Figure 4.

Platform-specific, log-transformed, average metabolite levels in control samples for vendors reporting absolute units; each point represents mean ± SEM for 11 control samples in total: 9 control samples from 6 individuals (with 3 technical replicates), and 2 NIST pooled reference plasma samples. Each panel depicts the range of covered metabolites, across all assays, for an exemplar metabolite class: (A) amino acids, (B) fatty acids, (C) lysophosphatidylcholines (LPC), (D) hydroxy acids, (E) ceramides, and (F) triglycerides. Depicted data are from the second sample shipment. NIST = concentrations reported in the National Institute of Standards and Technology (NIST) SRM 1950 Certificate of Analysis (COA, revised June 2020).