Enantiomers separation by nano-liquid chromatography: use of a novel sub-2 micron vancomycin silica hydride stationary phase.

A novel sub-2 micron chiral stationary phase (CSP) was prepared immobilizing vancomycin onto 1.8 m diolhydride-based silica particles. The CSP was packed into fused silica capillaries of 75 m i.d. with a length of11 cm and evaluated by means of nano-liquid chromatography (nano-LC) using model compounds of bothpharmaceutical and environmental interest (some non-steroidal anti-inflammatory drugs, -blockersand herbicides). The study of the effect of the linear velocity of the mobile phase on chromatographicefficiency showed good enantioresolutions up to a value of 5.11 at the optimal linear velocity with efficien-cies in terms of number of plates per meter in the range 51,650-68,330. The results were compared withthe ones obtained employing 5 m vancomycin modified diol-silica particles packed in capillaries of thesame i.d. For the acidic analytes the sub-2 m CSP showed better performances, the baseline chiral sepa-ration of several studied compounds occurred in an analysis time of less than 3 min. Column-to-columnpacking reproducibility (n = 3) expressed as relative standard deviation was in the range 2.2-5.8% and0.5-7.7% for retention times and peak areas, respectively.