Vancomycin-based chiral stationary phases for micro-column liquid chromatography

Vancomycin selectively immobilized to silica via either one of its two amin o groups has been investigated and compared with columns made from native v ancomycin. The chemical modification of vancomycin prior to immobilization involved protection of one amino group as a 9-fluorenylmethyl carbamate. Th e immobilization and the subsequent cleavage of the protecting group was pe rformed on-column. The types of compounds that can be separated with the va ncomycin chiral stationary phases resemble those separated previously by ca pillary electrophoresis and thin-layer chromatography. The protected chiral stationary phases were also investigated and in some cases very high enant ioselectivity were obtained. One example of this is a separation of thalido mide with an oc-value as high as 5.4. The soft immobilization procedure pre serves the structure of native vancomycin, in contrast to other approaches. Good repeatability and stability of the columns have also been obtained. ( C) 1999 Wiley-Liss, Inc.