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Volume 65, Issue 3
Special Articles : Solution Interfaces as the Fields for Novel Separation-Detection Methods
Displaying 1-7 of 7 articles from this issue
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Accounts
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Satoshi TSUKAHARAArticle type: Accounts
2016 Volume 65 Issue 3 Pages 113-118
Published: March 05, 2016
Released on J-STAGE: April 05, 2016
JOURNAL FREE ACCESSPhenomena and reactions occurring at liquid/liquid interfaces are hard to measure directly because of the flexibility of the interfaces, prevention of the interfaces by two phases, quite small amounts of substances existing at the interfaces, and the diffusion of substances at the interfaces. We invented a two-phase thin-layer microcell to observe and measure phenomena and reactions at liquid/liquid interfaces by optical microscopy with high magnification and high resolution. In this report, the following two topics are introduced: 1) the phase transition behaviors of a phospholipid monolayer at liquid/liquid interfaces, and 2) the reduction reactions of tetrachloroaurate(III) with hydrophobic substances at liquid/liquid interfaces.View full abstractDownload PDF (677K) -
Tetsuo OKADA, Makoto HARADAArticle type: Accounts
2016 Volume 65 Issue 3 Pages 119-128
Published: March 05, 2016
Released on J-STAGE: April 05, 2016
JOURNAL FREE ACCESSWhen an aqueous solution is frozen, solutes are expelled from ice crystals and accumulated in ice grain boundaries. The accumulated solutes are dissolved to form a concentrated liquid phase at temperatures higher than the eutectic point of the system. The liquid phase confined in ice typically has a size ranging from 100 nm to several micrometers, depending on the solute concentration and temperature. This liquid phase is useful to design various analytical systems, including highly sensitive methods that rely on the freeze concentration, chromatography in which solute partition and adsorption can be controlled, and the preparation of functional solid without heavy organic syntheses. In addition, we have found a number of interesting phenomena occurring in the liquid phase through the development of analytical methods based on the functionality of ice doped with an electrolyte. In this paper, we discuss these phenomena found in ice chromatographic, spectroscopic, and electrochemical measurements.View full abstractDownload PDF (900K)
Research Papers
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Ryota NAKAMURA, Teruo HINOUEArticle type: Research Papers
2016 Volume 65 Issue 3 Pages 129-136
Published: March 05, 2016
Released on J-STAGE: April 05, 2016
JOURNAL FREE ACCESSIn this work, a flow electrolytic cell for ion transfer across a DCE/W interface was manufactured from a block of Daiflon (Polychlorotrifluoroethylene resin). The cell was compact, and had a structure in which the DCE and W phases were separated by a membrane. To evaluate the cell performance, voltammograms of the promoted ion transfer of alkali and alkaline earth metal ions were measured. As ionophores for the ion transfer, 12-crown-4, 15-crown-5 and dibenzo-18-crown-6 were employed. Based on the measurements, the cell was improved, and various parameters (flow rate and the potential added) for amperometry were optimized. Two membranes separating the DCE and W phases, the cellulose dialysis membrane and the PTFE (polytetrafluoroethylene) hydrophilic membrane filter were tested. When the dialysis membrane was used, ion-transfer occurred in the dialysis membrane at the DCE/dialysis membrane/W interface. On the other hand, when the membrane filter was used, ion-transfer occurred in the W phase in the vicinity of the DCE/membrane filter/W interface. In practice, since the membrane filter was chemically resistant to DCE and mechanically stronger than the dialysis membrane, flow-injection amperometry was carried out with the membrane filter. Subsequently, the selectivity among the alkali and alkaline earth metal ions was examined. As a result, it was confirmed that Na+ could be selectively detected when 12C4 was employed. Based on this result, Na+ in soy sauce was determined. The determination value was 2.99 ± 0.14 mol dm−3 (n = 4). The value of 2.99 mol dm−3 was in agreement with the certified value of 2.80 mol dm−3 within the 95%-confidence limit. The relative standard deviation was 4.7%, which shows a reasonable reproducibility of this determination method using the electrolytic cell. The flow electrolytic cell manufactured in this work is easily handled, and can be used in actual analyses of various ions in the aid of flow injection amperometry.View full abstractDownload PDF (1058K) -
Electrochemical Evaluation on the Distribution and Diffusion of Ions in the Plant Cuticular MembraneShiho MORINO, Miki NAKATA, Mitsuru SUGIMOTO, Naoki OKUMURA, Mao FUKUYA ...Article type: Research Papers
2016 Volume 65 Issue 3 Pages 137-144
Published: March 05, 2016
Released on J-STAGE: April 05, 2016
JOURNAL FREE ACCESSCuticular membranes (M) isolated from green or red tomatoes and apples were equilibrated with an aqueous solution, and were set between the aqueous solution (W) and the organic solution (O). Voltammetry for ion transfer from W to O through M was carried out by cyclic voltammetry (CV) and potential step chronoamperometry (PSCA). Various quaternary ammonium ions were examined as an alternative of organic ions such as pesticides. When CV or PSCA was repeated every 5 or 10 minutes, the measured current for ion transfer from M to O decreased at every measurement. The decrement rate was damped with the repeat number of measurements. The current decrement was not observed at the W|O interface in the absence of a cuticular membrane, and was caused by both a slow distribution of ions at the W|M interface and slow diffusion inside the M. The distribution rate constant at the W|M interface and the diffusion coefficient in M were evaluated from PSCA and a simple simulation, and were obtained with various viewpoints, such as the difference of the face or back of membrane, the kind of plants, the degree of maturation of fruits, the hydropobicity of tested ion and the role of lenticel in apple membrane.View full abstractDownload PDF (1156K)
