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Volume 56, Issue 2
Displaying 1-6 of 6 articles from this issue
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Review
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Shuichi YAMAMOTO, Hideyoshi YOSHIOKA, Ryoshi ISHIWATARI2007 Volume 56 Issue 2 Pages 71-91
Published: 2007
Released on J-STAGE: March 05, 2007
JOURNAL FREE ACCESSA brown complex or refractory organic materials, which are often called humic substances and kerogen, are ubiquitous in aquatic and terrestrial environments. They play an important role in carbon and material cycles in the environment. Although a clear understanding of their molecular nature is essential, some knowledge of their chemical structure and the mechanism by which they form and change in time on Earth is still limited. The molecular characterization of these materials is difficult due to their insolubility and complex macromolecular nature. From this review, we highlight the following three types of chemical degradation techniques, which are becoming popular in the molecular characterization of these organic materials: i.e. pyrolysis gas chromatography-mass spectrometry (py-GCMS), pyrolysis in the presence of tetramethylammonium hydroxide coupled to gas chromatography-mass spectrometry (py-TMAH-GCMS), and gas chromatography-mass spectrometry after bond-selective chemical degradation (chemical degradation-GCMS). Both py-GCMS and py-TMAH-GCMS are often used as small-scale analytical methods. py-GCMS is commonly suitable for materials (e.g. kerogen in rocks) that produce non-polar or less-polar materials (e.g. hydrocarbons) on pyrolysis, while this technique may not be suitable for young humic substances, because they tend to produce polar materials by a thermal reaction of heteroatomic (such as oxygen, nitrogen) functional groups. py-TMAH-GCMS overcomes some of the weak points of py-GCMS. Since this technique is based on the cleavage of labile C-O bonds, such as ester, amide and ether bonds with simultaneous methylation (thermochemolysis), it can be applied for characterizing macromolecular organic matter, which is on the way of change from biomacromolecules (e.g. lignin, proteins, carbohydrates and lipids). Modern sequential chemical degradation-GCMS techniques involving the successive cleavage of different types of bonds (S-C bond, ether bond, double bonds and sub-units linked to aromatic moieties etc.) in refractory organic materials are described.
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Research Paper
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Masao INOSE, Kyoko FUJIMOTO, Satoshi KINOSHIRO, Atsushi CHINO2007 Volume 56 Issue 2 Pages 93-98
Published: 2007
Released on J-STAGE: March 05, 2007
JOURNAL FREE ACCESSAn analytical method of precipitates/inclusions existing a few μm from the surface in steel sheets has been established. Less than 0.1 g of a steel surface was electrolyzed, and the extracted precipitates/inclusions were decomposed with 2-step microwave digestion (1st step with H2SO4 and 2nd step with HF-HNO3). Al, Ti, Mn, Cu, Nb, V and Mo in the sample solution was determined by ICP-MS. The lower limits of detection in the surface of the steel sample were less than 1 μg g-1 for all elements that formed precipitates/inclusions. Furthermore, the concentration of the chelating agent (acetylacetone) in the electrolyte was reduced to 0.2%, which enabled us to quantitatively extract precipitates/inclusions that were unstable in the conventional 10% AA electrolyte. The procedure was applied to steel samples before and after annealing, and depth profiles of the precipitates/inclusions were obtained.
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Technical Paper
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Norio TESHIMA, Shingo YAMAMOTO, Qinghe ZHANG, Zen-Ichi YAMADA, Tadao S ...2007 Volume 56 Issue 2 Pages 99-106
Published: 2007
Released on J-STAGE: March 05, 2007
JOURNAL FREE ACCESSThe photocatalytic degradation of crystal violet (CV) was investigated with titanium dioxide particles (ST-01) or titanium dioxide supported on silica gel (hybrid-photocatalyst, HQC51). A CV solution was decolorized by each photocatalyst under UV irradiation. A hypsochromic shift from 590 nm to 562 nm occurred with increasing the UV irradiation time in the presence of a photocatalyst. The shift was probably caused by a stepwise release methyl groups from CV. Some photocatalytic degradation products by ST-01 were identified by using HPLC/MS and MS/MS techniques. It was proved that six methyl groups were stepwisely released from CV under photodegradation, and also dimethylamine was detected as a degradation product. In addition, ammonium ion and nitrate in sample solutions were also determined by flow injection analysis with an indophenol blue method and by using a nitrate ion selective electrode.
