Enantiomeric separation by capillary electrochromatography - I. Chiral separation of dansyl amino acids and organochlorine pesticides on a diol-silica dynamically coated with hydroxypropyl-beta-cyclodextrin

In this work, a commercially available diol-silica stationary phase was con verted in situ to a chiral stationary phase by dynamically coating it with hydroxypropyl-beta-cyclodextrin (HP-beta-CD). This stationary phase was sho wn useful for the capillary electrochromatography (CEC) separation of neutr al and anionic enantiomers such as some organochlorine pesticides and dansy l amino acids, respectively. The inclusion of HP-beta-CD in the mobile phas e to produce the in situ chiral stationary phase allowed the rapid separati on of the anionic dansyl amino acid enantiomers at relatively low electroos motic flow (EOF). The formation of host-guest complexes between the dansyl amino acids and the neutral HP-beta-CD in the mobile phase lowered the actu al charge-to-mass ratios of the anionic solutes, thus speeding up their tra nsport by the EOF across the packed capillary column. Several parameters af fecting enantioseparation were investigated, including the concentration of HP-beta-CD, ionic strength, pH, and organic modifier content of the mobile phase.