Vol. 47, No. 12
December, 1998
Masao Sugawara* and Ayumi Hirano**
*Department of Chemistry, College of Humanities and Sciences, Nihon University, 3-25-40, Sakurajousui, Setagaya-ku, Tokyo 156-8550
(Received 16 July 1998, Accepted 5 August 1998)The present paper describes analytical aspects of receptor-incorporated bilayer lipid membranes (BLMs) sensors based on transmembrane signaling: (i) membrane potential change, (ii) membrane permeability change and (iii) active transport. The receptors used in the present study included synthetic and natural ionophores as well as bioreceptors, such as Na+, K+-ATPase, glutamate receptor ion channel and Na+/D-glucose cotransporter. The receptors were incorporated into planar BLMs formed by the folding and tip-dip methods. The membrane capacitance and current noise of the BLMs formed by both methods were also investigated. By comparing the conductance of BLMs with and without receptors, an experimental criterion for judging the successful incorporation of receptors into the BLMs was achieved. The response characteristics of the constructed BLM sensors were considered in terms of their principles, sensitivity, selectivity and amplification ability. The potentiometric responses of BLM sensors based on synthetic ionophores were significantly improved by the simultaneous incorporation of anionic sites, providing a basis for quantitative BLM sensors. The highly sensitive detection of agonists with glutamate receptor-based BLM sensors was also demonstrated. Synthetic ionophore-incorporated BLM sensors were constructed that induce analyte-triggered membrane permeability changes, attributed to permeation of primary ions as well as counter anions. The future prospects of receptor-incorporated BLM sensors were also considered.
Keywords: bilayer lipid membrane; synthetic and bioreceptors; membrane potential; membrane permeability; active transport.
Masayuki Yamada, Hajime Katano and Mitsugi Senda*
*Department of Bioscience, Fukui Prefectural University, Matsuoka-cho, Fukui 910-1195
(Received 16 July 1998, Accepted 3 August 1998)The theory of normal pulse voltammetry (NPV) and potential sweep voltammetry (PSV) of amperometric ion-selective electrodes (AISEs) based on the ionophore-assisted transfer of ions across a polarized organic solvent or oil/water (O/W) interface is discussed. A numerical solution of the resulting integral equations has been used to show how their voltamograms vary with the ratio of the concentration of the analyte ion in the W phase (test solution) to that of ionophore in the O phase (ion-sensitive membrane). The theoretical prediction agrees well with the experimental results obtained with amperometric K+- or Na+-ISEs. up to 20 or 200 mM, respectively, at 20 mM of ionophore. Generally, the current response of the AISEs at constant ionophore concentration is not linear with respect to the concentration of the analyte ion when the ratio of the concentrations exceeds 0.01. In order to realize a linear calibration curve in wide range of analyte concentration up to a few molar of, e.g, Na+ ion, a new technique, called F-pulse amperometry, is proposed; it has been experimentally verified by applying a pulse voltage corresponding to the `foot of wave' potential and sampling the current response according to the NPV technique.
Keywords: potassium ion; sodium ion; amperometric ion-selective electrode; theory; high concentration analysis.
Koji Nakano, Hiroaki Taira*, Mizuo Maeda** and Makoto Takagi*
*Department of Chemical Systems and Engineering, Graduate School of Engineering, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka-shi, Fukuoka 812-8581
**Department of Materials Physics and Chemistry, Graduate School of Engineering, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka-shi, Fukuoka 812-8581
A gold substrate surface was modified with a self-assembled monolayer (SAM) from ω-carboxyalkanethiol of N-hydroxysuccinimide (NHS) ester form, followed by a reaction with a series of proteins with different molecular weights to create a protein-SAM/gold structure. The resulting substrates were first characterized by electrochemical measurements. A frequency-response analysis showed that the magnitude of the impedance of the substrate increased with increasing molecular weight of the immobilized protein. Reflection-absorption Fourier-transform infrared spectroscopy (FT-IRRAS) was employed for a detailed study of the protein-SAM/gold structure. A quantitative analysis of FT-IRRAS spectra showed that both the surface concentration of the protein and the apparent thickness of the protein adlayer correlated to the molecular weight of the immobilized protein. It was also suggested that the magnitude of the impedance of the substrate is linked to the apparent thickness of the protein adlayer, since its characteristic molecular-weight dependence was consistent with that for the protein adlayer thickness. This result seems to be important for chemical sensor applications of the present system based on an impedimetric principle.
Keywords: self-assembled monolayer; protein-modified electrode; impedance; FT-IR; biosensor.
Hiroshi Yao, Hiroshi Ikeda and Noboru Kitamura*
*Division of Chemistry, Graduate School of Science, Hokkaido University, Nishi 8, Kita 10, Kita-ku, Sapporo-shi, Hokkaido 060-0810
(Received 15 July 1998, Accepted 17 August 1998)Two types of a J aggregate with different optical properties were observed in an aqueous pseudoisocyanine (PIC) dye solution, depending on the nature of the thin-layer optical glass cell. In a quartz or hydrophobic glass cell, J aggregate formation was observed above 8 mM, exhibiting the absorption maximum (λmax) at~572 nm and its line width (Δ) of~70 cm-1 (JS aggregate). On the other hand, another J aggregate possessing a red-shifted (λmax~577 nm) and relatively broad (Δ~130 cm-1) absorption band was observed above 6 mM in a soda lime or borosilicate glass cell (JL aggregate). At higher concentrations above 6 mM, both JS and JL aggregates were observed. The interactions between the glass-cell surface and PIC are discussed in terms of the formation process and the distribution characteristics of the aggregate. Absorption and total-internal-fluorescence spectroscopy showed explicitly that JS aggregate formation was dependent on the monomer concentration, and was distributed in the bulk solution phase, whereas JL formation was confined to the vicinity of the glass/solution interface due to electrostatic interactions between the anionic sites on a glass and PIC.
