Separation and detection of peroxynitrite and its metabolites by capillary electrophoresis with UV detection

A method for the separation and direct detection of peroxynitrite (ONOO−) and two of its degradation products, nitrite (NO2−) and nitrate (NO3−), using capillary electrophoresis with ultraviolet detection is described. The separation parameters were optimized and included electrokinetic injection, a run buffer consisting of 25 mM K2HPO4 7.5 mM DTAB, pH 12, and a field strength of −323 V/cm. A diode array UV detector was employed in these studies as it allowed the determination of all three species simultaneously. Nitrate and nitrite provided the maximum response at 214 nm while peroxynitrite generated the best response at 302 nm. All three species could be detected at 214 nm, while simultaneous detection at 214 and 302 nm positively identified each peak.