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  • 1
    Electronic Resource
    Electronic Resource
    Enantiomeric separation of chiral components reported to be in coffee, tea, or cocoa (1993)
    s.l. : American Chemical Society
    Journal of agricultural and food chemistry 41 (1993), S. 1684-1689 
    Details
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jf00034a031
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  • 2
    Electronic Resource
    Electronic Resource
    Capillary Zone Electrophoresis Study of Naphthylethylcarbamoylated .beta.-Cyclodextrins (1995)
    s.l. : American Chemical Society
    Analytical chemistry 67 (1995), S. 19-25 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00097a005
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  • 3
    Electronic Resource
    Electronic Resource
    Derivatized cyclodextrins for normal-phase liquid chromatographic separation of enantiomers (1990)
    s.l. : American Chemical Society
    Analytical chemistry 62 (1990), S. 1610-1615 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00214a012
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  • 4
    Electronic Resource
    Electronic Resource
    Heparin: A Chiral Mobile-Phase Additive for Capillary Zone Electrophoresis (1994)
    s.l. : American Chemical Society
    Analytical chemistry 66 (1994), S. 3054-3059 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00091a011
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  • 5
    Electronic Resource
    Electronic Resource
    Optical enrichment of dansyl-rac-amino acids by formation of crystalline inclusion complexes with cyclodextrins (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 137-141 
    Details
    ISSN: 0899-0042
    Keywords: resolution by crystallization ; racemic mixture ; dansyl-D-leucine ; dansyl-L-leucine ; dansyl-D-norleucine ; dansyl-L-norleucine ; dansyl-D-phenylalanine ; dansyl-L-phenylalanine ; β-cyclodextrin ; γ-cyclodextrin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optical enrichment from racemic dansyl-leucine, dansyl-norleucine, and dansyl-phenylalanine with both β- and γ-cyclodextrins in water is reported. Initial crystallization yielded the dansyl-L-leucine isomer complexed in excess with β-cyclodextrin with an optical purity of 62-78% depending on experimental conditions. The optical purities obtained for L-norleucine and L-phenylalanine were 71 and 64%, respectively. The optical purity can be increased with continued recrystallization. The dansyl-D-leucine isomer was obtained in the mother liquor with an optical purity of 54-93% depending on experimental conditions. The optical purities obtained for D-norleucine and D-phenylalanine were 72 and 58%. The optical purity of the isomer depended on the molar ratio of host:guest and the pH value of the solution. Optimum enrichment of both enantiomers was achieved with host:guest ratios of 2 : 1 and 3 : 1. Although maximum crystalline yield of the dansyl-leucine/CD inclusion complex was obtained at a pH of 3.5, optical purity of both enantiomers was less than that obtained at other pHs. The influence of the molar ratio of host:guest and the pH value of the solution are discussed. This method is suitable for large-scale enantiomeric separations.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010207
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  • 6
    Electronic Resource
    Electronic Resource
    Sulfated cyclodextrins for the chiral separations of catecholamines and related compounds in the reversed electrophoretic polarity mode (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 316-324 
    Details
    ISSN: 0899-0042
    Keywords: sulfated cyclodextrin ; catecholamine ; chiral ; CZE ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The utility of negatively charged sulfated cyclodextrins (SCD) as chiral additives (CA) in capillary electrophoresis (CE) was studied in the chiral resolution of several compounds of pharmaceutical interest, including catecholamines such as norepinephrine, epinephrine, DOPA and their precursors, phenylalanine, and tyrosine. Experiments were conducted using 10 mM sodium phosphate monobasic solution and 2% SCD adjusted to pH 3.2 with phosphoric acid. Chiral recognition mechanisms were explored using structurally related analytes including basic, acidic, and neutral compounds as well as 3,5-dinitrobenzoyl phenylglycine, phenylalanine, and homophenylalanine. The advantage of the reversed electrophoretic polarity mode for the enantioresolution of these compounds is also discussed. © 1996 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    Application of heparin to chiral separations of antihistamines by capillary electrophoresis (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2119-2123 
    Details
    ISSN: 0173-0835
    Keywords: Chiral separations ; Antihistamines ; Heparin ; Capillary electrophoresis ; Enantiomers ; Capillary zone electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A study of the chiral separations of antihistamines, including pheniramine, chlorpheniramine, brompheniramine, carbinoxamine and doxylamine in capillary electrophoresis (CE) was accomplished using heparin as a chiral additive (CA) and phosphate buffer as the background electrolyte. Several factors were shown to affect both the selectivity and the migration time, including concentration of heparin, concentration of buffer, and the pH. A dual mechanism involving both inclusion complexation and ionic interactions with heparin is thought to be responsible for the chiral recognition. In the pH range of 2.6-3.5 and reversed polarity, baseline resolutions were obtained using a wide range of buffer and heparin concentrations. Typically, chiral resolution was obtained within 50 min.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191213
