BUNSEKI KAGAKU Abstracts

A small amount of nanobeads suspension was dropped onto a partially polymerized PDMS/Glass plate. The nanobeads in the drop were self-assembled by a capillary force, accompanied by solvent evaporation. Subsequently, a three-dimensional (3D) nanobeads array structure was formed on the plate. The plate with a 3D nanobeads array structure was placed inside an ultrasound bath, and then the nanobeads outside the PDMS layer were removed, while the nanobeads lying on the PDMS layer remained. In this way, a two-dimensional (2D) nanobeads array structure was fabricated. The sensor chip for a transmission-type surface plasmon resonance (SPR) sensor was prepared by forming a thin layer of gold on the 2D nanobeads array structure, and then a novel transmission-type SPR sensor using the sensor chip was developed. The calibration curve for sucrose solutions obtained on the developed SPR sensor was linear for concentrations under 2000 mM with a correlation coefficient of 0.967. In contrast to the sensor chip with a nanohole array structure generally-used for a transmission-type SPR sensor, the developed sensor chip with the 2D nanobeads array structure has an advantage that the sensor chip can be easily prepared at low cost without the use of an expensive electron beam lithography system.

We researched on effect of an organic solvent on the preparation of a gold nanoparticle two-dimensional array (AuNP 2D-array). AuNP 2D-array substrates were developed by using a liquid-liquid interface method. Four organic solvents (toluene, n-hexane, cyclohexane and diethyl ether) and four polar solvents (methanol, ethanol, 1-propanol and acetonitrile) were examined and compared with each other. Crystal violet (CV) molecules on the AuNP 2D-array substrate were measured by surface-assisted laser desorption/ionization mass spectrometry; we compared combinations of solvents and several experimental results (signal intensity of [CV-Cl]⁺ ion, fragment ratio of CV molecules, pictures of AuNPs thin film at the liquid-liquid interface and SEM images of AuNP 2D-array substrate). As a result, we found that the combinations of solvents, Tol+MeOH or n-Hex+MeOH, are suitable for a SALDI-MS substrate.

The atmospheric mercury (Hg) concentration was determined during Aug. 2010 – Jun. 2012 in Kagoshima City and compared with values reported for 1996 – 2002. The average concentrations were 10.8 ng m⁻³, 13.4 ± 10.1 ng m⁻³, 5.52 ± 3.85 ng m⁻³ and 1.9 ± 0.5 ng m⁻³ for 1996 – 1997, 1997 – 1998, 1999 – 2002 and 2010 – 2012, respectively. The recent atmospheric Hg level in Kagoshima City was the same as the Japanese background levels. The Hg concentration was higher in the summer than other seasons and a significant correlation was obtained between the Hg concentration and the air temperature. These results suggested that the evaporation of Hg from surfaces according to temperature was an important factor to increase the Hg concentration in ambient air. On the other hand, the atmospheric Hg concentration could not be enhanced directly by the fumarolic activity of the Sakurajima volcano located in Kagoshima City. In this study, 3.5 ng m⁻³ (= mean + 3 standard deviation) was defined as a background level in the Kagoshima City. The days were observed to have higher values than the background level in Kagoshima City; there were 5 days during the investigation period. From the back-trajectory over China, it could be considered that the observed high concentration of Hg in air showed the possibility of long-range transportation from the East Asia region.

A high-performance liquid chromatographic (HPLC) method with fluorescence detection was developed for the quantification of polycyclic aromatic hydrocarbons (PAHs) in cigarette mainstream and sidestream smoke particulates. Fifteen kinds of PAHs classified as priority pollutants by the US EPA were quantified with six perdeuterated PAHs as internal standards. The smoke filter samples obtained from 3 brands of cigarettes using standardized smoking conditions were extracted with dichloromethane, and then treated with tandem solid phase extraction cartridges (Silica and Neutral Alumina). The limits of detection ranged from 0.24 to 2.2 pg, and were more sensitive than those by GC-MS. The analytes were quantified by using the internal standards, and the developed method achieved sufficient reproducibility and accuracy. The PAH levels in mainstream and sidestream smoke from 3 cigarette brands were in the range of 0.2 – 305 ng cigarette⁻¹ and 26.4 – 6160 ng cigarette⁻¹, respectively. The total PAH content in sidestream smoke was more than 10 times higher compared with that of mainstream smoke. This method should be useful as an optional analytical method to quantify PAHs in cigarette smoke particulates.

Nondestructive X-ray analyses were applied to ancient Egyptian copper-red glass artefacts to investigate the coloring mechanism of the glass and relationships between their coloring mechanism and chemical composition. X-ray absorption near edge structure (XANES) analyses revealed that there are two mechanisms of red coloring in ancient Egyptian copper-red glass: a surface plasmon effect due to the presence of metallic copper nano-clusters, and the precipitation of reddish Cu₂O crystals in the glass matrix. In the case of glass objects from the New Kingdom Period, the earliest stage of copper-red glass production in ancient times, only the crystalline-Cu₂O was identified as being a coloring agent. In both coloring mechanisms, most of the copper contained within the copper-red glass exists as colorless Cu⁺ ion in the glass matrix. It was suggested that the coloring mechanism of copper-red glass changed from crystalline-Cu₂O coloring to metallic-Cu nano-cluster coloring in ancient Egyptian glass production. Additionally, it was revealed that two kinds of copper-red glass were produced in ancient Egypt during the Ptolemaic/Roman Period by regulating the chemical state of Cu and the chemical composition of the flux of the glass.

