Isotopic separation of [(14)n]- and [(15)n]aniline by capillary electrophoresis using surfactant- controlled reversed electroosmotic flow.

Separation of isotopically labeled [(14)N]- and [(15)N]aniline was achieved using capillary electrophoresis based on the isotopic effect on pK(a). The effects of the buffer co-ion, pH, and electroosmotic mobility on the resolution are investigated in this paper. Electroosmotic flow (EOF) was controlled using the zwitterionic surfactant Rewoteric AM CAS U as buffer additive. The resultant EOF was anodic (reversed) and low in magnitude (0.6 × 10(-)(4) cm(2)/(V·s)). The resolution of [(14)N]- and [(15)N]aniline was 1.22. Addition of a cationic surfactant, cetyltrimethylammonium bromide, to the zwitterionic surfactant increased the magnitude of the anodic EOF. This EOF improved the resolution to 1.33 based on mobility counterbalance.