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See detailInfluence of the nature of the electrolyte on the chiral separation of basic compounds in nonaqueous capillary electrophoresis using heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-cyclodextrin
Servais, Anne-Catherine ULg; Fillet, Marianne ULg; Chiap, Patrice ULg et al

in Journal of Chromatography. A (2005), 1068(1), 143-150

The influence on the enantiomeric resolution of the nature of the cationic BGE component (sodium, ammonium or potassium) and that of the anionic component (chloride, formate, methanesulfonate or ... [more ▼]

The influence on the enantiomeric resolution of the nature of the cationic BGE component (sodium, ammonium or potassium) and that of the anionic component (chloride, formate, methanesulfonate or camphorsulfonate) as well as the concentration of heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-cyclodextrin (HDMS-beta-CD), the selected chiral selector, was studied in nonaqueous capillary electrophoresis (NACE). For this purpose, two D-optimal designs with 33 and 26 experimental points were applied. Three beta-blockers (atenolol, celiprolol and propranolol) and three local anesthetics (bupivacaine, mepivacaine and prilocaine) were selected as basic model compounds. Both cationic and anionic BGE components were found to have a deep impact on the enantiomeric resolution of the investigated analytes but it is the cationic component that has shown the strongest influence. Indeed, in some cases, the change of the latter led to a complete loss of enantioresolution. Based on the observed results, two NACE systems were recommended, namely ammonium formate and potassium camphorsulfonate in a methanolic solution containing HDMS-beta-CD and acidified with formic acid, in order to separate efficiently the enantiomers of basic drugs. (c) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailSéparation et dosage de substances médicamenteuses par électrophorèse capillaire en milieu non aqueux : Influence de l’utilisation simultanée d’une cyclodextrine et d’un agent d’appariement d’ions
Servais, Anne-Catherine ULg

Doctoral thesis (2005)

The use of nonaqueous electrolyte solutions in capillary electrophoresis (CE) has made it possible to open up new horizons in the field of drug analysis. The achiral separation of four beta-blockers was ... [more ▼]

The use of nonaqueous electrolyte solutions in capillary electrophoresis (CE) has made it possible to open up new horizons in the field of drug analysis. The achiral separation of four beta-blockers was first investigated in nonaqueous CE (NACE) using the principle of ion-pair formation. Camphorsulfonate was selected as the counter-ion. The influence on resolution of parameters such as the nature and concentration of the counter-ion and the ionic components of the background electrolyte was studied by means of a univariate approach. Experimental designs were then applied to estimate possible quadratic effects and first-order interactions. Finally, the optimal conditions obtained by the univariate and the multivariate approaches were compared. The enantiomeric separation of basic pharmaceuticals was then investigated using an original combination in NACE, namely an ion-pairing reagent together with a cyclodextrin (CD). The simultaneous addition to the methanolic background electrolyte of (+)-S-camphorsulfonate or an alkanesulfonate and an anionic beta-CD derivative, namely heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-CD (HDMS-beta-CD), led to partial or complete enantioresolution in all cases. The influence on the enantioseparation of the nature and concentration of the counter-ion and the anionic CD derivative was studied by means of a univariate approach. In order to understand the effects on the enantiomeric resolution of the simultaneous use of camphorsulfonate and HDMS-b-CD, experimental designs were applied. A fast method development strategy was finally recommended for the enantioseparation of basic drug compounds. The influence on the enantiomeric resolution of the nature of the cationic and anionic background electrolyte components was also studied in the presence of several HDMS-beta-CD concentrations. Both cationic and anionic background electrolyte components were found to have a deep impact on the enantioseparation but it is the cationic component that seems to have the strongest influence. Finally, NACE was successfully applied to the resolution and the determination of salbutamol enantiomers in urine samples using heptakis(2,3-di-O-acetyl-6-O-sulfo)-beta-CD. Solid phase extraction was used for sample clean-up prior to the CE separation. The method was then fully validated using a new approach based on accuracy profiles over a concentration range from 375 to 7500 ng/ml for each enantiomer. [less ▲]

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See detailEvaluation de liquides ioniques chiraux comme sélecteurs pour des séparations électrocinétiques d'énantiomères en veine liquide capillaire
François, Yannis; Juillerat, E.; Villemin, Didier et al

Poster (2005)

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See detailEnantiomeric separation of basic compounds usin heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-cyclodextrin in combination with potassium camphorsulfonate in nonaqueous capillary electrophoresis: Optimization by means of an experimental design
Servais, Anne-Catherine ULg; Fillet, Marianne ULg; Chiap, Patrice ULg et al

in Electrophoresis (2004), 25(16), 2701-2710

The enantiomeric separation of a series of basic pharmaceuticals (beta-blockers, local anesthetics, sympathomimetics) has been investigated in nonaqueous capillary electrophoresis (NACE) systems using ... [more ▼]

