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A perspective on enantioselective chromatography by comparing ultra-high performance supercritical fluid chromatography and normal-phase liquid chromatography through the use of a Pirkle-type stationary phase. Trends Analyt Chem 2022. [DOI: 10.1016/j.trac.2021.116511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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2
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Tanács D, Orosz T, Ilisz I, Péter A, Lindner W. Unexpected effects of mobile phase solvents and additives on retention and resolution of N-acyl-D,L-leucine applying Cinchonane-based chiral ion exchangers. J Chromatogr A 2021; 1648:462212. [PMID: 33992991 DOI: 10.1016/j.chroma.2021.462212] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/22/2021] [Accepted: 04/25/2021] [Indexed: 11/18/2022]
Abstract
Chiral ion exchangers based on quinine (QN) and quinidine (QD), namely Chiralpak QN-AX and QD-AX as anionic and ZWIX(+) and ZWIX(-) as zwitterionic ion exchanger chiral stationary phases (CSPs) have been investigated with respect to their retention and chiral resolution characteristics. For the evaluation of the effects of the composition of the polar organic bulk solvents of the mobile phase (MP) and those of the organic acid and base additives acting as displacers necessary for a liquid chromatographic ion-exchange process, racemic N-(3,5-dinitrobenzoyl)leucine and other related analytes were applied. The main aim was to evaluate the impact of the MP variations on the observed, and thus the apparent enantioselectivity (αapp), and the retention factor. Significant differences were found using either polar protic methanol (MeOH) or polar non-protic acetonitrile (MeCN) solvents in combination with the acid and base additives as counter- and co-ions. It became clear, that the charged sites of both the chiral selectors of the CSPs and the analytes get specifically solvated, accompanied by the adsorption of all MP components on the CSP, thereby building a stagnant "stationary phase layer" with a composition different from the bulk MP. Via a systematic change of the MP composition, trends of resulting αapp and retention factors have been identified and discussed. In a detailed set of experiments, the effect of the concentration of the acid component in the MP containing MeOH or MeCN was specifically investigated, with the acid considered to be a displacer in anion-exchange type chromatographic systems. Surprisingly, all four chiral columns retained and resolved the tested N-acyl-Leu analytes with αapp values up to 21 within a retention factor window of 0.03 and 10 with pure MeOH as eluent. However, using pure MeCN as eluent, an almost infinite-long retention of the acidic analyte was noticed in all cases. We suggest that the rather different thickness of the solvation shells generated by MeOH or MeCN around the charged/chargeable sites of the chiral selector determines eventually the strength of the electrostatic selector-selectand interactions. As a control experiment we included the non-chiral N-acylglycine derivatives as analyte in all cases to support the interpretations with respect to the contribution of the enantioselective and non-enantioselective retention factor increments as a part of the observed αapp.
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Affiliation(s)
- Dániel Tanács
- Institute of Pharmaceutical Analysis, Interdisciplinary Excellence Centre, University of Szeged, H-6720 Szeged, Somogyi u. 4, Hungary
| | - Tímea Orosz
- Institute of Pharmaceutical Analysis, Interdisciplinary Excellence Centre, University of Szeged, H-6720 Szeged, Somogyi u. 4, Hungary
| | - István Ilisz
- Institute of Pharmaceutical Analysis, Interdisciplinary Excellence Centre, University of Szeged, H-6720 Szeged, Somogyi u. 4, Hungary.
| | - Antal Péter
- Institute of Pharmaceutical Analysis, Interdisciplinary Excellence Centre, University of Szeged, H-6720 Szeged, Somogyi u. 4, Hungary
| | - Wolfgang Lindner
- Department of Analytical Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria.
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3
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Bilonda MK, Mammino L. Computational studies of biologically active alkaloids of plant origin: an overview. PHYSICAL SCIENCES REVIEWS 2020. [DOI: 10.1515/psr-2019-0132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Computational studies nowadays constitute a crucial source of information for drug development, because they provide information on many molecular properties and also enable predictions of the properties of not-yet-synthesized compounds. Alkaloids are a vast group of natural products exhibiting a variety of biological activities, many of which are interesting for drug development. On the other hand, computational studies of biologically active alkaloids have so far mostly focused on few particularly relevant or “popular” molecules, such as quinine, caffeine, or cocaine, with only few works on the other molecules. The present work offers an overview of existing computational studies on alkaloid molecules, from the earliest ones to the most recent, and considering all the theoretical approaches with which studies have been performed (both quantum mechanics and molecular dynamics). The considered studies are grouped according to their objectives and outcomes, such as conformational analysis of alkaloid molecules, effects of selected solvents on their properties, docking studies aimed at better understanding of the interactions between alkaloid molecules and biological targets, studies focusing on structure activity relationships, and computational studies performed to confirm experimental results. It is concluded that it would be important that computational studies on many other alkaloid molecules are performed and their results made available, covering their different classes as well as the variety of their biological activities, to attain better understanding of the properties not only of individual molecules, but also of groups of related molecules and of the overall alkaloids family.
