Determination of Bromate in Drinking and Mineral Water by Isocratic Ion Chromatography with a Hydroxide Eluent

Importance of the Topic

Disinfection of drinking water is necessary to protect public health but can produce harmful byproducts such as bromate when bromide in source water is oxidized by ozone. Bromate is classified as a potential human carcinogen and regulated worldwide, often limited to 10 micrograms per liter. Reliable, sensitive analysis of bromate and related oxyhalides in drinking and mineral water is essential for regulatory compliance and consumer safety.

Objectives and Study Overview

This study demonstrates an isocratic ion chromatography (IC) method using a hydroxide eluent for simultaneous determination of bromate, chlorite, and chlorate in drinking and mineral water. The method aims to simplify analysis by avoiding gradient elution, achieve low detection limits below regulatory thresholds, and compare reagent free and manually prepared eluents.

Methodology and Instrumentation

The analytical separation employs a Dionex IonPac AS19 analytical column with AG19 guard at 25 °C, 1.0 mL/min flow rate, and 200 µL injection volume. An isocratic 20 mM hydroxide eluent is generated either by an RFIC system or prepared manually. Suppressed conductivity detection is performed with a Dionex ASRS ULTRA II suppressor at 60 mA. Instrumentation:

• Thermo Scientific Dionex ICS-1000 Ion Chromatography System or ICS-2000 for RFIC applications
• Dionex EluGen II EGC-KOH cartridge for eluent generation
• Dionex Chromeleon Chromatography Data System

Main Results and Discussion

Under isocratic conditions, nine common anions including fluoride, chlorite, bromate, chloride, nitrite, chlorate, bromide, nitrate, and sulfate were resolved within 15 minutes. Minimum detection limits for bromate were 0.14 µg/L with RFIC eluent and 0.16 µg/L with manually prepared hydroxide, demonstrating similar sensitivity but improved baseline stability with RFIC. Calibration curves for all analytes were linear with correlation coefficients above 0.999. Method accuracy was confirmed by spiking mineral water with 10 µg/L of chlorite, bromate, and chlorate, yielding recoveries of 96 to 111 percent, with slightly better performance using RFIC eluent.

Benefits and Practical Applications

The isocratic hydroxide method offers simplicity, rapid turnaround, and robust suppression detection without complex gradient programming. It meets regulatory requirements for low µg/L bromate determination and is compatible with high ionic strength samples such as mineral water. The reagent free option reduces manual preparation variability and improves baseline stability.

Future Trends and Opportunities

Advances in reagent free IC and automated eluent generation are expected to further enhance sensitivity and reproducibility. Integration with mass spectrometric detectors could broaden analyte scope. Miniaturization and online sampling will support real time monitoring in treatment plants. Expanding methods to include additional disinfection byproducts will address evolving regulatory demands.

Conclusion

The isocratic 20 mM hydroxide IC method using a Dionex IonPac AS19 column successfully determines bromate, chlorite, chlorate, and other anions in drinking and mineral water with low detection limits and high accuracy. RFIC eluent generation improves baseline stability and simplifies workflow. This approach provides a reliable tool for routine water quality monitoring.

Reference

1. Worawirunwong W and Rohrer J Determination of Trace Oxyhalides and Bromide in Water using RFIC Application Note 167 Dionex 2006
2. Dionex Corporation Ion Chromatographic Determination of Oxyhalides and Bromide Application Note 81 LPN0965 1997
3. U S EPA Method 300.1 Determination of Inorganic Anions by Ion Chromatography 1997
4. Dionex Corporation Determination of Inorganic Oxyhalide Byproducts using Postcolumn Reagent Application Note 136 LPN1229 2002
5. Dionex Corporation Determination of Trace Byproduct Anions and Bromide with Postcolumn Addition of o-Dianisidine Application Note 168 LPN1706 2005
6. U S EPA Method 317.0 O-Dianisidine Postcolumn Derivatization for Bromate 2000
7. Dionex Corporation On-Line Generated Postcolumn Reagent for Sub-µg/L Bromate Analysis Application Note 149 LPN1523 2003
8. Dionex Corporation Disinfection Byproduct Anions with Acidified On-Line Reagent Application Note 171 LPN1767 2006
9. U S EPA Method 326.0 Ion Chromatography with Triiodide Reaction for Bromate 2002