IOANA AMĂRIUȚEI*, MARINELA FLOREA*#, MIHAELA VIOLETA GHICA**, LĂCRĂMIOARA POPA**, CRINA-MARIA MONCIU*, MIHAELA ILIE***
*Department of Analytical Chemistry, ”Carol Davila” University of Medicine and Pharmacy, Bucharest, Romania
**Department of Physical Pharmacy and Colloids, ”Carol Davila” University of Medicine and Pharmacy, Bucharest, Romania
***Department of Toxicology, Faculty of Pharmacy, ”Carol Davila” University of Medicine and Pharmacy, Bucharest, Romania
Microemulsions are systems of interest to the pharmaceutical science. Important applications are found in the separation techniques, being used as running media in microemulsion electrokinetic chromatography (MEEKC). The paper surveys the possibility to include resonance light scattering (RLS) spectrometry as a preliminary step in the development of microemulsion electrokinetic chromatography method. Thus the scope of the RLS technique is extended. Microemulsion of heptane in borate buffer (pH = 9), prepared using natrium dodecyl suphate as surfactant and n-butanol as cosurfactant, and solutions of two antidiabetic drugs (metformin and glibenclamide) were studied. Results were correlated with molecular modeling and physical-chemical parameters (viscosity, conductivity, relative permittivity). The ability to form ion pairs of the studied molecules, in ionized form, with the surfactant molecules in the aqueous phase and the extent to which the antidiabetics in molecular form are distributed in the oil phase was also investigated. Thus for glibenclamide a strong retention at the surface of the oil droplet was suggested. Metformin forms ion pairs with low association constant anionic SDS molecules. MEEKC of the two antidiabetics proved an electrophoretic behavior in accordance with the mechanisms proposed.
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