In order to protect public health, drinking water is usually disinfected using chlorine, chlorine dioxide, sodium hypochlorite and ozone. However, disinfection will not only remove microorganisms that cause diseases in humans, but also produce disinfection byproducts (DBPs), including chlorite, chlorate and bromate. It is reported that a significant amount of chlorite and chlorate can be formed during water chlorination and bromate can be produced from water ozonation when water contains high levels of bromide. These DBPs are potentially harmful to humans. For example, bromate has been identified as a potential human carcinogen. Therefore, the Environmental Protection Agency (EPA) of the United States has proposed that the maximum concentration level (MCL) of bromate is 10ppb.
In this study, an IC-MS method was developed using a novel electrolytically regenerated suppressor as a part of a modular IC system coupled with a LC-MS 2020 single quadrupole MS for the determination of oxyhalide anions, including chlorite, chlorate and bromate in drinking water. Both conductivity detection (CDD) and MS with electrospray ionization in negative mode are used in the method. The CDD is used to monitor the column effluent; only the oxyhalides of interest are directed to MS via a divert valve. Quantitative analysis was performed by using the selected ion monitoring (SIM) on two isotopic mass of each compound.