Combined application of TLC and matrix-assisted laser desorption and ionisation time-of-flight mass spectrometry (MALDI-TOF MS) to phospholipid analysis of brain

Although matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) was so far scarcely used in phospholipid (PL) analysis, this technique has a great potential: It is fast and reliable, spectra can be quantified and fragmentation of analytes is negligible. However, individual PL are defected in mixtures with different sensitivities: PL with quaternary ammonia groups are most sensitively detectable while further PL may be suppressed. Therefore, an initial separation of the PL mixture into the individual PL classes is required to be able to detect all PL. It is the aim of this paper to show on the hand of organic extracts of pig brain as a typical lipid mixture that MALDI-TOF MS in combination with TLC enables the detection of all relevant brain PL. However, it will also be shown that there are problems with the analysis of alkenyl-acyl compounds (plasmalogens) since they decompose in the presence of traces of acids as well as the acidic groups on the TLC plate under formation of the corresponding lysophospholipids.