High-yield preparation of methyl stearolate

Simultaneous analysis of low plasma levels of deuterium-labeled saturated and unsaturated fatty acids as t-butyldimethylsilyl esters

A sensitive and accurate method for detection and quantitation of deuterated fatty acids in the presence of large amounts of unlabeled fatty acids is described using mass fragmentography in combination with the preparation of tertiarybutyldimethylsilyl esters (t-BDMS). The method has been applied to determination of deuterated stearic, oleic, elaidic and linoleic acids in human plasma lipoproteins following duodenal perfusion with a micellar mixture of acids. Over a concentration range of 10-1000 ng/ml, the average coefficient of variation for the linoleate was 3% and for the oleate (elaidate) ester was 2%.

Dual-labeled technique for human lipid metabolism studies using deuterated fatty acid isomers

Two deuterated fatty acids, elaidated2 and oleate-d4, were fed simultaneously to a human subject as a mixture of trielaidin-d6 and triolein-d12. Periodically, blood samples were drawn, and red blood cells were separated from the plasma. Red blood cells and plasma lipids were fractionated and analyzed by combined gas chromatography--multiple ion mass spectroscopy. Dual deuterium-labeling allows rate and extent of fatty acid incorporation to be followed in various plasma and red cell neutral and phospholipid fractions. Maximum amount of deuterated fat varied from 4% in cholescurred in either 6-, 8-, or 12-hr samples; generally, less than 1% labeled fatty acids could be detected in 72-hr samples. Because the method is based on dual-labeling, differences in the relative incorporation of both fatty acid isomers can be compared directly. Differences in rates of incorporation, rates of removal, and extent of incorporation of labeled fatty acids into blood plasma can also be determined reliably. Our experimental labeling of fats with deuterium permits for the first time the metabolism of two fatty acid isomers to be compared simultaneously in human subjects. This new method should be applicable to a variety of other lipid metabolic studies.