Complex formation of uranium(VI) in periodate solutions

The uranyl/periodate system was investigated by Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLIFS), and Capillary Electrophoresis (CE) in 0.1 and 0.05 mol L-1 perchloric solutions at pH 2.6, containing various amounts of periodate anions. The formation of only one complex, UO2IO4+, was observed for a periodate concentration ranging from 5 x 10(-5) to 10(-1) mol L-1. The stability constant of this complex was estimated to be log beta(11) = 1.8 +/- 0.2 by TRLIFS (fluorescence titration) and log beta(11) = 2.0 +/- 0.2 by CE, for an ionic strength of 10(-1) and 5 x 10(-2) mol L-1, respectively. Moreover, the 1 : 1 stoichiometrical ratio between uranium(VI) and periodate was confirmed by an analysis of the results obtained from the deconvolution of fluorescence spectra.