Analytical Sciences

Dissociation Kinetic Analysis of Ce(III) Complex with Quin2 by Microchip Capillary Electrophoretic Reactor

Kei-ichirou OHTSUKA,* Nobuhiko IKI,* Hitoshi HOSHINO,* and Toru TAKAHASHI**

*Graduate School of Environmental Studies, Tohoku University, 20 Aoba, Aramaki, Aoba, Sendai 980-8579, Japan
**Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan

Dissociation kinetic analysis of a complex of Ce³⁺ with a polyaminocarboxylic ligand, 8-amino-2-[(2-amino-5-methylphenoxyl)methyl]-6-methoxyquinoline-N,N,N′,N′,-tetraacetic acid (Quin2), was studied by microchip capillary electrophoretic reactor. Dissociation rate constants, k_d, of Ce³⁺-Quin2 complex in alkaline conditions at pH 8.3 – 9.8 were determined. The linear relationship of k_d with the concentration of hydroxide ion indicates the existence of a hydroxide ion-assisted path in the dissociation reaction of Ce³⁺-Quin2 complex in alkaline conditions. The solvolytic dissociation rate constant, and the hydroxide ion-assisted dissociation rate constant of Ce³⁺-Quin2 complex were determined to be 1.55 × 10⁻³ and 3.24 × 10² s⁻¹ in the analysis of the dependence of k_d with the concentration of hydroxide ion, respectively.

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