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    库仑滴定法间接测定补锌片中锌

    Indirect Determination of Zinc in Zinc Supplementation Tablets by Coulometric Titration

    • 摘要: 以pH 9.2的1.0 mol·L-1碘化钾-四硼酸钠溶液为支持电解质溶液,铂电极作为电解电极与指示电极,于室温下电解生成碘10 s后加入补锌片样品溶液滴定剩余的半胱氨酸,采用库仑滴定法指示滴定终点,根据法拉第电解定律,间接测定样品溶液中锌含量。锌的质量浓度在0.05~0.50 g·L-1内与其消耗的电量呈线性关系,检出限(3s)为0.04 mg·L-1。方法用于补锌片样品的分析,测定值的相对标准偏差(n=6)为0.76%~0.92%,测定值与标示量不存在显著性差异。

       

      Abstract: 1.0 mol·L-1 potassium iodide-sodium tetraborate solution (pH 9.2) was used as supporting electrolyte solution, and platinum electrodes were used as electrolysis electrode and indicating electrode. After 10 s of iodine formation by electrolysis in room temperature, the sample solution of zinc supplementation tablet was added to titrate residual cysteine. Endpoint of titration was indicated by coulometric titration. Zinc in the sample solution was indirectly determined according to Faraday's law of electrolysis. Linear relationship between values of quantity of electricity of consumption and mass concentration of zinc was obtained in the range of 0.05-0.50 g·L-1, with detection limit (3s) of 0.04 mg·L-1. The proposed method was applied to the analysis of the samples of zinc supplementation tablets, giving values of RSDs (n=6) of determined values in the ranges of 0.76%-0.92%. There was no significant difference between the determined value and the labeled amount.

       

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