Stripping voltammetric determination of mercury(II) and lead(II) using screen-printed electrodes modified with gold films, and metal ion preconcentration with thiol-modified magnetic particles

A novel approach to the electrochemical determination of heavy metals in tap water using anodic stripping voltammetry was developed using screen-printed electrodes modified with gold films. After optimisation of the experimental conditions, the screen-printed electrodes modified with gold films displayed excellent linear behaviour in the examined concentration range from 2 to 16 A mu g L-1 mercury and lead in 50 mM HCl with a detection limit of 1.5 A mu g L-1 and 0.5 A mu g L-1 for mercury and lead, respectively. In order to decrease the working range down to less than 1 A mu g L-1, a preconcentration step based on the use of magnetic particles modified with thiols was introduced into the protocol. Applying optimum binding conditions, the assay using screen-printed electrodes modified with gold films displayed excellent linear behaviour in the concentration range 0.1 to 0.8 A mu g L-1 in 50 mM HCl. The detection limit after a 120 s deposition time for mercury and lead were 0.08 A mu g L-1 and 0.02 A mu g L-1, respectively. The method has been applied to the determination of mercury and lead traces in tap water.