A nanocarbon paste electrode modified with nitrogen-doped graphene for square wave anodic stripping voltammetric determination of trace lead and cadmium

A nano-carbon paste electrode was modified with nitrogen doped graphene and applied to square wave anodic stripping voltammetric determination of lead(II) and cadmium(II). The modified electrode was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Key parameters affecting the performance of the sensor such as pH value, content of modifier, deposition potential and time were optimized. Under optimized conditions, the electrode exhibits linear response to lead (at about −0.56 V) and cadmium (at about −0.77 V) in the range between 10 pM to 1 nM, and the detection limits are 8.0 pM for cadmium(II) and 5.0 pM for lead(II), respectively. The sensitivity, selectivity and simplicity of the method are comparable to, or even better than those reported earlier.