Simultaneous electrochemical determination of epinephrine and uric acid in the presence of ascorbic acid using SnO2/graphene nanocomposite modified glassy carbon electrode

A novel biosensor has been constructed based on SnO2/graphene nanocomposite modified glassy carbon electrode (GCE) and was employed for the simultaneous determination of epinephrine (EP) and uric acid (UA) in the presence of common interferent ascorbic acid (AA) at physiological pH (7.0). SnO2/graphene composites were synthesized by a simple one-pot chemical reduction method. Physico-chemical analyses such as X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) revealed that the crystalline SnO2 nanoparticles were finely dispersed on the surface of graphene. The SnO2/graphene modified GCE exhibited enhanced electrocatalytic activity toward the oxidation of EP and UA when compared to the GO and SnO2 modified GCEs. Under the optimal conditions, the oxidation peak currents increased linearly with concentration over the wide range of 0.5-200 mu M and 0.1-200 mu M with the detection limits of 0.017 mu M and 0.28 mu M for EP and UA, respectively. The proposed modified electrode displayed high selectivity, good stability and reproducibility, and was successfully applied for the determination of epinephrine in epinephrine hydrochloride injection and uric acid in human urine samples. (C) 2015 Elsevier B.V. All rights reserved.