Differentiation of total organic brominated and chlorinated compounds in total organic halide measurement: A new approach with an ion-chromatographic technique

A new method to differentiate total organic chlorinated compounds (TOCl) and total organic brominated compounds (TOBr) has been developed. In this method, HBr and HCl, which are contained in the off-gas from the TOX combustion furnace and are equivalent to TOBr and TOCl in samples, are collected in water with a bubble diffuser instead of being titrated in a micro coulometric cell. Then the concentrations of bromide and chloride ions are determined by ion chromatography. For standard compounds such as 2,4,6-trichlorophenol (100 μg/L as Cl), recoveries of more than 75% were obtained from the full process, including carbon adsorption. Interference with chloride ion quantification by carbon dioxide gas, an auxiliary gas for the combustion furnace, was a barrier to earlier attempts of this method. This interference can be eliminated without loss of HBr and HCl by sparging the solutions with nitrogen gas. These differentiated values are expected to be used as new bulk indices of chlorinated and brominated disinfection by-products.