Keywords: J aggregate; soda lime glass; glass/solution interface; absorption line width; total-internal-reflection fluorescence.
Satoshi Tsukahara, Yoshiaki Yamada, Teruo Hinoue and Hitoshi Watarai
*Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-machi, Toyonaka-shi, Osaka 560-0043
(Received 8 July 1998, Accepted 21 August 1998)We made an apparatus for measuring the time-resolved fluorescence anisotropy of a fluorophore at a liquid-liquid interface with polarized incident light under the total internal-reflection condition. s-Polarized and pulsed laser light (wavelength, 536 nm; pulse width, 1 ns) was irradiated from the toluene phase to the interface at an angle of incidence of 70°, which is larger than the critical angle (63°) for the interface. The decays of s- and p-polarized fluorescences emitted from protonated octadecylrhodamine B (C18RB) adsorbed at the toluene/water (0.1 M H2SO4) interface were measured directly from the bottom of a drum-shaped sample cell. From the difference between the polarized fluorescence decays, the in-plane rotational relaxation of C18RB at the interface could be evaluated. Although C18RB molecules rotated freely at the interface, the rotating region of a C18RB molecule was restricted by the adsorption of the nonionic surfactant (Triton X-100), which was added (2.5×10-8 M) to the aqueous phase. C18RB molecules rotated at the interface with a time constant of less than 1 ns regardless of the co-adsorption of Triton X-100.
Keywords: total internal-reflection fluorometry at a liquid-liquid interface; time-resolved fluorescence anisotropy; octadecylrhodamine B; Triton X-100; in-plane rotational reorientation.
Toshio Takayanagi, Tomoko Miya and Shoji Motomizu*
*Department of Chemistry, Faculty of Science, Okayama University, 3-1-1, Tsushimanaka, Okayama 700-8530
(Received 10 July 1998, Accepted 21 August 1998)The formation rates of triphenylmethanols from corresponding cationic triphenylmethane dyes were investigated in the presence of nonionic surfactant micelles, such as Triton X-100, PONPE-20, Brij-35 and Brij-58. The increases in the formation rates of triphenylmethanols with the hydroxide ion in a nonionic micellar solution were almost comparable to that in the presence of a cationic micelle of stearyltrimetylammonium ion. The increase in the rate was largest with Triton X-100, and the rates with the hydroxide ion increased on the order of about 102.0~103.7 fold compared with those in an aqueous solution. The reaction rates for malachite green and brilliant green increased most significantly among the five dyes examined. The rates also increased along with an increase in the hydrophobicity (lipophilicity) balance of the surfactant molecule. These results indicate that the cationic dyes are adsorbed on the hydrophobic core of the surfactant micelle, and that the formed triphenylmethanols are incorporated in the core.
Keywords: nonionic surfactant micelle; triphenylmethane dye; kinetics; acceleration.
Hisashi Kato, Koichi Saitoh* and Tadayuki Imanaka**
*Research Center for Higher Education, Tohoku University, Kawauchi, Aoba-ku, Sendai 980-8576
**Graduate school of Engineering, Kyoto University, Yoshidahon-cho, Sakyo-ku, Kyoto 606-8501
This report deals with an evaluation of arthrofactin (AF) as pseudostationary phase component in micellar electrokinetic chromatography (MEKC). A micellar solution of AF is invaluable for MEKC owing to the ow electrophoretic mobility of the AF-micelle. However, a mixed micellar solution of AF and sodium dodecyl sulfate (SDS) is valuable. The contribution of different kinds of solute-micelle interactions to the MEKC behavior of solute compounds is discussed by using-the linear solvation energy relationship (LSER) model with the AF-SDS mixed micellar system. A notable difference is found between SDS and mixed AF-SDS micellar systems in selectivity, partifically for compounds having a hydrogen-donating ability. The effect of the hydrogen-bonding ability of the solute to its retention in the micelle increases with increasing concentration of AF in a mixed micellar solution. As a consequence, a specific increase in the retention is observed for phenols and alcohols, even at such a low concentration of AF as the 0.01% level of SDS. Such a sensitive effect of AF is regarded to be caused by the presence of many hydrogen-acceptable functional groups, such as amide and carboxyl, in the hydrophilic moiety in an AF molecule.
Keywords: micellar electrokinetic chromatography; pseudo-stationary phase; biosynthesized surfactant; arthrofactin; mixed micellar.