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Affiliation(s)
- Mireille K. Bilonda
- School of Mathematical and Natural Sciences, University of Venda , Thohoyandou , South Africa
- Faculty of Science, University of Kinshasa , Kinshasa , Democratic Republic of Congo
| | - Liliana Mammino
- School of Mathematical and Natural Sciences, University of Venda , Thohoyandou , South Africa
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He S, He Y, Cheng L, Wu Y, Ke Y. Novel chiral ionic liquids stationary phases for the enantiomer separation of chiral acid by high-performance liquid chromatography. Chirality 2018; 30:670-679. [PMID: 29476561 DOI: 10.1002/chir.22839] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 12/08/2017] [Accepted: 01/05/2018] [Indexed: 11/06/2022]
Abstract
Novel chiral ionic liquid stationary phases based on chiral imidazolium were prepared. The ionic liquid chiral selector was synthesized by ring opening of cyclohexene oxide with imidazole or 5,6-dimethylbenzimidazole, and then chemically modified by different substitute groups. Chiral stationary phases were prepared by bonding to the surface of silica sphere through thioene "click" reaction. Their enantioselective separations of chiral acids were evaluated by high-performance liquid chromatography. The retention of acid sample was related to the counterion concentration and showed a typical ion exchange process. The chiral separation abilities of chiral stationary phases were greatly influenced by the substituent group on the chiral selector as well as the mobile phase, which indicated that, besides ion exchange, other interactions such as steric hindrance, π-π interaction, and hydrogen bonding are important for the enantioselectivity. In this report, the influence of bulk solvent components, the effects of varying concentration, and the type of the counterion as well as the proportion of acid and basic additives were investigated in detail.
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Affiliation(s)
- Shanshan He
- Engineering Research Center of Pharmaceutical Process Chemistry, School of Pharmacy, Ministry of Education, East China University of Science and Technology, Shanghai, China
| | - Yunchao He
- Engineering Research Center of Pharmaceutical Process Chemistry, School of Pharmacy, Ministry of Education, East China University of Science and Technology, Shanghai, China
| | - Lingping Cheng
- Engineering Research Center of Pharmaceutical Process Chemistry, School of Pharmacy, Ministry of Education, East China University of Science and Technology, Shanghai, China
| | - Yaling Wu
- Engineering Research Center of Pharmaceutical Process Chemistry, School of Pharmacy, Ministry of Education, East China University of Science and Technology, Shanghai, China
| | - Yanxiong Ke
- Engineering Research Center of Pharmaceutical Process Chemistry, School of Pharmacy, Ministry of Education, East China University of Science and Technology, Shanghai, China
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Tran LN, Jeong JA, Park JH. Enantiomer Separation of Acidic Chiral Compounds on atert-Butylcarbamoylquinine-Silica Hybrid Monolith by Capillary Electrochromatography. B KOREAN CHEM SOC 2016. [DOI: 10.1002/bkcs.10820] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Le Ngoc Tran
- Department of Chemistry; Yeungnam University; Gyeongsan 38541 Korea
| | - Jeong-Ae Jeong
- Department of Chemistry; Yeungnam University; Gyeongsan 38541 Korea
| | - Jung Hag Park
- Department of Chemistry; Yeungnam University; Gyeongsan 38541 Korea
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6
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Tran LN, Park JH. Enantiomer separation of acidic chiral compounds on a quinine-silica/zirconia hybrid monolith by capillary electrochromatography. J Chromatogr A 2015; 1396:140-7. [DOI: 10.1016/j.chroma.2015.03.085] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 03/31/2015] [Accepted: 03/31/2015] [Indexed: 10/23/2022]
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7
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Al-Hussin A, Boysen RI, Saito K, Hearn MT. Preparation and electrochromatographic characterization of new chiral β-cyclodextrin poly(acrylamidopropyl) porous layer open tubular capillary columns. J Chromatogr A 2014; 1358:199-207. [DOI: 10.1016/j.chroma.2014.06.067] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 06/19/2014] [Accepted: 06/19/2014] [Indexed: 11/16/2022]
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8
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Novel carbamoyl type quinine and quinidine based chiral anion exchangers implementing alkyne–azide cycloaddition immobilization chemistry. J Chromatogr A 2014; 1337:85-94. [DOI: 10.1016/j.chroma.2014.02.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 02/10/2014] [Accepted: 02/11/2014] [Indexed: 11/18/2022]
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9
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Lai X, Tang W, Ng SC. Novel β-cyclodextrin chiral stationary phases with different length spacers for normal-phase high performance liquid chromatography enantioseparation. J Chromatogr A 2011; 1218:3496-501. [DOI: 10.1016/j.chroma.2011.03.071] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 03/26/2011] [Accepted: 03/28/2011] [Indexed: 10/18/2022]
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10
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Julínek O, Lindner W, Urbanová M. Study of stereoselective interactions of carbamoylated quinine and quinidine with 3,5-dinitrobenzoyl α-amino acids using VCD spectroscopy in the region of CH stretching vibrations. Chirality 2010; 23:354-60. [DOI: 10.1002/chir.20929] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Accepted: 09/10/2010] [Indexed: 12/29/2022]
