Simultaneous electrochemical determination of dihydroxybenzene isomers based on the hydrophilic carbon nanoparticles and ferrocene-derivative mediator dual sensitized graphene composite

A dual sensitized graphene composite decorated with carbon nanoparticles (CNP) and a new ferrocene-derivative redox mediator, (4-ferrocenylethyne) phenylamine (FEPA), is prepared by a facile and rapid one-step method. The as-prepared (4-ferrocenylethyne) phenylamine-carbon nanoparticles-graphene (FEPA-CNP-GR) composite coupling with Nafion was used to construct an ultrasensitive electrochemical sensor (Nafion-FEPA-CNP-GR) for simultaneous detection of dihydroxybenzene isomers. It was found that the well-dispersed hydrophilic-type CNP in the composite could improve the water-solubility and the surface area of GR, and exhibit an excellent catalytic activity toward resorcinol (RC) oxidation. Meanwhile, synthesized FEPA served as a good electron-transfer mediator, improved the sensitivity of the sensor, permitted favorable oxidation peak separations between isomers, and reduced the interferences between isomers. FEPA steadily adsorbed on the surface of GR through the π-stacking interaction between the conjugate chain of FEPA and GR, which effectively prevented FEPA mediator leaking from electrode surface. In addition, Nafion used as an immobilization film for eliminate the main interferences in relatively high concentrations, which led to an excellent selectivity. Thus, the proposed method exhibited good stability, sensitivity and selectivity for the simultaneous determination of dihydroxybenzene isomers due to the synergistic effect of CNP, FEPA and GR. Under the optimum conditions, the calibration curves for hydroquinone (HQ), catechol (CC), and RC were obtained in the range of 0.3-90 μmol L−1, 0.6-100 μmol L−1 and 4-300 μmol L−1, respectively. The detection limits were found to be 0.1 μmol L−1 for HQ, 0.2 μmol L−1 for CC and 0.7 μmol L−1 for RC based on S/N of 3. The developed method was successfully applied to the simultaneous determination of dihydroxybenzene isomers in synthetic and real samples, and the results are satisfactory.