BUNSEKI KAGAKU Abstracts

Two-dimensional spectroscopic imaging of infrared light emitted from a combustion flame was captured using an infrared video camera combined with a band-pass filter. Rovibrational emission band arising from carbon dioxide or carbon monoxide was used for the spectroscopic imaging. After temperature correction, two-dimensional distribution of actual concentrations was calculated by standard addition method. The actual concentration estimated by the in situ infrared emission spectroscopy showed good agreement with ex situ gas chromatography analysis of an exhaust gas. Complete and incomplete combustion regions in the flame were clearly visualized by two-dimensional plotting of concentrations ratios between carbon dioxide and carbon monoxide.

For human safety, we investigated how metals (aluminum, cadmium, chromium, copper, lead, manganese and tin) are leaked from fused slags by contact with acid rain and basic concrete effluent. We obtained 13 fused slags prepared from general garbage. Elution tests (6 hours interval in the room temperature) by using diluted nitric acid (instead of acid rain), water, and diluted potassium hydroxide (instead of basic concrete effluent) were performed. As a result, it has been understood that the elution rates are greatly different according to both the kinds of metal and slag. The influence of aluminum was especially large. The elution concentrations of aluminum from the slags were ppm-level in alkaline. On the other metals, the elution concentrations were lower than that of aluminum. The elution pattern also differed from aluminum, and it seemed to influence the character of the metals (dissolubility in alkaline and ability to be an oxyanion).

Humic acids (HAs), the major components of organic matter in soils, play an important role in global carbon cycling and regulation of the mobility and fate of plant nutrients and organic and inorganic pollutants. Despite intensive research on soil HAs during the past 200 years, the chemical nature of HAs is not fully understood. Studies using a variety of spectroscopic techniques have led to major advances in understanding the chemical nature of HAs, but the macromolecule structure and chemical heterogeneity of HAs is a serious hindrance. Therefore, the characterization and grouping of HAs with various chemical natures has been studied. ¹³C NMR analysis and high performance size exclusion chromatography (HPSEC) are the most powerful and popular tools in this study field. We here describe : (i) optimization of the HA measuring condition in both analyses, (ii) characterization of the chemical nature among HAs in various soil origins, and (iii) HA grouping by statistical analysis based on information data obtained by ¹³C NMR and HPSEC analyses. Thirty-three of HAs from various soil origins were analyzed and, conclusively, they were classified clearly by their chemical nature.

We identified minerals on the surface of polished surfaces of Itokawa dust particles by micro-Raman spectroscopy. Their sizes ranged from 30 to 150 μm across. Olivine, pyroxenes, plagioclase and chromite were identified, which correspond to SEM/EDX observations and analyses of these samples. Although Raman spectroscopy is suitable for the identification of maskelynite (diaplectic glass transformed from plagioclase), we could not find maskelynite in all of the samples investigated. This fact suggests that the shock stage of the samples did not reach S4, which is consistent with the other results of the Hayabusa initial analyses.

The solid-phase extraction (SPE) method for the preconcentration of trace amounts of Pb(II) and Cd(II) using hydrotalcite (HT), and its determination by graphite furnace atomic absorption spectrometry (GFAAS) were investigated. The Pb(II) and Cd(II) were quantitatively adsorbed onto HT at pH 4.0–10.0, respectively. The adsorption isotherms were found to be fitted by the Langmuir equation. After the solid-phase (metal ions adsorbed HT) was separated from the sample solution by a membrane filter, it was dissolved in 1.5 mol dm⁻³ hydrochloric acid. An aliquot of the resulting solution was injected into a cup-type graphite furnace, and the absorbances of Pb and Cd were measured by AAS. An ashing temperature of 300°C and an atomizing temperature of 2150°C were selected for Pb, and an ashing temperature of 250°C and an atomizing temperature of 1600°C were selected for Cd, respectively. The detection limit for Pb(II) was 0.01 μg/100 mL, and that for Cd(II) was 0.0008 μg/100 mL. The proposed method was applied to the determination of trace amounts of Pb(II) and Cd(II) in fresh-water samples.

