Separation of diastereomeric derivatives of enantiomers by capillary zone electrophoresis with a polymer network: Use of polyvinylpyrrolidone as buffer additive

Diastereomeric derivatives of D- and L-tryptophan obtained by reaction with (+)-diacetyl-L-tartaric anhydride were separated using capillary zone electrophoresis with polyvinylpyrrolidone as polymeric additive to the separation buffer. This additive is able to undergo hydrophobic as well as dipolar interactions with the sample components and in this way influences the effective mobility of the analytes. As this influence is of different strength for the two diastereomers, the selectivity for these separands is enhanced. The application of such physical networks as a kind of 'pseudophase' is of general significance as this method mirrors reversed-phase chromatography using aqueous mobile phases.