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11
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Wang Y, Young DJ, Tan TTY, Ng SC. "Click" immobilized perphenylcarbamated and permethylated cyclodextrin stationary phases for chiral high-performance liquid chromatography application. J Chromatogr A 2010; 1217:5103-8. [PMID: 20579654 DOI: 10.1016/j.chroma.2010.06.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Revised: 05/24/2010] [Accepted: 06/01/2010] [Indexed: 10/19/2022]
Abstract
Two cyclodextrin-based chiral stationary phases have been prepared by immobilization of functionalized mono-6-azido-beta-CD derivatives to alkynyl modified silica via "click" chemistry and applied to the HPLC enantioseparation of various chiral compounds. The perphenylcarbamated CD CSP (CCP-CSP) exhibited excellent chiral recognition of a wide range of analytes including racemic aryl alcohols, flavonoids, bendroflumethiazide, atropine and some beta-blockers. Methanol proved to be a better organic modifier than acetonitrile for most of the analytes with the exception of bendroflumethiazide. The "click" chemistry immobilized permethylated CD CSP (CCM-CSP) afforded poor chiral recognition for most analytes, but could resolve non-aromatic ionone derivatives which were not separated on CCP-CSP. These results suggest that resolution with cyclodextrin derived CSPs depend on a complex interplay of 'host'-'guest' inclusion, hydrogen bonding, pi-pi and hydrophobic interactions.
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Affiliation(s)
- Yong Wang
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore
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12
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Lee MR, Gwon JR, Park JH. Enantioseparation of Neutral Compounds on a Quinine Carbamate-Immobilized Zirconia in Reversed-Phase Capillary Electrochromatography. B KOREAN CHEM SOC 2010. [DOI: 10.5012/bkcs.2010.31.01.082] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Ding GS, Tang AN. Capillary electrochromatographic separation of racemates on a norvancomycin-bonded monolithic column under reversed-phase conditions. J Chromatogr A 2008; 1208:232-8. [DOI: 10.1016/j.chroma.2008.08.075] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 08/21/2008] [Accepted: 08/21/2008] [Indexed: 11/30/2022]
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14
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Enantioselective complexation of carbamoylated quinine and quinidine with N-blocked amino acids: vibrational and electronic circular dichroism study. Anal Bioanal Chem 2008; 393:303-12. [DOI: 10.1007/s00216-008-2323-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Revised: 07/26/2008] [Accepted: 07/28/2008] [Indexed: 10/21/2022]
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15
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André C, Berthelot A, Thomassin M, Guillaume YC. Enantioselective aptameric molecular recognition material: Design of a novel chiral stationary phase for enantioseparation of a series of chiral herbicides by capillary electrochromatography. Electrophoresis 2006; 27:3254-62. [PMID: 16865666 DOI: 10.1002/elps.200500070] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A chiral stationary phase derived from an L-RNA aptamer is evaluated for the enantiomer separation of a series of herbicide molecules (aryloxypropionic, aryloxyphenoxypropionic, and aminopropionic acid) by CEC after binding to biotin and grafting upon streptavidin-modified porous glass beads. We demonstrated that the aptamer capillary was stable in term of efficiency and retention during a long period. The influences of the mobile phase constitution and its flow-velocity on the enantioseparation were also investigated. The results suggest that the interactions of the enantiomer during CEC are solely based on chromatographic mechanisms and that the electrophoresis plays only a minor role. The separation efficiency and peak shape could be improved by Mg2+ divalent cation that stabilized the aptamer secondary structure and thus enhanced the mass transfer kinetics during the ligand-aptamer binding process. In addition, it was demonstrated that the determination of the enantiomerization barrier of flamprop was possible using this chiral stationary phase.
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Affiliation(s)
- Claire André
- Equipe des Sciences Séparatives et Biopharmaceutiques (2SB)-EA 3924, Laboratoire de Chimie Analytique, Faculté de Médecine Pharmacie, Besançon, France
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16
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Liu H, Yu A, Liu F, Shi Y, Han L, Chen Y. Chiral separation of cefadroxil by capillary electrochromatography. J Pharm Biomed Anal 2006; 41:1376-9. [PMID: 16600557 DOI: 10.1016/j.jpba.2006.02.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2005] [Revised: 02/09/2006] [Accepted: 02/15/2006] [Indexed: 10/24/2022]
Abstract
In this paper, the chiral separation of cefadroxil was studied by capillary electrochromatography. Monolithic capillary column was prepared for the separation of cefadroxil enantiomers. The optimum buffer contained 28.5 mmol/L sodium acetate, 0.95% (v/v) acetic acid, 19 mmol/L beta-cyclodextrin (beta-CD) and 5% (v/v) isopropanol in formamide solution (pH 7.0), with the running voltage of 12 kV, the UV detector wavelength of 254 nm, the sample injected time of 8s and the temperature of 25 degrees C. Under these conditions, the column efficiency of cefadroxil enantiomers were N1=5324 and N2=23,768 with a selectivity factor (alpha) of 1.056 and resolution (Rs) of 0.978. The effect of buffer pH value, beta-CD concentration, organic modifier (isopropanol) concentration and voltage was also investigated for the separation by CEC.
