“…The proportions of sphingolipids (25%) and phospholipids (53%) and the spectra of sphingolipids (sulfatides, sphingomyelins, and lactosylceramides) and phospholipids (phosphatidylserines, phosphatidylinositols, phosphatidylethanolamines, plasmalogens, and phosphatidylglycerols) identified in WM are consistent with previous reports in which MALDI-TOF IMS was performed in the negative ionization mode (Nunez et al, 2016; O'Brien & Sampson, 1965; Yalcin et al, 2015). In contrast, other abundant lipids in myelin, including cholesterol, phosphatidylcholine, and sphingomyelin, which form protonated ([M+H] + ), sodiated ([M+Na] + ), or potassiated ([M+K] + ) adducts, were not detected because they are preferentially accessible via positive ionization mode mass spectrometry (Berry et al, 2011; Löhmann, Schachmann, Dandekar, Villmann, & Becker, 2010).…”