The Methods Of The Determination Of Bromate
THE METHODS OF THE DETERMINATION OF BROMATE
IN DRINKING WATER
A. Gierak, R. Leboda, B. Charmas, J. Skubiszewska-Zieba
Faculty of Chemistry, Maria Curie-Sklodowska University,
Maria Curie-Sklodowska sq. 3, 20-031 Lublin, Poland
Bromate is a disinfection by-product in drinking water, formed during the ozonation of source water containing bromide ions. The bromide in the source water is oxidized to bromate by the ozone. Bromate is believed to be a cancer causing agent and has been classified by the International Agency for Research on Cancer as probably carcinogenic to humans. Typical concentrations of bromate found in ozonated water contain in the range 3-68 μg/dm3. Although the World Health Organization has a recommended provisional guideline of 10μg/dm3 in drinking water, this is likely to be significantly reduced as the ability to analyze bromate concentrations (at the μg/dm3 and sub- μg/dm3 level) in proves. In fact, there is already a suggestion that it could be set as low as 0.5 μg/dm3 (0.5 ppb).
Usually, bromate is analyzed by US EPA method 300.0 using ion chromatography (IC) with conductivity detection. However, the analysis of bromate in a chloride matrix by ion chromatography with conductivity detection suffer from the chloride signal (103 – 104 higher concentration) enveloping the much smaller bromate signal.
Several refinements have been made to address the chloride interference and improve the detection limits. Some research workers used a weaker solvent to improve the separation of the early eluting bromate and chloride. This improve the ability to tolerate a chloride matrix while improving the detection limit to 7 μg/dm3. Joyce et. al. [1,2] and Weinberg [3] used a silver containing cartridge for a sample pretreatment to remove the chloride. The cartridge removed the chloride but the silver in the sample needed to be removed prior to injection to avoid degrading the separation on the analytical column [1]. Gordon et. al. [4] have combined spectrometric technique with ion chromatography but still found it necessary to remove the chloride ion prior to analysis.
The focus of our paper is investigation on removing chloride ion from drinking water samples before the analysis of bromate, nitrate and nitrite with the application of ion chromatography with reverse spectrometric detection UV. Zeolite SY and Lewatit S (MERCK) pure and after ion exchange with silver (Ag+) have been used in our investigation.
Application of this process permits us to reduce of concentration of chloride practically without reduction of concentration of determined ions (bromate, nitrite and nitrate) in drinking water samples.
References
1. R.J.Joyce, H.S.Dhillon, J.Chromatogr.A 671 (1994) 165.
2. R.J.Joyce, H.S.Dhillon, International Ion Chromatography Symposium, Baltimore, MD, September 1993.
3. H.Weinberg, J.Chromatogr.A 671 (1994) 141.
4. G.Gordon, B.Bubnis, Ozone Sci. Eng., 17 (1995) 551.
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