Principal component analysis (PCA) of the phospholipid profile in plasma and whole blood samples.

In the score plot (left panel) each dot represents one analyzed sample and similar phospholipid profiles cluster together. A clear separation between plasma and blood samples is observed. In both types of specimen, the three disease categories are similarly positioned to each other, indicating a similar shift in the phospholipid profile in both sample types. Samples are color-coded by sample type and disease classification. The principal component loadings plot (right panel) visualizes the contribution of each phospholipid species to the total variance in the phospholipid profile, to which phospholipid species with the largest distance from the origin contributed the most. Each dot represents a different phospholipid species and the same color is used for the same phospholipid class. Dot sizes are proportional to the MS signal intensity of the phospholipid species. PrComp, principal component; PC, phosphatidylcholine; SM, sphingomyelin; PI, phosphatidylinositol.