Organo-silica sol-gel monoliths prepared solely from 3-(methacryloyloxy)propyltrimethoxysilane (MPTMS) attracted much attention in the early 2000s due to the possibility for fast <i>in situ </i>preparation via photopolymerization. The appeal of the MPTMS monomer precursor is that it contains both, organic (methacrylate) as well as silica-based (alkoxysilane) functionalities. In acid catalyzed conditions, methoxy groups of the methoxysilane undergo simultaneous hydrolysis and polycondensation forming silanols and siloxane chains. On the other hand, methacrylate functionalities undergo thermally or UV light-initiated free-radical polymerization. Previously, we have compared chromatographic performance of thermally (TSG) and photo-polymerized sol-gel (PSG) monoliths in the reversed-phase mode in respect to column efficiency, methylene and steric selectivity, and extent of hydrogen bonding. Slightly more hydrophobic surfaces with reduced number of residual silanols and comparable steric selectivity and column efficiency (111 000 plates/m for alkylbenzenes) were found for TSG monoliths. Recently, we have explored the feasibility of single-pot approach towards preparation of C18 and fluorinated TSG monoliths by the addition of an appropriate monomer directly into a polymerization mixture. Strong affinity towards alkylbenzenes, better retention and resolution for planar and non-planar analytes were displayed on C18 columns. On the other hand, fluorinated stationary phases were shown to provide enhanced retention and selectivity towards fluorinated compounds. In conclusion, the single-pot approach proved to be viable for modifying the surface chemistry of monolithic stationary phases.

Preparation of organo-silica sol-gel monoliths using "single-pot“ approach for applications in capillary liquid chromatography

2019 Spring National Meeting

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