Electrochemical sensor for trace silicic acid detection based on bismuth film electrode

A highly sensitive voltammetric detection of silicic acid (SA), the main chemical species of dissolved silica in sea water, is described. The protocol relies on a fast square-wave voltammetric measurement of the decreased molybdenum stripping signal due to the formation of silicomolybdate complex. The cathodic stripping experiments were performed at the bismuth film electrode using HCl–KCl (pH 1.6) buffer solution. Different ligands, pH, ligand concentration, deposition potential and accumulation time were evaluated. Under the optimal conditions, a linear response is observed over the 50–400 μg L⁻¹ SA concentration range with a detection limit of 2 μg L⁻¹. A highly stable response, with a relative standard deviation (RSD) of 4.8%, is observed for 10 repetitive measurements. Such an electrochemical approach offers great promise for a simple, rapid, sensitive, and on-site or in situ real-time detection of SA.