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. PRACTICAL APPLICATIONS Rats treated chronically with flaxseed oil and “dietetic oil” (composed of flaxseed, fish and sunflower oils) showed enhanced levels of n‐3 fatty acids. In particular, the levels found for α‐linolenic acid was a little higher after administration of the dietetic oil, probably due to an enhanced absorption and also a decreased metabolism. The data obtained underline that the tested oils can enhance the levels of n‐3 fatty acids and, therefore, they could be successfully used in the dietetic treatment of lipid‐related diseases.