Electrochemical determination of 4-nitrophenol using a single-wall carbon nanotube film-coated glassy carbon electrode

A single-wall carbon nanotubes (SWNT) film coated glassy carbon electrode (GCE) was fabricated for the direct determination of 4-nitrophenol (4-NP). The electrochemical behaviors of 4-NP at the SWNT-film coated GCE were examined. In 0.1 M phosphate buffer with a pH of 5.0, 4-NP yields a very sensitive and well-defined reduction peak at the SWNT-modified GCE. It is found that the SWNT film exhibits obvious electrocatalytic activity towards the reduction of 4-NP since it not only increases the reduction peak current but also lowers, the reduction overpotential. Based on this, an electrochemical method was proposed for the direct determination of 4-NP. The reduction peak current varies linearly with the concentration of 4-NP ranging from 1 x 10(-8) to 5 x 10(-6) M, and the detection limit is 2.5 x 10(-9) M after 3 min of open-circuit accumulation. The relative standard deviation at 2 x 10(-7) M 4-NP was about 6% (n = 10), suggesting excellent reproducibility. This new method was successfully employed to determine 4-NP in several lake water samples.