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Affiliation(s)
- Haixing Liu
- Department of Chemistry, Weifang University, Weifang 261061, China.
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17
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Flook KJ, Cameron NR, Wren SAC. Polymerised bicontinuous microemulsions as stationary phases for capillary electrochromatography. J Chromatogr A 2004; 1044:245-52. [PMID: 15354444 DOI: 10.1016/j.chroma.2004.05.102] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Monolithic columns for capillary electrochromatography (CEC) were prepared by in situ polymerisation of bicontinuous microemulsions containing butyl methacrylate. The resulting monoliths were found to be permeable to mobile phase flow and their behaviour as CEC stationary phases was investigated. It was found that the monoliths were able to separate a simple test mixture of phthalates, but that efficiencies were low. However, several advantages of the monoliths compared to conventional ODS packed columns were found: preparation time is short, many columns can be prepared from the same batch of microemulsion and column conditioning is much faster. The columns show promise as stationary phases for CEC, but more development is required to improve efficiencies.
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Affiliation(s)
- Kelly J Flook
- Department of Chemistry, University of Durham, Durham DH1 3LE, UK
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18
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Advanced statistical evaluation of the complex formation constants from electrophoretic data II. Anal Chim Acta 2004. [DOI: 10.1016/j.aca.2003.10.087] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Krawinkler KH, Maier NM, Ungaro R, Sansone F, Casnati A, Lindner W. Novel cinchona carbamate selectors with complementary enantioseparation characteristics for N-acylated amino acids. Chirality 2004; 15 Suppl:S17-29. [PMID: 12884371 DOI: 10.1002/chir.10257] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The synthesis and chromatographic evaluation of the enantiomer separation capabilities of covalently immobilized calix[4]arene-cinchona carbamate hybrid type receptors derived from quinine (QN) and its corresponding C9-epimer (eQN) in different solvents are reported. The receptors display complementary enantiomer separation profiles in terms of elution order, chiral substrate specificity, and mobile phase characteristics, indicating the existence of two distinct chiral recognition mechanisms. The QN-derived receptor binds the (S)-enantiomers of N-acylated amino acids more strongly, shows preferential recognition of open-chained amino acids, and superior enantioselectivity in polar media such as methanol/acetic acid. In contrast, the eQN congener preferentially recognizes the corresponding (R)-enantiomers, displays good enantioselectivity (alpha up to 1.74) for cyclic amino acids, and enhanced stereodiscriminating properties in apolar mobile phases, e.g., chloroform/acetic acid. A comparison of the enantiomer separation profiles with those of the corresponding QN and eQN tert-butyl carbamate congeners indicates no significant level of cooperativity between the calix[4]arene module and the cinchona units in terms of overall chiral recognition, most probably as a consequence of residual conformational flexibility of the calixarene module and the carbamate linkage.
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20
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Chapter 14 Chromatography of amino acids and peptides. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/s0301-4770(04)80027-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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21
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Czerwenka C, Lämmerhofer M, Lindner W. Structure-enantioselectivity relationships for the study of chiral recognition in peptide enantiomer separation on cinchona alkaloid-based chiral stationary phases by HPLC: Influence of the N-terminal protecting group. J Sep Sci 2003. [DOI: 10.1002/jssc.200301577] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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22
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Czerwenka C, Zhang MM, Kählig H, Maier NM, Lipkowitz KB, Lindner W. Chiral Recognition of Peptide Enantiomers by Cinchona Alkaloid Derived Chiral Selectors: Mechanistic Investigations by Liquid Chromatography, NMR Spectroscopy, and Molecular Modeling. J Org Chem 2003; 68:8315-27. [PMID: 14575453 DOI: 10.1021/jo0346914] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The chiral recognition mechanism of a cinchona alkaloid based chiral selector for N-protected peptide enantiomers was investigated. A chiral stationary phase derived from this selector was employed for liquid chromatographic enantiomer separations. It showed exceptionally high enantiomer discrimination for the (all-R)- and (all-S)-enantiomers of dialanine (alpha = 20), while a pronounced loss of chiral recognition occurred upon the insertion of an additional alanine residue into the peptide backbone. This reduction of enantioselectivity was investigated in great detail by NMR spectroscopy of complexes of the chiral selector and the analyte enantiomers accompanied by molecular modeling studies. Investigation of intramolecular NOEs provided the conformational states of the free and complexed forms of the selector. The analysis of complexation-induced shifts yielded information on intermolecular interactions and allowed us to propose binding models, which were further supported by the observation of intermolecular NOEs, indicating the relative arrangements of selector and analytes. Stochastic molecular dynamics simulations were able to reproduce the chromatographic retention orders and energy differences, as well as the intermolecular NOEs. The computational data were used to evaluate the intermolecular forces responsible for analyte binding. In addition, the relative contributions of the fragments of the chiral selector to the enantioselective binding event were assessed. A spatial arrangement of the chiral selector and the analyte allowing the primary ionic interaction as well as hydrogen bonding and pi-pi-stacking to take place simultaneously was found to be essential to obtain very high enantioselectivities.
