SFC制备EPA和DHA乙酯过程中上载量和流速的影响

Effects of Loading and Flow Rate on the Preparation of EPA-EE and DHA-EE by Supercritical Fluid Chromatography

以超临界CO2为流动相ODS-C18为固定相,以尿素包络法处理后的鱼油乙酯化物为原料,柱温为55℃,柱前压为12.1MPa,改变载量和流动相流速,测定了二十碳五烯酸乙酯(EPA-EE)和二十二碳六烯酸乙酯(DHA-EE)的色谱动态特性。结果表明,EPA-EE与DHA-EE之间的分离良好,但原料中其他脂肪酸乙酯杂质不能分离。适当切割流出物馏分,EPA-EE的纯度可达90%,DHA-EE可达75%。根据实验结果考察了载量和流动相流速对制备色谱效能的影响。色谱柱的生产能力随流速的增大而增大。在EPA-EE纯度一定的前提下,色谱柱的生产能力随载量的增大而增大,但载量过大则生产能力又会减小。当EPA-EE纯度要求在85%以下时,载量对其回收率的影响不大,CO2消耗量(每单位重量产品的消耗)随着载量的增大而减少;纯度要求在90%以上时,回收率随载量的增大而明显减小,CO2消耗量随载量的变化有最低点,在载量为4.076mL·L-1时为最小。EPA-EE纯度要求为90%时,适宜载量为7.13mL·L-1,流动相流速为3.928g·min-1,此时色谱柱的生产能力为2.41g·h-1·L-1,EPA-EE回收率为37.8%。同时得到的DHA-EE的纯度为75%,回收率为88.8%。

Eicosapentaenoic acid ethyl ester （EPA-EE） and docosahexaenoic acid ethyl ester （DHA-EE） were separated from ethyl ester of fish oil by supercritical fluid chromatography with the stationary phase C18, and the mobile phase supercritical fluid CO2 under 12.1 MPa and 55℃. Chromatographic characteristics were determined at various loadings and flow rates. It was found that EPA-EE and DHA-EE were well separated, but other esters of fatty acids presented in the feed could not be separated. By appropriately cutting the effluent, EPA-EE with 90% purity and DHA-EE with 75% purity were obtained. Based on the chromatographic curves, the effects of loading and flow rate of mobile phase on the performance of the column were studied. The results are as follows. The productivity of the column increases linearly with flow rate of mobile phase. For a given purity of EPA-EE, the productivity increases with loading to some extent, then decreases with further increase of loading. For EPA-EE purity less than 85%, recovery of EPA-EE changes little with loading, and the consumption of carbon dioxide based on unit product decreases as the loading increases. For EPA-EE purity greater than 90%, as the loading increases, recovery of EPA-EE decreases remarkably, and the curve of CO2 consumption versus loading has a minimum consumption point at the loading of 4.076 mL·L^-1. Under 12.1 MPa and 55℃, the suitable conditions for preparation of 90% EPA-EE are loading of 7.13 mL·L^-1 and CO2 flow rate of 3.928 g·min^-1. Meanwhile the productivity of 90% EPA-EE is 2.41 g·h^-1·L^-1 with a recovery of 37.8% and the purity of DHA-EE is 75% with a recovery of 88.8%.