Ion exchange resins are key raw materials in biopharmaceutical manufacturing processes, and variability in ligand density has the potential to compromise process robustness if not controlled within appropriate ranges. In this study, yield and impurity clearance were evaluated for several preparative cation exchange chromatography steps using SP Sepharose™ Fast Flow resins at the high, low, and center of the commercial ligand density specification range. This was accomplished using a design of experiments (DoE) approach coupled to high-throughput screening in 96-well plate format, as well as column chromatography experiments with gradient elution. Results of the DoE study indicated that ligand density variation within the commercial specification range of SP Sepharose™ Fast Flow had no effect on yield, HCP clearance, aggregate clearance, or distribution of charge variants. However, results from the column experiments showed that ligand density has the potential to influence protein elution profiles which can lead to small changes in impurity clearance in some cases.
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