In this study, we have developed a large-scale SRM assay targeting human body fluid proteins based on publicly available proteomics data. We first aimed to produce, in a high throughput manner, a peptide reference library. For this purpose, we selected 2,201 targeted peptides representing 1,215 proteins from previous published studies, and in vitro synthesized them as peptide concatamers (QconCATs) using a wheat germ cell-free system.