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Silica‐based monolithic columns with mixed‐mode reversed‐phase/weak anion‐exchange selectivity principle for high‐performance liquid chromatography
Author(s) -
Nogueira Raquel,
Lubda Dieter,
Leitner Alexander,
Bicker Wolfgang,
Maier Norbert M.,
Lämmerhofer Michael,
Lindner Wolfgang
Publication year - 2006
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.200500395
Subject(s) - monolith , monolithic hplc column , wax , chromatography , selectivity , chemistry , high performance liquid chromatography , ion exchange , hydrophilic interaction chromatography , reversed phase chromatography , analytical chemistry (journal) , ion , catalysis , organic chemistry
This article describes the synthesis, chromatographic characterization, and performance evaluation of analytical (100×4.6 mm id) and semipreparative (100×10 mm id) monolithic silica columns with mixed‐mode RP/weak anion‐exchange (RP/WAX) surface modification. The monolithic RP/WAX columns were obtained by immobilization of N ‐(10‐undecenoyl)‐3‐aminoquinuclidine onto thiol‐modified monolithic silica columns (Chromolith®) by a radical addition reaction. Their chromatographic characterization by Engelhardt and Tanaka tests revealed slightly lower hydrophobic selectivities than C‐8 phases, as well as higher polarity and also improved shape selectivity than RP‐18e silica rods. The surface modification enabled separation by both RP and anion‐exchange chromatography principles, and thus showed complementary selectivities to the RP‐18e monoliths. The mixed‐mode monoliths have been tested for the separation of peptides and turned out to be particularly useful for hydrophilic acidic peptides, which are usually insufficiently retained on RP‐18e monolithic columns. Compared to a corresponding particulate RP/WAX column (5 μm, 10 nm pore diameter), the analytical RP/WAX monolith caused lower system pressure drops and showed, as expected, higher efficiency ( e. g. by a factor of about 2.5 lower C ‐term for a tetrapeptide). The upscaling from the analytical to semipreparative column dimension was also successful.