Molecular species analysis of 1,3-diacylglycerols in edible oils by HPLC/ESI-MS

Abstract

A facile method for the determination of molecular species of regioisomeric 1,3-diacylglycerols (1,3-DG) in edible oils was developed. For this purpose, a DG-rich cooking oil (Econa), which can reduce fat deposits, was treated with 3,5-dinitrophenyl isocyanate in dry toluene under the presence of pyridine at room temperature. The resulting 1,3-DG 3,5-dinitrophenylurethanes were then separated by preparative thin-layer chromatography on silicic acid. The 1,3-DG was followed by reversed-phase HPLC on a C30 column (25 cm x 4.6 mm i.d.), which gave a clear resolution of the individual molecular species. Reversed-phase HPLC in conjunction with negative electrospray ionization MS (ESI-MS) showed a prominent [M-H]- ion, by which individual molecular species could be identified.