Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7613761 | Journal of Chromatography A | 2014 | 10 Pages |
Abstract
Porous polymer monolithic columns are prepared from a variety of monomers and cross-linkers and can be customized to exhibit different selectivities for separate analyte classes. The composition of the monolith can be precisely controlled by selecting different monomers and or cross-linker ratios. In this work monoliths exhibiting both fluorous and hydrophobic character were prepared using butyl methacrylate and its fluorous analogue (monomer) and 1,3-butanediol diacrylate and its fluorous analogue (cross-linker) in different ratios. The selectivity of the monoliths was probed using capillary electrochromatography with several fluorous and alkyl benzene analytes. Hydrophobic stationary phases exhibited greater methylene selectivity (αâCH2â) while those with increasing fluorous character show enhanced pefluoromethylene selectivity (αâCF2â). The Gibbs free energy change associated with the sorption of the analytes on each stationary phase composition can be calculated from migration times (i.e. capacity factor) for the addition of an individual âCF2â or âCH2â moiety. Furthermore, the Gibbs free energy change associated with a single âCF2â or âCH2â moiety (analyte) interacting with an individual âCF2â or âCH2â (stationary phase) can also be estimated by plotting fluorous column composition against ÎGâCH2ââ¡orâCF2â0. Furthermore ÎGâCH2â0 and ÎGâCF2â0 can be plotted versus H2O percentage in mobile phase, and a new concept, hypothetical water percentage (HWP) is proposed to evaluate the hydrophobicity/fluorophilicity of a stationary phase.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Zhenpo Xu, Richard D. Oleschuk,