Iodine and thiocyanogen numbers of the fatty acids of blood plasma.

LITTLE IS KNOWN about the degree of unsaturation of the fatty acids of human blood (1). A spectrophotometric method has recently been applied to plasma by Wiese and Hansen (2) which consists of conjugation of the double bonds by heating in alkaline solution at 1800 and measuring the conjugated forms in the ultraviolet spectrum region. The authors themselves admit that this procedure is subject to much uncertainty since standards are not available for fatty acids with more unsaturated bonds than arachidonic acid. The application of this time-consuming method in clinical chemistry would, therefore, not be warranted at this time. In order to study the degree of unsaturation of the fatty acids of blood we have chosen, therefore, to use the values of iodine and thiocyanogen numbers, which have proven useful in the analysis of oils and fats (3). In 1931 Yasuda (4) proposed the use of the Rosenmund and Kuhnhenn reagent (5) to determine the iodine number of the fatty acids analyzed according to Bloor (6). We have also found that the iodine number of the fatty acids of blood plasma may be determined in this way, but have improved the oxidative method of Bloor for colorimetric estimation of the fatty acids (7). However, we have found that the thiocyanogen number (8) can not be determined in fatty acid extracts prepared by the method of Bloor. In the present paper, we describe a method to determine both iodine number and thiocyanogen number of some of the fatty