Electrochemical reduction of metronidazole at a DNA-modified glassy carbon electrode

The electrochemical reduction of metronidazole was investigated using, for the first time, the newly developed DNA-modified glassy carbon electrode. The results are compared with reduction at bare glassy carbon electrodes. The potentials for reduction were less negative when using the DNA-modified glassy carbon electrode although the mechanism was the same. A potential-pH dependence of one electron per proton was observed in acid media whereas for neutral and alkaline solution no dependence was found. The DNA-modified glassy carbon electrode enables preconcentration of the sample for chosen times on the electrode surface which is convenient for analytical applications. The limit of detection using the DNA-modified glassy carbon electrode at pH 4.5 with 2 min preconcentration is 1.67 mu M, and without preconcentration it is three times higher, 3.25 mu M At a bare glassy carbon electrode, where preconcentration is not possible, the limit of detection for the same pH is 3.44 mu M. (C) 1997 Elsevier Science S.A.