It is shown that by a combination of positive and negative FAB mass spectrometry with collision activation using a tandem mass spectrometer diacyl glycerophosphoric acid ester mixtures can be analysed. The following results will be obtained: Molecular masses of the single components, nature of the residue bound to the phosphoric acid (choline, serine etc.), fatty acids present in the single components and (if different) their location at C-1/C-2 as well as a quantitative analysis both of the fatty acids in the mixture and of the various species making up the latter.