Time (min) Mobile phase A (%) Mobile phase B (%) Comment
0.0 80.0 20.0 Isocratic hold to elute positively charged peptide and hydrophilic formulation excipients
4.0 80.0 20.0
4.1 0.0 100.0 Gradient step to elute heterogeneous and lipophilic polysorbates in one single peak
9.0 0.0 100.0
9.1 80.0 20.0 Column re-equilibration
12.0 80.0 20.0
Table 1: Gradient program of the method.