T. Nikkari et al., MONITORING OF LIPOPROTEIN OXIDATION BY GAS-CHROMATOGRAPHIC ANALYSIS OF HYDROXY FATTY-ACIDS, Journal of lipid research, 36(1), 1995, pp. 200-207
We describe a method developed for the quantitative analysis of hydrox
y fatty acids derived from fatty acid monohydroperoxides formed during
lipoprotein oxidation. The procedure starts with catalytic hydrogenat
ion of the lipid extract, whereby hydroperoxyl groups are converted to
hydroxyl groups and double bonds are eliminated, and the risk for lip
id oxidation during the rest of the procedure is eliminated. The fatty
acids are converted to methyl esters, which are fractionated by gas c
hromatography on a nonpolar column. The major differences to existing
methods are that a mass spectrometer is not required and that the spec
ificity thus lost is replaced by gas chromatography before and after a
cetylation of the hydroxyl groups. This changes the retention times of
the hydroxyacids with respect to the unsubstituted fatty acids moving
them to positions usually occupied by trace components only. The meth
od allows quantification of monohydroxy fatty acids derived from 18-,
20- and 22-carbon polyunsaturated fatty acids. Positional isomers are
separated from each other to some extent. The method has been mainly u
sed for analysis of hydroperoxides in human low density lipoprotein pr
eparations and for following lipoprotein oxidation in vitro.