Analytical Sciences

Abstract − Analytical Sciences, 15(8), 725 (1999).

Simultaneous Determination of Periodate(VII) and Iodate(V) by Capillary Electrophoresis
Yoichi NAKASHIMA*, Hui SHEN**, Kohji KUSUYAMA** and Sadayuki HIMENO**
*Technology Research Institute of Osaka Prefecture, Izumi, Osaka 594-1157, Japan
**Department of Chemistry, Faculty of Science, Kobe University, Nada, Kobe 657-8501, Japan
A sensitive method was developed for the capillary electrophoretic determination of I(VII). In a 5x10-2 M malonate buffer solution (pH 4) containing low concentrations of I(VII) and 1x10-2 M Mo(VI), a stable [IMo6O24]5- complex was formed at room temperature. Since the heteropoly anion showed an approximately eight-fold increase in the molar-absorption coefficient than the free IO4- anion, the complex-formation reaction was applied to the sensitive capillary electrophoretic determination of I(VII) with UV detection at 220 nm. A simultaneous determination of I(VII) and I(V) was also possible, since both peaks due to [IMo6O24]5- and IO3- were well-separated in the electropherogram. For I(VII) and I(V), linear calibration curves were obtained in the concentration ranges of 2x10-6 - 2x10-4 M and 5x10-5 - 2x10-3 M, respectively. (Keywords: Capillary electrophoresis, 6-molybdoperiodate, oxidation state analysis of I(VII) and I(V))