Microemulsion electrokinetic chromatography of fatty acids as phenacyl esters

Abstract

A mixture of saturated fatty acids containing even number of carbon atoms was successfully separated as phenacyl esters by microemulsion electrokinetic chromatography. Separations were done by using an untreated fused-silica capillary [57 cm (effective length 50 cm)×75 μm] at 15 kV; detection was done by UV at 243 nm. The microemulsion system was composed of 10 m M borate buffer (87.93%, w/w), cholate (4.87%, w/w), heptane (0.66%, w/w) and n-butanol (6.55%, w/w), pH 10.2. Separation by microemulsion electrokinetic chromatography was characterized by high efficiency (theoretical plates ranged from 142·10 3 to 428·10 3) with peak resolution 1.25 and better. Micellar electrokinetic chromatography under the standard conditions with sodium dodecyl sulfate as micellar phase was unsuccessful in separating all long-chain fatty acids. The described method can be used for monitoring of saturated fatty acids containing even number of carbon atoms in the molecule in a broad spectrum of chain length (C 2–C 20).