BUNSEKI KAGAKU Abstracts

In this report, attaching importance to the results of joint research with Ehime prefecture, the studies on combustion method, gas treatment, and monitoring of combustion condition, which were essential to a dioxin-reduced small size incinerator named “Ehime method”, and the demonstrations of this type incinerator at Uoshima village in Ehime are presented. This method is a system that is combined combustion after gasification and gas treatment by adsorbents : artificial zeolite and activated alumina with on-site control methods ; harmless of used adsorbent and monitoring of combustion condition. It is of practical use for dioxin reduction of a small size incinerator, control of which is difficult.

In the present study, we introduced into the laminar diffusion flame to a KrF excimer laser to analyze the formation mechanism and characterization of in-flame soot and its precursor such as polycyclic aromatic hydrocarbons (PAHs). The test fuel was hexane, which was a typical paraffin-type hydrocarbon fuel. The spatial distributions of PAHs and soot were measured using laser-induced fluorescence and laser-induced incandescence methods. The graphite structure of soot was analyzed using a Raman spectroscopic method. From these results, a G-band attributed to the vibration mode of the graphitic lattice and a D-band attributed to the disordered graphitic lattice were detected. When the sampling position approached the downstream part of the flame, G/D ratio (ratio of these bands) of the soot increased. Further, the G/D ratio of PAHs was also detected. It was shown that the G/D ratio attributed to the PAHs and soot was in proportion to the flame temperature.

In order to estimate the dispersion of arsenic released thorough mining activity, a total of 39 soil samples were taken around the Gejiu tin mine, Yunnan, China. The highest total arsenic concentration, 1.1 × 10⁴ mg kg⁻¹, was observed in the tailing. Although the concentration in soil samples was slightly lower than that in the tailings, higher than 5.1 × 10² mg kg⁻¹ of arsenic was still observed. A linear relation was observed between SiO₂ and Fe₂O₃, which can be used for estimating the dispersion of the tailings. A trend was observed that the higher the chemical index of alteration, the lower the arsenic concentration, which suggests the elution of arsenic from tailings through weathering.

This paper describes some modifications of the distillation method for the determination of total cyanide content in soil. Generally, the total cyanide content in soil has been determined by a sediment survey method, which is based on JIS K 0102 in Japan. However, in the recovery test of spiked ferrocyanide in the simulated soil, the recovery ratio of total cyanide was less than 50% by this method. In order to improve the distillation method, some acids and some addition reagents, which were described in ISO, standard methods and JIS, have been examined. As a result, a distillation method using phosphoric acid (20 mL), copper chloride (89 g L⁻¹, 10 mL) and tin chloride (500 g L⁻¹, 5 mL) for the sample (10 g) has been recommended. This method (NSOF method) could recover more than 90% of the total cyanide from spiked ferrocyanide, ferricyanide, Prussian blue, copper cyanide (I) and potassium cyanide in the simulated soil samples. In addition, this method was applied to three real contaminated soil samples. As a reason of the low recovery ratio of total cyanide by the sediment survey method, we confirmed that Prussian blue was formed by the react with ferrocyanide and ferrous or ferric ions in soil under the phosphoric acid condition.

A system for in situ time-resolved X-ray diffraction (XRD) under hydrothermal condition has been developed using an originally designed autoclave cell in combination with high-energy X-rays from a synchrotron radiation and a photon-counting pixel array detector. The autoclave cell has welded beryllium X-ray windows. Thus, there are practically no interference signals from the window materials, and it is possible to obtain high-quality XRD patterns with very stable cell temperature and pressure. The system was applied to the formation process of autoclaved lightweight concrete (ALC). Evolutions of both crystalline and non-crystalline phases, structural and composition changes of those phases during the hydrothermal reaction were successfully observed.

We have been developing optical nanoprobes based on glycoconjugated gold nanoparticles that selectively and sensitively detect carbohydrate–protein interactions. Nanoparticle aggregations induced by specific carbohydrate–protein interactions shift plasmon absorption to longer wavelengths and increase plasmon light scattering. The dissociation constants (K_d) for carbohydrate–protein interactions were calculated from UV-Vis spectral data by performing computer simulations and assuming aggregates with a protein : glycoconjugated gold nanoparticle ratio of 1 : 2. The obtained K_d values were much higher than those of monosaccharaides. These results reveal that the presence of multiple carbohydrate ligands on gold nanoparticle surfaces significantly enhances the affinity for carbohydrate-binding proteins relative to that for monosaccharaides. Carbohydrate-binding proteins can be detected with a high sensitivity using such glycoconjugated gold nanoparticles. In this method based on plasmon absorption, the maximum wavelength shifts are proportional to the mannose-binding protein (Concanavalin A) concentration in the range of 12–45 nM ; the limit of detection (LOD) was 4.0 nM. The detection sensitivity can be further enhanced by using a method based on plasmon light scattering ; the corresponding LOD for Concanavalin A was 0.4 nM.

Little has been known about the cutaneous emanation of chemical compounds absorbed into the human body in working or living environments. The purpose of this study was to estimate the amount of chemical compounds absorbed into body by skin gas analysis using gas chromatography/mass spectrometry (GC/MS). Skin gas was gathered from the left hand of ten subjects (seven men and three women) working and living in different environments. We detected organic compounds, such as benzene, toluene, xylene, 2-ethyl-1-hexanol, and p-dichlorobenzene in the skin gas of each subject. There was a significant difference in the average concentration of 2-ethyl-1-hexanol between two groups of subjects belonging to two different laboratories. There was a subject whose toluene was significantly higher than the remaining nine. Because the subject worked for a gas manufacturer, it was supposed that he was exposed to toluene in his workplace. It was suggested that the concentrations of chemical compounds detected in skin gas was influenced by differences in the working or living environments.

Trimethylsilyl (TMS) derivatives of catechins in tea drink were analyzed by gas chromatography/mass spectrometry (GC/MS) in this study. The polyphenols of green-tea leaves are composed of four major catechins : (−)-epicatechin (EC), (−)-epigallocatechin (EGC), (−)-epicatechin gallate (ECG), and (−)-epigallocatechin gallate (EGCG). Bottled teas contain not only these epicatechins, but also their epimers : namely (+)-catechin (C), (−)-gallocatechin (GC), (−)-catechin gallate (CG), and (−)-gallocatechin gallate (GCG). Although the GC/MS is an analytical method useful for identification of unknown compounds, the simultaneous determination of these eight catechins has not been reported because of difficulty in separation between CG and GCG. GC/MS analysis under the analytical condition proposed in this study showed that the eight catechins could be successfully separated and identified. This analysis was very useful for discrimination between a hot water extract of tea leaves and bottled tea, and was applicable to discrimination between green tea and other types of teas, such as oolong tea and black tea.