Electrochemical determination of cadmium ions in biological and environmental samples using a newly developed sensing platform made of nickel tungstate-doped multi-walled carbon nanotubes

Simple and rapid analysis of cadmium ion in environmental and biological samples is of great importance due to the severe toxicity caused by this heavy metal. In the present work, nickel tungstate (NiWO4) dispersion was mixed with multi-walled carbon nanotubes (MWCNTs) to obtain a homogenous composite of (NiWO4/MWCNTs) which was assigned as carbon paste electrode modifier. The composite was fully characterized using various characterization techniques including X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Thermo-Gravimetric Analysis (TGA) and Fourier Transform InfraRed (FTIR). The electrochemical redox reactions of cadmium (II) ions at the modified electrode interface were investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and linear sweep voltammetry (LSV). Effective parameters on the electro-analysis assay performance including the electrode composition, types of electrolyte, scan rate and pH were tested to achieve the best effective optimum conditions. Accordingly, a linear relation of cadmium ions was achieved in the concentration range 50-450 mu M with limit of detection of 0.12 mu M. Besides, the proposed electrode was successfully used to monitor trace amounts of cadmium ions in various real samples.

Automated summary

Nickel tungstate/multi-walled carbon nanotubes composite was successfully utilized as a carbon paste electrode modifier for the simple and rapid analysis of cadmium ion in environmental and biological samples. The composite was fully characterized and the optimal conditions for the electro-analysis assay were determined. A linear relation of cadmium ions in the concentration range of 50-450 μM was achieved.