MALDI-TOF MS in lipidomics

So far, matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) seemed to be nearly a synonym for protein analysis. However, there is growing evidence that this technique is also an useful tool in lipid analysis and lipidomics because of its fast, simple and convenient performance allowing to record mass spectra of cells, crude tissue or body fluid extracts or even intact tissue slices in a few minutes. On the negative side, however, the reproducibility of MALDI-TOF mass spectra depends significantly on the homogeneity of the co-crystals between matrix and analyte and different lipid classes are detected with different sensitivities. This is especially important because lipids with quaternary ammonia groups (e.g., GPCho) may prevent the detection of other lipid classes (e.g., GPEtn). This review starts with a short overview on traditional methods of lipid analysis with the focus on mass spectrometric methods and compares MALDI-TOF MS with other important ionization techniques. Afterwards, some landmarks in the development of MALDI-TOF MS will be introduced and some important examples in the field of tissue and body fluid lipid analysis will be discussed. This review ends with a short outlook and summary focusing on the advantages and drawbacks of MALDI-TOF MS in lipidomics.