Notes
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Kiyoharu NAKATANI, Emi MATSUTA, Yuki KAWASAKIArticle type: Notes
2016 Volume 65 Issue 3 Pages 145-149
Published: March 05, 2016
Released on J-STAGE: April 05, 2016
JOURNAL FREE ACCESSThe mass transfer of 4-(1,1,3,3-tetramethylbutyl)phenyl polyethylene glycol (Triton X-100, TX-100) as a nonionic surfactant in the octadecylsilyl (ODS) silica gel/water system was investigated using coumarin 102, known as a solvatochromic dye, by the single microparticle manipulation-fluorescence microspectroscopy technique. A spherical ODS silica gel microparticle (particle radius (r) of 10–30 μm, pore diameter of 12 nm) including coumarin 102 was injected into an aqueous TX-100 solution, and the release rate of the dye from the microparticle into the aqueous phase was measured by a confocal fluorescence microscope. The intraparticle diffusion rates of the dye and TX-100 were much faster than the release rate of the dye. The release rate of the dye was discussed using the time dependence of the total fluorescence intensity (IF). An induction period for IF was observed in the short time region. After the induction period, IF could be analyzed on the basis of the first-order reaction-type equation, and the rate-constant values agreed with those for the release of the dye at the sorption equilibrium of TX-100. In the induction period, the fluorescence maximum of the dye depended on time. Therefore, we consider that the sorption of TX-100 proceeds in the induction period. Because the inverse of the time of the induction period was directly proportional to r−2, we conclude that the rate-determining step of the sorption rate of TX-100 is the diffusion between the bulk water phase and the spherical surface of the microparticle.View full abstractDownload PDF (580K) -
Katsumi CHIKAMA, Junichi NAKAJIMA, Mina MATSUO, Kiyoharu NAKATANIArticle type: Notes
2016 Volume 65 Issue 3 Pages 151-155
Published: March 05, 2016
Released on J-STAGE: April 05, 2016
JOURNAL FREE ACCESSDistribution and release processes of heavy-metal ions between spherical surface-modified silica gel microparticles and water were analyzed by microcapillary manipulation and absorption microspectroscopy. Silica gel modified with triamine (QuadraSil-TA, Q-TA) or thiol groups (QuadraSil-MP, Q-MP) was used as a surface-modified silica gel. A single microparticle was injected into an aqueous HAuCl4 or CuSO4 solution containing 0.01 M KCl (pH = 6), and the distribution rate of the metal ion from water into the microparticle was measured. The rate of release of Au(III) or Cu(II) from Q-TA into water (pH = 6) was much smaller than that of the distribution of the metal. The microparticle radius dependence of the absorbance of the metal in the microparticle and distribution of the metal by cross-sectional SEM-EDS analysis at the distribution equilibrium indicate that Au(III) and Cu(II) distribute into the microparticle interior for Q-TA, while Au(III) distributes at the outer layer in the spherical microparticle for Q-MP. The distribution processes were analyzed as the intraparticle diffusion, and the diffusion coefficient (Dp) observed in the present systems was compared with that calculated from the theoretical pore and surface diffusion model. We consider that the rate-determining step of the distribution of Au(III) in the Q-TA (pore diameter = 5.9 nm) system is the intraparticle diffusion of AuCl4−. On the other hand, the distribution of Cu(II) into Q-TA was much slower than the intraparticle diffusion.View full abstractDownload PDF (842K) -
Tatsuya KAKINAMI, Naoya NISHI, Ken-ichi AMANO, Tetsuo SAKKAArticle type: Notes
2016 Volume 65 Issue 3 Pages 157-161
Published: March 05, 2016
Released on J-STAGE: April 05, 2016
JOURNAL FREE ACCESSWe recently found that dendritic gold nanofibers are formed by a redox reaction at the interface between water (W) and trioctylmethylammonium bis(nonafluorobutanesulfonyl)amide, a hydrophobic ionic liquid (IL) [N. Nishi, T. Kakinami, T. Sakka: Chem. Commun., 51, 13638 (2015)]. The formation of such a highly anisotropic structure at the IL|W interface is likely to be achieved due to the viscosity difference of the two liquids, considering a proposed mechanism [F. Scholz, U. Hasse: Electrochem. Commun., 7, 541 (2005)] in which metal nanostructures grow towards the more viscous liquid phase from the liquid|liquid interface. In this paper, we considered the effect of the viscosity difference of the two liquids on the structure of the gold nanostructures formed at the liquid|liquid interface. We used two kinds of dichloromethane (DCM) solutions for the oil phase: the one thickened with polyvinyl chloride and the other containing the IL with a low viscosity compared with the IL itself. It has been revealed that not only the viscosity difference of the two liquids, but also the existence of the IL-ions in the DCM solution promote an anisotropic growth of Au at the liquid|liquid interface.View full abstractDownload PDF (706K)
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