ISO 12966-3 Animal and Vegetable Fats and Oils - Gas Chromatography of Fatty Acid Methyl Esters - Part 3: Preparation of Methyl Esters Using Trimethylsulfonium Hydroxide (TMSH)

EUROLAB, with its state-of-the-art accredited laboratories and expert team, provides precise and fast testing services within the scope of ISO 12966-3 testing. ISO 12966-3 specifies a rapid base-catalyzed transesterification method with trimethylsulfonium hydroxide (TMSH) for fats and oils to prepare fatty acid methyl esters. The method is specifically applicable to the preparation of methyl esters of fats and oils for gas liquid chromatographic (GLC) analysis.

It applies to all fats and oils, excluding those from milk and dairy products. Isomerization of unsaturated fatty acids occurs only to a small extent, and isomerized fatty acids are only at the limit of detection. The procedure is not recommended for conjugated linoleic acid (CLA) as isomerization takes place.

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 they do not interfere with the determination of fatty acids.

The sample is dissolved in tert-butyl methyl ether (TBME) and mixed with a trimethylsulfonium hydroxide solution with methanol. Glycerides are base-catalyzed transesterified to form fatty acid methyl esters. Free fatty acids are converted to methyl esters and salts which are pyrolyzed in dimethylsulfide in the injector. Excess reagent is further pyrolyzed to methanol and dimethylsulfide. To achieve a complete pyrolytic reaction, a hot injector (split injection) of at least 250°C is required.

Samples containing water were dissolved in petroleum ether and dried for 30 minutes by adding anhydrous sodium sulfate. The drying agent is filtered off through a fluted filter paper and the residue is carefully washed with petroleum ether. The solvent is then removed with the aid of a rotary evaporator.

EUROLAB assists manufacturers with ISO 12966-3 test compliance. Our test experts, with their professional working mission and principles, provide you, our manufacturers and suppliers, the best service and controlled testing process in our laboratories. Thanks to these services, businesses receive more effective, high-performance and quality testing services and provide safe, fast and uninterrupted service to their customers.