Single-step approach to beta-cyclodextrin-bonded silica as monolithic stationary phases for CEC

A novel single-step sol-gel approach for the preparation of beta-CD-bonded silica monolithic electrochromatographic columns is established. The porous silica networks were fabricated inside fused-silica capillaries using sol-gel processing of tetramethoxysilane and an organfunctional silicon alkoxide that contains beta-CD. Scanning electron micrographs and nitrogen adsorption-desorption data showed that these functional monolithic columns have double pores structures with micrometer-size co-continuous through-pores and silica skeletons with open mesopores. The beta-CD monolithic columns have successfully been applied to the separation of several neutral and negatively charged isomers by CEC. The column performance was evaluated by using positional isomers of naphthalenedisulfonic acid as model compounds. A plate height of less than 10 mum for the first eluted isomer of naphthalenedisulfonic acid was obtained at an optimal flow rate (0.47 mm/s) of the mobile phase. Moreover, the columns have been proved to be stable for more than 100 runs during 3 months period and show reasonable column reproducibility.