Quantitative Determination of Trans-Fatty Acids in Oils and Fats by Capillary Gas Chromatography: Results of a JOCS Collaborative Study

Excessive intake of trans-fatty acids increases the risk of cardiovascular disease. Much attention is drawn to the consumption of trans-fatty acids worldwide, and regulations for trans-fatty acids are instituted in several countries.    Precise and convenient methods for determination of trans-fatty acid level are required, but there is no standard method using capillary Gas Chromatography in Japan. Therefore, for the new standard method, collaborative studies were carried out.    The results were as follows:    1) Heptadecanoate (C17:0 free fatty acid) was chosen for internal standard substance.    2) Two Gas Chromatography columns, SP2560 (100 m) column (100% cyanopropyl polysiloxane liquid phase) and TC-70 (60 m) column (70% cyanopropyl polysilphenylene-siloxane liquid phase), were examined in the collaborative studies. We measured the edible oil samples containing 2-45 g/100 g of trans-fatty acids, and trans-fatty acid contents were quantitatively the same with both columns. The range of reproducibility coefficient of variation were below 10%.    3) Fats and oils sampled were soybean, rapeseed, palm, palm kernel, beef tallow, pork fat and their hydrogenated forms, for which good peak resolution was achieved.    From the above results, the technique evaluated in the present study was considered to be suitable for determination of the content of trans-fatty acids in fats and oils exclusive of fish oil and milk fat.