In this work, we report the novel green synthesis of Co3O4 nanoparticles (Co3O4NPs) using extract of Elaeagnus angustifolia leaves plant as a mild and non-toxic stabilizing agent. The synthesized Co3O4NPs was characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and FTIR spectroscopy. In order to obtain its applicability, the carbon paste electrode (CPE) modified with the Co3O4NPs and graphene oxide (GO) (Co3O4NPs/GO/CPE) was fabricated as anew sensor for trace determinations of dopamine (DA) and mefenamic acid (MFA). The electrochemical investigations on DA and MFA were carried out by application of differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamprometry (CA) methods. The results showed that Co3O4NPs as the modifier in the proposed sensor can accelerates the electron transfer reactions of DA and MFA. Under the optimum conditions, the electrode provides a linear response versus DA and MFA concentrations in the range of 0.5-250 µM and 1-500 µM, with a detection limit of 0.15 µM and 0.3 µM, respectively. The modified electrode exhibited some advantages such as convenient preparation, good stability, high sensitivity and selectivity toward DA and MFA determination.
