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Towards a microchip‐based chromatographic platform. Part 1: Evaluation of sol‐gel phases for capillary electrochromatography
Author(s) -
Breadmore Michael C.,
Shrinivasan Sushil,
Wolfe Kelley A.,
Power Mary E.,
Ferrance Jerome P.,
Hosticka Bouvard,
Norris Pamela M.,
Landers James P.
Publication year - 2002
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(200210)23:20<3487::aid-elps3487>3.0.co;2-5
Subject(s) - capillary electrochromatography , monolith , monolithic hplc column , electrochromatography , ethylene oxide , polymer , electrolyte , materials science , sol gel , chromatography , cationic polymerization , mesoporous material , chemical engineering , ion exchange , polydimethylsiloxane , chemistry , capillary electrophoresis , ion , high performance liquid chromatography , polymer chemistry , nanotechnology , copolymer , organic chemistry , catalysis , electrode , engineering , composite material
Silica monolithic columns suitable for implementation on microchips have been evaluated by ion‐exchange capillary electrochromatography. Two different silica monoliths were created from the alkyl silane, tetramethyl orthosilicate (TMOS), by introducing a water‐soluble organic polymer, poly(ethylene oxide) (PEO), with varying molecular weights into the prehydrolyzed sol. Silica monoliths created using 10 kDa PEO were found to have a much more closed gel structure with a smaller percentage of pores in the νm size range than gels created using 100 kDa PEO. Additionally, the size of the mesopores in the 100 kDa PEO monolith was 5 nm, while those in the 10 kDa PEO gel were only 3 nm. This resulted in a strong dependence of the electroosmotic flow (EOF) on the ionic strength of the background electrolyte, with substantial pore flow through the nm size pores observed in the 10 kDa PEO gel. The chromatographic performance of the monolithic columns was evaluated by ion‐exchange electrochromatography, with ion‐exchange sites introduced via dynamic coating with the cationic polymer, poly(diallyldimethylammonium chloride) (PDDAC). Separating a mixture of inorganic anions, the 10 kDa PEO monolithic columns showed a higher effective capacity than the 100 kDa PEO column.