Hirofumi Tani, Takashi Ooura and Tamio Kamidate*
*Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, Kita-13, Nishi-8, Sapporo-shi, Hokkaido 060-8628
(Received 16 July 1998, Accepted 31 August 1998)The effect of charged water-soluble polymers on the extractability of membrane proteins in a Triton X-114-based aqueous micellar two-phase system was examined. Cytochrome b5 (Cyt.b5), NADH-cytochrome b5 reductase (fp1), and NADPH-cytochrome P450 reductase (fp2), used as model proteins, were to be well-extracted into a surfactant-rich phase without polymers. In the presence of non-charged dextran, there were no changes in their extractability. However, by the addition of cationic diethylaminoethyl-dextran at the concentration range of 0.01~0.3%, the extractability of Cyt.b5 and fp2 was greatly reduced. In contrast, the use of anionic dextran sulfate at the same concentration range depressed the extraction of fp1 alone. A further increase in the polymer concentration or salt addition resulted in an increase in the extractability. From a calculation of net charge of the proteins, it was shown that Cyt.b5 and fp2 are negative and fp1 is positive at pH 7.4, where the extraction was conducted. Thus, the depressed extraction of the proteins in the presence of the charged polymers is attributable to the electrostatic interaction between the proteins and the charged polymers in the aqueous phase. These results indicate that charged polymers could be effective for the selective extraction of membrane proteins in a Triton X-114-based aqueous micellar two-phase system.
Keywords: charged polymer; Triton X-114; two-phase separation; membrane protein; extraction.
Mikio Aramata and Toshiaki Igarashi*
*Gunma Complex, Shin-Etsu Chemical Co., LTD., 2-13-1 Isobe, Annaka-shi, Gunma 379-0195
(Received 15 July 1998, Accepted 1 September 1998)29Si NMR is routinely utilized today in many laboratories as the method of choice for stractural determinations of organosilicon compounds. Usually, although solid state 29Si NMR is useful to obtain information about molecular dynamics, it is applied only in few cases for a silicone elastomer. On the other hand, the elucidation of the interface stating between silica and siloxane in a silicone elastomer is very important for design and developing of new materials as well as quality management. However, there was no suitable method to estimate the interface,but only to make a guess for an indirect measurement of the silica-siloxane interface. Therefore, we studied solid 29Si CP/MAS (cross polarization/magic angle spinning) NMR as a method for the analysis of this interface, and found suitable NMR conditions. This method is very useful and effective for examining the silica-siloxane interface, and is important for investigating the physical properties of a silic one elastomer. We could thus obtain surface information concerning of interaction between silica and siloxane.
Keywords : solid state 29Si NMR; silica-siloxane interface; silicone elastomer.
Takashi Nakano and Sunao Yamada*
*Department of Materials Physics and Chemistry, Graduate School of Engineering, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581
(Received 17 July 1998, Accepted 1 September 1998)The technique of optical second-harmonic generation (SHG) interference was applied to evaluate the nonlinear polarization vector of a monolayer assembly at the air/water interface. Coherent interference patterns of second-harmonic (SH) waves from a sample monolayer and a reference SHG-active material were clearly observed. Interference patterns were compared with three SHG-active amphiphilic dyes: ruthenium complex, stilbazole and hemicyanine dyes. The ruthenium complex and the hemicyanine dyes afforded almost identical interference patterns of SH waves, indicating the same sign of the nonlinear polarization vector in the monolayers with respect to the water surface. In spite of the fact that the stilbazole and the hemicyanine dyes have the same SHG-active moiety, an almost 180° phase shift of the interference patterns was observed. This result shows that the nonlinear polarization vector of the stilbazole monolayer is oppositely directed to that of the hemicyanine monolayer.
Keywords: optical second-harmonic generation (SHG); air/water interface; monolayer; SHG interference; molecular orientation.
Minoru Okumura, Kaoru Fujinaga, Yasushi Seike and Akihito Nagashima*
*Interdisciplinary Faculty of Science and Engineering, Shimane University, 1060, Nishikawatsu-cho, Matsue-shi, Shimane 690-8504
(Received 16 July 1998, Accepted 7 September 1998)A simple and rapid method for simultaneous in situ preconcentration of thiosulfate and sulfite in environmental waters samples has been developed based on solid-phase extraction using a couple of Sep-Pak C18 cartridges (SP-1 and SP-2). The first Sep-Pak C18 cartridge (SP-1) was treated with methanol and the second one (SP-2) with a tetrabutylammoniumhydrogen sulfate solution (TBAHS) before use. A water sample was taken into a graduated syringe to prevent oxidation of thiosulfate and sulfite by air, and to form DTMP derivatives of thiosulfate and sulfite, 2,2'-dithiobis(5-nitropyridine) (DTNP) was added. The mixture was passed through the connected SP-1·SP-2 cartridge, in which DTNP derivatives of thiosulfate and sulfite were retained on the SP-1 and the SP-2, respectively. The DTNP derivative of thiosulfate was eluted with 20% methanol, followed by measuring the absorbance of the eluate at 320 nm. The DTNP derivative of sulfite was eluted with a mixture of 40% methanol and TBAHS, and the absorbance was measured at 320 nm. The proposed method is applicable to brackish and sea water samples as well as freshwater samples.
Keywords: determination of thiosulfate and sulfite; preconcentration; solid phase extraction; Sep-Pak C18; brackish water and seawater.
