Chromatographic process for the production of highly purified polyunsaturated fatty acids

A process for recovering a first polyunsaturated fatty acid from a feed mixture that comprises the first polyunsaturated fatty acid and at least a second fatty acid in addition to the first polyunsaturated fatty acid, the process successively comprising:

• forming a final product having the first polyunsaturated fatty acid at greater than or equal to about 90% by weight and less than or equal to about 2% by weight of the second fatty acid, wherein the forming comprises:
• performing a main step of chromatographic separation using an aqueous organic eluent, and thereby collecting a first stream of eluent enriched in the first polyunsaturated fatty acid and a second stream of eluent enriched in the second fatty acid;
• subjecting the second stream of eluent to a concentration step so as to obtain a concentrated portion of the second stream comprising the second fatty acid and a depleted portion of the second stream comprising the eluent, but depleted of the second fatty acid, wherein a flow rate of the depleted portion of the second stream is reduced relative to a flow rate of the second stream of eluent;
• and
• at least partially recycling the depleted portion of the second stream for use in the main step of chromatographic separation.

A process for recovering a first polyunsaturated fatty acid from a feed mixture that comprises the first polyunsaturated fatty acid and at least a second fatty acid in addition to the first polyunsaturated fatty acid, the process comprising:

• forming a final product having the first polyunsaturated fatty acid at greater than or equal to about 90% by weight and less than or equal to about 1% by weight of the second fatty acid, wherein the forming comprises:
• performing a chromatographic separation step using an aqueous organic eluent and thereby collecting a first stream of eluent enriched in the first polyunsaturated fatty acid and a second stream of eluent enriched in the second fatty acid;
• subjecting the second stream of eluent to a partial concentration step that produces a third stream comprising the second fatty acid at a higher concentration than in the second stream and a fourth stream comprising the eluent, but depleted of the second fatty acid, wherein the fourth stream comprises less than or equal to about 20% by weight water;
• and
• at least partially recycling the depleted portion of the fourth stream to use it in the chromatographic separation step.