BUNSEKI KAGAKU Abstracts

Inorganic and inorganic/organic nanoporous materials synthesized by a supramolecular templating approach have been extensively studied, because they provide a stable and uniform nano-cavity. Since molecular functions inside the nano-cavity depend on the cavity structure, it has been expected that nanoporous materials with a well-defined pore structure can be used to control the chemical process by the pore structure. In this paper, we introduce structural features of mesoporous silica, which is one type of nanoporous material. In addition, the characteristic features on the acid-base equilibrium reaction, pH, and viscosity inside the silica mesopore are also described.

The methylene blue method was troublesome and susceptible to operational error. In our improved method, we use only one vial (50 mL glass centrifuge tube) to determine the concentration of anionic surfactants as methylene blue active substances (MBAS). The combination of hand-shaking 20 times with shaking (1000 rpm) for 5 minutes by a shaker leads to a calibration curve (n = 4) with a high linearity (average r = 0.996) and a high sensitivity (average 1.07 μM⁻¹) within 0 – 0.12 μM. In the optimum condition, the recovery of sodium dodecyl sulfate (SDS) was 94.7 ± 3.3% (n = 3) for a water extraction solution of blank quartz fiber filter, 92.3 ± 1.5% (n = 4) for that of atmospheric aerosol collected on a quartz fiber filter, and 90.8 ± 3.5% (n = 3) for the throughfall of Japanese ceder (Cyptomeria japonica), respectively. This improved method revealed that the concentration of anionic surfactants in atmospheric aerosol ranged from 44.9 to 163 pmol m⁻³ (84.3 pmol m⁻³ on average, n = 8) at Shinjuku, Tokyo in May, 2011.

Laser ionization/time-of-flight mass spectrometry (LI/TOF-MS) is a selective analytical means for the measurement of aromatic hydrocarbons in the gas phase. In the present study, a simple and sensitive method was developed for direct measurements of species in an aqueous solution. A volatile 2,4-xylenol in aqueous solution was directly detected by using an ionization laser emitting at 266 nm. Moreover, when a vaporization laser emitting at 532 nm was irradiated into the tip of the capillary column, a signal enhancement of the analyte was achieved; even without a frit, the molecules could be introduced into a vacuum chamber in a pulsed form. Furthermore, using a narrow capillary column (e.g., inner diameter 25 μm) as an inlet nozzle as well as using a vaporization laser, the aqueous solution was smoothly introduced into the vacuum system; then, the fluctuation of the signal intensity for the analyte was reduced. On the other hand, a low-volatile phenylalanine in an aqueous solution could be detected when the ionization laser was adjusted to the tip of the capillary. The present method has potential for use in the sensitive, selective and real-time monitoring of aromatic compounds in environmental water samples and in culture media.

The storage stabilities of four kinds of diffusive sampling devices, (DSD-DNPH for carbonyls, DSD-OZONE for ozone, DSD-TEA for acid gases and DSD-NH₃ for basic gases), were evaluated. Based on the resulting storage stability, chemical substances found both indoor and outdoor air were measured by using DSD-samplers. Almost all DSD-samplers, except for nitrogen dioxide (DSD-TEA), showed degradation in less than 7.2% for four weeks at room temperature. The storage stability of nitrogen dioxide collected in the DSD-TEA showed degradation in 9% for four weeks at room temperature. It is suggested that nitrite was oxidized to nitrate during the storage term at room temperature. In measurements of acid gases using DSD-TEA, when the analysis is not performed within two weeks, the samplers should be stored in a refrigerator at 4°C. In applications to real air samples, it was observed that almost all chemical substances, except for nitrogen dioxide, were higher in the summer than in the winter. The mean nitrogen dioxide concentration was significantly higher at 15 times in the winter than in the summer. It was suggested that the primary sources indoors are combustion processes, such as unvented combustion appliances, e.g. gas stoves.

