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K Cabrera

Publications and source records attributed to K Cabrera.

5 recordsLinked to original sources
PubMed2003

Monolithic silica columns with chemically bonded beta-cyclodextrin as a stationary phase for enantiomer separations of chiral pharmaceuticals.

An enantioselective silica rod type chiral stationary phase (CSP) is presented; a novel combination of the well known enantiomer separation properties of beta-cyclodextrin and the unique properties concerning the flow behavior of silica monoliths. Two different synthesis routes are described, and it was found that the in situ modification of a plain silica rod column turned out to be the best. The chromatographic behaviour of the beta-cyclodextrin silica rod was studied and compared with a very similar commercially available beta-cyclodextrin bonded particulate material (ChiraDex). Even if the amount of beta-cyclodextrin bound to the silica rod was only about half of the amount of beta-cyclodextrin bound to ChiraDex) particles, good resolutions were achieved for a set of chiral test components like Chromakalin, Prominal, Oxazepam, Methadone and some other drugs. By taking advantage of the unique features of the silica rods relating to their flat H/u (Van Deemter) curves, fast enantiomer separations could be demonstrated.

Chromatography↗
PubMed2001

Enantiomer separation by nonaqueous and aqueous capillary electrochromatography on cyclodextrin stationary phases.

Native beta- and gamma-cyclodextrin bound to silica (ChiraDex-beta and ChiraDex-gamma) were packed into capillaries and used for enantiomer separation by capillary electrochromatography (CEC) under aqueous and nonaqueous conditions. Negatively charged analytes (dansyl-amino acids) were resolved into their enantiomers by nonaqueous CEC (NA-CEC). The addition of a small amount of water to the nonaqueous mobile phase enhanced the enantioselectivity but increased the elution time. The choice of the background electrolyte (BGE) determined the direction of the electroosmotic flow (EOF). With 2-(N-morpholino) ethanesulfonic acid (MES) or triethylammonium acetate (TEAA) as BGE an inverse EOF (anodic EOF) was observed while with phosphate a cathodic EOF was found. The apparent pH (pH*), the concentration of the BGE, and the nature of the mobile phase strongly influenced the elution time, the theoretical plate number and the chiral separation factor of racemic analytes.

Acetonitriles↗
PubMed1992

[Miliary tuberculosis as a complication of BCG immunotherapy in cancer of the bladder. Case report].

Intravesical administration of BCG may be used as an ancillary immunotherapy after endoscopic resection for cancer of the bladder. Local side effects are usually mild. Here is reported a patient who developed miliary tuberculosis after this form of therapy. Radiologic studies of the thorax and liver biopsy confirmed the diagnosis. The patient recovered after treatment with anti-tuberculosis drugs (TA-81 scheme). Epithelial trauma may be invoked as an alteration facilitating this complication. Although it develops infrequently, patients with bladder cancer treated with BCG must be monitored for this complication.

BCG Vaccine↗