Journal Article 蛍光色素diOC2(3)が吸着した油水界面へのアルカリ金属・アルカリ土類金属イオンの促進移動

森口, 弥香  ,  永谷, 広久  ,  枝, 和男  ,  大堺, 利行

65 ( 2: 特集 : 新規な分離・検出の場としての溶液界面 )  , pp.71 - 77 , 2016-03-05 , 日本分析化学会 = The Japan Society for Analytical Chemistry
モノカチオン型の膜電位感受性色素3,3'-ジエチルオキサカルボシアニン{diOC2(3)}を添加した1,2-ジクロロエタン(DCE)|水(W)界面において,水相中の支持電解質カチオン(Li+, Na+, K+, Mg2+, Ca2+)の促進移動と思われる異常に大きなボルタンメトリー波が観察された.このメカニズムを解明するため,交流ボルタンメトリーによる界面の電気二重層容量の測定,及び電位変調蛍光分光測定を行った.その結果,diOC2(3)と油相中の支持電解質アニオン{テトラキス(4-クロロフェニル)ホウ酸}がDCE|W界面に共吸着し,その吸着層にイオンサイズの小さいカチオンがインターカレーションされ,移動が容易になると推察された.この促進効果はアルカリ金属よりもアルカリ土類金属の方が顕著であった.
At the 1,2-dichloroethane (DCE) | water (W) interface upon the addition of a monocationic membrane-potential-sensitive dye, 3,3'-diethyloxacarbocyanine {diOC2(3)}, an extraordinarily large voltammetric wave, was observed. This was probably due to a facilitated transfer of the supporting-electrolyte cation in W (i.e., Li+, Na+, K+, Mg2+, Ca2+). In order to explain the mechanism, we also carried out a determination of the double-layer capacity of the interface by ac voltammetry and potential-modulated fluorescence (PMF) spectroscopy measurements. The results have suggested that monocationic diOC2(3) and the supporting-electrolyte anion in DCE {tetrakis(4-chlorophenyl)borate} are co-adsorbed (probably in multilayers) at the DCE | W interface and, into the adsorption layer, the above cations of small sizes are intercalated, and thus transferred more easily. This facilitation effect is more significant for alkali-earth metal ions than for the alkali metal ions. A possible application has been suggested concerning the voltammetric or fluorescence determination of Mg2+ and/or Ca2+ (e.g., water hardness analysis).

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