Polyviologen modified glassy carbon electrode employed for anodic stripping voltammetric determination of mercury(II)

In this study, a polyviologen modified glassy carbon electrode (PVGCE) was used to detect Hg(II) in aqueous solutions containing significant amounts of chloride anions in order to demonstrate the electroanalytical application of the electropolymerized polyviologen. The polyviologen thin film was formed on the electrode surface by applying a constant potertial of - 1.0 V in the pH 4.2 Britton - Robinson (BR) buffer solution that contains 0.1 wt% of viologen oligomers. The PVGCE was found capability to improve the detection limit of Hg(II) in the solutions with high concentration of chloride because Hg(II) forms negative complex ions HgCl42- that can be accumulated to PVGCE by the anion-exchange characteristic of polyviologen. With 5 minutes accumulation at - 0.2 V, the adsorbed HgCl24- anions were reduced to Hg and deposited on the electrode surface, and were determined with the following anodic stripping differential pulse voltammetry (ASDPV). The dependence of anodic stripping current versus concentration was linear from 1 ppb (5 nM) to 100 ppb (0.5 mu M) with a regression coefficient of 0.9959.