Quantification of phospholipid molecular species by coupled gas chromatography-mass spectrometry of deuterated samples

Abstract

Recent findings suggest that changes in phospholipid molecular species may play a more important role in membrane acclimation than previously believed. The improvements in gas chromatography and gas chromatography-mass spectrometry quantification of phospholipid molecular species by specific deuteration of phospholipase C-derived diacylglycerols using the homogeneous catalyst tris(triphenylphosphine)rhodium (I) chloride are reported here. The reduced diacylglycerols were then converted to the t-butyldimethylsilyl derivatives for gas chromatography. Reduction of unsaturated fatty acyl chains with deuterium improved molecular species quantification in two important ways. First, reduction permitted a sharper gas chromatographic resolution of peaks differing only in their total number of carbon atoms. Second, it eliminated the need for empirically derived correction factors to compensate for the much greater tendency of polyunsaturated fatty acids to fragment during mass spectrometry while preserving, through the number of deuterium atoms incorporated, an accurate record of the degree of unsaturation for each fatty acid.