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Yoichi NAMIKI, Mamoru KOMATSU, Masahiro YONENO2007 Volume 56 Issue 2 Pages 107-110
Published: 2007
Released on J-STAGE: March 05, 2007
JOURNAL FREE ACCESSA new method to analyze conversion vs. depth (depth profile of conversion) in a thick-layer of UV curable resin non-destructively, using a laser micro-Raman spectrometer, has been investigated. A few methods exist to analyze the depth profiles of the curing state in a thick-layer of UV curable resins, but these methods are destructive. On one hand, laser micro-Raman spectrometry can be applied to non-destructive analysis inside a thick-layered film, but the polymerization of a sample by the irradiation of strong laser light was of concern, when it was applied to a measurement of the conversion of UV curable resin. Furthermore, if a long-wavelength laser is used in order to avoid polymerization of sample, Raman scattering at a deep part of the sample might be too weak to analyze the conversion. In this study, by confirming the influences of these issues, laser micro-Raman spectrometry was investigated as a depth-profiling method. We selected 780 nm as the long wavelength of the laser, and it was determined that the irradiation of a urethane methacrylic UV curable resin for 216 s did not promote polymerization of the sample. Then, a 1.86 mm thick cured sample of the UV curable resin was tested using the laser micro-Raman spectrometer through laser irradiation for 60 s. The Raman spectra at several depths in the cured sample were recorded. Because the spectrum of the deepest part was as clear as the others, it was determined that all of the spectra throughout the depth were acceptable to measurements of the conversions. From areas of the peaks on the spectra at 1635 cm-1 of C=C stretching vibration in the methacrylic group, the value of the conversion at each depth in the cured sample was calculated, and the depth profile was obtained. This study showed that laser micro-Raman spectrometry can be applied to the non-destructive analysis of the depth profile of conversion in a thick-layer of UV curable resins.
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Note
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Yuji SUZUKI2007 Volume 56 Issue 2 Pages 111-116
Published: 2007
Released on J-STAGE: March 05, 2007
JOURNAL FREE ACCESSDye-binding methods based on protein error for determining human serum albumin are classified into two methodologies via measurements of the absorbance increase under an acidic condition (absorbance increase method) and the absorbance decrease in a pH region near the neutral condition (absorbance decrease method). The color development of protein in the absorbance increase method is known to be affected by the pH, and the concentrations of dye, buffer and coexisting anions in the samples. However, the effect of coexisting anions on color development in the absorbance decrease method is unclear. In the present work, the effect of an inorganic salt on color development in the absorbance decrease method was investigated by a calculation based on the chemical equilibrium of the protein error and an experiment, and was compared with the results of the absorbance increase method. By adding an inorganic salt, the absorbance was decreased. The degree of its decrease was smaller in the absorbance decrease method than in the absorbance increase method, and differed according to the kind of inorganic salt. The experimental results agreed well with those obtained by a calculation.
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Analytical Report
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Ryoji SEKIOKA, Yasuo TAKAYAMA, Yasuo SETO, Yukio URASAKI, Hitoshi SHIN ...2007 Volume 56 Issue 2 Pages 117-124
Published: 2007
Released on J-STAGE: March 05, 2007
JOURNAL FREE ACCESSThe detection performance of a portable corona discharge ionization-type ion mobility spectrometer (LCD 3.2E, Smiths Detection) was investigated using nerve gases, blister agents, blood agents and related compounds. The vapors of sarin, soman and tabun were recognized as "G" after about several seconds of sampling; the detection limits were around 0.2 mg/m3. The vapors of mustard gas, lewisite 1, hydrogen cyanide and chloropicrin were recognized as "H" after several seconds of sampling, and the detection limits were around 10 mg/m3. The vapors of cyanogen chloride were also recognized as "H", but the detection limit was around 500 mg/m3. The vapors of trimethylphosphate, triethylphosphate, n-propanol, diethylamine, triethylamine, formaldehyde, and N,N-dimethylformamide were recognized as "G", and the vapors of 1,4-thioxane, 2-mercaptoethanol, diethylether and acetic acid were recognized as "H".
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