Capillary electrophoretic determination of Ga(III) based on the formation of a heteropolyoxomolybdate complex

A novel capillary electrophoretic (CE) method was developed for the determination of Ga(III). The so-called Anderson-type [GaMo6O24H6]3− complex was readily formed by the reaction of Mo(VI) with Ga(III) in 0.050 M monochloroacetate buffer (pH 2.0) and the precolumn complex-formation reaction was applied to the CE determination of Ga(III) with direct UV detection at 240 nm. The peak area was linearly dependent on the concentration of Ga(III) in the range of 5.0·10−7–5.0·10−5 M. Owing to the high molar absorptivity of the Anderson anion, a detection limit of 2.0·10−7 M (signal-to-noise ratio=3) was achieved. The advantage of the present method is that the presence of large excesses of Al(III) and In(III) does not cause interference.