Determination of phosphatidylcholine monohydroperoxides using quadrupole time-of-flight mass spectrometry.

An improved technique for the analysis of phosphatidylcholine (PC) monohydroperoxides was developed using quadrupole time-of-flight (Q-TOF) mass spectrometry with electrospray ionization. Separation was obtained using an HPLC C8 column with a gradient of methanol and 10 mM aqueous ammonium acetate. Monohydroperoxides of palmitoyl-linoleoyl (C16:0/C18:2) PC, stearoyl-linoleoyl (C18:0/C18:2) PC, and oleoyl-linoleoyl (C18:1/C18:2) PC were detected mainly as MH(+) and [M+Na](+) ions in the heart of the intact rat. Using standard synthetic PCOOH (C16:0/C18:2-OOH), the lipid extract component was identified as (C16:0/C18:2-OOH) PC based on the product ions of ESI-MS-MS and, the PCOOH concentration was quantitated using HPLC with chemiluminescence detection. Two epoxyhydroxy derivatives of the three PCs mentioned above were also detected. This is the first report to show the presence of monohydroperoxides and epoxyhydroxy-derivatives of (C16:0/C18:2)PC, (C18:0/C18:2)PC, and (C18:1/C18:2) PC in the rat heart.