Simultaneous determination of cadmium(II), lead(II) and copper(II) by using a screen-printed electrode modified with mercury nano-droplets

We are presenting a strategy for the fabrication of disposable screen-printed electrodes modified with mercury nano-droplets and capable of sensing heavy metal ions. They were prepared by coating electrodes with a mixture of multi-walled carbon nanotubes and chitosan, this followed by adsorption of mercury. The resulting sensor was characterized by cyclic voltammetry and impedance spectroscopy. Also the effects caused by adsorption of mercury were investigated. It is shown that square wave anodic stripping voltammetry enables simultaneous determination of cadmium(II), lead(II) and copper(II), for which detection limits of 12, 23 and 20 nM, respectively, are found. Relative standard deviations for ten determinations at 0.6 μM concentrations of these ions are in the range of 3.0 to 5.7%. The applicability was tested by analyzing river water and showed recoveries between 94.1 and 104.6%, thus demonstrating its utility for in-field monitoring of these heavy metal ions.