Anodic Stripping Voltammetry of Nickel Ion Using a Rotating Plastic Formed Carbon Electrode

Abstract

A quantitative analysis of Ni(II) by anodic stripping voltammetry (ASV) was investigated using a three electrode system with a plastic formed carbon (PFC) electrode as a working electrode. When ASV was performed with 10 μmol L⁻¹ Ni(II) aqueous solution containing 0.01 mol L⁻¹ NaSCN and 0.1 mol L⁻¹ KCl while rotating the PFC electrode at 2500 rpm, the positive peak current (I_p) was obtained at around –0.25 V due to the re-oxidation of Ni electrodeposited at the surface of PFC electrode. The I_p was proportional to the Ni(II) concentration in the range between 0.5 and 10 μmol L⁻¹, and the limit of quantitation of Ni(II) was found to 1.7 μmol L⁻¹. When 1 μmol L⁻¹ Bi(III) was added to the 0.1 mol L⁻¹ KCl aqueous solution instead of NaSCN and ASV was performed in the same manner, the I_p increased ca. 2-fold. The optimum condition for ASV of Ni(II) in 0.1 mol L⁻¹ KCl aqueous solution containing 1 μmol L⁻¹ Bi(III) was found to be the applied potential for the electrodeposition of Ni(II) of –1.6 V, the accumulation time of 900 s, the rotation rate of 2500 rpm, and the scan rate of 200 mV s⁻¹, respectively. The I_p obtained by three repeated measurements under the optimum condition was proportional to the Ni(II) concentration in the range between 10 and 100 nmol L⁻¹, and the correlation coefficient of the plot of I_p and Ni(II) concentration was R² = 0.9922. The limit of quantitation of Ni(II) was found to 26 nmol L⁻¹, which improved 65 time by adding Bi(III) compared with the addition of NaSCN. We have also clarified the conditions under which Ni(II) can be determined 10 times more sensitively than the water quality standard for drinking water.