Potentiometric Determination of Zinc in Supplement Tablets Using a Ca-Ion Selective Electrode
Potentiometric Determination of Zinc in Supplement Tablets Using a Ca-Ion Selective Electrode
复制标题
使用钙离子选择电极电位法测定补充剂片剂中的锌
DOI：
10.1021/acs.jchemed.2c00154
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发表时间：
2022
影响因子：
3
通讯作者：
Laskin, Julia
中科院分区：
文献类型：
--
作者：
Samayoa-Oviedo, Hugo Y.;Halpern, Emily;Mehnert, Samantha A.;Laskin, Julia
本实验室实验介绍了使用钙离子选择电极（Ca-ISE）来测定补充剂片中锌的浓度。开发这种方法是为了向学生展示如何扩大Ca-ISE的应用范围，以确定Ca2+以外的金属离子。为了测定Zn2+的浓度，学生将样品溶解在Ca-EDTA缓冲溶液中，并使用EDTA作为滴定剂。我们与学生讨论了固定pH值和离子强度对准确分析定量的重要性。学生们还使用比色滴定法，用murexide作为指示剂来测定Zn2+的浓度。他们使用统计工具来证实这两种方法提供了相似的结果。学生们得出结论，与制造商报告的已知值相比，两种滴定法都高估了片剂中锌的含量3-5%，并讨论了影响Zn2+测定准确性的因素。
The laboratory experiment presented here describes the use of a calcium ion-selective electrode (Ca-ISE) to determine the concentration of zinc in a supplement tablet. This approach was developed to show students how to expand the range of applications of Ca-ISE to enable the determination of metal ions other than Ca2+. To determine the concentration of Zn2+, students dissolved the sample in a Ca-EDTA buffer solution and used EDTA as titrant. We discuss with students the importance of a fixed pH and ionic strength for the accurate analytical quantification. Students also used colorimetric titration of the same sample with murexide as an indicator to determine the concentration of Zn2+. They used statistical tools to confirm that the two approaches provide similar results. Students concluded that both titrations overestimate the amount of zinc in a tablet by 3–5% in comparison with the known value reported by the manufacturer and discussed factors that affect the accuracy of Zn2+determination.