Kenji Chayama, Norihisa Koyama, Haruo Tsuji* and Eiichi Sekido**
*Department of Chemistry, Faculty of Science, Konan University, 8-9-1, Okamoto, Higashinada-ku, Kobe 658-8501
**Department of Chemistry, Faculty of Science, Kobe University, 1-1, Rokkodai, Nada-ku, Kobe 657-8501
Several kinds of new acyclic di-, tri- and tetrathioether derivatives were successfully synthesized. The liquid-liquid extraction of metal ions with these reagents was examined. Soft metal ions such as silver(I), copper(I), mercury(II) and palladium(II) were selectively and successfully extracted. On the other hand, hard and intermediate metal ions were not extracted at all, with the exception of the copper(II)ion. The extraction behavior of silver(I) ion with reagents having 2,3 and 4 sulfur atoms and two hydrophobic terminal groups was examined in detail. The extraction constants of silver(I) ion with 2S and 3S reagents were derived. It was clarified that the extraction efficiency of the reagent for the silver(I) ion depends on the number of sulfur donating atoms and the hydrophobic character of the terminal group.
Keywords: extraction; silver ion; acyclic polythioether; analytical reagent; synthesis.
Hideyuki Matsunaga and Toshirou Yokoyama*
*Tohoku National Industrial Research Institute, 4-2-1, Nigatake, Miyagino-ku, Sendai 983-8551
(Received 16 July 1998, Accepted 8 September 1998)Iron(III)-bound chelating resins (Fe-LDA and Fe-LTA) with lysine-polycarboxilic acid functional groups have been prepared and their adsorption characteristics for arsenic(III) and arsenic(V) examined. A relatively rapid adsorption of both iron with LTA and arsenic with Fe-LTA compared to LDA was observed, whereas their adsorptivities were not as good as those with LDA, except for a wider pH range from 2 to 7 for the optimum adsorption. These are probably because of an excessive carboxilic functional group in LTA against LDA. The hydrophilic property of the carboxilic group may lead to a fast uptake of the metal ions with LTA, whereas it may block the site for the adsorption of arsenic in the Fe-lysine complex. The preconcentration of trace arsenic for a determination with ICP-AES was studied using column methods packed with Fe-LDA resin. At least a 10-8 mol dm-3 As(V) solution was easily concentrated to one thousand times with 1g of Fe-LDA resin and a flow rate of 1 cm3 min-1, and was successfully determined with ICP-AES without any hydride generation technique.
Keywords: preconcentration; trace arsenic(V); iron(III) complex of chelating resin; lysine-polyacetic acid moiety; ICP-AES.
Tetsuo Ohnishi, Seiichiro Higuchi* and Yohichi Gohshi**
*Department of Applied Chemistry, Faculty of Engineering, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656
**National Institute for Environmental Studies, Onogawa ,Tsukuba-shi, Ibaraki 305-0053
The near-infrared(NIR) FT- surface enhanced Raman scattering (SERS) was measured for various concentrations (3×10-6 M~1×10-7 M) of Crystal Violet adsorbed on Au colloids aggregated upon the addition of KCl. The absorption spectra and the scanning electron-microscopic images were measured for Au colloids aggregated with the addition of KCl and crystal violet adsorbed on aggregated Au colloids in order to estimate the aggregation of Au colloids. It was found that the morphology of Au colloids aggregated upon the addition of KCl did not change even after the adsorption of Crystal Violet. Plots of the relative intensity of the FT-SERS bands for various concentrations of Crystal Violet adsorbed on Au colloids against the concentrations of Crystal Violet were examined. In this result, plots of the relative intensity of the FT-SERS bands against the concentrations of Crystal Violet was found to be linear with Crystal Violet in the concentration range from 5×10-7 to 1×10-7 M, while the relative intensity were constant in the concentration range larger than 5×10-7 M. Thus, the intensity enhancement due to the SERS effect in this case was considered in view of micro analytical applications of NIR FT-SERS spectra.
Keywords: FT-Raman spectroscopy; FT-surface enhanced Raman scattering; near-infrared; Au colloid; Crystal Violet.
Tadao Sakai*, Akihiko Hirose** and Hideto Sasaki**
*Department of Applied Chemistry, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota-shi, Aichi 470-0392
**Department of Material Sciences, Tottori University, Koyama-cho, Minami, Tottori 680-0945
Tetraiodofluorescein(TIF) reacts with quinine(Qn) to form TIF2-(Qn+)2 at pH 7.0, and the color of the associate develops in 1,2-dichloroethane. When trace amounts of quaternary ammonium salts, such as cetylpyridinium chloride and trimethylstearylammonium chloride, are added to the TIF-Qn extraction system, the extractability of the associate is enhanced. It is assumed that new ternary ion associates, TIF2-·Qn+·CPC+, are formed at pH 9.0. Although the molar absorptivity of TIF-CPC associate at pH 6.8 is about 2.5×104 l mol-1 cm-1, that of the ternary ion associate with Qn is 8.0×104 l mol-1 cm-1. It is possible to determine quaternary ammonium salts at the 10-7 mol/l level using this method. Various amines do not interfere in the extraction system.
Keywords: tetraiodofluorescein; formation of ternary ion associate; addition of cinchona-alkaloids; quinine; cinchonine; cetylpyridinium.
