Tandem MS analyses were performed on every ion on the final list as described previously
(Vinayavekhin et al., 2015). However, some parameters were modified slightly in this study to obtain
the optimal spectral data. Active exclusion was set to be released after
0.30 min. Collision energies were set at 30 V for m/z 500.00, 45 V for m/z 1000.00 and 60 V for m/z
2000.00 with automatic inter- polation from those of the two closest m/z values when the iso- lated
ions did not have the exact value. Data were collected using a mass range of 50–1500 Da from lipid
extracts (50 ml) or chemical standards (500–625 pmol).