Electrochemical behavior of hydroquinone and catechol at glassy carbon electrode modified by electropolymerization of tetraruthenated oxovanadium porphyrin

Abstract

This work presents the simultaneous determination of catechol (CC) and hydroquinone (HQ), employing a modified glassy carbon electrode with tetraruthenated oxovanadium (IV) porphyrin. The GCE was modified by electropolymerization of {VOTPyP[RuCl3(dppb)]4} porphyrin, onto the GCE surface, by cyclic voltammetry. The modified electrode, labeled as VOTPRu-GCE, showed two pairs of well-defined redox peaks for the electrochemical processes of catechol and hydroquinone. In bare GCE, the potential difference (ΔEp) of CC and HQ were 469mV and 457mV, respectively, while with VOTPRu-GCE the potential difference decreased to 29mV and 30mV, indicating that the redox processes were reversible onto the VOTPRu-GCE surface. With differential pulse voltammetry, it was possible to simultaneously determine the CC and HQ, with peak-to-peak potential separation of 129mV, in 0.1mol L−1 acetate buffer (pH 4.75). Under the optimized conditions, the calibration curves were obtained in the linear concentration ranges of 2–38μmolL−1 for both isomers using the VOTPRu-GCE, which showed high sensitivity in the determination of CC and HQ, 12.73 and 15.91μAμmolL−1cm−2, respectively. The detection limits were 0.41 and 0.55μmolL−1 for CC and HQ, respectively.