Determination of 4-aminophenylarsonic acid using a glassy carbon electrode modified with an ionic liquid and carbon nanohorns

We have developed a sensor for 4-aminophenylarsonic acid (4-APhAA) by coating a glassy carbon electrode (GCE) with a composite prepared from an ionic liquid and dahlia-like carbon nanohorns (CNHs). The good electric conductivity, large surface area and high pore volume of the CNHs, and the synergistic action of the ionic liquid (which is a good dispersant with excellent ion conductivity) result in efficient electrocatalysis towards oxidation of 4-APhAA. The effect was investigated by various electrochemical methods, and the electron transfer coefficient, diffusion coefficient, standard heterogeneous rate constant and thermodynamic activation energy were determined. The response range of 4-APhAA was evaluated using an i-t plot. If operated at a working voltage of 900 mV (vs Ag/AgCl), the sensor responds to 4-APhAA over the 0.5 mu M to 3.5 M concentration range.