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  • Supercritical fluid chromatography  (2)
  • Direct chiral resolution  (1)
  • 1
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Experimental design ; Direct chiral resolution ; Omeprazole ; Hydroxy-omeprazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A strategy for the optimisation of direct chiral separation of omeprazole and a metabolite, hydroxi-omeprazole, in reversed phase liquid chromatography is described. A factorial design was used, where mobile phase pH, concentration of a mobile phase modifier, ionic strength and column temperature were tested as the variables and enantioselective retention, column efficiency and asymmetry factor as the responses. The experimental results were evaluated with multivariate analyses, which demonstrated that the column temperature and content of mobile phase acetonitrile were by far the most important variables. The enantiomers of omeprazole and one of its metabolites were baseline resolved within 15 minutes. The optimised chromatographic system was used for a separation of the enantiomers of omeprazole and its main metabolite in a patient plasma sample.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 49 (1999), S. 327-332 
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography ; Semi-preparative chromatography ; Peak compression effect ; Dihydropyridine drug
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Peak compression of a dihydropyridine drug, clevidipine, is obtained in both analytical and semi-preparative scale supercritical fluid chromatography, resulting in extremely high apparent efficiencies. The observed effect, when utilising a carbon dioxide/2-propanol mobile phase with a bare silica stationary phase, is achieved when the retention of the clevidipine peak is controlled to coalesce with a system peak, generated as a result of having water in the sample. Apparent efficiencies of 350,000 and 170,000 plates meter−1 were obtained when 0.25 and 0.5 mg, respectively, are directly injected to a 200×4.6 mm ID 5 μm Hypersil silica packed column. The effect was extended to a semi-preparative system where apparent efficiencies in the region of 2,000,000 plates meter−1 were observed when 0.3 mg of a clevidipine sample containing 80% water was injected to a 250×10 mm I.D. column containing 5-μm Hypersil silica particles.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography ; Peak compression ; Chemometrics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In this paper chemometrics have been used to study and characterize peak compression phenomena in packed column SFC. A carbon dioxide/2-methyl-1-propanol mobile phase was used in the experimental design (modifier concentration, temperature and pressure) and modelling part of the investigation. A cubic interaction term was needed in the model to obtain a reasonable fit, suggesting that all three parameters are of significance in terms of controlling peak compression. At the optimum conditions derived from the model a narrow peak was obtained as predicted.
    Type of Medium: Electronic Resource
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