|Abstract or Summary
- Two methods for the estimation of non-esterified fatty acids in
plasma were evaluated. An attempt was made to obtain a reliable
micro-technique to estimate these acids in blood fractions.
The titrimetric method of Trout et al. was satisfactory in the
analyses of pure fatty acids and fatty acids added to serum. In the
analyses of palmitic and stearic acid solutions, the mean values ranged
from 95 to 115 percent of actual values. The mean recovery of palmitic
acid added to a serum was 110 percent. The reproductibility of
the method was fair in replicate analyses of three standard sera on
two to four different days. The mean values determined for Serum A
were 645, 653, 641, and 605; for Serum B, 587 and 587; and for
Serum C, 565, 571 and 533 μEq per liter of serum.
The colorimetric micro-method of Mendelsohn was also satisfactory
in the analyses of pure fatty acids, fatty acids added to a
serum, and a fatty acid as a component of standard lipid mixtures. In the analyses of palmitic, stearic, and oleic acid solutions, the
mean values ranged from 97 to 118 percent of actual values. The
recoveries of palmitic and oleic acids added to a serum ranged from
81 to 111 percent in four different experiments. In the determination
of oleic acid from mixtures of several lipids, the recovery ranged
from 95 to 107 percent. The reproductibility of the method was also
fair in replicate analyses of a standard serum on 11 different days.
The individual determinations ranged from 768 to 1046 μEq per liter
of serum with a mean of 917. The mean values of 11 different experiments
ranged from 830 to 1013 μEq per liter of serum.
A comparison of methods was made by analyzing four standard
sera in replicate by both methods. The values of the non-esterified
fatty acids by the method of Mendelsohn were approximately twice
those by the method of Trout et al. The difference was attributed to
the degrees of extraction of non-esterified fatty acids and/or other
acids from the serum by the two methods.
The concentrations of the non-esterified fatty acids in the sera
and the erythrocytes of 16 subjects of both sexes, ranging in age from
23 to 66 years, were determined by an adaptation of the colorimetric
method of Mendelsohn. The concentrations in the sera ranged from
380 to 1057 μEq per liter with a mean of 800. The concentrations in
the erythrocytes were consistently higher than those in the serum for
all the subjects and ranged from 552 to 1919 μEq per liter with a mean