Determination of bromate in drinking waters by ion chromatography with inductively coupled plasma mass spectrometric detection

Bromate is a disinfection by-product in drinking water, formed during the ozonation of source water containing bromide. An inductively coupled plasma mass spectrometer is combined with an ion chromatograph for the analysis of bromate in drinking waters. Three chromatographic columns are evaluated in terms of detection limits, analysis time and tolerance to potentially interfering inorganic anions. The detection limits for all columns are in the 1-2 mu g/l range for the direct analysis of bromate. A 5-min analysis time was achieved using a Dionex AG10 column and 100 mM NaOH as the eluent. Recoveries for bromate in fortified samples containing chloride (1000 ppm) or nitrate (50 ppm) were 96-107%. Recoveries for bromate in fortified samples containing sulfate (1000 ppm) were 91-124%. The R.S.D. values for drinking water analyses are in the 2-6% range. A 1.8-ml sample was preconcentrated on a Dionex AG10 column. This system produced bromate detection limits in the 0.1-0.2 mu g/l range. Coupling the AG10 preconcentrator column with an ultrasonic nebulizer produced a detection limit of 50 ppt for bromate. The precision for samples which are preconcentrated is degraded due to an adjacent peak interfering with integration of the bromate peak.