Detection of epinephrine and metanephrine at a nitrogen doped three-dimensional porous graphene modified electrode

A nitrogen doped three-dimensional porous graphene (NG) modified electrode was fabricated in our work. The electrochemical characterization based on the voltammetric behavior of hexaammineruthenium chloride (Ru(NH₃)₆Cl₃) showed that the redox peak currents were significantly enhanced at the modified electrode compared with that of the bare GCE, which was ascribed to the excellent properties of NG. Meanwhile, distinguishing electrocatalysis was observed for epinephrine (EP) and metanephrine (MEP) at the modified electrode. The redox mechanisms of EP and MEP were researched and proposed. The modified electrode can be used for the sensitive detection of EP and MEP. By differential pulse voltammetry, the anodic peak currents were linearly proportional to the concentrations from 1.0 μM to 1.0 mM with a sensitivity of 0.021 μA μM^-1 for EP and 1.5 μM to 0.41 mM with a sensitivity of 0.0095 μA μM^-1 for MEP. The detection limits were ascertained to be 0.67 μM and 1.3 μM for EP and MEP, respectively. Additionally, the detection of EP and MEP was possible in the presence of ascorbic acid and uric acid. The modified electrode showed good stability, reproducibility and repeatability, and was applied to the detection of EP and MEP in human plasma samples with recoveries from 98.9% to 100.9%, and EP hydrochloride injections with recoveries from 100.3% to 104.6%.