Electrochemical investigations of 8-hydroxydeoxyguanosine and its determination at an edge plane pyrolytic graphite electrode

Abstract

The electrochemical oxidation of 8-hydroxydeoxyguanosine (8-OHdG) has been studied at the edge plane surface of a pyrolytic graphite electrode (EPPGE) by cyclic sweep, square wave voltammetry, spectral studies, controlled potential electrolysis and related techniques. The oxidation of 8-OHdG occurred in a single well-defined peak over the entire pH range. The effect of pH revealed that the oxidation of 8-OHdG involved an equal number of electrons and protons. The 8-OHdG exhibited a linear calibration curve over a concentration range of 0.5–100 μM and the detection limit and sensitivity are found to be 28 × 10⁻⁹ M and 1.068 μA μM⁻¹ respectively. The kinetics of the decay of the UV-absorbing intermediate generated during oxidation has been studied and the decay has been found to follow first order kinetics having a rate constant (k) in the range ∼2.5 × 10⁻³ s⁻¹. The products of electrochemical oxidation have been characterized by using GC-MS studies. A tentative mechanism for the oxidation of 8-OHdG has also been suggested.