Simultaneous determination of periodate(VII) and iodate(V) by capillary electrophoresis

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 (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.