NF EN ISO 12966-2

La présente Norme internationale spécifie des méthodes de préparation des esters méthyliques d'acides gras.Elle comprend des méthodes de préparation des esters méthyliques d'acides gras à partir des corps gras d'origines animale et végétale, des acides gras et des savons. Afin de répondre à différentes exigences, trois méthodes de méthylation sont spécifiées, à savoir:a) la méthode au trifluorure de bore (BF3) (voir l'article 3);b) la méthode à l'hydroxyde de triméthylsulfonium (TMSH) (voir l'article 4);c) la méthode de transestérification (voir l'article 5).Les esters méthyliques ainsi obtenus peuvent être utilisés dans diverses méthodes d'analyse exigeant des produits dérivés de ce type, telles que la chromatographie en phase gazeuse (CPG), la chromatographie en couche mince (CCM) ou la spectrométrie à infrarouge (IR).

This International Standard specifies a gas chromatographic method using capillary columns for the determination of the content of trans fatty acid isomers of vegetable oils and fats. The method is specially designed to evaluate, by a single capillary gas chromatographic (GC) procedure, the level of trans isomers as formed during (high temperature) refining, or during hydrogenation of vegetable oils or fats. The method may also be used to report all other fatty acids (e.g. to obtain the full fatty acid composition and total amounts of saturated fatty acids, mono-unsaturated fatty acids and poly-unsaturated fatty acids) from the same sample and same analysis.

ISO 12966-2:2017 specifies methods of preparing the methyl esters of fatty acids. It includes methods for preparing fatty acid methyl esters from animal and vegetable fats and oils, fatty acids and soaps. To cover different requirements, four methylation methods are specified, namely: a) a "rapid" transmethylation procedure under alkaline conditions; b) a "general" transmethylation/methylation procedure under sequential alkaline and acid conditions; c) a BF3 transmethylation procedure; d) an alternative procedure using acid-catalysed transmethylation of glycerides. Methyl esters so produced are used in various analytical procedures requiring such derivatives, e.g. gas-liquid chromatography (GLC), thin-layer chromatography (TLC) and infrared spectrometry (IR). Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this document.