VOLTAMMETRIC AND SONOVOLTAMMETRIC STUDIES ON THE OXIDATION OF THYMINEAND CYTOSINE AT A GLASSY-CARBON ELECTRODE

The voltammetric behaviour of the pyrimidine bases thymine and cytosin e is studied using a glassy carbon electrode. In contrast to previous reports that assume electroinactivity at carbon electrodes, it is demo nstrated that both compounds undergo well-defined oxidation at a glass y carbon electrode. The experimental conditions that influence the ele ctrode reaction, in particular the pH of the electrolyte solution, are varied systematically and optimized for voltammetric determinations. The application of ultrasound in combination with differential pulse v oltammetry results in a reliable analytical procedure for thymine and cytosine measurements avoiding electrode fouling and maintaining the e lectrode characteristics. The effect of ultrasound is mainly to enhanc e transport of electroactive species and to clean the electrode in sit u. Besides studying the sonovoltammetric behaviour of cytosine and thy mine separately, simultaneous determinations are also performed and ex tended to the analysis of adenine, guanine, thymine and cytosine in th e same solution. (C) 1997 Elsevier Science S.A.