Electroosmotic flow electrokinetic chromatography

Figure 4.2 Classification of electrophoresis according to the contribution of the electroosmotic flow. CZE, Capillary zone electrophoresis MECC, micellar electrokinetic capillary chromatography CEC, capillary electrochromatography cIEF capillary isoelectric focusing cGE, capillary gel electrophoresis.

Janini GM, Muschik GM, Issaq HJ. Micellar electrokinetic chromatography in zero-electroosmotic flow environment. J Chromatogr B Biomed Appl 1996 683 29. 

A recently proposed method (314) for the separation of fat-soluble vitamins by electrokinetic chromatography was further developed (315). The separation medium consisted of acetonitrile water (80 20 v/v) and contained tetradecylam-monium bromide as a pseudostationary phase. The high acetonitrile content was necessary to keep the hydrophobic vitamins in solution during electrophoresis. With the cathode placed at the capillary outlet, the fat-soluble vitamins were separated based on different hydrophobic interactions with the pseudo-stationary phase. The vitamins migrated in order of decreasing hydrophobicity prior to the electroosmotic flow. 

Ryan R, Donegan S, Power J, Altria K (2010) Advances in the theory and application of MEEKC. Electrophoresis 31 755-767. doi 10.1002/elps.200900568 Yu L, Xu X, Huang L, Lin J, Chen G (2008) Microemulsion electrokinetic chromatography coupling with field amplified sample injection and electroosmotic flow suppressant for analysis of some quinolizidine alkaloids. J Chromatogr A 1198-1199 220-225. doi 10.1016/j.chroma2008.05.024... 

Figure 8.2.3. Micellar electrokinetic chromatography (MEKC) in a capillary with electroosmotic flow of the aqueous solution with micelles in cocurrent flow.

As the name implies, micellar electrokinetic chromatography (MEKC) is a chromatographic technique in which samples are separated by differential partitioning between two phases (Fig. 9). The technique is usually performed in uncoated capillaries under alkaline conditions to generate a high electroosmotic flow. The background electrolyte contains a surfactant at a concentration above its critical... 

The applicability of phosphonium-based ionic liquids, as pseudo-stationary phases in electrokinetic capillary chromatography (EKC), with UV-detection, has been elucidated for the separation of model analytes including neutral benzene and benzene-derivatives. It was found that the electroosmotic flow was strongly influenced by the type of ionic liquid, and the strongest impact on the flow was achieved with... 

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