Application of atmospheric pressure chemical ionization liquid chromatography-mass spectrometry in identification of lymph triacylglycerols

Atmospheric pressure chemical ionization liquid chromatography-mass spectro metry was used in the identification of triacylglycerol molecular species i n lymph samples from rats given either a structured lipid or safflower oil. The structured Lipid was MLM-type (M, medium-chain fatty acid; L, long-cha in fatty acid) and manufactured from caprylic acid (8:0) and the oil (saffl ower oil or high-oleic sunflower oil). The triacylglycerol composition of l ymph varied significantly between structured triacylglycerols and safflower oil. Diacylglycerol fragment ions were found for all triacylglycerols and we could also observe the ammonium adduct molecular ion [M+NH4](+) for all the triacylglycerols at the selected conditions. Protonated molecular ions were formed from triacylglycerols containing unsaturated fatty acids, and f atty acid fragment ions were also observed in the case of strong fragmentat ion. The lymph triacylglycerols were identified from their ammonium adduct molecular ions and diacylglycerol fragment ions. In addition to the intact MLM-type structured triacylglycerols, the MLL- and LLL-type triacylglycerol s were also identified. The absorption pathway of MLM-type structured triac ylglycerols is most likely the same as that of conventional long-chain tria cylglycerols, i.e. they were hydrolyzed into 2-monoacylglycerol and medium- chain fatty acids, which were then used for resynthesis of triacylglycerols . The present study thereby also demonstrates the possibility to study the absorption pathway of triacylglycerol via identification of triacylglycerol species in biological samples. (C) 2000 Elsevier Science B.V. All rights r eserved.