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. Author manuscript; available in PMC: 2010 Apr 18.
Published in final edited form as: Nat Biotechnol. 2009 Jun 28;27(7):633–641. doi: 10.1038/nbt.1546

Figure 1.

Figure 1

Sample preparation workflow for studies I, II and III. (a) Study I. Pooled, digested plasma was spiked with 12C and 13C/15N peptides to generate a nine-point standard curve. (b) Study II. An equimolar mixture of the seven target proteins was digested separately and spiked with an equimolar mixture of IS peptides. The digest of target proteins plus IS peptides was added to pooled, digested plasma. A nine-point standard curve was prepared with pooled, digested plasma spiked with an equimolar mixture of IS peptides as the diluent. Study I and study II samples were prepared centrally at NIST. (c) Study III. Undiluted plasma was spiked with an equimolar mixture of the target proteins, then diluted with plasma to generate a nine-point standard curve. Three aliquots of these samples (prepared at NIST) were then shipped to the eight participating sites where reduction, alkylation, digestion and desalting were carried out before SID-MRM-MS analysis. IS, internal standard; SPE, solid phase extraction.