Analysis of trace nickel by square wave stripping voltammetry using chloropalladium(II) complex-modified MWCNTs paste electrode

Abstract

The application of multiwalled carbon nanotubes (MWCNTs) paste electrode modified with chloropalladium(II) complex in the analysis of trace nickel is presented in this work. The chloropalladium(II) complex was characterized by fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and transmission electron microscope (TEM). Several operational parameters influencing the electroanalytical response of the modified electrode were optimized, such as the different composition of modifier, pH of the solution, accumulation potential, and accumulation time. At optimal condition a linear plot for nickel concentration between 10nM to 1.0μM with a limit of detection 7.4nM were obtained. The relative standard deviation for the 1.0μM of Ni(II) was 4.0% (n=5). This study shows that with the exception of Co2+, excess concentration (in 10 and 100-fold concentration) of other metal ions such as Zn2+, Cu2+, Cd2+, Mg2+, Ca2+, Ce3+, and Ba2+ did not influence the nickel response. The viability of the proposed electrodes for the determination of nickel in vegetables and different water samples was evaluated. Results were compared with those from inductively coupled plasma-optical emission spectrometry (ICP-OES).