Kusuo Narita

Ion exchange chromatography of aluminum using 3-carboxy-2-naphthylamine-N,N-diacetic acid as a fluorescent post-column chelating reagent.

Ion exchange chromatography of aluminum ion using 3-carboxy-2-naphthylamine-N,N-diacetic acid (CNDA) as a fluorescent post-column chelating reagent was studied. The solution containing ammonium chloride and hydrochloric acid was used for the eluent, and acetate buffer solution containing CNDA was used for the post column chelating reagent. The peak of aluminum was separated from that of calcium, magnesium and zinc, and the chromatogram was not affected by copper(II) and iron(III). The calibration curve gave linear plots with a range of 0.0027-0.54 ppm aluminum, the regression coefficient of correlation (r2) was 1.000, and the detection limit (S/N = 3) was 0.3 ppb, indicating that the method could determine aluminum with high sensitivity. It was demonstrated that CNDA is a useful metallofluorescent reagent for aluminum. This method has been successfully applied to the determination of aluminum in some tea drinks.

Observation of the melting process for ethyl p-aminobenzoate doped with eutectic mixture

Abstract In order to improve the reliability of purity measurements by differential scanning calorimetry (DSC), the melting process of a test material was studied using a system of ethyl p -aminobenzoate and n -butyl p -hydroxybenzoate. The eutectic mixture began melting accompanying the increase in temperature. After the minor component, p -hydroxybenzoate, had entirely melted in the eutectic mixture, it was confirmed by DSC measurement and solid phase-liquid phase titration that the major component, p -aminobenzoate, which remained as a solid, continued to dissolve into the eutectic mixture. In order to completely grasp the melting image of the test material, it was necessary to measure it from a sufficiently low temperature, and work up to the eutectic peak with the minor component. It was found that, by drawing up a solubility curve, the phenomenon in which p -aminobenzoate dissolves into the melted eutectic mixture is, in this system, close to the ideal solution based on Raoults equation, and that the heat of mixing in an infinite dilution was indicated to be a small value of −1.9 J g −1 . For that reason, the heat of fusion and the heat of dissolution coincided within the allowable error. Test materials that have been refined to a certain degree frequently include similar compounds as impurities, and this establishes an approximation of the heat of dissolution with the heat of fusion.

Rapid and simple determination of mercury in traditional Chinese medicines by amalgamgravimetry.

水銀の分析法は環境汚染物質を対象とするものに重点がおかれ,医薬品中の水銀を精度よく定量することは困難である.試料を熱分解し,生じた水銀蒸気をアマルガムとして捕集する重量法は,操作が簡単で水銀を含む廃棄物も少なく,信頼性の高い方法である.この報告では,中薬約10mgを試料とし酸化剤と妨害元素除去剤を充てんした燃焼管により燃焼し,銀を充てんした吸収管に水銀をアマルガムとして捕集する重量法について検討を行った.本法は1回の燃焼時間は25分であり,±0.2%以下の誤差(2σ)で定量することができた.又,水銀を吸収した銀粒は金属の水銀と同様の廃棄物処理法により処理することができた.

Precise and accurate determination of halogens in organic compounds using an amalgamated gold electrode

Abstract Precise and accurate titration of halogens in organic and inorganic materials has been studied. The halogen was titrated with coulometrically generated silver and determined potentiometrically by using an amalgamated gold indicator electrode. An argentometric titration curve using the amalgamated gold indicator electrode showed a large jump in potential at the endpoint as well as in mercurometric determination. Sodium carboxymethyl cellulose (CMC) and aluminum nitrate were added as they are most effective for clarifying the sample solution and eliminating adsorption of the halide ion on the silver halide generated. The electrolytes used were 0.5 M nitric acid containing 0.1% CMC and 0.2 M aluminum nitrate. Approximately 0.2 mmol of chloride, bromide, and iodide ions were titrated with high precision and accuracy. Their standard deviations were 0.03, 0.02, and 0.02%, respectively, with no apparent systematic error. The precise determination of halogens, employing oxygen flask combustion and dissolution of the halide salts in the electrolyte, was carried out with ±0.1% absolute error using samples weighing between 20 and 30 mg.

Desiccation of analytical materials.

分析の前処理として試料の乾燥を行うことは,正確な分析結果を得るため最初に必要な操作である.より確実な乾燥を行うために乾燥の過程を検討し,24種類の乾燥剤についてその性能を比較した.又有機元素分析用標準試料50種類について吸湿実験を行い,吸湿性のない物質でも長時間室内に放置すると水分を吸着して分析値の偏りを生じることを確認した.実験の結果より,試料を乾燥保存するためには酸化バリウムなどの入ったデシケーターを用いて70℃又は試料の性質に応じてできるだけ高い温度に加熱して1夜以上減圧乾燥し,小型の乾燥容器に保存することが必要であった.