HPLC analysis of n-3 and n-6 fatty acid levels in rat serum after chronic treatment with dietetic oils

High-performance liquid chromatography HPLC analysis of the major fatty acids of the n-3 family and n-6 family in rat serum was carried out. To perform sample cleanup, existing techniques of lipid extraction were tested and modified to achieve maximal free fatty acids recovery in a reasonable time. Concerning chromatographic analyses, p-bromophenacyl bromide was used as ultraviolet (UV)-derivatizing agent followed by reversed-phase HPLC/UV under mobile phase gradient conditions. The optimized and validated procedure was then applied to rats fed with flaxseed oil and a combination of flaxseed, fish and sunflower oils, defined as "dietetic oil", in order to evaluate how their chronic supplementation can influence serum levels of n-3 and n-6 fatty acids.