Shigeru Tanaka*, Naoki Ohashi**and Ken Takahashi*
*Hitachi Research Laboratory, Hitachi Ltd., 7-1-1, Omika-cho, Hitachi-shi, Ibaraki 319-1292
**Tokyo Institute of Technology, Faculty of Engineering, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8552
In order to comprehend the voltage-current characteristics (V-I) of grain boundaries of Bi-doped ZnO varistors containing Mn and Co oxides, electrical measurements for a single-grain boundary were performed by the two-probe method in a scanning electron microscope(SEM). Although the non-ohmic V-I characteristics at single grain boundaries were confirmed, the non-ohmic behavior varied greatly for individual grain boundaries. Based on the results of measurements of the V-I characteristics of each additive doped ZnO ceramic, Mn and Co ions were thought to play important roles in the appearance of the nonlinear behavior of ZnO ceramics. The chemical composition of grain boundaries was analyzed by Auger electron spectroscopy (AES). The main additive Bi and secondary additive Mn ions were detected at the grain boundaries at high concentraions; however, their values were not constant. Such compositional inhomogeneity was strongly related to the inhomogeneous electrical property in the single-grain boundary of the ZnO varistor.
Keywords: ZnO varistor; grain boundary; nonlinear; V-I characteristics; inhomogeneity.
Koji Tohda and Yoshio Umezawa*
*Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033
(Received 17 July 1998, Accepted 14 September 1998)Resonant optical second-harmonic generation (resonant optical SHG) at the interfaces between aqueous sample solutions and liquid membranes, based on ionophores with different surface activities was measured in order to investigate the influence of the surface activity of ionophores on ion-selective charge separation. As ionophores with different surface activities, but bearing the same crown ether moiety as a binding site for the Na+ion, 4'-(p-octadecylbenzoateazo)phenoxymethyl-15-crown-5 (1) and 4'-(p-methylbenzoateazo)phenoxymethyl-15-crown-5 (2) were synthesized. The dependence of the SHG intensities on the polarization angle of the incident laser light showed that the average molecular orientations of ionophores 1 and 2 at the liquid/liquid interface were nearly equal to each other. When the concentration of Na+ ion in the aqueous sample solutions increased, increases in the SHG intensities were observed for both membranes based on ionophores 1 and 2. However, the SHG intensities based on ionophore 1 were stronger, suggesting that the surface activity of ionophore 1 is higher than that of ionophore 2. The change in the phase boundary potentials of the ionophore 1-based membrane in contact with the aqueous Na+ ion solutions was found to be larger than that of ionophore 2. An improvement in the potentiometric detection limit for Na+ ion was also shown for membranes based on surface-active ionophore 1. These results demonstrate that the extent of charge separation at the liquid/liquid interface, as observed by resonant SHG from primary ion complexes, is increased by using surface-active ionophores.
Keywords: molecular orientation; phase boundary potential; surface activity; detection limit; resonant optical second harmonic generation (resonant optical SHG); SHG active complex cation; liquid/liquid interface; potentiometry.
Shigeru Taguchi, Hiroe Yasuda, Chikako Wada, Sun Huifeng and Issei Kasahara*
*Department of Environmental Biology and Chemistry, Faculty of Science, Toyama University, 3190 Gofuku, Toyama-shi, Toyama 930-8555
(Received 17 July 1998, Accepted 14 September 1998)Two membrane filters, solvent insoluble and soluble, were applied to preconcentration and spectrophotometric determinations of a cationic surfactant present as an ion associate with an anionic surfactant in environmental water. The ion associate in 100 cm3 water sample was collected on a PTFE membrane filter by filtration, and eluted with 2 cm3 of methanol. The methanol solution was diluted to 15 cm3 with water. Then a buffer solution (pH 9) and a methyl-orange solution were added to the solution followed by being made up to 25 cm3 with water. The solution was filtered through a mixed cellulose ester membrane filter to collect the ion associate of the cationic surfactant and methyl orange. The ion associate was dissolved in 5 cm3 of DMF together with the membrane filter. The absorbance of the DMF solution was measured at 423 nm against a reagent blank. The recovery test for 10-6 mol dm-3 level of Zephiramine, a standard material of a cationic surfactant, was satisfactory. This method was applied to river-water samples containing domestic waste.
Keywords: cationic surfactant; spectrophotometry; insoluble and soluble membrane filters; ion-pair solid-phase extraction; methyl orange.
Teruo Hinoue, Junji Kobayashi and Hitoshi Watarai*
*Department of Chemistry, Graduate School of Science, Osaka University, 1-1, Machikaneyama-cho, Toyonaka-shi, Osaka 560-0043
(Received 22 July 1998, Accepted 14 September 1998)In order to examine the orientation of water-soluble porphyrin (5, 10, 15, 20-tetraphenylporphyrintetrasulfonic acid, TPPS) incorporated with admicelles of a cationic surfactant (cetyltrimethylammonium bromide, CTAB) adsorbed at a glass-aqueous solution interface, the internal-reflection spectra were measured at different angles of incidence with light polarized both perpendicular and parallel to the plane of incidence. The dependence of the absorbance at maximum absorption on the angle of incidence for the aggregate with a TPPS4-:CTA+ ratio of 1:4 could be theoretically explained in each case of the polarization. As a result, it is suggested that the 1:4 aggregate was distributed at random in the interfacial layer with a thickness of 90 nm. On the other hand, the dependence for the 1:7 aggregate could be explained only by separating the mean-square electric field of the parallel polarized light into two components {parallel (x) and normal (z)} to the interface. The result of a theoretical analysis indicated that an interaction between the z component and transition moments of TPPS was weak compared with that between the x component and the moments, suggesting that the TPPS4- ion of the 1:7 aggregate was not distributed at random, but was present obliquely to the normal of the interface.
