Enantiomeric separation of promethazine and d,l-α-amino-β-[4-(1,2-dihydro-2-oxo-quinoline)] propionic acid drugs by capillary zone electrophoresis using albumin as chiral selectors

Abstract The enantiomeric separation of promethazine and d , l -α-amino-β-[4-(1,2-dihydro-2-oxo-quinoline)] propionic acid (AOQ) drugs using albumin as chiral selector by capillary zone electrophoresis (CZE) was developed. Several influencing factors, the capillaries pretreatment, electrolyte type, pH in background electrolyte (BGE), proteins or organic solvents as chiral additives, were optimized. Direct baseline separation of chiral promethazine was successfully achieved within 13 min by using 50 mM phosphate buffer solution of pH 7.6 which contains 50 μM bovine serum albumin (BSA) without any organic modifiers. It was found that the BSA has the ability of enantio-selectivity to promethazine only when it is in a negatively charged state. AOQ showed varied migration patterns in different coated capillaries. Baseline separation of AOQ was obtained only in polyacrylamide-coated capillary using the electrolyte of pH 7.4, 50 mM phosphate buffer solution containing 50 μM human serum albumin (HSA). Alternatively, nearly baseline separation of AOQ can be obtained in the HSA-coated capillary under the same conditions. The numbers of theoretical plates for the separation of AOQ in HSA-coated capillary and polyacrylamide-coated capillary were 23172 and 18723, respectively.