Simultaneous determination of 2-nitrophenol and 4-nitrophenol based on the multi-wall carbon nanotubes nafion-modified electrode

In this work, multi-wall carbon nanotubes (MWNT) were conveniently dispersed into Nafion-ethanol solution, and the MWNT-Nafion-modified glassy carbon electrode (GCE) was described for the simultaneous determination of 2-nitrophenol and 4-nitrophenol. At pH 4.0 phosphate buffer, the reduction peak currents of 2-nitrophenol (at -0.8 V) and 4-nitrophenol (at -1.0 V) increase significantly at the MWNT-Nafion-modified GCE, in comparison with that at the Nafion-modified GCE and the bare GCE. The experimental parameters, such as solution pH of phosphate buffer, accumulation potential and time, and the amounts of MWNT-Nafion onto the GCE surface, were optimized. The reduction peak currents are linear with the concentration of 2-nitrophenol from 5x10(-8) to 1x10(-5) mol L-1 and with that of 4-nitrophenol from 1x10(-7) to 1x10(-5) mol L-1. The detection limits after 3-min accumulation are 1x10(-8)moI L-1 for 2-nitrophenol and for 4x10(-8) mol L-1 for 4-nitrophenol. This modified electrode was applied to direct determination of 2-nitrophenol and 4-nitrophenol in lake water samples.