Synergetic accumulation and simultaneous determination of naphthol isomers on electrochemically reduced graphene oxide modified electrode

A novel method was developed for the synergetic accumulation and simultaneous determination of naphthol isomers (α-N and β-N) at electrochemically reduced graphene oxide modified glassy carbon electrode (E-rGO/GCE). One-step electrochemical reduction was employed for the fabrication of E-rGO/GCE, then the modified material was characterized by scanning electron microscope, Raman spectroscopy and Fourier transform infrared spectroscopy. Electrochemical behavior of naphthol isomers at E-rGO/GCE shows that the sensitivity of the isomers could be increased due to the synergistic effect of π–π conjugating and electrochemical accumulation. The oxidation peaks of α- and β-naphthol could be completely separated and the isomers were simultaneously detected with the linear ranges of 5–400   nM and 0.5–20   μM for α-N, 5–350   nM and 0.5–20   μM for β-N. The detection limits of α-N and β-N were 1.01   nM and 0.43   nM (S/N   =   3), and the corresponding sensitivity were 0.0097   μA/μM and 0.0113   μA/μM, respectively. More importantly, the naphthol isomers electrochemical sensor on E-rGO film with synergistic effect can be expected to result in significant improvements in the sensor performance and the developed method has been successfully applied to human urine sample with a satisfactory result.