Method for preparing pure EPA and pure DHA

1. A method for separating free EPA from a mixture of EPA and DHA comprising:

a. dissolving the mixture of EPA and DHA in a solvent and adding a salt of a metal ion that produces salts of EPA and DHA which have different solubilities in the solvent;

b. cooling the solution obtained in step (a) to precipitate the salt of EPA from solution;

c. filtering the solution to remove the EPA salt; and

d. acidifying the precipitate obtained from filtering the solution to produce pure EPA.

2. The method according to claim 1 wherein the metal ion is magnesium.

3. The method according to claim 1 wherein the solvent is acetone.

4. The method according to claim 1 wherein after the EPA salt has been filtered from the solution, the solvent is evaporated to recover DHA salt, and the DHA salt is acidified to produce pure DHA.

5. A method for obtaining substantially pure EPA and DHA from a naturally occurring fat or oil comprising:

a. subjecting the natural fat or oil to saponification or alcoholysis to convert triglycerides to free fatty acids;

b. removing unsaponified materials with an organic nonpolar solvent;

c. add an acid to the nonpolar solvent solution to form free fatty acids;

d. dissolve the solution in acetone and refrigerate the solution to precipitate saturated fatty acids;

e. add a base to the solution;

f. evaporate the acetone to produce a solution of ω-3 fatty acids;

g. adding a salt which forms salts with ω-3 fatty acids which have differing solubilities in acetone;

h. refrigerating the solution to case the EPA salt to precipitate;

i. acidify the solution to obtain free DHA;

j. acidifying the EPA salt to produce free EPA.

6. The method according to claim 5 wherein the natural oils are hydrolyzed with lipase.

7. The method according to claim 5 wherein the natural oils are saponified by adding a base.

8. The method according to claim 7 wherein the base is NaOH or KOH.

9. The method according to claim 5 wherein the nonpolar solvent is methylene chloride.