A rapid and highly specific method for the determination of cis-vaccenic acid content in plant lipids by mass chromatography has been developed.
Two calibration curves were obtained from the mass chromatography of several standard mixtures containing known amounts of dimethyl disulfide adduct (DMDSA) of methyl
cis-vaccenate and DMDSA of methyl oleate. The content of
cis-vaccenic acid in standard mixtures was proportional to the values calculated from the peak areas of characteristic ions due to the fragmentation of DMDSA of these esters.
A mixture of fatty acid methyl esters prepared from plant total lipids was subjected to a reaction with dimethyl disulfide in the presence of I
2 as the catalyst for 30min. After removal of contaminating by-products from the reaction products by thin-layer chromatography, the purified DMDSA fraction of methyl monoenoates was introduced into a gas chromatograph-mass spectrometer.
This method has been found applicable to the determination of
cis-vaccenic acid content in naturally-occurring lipids, such as chlorella, parsley seed, soybean, and maturing
Mallotus japonicus seed lipids.
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