Abstract
Epidemiological works in Greenland Eskimos indicated that ω-3 polyunsaturated fatty acids, especially ω-3 eicosapentaenoic acid (C20:5) have a potential anti-thrombotic and anti-atherosclerotic actions. For the determination of polyunsaturated fatty acids in total lipids in plasma, we established a new method using a gas chromatograph equipped with a glass capillary column. Total lipids were extracted from 0.4 ml of plasma using the method by Folch et al. After hydrolysis with KOH, methyl esters of fatty acids were prepared with BF3 methanol. C23:0 was used as an internal standard. The esters were analyzed by gas chromatography using a Hitachi 063 gas chromatograph equipped with a hydrogen flame ionization detector. A glass column of 40 m × 0.3 mm φ, coated with diethylene glycol succinate (DEGS), was used. The flow rate of carrier gas (nitrogen) was 25 ml/min. The injection port was kept at 350° and the detector cell at 220°. All the esters were chromatographed at 180° column temperature. Each methyl esters was indentified by the authentic fatty acid methyl esters. Reproducibility (cv value) of the determination of arachidonic acid (C20:4), C20:5, and docosahexaenoic acid (C22:6) by this method were 3.8 %, 4.4 % and 2.3 %, respectively. Recoveries for methyl esters of C20:4, C20:5 and C22:6 were 105.8 %, 112.0 % and 103.3 % respectively. For the quantitative analysis of fatty acids methyl esters, standard curves for C20:4, C20:5 and C22:6 were obtained using authentic samples. As an example of clinical application of this method, fatty acid composition of total plasma lipid was determined for healthy volunteers before and after taking C20:5 rich fish diet. A significant increase in plasma C20:5 content was observed. This new method will be useful for its high reliability.
