Electrochemistry of azidothymidine

The electrochemical properties of 3′-azido-3′-deoxythymidine (AZT) were investigated using cyclic voltammetry, differential-pulse voltammetry and chronocoulometry. These methods were used to determine the reduction pathway of AZT and the number of protons and electrons involved in the reduction process. Experiments using a narrow range of moderate scan rates (50–1000 mV s −1) indicate that the electrochemical reduction of AZT proceeds via a four-electron, two-proton mechanism to a reduced species that undergoes a fast chemical reaction to give a species that precipitates on the electrode surface, hindering further electron transfer. The fouling is a function of the concentration of AZT and the electroanalysis time. Evidence of fouling was seen for electrolysis times between 10 and 30 ms during a chronocoulometric experiment. AZT also adsorbs on mercury electrodes at potentials more positive than its reduction potential. The diffusion coefficient for AZT was calculated to be 4.90 × 10 −6 cm 2 s −1 using the irreversible cyclic voltammetry equation and an n value of four electrons.