In-source fragmentation (ISF) is a well-known detrimental effect occurring mainly via collisions with the neutral gas in the RF ion guides of the mass spectrometer. Extent of the ISF is also dependent on the amount of internal energy received during the ionization process . It may lead to false positives in lipid annotation and identification by a wrong choice of fragments of high abundant species as independent entities. The improvements observed in the µF/mnESI method can directly be ascribed to the alteration of the ionization mode, from pneumatically-assisted ESI to NSI, as S-lens radiofrequency level was set to the same value (70%) in both methods. This setting was reported earlier as a major factor contributing to ISF on Orbitraps in lipidomic applications . The influence of ion transfer tube temperature between both approaches (µF/mnESI = 300°C; AF/ESI = 340°C) may be considered a rather minor factor, due to the similar extent of ISF between TG, DG and PE classes for both setups.