Total ion current profiles across the chromatographic peptide separation for digests of undepleted (A, whole) and depleted (B) plasma from experiments C and D, respectively. Total ion current profiles across the chromatographic peptide separation for digests of undepleted (A, whole) and depleted (B) plasma from experiments C and D, respectively. Pie charts represent the protein composition of the samples: whole plasma contains >50% albumin (stippled region), whereas the proteins remaining after MARS depletion include fibrinogen, α2-macroglobulin, complement C3, and all other lower abundance proteins (four remaining pie slices ordered clockwise from 12 o’clock), showing the proportion of protein removed by depletion (white segments in B). The major peptide in A at 20.3 min is derived from albumin (whose abundance is shown by the black pie segment with white dots). cps, counts per second. Leigh Anderson, and Christie L. Hunter Mol Cell Proteomics 2006;5:573-588 © 2006 The American Society for Biochemistry and Molecular Biology