Identification of Phospholipid Molecular Species Using Neutral Loss Survey and MS3 Analysis

To elucidate the functions of phospholipids, it is important to conduct analysis not only of their classes and sub-classes, but of their molecular species as well. At Shimadzu, we found that electrospray ionization (ESI) MS3 analysis is effective for more detailed and accurate annotation of each molecular species. We established a system for phospholipid molecular species analysis using a neutral loss (NL) survey experiment of the head-group-related mass values, and succeeding MS3 analyses by selecting the resulting product ions as precursor ions for MS3 analyses (Fig. 1). Using this new method, 34 different molecular species of phosphatidylcholine (PC) were identified even without pre-separation by LC. We then turned our attention to establishing a system for analysis of phosphatidylethanolamine (PE) and phosphatidylserine (PS) in a mixture of lipids.