Urinary 8-hydroxy-2′-deoxyguanosine (8OHdG) is an excellent marker of oxidative DNA damage. Until now, urinary 8OHdG has been measured by high-performance liquid chromatography with electrochemical detection. A simple and sensitive method for the analysis of urinary 8OHdG by capillary electrophoresis with end-column amperometric detection has been developed and is described in this chapter. A single-step solid-phase extraction procedure was optimized and used for extracting 8OHdG from human urine. To improve the sensitivity of this method, a new focusing technique based on a dynamic pH junction was used. In the end, the urinary concentration of 8OHdG in healthy persons, patients with cancer, patients with diabetic nephropathy, and smokers was determined. Emphasis is focused on the establishment and application of the methods.
