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| 1.
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論文
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山本, 敦 ; 松永, 明信 ; 関口, 久義 ; 早川, 和一 ; 宮崎, 元一
概要:
Photometric ion chromatography is a novel method by using the photometer as a detector. A feature of this method is the use of light absorbing ion in the mobil phase, and the appearance of transparent sample ion in the effluent is
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detected by "trough"in the base line absorbance. We applied this technique by using a conventional HPLC system equipped with a commercially available ion exchange separation column to the determination of bromate in such foodstuffs as bread and kamaboko. Sample solution was prepared by aqueous extraction and mixed with acetone for removal of proteins. After evaporation of the organic solvent, the aqueous solution was dechlorinated by a DOWEX column (Ag-form), and then was subjected to chromatography. Samples of bread and kamaboko were spiked with 5.4 ppm and 8.4 ppm of bromate, respectively, and examined by the above method. The average recoveries were 88.3% in bread and 82.9% in kamaboko, and the coefficients of variation were 7.7% and 7.9%, respectively. The detection limit was 1 ppm. The above findings indicate that bromate can be detected by HPLC using conventional instrumentation, and the sensitivity of this system is comparable to conductimetric detection.
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| 2.
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論文
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吉田, 育世 ; 早川, 和一 ; 宮崎, 元一
概要:
Simultaneous determination of carboxylic acids and inorganic anions was investigated by photometric ion chromatography w
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ith phthalate solution as an eluent. The retention time and the peak area of carboxylic acids changed remarkably with eluent pH. The optimum conditions at present were as follows : analytical column, OYOBUNKO ASA-4000 (4.6 mm i.d.×25 cm) ; eluent, 5×10-4 M disodium phthalate ; flow rate, 2 ml/min ; column temperature, 40°C ; detection wavelength, 240 nm ; injection volume, 100 μl. The detection limits for several carboxylic acids as 3 times noise were 0.05-0.07 mg/l in sample solution. Their calibration curves showed straight lines by the peak area method. The present method has an advantage to determine simultaneously not only carboxylic acids but also inorganic anions. Under the condition described above, both carboxylic acids and inorganic anions in several liquid foods were easily determined by direct injection of the sample prepared with only dilution.
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| 3.
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論文
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山本, 敦 ; 松永, 明信 ; 牧野, 正雄 ; 早川, 和一 ; 宮崎, 元一
概要:
A method for the simultaneous determination of organic acids was investigated by photometric ion chromatography by using
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two different eluents. A 4.6 mm i.d.×25 cm stainless column packed with MCI GEL SCA 01 (Mitsubishi Chemical Ind., Ltd.) was used as a separator column. Sample was injected into this column previously equilibrated with 1 mM citraconic acid at pH 6.8. After elution of monobasic organic acids, the eluent was exchanged to a stronger one, 1 mM m-sulfobenzoic acid at pH 6.8. Dibasic organic acids were eluted before the column reequilibration with the secondary eluent. On the other hand, tribasic organic acids such as citric acid were eluted with the secondary eluent. To prevent the base line disorder due to the eluent exchange, the determination at 254 nm was performed. Because this wave length is an isosbestic point of the two eluents. Sour-taste agents in soft drinks could be analysed directly after dilution of samples.
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