How do you design and optimize continuous chromatography operations?

Continuous chromatography designs include: simulated moving bed (SMB) for binary separations, multi-column countercurrent solvent gradient (MCSGP) for center-cut separations, and periodic counter-current (PCC) for capture chromatography. Design considerations: number of columns (typically 3-8), column sizing (smaller than batch equivalent), zone configuration and timing, interconnection and valve systems, flow rates and switching times, and resin selection (fast kinetics critical). Optimization: productivity vs resin utilization trade-offs, buffer consumption minimization, and robustness to feed variability. Process control: real-time UV monitoring, automated switching, and disturbance handling. Scale-up: maintaining residence times and mass transfer characteristics. Validation challenges include lot definition, in-process pooling decisions, and steady-state qualification. Continuous chromatography typically achieves 3-5x higher productivity than batch.