Intact phospholipids in the digestive system of Antarctic krill measured with LC-HRMS

Antarctic krill, Euphausia superba, is a key species in the Southern Ocean with an immense biomass. Ongoing climate change affects their food availability, habitat and survivability. Therefore, markers documenting changes in this species are important to monitor and discover future issues, also because krill-derived products are manufactured for human consumption. While many studies focus on the analysis of the fatty acid composition after the hydrolysis of lipids, the composition of intact lipids has rarely been evaluated.Krill was caught with a continuous krill pumping system in May of 2021 in the Bransfield Strait and in January and March of 2022 at the South Orkney Islands aboard the commercial krill fishing vessel Antarctic Endurance. The stomach, digestive gland and hind gut were dissected and analysed individually. Samples were extracted with an optimized Bligh&Dyer protocol.Intact phospholipids from the digestive system of Antarctic krill, Euphausia superba, were measured with liquid chromatography - high-resolution mass spectrometry on an Orbitrap mass spectrometer. Identification of intact phospholipids was based on characteristic fragments of the head group in MS2 experiments in positive electrospray ionization mode, while the fatty acid compositions of intact phospholipids were determined by characteristic fragments occurring during MS2 measurements using negative electrospray ionization.