Detection of individual phospholipids in lipid mixtures by matrix-assistedlaser desorption/ionization time-of-flight mass spectrometry: Phosphatidylcholine prevents the detection of further species

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is an established tool for the analysis of proteins, whereas it gained by far less interest in the field of lipid analysis. This method works well with phospholipids as well as organic cell extracts and provides high sensitivity and reproducibility. The aim of the present paper is to e xtend our previous studies to the analysis of lysophospholipids and phospho lipid mixtures. To study the suitability of MALDI-TOF mass spectrometry for the analysis of lysophospholipids, different phospholipids like phosphatid ylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidic acid, and phosphatidylinositol as well as their mixtures were digested with phos pholipase A(2). Positive and negative ion mass spectra of all phospholipids before and after digestion were recorded. In all these cases, the molecula r ions of the expected digestion products could be detected and only a very small extent of further fragmentation was observed. On the other hand, spe ctra of phospholipid mixtures containing phosphatidylcholine were strongly dominated by phosphatidylcholine and lysophosphatidylcholine signals, which prevented the detection of further phospholipids even if those lipids were present in comparable amounts. This is of paramount interest for the analy sis of tissue and cell extracts. (C) 2001 Academic Press.