Figure 1

Schematics of peptide extraction and purification strategy Urine samples were passed through a centrifugal filtration column to separate intact (larger MW proteins) from native peptides (smaller MW peptides). The peptide fraction was subjected to solid phase extraction (SPE) and modified SPE (mSPE) methods described in the Methods section. The resulting peptides were analyzed by LC-MS and identified for comparison of robustness of the two isolation and purification methods.