Munehiko Mizobuchi

High-performance liquid chromatographic analysis of ammonium in human urine

A method for the quantitative determination of ammonium in human urine by high-performance liquid chromatography (HPLC) is described. After making fluorescent substances with fluorescamine, they were separated and quantified by their fluorometric intensity. The intensity (as measured by peak height) was linear between 0.5 and 5.0 micrograms, and coefficients of variation for elution time and peak height on replicate analysis of the standard were 0.15 and 4.2%, respectively. Recoveries of added ammonium were 96.5 and 97.3%, respectively, on 2.0 and 3.0 micrograms by this method. Detection limit of this method was 0.2 microgram. There was good agreement between the proposed HPLC method (X) and ion chromatographic method (Y), giving the relationships as Y = 0.956X + 0.012, r = 0.991.

Determination of chromate ion by ion chromatography with UV-detector in an alkaline solution.

産業廃棄物に含まれる六価クロムを,イオンクロマトグラフィー(IC)によりアルカリ性条件下で定量する方法を確立した.分離カラムとして陰イオン交換カラム(Dionex製HPIC AG-4A)を,溶離液として炭酸塩-炭酸水素塩溶液を用いたところ,他のイオン種の妨害もなく定量することができた.なお,六価クロムの検出・定量にはUV検出器を用いて波長370nmの吸光度を測定した.定量下限値は0.3mg/l,回収率は0.5,5.0,10.0mg/lの添加でそれぞれ104%,98.4%98.3%であった.実試料に適用したところ,JIS法では試料液を硫酸酸性にする操作でクロムが還元されて検出できなかったが,本法では0.4mg/lの六価クロムを検出することができた.

Ion exchange characteristics of commercial guard columns for ion chromatography and their application to determination of sulfate ion in mineral spring water as preconcentration columns.

3種類のプレカラム(Dionex製HPIC-AG3,HPIC-AG4,HPIC-AG5)についてフッ化物イオン,塩化物イオン,亜硝酸イオン,硝酸イオン,リン酸イオン,硫酸イオンの6種類の陰イオンに関するカラムのイオン交換特性を求めた.同じカラムでも陰イオンの種類により交換容量も異なった.標準混合陰イオン溶液をカラムに通すとフッ化物イオンや塩化物イオンはほとんどカラムに捕集されないのに対し,リン酸イオンや硫酸イオンはカラムに捕集された.又,HPIC-AG5では塩化物イオンが約2mg共存していても定量的に硫酸イオンを捕集することができた.そこでイオンクロマトグラフィーによる鉱泉水中の微量の硫酸イオンの定量における前濃縮に本プレカラムを応用した.

Composition of fatty acids and their characteristics in oil of instant Chinese noodles.

Twenty-two kinds of oil samples extracted from instant Chinese noodles were analyzed on their composition of fatty acid methyl esters by GC. Four main fatty acids in the oil were 18 : 1, 16 : 0, 18 : 2, and 18 : 0, and another trace ones detected were 14 : 0, 16 : 1, 17 : 0, 17 : 1, 18 : 3+20 : 0, 20 : 1, and 20 : 2. Constraction values of these four main fatty acids were used to evaluate and to calculate the difference among the six producing companies by a personal computer with the analytical method of principal component analysis. Samples were divided into three groups. The constraction values of company B was similar to that of the palm oil and another ones of companies A and E were also similar to that of the mixed oil with the ratio of 25 to 75 on the palm oil and lard.