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Affiliation(s)
- Christoph Czerwenka
- Institute of Analytical Chemistry, University of Vienna, Währingerstrasse 38, 1090 Wien, Austria
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23
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Jiskra J, Claessens HA, Cramers CA. Stationary and mobile phases in capillary electrochromatography (CEC). J Sep Sci 2003. [DOI: 10.1002/jssc.200301305] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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24
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Zarbl E, Lämmerhofer M, Woschek A, Hammerschmidt F, Parenti C, Cannazza G, Lindner W. Strong versus weak chiral cation exchangers: Comparative evaluation for enantiomer separation of chiral bases by non-aqueous CEC. J Sep Sci 2002. [DOI: 10.1002/1615-9314(20021101)25:15/17<1269::aid-jssc1269>3.0.co;2-r] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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25
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Desiderio C, Rudaz S, Veuthey JL, Raggi MA, Fanali S. Use of vancomycin silica stationary phase in packed capillary electrochromatography. Part IV: Enantiomer separation of fluoxetine and norfluoxetine employing UV high sensitivity detection cell. J Sep Sci 2002. [DOI: 10.1002/1615-9314(20021101)25:15/17<1291::aid-jssc1291>3.0.co;2-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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26
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Svec F. Capillary electrochromatography: a rapidly emerging separation method. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2002; 76:1-47. [PMID: 12126266 DOI: 10.1007/3-540-45345-8_1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
This overview concerns the new chromatographic method--capillary electrochromatography (CEC)--that is recently receiving remarkable attention. The principles of this method based on a combination of electroosmotic flow and analyte-stationary phase interactions, CEC instrumentation, capillary column technology, separation conditions, and examples of a variety of applications are discussed in detail.
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Affiliation(s)
- Frantisek Svec
- Department of Chemistry, University of California, Berkeley 94720-1460, USA.
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27
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Chankvetadze L, Kartozia I, Yamamoto C, Chankvetadze B, Blaschke G, Okamoto Y. Enantioseparations in capillary liquid chromatography and capillary electrochromatography using amylose tris(3,5-dimethylphenylcarbamate) in combination with aqueous organic mobile phase. J Sep Sci 2002. [DOI: 10.1002/1615-9314(20020701)25:10/11<653::aid-jssc653>3.0.co;2-t] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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28
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Tegeler T, El-Rassi Z. Surfactant-mediated capillary electrochromatography with octadecyl-silica- packed capillary columns for the separation of nonpolar compounds. Case of pyrethroid insecticides. Electrophoresis 2002; 23:1217-23. [PMID: 12007119 DOI: 10.1002/1522-2683(200205)23:9<1217::aid-elps1217>3.0.co;2-c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Capillary electrochromatography (CEC) with octadecyl-silica-packed capillary columns was evaluated in the separation of nonpolar compounds, e.g., pyrethroid insecticides, using surfactant-rich mobile phases. This novel concept is referred to as surfactant-mediated capillary electrochromatography (SM-CEC), and is based on including a charged surfactant, namely sodium di-2-ethylhexyl sulfosuccinate (DOSS), in the mobile phase. Under these conditions, DOSS plays the role of a slowly moving pseudostationary phase so that solutes are partitioned between a mobile phase, a fixed stationary phase and a slowly moving pseudostationary phase. The SM-CEC system was investigated with pyrethroid insecticides over a wide range of DOSS and acetonitrile concentrations in the mobile phase. Pyrethroid insecticides, which are very hydrophobic solutes consisting of geometric isomers and diastereomers, were better resolved in SM-CEC than in straight CEC.
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Affiliation(s)
- Tony Tegeler
- Department of Chemistry, Oklahoma State University, Stillwater, OK 74078-3071, USA
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29
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Gübitz G, Schmid MG. Chiral separation by chromatographic and electromigration techniques. A review. Biopharm Drug Dispos 2001; 22:291-336. [PMID: 11835252 DOI: 10.1002/bdd.279] [Citation(s) in RCA: 194] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This review gives a survey of different chiral separation principles and their use in high-performance liquid chromatography (HPLC), gas chromatography (GC), supercritical fluid chromatography (SFC), thin-layer chromatography (TLC), capillary electrophoresis (CE) and capillary electrochromatography (CEC) highlighting new developments and innovative techniques. The mechanisms of the different separation principles are briefly discussed and some selected applications are shown.
