Sensitive Voltammetric Determination of Cadmium(II) with 8-Hydroxyquinoline and Ionic Liquid Modified Carbon Paste Electrode

In this paper, 8-hydroxyquinoline (HQ) and ionic liquid (IL) modified carbon paste electrode was fabricated and used for the sensitive determination of cadmium(II) with differential pulse anodic stripping voltammetry (DPASV). The modified electrode was prepared by the addition of HQ and IL 1-ethyl-3-methylimidazoliam ethylsulphate as the modifiers into the traditional carbon paste mixture. Cd(II) was preconcentrated and reduced on the surface of the modified electrode at the potential of -1.0 V (vs. SCE) by the co-contributions from the formation of HQ-Cd(II) complex and the accumulation effect of IL. Then the reduced Cd on the electrode surface was reoxidized by DPASV with a sensitive oxidation peak appeared at -0.79 V (vs. SCE). Under the optimal conditions, the oxidation peak current was proportional to the Cd(II) concentration in the range from 0.03 to 2.0 mu mol/L with the detection limit as 5.0 nmol/L (3 sigma). The proposed method was successfully applied to the water samples detection with the recovery in the range from 95.6% to 96.6%.