Toward minimally invasive metabolomics: GC-MS metabolic fingerprints of dried blood microsamples in comparison to plasma.

Global metabolic profiles of dried blood microsamples (BμS) were studied in comparison to conventional plasma and blood samples using Gas Chromatography-Mass Spectrometry (GC-MS). Venous blood from 10 healthy, overnight-fasted individuals was collected and used to produce dried microsamples on Whatman cards, Capitainer and Mitra devices. In parallel paired plasma samples were collected. The metabolite extraction protocol was optimized and methanol was selected as the extraction solvent. Twenty µL of the venous BμS and plasma were analyzed using the Fiehn GC-MS protocol which includes methoximation and trimethylsilylation derivatization steps. In an additional study, three paired finger capillary BµS (Mitra), liquid venous blood, and plasma metabolic profiles were evaluated. BµS devices, mainly the Mitra, provided equivalent or greater information than plasma, considering it had the highest mean abundance of features and most annotated metabolites (37) with highest abundance. Additionally, in the last study, 14 metabolites had statistically higher abundance in the capillary blood Mitra BμS compared to liquid venous blood and plasma. Overall, the results suggest that BμS is a viable alternative for untargeted blood metabolomics, providing comparable information. Since the different BμS devices capture different metabolic profiles, the choice of device for a research study should be carefully considered depending on one's goals.