BUNSEKI KAGAKU Abstracts

A platinum phosphide sample was constituted of PtP₂ and Pt₅P₂ which were determined by X-ray diffraction. It had the shape of a thin plate (thickness of about 0.5 mm), and had a platinum-like color. It was not dissolved in aqua regia and other acids, because it was an acid-resistant substance. However, it could be dissolved in a mixture of hydrochloric and nitric acids, after it was heated sufficiently in concentrated sulfuric acid or melted sodium disulfate. Most of the phosphorus was first of all extracted from the phosphide by heat in concentrated sulfuric acid or melted sodium disulfate. On the other hand, most of the platinum remained in it, and the shape of the thin plate virtually remained the same. The platinum was dissolved in a mixture of hydrochloric and nitric acids. Platinum and phosphorus in the phosphide were determined by ICP optical emission spectrometry (ICP-OES) without their loss during dissolution.

Double-helix DNA, because of its unique morphology, is capable for capturing chemical hazards of planer structures, mainly due to the so-called intercalation interactions. Its intrinsic properties, such as mechanical weakness and high water solubility, however, have long been drawbacks restricting practical applications. These intrinsic difficulties of DNA were overcome in this study by encapsulation of the double-helix DNA using polyurethane by the formation of DNA/polyurethane composite foams (DNA/PUCF). The adsorptive capability of the resulting DNA/PUCF was evaluated using ethidium bromide, acridine orange and eosin B, as typically hazardous chemicals having planer structures. DNA/PUCF has shown high ability for absorbing ethidium bromide and acridine orange, both carrying positively charged moieties ; but no ability was found for eosin B, which is a negatively charged species, indicating that the charges on the hazardous molecules play an important rule in determining their distribution into the base-pairs of DNA where the intercalation takes a place. The investigation of DNA by using silver ions (Ag^＋) as reactive ions gave experimental evidence to confirm a fact that DNA involved in the DNA/PUCF kept their double-helix structures. DNA/PUCF is robust, mechanically strong, durable, and highly useful for eliminating positively charged, water-soluble type of hazardous chemicals of planer structures.

In order to develop an analysis method of skin conditions for humans, we have been investigating cathepsin L (Cat L) activity derived from stratum corneum as a biomarker. In the present work, an analysis method for a low amount of Cat L activity was demonstrated that was made possible by collecting stratum corneum using a tape stripping, concentrating stratum corneum sample solution and using an inhibitor and a fluorescent substrate of Cat L. Within the range of Cat L activity between 0.003 and 0.04 U/L, the calibration curve for this method showed coefficient with R²＝0.98. The Cat L activity ranged between 0.005 and 0.028 U/L in all of the stratum corneum samples in the subjective evaluation. It was indicated that this analysis method had a sufficient range for the analysis of human Cat L activity. The determined coefficient between the Cat L activity and the total protein showed 0.09, which was a comparatively low level. Therefore, it was considered that the Cat L/total protein ratio might be a useful index of the skin condition for humans. Thus, it was indicated that this analysis method might be suitable for an easy analysis of Cat L activity.

Rapid extraction for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin like-PCBs (DL-PCBs) in soils and sediments was developed by microwave-assisted extraction (MAE). Six grams of samples were extracted with mixed solvents composed of 6 mL of toluene, 2.4 mL of water, and 4.8 mL of ethanol at a temperature of 125℃ for 30 min. After purification and concentration, the samples were measured by a high-resolution gas chromatograph interfaced to a high-resolution mass spectrometric detector. The concentrations of PCDD/DFs and DL-PCBs were equivalent to results obtained by the conventional method using Soxhlet extraction (SE). The extraction efficiencies (MAE/SE×100) were in the range of 81〜116％ and the reproducibility of MAE was below 19％ for all samples. Furthermore, it was found that our extraction method could be applied to wet samples. This indicates that the analysis time of dioxins can be reduced, because it is possible to omit an air drying step.

