Square-wave voltammetric determination of lead(II) with a Nafion ®/2,2-bipyridyl mercury film electrode

Abstract

A chemically modified electrode (CME) system consisting of a Nafion-coated mercury film electrode containing appropriate amounts of 2,2-bipyridyl for practical use in the analysis of lead(II) was investigated. The relative advantages of using square-wave stripping voltammetry (SWSV) in combination with the CME for the determination of the reversible lead(II)-2,2-bipyridyl complex was assessed. The main advantages of the CMe are better mechanical stability of the mercury film, and improved resistance to interference from both surface-active compounds and those metals which commonly interfere in anodic stripping measurements. For a 5-min preconcentration period in the presence of oxygen, a linear calibration curve from 1 to 100 μg l −1 was obtained, and the detection limit was 0.1 μg l −. A lower detection limit can be obtained when longer preconcentration times are used. The CME surface could be regenerated by exposure to acid. For 10 successive preconcentration/determination/renewal cycles, the SWSV response could be reproduced with 5% relative standard deviation. Rapid and convenient acid renewal allows the use of an individual modified electrode surface in continuous-monitoring environmental or clinical applications.