Analysis of pharmaceuticals by microemulsion electrokinetic chromatographyin a suppressed electroosmotic flow environment

Microemulsion electrokinetic chromatography (MEEKC) in a suppressed electro osmotic Row environment has been evaluated for the separation of compounds of pharmaceutical interest. The separation medium was 0.8% (w/w) n-octane, 6.0% (w/w) sodium lauryl sulphate (SDS), 6.6% (w/w) 1-butanol, 20.0% (w/w) 2-propanol, and 66.6% (w/w) 25 mM phosphate buffer pH 2.5. The electroosmot ic flow was effectively suppressed by use of this acidic microemulsion. The separation voltage was reversed, with the anode placed at the capillary ou tlet and the negatively charged microdroplets of n-octane migrated towards the detector Several steroids benzodiazepines, antidepressants, antipsychot ic drugs, and antiepileptic drugs were effectively separated on the basis o f their different interactions with the migrating microdroplets of n-octane . The MEEKC system was briefly validated for the determination of the antid epressant citalopram in commercial tablets; quantitative data were in accor dance with the label claim (5.5% deviation) and intra-day and inter-day var iation were 1.63% RSD and 3.54% RSD, respectively.