Dynamic high‐resolution computer simulation of electrophoretic enantiomer separations with neutral cyclodextrins as chiral selectors

Abstract

GENTRANS, a comprehensive one-dimensional dynamic simulator for electrophoretic separations and transport, was extended for handling electrokinetic chiral separations with a neutral ligand. The code can be employed to study the 1:1 interaction of monovalent weak and strong acids and bases with a single monovalent weak or strong acid or base additive, including a neutral cyclodextrin, under real experimental conditions. It is a tool to investigate the dynamics of chiral separations and to provide insight into the buffer systems used in chiral capillary zone electrophoresis (CZE) and chiral isotachophoresis. Analyte stacking across conductivity and buffer additive gradients, changes of additive concentration, buffer component concentration, pH, and conductivity across migrating sample zones and peaks, and the formation and migration of system peaks can thereby be investigated in a hitherto inaccessible way. For model systems with charged weak bases and neutral modified β-cyclodextrins at acidic pH, for which complexation constants, ionic mobilities, and mobilities of selector-analyte complexes have been determined by CZE, simulated and experimentally determined electropherograms and isotachopherograms are shown to be in good agreement. Simulation data reveal that CZE separations of cationic enantiomers performed in phosphate buffers at low pH occur behind a fast cationic migrating system peak that has a small impact on the buffer composition under which enantiomeric separation takes place.

Microfluidic isotachophoresis: A review

“…SPRESSO now includes an extended Onsager–Fuoss correction to determine effective electrophoretic mobilities, and an extended Debye–Hückel formula to calculate and correct ionic activities as well as modifying the governing equations to take into account variable cross‐sectional area geometries in the context of a 1D geometry . GENTRANS has been modified to handle ITP separations with a complexing agent and a version of SIMUL (SIMUL 5 Complex) can simulate affinity ZE with a complexing agent . SIMUL and SPRESSO can both calculate the pH of solutions made from multiple, general amphoteric compounds, including ionic strength corrections .…”

Recent progress in analytical capillary isotachophoresis

“…shows an example of the effect of grid density, a parameter with impact on simulation speed, on numerical oscillations using the GENTRANS simulator). GENTRANS was also presented in an extended version for simulation of electrokinetic chiral separations with a neutral ligand. The presented examples of interaction of weak bases and neutral CDs include ITP separation of methadone enantiomers in presence of 2‐hydroxypropyl‐β‐CD, for which simulations of the separation dynamics are shown and insight into the properties of the system is provided.…”

Recent advances in electrodriven enantioseparations

“…Breadmore et al. extended the code of another one‐dimensional dynamic simulation program, GENTRANS, to handling of chiral separations by including complexation equilibria and the mobilities of the analyte–selector complexes . The parameters of enantioseparations of methadone in acidic BGEs using (2‐hydroxy)propyl‐β‐CD and DM‐β‐CD as chiral selectors were used for simulations.…”