Construction of a Carbon Paste Electrode Based on Novel Thiolated Ligand Capped Gold Nanoparticles for Determination of Trace Amounts of Mercury(II)

In the present study, a simple electrochemical sensor for trace determination of Hg(II) ions in aqueous solutions was introduced. The proposed sensor was designed by incorporation of the 4-methyl-piperidine-carbodithioate capped gold nanoparticles (GNPs) into the carbon paste electrode (CPE), which provides a remarkably improved sensitivity for stripping voltammetric determination of Hg(II). Differential pulse voltammetry (DPV) was applied for quantitative determinations. The resulting electrode exhibited a linear relationship towards Hg(II) concentrations ranging from 0.4 to 100.0 μg L-1. The detction limit was found to be 0.2 μg L-1 (S/N = 3) that is lower than the permitted value of Hg(II) reported by the Environmental Protection Agency (EPA) limit for drinkable water. The relative standard deviation (RSD) for 7 successive measurements at different electrodes was also found to be 3.8%. The interference studies showed that the several common metal ions did not interfere with the quantitative mercury determination. The designed sensor was further utilized for the determination of mercury ions in real water samples with satisfactory results.