THE MEASUREMENT OF VERY-LOW LEVEL BROMATE ION

The potential to form BrO3- as a byproduct during ozone treatment of raw water containing bromide ion is a major concern for utilities planning to use ozone. The proposed BrO3- Maximum Contaminant Level (MCL) of 10 mu g/L in the USA has been established largely by using ion chromatography. A spectrophotometric method based on the oxidation of chlorpromazine in the presence of BrO3- has been developed. The method detection limit (MDL) in reagent water is 0.8 mu g/L BrO3-. The procedure has an operating range of 1 to 40 mu g/L BrO3-. The precision of the method is calculated to be better than 2.5% with an accuracy within +/- 1 mu g/L BrO3-. Details of the method are presented along with data gathered by ion chromatography using berate and carbonate eluants; chlorpromazine post column studies; and low level capillary electrophoresis studies.