Multiwalled carbon nanotube modified with 1-(2-pyridylazo)-2-naphthol for stripping voltammetric determination of Pb(II).

The present work is focused on the modification of multiwalled carbon nanotubes with a ligand, 1-(2-pyridylazo)-2-naphthol (PAN), and its potential application for the development of a new, simple and selective modified glassy carbon electrode for stripping voltammetric determination of Pb(II). The electrochemical method is based on closed circuit accumulation of lead ions onto a PAN-modified multiwalled carbon nanotube electrode from 0.1 mol L(-1) oxalate buffer solution (pH = 3.0) during 150 s at the potential of -0.9 V, following by differential pulse anodic stripping voltammetric determination in the range -0.9 to -0.35 V. The analytical curve for Pb(II) ions covers a linear range varying from 0.8 up to 220.4 microg L(-1). The limit of detection was found to be 0.1 microg L(-1), while the relative standard deviation (RSD) at 50.0 microg L(-1) was 1.8% (n = 5). Many of the coexisting ions had little or no effect on the determination of lead(II). The results suggest that the proposed method can be applied as a simple and efficient alternative technique for the determination of lead ions which has good accuracy in real samples such as natural waters and standard alloys. In addition, this method demonstrates the powerful application of carbon nanotubes in the field of mercury-free electrodes in voltammetric stripping analysis.