An amperometric acid sensor for determining the titratable acidity in shochu has been developed using three plastic formed carbons (PFC) as working, reference, and counter electrodes. The detection was based on the voltammetric reduction of 3,5-di-tert-butyl 1,2-benzoquinone (DBBQ) in the presence of acids. Acetic acid in an unbuffered ethanol-water mixture solution of DBBQ gave rise to a new peak (termed the prepeak) on a voltammogram at more positive potential than that corresponding to the normal reduction peak of DBBQ. The prepeak current was found to be proportional to the acetic acid concentration from 0.09 to 4.0 mM with a correlation coefficient of 0.999. The sensor of the dimension and weight being 55 (W) × 31 (D) × 109 (H) mm and 100 g can be utilized for determining the acidity of shochu, ranging from 0.09 to 4.0. By the present sensor, 0.55 mL of shochu and 30 sec of analytical time were required for the determination of acidity in shochu. The titratable acidity in twelve kinds of commercial shochu determined by the amperometric acid sensor was compared with that determined by the conventional potentiometric titration method using 0.01 M NaOH. The correlation coefficient of both analytical results was 0.994.

The measurement of ethanol concentration in solution by near-infrared (NIR) spectroscopic analysis is generally used. On the other hand, in alcoholic beverages analysis, especially an analysis of Japanese sake, the ethanol concentration assay by this method is so far undeveloped. Coexistent compounds in Japanese sake have one or more absorbance peaks in the NIR area, and these absorbance peaks overlap with that of ethanol. Thus, the influence of coexisting compounds in Japanese sake could not be ignored in previous NIR spectroscopic analysis. Recently, according to selecting wavelengths in the NIR area, the measurement of the ethanol concentration in Japanese sake by a NIR spectroscope was developed; this equipment allowed us to measure the ethanol concentration of Japanese sake directly. In this work, by using a NIR spectrometer and a distillation-oscillatory densimeter, the ethanol concentration in sixty-four sorts of Japanese sake produced in many regions in Japan was analyzed. For an ethanol concentration from 13% to 18% (v/v), the values from the two methods were consistent with that displayed on these bottles and packs; most of the standard deviations in the NIR spectrometer were less than those of the conventional method. Moreover, the geographical influence on the measurement of the ethanol concentration, such as room temperature, room humidity, and any slight change of the voltage in the room, was not observed in both of these methods.

A method for quick and real-time observations of a solid surface at nanometer scale is described. The principle of the method is as follows. Soft X-rays from a synchrotron light source are irradiated on a solid surface, and the total photoelectrons are expanded and focused on a screen using electrostatic lenses. When the energy of X-rays is scanned and the brightness is plotted, we can obtain micro X-ray absorption (micro-XAFS) spectra in all regions of the image. The spacial resolution of the method was 40 nm. In order to more quickly observe a microscopic image and measure micro-XAFS spectra, the soft X-rays from the bending magnet were focused using a newly developed poly-capillary. As a result, we succeeded in observing a clear image at 10 ms for a bulk sample. We have also tried to shorten the measuring time of the micro-XAFS spectrum. For a Si-SiO₂ sample, it has been demonstrated that micro-XAFS spectra in all regions of an image can be obtained in the order of 10 sec. It is concluded that real-time observations of chemical-states at nanometer scale are possible by the present method.

A simple and rapid in situ separation and preconcentration method for the determination of molybdenum in environmental waters has been developed based on solid-phase extraction using a Sep-Pak CM cartridge loaded with zirconium (Zr-SP), followed by the determination of molybdenum with GFAAS. The adsorption and desorption behaviors of molybdenum on a Zr-SP were strongly affected by the pH of the solution. Molybdenum in the solution was quantitatively adsorbed on a Zr-SP at lower than pH 7. On the other hand, the desorption of molybdenum adsorbed on the Zr-SP was quantitatively made with solutions of higher than pH 12. A molybdenum solution adjusted to 0.2 mol L⁻¹ nitric acid was passed through a Zr-SP at a flow rate of 10 mL min⁻¹ for the adsorption of molybdenum. In field work, a guraduated syringe was used for the collection of molybdenum to make these operations simple and easy by hand in a short time. A mixture of 0.05 mol L⁻¹ sodium hydroxide and 0.05 mol L⁻¹ potassium sodium tartrate as an elute was found to more easily eluent molybdenum from Zr-SP than a 0.05 mol L⁻¹ sodium hydroxide solution. Therefore, the molybdenum adsorbed on the Zr-SP was eluted by passing 9 mL of a mixture of 0.05 mol L⁻¹ sodium hydroxide and 0.05 mol L⁻¹ potassium sodium tartrate through the Zr-SP at a flow rate of 0.5 mL min⁻¹. The eluted molybdenum was determined with GFAAS after adjusting the acidity with nitric acid. The established method was successfully applied to river water samples taken from some rivers in the eastern area of Shimane Prefecture, Japan. Relatively high concentrations of molybdenum were found in river water samples near molybdenum mines located in this area.