Zeolite/Polymer-Modification of a Mercury Electrode. Effects on the Cu2+ Interference in the Stripping Determination of Zn2

• Published in: Electroanalysis (New York, N.Y.) Vol. 10; no. 18; pp. 1285 - 1287
• Main Authors: Mogensen, Lene, Kryger, Lars
• Format: Journal Article
• Language: English
• Published: Weinheim VCH Verlagsgesellschaft mbH 01.12.1998
• Subjects: Cu2; Interference; Mercury electrode; Stripping; Zeolite modification; Zn2
• ISSN: 1040-0397; 1521-4109
• DOI: 10.1002/(SICI)1521-4109(199812)10:18<1285::AID-ELAN1285>3.0.CO;2-V

The present study was carried out in order to investigate whether zeolite 13X (aperture 7.4 A˚) modification of a mercury electrode could provide discrimination against the interference from Cu2+ in the stripping determination of Zn2+ (utilizing the zeolite ion exchange capability, and the possibility for small differences in size and shape of hydrated Zn2+ and Cu2+ and hence the differences in zeolite affinity to these species). For this purpose a chemically modified electrode (CME) was constructed from a glassy carbon electrode, which was first coated with a zeolite 10X containing polymer matrix then subjected to mercury plating. The analytical characteristics of the CME were subsequently compared with those of a conventional thin mercury film electrode (TMFE). The comparison, which was based on analogous stripping experiments carried out using first the TMFE, then the CME, showed that stripping signals for Zn2+ as well as Cu2+ were obtained with both electrodes. However, the intermetallic compound interference observed for the CME Zn‐response was much less pronounced than that encountered for the TMFE Zn‐response, thus indicating that the zeolite modification provided a marked discrimination towards deposition of Cu2+. Subsequent standard addition experiments with 60 s depositions at −1200 mV revealed that the Zn‐stripping signal obtained with the CME was linear for 0–3.5 μM Zn2+ in the presence of 10 μM Cu2+.