Keywords: orientation; porphyrin; admicelle; adsorption; solid-liquid interface; total internal reflection spectroscopy.
Takanori Inoue*, **, Saori Yamaguchi and Teiichiro Ogawa*
*Department of Molecular and Material Sciences, Kyushu University, Kasuga-shi, Fukuoka 816-8580
**Present address: Department of Applied Chemistry, Oita University, Oita-shi, Oita 870-1192
The laser two-photon ionization technique has been applied for highly sensitive determination of anthracene in a small amount of the solution in a standard quartz cell and on a glass plate. The effects of electrode shape, laser pulse energy and applied voltage were investigated in order to improve sensitivity. The photoionization current obtained using a set of Cu sheet electrodes was larger than that using a set of Cu wire electrode, but the latter gave a smaller noise. The time profile of the photoionization signal of the sheet electrodes was sharp and high. The photoionization signal increased with the laser pulse energy up to 150 mJ/pulse·cm2 for the sheet electrodes. A set of wire electrodes exhibited lower efficiency of collecting signal than plate electrodes. Nevertheless, it gave a low detection limit of 2.0 f mol for a droplet sample of 2 µl due to its lower background signal.
Keywords: Laser; two-photon ionization; micro-scale sample; highly sensitive determination; anthracene.
Satoshi Takahashi*, Masayuki Futamata** and Isao Kojima***
*Joint Research Center for Atom Technology - Angstrom Technology Partnership, 1-1-4 Higashi, Tsukuba-shi, Ibaraki 305-0046
**Joint Research Center for Atom Technology - National Institute for Advanced Interdisciplinary Research, 1-1-4 Higashi, Tsukuba-shi, Ibaraki 305-8562
***National Institute of Materials and Chemical Research, 1-1 Higashi, Tsukuba-shi, Ibaraki 305-8565
A scanning near-field optical microscope (SNOM) was constructed using a xenon lamp as a light source. A photon scanning tunneling microscope configuration was used, in which thin-film samples were attached to the surface of a prism, and illuminated by the evanescent field generated by the total reflection of white light emitted by the lamp. The evanescent field was scattered and picked up with a sharpened optical fiber and dispersed with a multichannel spectrometer, yielding the transmission spectra of samples with a spatial resolution of approximately 100 nm. The transmission spectra of two thin-film samples, copper phthalocyanine and gold, were measured with the SNOM and a conventional spectrophotometer. For copper phthalocyanine, the spectra measured with the SNOM and the spectrophotometer agreed well with each other. In contrast, for gold the spectrum obtained by the SNOM exhibited an inverted feature compared to that determined by the spectrophotometer. The origin of the inverse spectrum is discussed based on the surface plasmons locally generated on the gold thin-film surface.
Keywords: scanning near-field optical microscope; photon scanning tunneling microscope; white light source; transmission spectrum; copper phthalocyanine; gold; surface plasmons.
Issei Kasahara, Motoki Terashima, Tomoko Mukaiyama and Shigeru Taguchi*
*Department of Environmental Biology and Chemistry, Faculty of Science, Toyama University, 3190 Gofuku, Toyama-shi, Toyama 930-8555
(Received 17 July 1998, Accepted 16 September 1998)A silica-gel immobilized xanthurenic acid (4,8-dihydroxyquinoline-2-carboxylic acid) was synthesized and its potential as an adsorbent for metal ions was studied. An aminopropylated silica-gel was reacted with 4-aminobenzoic acid in the presence of 1-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) to form aminobenzamide silica-gel. The product was diazotized with sodium nitrite and coupled with xanthurenic acid. The silica-gel immobilized xanthurenic acid had an adsorption capacity of about 50 µmol g-1 for copper ion. This is more than twice that for silica-gel immobilized 8-quinolinol by the same method. Copper, lead, and zinc were adsorbed quantitatively from the solution of over pH 1, 2 and 3, respectively. Cadmium, nickel, cobalt and vanadium were adsorbed over pH 4. Many metal ions were adsorbed under a more acidic condition than the adsorbent, silica-gel immobilized 8-quinolinol, because xanthurenic acid has a carboxyl group in the structure. The silica-gel immobilized xanthurenic acid was applied to the determination of trace copper, vanadium and nickel ions in river water and seawater samples by ICP-AES or GFAAS after preconcentration. It was possible to determine sub µg dm-3 levels of trace metals after a 100-fold preconcentration using synthesized silica-gel immobilized xanthurenic acid.
Keywords : silica-gel immobilized xanthurenic acid; xanthurenic acid (4,8-dihydroxyquinoline-2-carboxylic acid); preconcentration; trace metals; separation.
