conductivity detection followed EPA Method 300.1 Part B. MS operated in negative electrospray ionization SIM mode, monitoring target ions for chlorite, bromate, chlorate and bromide with an ¹⁸O₃-bromate internal standard.

Main Results and Discussion

Baseline separation of all common anions and DBPs was achieved within 30 min. MS detection enhanced limits of detection by 5–10× (0.03–0.04 µg/L) relative to conductivity, while CD provided a linear range up to 500 µg/L. Dual detection enabled sensitive quantification below 10 µg/L by MS and reliable quantification above 10 µg/L by CD. MS also resolved co-eluting interferences and confirmed analyte identity. Recoveries in bottled and tap water ranged from 80–105%, with precision better than 2% RSD for peak area and <0.1% for retention time.

Benefits and Practical Applications

• High sensitivity for regulated disinfection byproducts
• Simultaneous quantification and confirmation of oxyhalides and bromide
• Flexible workflow for both low and high concentration samples
• Ensures compliance with global drinking water standards

Future Trends and Applications

Future enhancements may include high-resolution MS for non‐target screening of emerging DBPs, automated inline sample preparation to boost throughput, portable IC-MS platforms for field monitoring, and integration with advanced data analytics for real‐time water quality management.

Conclusion

The combined IC-MS method delivers a sensitive, selective and practical solution for accurate determination of chlorite, bromate, chlorate and bromide in drinking water, meeting stringent regulatory requirements and streamlining laboratory workflows.

Reference

1. Thermo Fisher Scientific. Application Note 72886: Determination of oxyhalides and bromide in drinking water by IC-MS.
2. US EPA Method 300.1 Part B: Determination of inorganic oxyhalides in drinking water.
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