Extracted ion chromatograms of hydrophilic peptides from a trypsin digestion of 2 pmol of tissue factor. Peptides that were not retained on the C8 trap and only weakly retained on the PGC column are region 1 (blue): (A) DVK, (B) SSSSGK, and (C) SSSSGKK. Peptides that were well retained by the PGC column and eluted from the column during the PGC gradient are region 3 (blue): (D) TLVR, (E) STNFK, and (F) DVFGK. One peptide was split between the PGC and C18 columns due to some retention on the C8 trap, region 2 (red): (G) QTYLAR.