Analysis of bromate and bromide in blood

Bromate is a regulated disinfection byproduct primarily associated with the ozonation of water containing bromide, but also is a byproduct of hypochlorite used to disinfect water. To study the pharmacokinetics of bromate, it is necessary to develop a robust and sensitive analytical method for the identification and quantitation of bromate in blood. A critical issue is the extent to which bromate is degraded presystemically and in blood at low (environmentally relevant) doses of ingested bromate as it is delivered to target tissue. A simple isolation procedure was developed using blood plasma spiked with various levels of bromate and bromide. Blood proteins and lipids were precipitated from plasma using acetonitrile. The resulting extracts were analyzed by ion-chromatography with inductively-coupled plasma mass spectrometry (IC-ICP/MS), with a method reporting limit of 5 ng/mL plasma for both bromate and bromide. Plasma samples purchased commercially were spiked with bromate and stored up to 7 days. Over the 7 day storage period, bromate decay remained under 20% for two spike doses. Decay studies in plasma samples from spiked blood drawn from live rats showed significant bromate decay within short periods of time preceding sample freezing, although samples which were spiked, centrifuged and frozen immediately after drawing yielded excellent analytical recoveries.