The purpose of this document is to describe a procedure for the determination of the ester content in fatty acid methyl esters (FAME) intended for incorporation into diesel oil. It also allows determining the linolenic acid methyl ester content. It allows verifying that the ester content of FAME is greater than 90 % (m/m) and that the linolenic acid content is between 1 % (m/m) and 15 % (m/m). This method is suitable for FAME which contains methyl esters between C6 and C24. NOTE 1 For the purposes of this document, the terms % (m/m) and % (v/v) are used to represent respectively the mass and volume fractions. NOTE 2 This method was elaborated for FAME samples from usual raw material. For FAME sample from unidentified raw material, a solution of the test sample is prepared without any internal standard addition, in order to verify the absence of natural nonadecanoic acid methyl ester. NOTE 3 The distribution off fatty acid methyl esters is given in Annex C. WARNING The use of this method may involve hazardous equipment, materials and operations. This method does not purport to address to all of the safety problems associated with its use, but it is the responsibility of the user to search and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.