Dissociation Kinetics and Complexation Equilibrium Studies of a ZnII Complex with 1,5-Bis(2-hydroxy-5-sulfophenyl)-3-cyanoformazan during Capillary Electrophoretic Separation Process
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- Takahashi Toru
- Division of Environmentally Benign Systems, Graduate School of Environmental Studies, Tohoku University
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- Takehara Yuka
- Department Applied Chemistry, Graduate School of Engineering, Tohoku University
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- Hoshino Hitoshi
- Division of Environmentally Benign Systems, Graduate School of Environmental Studies, Tohoku University
抄録
The dissociation kinetics and the complexation equilibrium of a ZnII complex with 1,5-bis(2-hydroxy-5-sulfophenyl)-3-cyanoformazan (hscf: H5L) during capillary electrophoretic (CE) separation process were studied. The solvolytic dissociation reaction rate constants of the ZnII–hscf complex ([ZnL]3−) (kd) in the pH range of 6.4 to 8.0 were determined with a CE-based dissociation kinetic analysis method. Small kd values on the order of 10−5 s−1 showed the remarkable kinetic inertness of [ZnL]3−, which was detectable in the CE system. The stability constant of [ZnL]3− (KZnL) at 293 K and I = 0.10 was estimated to be [ZnL3−]/{[Zn2+][L5−]} = 1024.2±0.3 through the spectrophotometric titration. The thermodynamic stability of [ZnL]3− in the pre-capillary complexation stage was thus demonstrated. In contrast, it was shown that the CE separation environment is thermodynamically unsuitable for the metal complexes based on the conditional stability constant of [ZnL]3−, which was determined under CE separation conditions, and the concentration of free HSCF in the complex band in the capillary. Thus, the “stability” of metal complex in the CE system strongly depends on kinetic inertness rather than thermodynamic stability, though their thermodynamic stability is necessary for the pre-capillary derivatization step.
収録刊行物
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- Bulletin of the Chemical Society of Japan
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Bulletin of the Chemical Society of Japan 80 (5), 910-915, 2007
公益社団法人 日本化学会
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詳細情報 詳細情報について
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- CRID
- 1390282679119727104
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- NII論文ID
- 130004152318
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- ISSN
- 13480634
- 00092673
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- 本文言語コード
- en
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- データソース種別
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- JaLC
- Crossref
- CiNii Articles
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- 抄録ライセンスフラグ
- 使用不可