ISO/TS 17764 specifies methods for the quantitative determination of individual fatty acids and of the sum of the fatty acids (elutable fatty acids). This part of ISO/TS 17764 specifies the application of gas chromatography with capillary columns and flame ionization detection for the determination of the quantitative content of fatty acids in a fat by making use of the methyl esters of the fatty acids obtained in accordance with the method specified in ISO/TS 17764-1. This part of ISO/TS 17764 is applicable to the investigation of animal and vegetable fats, oils and fatty acid mixtures for incorporation in animal feeding stuffs and fat extracts of animal feeding stuffs and raw materials for compound animal feeds, including fats and fatty acid mixtures containing butyric acid. This method is not applicable to polymerized fatty acids.