Separation Process For Purification Of EPA-EE And DHA-EE

Omega-3 polyunsaturated fatty acids are essential fatty acids due to can't de novo synthesis in body.Especially eicosapentaenoic acid(EPA)and docosahexaenoic acid(DHA),appear to play several important roles in human health relating to nutritional benefits and physiological functions.Therefore,they are widely used as ingredient for nutritional supplements,food additives,and medicines.It's known that the main sources of EPA and DHA are marine fish oils.However,low content of them in marine fish oils can't satisfy the needs of the food and pharmaceutical industries.Thus,it is important to produce high quality EPA and DHA by enrichment and purification.Eicosapentaenoic acid ethyl ester(EPA-EE)and docosahexaenoic acid ethyl ester(DHA-EE)were separated by three different processes.It is of great significance for the preparation of EPA-EE and DHA-EE in industrial production.The main contents and results are described as follows:Urea complexation is recognized as one of the simplest and most efficient methods of enriching PUFAs from fish oil fatty acids.In this work,the production of EPA-EE and DHA-EE concentrates by urea complexation was optimized.Firsty,experimental procedure of urea complexation was simplified to ensure urea was completely removed from the product.Then,the content and recovery of EPA-EE and DHA-EE in the final product were maximized.A single factor experiments were carried out to study the effects of the ratio of urea to fish oils,solvent to fish oil ratio,crystallization time,and crystallization temperature.Based on the results,three factors and three levels of orthogonal experiment were employed to optimize technological conditions.Under the optimal conditions,the highest content of EPA-EE(49.16%)and DHA-EE(31.33%)were obtained at the ratio of urea to fish oil fatty acids of 1:1(w/w),crystallization temperature of 0 ?,solvent to fish oil fatty acids of 2:1(w/w),and crystallization time of 2 h.Meanwhile,the high recovery of EPA-EE and DHA-EE can be up to 81.22%and 84.01%,respectively.What's more,crystallization temperature was increased to 20 ?,and has little impact on the purity and recovery of EPA-EE and DHA-EE.The polystyrene/divinylbenzene(PS/DVB)was selected as the stationary phase.And EPA-EE and DHA-EE were separated by fixed bed chromatography.Firstly,the effect of mobile phase on separation was investigated.The results show that methanol is a suitable mobile phase with the resolution of 2.75.Then,the effects of the particle diameter and pore size of PS/DVB were examined by HPLC.PS/DVB with particle diameter of 10 ?m,pore size of 100 A was the best choice for separation by comparing resolution.But taking pressure drop into account,particle diameter of 20 ?m is more favorable in large-scale preparation.Besides,the influence of the operating temperature,flow rate of mobile phase,injection volume,and sample concentration on the separation were studied.The results showed that in the scope of experiments,the resolution decreased with the increasing temperature,the resolution increases as the flow rate of mobile phase decreasing,the injection volume,and the sample concentration have unfavorable influence on separation.Finally,high-purity EPA-EE and DHA-EE were producedbya semi-preparative column with PS/DVB(10 mm×150 mm,20?m),the purity of EPA-EE and DHA-EE is greater than 99%.Based of the former reaserch,eight semi-preparative columns(10 ?m×150 mm)with PS/DVB(20 ?m,100 (?))was prepared for simulated moving bed(SMB)chromatography.And the homogeneity of eight semi-preparative columns was tested by HPLC.Then EPA-EE and DHA-EE mixture were separated with SMB chromatography and methanol was the eluent.The effect of flow rate of ?(?)zone,flow rate of feed,column temperature and feed concentration were systematically investigated.Under optimal conditions,EPA-EE and DHA-EE with the favorable purity of 91.6%and 93.6%can be achieved,respectively.And recovery of EPA-EE is 97.0%,recovery of DHA-EE is 91.6%.Besides,productivity and solvent requirement are 5.97 g/(L·h),1.52 L/g,respectively.Therefore,SMB chormotography is an attractive technology to produce high value products.