Journal of Lipid Research, Vol 22, 852-858, Copyright © 1981 by Lipid Research, Inc.
A rapid, simple, and sensitive procedure for the determination of free fatty acids in plasma using glass capillary column gas-liquid chromatography
KY Tserng, RM Kliegman, EL Miettinen and SC Kalhan
A rapid and sensitive method for the analysis of plasma free fatty acids
with glass capillary column gas-liquid chromatography and flame ionization
detection is described. The plasma sample, together with n- pentadecanoic
acid as an internal standard, was treated with 2,2- dimethoxypropane and
hydrochloric acid. 2,2-Dimethoxypropane serves as water scavenger,
deproteinizing agent, and as a methylating agent. Under the assay
conditions, only free fatty acids were converted to their methyl esters;
esterified fatty acids, such as those in triglycerides and phospholipids,
were not significantly transmethylated. This advantage eliminated the need
for thin-layer chromatography for the separation of free and esterified
fatty acids. The methyl esters of fatty acids were then extracted into
isooctane and analyzed with a 10-meter glass capillary column coated with
SP-2100. Splitless mode of injection was used to increase the sensitivity.
Only 20 microliter or less of plasma was required for analysis. The
coefficient of variation was 4.6%, which was better than the conventional
gas-liquid chromatographic methods. These latter methods require 20 to 50
times larger samples, as compared with the present assay. This method is
suitable for the measurement of both total free fatty acids and individual
fatty acid patterns in small plasma samples.