Chiral selectors in capillary electrophoresis

Rudaz, S., Calleri, E., Geiser, L., Gherkaoui, S., Prat, J., and Veuthey, J. L. (2003). Infinite enantiomeric resolution of basic compounds using highly sulfated cyclodextrin as chiral selector in capillary electrophoresis. Electrophoresis 24, 2633—2641. 

B Chankvetadze, G Endresz, G Blaschke. Charged cyclodextrin derivatives as chiral selectors in capillary electrophoresis. Chem Soc Rev 25 141-146,... 

T Schmitt, H Engelhardt. Charged and uncharged cyclodextrins as chiral selectors in capillary electrophoresis. Chromatographia 37 475-481, 1993. 

E DeLorenzi, G Massolini, M Quaglia, C Galbusera, G Caccialanza. Evaluation of quail egg white riboflavin—binding protein as a chiral selector in capillary electrophoresis by applying a modified partial-filling technique. Electrophoresis 20 2739-2748, 1999. 

R Gotti, V Cavrini, V Anchisano, G Mascellani. Dermatan sulfate as useful chiral selector in capillary electrophoresis. J Chromatogr A 814 205-211, 1998. 

G Jung, H Hofstetter, S Feiertag, D Stoll, O Hofstetter, KH Wiesmuller, V Schurig. Cyclopeptide libraries as new chiral selectors in capillary electrophoresis. Angew Chem Int Ed Eng, 35 2148-2150, 1996. 

R Vespalec, HA Billiet, J Frank, P Bocek. Vancomycin as a chiral selector in capillary electrophoresis An appraisal of advantages and limitations. Electrophoresis 17 1214-1221, 1996. 

At equilibrium, the effective mobility of an enantiomer in the presence of a chiral selector in capillary electrophoresis is the sum of the electrophoretic mobility of each species containing the enantiomer, weighted by the mole fraction of each species. Assuming for a given separation the enantiomers exist as either the free enantiomer with a mobility, ixr, or the enantiomer-chiral selector complex, p,c,R, then the effective mobility for the enantiomer is given by... 

Xu, H., Yu, X., and Chen, H. Enantiomeric separation of basic drugs with partially filled serum albumin as chiral selector in capillary electrophoresis. Anal. ScL, 20, 1409-1413, 2004. 

Ha P.T.H., Van Schepdael A., Roets E., Hoogmartens J., Investigating the potential of erythromycin and derivatives as chiral selector in capillary electrophoresis. J. Pharm. Biomed. Anal., 34, 861-870 (2004). 

Walshe, M. Garcia, E. Howarth, J. Smyth, M.R. Kelly, M.T. Separation of the enantiomers of propranolol by incorporation of molecularly imprinted polymer particles as chiral selectors in capillary electrophoresis. Anal. Commun. 1997, 34, 119-122. 

Ingelse, B.A., Reijenga, J.C., Claessens, H.A., Everaerts, F. and Fliegei M. (1996a) Ergot alkaloids as novel chiral selectors in capillary electrophoresis. /. High Res. Chromatogr., 19,225-226. 

Fanali S, Desidetio C (1996) Use of vancomycin as chiral selector in capillary electrophoresis. Optimization and quantitation of loxiglumide enantiomers in pharmaceuticals. J High... 

Kumar AP, Park JH. Azithromycin as a new chiral selector in capillary electrophoresis. J. Chromatogr. A 2011 1218 1314-1317. 

Nishi et al. [110] used dextran and dextrin as chiral selectors in capillary-zone electrophoresis. Polysaccharides such as dextrins, which are mixtures of linear a-(l,4)-linked D-glucose polymers, and dextrans, which are polymers of D-glucose units linked predominantly by a-(l,6) bonds, have been employed as chiral selectors in the capillary electrophoretic separation of enantiomers. Because these polymers are electrically neutral, the method is applicable to ionic compounds. The enantiomers of basic or cationic drugs such as primaquine were successfully separated under acidic conditions. The effects of molecular mass and polysaccharide concentration on enantioselectivity were investigated. 

H Nishi, S Izumoto, K Nakamura, H Nakai, T Sato. Dextran and dextrin as chiral selectors in capillary zone electrophoresis. Chromatographia 42 617-630, 1996. 

R Vespalec, S Fanali, P Bocek. Consequences of a maximum existing in the dependence of separation selectivity on concentration of cyclodextrin added as chiral selector in capillary zone electrophoresis. Electrophoresis 15 1523-1525, 1994. 