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  • 8
    Electronic Resource
    Electronic Resource
    Charged chelate - capillary electrophoresis of endogenous corticosteroids (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 3045-3051 
    Details
    ISSN: 0173-0835
    Keywords: Borate ; Charged chelate ; Corticosteroids ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Separation of endogenous 17- or 18-hydroxylated corticosteroids (of the 21-hydroxylated 4-pregnen series) as charged chelates in capillary electrophoresis with borate as the ligand is demonstrated. Aldosterone, 18-hydroxycorticosterone, 18-hydroxy-11-deoxycorticosterone, cortisone, cortisol, and 11-deoxycortisol are separated and resolved by 400 mM borate buffer at pH 9.0. Separation characteristics of the corticosteroid charged chelates were examined by varying the separation buffer borate concentration, pH, ionic strength, and addition of organic modifiers. The borate ion [B(OH)4]- is identified as the critical buffer component. Corticosteroids chelate borate with proximal hydroxyls composed of either the 17- or 18-hydroxyl in combination with the 21-position hydroxyl. Corticosteroid/borate chelation as indicated by CE results is corroborated with 11B-nuclear magnetic resonance (11B-NMR) sprectra. Chelation is a readily reversible process, with the strength of the resultant chelate, as opposed to the charge-to-mass ratio, predominantly determining analyte mobility in charged chelate - capillary electrophoresis (CC-CE).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191642
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  • 9
    Electronic Resource
    Electronic Resource
    Interactions of chiral molecules with an (r)-n-(3,5-dinitrobenzoyl) phenylglycine HPLC stationary phase (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 38-42 
    Details
    ISSN: 0899-0042
    Keywords: column liquid chromatography ; chiral stationary phases ; derivatization effects ; chiral recognition mechanism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Forty different chiral molecules were studied by liquid chromatography with a Pirkle-type, (R)-N-(3,5-dinitrobenzoyl) phenylglycine (DNBPG), chiral stationary phase column. The dramatic effect of a small molecular change on chiral recognition was demonstrated using DL-amino acid derivatives. The inductive effect on chiral recognition was also studied using trifluoro-, trichloro-, dichloro-, monochloroacetyl, and acetyl derivatives of four different chiral amines. The study of the enantiomer separation of 11 different crown ethers of 2,2′-binaphthyldiyl showed that the rigidity of the chiral center can be an additional parameter in chiral recognition for the DNBPG phase but not for a β-cyclodextrin bonded chiral phase. It is apparent from this study that steric effects, inductive effects, and molecular rigidity play important roles in chiral recognition with DNBPG chiral stationary phases.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020106
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  • 10
    Electronic Resource
    Electronic Resource
    Determination of the enantiomeric purity of scopolamine isolated from plant extract using achiral/chiral coupled column chromatography (1991)
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 5 (1991), S. 3-7 
    Details
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The optical purity of scopolamine derived from Datura sanguinea was determined using coupled column chromatography. A C18 column was used to separate scopolamine from the additional alkaloids and other biological material present in the vegetal extract. The C18 column was coupled through a six-port switching valve to two β-cyclodextrin columns in series which were used to resolve the scopolamine enantiomers. A single acetylated β-cyclodextrin column gives equivalent results to the native cyclodextrin columns because of slightly higher enantioselectivity for scopolamine. A multistep extraction procedure is used to isolate scopolamine from the vegetal material. 4-6% of the scopolamine in the final extract was found to be the d enantiomer. Sample extracts as well as commercial scopolamine hydrobromide were treated under various conditions commonly encountered during typical commercial extraction procedures and analyzed in order to determine if the d enantiomer was present in the original material or if it was produced during the extraction process and, if so, determine which step and conditions contribute to acemization. Both the salt and the extract were found to be susceptible to racemization under basic conditions (≥pH 9) although the extract appeared to be more susceptible than the salt. Tropic acid formed from the hydrolysis of scopolamine seemed to be completely racemized even though the remaining scopolamine was only partially racemized. Within experimental error, no d enantiomer was found in the original fresh plant material.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bmc.1130050103
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