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Affiliation(s)
- G Gübitz
- Institute of Pharmaceutical Chemistry and Pharmaceutical Technology, Karl-Franzens University, Universitätsplatz 1, A-8010 Graz, Austria.
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30
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Abstract
The review summarizes recent developments in enantioseparations by capillary electrochromatography (CEC). Selected fundamental aspects of CEC are discussed in order to stress those features which may allow the success of this technique in the competitive field of enantioseparations. In addition, the comparative characteristics of the different modes of chiral CEC and the stationary phases are presented. The effects of the characteristics of the stationary and liquid phases and operational conditions on the separation results are discussed. Finally, some future trends are briefly addressed.
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Affiliation(s)
- S Fanali
- Istituto di Cromatografia del C.N.R., Area della Ricerca di Roma, Monterotondo Scalo, Italy
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31
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Chankvetadze B, Kartozia I, Breitkreutz J, Okamoto Y, Blaschke G. Effect of organic solvent, electrolyte salt and a loading of cellulose tris (3,5-dichlorophenyl-carbamate) on silica gel on enantioseparation characteristics in capillary electrochromatography. Electrophoresis 2001; 22:3327-34. [PMID: 11589297 DOI: 10.1002/1522-2683(200109)22:15<3327::aid-elps3327>3.0.co;2-j] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The effect of the amount of the chiral selector, cellulose tris(3,5-dichlorophenylcarbamate) (CDCPC) on the separation characteristics of enantiomers of some charged and neutral analytes was studied in capillary electrochromatography (CEC). For better understanding of the effect of the loading of the chiral selector on the particles and pore size of the packing material, laser-beam particle size analyzer and scanning electron microscopy (SEM) were used. As shown in this study, CDCPC can be used for CEC enantioseparations of a wide range of chiral charged and neutral analytes with high efficiency. The loading of the polysaccharide derivative on the surface of silica materials even in high amounts does not markedly affect the particle size and porous structure of the packing material. The separation characteristics are strongly affected by the loading of CDCPC onto silica gel in both CEC and capillary liquid chromatography (CLC).
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Affiliation(s)
- B Chankvetadze
- Institute of Pharmaceutical Chemistry, University of Münster, Germany
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32
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Lämmerhofer M, Svec F, Fréchet JM, Lindner W. Capillary electrochromatography in anion-exchange and normal-phase mode using monolithic stationary phases. J Chromatogr A 2001; 925:265-77. [PMID: 11519811 DOI: 10.1016/s0021-9673(01)01034-2] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Hydrophilic macroporous weak and strong anion-exchange stationary phases have been prepared in a monolithic format within untreated fused-silica capillaries by the simple thermally or UV-initiated polymerization of 2-dimethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate and ethylene dimethacrylate in the presence of a binary porogenic mixture of dodecanol and cyclohexanol. The tertiary amino functionalities were then alkylated in situ to afford strong anion-exchangers. These new monolithic stationary phases with optimized porous properties were used for the CEC separation of various organic anions. Thus, a mixture of 2-substituted propionic acid drugs (profens) was separated in 13 min and high column efficiencies of up to 231,000 plates/m were achieved. The separation of substituted benzoic acids indicates that the selectivity results primarily from the anion-exchange interactions, while electrophoretic migration contributes only slightly. In addition, these hydrophilic anion-exchangers are also able to separate weakly acidic, neutral and basic compounds such as phenols, xanthines and aromatic amines in normal-phase electrochromatographic mode.
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Affiliation(s)
- M Lämmerhofer
- Department of Chemistry, University of California, Berkeley 94720-1460, USA
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33
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Kawamura K, Otsuka K, Terabe S. Capillary electrochromatographic enantioseparations using a packed capillary with a 3 microm OD-type chiral packing. J Chromatogr A 2001; 924:251-7. [PMID: 11521871 DOI: 10.1016/s0021-9673(01)00902-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Enantiomer separations by capillary electrochromatography (CEC) using a packed capillary were investigated. As a chiral stationary phase, an OD-type packing material of 3 microm particle diameter, which is a silica-gel based material coated with cellulose tris(3,5-dimethylphenylcarbamate), was employed. The chiral packing was packed into a 100 microm I.D. fused-silica capillary by a pressurized method. Several racemic enantiomers were successfully resolved with acidic or basic buffers containing acetonitrile as mobile phases. The separation efficiencies obtained in this chiral CEC system were superior to those in the previously reported chiral CEC system using 5 microm particles. The typical plate heights obtained for several enantiomers were 4.6-6.6 microm or reduced plate heights of 1.5-2.2. Good repeatabilities in the migration time, peak height, and corrected peak area were observed as well as for the plate number. As an application study of this CEC system, an optical purity test was carried out by using benzoin enantiomers. A 1% content of one enantiomer in the other enantiomer was successfully separated and detected.
