Highly sensitive p-nitrophenol determination employing a new sensor based on N-Methylphenazonium methyl sulfate and graphene: Analysis in natural and treated waters

This paper describes a rapid and highly sensitive method for determination of p-nitrophenol (p-NP) in water samples employing a glassy carbon electrode modified with N-Methylphenazonium methyl sulfate (NMP) adsorbed on graphene. This modified electrode presented very efficient capability toward p-NP reduction, decreasing substantially its oxidation potential to −0.6V vs Ag/AgCl. Electrochemical impedance spectroscopy and FTIR spectroscopy measurements were also carried out in characterizing of the modification process. It has been found that the electrode modification with NMP and graphene has significantly enhanced the electrode response toward p-NP reduction. Linear response range from 1nmolL−1 up to 1170nmolL−1 (or 0.001–1.17μmolL−1) by differential pulse voltammetry and from 500nmolL−1 up to 5600nmolL−1 (or 0.50–5.60μmolL−1) by amperometry were obtained with sensitivities of 42.42μALμmol−1 and 28.84μALμmol−1, respectively. The proposed method was effectively applied for the determination of p-NP in samples of natural and treated waters and recovery tests to the analyte presented satisfactory results.