Stereospecific analysis of triacylglycerols via racemic phosphatidylcholines and phospholipase C

A method of simultaneous determination of stereospecific distribution and molecular association of acyl groups in triacylglycerols has been developed. The analysis is based on a random generation of rac-1,2-diacylglycerols by Grignard degradation, synthesis of rac-phosphatidylcholines, and a stereospecific stepwise release of 1,2-sn- and 2,3-sn-diacylglycerols by phospholipase C. The exact structure of the original triacylglycerols is reconstituted on the basis of complete analysis of the molecular species of the 1,2-sn- and 2,3-sn-diacylglycerols as the tertiary-butyldimethylsilyl ethers by gas chromatography with mass spectrometry. The validity of the method is demonstrated by analyses of synthetic triacylglycerols of known structure. A practical application is illustrated by determination of the fatty acid distribution in lard.