Performance evaluation of thick film open tubular silica capillary by reversed phase liquid chromatography

The unquestioned potential of open tubular column design for miniaturized liquid chromatography systems has been assessed recently. Instrument limitation and insufficient mass loadability of the columns, however, have prevented experimental breakthrough in this field, the latter requiring new methods for the deposition of thick films as the stationary phase. In this work, a previously proposed synthesis strategy has been applied for the preparation of a C8 modified 15 μm inner diameter variant of 3 m length, providing a silica porous layer with a thickness of approximately 500 nm. The capillary column has been evaluated in terms of usability, permeability and chromatographic efficiency in reversed phase mode. Data was compared to both a monolithic and a particulate, commercially available C18 capillary column. High theoretical plate numbers have been generated in a test mixture separation composed of small molecules and the applicability of this new type of column was demonstrated by two reversed phase applications.

► Monolith formation in capillary confined spaces was applied to the synthesis of a silica thick film.
► Sample showed very high permeability compared to reference commercial columns.
► Connection optimization with standard LC instrumentation was discussed.
► Performance evaluation in RP mode was carried out with a simple test mixture.
► Applicability was demonstrated by two RP mode applications.