A comparison of results obtained using argon/glow discharge mass spectrometry (Ar/GD-MS) and fundamental parameter/X-ray fluorescence analysis (FP/XRF) was made by analyzing of cobalt (Co) alloys. The relative sensitivity factors (RSF) used for GD-MS quantitative analysis were determined using six commercial Co alloy standard reference materials. The analysis objects comprised 16 elements contained in Co alloys : C, Al, Si, P, S, Ti, Cr, Mn, Fe, Ni, Cu, Nb, Mo, Sn, La, and W. A glow-discharge cell for disk samples was used. A sample mask made from Ta, a part of the anode, was employed ; it had an internal diameter of 12 mm. The discharge parameters were 1 kV and 3 mA. Samples were put on a liquid sample cup with an adherent 6.3-μm-thick polypropylene film and subjected to a FP/XRF measurement. The sensitivity coefficients (K_ij) of XRF for Co alloys were determined through measuring identical standard substances, such as GD-MS, and processing thereof using UQ5 software. A commercial Co alloy, Haynes188, was subjected to chemical analysis ; the GD-MS, chemical analysis, and FP/XRF results were compared. The FP/XRF results of the main components (Cr, Fe, Ni, and W) agreed well with the GD-MS and chemical analysis results. The analytical accuracy was satisfactory as 0.18％ (Cr)〜0.46％ (W) in RSD. However, some overestimation occurred for minor, elements such as Cu and La, at low concentrations, where RSD was 10〜17％. On the other hand, the GD-MS results agreed well with results of chemical analysis obtained from P and S at the trace impurity level, minor components, to main components. The analytical accuracy of GD-MS was shown to be within 2％ as RSD for most elements, from main components, such as Cr (RSD : 1.2％), Ni (1.0％), and W (0.89％), to elements of trace impurity level, like S (4.5％), including minor components.

The present study investigated the optimal method for the multi-element quantification of 9 elements in soy milk : calcium, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, and zinc. Results obtained using ICP atomic emission spectrometry were compared with those obtained by atomic absorption spectrometry, which is the standard method. The same sample was measured using both ICP atomic emission spectrometry and atomic absorption spectrometry. The percentage of minerals recovered by ICP atomic emission spectrometry ranged from 99.3％ to 102％, which was equivalent to that by atomic absorption spectrometry. Therefore, a good result with standard deviation was obtained. The mineral contents of 16 samples of commercially-available soy milk products were measured. The Cu content was significantly proportional to the amount of soybean solids (P＜0.001). Moreover, although relationships did not attain statistical significance, the contents of Fe, Zn, K, Mg and P were proportional to the amount of soybean solids, and were highest in soy milk, followed by prepared soy milk and soy milk beverage. The Ca content of modified soy milk was significantly higher than that of soy milk and soy milk-based beverages (P＜0.001). Furthermore, the Na content in soy milk was significantly lower.

The Japan Society for Analytical Chemistry carried out its eighth and ninth series of proficiency testing on the determination of dioxins (polychlorodibenzo-p-dioxins, polychlorodibenzofurans and dioxin-like polychlorobiphenyls). The samples were a mixture of two kinds of incinerator dust for the eighth testing and synthetic wastewater for the ninth. These proficiency testing concerning the ability of analytical laboratories were based on ISO/IEC Guide 43-1, “Proficiency testing by interlaboratory comparisons”. The eighth testing were carried out from August to November ’06 with the participation of 101 laboratories, and the ninth from August to November ’07 with the participation of 91 laboratories. Laboratories were evaluated using z scores based on a robust method. As a result, 87 laboratories (86％) were estimated to be “satisfactory (| z |≦2)”, 9 laboratories (9％) as “questionable (2＜| z |＜3)” and 5 laboratories (5％) as “unsatisfactory (| z |≧3)” in the eighth testing using incinerator dust. In the ninth testing using wastewater, 76 laboratories (84％) were estimated to be “satisfactory”, 5 laboratories (5％) to be “questionable” and 10 laboratories (11％) to be “unsatisfactory”.

In the steelmaking industry, rapid and skill-free analysis methods have been required for energy saving and unskilled workers. At first, a flow-injection procedure combining electrolytic sample decomposition and inductively coupled plasma atomic emission spectrometry (ICP-AES) was proposed. This system was applied for silicon and phosphorus in steel. The analytical results were in a good agreement with those of the JIS methods. A quick evaluation technique of the defects of steel materials by laser induced breakdown spectroscopy (LIBS) was also established. LIBS could detect specific elements in defected parts due to alumina inclusions and contaminations from continuous casting mold flux as well as slag. The proposed method made it possible to inspect the steel defects within 30 minutes at the production site. Furthermore, supersonic jet resonance enhanced multi-photon ionization time-of-flight mass spectrometry (Jet-REMPI-TOFMS) was applied for real-time observations of the naphthalene emission behavior for heated coal samples in N₂ gas flow using an electric tube furnace. It is suggested that naphthalene is formed by breaking the naphthyl group contained in thermally unstable sites of coals. Those techniques were applied for practical uses, and improved the production yield and energy conservation.