Reduced graphene oxide-cyclodextrin-chitosan electrochemical sensor: Effective and simultaneous determination of o- and p-nitrophenols

A novel electrochemical sensor based on cyclodextrin and chitosan-functionalized reduced graphene oxide composite film was designed and prepared to detect o- and p-nitrophenols simultaneously. Apart from the synergistic effect of large specific surface area of reduced graphene oxide (RGO), the adsorption of nitrophenols (NPhs) through electrostatic interaction benefited from large quantities of host-guest recognition sites on cyclodextrin (CD) and abundant functional groups on chitosan. By taking advantage of the salient features of RGO, CDs, and chitosan, p-nitrophenol (p-NPh) and o-nitrophenol (o-NPh) can be determined simultaneously based on their nitroaromatic/hydroxylamine redox reactions. Under the optimized experimental conditions, a wide linear range was obtained over o-NPh concentration from 0.12 μM to 0.28 μM and 5 μM to 40 μM with a detection limit of 0.018 μM (S/N = 3) as well as p-NPh concentration from 0.06 μM to 0.16 μM and 5 μM to 40 μM along with a detection limit of 0.016 μM (S/N = 3). In addition, the newly developed reduced graphene oxide-cyclodextrin-chitosan (RGO-CD-CS) sensor displayed high accuracy, satisfactory reproducibility, good stability, and adequate efficiency in simultaneously detecting o-NPh and p-NPh in aqueous samples.