STRATEGY FOR SETTING UP SINGLE-CAPILLARY ISOTACHOPHORESIS ZONE ELECTROPHORESIS

A strategy is described for the optimization of capillary zone electrophoresis (CZE) with isotachophoretic (ITP) preconcentration in a single-capillary set-up. CZE with indirect UV absorbance detection is used as a tool in setting up ITP-CZE. The electropherograms obtained with indirect detection give an immediate insight into the migration order of possible leading and terminating ions and of the analyte ions. Furthermore, information is obtained on the ionic composition of the sample matrix. The separation window in the ITP step can be chosen in such a way that a sample clean-up is achieved before zone electrophoresis is started. The described approach is applicable for setting up an ITP-CZE analysis in both the cationic and anionic modes. The usefulness of the strategy is illustrated by setting up the ITP-CZE of three cationic antimuscarinic drugs. Applying the developed strategy, combined with liquid-liquid extraction, concentrations of homatropine and scopolamine down to 100 ng/ml could easily be determined.