Separation of phospholipid classes by HILIC-UPLC. Multiplex analysis of purified phospholipids (A) and human serum (B) using PIS and NLS in positive and negative ion mode. Top panel shows HILIC chromatographic separation and mass spectrometric detection of phospholipid/sphingolipid classes by either precursor m/z 184, 241, 264 or neutral loss m/z 141, 172, 185, 98. Middle panel shows NLS m/z 141 in positive ion mode specific for PE and LPE. Bottom panel shows summed mass spectral (MS) data from NLS m/z 141 in positive ion mode shown indicated in gray above. Inset: magnification from m/z 762 to m/z 774.