Tetsuo Okada*
*Department of Chemistry, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551
(Received 15 July 1998, Accepted 18 September 1998)A novel chromatographic model has been developed based on an electrostatic theory to describe the retention behaviors of ions in micellar chromatography. A previously developed electrostatic model for ion-exchange chromatography is applied to the interpretation of the retention of ions on the octylsilanized stationary phase adsorbing hexadecyltrimethylammonium chloride (HTAC). The ion-pair formation between HTA+ molecules and counteranions is assumed for both micellar and stationary phase surfaces; the ion-pair formation constant for HTA+ and Cl- is reasonably determined as 0.005 m-3 mol from a comparison of the calculated dissociation degrees with reported values. The resulting equations, derived by assuming the partition of ions to the spherical HTAC micelles, allow us to calculate the retention volumes of ions. The retention volumes of Br- and NO2- are well explained by calculations based on the present theory. The computed potential and the counteranion concentrations indicate that (1) the partition coefficients of ions are not constant, but are functions of the micellar concentration at relatively low added salt concentrations, and (2) at salt concentrations > 100 mM, both the surface potential and the counteranion concentration in solution nominally become constant; thus, the usual retention models based on two-phase partitions can reasonably describe the retention behaviors of ions in micellar chromatography.
Keywords: micellar chromatography of ions; retention model; electrostatic theory; cationic surfactant.
Kenji Chayama, Chieko Kurihara, Haruo Tsuji* and Eiichi Sekido**
*Department of Chemistry, Faculty of Science, Konan University, 8-9-1, Okamoto, Higashinada-ku, Kobe 658-8501
**Department of Chemistry, Faculty of Science, Kobe University, 1-1, Rokkodai, Nada-ku, Kobe 657-8501
A monoazadithioether {6-aza-3,9-dithiaundecane (ATU)} and a monoazatetrathioether {9-aza-3,6,12,15-tetrathiaheptadecane (ATH)} were successfully synthesized. Liquid-liquid distribution of the reagent between 1,2-dichloroethane and water was examined and compared with some azathiacrownethers. Since these reagents containing a nitrogen atom have a tendency to distribute to the organic phase at low pH, the formation of an ion pair of the protonated species with the picrate ion should be considered for metal-ion extraction. The liquid-liquid extraction of metal ions with these reagents was examined. Soft metal ions, such as silver(I), copper(I), mercury(II) and palladium(II) ions, were selectively extracted well. On the other hand, hard and intermediate metal ions were not extracted at all, with the exception of the copper(II) ion. The results show that the extraction efficiency of the ATU for the palladium(II) and mercury(II) ion are higher than that of the ATH.
Keywords: extraction; metal ion; monoazapolythioether; analytical reagent; synthesis.
Toshihide Ihara, Akira Nomura*, Tatsuro Nakagama and Toshiyuki Hobo**
*National Institute of Materials and Chemical Research, 1-1, Higashi, Tsukuba-shi, Ibaraki 305-8565
**Faculty of Engineering, Tokyo Metropolitan University, 1-1, Minami-Ohsawa, Hachioji-shi, Tokyo 192-0397
Diamide-type chiral stationary phases (CSPs) based on N-3,5-dimethylbenzoyl-L-valine alkylamide covalently bonded to silica gel at different coverage densities whether or not end-capped silanol groups were prepared. The authors had developed a new preparation method for end-capped CSPs in which silylation of the silanol groups is carried out first, and then a chiral selector is introduced into it by a hydrosilylation reaction. It was shown that the silanol groups are effectively covered by the new preparation method. The optical resolution of DL-amino acids on the end-capped CSPs gave excellent optical resolutions, especially when the coverage density was very low. In this study, molecular-dynamics simulations were applied to investigate the conformations of the non-end-capped CSPs and end-capped CSPs. It was found that with non-end-capped CSPs, the chiral selectors were lying almost parallel to the silica surface. In this case, several hydrogen bonds between the surface silanol groups and the chiral selector were observed. This was not the case if end-capped CSPs were simulated. The degree of ligand flexibility increased with reducing the number of residual silanol groups.
Keywords: computer simulation by molecular-dynamics method; diamide type chiral stationary phase; optimization of ligand coverage density; silylated silica gel.
Kensuke Arai, Kakujiro Watanabe and Fumiyo Kusu*
*School of Pharmacy, Tokyo University of Pharmacy and Life Science, 1432-1, Horinouchi, Hachioji-shi, Tokyo 192-0392
(Recieved 22 July 1998, Accepted 4 September 1998)A cell was designed for measuring the electrical potential oscillation across an octanol liquid membrane with a surfactant. The cell was made with an inverted U-shape so that two aqueous solutions can be poured into each side of the cell and an octanol solution can be layered on the top of the aqueous solutions. A pair of reference electrodes, made of silver/silver chloride, were connected to the two aqueous solutions by a pair of salt bridges on each arm of the cell. The shape, size, and material of the cell affected the reproducibility of the potential oscillation pattern concerning the amplitude, oscillatory period and induction period. A square section (10.0×10.0 mm) of each arm of the cell was recommended for good reproducibility of the oscillation pattern. The cell material affected the shape of the oil/water interface where a potential oscillation occurs. Poly(chlorotrifluoroethylene) gave reproducible oscillations better than those of quartz glass or polystyrene from the view point of hydrophobicity and solvent resistance. Poly(chlorotrifluoroethylene) was easier to process than Teflon.
