The lipids are annotated according to head group, total number of carbons in the chains, and total number of double bonds in the chains. For example, PC(16:1/20:5) becomes PC(36:6).The lipid analysis in the p180, p400 HR and MxP Quant 500 kits does not provide specific information regarding either the positions or chain lengths of the fatty acid residues linked to each lipid’s backbone. Consequently, the reported signal is a sum of several isobaric/isomeric lipids. For more detailed information please refer to the list of isobaric lipids for each kit: p180, p400 HR, MxP Quant 500 (available on request)