Electrochemical Impedance Spectroscopy Study of the Response Mechanism of the Jalpaite CuII Ion-Selective Electrode in Seawater
详细信息 查看全文
- 作者：Roland De Marco ; Ruth Eriksen ; and Alberto Zirino
- 刊名：Analytical Chemistry
- 出版年：1998
- 出版时间：November 15, 1998
- 年：1998
- 卷：70
- 期：22
- 页码：4683 - 4689
- 全文大小：175K
- 年卷期：v.70,no.22(November 15, 1998)
- ISSN：1520-6882
文摘
This paper presents the results of a novel study into theresponse mechanism of the jalpaite copper(II) ion-selective electrode (ISE) using electrochemical impedancespectroscopy (EIS) under conditions of minimal overpotential stimulation (i.e., ±10 mV). The EIS spectra of thejalpaite ISE in seawater and other ionic media revealed ahigh-frequency surface film impedance that is attributableto the modified hydrated surface layers of the ISE, and alow-frequency charge-transfer impedance that can beascribed to the reductive ion-exchange of CuII at themembrane/electrolyte interface. EIS data for a rotatingdisk electrode have shown that the charge-transfer process is under diffusion control. EIS and potentiometricresponse data in UV-oxidized seawater spiked with humicacid imply that organic complexation of CuI at the electrode diffusion layer is responsible for a weak interferenceeffect. The classical chloride interference effect of thejalpaite CuII ISE occurring at high concentrations of CuII(i.e., >10-6 M) yields an EIS response similar to the oneobserved with organic ligands. An EIS experiment for ajalpaite CuII ISE aged in seawater for 72 h demonstratedthat the charge-transfer impedance is constant untilelectrode release of CuII exceeds the complexing capacityof seawater, and this mechanistic information is consistentwith the hypothesis that electrode dissolution can be usedto autotitrate the natural ligands in seawater.