Prediction of pH Gradient Elution of Ion Exchange Chromatography for Antibody Charge Variants Separation Based on Salt Gradient Elution Experiments

> 0.99). Then, the well-calibrated pH-dependent SMA model showed a satisfactory capability for predicting the pH gradient elution behaviors with an RMSE of 16.18%. Moreover, the model was used for process optimization under different elution modes, including salt gradient, pH gradient, and salt-pH dual gradient, improving the yield from 70.07% to 74.91%. The optimized linear pH gradient elution was verified by experiment (RMSE = 8.30%). Finally, a methodological framework for utilizing the simplified pH-dependent SMA model developed in this work was summarized to explore its practical applications. The two-step calibration strategy proposed significantly alleviates the workload for the pH-dependent IEC modeling. The model-based process optimization effectively enables faster pH-dependent process development with minimal experiments.