R Vespalec, V Sustacek, P Bocek. Prospects of dissolved albumin as a chiral selector in capillary zone electrophoresis. J Chromatogr 638 255-261, 1993. 

In the group of Jung [90], a new approach has been developed for the use of selector libraries for chiral separations. Complex peptide libraries consisting of 183 different cyclo-hexapeptides in each sublibrary have been used as chiral additive in capillary electrophoresis. Three libraries separated enantiomers of a-amino acid derivatives as well as, e.g., Troger s base (Fig. 10.7). Meanwhile, our approach has also been applied successfully by Chiari et al. [91], who described the deconvolution of cyclopeptide libraries down to single selectors. 

Hedeland Y, Lehtinen J, Pettersson C. Ketopinic acid and dii-soproylideneketogulonic acid as chiral ion-pair selectors in capillary electrophoresis. Enantiomeric impurity analysis of 5-timolol and l/f,25-ephedrine. J. Chromatogr. A 2007 1141 287-294. 

Capillary electrophoresis employing chiral selectors has been shown to be a useful analytical method to separate enantiomers. Conventionally, instrumental chiral separations have been achieved by gas chromatography and by high performance liquid chromatography.127 In recent years, there has been considerable activity in the separation and characterization of racemic pharmaceuticals by high performance capillary electrophoresis, with particular interest paid to using this technique in modem pharmaceutical analytical laboratories.128 130 The most frequently used chiral selectors in CE are cyclodextrins, crown ethers, chiral surfactants, bile acids, and protein-filled... 

Phinney et al. [Ill] investigated the application of citrus pectins, as chiral selectors, to enantiomer separations in capillary electrophoresis. Successful enantioreso-lution of primaquine and other antimalarials, was achieved by utilizing potassium polypectate as the chiral selector. Changes in pH, chiral additive concentration, and capillary type were studied in relation to chiral resolution. The effect of degree of esterification of pectin materials on chiral recognition was evaluated. 

DK Lloyd, A Ahmed, F Pastore. A quantitative relationship between capacity factor and selector concentration in capillary electrophoresis and high-performance liquid chromatography evidence from the enantioselective resolution of benzoin using human serum albumin as chiral selector. Electrophoresis 18 958-964, 1997. 

DK Lloyd, S Li, P Ryan. Protein chiral selectors in free-solution capillary electrophoresis and packed-capillary electrochromatography. J Chromatogr A 694 285-296, 1995. 

A Ahmed, DK Lloyd. Effect of organic modifiers on retention and enantiomeric separations by capillary electrophoresis with human serum albumin as a chiral selector in solution. J Chromatogr A 766 237—244, 1997. 

In contrast, CSPs have achieved great repute in the chiral separation of enantiomers by chromatography and, today, are the tools of the choice of almost all analytical, biochemical, pharmaceutical, and pharmacological institutions and industries. The most important and useful CSPs are available in the form of open and tubular columns. However, some chiral capillaries and thin layer plates are also available for use in capillary electrophoresis and thin-layer chromatography. The chiral columns and capillaries are packed with several chiral selectors such as polysaccharides, cyclodextrins, antibiotics, Pirkle type, ligand exchangers, and crown ethers. 

To establish chiral separation method for donepezil hydrochloride enantiomers by capillary electrophoresis (CE) and to determine the two enantiomers in plasma [39], alkalized plasma was extracted by isopropa-nol-n-hexane (3 97) and L-butefeina was used as the IS. Enantioresolution was achieved using 2.5% sulfated-beta-cyclodextrin as chiral selector in 25 mmol/1 triethylammonium phosphate solution (pH 2.5) on the uncoated fused-silica capillary column (70 cm x 50 fim i.d.). The feasibility of the method to be used as quantitation of donepezil HC1 enantiomers in rabbit plasma was also investigated. Donepezil HC1 enantiomers were separated at a baseline level under the above condition. The linearity of the response was evaluated in the concentration range from 0.1 to 5 mg/1. The linear regression analysis obtained by plotting the peak area ratio (A(s)/A(i)) of the analyte to the IS versus the concentration (C) showed excellent correlation coefficient The low limit of detection was 0.05 mg/1. The inter- and intra-day precisions (RSD) were all less than 20%. Compared with chiral stationary phase by HPLC, the CE method is simple, reliable, inexpensive, and suitable for studying the stereoseletive pharmacokinetics in rabbit. 

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