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Affiliation(s)
- K Kawamura
- Department of Material Science, Faculty of Science, Himeji Institute of Technology, Kamigori, Hyogo, Japan
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34
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Franco P, Klaus PM, Minguillón C, Lindner W. Evaluation of the contribution to enantioselectivity of quinine and quinidine scaffolds in chemically and physically mixed chiral selectors. Chirality 2001; 13:177-86. [PMID: 11284022 DOI: 10.1002/chir.1017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Three "dimeric" C(9)-carbamates of quinine (QN) and quinidine (QD), that is, QN-QN, QD-QD, and QN-QD (chemically prepared mixture of the two cinchona-derived subunits), separated by an ethylene spacer were synthesized and used as chiral selectors for HPLC and capillary electrophoresis (CE) for the resolution of chiral acids. The chiral recognition abilities of these dimers and of several physically prepared mixtures thereof were compared in order to estimate the contribution of every cinchona scaffold to the overall enantioselectivity. The diverse phenomena observed in nonaqueous capillary electrophoresis (NACE), either using the selector added to the background electrolyte (BGE) in the total filling or partial filling mode, led us to rationalize, taking into account the relative mobilities of the chiral selectors in the capillary. The chromatographic and electrophoretic properties were compared with those of the corresponding "monomeric" QN and QD carbamates.
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Affiliation(s)
- P Franco
- Institute of Analytical Chemistry, University of Vienna, Vienna, Austria
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35
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Desiderio C, Aturki Z, Fanali S. Use of vancomycin silica stationary phase in packed capillary electrochromatography I. Enantiomer separation of basic compounds. Electrophoresis 2001; 22:535-43. [PMID: 11258766 DOI: 10.1002/1522-2683(200102)22:3<535::aid-elps535>3.0.co;2-8] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Chiral separation of basic compounds was achieved by using 75 or 100 microm ID fused-silica capillaries packed with a vanoomycin-modified diol silica stationary phase. The capillary was firstly packed for about 12 cm with a slurry mixture composed of diolsilica (3:1) then with the vancomycin modified diol-silica (3:1) (23 cm), and finally with diol-silica (3:1) for about 2 cm. Frits were prepared by a heating wire at the two ends of the capillary; the detector window was prepared at 8.5 cm from the end of the capillary where vancomycin was not present. The influence of the mobile phase composition (pH and concentration, organic modifier type and concentration) on the velocity of the electroosmotic flow, chiral resolution and enantioselectivity was studied. Good enantiomeric resolution was achieved for atenolol, oxprenolol, propranolol, and venlafaxine using a mobile phase composition of 100 mM ammonium acetate solution (pH 6)/water/acetonitrile (5:5:90 v/v/v) while for terbutaline a mixture of 5:15:80 v/v/v provided the best separations. The use of methanol instead of acetonitrile caused a general increase of enantiomer resolution of the studied compounds together with a reduction of efficiency and detector response. However, the combination of acetonitrile and methanol in the mobile phase (as, e.g., 10% methanol and 80% acetonitrile) allowed to improve the enantiomer resolution with satisfactory detector response.
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Affiliation(s)
- C Desiderio
- Istituto di Cromatografia del CNR, Monterotondo Scalo, Roma, Italy
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36
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Chankvetadz B, Blaschke G. Enantioseparations in capillary electromigration techniques: recent developments and future trends. J Chromatogr A 2001; 906:309-63. [PMID: 11215895 DOI: 10.1016/s0021-9673(00)01124-9] [Citation(s) in RCA: 264] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This review summarizes the current status of enantioseparations using capillary electromigration techniques and gives the authors insights on the selected fundamental aspects and future trends in this field. The most recent developments in the field of chiral separations using capillary electrophoresis (CE) and capillary electrochromatography (CEC) are summarized. The status of chiral electromigration techniques is evaluated tacking into account the most recent developments in related techniques such as chiral HPLC, GC and SFC.
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Affiliation(s)
- B Chankvetadz
- University of Münster, Institute of Pharmaceutical Chemistry, Germany.
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37
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Other chiral selectors. Chromatographia 2001. [DOI: 10.1007/bf02492895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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38
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Girod M, Chankvetadze B, Okamoto Y, Blaschke G. Highly efficient enantioseparations in non-aqueous capillary electrochromatography using cellulose tris(3,5-dichlorophenylcarbamate) as chiral stationary phase. J Sep Sci 2001. [DOI: 10.1002/1615-9314(20010101)24:1<27::aid-jssc27>3.0.co;2-g] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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39
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Liu Z, Otsuka K, Terabe S. Chiral separation by open tubular capillary electrochromatography with adsorbed avidin as a stationary phase. J Sep Sci 2001. [DOI: 10.1002/1615-9314(20010101)24:1<17::aid-jssc17>3.0.co;2-i] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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40
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Pressure Supported CEC: a High-Efficiency Technique for Enantiomer Separation. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s0301-4770(01)80081-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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41
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42
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L�mmerhofer M, Svec F, Fr�chet JMJ, Lindner W. Monolithic stationary phases for enantioselective capillary electrochromatography. ACTA ACUST UNITED AC 2001. [DOI: 10.1002/1520-667x(2000)12:12<597::aid-mcs1005>3.0.co;2-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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43
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Colón LA, Maloney TD, Fermier AM. Packed Bed Columns. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s0301-4770(01)80076-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
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44
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Modes of CEC Separation. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s0301-4770(01)80075-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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45
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Abstract
Capillary electrochromatography (CEC) continues to captivate many separation scientists. A remarkable activity is apparent from the numerous publications in the literature using CEC. A review of the most recent progress in CEC is presented herein, covering an extensive fraction of the literature on CEC published from the year 1997 until the beginning of 2000. Most of the recent developments have concentrated on column technology.
