2001 年 50 巻 5 号 p. 339-352
In partially hydrogenated vegetable oils (PHVO) more than 40 cis and trans fatty acids, primarily of the C18 chain length are possible. Partially hydrogenated fish oils (PHFO), invariably have much more complex fatty acid profiles because of the large number of possible isomers of the chain lengths ranging from C16 to C22. Traditionally, total trans content was determined by infrared (IR) spectroscopic techniques that do not quantify individual fatty acids. Nowadays, a satisfactory, and near quantitative analysis of fatty acid profile of PHVO can be achieved by gas chromatography (GC) using 100 m long capillary columns coated with highly polar cyanolsilicone stationary phases. In these columns, there is very little overlap of cis and trans isomers. Almost all the cyanosilicone capillary columns are capable of readily separating the low delta value trans 18:1 isomers (up to and including 12t-18:1) from the cis-18:1 isomers. If appropriate GC operating conditions are selected, then some cyanosilicone columns, especially, SP-2560 and CP-Sil 88, could provide a satisfactory saparation of the high delta isomers (13t-18:1, 14t-18:1, 16t-18:1) from the cis isomers. The 15t-18:1 is the only isomer that cannot be separated from the cis isomers. The geometric and positional isomers of linoleic and α-linolenic acids that are normally encountered in dietary fats could also be easily separated on cyanosilicone capillary columns. For applications requiring more precise trans fatty acid data and detailed information of individual isomers, it is necessary to couple capillary GC analysis with either silver nitrate-thin-layer or -high pressure liquid chromatography.
