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  • Polymer encapsulated particles  (2)
  • Springer  (2)
  • American Physical Society (APS)
  • 1
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography ; Packed capillary columns ; Polyethylene oxide coated phases ; Polymer encapsulated particles ; Amines and acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polyethylene oxide (PEO)-based polymers with hydroxy, methoxy, and aminopropoxy terminal groups were coated on diol functionalized and hexamethyldisilazane end-capped silica particles. Proton-donor and proton-acceptor test solutes, including carboxylic acids, hydroxy-containing compounds, arylamines, and alkylamines were used to evaluate the chromatographic performances of these polymer coated particles under SFC conditions with neat CO2 as mobile phase. It was found that the particles coated with hydroxy-terminated PEO were suitable for the separation of proton-donor compounds such as hydroxy-containing compounds and carboxylic acids, and the particles coated with aminopropoxy-terminated PEO could be used for the separation of amines. That is, the proton-accepting stationary phase is suitable for the separation of proton accepting solutes, including strong basic alkylamines (pKb≈4), using neat CO2 as mobile phase, while the protondonating stationary phase is suitable for the separation of proton-donating compounds such as carboxylic acids (pKa≈4). Hydrogen bond basicity was found to be a critical factor for the chromatography of basic amines. Low volatility acidic and basic drugs were chromatographed using the new stationary phases. The stability of the PEO coated particles was determined by measuring the loss of organic carbon under SFC conditions. It was found that approximately 18 % of the coating (average molecular weight of 15,000) was washed out of the particles by supercritical CO2 after 7 h at 350 atm and 50°C
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography ; Packed capillary columns ; Liquid crystalline polysiloxane ; Polymer encapsulated particles ; Vitamins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Liquid crystal polysiloxane stationary phases were prepared by coating two different polymers on deactivated porous silica particles (10 μm diameter, 80 Å pores). Deactivation of the silica particles before coating was necessary to prepare highly efficient and inert stationary phases for supercritical fluid chromatography (SFC). Fat-soluble vitamins E, A, K1, K2, D2, and D3 were separated on these columns using neat supercritical CO2 as mobile phase. The analyses were completed within 40 min at 70 °C. The results were compared to those obtained using a capillary column packed with less ordered liquid crystalm,m-cyanobiphenyl-substituted polysiloxane coated particles. Reduced shape selectivity was observed with this cyanobiphenyl phase. The response factors of vitamins A, E, K1, K2, D2, and D3 when using the flame ionization detector (FID) were determined to be very similar.
    Type of Medium: Electronic Resource
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