Simultaneous capillary electrophoretic separation and detection of P(V) and As(V) as heteropoly-blue complexes

A capillary electrophoretic (CE) method was developed for the simultaneous determination of P(V) and As(V). A Mo(VI)–ascorbic acid reagent reacted with a mixture of trace amounts of P(V) and As(V) to form the corresponding heteropoly-blue complexes in 0.05 M acetate buffer (pH 3.5). When 0.05 M malonate buffer was used as a migration buffer, the peaks due to their migrations were well separated in the electropherogram, and the pre-column complex-formation reaction was applied to the simultaneous CE determination of P(V) and As(V) with direct UV detection at 220 nm. With the proposed method, the calibration curves were linear in the concentration range of 5·10−7–1·10−4 M, with a detection limit of 1·10−7 M (a signal-to-noise ratio of 3). Interference from foreign ions was also discussed.