Selective determination of inosine in the presence of uric acid and hypoxanthine using modified electrode

This article describes the selective determination of inosine (INO) in the presence of important physiological interferents, uric acid (VA) and hypoxanthine (HXN), by differential pulse voltammetry at physiological pH (7.2) using the electropolymerized film of 3-amino-5-mercapto-1,2,4-triazole (p-AMTa) modified glassy carbon (GC) electrode. The electropolymerization of AMTa was carried out by the potentiodynamic method in 0.1 M H2SO4. An atomic force microscopy image shows that the p-AMTa film contains a spherical-like structure. Bare GC electrode fails to resolve the voltammetric signal of INO in the presence of UA and HXN due to the surface fouling caused by the oxidized products of VA and HXN. However, p-AMTa film modified GC electrode (p-AMTa electrode) not only separates the voltammetric signals of VA, HXN, and INO, with potential differences of 730 mV between VA and HXN and 310 mV between HXN and INO, but also shows enhanced oxidation current for them. The selective determination of INO in the presence of VA and HXN at physiological pH was achieved for the first time. Using the amperometric method, we achieved the lowest detection of 50 nM for INO. The practical application of the current modified electrode was demonstrated by determining the concentration of INO in human blood serum and urine samples. (C) 2011 Elsevier Inc. All rights reserved.