A Simple TLC-MALDI Method to Monitor Oxidation Products of Phosphatidylcholines and -Ethanolamines

The analysis of lipid-phospholipid oxidation products is of primary importance. Although there are established HPLC and LC-MS techniques, it is shown here for the first time that the combination of matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) and TLC represents a sensitive, fast, and convenient alternative. A mixture of 1-palmitoyl-2-linoleoyl-sn-phosphatidylcholine (PLPC) and -ethanolamine (PLPE) was oxidized under the influence of atmospheric oxygen and characterized by direct positive ion MALDI-TOF MS as well as combined TLC-MALDI. It is shown that much more detailed information - particularly related to the oxidation products of PLPE that have so far been scarcely investigated - can be obtained by TLC-MALDI. However, it is also shown that further methodological improvements are necessary to make this method generally applicable to complex lipid mixtures.