Simultaneous measurement of free and esterified fatty acids by gas chromatography from normal and type IV hyperlipoproteinaemic sera.

A transmethylated reaction of esterified fatty acids with sodium- methoxide in a mixture of serum, petroleum ether and methanol is presented. In the conditions used the free fatty acids in the sample were not esterified. 1-2 microliters of the organic phase was injected into an OV-351 fused silica capillary column of gas liquid chromatography (GLC) fitted with flameionizing detector (FID) temperature program, and calculating integrator. By this method both free and esterified fatty acids were measured in a single run. The development of the present method for the better quantitation of free fatty acids is in progress as using gas chromatography/mass spectrometry for identification of the peaks. In thirteen healthy subjects, the serum free fatty acid content was 538 +/- 176 mumol/l and free glycerol 107 +/- 39 mumol/l, while in seven type IV hyperlipoproteinaemic sera the corresponding values were 1049 +/- 529 and 86 +/- 38 mumol/l. The most prominent differences between healthy and type IV hyperlipoproteinaemic subjects for esterified fatty acids were found in palmitic, oleic and arachidonic acids. The correlations between free and bound fatty acids has been discussed.