BUNSEKI KAGAKU Abstracts

Pentaethylenehexamine was immobilized on acrylic fiber in 2-propanol/water at 100°C for 15 h. The obtained fibrous adsorbent was able to adsorb gold(III) effectively at pH 1. The adsorption capacity for gold(III) was 2.5 ± 0.1 mmol g⁻¹ (mean ± standard deviation, n = 3). The adsorption was rapid; 80％ of gold(III) was adsorbed even at a flow rate of 63 mL min⁻¹ when 0.10 g of the fibrous adsorbent and 100 mL of a solution containing 5.1 × 10⁻² mmol L⁻¹ of gold(III) at pH 1 were used. The adsorbed gold(III) could be quantitatively desorbed using 1 mol L⁻¹ hydrohloric acid containing 0.1 mol L⁻¹ thiourea. The fibrous adsorbent barely adsorbed 21 kinds of elements, including alkaline earth elements, such as calcium(II), and transition metal elements, such as manganese(II) and iron(III), at pH 1. The solid-phase extraction using the fibrous adsorbent was applicable to the separation of gold(III) in a real wastewater.

Selective collection and separation characteristics of precious metal ions (Au³⁺, Ag⁺, Pt²⁺) were found by using poly(2-acetoacetoxy ethyl vinyl ether) {poly(AAEVE)} as a pH-sensitive polymer under the coexistence of L-ascorbic acid. The phase-transition phenomenon was shown at pH = 9.1 in an alkaline aqueous solution containing acetone. Sixty mg of poly(AAEVE) was solved with a mixed solution of an acetone (1.2 mL) and 1 M sodium hydroxide aqueous solution (1.2 mL). The polymer solution (2.4 mL) and 0.1–1.0 g L⁻¹ L-ascorbic acid 1 mL were added to 4 mL of an elements solution; they were then gently shaken in order to from a homogeneous solution. One M of acid 2.6 mL was added to the solution and the collection behavior of metals was examined. A sedimented phase of the polymer was produced with less than pH = 9.1. As a result of a detailed examination for 62 kinds of elements, each extraction percentage of 93％, 93％ and 99％ was obtained for gold(III), silver(I) and platinum(II). In addition, the collection percentage was found to be changed in accordance with the L-ascorbic acid concentration.

DNA analyses are required for food labeling regulation to differentiate commercially important fishery products, because many of the distinguishing morphological features are no longer identifiable after food processing. In Japan, the Law Concerning Standardization and Proper Labeling of Agricultural and Forestry Products (JAS Law) of revision in 1999 has been establishing quality labeling standards for almost of foods and beverages. In perishable foods, “Name of the food” and “Country of origin” must appear on the food label. In processed foods, “Name”, “Names of ingredients”, “Net contents”, etc. must appear on the food label. The DNA-based genetic methods for species and product identification are very important to certify correct food labeling in the market places. Several fishery products have been investigated to develop the DNA-based analytical methods for examining the authentication of species name and origin identification. We introduce the species identification methods for tuna, horse mackerel, mackerel, cod roe, and yellowtail-related species.

Under laser-assisted three-dimensional atom probe analyses, the delay time of field evaporation at the shadow-side of the laser was measured. The samples were three materials of different thermal diffusivity: Al, W and GaAs. The curvature radius of each tip-sample was estimated from the TEM image. The flight distances, depending on a detected position, were corrected based on the Pythagorean Theorem. After corrections, the flight times of the ions emitted at the laser-side and shadow-side were compared. The delay time of field evaporation was also observed in the measurement of an Al sample (high thermal diffusivity). The delay time of the sample with lower thermal diffusivity was longer. Concerning each sample, the quadratic curve was fitted to the relationship between the delay time and the detected position. We defined the thermal factor under laser-assisted field evaporation as the reciprocal of the coefficient of the quadratic curve. These thermal factors had a correlation to the thermal diffusivities. Thus, we concluded that the thermal factor defined in this study was an important factor under laser-assisted field evaporation.

