Simultaneous Determination of Trace Bromate, Nitrite and Bromide in Cool Boiled Water by Ion Chromatography

The sample was filtered by a 0.22 μm membrane, and then bromate (BrO₃^-), nitrite (NO₂^-) and bromide (Br^-) were determined by conductivity detector with SH-AP-1 anion exchange column for separation and 14 mmol·L^-1 KOH solution for elution. It was shown that linear relationships between mass concentrations and peak areas of BrO₃^-, NO₂^- and Br^- were kept in the range of 1.00-10.00 μg·L^-1, with detection limits of 0.19, 0.06, 0.18 μg·L^-1, respectively. RSDs (n=6) of BrO₃^-, NO₂^- and Br^- in the blank spiked water sample were 1.5%, 2.1% and 3.1%, respectively. Test for recovery was made on the actual sample at 3 concentration levels, giving results in the range of 86.5%-104%. Compared with the analysis of the fast detection equipment based on diazo coupling spectrophotometry, the accuracy of this method for the determination of low concentration level of NO₂^- less than 5.00 μg·L^-1 was higher. This method was used to analyze the cool boiled water and the reverse osmosis water in production process, and BrO₃^- was not detected. The detection amounts of Br^- and NO₂^- in the reverse osmosis water were 1.13 μg·L^-1 and 1.54 μg·L^-1, respectively, and the detection amounts of Br^- and NO₂^- in the cool boiled water were 1.33 μg·L^-1 and 1.21 μg·L^-1, respectively.