Further research on iodine speciation in seawater by capillary zone electrophoresis with isotachophoresis preconcentration

A novel, simple and highly sensitive CE method was developed to determine total iodine (TI) in seawater. The method is based on the on-capillary reduction of iodine species to iodide by a reductant, introduced into the capillary before sample injection, the preconcentration of iodide using isotachophoresis, followed by its UV detection. Under optimized conditions for reduction and CE separation, the limit of detection for TI (S/N = 3) reached 0.4 μg L−1 (226 nm). The repeatability of migration time and peak area, expressed by relative standard deviation, was 0.46 and 1.45%, respectively (n = 19). The correlation factor was 0.9991 (n = 10) for the concentration range of 12–115 μg I L−1. The CE results obtained for the real seawater analysis agreed with the data of ion chromatography. To determine the genuine TI by the proposed method, organic iodinated compounds in the sample were treated with H2O2 and irradiation with UV light before analysis.