Interferences from iodate during the iodometric determination of residual chlorine in seawater

The greater values obtained from the iodometric titration of residual chlorine in sea-water at pH 2 have been shown to be due to the presence of iodate. It has been observed that the results from the iodometric titration of reisual chlorine in seawater at pH 2 were greater than those at pH 4 by up to twenty percent. The investigation of this phenomenon assumed as a working hypothesis the possible interference from bromate or iodate generated from the bromide or iodide present in the seawater during the initial addition of excess chlorine. This approach was to look specifically for such species as iodate and bromate by mobile phase ion chromatography (MPIC) and to examine the effect of pH on the iodometric titration of these two ions.