Oxidative DNA damage is one of the most significant and extensively studied mechanisms of neurodegenerative diseases such as Parkinson and Alzheimer. This study was devoted to proposing an electrochemical method for monitoring oxidative DNA damage by hydroxyl radical through dopamine reacted with the localization of ferric catalytic. A hydrophobic room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), was applied as nonaqueous solvent for the generation of free radicals. DNA damage could be detected by differential pulse voltammetry signals of the electroactive indicator [Co(bpy)(3)](3+) and electrochemical impedance spectroscopy signals of [Fe(CN)(6)](3-)/(4-). More dramatic damage degree of DNA film initiated by dopamine/Fe-2(SO4)(3) reaction in [bmim][PF6] compared with that in an aqueous solution indicated that ionic liquid was much more suitable for the investigation of radicals induced DNA damage. The influences of incubation time and the molar ratio of dopamine/Fe-2(SO4)(3) to current respond were also explored. The most likely mechanism of DNA damage here was that the hydroxyl radical generated from the ferric ions facilitated oxidation of dopamine disturbed DNA double helix structure or caused DNA strand break. Furthermore, it turned out that both ascorbic acid and rutin could protect DNA from oxidative damage efficiently under certain conditions. (C) 2013 Elsevier Ltd. All rights reserved.