Determination of nitrite on manganese dioxide doped reduced graphene oxide modified glassy carbon by differential pulse voltammetry

Abstract

A transition metal oxide, MnO2, doped reduced graphene oxide (rGO) was prepared to develop a 2D-carbon-metal oxide composite modified glassy carbon electrode (GC) for sensitive electrochemical determination of nitrite ion (NO2-). GO was first synthesized and reduced to rGO followed by a MnO2 doping process. The obtained MnO2-rGO composite was then characterized with Raman spectroscopy, infrared spectroscopy, and scanning electron microscopy techniques. The MnO2-rGO coated on GC electrodes were electrochemically characterized using cyclic voltammetry, electrochemical impedance spectroscopy and optimized for the determination of NO2- using differential pulse voltammetry. A linear calibration curve was obtained between 0.1 and 5.5 mu M with LOD and LOQ values of 0.02 mu M and 0.06 mu M, respectively. The selectivity of the proposed sensor was tested in different substances and no significant interference was found. The sensor validation test showed that the precision (% RSD) and accuracy of the system were around 1.95-2.73% and (- 3.5)-2.5%, respectively. Finally, real sample tests with commercially available juice samples and tap water confirmed that the method could detect the spiked NO2- in real samples. As a result, the sensitive and easy determination of NO2- has been achieved using MnO2-rGO composite materials in real samples with good recovery values and minimum interference.