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SCIENTIFIC CURRICULUM VITAE SURNAME: Castells PROJECT TITLE. "STUDY OF CELLULOSE 3,5-DIMETHYLPHENYLCARBAMATE COATED ZIRCONIA FOR CHIRAL HIGH PERFORMANCE LIQUID CHROMATOGRAPHY" Cellulose and amylose carbamates coated onto pre-silanized silica supports are widely used as materials for the chiral separation of many enantiomeric mixtures in both normal- and reversed-phase HPLC. Several studies have demonstrated that the coating conditions have a strong influence on the chiral recognition ability of the polymer. These conditions include the coating solvent, pore diameter of the silica particles and polymer content, but in general, the results are solute-dependent and no systematic conclusions have been drawn. Furthermore, although high separation factors between the enantiomers is the main objective, the resolution of the two components also depends on the column efficiency. Higher efficiencies allow a reduction in column length and thus solvent consumption. To our knowledge there is no systematic studies on this topic. In the present study, we explore porous zirconia as a support for cellulose tris(3,5-dimethylphenylcarbamate). We coated pre-sintered 2.5 mm zirconia particles, having 300 Å average pore diameter. In order to improve the efficiency of the resulting stationary phase, we studied several coating conditions. The optimized procedure implies the periodic addition of small aliquots of polymer dissolved in THF at about 0.05 ml/min. The nitrogen adsorption (BET) results demonstrated practically no pore blockage after coating the substrate with polymer at less than 3% (w/w). On the other hand, we found, as previously reported, that the chromatographic selectivity increases as more polymer is coated on the support up to a threshold level of about 4% (w/w). Moreover, the resolution of some chiral mixtures in a 5-cm column packed with 4%(w/w) chiral polymer under the normal phase mode is comparable to that reached in a typical 25-cm cellulose carbamate coated silica column. The stability of the column was also assessed under high flow-rates. No changes in separation factors neither column backpressure were detected after 4800 column volumes at 4 ml/min.
1. ACADEMIC QUALIFICATIONS
2. DOCTORAL THESIS
3. FELLOWSHIPS
4. PUBLICATIONS "Analisis of isomeric cresols by gas chromatography". "Thermodynamics of tetra-n-octyltin + hydrocarbon systems by gas
chromatography". "Thermodynamics of tri-n-octyltin chloride + hydrocarbon systems
by gas chromatography". "Evaluation of theoretical models of non-electrolyte solutions in
the prediction of Kováts retention indices of branched alkanes in
alkane stationary phases". "Influence of differences between sample and mobile phase viscosities
on the shape of chromatographic elution profiles" "Peak distortion in reversed phase liquid chromatography (RPLC)
as a consequence of viscosity differences between sample solvent and mobile
phase". "Cellulose tris(3,5-dimethylphenylcarbamate) coated zirconia as
a chiral stationary phase for HPLC". "Comparative study of semi-theoretical models for predicting infinite
dilution activity coefficients of alkanes" 12. "Infinite dilution activity coefficients of eleven alkanes in
sixty seven organic solvents at 298.15K measured by headspace gas chromatography.
Part I" "Accuracy and precision of infinite dilution activity coefficients
of alkanes in organic solvents measured by headspace gas chromatography.
Part II" "Influence of temperature on chiral high-performance liquid chromatographic
separations on cellulose 3,5-dimethylphenylcarbamate coated zirconia"
5. ACADEMIC EXPERIENCE AND PRESENT POSITION
Last updated: 6/30/99 |
