CHOICE OF CAPILLARY ELECTROPHORESIS SYSTEMS FOR THE IMPURITY PROFILING OF DRUGS

In order to develop a strategy for the impurity profiling of drugs, th e possibilities of some capillary electrophoresis systems were investi gated. A mixture containing a drug and some of its possible impurities has been used as a model problem. The test compounds were investigate d by capillary zone electrophoresis (CZE) and by micellar electrokinet ic chromatography (MEKC). The pH of the CZE buffer was varied; but the two stereoisomers could not be separated. Moreover, CZE is not suitab le for neutral compounds. In MEKC, two different types of surfactants, sodium dodecyl sulphate (SDS) and cetyltrimethylammonium bromide (CTA B), have been used and the effect of type and concentration modifier o n the separation and the elution window was studied. In the SDS system , both the resolution and the elution window could be increased consid erably by the addition of modifier. The use of two MEKC systems of dif ferent selectivity seems to be a combination with high potential for t he impurity profiling of drugs. (C) 1998 Elsevier Science B.V. All rig hts reserved.