BUNSEKI KAGAKU Abstracts

The vapor pressure and flash point of motor gasoline were determined using gas chromatography (GC). The contents of 24 major hydrocarbon components of gasoline and ethyl t-butyl ether (ETBE) were measured by GC. The saturated vapor pressure of each component was calculated using Antoine’s equation. The vapor pressure of gasoline was found to be calculated as the sum of the product of the content value and the saturated vapor pressure of each of the 25 components. The calculated vapor pressures of regular gasoline and bio-gasoline (regular gasoline containing bio-ETBE) were in good accordance with vapor pressures measured by Reid method, which is established in Japanese Industrial Standards (JIS). The vapor pressure of 0 – 50 wt% evaporated gasoline in the 10 – 40°C temperature range was calculated in the same way. The calculated vapor pressures of evaporated gasoline also agreed well with values obtained by Reid method. The flash point of 0 – 50 wt% evaporated gasoline was calculated by Le Chatelier’s law using the content value measured by GC. The calculated flash points were found to be about the same as the measured values by Tag closed cup method, the official method in JIS. The method is effective for assessing the flammability of gasoline used in arson cases because GC is widely available, and requires a smaller amount of the sample compared to the conventional methods in JIS.

The application of trace element analysis using ICP-MS was investigated for the forensic discrimination of charcoal samples. Eleven kinds of commercially available charcoal samples were collected and used for the experiments. A small amount of each charcoal was burned in an electrical furnace to make ash. Approximately 5 mg of ash was sonicated with a mixture acid of 250 μL of nitric acid, 250 μL of hydrochloric acid and 500 μL of hydrofluoric acid, followed by heating to dryness. The residue was dissolved again in 500 μL nitric acid, and diluted to 10 mL to prepare sample solutions. Qualitative analysis of the sample solution using ICP-MS indicated that charcoal ash contained elements such as Mn, Fe, Cu, Zn, Rb, Sr, Ba, La, Ce, Nd, Pb. Four trace elements (La, Ce, Nd, Pb) were selected for the determination, and a comparison for the discrimination of different ash samples. Ash made from different charcoals tend to exhibit larger difference in the concentration of these elements than the variation within a sample. The ranges of the mean ± 2 SD for each element were compared for all of 55 pairs among 11 different ash samples. The combination of 4 elements allowed for the discrimination of all possible pairs, although no single element could achieve complete discrimination. The analysis and comparison of trace elements by the present method was quite effective for the forensic discrimination of charcoal ashes.

In order to provide therapeutic advice or diagnosis, it is important to determine the concentration of a pharmaceutical agent or biomarker in biological fluids. However, it is difficult to determine a target analyte selectively due to interferences derived from a large number of co-existing biological components. In order to overcome this problem, we have developed selective detection methods for pharmaceutical agent or biomarker in the presence of biological components using a specific structure or characteristic of the target analyte. Among related studies, this review describes two principle methods : namely (1) selective fluorescence derivatization methods for aryl halide or terminal double bond based on palladium coupling reaction, and (2) selective detection methods for quinone by chemiluminescence and fluorescence reactions of utilizing the specific characteristics of quinone.

Spectroscopic studies in the far-UV (FUV) region (120 – 200 nm) are very attractive for both basic sciences and applications, since various kinds of electronic transitions are observed in the region. However, because of very large absorption coefficients, full-scale FUV spectra for liquids and solids could not be measured easily. We have recently developed a totally new FUV spectrometer based on attenuated total reflection (ATR) that enables us to measure the full-scale spectra of liquid and solid samples in the 140 – 200 nm region. In this paper, at first we outline the characteristics and advantages of the FUV spectroscopy, and then discuss our studies on the development of an ATR-FUV spectrometer and its applications to analytical chemistry. At the end, we introduce our newly developing time-resolved ATR-FUV spectrometer.

We proposed a rapid screening of methamphetamine using an X-ray foreign body inspection system based on dual-energy X-ray method. Theoretical calculation of the discrimination capability with the dual-energy X-rays was performed by α-curve model using relative proportion T (X-ray transparency) of high- and low-energy X-rays transmitted through the material based on the attenuation coefficient of the materials. Due to the absorption rate difference in material of X-rays generated by X-ray sources with different energies, discrimination of materials becomes possible. >From the scatter plot : the slope of α-curve of 11 materials including methamphetamine vs. their effective atomic number (Z_eff.), the illegal drug group was clearly separated from other material groups (organic, inorganic, and metal). The actual experiments were performed at 6 materials (methamphetamine, sugar, flavor enhancer, Si gel, Al powder, and Fe powder) by using available X-ray foreign body inspection system equipped with a dual energy X-ray sensor. Obtained X-ray inspected image with the dual-energy mode can discriminate methamphetamine from other materials. The results obtained by the X-ray inspection system were in approximate agreement with those obtained by the theoretical calculation. By this proposed method we expect the improvement of X-ray inspection systems for identification of illegal drugs hidden in small luggage or international mail.

