Graphene paste electrode: Electrochemical behavior and analytical applications for the quantification of NADH

This work reports a critical study of the electrochemical behavior of a graphene paste electrode (GrPE) obtained by mixing graphite, mineral oil, and graphene obtained by reduction of graphene oxide with ascorbic acid and characterized by IR and Raman spectroscopy. The GrPE was characterized by scanning electron microscopy, cyclic voltammetry and amperometry. The effect of the GrPE composition on the electrochemical response of the resulting electrodes was studied using different redox probes. GrPE selectively catalyzes the electrooxidation of different bioanalytes such as ascorbic acid, dopamine and NADH without suffering common surface passivation. The advantages of GrPE for the simultaneous, selective and sensitive quantification of NADH in the presence of ascorbic acid are also reported.