Semi-volatile samples were analyzed by high performance liquid chromatography (HPLC) coupled with a corona charged aerosol detector (corona CAD). Nine phthalates with different side chains (carbon numbers of 1—8) were used as samples, and their concentrations were changed from 6–188 μg mL⁻¹. Acetonitrile, methanol, tetrahydrofuran (THF), acetone, 2-propanol and their binary mixtures were used as mobile phase. All experiments were carried out under isocratic conditions. Phthalates with higher vapor pressure show lower sensitivity for corona CAD. Dimethyl phthalate (DMP) showed no peak in the experiments. The signal intensities of phthalate observed by corona CAD were drastically changed with the compositions of the mobile phase. When mixtures of acetonitrile and methanol were used as the mobile phase, all of the phthalates, except for DMP showed the maximum intensities at the composition of acetonitrile/methanol = 35/65 (v/v). Acetonitrile/THF and methanol/THF also showed the maximum intensities at the compositions of acetonitrile/THF = 80/20 (v/v) and of methanol/THF = 70/30 (v/v). On the other hand, the intensities were changed monotonously using acetonitrile/acetone or acetonitrile/2-propanol as mobile phases. The estimated sensitivity (S_m) of corona CAD, calculated from an empirical equation, agreed qualitatively with all of the results monitored for the binary mixtures of mobile phase. S_m generally varies depending on the size of aerosol prepared by nebulization of an analyte solution in corona CAD. The size of the aerosol changes with the composition in the mobile phase. Therefore, the signal intensity of a sample component observed by corona CAD should be changed with the mixed composition of the mobile phase solvents.

In this study, we examined a method to discriminate Coffea Arabica (Arabica) and Coffea canephora (Robusta). In order to explore the respective biomarkers, an ion attachment ionization mass spectrometer (IA-MS) equipped with a direct inlet probe (DIP) was used. It was possible to measure solid samples directly by DIP. Furthermore, in IA ionization mass spectra, because only quasi-molecular ion peaks are obtained, the mass spectra showed the characteristic pattern, which reflected the states in the sample. Therefore, easy screening analysis was possible. By using DIP/IA-MS, we measured nine kinds of roasted coffee beans. As a result, peaks estimated to be Kahweol palmitate and 16-O-methylcafestol palmitate were detected from Arabica and Robusta, respectively. In addition, this method offers an estimation of the mixed ratio of the Arabica and Robusta in not only roasted coffee beans milled, but extract with and without heat sterilization.

Nuclear reaction analysis (NRA) is a powerful tool for determining the absolute hydrogen concentration in materials. Based on the assumption that all hydrogen atoms form silanol species in glasses, NRA allows for measurements of the water concentration. For a precise determination of the absolute hydrogen concentration, it is necessary to obtain the γ-ray detection efficiency of the system. However, it is confirmed that some polymer materials suffer from damage under the ¹⁵N²⁺ bombardment where a substantial amount of hydrogen is lost. This causes a large error in the quantification of the hydrogen concentration in samples. In the present study, it was shown that a Kapton^® thin film mounted on a Cu block is useful for the calibration standard for determining the γ-ray detection efficiency.

In order to investigate the long-range transfer mechanism of inorganic small spherical particles in wet-depositions, such as rime, snow and glaze, on the summit of Mt. Kajigamori (1399.4 m alt.), Kochi, Shikoku Island, in 2011–2013, the residue was obtained with a 0.45 μm pore-sized filter and then, a single-particle analysis was carried out for ones below 3 μm by using a Low-Vacuum Tabletop scanning electron microscope-energy dispersion X-ray spectroscopy (SEM-EDX). Particles were classified in the six categories according to their compositions. In this work, it was found that two majour types of distribution patterns of the particles were presented. It was proposed that these depended on the 24 hrs back-trajectory, such as a typical fly-ash category in Huabei type and a Fe–Si–Al particle category in Dongbei type in China. The Zn-included particles were also analyzed.