製藥中維生素C之差異電解質電位滴定法   全文下載

Differential Electrolytic Potentiometric Titration of Vitamin C in Pharmaceutical Preparations

直流差異電解質電位原理應用在維生素c之水溶性滴定已被研究。鈰（IV）與維生素c之反應快速足以使後者在0.09 M硫酸介質中直接滴定。硫酸鈰銨作為滴定用標準液，一組白金電極作為指示系統。所得到之滴定曲線幾乎對稱且有銳利之波峰。最適之電流密度為0.65 μA cm-2。此程序已成功地應用在商業化錠劑、膠囊以及果汁中0.02~10 ppm維生素c之檢測。這項研究結果與官方檢測方法相比是令人滿意的。

The application of direct current differential electrolytic potentiometry for the aqueous titration of vitamin C has been investigated. The reaction of vitamin C with C e (IV) is fast enough to permit its direct titration in 0.09 M sulfuric acid media. C erium ammonium sulfate was used as a titrant and a couple of platinum electrodes as an indicating system. Titration curve shapes obtained are almost symmetrical with sharp peaks. The optimum current density was found to be 0.65 μA cm-2. The procedure was applied successfully to the determination of vitamin C in commercial tablets, capsules as well as in juice in the concentrations of 0.02~10 ppm. The results of this study were favorably compared statistically with those obtained with official methods.