網版印刷電極在大學分析化學實驗課程的應用──電位滴定法測定氯離子與碘離子混合溶液

The Application of Screen-printed Electrode for Undergraduate Experimental Course of Analytical Chemistry--The Potentiometric Titration of Chloride and Iodide in a Mixture

蔡惠燕(Hwei-Yan Tsai) ； 傅冠儒(Bohr K. Fuh)

《化學》 68卷2期 (2010/06) Pp. 133-140

https://doi.org/10.6623/chem.2010014

摘要

本實驗利用拋棄式網版印刷電極(screen-printed electrode)，以銀膠修飾電極表面，形成工作電極。參考電極則取材日常生活隨手可得的材料，製成具多孔性可以聯通大燒杯溶液的管子，然後放入網版印刷碳電極，形成參考電極。希望透過簡單的實驗設計，讓學生可以實際操作，使學生更了解實驗的原理及引發學生對實驗設計的興趣。由學生實際自行製作電極進行鹵素離子混合物之滴定操作，結果顯示不論自製電極或商業電極，滴定曲線都可產生明顯的二次陡升，雖然兩組電極對銀離子之靈敏度不相同，但變化趨勢一致，經過數據微分處理可得到準確的當量點，因此自製電極組可取代商業電極組。若能將網版印刷電極廣泛的運用在學生實驗上，對於大學實驗課程中的實驗操作不僅具有實用的意義，同時也是一項符合經濟效益的分析工具。

關鍵字

電位滴定法 ； 網版印刷電極

並列摘要

The potentiometric titration of chloride and iodide in a mixture is a typical experiment for undergraduate analytical course. A commercial device integrating a silver electrode and a Ag/AgCl reference electrode is available for this experiment. A fritted disk is used as a salt bridge to connect the indicating and reference electrodes. The precipitates formed during the titration can block the fritted disk and cause slow and unstable response of potential change. In this study, a screen-printed carbon electrode (SPCE) was used as a reference electrode; a silver epoxy-coated SPCE was used as an indicating electrode. The cost of SPCE is much lower than that of commercial silver electrodes. There is no special handling needed for the storage of SPCEs and no blocking problems of salt bridge. The titration results from SPCEs show no significant difference compared with those from commercial silver electrodes. Students are interested to assemble the electrodes by themselves. These results reveal that the home-made reference electrode and silver epoxy-coated SPCE can be an alternative to the traditional silver electrode for potentiometric titration of halide ions.

並列關鍵字

Screen-printed electrode ； Potentiometric titration