New, sensitive and selective method for determining sub-microgram/l levels of bromate in drinking water

Health effects studies suggest that bromate should be regulated at 0.5 microgram/l or less in drinking water. Accordingly, an analytical method is needed to quantify this contaminant with great sensitivity and selectivity. Past efforts to do this have focused on pre-concentration ion chromatographic (IC) separation followed by suppressed conductivity detection. Interfering chloride was removed by passing samples over a silver resin which increased sample analysis time to almost 1 h. In this paper, a new method which uses IC separation with no pre-treatment followed by a post-column reaction to produce tribromide (Br3-) from bromate, is applied to the analysis of a variety of aqueous samples. The tribromide ion is detected by UV absorbance at 267 nm. This method is very sensitive for bromate with a limit of quantitation of 0.2 microgram/l and is also very selective. Common anions typically separated by IC exhibit no interference, even at the levels normally found in drinking water.