Large-Scale Lipid Profiling of a Human Serum Lipidome Using a High-Resolution, Accurate-Mass LC/MS/MS Approach

Introduction Lipids play a key role in cell, tissue, and organ physiology. Many diseases, such as cancer and diabetes, involve disruption of their metabolic enzymes and pathways. Identification of unique lipid biomarkers to distinguish healthy humans compared to those with a disease can have an impact on the early detection of diseases and personalized medicine. Because of the complexity of a lipidome, which includes eight major categories of lipids, over 80 major classes, 300 sub-classes, and thousands of lipid species,1 HPLC MS/MS methods are often used to separate many overlapping isomeric or isobaric molecular ions. It is critical that the adapted LC-MS platform offers the capability to separate and identify as many of the isobars and isomers from the biological lipid extracts using both chromatographic separation and the resolution of the MS detector. C30 reversed-phase HPLC columns uniquely offer high shape selectivity, which denotes a chromatographic quality exhibited by certain stationary phases for which enhanced separations of geometric isomers result based on their molecular structure, rather than other physical or chemical differences of the solutes.2 This selectivity provides separation of structurally related isomers and improved lipid isomer separation efficiency compared to C18 columns. The high resolving power offered by the quadrupole Orbitrap mass detector, in combination with accurate-mass capabilities, enables large lipid identification coverage and precise quantitation for complex biological samples.3 Here we report that approximately one thousand lipid molecules from a human serum sample were simultaneously identified and quantified using a newly developed UHPLC Thermo ScientificTM AcclaimTM C30 column (2.1 x 250 mm, 1.9 μm) and a quadrupole Orbitrap high-resolution, accurate-mass (HRAM) MS instrument.