Low-level bromate analysis in drinking water by ion chromatography with optimized suppressed conductivity cell current followed by a post-column reaction and UV/Vis detection

Abstract

In the present work, a high capacity anion exchange column was used to efficiently and simultaneously separate traces of oxyhalide disinfection byproducts (DBP) anions and bromide by an ion chromatography system followed by a post-column reaction (PCR). The PCR generates in situ hydroiodic (HI) acid from the excess of potassium iodate that combines with bromate from the column effluent to form the triiodide anion detectable by UV/Vis absorbance at 352 nm. The suppressed conductivity cell current was optimized at 70 mA, with a flow rate of 1.0 mL/min and a 9 mM carbonate eluent. Its performance was investigated on a trace-level determination of bromate in ozonated municipal and bottled drinking water. Based on ozonated municipal drinking water matrix, the method detection limit of 0.27 μg BrO⁻ ₃/L was evaluated with the Method Quantification Limit (MQL) of 0.89 μg BrO⁻ ₃/L. However, in ultrapure water, a MDL of 0.015 μg BrO⁻ ₃/L and a MRL of 0.052 μg BrO⁻ ₃/L were achieved. The recovery for spiked municipal samples was in the range of 90%–115%.

Keywords:

• Drinking water
• bromate
• suppressed conductivity
• ozonation
• ion chromatography

Acknowledgments

The authors wish to thank Julie Philibert for the ozonation of the municipal water. The industrial partners of the Industrial NSERC Chair in Drinking Water at Ecole Polytechnique de Montreal, the City of Montreal, the City of Laval and John-Meunier Inc. are gratefully acknowledged for their financial support.