This paper presents an overview based on the latest topics concerning detailed investigations of the molecular orientation in organized molecular films from the monomolecular layer to the several-layer levels by using polarized near-edge X-ray absorption fine-structure spectroscopy (NEXAFS) while taking advantage of the polarization and absorption of soft X-rays. Especially, while focusing on functional polymers (containing copolymers) having a plurality of functional groups in the molecular structure, an approach for elucidating the ultimate structure formed in sub-nanometer scale spaces is introduced.

Gene detection based on electrochemical techniques has been gaining much attention in recent years, not only because it provides simple and rapid methods for measurement and detection, but also for the easiness of downsizing the instrumentation. Ferrocenylnaphthalene diimide, which forms a pseudo-catenane complex with double-stranded DNA, has been developed to be used in an electrochemical detection system for double-stranded DNA coupled with a DNA probe-immobilized electrode. To improve the performance of electrochemical gene detection, FND or its derivatives, which can form a supramolecular complex, have been under development. Here, we review an electrochemical DNA or DNA-related enzyme detection technique based on supramolecular complex formation.

Although destructive analysis has been frequently utilized for determining hormones and chemicals, it does not provide direct evidence of their physiological activities. Since we recently developed superluminescent and stable luciferases to improve the sensorial properties of the probes, the present review specifies our original speculation and the developing process. We also highlight a new technology using a luciferase that estimates hormonal activities of endocrine hormones and chemicals with both high sensitivity and sample throughput, using a single-chain probe that is genetically designed and synthesized with a luciferase as the molecular backbone. To demonstrate the advantages of the methodology, we exemplify (i) single-chain probes that illuminate the activities of sex hormones and stress hormones and (ii) the visualization of apoptosis signaling using bioluminescent capsules. (iii) We also developed a bioluminescence assay device that efficiently utilizes the advantages of the single-chain probes. The merits of the device, e.g., high sample throughput and multicolor imaging ability, were exemplified with a single-chain probe set that visualizes the bifacial activities of woman’s sex hormones. The present technology that quantitatively visualizes the activities of hormones and chemicals may be broadly applied for the screening of drug candidates, and for risk assessments of endocrine disruptors and toxic chemicals.

A rapid and safe method was developed for the field discrimination of various liquid samples using two dyes, brilliant green and methyl red. “Pipette for discrimination” was developed as a new method for the discrimination of liquid samples. The pipette is composed of two dye layers (brilliant green and methyl red) and three colored layers (silica gel, florisil and polypropylene). When liquid samples are applied to the pipette, various color patterns of the colored layers were observed. The pipette method performed as follows; 8 types of liquid samples, such as water, methanol, ethanol, 2-propanol, acetone, acetonitrile, ethyl acetate and toluene, were discriminated with regard to each other.

Twenty types of mayonnaise-type dressings were analyzed by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) for developing their forensic discrimination. Volatile compounds, fatty acids and unsaponifiables in samples were analyzed by GC/MS. The colorants and saccharides were analyzed by LC/MS. The major components of mayonnaise-type dressings were fats and oils, vinegar, and egg. These three major components were all analyzed in this study. Moreover, twenty samples could not be discriminated by only each analytical result, but twenty samples could be discriminated by combining those analytical results. Accordingly, the GC/MS and LC/MS analyses of mayonnaise-type dressings in this study were very useful for the discrimination of mayonnaise-type dressings.

The acceleration of a complexation of Cr(III)-4-(2-pyridylazo)resorcinolato (PAR) complex with microwave heating was achieved. Though it required more than 100 min for completing the complexation reaction of Cr(III) with 4-(2-pyridylazo)-resorcinol by heating with a hot-water bath, the reaction was completed within 2 min by microwave heating with a household microwave oven. The successful application of the acceleration of the complexation reaction by microwave heating to the derivatization of the determination method for trace Cr(III) by a pre-column derivatized ion-pair reversed-phase partition high-performance liquid chromatography was also accomplished. A detection limit as low as 7.7 nM was achieved, and a successful application of the proposed method to the determination of Cr(III) in the certified reference material of a river-water sample, JSAC 0302-3b, was also performed.