MICROEMULSION ELECTROKINETIC CHROMATOGRAPHY WITH DIFFERENT ORGANIC MODIFIERS - SEPARATION OF WATER-SOLUBLE AND LIPID-SOLUBLE VITAMINS

Microemulsions prepared by using either sodium dodecyl sulfate (SDS) o r trimethyltetradecylammonium bromide (TTAB) were tested with regard t o the migration time, selectivity and number of theoretical plates usi ng a set of both water-soluble and lipid-soluble vitamins. While in th e separations where SDS was used as the surface-active agent for micro emulsion preparation, better resolutions were obtained with both hydro philic and lipophilic vitamins, with TTAB the best separations were ob tained with the micelle-forming reagent only or with diethyl ether as the microemulsion-forming component. In the SDS-based separations nico tinic acid was moving with the same velocity (relative to the endoosmo tic flow) regardless of the emulsion or micellar phase used. It is pro posed that owing to its behaviour it can serve as an ideal internal st andard in further studies on microemulsion separations.