(ENANTIO-)SEPARATION OF PHENOXY ACID HERBICIDES USING CAPILLARY ZONE ELECTROPHORESIS

Capillary zone electrophoretic (CZE) methods were developed for the se paration of phenoxy acid herbicides and related impurities (including positional isomers) originating from production processes. In addition , chiral separations of phenoxy-propionic acid herbicides were achieve d by adding a suitable cyclodextrin-type chiral selector to the electr ophoresis buffer. The selectivity of the separation can be controlled and fine-tuned by using different types of cyclodextrins. The presence of specific impurities could be confirmed after comparison of the ele ctropherograms obtained with CZE systems having different selectivitie s. The CZE method shows good precision, linearity and long-term stabil ity. The methods developed have been successfully applied to the analy sis of real production samples and the determination of their enantiop urity. Both the identification and determination of the impurities com pare with the results obtained with chromatographic methods. The CZE m ethods, however, are more flexible and simpler and will be more econom ical. The methods have potential for automated quality control assays.