ANALYSIS OF POLYMERS FROM AUTOXIDIZED MARINE OILS BY GEL-PERMEATION HPLC USING A LIGHT-SCATTERING DETECTOR

A high-performance gel-permeation chromatographic method was developed for the isolation and quantification of polymers from autoxidized fish oils. The chromatographic system consists of a single pump, a 500 angstrom styrene/divinylbenzene column, and a light-scattering "mass" detector. Dichloromethane was used as the mobile phase, and quantifications were carried out using glycerol as internal standard. The polymer content of commercially available fish oils was found to be around 2%, but the value increased rapidly during oxidation at 35-degrees-C in air under light. The oxidized oils were also characterized by peroxide value, thiobarbituric acid value, ultraviolet (UV) measurements, thin-layer chromatography (TLC)/densitometry, and capillary gas chromatography. No correlation between polymer content and standard oxidation assessment parameters for the fish oils analyzed was found. However, a relationship between the polymer increase and the decrease of total fatty acids was observed, indicating that the polymers may be the main oxidation product in autoxidized marine oils.