Separation of unsaturated C18 fatty acids using perfluorinated-micellar electrokinetic chromatography: II) role of nano-structuration

Abstract

• Free fatty acids are separated by capillary electrophoresis using fluorosurfactants. • Scattering experiments evidence aggregation from small micelles to large structures. • Micelle structuration in injection buffer and background electrolytes is affected by fatty acids. • Selective interactions between fatty acids and fluorosurfactant allow CE separation. Three fatty acids were separated by micellar electrokinetic chromatography (MEKC) using ammonium perfluorooctanoate as volatile surfactant. Characterizations of both injection buffer and background electrolyte have been performed by complementary techniques including scattering experiments (light, x-rays) and NMR. Different structures have been observed such as small micelles at low methanol content and larger aggregates at high methanol content. In both cases fatty acids interact specifically with the perfluorinated self-assemblies due to different geometrical constraints and different interactions between polar head groups, ensuring separation by MEKC.