Use of berate complexation for the separation of non-UV-absorbing calystegines by capillary electrophoresis

A capillary zone electrophoresis method was developed for the simultaneous analysis of seven closely related polyhydroxyalkaloids called calystegines. Successful results were obtained with a fused-silica capillary, 80 mM sodi um tetraborate at pH 9.2 and temperature of 50 degreesC. Detection of non-U V-absorbing calystegines was achieved through in-situ complexation with ber ate ions. To further improve method sensitivity, a capillary with a bubble cell was used and detection performed at low wavelength (191 nm). Effects o f buffer concentration, pH and temperature on migration times and efficienc y are discussed. Migration behavior of selected compounds was significantly affected by their chemical structure (i.e., number and position of hydroxy groups). Under optimized conditions, baseline separation of the selected c ompounds was achieved in less than 12 min. Precision was evaluated by measu ring repeatability and intermediate precision of migration times and correc ted peak areas. Finally, the method was applied to the qualitative analysis of calystegines in plant extracts and results were confirmed by CC-MS. (C) 2000 Elsevier Science B.V. All rights reserved.