Sensitive and Simple Electrochemical Detection of Lead(II) with Carbon Ionic Liquid Electrode

In this paper a carbon ionic liquid electrode (CILE) was fabricated by using ionic liquid 1-ethyl-3-methylimidazolium ethylsulphate ([EMIM]EtOSO 3 ) as the modifier and further used as the working electrode for the sensitive anodic stripping voltammetric detection of Pb 2+ . The characteristics of the CILE were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In pH 4.5 NaAc-HAc buffer Pb 2+ was accumulated on the surface of CILE due to the extraction effect of IL and reduced at a negative potential (-1.20 V). Then the reduced Pb was oxidized by differential pulse anodic stripping voltammetry with an obvious stripping peak appeared at -0.67 V. Under the optimal conditions Pb 2+ could be detected in the concentration range from 1.0 x 10 -8 mol/L to 1.0 x 10 -6 mol/L with the linear regression equation as I p (μA) = -0.103 C (μmol/L) + 0.0376 (y = 0.999) and the detection limit as 3.0 x 10 -9 mol/L (3σ). Interferences from other metal ions were investigated and Cd 2+ could be simultaneously detected in the mixture solution. The proposed method was further applied to the trace levels of Pb 2+ detection in water samples with satisfactory results.