Electrochemistry at liquid/liquid interfaces: methodology and potential applications

Electrochemistry at the interface between two immiscible electrolyte solutions

Electrochemical polarization phenomena at the interface of two immiscible electrolyte solutions—III. Progress since 1983

Scanning electrochemical microscopy induced transfer (SECMIT) is introduced as a new approach for probing the dynamics of partitioning of electroactive solutes between two immiscible phases. The partitioning process, initially at equilibrium, is perturbed by electrolysis of the target solute at an ultramicroelectrode (UME) tip positioned in one phase, close to the interface with a second phase. For a particular separation between the tip and interface, the flux of soluteand hence current flowingat the UME is governed primarily by the partition coefficient of the solute, Ke, the relative diffusion coefficients of the solute in the two phases, γ, and the interfacial transfer kinetics. A numerical model is developed for SECMIT under potential step chronoamperometric conditions, where the target solute is electrolyzed at the UME at a diffusion-controlled rate. When the interfacial kinetics are nonlimiting, the steady-state current is strongly dependent on the product Keγ, particularly for Keγ > 1, while for c...

Scanning Electrochemical Microscopy (SECM) as a Probe of Transfer Processes in Two-Phase Systems: Theory and Experimental Applications of SECM-Induced Transfer with Arbitrary Partition Coefficients, Diffusion Coefficients, and Interfacial Kinetics

The electron transfer (ET) rate at the interface between two immiscible electrolyte solutions was probed as a function of the driving force and distance between redox centers by scanning electrochemical microscopy The adsorption of phospholipids at the interface resulted in a decrease in the rate of interfacial ET between aqueous redox species and the oxidized form of zinc porphyrin in benzene The fraction of the interfacial area covered with lipid (θ) was evaluated from the measured heterogeneous rate constants (kf) The dependence of θ vs lipid concentration in benzene fit a Langmuir isotherm For complete monolayers of phospholipids, kf was a function of the number of methylene groups in a hydrocarbon chain The driving force dependencies of interfacial ET rates (Tafel plots) were measured for several aqueous redox couples They were linear, with a transfer coefficient of α ≅ 05 when the driving force for ET (ΔG°) was not too high, in agreement with Marcus theory, and leveled off to the diffusion-co

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Long-range electron transfer through a lipid monolayer at the liquid/liquid interface

Theoretical expressions are presented for the potential step chronoamperometry, normal pulse voltammetry and cyclic voltammetry of the ion-transfer at an ion-selective microelectrode in which a polarizable nitrobenzene/water interface is formed at the tip of a micropipet of μm-order diameter with the nitrobenzene phase inside the micropipet. Experiment includes the ion transfer voltammetry of acetylcholine at the microelectrode. The experimental results are well explained by the theoretical predictions. Stripping voltammetry with the microelectrode is also studied; this proved to be promising for determination of acetylcholine at micromolar concentration levels.

Voltammetry with an Ion-Selective Microelectrode Based on Polarizable Oil/Water Interface

The transfer of acetylcholine ion at the polyvinyl chloride-nitrobenzene (PVC-NB) gel/water interface was studied by cyclic voltammetry, potential-step chronoamperometry and potentiometry. The results indicate that the PVC-NB gel/water interface or, in general, the interface between two immiscible electrolyte solutions can be used as the ion-selective electrode surface for both voltammetric and potentiometric analyses of ions, both based on the electrochemical principle of ion transfer at the interface.

Ion-Transfer Voltammetry and Potentiometry of Acetylcholine with the Interface between Polymer-Nitrobenzene Gel and Water

Electrochemical theory of the transfer of protons across a biological membrane facilitated by weak acid uncouplers added to the medium

Electrochemical study of the transfer of uncouplers across the organic/aqueous interface

Recent requirements of the pesticide industry have become much severer, and pesticides (formulated products) are required to satisfy higher safety to both human beings and the environment, higher biological efficacy, lower price, and labor-saving. This review explains the outline of basic pesticide formulation technology, followed by recent advances in developing new formulations and application technologies. Labor-saving formulations and application technologies, environmental load reduction technologies, and user-friendly formulations and application technologies are elucidated.

https://www.jstage.jst.go.jp/article/jpestics/47/4/47_D22-055/_pdf

Takeo Ohkouchi

Papers

Voltammetry with an Ion-Selective Microelectrode Based on Polarizable Oil/Water Interface

Ion-Transfer Voltammetry and Potentiometry of Acetylcholine with the Interface between Polymer-Nitrobenzene Gel and Water

Electrochemical theory of the transfer of protons across a biological membrane facilitated by weak acid uncouplers added to the medium

Electrochemical study of the transfer of uncouplers across the organic/aqueous interface

Basic Technology and Recent Trends in Agricultural Formulation and Application Technology