Fig. 4.

Assessment of method-induced losses of identified lipid species for the different extraction approaches. (A) All identified lipid species, (B) fatty acids, (C) phospholipids, (D) lysophospholipids, (E) ceramides, (F) sphingomyelins, (G) triglycerides, (H) diglycerides, and (I) cholesterol esters. For visualization purposes, levels are expressed as percentage of the highest observed average level for each identified lipid. Statistically significant differences (p < 0.05, Newman-Keuls multiple comparison test; performed on the absolute average levels) were found between all comparisons, unless specified otherwise in the figure