The invention relates to a method for preparing
fish oil ethyl ester by
microwave esterification and purifying ethyl eicosapentaenoate, which comprises the following steps: adding
fish oil, absolute
ethanol and catalyst concentrated
sulfuric acid into a reaction vessel, and heating under
reflux in a
microwave reactor to convert free
fatty acid into
fatty acid ethyl ester; after the reaction is carried out for 10-30 minutes, removing excessive
solvent and catalyst from the product, and
drying to obtain the
fish oil fatty acid glyceride of which the
acid value is smaller than 2; preparing the pre-esterified fish oil, absolute
ethanol and catalyst KOH into a KOH-
ethanol solution, adding the KOH-ethanol solution into the reaction vessel, and heating under
reflux in the
microwave reactor to carry out the ester exchange process; and after the reaction is carried out for 5-15 minutes, stratifying the product by standing or centrifuging, removing the understratum
glycerol, removing the excessive ethanol and catalyst, and
drying to obtain the ethyl eicosapentaenoate. The invention adopts two-stage vacuum rectification: light components with lower
boiling point than ethyl EPA (eicosapentaenoate) are removed in the primary rectification
tower; and the component subjected to light component removal enters a secondary rectification
tower to separate the ethyl EPA from ethyl DHA, thereby obtaining the ethyl EPA with the purity of higher than 97%.