Determination of bromide ions in seawater by capillary zone electrophoresis using diluted artificial seawater as the buffer solution

Abstract

A novel capillary zone electrophoresis method was developed for the determination of bromide ion in seawater. A tenfold-diluted artificial seawater was adopted as the buffer solution, to prevent interference from high concentrations of chloride ion in seawater. No electroosmotic flow reverser was used to shorten the analysis time. It was found that the peak area and migration time for bromide ion were almost constant, despite differences in the salinity of sample solutions; the peak height decreased linearly with an increase in the salinity. The limit of detection for bromide ion was 0.46 mg/l ( S/ N=3). The values of the relative standard deviation for peak area and migration time for bromide ion were 1.4 and 1.5%, respectively. The proposed method was applied to the determination of bromide ion in seawater samples taken from the surface and the sea-bed. The analytical results obtained by the working curve method agreed with those obtained by the standard addition method. The method may be applicable to the determination of other ions, such as nitrite and nitrate ions, in seawater