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Affiliation(s)
- L A Colón
- Department of Chemistry, State University of New York at Buffalo, 14260-3000, USA.
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46
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Abstract
Enantiomer separation by electrochromatography (CEC) can be performed in three modes: (i) open-tubular capillary electrochromatography (o-CEC), in which the chiral selector is physically adsorbed coated, and thermally immobilized or covalently attached to the internal capillary wall; (ii) packed capillary electrochromatography (p-CEC), in which the capillary is either filled with chiral modified silica particles or with an achiral packing material, and a chiral selector is added to the mobile phase; and (iii) monolithic (rod)-capillary electrochromatography (rod-CEC) in which the chiral stationary phase (CSP) consists of a single piece of porous solid. We present an overview on methods and new trends in the field of electrochromatographic enantiomer separation such as CEC with either nonaqueous mobile phases or stationary phases with incorporated permanent charges, or with packing beds consisting of nonporous silica particles or particles with very small internal diameters.
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Affiliation(s)
- D Wistuba
- Institute of Organic Chemistry, University of Tübingen, Germany.
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47
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Abstract
This review summarizes recent developments in the field of chiral separations by electromigration techniques including capillary zone electrophoresis (CZE), capillary gel electrophoresis (CGE), isotachophoresis (ITP), electrokinetic chromatography (EKC), and capillary electrochromatography (CEC). This overview focuses on the development of new chiral selectors and the introduction of new techniques rather than applications of already established selectors and methods. The mechanisms of the different chiral separation principles are discussed.
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Affiliation(s)
- G Gübitz
- Institute of Pharmaceutical Chemistry, Karl-Franzens University, Graz, Austria.
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48
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Abstract
This review summarizes recent developments in the field of enantioseparations in capillary electromigration techniques using nonaqueous background electrolytes. The more established and rather intensively reviewed field of nonaqueous chiral capillary electrophoresis (NAQ-CE) is covered in less detail whereas more attention is paid to the relatively new field of nonaqueous capillary electrochromatography (NAQ-CEC).
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Affiliation(s)
- B Chankvetadze
- Institute of Pharmaceutical Chemistry, University of Münster, Germany.
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49
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Abstract
Adsorption is always considered a troublesome effect in capillary electrophoresis (CE) and capillary electrochromatography (CEC). However, the adsorption effect can also be exploited to prepare or optimize the stationary phase in CEC. Compared with the chemical synthesis of new stationary phase materials for CEC, this method is simpler and more convenient. This review is focused on CEC with physically and dynamically adsorbed stationary phases. Separation of some acidic, basic and neutral solutes as well as enantiomers in CEC with dynamically adsorbed stationary phases are presented. The theory for the migration of charged solutes and the stationary phases currently used in CEC are also briefly reviewed.
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Affiliation(s)
- H Zou
- National Chromatographic R & A Center, Dalian Institute of Chemical Physics, The Chinese Academy of Sciences.
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50
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Lämmerhofer M, Svec F, Fréchet JM. Chiral monolithic columns for enantioselective capillary electrochromatography prepared by copolymerization of a monomer with quinidine functionality. 2. Effect of chromatographic conditions on the chiral separations. Anal Chem 2000; 72:4623-8. [PMID: 11028620 DOI: 10.1021/ac000323d] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effect of chromatographic conditions on the performance of chiral monolithic poly(O-[2-(methacryloyloxy)-ethylcarbamoyl]-10,11-dihydroqui nidine-co-ethylene dimethacrylate-co-2-hydroxyethyl methacrylate) columns in the capillary electrochromatography of enantiomers has been studied. The flow velocity was found to be proportional to the pore size of the monolith and both the pH and the composition of the mobile phase. The length of both open and monolithic segments of the capillary column was found to exert a substantial effect on the run times. The use of monoliths as short as 8.5 cm and the "short-end" injection technique enabled the separations to be achieved in approximately 5 min despite the high retentitivity of the quinidine selector. Very high column efficiencies of close to 250000 plates/m and good selectivities were achieved for the separations of numerous enantiomers using the chiral monolithic capillaries with the optimized chromatographic conditions.
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Affiliation(s)
- M Lämmerhofer
- Department of Chemistry, University of California, Berkeley 94720-1460, USA
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