The enantiomeric separation of a series of basic pharmaceuticals (beta-blockers, local anesthetics, sympathomimetics) has been investigated in nonaqueous capillary electrophoresis (NACE) systems using heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-cyclodextrin (HDMS-P-CD) in combination with potassium camphorsulfonate (camphorSO(3)(-)). For this purpose, a face-centered central composite design with 11 experimental points was applied. The effect of the concentrations of HDMS-beta-CD and camphorSO(3)(-) on enantioresolution was statistically evaluated and depended largely on the considered analyte. The presence of camphorSO(3)(-) was found to be particularly useful for the enantioseparation of compounds with high affinity for the anionic CD. CamphorSO(3)(-) seems to act as a competitor, reducing the affinity for the CD, probably by ion-pair formation with these analytes. For compounds with lower affinity for HDMS-beta-CD, the combination of camphorSO(3)(-) and the CD appeared to have a favorable effect on enantioresolution only if the optimal CD concentration could be reached. On the other hand, for compounds characterized by a very low affinity for the anionic CD, the association of camphorSO(3)(-) and HDMS-beta-CD is always unfavorable. Finally, experimental conditions were selected by means of the multivariate approach in order to obtain the highest resolution (R-s) value for each studied compound. [less ▲]

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See detailDetermination of salbutamol enantiomers in human urine using heptakis(2,3-di-O-acetyl-6-O-sulfo)-beta-cyclodextrin in nonaqueous capillary electrophoresis
Servais, Anne-Catherine ULg; Chiap, Patrice ULg; Hubert, Philippe ULg et al

in Electrophoresis (2004), 25(10-11), 1632-1640

Nonaqueous capillary electrophoresis (NACE) was successfully applied to the resolution and the determination of salbutamol enantiomers in urine samples using heptakis(2,3-di-O-acetyl-6-O-sulfo)-beta ... [more ▼]

Nonaqueous capillary electrophoresis (NACE) was successfully applied to the resolution and the determination of salbutamol enantiomers in urine samples using heptakis(2,3-di-O-acetyl-6-O-sulfo)-beta-cyclodextrin (HDAS-beta-CD). After optimization of the electrophoretic parameters, namely the background electrolyte (BGE) composition and the HDAS-beta-CD concentration, salbutamol enantiomers were completely resolved using a BGE made up of 10 mm ammonium formate and 15 mm HDAS-beta-CD in methanol acidified with 0.75 M formic acid. Isoprenaline was selected as internal standard. Solid-phase extraction (SPE) was used for sample cleanup prior to the CE separation. Different sorbents involving polar, nonpolar interactions or dual retention mechanisms were evaluated and extraction cartridges containing both nonpolar and strong cation-exchange functionalities were finally selected. Salbutamol enantiomers recoveries from urine samples were determined. The method was then successfully validated using a new approach based on accuracy profiles over a concentration range from 375 to 7500 ng/mL for each enantiomer. [less ▲]

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See detailEffects of background electrolyte composition and addition of selectors on separation selectivity in nonaqueous capillary electrophoresis
Fillet, Marianne ULg; Servais, Anne-Catherine ULg; Crommen, Jacques ULg

in Electrophoresis (2003), 24(10), 1499-1507

This review gives a survey of the approaches employed to obtain, enhance and tune selectivity in nonaqueous capillary electrophoresis (NACE). Recent developments in NACE are described and the effects of ... [more ▼]

This review gives a survey of the approaches employed to obtain, enhance and tune selectivity in nonaqueous capillary electrophoresis (NACE). Recent developments in NACE are described and the effects of background electrolyte composition and addition of selectors on separation selectivity are discussed. The use of one organic solvent, a mixture of several organic solvents or the use of additives to tune separation selectivity in NACE is presented and a list of relevant applications is included. [less ▲]

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See detailSynergistic effects of ion-pairing in the enantiomeric separation of basic compounds with cyclodextrin derivatives in nonaqueous capillary electrophoresis
Servais, Anne-Catherine ULg; Fillet, Marianne ULg; Abushoffa, Adel M. et al

in Electrophoresis (2003), 24(3), 363-369

The enantiomeric separation of various kinds of basic pharmaceuticals has been investigated in nonaqueous capillary electrophoresis (NACE) systems using an ion-pairing reagent in combination with ... [more ▼]

The enantiomeric separation of various kinds of basic pharmaceuticals has been investigated in nonaqueous capillary electrophoresis (NACE) systems using an ion-pairing reagent in combination with cyclodextrins (CDs). The simultaneous addition to the methanolic background electrolyte (BGE) of (+)-S-camphorsulfonate or alkanesulfonates and an anionic beta-cyclodextrin derivative, heptakis(2,3-dimethyl-6-sulfato)-beta-cyclodextrin (HDMS-beta-CD), led to partial or complete enantioresolution in most cases. In the absence of ion-pairing reagent, the enantiomeric resolution obtained with this CD derivative was most often completely lost or strongly reduced, indicating the important role of ion-pairing in the chiral recognition mechanism in these NACE systems. The influence of the nature and concentration of the counterion and the anionic CD derivative on the enantioseparation of basic compounds was studied. Synergistic effects between these two kinds of charged additives were clearly observed. [less ▲]

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