L-アスコルビン酸オキシダーゼを用いた迅速電量分析法によるL-アスコルビン酸の定量

概要

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Determination of L-ascorbate in vitamin C tablets was carried out by the controlled potential coulometry using a porous carbon felt electrode and ferricyanide ion as a mediator. Each tablet was dissolved in 2000 ml of 5% metaphosphate aqueous solution and this sample solution was dropped with micropipet on the center of the carbon felt electrode containing electrolyte which was maintained in a controlled potential condition ( +0.5 V vs. counter electrode). The added L-ascorbate is readily diffused into the carbon felt and oxidized by ferricyanide ion. The produced ferrocyanide ion is electrooxidized completely in a three-dimensional porous carbon felt. The total coulombs flowed in the electrode reaction was measured by a coulometer. Next, L-ascorbate oxidase (EC.1.l0.3.3) was added to 1 ml of the sample solution and L-ascorbate was converted to dehydroascorbate completely. The coulombs flowed by the solution added enzyme was also measured by dropping this solution on the carbon felt electrode. The concentration of L-ascorbate in vitamin C tablet was calculated from the difference of the coulombs obtained between the sample solution and the same solution added enzyme. The determination time for each sample was about 2 min and the coulometric results obtained by the present method was in fairly good agreement with those obtained by spectrophotometry.
社団法人日本分析化学会の論文
1989-06-05