Determination of bromide ions in seawater using flow system with chemiluminescence detection

A simple flow-based procedure with chemiluminescence (CL) detection is proposed for bromide ion determination in seawater. The procedure was based on the oxidation of bromide to bromine by chloramine-T followed by the reaction of bromine with luminol resulting in CL emission. Since no significant reaction within chloramine-T and luminol was observed, the detection was carried out without bromine extraction from the oxidant medium. The proposed flow system had a sampling rate of 40 determinations per hour, reagents consumption of 100 μg luminol and 60 μg chloramine-T per determination, a limit of detection of 0.5 mg l−1 bromide ions, a linear concentration range (r = 0.999 and n = 7) between 0 and 100 mg l−1, and a coefficient of variance better than 2.5% (for 10 measurements of a 10 mg l−1 Br− solution) were achieved. The analytical system was applied for the determination of bromide in seawater and estuarine-water samples, obtaining an analyte recovery ranging from 94 to 102% and comparing the results with a reference spectrophotometric method no significant difference was observed in 95% confidence level.