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論文
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山本, 敦 ; 早川, 和一 ; Yamamoto, Atsushi ; Hayakawa, Kazuichi
概要:
金沢大学理工研究域自然システム学系
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| 2.
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早川, 和一 ; 山本 , 敦 ; 宮崎, 元一 ; Hayakawa, Kazuichi ; Yamamoto, Atsushi ; Miyazaki, Motoichi
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| 3.
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Kaneko, Chikara ; Fujii, Harue ; Kawai, Shinji ; Yamamoto, Atsushi ; Hashiba, Kazuhiko ; Kimata, Toshihiko ; Hayashi, Reiko ; Somei, Masanori
概要:
A novel photochemical ring-contraction reaction of 5-unsubstituted 3, 1-benzoxazepines and their 5-halogeno or carboxyl
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derivatives to yield 3-formylindoles in an aprotic solvent is reported. This ring contraction was successfully extended to oxazepines having an alkoxycarbonyl function at the 5-position to give the indoles having this function at the 3-position. Though most of the oxazepines underwent the ring-contraction reaction only on irradiation at 254 nm, 5-carboxy derivatives or their esters afforded the ring-contraction products even at ≥ 300 nm. The intermediacy of 3H-indole species in these photochemical ring-contraction reactions was demonstrated by the isolation of methyl 3-acetyl-2-phenyl-3H-indole-3-carboxylate during the photolysis of methyl 4-methyl-2-phenyl-3, 1-benzoxazepine-5-carboxylate. It was found that this 3H-indole afforded methyl 6-and 4-acetyl-2-phenyl-indole-3-carboxylates upon further irradiation. The mechanism of this acetyl migration is discussed based on the result of the photochemical acetyl migration of methyl 1-acetyl-2-phenylindole-3-carboxylate.
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| 4.
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Yamamoto, Atsushi ; Hayakawa, Kazuichi ; Matsunaga, Akinobu ; Mizukami, Eiichi ; Miyazaki, Motoichi
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Yamamoto, Atsushi ; Matsunaga, Akinobu ; Mizukami, Eiichi ; Hayakawa, Kazuichi ; Miyazaki, Motoichi
概要:
A simultaneous determination method for five organic acids in vinegar has been established by photometric ion chromatogr
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aphy. Both trace components (lactic, gluconic, succinic and pyroglutamic acids) and the major component (acetic acid) in vinegar were separated on a TSK gel IC-Anion-PW column with 0.45 mM o-aminobenzenesulfonic acid aqueous solution as an eluent. Their elutions were detected as positive peaks before the system peak, and a negative peak after that by a UV monitor. The sensitivities of trace components were enhanced by adjusting their elutions close to the system peak. The lowest detection limits were 10μM lactic acid, 5μM gluconic and succinic acids and 3μM pyroglutamic acid, respectively. The only pretreatment necessary was dilution of vinegar 100-fold with the eluent. The results obtained by the proposed method were in good agreement with those by the enzymatic one.
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| 6.
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Nishimura, Masayuki ; Hayashi, Morimasa ; Yamamoto, Atsushi ; Hayakawa, Kazuichi ; Miyazaki, Motoichi
概要:
The effect of a mobile phase polyvalent counter ion on the retention behavior and peak intensity of sulfate in non- suppressed ion chromatography was quantitatively studied using a chromatogram simulation method. In this study,
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both indirect photometric detection (IPD) method and conductometric detection (CD) method were evaluated. With the IPD method, the retention of sulfate was observed to decrease in the presence of the polyvalent counter ion (Trien) without any change in peak intensity. With the CD method, however, peak intensity of sulfate decreased and, under some conditions, gave a negative peak in simulation as was also observed in actual experiments. The present work demonstrates the possibility of predicting the effect of a polyvalent counter ion on sulfate retention without resorting to physical experiments.
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| 7.
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Yamamoto, Atsushi ; Matsunaga, Akinobu ; Hayakawa, Kazuichi ; Mizukami, Eiichi ; Miyazaki, Motoichi
概要:
A photometric detector for an optically active compound is described in which two polarizers are set on both sides of the flow cell. When a nonchromophoric, optically active compound passes through the cell, the intensity of natural
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light transmitted through the polarizers and flow cell is changed. The detection of such a sample is possible photometrically. A large inclination angle between the polarizers increases the absorbance change and allows dextrorotatory and levorotatory to be differentiated. The direct HPLC/photometric detection of sugars is presented as an axample of this device.
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| 8.
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Hayakawa, Kazuichi ; Kato, Akio ; Yamamoto, Atsushi ; Miyazaki, Motoichi
概要:
In non-suppressed conductometric ion chromatography, when a carboxylic acid eluent of low pH is used, the signal intensi
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ty (ΔHc) is proportional to the sum of the conductivity change caused by changes in the sample concentration (ΔCs) as well as conductivity changes caused by changes in the eluent concentration (ΔCe). This can be expressed as ΔHC=B(ΔCs)+B(ΔCe), where B is a constant. In this equation, ΔCs is constant for any sample species. However, ΔCe varies with changes in the sample capacity factors. This value is positive when the sample elutes before the system peak (k′s<k′e), and is negative when it elutes after the system peak (k′s>k′e). Therefore, the sample peak intensity (ΔHC) is enhanced prior to the system peak and is suppressed after it. These effects increase the closer the sample and the system peaks. The effect of this theory was proved by a determination of orthophosphate using a TSK gel IC-Anion-PW column and a 0.75mM phthalic acid eluent. The detection limit of this method for orthophosphate (1×10-11mol, with an S/N of three) was smaller (by a factor of 10-30) than those by previous conventional ion chromatographic methods. Also, the interference of chloride or nitrate, often observed in the previous methods, was removed by suppressing their peak intensities. When this method was applied for the determination of orthophosphate in environmental samples, other interfering compounds were effectively removed by a column-switching system attached to the ion chromatograph, and a trace level of the orthophosphate was determined.
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| 9.
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Yamamoto, Atsushi ; Kawai, Mio ; Sakamoto, Mitsunori ; Kodama, Shuji ; Hayakawa, Kazuichi
概要:
A sensitive and variable-wavelength optical rotatory (OR) detector for high-performance liquid chromatography is present
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ed. This design is entirely different from that of conventional OR detectors consisting of a crossed polarizer pair. By placing a polarizing prism and a retardation plate into a commercial circular dichroism (CD) detector, the OR signal was obtained. The Mueller matrix approach was used to prove the principle of the OR signal appearance. Sugars and 4-androstene-3,17-dione were chosen as test compounds. The limit of detection was below 0.5 μg of injected sucrose at 260 nm, which was superior to that obtained with a conventional OR detector. For 4-androstene-3,17-dione, which is CD active, and shows a large anomalous OR dispersion curve, our detector gave a large OR signal with approximately half the intensity of the CD signal at 340 nm. 2008 © The Japan Society for Analytical Chemistry.
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