Quantitative and Wide-Ranging Profiling of Phospholipids in Human Plasma by Two-dimensional Liquid Chromatography/Mass Spectrometry

Normal phase or reverse-phase liquid chromatography has been used in phospholipidomics for lipid separation prior to mass spectrometry analysis However, separation using a single separation mode is often inadequate, as high-abundance phospholipids can mask large numbers of low abundance lipids of interest. In order to detect and quantify low-abundance phospholipids, we present a novel two-dimensional (2D) approach for sensitive and quantitative global analysis of phospholipids The methodology monitors individual glycerolipids and phospholipids through the use of a new quantitative normal-phase, solid phase extraction procedure, followed by molecular char acterization and relative quantification using an ion trap Orbitrap equipped with a reverse-phase liquid chromato graph, with data processing by MS++ software The CV (%) of the peak area of each lipid standard was less than 15% with this extraction method When the method was applied to a liver sample, we could detect more phosphatidylsenne (PS) compared to the previous method Finally, our developed method was applied to Alzheuner's disease (AD) plasma samples Several hundred peaks were detected from a 60 mu L plasma sample A partial least squares discriminant analysis (PLS DA) plot using peak area ratio gave a unique group of PLS scores which could distinguish plasma samples of Alzheimer's disease (AD) patients from those of age-matched healthy controls