Generalized model of electromigration with 1:1 (analyte:selector) complexation stoichiometry: Part I. Theory

Dubský, Pavel; Müllerová, Ludmila; Dvořák, Martin; Gaš, Bohuslav

doi:10.1016/j.chroma.2015.01.029

Cited by 16 publications

(11 citation statements)

References 37 publications

(65 reference statements)

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“…S‐β‐CD as used in the experiments represents a multiple isomer mixture of molecules. For fast complexation with a 1:1 stoichiometry between analytes and the ligands of a multiple isomer mixture, complexation for each enantiomer can be described in the same manner as for a single isomer reaction , i.e. with an apparent complexation constant K and a mobility of the formed complex u c (Table ).…”

Section: Resultsmentioning

confidence: 97%

Inverse cationic ITP for separation of methadone enantiomers with sulfated β‐cyclodextrin as chiral selector

et al. 2018

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Chiral ITP of the weak base methadone using inverse cationic configurations with H+ as leading component and multiple isomer sulfated β‐CD (S‐β‐CD) as leading electrolyte (LE) additive, has been studied utilizing dynamic computer simulation, a calculation model based on steady‐state values of the ITP zones, and capillary ITP. By varying the amount of acidic S‐β‐CD in the LE composed of 3‐morpholino‐2‐hydroxypropanesulfonic acid and the chiral selector, and employing glycylglycine as terminating electrolyte (TE), inverse cationic ITP provides systems in which either both enantiomers, only the enantiomer with weaker complexation, or none of the two enantiomers form cationic ITP zones. For the configuration studied, the data reveal that only S‐methadone migrates isotachophoretically when the S‐β‐CD concentration in the LE is between about 0.484 and 1.113 mM. Under these conditions, R‐methadone migrates zone electrophoretically in the TE. An S‐β‐CD concentration between about 0.070 and 0.484 mM results in both S‐ and R‐methadone forming ITP zones. With >1.113 mM and < about 0.050 mM of S‐β‐CD in the LE both enantiomers are migrating within the TE and LE, respectively. Chiral inverse cationic ITP with acidic S‐β‐CD in the LE is demonstrated to permit selective ITP trapping and concentration of the less interacting enantiomer of a weak base.

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Section: Resultsmentioning

confidence: 97%

Inverse cationic ITP for separation of methadone enantiomers with sulfated β‐cyclodextrin as chiral selector

et al. 2018

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“…As described by Dubský et al. , fast complexation with a 1:1 stoichiometry between analytes and the ligands of a multiple isomer mixture can be described in the same manner as for a single isomer complexation reaction when overall complexation parameters, that is, K i over and u c,i over , are used. For the system with HS‐γ‐CD, the effective mobility of analyte i can be described as :

u_{e f f, i} = \frac{u_{f, i} + u_{normalc, normali}^{o v e r} K_{i}^{o v e r} {([], H normalS - γ - CD)}_{t o t}}{1 + K_{i}^{o v e r} {([], H normalS - γ - CD)}_{t o t}},

where

0true u_{normalc, normali}^{o v e r} = \sum_{q} u_{normalc, normali}^{q} K_{normali}^{q} χ_{q} / K_{i}^{o v e r}

, u f denotes the mobility of the free, uncomplexed component, u c is the mobility of the formed complex, q refers to the cyclodextrin isomer, and χ q is the molar fraction of the qth selector in the mixture.…”

Section: Input Parameters For Simulationsmentioning

confidence: 99%

“…In comparison to the GENTRANS data presented in , the concentration of ketamine was lowered by a factor of 100 and norketamine was added to the reaction mixture and given the same initial distribution as ketamine. Furthermore, the multiple isomer mixture HS‐γ‐CD was described as a single isomer assuming a degree of substitution and negative charge of 13 (and the amount of sodium was increased accordingly) and CYP3A4 was omitted from the simulations due to its low concentration and thereby negligible contribution to the evolution of the overall component profiles. The incubation step was simulated with 1000 segments by allowing diffusion only (no electric field applied) for 11.5 min, that is, the total time of incubation and cooling .…”

Section: Input Parameters For Simulationsmentioning

confidence: 99%

Computer simulation of the enantioselective separation of weak bases in an online capillary electrophoresis based microanalysis configuration comprising sulfated cyclodextrin as selector

Mikkonen

Thormann

2018

Electrophoresis

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Computer simulation was utilized to characterize the electrophoretic processes occurring after reactant mixing in an online assay format used for monitoring the enantioselective N-demethylation of ketamine to norketamine in the presence of highly sulfated γ-cyclodextrin (HS-γ-CD). The incubated reaction mixture (at pH 7.4 and without chiral selector) is bracketed by a low pH BGE containing 2% HS-γ-CD as chiral selector, thereby forming a discontinuous buffer system. Upon power application, simulation provides insight into the formation of moving boundaries and new zones together with the prediction of the behavior of ketamine and norketamine enantiomers. The analytes first migrate cationically in a zone electrophoretic manner until they come in contact with HS-γ-CD upon which enantioseparation is initiated. Complexation has a focusing effect and the electrophoretic transport becomes reversed, that is, toward the anode. Simulation revealed that the initial conditions for the chiral separation, including buffer components concentrations, pH, and ionic strength, are different than those in the BGE. As a consequence thereof, the experimentally determined complexation parameters for the BGE were unable to correctly describe the migration behavior of the analytes in this column section. An increase in the input binding constants by a factor of two to four, as a result of the decreased ionic strength, resulted in simulation data that agreed with experimental findings.

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“…The theory results in a generalized model of selector-assisted CE with 1:1 (analyte:selector) complexation stoichiometry (the overall multifree-analyte-form multi-selector model, M A M S model) [42]. In this model, L protonated/deprotonated states of the free (uncomplexed) analyte A i0 (i = {1, .…”

Section: Introductionmentioning

confidence: 99%

“…The M A M S model (1) is valid under the following conditions: (i) only 1:1 complexation (analyte:selector) takes place; (ii) the kinetics of the complexation are much faster than those of the electrophoretic movement; (iii) the ionic strength (IS) of the BGE is constant (the complexation constants K ij are defined by the equilibrium concentrations, not the activities, and therefore depend on the ionic strength of the solution). The detailed derivation and validity conditions of the model are discussed in detail in Part I of this series [42]. Though not given explicitly in Eq.…”

Section: Introductionmentioning

confidence: 99%

Generalized model of electromigration with 1:1 (analyte:selector) complexation stoichiometry: Part II. Application to dual systems and experimental verification

Müllerová

Dubský

Gaš

2015

Journal of Chromatography A

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Generalized model of electromigration with 1:1 (analyte:selector) complexation stoichiometry: Part I. Theory

Cited by 16 publications

References 37 publications

Inverse cationic ITP for separation of methadone enantiomers with sulfated β‐cyclodextrin as chiral selector

Inverse cationic ITP for separation of methadone enantiomers with sulfated β‐cyclodextrin as chiral selector

Computer simulation of the enantioselective separation of weak bases in an online capillary electrophoresis based microanalysis configuration comprising sulfated cyclodextrin as selector

Generalized model of electromigration with 1:1 (analyte:selector) complexation stoichiometry: Part II. Application to dual systems and experimental verification

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