Molecular species analysis of phosphatidylcholines by reversed-phase HPLC/electrospray ionization MS

A simple and sensitive method for the determination Of molecular species of phosphatidylcholine (1,2-diacyl-sn-glycero-3-phosphocholine, PC) was develoved. Intact PC, which was isolated from soybean and salmon roe, was followed by reversed-phase high-performance liquid chromatography (HPLC) on a highly efficient ODS column (25 cm x 4 mm i.d., 4 mum particle size) using methanol-acetonitrile-triethylamine (90 : 10 : 0.1, v/v/v) as the mobile phase, which gave a clear resolution of individual molecular species containing polyunsaturated fatty acids. Reversed-phase HPLC in conjunction with positive electrospray ionization mass spectrometry (ESI-MS) gave a weak [M - RCO + 2Na](+) ion in addition to prominent pseudomolecular [M + H](+) and [M + Na](+) ions, by which individual molecular species could be identified.