The glycerol backbone of triacylglycerols (TAGs) can have different acyl side chains occupying two or more of the three available positions, which gives rise to regioisomerism. There is a major interest in the quantitative determination of the regioisomers of dietary TAGs, because these may have different bioavailability.1 This analysis can be accomplished using chromatographic separation of the isomers, but in certain cases it can be performed without chromatography using tandem mass spectrometry, provided the fragmentation is position sensitive. In these cases the analysis of regioisomers is both easier and faster.