Nanomaterials as a Tool for Increasing Sensitivity and Selectivity in the Analytical Chemistry of Tungsten by Stripping Voltammetry.

Tungsten is an extremely durable metal with a wide range of industrial applications and its toxicity is relatively low, although chronic exposure to its compounds can lead to adverse health effects. This paper proposes a method for the determination of trace amounts of tungsten using cathodic stripping voltammetry (CSV). A hybrid structure based on a mixture of multi-walled carbon nanotubes and spherical glassy carbon was used as the working electrode, on the surface of which a film of lead was formed during the measurement to increase the efficiency of the determination. A comprehensive optimization of the analytical parameters, including accumulation potential and time, signal recording conditions and electrolyte solution composition, was carried out to maximize sensitivity and improve the signal-to-noise ratio. The method developed achieved a detection limit for tungsten of 3 × 10-10 mol L-1, demonstrating its high sensitivity. The working electrode showed selectivity, signal reproducibility and resistance to the presence of potential interferences. The reliability and applicability of the proposed solution were confirmed by applying the method to the analysis of real environmental samples and certified reference materials, with satisfactory results. The presented analytical procedure represents a promising tool for the routine determination of tungsten in complex real matrices.