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Preinerstorfer, B; Lubda, D; Lindner, W; Lämmerhofer, M.
(2006): Monolithic silica-based capillary column with strong chiral cation-exchange type surface modification for enantioselective non-aqueous capillary electrochromatography.
J Chromatogr A. 2006; 1106(1-2):94-105 FullText FullText_BOKU

Abstract:
A silica-based monolithic stationary phase prepared by the sol-gel process in a 100 mu m I.D. fused-silica (FS) capillary has been modified chemically with 3-mercaptopropyl trimethoxysilane followed by immobilization of a strong cation-exchange (SCX) type chiral selector, (S)-N-(4-allyloxy-3,5-dichlorobenzoyl)-2-amino-3,3-dimethylbutane phosphonic acid, by radical addition reaction onto the reactive sulfhydryl surface. After a fine-tuning of the mobile phase composition, the enantioselective capillary column was evaluated for the separation of various chiral basic drugs by enantioselective non-aqueous capillary electrochromatography (CEC), in comparison to capillary column analogs packed with 3.5 mu m silica particles having attached the same selector. The performance of the monolithic silica column was further compared to corresponding polymethacrylate-based organic polymer monoliths. The study indicated that strong counter-ions such as 2-aminobutanol or N,N,N ',N ',-tetramethylethylenedianiine are needed - although they reduce the electroosmotic flow velocity and separation factors in comparison to less efficient counter-ions, in order to allow the elution of the oppositely charged solutes in the ion-exchange retention mode within reasonable run time and as sharp zones. In contrast, weak counter-ions such as N,N-diisopropylethylamine (Huenig base) provided stronger electroosmotic flow and much better separation factors, but relatively poor peak efficiencies. Overall, with the chemically functionalized monolithic silica column the high quality separations of packed column analogs could be approximated, with regards to both separation factors and peak performances. On the other hand, the monolithic capillary column certainly outperformed the packed column in terms of system robustness under capillary electrochromatography conditions and showed excellent column longevity. The enantioselective strong cation-exchange-type monoiithic silica column performed also well in comparison to the organic polymer monolith. (c) 2005 Elsevier B.V. All rights reserved.
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Find related publications in this database (using NML MeSH Indexing)
Cation Exchange Resins -
Chromatography, Ion Exchange - methods
Chromatography, Micellar Electrokinetic Capillary - methods
Microscopy, Electron, Scanning -
Silicon Dioxide - chemistry
Stereoisomerism -
Surface Properties -

Find related publications in this database (Keywords)
silica monolith
sol-gel process
in situ (in-column) derivatization
chiral stationary phase
strong cation-exchanger
enantioselective capillary electrochromatography
chiral aminophosphonic acid
chiral basic drugs


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