Keywords: electrical potential oscillation; octanol liquid membrane; surfactant; cell design; poly(chlorotrifluoroethylene).
Takuya Shimosaka, Toshiaki Sugii, Katsumi Uchiyama and Toshiyuki Hobo*
Department of Applied Chemistry, Graduate School of Technology, Tokyo Metropolitan University, 1-1, Minamiosawa, Hachioji-shi, Tokyo 192-0397
(Received 17 July 1998, Accepted 6 August 1998)We developed a novel non-destructive depth profiling method involving incident-angle-dependent internal reflection spectroscopy coupled with thermal-lens spectroscopy. It was confirmed that the thermal lens originated from dyes in the vicinity of the prism/solution interface and that a depth-profiling analysis of the interface is possible. The detection limit of the proposed method with a 20 mW excitation laser corresponded to 1×10-5 absorbance unit, which is better than that of attenuated total-reflection methods. This method was applied to dye-adsorption phenomenon on a glass/solution interface. The result agreed well with that expected from the dissociation constants of both the silanol group and acridine orange.
Keywords: thermal lens; total internal reflection; depth profiling; adsorption; evanescent wave.
Soichi Yabuki, Fumio Mizutani and Yoshiki Hirata*
*National Institute of Bioscience and Human-Technology, 1-1, Higashi, Tsukuba-shi, Ibaraki 305-8566
(Received 13 July 1998, Accepted 15 August 1998)A polyion complex membrane containing fructose dehydrogenase (FrDH) was prepared. A FrDH solution, a polystyrene sulfonate solution and a poly-L-lysine solution were successively placed on a glassy carbon electrode; the electrode was then dried for 4 hr. The current response caused by electron transfer from FrDH to fructose was observed; the response time was short (~15 s). The response current was proportional to the fructose concentration up to 10 mM, and the lower detection limit was 1 mM (S/N=5). The electrode could detect the fructose concentration based on the current caused by the transferred electron.
Keywords: fructose biosensor; electron transfer; polyion complex membrane; fructose dehydrogenase.
*Faculty of Integrated Arts and Sciences, University of Tokushima, 1-1, Minami-josanjima-cho, Tokushima 770-8502
**Graduate School of Engineering, University of Tokushima, 2-1, Minami-josanjima-cho, Tokushima 770-8506
The droplet method, developed by Dasgupta et. al., was applied to soluble constituents contained in the gas phase. They diffused to and dissolved into the liquid drop as gas stream flows across a liquid droplet. From the view point of environmental analytical chemistry, this droplet has a potential sampling interface for such soluble constituents. This paper describes the coupling of this passive sampling interface with a sequential spectrophotometric analysis system, the behavior of the liquid droplet as a collection interface using a wind-tunnel method and nitrogen dioxide as a test gas, and an evaluation of the performance of this experimental arrangement. Several aspects of the demonstration of its applicability for measuring ppb levels of gaseous nitrogen dioxide in a rural atmospheric environment were obtained by using a polyacrylate wind tunnel with satisfactory results.
Keywords: droplet method; passive sampling; nitrogen dioxide; trace gas analysis; analytical instrumentation for environmental monitoring.
Takashi Mukuno, Koji Takahashi and Toshihiko Imato*
*Department of Chemical Systems and Engineering, Graduate School of Engineering, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581 (Received 17 July 1998, Accepted 11 September 1998)Four kinds of macrocyclic polyamine (MCPA)-immobilized polymer resins were prepared by reacting macroreticular-type chloromethylated polystyrene (CPS) with [9]aneN3, [14]aneN4, [15]aneN5 and [18]aneN6. The retention times of the solutes (dihydroxybenzene, hydroxybenzoic acid and dihydroxybenzoic acid isomers) were measured for a column packed with the MCPA-immobilized polymer resin by using a liquid-chromatographic method. Phosphate buffer solutions of pH 1.8, 4.5 and 6.8 were used as eluents. The distribution coefficients of the solutes on the MCPA-immobilized polymer resin were calculated from the capacity factors obtained by the retention time and volume of the resin and liquid phases in the column. Linear polyamines, such as diethylenetriamine and triethylenetetramine, were immobilized on the polymer resin, and the distribution coefficients of the solutes on these resins were measured as well as the unmodified resin for a comparison with the MCPA-immobilized polymer resin. The MCPA-immobilized polymer resins showed higher adsorptivity for the solutes than did the linear polyamine-immobilized polymer resin. Especially, the [15]aneN5-immobilized polymer resin showed selective adsorptivity for the isomers of dihydroxybenzene among the MCPA-immobilized polymer resin. The distribution coefficients of the MCPA-immobilized polymer resin for hydroxybenzene isomers increased in the order para < meta < ortho isomer. The same sequence was observed for the isomers of hydroxybenzoic acid when phosphate buffer solutions of pH 1.8 and 4.5 were used as eluents. For dihydroxybenzoic acid isomers, the distribution coefficients of the MCPA-immobilized polymer resin increased in the order 3,5- =3,4- <2,5- isomers. The hydrogen-bonding interaction between the MCPA-immobilized resin and the solutes is estimated to be more effective than the electrostatic interaction for the distribution of the solutes on the MCPA-immobilized resin.
Keywords: macrocyclic polyamine; liquid chromatography; distribution coefficient; hydroxybenzene derivatives.
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