Analytical Sciences


Abstract − Analytical Sciences, 23(8), 959 (2007).

Selective Determination of Cadmium(II) from Divalent Metal Ions in Environmental Samples by Capillary Electrophoresis Using In-capillary Complexation with a Lacunary Keggin-type [PW11O39]7- Complex
Sadayuki HIMENO, Eri KITANO, and Kenta MORISHITA
Department of Chemistry, Graduate School of Science, Kobe University, Nada, Kobe 657-8501, Japan
A novel capillary electrophoretic (CE) method, based on in-capillary complexation with [PW11O39]7-, was developed for the determination of cadmium(II) in natural water samples. When a sample solution is injected into a capillary containing 0.20 mM [PW11O39]7- and 0.10 M malonate buffer (pH 3.0), the ternary Keggin-type complex, [P(CdIIW11)O39]5-, which possesses high molar absorbtivities in the UV region, is formed in the capillary, and its migration toward the anode gives a well-defined migration peak in the electropherogram. An advantage of this method is that many divalent metal ions do not interfere. The proposed method was successfully applied to the determination of Cd(II) in environmental samples. The detection limits were 1 × 10-7 and 5 × 10-7 M for river-water and seawater samples, respectively (signal-to-noise ratio = 3).