Human blood products (plasma and serum) provide a gateway to the study of endogenous and exogenous substrate metabolism, including microbial co-metabolism, as influenced through the expression of human and microbial genetics, changes in nutrition, exposure to environmental factors, infection and disease, and other stimuli . Both plasma and serum are commonly studied for the discovery of diagnostic and prognostic metabolic biomarkers which can be translated into clinical practice or used in the development of therapeutics. The chemical compositions of plasma and serum are complex, ranging from volatile transient signaling molecules (e.g. nitric oxide), small polar metabolites (e.g. organic acids), larger and more hydrophobic molecules (e.g. sterols, steroids, bile acids, drug metabolites), complex and neutral lipids, peptides and larger macromolecules (e.g. protein and lipoprotein species). This broad chemical expanse, together with the great physiological range of blood metabolites , poses an analytical challenge for researchers aiming to construct a complete image of the metabolome, as no single technology or profiling method is truly comprehensive .