Figure 2.

Mass spectra obtained by MALDI-TOF of Fondaparinux (50 µM) and proportion of forms presenting at least one Na/K exchange prepared in water (blue line) and after saturation with sodium ions by pretreatment on a DOWEX cation-exchange resin converted to Na (orange line); centered between 1000 and 1800 Th. Samples are prepared with a HABA/TMG ½ 80 mg/mL matrix in methanol at a ratio of 0.5/1 µL of matrix/sample on a MALDI Anchorship plate. The spectra were obtained with a laser power of 73% for 100,000 spectra. Asterisks represent Na/K exchanges.