Feasibility study of the fractionation of monoclonal antibody charge variants using a cuboid packed-bed device

Cuboid packed-bed devices have been proposed as efficient alternative to preparative columns. In the current study, we discuss a challenging purification application i.e. separation of monoclonal antibody (mAb) charge variants by ion-exchange chromatography based on subtle charge heterogeneity. Head-to-head experiments were carried out using a cuboid packed-bed device and its equivalent column. Efficiency related metrics such as plate height and peak attributes such as asymmetry and tailing were first compared. Charge variants containing mAb samples were then fractionated. The results obtained showed that the cuboid packed-bed device outperformed the column, both in terms of efficiency and resolution. For instance, at 30 cm/h superficial velocity, the cuboid packed-bed device had 14240 theoretical plates/m as opposed to 4409 theoretical plates/m in the column. Also, at 15 cm/h superficial velocity and 150 mL linear gradient, the resolution between the main peak and the basic peaks were 1.29 and 1.12 respectively for the cuboid packed-bed device and the column. The enhancement in resolution was particularly significant at lower flow rates and when shorter gradients were used. For instance, a 100 mL gradient could be used with the cuboid packed-bed device to achieve resolution comparable to that obtained with the column using 150 mL gradient. Simulations showed that high purity (>94%) and recovery (>95%) of the main mAb peak component could simultaneously be achieved using the cuboid packed-bed device. In this paper we also discuss a new in-situ resin packing method for cuboid packed-bed devices.