Continuous measurements of air pollutants [NO_x (NO₂, NO), SO₂, and O₃] by passive samplers were made in the mountains around the Kyoto basin for the purpose of elucidating the effects of acidic deposition within various ecosystems. The sampling sites were Mt. Hiei, Mt. Daimonji, 4 other mountains and a clean site (Kuroda). The behavior and origin of atmospheric NO_x, SO₂, and O₃ from 1996 to 2005 were analyzed. The seasonal changes in the concentrations of NO₂ at mountains around the Kyoto basin showed winter maxima and summer minima. Atmospheric NO₂ concentrations in the summer were higher in 2000 and those in the winter decreased after 2004. A positive relation was obtained between the NO₂ concentrations and the formation days of a temperature-inversion layer. The concentrations of atmospheric SO₂ in mountains around the Kyoto basin were lower than those of atmospheric NO₂, and their seasonal changes were small. However, the concentrations increased from September 2000 to 2001. A large quantity of SO₂ discharge by the eruption on Miyake Island may have affected the increase of atmospheric SO₂ concentrations in Kyoto. Atmospheric O₃ concentrations in the mountains around Kyoto basin have their origins in both O₃ productions by photochemical reactions and stratospheric input. Furthermore, a sudden increase of O₃ concentrations was observed when air mass may have been transported from China to Japan by backward trajectory analysis.

A method for the determination of methylmercury in foods by GC-MS method following phenylation was investigated. Methylmercury was isolated by acid leaching (mixture of potassium bromide solution and sulfuric acid saturated with copper sulfate), the extraction of methylmercury into toluene, then back-extraction into L-cysteine solution. Methylmercury was phenylated with sodium tetraphenylborate, and extracted into n-heptane. Phenylated methylmercury was purified by PSA mini-column, then analyzed by GC-MS (SIM). As a result of the performance evaluation using five certified reference materials (CRM-7402a, CRM-7403a, BCR-463, ERMCE-464 and DOLT-4), trueness (%), repeatability (RSD%) and reproducibility within laboratory (RSD%) was 98-108, less than 10 and less than 15, respectively. It was shown that the method satisfy the performance satisfied criteria set by Ministry of Health, Labor and Welfare.

A monolith-like continuous macroporous adsorbent sintered with a reverse-phase/anion exchange-type polymer and a polyethylene powder was prepared for solid-phase extraction (SPE). The sintered SPE adsorbent showed high permeability, which was equal to that using bulk adsorbent. Several drugs such as caffeine and acetaminophen could be extracted quantitatively even at 30 mL min⁻¹ of a sample flow rate. Neutral and basic drugs, such as acetoaminophen, caffeine, theobromine, atenolol, procaine and procainamide, were clearly retained by hydrophobic interaction ; they were quantitatively eluted with methanol. Acidic drugs, such as acetylsalicylic acid, naproxen and salicylic acid, were strongly retained by both a hydrophobic interaction and an anion exchange interaction. The acidic drugs retained were not eluted with only methanol, whereas they were quantitatively eluted with methanol containing 1% of formic acid. The sintered SPE adsorbent could produce an ion-exchange interaction effectively without any influence based on the water repellency of polyethylene. The monolith-like macroporous SPE adsorbent is easy to handle and is useful for the SPE of drugs and the other compounds. Additionally, the sintering technique using a bulk adsorbent and a polyethylene powder would be applicable to the preparation of SPE adsorbents having various shapes.

For the quantitative analysis of sennoside A (SA) and sennoside B (SB) in health tea, the stability of standard solutions prepared according to the Japanese Pharmacopoeia was investigated. Standard solutions of SA and SB began to decompose one day after preparation at room temperature. The results suggest that the instability of the standard solution may lead to uncertainty in quantification. Whereas it was difficult to confirm the degradation products of SA and SB by means of ultraviolet absorption measurements (wavelength, 366 nm), an unknown peak derived from the degradation product was detected in fluorescence measurements. Structure analysis revealed that the degradation product was rhein-8-glucoside. It was also found that SB having an erythro configuration is more unstable than SA having a threo configuration. A stability study of the standard solutions showed that such solvents as THF/water (7 : 3) prevented degradation at 4°C storage but not at 37°C storage. However, when 0.1% phosphoric acid/acetonitrile (4 : 1) was used, the degradation of SB was fairly suppressed even at 37°C. This solvent is considered to be more useful for the preparation of standard solutions of SA and SB than conventionally used methanol.

Currently, approval and license examinations of Food for Special Dietary Uses (FOSDU) have been held by six testing institutions. For proper operation of the FOSDU system, it is important to maintain the analytical accuracy, however, the accuracy of analysis among the groups has never been discussed. For that reason, we carried out a study to clarify the factors affecting the interlaboratory analytical accuracy with vitamin B₁₂ contents in fortified food. As a result, it was found to be important that it has to adhere closely to the analytical method for the assurance of reproducibility, and has to use the most suitable approximate method against the calibration curve and/or to take account the proliferation potential of strain for improvement of reproducibility in the microbiological assay for the vitamin B₁₂ quantitation.