ISO 12966-3:2016规定了用三甲基锍氢氧化物（TMSH）对脂肪和油进行快速碱催化酯交换法制备脂肪酸甲酯。该方法仅适用于制备用于气相色谱（GLC）分析的脂肪和油的甲酯。适用于所有脂肪和油脂，但不包括牛奶和奶制品。不饱和脂肪酸的异构化仅发生在较小程度上，异构化的脂肪酸仅存在于测定极限。异构化发生时，不建议使用共轭亚油酸（CLA）。 仅约70％至80％的游离脂肪酸被酯化。在共轭环丙基和环丙烯基脂肪酸的情况下，可能发生副反应，但这些不影响脂肪酸的测定

ISO 12966-3:2016 specifies a rapid base-catalysed transesterification method for fats and oils with trimethylsulfonium hydroxide (TMSH) to prepare fatty acid methyl esters. The method is exclusively applicable to the preparation of methyl esters of fats and oils for gas liquid chromatographic (GLC) analysis. It is applicable to all fats and oils, but excluding those coming from milk and milk products. Isomerization of unsaturated fatty acids only occurs to a minor extent and isomerized fatty acids are only present at the determination limit. As isomerization takes place, the procedure is not recommended for conjugated linoleic acid (CLA). Only about 70 % to 80 % of the free fatty acids are esterified. In the case of conjugated cyclopropyl and cyclopropenyl fatty acids, side reactions may occur, but these do not interfere with the determination of the fatty acids.