Separation of olanzapine, carbamazepine and their main metabolites by capillary electrophoresis with pseudo-stationary phases

Conditions were worked out for the separation of carbamazepine, olanzapine, and their main metabolites carbamazepine 10,11-epoxide, 10-hydroxycarbamaz epine, and desmethylolanzapine. The separation was based on electrokinetica lly driven methods in the capillary format. The main difficulty in separati ng these compounds is related to their different chemical classes. Whereas the carbamazepine members are amides, and are electrically neutral, the ola nzapine members have aliphatic amino groups and are thus cationic under mos t experimental conditions. Different additives were applied as pseudo-stati onary phases to implement selectivity. Poly(diallyldimethylammonium), PDADM A, is a polycationic replaceable and soluble polymer, that interacts mainly according to the polarisability of the analyte molecules. The MEKC princip le was applied with the common SDS as micelle former. In both systems, only partial resolution of the analytes was obtained. The most favorable system consisted of a charged, oligomeric additive: full separation of all analyt es within 4 min was achieved with heptakis-6-sulfato-beta -cyclodextrin (7 mM) in 30 mM berate buffer, pH 8.5. (C) 2001 Elsevier Science B.V. All righ ts reserved.