Underpotential deposition-anodic stripping voltammetric detection of copper at gold nanoparticle-modified ultramicroelectrode arrays

The sensitive detection of copper (II) at gold nanoparticle-modified ultramicroelectrode arrays (UMEAs) is reported. Gold nanoparticles were electrode posited onto the UMEAs surface by applying a constant positive potential of 1.6 V for 20 min in a 20-nm gold nanoparticle solution. This process significantly increases the electrode area without losing the UMEAs analytical features. Underpotential deposition-anodic stripping voltammetry of copper (II) with such modified UMEAs was performed and showed a high increase in sensitivity (25.9 +/- 1.3 nC(.)mu M-1) and a broader linear range of response (0-10 mu M) compared with those values obtained using bare UMEAs (7.5 +/- 0.6 nC(.)mu M-1 and 0-2 mu M, respectively). The copper content of acid extracts of contaminated soils was successfully determined with the modified UMEAs and results are in good agreement with those obtained using the ICP-AES standard method. Overall, this work shows an alternative easy-to-use novel miniaturized device for the rapid and reliable determination of copper in soil samples whose application could be readily extended to other heavy metals of environmental interest.