Separation and detection of peroxynitrite using microchip electrophoresis with amperometric detection

Peroxynitrite (ONOO(-)) is a highly reactive species implicated in the pathology of several cardiovascular and neurodegenerative diseases. It is generated in vivo by the diffusion-limited reaction of nitric oxide (NO(*)) and superoxide anion ((*)O(2)(-)) and is known to be produced during periods of inflammation. Detection of ONOO(-) is made difficult by its short half-life under physiological conditions (approximately 1 s). Here we report a method for the separation and detection of ONOO(-) from other electroactive species utilizing a microchip electrophoresis device incorporating an amperometric detection scheme. Microchip electrophoresis permits shorter separation times (approximately 25 s for ONOO(-)) and higher temporal resolution than conventional capillary electrophoresis (several minutes). This faster analysis allows ONOO(-) to be detected before substantial degradation occurs, and the increased temporal resolution permits more accurate tracking of dynamic changes in chemical systems.