Joint MS-based platforms for comprehensive comparison of rat plasma and serum metabolic profiling

Metabolomics is a rapidly growing field in the comprehensive understanding of cellular and organism-specific responses associated with perturbations induced by medicines, chemicals and environment. Blood matrices are frequently used in clinical and biological studies. In this study, we compared metabolic profiling between rat plasma and serum using complementary platforms of gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-quadruple time-of-flight-mass spectrometry (LC-QTOF-MS). The sample types that were tested included plasma prepared with K2 EDTA and serum collected using venous blood collection protocols. The results of peak area variation for each detected metabolite/feature in the quality control samples showed a good reproducibility in LC-QTOF-MS and better reproducibility in GC-MS. In GC-MS analysis: (a) 25.8% of the defined metabolites differed serum from plasma profiling (t-test, p < 0.05); and (b) serum possessed higher sensitivity than plasma for its generally higher peak intensity in the metabolic profiling. In LC-QTOF-MS analysis, 13 (in positive ion mode) and seven (in negative ion mode) important metabolites were identified as mainly contributing to the separation between serum and plasma.