Simultaneous capillary electrophoretic determination of Sb(III) and Bi(III) based on the complex-formation with a W(VI)-P(V) reagent

Abstract A capillary electrophoretic method was developed for the simultaneous determination of Sb(III) and Bi(III). A 1.0 mM W(VI)–0.10 mM P(V) complexing reagent readily reacted with a mixture of trace amounts of Sb(III) and Bi(III) to form the corresponding ternary Keggin-type complexes; [P(Sb III W 11 )O 40 ] 6− and [P(Bi III W 11 )O 40 ] 6− in 0.01 M malonate buffer (pH 2.4). Since the peaks due to the migrations of the ternary complex anions were well separated in the electropherogram, the pre-column complex-formation reaction was applied to the simultaneous CE determination of Sb(III) and Bi(III) with direct UV detection at 255 nm. The calibration curves were linear in the range of 2×10 −7 –5×10 −5 M; a detection limit of 1×10 −7 M was achieved for Sb(III) or Bi(III) (the signal-to-noise ratio=3).