During the preparation of the iodide-iodate solution I - was oxidized,which caused large deviation of calculated segregation index from experimental value.In this paper, the concentrations of I-3,I- and I2 in as-prepared solution were determined through concentration analysis of I- 3 by spectrophotometer, and then the oxidized amount of I- was calculated. A modified expression of segregation index for iodide-iodate reaction system wa s deduced and verified by experiments, indicating that the deviation between exp erimental results and the modified expression was within ±15%.
