Capillary electrochromatography mobile phase electroosmotic flow

Capillary Electrochromatography Another approach to separating neutral species is capillary electrochromatography (CEC). In this technique the capillary tubing is packed with 1.5-3-pm silica particles coated with a bonded, nonpolar stationary phase. Neutral species separate based on their ability to partition between the stationary phase and the buffer solution (which, due to electroosmotic flow, is the mobile phase). Separations are similar to the analogous HPLC separation, but without the need for high-pressure pumps, furthermore, efficiency in CEC is better than in HPLC, with shorter analysis times. 

Capillary electrochromatography (CEC) — A special case of capillary liquid chromatography, in which the mobile phase motion is driven by -> electroosmotic volume flow through a capillary, filled, packed, or coated with a stationary phase, (which may be assisted by pressure). The retention time is determined by a combination of -> electrophoretic mobility and chromatographic retention. 

Capillary electrochromatography (CEC) is a high-efficiency microseparation technique in which mobile-phase transport through a capillary (usually 50- to lOO-pm I.D., packed with stationary-phase particles) is achieved by electroos-motic flow instead of a pressure gradient as in HPLC (342-349). The absence of backpressure in electroosmotic flow allows the use of smaller particles and longer columns than in HPLC. In the reversed-phase mode, CEC has the potential to yield efficiencies 5 to 10 times greater than reversed-phase HPLC. 

Flush for several hours at normal flow rates with the mobile phase to be used for the separation. Further condition on the capillary electrochromatography instrument with a stepwise increase in the operating voltage until a stable and adequate electroosmotic flow is obtained. 

Szekely, L. and Freitag, R., Study of the electroosmotic flow as a means to propel the mobile phase in capillary electrochromatography in view of further miniaturization of capillary electrochromatography systems, Electrophoresis, 26, 1928, 2005. 

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