Microemulsion Electrokinetic Chromatography (MEEKC) is a relatively new capillary electrophoresis technique using a microemulsion as a separation carrier. Two kinds of mixture samples were separated by MEEKC and compared with Micellar Electrokinetic Chromatography (MEKC). The effects of microemulsion composition on MEEKC separation were studied. The different core phase showed different migration time, efficiency and time window. The separation was also affacted by core phase and cosurfactant concentration. Using microemulsion consisting of 80mmol/L octane -120mmol/L sodium dodecyl sulphate -900mmol/L 1-butanol -10mmol/L borate, relative standard deviation (RSD) of migration time was less than 0.8% and RSD of peak area was less than 3% (n=6). High separation efficiency can be obtained if the microemulsion composition is properly chosen.

Key words: BORAX, NORMAL OCTANE, N-BUTANOL, MICROEMUSION, LAURYL SODIUM SULFATE