Fig. 3

Cation-exchange chromatography of trastuzumab reference material following incubation in a PBS and b in vivo administration. Characterization of IgG charge variants was performed by cation-exchange chromatography using a ProPac WCX-10 analytical cation-exchange column (4 × 250 mm) on an UltiMate3000 HPLC system. The trastuzumab charge-variants profile was significantly altered. Increases in the acidic charge variants were observed with a corresponding decrease in native trastuzumab (main peak) but almost no change to the basic charge variants. Analytical characterization data are summarized in Table 3. mAU milli-absorbance units