Determination of bromate at parts-per-trillion levels by gas chromatography–mass spectrometry with negative chemical ionization

Abstract

The ozonation of bromide-containing source waters produces bromate as a class 2B carcinogenic disinfection by-product. The present work describes the determination of bromate by gas chromatography–negative chemical ionization mass spectrometry (GC–NCIMS) following a bromate reaction/extraction procedure. The method detection limit for bromate based on 3.14 σ n−1 of seven replicate injections was 22 ng/l (parts-per-trillion). The overall GC–NCIMS analysis time was less than 5 min. In chlorinated waters, an interference is observed. Therefore, the current application is for unchlorinated waters, such as those produced in ozone contactors within water treatment plants, prior to the addition of chlorine. The bromate levels determined in these ozone contactor waters agreed within experimental error to the levels determined by an ion chromatographic technique. These water samples were fortified and recoveries ranged between 96% and 114% with relative standard deviation between 4% and 14%.