Purification of Docosahexaenoic Acid Ethyl Ester Using a Silver-Ion-Immobilized Porous Hollow-Fiber Membrane Module

• Published in: Biotechnology progress Vol. 17; no. 5; pp. 893 - 896
• Main Authors: Ozawa, Ichiro, Kim, Min, Saito, Kyoichi, Sugita, Kazuyuki, Baba, Takashi, Moriyama, Shigeru, Sugo, Takanobu
• Format: Journal Article
• Language: English
• Published: USA American Chemical Society 01.09.2001; American Institute of Chemical Engineers
• Subjects: Adsorption; Biological and medical sciences; Biotechnology; carbon; docosahexaenoic acid ethyl ester; Docosahexaenoic Acids - isolation & purification; Equipment Design; Fatty Acids, Unsaturated - isolation & purification; Fundamental and applied biological sciences. Psychology; Membranes, Artificial; Methods. Procedures. Technologies; Others; Permeability; silver; Silver - chemistry; Sulfonic Acids - chemistry; Various methods and equipments; Separation method; Elution; Purification; Adsorption; Porous membrane; Hollow fiber; Polyunsaturated fatty acid; Fatty ester; Immobilization; Silver ion; Docosahexaenoic acid
• ISSN: 8756-7938; 1520-6033
• DOI: 10.1021/bp0100777

Docosahexaenoic acid ethyl ester (DHA‐Et) was purified by adsorption on Ag‐ion‐immobilized membranes via selective interaction between silver ion and carbon‐carbon double bonds of DHA‐Et. Silver ions were immobilized onto sulfonic‐acid‐group‐containing porous hollow‐fiber membranes at an Ag ion density of 1.4 mol/kg of membrane, and 30 membranes were housed in one module (inner diameter = 18 mm and effective length = 80 mm). The adsorption isotherms of DHA‐Et in various organic solvents revealed that DHA‐Et was adsorbed on the immobilized Ag ions with a DHA‐Et/Ag ion molar binding ratio of 1/5 in methanol, and that acetonitrile was the solvent of choice for the elution of the adsorbed DHA‐Et. Permeation of bonito oil ethyl ester solution in methanol through the Ag‐ion‐immobilized hollow‐fiber membrane module demonstrated that the displacement adsorption of other lower unsaturated fatty‐acid ethyl esters by DHA‐Et proceeded along the membrane thickness. The purity of DHA‐Et was improved to 99 wt % by permeating first bonito oil ethyl ester containing 95 wt % DHA‐Et and then acetonitrile through the module.