Abstract
A detailed computer simulation study of the isotachophoretic migration and separation of norpseudoephedrine stereoisomers for cases with the neutral selector added to the leader, immobilized to the capillary wall or support, or partially present in the separation column is presented. The electrophoretic transport of the analytes from the sampling compartment into the separation medium with the selector, the formation of a transient mixed zone, the separation dynamics of the stereoisomers with a free or immobilized selector, the dependence of the leader pH, the ionic mobility of norpseudoephedrine, the complexation constant and selector immobilization on steady-state plateau zone properties, and zone changes occurring during the transition from the chiral environment into a selector free leader are thereby visualized in a hitherto unexplored way. For the case with the selector dissolved in the leading electrolyte, simulation data are compared to those observed in experimental setups with coated fused-silica capillaries that feature minimized electroosmosis and zone detection with conductivity and absorbance detectors.
Highlights
Isotachophoresis (ITP) is performed in a discontinuous buffer system with the sample introduced at the interface between the two electrolytes
In ITP, effective mobilities can be influenced via inclusion of chemical equilibria, including protolysis [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15], complex formation between a counter ion and the components to be separated [16,17], complexation of analytes with uncharged or charged additives in the leader [18] or a charged ligand of like charge added to the terminator [19]
Enantioseparation is achieved in presence of DIMEB
Summary
Isotachophoresis (ITP) is performed in a discontinuous buffer system with the sample introduced at the interface between the two electrolytes. Sample components with intermediate effective mobilities compared to those of the electrolyte components of like charge separate according to differences in effective mobilities by forming a pattern of consecutive zones or peaks between the leading zone and the terminating zone with zone properties becoming adjusted according to the electrophoretic regulating principle. Analytes present in trace amounts become concentrated without forming a plateau-shaped zone and migrate as a sharp peak within a steady-state boundary. In ITP, effective mobilities can be influenced via inclusion of chemical equilibria, including protolysis (proper selection of pH and counter component) [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15], complex formation between a counter ion and the components to be separated [16,17], complexation of analytes with uncharged or charged additives in the leader [18] or a charged ligand of like charge added to the terminator [19]
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