A voltammetric sensor based on graphene-modified electrode for simultaneous determination of catechol and hydroquinone

In this report, a voltammetric sensor for simultaneous determination of hydroquinone (HQ) and catechol (CC) was developed at a glassy carbon electrode modified with graphene (GR/GCE). The separation of oxidation and reduction peak (ΔE) is decreased from 281 to 31 mV for HQ and from 250 to 26 mV for CC at GR/GCE, respectively. Separation of the oxidation peak potentials for HQ and CC was about 112 mV in 0.10 M acetate buffer solution (pH 4.5), and the anodic currents for the oxidation of both HQ and CC are greatly increased at GR/GCE, which makes it suitable for simultaneous determination of these compounds. Under the optimized condition, the anodic peak current of HQ is linear with the concentration of HQ from 1 × 10^-6 to 5 × 10^-5 M in the presence of 5 × 10^-5 M CC. A detection limit of 1.5 × 10^-8 M (S/N = 3) can be achieved. At the same time, the anodic current of CC is linear with the concentration of CC from 1 × 10^-6 to 5 × 10^-5 M with a detection limit of 1.0 × 10^-8 M (S/N = 3) in the presence of 5 × 10^-5 M HQ. The proposed sensor was successfully applied to the simultaneous determination of HQ and CC in tap water, and the results are satisfactory.