HCl Treatment Followed By Bligh and Dyer Extraction Extract More Fatty Acids than Stoldt Fat Extraction in Feed and Fecal Samples., S.K. Jensen, C. Lauridsen, Aarhus University, Faculty of Agricultural Sciences, Tjele, Denmark. The official EU method for fatty acid analysis in feed is based on boiling of the feed sample in 3 M HCl followed by a filtration, drying, Soxhelet extraction of the fat with petrol ether, conversion of the fatty acids to their corresponding methyl esters and followed by GC separation. Besides being very time consuming, this method has several disadvantages, e.g. the filtration step may allow some shorter chain free fatty acids and some phospholipids to be washed through the filter and escape the analysis. Further, during the drying step of filter paper, oxidation of polyunsaturated fatty acids (PUFA) is a risk. Because of the mentioned disadvantages, a new method ("HCl-Bligh and Dyer method") has been developed, and compared with the traditional Stoldt fat extraction. The new method combines the HCl treatment of the sample with a Bligh and Dyer extraction (water-methanol-chloroform) of the lipid. Depending on the matrix (feed ?), the HCl-Bligh and Dyer extraction lead to 10-15% more total fatty acids and a 30-50% increase in some of the PUFA compared with the official EU method. Thus, besides being much more efficient for extraction of fatty acids, the HCl-Bligh and Dyer method is much faster, and allows inclusion of an internal standard from the beginning of the sample treatment.