Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1995-1999  (3)
  • 1990-1994  (2)
  • Column liquid chromatography  (4)
  • Polymer solution
  • 1
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantiomer separation ; Chiral ovomucoid column ; Diltiazem hydrochloride ; Clentiazem maleate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A direct HPLC separation method was developed for the determination of the enantiomers of racemic precursors to diltiazem (I) and its 8-chloro derivatives (II). The enantiomers were successfully separated on a chiral ovomucoid column using an aqueous-organic mobile phase (reversed-phase HPLC). The influence of the organic modifier and buffer pH on the retention and enantioselectivity was investigated. The chromatographic conditions chosen for the separation permitted complete resolution of the enantiomers of both the acid (Ib and IIb) and methyl ester precursors (Ia and IIa) within 20 min. The influence of sample load on retention times, theoretical plates numbers, peak heights and peak areas was also investigated. The peak areas showed a good linearity over the concentration range examined, although all the others were influenced significantly by the sample size. An optical antipode of the intermediate to be determined could be detected by the area-percentage method down to ca. 0.1%, together with the determination of its precursor, including its optical purity.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantiomer separation ; Denopamine ; Derivatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A reversed-phase high-performance liquid chromatographic (HPLC) method was developed to determine the optical purity of denopamine, which is a new cardiotonic agent having an asymmetric carbon in a molecule. The enantiomers were converted to diastereomeric thiourea derivatives using 2,3,4,6-Tetra-O-acetyl-β-D-glucopyranosyl isothiocyanate (GITC) reagent. Separation of the enantiomers of denopamine as diastereomers was successfully achieved by reversed-phase HPLC within 10 min using an ODS column and UV detection. Derivatization of denopamine proceeded rapidly under the alkaline conditions and the ambient temperature. This method was applied to the determination of the optical purity of denopamine drug substances and those in tablets. The favorable UV absorption of the derivatives enabled the optical antipode to be determined down to the 0.2% level.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Capillary electrophoresis ; Enantiomer separation ; Trimetoquinol ; Denopamine ; Timepidium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two methods for the direct separation of the enantiomers of trimetoquinol hydrochloride, denopamine and timepidium bromide were investigated, namely capillary zone electrophoresis (CZE) using cyclodextrins (CDs) (CD-CZE) and high-performance liquid chromatography (HPLC) using chiral stationary phases (CSPs). By CZE, separation of the enantiomers of trimetoquinol was successfully achieved when using β-cyclodextrin (β-CD), heptakis(2,6-di-0-methyl)-β-cyclodextrin (DM-β-CD) and β-CD polymer, but direct HPLC separation of the enantiomers was not successful. The enantiomers of denopamine were successfully separated by both CZE, employing DM-β-CD under acidic conditions, and HPLC, with cyclodextrin immobilized CSPs (CD-CSPs). Timepidium bromide, which is a racemic drug, was successfully enantioseparated by both CD-CZE and HPLC with CD-CSPs. The CD-CZE mode was selected as the optical purity testing method for trimetoquinol and denopamine because of the superiority of capillary electrophoretic (CE) techniques. Method validation results obtained clearly show that the CE method would be useful as an quality control method for assessing the optical purity of the drugs.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 48 (1998), S. 569-575 
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Oligonucleotides ; Dextran ; Polymer solution ; Purity testing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Capillary gel electrophoresis (CGE) has been recognized as an effective method for the analysis of oligonucleotides. CGE using polymer solutions is especially useful and effective compared with that using crosslinked gels, because of easy change of media. Replacement of media leads to the reproducible separation of analytes. We have investigated CGE analysis of oligonucleotides of less than 20 bases employing various kinds of polymers. Polyacrylamide, dextrin, dextran, pullakin, and poly(ethylene glycol) were used as sieving matrixes at concentrations of 0–30 %. Polydeoxythymidylic acids [p(dT)11–20] were used as a test sample. These small oligonucleotides were successfully resolved on the basis of their base number by CGE using some of these polymer solutions. In particular, dextran was found to be effective and baseline separation was observed when a 30 % dextran solution was employed. Some validations such as linearity and reproducibility were also established and this method was found to be an adequate quality control method for small oligonucleotides. Finally, CGE using a 30 % dextran solution was successfully applied to impurity profiling of some synthetic oligonucleotides.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral stationary phases ; Crown ether derivatives ; Amino compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The enantiomers of primary amino compounds have previously been resolved on a chiral stationary phase (CSP) CSP-18C6I, prepared by immobilizing (+)-18-crown-6 tetracarboxylic acid. In this study related chiral stationary phases were prepared in an effort to broaden the scope of CSP18C6I. CSP-18C6II, synthesized to investigate the effect of spacer length, resolved the enantiomers of 2-amino-1,2-diphenylethanol and 1-(1-naphthyl)ethylamine (1-NEA) (hydrophobic amino compounds) with the largerk values and smaller α values than on CSP-18C6I, probably because of the greater hydrophobicity of CSP-18C6II. Use of CSP-18C6III, synthesized by modification of carboxylic acid functionality of CSP-18C6II by introduction of another chiral moiety,S-1-NEA, resulted in larger α values for 2-amino-1-phenylethanol and 2-amino-1-phenylpropanol than on CSP-18C6II, but the enantiomers of 1-NEA were not resolved, because of steric hindrance between 1-NEA and the chiral moiety. The amide derivativeN-3,5-dinitrobenzoyl-1-(α-naphthyl)ethylamine (DNN) as π-acceptor (3,5-dinitrobenzoyl function) or π-donor (naphthylethylamide function), and no primary amino functionality, was resolved on CSP-18C6III. The mechanism of separation of the enantiomers of DNN was assumed to be the π−π interaction between the 3,5-dinitrobenzoyl function (π-acceptor) of DNN and theS-1-NEA moiety (π-donor) of CSP-18C6III.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...