Determination of Saturated and Unsaturated Fatty Acids: Comparison of Gas-Liquid Chromatographic, Thiocyanogen Number, and Lead Salt-Ether Methods

The weight per cent composition of the C16—Cis series of fatty acids in edible vegetable oils was determined by GLC, lead salt-ether, and thiocyanogen number methods. Total saturated and unsaturated fatty acid percentages obtained by GLC and the lead salt-ether methods were in poor agreement; the lead salt-ether unsaturated fatty acid percentages tended to be higher than the GLC values. The thiocyanogen number values for unsaturation were higher than GLC values lor every fat and oil analyzed except one. The polyunsaturated fatty acid percentages obtained by the thiocyanogen number method were not similar to the GLC values for about half of the fats and oils examined.

Iodine and Thiocyanogen Numbers of the Fatty Acids of Blood Plasma

A method has been described for the determination of both iodine and thiocyanogen numbers of the fat isolated from human blood plasma by the Allen volumetric method. The values found in 13 normal individuals varied from 111 to 157 for iodine number and from 64 to 122 for thiocyanogen number. The differences between the two numbers varied between 9 and 78.