Improved separation of diastereomeric derivatives of enantiomers by a physical network of linear polyvinylpyrrolidone applied as pseudophase in capillary zone electrophoresis.

Diastereomeric analytes were separated using capillary zone electrophoresis with polyvinylpyrrolidone as polymeric additive to the buffer solution. As test substances derivatives of D- and L- alpha-amino and alpha-hydroxy acids formed by reaction with (+)-O,O'-diacetyl- and (+)-O,O'-dibenzoyl-L-tartaric anhydride, respectively, were used. The physical network formed by the linear polymer is supposed to act as a kind of pseudophase. It was found that the network affects the mobility of diastereomeric compounds to a different extent, enhancing the selectivity of the system. In nearly all cases of aromatic acids the diastereomer carrying the D-amino acid was more strongly retained than the L-isomer, as opposed to the situation with aliphatic acids.