Direct simultaneous determination of dihydroxybenzene isomers at C-nanotube-modified electrodes by derivative voltammetry

The voltammetric behavior of dihydroxybenzene isomers was studied with glassy carbon electrodes modified with multi-wall carbon nanotubes. In 0.1 mol L−1 HAc + NaAc buffer solution (pH 5.5), the modified electrode showed a good electrocatalytic response towards dihydroxybenzenes. The peak currents increased significantly and their oxidation potentials shifted negatively. Through a derivative technique, the three oxidation peaks of dihydroxybenzene isomers can be separated, thus the method can be applied to direct simultaneous determination without previous separation. The linear calibration ranges were 2 × 10−6-1 × 10−4 mol L−1 for hydroquinone and catechol, respectively, and 5 × 10−6 to 8 × 10−5 mol L−1 for resorcinol, with detection limits of 6 × 10−7, 6 × 10−7 and 1 × 10−6 mol L−1, respectively. This method has been applied to the direct determination of dihydroxybenzene isomers in artificial wastewater, and the recovery was from 92% to 104%.