title: Eicosapentaenoic acid enrichment from sardine oil by argentation chromatography.
abstract: Eicosapentaenoic acid (EPA) derived from chemically hydrolyzed sardine oil was concentrated by urea fractionation using methanol at different temperatures (2, 4, and 6 degrees C) and urea/fatty acid ratios (2:1, 3:1, and 4:1 w/w) and purified by argentation neutral alumina column chromatography. The individual fatty acids were determined as fatty acid methyl esters (FAME) by gas-liquid chromatography and gas chromatography-mass spectroscopy as FAME and N-acyl pyrrolidides. In the mass fragmentation pattern of FAME, the base peak was assigned to be the 1-methoxyethenol moiety (m/z = 74) obtained by McLafferty rearrangement. Formation of the cyclic tropylium ion (m/z = 91) in fatty acids with four or more double bonds was apparent in FAME-PUFAs. The base peak of N-acyl pyrrolidides was the McLafferty rearrangement ion, 1-(pyrrolidin-1-yl)ethenol (m/z = 113). The highest concentration of EPA (47.78%) was obtained at the crystallization temperature of 4 degrees C with a urea/fatty acid ratio of 4:1 (w/w) with 93.74% yield. After complexation of saturated and less unsaturated fatty acids by urea complexation, argentation chromatography resulted in an EPA of high purity (99.6%) with an overall recovery of 54.09% using 50% diethyl ether/n-hexane as eluting solvent. The peroxide (POV) and thiobarbituric acid (TBS) values were found to be highest (4.0 mequiv of O2/kg and 5.2 mg of malondialdehyde/kg, respectively) during urea fractionation at the higher crystallization temperature (6 degrees C) and higher urea/fatty acid ratio (4:1).
  
  
  BACKGROUND
  Sardine oil; eicosapentaenoic acid (EPA); fatty acid methyl esters (FAME); urea fractionation; argentation column chromatography.
authors.affiliation: Physiology Nutrition and Pathology Division, Central Marine Fisheries Research Institute, Ernakulam North P.O., P.B. No. 1603, Cochin-682018, Kerala, India. kajal_iari@yahoo.com
authors.forename: Kajal
authors.initials: K
authors.lastname: Chakraborty
authors.forename: R Paul
authors.initials: RP
authors.lastname: Raj
mesh_terms: D005591:Chemical Fractionation; D002853:Chromatography, Liquid / Q000379:methods*; D015118:Eicosapentaenoic Acid / Q000302:isolation & purification*; D005395:Fish Oils / Q000737:chemistry*; D012835:Silver Nitrate; D014508:Urea
chemical_list: D005395:Fish Oils; D014508:Urea; D012835:Silver Nitrate; D015118:Eicosapentaenoic Acid