, Volume 91, Issue 8, pp 1417-1424
Date: 12 Jun 2014

Quantification of the Molecular Species of TAG and DAG in Lesquerella (Physaria fendleri) Oil by HPLC and MS

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Abstract

Ten diacylglycerols (DAG) and 74 triacylglycerols (TAG) in the seed oil of Physaria fendleri were recently identified by high-performance liquid chromatography (HPLC) and mass spectrometry (MS). These acylglycerols (AG) were quantified by HPLC with evaporative light scattering detector and electrospray ionization mass spectrometry of the lithium adducts of the AG in the HPLC fractions of lesquerella oil. The MS1 ion signal intensities of molecular ions [M + Li]+ in HPLC fractions of an HPLC peak were used to estimate the ratios of AG in the HPLC peak. The ratios of TAG with the same mass in HPLC fractions were estimated by the ratios of the sums of MS2 ion signal intensities from the neutral loss of the three fatty acids [M + Li − FA]+. The ratio of DAG with the same mass were estimated by the ratio of the sums of two MS2 ion signal intensities [M + Li − FA]+ and [FA + Li]+ from the two different FA of a DAG. We have estimated the contents of ten molecular species of DAG and 74 molecular species of TAG in P. fendleri oil using this new method. The content of ten DAG combined was about 1 % and 74 TAG was about 98 %. The contents of DAG in decreasing order were: LsLs (0.25 %), LsLn (0.25 %), LsO (0.24 %), and LsL (0.11 %); and the contents of TAG in decreasing order were: LsLsO (31.3 %), LsLsLn (24.9 %), LsLsL (15.8 %), LsL-OH20:2 (4.3 %), LsO-OH20:2 (2.8 %), and LsLn-OH20:2 (2.5 %).