Surface initiated molecularly imprinted polymer films: a new approach in chiral capillary electrochromatography

A new generation of imprinted composite particles was tested as capillary electrochromatography stationary phase. Silica particles characterised by a well defined particle size (10 mum diameter), shape and pore system (1000 Angstrom) were modified with an azoinitiator and subsequently used to graft molecularly imprinted polymers targeted to bind L-phenylalanine anilide. Fused silica capillaries were packed over a length corresponding to 8 cm, using a pneumatic amplification pump, and the stationary phase thus obtained was tested with respect to its electrochromatographic performance. The electroendosmotic flow mobility was evaluated with respect to both the different content of polymer on the silica particle surface and different operating pH values. The dependence of various parameters, namely the analyte concentration, the polymer layer thickness and the pH of the mobile phase on the enantioselectivity was investigated. These CEC capillaries showed enantioselectivity comparable with that showed in LC, and exhibited improved performance in terms of plate number N-1 ( similar to 13 000), selectivity alpha ( similar to 1.5), analysis time ( < 3 min), inter-intraday and intercapillary reproducibility. We expect this approach to result in a new generation of robust, tailor-made chiral or affinity stationary phases for CEC.