This International Standard specifies a method using HPSEC to determine the contents of polymerized triglycerides in oils and fats which contain at least 3 % (from peak areas) of these polymers. This method is applicable to frying fats, and fats and oils that have been thermally treated. It can also be applied to the determination of polymers in fats for animal feedstuffs. NOTE 1 Polymerized triglycerides (strictly speaking dimeric and oligomeric triglycerides) are formed during the heating of fats and oils, thus the method serves to assess the thermal deterioration of frying fats with use. NOTE 2 In the case of analysis of fats from animal feeding stuffs, the extraction method used can have an influence on the result (see ISO 6492).