Electrochemical Determination of Cu(II) Using a Glassy Carbon Electrode Modified with Multiwall Carbon Nanotubes Dispersed in Polyhistidine

We report the sensitive and selective quantification of Cu(II) at glassy carbon electrodes (GCE) modified with multiwall carbon nanotubes (MWCNT) dispersed in polyhistidine (Polyhis), (GCE/MWCNT-Polyhis) based on the complexation of Cu(II) by the histidine residues and further reduction by Differential Pulse Voltammetry in acetate buffer solution. The sensitivity was (3.6 +/- 0.3) x 10(6) mu AM(-1), the reproducibility 6.6%, and the detection limit 75 nM (4.8 mu gL(-1)). The quantification of Cu(II) was highly selective even in the presence of excess of Cd(II), Zn(II), Co(II), Fe(II), Fe(III), Al(III), Pb(II), Cr(III), Mn(II), and Ag(I). The proposed sensor was successfully used for quantifying Cu(II) in tap-water and groundwater samples without any pretreatment.