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

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((SbW11)-W-III)O-40](6-) and [P((BiW11)-W-III)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 x 10(-7) - 5 x 10(-5) M; a detection limit of 1 X 10(-7) M was achieved for Sb(III) or Bi(III) (the signal-to-noise ratio = 3). (C) 2003 Elsevier B.V. All rights reserved.