SEPARATION OF w-3 POLYUNSATURATED FATTY ACIDS FROM FISH OIL

Abstract

w-3 polyunsaturated fatty acids, especially cis- 5.8, 11, 14,17- eicopentaenoic acid (EPA) and cis- 4,7.1 0, 13, 16,19- docosahexaenoic acid (DHA) have therapeutic potential to the cardiovascular diseases, inflammatory diseases and cancers. Therefore, the reason in the consumption of fish oils is for the prevention and treatment of variety of human diseases. For further clinical studies, and perhaps as a nutritional health supplement, it is necessary to purify EPA or DHA to keep the intake of other possible physiologically active fatty acids as low as possible. The present work investigates the reversed phase high performance liquid chromatographic separation of EPA and DHA from the concentrated free fatty acids. Non-toxic mobile phase: ethanol-water (55-45, by volume) with 0.3% acetic acid and the self-packed C18 columns are employed. The purities of EPA and DHA of 97.2% and 95.4% respectively are achieved on a preparative self-packed column. The retention behaviors of fatty acids are also studied as a function of mobile phase composition, temperature and flow-rate on an analytical column and a semi preparative self-packed column. It is obvious that the capacity factors of fatty acids increase with decreasing the volume percentage of ethanol in mobile phase and temperature but they seem to be independent of the flow-rate. It is found that the capacity factors of fatty acids are exponentially a function of inverse of temperature and volume percentage of ethanol in a mobile phase. which is well described by solvophobic theory. At the same time, the statistical experimental design and the statistical analysis software: SAS (Statistical Analysis System) are successfully employed to study the retention behaviors of fatty acids. Meanwhile, modelling of the chromatographic separation profiles of EPA and DHA is developed by combining the empirical model based on the solvophobic theory and the equilibrium-dispersive mathematical model. It is found that the simulated profiles agree the experimental data well. In addition, it is found that the Height Equivalent to Theoretical Hight(HETP) for EPA and DHA are to be independent to the flow-rate in this system.