Figure 5: Comparison of electropherograms of rituximab obtained by CGE using sieving matrix (a, d), CZE using EACA-TETA-HPMC additives in the buffer (b,) and CZE using phosphate buffer (c,), (b,). Conditions: (a, d): CGE separations, Beckman Coulter SDS-MW gel buffer sieving matrix, electrokinetic (short-end) injection: +7.5 kV for 50 sec, capillary: 30 cm x 50 μm i.d., U= +15 kV, λ= 200 nm. (b,): CZE separation, 800 mM EACA, 2 mM TETA, 0.05% HPMC, pH= 5.2, capillary: 30 cm x 50 μm i.d., 150 mbar s, +15 kV, λ= 200 nm. (c,): CZE separation. The sample was stressed by 55°C for 15 h, 100 mM phosphate buffer pH 9.3, capillary: 64.5 cm x 50 μm i.d., 60 mbar s, +10 kV, λ= 200 nm (d,): CGE separation. The sample was stressed by 55°C for 15 h, 100 mM phosphate buffer pH 9. 1 mg/ml pharmaceutical product MabThera samples were prepared by dilution with Beckman Coulter SDS-MW sample buffer (a, d,), water (b,) and with the buffer solution (c).