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Model: Electrophoresis, Transport in a Capillary Column. Introduction. In analytical chemistry CZE ( Capillary Zone Electrophoresis ) is the most used electrophoretic separation technique. A typical CZE instrument consists of a capillary, detector and a high voltage power supply.
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Introduction • In analytical chemistry CZE ( Capillary Zone Electrophoresis ) is the most used electrophoretic separation technique. • A typical CZE instrument consists of a capillary, detector and a high voltage power supply.
Model Definition • The mass balance equation for an electrophoretic system can be written as: • where cj denotes the concentration of species j, Fj the migrational flux of the species j and Dj the diffusion coefficient for species j.
Model Definition • For a ionic species, the migrational flux in CZE is caused by two effects; • A flow of the background electrolyte ( BGE ), usually an electro-osmotic flow • The local electric field strength in the column. • The mass balance analysis gives the following expression for F: where u denotes the linear velocity of the BGE (=the electro-osmotic flow ), zj the charge of species j, mj = the electro-phoretic mobility of species j, and E = the local electric field strength within the column.
Results • Concentration profile for Na+, Bz-, and BzCl- at t = 0. • Concentration profile for Na+, AcO-, Bz-, and BzCl-at t = 0.5 s. • Electric field strength, E, at t = 0 and t = 0.4 s. a) b) c)