Influence of ring opening-closure equilibrium of oxanine, a novel damaged nucleobase, on migration behavior in capillary electrophoresis

Oxanine (Oxa) is a novel damaged nucleobase which is generated from guanine by HNO2 or NO. As a fundamental study for detection of Oxa formed in vivo, capillary zone electrophoresis (CZE) and micellar electrokinetic chromatog raphy (MEKC) have been tested by changing the pH of the running buffer. At pH 7, CZE did not separate Oxa from seven other nucleobases, and MEKC separ ated Oxa but their peaks migrated close together. In both the techniques, a n extreme peak broadening occurred for Oxa around pH 9 and a good peak sepa ration was achieved at pH 12. The behavior of the Oxa peak is discussed in relation to the unique multistep acid-base equilibria of Oxa. (C) 2000 Else vier Science B.V. All rights reserved.