A new hydrophilic stationary phase (Ac-DAA resin) that was acetylated after immobilizing a diallylamine-acrylamide copolymer into a hydrophilic base resin was prepared. The retention characteristics for the water-soluble compounds on the Ac-DAA resin were evaluated by comparisons with the diallylamine-maleic acid copolymer immobilized stationary phase (DAM resin). The copolymer-immobilizing content of the Ac-DAA resin was approximately 2.5-times higher than that of the DAM resin, but the contents of holding-water and hydration water were almost the same. Water-soluble compounds, such as nucleobase, nucleoside and glucoside, were clearly retained on both stationary phases by hydrophilic interaction. However, for the nucleobases, the specific affinity, which was estimated to be a hydrogen associativity, was observed in the Ac-DAA resin. Further, the strength of the electrostatic interaction in both stationary phases was compared using ionic water-soluble compounds as analytes. The electrostatic interaction of the Ac-DAA resin was stronger than that of the DAM resin. However, by adjusting the buffer solution pH of the mobile phase above 8, the electrostatic interaction of the Ac-DAA resin could be suppressed without a decrease of retention based on the hydrophilic interaction. It was concluded that the Ac-DAA resin was effective for the separation of water-soluble compounds including ionic compounds by employing the mobile phase adjusted with an appropriate pH.

A chelating fiber was prepared with a wet spinning technique using a mixture of viscose and slurry containing wet-milled chelate resin immobilizing carboxymethylated pentaethylenehexamine. The solid-phase extraction behavior of several elements, such as Cd, Cu, Fe, Ni, Pb, and Zn, using the chelating fiber was almost the same as that using the chelate resin. The chelating fiber could effectively extract the elements under the conditions at a high flow rate and a large solution volume. The extractions of alkaline earth elements, such as Mg and Ca, were observed under weakly acidic, neutral, and alkaline conditions. The presence of coexisting ions, including sulfate ion, interfered with the extraction of elements. These facts would be due to the low content of the chelate resin in the chelating fiber. The solid-phase extraction technique using the chelating fiber was applicable to the separation of 6 kinds of elements, including Cd, Co, Cu, Fe, Ni and Zn, in the certified reference material (EU-L-1 wastewater).

Marine debris plastics (50000 to 150000 tons) have washed up every year to Japan. Seventy percent of this stranded debris is polystyrene (PS). Drift and stranded PS is presumed to generate styrene oligomer (SO) in the marine environment. In this study, field work was carried out to clarify the pollution of the coastal area by such chemicals as SO derived from PS. Therefore, sea water and sand were collected at the investigation sites, while visual observations were made in Okinawa island and Yaeyama islands (Iriomoteshima Island and Ishigakishima Island). These are representative islands to which many drift plastics arising from Asian countries are washed up. From a SIM-GC/MS analysis of picked-up sea water and sand, SO (styrene monomer phenylethylene, SM ; styrene dimer, 2,4-diphenyl-1-butene, SD ; styrene trimer, 2,4,6-triphenyl-1-hexene, ST) were detected at every sampling site. Among SO, ST was found to be contained most abundantly in the sea sand ; 4400 ng/g of ST was detected as the maximum level. The SO composition determined by an analysis of sea sand and water tended to be almost similar to the SO composition of the purified PS thermal decomposition of the markets PS.

We have applied a polycapillary X-ray focusing optic to a micro X-ray fluorescence analysis (micro-XRF) instrument. The spatial resolution of the developed instrument was about 10 micrometers. We used the micro-XRF instrument to determine the migratory environmental history of a fish (ayu : Plecoglossus altivelis) from the Sr intensity profile in a otolith (ear stone). The obtained 2D elemental map showed a high concentration of Sr distributed in the center of the otolith, indicating that this ayu stayed in the sea during the corresponding period. In order to investigate the migratory environmental history of the ayu, we compared captured fishes with cultivated fishes based on the Sr intensity profile. The results suggest that captured fishes include four cultivated fishes. We could easily estimate the migratory environmental history of fishes by using this method and measured nondestructively in air.

In this study, we examined the carbon stable isotope ratio (δ¹³C) of alcohol and the oxygen stable isotope ratio (δ¹⁸O) of water in commercially supplied Honkaku Shochu (Mugi Shochu, Imo Shochu, Kome Shochu, Soba Shochu, Kokuto Shochu, Sakekasu Shochu, Awamori) to confirm them as a potential index for verifying the geographical and raw material origins. The small-scale Kome Shochu brewing experiment revealed that the material water affects the δ¹⁸O value of water in it at around 25% alcohol. The δ¹⁸O values of water in Honkaku Shochu are correlated with the latitude (R² = 0.67), regardless of the kind of raw materials used. The δ¹³C values of alcohol in Kokuto Shochu (−17.6 ± 0.8‰), made from brown sugar, are higher than those in other Honkaku Shochu, made from rice, barley, sweet potato, buckwheat, and Sake lees. Mugi Shochu, made from domestic barley (−26.2 ± 0.8‰), is characterized by a lower δ¹³C of alcohol than that has no indication of the geographical origin of barley ( – 24.8 ± 1.4‰). Imo Shochu, made from Imo Koji (−28.4 ± 0.2‰), is characterized by a lower δ¹³C of alcohol than that from Kome Koji ( – 27.8 ± 0.4‰). These results suggest that the δ¹³C values of alcohol and the δ¹⁸O values of water in Honkaku Shochu are partially useful for confirming the geographical and raw material origins.

The binding constants (K_B) of four kinds of 1-alkyl-3-methylimidazolium ions to nonionic surfactant micelles have been determined through changes in the electrophoretic mobility in capillary zone electrophoresis. Larger binding constants were obtained with much bulky 1-alkyl-3-methylimidazolium ions. A linear free-energy relationship was observed with the K_B values against the van der Waals volume of the cations. The K_B values obtained with 1-alkyl-3-methylimidazolium ions are almost comparable with a series of N-alkylpyridinium ions previously reported. Both the binding constants and the linear free-energy relationship are smaller than the binding of anionic alkylbenzene sulfonate ions. The results have suggested a weak binding of cations to nonionic surfactant micelles.