Tuning preparation conditions towards optimized separation performance of thermally polymerized organo-silica monolithic columns in capillary liquid chromatography.

Tuning of preparation conditions, such as variations in the amount of a porogen, concentration of an aqueous acid catalyst, and adjustment in polymerization temperature and time, towards optimized chromatographic performance of thermally polymerized monolithic capillaries prepared from 3-(methacryloyloxy)propyltrimethoxysilane has been carried out. Performance of capillary columns in reversed-phase liquid chromatography was assessed utilizing various sets of solutes. Results describing hydrophobicity, steric selectivity, and extent of hydrogen bonding enabled comparison of performance of hybrid monolithic columns prepared under thermal (TSG) and photopolymerized (PSG) conditions.

Photopolymerized organo-silica hybrid monolithic columns: characterization of their performance in capillary liquid chromatography.

Porous hybrid organo-silica monoliths have been prepared inside pretreated 100 μm id UV transparent fused-silica capillaries using simultaneous sol-gel transition and polymerization of 3-(methacryloyloxy)propyl trimethoxysilane in the presence of toluene as a porogen. The sol-gel reaction was catalyzed by hydrochloric acid while various photoinitiators including azobisisobutyronitrile, 2,2-dimethoxy-2-phenylacetophenone, and Irgacure 819 were used for the photopolymerization carried out under irradiation with UV light at a wavelength of 254 or 365 nm. The chromatographic performance of photopolymerized monolithic columns in RP liquid chromatographic mode was assessed with respect to the following metrics: column efficiency, methylene and steric selectivity, effect of silanol groups, van Deemter plot, permeability, and pore size distribution.